Printing apparatus, control method of printing apparatus, storage medium, and computer program product

Abstract

The invention provides a printing apparatus, a control method of the printing apparatus, a storage medium, and a computer program product. The printing apparatus includes: a feeding unit for feeding a printing medium; a printing unit including a first array of printing elements and a second array of printing elements for applying a first ink and a second ink onto a printing medium, respectively; and a fixing unit located downstream of the printing unit in the feeding direction to fix the image printed on the printing medium. The printing unit prints a first image on a printing medium by applying a first ink. The feeding unit feeds a printing medium on which a first image is printed to the fixing unit from upstream to downstream in a feeding direction. The fixing unit fixes the first image. The feeding unit reversely feeds the printing medium on which the first image is fixed to the printing unit from downstream to upstream in a feeding direction. The printing unit prints a second image on the first image by applying a second ink.

Description

Technical Field

[0001] The present disclosure relates to a printing apparatus for printing an image by ejecting ink from nozzles of a print head. Background Art

[0002] Inkjet printing devices for printing images by ejecting ink onto a non-absorbent or low-absorbent printing medium and drying the ink applied to the printing medium using a fixing unit having a heating or air supply function are known. In some cases, such devices can be used to print images on colored or transparent printing media having a lower reflectivity than white printing media. In addition, in order to print high-quality images, it is necessary to adjust the print head and the printing device using the printing medium on which the image is actually to be printed.

[0003] Japanese Patent Application Laid-Open No. 2021-133601 discloses a technique for color measurement by printing an adjustment pattern using a printing medium having a backing and a sheet attached to the backing. In this technique, a color chart is printed after a base is printed using white ink to eliminate the influence of the color of the backing.

[0004] However, Japanese Patent Laid-Open No. 2021-133601 does not consider a fixing step of drying the ink using a fixing unit with a heating or air supply function. After printing a substrate on a non-absorbent or low-absorbent printing medium using a first ink, an adjustment pattern is printed using a second ink without subjecting the substrate to a fixing step. In this case, the colors of the first ink and the second ink may be mixed because the substrate is not sufficiently dried. Therefore, this leads to problems such as the printing position of the second ink being shifted and the dots failing to have the desired shape.

[0005] In view of the above-mentioned problems, the present disclosure is directed to enabling various adjustments to a printing apparatus capable of printing using white ink to be automatically performed. Summary of the invention

[0006] An embodiment of the present invention is a printing device, comprising: a feeding unit for feeding a printing medium; a printing unit including a first printing element array for applying a first ink to the printing medium among a plurality of printing elements and a second printing element array for applying a second ink to the printing medium among a plurality of printing elements; and a fixing unit, which is located downstream of the printing unit in a feeding direction and fixes an image printed on the printing medium. The printing unit prints a first image on the printing medium by applying the first ink, the feeding unit feeds the printing medium on which the first image has been printed to the fixing unit from upstream to downstream in the feeding direction, the fixing unit fixes the first image, the feeding unit reversely feeds the printing medium on which the first image has been fixed to the printing unit from downstream to upstream in the feeding direction, and the printing unit prints a second image on the first image by applying the second ink.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a stereogram of the printing device;

[0009] Figure 2 is a schematic side view of a printing apparatus;

[0010] Figure 3 is a schematic diagram of the print head;

[0011] Figure 4A and Figure 4B is a schematic diagram of an optical sensor;

[0012] Figure 5 is a block diagram showing the configuration of a control system of a printing apparatus;

[0013] FIG. 6A to FIG. 6C is a diagram showing multi-pass printing;

[0014] 7A to 7C is a diagram showing a registration adjustment pattern;

[0015] Figure 8 is a flowchart of processing performed when performing registration adjustment processing (or conveyance adjustment processing);

[0016] Fig. 9A and Fig. 9B is a diagram showing a conveying adjustment pattern;

[0017] Fig. 10A and Fig. 10B is a flow chart of the processing performed when performing color calibration;

[0018] Fig.11 is a diagram showing a color calibration adjustment pattern;

[0019] FIG. 12A to FIG. 12D is a schematic diagram showing a state in which an image to be used as a base is fixed;

[0020] FIG. 13A to FIG. 13C is a schematic diagram showing a case where an image to be used as a base is not fixed;

[0021] Fig.14 is a flow chart of the processing performed when performing various adjustments;

[0022] Fig.15 is a detailed flow chart of S1403;

[0023] Fig.16 is a flow chart of a process for printing a given image on a base image; and

[0024] Fig.17 This is a flowchart of color calibration of the W nozzle. DETAILED DESCRIPTION

[0025] [First embodiment]

[0026] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0027] <Configuration of inkjet printing device>

[0028] Figure 1 1 is a perspective view showing the appearance of an inkjet printing apparatus A (hereinafter also referred to as a printing apparatus or a printer) according to the present embodiment. The printing apparatus A is a so-called serial scanning printer, and prints an image by scanning a print head in an X direction (main scanning direction) intersecting (or specifically, orthogonal) with a Y direction (sub-scanning direction), in which the printing medium P is conveyed. Figure 1 The configuration of the printing apparatus A and an overview of its printing operation are described.

[0029] First, the print medium P is conveyed in the Y direction toward the take-up shaft 12 for holding the print medium P by a conveying roller driven by a conveying motor (not shown) via a gear. On the other hand, when the print medium P is at a predetermined conveying position, the carriage 22 is scanned (moved) in a reciprocating manner along the guide shaft 8 extending in the X direction by a carriage motor (not shown). Then, in this scanning process, an inkjet operation is performed at a timing based on a position signal obtained by the encoder 7. In the inkjet operation, ink is ejected from the nozzle of a print head (described later) that can be attached to the carriage 22, thereby printing an image with a certain bandwidth corresponding to the range of the nozzle array. Thereafter, the print medium P is conveyed, and an image of the next bandwidth is printed. The printing device A of the present embodiment is configured to perform a jetting operation at a scanning speed of 40 inches per second and a printing resolution of 1200dpi (1 / 1200 inch intervals). However, the print head can also be scanned at a speed faster than 40 inches per second.

[0030] A carriage belt may be used to transmit the driving force of the carriage motor to the carriage 22. Note that, for example, other transmission means (such as a configuration having a lead screw extending in the X direction and driven and rotated by the carriage motor and an engagement unit provided to the carriage 22 and configured to engage with a groove on the lead screw) may be used instead of the carriage belt.

[0031] The print medium P being fed is sandwiched and conveyed between the paper feed roller and the clamping roller, and is guided to the printing position on the platen 4 (a position within the area where the print head can scan and the print head prints). Hereinafter, the image printing configuration around the printing position is referred to as an "image printing unit" (image printing component). In a state where the printing device is in an idle state, the face surface of the print head is usually covered. Therefore, the cover is removed before printing to put the print head into a printable / scannable state. Thereafter, once the data for one scan is accumulated in the buffer, the carriage 22 is scanned by the carriage motor, and printing is performed as described above.

[0032] Figure 2: is a schematic side view of the main body of the printing device A. A curing region is arranged downstream in the sub-scanning direction Y of the position where the print head 9 attached to the carriage 22 scans in a reciprocating manner in the X direction (main scanning direction) (hereinafter, the image fixing configuration around the curing region is referred to as an "image fixing unit (image fixing component)"). In the image fixing unit, a heater 10 is provided and supported on a frame (not shown), and uses heat to dry the ink in liquid form on the printing medium P. The heater 10 is covered by a heater cover 11, and the heater cover 11 serves the function of enabling the heat from the heater 10 to be efficiently applied to the printing medium P and the function of protecting the heater 10. After printing an image on the printing medium P by the print head 9, the printing medium P is wound around the winding shaft 12 and formed into a rolled winding medium. Specific examples of the heater 10 include an armored heater and a halogen heater. Taking into account the film forming property and productivity related to the water-soluble resin particles and the heat resistance of the printing medium P, the heating temperature of the heater at the above-mentioned image fixing unit is set. Note that the heating of the heating unit in the image fixing unit may be, for example, heating from above by blowing hot air or heating from below the print medium using a contact-type thermal conduction heater. In addition, although the heating unit is located at a single location in the present embodiment, the heating unit may be provided at two locations and used together as long as the measured temperature measured above the print medium P by a radiation thermometer (not shown) does not exceed the set value of the heating temperature.

