Printing apparatus and printing method

Abstract

A printing apparatus and printing method are provided, which can appropriately perform nozzle inspection even when read in an inclined state. N is an integer of 3 or more. TP has a main TP consisting of N pattern element groups arranged in a first direction at N cycles and arranged offset from each other in a second direction intersecting the first direction, and at least one of a first sub-TP disposed in a region sandwiching the main TP in the second direction and a second sub-TP disposed in another region. The first sub-TP is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the region in the second direction among the N pattern element groups. The second sub-TP is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the region in the second direction among the N pattern element groups.

Description

Technical Field

[0001] This invention relates to printing apparatus and printing method. Background Technology

[0002] A technology is disclosed as follows: an inkjet printing device that records a test pattern on printing paper through a recording head, reads the test pattern through a scanner, performs interpolation processing on the read data, and determines the nozzle abnormality based on the interpolated read data (refer to Patent Document 1).

[0003] In the document 1 Figure 3 The paper discloses a stepped test pattern as described below: rows printed according to the nozzle units of the recording head are arranged in a column pattern of eight cycles, and the column patterns are staggered from each other in a direction orthogonal to the nozzle arrangement direction. By printing in a stepped manner with the rows corresponding to each nozzle staggered, the identification and visual recognition of each row can be easily performed.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-54970

[0005] However, when a scanner reads a printed medium bearing a test pattern, there is a possibility that the medium may be tilted. In the read data obtained from reading a tilted medium, the greater the misalignment between the measured rows regarding the spacing between lines, the more either too wide or too narrow the spacing becomes. Therefore, it may be difficult to detect the original spacing between the printed rows based on the read data, resulting in difficulty maintaining the accuracy of nozzle inspection. Therefore, a test pattern is needed that allows for proper nozzle inspection even when read from a tilted position. Summary of the Invention

[0006] The printing apparatus includes: a printhead having a plurality of nozzles that eject ink; and a control unit that controls the printhead to print a test pattern onto a printing medium for checking the state of ink ejection from the nozzles, where N is an integer of 3 or more. The test pattern includes: a main test pattern, which is a main test pattern having a plurality of pattern elements printed by the nozzles arranged in a first direction, and consisting of N pattern element groups arranged in a period of N in the first direction but staggered from each other in a second direction intersecting the first direction; and at least one of a first sub-test pattern disposed in one of two regions sandwiching the main test pattern in the second direction and a second sub-test pattern disposed in the other of the two regions, wherein the first sub-test pattern is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the first region in the second direction among the N pattern element groups, and the second sub-test pattern is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the other region in the second direction among the N pattern element groups.

[0007] The printing method includes: a printing step in which a test pattern for checking the state of ink ejection from the nozzles is printed onto a printing medium by controlling a print head having a plurality of nozzles that eject ink, where N is an integer greater than or equal to 3. The test pattern includes: a main test pattern, which is a main test pattern having a plurality of pattern elements printed by the nozzles arranged in a first direction, and consisting of N groups of pattern elements arranged in a period of N in the first direction but staggered from each other in a second direction intersecting the first direction; and at least one of a first sub-test pattern disposed in one of two regions sandwiching the main test pattern in the second direction and a second sub-test pattern disposed in the other of the two regions, wherein the first sub-test pattern is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the first region in the second direction among the N groups of pattern elements, and the second sub-test pattern is composed of pattern elements printed by a nozzle that prints pattern elements of the pattern element group located furthest from the other region in the second direction among the N groups of pattern elements. Attached Figure Description

[0008] Figure 1 It is a simple block diagram showing the structure of the device.

[0009] Figure 2 This is a diagram showing a specific example of the structure including the print head and the conveyor section.

[0010] Figure 3 This diagram illustrates the relationship between the printing medium and the print head from an upward perspective.

[0011] Figure 4 This is a flowchart illustrating the process from TP printing to nozzle inspection.

[0012] Figure 5 This is a diagram showing a portion of the TP involved in the first embodiment.

[0013] Figure 6 It is a diagram showing printing media, etc., with each ink color printed on TP.

[0014] Figure 7 This is a diagram showing a portion of the TP involved in the second embodiment.

[0015] Figure 8 This is a diagram showing a portion of the TP involved in the third embodiment.

