Image processing apparatus, image processing method, storage medium, and computer program product

Abstract

The invention relates to an image processing apparatus, an image processing method, a storage medium, and a computer program product. A read image is obtained. A read image is obtained by reading a pattern for a colored material and a colorless material formed on a print medium by a printhead. An adjustment value for adjusting a misalignment between print positions of a printhead is determined by generating an inverted image as a read image whose density is inverted based on at least one of a result of a recognition process on a pattern in the read image and print medium information for indicating a type of print medium.

Description

Technical Field

[0001] The present disclosure relates to adjustment of a printing position of a printing material. Background Art

[0002] An inkjet printing device is known that includes a so-called full-line print head having a printing width equivalent to the width of a print medium. An inkjet printing device having such a print head is capable of printing an image on substantially the entire surface of a print medium by moving the print head once relative to the print medium. A printing device having a full-line print head may have errors in the attachment position of (one or more than one) print heads and the attachment positions of the plurality of print heads relative to each other. These errors may lead to a deterioration in the print quality by causing a misalignment of the ink landing position (attachment position) on the print medium. Hereinafter, the process of correcting such a misalignment of the ink landing position will be referred to as "print position adjustment".

[0003] As a printing position adjustment method, Japanese Patent Laid-Open No. 2014-091304 discloses a method of performing printing position adjustment based on an analysis result obtained by analyzing a result of reading a pattern formed on a printing medium. Summary of the invention

[0004] According to one aspect of the present disclosure, an image processing device includes: an obtaining unit for obtaining a read image obtained by reading patterns for colored materials and colorless materials formed by a print head on a print medium; and a determining unit for determining an adjustment value for adjusting misalignment between printing positions of the print head by generating an inverted image of the read image as a concentration inverted image based on a result of a recognition process of the pattern in the read image and at least one of print medium information indicating the type of the print medium.

[0005] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic cross-sectional view of a printing device;

[0007] Figure 2 It is an enlarged stereogram of the printing unit;

[0008] Figure 3 is a diagram showing a print head lifting mechanism;

[0009] Figure 4 is a diagram showing a test pattern for correcting print head misalignment;

[0010] Figure 5A and Figure 5B is a diagram showing a detailed layout of a pattern for pattern matching;

[0011] Figure 6 It is an explanatory diagram of the correspondence between the printing chip, the ejection nozzle and the pattern;

[0012] Figure 7 is an explanatory diagram of a pattern for calculating the amount of misalignment between colors;

[0013] Figure 8 is an explanatory diagram of a method for calculating the misalignment amount between nozzle arrays;

[0014] Fig. 9 It is an explanatory diagram of a method for calculating the misalignment amount between chips and a method for calculating the tilt amount of a head;

[0015] Fig.10 is an explanatory diagram of a method for calculating the misalignment amount between print heads;

[0016] Fig.11 is an illustration of a marker detection process;

[0017] Fig. 12A and Fig. 12B is a flowchart showing the flow of a print position adjustment process;

[0018] FIG. 13A to FIG. 13C is a diagram showing a pattern for calculating the amount of misalignment between a clear ink print head and a color ink print head;

[0019] FIG. 14A to FIG. 14D is a flowchart showing the flow of a printing position adjustment process; and

[0020] Fig.15 : is a diagram showing a pattern for calculating the amount of misalignment between the print heads of paper and film. DETAILED DESCRIPTION

[0021] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that the components described in the following embodiments are merely examples, and without departing from the gist of the present disclosure, the device configuration and various conditions to which the present disclosure is applicable may be appropriately modified or changed, and are not limited to the following embodiments. For example, the size, material, shape, and relative positions of the components described in the following embodiments, etc. may be appropriately changed based on the device configuration and various conditions to which the present disclosure is applicable, and unless otherwise specified, the present disclosure is not limited to the following embodiments.

[0022] Depending on the type of printing medium, the tone of the background color is sometimes reversed in the pattern of the colorless material used to fix the colored material. As a result, an analysis error may occur for the read pattern. Although it has been found that this phenomenon occurs due to the permeability characteristics of the printing medium to the colorless material used to print the pattern, it is difficult for the user to identify and set all these permeability characteristics.

[0023] An object of the present disclosure is to provide a technology for accurately adjusting misalignment between printing positions of a print head regardless of the permeability characteristics of a print medium to a colorless material for fixing a color material.

[0024] [Example 1]

[0025] Figure 1 1 is a schematic cross-sectional view showing the internal configuration of a high-speed line printer as a printing device 1 according to Embodiment 1, wherein the high-speed line printer uses a continuous long sheet rolled into a roll as a printing medium. Figure 1 , the direction above the printing device 1 is defined as "upward", the direction from right to left is defined as "longitudinal direction", and the lateral direction of the long sheet perpendicular to the sheet conveying direction (from the near side to the far side) is defined as "sheet width direction".

[0026] The printing device 1 includes an unwinding roller unit 2, a first tension adjustment unit 3, a first main conveying unit 4, a meander correction unit 5, a conveying detection unit 6, a printing unit 7, a fixing unit 8, a conveying tension detection unit 9, a printing image position detection unit 10, a scanner unit 11, a second main conveying unit 12, a second tension adjustment unit 13, and a winding roller unit 14. The printing device 1 also includes a maintenance unit 15. The fixing unit 8 includes a drying unit 40 and a cooling unit 50. The sheet S is moved along Figure 1 The material is transported along the transport path shown by the solid line and processed at each unit.

[0027] The printing device 1 sequentially performs the first printing stage and the second printing stage along the conveying path of the sheet S from the upstream side in the conveying direction of the sheet S. At the first printing stage, the image is printed and fixed to the sheet S by the first printing unit 7a, the first drying unit 40a, and the first cooling unit 50a. At the second printing stage, the image is printed and fixed to the sheet S that has passed the first printing step by the second printing unit 7b, the second drying unit 40b, and the second cooling unit 50b. Thus, the printing device 1 can continuously print images on the sheet S by passing the sheet S through the first printing stage and the second printing stage. The printing device 1 can also determine the printing stage to be selected alternatively based on the printing conditions. In this case, the image is printed on the sheet S only at the selected printing stage.

[0028] Incidentally, regarding the conveyance of the sheet S, the conveyance of the sheet S in the direction from the unwinding roller unit 2 to the winding roller unit 14 is defined as “forward conveyance”, and the conveyance of the sheet S in the opposite direction from the winding roller unit 14 to the unwinding roller unit 2 is defined as “reverse conveyance”.

[0029] The unwinding roller unit 2 holds and feeds the sheet. The unwinding roller unit 2 is configured to accommodate an unwinding roller, and feed the sheet S by pulling out the sheet S. Note that the number of rolls that can be accommodated is not limited to one, and the unwinding roller unit 2 may be configured to accommodate two rolls or three or more rolls, and feed the sheet S by pulling out the sheet S from one of the rolls. In addition, the rotation of the unwinding roller unit 2 is controlled solely by a drive motor (not shown), so that the unwinding roller unit 2 can rotate forward and reverse.

[0030] The first tension adjusting unit 3 is a unit for applying a constant sheet tension between the unwinding roller unit 2 and the first main conveying unit 4. The first tension adjusting unit 3 applies sheet tension using a tension applying unit not shown.

[0031] The first main conveying unit 4 feeds the sheet S along the conveying path to the units arranged in the following order. Specifically, the first main conveying unit 4 feeds the sheet S to the first meandering correction unit 5a, the first conveying detection unit 6a, the first printing unit 7a, the first fixing unit 8a, the conveying tension detection unit 9, the print image position detection unit 10, the second fixing unit 8b, and the scanner unit 11. The first fixing unit 8a includes a first drying unit 40a and a first cooling unit 50a. The second fixing unit 8b includes a second drying unit 40b and a second cooling unit 50b. The first main conveying unit 4 is rotated by driving a motor not shown while applying sheet tension between itself and the second main conveying unit 12, thereby conveying the sheet S under tension.

[0032] During the tension conveyance of the sheet S, the meander correction unit 5 corrects the meandering of the sheet S in the sheet width direction. In the present embodiment, the meander correction unit 5 has a first meander correction unit 5a provided upstream of the first printing stage on the conveying path, and a second meander correction unit 5b provided upstream of the second printing stage on the conveying path. The meander correction unit 5 includes a meander correction roller and a meander detection sensor (not shown) for detecting the meandering of the sheet S. The meander correction roller changes the inclination of the sheet S using a motor (not shown) based on the measurement result of the meander detection sensor to correct the meandering of the sheet S. At this time, the sheet S is wound around the meander correction roller. This enhances the meander correction function.