[0033] The printing apparatus A in this embodiment can perform so-called multi-pass printing in which an image is printed on a predetermined area (1 / n band) on the print medium P by multiple scans (n ​​scans) of the print head. Details of this multi-pass printing will be described later.

[0034] <Print Head Configuration>

[0035] Figure 3 The nozzle face 34 of the print head 9 in the present embodiment is shown. The print head 9 has a nozzle array 33K for ejecting black ink, a nozzle array 33C for ejecting cyan ink, a nozzle array 33M for ejecting magenta ink, a nozzle array 33Y for ejecting yellow ink, and a nozzle array 33W for ejecting white ink. Note that in the case where there is no need to make any particular distinction between colors, they are collectively referred to herein as the nozzle array 33. In addition, this collective rule is similarly applied to constituent elements other than the nozzle array.

[0036] In the print head 9, the nozzle array 33K, the nozzle array 33C, the nozzle array 33M, the nozzle array 33Y and the nozzle array 33W are arranged in this order in the +X direction. Each of these nozzle arrays is composed of 1280 nozzles 30 arranged in the Y direction (array direction) at a density of 1200 dpi, and the nozzles 30 eject corresponding inks. Note that in this embodiment, the amount of ink ejected from a single nozzle 30 is about 4.5 pl.

[0037] These nozzle arrays are connected to their respective ink tanks (not shown) storing corresponding inks and are supplied with ink. Note that the print head 9 and the ink tanks in the present embodiment may be configured integrally with each other or separately from each other.

[0038] Energy generating elements (hereinafter also referred to as printing elements) are provided at the print head 9. Each energy generating element generates ejection energy for ejecting ink from the nozzle. An electrothermal converter for locally heating ink to cause film boiling and ejecting ink using the pressure of film boiling is used as the energy generating element. However, the technology disclosed in the present invention is not limited to the electrothermal converter, and can also be applied to the case of using an electromechanical conversion element.

[0039] <Optical Sensor>

[0040] Figure 4A is a schematic diagram showing a schematic configuration of an optical sensor, and Figure 4B 2 is a diagram showing a detection light spot. The optical sensor 200 is provided and fixed to the carriage 22 so that the measurement area can be located downstream in the Y direction (i.e., +Y direction) of the plurality of nozzle arrays provided at the print head 9. The lower surface 200a of the optical sensor 200 is located at the same position as the nozzle face 34 in the Z direction, or downstream of the nozzle face 34 in the +Z direction.

[0041] The optical sensor 200 has a light emitting unit 202 implemented by a visible LED of, for example, red, green, or blue, and a light receiving unit 204 implemented by a photodiode. The light emitting unit 202 and the light receiving unit 204 are disposed at a lower surface 200a of the optical sensor 200. The light emitting unit 202 irradiates the print medium P with light, and the light receiving unit 204 receives light reflected from the print medium P. Thus, in the optical sensor 200, light 206 emitted from the light emitting unit 202 is irregularly reflected by the print medium P, and the reflected light 208 is received by the light receiving unit 204. The diameter of a detection light spot 210 where the light emitted by the light emitting unit 202 is irregularly reflected by the print medium P is, for example, approximately 3 mm.

[0042] The light receiving unit 204 transmits a detection signal (analog signal) of the received reflected light 208 to a control circuit on a circuit board in the printing apparatus A via a flexible cable (not shown) or the like, and the detection signal is converted into a digital signal by an A / D converter in the control circuit. In order to detect the optical characteristics of an adjustment pattern to be described later, the conveyance of the print medium P in the Y direction and the movement of the carriage 22 to which the optical sensor 200 is attached in the X direction are alternately performed. Then, in synchronization with the timing based on the position signal obtained by the encoder 7, the optical sensor 200 detects the density of the image printed on the print medium P as an optical reflectance.

[0043] <Control system configuration>

[0044] The configuration of the control system of the printing apparatus A is described below. Figure 5 is a block diagram showing the configuration of a control system of a printing apparatus.

[0045] The control unit 100 for performing overall control of the printing apparatus has a CPU 102, a ROM 104, a RAM 106, and a memory 108. Based on various programs, the CPU 102 performs, for example, control of the operation of each constituent element of the printing apparatus and processing of input image data. The ROM 104 is used as a memory for storing programs such as programs related to various controls performed by the CPU 102 and programs related to processing of image data. The RAM 106 temporarily stores various data used for control of the printing apparatus. The memory 108 stores various data such as a mask pattern and an adjustment pattern to be described later. The control unit 100 also has an input / output port 110, and is connected to various drivers and drive circuits and the like via the input / output port 110.

[0046] The control unit 100 is connected to an interface circuit 112 via an input / output port 110, and is connected to a host device 114 via the interface circuit 112. The control unit 100 is also connected to an operation panel 124 operable by a user via the input / output port 110. The user inputs image data to the printing device via the host device 114, and inputs various information to the printing device via the host device 114 and the operation panel 124. The control unit 100 is also connected to a motor driver 116 via the input / output port 110, and controls the driving of a motor 118 via the motor driver 116. Note that in Figure 5 In the figure, various motors in the printing apparatus (such as a motor for moving the carriage 22 and a motor for driving a conveying unit for conveying a printing medium) are collectively referred to as a motor 118.

[0047] The control unit 100 is connected to the head driver 120 via the input / output port 110, and ejects ink by controlling the print head 9 via the head driver 120. The control unit 100 is also connected to the drive circuit 122 via the input / output port 110, and controls the driving of the heater 10 via the drive circuit 122. The control unit 100 is also connected to the optical sensor 200 via the input / output port 110, and the control unit 100 controls the driving of the optical sensor 200 and detects the optical characteristics of the adjustment pattern based on the output from the optical sensor 200. In this way, in the present embodiment, the control unit 100 and the optical sensor 200 function as a detection unit capable of detecting the optical characteristics of an image printed on a print medium.

[0048] In the control unit 100, the CPU 102 converts the image data input from the host device 114 into print data, and stores the print data in the RAM 106. Specifically, after obtaining bitmap image data represented by 8-bit (256-level) information (0 to 255) of R, G, and B respectively, the CPU 102 converts the image data into multi-value data represented by K, C, M, Y, and W used in printing. Through this color conversion processing, multi-value data representing each of a plurality of pixels by 8-bit 256-level information (0 to 255) for defining the gradation of ink K, C, M, Y, and W is generated.

[0049] Next, multi-value data represented by K, C, M, Y, and W are quantized to generate quantized data (binary data) in which, for each pixel, each of K, C, M, Y, and W inks is represented by 1-bit binary information (0 or 1) indicating whether ink is ejected to the pixel. The quantization process can be performed using various well-known quantization methods such as an error diffusion method, a dithering method, and an indexing method. Thereafter, an allocation process is performed to allocate the quantized data to multiple scans performed by the print head 9 for a unit area. As a result of the allocation process, print data represented by 1-bit binary information (0 or 1) is generated, and the 1-bit binary information is used to define whether each of K, C, M, Y, and W inks is ejected for each pixel in each of the multiple scans on the unit area on the print medium P. The allocation process is performed using a mask pattern for defining whether ink ejection to each pixel is permitted, and the mask pattern corresponds to the corresponding multiple scans. Note that the generation of print data is not limited to being performed by the control unit 100. The processing may be performed by the host device 114 , or part of the processing may be performed by the host device 114 and the rest of the processing may be performed by the control unit 100 .

[0050] <Multi-pass printing method>

[0051] In the present embodiment, the printing apparatus prints an image using so-called multi-pass printing in which an image is printed on a predetermined area of ​​a printing medium with a plurality of scans using K, C, M, Y, and W inks.

[0052] First, multi-pass printing using the entire nozzle array area is described using W ink and K ink as examples.

[0053] Fig. 6A 33W and 33K are each divided into six nozzle groups A1 to A6 arranged in the Y direction, and W ink and K ink are ejected from the corresponding six nozzle groups A1 to A6 to a predetermined area in six scans. The print data for W ink and the print data for K ink are each assigned to the six scans, so that the printing of an image can be completed by the six scans. Although the print medium P is actually transported downstream in the Y direction between scans of the print head 9, the print head 9 FIG. 6A to FIG. 6C is depicted as if moving upstream in the Y direction between scans.

