This disclosure relates generally to a system for printing on three-dimensional (3D) objects, and more particularly, to systems for evaluating the effect of varying flight distances for ejected drops in such printers.
Commercial article printing typically occurs during the production of the article. For example, ball skins are printed with patterns or logos prior to the ball being completed and inflated. Consequently, a non-production establishment, such as a distribution site or retail store, for example, in a region in which potential product customers support multiple professional or collegiate teams, needs to keep an inventory of products bearing the logos of various teams popular in the area. Ordering the correct number of products for each different logo to maintain the inventory can be problematic.
One way to address these issues in non-production outlets is to keep unprinted versions of the products, and print the patterns or logos on them at the distribution site or retail store. Printers known as direct-to-object (DTO) printers have been developed for printing individual objects. These DTO printers have a plurality of printheads that are typically arranged in a vertical configuration with one printhead over another printhead. These printheads are fixed in orientation. When the objects to be printed are ovoid or shapes having multiple indentations and protrusions, such as balls, water bottles, and the like, printing a complete image on the surface accurately is difficult because portions of the surface of object fall away from the planar face of the printheads. Multiple alignment issues between printheads arise because the ejectors in the printheads eject the marking material across gaps of various distances. The movement of the objects past the printheads taken in conjunction with the various gap distances also affects the coordination of the timing of the signals used to operate the ejectors in the printheads. These issues include the droop in the drops as they cross the gaps, the orientation of the ejectors in the printheads, and the like. For example, the drops from an ejector that is not truly oriented perpendicularly to an object stray further from the intended flight path as the imaging distance increases. Identifying and measuring these effects so the data used to operate the printheads during printing could be modified to compensate for these effects would be beneficial.
An apparatus has been configured to enable a printing system to identify and measure the effects of gap distances on the characteristics of the printhead. The apparatus includes a housing having a cavity with a sloping floor to enclose a triangular volumetric space within the cavity and the housing has a planar surface that surrounds the cavity, and a substrate attached to the planar surface adjacent the cavity and to the sloping floor within the cavity to enable a printhead that extends across a plane parallel to the planar surface of the housing in a cross-process direction to eject drops of material onto the substrate for evaluation of an effect of a changing distance between ejectors in the printhead and the substrate.
A new printing system is configured with an apparatus that enables the printing system to identify and measure the effects of gap distances on the characteristics of the printhead. The printing system includes a plurality of printheads arranged in a two-dimensional array, each printhead being configured to eject marking material, a support member positioned to be parallel to a plane formed by the two-dimensional array of printheads, a member movably mounted to the support member, an actuator operatively connected to the movably mounted member to enable the actuator to move the moveably mounted member along the support member, an apparatus configured to mount to the movably mounted member to enable the object holder to pass the array of printheads as the moveably mounted member moves along the support member. The apparatus includes a housing having a cavity with a sloping floor to enclose a triangular volumetric space within the cavity and the housing has a planar surface that surrounds the cavity, and a substrate attached to the planar surface adjacent the cavity and to the sloping floor within the cavity to enable a printhead that extends across a plane parallel to the planar surface of the housing in a cross-process direction to eject drops of material onto the substrate for evaluation of an effect of a changing distance between ejectors in the printhead and the substrate. The printing system also includes a controller operatively connected to the plurality of printheads and the actuator, the controller being configured to operate the actuator to move the apparatus past the array of printheads and to operate the plurality of printheads to eject marking material onto the apparatus as the apparatus passes the array of printheads.
The foregoing aspects and other features of an apparatus that enables a printing system to identify and measure the effects of gap distances on drops ejected by a printhead in the system are explained in the following description taken in connection with the accompanying drawings.
For a general understanding of the present embodiments, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate like elements.
The support member 108 is positioned to be parallel to a plane formed by the array of printheads and, as shown in the figure, is oriented so one end of the support member 108 is at a higher gravitational potential than the other end of the support member. This orientation enables the printing system 100 to have a smaller footprint than an alternative embodiment that horizontally orients the array of printheads and configures the support member, movably mounted member, and object holder to enable the object holder to pass objects past the horizontally arranged printheads so the printheads can eject marking material downwardly on the objects.
The member 112 is movably mounted to the support member 108 to enable the member to slide along the support member. In some embodiments, the member 112 can move bi-directionally along the support member. In other embodiments, the support member 108 is configured to provide a return path to the lower end of the support member to form a track for the movably mounted member. The actuator 116 is operatively connected to the movably mounted member 112 so the actuator 116 can move the moveably mounted member 112 along the support member 108 and enable the object holder 120 connected to the moveably mounted member 112 to pass the array of printheads 104 in one dimension of the two-dimensional array of printheads. In the embodiment depicted in the figure, the object holder 120 moves an object 122 along the length dimension of the array of printheads 104.
