The present disclosure relates to an ink cassette and a printer.
In recent years, printing devices that make it possible to easily print photographic image data captured by image capturing devices such as digital cameras and smartphones have become common. A thermal printer, which uses a thermal head, is one example of such a printing device. In a thermal printer, an ink cassette is mounted along a longer direction of the thermal head, which results in a large opening being formed in one side wall portion of a chassis. On the other hand, head shaft support portions which support the thermal head so that the thermal head can be raised/lowered are provided in both side wall portions of the chassis. To print, the thermal head presses against a platen rotatably supported by the chassis, and thus a strong counterforce acts on the head shaft support portions. Because a large opening is formed in the chassis, there is a drastic loss of strength. As a result, the chassis deforms under the counterforce from the pressure of the thermal head during printing, and the desired pressure contact force cannot be applied to the thermal head, which may result in a drop in printing quality.
Japanese Patent Laid-Open No. 2007-229937 discloses a technique for preventing deformation of an ink cassette due to a force generated inside the printer, which prevents a drop in printing quality.
However, the technique disclosed in Japanese Patent Laid-Open No. 2007-229937 cannot compensate for the loss of strength due to the opening formed in the printer main body, which may result in a drop in printing quality.
As provided in more detail below, a loss of strength in a printer main body can be compensated for, and a drop in printing quality can be reduced. An ink cassette and printer may be configured to compensate for a loss of strength in a printer main body and reduce a drop in printing quality.
According to an aspect of the present disclosure, an ink cassette capable of being mounted in a printer includes a supply bobbin on which an ink sheet, that is long and coated with ink, is wound, a winding bobbin on which the ink sheet pulled out from the supply bobbin is wound, a plate member provided on an end part of the ink cassette on a near side of the ink cassette in a mounting direction of the ink cassette, and at least three engaging portions provided in the plate member and configured to engage with engagement portions of the printer when the ink cassette is mounted in the printer, wherein, in a case where the ink sheet, pulled out from the supply bobbin, and a print sheet are overlaid and pressed against a print head of the printer, ink is transferred from the ink sheet to the print sheet.
According to the present disclosure, a loss of strength in a printer main body can be compensated for, and a drop in printing quality can be reduced.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Embodiments will be described hereinafter in detail, with reference to the accompanying drawings. Note that the following embodiments do not limit the disclosure as set forth in the scope of patent claims. Although several features are described in the embodiments, all of these features are not necessarily required for the disclosure, and multiple features may be combined as desired. Furthermore, in the accompanying drawings, the same or similar configurations are given the same reference signs, and redundant descriptions thereof will be omitted.
An example in which the present disclosure is applied in a thermal printer that uses thermal transfer or dye sublimation will be described hereinafter. However, the present disclosure is not limited to a thermal printer or an ink cassette, and can be applied in other types of printers and ink cassettes as well.
Additionally, the present disclosure is not limited to a printer alone, and can be applied in any device having a printing function, such as a copier, a facsimile device, a computer system, or the like. “Recording sheet” according to the present disclosure includes not only paper material, but also sheet materials made from other types of material, such as plastic film or the like.
In a thermal printer, an ink ribbon to which ink is applied (an ink sheet) and recording sheet are pressurized by a thermal head (a print head) and a platen roller (a receiving member), and printing is performed by conveying the ink ribbon and the recording sheet (print sheet) in a state of contact with the thermal head. A plurality of thermal elements (resistance elements) are disposed in a line shape in the thermal head, and an image is printed onto the recording sheet by selectively electrifying the heating elements so as to transfer the ink from the ink ribbon onto the recording sheet. In particular, when printing in full color, yellow (Y) magenta (M), and cyan (C) inks, which are applied to the ink ribbon in order, are superimposed on each other in that order to form a full-color image, and an overcoat (OP) is also transferred onto the image.
In the following descriptions, “printing” is assumed to refer to an overall series of operations, from printing on the basis of a printing instruction from a user, to discharging recording sheet onto which an image has been printed. An “image being printed” is assumed to refer to an operation, among the printing operations, of forming an image on the recording medium by thermally transferring ink from the ink ribbon onto the recording sheet. Note that with monochromatic printing, the recording sheet may be in the form of a roll, and may be discharged after being cut to a predetermined size after an image is printed.