[0054] First, in the first scan (scan 1), W ink and K ink are ejected from the nozzle group A1 in the nozzle array 33W and the nozzle array 33K to the predetermined area 80 according to the print data for W ink and the print data for K ink corresponding to scan 1. After the completion of scan 1, the print medium is conveyed in the Y direction by a distance corresponding to a single nozzle group. Thereafter, the second scan (scan 2) is performed, and W ink and K ink are ejected from the nozzle group A2 to the predetermined area 80. Thereafter, the conveyance of the print medium and the ejection of ink from the print head are alternately performed to eject ink from the nozzle groups A3 to A6 to the predetermined area 80 in the third to sixth scans. Thus, the multi-pass printing of the predetermined area 80 is completed.

[0055] Next, a multi-pass printing method using different areas of the nozzle array for each color of ink is described. Figure 6B 3 is a diagram showing nozzle areas corresponding to nozzle groups A1 to A3 and nozzle areas corresponding to nozzle groups A4 to A6 in all nozzles of nozzle arrays 33K and nozzle arrays 33W. Nozzle array 33K has nozzle area 44K including nozzle groups A1 to A3 and nozzle area 55K including nozzle groups A4 to A6. Similarly, nozzle array 33W has nozzle area 44W including nozzle groups A1 to A3 and nozzle area 55W including nozzle groups A4 to A6.

[0056] Figure 6C It is shown in Fig. 6AThe nozzle groups A1 to A6 shown in the figure eject W ink from the nozzle groups A1 to A3 in the nozzle area 44W and eject K ink from the nozzle groups A4 to A6 in the nozzle area 55K. The print data for the W ink is allocated so that the printing of the image can be completed through the first scan to the third scan, and the print data for the K ink is allocated so that the printing of the image can be completed through the fourth scan to the sixth scan.

[0057] First, in the first scan (scan 1), W ink is ejected from the nozzle group A1 in the nozzle array 33W to the predetermined area 80 according to the print data for W ink corresponding to scan 1. After the completion of scan 1, the print medium is conveyed in the Y direction by a distance corresponding to the single nozzle group. Thereafter, the conveyance of the print medium and the ejection of ink from the print head are alternately performed to perform the second and third scans (scan 2 and scan 3), and W ink is ejected from the nozzle groups A2 and A3 in the nozzle array 33W to the predetermined area 80. The image of W ink is completed by the printing in scan 3. Next, K ink is ejected from the nozzle group A4 in the nozzle array 33K to the predetermined area 80 according to the print data for K ink corresponding to scan 4. Thereafter, the conveyance of the print medium and the ejection of ink from the print head are alternately performed to perform the fifth and sixth scans for the predetermined area 80, and K ink is ejected from the nozzle groups A5 and A6 in the nozzle array 33K. Thus, the multi-pass printing on the predetermined area 80 is completed.

[0058] In this way, different sets of nozzle array groups are used for W ink and K ink, so that in the six scans for the predetermined area 80, the first three scans are used to complete the image of W ink, and the last three scans are used to complete the image of K ink. Thus, on the predetermined area 80, the image of K ink can be printed above the image printed using W ink.

[0059] <Ink>

[0060] The K ink, C ink, M ink, Y ink and W ink used in this embodiment are described below. Each of these inks contains a solid component for printing an image and a liquid component that evaporates. Examples of the solid component include colorants such as pigments and dyes, and examples of the liquid component include water and water-soluble organic solvents. All inks contain water-soluble resin particles for making the colorant in close contact with the print medium and improving the wear resistance (fixability) of the printed image.

[0061] <Print Media>

[0062] The printing device in this embodiment prints on a low-permeability printing medium that is difficult for water to penetrate. As mentioned above, the low-permeability printing medium in this article refers to a medium that does not absorb water at all or absorbs only a small amount of water. Therefore, a water-based ink that does not contain an organic solvent is repelled and an image cannot be printed. However, the low-permeability printing medium is excellent in water resistance and weather resistance, and is suitable as a medium for printing images to obtain printed products intended for outdoor use. Generally, a printing medium having a water contact angle of 45° or more, or preferably 60° or more at 25°C is used.

[0063] Examples of low-permeability printing media include printing media formed with a plastic layer as the outermost surface of a substrate; printing materials on which an ink receiving layer is not formed; sheets or films of glass, YUPO, or plastic; and banners. Examples of the plastic applied thereto include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. These low-permeability printing media are excellent in water resistance, light resistance, and abrasion resistance, and are therefore generally used for printing of printed products for outdoor display.

[0064] As an example of a method for evaluating the permeability of a printing medium, the Bristow method described in "Method for Determining Liquid Absorbency of Paper and Paperboard" in JAPAN TAPPI's Paper and Pulp Test Method No. 51 can be used. The measurement method using the Bristow method is briefly described below. First, a predetermined amount of ink is poured into a storage container having an opening slit of a predetermined size. Then, the storage container is brought into contact with a printing medium processed into a strip shape and wound around a disk through the slit. Next, the disk is rotated with the storage container fixed in place, and the area (length) of the ink ribbon transferred to the printing medium is measured. Based on the area of ​​the ink ribbon, the transfer amount per unit area per second (ml·m -2 ). In this embodiment, the Bristow method is used to calculate the 1 / 2 The ink transfer amount (absorption amount) measured is less than 10ml·m -2 In this case, the print medium is considered to be low-permeability print medium.

[0065] <Various Adjustments>

[0066] Various adjustments performed in this embodiment are described below.

[0067] (1) Registration adjustment

[0068] First, registration adjustment is described in concrete terms.

[0069] The print head 9 in this embodiment moves in the main scanning direction and has inkjet nozzles arranged in a direction (sub-scanning direction) intersecting the main scanning direction. A printing device using such a print head 9 needs to perform a process for obtaining appropriate ejection timing to make the landing positions of ink droplets ejected from each nozzle array consistent (such a process is called registration adjustment).

[0070] Registration adjustment is also performed in bidirectional printing, in which printing is performed while the print head is scanning in a reciprocating manner, so that the landing position of the printing in the forward direction and the landing position of the printing in the return direction coincide with each other. Registration adjustment in bidirectional printing is achieved by correcting the ejection timing of the printing in the return direction relative to the printing in the forward direction.

[0071] An example method for registration adjustment is to solve a correction amount for registration adjustment for making the printing position consistent by printing a reference pattern with a certain nozzle array used as a reference and printing a plurality of patterns at gradually shifted printing positions with another nozzle array (hereinafter the correction amount is referred to as a registration adjustment value). Another method is to solve a correction amount for registration adjustment for making the printing position consistent between the forward direction and the backward direction by printing a reference pattern in printing in the forward direction and printing a plurality of patterns with shifted printing positions in printing in the backward direction.

[0072] refer to 7A to 7C The configuration of the registration adjustment pattern used in the registration adjustment process will be described.

[0073] Fig. 7A : is a diagram showing an example configuration of a registration pattern used for density detection by the optical sensor of the present embodiment.

[0074] The registration adjustment pattern is configured so that a rectangular pattern of i pixels × n pixels is repeated in the main scanning direction at intervals with a blank area of ​​m pixels inserted therebetween. The registration adjustment pattern includes a reference pattern 501 and an offset pattern 502, and the offset pattern 502 is printed at a printing position offset from the reference pattern 501 by a distance a corresponding to a predetermined number of pixels. The resolution and offset amount of the registration adjustment pattern can be determined according to the printing resolution of the printing device. Note that in this embodiment, the printing resolution is 1200 dpi. Although for ease of illustration, Fig. 7A The reference pattern and the offset pattern are drawn as if they are misaligned in the longitudinal direction, but these printed patterns actually overlap. In other words, the reference pattern is printed while overlapping with the offset pattern offset in the main scanning direction by a distance a corresponding to a predetermined number of pixels.

[0075] Figure 7B The arrangement in the main scanning direction is shown Fig. 7AIn this case, when the offset amount a of the offset pattern changes from -3 pixels to +3 pixels, the print Figure 7B In other words, as shown in FIG. Figure 7B It can be understood that, in the case where the offset is 0, the offset pattern is printed directly above the reference pattern. On the other hand, the larger the offset, the more the offset pattern is offset from the reference pattern, and thus the wider the pattern. For convenience, Figure 7B An example is shown in which the offset pattern is least offset relative to the reference pattern when the offset amount is 0. However, for the registration adjustment pattern actually printed, the value of the shift amount at which the offset pattern is least offset relative to the reference pattern differs depending on various conditions.

[0076] like Figure 7B As shown, different offset amounts of the printing positions between the reference pattern and the offset pattern result in different proportions of the ink area occupying the printed medium.

