Printing apparatus and method for controlling the printing apparatus

Abstract

The present invention provides a printing apparatus and a control method for the printing apparatus that can improve the printing accuracy of the first and second images. [Solution] The control unit performs the following: ejects a pre-processing solution onto a feature region on the first surface of a medium corresponding to a feature point of the first image or a feature point of the second image; ejects ink onto the first surface of the medium on which the pre-processing solution has been ejected onto the feature region, thereby printing the first image onto the first surface; captures the medium on which the first image is printed from the second surface, which is the opposite surface from the first surface; and corrects the second image to be printed on the second surface based on the captured image and the feature points of the first image or the feature points of the second image.

Description

Technical Field

[0001] The present invention relates to a printing apparatus and a control method thereof.

Background Art

[0002] For example, as in Patent Document 1, after printing a first image on a first surface of a printing material which is an example of a medium, the first image is imaged from the second surface side which is the back surface of the first surface, and a duplex printing system is disclosed which matches the position of the first image on the first surface and the position of the second image on the second surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in such a duplex printing system, imaging is performed from the second surface on the opposite side of the first surface on which the first image is printed. Therefore, there are cases where the first image cannot be sufficiently identified from the captured image. Therefore, it is desired to improve the printing accuracy of the first image and the second image. <​​​​​A printing apparatus for solving the above problems comprises a pre-treatment liquid dispensing unit for dispensing a pre-treatment liquid onto a medium, an ink dispensing unit for dispensing ink onto a medium to print an image on the medium, an imaging unit for imaging the medium, and a control unit. The control unit performs the following actions: dispensing a pre-treatment liquid from the pre-treatment liquid dispensing unit onto a feature region of the first surface of the medium corresponding to a feature point of the first image or a feature point of the second image; dispensing ink from the ink dispensing unit onto the first surface of the medium on which the pre-treatment liquid has been dispensed onto the feature region to print the first image on the first surface; imaging the medium on which the first image has been printed from a second surface opposite to the first surface using the imaging unit; and correcting the second image to be printed on the second surface based on the image captured by the imaging unit and the feature points of the first image or the second image.

[0006] A control method for a printing apparatus that solves the above problems is a control method for a printing apparatus that prints a first image by ejecting ink onto a first surface of a medium and prints a second image by ejecting ink onto a second surface of the medium opposite to the first surface, and the method involves ejecting a pre-treatment liquid onto a feature region of the first surface corresponding to a feature point of the first image or a feature point of the second image; printing the first image onto the first surface by ejecting ink onto the first surface of the medium onto which the pre-treatment liquid has been ejected to the feature region; capturing an image of the medium on which the first image has been printed from the second surface; and correcting the second image to be printed on the second surface based on the captured image and the feature points of the first image or the feature points of the second image. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a printing apparatus according to the first embodiment. [Figure 2] Figure 2 is a block diagram showing the electrical configuration of the printing apparatus according to the first embodiment. [Figure 3] Figure 3 is a schematic diagram showing the first surface of the printed medium according to the first embodiment. [Figure 4]Figure 4 is a schematic diagram showing the second surface of the printed medium according to the first embodiment. [Figure 5] Figure 5 is a schematic diagram showing the first image data of the first embodiment. [Figure 6] Figure 6 is a schematic diagram showing the second image data of the first embodiment. [Figure 7] Figure 7 is a schematic diagram showing the characteristic points and characteristic regions of the first embodiment. [Figure 8] Figure 8 is a flowchart showing the feature point setting process of the first embodiment. [Figure 9] Figure 9 is a flowchart showing the first print control process of the first embodiment. [Figure 10] Figure 10 is a flowchart showing the second print control process of the first embodiment. [Figure 11] Figure 11 is a schematic diagram showing the characteristic points and characteristic regions of the second embodiment. [Figure 12] Figure 12 is a flowchart showing the first print control process of the fifth embodiment. [Figure 13] Figure 13 is a flowchart showing the feature point setting process of the sixth embodiment. [Figure 14] Figure 14 is a flowchart showing the first print control process of the sixth embodiment. [Figure 15] Figure 15 is a flowchart showing the second print control process of the sixth embodiment. [Figure 16] Figure 16 is a flowchart showing the first print control process of the seventh embodiment. [Modes for carrying out the invention]

[0008] [First Embodiment] Hereinafter, an embodiment of a printing apparatus and a control method of the printing apparatus will be described. In the following description, with the printing apparatus installed on a horizontal surface, the axis intersecting the horizontal surface is defined as the Z-axis, the axis intersecting the Z-axis is defined as the X-axis, and the axis intersecting the X-axis and the Z-axis is defined as the Y-axis, respectively. One direction along the X-axis is defined as the first width direction X1, and the other direction along the X-axis is defined as the second width direction X2. One direction along the Y-axis is defined as the front Y1, and the other direction along the Y-axis is defined as the rear Y2. The upward direction along the Z-axis is defined as the upper Z1, and the downward direction along the Z-axis is defined as the lower Z2.

[0009] <Configuration of the printing apparatus 11> As shown in FIG. 1, the printing apparatus 11 may be an inkjet printer that performs printing on the medium 99 by discharging ink onto the medium 99. The medium 99 includes a first surface 99A and a second surface 99B. The second surface 99B is the surface opposite to the first surface 99A.

[0010] The medium 99 may be long. The medium 99 may be fed out, for example, from a roll-shaped web. The medium 99 is not limited to being long and may be in the form of a single sheet. The medium 99 may be a fabric.

[0011] The printing apparatus 11 includes an ink ejection unit 12. The ink ejection unit 12 may be provided above the medium 99 in the upper Z1 direction. The ink ejection unit 12 is configured to perform printing on the medium 99 by discharging ink onto the medium 99. The ink ejection unit 12 performs printing on the conveyed medium 99.

[0012] The ink ejection unit 12 may include a head. The ink ejection unit 12 may be a serial head or a line head. The serial head is a head that scans along the X-axis with respect to the medium 99. The line head is a head that performs simultaneous recording across the X-axis.

[0013] The printing apparatus 11 includes a conveyance unit 13. The conveyance unit 13 is configured to convey the medium 99 in the conveyance direction D. The conveyance direction D may be along the Y-axis. The conveyance direction D may be toward the front Y1.

[0014] The conveying unit 13 may include a first roller 21 and a second roller 22. The first roller 21 is located upstream of the second roller 22 in the conveying direction D. The first roller 21 is located upstream of the ink ejection unit 12 in the conveying direction D. The second roller 22 is located downstream of the ink ejection unit 12 in the conveying direction D.

[0015] The conveying unit 13 includes a conveying belt 23. The conveying belt 23 is configured to convey the medium 99 while supporting the medium 99. The conveying belt 23 is wound around the first roller 21 and the second roller 22. When the first roller 21 rotates, the conveying belt 23 moves along the first roller 21 and the second roller 22.

