Patent Application
20140111595
The present application generally relates to printing systems. In particular, the present application relates to printing systems, including multicolor direct thermal printers, and a dual time-constant heat sink for said printing systems.
Printers have long suffered from portability problems, with the majority of printers primarily for desktop use and typically weighing dozens of pounds. Even as computing devices have moved towards more lightweight systems, such as smart phones, laptop computers, notebook and sub-notebook computers, and tablet computers, printing from these devices frequently requires connecting, either wirelessly or physically, to a desktop printer. As a result, use cases for these printers are limited.
Manufacturers have attempted to extend portability to printers, though current implementations suffer from various defects. For example, continuous-roll black and white direct thermal printers, such as those used in portable credit card readers and point-of-sale terminals utilize a thermal printing head that applies heat to a dye impregnated in a printing medium, activating the dye or color-forming chemical to create black and/or gray pixels. The resulting prints are frequently low-resolution and relatively unstable, fading and/or darkening over time, and as a result are useful only for temporary prints, such as receipts.
Conversely, continuous-roll thermal wax transfer printers or dye-diffusion thermal transfer printers use separate donor and receiver materials, allowing color-on-color printing with very high stability. Prints typically do not fade unless damaged through friction. However, color choices are fixed (e.g. black lettering on a white medium, or red lettering on a yellow medium), and switching between colors requires switching cassettes or cartridges. As a result, multicolor images or labels cannot be created.
Multicolor thermal printers produce full-color, stable prints, and may be relatively small. However, in typical implementations, the printing medium is delivered in predetermined dimensions, such as 3 inches by 5 inches, or 5 inches by 7 inches, limiting potential uses compared to a continuous-roll printer. Other printing methods such as ink jet printers and laser printers are typically larger and heavier, making them unavailable for portable printing, and suffer from problems such as ink cartridges drying out before the user has consumed the maximum number of prints possible.
Furthermore, as typically befits their roles as printers for other computing devices, most printers lack user interfaces for editing images or text to be printed. Conversely, the few that include keypads such as handheld label printers, typically allow only alphanumeric entry, and have formatting constraints such as fixed sizes, fonts, or text orientations.
The present application is directed to portable printers, including printers with user interfaces for direct what-you-see-is-what-you-get (WYSIWYG) editing and printers that provide network printing capability for other computing devices, such as smart phones, tablet computers, or other devices. In some embodiments, the printers may be multicolor direct thermal printers, and/or may utilize continuous-roll cassettes of printing media, allowing printing of labels or images of variable length, and in other embodiments, other printing technologies may be employed. In embodiments utilizing multicolor direct thermal printers, the printing medium may comprise a substrate and one or more color-forming layers, each impregnated with a temperature-activated color forming dye having various activation times and temperatures. The printer may include a pulsing thermal print head with pulse amplitudes and frequencies controllable to selectively activate one or more of the color-forming layers of the printing medium to generate a pixel of any color.
The printers may include one or more cutters capable of cutting fully through a printing medium to perform a full cut, or capable of cutting only partway through a printing medium, such as through a medium substrate and adhesive layer to a backing liner, to perform a partial cut or “kiss cut”. These latter cuts may be used to make labels that may be easily peeled from a backing by a user. The printers may execute printing and image placement methods to print to or beyond the edges of the printing medium to perform “full-bleed” printing, or printing whereby the resulting image fills the printing medium without leaving an un-printed border.
The printers may incorporate either a manually-triggered or automatic media ejection mechanism and/or cutting system. Manual triggering may be via a swipe gesture by a user via a touch-sensitive input device. To reduce friction and load on the media that may cause stuttering or the appearance of visual bands on printed media, the media ejection mechanism may incorporate a non-circular roller that does not interfere with the media during printing, and rotates into position for ejection of the media after cutting.
To print on various widths of media, the printers may utilize cassettes or cartridges of different widths. Each cassette may include a spool of printing medium, and to ensure the printing medium exits the cassette in a uniform fashion, may dynamically vary the position of the axis of the spool of printing medium. To prevent dust or foreign bodies from interfering with printing, the cassette may include a cleaning material along a media exit slot or opening. The printer may utilize a variable pressure print head such that constant pressure may be applied to the printing medium regardless of width of the medium.
To ensure proper alignment of printing and to allow printing of full-bleed images across the width of the printing medium, the printing medium may include an alignment pattern. A sensor of the printer may detect the alignment pattern during printing and dynamically adjust output of the print heads to remove lateral displacement errors, resulting in an aligned image.
As discussed above, the printer may include a user interface for editing and printing images, or may directly connect wirelessly to a second device providing a user interface such as a smart phone or tablet computer. The printer may also be able to join an existing wireless network to allow printing from the second device or from other devices connected to the network. In some embodiments in which the printer does not include a user interface, the printer may utilize a wireless interface to provide an access point. The second device may connect to the access point to provide images for printing, or may provide configuration commands to cause the printer to join the existing wireless network, allowing custom network configurations of the printer without utilizing cumbersome on-board controls.
The user interface provided by the printer or by the second device may allow WYSIWYG editing in an intuitive manner, allowing users to drag elements dynamically around a representation of the printed label, add text or images, dynamically adjust colors, sizes, and borders, and dynamically adjust the length of a label or image to be printed. The user interface may further provide communication with an online database or store of elements, and may provide functionality for purchasing elements, themes, images, templates, or other articles for generating images.
In one aspect, the present disclosure is directed to a variable pressure print head for a printer. The variable pressure print head includes a print head for printing on a print medium, the print head having a bow perpendicular to the plane of the print medium. The variable pressure print head also includes a platen roller for supporting the print medium. The variable pressure print head further includes a variable print head load mechanism for positioning the print head and platen roller, wherein the print head and platen roller position are automatically varied responsive to a width of the print medium.
In some embodiments of the variable pressure print head, positioning of the print head and platen roller is varied to maintain a constant pressure on the print medium regardless of width of the print medium. In a further embodiment of the variable pressure print head, the constant pressure comprises a constant pressure per unit width of the print medium. In one embodiment of the variable pressure print head, the platen roller is deflected responsive to pressure from the print head transmitted via the print medium. In a further embodiment, the platen roller is deflected to have a curvature parallel to the bow of the print head.
In some embodiments of the variable pressure print head, the variable print head load mechanism further comprises a head pressure controller configured for receiving an identification of a width of the print medium of a predetermined plurality of widths; and selecting a position for the print head and platen roller from a corresponding plurality of predetermined positions, responsive to the identified width. In other embodiments, the variable print head load mechanism further comprises a screw, fixed to a frame of the variable print head load mechanism, in contact with the print head and rotatable to vary the bow of the print head. In still other embodiments, the variable print head load mechanism further comprises a lever supporting an axis of the platen roller, said lever moved to vary the position of the platen roller. In a further embodiment, the lever is fixed at a fulcrum at a first position, and wherein the axis of the platen roller is supported by the lever at a second position displaced from the first position. In another further embodiment, the print head load mechanism includes a motor attached to the lever, controlled by the variable print head load mechanism to move said lever.
In another aspect, the present disclosure is directed to a method for providing variable pressure to a print head. The method includes identifying, by a head pressure controller of a printer, a width of a print medium. The method also includes determining a print head and platen roller position, responsive to the width of the print medium. The method further includes adjusting positions of a print head and a platen roller responsive to the determined positions.
In one embodiment of the method, determining the print head and platen roller position further comprises determining positions of the print head and platen roller to provide a constant pressure on the print medium when the print medium is between the print head and platen roller, regardless of width of the print medium. In a further embodiment, the constant pressure comprises a constant pressure per unit width of the print medium.
In some embodiments of the method, the print head has a bow perpendicular to the plane of the print medium, and adjusting positions of the print head and platen roller further includes positioning the platen roller to be deflected responsive to pressure from the print head transmitted via the print medium. In a further embodiment, the platen roller is deflected to have a curvature parallel to the bow of the print head.
In some embodiments of the method, the head pressure controller receives an identification of the width of the print medium of a predetermined plurality of widths, and determining the print head and platen roller position comprises selecting a position for the print head and platen roller from a corresponding plurality of predetermined positions, responsive to the identified width.
In one embodiment, the method includes reading a parameter stored on a storage medium attached to a print medium cassette to identify a width of the media. In another embodiment, adjusting positions of the print head and platen roller further includes moving a lever supporting an axis of the platen roller. In a further embodiment, the lever is fixed at a fulcrum at a first position, and the axis of the platen roller is supported by the lever at a second position displaced from the first position. In another further embodiment, the method includes controlling a motor attached to the lever.
In another aspect, the present disclosure is directed to a method for full bleed printing. The method includes cutting, by a cutter of a printer, a first kiss cut in a continuous printing medium at a first position displaced from an end of the continuous printing medium. The method also includes positioning, by a medium advancement mechanism of the printer, the continuous printing medium with a print head of the printer at a print start location between the first position and the end of the continuous printing medium. The method further includes printing, by the print head, a first image on a continuous printing medium to a print end location. The method also includes cutting, by the cutter, a second cut in the continuous printing medium at a second position between the first position and the print end location. A portion of the continuous printing medium between the first kiss cut and the second cut comprises a full bleed print.
In one embodiment, the method includes cutting the first kiss cut by cutting through the continuous printing medium to an adhesive backing. In another embodiment, the cutter is positioned beyond the print head in the direction of travel of the continuous printing medium by a first distance. In a further embodiment, the method includes positioning the continuous printing medium with the print head of the printer at the print start location by retracting the continuous printing medium by an amount greater than the first distance. In another further embodiment, the method includes cutting the second cut in the continuous printing medium at the second position by advancing the continuous printing medium, after printing the first image, by an amount less than the first distance.
In some embodiments of the method, the second cut is a full cut. In other embodiments of the method, the second cut is a kiss cut. In a further embodiment, the method includes cutting, by the cutter, a third kiss cut in the continuous printing medium at a third position. The method also includes positioning, by the medium advancement mechanism of the printer, the continuous printing medium with the print head of the printer at a second print start location between the second position and the third position. The method further includes printing, by the print head, a second image on the continuous printing medium to a second print end location. The method also includes cutting, by the cutter, a fourth cut in the continuous printing medium at a fourth position between the third position and the second print end location. The portion of the continuous printing medium between the third kiss cut and the fourth cut comprises a second full bleed print. In a further embodiment, cutter is positioned beyond the print head in the direction of travel of the continuous printing medium by a first distance, and cutting the third kiss cut in the continuous printing medium comprises advancing the continuous printing medium by an amount greater than the first distance. In another further embodiment, the fourth cut comprises a full cut.
In yet another aspect, the present disclosure is directed to an apparatus for full bleed printing. The apparatus includes a print head of a printer for printing a first image on a continuous printing medium. The apparatus also includes a cutter of the printer configured for cutting a first kiss cut in the continuous printing medium. The apparatus further includes a medium advancement mechanism of the printer configured for: positioning the continuous printing medium with the cutter at a first position displaced from an end of the continuous printing medium; subsequent to the cutter cutting the kiss cut at the first position, repositioning the continuous printing medium with the print head at a print start location between the first position and the end of the continuous printing medium; and subsequent to the print head printing the first image on the continuous printing medium from the print start location to a print end location, repositioning the continuous printing medium with the cutter at a second position between the first position and the print end location. The cutter is further configured for cutting a second cut in the continuous printing medium at the second position, such that a portion of the continuous printing medium between the first kiss cut and the second cut comprises a full bleed print.
In one embodiment of the apparatus, the cutter of the printer is configured for cutting the first kiss cut by cutting through the continuous printing medium to an adhesive backing. In another embodiment, the cutter is positioned beyond the print head in the direction of travel of the continuous printing medium by a first distance. In a further embodiment, the medium advancement mechanism is further configured for positioning the continuous printing medium with the print head of the printer at the print start location by retracting the continuous printing medium by an amount greater than the first distance. In another further embodiment, the medium advancement mechanism is further configured for repositioning the continuous printing mechanism with the cutter at the second position by advancing the continuous printing medium by an amount less than the first distance.
In some embodiments of the apparatus, the second cut is a full cut. In other embodiments, the second cut is a kiss cut. In a further embodiment, the medium advancement mechanism of the printer is further configured for: positioning the continuous printing medium with the cutter at a third position for the cutter to execute a third kiss cut; subsequently repositioning the continuous printing medium with the print head of the printer at a second print start location between the second position and the third position; and subsequent to the print head printing a second image on the continuous printing medium to a second print end location, repositioning the continuous printing medium with the cutter at a fourth position between the third position and the second print end location for the cutter to execute a fourth cut. The portion of the continuous printing medium between the third kiss cut and the fourth cut comprises a second full bleed print. In a further embodiment, the cutter is positioned beyond the print head in the direction of travel of the continuous printing medium by a first distance, and positioning the continuous printing medium with the cutter at the third position includes advancing the continuous printing medium by an amount greater than the first distance. In another further embodiment, the fourth cut comprises a full cut.
In yet another aspect, the present disclosure is directed to a dual time-constant heat sink for a thermal printer. The dual time-constant heat sink includes a print head heat sink, in contact with a print head of a thermal printer, the print head heat sink having a first thermal time constant. The dual time-constant heat sink also includes an insulator in contact with the print head heat sink; and a thermal reservoir, in contact with the insulator, the thermal reservoir having a second thermal time constant, the second time constant longer than the first thermal time constant.
In one embodiment of the dual time-constant heat sink, the print head heat sink has a high thermal conductivity and a small volume, or a low heat capacity. In a further embodiment, the print head heat sink has a thermal conductivity of at least 50 W/mK.
In another embodiment of the dual time-constant heat sink, the thermal reservoir has a high thermal conductivity and a large volume and/or large surface area, or a high heat capacity. In a further embodiment, the thermal reservoir has a thermal conductivity of at least 50 W/mK.
In still another embodiment of the dual time-constant heat sink, the insulator has a low thermal conductivity. In a further embodiment, the insulator has a thermal conductivity of less than 1 W/mK. In a still further embodiment, the thermal conductivity of the insulator is at least two orders of magnitude lower than the thermal conductivity of the print head heat sink or the thermal reservoir. In another further embodiment, the thermal conductivity of the insulator is at least three orders of magnitude lower than the thermal conductivity of the print head heat sink or the thermal reservoir.