[0033] The conveyance detection unit 6 is a unit that detects the conveyance speed of the sheet S and the mark pre-printed on the sheet S in order to control the image formation timing of the printing unit 7. In the present embodiment, the conveyance detection unit 6 has a first conveyance detection unit 6a provided upstream of the first printing stage on the conveyance path, and a second conveyance detection unit 6b provided downstream of the first printing stage but upstream of the second printing stage on the conveyance path. The conveyance speed and the mark of the sheet S detected by the first conveyance detection unit 6a are used to control the image formation timing of the first printing unit 7a. The conveyance speed and the mark of the sheet S detected by the second conveyance detection unit 6b are used to control the image formation timing of the second printing unit 7b.

[0034] The image forming unit (printing unit) 7 includes a print head 22 of each ink color, which performs inkjet printing using each color plate from above the conveyed sheet S. The conveying path at the image forming unit (printing unit) 7 is formed by a guide roller 23 arranged in an arc shape convex upward. Here, a constant tension is applied to the sheet S so that a gap is left between the sheet S itself and the print head 22. The print heads 22 are arranged along the conveying direction. For example, the print heads 22 are each a full-line type print head in which nozzles for ejecting ink are arranged over a length equivalent to the width of the printing medium. In this embodiment, there are a total of two print heads at the first printing unit 7a: a print head for white (W) ink and a print head for reaction liquid. There are a total of eight print heads at the second printing unit 7b: print heads for four colors of black (K), yellow (Y), magenta (M) and cyan (C), and additionally a print head for reaction liquid and a print head for three spot colors. Each reaction liquid is a liquid containing a component for increasing the viscosity of (one or more than one) ink. Here, increasing the viscosity of the ink refers to contacting the color material, resin, etc. that form the ink with the component for increasing the viscosity of the ink, thereby causing a chemical reaction or physical adsorption, which will lead to a state in which the viscosity of the ink is increased. Increasing the viscosity of the ink is not limited to increasing the viscosity of the entire ink, but also includes partially increasing the viscosity due to partial polymerization of the constituent components of the ink (such as its color material, resin, etc.). The component for increasing the viscosity of the ink can be a metal ion or a polymerizer, etc. Although the component is not particularly limited, a substance for causing a pH change in the ink to polymerize the color material in the ink can be used, and an organic acid can be used. The reaction liquid is applied to the sheet S before applying (one or more than one) ink, so that the (one or more than one) ink can be fixed on the sheet S as soon as it lands on the sheet S. This prevents the adjacent ink from being mixed. Bleeding. Note that the color type, the number of colors, and the number of print heads 22 are not limited. As for the ink jet method, a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a microelectromechanical system (MEMS) element, etc. may be adopted. Ink of each color is supplied from an unillustrated ink tank to the corresponding print head 22 through a corresponding ink tube.

[0035] like Figure 2 As shown, a plurality of positioning members 711 for positioning the print head 22 are provided on the sheet conveying unit housing 71 of the image forming unit (printing unit) 7. These positioning members 711 are provided on both sides of the sheet S, and for each individual print head 22, one positioning member 711 is provided on the near side in the sheet width direction and two positioning members 711 are provided on the far side. Figure 3As shown, each print head 22 is pivotally supported in such a manner that a head support shaft 27 is supported from below by a head holding unit 26 for holding and vertically lifting the print head 22. The head holding unit 26 performs an operation for moving up and down along an elevating guide rail 29 included in a print head elevating frame 28 using a not-shown driving mechanism incorporated in the head holding unit 26. Incidentally, in the present embodiment, a print head adopting an inkjet printing method is used to apply ink to a sheet S, but a method of applying ink to a sheet at the printing unit 7 is not particularly limited to this method.

[0036] The conveyance tension detection unit 9 detects tension in tension conveyance between the first main conveyance unit 4 and the second main conveyance unit 12. The print image position detection unit 10 is a unit for detecting misalignment of an image formed on a sheet S by the image forming unit (printing unit) 7 during printing to correct printing.

[0037] The winding guide rollers R1 are rollers on each of which a surface of the sheet S at a downstream position of the second printing unit 7b in the conveying direction opposite to its ink application surface is wound at a certain winding angle. In the present embodiment, two winding guide rollers R1 are arranged between the second printing unit 7b and the second drying unit 40b, and the sheet S is bent in such a manner that a portion on the upper side of the device and a portion on the lower side of the device are substantially parallel to each other. The second drying unit 40b is arranged on the lower side of the device relative to the second printing unit 7b.

[0038] The drying unit 40 has a first drying unit 40a arranged downstream of the first printing unit 7a in the sheet conveying direction, and a second drying unit 40b arranged downstream of the second printing unit 7b in the sheet conveying direction. The first drying unit 40a and the second drying unit 40b reduce the liquid contained in the ink ejected onto the sheet S by the first printing unit 7a and the second printing unit 7b to enhance the fixability of the ink to the sheet S. The first drying unit 40a and the second drying unit 40b apply air to the printed sheet S to dry the ink applied to the sheet S. Inside the first drying unit 40a and the second drying unit 40b, air is applied to the passed sheet S at least from the side facing the ink application surface of the sheet S to dry the ink application surface of the sheet S. Incidentally, the drying method may combine a method of applying air with a method of irradiating the surface of the sheet S with electromagnetic waves (such as ultraviolet rays or infrared rays, etc.) and / or a conductive heat transfer method using contact with a heating body.

[0039] The cooling unit 50 has a first cooling unit 50a arranged downstream of the first drying unit 40a in the sheet conveying direction, and a second cooling unit 50b arranged downstream of the second drying unit 40b in the sheet conveying direction. The first cooling unit 50a and the second cooling unit 50b cool the sheet S to which the ink is fixed by the first drying unit 40a and the second drying unit 40b to solidify the softened ink. This reduces the amount of temperature change of the sheet S at the downstream stage of the printing device. Inside the first cooling unit 50a and the second cooling unit 50b, air cooler than the sheet S passing through is applied to the sheet S at least from the side facing the ink application surface of the sheet S to cool the ink application surface of the sheet S. Note that the cooling method is not limited to the method of applying air, and may also be a conductive heat transfer method using contact with a heat dissipation member or a combination of these methods.

[0040] The scanner unit 11 is a unit that reads a test image formed on a sheet S by the printing unit 7 before printing for actual production, and detects image misalignment and density based on the read test image to correct printing for actual production.

[0041] The second main conveying unit 12 conveys the sheet S while applying tension to the sheet S in cooperation with the first main conveying unit 4 to adjust the tension of the sheet S. The second main conveying unit 12 is rotated by driving a motor not shown, and the speed of the second main conveying unit 12 is controlled according to the value of the tension detected by the conveying tension detection unit 9 by using a tension control unit not shown. Incidentally, as an additional configuration for adjusting the tension of the sheet S, a configuration for adjusting the tension of the sheet S by using a clutch (not shown) capable of controlling the torque of the drive coupling may be added. As for the tension control method in this case, a torque control method for controlling the value of the torque transmitted from the clutch and a speed control method for controlling the roller speed of the second main conveying unit 12 may be adopted, and the tension control method may be switched between the two methods according to the purpose, or the two methods may be used.

[0042] The second tension adjusting unit 13 applies a constant sheet tension between the second main conveying unit 12 and the winding roller unit 14. The second tension adjusting unit 13 applies the sheet tension using a tension applying unit not shown.

[0043] The winding roller unit 14 winds the sheet S after the printing process on the winding core. The number of rolls that can be collected from the winding roller unit 14 is not limited to one. The winding roller unit 14 may have two winding cores or three or more winding cores, and the winding core to collect the sheet S may be switched alternately. In addition, the rotation of the winding roller unit 14 is controlled by a driving motor (not shown) alone, so that the winding roller unit 14 can rotate forward and reverse. The sheet S is conveyed in the forward direction by controlling the driving motor (not shown) for the unwinding roller unit 2 and the winding roller unit 14 so that the unwinding roller unit 2 and the winding roller unit 14 rotate forward. The sheet S is conveyed in the reverse direction by controlling the driving motor (not shown) for the unwinding roller unit 2 and the winding roller unit 14 so that the unwinding roller unit 2 and the winding roller unit 14 rotate reversely. Similarly, in the reverse conveying, the sheet S is conveyed under tension between the first main conveying unit 4 and the second main conveying unit 12 as in the forward conveying. Incidentally, depending on the content of post-print processing, a configuration in which the sheet S is cut with a cutter and the cut sheets are stacked may be adopted instead of a configuration in which the sheet S is wound around a core.

