Printer

Abstract

In order to prevent the occurrence of color unevenness or color unevenness from being conspicuous, a printer (100) comprises: a printing unit (10) having a thermal head (12) and an ink ribbon (13); a standby unit (20) provided on the upstream side in a conveyance direction; a supply unit (50) provided on the downstream side in the conveyance direction; a conveyance unit (30) conveying a paper sheet (200) between the supply unit (50) and the standby unit (20); and a control unit (40) controlling the conveyance unit (30) and the printing unit (10) on the basis of image information (S) that has been input. When the paper (200) is to be conveyed to the standby unit (20), the control unit (40) switches to a second operation for disposing a used region of the ink ribbon (13) on the front surface of the thermal head (12) when the image information (S) satisfies a specific condition, and switches to a first operation for disposing an unused region of the ink ribbon (13) on the front surface of the thermal head (12) when the image information (S) does not satisfy the specific condition.

Description

Printer

[0001] The present invention relates to a printer.

[0002] There is known a printer that performs printing with sublimation dyes by thermally diffusing and transferring the sublimation dyes applied to an ink ribbon onto paper (image receiving paper) (see, for example, Patent Document 1).

[0003] International Publication No. 2023 / 112641

[0004] The printer of Patent Document 1 prints on a sheet of paper cut to a predetermined length. Prior to actual printing, the paper (sheet of paper) is conveyed to a standby section upstream of the printing section, and in the process of this conveyance, the leading end of the sheet of paper (paper) on the standby section side is detected.

[0005] Then, the printer reverses the feeding direction of the conveying means and prints on the paper at the printing section while passing the paper from the standby section through the printing section. The timing via printing at the printing section is set based on the detection of the leading end of the paper on the standby section side.

[0006] The printer completes the ink ribbon head-out prior to conveying the paper to the standby section. That is, the printer arranges an unused area of the ink ribbon used for printing on the paper in the printing section before the paper is sent to the standby section.

[0007] Here, when the paper is conveyed along a curved conveyance path from the printing section to the standby section, a part of the paper that curves and protrudes toward the ink ribbon side may be conveyed while rubbing against a specific part of the unused area of the ink ribbon.

[0008] In certain parts of the ink ribbon that have rubbed against the paper, the sensitivity of the ink ribbon (the characteristic of the sublimation dye's color intensity in response to applied heat) may change due to the effects of additives on the paper's surface. Therefore, even in unused areas of the ink ribbon, if printing is performed using an ink ribbon whose sensitivity has changed in only certain parts, color unevenness will occur in the printed image, with differences in color intensity between the specific areas and other parts of the image.

[0009] This invention has been made in view of the above circumstances, and aims to provide a printer that can prevent color unevenness from occurring in prints, or prevent color unevenness from being noticeable if it does occur.

[0010] The present invention relates to a printer comprising: a print unit having a thermal head and an ink ribbon; a standby unit provided upstream of the print unit in the transport direction; a supply unit provided downstream of the print unit in the transport direction; a transport unit that transports paper between the supply unit and the standby unit; and a control unit that controls the transport unit and the print unit based on image information input corresponding to an image to be printed on the paper, wherein the control unit switches to a second operation in which, when the image information satisfies certain conditions, it places the used area of ​​the ink ribbon in front of the thermal head when transporting the paper from the supply unit to the standby unit; and switches to a first operation in which, when the image information does not satisfy certain conditions, it places the unused area of ​​the ink ribbon in front of the thermal head when transporting the paper from the supply unit to the standby unit.

[0011] The printer according to the present invention can prevent color unevenness from occurring in prints, or prevent any color unevenness that does occur from being noticeable.

[0012] This is a schematic diagram illustrating the operation of a dye-sublimation thermal printer, showing the state where paper is placed in the feed unit and the thermal head and ink ribbon are in the retracted position. This is a schematic diagram illustrating the operation of a dye-sublimation thermal printer, showing the state where ribbon leading is complete and paper leading is continuing. This is a schematic diagram illustrating the operation of a dye-sublimation thermal printer, showing the state where paper leading is complete. This is a schematic diagram illustrating the operation of a dye-sublimation thermal printer, showing the state where the thermal head and ink ribbon are in the print position. This is a schematic diagram illustrating the operation of a dye-sublimation thermal printer, showing the state where printed paper is placed in the feed unit. This is a diagram showing the arrangement of sublimation dyes in the ribbon. This is a magnified view of the contact area between the ribbon and the paper in Figure 1B. This is a diagram showing an example of an image printed on paper, an image of the upper body of a person wearing a white shirt. This is a schematic diagram illustrating the operation in which, prior to ribbon leading in the first operation, the ribbon is rewound onto the feed roller and the used portion of the ribbon is placed in front of the thermal head. This schematic diagram illustrates the operation in which, prior to the ribbon's lead-out in the first operation, the ribbon is rewound onto the feed roller to position the used portion of the ribbon in front of the thermal head, showing a state where paper lead-out is continuing. This flowchart shows the process flow in which the control unit determines whether the content of the image information meets specific conditions for switching between the first and second operations before printing a yellow image. This flowchart shows the process flow in which the control unit determines whether the content of the image information meets specific conditions for switching between the first and second operations before printing a magenta image. This flowchart shows the process flow in which the control unit determines whether the content of the image information meets specific conditions for switching between the first and second operations before printing a cyan image. This schematic diagram shows a state in which, during paper lead-out, the paper is not fully transported to the standby section but stops a length L4 in front of it.

[0013] An embodiment of the printer according to the present invention will be described below with reference to the drawings.

[0014] <Configuration> Figures 1A, 1B, 1C, 1D, and 1E are schematic diagrams illustrating the operation of the dye-sublimation thermal printer 100 (hereinafter referred to as the printer 100). Figure 1A shows the state in which the paper 200 is placed in the supply unit 50 and the thermal head 12 and ink ribbon 13 are in the retracted position. Figure 1B shows the state in which the ribbon 16 has finished leading out and the paper 200 is continuing to lead out. Figure 1C shows the state in which the paper 200 has finished leading out. Figure 1D shows the state in which the thermal head 12 and ink ribbon 13 are in the print position. Figure 1E shows the state in which the printed paper 200 is placed in the supply unit 50 (the rear end 201 of the paper 200 is not detached from the thermal head 12).

[0015] Figure 2 shows the arrangement of sublimation dyes in the ribbon 16, and Figure 3 is a magnified view of the contact area where the unused area of ​​the ribbon 16 and the paper 200 come into contact in Figure 1B.