In some embodiments of the dual time-constant heat sink, the insulator comprises a controllable heat pipe, and heat flow from the print head heat sink to the thermal reservoir is reduced during preheating of the print head of the thermal printer. In other embodiments, the insulator comprises an air gap. In a further embodiment, after preheating the print head of the thermal printer, the air gap is closed to place the print head heat sink in contact with the thermal reservoir. In a still further embodiment, the dual time-constant heat sink includes a lever connected to the thermal reservoir to move the thermal reservoir to contact the print head heat sink after preheating the print head. In another still further embodiment, the print head heat sink further includes a bimetallic strip configured to contact the thermal reservoir upon reaching a predetermined temperature. In other embodiments, the dual time-constant heat sink has no moving parts.
In yet another aspect, the present disclosure is directed to a method for controlling temperature of a print head of a thermal printer via a dual time-constant heat sink. The method includes preheating a print head of the thermal printer to a first predetermined temperature, the print head in contact with a print head heat sink having a first thermal time constant, the print head heat sink in contact with an insulator, and the insulator in contact with a thermal reservoir having a second thermal time constant longer than the first thermal time constant such that the print head heat sink reaches the first predetermined temperature before the thermal reservoir. The method also includes printing a first image via the print head, the print head and print head heat sink reaching a second, higher temperature, the thermal reservoir at a temperature lower than the second temperature. The method further includes cooling, by the thermal reservoir, the print head and print head heat sink to a third temperature lower than the second temperature.
In one embodiment of the method, the print head heat sink has a high thermal conductivity and a small volume, or a low heat capacity. In a further embodiment of the method, the print head heat sink has a thermal conductivity of at least 50 W/mK. In still another embodiment of the method, the thermal reservoir has a high thermal conductivity and a large volume and/or large surface area, or a high heat capacity. In a further embodiment of the method, the thermal reservoir has a thermal conductivity of at least 50 W/mK. In some embodiments of the method, the insulator has a low thermal conductivity. In a further embodiment, the insulator has a thermal conductivity of less than 1 W/mK. In one embodiment of the method, the insulator has a thermal conductivity of at least two orders of magnitude less than the thermal conductivity of the print head heat sink or the thermal reservoir. In a further embodiment of the method, the insulator has a thermal conductivity of at least three orders of magnitude less than the thermal conductivity of the print head heat sink or the thermal reservoir. In another embodiment of the method, the insulator comprises a controllable heat pipe, and wherein heat flow from the print head heat sink to the thermal reservoir is reduced during preheating of the print head of the thermal printer. In yet another embodiment of the method, the insulator comprises an air gap. In a further embodiment, the method includes closing the air gap after preheating the print head. In a still further embodiment, the print head heat sink includes a bimetallic strip and the method includes bending, by the bimetallic strip, to contact the thermal reservoir upon reaching the first predetermined temperature. In still another embodiment, the dual time-constant heat sink has no moving parts.
In yet still another aspect, the present disclosure is directed to a method for print alignment by a continuous feed printer. The method includes detecting, by a sensor of a printer, a first line of a pattern on a non-printing side of a printing medium, the pattern comprising two non-parallel lines separated by a predetermined distance at a predetermined position of the printing medium. The method also includes advancing, by the printer, the printing medium a first distance. The method further includes detecting, by the sensor, a second line of the pattern. The method also includes identifying, by the printer, a horizontal offset of the printing medium from an expected location of the predetermined position proportional to the difference between the first distance and the predetermined distance.
In one embodiment, the method includes identifying a difference between the first distance and the predetermined distance by identifying a first time period from detecting the first line to detecting the second line. In another embodiment, the sensor and a print head of the printer are separated by a distance in the direction of travel of the printing medium, and the method includes identifying the horizontal offset of the printing medium further by adjusting the identified horizontal offset by a correction factor proportional to the distance. In yet another embodiment, the first line and second line of the pattern have different widths.
In some embodiments, the method includes advancing, by the printer, the printing medium a second distance; detecting, by the sensor, a third line of the pattern; and identifying a difference between the first distance and the second distance, the difference proportional to the horizontal offset. In a further embodiment, the method includes identifying a horizontal offset of the printing medium corresponding to the identified difference by identifying a horizontal offset proportional to a ratio of the difference between the first distance and the second distance and the sum of the first distance and the second distance. In another further embodiment, the first and third lines of the pattern are parallel, and the second line of the pattern is not parallel to either the first or third line. In still another further embodiment, the method includes categorizing, by the printer, each of the first line, second line, and third line, as belonging to either a first category or a second category. In an even further embodiment, the method includes maintaining a state machine, by the printer, the state machine having probability weights corresponding to transitions from the first category to the second category and from the second category to the first category. In many embodiments, the method includes printing, by the printer, an image on the printing side of the printing medium, offset according to the identified horizontal offset. In a further embodiment, the printing offset is obtained by dithering and quantizing the identified horizontal offset to a predetermined resolution.
In yet another aspect, the present disclosure is directed to a system for print alignment by a continuous feed printer. The system includes a continuous feed printer comprising a sensor placed to detect a pattern on a non-printing side of the printing medium, the pattern comprising two non-parallel lines separated by a predetermined distance at a predetermined position of the printing medium. The system also includes a print engine configured for: detecting, via the sensor, a first line of the pattern; advancing the printing medium a first distance; detecting, via the sensor, a second line of the pattern; and identifying a horizontal offset of the printing medium from an expected location of the predetermined position proportional to the difference between the first distance and the predetermined distance.
In one embodiment, the print engine is further configured for identifying a first time period from detecting the first line to detecting the second line. In another embodiment, the sensor and a print head of the printer are separated by a distance in the direction of travel of the printing medium, and the print engine is further configured for identifying the horizontal offset of the printing medium further by adjusting the identified horizontal offset by a correction factor proportional to the distance. In still another embodiment, the first line and second line of the pattern have different widths.
In some embodiments, the print engine is further configured for: advancing the printing medium a second distance; detecting, via the sensor, a third line of the pattern; and identifying a difference between the first distance and the second distance, the difference proportional to the horizontal offset. In a further embodiment, the print engine is further configured for identifying the horizontal offset of the printing medium corresponding to the identified difference as proportional to a ratio of the difference between the first distance and the second distance and the sum of the first distance and the second distance. In another further embodiment, the first and third lines of the pattern are parallel, and the second line of the pattern is not parallel to either the first or third line. In yet another further embodiment, the print engine is further configured for categorizing each of the first line, second line, and third line, as belonging to either a first category or a second category. In an even further embodiment, the print engine is further configured for maintaining a state machine, the state machine having probability weights corresponding to transitions from the first category to the second category and from the second category to the first category. In many embodiments, the print engine is further configured for printing an image on the printing side of the printing medium, offset according to the identified horizontal offset. In a further embodiment, the printing offset is obtained by dithering and quantizing the identified horizontal offset to a predetermined resolution.
In another aspect, the present disclosure is directed to an overcoat for a thermal printing medium, comprising two or more layers, wherein at least one layer of the overcoat comprises polyisocyanate or a derivative thereof. In some embodiments, at least one layer of the overcoat is an ultra-violet (UV) curable layer. In many embodiments, the ultra-violet (UV) curable layer comprises an additive selected from the group consisting of a photoinitiator, acrylate monomer, diacrylate monomer, triacrylate monomer, siliconized urethane acrylate oligomer and combinations thereof. In some embodiments, at least one layer of the overcoat comprises an additive selected from the group consisting of a latex component, activator, lubricant, surfactant, rheology control additive, anti-blocking additive, catalyst and combinations thereof.
In yet another aspect, the present disclosure is directed to a printing medium cassette. The cassette includes a shell comprising a vertical slot along a center line of each lateral side of the shell and a media exit slot tangent to a curve of the shell. The cassette also includes a spool extending laterally across the shell, the spool comprising two protrusions, each protrusion extending into and supported by a corresponding vertical slot of the shell. The cassette further includes at least one spring configured to raise the protrusion within the vertical slot as printing media wound around the spool is withdrawn from the media exit slot.
In some embodiments, an axis of the spool is raised by the spring such that the printing media exits the through the media exit slot tangent to the remaining media wound around the spool. In other embodiments, the spool further comprises a central spindle and a sleeve surrounding the central spindle, the sleeve able to slide laterally across the spindle within the shell. In a further embodiment, the sleeve comprises a space frame. In another further embodiment, the cassette includes the printing media wound around the sleeve.
In one embodiment, the cassette includes a cleaning pad attached within the media exit slot. In another embodiment, the cassette includes a storage memory storing parameters of the printing medium. In still another embodiment, the shell includes one or more ridges or notches for providing a secure grip for a user.
In yet another aspect, the present disclosure is directed to a method of dynamically resizing an image. The method includes displaying, by a display of a computing device, an image. The method also includes receiving, by an input device of the computing device, a user selection of an image resize function. The method further includes displaying, by the display, at least one dynamic length adjustment band as an overlay on the image. The method also includes detecting, by the input device, a selection and movement of the at least one dynamic length adjustment band by the user, the movement having a direction and distance. The method further includes resizing the image, by an image processing engine executed by a processor of the computing device, in a direction corresponding to the direction of the detected movement and by an amount proportional to the distance of the detected movement.
In one embodiment, the method includes displaying the at least one dynamic length adjustment band in a stretched format during detection of the movement of said dynamic length adjustment band. In another embodiment, resizing the image includes (i) enlarging the image, responsive to the direction of the detected movement being in a first predetermined direction, or (ii) reducing the image, responsive to the direction of the detected movement being in an opposing second predetermined direction. In some embodiments, the method includes scaling the display of the image, subsequent to resizing the image, to fully display the resized image on the display. In other embodiments, the user selection of an image resize function includes a selection of a button. In still other embodiments, the user selection of an image resize function includes a pinch gesture.
In yet another aspect, the present disclosure is directed to a method for dynamically adjusting the dimensions of an image. The method includes displaying, by a display of a computing device, an image having a first length and a dynamic selection element on the image at a first position. The method also includes detecting, by a touch interface of the display, a contact on the surface at the first position. The method further includes detecting, by the touch interface, a first motion of the contact to a second position. The method also includes displaying, by the display, the dynamic selection element stretched to the second position, responsive to detection of the first motion. The method further includes extending, by the computing device, the image to a second length, the second length longer than the first length by an amount proportional to a length of the first motion.
In one embodiment, the method includes detecting, by the touch interface, a breaking of the contact at the second position; displaying, by the display, the dynamic selection element unstretched at the first position, responsive to the detection of the breaking of the contact; and retaining, by the computing device, the image at the extended length.
In still another aspect, the present disclosure is directed to a method for dynamically adjusting the aspect ratio of an image. The method includes displaying, by a display of a computing device, an image across a predetermined region of the display, the image having a first length, a first height, and a corresponding first aspect ratio, and displaying a dynamic selection element on the image at a first position. The method also includes detecting, by a touch interface of the display, a contact on the surface at the first position. The method further includes detecting, by the touch interface, a first motion of the contact to a second position. The method also includes displaying, by the display, the dynamic selection element stretched to the second position, responsive to detection of the first motion. The method also includes extending, by the computing device, the image to a second length, the second length longer than the first length by an amount proportional to a length of the first motion; and displaying, by the display, the extended image across the predetermined region of the display at a second aspect ratio of the second length and the first height.
In one embodiment, the method includes detecting, by the touch interface, a breaking of the contact at the second position. The method also includes displaying, by the display, the dynamic selection element unstretched at the first position, responsive to the detection of the breaking of the contact. The method further includes retaining, by the computing device, the image at the extended length.
In still yet another aspect, the present disclosure is directed to an automatic media ejection system for a printer. The media ejection system includes a platen configured to support media during and after printing. The system also includes a non-circular roller positioned above the platen having a first portion with a first diameter and a second portion with a second, smaller diameter, the smaller diameter less than the distance between the axis of the non-circular roller and the platen. The system further includes an auto-ejection motor configured to rotate the non-circular roller to orient the second portion toward the platen during printing of the media, and rotate the non-circular roller continuously to eject printed media after printing.
In one embodiment of the media ejection system, the non-circular roller does not contact the media during printing. In another embodiment of the media ejection system, the non-circular roller has a D-shaped profile. In still another embodiment of the media ejection system, the non-circular roller comprises a high friction surface. In yet another embodiment of the media ejection system, the platen comprises a low friction surface.
In another aspect, the present disclosure is directed to a method for cutting a label by a printer. The method includes receiving, by a printer, a first image for printing on a continuous-feed printing medium. The method also includes printing, by the printer, the first image at a first position of the continuous-feed printing medium. The method further includes detecting, by a touch interface of a display of the printer, a motion of a contact on a surface of the display from a first predetermined position on the display to a second predetermined position on the display, and a breaking of the contact at the second predetermined position on the display. The method also includes cutting the continuous-feed printing medium at a second position of the continuous-feed printing medium subsequent to the printed first image, by a cutting mechanism of the printer, responsive to detection of the motion and breaking of the contact.
In some embodiments, the method includes receiving, by the printer, a second image for printing on the continuous-feed printing medium. The method also includes printing, by the printer, the second image at a third position of the continuous-feed printing medium subsequent to the second position. The method further includes receiving, by the direct thermal printer, a third image for printing. The method also includes kiss cutting the continuous-feed printing medium at a fourth position subsequent to the printed second image, by the cutting mechanism, responsive to receiving the third image. The method also includes printing, by the printer, the third image at a subsequent fifth position of the continuous-feed printing medium. The method further includes detecting, by the touch interface, a second motion of a second contact on the surface of the display from the first predetermined position on the display to the second predetermined position on the display, and a breaking of the second contact at the second predetermined position on the display. The method also includes cutting the continuous-feed printing medium at a sixth position of the continuous-feed printing medium subsequent to the printed third image, by the cutting mechanism, responsive to detection of the motion and breaking of the second contact. In a further embodiment, kiss cutting the continuous-feed printing medium further includes partially cutting through the medium to an adhesive backing of the medium.
In still another aspect, the present disclosure is directed to a method for illustrating the progress of printing of an image via a virtual image. The method includes receiving an image for printing, by a printer having a display positioned adjacent to a media ejection slot of the printer. The method also includes displaying, by the printer, a virtual image of the printed image on the display. The method further includes printing, by the printer, the image on a printing medium, the printing medium advanced through the media ejection slot during printing. The method also includes during printing, translating the image off the display, by the printer, in the direction of the media ejection slot, as a speed corresponding to a printing speed of the printer.