[0016] Figure 9 This is a diagram showing a portion of the TP involved in the fourth embodiment.

[0017] Figure 10 This is a diagram showing the state of a printed medium with TP printed on it.

[0018] Explanation of reference numerals in the attached figures

[0019] 10… Printing apparatus; 11… Control unit; 11a… CPU; 11b… ROM; 11c… RAM; 12… Program; 12a… Printing control unit; 12b… Reading control unit; 12c… Inspection unit; 16… Transport unit; 17… Carriage; 18… Print head; 19… Reading unit; 21… Nozzle; 26, 26C, 26M, 26Y, 26K… Nozzle array; 30… Printing medium; 31… First area; 32… Second area; 40C, 40M, 40Y, 40K… TP; 41C, 41M, 41Y, 41K… Main TP; 41C1… First pattern element group; 41C2… Second pattern element group; 41C3… Third pattern element group; 42C, 42M, 42Y, 42K… Second sub-TP; 43C… Pattern element; 44C… First sub-TP. Detailed Implementation

[0020] The embodiments of the present invention will now be described with reference to the figures. It should be noted that the figures are merely examples for illustrating these embodiments. As the figures are examples, there may be instances where proportions or shapes are incorrect, they do not match each other, or parts are omitted.

[0021] 1. Device Composition:

[0022] Figure 1 The configuration of the printing apparatus 10 according to this embodiment is shown in a simplified manner.

[0023] The printing apparatus 10 includes a control unit 11, a display unit 13, an operation receiving unit 14, a communication interface 15, a transport unit 16, a carriage 17, a print head 18, and a reading unit 19. IF is short for interface. The control unit 11 is configured to include one or more ICs such as a CPU 11a, ROM 11b, and RAM 11c that serve as processors, as well as other non-volatile memories.

[0024] In the control unit 11, the processor, i.e., the CPU 11a, uses RAM 11c and the like as a working area to execute arithmetic processing based on one or more programs 12 stored in ROM 11b, other memory, etc., thereby realizing various functions such as the printing control unit 12a, the read control unit 12b, and the inspection unit 12c. It should be noted that the processor is not limited to a single CPU; it can also be configured to perform processing through multiple CPUs, ASICs, or other hardware circuits, or it can be configured to perform processing through the coordinated operation of the CPU and hardware circuits.

[0025] Display unit 13 is a unit for displaying visual information, and may be composed of, for example, a liquid crystal display (LCD) or an organic EL display. Display unit 13 may also include a display and driving circuitry for driving the display. Operation receiving unit 14 is a unit for receiving user operations, and may be implemented via, for example, physical buttons, a touch panel, a mouse, or a keyboard. Of course, a touch panel may also be implemented as a function of display unit 13.

[0026] The display unit 13 and the operation receiving unit 14 may be part of the printing apparatus 10, but they may also be peripheral devices external to the printing apparatus 10. The communication IF 15 is a general term for one or more IFs used by the printing apparatus 10 to connect to the outside in a wired or wireless manner according to a specified communication protocol including known communication standards.

[0027] The transport unit 16 is a unit for transporting the printing medium, including rollers and a motor that rotates the rollers. The print head 18 performs printing by spraying ink from nozzles onto the printing medium using an inkjet method. The readout unit 19 is a unit for reading the printing result on the printing medium. The readout unit 19 is also referred to as a scanner. However, the printing apparatus 10 may also be configured without the readout unit 19.

[0028] The carriage 17 is a mechanism capable of reciprocating in a predetermined direction by receiving power from a carriage motor (not shown). The predetermined direction in which the carriage 17 is moved is also called the main scanning direction. Figure 2 , Figure 3 As shown, the carriage 17 is equipped with a printing head 18.

[0029] Figure 1 The printing apparatus 10 shown can be implemented by a single printer or by multiple devices that can be connected in a communicative manner.

[0030] In other words, the printing apparatus 10 can also be a printing system 10 in its actual form. The printing system 10 includes, for example, an information processing device that functions as a control unit 11, and a printer that includes a transport unit 16, a carriage 17, a print head 18, and a reading unit 19. With such a printing apparatus 10 or printing system 10, the printing method of this embodiment can be realized.