Apparatus Configuration
The overall configuration of a thermal printer according to the present embodiment will be described with reference to
The printer 100 includes a main body case 150, which is an exterior housing member that covers an upper side and a lower side of a printer main body. A cassette cover 110, which is capable of opening and closing, is provided on one side surface of the main body case 150. The cassette cover 110 is capable of opening and closing a cassette mounting portion 130, which is an opening provided in a chassis 120. The ink cassette 300 can be inserted into and removed from the printer 100 through the cassette mounting portion 130. The ink cassette 300 can be mounted, in the direction of an arrow 140, within the printer 100 from the cassette mounting portion 130 of the chassis 120, when the cassette cover 110 is open, and can be removed to the exterior of the printer 100 in the direction opposite from the direction of the arrow 140. The ink cassette 300 contains a long ink ribbon, which is conveyed along with recording sheet 320 when printing an image. The ink cassette 300 will be described in detail later.
A user interface (UI) unit 180, including a display unit 160 and an operating unit 170, is provided in an upper surface of the main body case 150. The display unit 160 includes a plurality of light-emitting elements such as LEDs, and displays an operating state of the printer 100 through colored light, lighting up, flashing, or the like. The operating unit 170 receives operating instructions such as turning the printer 100 on and off. Upon receiving a printing instruction in which a desired image is selected from a host device while the power is on, the printer 100 starts printing according to the printing instruction.
Additionally, an external connection terminal 190 is provided in one side surface of the main body case 150, which makes it possible to use a USB cable or the like to connect an AC adapter and charge a battery provided within the main body case 150, connect an external device such as a digital camera or smartphone, and so on. The printer 100 is capable of receiving image data from a host device connected through the external connection terminal 190 and printing the image data.
Additionally, a tray cover 200, which can be opened and closed, is provided on a bottom surface of the main body case 150, and by opening the tray cover 200, a specified number of sheets of the recording sheet 320 can be loaded into a sheet storage unit 201. A user loads the recording sheet 320 of a specified size into the sheet storage unit 201, and during printing, one sheet is pulled out from the sheet storage unit 201 by a sheet feed mechanism (not shown) of the printer 100. A full-color image is printed by using a thermal head 330 to transfer yellow (Y), magenta (M), and cyan (C) color inks (described later with reference to
The configuration of the ink ribbon 310 will be described next with reference to
In the case of full-color printing, yellow (Y), magenta (M), and cyan (C) color inks are arranged on the ink ribbon 310. A full-color image is formed by overlaying each ink color on the recording sheet 320 to print an image, and an overcoat (OP) surface is furthermore formed on the image. Black band-shaped markers 311 are provided between each color of ink for a purpose of detecting the starting position of each color of ink, and two of the markers are provided at the start of the yellow (Y) surface in order to distinguish yellow from the other colors. The ink ribbon according to the present embodiment uses a highly heat-resistant film, such as polyethylene terephthalate, having a resistance to heat that meets a predetermined level, with a thickness of approximately 2 to 10 or more microns, as a base material. The yellow (Y), magenta (M), and cyan (C) inks are sublimation inks prepared by mixing dyes, binders, plasticizers, binding agents, and the like, and have a thickness of approximately 0.2 to 5 μm on the film. The transparent and colorless overcoat surface is formed by applying a styrose derivative, styrene resin, styrene copolymer resin, a binder, or the like at a thickness of approximately 0.5 to 5 μm. On the surface on the side opposite from the surface to which the ink is applied, a lubricant is applied to reduce frictional resistance with the thermal head and stabilize the travel of the ink ribbon, an abrasive agent is applied to polish and clean the surface of the thermal head, and so on.
A sequence of operations performed when the printer 100 according to the present embodiment prints will be described next with reference to
When the user sets the ink cassette 300 in the printer 100, loads the recording sheet 320 into the sheet storage unit 201, and turns the power on using the operating unit 170, the printer 100 enters the standby state. When, in the standby state, image data begins being received from a host device, the LED of the display unit 160 flashes to indicate that the data is being loaded. The printer 100 includes the thermal head 330 and a platen roller 340. In the thermal head 330, a head arm 331 is rotatably supported by a head support shaft 332, and is biased by a head raising spring 333 in what is the clockwise direction in the drawings. The thermal head 330 is restricted to a position that maximizes the distance from the platen roller 340 so as not to interfere with the ink cassette 300 during mounting.