[0016] The conveying unit 13 includes a roller driving unit 24. The roller driving unit 24 is a driving source for rotating a plurality of rollers. The roller driving unit 24 may be a motor. The roller driving unit 24 is connected to the first roller 21, but may also be connected to the second roller 22, or may be connected to both the first roller 21 and the second roller 22.

[0017] The conveying unit 13 conveys the medium 99 such that the surface facing the ink ejection unit 12 becomes the printing surface. Thus, when the medium 99 is installed such that the first surface 99A faces the ink ejection unit 12, the first surface 99A becomes the printing surface. When the medium 99 is installed such that the second surface 99B faces the ink ejection unit 12, the second surface 99B becomes the printing surface.

[0018] " The printing apparatus 11 includes a pretreatment liquid ejection unit 14. The pretreatment liquid ejection unit 14 is provided at a position facing the medium 99. The pretreatment liquid ejection unit 14 may be provided above the medium 99 in the Z1 direction. The pretreatment liquid ejection unit 14 is located upstream of the ink ejection unit 12 in the conveying direction D.

[0019] The pretreatment liquid discharge unit 14 is configured to discharge the pretreatment liquid onto the medium 99. The pretreatment liquid discharge unit 14 may include a head. The pretreatment liquid discharge unit 14 may be a serial head or a line head.

[0020] The pretreatment solution may be a penetrating solution. In this way, the pretreatment solution dispensing unit 14 dispenses the penetrating solution as the pretreatment solution. The penetrating solution promotes ink penetration. The penetrating solution may be a liquid that is difficult to see. The penetrating solution may be a colorless liquid.

[0021] The printing apparatus 11 includes an imaging unit 15. The imaging unit 15 is positioned opposite the medium 99. The imaging unit 15 may be positioned above the medium 99 Z1. The imaging unit 15 is located upstream of the ink ejection unit 12 in the transport direction D. The imaging unit 15 is located upstream of the pre-treatment liquid ejection unit 14 in the transport direction D.

[0022] The imaging unit 15 is configured to image the medium 99. When the medium 99 is transported with its first surface 99A facing the other surface, the imaging unit 15 images the first surface 99A of the medium 99. When the medium 99 is transported with its second surface 99B facing the other surface, the imaging unit 15 images the second surface 99B of the medium 99.

[0023] The printing apparatus 11 includes a control unit 30. The control unit 30 comprehensively controls the printing apparatus 11. The control unit 30 controls various operations performed by the printing apparatus 11. The control unit 30 controls the ink ejection unit 12, the transport unit 13, the pre-treatment liquid ejection unit 14, and the imaging unit 15.

[0024] As shown in Figure 2, the control unit 30 may be composed of one or more computers. The control unit 30 may include one or more processors 31 and one or more memories 32. The processor 31 may be a CPU (Central Processing Unit). The processor 31 is configured to execute processing based on a program stored in the memory 32.

[0025] The control unit 30 may be configured as a circuit including α: one or more processors that perform various processes according to a computer program, β: one or more dedicated hardware circuits that perform at least some of the various processes, or γ: a combination thereof. The hardware circuit is, for example, an application-specific integrated circuit.

[0026] Memory 32 includes a computer-readable medium accessible by a general-purpose or dedicated computer. Memory 32 stores program code or instructions configured to cause the processor 31 to perform processing. Memory 32 is a non-temporary computer-readable medium for storing programs, but may include temporary computer-readable medium.

[0027] Memory 32 stores the first image data D1. The first image data D1 is the image data of the first image P1 shown in Figures 3 and 5. The first image data D1 shows the shape, color, etc. of the first image P1. The first image P1 is printed on the first surface 99A. The first image data D1 may also be CAD data representing the first image P1 created by software.

[0028] Memory 32 stores the second image data D2. The second image data D2 is the image data of the second image P2 shown in Figures 4 and 6. The second image data D2 shows the shape, color, etc. of the second image P2. The second image P2 is printed on the second surface 99B. The second image data D2 may also be CAD data representing the second image P2 created by software.

[0029] Memory 32 stores feature point data D3. Feature point data D3 is coordinate data representing feature point P3 shown in Figure 7. Feature point P3 is a coordinate that represents a feature of the first image P1, but it may also be a coordinate that represents a feature of the second image P2.

[0030] Memory 32 stores feature region data D4. Feature region data D4 is coordinate data representing feature region P4 as shown in Figure 7. Feature region P4 is the coordinate of the region containing feature point P3 of the first image P1, but it may also be the coordinate of the region containing feature point P3 of the second image P2. Feature region P4 is the region where the pretreatment solution is discharged.

[0031] Memory 32 stores the captured image data D5. The captured image data D5 is the image data of the captured image. The captured image is captured by the imaging unit 15. The captured image may be an image of the medium 99 captured from the second surface 99B. In particular, the captured image may be an image of the medium 99 captured from the second surface 99B when the first image P1 is printed on the first surface 99A and the second image P2 is not printed on the second surface 99B.

[0032] <Type of medium 99 and printing on medium 99> As shown in Figures 3 and 4, in this embodiment, the printing device 11 prints on both the first surface 99A and the second surface 99B. The printing device 11 prints the first image P1 shown in Figure 3 by ejecting ink onto the first surface 99A, and then prints the second image P2 shown in Figure 4 by ejecting ink onto the second surface 99B.

[0033] As shown in Figure 3, the first image P1 is printed periodically on the medium 99. The first image P1 may also be printed periodically on the medium 99 so that it appears repeatedly in the transport direction D.

[0034] As shown in Figure 4, the second image P2 is printed periodically on the medium 99. The second image P2 may be printed periodically on the medium 99 so that it appears repeatedly in the transport direction D.

[0035] As shown in Figures 3 and 4, the first image P1 and the second image P2 are images that are inverted on the first surface 99A and the second surface 99B of the medium 99. The first image P1 and the second image P2 are images that are symmetrical in the direction along the X-axis. The first image P1 and the second image P2 are images that are symmetrical in the direction along the X-axis with respect to a first center line C1 along the Y-axis. The first center line C1 may or may not be the center line of the medium 99. In this way, the second image P2 on the second surface 99B is printed in the area corresponding to the first image P1 on the first surface 99A.

[0036] As shown in Figures 5 and 6, the first image data D1 and the second image data D2 are symmetrical image data in the direction along the X-axis. The first image data D1 and the second image data D2 are symmetrical image data in the direction along the X-axis with respect to a second center line C2 along the Y-axis. The second center line C2 may or may not be the center line of the first image data D1. The second center line C2 may be at the same position as the first center line C1 or at a different position.

[0037] As shown in Figure 7, feature point P3 may be a characteristic location in the first image P1. Feature point P3 may be included in the printing area where ink is ejected as the first image P1. Feature point P3 may be a corner in the first image P1. Feature point P3 may be assigned to the first image data D1.