[0031] Furthermore, the part of the control unit 11 that functions as the printing control unit 12a and the part that functions as the reading control unit 12b and the inspection unit 12c can also be separate information processing devices.

[0032] Figure 2 A portion of the printing apparatus 10 is shown, and it is a specific example of a configuration mainly including a print head 18 and a transport section 16. Figure 2 The upper section within the image shows the specific example from a perspective orthogonal to the transport direction D1 of the printing medium 30. Figure 2 The lower section within the text shows a portion of the specific example from an upward perspective.

[0033] The conveying unit 16 has a feed shaft 22 upstream of the conveying direction and a winding shaft 25 downstream of the conveying direction. The upstream and downstream directions of the conveying direction are simply labeled as upstream and downstream. A long strip of printing medium 30 wound into a roller shape is mounted on the feed shaft 22 and the winding shaft 25 along the conveying direction D1. The printing medium 30 is conveyed in the conveying direction D1. The printing medium 30 can be paper or a medium made of a material other than paper.

[0034] exist Figure 2 In this example, the printing medium 30 wound on the feed shaft 22 is fed downstream by rotating the feed shaft 22 clockwise. A front drive roller 23 is provided downstream of the feed shaft 22, and a rear drive roller 24 is provided upstream of the winding shaft 25. The clockwise rotation of the front drive roller 23 conveys the printing medium 30 fed from the feed section 22 downstream. A clamping roller 23n is provided opposite to the front drive roller 23. The clamping roller 23n abuts against the printing medium 30, thereby clamping the printing medium 30 between the clamping roller 23n and the front drive roller 23.

[0035] The clockwise rotation of the rear drive roller 24 further conveys the printing medium 30, which is being conveyed downstream by the front drive roller 23, downstream. A clamping roller 24n is provided relative to the rear drive roller 24. The printing medium 30 is clamped between the clamping roller 24n and the rear drive roller 24 by abutting against the clamping roller 24n.

[0036] A print head 18 is disposed between the front drive roller 23 and the rear drive roller 24, which ejects ink from above onto the printing medium 30. Figure 2 It is known that the print head 18 is mounted on the carriage 17. The print head 18 is capable of spraying inks of various colors such as cyan (C), magenta (M), yellow (Y), and black (K).

[0037] The printhead 18 has nozzles that open on the nozzle face 20 opposite to the printing medium 30. The printhead 18 may or may not eject ink from the nozzles based on printing data. The ink ejected from the nozzles is called an ink droplet or dot. The printhead 18 may also be called a printing head, inkjet head, liquid printhead, recording head, etc.

[0038] The printed printing medium 30, conveyed by the rear drive roller 24, is wound around the winding shaft 25 via the clockwise rotation of the winding shaft 25.

[0039] The feed shaft 22, winding shaft 25, rollers, and a motor (not shown) for properly rotating these components are specific examples of the transport section 16 for transporting the printing medium 30. The number and arrangement of rollers located along the transport path for transporting the printing medium 30 are not limited to [specific details needed]. Figure 2 The shape shown is correct. Furthermore, the color of the ink ejected from the printhead 18 is not limited to the colors described above. Undoubtedly, a flat pressure roller or similar device can be provided between the front drive roller 23 and the rear drive roller 24 to receive the printing medium 30 ejected from the printhead 18 from below. Additionally, the portion of the printing medium 30 printed using the printhead 18 may not be wound into a roller shape by the winding shaft 25, but rather cut and separated from the printing medium 30 further upstream by a cutter (not shown) and recycled.

[0040] exist Figure 2 In this example, the reading unit 19 is positioned downstream of the carriage 17 and the print head 18, and upstream of the rear drive roller 24. The reading unit 19 optically reads the printing medium 30 that has been printed by the print head 18 using an image sensor and outputs image data as the reading result. Figure 2 In the example, the reading unit 19 has a length that extends in the main scanning direction D2, which intersects the transport direction D1, and is capable of covering the width of the printing medium 30, and reads the printing medium 30 transported by the transport unit 16 in a stationary state.