Next, when the image data has been successfully received from the host device, and the LED in the display unit 160 switches from flashing to being constantly on, the printing operations by the printer 100 start (step S101). Upon the printing operations being started, the printer 100 uses a driving mechanism (not shown) to cause the thermal head 330 to rotate, in what is the counterclockwise direction in the drawings, about the head support shaft 332, against a biasing force produced by the head raising spring 333. As illustrated in
Once it is confirmed that there are no issues with the sheet feed operations, the pressure plate 370 is rotated to the standby state illustrated in
During the cueing operations, the ink ribbon 310 is conveyed at a faster speed than the printing in order to reduce the amount of time required for printing. That is, the speed at which the supply bobbin 302 rotates increases, which increases inertia. As described above, the conveyance of the ink ribbon 310 stops when the markers 311 provided in the ink ribbon 310 are detected, but the supply bobbin 302 will try to keep rotating due to its own weight and inertia produced by the wound ink ribbon 310. If the supply bobbin 302 continues rotating, an unneeded part of the ink ribbon 310 will be pulled out, which causes issues such as ink ribbon jams and the like. To prevent this, the supply bobbin 302 is provided with a sliding part that produces a small amount of rotational resistance.
Once the cueing of the yellow (Y) part is complete, the thermal head 330 is rotated further about the head support shaft 332 in what is the counterclockwise direction in the drawings, and moves to a printing position, in which the ink ribbon 310 and the recording sheet 320 are tightly held between the thermal head 330 and the platen roller 340 (step S108). Once the thermal head 330 has moved to the printing position, the recording sheet 320 and the ink ribbon 310 remain tightly held between the thermal head 330 and the platen roller 340, as illustrated in
When an image is printed as a result of the heating performed by the thermal head 330, the ink ribbon 310 and the recording sheet 320 are conveyed for a set distance while remaining in a state of close contact, and are then conveyed in directions away from each other. In other words, the recording sheet 320 is conveyed in the direction of the arrow A by the convey roller 350, and the ink ribbon 310 is conveyed toward the winding bobbin 301 of the ink cassette 300 while sliding along a separating plate 335 of the thermal head 330. Although the ink ribbon 310 has adhered to the recording sheet 320 as a result of being heated by the thermal head 330 during printing, the ink ribbon 310 is conveyed to the position of the separating plate 335 and is separated from the recording sheet 320. If the image to be printed is a high-gradation image, a high density is required. Accordingly, more heat is applied to the ink ribbon 310 to diffuse more ink onto the recording sheet 320.
The ink ribbon 310 is constituted by polyethylene terephthalate film as mentioned above, and therefore shrinks when heat is applied. Particularly when printing high-gradation images, a large amount of heat is applied to the ink ribbon 310, which causes the ink ribbon 310 to shrink greatly. When this happens, the ink ribbon 310 wound around the supply bobbin 302 is pulled out due to the shrinkage, which causes the ribbon to twist, sag, wrinkle, and so on. Twisting and wrinkles can lead to color loss, which causes a drop in the printing quality. In order to prevent such a situation in which the printing quality drops, a configuration that creates an appropriate rotational resistance in the rotational shaft of the supply bobbin 302, so that the supply bobbin 302 is not easily pulled out under the effect of a relatively minute force such as that produced by shrinkage, is effective. As described above, the configuration is such that a small rotational resistance is produced in the rotational shaft of the supply bobbin 302. This configuration, that produces rotational resistance, not only prevents the ink ribbon 310 from loosening when the cueing operations are stopped, but also functions to improve resistance to wrinkling.
The distance of the separating plate 335 from the heating elements of the thermal head 330 is optimized to a value necessary for the ink diffused and transferred from the ink ribbon 310 to the recording sheet 320 to be sufficiently cooled and fixed. Once the yellow image region has been printed onto the recording sheet 320, a driving mechanism (not shown) of the printer 100 rotates and retracts the thermal head 330 to the position illustrated in
Through the foregoing, the printing operations, in which the inks are layered in the order of yellow (Y), magenta (M), cyan (C), and the overcoat (OP) and are transferred, are completed.