In one embodiment, the method includes positioning the image within the display offset from an edge of the display by a distance corresponding to a distance between a print head of the printer and the media ejection slot. In another embodiment of the method, the speed corresponding to the printing speed of the printer is proportional to a ratio of the size of the displayed virtual image and the printed image.
The details of various embodiments of the invention are set forth in the accompanying drawings and the description below.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:
The features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
Referring first generally to
Referring now to
The case 102 may include a removable or rotatable portion, shell or door 104 to cover and/or secure a cassette or cartridge inserted into the printer 100. Door 104 may be hinged on one edge, or may be held in place with clips, screws, thumbscrews, latches, pins, or via any other means, including compression-fitting.
Printer 100 may include a user interface module 106, which may include a capacitive or resistive touch screen or multi-touch screen; liquid crystal display (LCD), light emitting diode (LED) display, organic LED (OLED) display, electronic paper or electrophoretic ink (eInk) display, or any other type of display; one or more capacitive sensors, buttons, switches, or other contacts; a keypad or keyboard; a pointing stick or isometric joystick; or any other input/output devices or combination of these or other devices. For example, in one embodiment, the user interface 106 may include a multi-touch capacitive screen, one or more LEDs, and one or more capacitive sensors, while in another embodiment, the user interface 106 may include a resistive touch screen and a stylus. The user interface module 106, discussed in more detail below, may provide functionality for configuration, printing, editing of images, retrieving images from other devices or storage, connecting to a network, purchasing elements, or performing other functions.
Case 102 may include a media ejection slot 108 or similar opening through which printed media may be ejected. Although shown below user interface module 106, in other embodiments, the media ejection slot 108 may be on another side of the case 102 or above the user interface module 106, or even within the user interface module 106 in embodiments in which the user interface module 106 includes multiple portions such as a screen and keypad or screen and buttons. In other embodiments, media may be retained within printer 100 and the user may open a slot, door, or portion of case 102 to remove printed media.
Printer 100 may include one or more physical connection interfaces 109-111, and/or one or more wireless connection interfaces (WiFi, cellular, Bluetooth, or others, discussed in more detail below). Physical connection interfaces 109-111 may include any full-size, mini- or micro-receptacle, port or jack for interfaces such as universal serial bus (USB) including USB 2.0, or USB 3.0; FireWire (IEEE 1394, 1394b, or any other variant); Ethernet; Serial; Parallel; ThunderBolt or LightPeak; cylindrical connectors such as ⅛″ TRS or other variants; or any other type and form of connection interface for transferring data into or out of printer 100. For example, as shown in
As shown in
Other embodiments of printers may not include a touch screen user interface module or similar interface, reducing size, weight, and cost. For example, referring now to
Printer 200 may include battery pack 204. Battery pack 204 may comprise a compartment and/or holder for user-replaceable batteries, such as AA or 9 volt batteries, or may include a Li-ion or NiCad battery pack. As shown, battery pack 204 may securely connect to a case 202 of printer 200, via one or more latches, clips, or compression fittings. For example, electrical connections from the battery pack 204 to the rest of the printer 200 may be via pins or contacts between pack 204 and case 202, and the battery pack 204 may clip into the case to form a tight physical and electrical connection. This may allow a user to swap battery packs if one is drained, and/or may also allow for attachment of accessories. For example, in one embodiment, an accessory pack with an extended battery or accessory pack with additional wired or wireless communications features may be attached in place of battery pack 204. In another embodiment, an accessory pack may be attached in addition to battery pack 204. For example, an accessory pack may be configured to fit in between battery pack 204 and case 202, with top and bottom electrical contacts to pass power from the battery to the printer.
Printer 200 may include a media ejection port or slot 206 through which printed media may exit. Although shown on the front of printer 200, media ejection slot 206 may be on top of the printer, or in any other location. Media ejection slot 206 may be open, as shown, or may include a door or cover. In some embodiments, accessories such as media catch trays may be connected to printer 200 and/or slot 206 to receive printed media after ejection.
Printer 200 may include a sensor for triggering a cut by a user, or a “cut sensor” 208. Cut sensor 208 may comprise one or more capacitive sensors, one or more buttons, one or more optical sensors, or any other type and form of sensor for detecting a user interaction to indicate a command to cut printed media. As discussed in more detail below, in some embodiments of cutting systems discussed herein, printed media may be cut partially through to a backing layer (referred to as a kiss cut), which may allow for easy removal of printed adhesive labels of variable length. Printed media may also be fully cut (referred to as a full cut) to eject the media from printer 200. In some embodiments of printer 200, a full cut mechanism may be positioned internally at some distance from media ejection slot 206, such that after cutting the media, in some instances, the media may not fall free of the ejection slot due to gravity alone. As a result, the printed media may rest partially inside printer 200. If the user tries to subsequently print another image, the media being printed would press against the previously printed and cut media, resulting in additional friction, bending of the media during printing, sliding or skipping resulting in visible distortions or “banding” within the printed image, or other undesirable effects. Accordingly, in some embodiments, the printer 200 may require the user to interact with a cut sensor 208 to perform a cut command or gesture, discussed in more detail below. Thus, the user can be in position to manually remove a cut segment of media from media ejection slot 206, eliminating the potential for the above undesirable effects.
In some embodiments, cut sensor 208 may further include one or more indicator lights, which may be lit responsive to the user interaction with the sensor 208. For example, the cut sensor 208 may comprise three capacitive sensors positioned across the width of the sensor region 208, with corresponding LEDs placed below transparent or partially transparent portions of case 202. As the user swipes a finger across the three sensors, each corresponding LED may light (either remaining lit, or extinguishing once the user's finger has moved from the corresponding sensor) and upon completion of the swipe, a cutting mechanism of the printer 200 may fully cut the printed media. The user may manually remove the printed media from slot 206, and the printer 200 is ready to print a subsequent image.
The printer 200 may also have a physically-controlled cutting mechanism, such as a rolling or sliding cutter. Sensor region 208 may be replaced in such embodiments with a physical handle, knob, button, or similar implement. The user may manually move said physical implement along a slot to move a corresponding physical cutter across the printed media. In still other embodiments, other manual cutting mechanisms, such as guillotine-type manual cutters, may be employed. In various embodiments, the printer 200 can include a mechanical actuator (e.g. a physical handle) to control the cutting mechanism, a sensor (e.g., sensor 208), or both.
Printer 200 may include may include one or more physical connection interfaces 210, and/or one or more wireless connection interfaces (WiFi, cellular, Bluetooth, or others, discussed in more detail below). Physical connection interfaces 210 may include any full-size, mini- or micro-receptacle, port or jack for interfaces such as USB, including USB 2.0, or USB 3.0; FireWire; Ethernet; Serial; Parallel; ThunderBolt or LightPeak; cylindrical connectors such as ⅛″ TRS or other variants; or any other type and form of connection interface for transferring data into or out of printer 200. Physical connection interfaces 210 may also include slots, receptacles, or interfaces for flash memory or other storage devices or expansion cards, such as PCMCIA, MMC, CompactFlash; SD, MicroSD, MiniSD; or any other type and form of storage device or card. Although shown as a USB type B receptacle on the side of case 202, one or more connection interfaces 210 of various types may be in other locations of the printer 200 and may be together or separate in location.
Printer 200 may include one or more function buttons 212. Function buttons 212 may be physical buttons, capacitive sensors, or any other type of button, switch, or sensor. A button 212 may be a power button for powering the printer 200 on or off, or may be a function button for performing various control and/or configuration functions. For example, in one embodiment discussed in more detail below, a printer 200 may include a wireless network interface, and a function button 212 may be used to switch the network interface between an independent access point mode and an existing-network connected mode. A single function button 212 may also perform multiple functions, allowing the user to rotate between multiple status or configuration modes, such as off; on in access point mode; and on in network-connected mode. Although shown on the side of case 202, one or more function buttons 212 may be placed anywhere on case 202 and/or battery pack 204.
Printer 200 may include a power receptacle 214, which may be positioned on the case 202 or as part of battery pack 204 as shown. For example, battery pack 204 may comprise a rechargeable Li-ion battery and may include a DC power input jack 214. This may allow users to charge a first battery pack 204 while using a second battery pack 204 with the printer, which may be particularly helpful in uses where portability is required, such as using printer 200 for printing wire labels during construction of a building, or using printer 200 for generating name tags at an outdoor reception.
A battery pack 204 may also include a latch 216 for clipping battery pack into case 202. Latch 216 may comprise a spring latch, sliding or locking latch, or similar latch or clip to provide a secure connection of battery pack 204 to case 202. Battery pack 204 may include multiple latches 216 on different sides or in different orientations along the bottom, or may include a single latch as shown. In embodiments with the latter, the battery pack 204 may include hooks or similar protrusions along the top of the pack to connect with corresponding catches or receptacles of case 202, with latch 216 providing a secure hold on an opposing edge of the battery pack. In other embodiments, a battery pack 204 may not include a manually operated latch 216. In such embodiments, the battery pack 204 may securely attach to printer 200 via snap-in hooks or internal latches in deflectable or deformable portions of the plastic case, via magnets, or via other attachment means.
Printers 100 and 200 may be used with various types of media, including black and white direct thermal media or full color direct thermal media, such as various media manufactured by ZINK Imaging, Inc.; plain paper media for black and white or inkjet or toner-based printing; thermal dye-sublimation printing or transfer printing; or any other type and form of media. Media may be of fixed or predetermined lengths, such as sheets of predetermined dimensions, or may be on continuous rolls in cassettes or cartridges for variable-length printing. In some embodiments, media may include an adhesive between a substrate and a disposable backing layer, allowing printing of labels or stickers. The media may also include transparent sections for self-laminating wire labels or similar uses. The media may be provided in any width. In some embodiments using cassettes or cartridges, rolls of media of predetermined width may be used and cut to desired lengths during printing. In other embodiments, longitudinal cutting mechanisms may be employed to cut a wide strip of media to a narrower width.
Referring now to
Cassette 300 may include a roll of media 302 (partially shown protruding from cassette 300 in
Cassette 300 may include an alignment protrusion 304 for aligning and centering the cassette when inserted into a printer 100, 200. Protrusion 304 may prevent rotational torque along the vertical axis of the cassette when media 302 is being pulled from the cassette and/or aid in alignment of the media against a print head. Similarly, cassette 300 may include one or more additional protrusions or guides 306 for engaging a corresponding slot or guide of a printer 100, 200, to align the cassette when inserted into the printer. Although shown on top, in many embodiments, protrusions or guides 304, 306 may be on the sides and/or bottom of the cassette.
During manufacture, adhesive tape 310 or a similar material may be placed on cassette 300 in contact with both the shell of cassette 300 and media 302, for example, to prevent media 302 from accidentally being irretrievably rewound into the cassette. As shown in
Cassette 300 may include labeling 308 to indicate width of the media and/or type of media. For example, as discussed above, media may be adhesive or non-adhesive; black and white or color direct thermal media; partly or entirely transparent or self-laminating; be white or pre-colored for sublimation printing on a colored background; or may be a non-printing cartridge including a cleaning medium, discussed in more detail below, and may be provided in different widths. Cassette 300 may also be colored to indicate media type, such as blue for a cleaning cassette and green for a direct thermal color cassette, or any other color or combination of colors.
For example, shown in
Referring back to
To control brakes within the cassette that prevent media from moving in or out of the cassette unintentionally, a cassette 300 may include an opening 316 through which a brake lever (discussed in more detail below) may be released. Opening 316 may be near an edge or end cap of cassette 300, as shown in
Some printers 100, 200 may accommodate these multiple positions of opening 316 by providing several corresponding levers at different positions corresponding to the varied positions of opening 316 with different width cassettes 300. For example, a printer 100, 200 may have three levers which may be simultaneously moved to engage a corresponding brake lever through an opening 316 of an inserted cassette 300, regardless of which cassette 300 is used. As these levers are of a length to extend into opening 316 to engage the brake lever, wider shells may include false openings 314 and 314′ so as to provide a clear space for inner levers to move freely when wider cassettes 300 are inserted into the printer.
Cassette 300 may include an identification module 320. Identification module 320 may comprise a storage device, such as flash memory, an EEPROM or other non-volatile memory, or any other type of hardware for storing an identification signal identifying the cassette 300. Although shown with electrical contacts, identification module 320 may comprise a radio-frequency identification (RFID) tag or similar near-field communication device.
Identification module 320 may be used by printer 100, 200 to automatically identify an inserted cartridge. For example, data stored in identification module 320 may include:
Gear 322 may be engaged by brake lever 318, which may be manipulated by a corresponding lever of printer 100, 200 via an opening 316, as discussed above. As shown in
Cassette 300 may include a cleaning pad 326. Cleaning pad 326 may comprise an abrasive material, absorptive material, microfiber material, felt fabric, or similar material for wiping foreign materials from the surface of media 302 prior to the media being moved into position beneath a print head of the printer. Cleaning pad 326 may be held under pressure against media 302, may be connected to a helical spring or leaf spring to hold the pad against media 302, or otherwise positioned to engage media 302. In some embodiments, cleaning pad 326 may prevent entry of dust into cassette 300, while in other embodiments, cassette 300 may have other openings (such as opening 316) that allow dust to enter. Accordingly, cleaning pad 326 may instead prevent exit of dust from cassette 300 into the body of a printer 100, 200 or from being carried by media 302 to a print head where it may disrupt printing or cause artifacts.
As shown in
For example, referring to
In some instances, media may be wound off-center around the central portion 336 of a spindle, resulting in lateral forces on the media during printing as the media rubs against a wall of the cassette. Accordingly, in some embodiments, the central portion 336 may be surrounded by a floating or sliding sleeve 340. Sleeve 340 may comprise a circular element with an interior diameter slightly larger than central portion 336, and a width of less than central portion 336. Sleeve 340 may comprise one or more internal protrusions 339 which may be mated with a corresponding one or more external notches 338 on central portion 336, such that the sleeve 340 may rotate with central portion 336 (and end caps 330a, 330b), but may freely slide laterally across central portion 336 (to the extent of the notch). During manufacture, the media may be wound around sleeve 340, and then installed on central portion 336. During use, the media and sleeve 340 may slide laterally within cassette 300 and/or may be pushed away from walls of the cassette 300, reducing or eliminating lateral forces on the media during printing that may cause visible errors. Although the media may not remain centered within the cassette during printing, various printing re-alignment methods discussed in more detail herein may be employed to ensure that printed images are centered on the media.