[0077] Figure 7C The optical sensor 200 measures Figure 7B 720 shows the measurement result of the optical reflectance obtained for the offset pattern shown. Note that the density and the reflectance have an inverse relationship with each other, and the smaller the positional offset between the patterns in the registration adjustment pattern actually printed on the print medium, the lower the density. In other words, the offset pattern with a higher reflectance is the pattern with a smaller positional offset; therefore, the offset amount of the registration adjustment pattern with the lowest density is set as the registration adjustment value.

[0078] Note that the number of registration adjustment patterns printed on the print medium and their offsets can be determined based on the adjustment range required by the mechanical tolerance of the device and the offset unit of the print position. In other words, they can be determined based on the accuracy of the registration adjustment process. In addition, the print area of ​​the registration adjustment pattern can be determined, for example, based on the size of the area detected by the optical sensor 200, the width of the area printable using a single print scan, and the size of the printable area of ​​the registration adjustment pattern group and the print medium.

[0079] In addition, the nozzle array used to print the reference pattern and the offset pattern is determined based on a combination of the ink color and the scanning direction of the nozzle array to be adjusted. For example, in order to perform registration adjustment of the ink color of the nozzle array, a reference nozzle array (e.g., nozzle array 33K) is determined, and the reference pattern is printed by the reference nozzle array. Then, another nozzle array (e.g., nozzle array 33C) is used to print the offset pattern. In the case of bidirectional printing, the registration adjustment can be performed in a manner similar to that described above. For example, the reference pattern is printed in the forward direction using nozzle array 33K, and the offset pattern is printed in the backward direction using nozzle array 33K. Thus, the registration adjustment of bidirectional printing using the same nozzle array 33K can be accurately performed. Note that the combination of nozzle arrays is not limited to this, and any nozzle arrays can be combined.

[0080] The registration adjustment value is determined or set based on the positional offset a thus determined. The registration adjustment value is a value indicating a correction amount of ink ejection timing, and the ink ejection timing of each nozzle array is controlled based on the registration adjustment value. Note that the positional offset a may be directly used as the registration adjustment value, or a value derived based on the positional offset a may be used as the registration adjustment value.

[0081] Figure 8 : is a flowchart of the registration adjustment process performed using the white print medium in this embodiment.

[0082] First, in step S801, the CPU 102 executes light intensity adjustment processing of the optical sensor 200 using the paper white portion of the print medium. Note that, for the sake of brevity, "step SXXX" is hereinafter simply referred to as "SXXX".

[0083] In S802, the CPU 102 executes a print process using the image printing unit to print the image on a print medium. Fig. 7A and Figure 7B Adjustment pattern shown.

[0084] In S803 , the CPU 102 executes a reading process using the optical sensor to read the adjustment pattern printed in S802 .

[0085] In S804 , the CPU 102 calculates an adjustment value based on the read detection result in S803 .

[0086] In S805 , the CPU 102 sets the registration adjustment value (ie, stores the adjustment value calculated in S804 into the RAM 106 ).

[0087] In S806, the CPU 102 feeds the print medium so as not to cause stains on the ink used to print the adjustment pattern. As a result of the feeding in this step, the adjustment pattern printed on the print medium is brought to the image fixing unit. Note that feeding means conveying the print medium in the forward direction. The forward direction is the direction from upstream to downstream in the conveying direction, i.e., the +Y direction (see FIG. 1 ). Figure 1 In addition, as a conceivable way of performing control to “bring the adjustment pattern printed on the printing medium to the image fixing unit”, for example, the number of revolutions of the motor corresponding to the distance between the optical sensor and the image fixing unit is stored in advance, and the stored number of revolutions is compared with the actual number of revolutions in actual operation.

[0088] Finally, in S807 , the CPU 102 executes a fixing process for fixing ink used to print the adjustment pattern onto the print medium using the image fixing unit, and the registration adjustment process ends.

[0089] (2) Transportation adjustment

[0090] Next, delivery adjustment is described in specific terms.

[0091] The conveyance adjustment is used to make corrections with respect to the sub-scanning direction (the conveyance amount of the print medium) so that the landing positions of dots formed by the previous print scan and the landing positions of dots formed by the subsequent print scan performed after the conveyance of the print medium can coincide with each other. One method for the conveyance adjustment is to measure the change in the conveyance amount that occurs when the print medium is conveyed by calculating the change in the conveyance amount based on the difference between two adjustment patterns.

[0092] Fig. 9A and Fig. 9B 3 is a diagram showing an example of printing a conveyance adjustment pattern using the nozzle array 33K. Fig. 9A and Fig. 9B As shown, a single adjustment pattern consists of seven blocks (in Fig. 9A and Fig. 9B Although seven blocks are used as an example here, the number of blocks is not limited to seven, and any number of blocks can be set according to the ink and print medium used so that the optimal conveying amount can be set.

[0093] The nozzles of a single array are divided into two parts in the sub-scanning direction. The nozzles of the downstream part are called block 1, and the nozzles of the upstream part are called block 2. First, as Fig. 9A As shown, the reference pattern is printed using a predetermined nozzle located in the block 2 located upstream in the sub-scanning direction. The seven reference patterns arranged in the carriage scanning direction are printed by the same predetermined nozzle in the block 2.

[0094] Next, the command pulse value is set to 5120, and the print medium is fed. Fig. 9B As shown, the seven offset patterns printed using the nozzles in block 1 are each printed using a different combination of nozzles, thereby offset relative to the reference pattern. Here, hollow dots are used to show dots printed using upstream nozzles, and solid dots are used to show dots printed using downstream nozzles. In this way, a single block is formed by the reference pattern and the offset pattern printed by different printing scans from each other.

[0095] Although the conveying resolution is a value depending on the performance of the printer, the printer here can convey the print medium at a resolution of 9600 dpi. Under these conditions, the command pulse value for conveying the print medium by a distance corresponding to half the nozzles (the number of nozzles in the half nozzle array × the resolution of the nozzle array / the resolution of the conveying amount) is as follows.

[0096] 640×25.4 / 1200 / 25.4×9600=5120 …(1)

[0097] Note that in equation (1), the number of nozzles in half the nozzle array is 640, the resolution of the nozzle array (nozzle spacing) is 1200 dpi, and the resolution of the conveying amount is 9600 dpi. In addition, the ideal value of the conveying amount of the print medium conveyed in response to the command pulse value (5120) is as follows.

[0098] 640×25.4 / 1200=13.55[mm]…(2)

[0099] After the print medium is conveyed by the above-mentioned ideal value of the conveyance amount of the print medium, the adjustment pattern is printed using the downstream nozzles of the print head.

[0100] For convenience, Fig. 9B An example is shown in which block 3 has the smallest offset between the reference pattern and the offset pattern. However, on an actually printed conveyance adjustment pattern, a block identification number having the smallest offset between the reference pattern and the offset pattern differs depending on various conditions.

[0101] Also in the conveyance adjustment, the smaller the positional offset between the reference pattern and the offset pattern printed on the print medium, the lower the density. Therefore, the amount of conveyance of the print medium to print the block with the lowest density is the ideal conveyance amount. Therefore, similar to the above-mentioned (1) registration adjustment, the optimal paper conveyance amount can be derived by selecting the block with the lowest density (block with high reflectivity).

[0102] Although in the present embodiment the reference pattern is printed using the nozzles in the upstream block 2 and the offset pattern is printed using the nozzles in the downstream block 1 , it does not matter which of the blocks 1 and 2 is used for which pattern.

[0103] Figure 8 is a flowchart of the conveyance adjustment process performed using white print media in this embodiment. The conveyance adjustment process can be performed using the same flowchart as the above-mentioned (1) registration adjustment. In other words, in (1) registration adjustment, the adjustment pattern printed in S802 is Fig. 7A and Figure 7B The registration adjustment pattern shown, while in (2) conveying adjustment, the adjustment pattern printed in S802 is Fig. 9A and Fig. 9B Since the conveyance adjustment process and the registration adjustment process differ only in the adjustment pattern to be printed, the flowchart of the conveyance adjustment process is not described here.

[0104] (3) Color calibration

[0105] Next, color calibration is described in specific terms.