[0041] Figure 3 The relationship between the printing medium 30 and the print head 18 is simply illustrated from a top-view perspective. The print head 18, mounted on the carriage 17, moves together with the carriage 17 from one end of the main scanning direction D2 towards the other (forward movement) and from the other end towards one end (reverse movement). The main scanning direction D2 intersects the transport direction D1. This intersection can also be understood as orthogonal. Therefore, in Figure 2 The upper section shows the print head 18, etc., from a perspective parallel to the main scanning direction D2. However, due to various errors, such as those in the printer used for production, there are cases where the main scanning direction D2 and the transport direction D1 are not strictly orthogonal. The transport direction is also referred to as the sub-scanning direction.

[0042] exist Figure 3 The image shows an example of the arrangement of nozzles 21 on the nozzle surface 20. Each small circle within the nozzle surface 20 is a nozzle 21. The printhead 18, in a configuration that receives ink of various colors from a liquid holding unit (not shown) called an ink cartridge, ink container, etc., and ejects it from the nozzles 21, has multiple nozzle rows 26. The nozzle row 26 consisting of nozzles 21 ejecting C ink is also referred to as nozzle row 26C. Similarly, sometimes the nozzle row 26 consisting of nozzles 21 ejecting M ink is referred to as nozzle row 26M, the nozzle row 26 consisting of nozzles 21 ejecting Y ink is referred to as nozzle row 26Y, and the nozzle row 26 consisting of nozzles 21 ejecting K ink is referred to as nozzle row 26K. Nozzle rows 26C, 26M, 26Y, and 26K are arranged along the main scanning direction D2.

[0043] Each nozzle array 26 consists of multiple nozzles 21 with a fixed or approximately fixed spacing between them in the conveying direction D1. The direction in which the multiple nozzles 21 constituting the nozzle array 26 are arranged is called the nozzle array direction D3. Figure 3 In the example, the nozzle array direction D3 is parallel to the transport direction D1. In this configuration where the nozzle array direction D3 is parallel to the transport direction D1, the nozzle array direction D3 is orthogonal to the main scanning direction D2. However, it is also possible for the nozzle array direction D3 to be not parallel to the transport direction D1, but rather to intersect the main scanning direction D2 at an angle.

[0044] The nozzle rows 26C, 26M, 26Y, and 26K on the transport direction D1 are positioned in the same direction. The printing apparatus 10 prints an image on the printing medium 30 by combining the transport of the printing medium 30 toward the transport direction D1 with the ink ejection of the print head 18, which accompanies the movement of the carriage 17 along the main scanning direction D2. The action of ink ejection by the print head 18 accompanying the forward and reverse movement of the carriage 17 is called "scanning" or "stroke".

[0045] 2. Test pattern printing:

[0046] The flowchart illustrates the process executed by the control unit 11 according to procedure 12, from the printing of the test pattern (TP) to the inspection of the TP-based nozzle 21. TP is short for Test Pattern. The flowchart roughly consists of TP printing processing (step S100), obtaining the reading results of the printed TP (step S200), and inspection based on the TP reading results (step S300). Step S100 corresponds to the TP printing process. Figure 4 In the diagram, step S100 is further subdivided into steps S110 to S130 for illustration.

[0047] In step S110, the printing control unit 12a acquires TP image data, which represents TP image data, from a storage source such as a memory or storage device that is communicatively connected to the control unit 11. The TP image data is, for example, image data in bitmap form where the color of each pixel is defined by a specified color system. The color system referred to here includes various color systems such as RGB (red, green, blue) and CMYK.

[0048] In step S120, the printing control unit 12a generates printing data for printing the TP based on the TP image data. The printing control unit 12a generates printing data corresponding to each pixel and specifying whether ink is ejected (dotted) or not ejected (no dotted) for each ink color by performing prescribed image processing such as color conversion processing and halftone processing on the TP image data as needed. (See reference...) Figure 3 As explained, when the print head 18 uses inks of the four CMYK colors, in step S120, the print control unit 12a generates print data corresponding to each pixel and specifying dots or no dots for each CMYK color based on the TP image data.

[0049] In step S130, the printing control unit 12a prints TP onto the printing medium 30 based on printing data by controlling the ink ejection from each nozzle 21 of the print head 18.

[0050] In this embodiment, the TP is composed of a "main TP" and a "sub-TP". The sub-TP includes either or both of the "first sub-TP" and the "second sub-TP".