As media may be wound around sleeve 340, the central portion 336 does not necessarily need a substantial body to support the media, and may comprise a space frame or space structure rather than a solid surface. Accordingly, in another embodiment not illustrated, the central portion 336 and/or end caps 330a, 330b may comprise one or more holes or slots to reduce weight and material requirements, or may be formed of one or more curved members to support sleeve 340.
As noted, in some embodiments, the printers 100, 200 are multicolor direct thermal printers, and/or may utilize continuous-roll cassettes 300 of printing media 302. As used herein the terms “printing medium” and “direct thermal imaging member” are used interchangeably. In embodiments utilizing multicolor direct thermal printers, the printing medium 302 may comprise a substrate and one or more color-forming layers, each impregnated with a color forming dye, said dyes having various activation times and temperatures.
Direct thermal imaging is a technique in which a substrate bearing at least one color-forming layer, which is typically initially colorless, is heated by contact with a thermal printing head to form an image. In direct thermal imaging there is no need for ink, toner, or thermal transfer ribbon. Rather, the chemistry required to form an image is present in the imaging member itself.
In some embodiments, the direct thermal imaging member (i.e., printing media) 302 comprises three color-forming layers, each affording one of the subtractive primary colors, and is designed to be printed with a single thermal printing head. The topmost (relative to substrate 380 in
The composition of the thermally-insulating layers is chosen so as neither to compromise the chemistry responsible for formation of color in the color-forming layers nor to degrade the stability of the final image. Each color-forming layer typically comprises a dye precursor that is colorless in the crystalline form but colored in an amorphous form. Materials such as thermal solvents, developers or other additives may be incorporated into the color-forming layer to adjust the temperature at which color is formed, the degree of coloration that is achieved and/or the stability of the media and print.
Each color-forming layer can change color, e.g., from initially colorless to colored, where it is heated to a particular temperature referred to herein as its activating temperature.
Any order of the colors of the color-forming layers can be chosen. One preferred color order is as described above. Another preferred order is one in which the three color-forming layers 382, 386, and 390 provide yellow, magenta and cyan, respectively.
All the layers disposed on the substrate 380 are substantially colorless and transparent before color formation. When the substrate 380 is reflective (e.g., white), the colored image formed on imaging member 302 is viewed through the overcoating 392 (or overcoatings 392a and 392b) against the reflecting background provided by the substrate 380. The transparency of the layers disposed on the substrate ensures that combinations of the colors printed in each of the color-forming layers may be viewed.
Discussions of representative multicolor direct thermal printing media and the dyes used in such media are provided in the following commonly assigned U.S. Pat. Nos. 7,807,607, 7,829,497, 7,704,667, 7,176,161, 7,504,360, 6,951,952, 7,282,317, 7,279,264, 7,008,759, 7,282,317, 6,906,735, 6,801,233, 6,906,735, 7,166,558, 7,635,660, 7,504,360, and the published U.S. Patent Application No. US 2010/087316, each of which is incorporated herein by reference.
Referring to
Exemplary Overcoating I: A Single Overcoat Layer 392 Comprising an Aqueous Dispersible Polyisocyanate Component and One or More Reactive Hydroxyl and/or Amino Functional Components
In some embodiments, the printing media described herein comprises a single overcoating layer 392 that includes a polyisocyanate and one or more reactive hydroxyl and/or amino functional components. Overcoating compositions of this type are designed to adhere to the printing media and provide the printing media with a protective layer and a contact point that does not stick, degrade, or deform upon contact with the high temperature print head of any of the thermal printers described herein.
In some embodiments, the overcoating layer comprising a polyisocyanate includes a reactive hydroxyl functional latex. In some embodiments, the overcoating layer comprising a polyisocyanate includes a reactive amino functional component. In some embodiments, the overcoating layer comprising a polyisocyanate includes both a reactive hydroxyl functional latex and a reactive amino functional component. Such overcoating layers also include lubricating components to reduce the friction between the media and the thermal print head during printing. Overcoating layers such as these provide water resistance, protection from handling (e.g., abrasion resistance and skin oil resistance), and allow the media to withstand the high temperatures of thermal printing. In some embodiments, the overcoating layer comprising a polyisocyanate prevents the media from deforming or sticking to a thermal print head upon exposure to heat, friction, humidity and pressure. In some embodiments, the overcoating layer comprising a polyisocyanate provides increased image stabilities.
The overcoating layer comprising a polyisocyanate can be applied as a single layer on top of the printing media. The polyisocyanate along with other components can be pot blended together prior to being applied to the printing medium. Alternatively, the polyisocyanate along with other components can be applied separately to the media as in-line blend streams during manufacture. In one embodiment the polyisocyanate is introduced into the coating fluid as an in-line blend stream just before the layer is applied to the substrate in the coating process. The in-line blend approach is particularly useful when the polyisocyanate and other components such as a hydroxyl functional latex or an amino functional component are highly reactive such that unwanted premature cross linking reactions would occur causing coating defects if they were pot blended together in the coating process. In some embodiments, the overcoating layer 392 comprising a polyisocyanate requires approximately 24 to 72 hours to cure after being coated onto the printing media.
Representative examples A and B of a single overcoating layer (I) comprising a polyisocyanate are shown below in Table 1.
Exemplary Overcoating II: A Two Layer Overcoating System 392a and 392b, where One Layer 392a Includes a Polyisocyanate Along with One or More Reactive Hydroxyl Functional Latex Components and a Second Layer 392b Includes an Activator the Purpose of which is to Accelerate the Polyisocyanate Cross Linking Reactions in the First Layer.
In some embodiments, the media is coated with a two layer overcoating system 392a and 392b comprising a first layer 392a having a polyisocyanate along with one or more reactive hydroxyl functional latex components and a second layer 392b comprising a latex binder and a cross linker activator. The two overcoating layers are the top most layers in the multilayer imaging member. In one embodiment the second overcoating layer 392b containing the activator is positioned above the first polyisocyanate containing overcoating layer 392a (e.g., as a separate layer above the first overcoating layer). The second overcoating layer 392b may, in some embodiments, be referred to as a top coat, while the first layer 392a may be referred to as an overcoat. In some embodiments, the second layer 392b or top coat may contain a latex binder, a cross linker activator (e.g., Bacote 20), one or more meltable lubricants, and other coating additives. In particular, in many embodiments, Bacote 20 or similar crosslinker activators in the top coat may significantly increase the speed of polyisocyanate crosslinking reactions in the overcoat layer. In some embodiments the order of the two overcoating layers may be reversed with the polyisocyanate containing layer being the topmost layer.
This two layer overcoating system 392a and 392b improves the media manufacturing process by reducing the time required for the overcoating system to cure (i.e., cross link). As such, the two layer overcoating system prevents disruptions in the continuous process of coating the media and minimizes defects in the coated media. The two layer overcoating system also reduces the tackiness of the printing media during the period of time after the coating is complete to when the curing is complete. In particular, the two layer overcoating system, once fully cured, provides a surface of the media that does not stick to the thermal print head, degrade, or deform under printing conditions that include elevated temperatures and high humidity.
The components of each layer 392a or 392b can be pot blended before each layer is coated onto the media. Alternatively, the components of each layer can be applied by an in-line blend process, directly to the media as separate fluid streams. In one embodiment the polyisocyanate is introduced into the coating fluid as an in-line blend stream just before the layer containing it is applied to the substrate in the coating process. In some embodiments, the two layer overcoating system requires approximately 24 to 48 hours to cure.
Representative examples C-E of the second layer 392b or topcoat of the two layer overcoating system (II) (containing the cross linker activator) are shown below in Table 2. Representative examples F and G of the first layer 392a of the two layer overcoating system (II) are shown below in Table 3.
In some embodiments, the printing media includes an overcoating (III) layer 392 that is formulated to be UV curable. UV curable overcoating provides excellent water resistance and also helps provide a media surface that does not stick to the thermal print head, degrade, or deform under printing conditions that include elevated temperatures and high humidity.
In some embodiments, the overcoating layer 392 is formulated to be UV curable by adding UV curable monomers or oligomers to the overcoating and subsequently exposing the overcoating to UV light. The UV curable monomers or oligomers may further include photoinitiators, lubricants, and surfactants well known to the skilled artisan. The UV cured overcoating can be formulated from 100% solids or a solvent based gravure coating, or as a solvent slot coating, that cures upon exposure to UV light. The UV cured overcoating layer 392 provides excellent water resistance, thermal printing performance, and gloss characteristics. The UV curable overcoating layer 392 can be cured with an H bulb on a Fusion UV system.
Representative examples H-J of UV curable overcoatings (III) 392 are shown below in Table 4.
Referring now to
A printer may include a processor 402. Processor 402 may be any type and form of processor or microprocessor, such as those manufactured by Intel Corporation of Mountain View, Calif.; those manufactured by Motorola Corporation of Schaumburg, Ill.; the ARM processor and Tegra system on a chip (SoC) manufactured by Nvidia of Santa Clara, Calif.; those manufactured by Apple Inc. of Cupertino, Calif. or Samsung Electronics of Korea, such as the A4, A5, or A5X SoC; those manufactured by International Business Machines of White Plains, N.Y., such as the POWER7 processor; or those manufactured by Advanced Micro Devices of Sunnyvale, Calif.; or any other processor capable of operating as described herein. The processor 402 may utilize instruction level parallelism, thread level parallelism, different levels of cache, and multi-core processors. An example of a multi-core processor is the AMD Phenom IIX2 or Intel Core i5 or Core i7. Processor 402 may comprise logic circuitry that responds to and processes instructions fetched from memory.
The printer may include memory 404. Memory 404 may comprise one or more storage devices, including random access memory for execution of processes, or non-volatile storage for retaining applications, data, operating systems, or other elements. For example, memory 404 may include one or more hard disk drives or redundant arrays of independent disks or flash memory elements for storing an operating system and other related software, and for storing application software programs. Memory 404 may include one or more hard disk drives (HDD); optical drives including CD drives, DVD drives, or Blu-Ray drives; solid-state drives (SSD); USB flash drives; or any other device suitable for storing data. Memory 404 or a portion of memory 404 may be non-volatile, mutable, or read-only. Memory 404 may be internal or external to the printer. For example, in one embodiment of the latter, memory 404 may comprise a flash memory storage device, such as an SD card inserted into a card reader of the printer. Memory 404 may further include remote storage devices that connect to the printer via a network interface such as the Remote Disk for the MacBook Air provided by Apple Inc. or other network storage devices. Memory 404 or a portion of memory 404 may also be one or more memory chips capable of storing data and allowing any storage location to be directly accessed by processor 402. For example, such memory or a portion of memory 404 may be volatile and faster than storage memory. Memory 404 may comprise Dynamic random access memory (DRAM) or any variants, including static random access memory (SRAM), Burst SRAM or SynchBurst SRAM (BSRAM), Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended Data Output RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), Burst Extended Data Output DRAM (BEDO DRAM), Single Data Rate Synchronous DRAM (SDR SDRAM), Double Data Rate SDRAM (DDR SDRAM), Direct Rambus DRAM (DRDRAM), or Extreme Data Rate DRAM (XDR DRAM). Memory 404 may be based on any of the above described memory chips, or any other available memory chips capable of operating as described herein.
The printer may include a power supply 406. Power supply 406 may comprise any type and form of power supply, including one or more batteries or battery packs, including user replaceable batteries and non-user replaceable batteries. As discussed above, batteries may be accessible via a compartment or access panel of the printer, may be in a separate package that may be clipped on or connected to the printer, or may be installed within the printer in a non-user replaceable manner. The power supply 406 may comprise an alternating current or direct current power supply, such as a switched-mode power supply, linear power supply, or other power supply. In some embodiments, power supply 406 may include both batteries and an AC or DC power supply, allowing for both portable use and long term use with external power, as well as recharging of batteries. The power supply 406 may supply power to computing elements such as processor 402 and memory 404 and display devices, as well as printing elements such as a print head and media transport or a print engine 408. The printer may include multiple power supplies for redundancy and/or efficiency. For example, a low power supply may be used to power low-power computing elements, and a high power supply may be used to power heaters and mechanical transport elements.
The printer may include a print engine 408. Print engine 408 may comprise one or more processors, integrated circuits, signal processors, or other hardware or logic elements for controlling a print head and/or transport elements of a printer. For example, the print engine 408 may include a processor for controlling pulses (e.g. electrical pulses) transmitted to resistive heaters of a thermal print head, or for advancing media. The print engine 408 may further include graphics processors for performing various processing steps on an image to be printed, including stretching, dithering, anti-aliasing, color correction, corrections to contrast or brightness, stitching, or other such processes. For example, due to the expense and difficulty of creating large format thermal print heads, the printer may include multiple thermal print heads arranged in an overlapping configuration to print across media that is wider than a single print head. Print engine 408 may divide images for printing by each print head, as well as applying stitching techniques to reduce or eliminate visible artifacts or banding in the stitched or overlap area. Print engine 408 may also control one or more mechanical portions of the printer, such as transport motors, tension motors, cutters, ejection mechanisms, or other such elements. Although shown separate from processor 402, in many embodiments, print engine 408 may comprise functions and logic executed by processor 402, which may reduce expenses at the cost of some efficiency or processing speed.
In some embodiments, a print engine 408 may include a print head controller 430, a head pressure controller 432, a transport controller 434, and/or a cutter controller 436. Controllers 430-436 may comprise hardware, software executed by a processor of print engine 408, or a combination of hardware and software. For example, controllers 430-436 may comprise subroutines, services, threads, or modules executed by print engine 408. In some embodiments, a print engine 208 may further comprise a media sensor 438.
In some embodiments, a print head controller 430 may comprise logic for controlling one or more print heads or elements of one or more print heads, such as resistive elements of a thermal printer. Print head controller 430 may comprise functionality for stitching images between a plurality of print head elements; controlling pre-heating functions; triggering pulses for a thermal printer; adjusting position, density, or other features of an image during printing; or performing other calculations and functions for printing an image.