The configuration of the ink cassette 300 will be described in detail next with reference to
As illustrated in
The ink ribbon 310 is contained within a cassette case 303, wound upon the supply bobbin 302 and with another end attached to the winding bobbin 301. The cassette case 303 is manufactured by injection-molding a high-strength engineering plastic such as ABS or PC to ensure sliding performance with respect to the ink ribbon 310, conveyance performance, and so on, which will be described later.
The cassette case 303 has a configuration in which both end parts of two semicylinders are connected, and open portions of the two semicylinders are covered by a winding bobbin cover 304 and a supply bobbin cover 305, with the two semicylinders disposed parallel to each other. The winding bobbin cover 304 and the supply bobbin cover 305 are integrated by having engagement claws 306, four each of which are provided near both end parts of those covers, engage with engagement holes provided in the cassette case 303. Like the cassette case 303, the winding bobbin cover 304 and the supply bobbin cover 305 are injection-molded components.
End parts of the winding bobbin cover 304 and the supply bobbin cover 305 on a near side in the mounting direction of the printer 100 are connected by a connecting portion 400 constituted by a substantially flat, thin plate member having a surface area that is as broad as possible. The connecting portion 400 is provided with a protrusion-shaped positioning boss 410 and a restricting boss 420 as engagement portions, and a positioning hole 430 as an engaged portion, that engage with the chassis 120 during mounting in the printer 100. Positional relationships between the ink cassette 300, and the printer 100 and chassis 120, will be described later.
The winding bobbin 301 and the supply bobbin 302 are rotatably supported within the winding bobbin storage portion 303A and the supply bobbin storage portion 303B, respectively, of the cassette case 303. The winding bobbin 301 and the supply bobbin 302 have the same shape, and are injection-molded components made using a high-strength resin material such as ABS or PS.
The ink ribbon 310 is bent at a guide shaft 307 rotatably supported by the cassette case 303, and is disposed so as to pass through an opening formed between the cassette case 303, and the winding bobbin cover 304 and supply bobbin cover 305. The guide shaft 307 is made of injection-molded 30% PBT-G, which is a high-strength resin, and has a large-diameter portion which makes contact with the ink ribbon 310 and small-diameter portions provided at both end parts of the large-diameter portion.
Positional relationships between the ink cassette 300, and the printer 100 and chassis 120, will be described next with reference to
As described with reference to
As illustrated in
Here, the positioning boss 410 and the positioning hole 430 are in a positional relationship in which the cassette mounting portion 130 is interposed therebetween, and thus the connecting portion 400 provided on the near side of the ink cassette 300 in the mounting direction receives the force indicated by the arrows D and E. Specifically, the positioning boss 410 and the positioning hole 430 restrict deformation in the side wall portion 120a of the chassis 120 so that a distance between the boss and the hole does not change due to the rigidity of the connecting portion 400 of the cassette case 303. However, the positioning boss 410 and the positioning hole 430 are not disposed on a straight line connecting the centers of the respective bearing portions of the pressure contact cam shaft 336 and the platen roller 340, and thus moment which rotates the cassette case 303 in what is the clockwise direction in
Additionally, because the positioning boss 410 and the positioning hole 430 in the connecting portion 400 of the cassette case 303 function as positioning portions when mounting the ink cassette 300 in the printer 100, the diameter of the hole that fits with the boss is set to the smallest possible clearance. Specifically, the shaft diameter of the boss is set to a diameter which is greater than the diameter of the hole, to ensure a tight fit. On the other hand, the diameter of the hole into which the restricting boss 420 fits has the minimum necessary gap so as to ensure that the boss and the hole do not interfere with each other. Although the minimum necessary gap permits deformation in the chassis 120, the deformation is within a range at which there is no effect on the printing quality by a drop in pressure contact force caused by the deformation. Specifically, the shaft diameter of the restricting boss 420 is set to φ2.2±0.05 mm, and the hole diameter is set to φ2.35±0.05 mm. In contrast to the maximum shaft diameter of the restricting boss 420, which is φ2.15 mm, the hole diameter is φ2.40, allowing 0.125 mm of movement (deformation). However, the reduction in pressure contact force due to this deformation is kept within the range where the printing quality can be ensured.
While the present disclosure has been described with reference to an exemplary embodiment, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiment. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-015531, filed Jan. 31, 2020, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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JP2020-015531 | Jan 2020 | JP | national |
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Number | Date | Country | |
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20210237495 A1 | Aug 2021 | US |