[0044] The control unit 31 includes a computing device such as a central processing unit (CPU) and a storage device such as a memory (random access memory (RAM), read-only memory (ROM)) and a hard disk drive (HDD). The computing device executes the program stored in the storage device to comprehensively control the above-mentioned units and realize the operation flow described later. The control unit 31 also has an external interface and an operation unit 32 for the user to perform input and output operations. The operation of the printing device 1 is controlled according to instructions from the operation unit 32 or a host device 33 (such as a host computer, etc.) connected to the printing device 1 through the external interface.

[0045] The maintenance unit 15 has a cover mechanism for protecting the inkjet surface of the print head 22, a wiping mechanism for wiping the inkjet surface, an aspiration mechanism operating unit for sucking the ink inside the print head 22 out of the inkjet surface using negative pressure, and maintains the performance of the print head 22. The maintenance unit 15 also includes a driving mechanism and a guide rail not shown, and can be horizontally reciprocated along the guide rail. During the maintenance of the print head, the maintenance unit 15 is moved to the position directly below the print head. When no maintenance operation is performed, the maintenance unit 15 is moved to a position retracted from the position directly below the print head. In the present embodiment, the maintenance unit 15 has a first maintenance unit 15a for the first printing unit 7a and a second maintenance unit 15b for the second printing unit 7b.

[0046] Incidentally, the roller R2 is a driven roller arranged downstream of the first fixing unit 8a in the conveying direction. The roller R3 is a driven roller arranged downstream of the second fixing unit 8b in the conveying direction.

[0047] [How to correct print head misalignment]

[0048] Figure 4 is a diagram for explaining a test pattern for correcting misalignment of a print head according to the present embodiment. Figure 4 An example of printing a test pattern 402 for correcting head misalignment on a print medium S serving as a sheet S is shown. Note that the following description will be given assuming that the area covering the test pattern is one page, but this does not mean that the area is cut out because the sheet S is a continuous sheet as described above. The nozzle array direction 403 indicates the direction in which the nozzles in the print head 22 are arranged. That is, the nozzle array direction 403 is consistent with the direction in which the nozzles in the print head 22 are arranged. Figure 2 The Y direction shown corresponds to the

[0049] like Figure 1 As shown, the printing device 1 includes a plurality of print heads 22. Each print head can handle color inks of white (W), black (K), cyan (C), magenta (M), and yellow (Y), and can also handle a reaction liquid (primer) as a colorless transparent ink. Some print heads 22 may be empty slots without a print head or print heads capable of handling spot colors such as gray (G), light magenta (LM), and light cyan (LC).

[0050] The scanner unit 11 is arranged downstream of the print head 22 in the conveying direction of the print medium S. The scanner unit 11 reads the test pattern 402 printed on the print medium S to detect the misalignment amount of the print head 22 .

[0051] Each print head 22 of the printing device 1 includes a plurality of print chips. The print chip 404 represents one print chip. In the present embodiment, an example is shown in which each single print chip is formed in the shape of a parallelogram. Each print head 22 includes 17 print chips 404 arranged along the nozzle array direction 403, but the number of print chips is not limited to this number and may be more or less. The nozzle array direction 403 is parallel to the nozzle array direction 403. Figure 2 The width direction 203 shown in FIG. 4 corresponds to the width direction 203 shown in FIG. 4. A plurality of nozzle arrays 405 are arranged in each printing chip 404. In the present embodiment, 16 nozzle arrays 405 are arranged in each printing chip 404, but the number of arrays is not limited to this number and can be changed. In addition, in the present embodiment, as shown in FIG. Figure 4 As shown, the nozzle array 405 in the printing chip 404 is arranged at a predetermined angle to the conveying direction. In addition, the end of the nozzle array 405 is arranged to be inclined relative to the conveying direction.

[0052] Types of head misalignment will now be described. Each of these misalignments originates from a formation error of a chip or nozzle in the print head 22 or a placement error of the print head 22, etc. Types of misalignment include inter-array misalignment (i.e., misalignment between nozzle arrays 405 in the print chip 404), inter-chip misalignment (i.e., misalignment between print chips 404), and inter-color misalignment (i.e., misalignment between print heads 22), etc. In the event of these misalignments, the landing position of the ink droplet is offset from the ideal position, thereby deteriorating the quality of the printed image. Head misalignment correction is a function of correcting the ink landing position by changing the ink ejection timing of (one or more than one) print chips 404 or changing the nozzle that ejects (one or more than one) ink.

[0053] In this embodiment, misalignment in the direction perpendicular to the nozzle array direction 403 (transport direction 201) is solved by correcting misalignment of dots formed by changing the ejection timing of each print chip 404 forming the print head 22. Misalignment in the nozzle array direction 403 is corrected by changing ejection data.

[0054] Test pattern 402 is a test pattern for correcting the misalignment of print head 22. Test pattern 402 includes test patterns 406 to 410 corresponding to five print heads 22. Each of test patterns 406 to 410 is used to detect the misalignment amount of the corresponding print head 22. Each of these test patterns is used to calculate the inter-array misalignment amount between nozzle arrays in each print chip in the corresponding print head 22, and the inter-chip misalignment amount between print chips. In the present embodiment, test patterns 406 to 410 are test patterns of print heads 22 for K, C, M, Y, and primer inks, respectively. The number of test patterns for print heads 22 included in test pattern 402 can be changed from five, and the order of the test patterns can be changed. Thus, the number of test patterns can be changed according to the number of print heads 22 to be tested. Incidentally, test pattern 411 is a test pattern for calculating the inter-color misalignment amount between print heads 22. This will be described later. Figure 7 The test pattern 411 is described in detail.

[0055] In this embodiment, Figure 4 4 shows a pattern 414 which is an enlarged version of a portion of the test pattern 406 for ink color K. Enlarged patterns (not shown) of the test patterns 407 to 409 for ink colors C, M, and Y also have a configuration similar to that of the test pattern 406. A pattern 415 which is an enlarged version of a portion of the test pattern 410 for primer ink is also shown. Note that these patterns are examples, and the correspondence between the test patterns and ink colors of each type of print head 22 may vary.

[0056] As pattern 415, a pattern in which some parts are larger than those in pattern 414 is used. In addition, although the difference in individual brightness values ​​between the base color of the print medium S and the primer ink as the printing material is small, the following processing is performed to ensure detection accuracy. Specifically, K ink is uniformly applied to the entire shadow area of ​​pattern 415, which includes the area overlapping with the detection mark 420, the alignment mark 421, and the pattern 423 for pattern matching. This produces a detection brightness difference at the parts of the detection mark 420, the alignment mark 421, and the pattern 423 for pattern matching with the primer ink. In addition, pattern 416 is a pattern corresponding to one print chip 404 included in the print head of ink color K, C, M, or Y, and pattern 419 is a pattern corresponding to one print chip 404 included in the print head of the primer ink.

[0057] In each of the patterns 414 and 415, the area depicted in black is an area printed with the corresponding ink. The area depicted in white is an area of ​​the base color of the print medium S that is not printed with the ink.

[0058] Each print head 22 is configured such that a plurality of print chips 404 are linearly arranged along the nozzle array direction 403. For each print chip 404 forming each print head 22, a pattern 416 or 419 corresponding to each print chip 404 is linearly printed in parallel with the nozzle array direction 403.

[0059] The configuration of the patterns 416 and 419 corresponding to the print chip 404 and the printing method will now be described. One pattern 416 corresponding to one print chip 404 used in the print head 22 that ejects color ink includes a detection mark 417, an alignment mark 418, and a pattern matching pattern 422. One pattern 419 corresponding to one print chip 404 used in the print head 22 that ejects primer ink includes a detection mark 420, an alignment mark 421, and a pattern matching pattern 423.

[0060] The detection marks 417 and 420 are used to detect the pattern corresponding to the printed chip 404 in the read image during the image analysis process. Figure 4 As shown, detection marks 417 and 420 are patterns printed in the form of rectangular areas. In the present embodiment, as previously mentioned, each printing chip includes a plurality of nozzle arrays. Detection marks 417 and 420 are patterns printed by ejecting ink from a plurality of nozzle arrays. In the case of a faulty nozzle, a plurality of nozzle arrays are used for printing so that the nozzles in other nozzle arrays eject ink. This reduces the missing part in the detection pattern caused by the faulty nozzle. Therefore, the detection mark will be stably detected in the image analysis process.