A head pressure controller 432 may comprise logic for controlling a motor or other element for adjusting pressure of a print head against a platen during printing. As discussed in more detail herein, in many embodiments of printers that may utilize different widths of media, it may be desirable to adjust pressure of the head against the platen to provide full width printing while preventing printing on the platen roller itself.
A transport controller 434 may comprise logic for adjusting a transport to advance and/or retract media. For example, transport controller 434 may control rollers to advance media for cutting, and then retract the media to allow printing across the cut to provide full bleed images, as discussed in more detail herein. In some embodiments, transport controller 434 may track the rotational position of a platen roller. For example, the platen roller may not be uniform or may have defects along its surface due to manufacturing tolerances. The transport controller 434 may monitor the position of the platen, such as via a sensor or by monitoring rotation of a gear connected to the platen directly or via a chain of gears in an integer relationship, such that rotation of the gear may directly correlate to a rotational position of the platen. The transport controller 434 may notify the print head controller 430 and/or head pressure controller 432 that a platen or other transport defect will cause a potential print defect at an identified time or printing location, such that controllers 430, 432 may compensate.
A cutter controller 436 may comprise logic for controlling one or more cutters or motors connected to cutting levers, including a kiss cutter or full cutter. The cutter controller 436 may communicate with the transport controller 434 to ensure proper positioning of media for cutting, and for indicating a cut is complete such that the media may be advanced or retracted.
Print engine 408 and/or printer 100, 200 may include a media sensor 438. Media sensor 438 may comprise an optical sensor, physical sensor, or any other type and form of sensor for detecting media 302 and/or a pattern 1000, 1100 imprinted on media 302 for tracking purposes and discussed in more detail below. In many embodiments, media sensor 438 may be positioned underneath media 302 or on a side opposite that of a print head or printing surface of media 302. Media sensor 438 may be used to identify entry of media 302 into the printing apparatus, and/or may be used to identify markers indicating that the end of the roll of media in the cartridge or cassette is approaching, such as double lines, lines in a different color, patterns, or other indicators.
The printer may include one or more network interfaces 410. Network interfaces 410 may include, without limitation, telephone lines, Ethernet interfaces to a local area network (LAN) or wide area network (WAN), broadband connections (e.g., ISDN, Frame Relay, ATM, Ethernet-over-SONET, ADSL, VDSL, BPON, GPON, fiber optical including FiOS), wireless connections (e.g. radio frequency, cellular, BlueTooth), or some combination of any or all of the above or other interfaces, such as ThunderBolt, FireWire, or serial or parallel interfaces of any type. Connections can be established using a variety of communication protocols (e.g., TCP/IP, ARCNET, SONET, SDH, Fiber Distributed Data Interface (FDDI), IEEE 802.11a/b/g/n/ac, CDMA, GSM, WiMax and direct asynchronous connections). A network interface 410 may comprise a built-in network adapter, network interface card, PCMCIA network card, ExpressCard network card, card bus network adapter, wireless network adapter, USB network adapter, cellular modem, WiFi access point or wireless network interface or any other device suitable for interfacing the printer to any type of network capable of communication and performing the operations described herein. Network interface 410 may execute a network stack providing communications via one or more OSI layers, and may perform various processing functions including compression and decompression, encryption and decryption, acceleration, tunneling, caching, buffering, multiplexing, connection pooling, or any other type and form of communications processing.
Multiple network interfaces 410 may be bridged. For example, a printer may include a wired interface to a switch or router and a wireless interface acting as a WiFi access point, and may bridge between the interfaces to provide network access to other computing devices. In other embodiments, network interfaces 410 may not be bridged. For example, a printer may include a first network interface providing a WiFi access point through which a computing device may connect to provide configuration commands to the printer. The configuration commands may cause the printer to reconfigure a second network interface to join an existing wireless network to serve as a network printer. This may allow for easy configuration of a “headless” printer or printer without a display or input device such as a printer 200. In a similar embodiment, the printer may include one wireless network interface which may be configured as a WiFi access point. The user may connect, via a computing device, to the printer and provide configuration commands to the printer. The printer may then reconfigure the wireless network interface to join an existing wireless network. As discussed above, the printer may include a button or control to reset the wireless network interface or return the printer to an access point mode.
The printer may also include one or more communications interfaces 412. Communication interface 412 may include any type of wired or wireless communication interface for direct connection to a computing device, such as a serial or parallel connection, a USB interface, FireWire interface, ThunderBolt interface, or any other type and form of connection interface for transferring data between the printer and a computing device. For example, the printer may connect to a desktop computer via a USB cable and may appear to applications and the operating system of the desktop computer as a USB printing device.
The printer may include a media cutter 414, which may comprise one or more cutters, including full cutters or kiss cutters as discussed above. A cutter 414 may include a rotary cutter, scissors or guillotine cutter, or any other type and form of cutter or cutting mechanism. A cutter 414 may be configured to cut laterally across media, or may be configured to cut longitudinally along media. A single cutter 414 may be configured to cut to a first depth in the media to perform a kiss cut and configured to cut to a second depth through the media to perform a full cut, or kiss cutting and full cutting may be provided by separate cutters 414.
The printer may include a display 416, such as an LCD display, LED or OLED display, eInk display, or any other type and form of display. Display 416 may be coupled with an input device 418, such as a multi-touch capacitive LCD touch screen. In other embodiments, the printer may connect to an external display 416, such as an external CRT or LCD screen or micro- or pico-projector, or any other type of display. Input device 418 may include one or more buttons, capacitive sensors, resistive or capacitive touch screens, keypads or keyboards, joysticks, stylus or pen input devices, trackballs, pointers, directional buttons, or any combinations of these or other input devices. In some embodiments, the printer may connect to an external input device 418 such as a BlueTooth or USB keyboard. The printer may also include a speaker 417 for providing audio feedback, such as clicks for a virtual keyboard, beeping or other alert noises, or similar sounds.
The processor 402 of a printer may execute one or more applications, services, servers, daemons, routines, subroutines, or other executable logic or code. For example, processor 402 may execute an operating system 420. Operating system 420 may comprise an operating system, such as the iOS system provided by Apple Inc., Android operating system provided by Google Inc., the Windows Mobile or Windows Phone operating systems provided by Microsoft, or one of the variants of Embedded Linux or Linux, or any other type and form of embedded, real-time, proprietary, open-source, mobile, or other operating system for controlling access to resources and scheduling tasks.
The printer 100, 200 may execute a print server 422. Print server 422 may be an application, service, server, or other executable logic for receiving printing commands and data files, including text and/or images, from clients such as desktop computers, tablet computers, laptop computers, and smart phones. Print server 422 may support any type and form of printing protocol including internet printing protocol, line printer daemon protocol, NetWare, NetBIOS/NetBEUI, JetDirect, or any other type of protocol. Print server 422 may include a buffer or storage for storing images or files for printing, and may include queuing or spooling functionality.
The printer 100, 200 may execute a configuration interface 424. Configuration interface 424 may comprise an application, server, service, or other executable logic for receiving configuration information from a user. For example, configuration interface 424 may include a web server and a configuration page provided by the web server. A user may connect a computing device to a WiFi access point provided by network interface 410 and may direct a browser to open the configuration page. The user may then provide configuration commands, such as printing default settings or commands to join a network provided by an external wireless router.
The printer 100, 200 may execute an editing application 426. Editing application 426, discussed in more detail below, may comprise an application allowing WYSIWYG generation and editing of images or labels for printing, and saving and retrieval of images and/or elements to a portion of memory such as file storage 428. Editing application 426 may provide templates or pre-printed images, and/or may allow for purchase of such elements, templates, and images from an online store.
As discussed above, some printers such as printer 100 may include a user interface and display. On such printers, a user may directly select a wireless configuration screen or menu and request the printer to join a network provided by a wireless router. However, on other printers such as printer 200 that do not include a display, the user may not be able to directly select existing networks or enter passwords if required. Accordingly, in some embodiments of the latter, a wireless network interface of the printer may provide a wireless access point. The user may connect to the printer's wireless network and select another existing network provided by another device or router for the printer to join. The printer may reconfigure the wireless network interface, or configure a second wireless network interface, and join the selected network, allowing network devices to print via the printer.
Referring now to
At step 2, the printer may configure the wireless network interface 410 to join the network provided by the WiFi access point 442. In embodiments in which the printer has a single wireless network interface 410, the printer may reconfigure the interface to join the network provided by access point 442 as a client. This can disconnect device 440a from the network provided by the wireless network interface 410. In other embodiments, the printer may have multiple wireless network interfaces 410, and may configure a second network interface to join the WiFi access point while the first remains in an access point mode. The second interface may be bridged to the first, allowing the user to access the network provided by the WiFi access point 442 without having to reconfigure their device 440a. In a similar embodiment, the user may connect a computing device to the printer via a communication interface, such as USB, to configure the wireless network interface 410. Once configured and joined to the network of WiFi access point 442, the printer may bridge the communication interface and network interface and provide wireless communications for the computing device of the user. In other embodiments, at step 3, the user may connect their device to the WiFi access point 442 and print via the wireless network to the printer 200. Similarly, other devices 440b and 440c may also print via the wireless network to printer 200.
Referring first to auto-eject mechanism 502, illustrated in
As discussed above, during printing and depending on the length of the image to be printed, media 302 may be advanced past the print head 500 and through the automatic ejection mechanism 502. For example, the distance between the print head 500 and ejection mechanism 502 may be three inches in one embodiment. If an image is longer than three inches, then even if the media is cut immediately prior to printing and printing begins at the cut, the media will be between roller 600 and platen 602 during printing of part of the image. If roller 600 and platen 602 are both contacting the media, then the added friction may create a back pressure or tension on the media, even with freely-rotating rollers. This friction may result in stuttering, jerking, or slipping of the media, resulting in visible artifacts or banding during printing.
Accordingly, to avoid such artifacts, roller 600 may have a non-circular or D-shaped profile as shown, and may be rotated to the position illustrated in
In some printers, the print head may be significantly smaller than the media, and may be mechanically moved across the media to print each line. For example, many inkjet printers move an inkjet cartridge across a page of media, advancing the media line by line to print an image. Such implementations allow for many different widths of media, but add expense and suffer from reduced printing speed and potential mechanical problems. In other printers, the print head may be equal in size to the media. For example, a direct thermal printer for a cash register may have a width equal to a roll of thermal media to be printed. Such implementations may be cheap and efficient, but require fixed-width media, reducing flexibility of use.
Problems appear when a wide print head is used with narrow media. Specifically, an ink print head, such as an inkjet or dot matrix printer may deposit ink on a platen roller beyond the bounds of the narrow media to be printed on, if the travel of the print head is not carefully controlled. Such ink may transfer from the roller to wider media when inserted into the printer, resulting in smudging. Similarly, with a stationary print head, such as in thermal printer, the print head may transfer heat to the platen roller, degrading the rubber material and/or reducing efficiency of thermal transfer.
In some embodiments of printers, a print head such as a thermal print head may be bowed or have a curvature in a direction perpendicular to the plane of the media to be printed. This may be due to the method of manufacture or installation of the print head. By dynamically adjusting the pressure of a deflectable platen roller against the print head, the bow may be used to eliminate contact between the print head and roller at locations beyond the width of media.
For example,
Conversely, at high head pressure as shown in
Accordingly, variable head pressure may be applied as in
In some embodiments, head pressure may be adjusted via a screw, attached to the head and threaded through a hole on a supporting frame, or conversely attached to a frame and in contact with the head. The screw may be rotated to vary the bow of the print head. The screw may be adjusted via a motor, in some embodiments. In other embodiments, the screw position may be fixed or calibrated during manufacture and other means may be used for variable head pressure. For example, in one embodiment, the print head may be moved via one or more levers and/or motors against a fixed platen and/or deformable platen having a fixed axis or fulcrum. In another embodiment, the print head may be fixed to the frame and an axis or fulcrum of the platen may be adjusted to provide variable pressure on media between the platen and the print head. For example, the platen may comprise a platen roller, and the axis of the roller may be adjusted by one or more levers supporting the axis. The levers may be moved by a motor to vary the position of the platen roller, moving the roller towards the head to increase pressure or away to decrease pressure. In other embodiments, the platen may comprise a flat or bent plate, such as a spring steel plate. The fulcrum of the plate or a spring support for the plate may be moved via a lever such that the plate presses harder or softer against media and the print head. In some embodiments, the pressure may vary in a linear relationship to the position of the axis or fulcrum of the platen, while in other embodiments, the pressure may vary in a geometric or fashion (such as a platen that increasingly resists deformation as it is deflected, e.g. with a force of F=½kx2 with k depending on the material of the platen and x representing the change in position of the platen; or any other such relationship).
As discussed above, many types of media may include a non-adhesive backing. For example, such media may be used for photos, cards, framed pictures, coupons, receipts, or other uses where an adhesive is either not desirable or is irrelevant. For such uses, a printer may employ a full cutter to be able to cut a continuous spool of media to any length according to the printed image. In other uses, the media may include an adhesive, such as for stickers, labels, or similar uses. During manufacture, a thin backing may be applied to the media, such as a paper layer, to cover the adhesive. A user may peel the backing from the media, exposing the adhesive, and allowing the media to be fixed to a surface. To aid in peeling the media, as well as to perform full-bleed printing as discussed herein, the printer may include a kiss cutter that may cut through the media to the depth of the backing, but leaving the backing uncut or partially uncut. The resulting tab may be used to peel off the backing to expose the adhesive.
For example, shown in
As shown in
As discussed above, printing may be referred to as full-bleed if a printed image extends to the edge of the resulting media. Many printers may be unable to print full bleed images, for example, because of a need to avoid spilling ink onto a platen roller or avoid applying heat to the edges of media that may cause them to curl. Kiss cutting and/or full cutting may be used to achieve full-bleed printing. For example, as shown in the left hand diagram of
Other printers may not need additional lateral space for a print area 900. For example, in some embodiments of direct thermal printers, the print head may extend past the media 302 and be able to print to the edge (and/or slightly beyond the edge) of the media, providing full-bleed printing across the width of the media. Although this may result in heat being transferred from the print head to a platen roller, undesirable effects may be mitigated through variable head pressure as discussed above. However, due to the need for the print head to be in position above the media 302 when printing is started, the printer cannot directly create an image that extends to the cut edge of the media (because the print head would have to start printing before the media reaches the print head, the media could skip or jam against the lowered print head). Accordingly, in some embodiments, kiss cutting and full cutting of the media may be used to allow full bleed printing in a longitudinal direction.