[0106] In a printing apparatus having a plurality of print heads and a printing apparatus having a plurality of nozzle arrays such as the print head 9 used in the present embodiment, a printed image may not reproduce a desired tone due to differences in ejection characteristics between the individual print heads or the individual nozzle arrays. This is because the print heads or nozzle arrays have different ejection characteristics from the beginning or after the lapse of time, and the different ejection characteristics result in different density values ​​on the printed image.

[0107] The color shift correction process (color calibration) is a technique for coping with color tone differences due to differences in ejection characteristics between print heads or nozzle arrays.

[0108] Specifically, an adjustment pattern including a measurement color patch is printed on a printing medium, and the adjustment pattern is measured to obtain information related to the color of an image printed by a print head. Then, a color correction parameter is generated based on the obtained information so that an image with a desired color tone can be printed. The image data is corrected using the color correction parameter so that the image data can be printed with a desired color tone.

[0109] Fig. 10A A flowchart showing a color measurement process performed when color calibration is performed using white print media in this embodiment.

[0110] In S1001 , the CPU 102 executes a light intensity adjustment process of the optical sensor 200 using the paper white portion of the print medium.

[0111] In S1002 , the CPU 102 executes a printing process using the image printing unit to print the adjustment pattern 400 on a printing medium.

[0112] refer to Fig.11 The configuration of the adjustment pattern 400 used for the color correction parameter generation process is described below. The adjustment pattern 400 printed in the above S1002 is formed of blocks of five colors (i.e., blocks 401 of K ink, blocks 402 of C ink, blocks 403 of M ink, blocks 404 of Y ink, and blocks 405 of W ink), and each color further includes blocks of 16 chromaticities.

[0113] Immediately after printing the adjustment pattern 400, the adjustment pattern 400 has not yet been fixed on the printing medium. Therefore, in S1003, the CPU 102 feeds the printing medium to bring the adjustment pattern 400 to the image fixing unit.

[0114] In S1004 , the CPU 102 executes fixing processing using the image fixing unit to fix the adjustment pattern 400 .

[0115] In S1005, the CPU 102 reversely feeds the print medium to bring the adjustment pattern 400 to the image printing unit. Note that reversely feeding the print medium means conveying the print medium in the reverse direction. The reverse direction is the direction from downstream to upstream in the conveying direction, i.e., the -Y direction (see Figure 1 wait).

[0116] In S1006 , the CPU 102 executes a reading process using the optical sensor 200 to read the adjustment pattern 400 , and measures the density of each patch included in the adjustment pattern 400 .

[0117] Note that, since the optical sensor 200 is provided and fixed to the carriage 22 in the present embodiment, the print medium needs to be fed in reverse in S1005 to bring the adjustment pattern 400 to the image printing area where the image printing unit can print. However, the installation position of the optical sensor is not limited to the carriage 22, and in the case where the optical sensor is provided at a different position, the print medium is fed to bring the adjustment pattern to the position where the optical sensor is located.

[0118] In S1007, the CPU 102 stores the measurement result (ie, the density value of the patch) into the RAM 106 of the control unit 100, and Fig. 10A The color measurement process in is completed.

[0119] Fig. 10B is shown for Fig. 10A , correcting input image data using the color correction parameters thus generated, and printing an image based on the input image data thus corrected.

[0120] In S1011, CPU 102 reads the data from RAM 106 by Fig. 10AThe concentration values ​​obtained from the measurement process in .

[0121] In S1012 , based on the density value obtained in S1011 , the CPU 102 generates color correction parameters for correcting the input image data.

[0122] In S1013, the CPU 102 corrects the input image data by applying the color correction parameters generated in S1012. Through this step, the input image data can be corrected so that a reference color having a target color value can be output.

[0123] In S1014, the CPU 102 executes a print process based on the image data corrected in S1013.

[0124] As described above, color correction parameters are applied as needed, so that a stable image without color fluctuation can be always output.

[0125] Note that, as described in the various adjustments (1) to (3) above, the light intensity of the optical sensor must be adjusted before the adjustment is made. Although white plate calibration is generally performed to adjust the light intensity of the optical sensor, the printing device A performs the light intensity adjustment by using a printing medium instead of a white plate. For this reason, in the case where the printing medium is not white, the light intensity adjustment cannot be properly performed. For example, in the case of a transparent printing medium with low optical reflectivity, the projected light passes through the printing medium and does not return to the light receiving unit. Thus, the light intensity adjustment cannot be properly performed. It is also impossible to properly perform the light intensity adjustment using a colored printing medium because light in a certain wavelength range is absorbed and does not return to the light receiving unit.

[0126] In addition, because the adjustment pattern is affected by the color of the substrate (printing medium), the color of the substrate needs to be uniformly white or black. In the case of a transparent printing medium, the adjustment pattern is affected by the color of the platen 4 of the printing device A (which is the color of the substrate of the adjustment pattern). The platen 4 has an uneven shape and therefore has a shadow due to the unevenness. In addition, the platen 4 does not provide a background color suitable for measurement. Therefore, it is impossible to obtain an appropriate measurement value based on the adjustment pattern. Similarly, in the case of a colored printing medium, due to the color gradation of the printing medium, it is impossible to obtain an appropriate measurement value based on the adjustment pattern.

[0127] However, by using the characteristic configuration of the present embodiment described below or specifically by printing an adjustment pattern on a fixed base image, the above-mentioned adjustments (1) to (3) can be performed even with a transparent or colored print medium.

[0128] <Feature Configuration>

[0129] The characteristic of this embodiment is that after the image printing unit finishes printing the first image using the first ink, the image fixing unit fixes the first image, and then the image printing unit prints the adjustment pattern on the first image again.

[0130] The adjustment pattern is a pattern used for adjustment of a print head or a printing device. After the adjustment pattern is printed, the printed adjustment pattern is read using an optical sensor. Reading the adjustment pattern printed on the fixed first image enables accurate measurement values ​​to be obtained regardless of the color of the printing medium, its reflectivity to the optical sensor, or the color of the second ink used to print the adjustment pattern.

[0131] When the adjustment pattern is printed on the first image used as a substrate using the above-mentioned low-permeability printing medium and the first image is not sufficiently fixed, the color of the first ink used to print the first image and the color of the second ink used to print the adjustment pattern are mixed together. The mixture of the color of the first ink and the color of the second ink prevents the second ink from being printed at an appropriate position or printed in a dot shape.

[0132] FIG. 12A to FIG. 12D : is a schematic diagram showing a second ink droplet printed on a first ink layer that is fully fixed (forming a first image) as a cross-sectional view. The first ink droplet lands on the printing medium P ( Fig. 12A ), and the first ink droplet on the print medium P is fixed to become a uniform layer Q ( Fig. 12B The second ink droplet ( Fig. 12C ) can be uniformly diffused at the desired location ( Fig.12D ).

[0133] on the other hand, FIG. 13A to FIG. 13C is a schematic diagram showing a second ink droplet printed on the first ink layer (forming the first image) which is not sufficiently fixed as a cross-sectional view. By dropping the first ink droplet on the printing medium P ( Fig.13A ) Then the second ink droplet is dropped on the first ink layer R which is not fully fixed ( Fig. 13B ), and obtain Fig. 13C Status shown. Fig. 13C This shows how the second ink droplet is moved or buried from the desired printing position as a result of landing on the insufficiently fixed first ink layer R. In the case where the second ink droplet is thus moved or buried from the desired printing position, the adjustment pattern cannot satisfy the accuracy required for adjustment of the print head or printing device, and thus the above-mentioned adjustments (1) to (3) cannot be performed with high accuracy.

[0134] Therefore, in order to perform appropriate adjustments, such as FIG. 12A to FIG. 12D As shown, it is necessary to print the adjustment pattern after the first image used as the base is sufficiently fixed.

[0135] One of the characteristic configurations of the present embodiment, or specifically a method for performing registration adjustment of a print head or conveyance adjustment of a printing apparatus by using a transparent or colored print medium, is described below.

[0136] In this embodiment, first, an image (first image) serving as a base is printed on a print medium P using W ink, the printed image is sufficiently fixed, and then an adjustment pattern is printed on the base using color inks (i.e., K, C, M, and Y inks). This enables position adjustment of the K, C, M, and Y nozzles of the print head even when the print medium P used is transparent or colored.

[0137] Various print media that can be used in the printing device A are pre-classified into a first print media group and a second print media group based on their optical reflectance and color gradation. White print media are classified into the first print media group, and transparent print media and colored print media are classified into the second print media group. The printing device A holds information related to these print media groups (print media group information). The technical features of the present embodiment are realized using this print media group information (see Fig.14 ).