[0038] Feature region P4 is the region in the first image P1 that contains feature point P3. Feature region P4 is the region in the first image P1 where feature point P3 can be identified. Feature region P4 may also be an edge in the first image P1 that contains feature point P3. An edge is the boundary between the printing region where ink is ejected as the first image P1 and the non-printing region where ink is not ejected as the first image P1. Feature region P4 is the region where the pretreatment solution is ejected. Feature region P4 may also be assigned to the first image data D1.

[0039] The pre-treatment liquid dispensing unit 14 is configured to dispense pre-treatment liquid onto the medium 99 when the medium 99 is positioned facing the first surface 99A. In other words, the pre-treatment liquid dispensing unit 14 dispenses pre-treatment liquid onto the first surface 99A. The pre-treatment liquid dispensing unit 14 dispenses pre-treatment liquid onto the first surface 99A before the ink dispensing unit 12 dispenses ink onto the first surface 99A.

[0040] In particular, the pretreatment liquid discharge unit 14 is configured to discharge the pretreatment liquid from the first surface 99A to the feature region P4. Therefore, when ink is discharged in the feature region P4 of the medium 99 after the pretreatment liquid has been discharged from the first surface 99A, the penetration of the ink from the first surface 99A to the second surface 99B is promoted.

[0041] The imaging unit 15 can image the medium 99 from the second surface 99B after the pre-processing liquid has been ejected from the first surface 99A to the feature region P4 and printing has been performed on the first surface 99A. That is, by imaging the second surface 99B, the imaging unit 15 can image the first image P1 printed on the first surface 99A through it. In this case, the medium 99 has not been printed on the second surface 99B. The imaging unit 15 can image the feature region P4 in a discernible manner because the ink ejected from the first surface 99A penetrates to the second surface 99B in the feature region P4. The imaging unit 15 can image the feature points P3 corresponding to the feature region P4 in a discernible manner.

[0042] <Feature point setting process> Here, the feature point setting process will be explained with reference to Figure 8. The feature point setting process is performed by the control unit 30 when setting the feature points P3 of the image to be printed on the medium 99. The feature point setting process may also be performed by the control unit 30 based on user instructions. The following processes will be described as processes performed by the control unit 30, but they may also be processes performed by the processor 31.

[0043] As shown in Figure 8, in step S11, the control unit 30 executes the first image data acquisition process. In this process, the control unit 30 reads the first image data D1 stored in the memory 32. As a result, the control unit 30 acquires the first image data D1.

[0044] In step S12, the control unit 30 performs a binarization process. In this process, the control unit 30 binarizes the first image data D1. This allows the control unit 30 to recognize the print area of ​​the first image P1.

[0045] In step S13, the control unit 30 performs a first image feature point calculation process. In this process, the control unit 30 calculates feature points P3 of the first image P1 based on the binarized first image data D1. The control unit 30 may calculate the corners of the printing area of ​​the first image P1 as feature points P3 of the first image P1. The control unit 30 stores the feature point data D3 indicating the feature points P3 of the first image P1 in the memory 32. In this way, the control unit 30 sets feature points P3 in the first image P1.

[0046] The control unit 30 calculates the feature region P4 of the first image P1 that corresponds to the feature point P3 of the first image P1. The control unit 30 stores the feature region data D4 indicating the feature region P4 of the first image P1 in the memory 32. In this way, the control unit 30 sets the feature region P4 in the first image P1.

[0047] The control unit 30 may calculate the feature point P3 of the first image P1 itself as the feature region P4 of the first image P1. Alternatively, the control unit 30 may calculate the region containing the feature point P3 of the first image P1 as the feature region P4 of the first image P1.

[0048] To give a specific example, the control unit 30 may calculate the corner of the printing area from which ink is ejected as the first image P1 as the feature area P4 of the first image P1. The control unit 30 may calculate the area including the corner of the printing area of ​​the first image P1 as the feature area P4 of the first image P1. The control unit 30 may calculate the corner of the printing area of ​​the first image P1 and the edge of the printing area of ​​the first image P1 that is continuous from the corner as the feature area P4 of the first image P1. The control unit 30 may calculate the area enclosed by the corner of the printing area of ​​the first image P1 and the edge of the printing area of ​​the first image P1 that is continuous from the corner as the feature area P4 of the first image P1.

[0049] <First Print Control Process> Next, the first print control process will be described with reference to Figure 9. The first print control process is performed by the control unit 30 when printing the first image P1 on the first surface 99A. The first print control process is performed by the control unit 30 based on user instructions when the medium 99 is placed in the transport unit 13 so that the first surface 99A faces the ink ejection unit 12.

[0050] As shown in Figure 9, in step S21, the control unit 30 executes the first image feature region acquisition process. In this process, the control unit 30 reads the feature region data D4 of the first image P1 from the memory 32. As a result, the control unit 30 acquires the feature region P4 of the first image P1.

[0051] In step S22, the control unit 30 performs a pretreatment liquid discharge process. In this process, the control unit 30 controls the pretreatment liquid discharge unit 14 to discharge the pretreatment liquid to the feature region P4 of the first image P1. In this way, the control unit 30 causes the pretreatment liquid discharge unit 14 to discharge the pretreatment liquid to the feature region P4 of the first surface 99A corresponding to the feature point P3 of the first image P1.

[0052] In step S23, the control unit 30 executes the first image printing process. In this process, the control unit 30 controls the ink ejection unit 12 to print the first image P1 on the first surface 99A by ejecting ink onto the first surface 99A based on the first image data D1.

[0053] In this way, the control unit 30 prints the first image P1 on the first surface 99A of the medium 99 on which the pre-treatment liquid has been discharged in the feature region P4 by causing the ink discharge unit 12 to discharge ink.

[0054] In feature region P4, ink is ejected after a pretreatment solution (penetrating liquid) is ejected from the first surface 99A. This promotes ink penetration from the first surface 99A to the second surface 99B in feature region P4. As a result, feature region P4 becomes easier to recognize from the second surface 99B due to the ink ejected from the first surface 99A.

[0055] <Second Print Control Process> Next, the second print control process will be described with reference to Figure 10. The second print control process is executed by the control unit 30 when printing the second image P2 on the second surface 99B. The second print control process is executed by the control unit 30 based on user instructions when the medium 99 is placed in the transport unit 13 so that the second surface 99B faces the ink ejection unit 12. The second print control process is executed by the control unit 30 after the execution of the first print control process.

[0056] As shown in Figure 10, in step S31, the control unit 30 performs imaging processing. In this process, the control unit 30 controls the imaging unit 15 to image the medium 99 from the second surface 99B. The control unit 30 stores the image data D5 of the second surface 99B in the memory 32.

[0057] In this manner, the control unit 30 causes the imaging unit 15 to image the medium 99 on which the first image P1 has been printed from the first surface 99A after the pre-processing liquid has been discharged from the first surface 99A to the feature region P4, from the second surface 99B.