The controller 124 is configured with programmed instructions stored in the memory 128 operatively connected to the controller so the controller can execute the programmed instructions to operate components in the printing system 100. Thus, the controller 124 is configured to operate the actuator 116 to move the object holder 120 past the array of printheads 104 and to operate the array of printheads 104 to eject marking material onto objects held by the object holder 120 as the object holder passes the array of printheads 104. Additionally, the controller 124 is configured to operate the inkjets within the printheads of the array of printheads 104 so they eject drops with larger masses than the masses of drops ejected from such printheads. In one embodiment, the controller 124 operates the inkjets in the printheads of the array of printheads 104 with firing signal waveforms that enable the inkjets to eject drops that produce drops on the object surfaces having a diameter of about seven to about ten mm. This drop size is appreciably larger than the drops typically ejected onto a material receiving surface having a mass of about 21 ng.
The system configuration shown in
An alternative embodiment of the system 100 is shown in
An example of a device 300 useful for identifying the effects of varying distance on the flight paths of ejected drops from printheads in a DTO printer, for example, is shown in
Mounted to the surface of the device 300 is a substrate 316. Substrate 316 is attached to the planar surface of the housing 304 that is adjacent the cavity 308 and to the sloping floor 312 to enable a printhead that extends across the shorter dimension of the cavity 308 in a plane parallel to the planar surface of the housing 304 that surrounds the cavity 308 to eject drops of material onto the substrate for evaluation of an effect of a changing distance between ejectors in the printhead and the substrate. The substrate 316 is configured with fiducial marks 320 and target lines 324. As used in this document, the term “fiducial mark” and “target line” refers to any indicia useful for providing a reference point to analyze a test pattern printed on the substrate. The area of the substrate 316 between fiducial marks 320 and target lines 324 is left blank so the printheads can be operated to eject marking material in this area for comparison to the fiducial marks 320 and the target lines 324. The comparison of the printed lines to the fiducial marks 320 and the target lines 324 enables the deviations of the printed lines from these marks and lines to be measured to identify the effects of the varying distance between the sloping floor 312 and the ejectors in the printheads that formed the lines on the flight paths of the ejected drops. In one embodiment, the fiducial marks 320 are spaced 1 mm apart on a line parallel with the slope of the sloping floor 312 to identify the gap distance between the ejectors and the substrate at that location. The target lines 324 identify the lines that would be printed if the gap distance remained at the distance closest to the printheads, which is the distance of the planar surface of the housing 304 from the face of the printheads in the array 104.
Another embodiment of device 300′ that is useful for identifying a different set of effects of varying distances on the flight paths of drops from printheads in a DTO printer, for example, is shown in
Mounted to the surface of the device 300′ is a substrate 316′. Substrate 316′ is attached to the planar surface of the housing 304′ that is adjacent the cavity 308′ and to the sloping floor 312′ to enable a printhead that extends across the longer dimension of the cavity 308′ in a plane parallel to the planar surface of the housing 304′ that surrounds the cavity 308′ to eject drops of material onto the substrate for evaluation of an effect of a changing distance between ejectors in the printhead and the substrate. The substrate 316′ is configured with fiducial marks 320′ and target lines 324′. The area of the substrate 316′ between fiducial marks 320′ and target lines 324′ is left blank so the printheads can be operated to eject marking material in this area for comparison to the fiducial marks 320′ and the target lines 324′. The comparison of the printed lines to the fiducial marks 320′ and the target lines 324′ enables the deviations of the printed lines from these marks and lines to be measured to identify the effects of the varying distance between the sloping floor 312′ and the ejectors in the printheads that formed the lines on the flight paths of the ejected drops. In one embodiment, the fiducial marks 320′ are spaced 1 mm apart on a line parallel with the slope of the sloping floor 312′ to identify the gap distance between the ejectors and the substrate at that location. The target lines 324′ identify the lines that would be printed if the gap distance remained at the distance closest to the printheads, which is the distance of the planar surface of the housing 304′ from the face of the printheads in the array 104.
The device 300 is useful for identifying characteristics of the printheads for printing objects as the surface of the object slopes away from the printheads in a manner similar to the floor 312. This direction is denoted as the cross-process direction in this document as it is orthogonal to the direction of device 300 movement past the printheads in the plane of the device movement. The device 300′ is useful for identifying characteristics of the printheads for printing objects as the surface of the object slopes away from the printheads in a manner similar to the floor 312′. This direction is denoted as the process direction in this document, which is the direction of device 300′ movement past the printheads.