For example, referring first to
As shown, the media 302 may have a portion that is beyond the print head 700 in a start position. Depending on the cutter design, the printer may begin printing the first image 906a and may perform the first kiss cut 908a during printing. However, in many embodiments, the media must be stopped prior to cutting, or the cutting blade may cause a stutter or jerk in the print, resulting in a visual artifact or band. The media may be advanced to the position for cutting, held still while the cut is performed, and then advanced to print the rest of the image, but this may also result in visual artifacts as the speed of the media past the print head 700 may not be constant.
Accordingly, it may be desirable to perform the first cut 908a prior to printing. For example, the printer may advance the media 302 such that a start point on the media is beneath the kiss cutter 800a. The cutter may perform the kiss cut, and the media may be retracted or rewound to return the start point to the print head 700 or slightly beyond the print head. The printer may then print the entire first image 906a. After printing, the media may be advanced such that the kiss cutter 800a may perform cut 908b. To print a second image, the media may be advanced again to perform cut 908c, and then rewound to allow printing of second image 906b. After printing, each full bleed image 906a, 906b may be peeled from a backing of the media. To ensure proper advancement and retraction, during manufacture and calibration of the printer, the distance between a cutter 800a, 800b and the print head 700 may be measured and recorded, such that the printer may advance and retract the media properly.
Thus, as shown in
At step 952, the media may be rewound or retracted so that the print head is positioned at a point before the kiss cut. This will allow printing of the image to begin prior to the kiss cut and overlap the kiss cut, ensuring full bleed printing. The retraction distance may be greater than the distance between the kiss cutter and the print head. In many embodiments, a portion of the media may still be under the print head after retraction, allowing printing without concern about binding or catching against the print head or platen.
At step 954, the printer may print the image. The image may be of any length, and may be dynamically adjusted. For example, as discussed in more detail below, an image may have dimensions of width a and length b, defining an aspect ratio of a: b. Responsive to the width a of media in a cassette inserted into the printer, the length b may be dynamically adjusted to maintain the aspect ratio, allowing the same image to be printed without distortion on any size of media. The image may be text and/or graphics, and may be black and white and/or color.
At step 956, after printing the entire image, the printer may advance the media. The printer may advance the media by a distance less than the distance between the print head and a cutter, such as a kiss cutter or full cutter. This ensures that the cutter will cut through a printed region of the media, ensuring full bleed printing. For example, if there are no subsequent images queued for printing on the same length of media, at step 958, the printer may perform a full cut on the media. Accordingly, at step 956, the printer may advance the media to a distance less than the distance between the print head and the full cutter. Conversely, if there are subsequent images to be printed, then at step 956, the media may be advanced to a distance less than the distance between the print head and the kiss cutter. In both instances, the distance may be a predetermined distance less than the distance between the print head and the corresponding cutter, such as 1 millimeter less, 2 millimeters, or any other value.
As discussed above, if there are no subsequent images to be printed, then at step 958, the media may be fully cut, and the cut segment may be ejected from the printer. Alternately, if there are subsequent images to be printed, then at step 960, the printer may perform a second kiss cut. The media may then be advanced at step 962 by a second predetermined distance to create the tab, as discussed above. The second predetermined distance may be quite small, as a large tab may not be needed between images. Rather, in such instances, the tab may be used merely to provide separation between the kiss cuts to prevent bleed from the first image from interfering with the second image (and preventing bleed from the second image from interfering with the first image). Steps 950-962 may be repeated iteratively for additional prints.
As discussed above, in many embodiments, media cassettes may be provided in various widths, background colors, may have precut lengths, pre-printed borders or label elements, or may include other features. In practice, a user may remove and replace cassettes either when empty of media or while still partially full, to utilize a different width or type of media. Typically, printer heads are in fixed positions relative to the path of media as it advances through the printer from the cassette. Other implementations of printers may have heads that may move across a predetermined path relative to the media, and while having variable positions, may still require alignment with the media. For example, to print properly aligned images with the media (for example, for printing from edge to edge, known as “full bleed” printing), the relative positions of the media and the printing heads must be tightly controlled.
Referring now to
Printing full-bleed images across the width of media, and particularly media that may be significantly smaller than the width of the print head, may require control over lateral displacement of the media and/or control over displacement of the print image within the print head. For example, with a two inch print head and half-inch media, the media may be centered on the print head, or may be displaced from center by a significant amount due to slipping in the transport, misalignment, or other variations. As shown and exaggerated for clarity, with misaligned full bleed printing, the print area 900 may extend off the media 302, resulting in unintentional printing on the platen or other surfaces in inkjet, die diffusion thermal transfer, or similar systems, and misalignment of the image on the media 302. The media may be rotated as shown, and/or may be laterally offset, resulting in an unprinted edge. Similarly, in thermal printing, misalignment may result in undesirable heating of the platen, or heating of print elements that are not in contact with and able to dissipate heat into the media, resulting in higher print element temperatures than desired.
A mechanical solution to this alignment or tracking problem, such as guide rails for the media, may be difficult to implement if the printer has to deal with different size cassettes with multiple media widths and frequent swapping of these cassettes by the user. The usual solution of having a fixed width edge guide to steer the media as it is transported from the opening of the cassette to the print-head to the exit chute is not possible in such scenarios. Variable width edge guides that adjust to the width of the inserted media cassette may not be feasible to implement in an inexpensive printer and do not eliminate the problem completely. Furthermore, manufacturing tolerances in the slitting of the media and the printer parts that mate with the cassette also make it impractical for a purely mechanical solution to be effective.
If the tracking of the media is not controlled at it passes under the print-head, the printed image will move with respect to the edges of the media. For full bleed images, this leads to a loss of image content near one edge or the other. For other label images with a frame around the central content, the variable placement with respect to the media edges is readily noticeable to the user and results in unacceptable quality prints.
One solution is to track the edge of the media as it passes under the print-head and then electronically shift the image such that the relative position of the image with respect to the edges of the media stays constant. This requires a dedicated sensor that is dynamically positioned as a new cassette is loaded by the user. The dedicated sensor and its variable positioning leads to increased hardware cost and makes this a less desirable option.
Instead of expensive dedicated sensors, inexpensive sensors may be employed with the use of a tracking pattern that is preprinted on media. Specifically, a pattern may be printed on the back side of the media that may comprise distinct features at angles to each other, such as horizontal and diagonal lines of a “Z” pattern. A sensor such as an optical media-detect sensor may register the distinct features of the pattern as the media is translated along the print path. As the sensor traverses the length of the media, the distance between the distinct features of the pattern varies continuously. The difference of this distance encodes the cross-web position of the media as it passes under the sensor while their sum provides invariance to the translation speed v of the media.
Referring now to
As shown, as the media passes the sensor 1002, the sensor may detect printed and non-printed areas of the pattern along a straight read line 1004. Referring now to the graph of
Conversely, with the media out of alignment as shown in
Due to the symmetry of lines in the example pattern used for
Other alignment patterns may be used incorporating the above features. For example,
In many embodiments, a sensor 1002 may have an aperture larger than an alignment pattern feature. For example, an alignment pattern 1000 may include lines of, for example, 1 mm in width. However, an optical sensor with an aperture of, for example, 5 mm, may be used in some embodiments. Accordingly, in such embodiments, the sensor will not reach full saturation during scanning. Illustrated in
As shown, in many embodiments, due to a difference in thickness between horizontal elements and diagonal elements in the alignment pattern and the sensor aperture being larger than pattern elements, amplitude of the sensor output when reading the wider features may be higher than amplitude of the sensor output when reading narrow features. These differences in amplitude may be used to determine whether the sensor is reading a horizontal feature or diagonal feature of the pattern, by identifying whether the amplitude of the sensor output is above or below a threshold. The threshold may be predetermined, or may be dynamically determined based off of average values or a weighted average of one or more previous readings, or other similar algorithms.
In some embodiments utilizing a sensor with a wider aperture than normal alignment pattern features, an alignment pattern may include a wider feature to represent an approaching end of the roll of media. The printer 100, 200 may use the end of roll detection to prevent printing an image that is longer than the remaining length of blank media.
To further illustrate media and printing alignment,
Let Δt1 and Δt2 denote the time elapsed between registering a horizontal line followed by a diagonal line and a diagonal line followed by a horizontal line respectively. Although measured as a series of discrete values upon reading each line, Δt1 and Δt2 may be thought of as points on a smooth time-dependent curve. Thus, for example, tracking T(t) 1103 (such as the illustrated distance between horizontal arrows T(t5) 1103 at t5) represents the cross-web distance between the center of the print-head (or location of the sensor) and the center of the “Z” pattern, and may be determined directly at points corresponding to detected lines, or may be interpolated at any point (e.g. t5) based on the smooth time-dependent curve. Letting Zw represent the width of the “Z” pattern 1100 and φ represent the angle between the horizontal and diagonal line, the value of T(t) can be computed from the geometry of the pattern as follows:
where
Let δx denote the root-mean-square (RMS) noise in determining the location of the individual lines of the “Z”. Eq. (2) may then be used to determine the RMS noise δT and the signal-to-noise ratio (SNR) of the tracking signal:
SNR scales with tan(φ), such that small values of φ result in reduced SNR for the tracking signal. However, small values of Zw tan(φ) increase the sampling frequency of the tracking, yielding a better reconstruction of the dynamic tracking when it is quickly varying. Accordingly, there is a design trade-off, in which both φ and Zw are design parameters controlling a balance between tracking range, dynamic reconstruction, and SNR.
Let y denote the signal amplitude measured by the optical sensor. Although the measurements are made in time as the media moves by the sensor, the measurements may also be represented as functions of distance down the media x. Accordingly, y(t) and y(x) may be used interchangeably assuming x=
Referring briefly ahead,
In many embodiments, the signal from the sensor may be digitized to form a stream of digital samples representative of the sensor output. In the presence of noise, detecting the peaks by simply comparing the value of each sample to its immediate neighbors to determine a local maxima is not robust. Instead, in some embodiments, a model is employed to smooth out the measurements facilitating a robust detection and localization of the peaks. Let q(•,x0) denote a second order polynomial around location x0 given as
q(x,x0)=a(x0)(x−x0)2+b(x0)(x−x0)+c(x0) Eq. (4)
The coefficients a(•), b(•), and c(•) are parameters of the polynomial and are adjusted for each location x0 such that
y(x)≈q(x,x0),xε(x0) Eq. (5)
where (x0) denotes a set of x values in the local neighborhood of x0. Using Eqs. (4) and (5), the polynomial coefficients can be interpreted as
Therefore c(x0) may be considered the smoothed modeled value of the measurement at x0, b(x0) the first derivative, and a(x0) half of the second derivative of the model curve. The model may be accordingly described as a truncated Taylor series representation of the measurements. Enforcing the relationship of Eq. (5) in a least-squares sense, the estimation of the coefficients at each location x0 is given as
Let Δx denote the sampling interval in x for the measurements. The neighborhood (x0) is defined to be 2N+1 samples around x0, i.e.,
(x0)={x:|x−x0≦NΔx} Eq. (10)
Then the least-squares solution to Eq. (9) can be written in closed form as
where the matrix A is given as
and the vector {right arrow over (y)}(x0) contains the local sampling of y
To obtain the smoothed measurements and its derivatives given by Eqs. (6)-(8), an efficient method is needed to compute the solution of Eq. (11) at every location. Towards this end, note that the matrix
F=(AtA)−1At Eq. (14)
is independent of the location x0 and therefore only needs to be computed once and stored for subsequent use. Also, even though the data model is non-linear in x, the solution is linear in the measurements and is obtained by a dot-product of the rows of the matrix F with a sliding window of the measurements given by {right arrow over (y)}(x0). This can be implemented as a 2N+1 tap finite impulse response (FIR) filter on the stream of incoming measurements. Additional computational savings result from the fact that the filters are symmetric about their center point by construction. Using this property, each filtered data point can be obtained with only N multiplies and 2N adds.
The FIR filters are obtained from the rows of the matrix F, with each row reversed in the order of elements. Plot (a) in
In practice, the quadratic fit to the measurements gets progressively worse as N increases. Consequently, it is desirable to deemphasize the influence of the data points further away from the center point. In some embodiments, this is accomplished by a weighting function that modulates the cost of the error in the least-squares fitting process as a function of distance from x0. This may be referred to as applying a windowing function to the measurements. In one embodiment, a Blackman window is applied for the weights w(•) given as
Let W denote the diagonal matrix constructed from the weights
The filter matrix F for solving the weighted least-squares solution to Eq. (9) may be expressed as
F=(AtWA)−1AtW Eq. (17)
Plot (b) in
Ideally, the first derivative will be zero and the second derivative will be negative only at a peak location. However, in practice, this is not sufficient as seen in
Peak detected:b(xl)b(xr)<0,a(xl)<<0,a(xr)<<0 Eq. (18)
In one embodiment, peaks may be detected through interpolation of the b values, by fitting a straight line to b between xl and xr and determining the exact location xp of the zero-crossing of the peak as follows:
This method works well when the sampling interval Δx is small enough that b can be approximated as a straight line between the two samples.
However, when the sampling interval is large, in many embodiments higher accuracy may be achieved by determining the maxima of the fitted model q(•,xl) and q(•,xr). Setting the first derivative of Eq. (4) to zero and solving for x yields:
In general, the location of the maxima may differ slightly between the two consecutive fits at xl and xr. Accordingly, in some embodiments, the average of and xv, may be used to find the peak xp=(xpl+xpr)/2.
Once a peak location is determined, in some embodiments, both the a and c values may be passed to the classification module at step 1160 for determining whether the peaks correspond to a horizontal or a diagonal line of the Z pattern.