[0058] In step S32, the control unit 30 performs an image inversion process. In this process, the control unit 30 inverts the image data D5 in the direction along the X-axis. As a result, the control unit 30 generates image data D5 corresponding to the first surface 99A based on the image data D5 of the second surface 99B. In other words, the control unit 30 obtains the image data D5 of the first surface 99A from the image data D5 of the second surface 99B.

[0059] In step S33, the control unit 30 performs a first image feature point search process. In this process, the control unit 30 identifies a feature region P4 on the first surface 99A where the pretreatment liquid was ejected, based on the inverted captured image. Specifically, the control unit 30 identifies the region in the captured image where the ink ejected from the first surface 99A has penetrated to the second surface 99B as the feature region P4. The control unit 30 obtains a feature point P3 from the feature region P4 identified from the captured image.

[0060] In step S34, the control unit 30 performs a second image data correction process. In this process, the control unit 30 acquires feature points P3 of the first image P1 stored in the memory 32. Based on the feature points P3 acquired from the captured image and the feature points P3 of the first image P1 acquired from the memory 32, the control unit 30 corrects the first image data D1 as the first corrected image data. The control unit 30 may also correct the first image data D1 as the first corrected image data based on the deviation between the feature points P3 acquired from the captured image and the feature points P3 of the first image P1 acquired from the memory 32.

[0061] The control unit 30 inverts the first corrected image data in the direction along the X-axis. As a result, the control unit 30 generates second corrected image data based on the first corrected image data. In other words, the control unit 30 obtains the second corrected image data from the first corrected image data. The control unit 30 stores the second corrected image data in the memory 32.

[0062] In this way, the control unit 30 corrects the second image P2 to be printed on the second surface 99B based on the feature points P3 of the captured image and the feature points P3 of the first image P1. In other words, the control unit 30 acquires a second corrected image data to be printed on the second surface 99B based on the feature points P3 of the captured image and the feature points P3 of the first image P1.

[0063] In step S35, the control unit 30 executes a second image printing process. In this process, the control unit 30 controls the ink ejection unit 12 to print the second image P2 on the second surface 99B by ejecting ink onto the second surface 99B based on the second corrected image data.

[0064] In this manner, the control unit 30 prints a second corrected image by having the ink ejection unit 12 eject ink onto the second surface 99B of the medium 99, on which a pre-treatment liquid is ejected to the first surface 99A and the first image P1 is printed on the first surface 99A.

[0065] <Operation and Effects of the First Embodiment> The operation and effects of the first embodiment will now be described. (1-1) The control unit 30 prints the first image P1 on the first surface 99A by ejecting a pre-treatment liquid onto the feature region P4 of the first surface 99A corresponding to the feature point P3 of the first image P1 and ejecting ink onto the first surface 99A. The control unit 30 corrects the second image P2 to be printed on the second surface 99B based on the captured image taken from the second surface 99B of the medium 99 on which the first image P1 is printed and the feature point P3 of the first image P1. With this configuration, the feature point P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A on which the pre-treatment liquid was ejected can be recognized based on the captured image taken from the second surface 99B of the medium 99. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0066] (1-2) The control unit 30 sets feature points P3 in the first image P1. With this configuration, feature points P3 can be set as intended according to the first image P1. (1-3) The pretreatment liquid discharge unit 14 discharges a penetrating liquid as a pretreatment liquid to promote ink penetration. With this configuration, the ink discharged to the feature region P4 penetrates more easily from the first surface 99A to the second surface 99B. As a result, based on the captured image of the medium 99 from the second surface 99B, it becomes easier to recognize the feature point P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A from which the pretreatment liquid was discharged. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0067] [Second Embodiment] Next, a second embodiment will be described. In the following description, redundant explanations of the same configuration as in the previously described embodiment will be omitted or simplified, and configurations that differ from those in the previously described embodiment will be described.

[0068] In the second embodiment, the feature point P3 only needs to be included in the printed area of ​​the first image P1. The feature point P3 does not need to be a characteristic part of the first image P1. The feature area P4 may be included in both the printed area and the non-printed area of ​​the first image P1.

[0069] As shown in Figure 11, the feature region P4 may be grid-like. The feature point P3 may be a point where the feature region P4 intersects in the printed area of ​​the first image P1. The feature point P3 may not be a corner or edge of the first image P1.

[0070] <Operation and Effects of the Second Embodiment> The operation and effects of the second embodiment will now be described. (2-1) The feature region P4 may be included in both the printable region and the non-printable region of the first image P1. With this configuration, in the feature region P4 set in the non-printable region of the first image P1, the pretreatment liquid is ejected from the first surface 99A, but no ink is ejected. Therefore, even if the pretreatment liquid is ejected into the feature region P4 set in the non-printable region of the first image P1, the ink does not penetrate into the second surface 99B. In addition, the pretreatment liquid is a penetrating liquid that is difficult to see, so even if the pretreatment liquid itself penetrates into the second surface 99B, it becomes difficult to see. Therefore, a decrease in print quality on the second surface 99B can be suppressed.

[0071] [Third Embodiment] Next, a third embodiment will be described. In the third embodiment, the imaging unit 15 may be an infrared camera. That is, the imaging unit 15 may image the medium 99 using infrared light. The imaging unit 15 may be equipped with a filter that transmits light in a predetermined frequency band.

[0072] The pretreatment liquid dispensing unit 14 may dispense white ink as the pretreatment liquid. The pretreatment liquid dispensing unit 14 may dispense white dye ink as the pretreatment liquid. The white ink reflects infrared light. The white ink may contain, for example, titanium dioxide, zinc oxide, lithopone, lead white, etc.

[0073] Feature points P3 and feature regions P4 of the first image P1 are set in the printable area of ​​the first image P1. Feature points P3 and feature regions P4 of the first image P1 are not set in the non-printable area of ​​the first image P1.

[0074] The ink ejection unit 12 may eject dye ink as ink for printing an image. Dye inks, such as acidic inks and reactive inks, transmit infrared light. If the white ink used as a pretreatment solution is a dye-based white ink, the feature points P3 and feature regions P4 of the first image P1 may be set to areas of the first image P1's print area that do not contain white ink.

[0075] In step S13 of Figure 8, the control unit 30 sets feature points P3 and feature region P4 of the first image P1 in the printing area of ​​the first image P1. In step S22 of Figure 9, the control unit 30 dispenses white dye ink as a pretreatment solution into the feature region P4 of the first image P1 that has been set in the printing area of ​​the first image P1.

[0076] In the feature region P4, infrared light is reflected by ejecting white ink as a pretreatment solution between the first surface 99A and the ink of the first image P1. Outside the feature region P4, no white ink is ejected between the first surface 99A and the ink of the first image P1, and therefore infrared light is not reflected. As a result, in step S33 of Figure 10, the control unit 30 can recognize the feature region P4 of the first image P1 that reflects infrared light based on the captured image.