[0016] Printer 100 is an embodiment of the printer according to the present invention. Printer 100 prints an image P corresponding to input CMY image information S onto a sheet of paper 200 that has been pre-cut to a predetermined length. Paper 200 is a receiving paper having a receiving layer that develops color by receiving sublimation dye transferred by thermal diffusion from a ribbon 16. As shown in Figure 1A, printer 100 has at least a printing unit 10, a standby unit 20, a supply unit 50, a transport unit 30, a paper sensor 60, a ribbon sensor 70, and a control unit 40.

[0017] The supply unit 50 is the area that supplies paper 200 to the standby unit 20, and is also the area through which the printed paper 200 is sent out from the standby unit 20 after passing through the print unit 10. The supply unit 50 is located downstream of the print unit 10 in the forward transport direction (the transport direction of the paper 200 when the print unit 10 prints on the paper 200).

[0018] The standby section 20 is an area where the paper 200 temporarily waits before being sent to the print section 10. The standby section 20 is located upstream of the print section 10 in the forward transport direction.

[0019] Under the control of the control unit 40, the printer 100 places the paper 200 in the supply unit 50 and positions the print unit 10 in a retracted position, as shown in Figure 1A. Then, as shown in Figure 1B, the printer 100 drives the transport means 32. Driven by the transport means 32, the printer 100 sends the paper 200 along the transport path 31 to the standby unit 20, as shown in Figure 1C. With the paper 200 in the standby unit 20, the printer 100 moves the print unit 10 to the print position.

[0020] After the print unit 10 is positioned at the print location, the printer 100 drives the transport means 32 to pull the paper 200 back to the supply unit 50 along the transport path 31, as shown in Figure 1D, and prints on the paper 200 using the print unit 10 based on the input image information S.

[0021] Since the printer 100 in this embodiment is a color printer, it sequentially prints yellow based on the yellow (Y) image signal Sy, magenta based on the magenta (M) image signal Sm, and cyan based on the cyan (C) image signal Sc on the paper 200, separately. Furthermore, to protect the printed surface, it prints an overcoat (OC) after the cyan print. Therefore, the printer 100 moves the paper 200 back and forth between the supply unit 50 and the standby unit 20 from the state shown in Figure 1A to the state shown in Figure 1E, and repeats the operation of printing on the paper 200 four times during this back and forth movement.

[0022] (Conveying section) The conveying section 30 includes a conveying path 31 and a conveying means 32. The conveying means 32 is provided on the conveying path 31. The conveying path 31 is provided between the supply section 50 and the standby section 20. As shown in Figure 1A, the conveying path 31 is formed with a cross-sectional shape that is curved in an arc shape, for example. Specifically, the conveying path 31 is formed with a cross-sectional shape that is convex to the side of the print section 10, which will be described later, where the thermal head 12 and ink ribbon 13 are provided. Note that the conveying path 31 may be formed with a planar shape with a straight cross-sectional shape instead of a curved shape.

[0023] The conveying means 32 includes a drive roller 33 and a driven roller 34. The drive roller 33 and the driven roller 34 are positioned opposite each other across the conveying path 31. The drive roller 33 and the driven roller 34 grip the paper 200, which is placed along the conveying path 31, in the thickness direction. As the drive roller 33 rotates, the paper 200 is conveyed along the conveying path 31. The driven roller 34 rotates due to friction with the moving paper 200. The drive roller 33 can be switched between forward rotation, reverse rotation, and stopping by the control unit 40.

[0024] In this specification, forward rotation of the drive roller 33 is in the direction of transporting the paper 200 from the standby unit 20 to the supply unit 50, and reverse rotation of the drive roller 33 is in the direction of transporting the paper 200 from the supply unit 50 to the standby unit 20.

[0025] In the printer 100, the driven roller 34 is provided on the side of the transport path 31 with a convex cross-sectional shape, and the drive roller 33 is provided on the side of the transport path 31 with a concave cross-sectional shape (the side opposite to the side with a convex cross-sectional shape). Alternatively, the printer 100 may have the drive roller 33 provided on the side of the transport path 31 with a convex cross-sectional shape, and the driven roller 34 provided on the side of the transport path 31 with a concave cross-sectional shape.

[0026] (Printing section) The printing section 10 is provided on the transport path 31. The printing section 10 includes a platen roller 11, a thermal head 12, and an ink ribbon 13. The platen roller 11 is provided on one side of the transport path 31, that is, on the side of the transport path 31 with a concave cross-sectional shape. The thermal head 12 and the ink ribbon 13 are provided on the other side of the transport path 31, that is, on the side of the transport path 31 with a convex cross-sectional shape. The platen roller 11, the thermal head 12, and the ink ribbon 13 are arranged facing each other.

[0027] The ink ribbon 13 comprises a feed roller 14, a take-up roller 15, and a ribbon 16. The ribbon 16 is formed by coating a long base film with sublimation dyes of the three primary colors, yellow (Y), magenta (M), and cyan (C), as shown in Figure 2, and also by coating it with a transparent overcoat material (OC). One end of the ribbon 16 in the longitudinal direction is fixed to the feed roller 14, and the other end in the longitudinal direction is fixed to the take-up roller 15. Almost all of the unused portion of the ribbon 16 is wound onto the feed roller 14, and the portion used for printing is wound onto the take-up roller 15.

[0028] The ribbon 16 is divided in the longitudinal direction into four regions, starting from the side closest to the winding roller 15: a Y region 16y coated with yellow sublimation dye, an M region 16m coated with magenta sublimation dye, a C region 16c coated with cyan sublimation dye, and an OC region 16o coated with an overcoat material. The ribbon 16 is formed by repeating the Y region 16y, M region 16m, C region 16c, and OC region 16o in the longitudinal direction.

[0029] The Y region 16y and the M region 16m are in contact at boundary 17ym, the M region 16m and the C region 16c are in contact at boundary 17mc, the C region 16c and the OC region 16o are in contact at boundary 17co, and the OC region 16o and the Y region 16y are in contact at boundary 17oy.

[0030] The ribbon 16 has a portion that spans the front of the thermal head 12 between the portion wound on the feed roller 14 and the portion wound on the take-up roller 15. The portion of the ribbon 16 that spans the front of the thermal head 12 has the base film surface facing the front of the thermal head 12. Therefore, the ribbon 16 is positioned so that the surface coated with sublimation dye faces the platen roller 11.