[0061] The alignment marks 418 and 421 are used to calculate the reference position of the analysis area of ​​the pattern matching patterns 422 and 423 in the image analysis process. Figure 4 As shown, the alignment marks 418 and 421 are printed in the form of rectangular areas. By ejecting ink from a plurality of nozzle arrays, the alignment marks 418 and 421 are each printed for one pattern matching pattern 422 or 423 corresponding to the nozzle array.

[0062] The pattern matching patterns 422 and 423 are patterns used to detect misalignment of the print head 22 in the image analysis process. The pattern matching patterns 422 and 423 are each used according to the type of printing color and misalignment amount to be calculated.

[0063] In the case of forming a pattern using primer ink, the signal difference between the brightness values ​​of the base color of the print medium S and the print color (transparent) tends to be small. That is, it is difficult to detect the difference in brightness value between the substrate and the ink. Therefore, in this embodiment, for transparent ink, a pattern matching pattern 423 larger than the pattern matching pattern 422 is used to detect misalignment.

[0064] Figure 5A and Figure 5B 4 is a diagram showing the detailed layout of the pattern matching patterns 422 and 423. Figure 5A and Figure 5B , reference numeral 501 represents the number of pixels of the pattern matching pattern 422 in the vertical direction, reference numeral 502 represents the number of pixels of the pattern matching pattern 422 in the horizontal direction, reference numeral 503 represents the number of pixels of the pattern matching pattern 423 in the vertical direction, and reference numeral 504 represents the number of pixels of the pattern matching pattern 423 in the horizontal direction.

[0065] In the present embodiment, reference numerals 501 and 502 around the pattern matching pattern 422 respectively indicate directions parallel to the conveying direction 201 and the nozzle array direction 403, and each of the reference numerals 501 and 502 is measured in 82 pixels in a unit of 1200 DPI (dots per inch). Reference numerals 503 and 504 around the pattern matching pattern 423 respectively indicate directions parallel to the conveying direction 201 and the nozzle array direction 403, and each of the reference numerals 503 and 504 is measured in 210 pixels in a unit of 1200 DPI.

[0066] Note that the number of pixels forming each pattern for pattern matching is not limited to the above, and other numbers may be used. Figure 5A and Figure 5B As shown, the pattern matching pattern 422 is smaller in size than the pattern matching pattern 423 .

[0067] Figure 6 4 is a diagram showing the correspondence between patterns 416 and 419 corresponding to one print chip 404 and its ejection nozzles. Note that other print chips forming the print head 22 have a configuration similar to that of the print chip 404.

[0068] The print chip 404 includes a plurality of nozzle arrays 405. In the present embodiment, 24 nozzle arrays 405 are arranged in one print chip 404. The test pattern of one print chip 404 is printed by using nozzles in the range indicated by dotted lines 607 and 608 in each nozzle array included in the print chip 404. The range may vary depending on the configuration of the print chip 404.

[0069] The pattern matching patterns included in the pattern 416 of one print chip 404 each correspond to one of the multiple nozzle arrays. Here, each pattern matching pattern is printed using a nozzle array with a corresponding number. Specifically, pattern matching patterns 0 to 23 are set for 24 nozzle arrays, respectively. Based on the arrangement of the nozzle patterns in the layout 601, the misalignment is calculated based on the relative position of the pattern matching pattern represented as "0" (i.e., the nozzle array assigned "0") as the reference pattern and the remaining nozzles. As an exception, a pattern matching pattern 602 is set. This is a pattern matching pattern to be printed by the nozzle array assigned "20" among the nozzles included in the adjacent print chip 404 on the left. Note that the nozzle array for printing the pattern matching pattern 602 in the adjacent print chip is not limited to the nozzle array assigned "20", and can be changed according to the number of nozzle arrays forming each print chip 404 and the shape of the print chip 404, etc.

[0070] The pattern matching pattern 602 is not a pattern printed by the print chip of interest, and therefore will not be used for calculation of misalignment of the nozzle array in the print chip of interest. One pattern 416 is printed for one print chip 404, and the misalignment of the print chip 404 and the tilt of the print head 22 due to manufacturing errors are calculated based on one pattern matching pattern of one nozzle array in the print chip 404. With the print chip corresponding to the second pattern 416 at the left or right end printed on the print medium S as a reference chip, the chip-to-chip misalignment between the print chips and the tilt of the print head 22 are calculated.

[0071] Note that the size of the print medium S is variable. Therefore, the pattern 416 at the left or right end of the print medium S may sometimes be only partially printed. In the case where such a pattern is printed with a length of the detection mark 603 or longer, the pattern matching pattern 604 is selected as the calculation pattern for the right end, and the pattern matching pattern 602 is selected as the calculation pattern for the left end.

[0072] Depending on the print head, the layout of the test pattern for each individual print chip may be such that, instead of the pattern 416, a pattern matching pattern 422 exists only at either end as shown in pattern 609. Each of these pattern matching patterns 422 corresponds to a nozzle in the layout 605. Reference symbol P in the layout 605 means that the pattern matching pattern 422 for calculating the tilt of the print head is printed with a plurality of nozzles.

[0073] Each pattern matching pattern 423 in the pattern 419 of one print chip 404 corresponds to a nozzle in the print area 606. Reference symbol P in the area 606 means that the pattern matching pattern 423 for calculating the tilt of the print head is printed using a plurality of nozzles.

[0074] Each of the patterns 416 and 419 of one print chip 404 is printed with the printing timing on the print medium S shifted by an amount taking into account the manufacturing error of its nozzle(s) and the manufacturing error of the print chip. This prevents the test patterns from overlapping each other due to errors.

[0075] Figure 7 701 is a diagram showing the correspondence between a test pattern used for calculation to correct the misalignment between colors between the print heads 22 and a print chip 404. Test pattern 701 is a test pattern used to calculate the position error between the print heads 22. Here, the pattern is printed by a print head for the print color indicated in layout 702. One print chip 404 in each print head is selected as the print chip to be used for printing the pattern. In this example, a print chip at the position of print head 703 in each print head is selected. In the present embodiment, print chip 703 is used to print the pattern. In the test pattern 701, the portion depicted in black is a pattern portion printed in the corresponding print color (ink), and the portion depicted in white is a paper white (base) portion of the print medium S. The shaded area indicates an area where K ink is continuously applied (covering the pattern area T described later).

[0076] In the present embodiment, in printing using inks represented as K, C, M, and Y, pattern matching pattern 422 is used. In printing using primer ink represented as T, pattern matching pattern 423 is used. As shown in layout 702, a pattern is printed using a print head that ejects K ink as a reference head, and the misalignment of each print head is calculated using the pattern thus printed. As the pattern of the reference head, a pattern similar to the pattern matching pattern of the printed color used to calculate the misalignment is used. This pattern is a reverse pattern K (underline) to which K ink is continuously applied around it. The pattern matching patterns of the above colors are not limited to Figure 5A and Figure 5B as well as Figure 7The pattern shown, and different patterns may be used.

[0077] When the printing timing on the print medium S is shifted by an amount greater than the maximum inter-color misregistration amount between print heads, a test pattern 701 for calculating the inter-color misregistration between the print heads 22 is printed. Shifting the printing timing of each print head in this manner prevents the test patterns from overlapping each other.

[0078] (Calculation of misalignment between nozzle arrays)

[0079] Figure 8 4 is a diagram showing a method of calculating the misalignment amount between nozzle arrays. In the present embodiment, 24 nozzle arrays are arranged in one print chip 404. Here, each nozzle array is numbered in the following manner: the first nozzle array from the downstream side in the conveying direction 201 of the print medium is defined as the 0th array, and the last nozzle array is defined as the 23rd array. Hereinafter, these nozzle arrays will be referred to as "nozzle arrays 0 to 23", respectively.

[0080] A method of calculating the misalignment amount between nozzle arrays will be described using a scanned image obtained by using a scanner to read a pattern printed based on the test pattern layout 601. In the test pattern layout 601, the numerical value indicated inside each rectangle represents the number assigned to the nozzle array used to print the corresponding pattern matching pattern. For example, pattern matching pattern 805 indicates that the pattern matching pattern is printed using nozzle array 0. Hereinafter, a printed pattern using nozzle array x will be referred to as an "array x pattern".