[0051] The main TP is a pattern formed by arranging multiple pattern elements printed by nozzle 21 in a first direction. Specifically, a main TP consisting of N pattern element groups is formed by arranging multiple pattern elements arranged in N cycles in the first direction in a second direction intersecting the first direction, thus offsetting each other. (Refer to...) Figure 2 , 3 Then, the transport direction D1 is equivalent to the first direction, and the main scanning direction D2 is equivalent to the second direction. N is an integer greater than or equal to 3. The main TP can also be understood as the pattern printed in the prior art for the purpose of checking the nozzle 21.

[0052] In step S130, the printing control unit 12a causes the print head 18 to print, as a TP, at least one of a main TP, a first sub-TP disposed in one of two regions sandwiching the main TP in a second direction, and a second sub-TP disposed in the other of the two regions onto the printing medium 30. The first sub-TP is composed of pattern elements printed by the nozzle 21 of the pattern element group (Nth pattern element group) located furthest from the first region in the second direction among the N pattern element groups of the main TP. On the other hand, the second sub-TP is composed of pattern elements printed by the nozzle 21 of the pattern element group (first pattern element group) located furthest from the other region in the second direction among the N pattern element groups of the main TP.

[0053] The printing control unit 12a can complete the printing of TP based on step S130 in one stroke of the print head 18, or it can complete the printing of TP based on step S130 in multiple strokes. In either case, during the period from the start of the initial stroke for printing TP in step S130 to the end of the final stroke, the printing control unit 12a prevents the transport unit 16 from transporting the printing medium 30.

[0054] Figure 5 A portion of nozzle array 26C for printing TP40C, a portion of printing medium 30, and a portion of TP40C printed on printing medium 30 via step S130 are shown. Figure 5 The TP described herein is also referred to as the TP of the "first embodiment". It should be noted that... Figure 5 And the following explanation Figures 6-10 TP is shown for N=3.

[0055] As the print head 18 travels, C ink is ejected from each nozzle 21 of the nozzle array 26C, printing multiple pattern elements 43C. A pattern element 43C is a grid line formed by dots of C ink ejected from a single nozzle 21 within the nozzle array 26C, parallel to the main scanning direction D2. Figure 5 In order to distinguish the nozzles 21 within nozzle row 26C and for ease of explanation, each nozzle 21 is labeled with a nozzle number. Specifically, each nozzle 21 is labeled with nozzle numbers #1, #2, #3… from downstream to upstream. Figure 5Due to space limitations, only 13 nozzles 21 with nozzle numbers #1 to #13 are shown. However, there is no doubt that nozzle array 26C can be composed of more nozzles 21, and each nozzle 21 of nozzle array 26C prints pattern element 43C.

[0056] Ideally, the main TP41C in TP40C is formed by arranging multiple pattern elements 43C printed by each nozzle 21 at intervals corresponding to the nozzle pitch in the transport direction D1. Furthermore, the main TP41C is formed by a first pattern element group 41C1, a second pattern element group 41C2, and a third pattern element group 41C3. The third pattern element group 41C3 corresponds to the Nth pattern element group.

[0057] A pattern element group within the main TP41C consists of multiple pattern elements 43C arranged in three cycles along the transport direction D1. Figure 5 In the example, multiple pattern elements 43C printed by nozzles 21 with nozzle numbers #1, #4, #7, #10, and #13 respectively form a first pattern element group 41C1. Similarly, in Figure 5 In the example, the multiple pattern elements 43C printed by each nozzle 21 with nozzle numbers #2, #5, #8, and #11 respectively form a second pattern element group 41C2, and the multiple pattern elements 43C printed by each nozzle 21 with nozzle numbers #3, #6, #9, and #12 respectively form a third pattern element group 41C3.

[0058] This can also be understood as the multiple pattern elements 43C forming a pattern element group being positioned identically or approximately identically along the main scanning direction D2. Furthermore, the first pattern element group 41C1, the second pattern element group 41C2, and the third pattern element group 41C3 are arranged at staggered positions relative to each other along the main scanning direction D2. In other words, the first pattern element group 41C1, the second pattern element group 41C2, and the third pattern element group 41C3 are arranged in this order along the main scanning direction D2.