[0031] The ribbon 16 is unwound from the feed roller 14 and wound onto the feed roller 15 when the winding roller 15 is driven in the forward direction by the control unit 40. At this time, in order to apply tension to the ribbon 16 so that the portion of the ribbon 16 stretched across the front of the thermal head 12 does not become loose, a torque is applied to the feed roller 14 that rotates it in the reverse direction.

[0032] Furthermore, under the control of the control unit 40, the feed roller 14 and the take-up roller 15 are driven in the reverse direction to rewind the used ribbon 16 onto the feed roller 14. As the feed roller 14 rewinds the ribbon 16 and the take-up roller 15 unwinds the used ribbon 16, the used ribbon 16 moves towards the feed roller 14.

[0033] Furthermore, as mentioned above, a torque is applied to the feed roller 14 that rotates it in the reverse direction. Therefore, to prevent excessive tension from being applied to the portion of the ribbon 16 that is stretched across the front of the thermal head 12, a torque limiter is provided on the feed roller 14.

[0034] Except when printing on the paper 200 (see Figure 1D), the thermal head 12 and ink ribbon 13 are positioned in a retracted position away from the transport path 31, as shown in Figures 1A, 1B, and 1C, under the control of the control unit 40. When printing on the paper 200, the thermal head 12 and ink ribbon 13 are positioned in a print position closer to the platen roller 11, as shown in Figure 1D, under the control of the control unit 40. In the print position, the thermal head 12 and ink ribbon 13 sandwich the paper 200, which is being transported along the transport path 31, between themselves and the platen roller 11.

[0035] Furthermore, when the printer 100 prints on the paper 200, the transport means 32 transports the paper 200 in the forward direction under the control of the control unit 40, and the thermal head 12 generates heat according to the input signal value, causing the sublimation dye of the ribbon 16 to be thermally diffused and transferred to the receiving layer of the paper 200 in contact with the ribbon 16, thereby printing an image corresponding to the signal value on the paper 200.

[0036] (Control Unit) When the printer 100 receives image information S corresponding to the image P to be printed on the paper 200, the control unit 40 controls the operation of the transport means 32 and the print unit 10 based on the content of the input image information S, and prints the image P represented by the image information S onto the paper 200.

[0037] The control unit 40 switches the paper transport operation by the transport means 32 and the ribbon feeding operation of the print unit 10 between a first operation (normal operation) and a second operation (color unevenness reduction operation) according to the input image information S.

[0038] [First Operation] The first operation is the normal transport operation of the paper 200 by the transport means 32 and the normal feeding operation of the ribbon 16 by the print unit 10. Specifically, the control unit 40 performs the first operation shown in (1) to (5) below when the content of the input image information S does not satisfy the specific conditions described later.

[0039] (1) With the paper 200 placed in the supply unit 50, the control unit 40 positions the thermal head 12 and ink ribbon 13 in the retracted position (see Figure 1A). Note that when the previous print operation is completed, the state shown in Figure 1A is not required to repeat the operation in (1), and in that case, the operation in (1) may be omitted.

[0040] (2) The control unit 40 rotates the winding roller 15 in the forward direction so that the unused Y region 16y of the ribbon 16 is positioned in front of the thermal head 12. When the ribbon sensor 70 detects the boundary 17oy (see Figure 2) between the unused Y region 16y and the used OC region 16o that precedes the unused Y region 16y, the control unit 40 stops the rotation of the winding roller 15 and rotates the unwinding roller 14 and the winding roller 15 in the reverse direction to rewind the ribbon 16 by a predetermined length, and then stops (see Figure 1B).

[0041] The reason the printer 100 rewinds the ribbon 16 by a predetermined length is that the ribbon sensor 70 is located downstream of the front of the thermal head 12 in the transport direction during printing. However, when the ribbon sensor 70 detects the boundary 17oy, the end region of the unused Y region 16y in the transport direction (the end region of the Y region 16y close to the boundary 17oy) has already passed the front of the thermal head 12. If printing continues in this state, the ribbon will not be used for printing and will be wasted.

[0042] Therefore, the control unit 40 rewinds the unused end region of the Y region 16y in the transport direction to the front of the thermal head 12, allowing the printer 100 to effectively utilize the unused end region of the Y region 16y in the transport direction for printing. However, if it is acceptable for the unused end region of the Y region 16y in the transport direction to remain unused and go to waste, the control unit 40 may be controlled not to perform the operation of rewinding the ribbon 16 by a predetermined length.

[0043] In this way, the state in which the unused Y region 16y of the ribbon 16 is positioned in front of the thermal head 12 and stopped is the state in which the Y region 16y of the ribbon 16 for printing has been fully extended, that is, the state in which the Y region 16y of the ribbon 16 is positioned at a predetermined location when printing is to begin. The predetermined length to unwind the ribbon 16 can be detected by the control unit 40 by detecting the amount of rotation of the winding roller 15 using an encoder or the like provided on the winding roller 15.

[0044] (3) The control unit 40 controls so as to start the leading-out operation of the sheet 200 in parallel with the start of the leading-out operation of the ribbon 16 in (2) by the printer 100. Specifically, as shown in FIG. 1A, the control unit 40 rotates the drive roller 33 in the reverse rotation direction, and conveys the sheet 200 of the supply unit 50 along the conveyance path 31 toward the standby unit 20 (see FIG. 1B). After the sheet sensor 60 detects the leading end 201 in the conveyance direction of the sheet 200 (the leading end closer to the standby unit 20) and further conveys it by a certain length, the control unit 40 stops the rotation of the drive roller 33 (see FIG. 1C). This certain length is stored in the control unit 40 in advance. Since the drive roller 33 is driven by a stepping motor, the control unit 40 can control the conveyance of a certain length by controlling the rotation of the stepping motor. The state where the conveyance of a certain length is completed is the state where the leading-out of the sheet 200 for printing is completed, that is, the state where the sheet 200 at the time of starting printing is arranged at a predetermined position.

[0045] Incidentally, in the state where the previous printing has ended (see FIG. 1A) by the printer 100, the boundary between the used area of the ribbon 16 used in the previous printing and the unused area of the ribbon 16 used in the next printing is sent to a position close to the ribbon sensor 70. Therefore, the length of the ribbon 16 (for example, 2 cm) that conveys the ribbon 16 in the conveyance direction for the leading-out of the ribbon 16 shown in (2) is extremely shorter than the length of the sheet 200 (for example, 30 cm) that conveys the sheet 200 from the supply unit 50 to the standby unit 20 shown in (3). Therefore, at the time when the leading-out operation of the ribbon 16 ((2) operation) is completed (see FIG. 1B), the leading-out operation of the sheet 200 ((3) operation) continues, and thereafter, the leading-out operation of the sheet ends (see FIG. 1C).