[0138] Fig.14 1 is a flowchart of the processing performed when executing the above-mentioned (1) registration adjustment or (2) conveying adjustment. Once the CPU 102 is instructed to start the execution of (1) registration adjustment or (2) conveying adjustment of the print head, Fig.14 in the processing.

[0139] First, in S1401, the CPU 102 determines whether the print medium P to be printed belongs to the first print medium group. If the judgment result of this step is "yes", the processing proceeds to S1402. On the other hand, if the judgment result of this step is "no" (that is, if the print medium P belongs to the second print medium group), the processing proceeds to S1403. Although the judgment of this step is performed using the print medium group information, the present disclosure is not limited to this mode. In another example, the judgment of this step can be performed using information included in the print job obtained by the printing device, which indicates the group to which the print medium P to be printed belongs: the first print medium group or the second print medium group. Alternatively, the user himself can select whether the print medium P belongs to the first print medium group or the second print medium group.

[0140] In S1402, the CPU 102 executes adjustment processing, or specifically, Figure 8 The processing in S801 to S807 shown in the flowchart.

[0141] In S1403, the CPU 102 prints a base of an adjustment pattern, and then executes adjustment processing.

[0142] Fig.15 A detailed flowchart of S1403 is shown.

[0143] First, in S1501, the CPU 102 executes a print process using a multi-pass printing method to use Figure 3 The nozzles in the entire area of ​​the nozzle array 33W for ejecting W ink are shown to print a base image (first image) using W ink. Note that the first image printed in this embodiment is a 200% solid image of A4 size (where one dot is 100% at 1200 dpi).

[0144] In S1502, the CPU 102 feeds the print medium to bring the first image that has been printed (S1501) to the image fixing unit.

[0145] In S1503, the CPU 102 fully fixes the first image by exposing it to hot air at 80° C. For “fully fixing”, in the present embodiment, the first image is exposed to hot air at 80° C. for a predetermined period of time set in advance.

[0146] In S1504, the CPU 102 reversely feeds the printing medium to bring the first image fixed in S1503 to the image printing unit.

[0147] In S1505, the CPU 102 executes light intensity adjustment processing of the optical sensor using the first image printed with the W ink.

[0148] In S1506, the CPU 102 executes adjustment processing, or specifically, Figure 8 The processing in S802 to S807 shown in the flowchart.

[0149] The processing in S1501 to S1505 described above is a characteristic configuration of the present embodiment. This processing enables appropriate adjustment required when performing (1) registration adjustment or (2) conveyance adjustment even when using a transparent or colored low-permeability print medium.

[0150] As described above, in this embodiment, the first image used as a base is printed, and then the first image is fixed by the image fixing unit. Thereafter, the print medium is fed in reverse to bring the first image to the image printing area where the image printing unit can print, and the adjustment pattern is printed above the first image.

[0151] In such a mode of the present embodiment in which the print medium is reversely fed after the printed first image is fixed by the image fixing unit, the print start position may be different between the first image and the adjustment pattern due to the conveying accuracy during reverse feeding. In this regard, in the present embodiment, the first image is printed over the entire area to serve as a background for the adjustment pattern, so some differences in the print start position between the first image and the adjustment pattern are not a problem. From the above viewpoint, in the actual image printing mode for printing a given image, unlike the adjustment pattern printing mode for printing an adjustment pattern, the second image is printed on the first image without the fixing unit fixing the printed first image.

[0152] The above-mentioned multi-pass printing method using different nozzle groups for each ink is a method for making the deviation of the printing start position between the first image used as the base and the image above the first image less. In such a multi-pass printing method, after printing the base image, a given image is printed on the base image without fixing the base image by an image fixing unit.

[0153] As a flowchart of a multi-pass printing method using different nozzle groups for each ink, refer to Fig.16 A case where printing of an image of W ink and printing of an image of K ink are completed by six scans for a predetermined area will be described.

[0154] First, in S1601, an image is printed using W ink through the first to third scans. The print data of W ink is divided so that the printing of the image can be completed through the first to third scans, and the third scan completes the printing of the image using W ink.

[0155] Next, in S1602, an image is printed using K ink through the fourth to sixth scans. The print data of K ink is divided so that the printing of the image can be completed through the fourth to sixth scans. In the fourth to sixth scans, the image of K ink is printed on the image of W ink that has been printed through the first to third scans. The sixth scan completes the printing of the image of K ink. This completes the printing of the image of K ink on the image of W ink on the predetermined area.

[0156] In S1603, the CPU 102 feeds the print medium to bring the print image to the image fixing unit.

[0157] In S1604, using the image fixing unit, the CPU 102 performs fixing processing to fix the image onto the print medium.

[0158] Fig.16The printing method shown does not need to reversely feed the print medium before printing the image on the base image. Thus, there is less misalignment between the base image and the image printed on the base image, which makes it possible to obtain a high-quality image.

[0159] However, with the above-mentioned multi-pass printing method using different nozzle groups for each ink color, the image fixing unit cannot fix only the base image. Therefore, there is a problem of color mixing of the ink (first ink) used to print the base image and the ink (second ink) used to print the image above the base. Therefore, in order to avoid color mixing of the first ink and the second ink, it is necessary to slow down printing and scanning to dry the first ink to a certain extent during printing and scanning.

[0160] For this reason, the multi-pass printing method is generally adopted in the case where a base image is required and the image is also printed with high quality rather than with a short printing time.

[0161] As described above, in the printing of the adjustment pattern, it is not necessary to positionally match the area of ​​the base image and the area of ​​the image of the adjustment pattern with high accuracy. Therefore, the printing method described in this embodiment is adopted to enable shortening of the adjustment time.

[0162] In this way, in the present embodiment, after the base image is printed on the print medium P using the W ink and sufficiently fixed, the adjustment pattern is printed on the base using the K, C, M, and Y inks. Thereafter, the printed adjustment pattern is read. This configuration makes it possible to measure the density difference depending on the offset amount between the reference pattern and the offset pattern of the K, C, M, or Y ink, and thus makes it possible to perform registration adjustment and conveyance adjustment of the K, C, M, and Y nozzles of the print head.

[0163] [Second embodiment]

[0164] This embodiment describes a method for color calibration using a transparent or colored print medium. The characteristic of this embodiment is that the adjustment pattern is fixed at a timing different from that in the first embodiment.

[0165] As described in (1) registration adjustment and (2) conveyance adjustment in the first embodiment, the timing of fixing the adjustment pattern in color calibration is different from the timing of fixing in registration adjustment or conveyance adjustment. Specifically, in registration adjustment or conveyance adjustment, after the adjustment pattern is read in S803, the adjustment pattern is finally fixed in S807 (see FIG. Figure 8 ). In contrast, in color calibration, after the adjustment pattern is fixed in S1004, the adjustment pattern is read in S1006 (see Fig. 10A ).

[0166] When color calibration is performed, it is important to stabilize the color of the adjustment pattern, so it is necessary to fully dry the ink used to print the adjustment pattern. To this end, the adjustment pattern is fixed at an image fixing unit before reading the adjustment pattern.

[0167] On the contrary, Fig. 7A , Figure 7B , Fig. 9A and Fig. 9B As shown in FIG. 1 , the registration adjustment or the conveyance adjustment measures the density of the positional offset between the reference pattern and the offset pattern depending on the adjustment pattern, so there is no need to stabilize the color of the adjustment pattern. Therefore, in order to shorten the adjustment time, the adjustment pattern is fixed after reading the adjustment pattern. In the case where the adjustment pattern is fixed after reading the adjustment pattern, the adjustment time can be shortened because there is no need to perform Fig. 10A S1005 (reverse feeding step) is shown.

[0168] In this embodiment, first, an image (first image) serving as a base is printed on a transparent or colored printing medium P using W ink, and after the image of W ink is sufficiently fixed, K, C, M, and Y inks are used to fix the image of W ink. Fig.11 The above adjustment pattern shown is printed on the substrate. In this way, even when using a transparent or colored print medium, the K nozzle, C nozzle, M nozzle and Y nozzle of the print head can be color calibrated.

[0169] Various print media that can be used in the printing device A are pre-classified into a first print media group and a second print media group based on their optical reflectivity and color gradation. Specifically, white print media are classified into the first print media group, and transparent print media and colored print media are classified into the second print media group. The printing device A maintains information related to these print media groups (print media group information). The technical features of the present embodiment are realized using this print media group information.