[0077] <Operation and Effects of the Third Embodiment> The operation and effects of the third embodiment will now be described. (3-1) The imaging unit 15 images the medium 99 using infrared light. With this configuration, by using infrared light, it is possible to capture an image that includes the situation on the first surface 99A as well as the second surface 99B. Therefore, based on the image of the medium 99 captured from the second surface 99B, it becomes easier to recognize the feature point P3 of the first image P1 that corresponds to the feature region P4 of the first surface 99A on which the pre-treatment liquid was discharged. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Consequently, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0078] (3-2) The pretreatment liquid discharge unit 14 discharges white ink as the pretreatment liquid. With this configuration, by discharging white ink that reflects infrared rays as the pretreatment liquid, it becomes easier to recognize the feature points P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A from which the pretreatment liquid was discharged, based on the captured image of the medium 99 from the second surface 99B. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0079] (3-3) The control unit 30 sets feature points P3 of the first image P1 in a region of the first image P1 that does not contain white ink. The pre-treatment liquid discharge unit 14 discharges white ink as a pre-treatment liquid into the feature region P4 of the first image P1 that does not contain white ink. With this configuration, white ink is discharged as a pre-treatment liquid into the feature region P4 of the first image P1 that does not contain white ink. As a result, it becomes easier to recognize feature points P3 of the first image P1 that correspond to the feature region P4 of the first surface 99A from which the pre-treatment liquid was discharged, based on the captured image obtained by capturing the medium 99 from the second surface 99B. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0080] [Fourth Embodiment] Next, a fourth embodiment will be described. In the fourth embodiment, the imaging unit 15 may image the medium 99 using infrared light. The pretreatment liquid discharge unit 14 may discharge white pigment ink as the pretreatment liquid. The black pigment ink absorbs infrared light. The pigment inks other than black reflect infrared light compared to the black pigment ink.

[0081] Feature points P3 and feature regions P4 of the first image P1 are set in the printable area of ​​the first image P1. Feature points P3 and feature regions P4 of the first image P1 are not set in the non-printable area of ​​the first image P1.

[0082] The ink ejection unit 12 may eject pigment ink as ink for printing an image. In this case, the feature points P3 and feature regions P4 of the first image P1 may be set as regions within the printing region of the first image P1 where black ink is ejected as the first image P1. In this way, white ink is ejected as a pretreatment solution in the feature region P4 of the first image P1 so as to be adjacent to the region where black ink is ejected as the first image P1.

[0083] In step S13 of Figure 8, the control unit 30 sets the feature point P3 and the feature region P4 of the first image P1 as areas where black ink is ejected in the first image P1. In this way, the feature point P3 and the feature region P4 of the first image P1 are set as areas where black ink is ejected in the printing area of ​​the first image P1.

[0084] In step S22 of Figure 9, the control unit 30 ejects white pigment ink as a pretreatment solution into the feature region P4 of the first image P1, which is set as the region where black ink is ejected within the printing area of ​​the first image P1.

[0085] In the feature region P4, infrared light is reflected by ejecting white ink as a pretreatment solution between the first surface 99A and the ink of the first image P1. In the region adjacent to the feature region P4, infrared light is absorbed by ejecting black ink as the first image P1 onto the first surface 99A. As a result, in step S33 of Figure 10, the control unit 30 can recognize the feature region P4 of the first image P1 that reflects infrared light based on the captured image.

[0086] <Operation and Effects of the Fourth Embodiment> The operation and effects of the fourth embodiment will now be described. (4-1) The control unit 30 sets a feature point P3 of the first image P1 in the region where black ink is ejected in the first image P1. The pre-treatment liquid ejection unit 14 ejects white ink as a pre-treatment liquid into the feature region P4 where black ink is ejected in the first image P1. With this configuration, white ink is ejected as a pre-treatment liquid into the feature region P4 where infrared-absorbing black ink is ejected in the first image P1. Therefore, based on the captured image of the medium 99 from the second surface 99B, it becomes easier to recognize the feature point P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A where the pre-treatment liquid was ejected. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0087] [Fifth Embodiment] Next, a fifth embodiment will be described. In the fifth embodiment, the amount of pretreatment liquid discharged from the first surface 99A may be adjusted based on the type of medium 99. The amount of pretreatment liquid discharged from the first surface 99A may be adjusted based on the thickness of the medium 99. The amount of pretreatment liquid discharged from the first surface 99A may be adjusted based on the material of the medium 99.

[0088] As shown in Figure 12, when step S21 is completed, the control unit 30 moves to step S24. In step S24, the control unit 30 performs a media type acquisition process. In this process, the control unit 30 acquires the type of media 99. The control unit 30 may also acquire the thickness of the media 99 corresponding to the type of media 99. The control unit 30 may also acquire the material of the media 99 corresponding to the type of media 99.

[0089] The control unit 30 acquires the type of media 99 in response to setting instructions from the user. The control unit 30 may also acquire the type of media 99 in response to a signal from the media detection unit that detects the type of media 99.

[0090] In step S25, the control unit 30 performs a pretreatment liquid discharge amount setting process. In this process, the control unit 30 reads the discharge amount of the pretreatment liquid corresponding to the type of medium 99 from the memory 32. The control unit 30 reads the discharge amount of the pretreatment liquid corresponding to the thickness of the medium 99 from the memory 32. The control unit 30 reads the discharge amount of the pretreatment liquid corresponding to the material of the medium 99 from the memory 32. As a result, the control unit 30 obtains the discharge amount of the pretreatment liquid.

[0091] In step S22, the control unit 30 controls the pretreatment liquid dispensing unit 14 to dispense the pretreatment liquid onto the feature region P4 of the first image P1 based on the amount of pretreatment liquid dispensed. In this way, the control unit 30 adjusts the amount of pretreatment liquid dispensed from the first surface 99A based on the type of medium 99. The control unit 30 adjusts the amount of pretreatment liquid dispensed from the first surface 99A based on the thickness of the medium 99. In this way, the control unit 30 adjusts the amount of pretreatment liquid dispensed from the first surface 99A based on the material of the medium 99.