[0046] (4) After the leading-out of the ribbon 16 and the leading-out of the sheet 200, the control unit 40 arranges the thermal head 12 and the ink ribbon 13 at the printing position (the position where the platen roller 11 and the thermal head 12 sandwich the sheet 200 and the ink ribbon 13) (see FIG. 1D).

[0047] (5) The control unit 40 rotates the drive roller 33 in the forward rotation direction to convey the paper 200 of the standby unit 20 along the conveyance path 31 toward the supply unit 50, and drives the take-up roller 15 in the forward rotation direction by torque control so that an appropriate tension is applied to the ribbon 16. Further, in parallel with the conveyance of the paper 200 and the feeding of the ribbon 16, the control unit 40 controls the thermal head 12 so as to generate heat corresponding to the image signal Sy corresponding to the yellow color development among the input image information S (see FIG. 1D). After conveying the paper 200 to the position corresponding to the image information S, the control unit 40 stops the rotation of the drive roller 33 and the rotation of the take-up roller 15, and moves the thermal head 12 and the ink ribbon 13 to the retracted position (see FIG. 1E).

[0048] In the first operation in which the printer 100 does not perform the control to rewind the ribbon 16, after performing the printing of the first, second, and third colors and the overcoat printing on the paper 200, the conveyance of the paper 200 is stopped at a position where the paper 200 does not completely come off from the front surface of the thermal head (a position where the rear end 201 of the paper 200 remains on a part of the front surface of the thermal head). On the other hand, in the second operation described later in which the printer 100 rewinds the ribbon 16, since the operation of rewinding the ribbon 16 is performed before printing, when the printing before that printing is completed, the conveyance of the paper 200 is stopped at a position where the rear end 201 of the paper 200 completely passes beyond the front surface of the thermal head 12.

[0049] Through the operations (1) to (5) above, the printer 100 prints the yellow image Py corresponding to the image signal Sy corresponding to the yellow color development among the input image information S on the paper 200.

[0050] Next, the control unit 40 repeats operations (2) to (5) to superimpose a magenta image Pm corresponding to the image signal Sm corresponding to the magenta color development onto the same paper 200, then repeats operations (2) to (5) to superimpose a cyan image Pc corresponding to the image signal Sc corresponding to the cyan color development onto the same paper 200, and then repeats operations (2) to (5) to superimpose an overcoat Po corresponding to the image signal So corresponding to the overcoat onto the same paper 200, and then finishes printing.

[0051] Furthermore, when repeating operations (2) to (5) on the paper 200 after printing the yellow image Py, as operation (2), the control unit 40 rotates the winding roller 15 in the forward direction so that the unused M region 16m of the ribbon 16 is positioned in front of the thermal head 12. When the ribbon sensor 70 detects the boundary 17ym between the unused M region 16m and the preceding used Y region 16y, it rewinds the ribbon 16 by a predetermined length and then stops the rotation of the winding roller 15, completing the position where the beginning of the M region 16m of the ribbon 16 is exposed.

[0052] Furthermore, as part of operation (5), in parallel with the transport of the paper 200 and the feeding of the ribbon 16, the control unit 40 controls the thermal head 12 to generate heat corresponding to the image signal Sm that corresponds to the magenta color development among the input image information S, thereby superimposing the magenta image Pm onto the yellow image Py of the paper 200.

[0053] Similarly, when repeating operations (2) to (5) on a sheet of paper 200 after printing a magenta image Pm superimposed on a yellow image Py, operation (2) is performed by the control unit 40, which rotates the take-up roller 15 in the forward direction so that the unused C region 16c of the ribbon 16 is positioned in front of the thermal head 12. When the ribbon sensor 70 detects the boundary 17mc between the unused C region 16c and the preceding used M region 16m, it rewinds the ribbon 16 by a predetermined length and then stops the rotation of the take-up roller 15, completing the position where the beginning of the C region 16c of the ribbon 16 is exposed.

[0054] Furthermore, as part of operation (5), in parallel with the transport of the paper 200 and the feeding of the ribbon 16, the control unit 40 controls the thermal head 12 to generate heat corresponding to the image signal Sc that corresponds to the development of cyan color in the input image information S, thereby superimposing the cyan image Pc onto the yellow image Py and magenta image Pm of the paper 200.

[0055] Similarly, when repeating operations (2) to (5) on a sheet of paper 200 after printing a cyan image Pc superimposed on a yellow image Py and a magenta image Pm, as operation (2), the control unit 40 rotates the take-up roller 15 in the forward direction so that the unused OC region 16o of the ribbon 16 is positioned in front of the thermal head 12. When the ribbon sensor 70 detects the boundary 17co between the unused OC region 16o and the preceding used C region 16c, the control unit 40 rewinds the ribbon 16 by a predetermined length and then stops the rotation of the take-up roller 15, completing the positioning of the OC region 16o of the ribbon 16.

[0056] Furthermore, as part of operation (5), in parallel with the transport of the paper 200 and the feeding of the ribbon 16, the control unit 40 controls the thermal head 12 to generate heat corresponding to the input overcoat, thereby superimposing the overcoat onto the yellow image Py, the magenta image Pm, and the cyan image Pc on the paper 200.

[0057] [Second Operation] Next, the second operation performed by the control unit 40 will be described. The second operation is the control performed in place of the first operation described above when the content of the CMY image information S input to the printer 100 satisfies specific conditions. The specific conditions for the content of the image information S under which the control unit 40 performs the second operation will be described later. When the content of the image information S satisfies specific conditions, if the printer 100 prints the image P on the paper 200 in the first operation, noticeable color unevenness may occur in a specific area of ​​the image P. Therefore, when the content of the input image information S satisfies specific conditions, the printer 100 switches the control of the control unit 40 to the second operation, which is different from the first operation, in order to avoid the occurrence of noticeable color unevenness.

[0058] The mechanism by which this print color unevenness occurs will be explained below. Figure 4 shows an example of image P printed on paper 200, which is an image of the upper body of a person wearing a white dress shirt.

[0059] In the first operation described above, the printer 100 completes the ribbon 16 leading operation before the paper 200 leading operation (see Figure 1B). Therefore, while the paper 200 is leading, as shown in Figures 1B and 3, the ribbon 16, which has completed leading, stops with an unused area facing the paper 200. In this state, the paper 200, which is sent to the standby unit 20 along the curved transport path 31, comes into contact with a specific position 16A in the unused area of ​​the ribbon 16 facing it. The paper 200 then continues to slide along that specific position 16A in the unused area of ​​the ribbon 16 until the paper 200 leading operation (operation (3)) is completed.