Peak Classification
In some embodiments, the detected peaks may need to be classified as a horizontal or a diagonal line of the “Z” pattern, for example, to detect whether lateral displacement of the media is to the left or right. In some embodiments, as discussed above, the horizontal and diagonal lines may have different thicknesses. In other embodiments, other distinct features may be used, such as patterning or saturation of the line. Depending on the thickness of these two line types or other such features and the shape of the aperture of the optical sensor, both the amplitude and the width of the recorded peaks may vary between horizontal and diagonal lines. The c coefficient captures the amplitude while the second derivative a captures the width and the curvature of the peak. In some embodiments, these two coefficients, a and c, computed at the peak locations may be used as features to classify the peaks.
If the “Z” pattern is clean with no extraneous marks such as smudges or dirt on the media 302 and the amplitude of the tracking is not large enough such that the horizontal and diagonal lines merge at the corners of the “Z”, then a two-class Bayes classifier or similar algorithm may be applied. If dirt or other unintended markings on the media are present, then the sensor may register a peak that does not correspond to the horizontal or diagonal line. In such instances, a multi-class classification algorithm, discussed in more detail below, may be applied.
Two-Class Bayes Classifier
Let denote a feature vector made up of the set of valid classes. For the two class problem,
={‘d’, ‘h’}, where ‘d’ and ‘h’ denote the diagonal and horizontal line class respectively. Let {circumflex over (l)}p denote the estimated line type for the pth peak located at xp and let
denote the feature vector made up of the “a” and “c” coefficients described above. The minimum classification error may be obtained by maximizing the posterior probability of the line type, given the observed features
Using Bayes rule and taking the logarithm of Eq. (22), the equation
is obtained where P(l) denotes the a priori probability of line type l.
The probability distribution of the features given the line type may be modeled as a multi-variate Gaussian distribution. Letting {right arrow over (m)}l denote the mean value of the feature vectors, and Σl denote the covariance matrix of the Gaussian distribution for lines of type l, the general form of the decision boundary of Eq. (23) for Gaussian distributions may be
where the pth line is assigned the type {circumflex over (l)}p=d (diagonal) when the <inequality is satisfied and {circumflex over (l)}p=h (horizontal) when the > inequality is satisfied. This is a quadratic function in feature space. If the covariance of the two class distributions can be modeled to be equal, Σ=Σd=Σh, then the decision boundary simplifies to a line in feature space
In some embodiments, if there is dirt or other unintended markings on the media, the sensor may register a peak that does not correspond to the horizontal or diagonal line. Forcing the classification to either of the two known classes may result in an error and throw the tracking estimate off. The probability distribution of the all the peaks that are not the horizontal or the diagonal line is unknown and cannot be quantified using the two-class algorithm discussed above. Instead, in such embodiments, a threshold may be applied to the likelihood of a peak corresponding to the two known classes. The unknown class ‘u’ is chosen when these likelihoods fall below the threshold. The classification to the known classes is then the same as discussed above. The overall decision rule is given as
For the special case of equal a priori probabilities and diagonal covariance matrices, the classification rule reduces to computing and comparing weighted distances of the sample to the class means as follows:
The “Z” pattern by itself in the absence of dirt or other unintended marks yields a very predictable pattern of alternating horizontal and diagonal lines. The a priori probability P(l) discussed above considers each peak in isolation and completely ignores this correlation. Leveraging this information can significantly improve classification accuracy in the presence of noise.
Let {right arrow over (l)}l,n=(l1, . . . , ln) denote the vector of line types for lines with indices 1 to n. The joint probability of the line types may be modeled by the Markov chain
The model is thus completely defined by transition probabilities from the state at index p to index p+1.
Diagram (c) of
For best performance, the classification needs to be done for a block of line types rather than one at a time. However, waiting to classify a peak until additional peaks are observed may result in a delay that may be unacceptable in a real-time tracking application (although it may be used in an off-line initialization sequence). The block classifier is obtained as
The optimization of Eq. (29) may involve evaluating dn class assignments to {right arrow over (l)}1,n, where d is the number of possible classes. This can be reduced to O(d2n) computations employing a Viterbi algorithm that does a forward pass keeping track of d paths that achieve the maximum probability through the n stages and a backward pass to compute the optimal class assignments.
For reduced block sizes, the probabilities may be conditioned on the class determinations for the previous indices. For a block size of 1, the Bayes classifier is given as
Comparing to Eq. (23), the a priori probability P(l) is simply replaced by the transition probability from the previously determined optimal class to the current class. Note that Eq. (23) when computed on the model shown in diagram (a) of
At (a),
The resulting signal is shown in the exemplary plot of FIG. 11K(b), showing the voltage recorded by the sensor (line) and peaks (circles and crosses) identified by the classifier. The paper has tracked to an extreme location as shown by the sensor path resulting in the diagonal peaks merging with the horizontal peaks in the first half of the recording. The peaks get progressively more resolved in the latter half of the recording as the media tracks towards the center. The peak finding algorithm is able to resolve all the peaks (marked by crosses and circles).
The a coefficients of each of the peaks are plotted in FIG. 11L(a), with circles representing coefficients for horizontal lines, and crosses representing coefficients for diagonal lines. The dashed line of FIG. 11L(a) and FIG. 11L(b), discussed in more detail below, illustrates a threshold for the classifier, determined as the a value where the two classes have the same probability. In an off-line initialization sequence, the probably distribution of the two classes will not be known and may need to be estimated from this data. A clustering algorithm such as k-means can be used to sub-divide the a coefficients into two groups. The probability distribution for each of the two horizontal groups can then be computed as discussed below.
FIG. 11L(b) shows the estimated Gaussian distributions for the horizontal (solid line) and diagonal (line with crosses) classes. Since this is a one-dimensional classification problem with only one feature, the decision boundary is a simple threshold obtained as the value of a where the probability of the two classes are equal, illustrated as the dashed line in FIGS. 11L(a) and 11L(b). The resulting classification misclassifies a number of the horizontal peaks as diagonal peaks. The a values of the horizontal peaks are artificially elevated due to the merging of the peaks and fall in the region occupied by the diagonal peaks. Accordingly, in such embodiments using the classifier of Eq. (23), it may not be possible to correctly classify all the peaks correctly, because the classifier only looks at one sample at a time and classifies it based on the two class distribution. To remedy this, in some embodiments, a priori knowledge of the repeating patterns of horizontal and diagonal lines may be leveraged. For the distinct Z pattern of FIG. 11K(a), the leading and trailing horizontal lines of each “Z” may be represented by two distinct classes, namely ‘h1’ and ‘h2’, yielding the state transition diagram of
To compute the data probabilities, mean and covariance parameters of the Gaussian distribution for each class are utilized. These can be estimated from sample averages given labeled training data in which the class of each line type is known. Given n labeled samples, the mean and covariance estimators are
where the indicator function
and Nl denotes the number of samples of class l out of the n samples,
In typical usage, the characteristics of the printer transport and the response of the optical sensor may drift with time. Each run of the media may also have variations in the printed “Z” pattern. Both of these factors may cause the class distributions in feature space to vary over time. Consequently, in some embodiments, it may be desirable to dynamically update the parameters of the classifier to track these changing characteristics. This can be done by using the previously classified samples as ground truth. As long as the parameters do not change abruptly, this circular method of the using the classifier to classify the samples and then using the classified samples to update the classifier parameters does not pose any problems. The mean estimator {right arrow over ({circumflex over (m)}1 of each class l given by Eq. (31) can be adapted to update when a new sample arrives with class {circumflex over (l)}=l as
Eq. 35 is thus a weighted sum of the previous mean estimate and the new sample. However, the contribution of the new samples to the class mean are reduced in weight as more samples are collected and Nl increases. In order to make this computation adaptive, the result of Eq. (35) is replaced by:
e
−1/τ
{right arrow over ({circumflex over (m)}(n−1)+(1−e−1/τ){right arrow over (f)}n Eq. (36)
This is a recursive update yielding a one-tap infinite impulse response (IIR) filter with τ as a constant that determines the number of samples it takes to erase the memory of the previous samples. Small values of τ enable the filter to adapt quickly to newer samples whereas large value does the opposite. Note that the update does nothing, {right arrow over ({circumflex over (m)}1(n)={right arrow over ({circumflex over (m)}(n−1), when {circumflex over (l)}n≠l. Similarly, the IIR filter for the covariance matrix can be obtained from Eq. (32) as
In some embodiments, once a diagonal line is identified in between two horizontal lines, the tracking can be computed using Eq. (1). This gives a discrete sampling of the continuous tracking of the media at the location of the diagonal line as follows:
In some embodiments, the estimate above may be delayed with respect to where the print head is printing due to a need to wait to complete the “Z”. It may also be discrete as samples are obtained only at the diagonal line locations. Accordingly, it may be preferable to generate a continuous estimate that predicts the tracking in the future to minimize the tracking error appearing on the print. This may be achieved in two parts: a model based predictor that predicts the tracking in the future that may be discontinuous as new samples come in and an IIR filter that smoothly incorporates this potentially discontinuous predictor into a smooth continuous estimate of the tracking.
In some embodiments, the tracking predictor may be based on a polynomial model fitted to the last r discrete estimates of the tracking obtained using Eq. (38). The support r of the model-based predictor controls how quickly the predictor adapts to changing tracking estimates. For book keeping purposes, a time varying set Tt may include the last r tracking estimates at any given time t and their corresponding locations. The set Tt may be updated whenever a new tracking estimate is available with the latest value replacing the oldest value in the set such that the number of elements in the set remains constant at r.
The order of the fitted polynomial is another design parameter; higher order polynomials can give better fits to the tracking estimates of the past but in general do not give robust prediction estimates for the future. For this reason, in some embodiments, linear fits (i.e. first order) may be employed. If the support r is chosen small enough to ensure that the tracking is more or less linear over this support, the model will provide sufficient accuracy for the tracking data and robust prediction capability. The parameters of the linear fit, namely, slope s and offset o can be obtained by a least-squares fit to the data in Tt. The parameters will therefore be functions of time t and change abruptly when a new tracking estimate becomes available and Tt is updated. The model-based tracking predictor is given as
{circumflex over (T)}
m(x)=ŝ(t)x+ô(
t) Eq. (39)
explicitly showing the dependence of the estimate parameters, ŝ and ô on time t via the set Tt. Note that this predictor will most probably be discontinuous in x when a new tracking estimate is obtained and the parameters of the fit are recomputed. To obtain a smooth continuous prediction, {circumflex over (T)}m(x) is fed into a one tap IIR filter that operates at the sampling interval Δx as
{circumflex over (T)}(iΔx)=e−Δx/β{circumflex over (T)}((i−1)Δx)+(1−e−Δx/β){circumflex over (T)}m(iΔx) Eq. (40)
where β is the space constant of the IIR filter in distance units and controls how quickly the filter reacts to changes in {circumflex over (T)}m(•). It trades off the bias versus variance of the tracking prediction.
While estimating the parameters s and o of the linear predictor, in some embodiments, the tracking estimate data in Tt may be weighted to give more weight to the more recent estimates as compared to the older estimates. This improves the accuracy of the predictor as the most recent samples better reflect what the estimate is going to be in the future. [1−r2/(r+1)2, 1−(r−1)2/(r+1)2, . . . , 1−1/(r+1)2] was used as the weighting for the r samples ordered from oldest to most recent.
When first starting up, in many embodiments, the print engine will not have any tracking data available to estimate the parameters of the linear predictor. It will also take time to have the full complement of r samples for the full support of the predictor. So in the initial portion of the prediction, the print engine works with whatever number of samples are available until reaching the support of r samples after which it starts to discard the older samples from Tt. This is seen in plot (b) of
{circumflex over (T)}(ioΔx)={circumflex over (T)}m(ioΔx) Eq. (41)
where i0 is the first sample index where the predictor {circumflex over (T)}m has valid data.
To compensate for the tracking of the media, in some embodiments, the print engine may shift the printed image by the amount predicted by the IIR filter {circumflex over (T)} of Eq. (40). This shift may be implemented by re-interpolating the image on a grid displaced from the original grid by the predicted tracking {circumflex over (T)}. However, this re-interpolation may be quite computationally intensive to perform for every line of the image. To reduce the computational burden, in some embodiments, the image shifts may be limited to a full pixel or a half pixel shift. However, such shifts may be more readily apparent to the eye. To mask these shifts, in some embodiments, the print engine may employ a technique known as dithering in which a high frequency noise pattern is added to the tracking estimates before quantization. This may effectively achieve finer quantization intervals leveraging the smoothing that will be performed by the eye when the print is viewed.
Let d be the length of the dither pattern and D denote the array of dither (noise) values. Let AT denote the quantization interval. The quantized tracking estimate
In some embodiments, the tracking set T(t) as measured by the optical sensor may differ from the true tracking of the media with respect to the print-head due to positioning errors in the sensor and the “Z” markings on the media. This leads to a static and dynamic tracking offset in the measurements; the former can be corrected via a calibration whereas the latter may not be as easily corrected and could result in an uncontrolled error. Systems and methods for addressing these errors are discussed below, in which Tp(t) is used to denote the true tracking of the print with respect to the print head.
Although in many embodiments the Z's or similar pattern are intended to be centered on the media and the optical sensor designed to be centered with respect to the print head, in practice, this might not be so given some tolerance in the printing of the Z's as well as manufacturing tolerances in the printer hardware. Let Tz and Ts denote the cross-web offset between the center of the media and the “Z” pattern and the center of print-head and the sensor respectively. The offset Tz is positive when Z's are shifted right with respect to the center of the media 302 when viewed from the underside (the side on which the Z's are printed) of the media with the leading edge of the print at the top. The offset Ts is positive when the sensor is shifted right with respect to the print head when viewed from the print-side and the leading edge of the print at the top. With this sign convention, Tz and Ts will be additive offsets to the measured tracking to obtain the final tracking of the print with respect to the print-head. Eq. (43) discussed below lists these as static offsets in the tracking measurements that can be calibrated out for each printer and media run.
In addition to the cross-web offset Ts, the sensor will generally have an offset in the down-web direction denoted as xs, as it may not be physically coincident with the print head in some embodiments (for example, a platen may be coincident with the print head to support media 302 during printing). In other embodiments, the sensor may be coincident with the print head, where media 302 is not required to be supported during printing. In practice, this offset may be quite large since the optical sensor may perform multiple functions (e.g. as a paper sensor) and its position may be chosen to optimize some other functionality. This down-web sensor offset can manifest itself as a tracking offset when the media is fed at an angle to the print-head. For example,
The measurements are both scaled and offset from the true value. In general, angle θ may vary during the print leading to a dynamic offset and scaling in the tracking values. In many embodiments, it may not be possible to measure the angle θ with a single sensor. In such embodiments, if it is assumed that angle θ is the sole source of the media tracking offset (as opposed to lateral translation), we may estimate θ from the measurements as
and correct for this error as well. In many embodiments, the offset xs may be quite small to minimize the magnitude of the error.