Device 300 mounts to movably mounted member 212 as shown in
A rear perspective view of the device 300 is shown in
The controller operatively connected to the input device 340 is further configured with programmed instructions stored in a memory to compare the identifier received from the input device 340 of the movably mounted member 212 to identifiers stored in the memory operatively connected to the controller. The controller disables operation of the actuator that moves the member 212 in response to the identifier received from the input device 340 failing to correspond to one of the identifiers stored in the memory. In another embodiment, the controller is further configured with programmed instructions stored in the memory to compare the identifier received from the input device 340 of the movably mounted member 212 to identifiers stored in the memory, and the controller 224 disables operation of the printheads in the array of printheads 204 in response to the identifier failing to correspond to one of the identifiers stored in the memory. In some embodiments, the controller is configured to disable both the actuator that moves the member 212 and the array of printheads 204 in response to the identifier received from the input device 340 failing to match one of the identifiers stored in the memory.
In all of the embodiments that are configured for use device 300 and device 300′, the controller is operatively connected to a user interface, such as the user interface 350 shown in
The sloping floors 312 and 312′ and their opposites enable accurate visualization of the “time-of-flight” droops in the ejected drop paths induced by the increasing gap between the ejectors and the substrate. The lines on the substrate also show how different types of ink, different ejectors within a printhead, and different printheads affect the droop in the drop paths. The different droop rates cause cola to-color mis-registrationat different gap distances. While the printed lines and fiducial marks on the substrate enable immediate intuitive human analysis, the substrates can be detached from the devices and fed through a scanner for optical imaging and computer analysis. The effects identified either by human observation or computer analysis can be used to adjust tonal reproduction curves for the DTO printer. The analysis enabled by the devices 300 and 300′ and their opposites is faster, simpler, and more efficient than obtaining the printing of test patterns on multiple flat substrates and then analyzing the optical images of the multiple substrates printed at a constant gap distance.
The devices 300 and 300′ and the embodiments that having sloping floors in the opposite directions help evaluate any image quality (IQ) artifact that has an angular component in either or both of the process or cross-process directions over various depths. Additionally, the longer the length of the sloping floor enables more accurate measurements to be obtained. This advantage occurs because IQ artifacts arising from angular components provide more information about the artifact as the gap distance increases so as the depth increases the artifact becomes more pronounced. Thus, the effect can be measured more easily without noise, which helps simplify the analysis of the effect for preparation of its compensation.
In operation, an operator can initiate a test or setup mode through the input device of the user interface 350 once a device 300, 300′, or one of the embodiments having floors that slope in the opposite directions is installed on the member 112 or 212, and the controller obtains the data identifying the device from the identification tag on the device. In response, the controller in the printer, such as controller 224, operates an actuator, such as actuator 216, to move the identified device past the printheads as the controller operates the printheads with reference to the type of device being used to eject one or more test patterns onto the substrate on the device. As noted above, a printing system in which the devices 300, 300′ and the embodiments having floors that slope in the opposite directions can be used, an optical sensor 354, such as a digital camera, can be included that is positioned to generate image data of the test pattern on the substrate after the test pattern has been printed. The controller executing programmed instructions analyzes the image data of the test pattern on the media sheet to identify the effects of depth changes on the ejectors in the printheads and develop compensation parameters for improving the alignment of drops from ejectors within printheads or from ejectors in different printheads.
While the DTO printers depicted in
The devices described above with slopes in the process direction and fiducial marks and target lines in the cross-process direction can be used to obtain and quantify image distortion that occurs from compression and expansion of an image arising from linear motion of an object at varying depths in the in-process direction. The devices having slopes in the process direction and the fiducial marks and target lines in the process direction are useful for calibrating printhead firing parameters for the effect of varying depth in the cross-process direction on particular printheads or ejectors. Also, devices with slopes in the process direction and fiducial marks and target lines in the cross-process direction enable drop shifts for particular printheads caused at different depths to be detected and compensation parameters identified. For example, these devices can be used to detect an effect that temperature and depth can have on the path of drops can have on some printheads used in DTO printers. Devices with slopes in either direction at various slopes can be used to quantify the effects of object slope on image quality. Devices with floors that slope in either direction and that have target lines of solid and tinted tone or color patches can be used to quantify tone and color differences at various depths. Also, devices with floors that slope in either direction and that have target lines of fine graphic and type elements can be used to quantify image quality of small features at different depths.
It will be appreciated that variations of the above-disclosed apparatus and other features, and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Although the various embodiments of the devices have been described with reference to a DTO printer, the devices can be used in any printer in which the surfaces to be printed can be placed at different depths from the printheads or in system that use ejector heads at different distances from the material receiving surface, such as a deposition surface. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.
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