[0060] The sublimation dye at a specific position 16A of the ribbon 16 is affected by additives that bleed out onto the surface of the paper 200 due to sliding with the paper 200. This changes the characteristics (sensitivity) of the color intensity to heat, causing it to develop color with different characteristics than the sublimation dye in other parts of the ribbon 16. When printing (operation (5)) is performed using the ribbon 16 with the changed sensitivity at the specific position 16A, the image P printed on the paper 200 will have color unevenness in a specific part of the printed paper 200 in the transport direction corresponding to the specific position 16A of the ribbon 16 (the part at a distance L1 from the leading edge 202 in the transport direction of the paper 200 during the printing operation), resulting in a different color intensity than other parts in the transport direction. This uneven coloring occurs in a specific part of the printed paper 200 in the transport direction corresponding to the specific position 16A of the ribbon 16, as shown in Figure 4.

[0061] The changes in sensitivity of the sublimation dye described above occur in each color region of the ribbon 16 (Y region 16y, M region 16m, C region 16c). Furthermore, this color unevenness is noticeable to human vision in light gray and yellow, light tonal ranges (ranges with small signal values ​​of image information S), and conversely, it is hardly noticeable in dark, dense tonal ranges (ranges with large signal values ​​of image information S).

[0062] Therefore, the printer 100's control unit 40 determines, based on the input image information S, whether the image signals Sy, Sm, and Sc of each color corresponding to a specific position 16A on the ribbon 16 are within a specific grayscale range. If it determines that the image signals Sy, Sm, and Sc of each color corresponding to a specific position 16A are within a specific grayscale range, then a specific condition is met, and the control unit 40 performs control to switch from the first operation to the second operation.

[0063] Figures 5A and 5B are schematic diagrams illustrating the operation in which, prior to the leading edge of the ribbon 16 in (2) of the first operation, the ribbon 16 is rewound onto the feed roller 14, thereby positioning the used portion of the ribbon 16 in front of the thermal head 12.

[0064] Specifically, the second operation involves the control unit 40, before the ribbon 16 is extended in the first operation, starting the operation (2') of rewinding the ribbon 16 onto the feed roller 14, as shown in Figure 5A, to position the used portion of the ribbon 16 in front of the thermal head 12. Once the used portion of the ribbon 16 is positioned in front of the thermal head 12, the control unit 40 stops rewinding the ribbon 16 (see Figure 5B).

[0065] Ideally, the paper 200 should be transported in the same direction as the ribbon 16 (towards the standby unit 20) in synchronization with the rewinding of the ribbon 16. By transporting the paper 200 in synchronization with the rewinding of the ribbon 16, the ribbon 16 can be rewound stably without being affected by static electricity or frictional loads between the ribbon 16 and the paper 200. The control unit 40 continues to transport the paper 200 to complete the leading-out of the paper 200, and then controls the leading-out of the ribbon 16.

[0066] As a result, when the paper 200 being transported to the standby unit 20 passes in front of the thermal head 12, the used area of ​​the ribbon 16 is positioned in front of the thermal head 12. Therefore, the printer 100 can prevent the transported paper 200 from coming into contact with the unused area of ​​the ribbon 16, and prevent the sensitivity of the unused area of ​​the ribbon 16 from changing.

[0067] Then, after the ribbon 16 and the paper 200 have been led out, the control unit 40 controls the system to (4) position the thermal head 12 and ink ribbon 13 at the print position and to perform the print operation (5).

[0068] In this way, the printer 100 can prevent the sensitivity of the sublimation dye at a specific position 16A in the unused area of ​​the ribbon 16 from changing by controlling the printer to avoid the paper 200 sliding into the unused area of ​​the ribbon 16 when the paper 200 is first fed out. As a result, the printer 100 can prevent the occurrence of color unevenness that is noticeable to the human eye in the image P printed on the paper 200.

[0069] [Specific conditions regarding the content of image information S] The specific conditions regarding the content of image information S, under which the control unit 40 performs the second operation, will be described in detail below.

[0070] The image information S is composed of, for example, 2448 pixels in the horizontal direction (main scanning direction x; corresponding to the width direction W in Figure 4) and 3036 lines in the vertical direction (sub-scanning direction y; corresponding to the length direction L in Figure 4). Therefore, the image signal Sy corresponding to the yellow image Py is composed of the signal values ​​Sy(x,y) of each pixel with a total of 2448 × 3036 pixels, the image signal Sm corresponding to the magenta image Pm is composed of the signal values ​​Sm(x,y) of each pixel with a total of 2448 × 3036 pixels, and the image signal Sc corresponding to the cyan image Pc is composed of the signal values ​​Sc(x,y) of each pixel with a total of 2448 × 3036 pixels.

[0071] First, as shown in Figure 3, the specific position 16A that the paper 200 contacts on the ribbon 16, which has been fully deployed in the printing unit 10, differs depending on the number of layers already printed in the printing unit 10. Specifically, when paper 200 that has not been printed at all (number of printed layers is 0) is sent to the standby unit 20, that is, when the unused Y region 16y of the ribbon 16 is positioned in front of the thermal head 12, the inventors have confirmed that the specific position 16A is the portion of the ribbon 16 in the Y region 16y corresponding to the position (y=250) of the L1=250 line in the transport direction (sub-scanning direction y by the thermal head 12) of the yellow image Py.

[0072] In contrast, when a sheet of paper 200 with only the yellow image Py printed on it (1 printed layer) is sent to the standby unit 20, that is, when the unused M region 16m of the ribbon 16 is positioned in front of the thermal head 12, the inventors have confirmed that the portion of the ribbon 16 in the M region 16m corresponding to the position (y=300) of the L1=300 line in the transport direction (sub-scanning direction y by the thermal head 12) of the magenta image Pm is a specific position 16A.

[0073] Furthermore, the inventors have confirmed that when a sheet of paper 200 with a yellow image Py and a magenta image Pm printed on it (2 printed layers) is sent to the standby unit 20, that is, when the unused C region 16c of the ribbon 16 is positioned in front of the thermal head 12, the portion of the ribbon 16 in the C region 16c corresponding to the position (y=300) of the L1=300 line in the transport direction (sub-scanning direction y by the thermal head 12) of the cyan image Pc is a specific position 16A.