The printed Z offset can be estimated by scanning the back side of the media as discussed above. Although it's possible that the offset Tz can vary down the length of the media, typically, the offset may be lateral and lack any angular component. Accordingly, in such instances, the offset may remain more or less constant within some tolerance and the print engine may just estimate the average offset once per coated lane of the media.
Referring briefly ahead to
In order to calibrate the cross-web position of the sensor, the true tracking Tp(•) is measured in addition to the tracking measured by the sensor. Briefly referring to
Once the image 1180 is printed and scanned, image processing is employed to localize the edges of the prints (shown as black large dotted lines) and the tick marks 1182 (shown as grey dots.) The longitudinal edges of image 1180 are again constrained to be parallel. By measuring the distance of the grey dots 1182 with respect to the dotted black lines, the true tracking experienced by the print {circumflex over (T)}p can be estimated. The sensor offset can then be computed from Eq. (42) as
{circumflex over (T)}
s=mean({circumflex over (T)}p(•))−mean({circumflex over (T)}(•))−{circumflex over (T)}z Eq. (45)
where it is assumed that the media angle into the print head θ≈0.
At step 1252, the printer may advance the printing medium by a first distance or for a first time period. The printer may advance the printing medium by a predetermined distance or may continuously advance the medium at a set speed during printing, which may be dependent on print settings (e.g. draft or fine mode).
At step 1254, the printer may identify or detect a second line. In some embodiments, the sensor output for the second line may have a higher or lower amplitude, or may have a longer or shorter sustained output, which may allow the printer to distinguish between the first line and second line in the alignment pattern. In some embodiments, the printer may skip steps 1256 and 1258, as the distance between two successive lines may be enough to identify an offset and direction, depending on the pattern.
At step 1256, the printer may advance the printing medium by a second distance or for a second time period, as discussed above, and at step 1258, the printer may identify or detect a third line. The printer may determine if there is a difference between the first time period or distance and second time period or distance. If there is no difference, then the printer may identify the media as being properly aligned, and repeat steps 1256-1258. If there is a difference, then the printer may identify the horizontal offset proportional to the difference between the first time period and second time period. As discussed above, in embodiments with a distinct first line and second line, the printer may further identify the direction of the offset based on whether the difference is positive or negative. The printer may apply a horizontal shift in printing of the image at step 1260 corresponding to the offset and repeat steps 1252-1256.
Although discussed above with the alignment pattern centered on the media, the alignment pattern does not necessarily have to be centered. For example, if the alignment pattern is offset to one side during manufacture, the memory of the cassette may be configured with a default offset value for the cassette which may be added to or subtracted from any identified offset determined by the printer via the alignment pattern. For example, if the alignment pattern is 15 pixels to the left of center of the media, then a +15 modifier may be stored on the card and added to an identified offset of −15 if the media is properly aligned, resulting in a net of zero and not causing the printer to adjust printing output. Thus, centering of the alignment pattern need not actually be necessary during manufacture or printing, provided it is consistent within the roll of media.
In some embodiments of printers 100, 200, the printer may heat up during use. For example and as discussed above, a thermal printer may heat up resistive print elements to print pixels and/or activate color-forming dyes in a print medium. Additionally, to print quickly, the thermal printer may preheat the print elements to a temperature above ambient temperature but below a temperature at which a first color-forming dye is activated, reducing the amount of additional energy needed to print a pixel. For example, if a first color-forming dye becomes activated at a temperature of 90 degrees Celsius for a predetermined time, by preheating print elements to a temperature of, for example, 30 degrees Celsius, the printer need only raise the elements another sixty degrees to begin printing the pixel rather than the seventy degrees needed from a room temperature of 20 degrees Celsius. Although this may seem like a minor difference, it may be important for high speed printing, particularly with dyes that require heat at an activation temperature for an extended period of time. Because the ambient temperature is closer to this activation temperature, the dye may be raised to activation temperature more quickly, resulting in reduced or eliminated activation of other dyes as heat transfers through the medium). Similarly, ink jet printers may include heating elements to heat ink to ensure proper flow. However, if the ambient temperature around the print head becomes too high and/or if the heating elements or print head cannot shed heat quickly enough, a thermal printer may be unable to avoid printing a pixel where a blank space is required or pixels may be oversaturated or performance of electronic components in the print head such as driver chips may degrade, or a lower-activation temperature color may be accidentally activated while printing a pixel of a higher-activation temperature color, or ink may congeal, and the printer may have to pause before printing to cool off or delay printing the subsequent print. Although referred to as overheating, in many embodiments, such temperatures may not cause damage to the unit but may degrade printing quality. For example, if the ambient temperature within a thermal printer is too high, color-forming dyes in the media may be activated by such ambient temperature, resulting in over-saturated colors, spurious colors, darkening, or other undesirable visual artifacts. Accordingly, many printers incorporate a heat sink or reservoir to transfer heat from the print head.
If the printer's heat sink is undersized, the printer may overheat quickly, resulting in reduced printing time before pausing to cool. However, if the heat sink is oversized, the printer may take a long time to preheat one or more print elements. For example, illustrated in
To solve these contrasting requirements of quick-preheating and slow-overheating, a hybrid heat sink or dual time-constant heat sink 1300c may be employed. The print head heat sink or a portion of the heat sink in contact with the print head with a first time constant may allow a head temperature to rise quickly to a first temperature allowing quick preheating. As shown in
Additionally, during printing of images that have different densities laterally across the media, the print head may heat unevenly, with one end of the print head being hotter than the other end, or one position on the print head may have a temperature different from another position, complicating control of print density. Accordingly, a hybrid heat sink or print head heat sink having a fast time-constant in the vicinity of the heaters may allow heat to diffuse quickly across the print head, reducing or eliminating these temperature variations.
Insulator 1314 may comprise any type and form of static or dynamic thermal insulator for preventing or resisting the initial flow of heat from small heat sink 1312 to large heat sink 1316. For example, in one embodiment, insulator 1314 may comprise an air gap. Large heat sink 1316 may be separated from small heat sink 1312 by the air gap during preheating, and when the printer is ready to print, the large heat sink 1316 may be moved into position against small heat sink 1312. This may require an additional motor or lever to move the heat sink. In other embodiments, a bimetallic strip or passive thermosensitive switch attached to the small heat sink 1312 or print head may bend due to a rise in temperature and contact large heat sink 1316, providing a path for shedding excess heat. In other embodiments, magnets or electromagnets may be employed to move large heat sink 1316 and small heat sink 1312 into contact.
In other embodiments, insulator 1314 may comprise a material with a low thermal conductivity or conductivity lower than that of aluminum, such as brass, nickel, iron, steel, plastic, glass, or any other type and form of material or combination of materials. For example, insulator 1314 may have a thermal conductivity of between 0.1 and 0.6 W/mK, compared to a thermal conductivity of around 200 W/mK for aluminum alloys. In use, the small heat sink 1312 may quickly heat up with the print head 700 during use. Insulator 1314 may prevent energy from flowing quickly into large heat sink 1316. However, once the printer has overheated and printing is paused, the large heat sink 1316 may quickly shed heat, reducing the time during which the printer needs to be paused. Additionally, in practice and when not printing fully saturated images, as the print head 700 is not on at all times, the large heat sink 1312 provides significant cooling of the print head 700 after each print, increasing the time for the print head to reach the overheating temperature 1310.
In still other embodiments, insulator 1314 may comprise a controllable heat pipe or other such element allowing the heat sink to be “switched” on and off, or enabled or disabled dynamically for preheating or printing. For example, flow of a cooling fluid within a heat pipe may be throttled to control cooling.
As discussed above, some printers may include auto-ejection mechanisms to eject printed and cut media. However, in some embodiments, for example due to the small size of the printer, it may not be practical to include an ejection mechanism. For example, some versions of printer 200 may not include an auto-ejection mechanism. Cut media may fall freely from the media ejection slot of the printer, or may be retained within or rest inside the printer. This may cause a problem in unattended printing if full cuts are used, rather than the multiple image kiss cut method discussed above. For example, if a user is printing several images from a tablet computer with full cuts after each image, a previously printed and cut image may impede the forward progress of media during printing. This may cause slippage or stuttering, resulting in visual artifacts or banding on the printed image. Accordingly, with such printers, it may be desirable to ensure that the user is physically present at the printer after printing and cutting the image and may remove the printed media from the printer.
One method of ensuring the user is at the printer may include requiring the user to perform a gesture or movement to cut the media, such as a swipe-to-cut gesture.
Referring now to
As discussed above, if the printer receives multiple images for queuing and printing or is commanded to print multiple copies of an image, the printer may kiss cut the media at step 1454 and advance the media for printing a subsequent image. The printer may repeat steps 1452-1454 for any additional images or copies. In some embodiments, the printer may receive additional images while printing, and may thus repeat steps 1450-1454 as necessary.
At step 1456, the printer may detect activation or touch of a first sensor at a first position. Upon detecting release or deactivation of the first sensor, indicating that the user's finger has moved from the sensor, the printer may initiate a countdown timer of a predetermined time or duration, such as 3 seconds, 5 seconds, or any other value. If no activation of a second sensor at a second position is detected before the timer expires, then the printer may return to step 1456 and wait for activation of a sensor again. In some embodiments, the printer may include multiple sensors and look for release or deactivation of a first sensor and activation of a second sensor within a short time period, and then deactivation of the second sensor and activation of a third sensor within another short time period. Thus, the timer may be reset or multiple timers may be used.
If at step 1458 the printer detects activation of a second sensor at a second position (or motion of the user's finger via multiple sensors or a slider as discussed above to the second position), the printer may, at step 1460, perform a full cut on the media. As discussed above, performing the full cut may comprise advancing or retracting the media into position for cutting. Because the user has just performed the swipe gesture, the user is in physical proximity to the printer at the time of cutting media and may manually remove the media from the printer's media ejection slot.
Additionally, if multiple images are queued for printing, such as multiple address labels, the printer may perform kiss cuts between each image as discussed above. However, at any point during printing, the user may perform the swipe gesture or activate the sensors to command the printer to cut the media. Responsive to detecting the activation or gesture, after completing printing of any currently printing image, the printer may perform a full cut rather than a kiss cut, and then continue printing the queued images or copies. This may allow a user to begin using a cut strip of printed labels while the printer continues with the queue.
In some embodiments, a home button on a printer, such as button 118 shown in
The application may include an edit screen 1504, as shown in
For comparison, these views are shown in
In some embodiments, images may be of an explicit width (e.g. 1 inch), and may be printed only on media of that width or larger. In other embodiments, images may be scaled automatically to match the media inserted into the printer. For example, an image may be created of width x and length y. Width x may be dynamically set before printing to the width of the media in an inserted cassette, and length y may be dynamically calculated based on the aspect ratio. The image may be scaled appropriately and printed as a full-bleed image on the media, regardless of media width. Combining these embodiments, the image may also be generated with an explicit width and scaled if necessary if the inserted media does not match the selected width. For example, referring to
As discussed above, a user may add elements, such as photos, backgrounds, or art or clip-art to an image. Referring now to
To facilitate easy, intuitive editing, dynamic sliders may provide a user the ability to modify border sizes or color selection. For example, referring to
As shown in
As discussed above, a user may enter a default width for creation of an image or may create an image with a default width of x or a similar variable. The user may enter an explicit value for the length of the image, such as 2 inches or 4 inches, or may utilize dynamic length adjustment bands 1518a-1518b to stretch the image, as shown in
When the image is shown in a fit to length mode, as discussed above, dragging a band 1518a, 1518b will change the aspect ratio of the image, causing the displayed width to enlarge or shrink proportionally. Alternately, when the image is shown in a 1:1 scale mode, dragging a band or suspender may cause the image and elements of the image to scroll off the screen, as discussed above.
As shown in
Edited images may be saved to be printed or edited at a later time.
Images may be printed, either from the editing screen 1504 or library selection screen 1520, such as by pressing a print button on the printer (e.g. print button 120 in
As shown in
As shown in
It should be understood that the systems described above may provide multiple ones of any or each of those components and these components may be provided on either a standalone machine or, in some embodiments, on multiple machines in a distributed system. The systems and methods described above may be implemented as a method, apparatus or article of manufacture using programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. In addition, the systems and methods described above may be provided as one or more computer-readable programs embodied on or in one or more articles of manufacture. The term “article of manufacture” as used herein is intended to encompass code or logic accessible from and embedded in one or more computer-readable devices, firmware, programmable logic, memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, SRAMs, etc.), hardware (e.g., integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.), electronic devices, a computer readable non-volatile storage unit (e.g., CD-ROM, floppy disk, hard disk drive, etc.). The article of manufacture may be accessible from a file server providing access to the computer-readable programs via a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. The article of manufacture may be a flash memory card or a magnetic tape. The article of manufacture includes hardware logic as well as software or programmable code embedded in a computer readable medium that is executed by a processor. In general, the computer-readable programs may be implemented in any programming language, such as LISP, PERL, C, C++, C#, PROLOG, or in any byte code language such as JAVA. The software programs may be stored on or in one or more articles of manufacture as object code.
While various embodiments of the methods and systems have been described, these embodiments are exemplary and in no way limit the scope of the described methods or systems. Those having skill in the relevant art can effect changes to form and details of the described methods and systems without departing from the broadest scope of the described methods and systems. Thus, the scope of the methods and systems described herein should not be limited by any of the exemplary embodiments and should be defined in accordance with the accompanying claims and their equivalents.
The present application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/716,303, entitled “Printing Systems and Control Methods,” filed Oct. 19, 2012; and U.S. Provisional Patent Application No. 61/765,311, entitled “Printing Tracking Correction Methods and Systems,” filed Feb. 15, 2013.
| Number | Date | Country | |
|---|---|---|---|
| 61716303 | Oct 2012 | US | |
| 61765311 | Feb 2013 | US |