[0170] Fig.14 2 is a flowchart of the processing performed in the present embodiment when color calibration is performed. This processing is similar to the flowchart of the processing performed in the first embodiment when registration adjustment and conveyance adjustment are performed.

[0171] First, in S1401, the CPU 102 determines whether the print medium P to be printed belongs to the first print medium group. If the determination result of this step is "Yes", the process proceeds to S1402. On the other hand, if the determination result of this step is "No", the process proceeds to S1403.

[0172] In S1402, the CPU 102 executes adjustment processing, or specifically, Fig. 10AThe processing in S1001 to S1007 shown in the flowchart.

[0173] In S1403, the CPU 102 prints a base of an adjustment pattern, and then executes adjustment processing.

[0174] Fig.15 A detailed flowchart of S1403 is shown. Fig.15 1 is a flowchart described in the first embodiment, and the present embodiment is described using the same flowchart.

[0175] First, in S1501, the CPU 102 executes a print process using a multi-pass printing method to obtain a print result by using Figure 3 The nozzles in the entire area of ​​the nozzle array 33W for ejecting W ink are shown to print a base image (first image) using W ink. Note that the first image printed in this example is a 200% solid image of A4 size (where one dot is 100% at 1200 dpi).

[0176] In S1502, the CPU 102 feeds the print medium to bring the first image that has been printed (S1501) to the image fixing unit.

[0177] In S1503, the CPU 102 fully fixes the first image by exposing it to hot air at 80° C. For “fully fixing”, in the present embodiment, the first image is exposed to hot air at 80° C. for a predetermined period of time set in advance.

[0178] In S1504, the CPU 102 reversely feeds the printing medium to bring the first image fixed in S1503 to the image printing unit.

[0179] In S1505, the CPU 102 executes light intensity adjustment processing of the optical sensor using the first image printed with the W ink.

[0180] In S1506, the CPU 102 executes adjustment processing, or specifically, Fig. 10A The processing in S1002 to S1007 shown in the flowchart.

[0181] The processing in S1501 to S1505 described above is a characteristic configuration of the present embodiment. This processing makes it possible to perform appropriate adjustments required when performing color calibration even when using a transparent or colored low-permeability print medium.

[0182] Note that in the case where the color of the print medium or the first image used as the substrate is white, the measurement value for the block printed with W ink cannot be obtained. In view of this, in the present embodiment, the W nozzle for ejecting W ink is not adjusted. Although the adjustment pattern 400 used in the present embodiment includes a block 405 of W ink, the block 405 of the adjustment pattern 400 is not read in S1006. Alternatively, the adjustment pattern may be printed without the block 405 and include only the blocks 401 to 404.

[0183] In the present embodiment described so far, as in the first embodiment, after the first image used as a base is printed and fixed by the image fixing unit, the print medium is fed in reverse to bring the first image to the image printing unit, and the adjustment pattern is printed above the first image.

[0184] In a mode in which the print medium is fed in reverse to bring the first image to the image printing area after the printed first image is fixed by the image fixing unit, there is a problem that the printing start position between the first image and the adjustment pattern is different due to the conveying accuracy during the reverse feeding. In this regard, the first image used as a base is printed on the entire area as the background of the adjustment pattern, so some difference in the printing start position between the first image and the adjustment pattern is not a problem. Therefore, as described in the first embodiment, the first image can be fixed at the image fixing unit, which can make the adjustment time shorter.

[0185] On the other hand, as described in the first embodiment, in the printing of a given image, a method in which the printing medium is reversely fed after the first image is fixed by the image fixing unit and the second image is printed on the first image by the image printing unit is not preferable from the viewpoint of image quality. Thus, the given image is printed using the method described in the first embodiment.

[0186] In this way, in the present embodiment, after the image used as the base is printed on the print medium P using the W ink and the image is sufficiently fixed, the adjustment pattern is printed on the base using the K, C, M, and Y inks. Thereafter, the printed adjustment pattern is fixed and read. This configuration makes it possible to measure the density difference depending on the difference in the exposure amount of the W ink base from the amount of K, C, M, and Y inks, and thus makes it possible to perform color calibration of the K, C, M, and Y nozzles of the print head.

[0187] [Third embodiment]

[0188] This embodiment describes a method for performing color calibration of W ink (also referred to as white ink) ejected from a W nozzle. It is not possible to measure the density difference between W ink patches printed on a white print medium because the ink and the print medium are the same color. In addition, it is also not possible to measure the density difference between W ink patches printed on a transparent print medium because the measurement is affected by the color of the platen 4.

[0189] Thus, in this embodiment, an image (first image) serving as a base is printed on a print medium P using K ink (also referred to as black ink), the K ink image is sufficiently fixed, and then an adjustment pattern is printed on the base using W ink. This makes it possible to measure a density difference depending on the difference in exposure amount of the K ink base according to the amount of W ink, and to perform color calibration of the W ink. Note that the ink used for printing the base is preferably K ink having high light absorption, but is not limited to K ink. Other inks (such as C ink, etc.) may be used as long as a desired density difference can be measured.

[0190] Fig.17 2 is a flowchart of the color calibration of W ink in this embodiment. In the color calibration of W ink, regardless of the type of the printing medium P, the base of the adjustment pattern must be printed.

[0191] First, in S1701, the CPU 102 uses the multi-pass printing method, using Figure 3 The base image (first image) is printed using the K ink using the nozzles in the entire area of ​​the nozzle array 33K shown for ejecting the K ink. At the same time, in order to perform the light intensity adjustment, the CPU 102 uses the nozzles in the entire area of ​​the nozzle array 33W for ejecting the W ink to print the light intensity adjustment image, which is aligned with the first image in the main scanning direction. Note that the first image and the light intensity adjustment image printed in this example are 200% solid images of A4 size (where one dot is 100% at 1200 dpi).

[0192] In S1702, the CPU 102 feeds the print medium to bring the first image and the light-intensity-adjusted image that have been printed (S1701) to the image fixing unit.

[0193] In S1703, the CPU 102 fully fixes the first image and the light intensity adjusted image by exposing them to hot air at 80° C. For “fully fixing”, in the present embodiment, the first image and the light intensity adjusted image are exposed to hot air at 80° C. for a predetermined period of time set in advance.

[0194] In S1704, the CPU 102 reversely feeds the printing medium to bring the first image and the light-intensity-adjusted image fixed in S1703 to the image printing unit.

[0195] In S1705, the CPU 102 executes the light intensity adjustment process of the optical sensor using the light intensity adjustment image printed with the W ink.

[0196] In S1706, the CPU 102 executes adjustment processing, or specifically, Fig. 10A The processing in S1002 to S1007 shown in the flowchart.

[0197] The processing in S1701 to S1705 described above is a characteristic configuration of the present embodiment. This processing enables appropriate adjustment of the color calibration for the W ink.

[0198] Note that although the adjustment pattern 400 used in the present embodiment includes patches 401 to 404 other than W ink, the patches 401 to 404 in the adjustment pattern 400 are not read in S1006. Alternatively, the printed adjustment pattern may include only the patches 405 of white ink.

[0199] In addition, although the light intensity adjustment image printed with W ink is used to adjust the light intensity of the optical sensor in this embodiment, other methods can be used. For example, in the case where a white board is provided in the printing device, the white board can be used. In addition, in the case where the printing medium is white, the printing medium can be used. In this case, it is not necessary to print the light intensity adjustment image.

[0200] In this way, in the present embodiment, an image used as a base is printed on the print medium P using K ink, the K ink image is sufficiently fixed, and then an adjustment pattern is printed on the base using W ink. Thereafter, the printed adjustment pattern is fixed and read. This configuration makes it possible to measure a density difference depending on an exposure difference of the K ink base according to the amount of W ink.

[0201] [Other embodiments]

[0202] In the above-described embodiment, the printing device A maintains in advance the printing medium group information indicating that the printing media are classified into groups (a first printing medium group and a second printing medium group), and uses the printing medium group information to determine whether to print the substrate of the adjustment pattern. However, the present disclosure is not limited to this mode, and the printing device A does not necessarily have to maintain the printing medium group information. For example, a user can select the printing medium group to which the printing medium to be printed belongs. In addition, for example, the reflectivity of the printing medium can be measured using an optical sensor installed in the printing device, and the printing medium group can be automatically selected based on the measured reflectivity. In an example of automatic selection based on reflectivity, when the reflectivity threshold is set to 0.5, the processing for the first printing medium group is selected when the measured reflectivity is equal to or greater than the threshold, and the processing for the second printing medium group is selected when the measured reflectivity is less than the threshold. In addition, for example, the color gradation of the printing medium can be measured using an optical sensor installed in the printing device, and the printing medium group can be automatically selected based on the measured color gradation.