[0074] It is presumed that the reason why a specific position 16A of the ribbon 16 changes depending on the number of printed layers is because the position where the paper 200 makes strong contact with the unused area of ​​the ribbon 16 changes depending on the number of printed layers, but this has not been clearly explained.

[0075] Furthermore, the inventors have confirmed that when the signal values ​​(yellow image signals Sy) of 40% or more of the total number of pixels on the L1=250 line of the yellow image Py in the image information S input to the printer 100 are between 15 and 55 (in the case of 8-bit signal values ​​(0 to 255)), color unevenness due to fluctuations in the intensity of yellow color becomes noticeable on the L1=250 line of the yellow image Py.

[0076] Furthermore, the inventors have confirmed that when the signal values ​​(magenta image signal Sm) of 40% or more of the total number of pixels on the L1=300 line of the magenta image Pm in the image information S input to the printer 100 are between 15 and 55 (in the case of an 8-bit signal value (0 to 255)), color unevenness due to fluctuations in the intensity of magenta color development becomes noticeable on the L1=300 line of the magenta image Pm.

[0077] Furthermore, the inventors have confirmed that when the signal values ​​(cyan image signals Sc) of 40% or more of the total number of pixels on the L1=300 line of the cyan image Pc in the image information S input to the printer 100 are between 15 and 55 (in the case of 8-bit signal values ​​(0 to 255)), color unevenness due to fluctuations in the intensity of cyan color development becomes noticeable on the L1=300 line of the cyan image Pc.

[0078] Based on the inventor's analysis described above, the printer 100's control unit 40 switches between a first operation and a second operation in response to specific conditions defined in (A), (B), or (C) below, and controls the transport operation of the transport means 32 and the feeding operation of the ink ribbon 13 before printing each color, and then prints each color.

[0079] Figure 6A is a flowchart showing the process flow for determining whether the content of image information S meets a specific condition when the control unit 40 prints a yellow image Py and switches between the first and second operations. Figure 6B is a flowchart showing the process flow for determining whether the content of image information S meets a specific condition when the control unit 40 prints a magenta image Pm and switches between the first and second operations. Figure 6C is a flowchart showing the process flow for determining whether the content of image information S meets a specific condition when the control unit 40 prints a cyan image Pc and switches between the first and second operations.

[0080] (A) The control unit 40 determines whether a specific condition is met for color unevenness to occur on the L1=250 line in the image P (an image in which the yellow image Py, the magenta image Pm, and the cyan image Pc are superimposed) based on the change in sensitivity of the Y region 16y in the ribbon 16, and controls the operation before printing the yellow image Py to switch between the first operation and the second operation.

[0081] Specifically, as shown in Figure 6A, the control unit 40 first sets the initial values ​​to x = 1 and the number of pixels that satisfy the condition among the 250 lines of the yellow image signal Sy, Ny = 0 (S11). Next, the control unit 40 determines whether the signal value Sy(x, 250) of each pixel (x, 250) on the 250 lines (y = 250) in the sub-scanning direction y of the yellow image Py satisfies the condition of being 15 or more and 55 or less (S12), whether the signal value Sm(x, 250) of each pixel (x, 250) on the 250 lines (y = 250) in the sub-scanning direction of the magenta image Pm satisfies the condition of being 15 or more and 55 or less (S13), and whether the signal value Sc(x, 250) of each pixel (x, 250) on the 250 lines (y = 250) in the sub-scanning direction y of the cyan image Pc satisfies the condition of being 15 or more and 55 or less (S14).

[0082] Then, if all of the conditions in S12 to S14 are met (if all of S12 to S14 are YES), the control unit 40 increments the number of pixels that satisfy the conditions Ny by 1 (S15). If any one of S12 to S14 is not met (if any one of S12 to S14 is NO), the control unit 40 does not increment the number of pixels that satisfy the conditions Ny, but instead sequentially replaces the pixels in the main scanning direction x with the adjacent pixels (S16), and repeats the same process (S12 to S16) until the last pixel in the main scanning direction (x = 2448) (S17).

[0083] The control unit 40 determines whether the number of pixels Ny that satisfy the condition among all pixels (2448 pixels) on the 250 lines in the sub-scanning direction y (main scanning direction x) is 40% or more (980 or more) (S18). If it determines that it is 40% or more (YES in S18), the control unit 40 switches the operation before printing the yellow image Py to the second operation (S19). If it determines that the number of pixels is less than 40% (less than 980) (NO in S18), the control unit 40 switches the operation before printing the yellow image Py to the first operation (S20).

[0084] (B) The control unit 40 determines whether a specific condition is met for color unevenness to occur on the L1=300 line in the image P (an image in which the yellow image Py, the magenta image Pm, and the cyan image Pc are superimposed) based on the change in sensitivity of the M region 16m in the ribbon 16, and performs control to switch the operation before printing the magenta image Pm to either the first operation or the second operation.

[0085] Specifically, as shown in Figure 6B, the control unit 40 first sets the initial values ​​to x = 1 and the number of pixels that satisfy the condition among the 300 lines of the magenta image signal Sm, Nm = 0 (S21). Next, the control unit 40 determines whether the signal value Sm(x,300) of each pixel (x,300) on the 300 lines (y=300) in the sub-scanning direction y of the magenta image Pm is 15 or more and 55 or less (S22), and whether the signal value Sc(x,300) of each pixel (x,300) on the 300 lines (y=300) in the sub-scanning direction of the cyan image Pc is 64 or less (S23).

[0086] Then, if all of the conditions in S22 and S23 are met (if all of S22 and S23 are YES), the control unit 40 increments the number of pixels Nm that satisfy the conditions by 1 (S24). If even one of S22 and S23 is not met (if even one of S22 and S23 is NO), the control unit 40 does not increment the number of pixels Nm that satisfy the conditions, but instead sequentially replaces the pixels in the main scanning direction x with the adjacent pixels (S25), and repeats the same process (S22 to S25) until the last pixel in the main scanning direction (x = 2448) (S26).

[0087] The control unit 40 determines whether the number of pixels Nm that satisfy the condition among all pixels (2448 pixels) on the 300 lines in the sub-scanning direction y (main scanning direction x) is 40% or more (980 or more) (S27). If it determines that it is 40% or more (YES in S27), the control unit 40 switches the pre-print operation of the magenta image Pm to the second operation (S28). If it determines that the number of pixels is less than 40% (less than 980) (NO in S27), the control unit 40 switches the pre-print operation of the magenta image Pm to the first operation (S29).