[0081] The test pattern layout 601 is divided into four areas 801 to 804. In area 801, array 0 patterns 805 and 806 are used as reference patterns. Similarly, in areas 802, 803, and 804, array 0 patterns 807 and 808, array 0 patterns 809 and 810, and array 0 patterns 811 and 812 are used as reference patterns, respectively. In each of areas 801 to 804, the amount of misalignment between the two array 0 patterns used as reference patterns and the print patterns using other nozzle arrays is calculated.

[0082] As an example, a method of calculating the misalignment amount between nozzle arrays 0 and 9 will be discussed. Print pattern 814 corresponds to array 0 pattern 805 in area 801, and print pattern 815 corresponds to array 0 pattern 806 in area 801. Each of print pattern 814 and print pattern 815 is an array 0 pattern used as a reference pattern. Print pattern 816 is an array 9 pattern printed in area 801.

[0083] In the case where nozzle arrays 0 and 9 print patterns with no misalignment of the landing position of the ejected ink, the array 9 pattern is printed on a straight line connecting print patterns 814 and 815. In this case where there is no misalignment of the landing position, the array 9 pattern 818 is printed at an ideal position. On the other hand, the print pattern 816 indicates the actual print position of the array 9 pattern.

[0084] The misalignment between the print patterns 816 and 818 is the misalignment of the nozzle array 9 relative to the nozzle array 0. The misalignment is represented by the misalignment 817 as the horizontal component and the misalignment 819 as the vertical component. The misalignment 819 as the vertical component is the length of the perpendicular line drawn from the print pattern 816 to the straight line connecting the print patterns 814 and 815. Thus, the misalignment 819 as the vertical component can be calculated based on the positions of the print patterns 814, 815, and 816. Similarly, the misalignment 817 as the horizontal component can be derived from these positions.

[0085] By adopting the above method, the misalignment of the array 1 pattern to the array 23 pattern can be calculated with the array 0 pattern as the reference pattern, and the misalignment of the nozzle arrays 1 to 23 relative to the nozzle array 0 can be obtained.

[0086] (Calculation of misalignment between printed chips and tilt of print head)

[0087] Fig. 9 4 is a diagram for explaining a method for calculating the misalignment amount between the print chips 404 and a method for calculating the tilt amount of the print head 22. In this embodiment, 36 print chips 404 are arranged in one print head 22, and the print chips are numbered as follows: the first print chip from the far side of the device is defined as "print chip 0", and the last print chip is defined as "print chip 35". Fig. 9 The right side is the distal side of the device and the left side is the proximal side of the device. Fig. 9 A method of calculating the amount of misalignment between printed chips using a scanned image obtained by reading a pattern printed based on the layout 601 of the pattern 416 using a scanner will be described.

[0088] Print patterns 901 to 903 are patterns printed based on the layout 601 by using three print chips in the print head 22. Depending on the size of the print medium S and its conveyance error, there may be a print chip that is not printed on the print medium S. Hereinafter, a pattern printed on the print medium S by using a print chip x is referred to as a "chip x pattern."

[0089] Print pattern 901 is a pattern printed by the second print chip from the left end to the right among the patterns printed on the print medium S. The print chip number used to print print pattern 901 varies depending on the size of the print medium S, etc. In the present embodiment, print pattern 901 is referred to as a "chip 34 pattern". Print pattern 902 is a pattern printed by the second print chip from the right end to the left among the patterns printed on the print medium S. In the present embodiment, print pattern 902 is referred to as a "chip 1 pattern". Print pattern 903 represents a layout 601 of a pattern corresponding to a print chip used to calculate the amount of misalignment between chips. The following description will be made by taking print chip 18 as an example. The print chip 18 is a print chip located at the center of the print chip array in the print head 22.

[0090] Print pattern 907 is a pattern in print pattern 901 printed using nozzle array 0 in print chip 34. Print pattern 908 is a pattern in print pattern 902 printed using nozzle array 0 in print chip 1. The print chip that prints these print patterns is a reference chip for calculating misalignment between print chips. Print pattern 911 is a pattern printed using nozzle array 0 in print chip 18, which is a chip for calculating the amount of misalignment between chips.

[0091] In the case where the nozzle array 0 in the print chips 1, 18, and 34 prints the print pattern in a state where there is no misalignment of the landing position, the chip 18 pattern printed by the print chip 18 is on a straight line connecting the print patterns 907 and 908. The print pattern 912 indicates the position of the chip 18 pattern printed at an ideal position in the case where there is no misalignment of the landing position of the ejected ink. On the other hand, the print pattern 911 indicates the actual print position of the chip 18 pattern.

[0092] The misalignment between the print patterns 911 and 912 is assumed to be a misalignment of the relative position of the straight line connecting the print chips 1 and 34 and the print chip 18, and the misalignment amount will be referred to as "misalignment amount 914". The misalignment amount 914 is the length of a perpendicular line drawn from the print pattern 911 to the straight line connecting the print patterns 907 and 908. Thus, the misalignment amount 914 can be derived from the positions of the print patterns 907, 908, and 911. In addition, the misalignment amount 913 can be derived by calculating the distance between a line that passes through the print pattern 911 and perpendicularly intersects the straight line connecting the print patterns 907 and 908 and a line that passes through the print pattern 912 and perpendicularly intersects the straight line. Thus, the misalignment amount in the direction perpendicular to the straight line connecting the print patterns 907 and 908 can be used to correct the printing position.

[0093] By adopting the above method, the misalignment amount of each print chip between the two print chips located around the left and right end portions serving as the reference chips with respect to the straight line connecting the reference chips can be found. Note that a different calculation method is used for the print chips located farther on the end side than the two reference chips (print chips 34 and 1 in the illustrated example) (i.e., the print chips at the leftmost and rightmost ends).

[0094] In this example, of the two print chips used as reference chips, the print chip around the left end is the print chip 34, and the print chip around the right end is the print chip 1. Therefore, there are the print chip 35 at the left end as the print pattern 911 to be adjusted, and the print chip 0 at the right end as the print pattern 911 to be adjusted. As with the other print chips, the misalignment amount of the print chip at the left end is calculated using the pattern matching pattern 604 in the layout 601. On the other hand, for the print chip at the right end, the pattern matching pattern 602 formed by the print chip adjacent to the left is used instead of the pattern matching pattern 604. This is because there is a possibility that the print chip at the end can only print the layout 601 to the middle length on the print medium S.

[0095] Depending on the length of the print medium S, there may be print chips outside the print chips at the left and right ends of the printing range. Since these print chips cannot be printed on the print medium S, their patterns cannot be detected. Therefore, for the print chips outside the left end, the misalignment amount of the chip adjacent to the right end is used as the correction value. Similarly, for the print chips outside the right end, the misalignment amount of the chip adjacent to the left end is used as the correction value.

[0096] Will use Fig. 9 A method of calculating the tilt amount of the print head 22 using a scanned image of a pattern printed based on the layout 601 is described. The calculation of the tilt amount of the print head 22 uses a pattern similar to the pattern for calculating the misalignment amount between the print chips 404. Regarding the tilt of the print head 22, the tilt amount relative to the reference head will be regarded as the misalignment amount. The tilt correction amount is calculated for each print head other than the reference head.

[0097] Reference numeral 906 denotes a diagram for explaining a method for calculating the amount of inclination of the print head 22. First, the amount of inclination of the reference head is calculated. Print patterns 907 and 908 are print patterns formed by the reference chips around the left and right ends described above. Angle 916 represents an angle formed by a straight line connecting the print patterns 907 and 908 and an ideal line without misalignment of the landing position due to the inclination of the print head 22, and indicates the amount of inclination of the reference head.

[0098] Next, the tilt amount of the print head to be corrected is calculated. Print patterns 909 and 910 are print patterns formed by the above-mentioned reference chips around the left and right ends of the print head to be corrected. Angle 917 represents the angle formed by the straight line connecting the print patterns 909 and 910 and the ideal line without the landing position misalignment caused by the tilt of the print head 22, and indicates the tilt amount of the print head to be corrected.

[0099] Finally, the calculation amount for correcting the tilt of the print head to be corrected is calculated. The tilt amount of the print head to be corrected can be calculated by the following formula: The tilt amount of the print head is expressed in the form of an angle.