[0092] <Operation and Effects of the Fifth Embodiment> The operation and effects of the fifth embodiment will now be described. (5-1) The control unit 30 adjusts the amount of pretreatment liquid discharged based on the type of medium 99. With this configuration, by adjusting the amount of pretreatment liquid discharged according to the type of medium 99, it becomes easier to recognize the feature points P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A from which the pretreatment liquid was discharged, based on the captured image of the medium 99 from the second surface 99B. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0093] (5-2) The control unit 30 adjusts the amount of pretreatment liquid discharged based on the thickness of the medium 99. With this configuration, by adjusting the amount of pretreatment liquid discharged according to the thickness of the medium 99, it becomes easier to recognize the feature points P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A from which the pretreatment liquid was discharged, based on the captured image of the medium 99 from the second surface 99B. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0094] (5-3) The control unit 30 adjusts the amount of pretreatment liquid discharged based on the material of the medium 99. With this configuration, by adjusting the amount of pretreatment liquid discharged according to the material of the medium 99, it becomes easier to recognize the feature points P3 of the first image P1 corresponding to the feature region P4 of the first surface 99A from which the pretreatment liquid was discharged, based on the captured image of the medium 99 from the second surface 99B. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0095] [Sixth Embodiment] Next, a sixth embodiment will be described. In the sixth embodiment, the feature region P4 of the first image P1 may be defined based on the feature point P3 of the second image P2, rather than the feature point P3 of the first image P1.

[0096] <Feature point setting process> As shown in Figure 13, in the feature point setting process, when step S11 is completed, the control unit 30 moves the process to step S14. In step S14, the control unit 30 executes the second image data acquisition process. In this process, the control unit 30 inverts the first image data D1 in the direction along the X axis with respect to the second center line C2 along the Y axis. As a result, the control unit 30 generates the second image data D2 based on the first image data D1. In other words, the control unit 30 acquires the second image data D2 from the first image data D1. The control unit 30 stores the second image data D2 in the memory 32.

[0097] In step S15, the control unit 30 performs a binarization process. In this process, the control unit 30 binarizes the second image data D2 in the same way as in step S12 of Figure 8. As a result, the control unit 30 can recognize the print area of ​​the second image P2.

[0098] In step S16, the control unit 30 performs a second image feature point calculation process. In this process, the control unit 30 calculates the feature points P3 of the second image P2 based on the binarized second image data D2, just as in step S13 in Figure 8. The control unit 30 stores the feature point data D3, which represents the feature points P3 of the second image P2, in the memory 32. In this way, the control unit 30 sets the feature points P3 in the second image P2.

[0099] The control unit 30 calculates the feature region P4 of the second image P2 that corresponds to the feature point P3 of the second image P2. The control unit 30 stores the feature region data D4, which represents the feature region P4 of the second image P2, in the memory 32. In this way, the control unit 30 sets the feature region P4 in the second image P2.

[0100] <First Print Control Process> As shown in Figure 14, in the first print control process, in step S20, the control unit 30 executes the second image feature region acquisition process. In this process, the control unit 30 reads the feature region data D4 of the second image P2 from the memory 32. As a result, the control unit 30 acquires the feature region P4 of the second image P2.

[0101] In step S21, the control unit 30 executes the first image feature region acquisition process. In this process, the control unit 30 inverts the feature region P4 of the second image P2 in the direction along the X axis with respect to the second center line C2 along the Y axis. As a result, the control unit 30 generates the feature region P4 of the first image P1 based on the feature region P4 of the second image P2. In other words, the control unit 30 acquires the feature region P4 of the first image P1 from the feature region P4 of the second image P2. The control unit 30 stores the feature region data D4 of the first image P1 in the memory 32. As a result, in step S22, the control unit 30 discharges the pre-processing solution onto the feature region P4 of the first surface 99A corresponding to the feature point P3 of the second image P2.

[0102] <Second Print Control Process> As shown in Figure 15, in the second print control process, when step S31 is completed, the control unit 30 moves the process to step S36. In step S36, the control unit 30 executes the second image feature point search process. In this process, the control unit 30 identifies a feature region P4 on the first surface 99A where the pretreatment liquid was ejected, based on the captured image, just as in step S33 in Figure 10. The control unit 30 obtains a feature point P3 from the feature region P4 identified from the captured image.

[0103] As a result, in step S34, the control unit 30 corrects the second image P2 to be printed on the second surface 99B as a second corrected image based on the captured image and the feature points P3 of the second image P2. In other words, the control unit 30 acquires second corrected image data to be printed on the second surface 99B based on the feature points P3 of the captured image and the feature points P3 of the second image P2.

[0104] <Operation and Effects of the Sixth Embodiment> The operation and effects of the sixth embodiment will now be described. (6-1) The control unit 30 ejects a pre-treatment liquid onto the feature region P4 of the first surface 99A corresponding to the feature point P3 of the second image P2, and ejects ink onto the first surface 99A, thereby printing the first image P1 onto the first surface 99A. The control unit 30 corrects the second image P2 to be printed on the second surface 99B of the medium 99 on which the first image P1 has been printed, based on the captured image taken from the second surface 99B and the feature point P3 of the second image P2. With this configuration, it is possible to recognize the feature point P3 of the second image P2 corresponding to the feature region P4 of the first surface 99A on which the pre-treatment liquid was ejected, based on the captured image taken from the second surface 99B of the medium 99. This improves the accuracy of correcting the second image P2 to be printed on the second surface 99B. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0105] [Seventh Embodiment] Next, a seventh embodiment will be described. In the seventh embodiment, the medium 99 may be, for example, a jacquard fabric. A jacquard fabric is a fabric in which a pattern is formed by weaving. The pattern may be formed by the unevenness caused by weaving. The medium 99 may have a pattern on at least the first surface 99A.

[0106] In the seventh embodiment, the first image P1 may be printed so as to correspond to the pattern on the first surface 99A. In the seventh embodiment, the imaging unit 15 may image the first surface 99A before printing the first image P1 on the first surface 99A. This captures the pattern on the first surface 99A.

[0107] In the seventh embodiment, the control unit 30 may correct the first image data D1 based on pattern image data captured from the first surface 99A, and print the first image P1 on the first surface 99A based on the corrected first image data. In this case, the control unit 30 may correct the feature region P4 of the first image P1 corresponding to the first image data D1 based on pattern image data captured from the first surface 99A, and discharge a pretreatment agent into the corrected feature region P4.

[0108] <First Print Control Process> As shown in Figure 16, in the first print control process, in step S26, the control unit 30 performs an imaging process. In this process, the control unit 30 controls the imaging unit 15 to image the medium 99 from the first surface 99A. In this way, the control unit 30 causes the imaging unit 15 to image the medium 99 from the first surface 99A, where no pretreatment liquid or ink has been ejected. The control unit 30 stores the pattern image data of the first surface 99A in the memory 32.

[0109] In step S27, the control unit 30 performs a pattern feature point search process. In this process, the control unit 30 identifies a pattern region on the first surface 99A based on the pattern image data of the first surface 99A. Based on the pattern region identified from the pattern image data, the control unit 30 obtains a feature point P3 of the pattern image. The feature point P3 of the pattern image may be a corner of the pattern region.

[0110] When step S21 is completed, the control unit 30 moves the process to step S28. In step S28, the control unit 30 executes the first image data correction process. In this process, the control unit 30 acquires the feature points P3 of the first image P1 stored in memory 32. Based on the feature points P3 of the pattern image and the feature points P3 of the first image P1 acquired from memory 32, the control unit 30 corrects the first image data D1 as the first corrected image data. The control unit 30 may also correct the first image data D1 as the first corrected image data based on the deviation between the feature points P3 of the pattern image and the feature points P3 of the first image P1.