[0088] (C) The control unit 40 determines whether a specific condition is met for color unevenness to occur on the L1=300 line in the image P (an image in which the yellow image Py, the magenta image Pm, and the cyan image Pc are superimposed) based on the change in sensitivity of the C region 16c in the ribbon 16, and controls the operation before printing the cyan image Pc to switch between the first operation and the second operation.

[0089] Specifically, as shown in Figure 6C, the control unit 40 first sets the initial values ​​to x = 1 and the number of pixels on the 300 line of the cyan image signal Sc that satisfy the condition Nc = 0 (S31). Next, the control unit 40 determines whether the signal value Sm(x,300) of each pixel (x,300) on the 300 line (y=300) in the sub-scanning direction y of the magenta image Pm is 127 or less (S32), and whether the signal value Sc(x,300) of each pixel (x,300) on the 300 line (y=300) in the sub-scanning direction of the cyan image Pc is 15 or more and 55 or less (S33).

[0090] Then, if all of the conditions in S32 and S33 are met (if all of S32 and S33 are YES), the control unit 40 increments the number of pixels Nc that satisfy the conditions by 1 (S34). If even one of S32 or S33 is not met (if even one of S32 or S33 is NO), the control unit 40 does not increment the number of pixels Nc that satisfy the conditions, but instead sequentially replaces the pixels in the main scanning direction x with the adjacent pixels (S35), and repeats the same process (S32 to S35) until the last pixel in the main scanning direction (x = 2448) (S36).

[0091] The control unit 40 determines whether the number of pixels Nc that satisfy the condition among all pixels (2448 pixels) on the 300 lines in the sub-scanning direction y (main scanning direction x) is 40% or more (980 or more) (S37). If it determines that it is 40% or more (YES in S37), the control unit 40 switches the pre-print operation of the cyan image Pc to the second operation (S38). If it determines that the number of pixels is less than 40% (less than 980) (NO in S37), the control unit 40 switches the pre-print operation of the cyan image Pc to the first operation (S39).

[0092] Furthermore, when the control unit 40 performs the rewinding operation of the ribbon 16 in operation (2') of the second operation, it is preferable that the length to which the ribbon 16 is rewound is, for example, a dimension that exceeds the length L1 in the transport direction (sub-scanning direction y) in the image P.

[0093] As described above, in this embodiment, the printer 100 can prevent color unevenness from occurring in the image P printed on the paper 200 by the control unit 40 switching the paper transport operation by the transport means 32 and the ribbon feeding operation of the print unit 10 to a second operation (color unevenness reduction operation) according to the content of the input image information S.

[0094] On the other hand, in the printer 100 of this embodiment, even if color unevenness occurs, if it occurs only in less than 40% of the total number of pixels in the main scanning direction x, as described above, the color unevenness is not noticeable to the human eye, and therefore there is little need to perform the second operation to reduce color unevenness. Accordingly, in the printer 100 of this embodiment, even if color unevenness occurs, if it is not noticeable to the human eye, the first operation can be performed without performing the second operation, thereby shortening the time required before printing compared to the second operation.

[0095] In this embodiment, the printer 100's control unit 40 indicates that the number of pixels Ny, Nm, and Nc satisfying the conditions is 40% or more of the total number of pixels in the main scanning direction x, as specified in (A), (B), or (C). However, instead of 40%, the number of pixels Ny, Nm, and Nc satisfying the conditions may be 35% or more of the total number of pixels in the main scanning direction x, or 30% or more of the total number of pixels in the main scanning direction x. The specific value of this percentage, which represents the ratio to the total number of pixels, will change depending on the characteristics of the media used (ribbon 16 and paper 200), so it is desirable to adjust it according to the media used.

[0096] [Control to prevent or suppress the effects of static electricity] In the first operation (2) of the printer 100 of this embodiment, the ribbon 16 is brought forward. More specifically, the control unit 40 rotates the take-up roller 15 in the forward direction so that the unused Y region 16y of the ribbon 16 is positioned in front of the thermal head 12. When the ribbon sensor 70 detects the boundary 17oy (see Figure 2) between the unused Y region 16y and the used OC region 16o that precedes the unused Y region 16y, the control unit 40 stops the rotation of the take-up roller 15 (see Figure 1B) and rotates the feed roller 14 and the take-up roller 15 by a certain amount in the reverse direction.

[0097] The reason for rotating the feed roller 14 and the take-up roller 15 in the reverse direction by a certain amount is, as mentioned above, to rewind the leading edge of the unused Y region 16y to the front of the thermal head 12, thereby making effective use of the Y region 16y. The printer 100, through the above control by the control unit 40, also makes effective use of the other unused M region 16m, C region 16c, and OC region 16o, similar to the Y region 16y.

[0098] When the ribbon sensor 70 detects the boundary 17oy between the Y region 16y and the OC region 16o, the control unit 40 calculates the amount of rewind needed to bring the Y region 16y to the front of the thermal head 12 by rewinding the leading edge of the Y region 16y to the front of the thermal head 12, and also calculates the amount of feed needed to position (bring to the front) the leading edge of the subsequent M region 16m to the front of the thermal head 12.

[0099] Then, during the period when yellow printing is being performed using the Y region, the control unit 40, based on the calculated feed amount, moves the thermal head 12 and ink ribbon 13 to a retracted position away from the platen roller 11 after the yellow printing is finished, so that the leading edge of the M region for magenta printing is positioned in front of the thermal head 12 from the position where the boundary 17oy between the Y region 16y and the OC region 16o passes in front of the ribbon sensor 70 again and the ribbon sensor 70 detects the boundary 17oy, and then feeds the ribbon 16 in the forward direction, thereby completing the leading edge of the M region 16m and eliminating the need to rewind the ribbon 16.

[0100] Furthermore, the lengths of the Y region 16y, the M region 16m, the C region 16c, and the OC region 16o are known, the length from the position where the ribbon sensor 70 detects the boundary 17oy to the front of the thermal head 12 is also known, and the feed amount of the ribbon 16 corresponding to the counter value of the rotation amount of the winding roller 15 (such as the count value of an encoder provided coaxially with the winding roller 15) is also known. Since these lengths and feed amounts are stored in advance in the control unit 40, the control unit 40 can calculate the position of the tip of the M region 16m from the position where the ribbon sensor 70 detects the boundary 17oy between the Y region 16y and the OC region 16o based on this stored data. The calculation of the tip of the C region 16c and the tip of the OC region 16o, which will be described below, is done in the same way.