[0100] The tilt amount of the print head to be corrected = Angle 917 - Angle 916

[0101] In the present embodiment, the print head 22 that performs printing using K ink among the print heads 22 is the reference head. By adopting the above method, the amount of inclination of each print head other than the reference head (K print head) relative to the reference head can be obtained.

[0102] (Calculation of the amount of misalignment between print heads (misalignment between colors))

[0103] Fig.10 2 is a diagram for explaining a method for calculating the misalignment amount between print heads. In the present embodiment, the print head for ejecting K ink (i.e., the first print head from the downstream side in the conveying direction 201 of the print medium S) will be referred to as "print head K", and the print heads for ejecting C, M, and Y inks will be referred to as "print head C", "print head M", and "print head Y", respectively. In addition, each print head for ejecting transparent ink will be referred to as "print head T". A method for calculating the misalignment amount between print heads (hereinafter referred to as "inter-color misalignment") using a scanned image obtained by reading a pattern printed based on a layout 702 of a test pattern 701 using a scanner will be described.

[0104] Test pattern 701 is a test pattern for calculating the amount of misalignment between colors. Test pattern 701 is printed using a print chip 703 at a predetermined position of each print head 22 for a predetermined color indicated in layout 702. In the present embodiment, chip 18 is used as the print chip 703 at the above-mentioned predetermined position. Print patterns 1001 to 1010 are patterns printed by a reference head, and in the present embodiment, patterns printed by print head K. Patterns of other print colors are patterns of colors for calculating misalignment between print heads. In the present embodiment, these patterns are C, M, Y, and T (primer ink) patterns, but the number of print colors can be changed. In the present embodiment, there is a vacant area for additionally placing patterns for other print heads.

[0105] In this embodiment, the C, M and Y heads are connected by using Figure 5A The K print patterns 1001 to 1006 used as reference patterns for these heads are also printed using the arrangement of the pattern matching pattern 422.

[0106] By using Figure 5B The configuration of the pattern matching pattern 423 shown in FIG. 1 is used to print the print pattern 1017 using the primer ink. The print patterns 1007, 1008, 1009, and 1010, which are the K pattern used as the reference pattern of the print pattern 1017, are printed using the configuration of the reverse pattern K (underline), which is as shown in FIG. Figure 7 This is an outline version of the pattern matching pattern 423. The head for which the inter-color misalignment relative to the reference head is to be calculated uses a pattern matching pattern of the same size.

[0107] In this embodiment, when calculating the misalignment between the print head K (reference head) and other print heads, a similar method is used for each print head. Hereinafter, the calculation method of the misalignment between the print head K and the print head T (primer ink) will be described as an example.

[0108] Print pattern 1020 corresponds to print pattern 1007, and print pattern 1021 corresponds to print pattern 1008. These print patterns are reference head patterns printed by print chip 18 in print head K. Print pattern 1022 is a pattern corresponding to print pattern 1017 and printed by print chip 18 in print head T, and is a print pattern printed by the print head for which the misalignment amount is to be calculated.

[0109] In the case where the print heads K and T print the print pattern without any misalignment of the landing position of the ejected ink, the patterns are arranged so that the print pattern of the print head T is on a straight line connecting the print patterns 1020 and 1021. The print pattern 1024 indicates the position of the print pattern printed at the ideal position by the print head T without any misalignment of the landing position of the ejected ink. On the other hand, the print pattern 1022 indicates the actual print position of the chip 18 pattern.

[0110] In the present embodiment, the misalignment between the print patterns 1022 and 1024 in the scanned image is assumed to be the misalignment of the print head T relative to the print head K. This misalignment amount will be referred to as "misalignment amount 1025". The misalignment amount 1025 is the length of a perpendicular line drawn from the print pattern 1022 to the straight line connecting the print patterns 1020 and 1021. Thus, the misalignment amount 1025 can be obtained according to the positions of the print patterns 1020, 1021, and 1022. In addition, the distance between the line passing through the print pattern 1022 and perpendicularly intersecting the straight line connecting the print patterns 1020 and 1021 and the line passing through the print pattern 1024 and perpendicularly intersecting the straight line is obtained. In this way, the misalignment amount 1026 between the print patterns 1024 and 1022 can be obtained. In the present embodiment, for the calculation of the print head misalignment correction, the correction amount in the direction perpendicular to the misalignment amount 1025 is also calculated. Therefore, correction amounts are calculated for head misalignment amounts in two directions (ie, misalignment amounts 1025 and 1026).

[0111] By adopting the above method, the amount of inter-color misalignment of each print head other than the print head K with respect to the reference head can be obtained.

[0112] (Marker Detection Processing)

[0113] Fig.11 : is a diagram for explaining the mark detection processing of the print chip 404. In this embodiment, a process of detecting the detection mark in each pattern of the print chip 404 from the read image of the test pattern for calculating the misalignment amount will be described. Fig.11 It shows that Figure 6 Some printed chip patterns such as pattern 416 shown.

[0114] In this embodiment, the pattern of the printed chip 404 includes Figure 6 The three types of patterns 416, 419 and 609 shown in FIG. 1 are detected and processed similarly for each type. Figure 7 The test pattern 701 shown for calculating the position error between the print heads 22 is also similar. Figure 6 The illustrated pattern 416 is described as an example.

[0115] The mark detection process mainly includes three steps. In the first step, the detection mark 417 is detected. Based on the detected position of the detection mark 417, the position of the test pattern of the single print chip 404 is estimated.

[0116] In the second step, the alignment mark 1103 is detected based on the estimated position of the test pattern in the first step. Figure 6The pattern 416 in FIG. 1 is used as an example, so the alignment mark 1103 is a mark similar to the alignment mark 418. Each of these alignment marks 1103 is printed near the pattern matching pattern. Therefore, based on the detection position of the alignment mark 1103, the position of the corresponding pattern matching pattern is estimated.

[0117] In the third step, the pattern position is detected by using pattern matching based on the estimated position of the pattern for pattern matching in the second step. Figure 6 The pattern 416 in FIG. 1 is used as an example, and thus the region 1104 corresponds to the pattern 422 for pattern matching.

[0118] The process of detecting the detection mark 417 in the first step will now be described. In this process, among the brightness values ​​of the three RGB channels of the read image that can be read by the inspection unit 9B, the brightness value of the channel whose print color of the print head corresponding to the detection object pattern has the highest density is used. For example, the R channel is used in the case where the color with the highest density is C (cyan), the G channel is used in the case where the color with the highest density is M (magenta), and the B channel is used in the case where the color with the highest density is Y (yellow). By the way, in the case where all channels have a high-density print color (such as K (black) etc.), any one of these channels is designated and used.

[0119] Reference numeral 1105 denotes an enlarged view of a portion of the detection mark 417. The detection mark 417 is detected based on the average density of a predetermined area in the read image. The detection mark detection area 1106 is an area for obtaining the average density. In the case where the average density obtained from the detection mark detection area 1106 is above the predetermined density, the area is identified as the detection mark area, and the center position of the area is set as the detection mark detection position 1107. The range of the detection mark detection area and the predetermined density to be used as the threshold value can be changed.

[0120] After that, the positions of the upper left end and the upper right end of the detection mark 417 are detected. Reference numeral 1108 denotes an enlarged view of a portion around the upper left end of the detection mark 417, and reference numeral 1110 denotes an enlarged view of a portion around the upper right end. An area having a predetermined density or more from the detection mark detection position 1107 is scanned. The upper left end of the area having a predetermined density or more is defined as a detection mark upper left end position 1109. Similarly, the upper right end of the area having a predetermined density or more is defined as a detection mark upper right end position 1111.

[0121] With the position determined based on the detection mark upper left end position 1109 as the starting point, the center of gravity of the concentration of the predetermined area is calculated to estimate the alignment mark detection range. Figure 4By using the detection mark 417 in the pattern 416, the range for detecting the alignment mark 1103 can be estimated. The detection process of the alignment mark 1103 is similar to the detection process of the detection mark 417. The position of the alignment mark 1103 is detected by scanning an area having a predetermined density or more and calculating the center of gravity of the density of the area.