[0203] Furthermore, although the multi-pass printing method is used as a method for printing the first image used as a substrate in the above-described embodiment, the printing method is not limited to the multi-pass method. For example, the printing of the image used as a substrate may be completed by one scan, depending on the ink or adjustment pattern, etc. The printing of the image by fewer scans can make the printing time of the image shorter, and thus the adjustment time can be shortened.

[0204] Furthermore, although the first image used as the basis of the adjustment pattern in the above-described embodiment is a 200% solid image (where one dot is 100% at 1200 dpi), the first image is not limited to a 200% solid image.

[0205] According to the adjustment pattern, even in the case where the print coverage (%) of the first image is small, the adjustment value can be obtained. Thus, the print coverage (%) can be appropriately set. For example, according to the adjustment pattern, the print coverage (%) of the first image used as the base of the given image can be smaller than the print coverage (%) of the first image used as the base of the adjustment pattern. The lower print coverage (%) of the first image as the base of the adjustment pattern shortens the fixing time of the first image and thus shortens the adjustment time. Note that the print coverage means the amount of ink applied per unit area.

[0206] In addition, although the first image used as the base of the adjustment pattern in the above-mentioned embodiment is of A4 size, the size of the first image is not limited to A4 size. The size of the first image as the base can be appropriately changed according to the size of the adjustment pattern, as long as the first image is large enough to serve as the background of the adjustment pattern. In the case where the adjustment pattern is small, the first image can also be small. The smaller the printed first image is, the shorter the printing time of the first image and the fixing time of the first image are, and thus the adjustment time can be shortened.

[0207] In addition, although the optical sensor 200 obtains the density value as the measurement value of the adjustment pattern in various adjustments (i.e., registration adjustment, conveying adjustment, and color calibration), the measurement value is not limited to the density value. For example, a colorimeter capable of obtaining color values ​​may be used to obtain CMYK values, L*a*b values, XYZ values, or RGB values ​​of the pattern.

[0208] Furthermore, in the case of performing light intensity adjustment using a white plate used in general light intensity adjustment, appropriate measurement values ​​cannot be obtained due to the influence of the color of the base of the above-mentioned adjustment pattern; therefore, the characteristic configuration of the present disclosure can be applied to enable appropriate adjustment.

[0209] Other embodiments

[0210] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0211] The present disclosure can automatically make various adjustments to a printing device capable of printing using white ink.

[0212] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A printing device, comprising: A feeding unit, used for feeding a printing medium; a printing unit including a first printing element array among a plurality of printing elements for applying a first ink onto the printing medium and a second printing element array among a plurality of printing elements for applying a second ink onto the printing medium; as well as a fixing unit which is located downstream of the printing unit in a feeding direction and which fixes the image printed on the printing medium, wherein the printing unit prints a first image on the printing medium by applying the first ink, The feeding unit feeds the printing medium on which the first image is printed to the fixing unit from upstream to downstream in the feeding direction, The fixing unit fixes the first image. The feeding unit reversely feeds the printing medium on which the first image has been fixed to the printing unit from downstream to upstream in the feeding direction, and The printing unit prints a second image on the first image by applying the second ink.

2. The printing device according to claim 1, wherein: The second image is at least one of a registration adjustment pattern, a feed adjustment pattern, and a color calibration pattern.

3. The printing device according to claim 1, wherein: The first ink is an ink for a substrate.

4. The printing device according to claim 1, wherein: The first ink contains a white colorant. 5 . The printing apparatus according to claim 1 , further comprising a reading unit configured to read the second image.

6. The printing device according to claim 5, wherein: The reading unit is integrated with the printing unit.

7. The printing device according to claim 5, wherein: In a case where the second image is a registration adjustment pattern or a feed adjustment pattern, after the reading unit reads the second image, the feeding unit feeds the printing medium to the fixing unit, and the second image is fixed.

8. The printing device according to claim 5, wherein: In a case where the second image is a color calibration pattern, the feeding unit feeds the printing medium on which the second image is printed to the fixing unit, the fixing unit fixes the second image, and the reading unit reads the fixed second image. 9 . The printing apparatus according to claim 5 , further comprising a determination unit configured to determine an adjustment value based on a reading result of the second image.

10. The printing device according to claim 1, wherein The printing medium is a transparent printing medium or a colored printing medium. 11 . The printing apparatus according to claim 1 , further comprising an obtaining unit that obtains information indicating a type of the printing medium.

12. The printing device according to claim 11, wherein The obtaining unit obtains the information based on information set by a user.

13. The printing device according to claim 11, wherein The obtaining unit obtains the information based on information included in the print job.

14. The printing device according to claim 1, wherein: In a case where the printing medium is a white printing medium, the printing unit prints the second image without printing the first image.

15. The printing device according to claim 1, wherein In the case of printing the user image, the fixing unit does not fix the third image between printing of the third image using the first ink by the printing unit and printing of the fourth image using the second ink by the printing unit.

16. The printing device according to claim 15, wherein: The feeding unit feeds the printing medium on which the third image and the fourth image have been printed by the printing unit to the fixing unit, and The fixing unit fixes the third image and the fourth image printed on the printing medium.

17. The printing device according to claim 1, wherein: The first image is a solid image formed by the first ink and having a uniform density.

18. A control method for a printing device, the printing device comprising: A feeding unit, used for feeding a printing medium; a printing unit including a first printing element array among a plurality of printing elements for applying a first ink onto the printing medium and a second printing element array among a plurality of printing elements for applying a second ink onto the printing medium; a fixing unit located downstream of the printing unit in a feeding direction and fixing an image printed on the printing medium; as well as Control unit, Wherein, the control method comprises: Printing a first image on the printing medium by applying the first ink using the printing unit, by the control unit; By the control unit, the printing medium on which the first image is printed is fed to the fixing unit from upstream to downstream in the feeding direction using the feeding unit; Fixing the first image by the control unit using the fixing unit; By the control unit, reversely feeding the printing medium on which the first image has been fixed to the printing unit from downstream to upstream in the feeding direction using the feeding unit; and The second image is printed on the first image by applying the second ink using the printing unit through the control unit.

19. A non-transitory computer-readable storage medium storing a program for causing a computer to execute a control method for a printing device, the printing device having: A feeding unit, used for feeding a printing medium; a printing unit including a first printing element array among a plurality of printing elements for applying a first ink onto the printing medium and a second printing element array among a plurality of printing elements for applying a second ink onto the printing medium; a fixing unit located downstream of the printing unit in a feeding direction and fixing an image printed on the printing medium; as well as Control unit, Wherein, the control method comprises: Printing a first image on the printing medium by applying the first ink using the printing unit, by the control unit; By the control unit, the printing medium on which the first image is printed is fed to the fixing unit from upstream to downstream in the feeding direction using the feeding unit; Fixing the first image by the control unit using the fixing unit; By the control unit, reversely feeding the printing medium on which the first image has been fixed to the printing unit from downstream to upstream in the feeding direction using the feeding unit; and The second image is printed on the first image by applying the second ink using the printing unit through the control unit.

20. A computer program product, comprising a program for causing a computer to execute a control method for a printing device, the printing device having: A feeding unit, used for feeding a printing medium; a printing unit including a first printing element array among a plurality of printing elements for applying a first ink onto the printing medium and a second printing element array among a plurality of printing elements for applying a second ink onto the printing medium; a fixing unit located downstream of the printing unit in a feeding direction and fixing an image printed on the printing medium; as well as Control unit, Wherein, the control method comprises: Printing a first image on the printing medium by applying the first ink using the printing unit, by the control unit; By the control unit, the printing medium on which the first image is printed is fed to the fixing unit from upstream to downstream in the feeding direction using the feeding unit; Fixing the first image by the control unit using the fixing unit; By the control unit, reversely feeding the printing medium on which the first image has been fixed to the printing unit from downstream to upstream in the feeding direction using the feeding unit; and The second image is printed on the first image by applying the second ink using the printing unit through the control unit.

Images