[0101] Similarly to this control, during the period when magenta printing is in progress, when the ribbon sensor 70 detects the boundary 17ym between the M region 16m and the Y region 16y, the control unit 40 also calculates the feed amount to position the leading edge of the subsequent C region 16c in front of the thermal head 12. Based on the calculated feed amount to position the leading edge of the C region for cyan printing in front of the thermal head 12 from the position where the boundary 17ym is detected by the ribbon sensor 70, after the magenta printing is completed, the thermal head 12 and ink ribbon 13 are moved to a retracted position away from the platen roller 11, and the ribbon 16 is fed in the forward direction, thereby completing the leading edge of the C region 16c and eliminating the need to rewind the ribbon 16.

[0102] Similarly to this control, during the period when cyan printing is in progress, when the ribbon sensor 70 detects the boundary 17mc between the C region 16c and the M region 16m, the control unit 40 also calculates the feed amount to position the leading edge of the subsequent OC region 16o in front of the thermal head 12. Based on the calculated feed amount to position the leading edge of the OC region 16o for overcoat printing in front of the thermal head 12 from the position where the boundary 17mc was detected by the ribbon sensor 70, after the cyan printing is completed, the thermal head 12 and ink ribbon 13 are moved to a retracted position away from the platen roller 11, and the ribbon 16 is fed in the forward direction, thereby completing the leading edge of the OC region 16o and eliminating the need to rewind the ribbon 16.

[0103] Incidentally, while this is not a problem in the rewinding operation of the ribbon 16 for leading out the Y region 16y in the first operation described above, static electricity generated between the ribbon 16 and the paper 200 can be a problem in the rewinding operation of the ribbon 16 for leading out the Y region 16y in the second operation.

[0104] In other words, in the second operation, with the paper 200 positioned in the standby unit 20, the used OC area 16o is positioned in front of the thermal head. From this state, in order to bring out the Y area 16y of the ribbon 16, the control unit 40 rotates the take-up roller 15 in the forward direction so that the ribbon 16 is fed in the forward direction, and after the ribbon sensor 70 detects the boundary 17oy, the control unit 40 rotates the feed roller 14 and the take-up roller 15 in the reverse direction to rewind the ribbon 16 by a certain amount to bring out the Y area 16y.

[0105] However, in the second operation, when the ribbon 16 is being fed in the forward direction, it is fed in close proximity to the paper 200 located in the standby unit 20, so static electricity is generated between the paper 200 and the ribbon 16, and an electric charge accumulates on the ribbon 16. Therefore, when the ribbon sensor 70 detects the boundary 17oy and the control unit 40 rotates the feed roller 14 and the take-up roller 15 in the reverse direction to rewind the ribbon 16, the ribbon 16 may be attracted to the paper 200 or the like due to the accumulated electric charge.

[0106] As mentioned above, the feed roller 14 has a torque limiter, so when the ribbon 16 is attracted to the surrounding rollers, the feed roller 14 may spin freely due to the torque limiter's effect, preventing it from rewinding the ribbon 16. On the other hand, when the ribbon 16 is rewound, the take-up roller 15 also rotates in the reverse direction, so the used ribbon 16 that was wound on the take-up roller 15 is unwound. As a result, the ribbon 16 becomes irregularly loose between the feed roller 14 and the take-up roller 15, making it impossible to bring out the end of the ribbon 16.

[0107] Figure 7 is a schematic diagram showing a state in which, when the paper 200 is being led out, the paper 200 is not fully transported to the standby unit 20, but is stopped a distance L4 before it.

[0108] In this embodiment, the printer 100, during the second operation in which the ribbon 16 is unwound and the paper 200 is led out, controls the drive roller 33 so that the paper 200 is not fully transported to the predetermined position in the standby unit 20, but is stopped by a length L4 before the predetermined position, as shown in Figure 7.

[0109] The printer 100 stops the paper 200 in front of a predetermined position in the standby unit 20 and then brings out the Y region 16y of the ribbon 16. When the feed roller 14 and take-up roller 15 are rotated in the reverse direction to rewind the ribbon 16, the control unit 40 feeds the ribbon 16 in the reverse direction and simultaneously transports the paper 200 to the predetermined position in the standby unit 20.

[0110] Due to the effect of static electricity between the ribbon 16 and the paper 200, the ribbon 16 is attracted to the paper 200 as it is being transported in the reverse direction. This makes it easier for the ribbon 16 to move in the reverse direction as well, allowing it to be wound onto the feed roller 14 and enabling the ribbon 16 to be properly extended.

[0111] In this way, the printer 100 of this embodiment can eliminate or reduce the effects of static electricity generated on the ribbon 16 by performing the second operation, stopping the paper 200 from being completely transported to the standby unit 20 even when static electricity is generated on the ribbon 16, and simultaneously sending the paper 200 to the standby unit 20 when the ribbon 16 is rewound. Cross-reference of related applications

[0112] This application claims priority pursuant to Japanese Patent Application No. 2024-164095, filed with the Japan Patent Office on September 20, 2024, all of which disclosures are incorporated herein by reference in their entirety.

Claims

1. A printer comprising: a print unit having a thermal head and an ink ribbon; a standby unit provided upstream of the print unit in the transport direction; a supply unit provided downstream of the print unit in the transport direction; a transport unit that transports paper between the supply unit and the standby unit; and a control unit that controls the transport unit and the print unit based on image information input corresponding to an image to be printed on the paper, wherein the control unit switches to a second operation in which, when the image information satisfies a specific condition, it places the used area of ​​the ink ribbon in front of the thermal head when transporting the paper from the supply unit to the standby unit; and switches to a first operation in which, when the image information does not satisfy a specific condition, it places the unused area of ​​the ink ribbon in front of the thermal head when transporting the paper from the supply unit to the standby unit.

2. The printer according to claim 1, wherein when the control unit transports the paper from the supply unit to the standby unit, if the image information on the line corresponding to a specific position where the paper contacts the ink ribbon positioned in front of the thermal head is a signal value corresponding to a specific bright color, the specific condition is met and the control unit switches to the second operation.

3. The printer according to claim 2, wherein the control unit switches to the second operation when the image information of 40% or more of the total number of pixels on the line is a signal value corresponding to a specific bright color, thus satisfying the specific condition.

4. The printer according to any one of claims 1 to 3, wherein the control unit, in the second operation, stops the paper before a predetermined position in the standby unit when transporting the paper from the supply unit to the standby unit, and after stopping the paper, transports the paper to the predetermined position in the standby unit when rewinding the used area of ​​the ink ribbon, which is positioned in front of the thermal head, back into the unused area of ​​the ink ribbon.

Images