[0122] After that, the position of the pattern matching pattern is estimated. Area 1104 is an area indicating the position of the upper left end of the pattern matching pattern. The detection result of the detection mark 417 is used to determine which chip in which print head the pattern corresponds to as a test pattern. After the position of each pattern matching pattern is roughly determined by the above-mentioned processing, a position detection process including a pattern matching process is performed to detect the final position in the image. This position of the pattern matching pattern in the image is a position for calculating the distance to be used for calculating various misalignment amounts in the head misalignment correction. The above-mentioned various misalignment amounts are manufacturing errors between nozzle arrays, manufacturing errors between chips, tilt of the print head, and misalignment between print heads.

[0123] (Processing Flow)

[0124] Fig. 12A and Fig. 12B : is a flowchart showing the flow of the printing position adjustment process. Fig. 12A The entire flow of the printing position adjustment process is shown. Fig. 12B The detailed flow of the pattern analysis process is shown. The print position adjustment process in this embodiment can be performed at any timing selected by the user (such as when the print medium is changed to a different type from the print medium printed last time, etc.). As described above, pattern printing and pattern reading are performed, and then pattern analysis is performed. Note that the following analysis process is implemented using the CPU of the control unit 31 of the printing device 1 used as an image processing device, but can also be implemented using a CPU installed in the scanner unit 11 or the host device 33. In addition, the processing can be divided and shared by, for example, having the printing device 1 perform part of the processing and having the host device 33 perform the rest of the processing.

[0125] In S1201, the CPU of the control unit 31 prints a test pattern 402 of colored materials and colorless materials on a print medium S using a print head. In S1202, the CPU of the control unit 31 reads the test pattern 402 printed on the print medium S using the scanner unit 11, and obtains a detection mark, an alignment mark, and a pattern for pattern matching from the scanned image (read image) obtained thereby. In S1203, the CPU of the control unit 31 analyzes the pattern obtained in S1202. In S1204, based on the analysis result obtained in S1203, the CPU of the control unit 31 updates the print position adjustment value (i.e., an adjustment value for adjusting the misalignment between the print positions of the print head). Specifically, the CPU of the control unit 31 stores or applies the print position adjustment value. In this way, the printing device 1 can adjust the misalignment between the print positions of the print head based on the print position adjustment value.

[0126] (Details of pattern analysis)

[0127] Now we will use Fig. 12B Describe the detailed process of pattern analysis (S1203). Note that, as already referred to Fig.11 As described above, through image analysis processing, a pattern corresponding to the target chip in the test pattern 402 printed on the print medium is detected based on the detection marks 417 and 420 .

[0128] In S1211, the CPU of the control unit 31 recognizes the registration mark and the pattern with a predetermined density as a threshold value, and calculates the coordinates of the print patterns 1007 and 1008 used as reference patterns. Figure 7 and Fig.10 As described above, the inversion pattern K (underline) is used. For this purpose, a value obtained by subtracting the brightness value of any channel read by the inspection unit 9B from, for example, 255 in the case of using 8-bit data is used as an inverted brightness value.

[0129] In S1212, the CPU of the control unit 31 detects the print pattern 1017 using the primer ink. In S1213, the CPU of the control unit 31 determines whether the pattern recognition process in S1212 is successful. First, assuming that the detection mark and the alignment mark have a lower concentration than their surroundings like the reference patterns 1007 and 1008, the CPU of the control unit 31 roughly determines the position of the print pattern 1017 by detecting the mark position using the inverted brightness value of the reading channel. After that, the CPU of the control unit 31 performs a position detection process including a pattern matching process, and for example, when the position detection ends without error (such as failing to find an area matching the pattern 423, etc.), it is determined that the pattern recognition process is successful. In the case of obtaining a judgment result indicating that the print pattern 1017 is successfully detected ("Yes" in S1213), the process enters S1216. In the case of obtaining a judgment result indicating that the print pattern 1017 cannot be detected ("No" in S1213), the process enters S1214.

[0130] In S1214, the CPU of the control unit 31 performs a tone inversion process of inverting the tone of the read data of the object portion, thereby generating an inverted image as a read image with inverted density. Specifically, unlike S1212, the CPU of the control unit 31 performs analysis using the brightness value of a normal read channel (opposite to the reference patterns 1007 and 1008) assuming that the print pattern 1017 using the primer has a higher density than its surroundings. As a result, a tone inversion pattern (hereinafter also referred to as an "inversion pattern") is obtained.

[0131] In S1215, the CPU of the control unit 31 determines whether the reverse pattern is successfully detected. First, the CPU of the control unit 31 roughly determines the position of the print pattern 1017. Specifically, assuming that the detection mark and the alignment mark have a lower concentration than their surroundings as in the "reverse pattern" (which is different from the reference patterns 1007 and 1008 due to the inversion of the brightness value), the CPU of the control unit 31 detects the mark position using the reverse brightness value of the read channel. Through this detection, the position of the pattern 1017 is roughly determined. Subsequently, the CPU of the control unit 31 performs a position detection process including a pattern matching process, and, for example, when the position detection ends without error (such as failing to find an area matching the pattern 423, etc.), it is determined that the reverse pattern is successfully detected. In the case of obtaining a judgment result indicating that the reverse pattern is successfully detected ("Yes" in S1215), the process enters S1216. In the case of obtaining a judgment result indicating that the reverse pattern cannot be detected ("No" in S1215), the process enters S1217.

[0132] In S1216, based on the coordinate analysis between the patterns, the CPU of the control unit 31 calculates the misalignment amount and the adjustment value. As a result, the adjustment value is obtained. In other words, in the case of obtaining "yes" in S1213, the adjustment value is determined based on the result of pattern recognition of the read image. In the case of obtaining "yes" in S1215, the adjustment value is determined based on the result of pattern recognition of the inverted image.

[0133] FIG. 13A to FIG. 13B 1 is a diagram showing a part of a test pattern on print media having different ink permeation characteristics in this embodiment. Fig.13A shows the case of coated paper, while Fig. 13B The case of uncoated paper is shown. Note that Fig.13A and Fig. 13B The method of applying ink during printing is exactly the same. Fig.13A In the case of the coated paper shown in FIG. 1 , K ink is then applied to the entire area of ​​the print primer pattern 1302. The reference patterns 1301 and 1303 are patterns without K ink. For example, the K ink applied to the print primer pattern 1302 that does not completely penetrate the coated paper flows to the surroundings, making the base (i.e., background color) of the coated paper transparent and visible. On the other hand, in Fig. 13B In the case of the non-coated paper shown, the printed primer pattern 1305 will penetrate quickly so that the subsequently applied K ink will not flow around. The primer ink reacts chemically with the color ink to improve its color rendering. Therefore, the printed primer pattern 1305 has a higher concentration than the surrounding area where the primer is not applied.

[0134] Fig. 13C 1 is a diagram showing an example test pattern using W ink and primer for W ink for film (such as a transparent film label attached to a colored release paper). Reference numeral 1310 represents the background color of the film, and as in the case of K ink, reference patterns 1307 and 1309 are formed as patterns whose insides are partially removed. Print primer pattern 1308 is arranged in the middle to calculate the misalignment amount of the printing position relative to W ink. As for the color tone in the analysis, print primer pattern 1308 is in Fig.13A The state in which all brightness values ​​in the test pattern are inverted is shown.

[0135] In S1217, the CPU of the control unit 31 determines that an analysis error has occurred, and does not update the adjustment value.

[0136] After completing the processing of S1216 or S1217, the CPU of the control unit 31 terminates Fig. 12B The pattern analysis process shown.

[0137] As described above, according to the present embodiment, it is possible to analyze the print position adjustment pattern of the colorless transparent primer ink regardless of the permeation characteristics of the print medium and accurately adjust the misaligned print position between the print heads.

[0138] [Example 2]

[0139] In Embodiment 2, how to perform processing in the case of obtaining information on a print medium to be printed will be described using drawings.

[0140] FIG. 14A to FIG. 14D : is a flowchart showing the flow of the printing position adjustment process in this embodiment. Fig.14A The entire printing position adjustment process is shown in FIG. Fig. 14B The details of the pattern analysis process (S1402) are shown. Fig. 14C The details of the pattern analysis process (S1412) for the film are shown, and Fig.14D Details of the pattern analysis process (S1413) for paper are shown. Fig.15 is a diagram showing an example analysis target pattern.

[0141] (Flow of Print Position Adjustment Processing)

[0142] In this embodiment, the difference between this embodiment and Embodiment 1 will be mainly described.