[0111] In step S29, the control unit 30 performs a first image feature region correction process. In this process, the control unit 30 corrects the feature region data D4 of the first image P1 based on the feature points P3 of the pattern image and the feature points P3 of the first image P1. The control unit 30 may also correct the feature region data D4 of the first image P1 based on the deviation between the feature points P3 of the pattern image and the feature points P3 of the first image P1.

[0112] As a result, in step S22, the control unit 30 discharges a pre-treatment liquid onto the feature area P4 of the first surface 99A based on the feature area data D4 corrected to correspond to the pattern of the first surface 99A. In step S23, the control unit 30 prints the first image P1 onto the first surface 99A based on the first corrected image data corrected to correspond to the pattern of the first surface 99A.

[0113] <Operation and Effects of the 7th Embodiment> The operation and effects of the seventh embodiment will now be described. (7-1) The control unit 30 acquires a pattern image on the first surface 99A by causing the medium 99, which has not had the pretreatment liquid and ink ejected, to be imaged from the first surface 99A. The control unit 30 corrects the feature region P4 of the first image P1 and the first image P1 to correspond to the pattern on the first surface 99A. With this configuration, the pretreatment liquid can be ejected to the feature region P4 corresponding to the pattern, and the first image P1 can be printed on the first surface 99A to correspond to the pattern. Therefore, the printing accuracy of the first image P1 and the second image P2 can be improved.

[0114] [Example of changes] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0115] The control unit 30 may prepare a test medium 99 in advance with the first image P1 printed on the first surface 99A, and acquire feature points P3 of the first image P1 based on the image captured by the imaging unit 15 from the first surface 99A of the test medium 99. The control unit 30 does not have to acquire feature points P3 of the first image P1 based on the first image data D1.

[0116] The control unit 30 may prepare a test medium 99 in advance with the second image P2 printed on the second surface 99B, and acquire feature points P3 of the second image P2 based on the image captured by the imaging unit 15 from the second surface 99B of the test medium 99. The control unit 30 does not have to acquire feature points P3 of the second image P2 based on the second image data D2.

[0117] The pretreatment solution may be an ink containing a fluorescent pigment. The pretreatment solution may also be black pigment ink. In this case, the feature region P4 may be set to a region in the printing region of the first image P1 where white pigment ink is ejected.

[0118] The control unit 30 may calculate the edges of the printing area of ​​the first image P1 as feature points P3 of the first image P1. The control unit 30 may also calculate the areas other than the corners and edges of the printing area of ​​the first image P1 as feature points P3 of the first image P1.

[0119] The first image P1 and the second image P2 do not need to be images that are symmetrical on the front and back of the first surface 99A and the second surface 99B, as long as they are printed in corresponding positions on the first surface 99A and the second surface 99B.

[0120] The ink ejection unit 12 may be configured as at least one head. The ink ejection unit 12 and the pretreatment liquid ejection unit 14 may be configured as a single head if they are ejected from different nozzles.

[0121] The printing device 11 may include a plurality of ink ejection units 12. The printing device 11 may include a first ink ejection unit for printing a first image P1 on a first surface 99A and a second ink ejection unit for printing a second image P2 on a second surface 99B. The first ink ejection unit is provided upstream of the second ink ejection unit. In this case, it is not necessary to reposition the medium 99 when printing the first image P1 on the first surface 99A and when printing the second image P2 on the second surface 99B.

[0122] The printing apparatus 11 may include a plurality of imaging units 15. The printing apparatus 11 may include a first imaging unit that images the first surface 99A and a second imaging unit that images the second surface 99B. In this case, the first imaging unit is provided upstream of the first ink ejection unit. The second imaging unit is provided downstream of the first ink ejection unit and upstream of the second ink ejection unit.

[0123] The medium 99 is not limited to a roll. The medium 99 may be paper, resin films or sheets, resin-metal composite films, laminate films, textiles, nonwoven fabrics, metal foils, metal films, ceramic sheets, and clothing, etc.

[0124] The liquid can be any liquid that can adhere to the medium 99 and allow for recording on the medium 99. For example, ink may include functional material particles consisting of solids such as pigments or metal particles dissolved, dispersed, or mixed in a solvent, and shall encompass various compositions such as water-based inks, oil-based inks, gel inks, and hot-melt inks.

[0125] As used herein, the expression "at least one of" means one or more of the desired options. For example, as used herein, if there are two options, the expression "at least one of" means either one option or both of the two options. As another example, as used herein, if there are three or more options, the expression "at least one of" means either one option or any combination of two or more options.

[0126] [Note] The following describes the technical concepts and their effects as understood from the embodiments and modifications described above. These technical concepts and their effects can be combined with each other to the extent that they do not contradict each other.

[0127] [1] The printing apparatus comprises a pre-treatment liquid dispensing unit for dispensing a pre-treatment liquid onto a medium, an ink dispensing unit for dispensing ink onto a medium to print an image on the medium, an imaging unit for imaging the medium, and a control unit, wherein the control unit performs the following: dispensing a pre-treatment liquid onto a feature region of the first surface of the medium corresponding to a feature point of the first image or a feature point of the second image; dispensing ink onto the first surface of the medium on which the pre-treatment liquid has been dispensed onto the feature region to print the first image on the first surface; imaging the medium on which the first image has been printed from a second surface opposite to the first surface using the imaging unit; and correcting the second image to be printed on the second surface based on the image captured by the imaging unit and the feature points of the first image or the second image.

[0128] With this configuration, based on the image captured from the second surface of the medium, it is possible to recognize feature points of the first image or the second image that correspond to the feature region of the first surface where the pre-treatment liquid was discharged. This improves the accuracy of correcting the second image to be printed on the second surface. Therefore, the printing accuracy of both the first and second images can be improved.

[0129] [2] In the above-described printing apparatus, the control unit may print a second corrected image in which the second image has been corrected by ejecting ink from the ink ejection unit onto the second surface of the medium on which the first image has been printed. This configuration can achieve the same effect as [1].

[0130] [3] In the above-described printing apparatus, the control unit may perform the action of setting feature points in the first image or the second image. With this configuration, feature points can be arbitrarily set according to the first or second image.

[0131] [4] In the above-described printing apparatus, the pretreatment liquid discharge unit may discharge a penetrating liquid that promotes ink penetration as the pretreatment liquid. This configuration allows ink ejected into feature regions to easily penetrate from the first surface to the second surface. This makes it easier to recognize feature points in the first image or the second image corresponding to the feature regions of the first surface, based on the image captured from the second surface. This improves the accuracy of correcting the second image printed on the second surface. Therefore, the printing accuracy of both the first and second images can be improved.