[0059] One of the two regions within the printing medium 30 sandwiching the main TP41C along the main scanning direction D2 is designated as the first region 31, and the other region as the second region 32. The first region 31 is adjacent to the first pattern element group 41C1 of the main TP41C, and the second region 32 is adjacent to the third pattern element group 41C3 of the main TP41C. Figure 5 In the example, based on the positional relationship of the first pattern element group 41C1, the second pattern element group 41C2, and the third pattern element group 41C3, the area on the left relative to the main TP41C is the first area 31, and the area on the right relative to the main TP41C is the second area 32.

[0060] according to Figure 5 It is understood that the TP40C involved in the first embodiment has a main TP41C and a second sub-TP42C printed in the second region 32. The second sub-TP42C is composed of pattern elements 43C that are in the same position in the transport direction D1 as the pattern elements 43C of the first pattern element group 41C1, which is farthest from the second region 32 among the three pattern element groups of the main TP41C. The pattern elements 43C that are in the same position in the transport direction D1 as the pattern elements 43C of the first pattern element group 41C1 refer to the pattern elements 43C printed by the nozzle 21 used for printing the first pattern element group 41C1. According to Figure 5 It is understood that each pattern element 43C forming the second sub-TP42C is printed by each nozzle 21 with nozzle numbers #4, #7, #10, and #13 used for printing the first pattern element group 41C1. That is, regarding the first embodiment, the printing control unit 12a prints a pattern in the second region 32 that is substantially the same as the first pattern element group 41C1 printed in each pattern element group of the main TP41C at the position furthest from the second region 32.

[0061] In step S130, undoubtedly, the print head 18 also ejects ink from nozzle rows 26M, 26Y, and 26K, other than nozzle row 26C, and prints TP of each ink color onto the printing medium 30 in the same manner as when printing TP40C with C ink.

[0062] Figure 6 The result of step S130 is shown as a printing medium 30 printed with TP40C, 40M, 40Y, and 40K inks of each color. TP40C is produced by using... Figure 5 As explained, TP41C and the second sub-TP42C are formed by printing C ink through each nozzle 21 of nozzle array 26C. Similarly, TP40M is formed by printing M ink through each nozzle 21 of nozzle array 26M, consisting of a main TP41M and a second sub-TP42M. TP40Y is formed by printing Y ink through each nozzle 21 of nozzle array 26Y, consisting of a main TP41Y and a second sub-TP42Y. TP40K is formed by printing K ink through each nozzle 21 of nozzle array 26K, consisting of a main TP41K and a second sub-TP42K. In other words, the printing data generated in step S120 represents the data of TP for each ink color.

[0063] The specific example of TP involved in this embodiment is not limited to the first embodiment, but can also be any one of the second to fourth embodiments below.

[0064] Figure 7 , 8Figures 9 and 10 respectively show a portion of the nozzle array 26C for printing TP40C, a portion of the printing medium 30, and a portion of TP40C printed on the printing medium 30 by step S130. Figures 7-9 The reading method and Figure 5 The reading method is the same.

[0065] Will Figure 7 The TP described herein is also referred to as the TP of the "second embodiment". Figure 8 The TP described herein is also referred to as the TP of the "Third Embodiment". Figure 9 The TP described herein is also referred to as the TP of the "Fourth Embodiment".

[0066] according to Figure 7 It is understood that the TP40C involved in the second embodiment has a main TP41C and a first sub-TP44C printed in the first region 31. The first sub-TP44C is composed of pattern elements 43C that are in the same position in the transport direction D1 as the pattern elements 43C of the third pattern element group 41C3, which is the furthest from the first region 31 among the three pattern element groups of the main TP41C. The pattern elements 43C that are in the same position in the transport direction D1 as the pattern elements 43C of the third pattern element group 41C3 refer to the pattern elements 43C printed by the nozzle 21 used for printing the third pattern element group 41C3. According to Figure 7 It is understood that each pattern element 43C forming the first sub-TP44C is printed by each nozzle 21 with nozzle numbers #3, #6, #9, and #12 used for printing the third pattern element group 41C3. That is, regarding the second embodiment, the printing control unit 12a prints a pattern in the first region 31 that is substantially the same as the pattern of the third pattern element group 41C3 printed in the pattern element group of the main TP41C at the position furthest from the first region 31.