[0143] In S1401, the CPU of the control unit 31 obtains information related to the print medium. For example, the CPU of the control unit 31 obtains information related to the print medium (print medium information) specified by a user operation on a user interface (UI) screen displayed on the operation unit 32. For example, in the case where the print object is paper, the CPU of the control unit 31 obtains print medium information indicating that the print object is paper. In the case where the print object is film, the CPU of the control unit 31 obtains print medium information indicating that the print object is film.

[0144] In S1402, the CPU of the control unit 31 performs pattern analysis.

[0145] (Details of pattern analysis)

[0146] In the pattern analysis (S1402), first, in S1411, the CPU of the control unit 31 determines whether the print medium information obtained in S1401 is print medium information for indicating that the print object is a film. In the case where the judgment result indicates that the print medium information for indicating that the print object is a film is obtained ("Yes" in S1411), the processing enters S1412. In the case where the judgment result indicates that the print medium information for indicating that the print object is a film is not obtained ("No" in S1411), the processing enters S1413. After the processing of S1412 or S1413, the CPU of the control unit 31 terminates Fig. 14B The process shown.

[0147] (Details of pattern analysis processing for film)

[0148] In S1421, as in S1211, the CPU of the control unit 31 calculates the coordinates of the reference pattern. In S1422, the CPU of the control unit 31 performs a tone inversion process of inverting the tone in the data obtained by reading the position detection pattern of the color ink and the transparent ink as the target pattern, thereby generating a reverse image as a read image in which the density is inverted. The process of S1422 is the same as S1214, and its detailed description is omitted.

[0149] In S1423, the CPU of the control unit 31 performs recognition processing on the pattern (reverse pattern) in the reverse image. In the case of obtaining a judgment result indicating that the reverse pattern is recognized ("Yes" in S1423), the process proceeds to S1424. In the case of obtaining a judgment result indicating that the reverse pattern cannot be recognized ("No" in S1423), the process proceeds to S1425.

[0150] In S1424, as in S1216, based on the coordinate analysis between the patterns, the CPU of the control unit 31 calculates the misalignment amount and the adjustment value. As a result, the adjustment value is obtained. In other words, the adjustment value is determined based on the result of pattern recognition of the inverted image. In S1425, as in S1217, the CPU of the control unit 31 determines that an analysis error has occurred, and does not update the adjustment value. After the processing of S1424 or S1425, the CPU of the control unit 31 terminates Fig. 14C The process shown.

[0151] Note that the detailed flow of the pattern analysis process (S1413) for paper is shown in FIG. Fig.14D and Fig. 12B The pattern analysis process (S1203) shown is the same, and its detailed description is omitted.

[0152] <Relationship between paper, film and pattern>

[0153] Fig.15 : is a diagram showing the relationship between paper and film and a print pattern. Note that reference symbol K indicates use of black ink, reference symbol Pri indicates use of primer ink, and reference symbol Whi indicates use of white ink. Fig.15 The top row of the table shown indicates the types of print media to be printed on and indicates if these types are paper and film. Fig.15 The second row from the top of the illustrated table indicates the colors of the print media, and indicates the cases where these colors are white and transparent.

[0154] like Fig.15 As shown, in the case of paper, due to its permeability, it can be seen that the pattern will appear as A or B. First, the analysis process is started under the assumption that A represents a tonal relationship. In the case where it is determined that the primer pattern in the center cannot be identified, the analysis is performed again under the assumption that B is a tonal relationship. In the case of a non-permeable film, instead of the setting for indicating that A is a tonal relationship, the analysis is performed only based on the setting for indicating that B is a tonal relationship. As described above, the analysis is performed based on the setting corresponding to the type of printing medium, which shortens the time required for the analysis. Incidentally, C represents the position adjustment pattern of the white ink to be used on the transparent film and the primer ink for the white ink. In this case, since the concentration of the pattern to be identified is high, concentration inversion is not required. Therefore, the data obtained by the same processing as in normal cases is analyzed.

[0155] As described above, according to this embodiment, analysis corresponding to the type of print medium to be printed can be performed. In the case where the print medium is a film, processing for identifying that the print object is a film is not required, so that the time required for analysis is correspondingly shortened.

[0156] In Embodiment 1, a reverse image of a read image with reversed density is generated based on the result of pattern recognition processing. In Embodiment 2, in the case where the printing medium is a film, a reverse image is generated by reversing the density of the read image based on printing medium information. In the case where the printing medium is paper, a reverse image of a read image with reversed density is generated based on printing medium information and the result of pattern recognition processing. Thus, a reverse image of a read image with reversed density is generated based on at least one of the printing medium information and the result of pattern recognition processing. In this way, misalignment between the printing positions of the print head can be accurately adjusted. Note that a configuration for switching between the processing in Embodiment 1 and the processing in Embodiment 2 can be adopted. For example, the UI screen may include an area where the user can select between the processing in Embodiment 1 and the processing in Embodiment 2.

[0157] [Other embodiments]

[0158] 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.

[0159] While the present disclosure 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.

[0160] According to the technology of the present disclosure, it is possible to accurately adjust the misalignment between the printing positions of the print heads regardless of the permeability characteristics of the print medium to the colorless material for fixing the color material.

Claims

1. An image processing device, comprising: an obtaining unit for obtaining a read image obtained by reading a pattern for a colored material and a colorless material formed on a printing medium by a printing head; as well as A determination unit for determining an adjustment value for adjusting misalignment between printing positions of the print head by generating a reverse image of the read image as a concentration-inverted read image based on a result of recognition processing of a pattern in the read image and at least one of print medium information indicating a type of the print medium.

2. The image processing device according to claim 1, in, The determination unit determines the adjustment value by generating the reverse image based on a result of the recognition process.

3. The image processing device according to claim 2, in, The determination unit generates the reverse image when the pattern in the read image cannot be recognized, and determines the adjustment value based on the pattern in the generated reverse image.

4. The image processing device according to claim 2, in, The determination unit determines the adjustment value based on the pattern in the read image when the pattern in the read image can be recognized.

5. The image processing device according to claim 1, in, The determination unit determines the adjustment value by generating the reverse image based on the printing medium information.

6. The image processing device according to claim 5, in, The determination unit generates the reverse image if the printing medium information indicates that the printing medium is a film, and determines the adjustment value based on a pattern in the generated reverse image.

7. The image processing device according to claim 5, in, The determination unit generates the reverse image if the printing medium information indicates that the printing medium is paper and a pattern in the read image cannot be recognized, and determines the adjustment value based on the pattern in the generated reverse image.

8. The image processing device according to any one of claims 3, 6 and 7, in, In the case that the pattern in the reverse image cannot be recognized, the determination unit does not update the adjustment value.

9. The image processing device according to claim 5, in, In a case where the printing medium information indicates that the printing medium is paper and a pattern in the read image can be recognized, the determination unit determines the adjustment value based on the pattern in the read image.

10. The image processing device according to claim 1, in, The read image is an image obtained by forming the pattern with the colorless material ejected from one of the print heads, covering the pattern with the color material ejected from the other of the print heads, and then reading the pattern.

11. The image processing device according to claim 1, in, The colorless material is used to fix the colored material to the printing medium.

12. The image processing device according to claim 1, in, The print head is an inkjet print head.

13. The image processing device according to claim 1, in, The print heads are full line print heads in each of which nozzles ejecting ink are arranged over a length equivalent to a width of the print medium.

14. An image processing method, comprising: obtaining a read image obtained by reading a pattern for a colored material and a colorless material formed on a printing medium by a print head; as well as An adjustment value for adjusting misalignment between printing positions of the print head is determined by generating a reverse image of the read image as a concentration-inverted read image based on a result of recognition processing of a pattern in the read image and at least one of print medium information indicating the type of the print medium.

15. A non-transitory computer-readable storage medium storing a program for causing a computer to perform an image processing method, the image processing method comprising: obtaining a read image obtained by reading a pattern for a colored material and a colorless material formed on a printing medium by a print head; as well as An adjustment value for adjusting misalignment between printing positions of the print head is determined by generating a reverse image of the read image as a concentration-inverted read image based on a result of recognition processing of a pattern in the read image and at least one of print medium information indicating the type of the print medium.

16. A computer program product comprising a program for causing a computer to perform an image processing method, the image processing method comprising: obtaining a read image obtained by reading a pattern for a colored material and a colorless material formed on a printing medium by a print head; as well as An adjustment value for adjusting misalignment between printing positions of the print head is determined by generating a reverse image of the read image as a concentration-inverted read image based on a result of recognition processing of a pattern in the read image and at least one of print medium information indicating the type of the print medium.

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