[0132] [5] In the above-described printing apparatus, the imaging unit may use infrared light to image the medium. This configuration allows for the capture of images that include the conditions on both the first and second surfaces, not just the second surface, by using infrared light. Therefore, based on the image of the medium captured from the second surface, it becomes easier to recognize feature points in the first or second image that correspond to the feature regions of the first surface where the pre-treatment solution was dispensed. This improves the accuracy of correcting the second image printed on the second surface. Consequently, the printing accuracy of both the first and second images can be improved.

[0133] [6] In the above-mentioned printing apparatus, the pretreatment liquid discharge unit may discharge white ink as the pretreatment liquid. In this configuration, a white ink that reflects infrared light is ejected as a pretreatment solution. Therefore, based on the image captured from the second surface of the medium, it becomes easier to recognize feature points in the first image or the second image that correspond to the feature regions of the first surface where the pretreatment solution was ejected. This improves the accuracy of correcting the second image printed on the second surface. Consequently, the printing accuracy of both the first and second images can be improved.

[0134] [7] In the above-described printing apparatus, the ink ejection unit may eject pigment ink. This configuration can achieve the same effect as [6]. [8] In the above-described printing apparatus, the control unit may set feature points of the first image or feature points of the second image in the region where black ink is ejected in the first image, and the pretreatment liquid ejection unit may eject white ink as a pretreatment liquid in the feature region where black ink is ejected in the first image.

[0135] In this configuration, white ink is ejected as a pretreatment solution in the feature region of the first image where infrared-absorbing black ink is ejected. Therefore, based on the image captured from the second surface of the medium, it becomes easier to recognize the feature points of the first image or the second image that correspond to the feature region of the first surface where the pretreatment solution was ejected. This improves the accuracy of correcting the second image to be printed on the second surface. Consequently, the printing accuracy of both the first and second images can be improved.

[0136] [9] In the above-described printing apparatus, the control unit may adjust the amount of pretreatment liquid to be discharged to the pretreatment liquid discharge unit based on the thickness of the medium. With this configuration, by adjusting the amount of pretreatment solution dispensed according to the thickness of the medium, it becomes easier to recognize feature points in the first image or the second image that correspond to the feature region of the first surface where the pretreatment solution was dispensed, based on the image captured from the second surface of the medium. This improves the accuracy of correcting the second image to be printed on the second surface. Therefore, the printing accuracy of both the first and second images can be improved.

[0137]

[10] A method for controlling a printing apparatus, which prints a first image by ejecting ink onto a first surface of a medium and prints a second image by ejecting ink onto a second surface of the medium opposite to the first surface, comprising: ejecting a pre-treatment liquid onto a feature region of the first surface corresponding to a feature point of the first image or a feature point of the second image; printing the first image onto the first surface by ejecting ink onto the first surface of the medium onto which the pre-treatment liquid has been ejected to the feature region; capturing an image of the medium on which the first image is printed from the second surface; and correcting the second image to be printed on the second surface based on the captured image and the feature points of the first image or the feature points of the second image. This configuration can achieve the same effect as [1]. [Explanation of Symbols]

[0138] 11...Printing device, 12...Ink ejection unit, 13...Conveyor unit, 14...Pre-treatment liquid ejection unit, 15...Imaging unit, 21...First roller, 22...Second roller, 23...Conveyor belt, 24...Roller drive unit, 30...Control unit, 31...Processor, 32...Memory, 99...Media, 99A...First surface, 99B...Second surface, C1...First centerline, C2...Second centerline, D...Conveyor direction, D1...First image data, D2...Second image data, D3...Feature point data, D4...Feature region data, D5...Imaging image data, P1...First image, P2...Second image, P3...Feature point, P4...Feature region, X1...First width direction, X2...Second width direction, Y1...Forward, Y2...Backward, Z1...Upward, Z2...Downward.

Claims

1. A pretreatment liquid discharge unit that discharges a pretreatment liquid onto the medium, An ink ejection unit that prints an image onto a medium by ejecting ink onto the medium, An imaging unit that images the medium, Control unit and Equipped with, The control unit, Dispensing a pre-treatment liquid from the pre-treatment liquid dispensing unit to a feature region on the first surface of a medium corresponding to a feature point of the first image or a feature point of the second image, The first image is printed on the first surface of the medium on which the pretreatment liquid has been discharged to the characteristic region by discharging ink from the ink discharge unit onto the first surface. The medium on which the first image is printed is to be imaged by the imaging unit from the second surface, which is the opposite surface to the first surface, The system performs the following actions: correcting the second image to be printed on the second surface based on the captured image taken by the imaging unit and the feature points of the first image or the feature points of the second image. A printing apparatus characterized by the following features.

2. A printing apparatus according to claim 1, The control unit prints a second corrected image, which is a corrected version of the second image, by causing the ink ejection unit to eject ink onto the second surface of the medium on which the first image is printed. A printing apparatus characterized by the following features.

3. A printing apparatus according to claim 2, The control unit performs the action of setting feature points in the first image or the second image. A printing apparatus characterized by the following features.

4. A printing apparatus according to any one of claims 1 to 3, The aforementioned pretreatment liquid dispensing unit dispenses a penetrating liquid as a pretreatment liquid to promote ink penetration. A printing apparatus characterized by the following features.

5. A printing apparatus according to any one of claims 1 to 3, The imaging unit uses infrared light to image the medium. A printing apparatus characterized by the following features.

6. A printing apparatus according to claim 5, The aforementioned pretreatment liquid dispensing unit dispenses white ink as the pretreatment liquid. A printing apparatus characterized by the following features.

7. A printing apparatus according to claim 6, The ink ejection unit ejects pigment ink. A printing apparatus characterized by the following features.

8. A printing apparatus according to claim 7, The control unit performs the action of setting a feature point of the first image or a feature point of the second image for the region in the first image where black ink is ejected. The pretreatment liquid dispensing unit dispenses white ink as a pretreatment liquid into the feature region where black ink is dispensed in the first image. A printing apparatus characterized by the following features.

9. A printing apparatus according to any one of claims 1 to 3, The control unit adjusts the amount of pretreatment liquid to be discharged to the pretreatment liquid discharge unit based on the thickness of the medium. A printing apparatus characterized by the following features.

10. A control method for a printing apparatus that prints a first image by ejecting ink onto a first surface of a medium, and prints a second image by ejecting ink onto a second surface of the medium opposite to the first surface, Dispensing a pretreatment solution to a feature region of the first surface corresponding to a feature point of the first image or a feature point of the second image, Printing a first image on the first surface by ejecting ink onto the first surface of a medium onto which a pre-treatment liquid has been ejected in the characteristic region, The medium on which the first image is printed is to be imaged from the second surface, The process involves correcting the second image to be printed on the second surface based on the captured image and the feature points of the first image or the feature points of the second image. A method for controlling a printing apparatus, characterized by the following:

Images