[0067] according to Figure 8 It is understood that the TP40C involved in the third embodiment has a main TP41C, a first sub-TP44C printed in the first region 31, and a second sub-TP42C printed in the second region 32.

[0068] Thus, according to the first to third embodiments, as a sub-TP printed together with the main TP, either the first sub-TP or the second sub-TP can be printed, or both can be printed.

[0069] Figure 9The TP40C shown in the fourth embodiment can be considered a variation of the third embodiment. A portion of pattern elements 43C from the first sub-TP44C and a portion of pattern elements 43C from the second sub-TP42C are randomly printed in the first region 31 and the second region 32. The pattern elements 43C in the first region 31 and the second region 32 can be considered pattern elements used to compare, with respect to the closest possible distance, pattern elements in the first pattern element group 41C1 and the third pattern element group 41C3, which are consecutively numbered in the main scanning direction D2. In the TP40C of the fourth embodiment, based on the idea that such a comparison can be performed using any one region by simply combining the first region 31 and the second region 32, the number of pattern elements 43C in the first sub-TP44C and the second sub-TP42C is reduced compared to the third embodiment.

[0070] 3. Post-printing processing of the test pattern:

[0071] In step S200, the reading control unit 12b controls the reading unit 19 to read the printing medium 30 on which TP was printed in step S100, and obtains image data, i.e., read image data, as the reading result from the reading unit 19. Undoubtedly, the transport unit 16 performs the transport of the amount required for the reading unit 19 to read the printed printing medium 30.

[0072] exist Figure 6 In the diagram, a reading unit 19 is shown downstream of the printing medium 30. The printing medium 30 is read by the reading unit 19 as it passes below the reading unit 19, which is being transported downstream by the conveying unit 16. Figure 6 In this example, the reading unit 19 is composed of multiple sensor chips 191, 192, 193, and 194 connected in the main scanning direction D2. Each of the multiple sensor chips 191, 192, 193, and 194 has an image sensor and reads a specified range of the transported printing medium 30.

[0073] However, in step S200, it is sufficient for the control unit 11 to obtain the reading result of the printing medium 30 printed with TP. Therefore, it is also possible for the user to have an external scanner read the printing medium 30 printed with TP, and the printing apparatus 10 to obtain the read image data from the scanner via communication IF15.

[0074] In step S300, the inspection unit 12c checks the ink ejection status of the nozzles 21 of the print head 18 based on the image data acquired in step S200. The ink ejection status is divided into normal and abnormal. Abnormality refers to deviations in the landing position of the dots from the ideal position, etc. The inspection unit 12c only needs to detect each pattern element forming the main TP based on the image data, and compare the interval (hereinafter, pattern element spacing) between pattern elements that are in a continuous relationship of nozzle numbers for printing in the transport direction D1 with a predetermined reference value related to the pattern element spacing. The inspection unit 12c only needs to determine that the relevant nozzles 21 with pattern element spacing that are, for example, too narrow or too wide compared to the reference value are abnormal. The inspection unit 12c checks each ink color and each nozzle 21 based on the image data, and saves the inspection results as data.

[0075] However, the inspection unit 12c performs the inspection on the pattern element spacing that should be detected between the pattern element in the Nth pattern element group and the pattern element in the first pattern element group, instead of using the pattern element of one of the pattern elements.

[0076] In other words, whenever a pattern element 43C of the third pattern element group 41C3 of the main TP41C is printed, and a pattern element 43C of the second sub-TP42C corresponding to the next nozzle number of the nozzle number corresponding to that pattern element 43C is printed, the inspection unit 12c can detect the pattern element spacing between these two pattern elements 43C based on the read image data and compare it with a reference value. Furthermore, whenever a pattern element 43C of the first pattern element group 41C1 of the main TP41C is printed, and a pattern element 43C of the first sub-TP44C corresponding to the previous nozzle number of the nozzle number corresponding to that pattern element 43C is printed, the inspection unit 12c can detect the pattern element spacing between these two pattern elements 43C based on the read image data and compare it with a reference value.

[0077] Reference Figure 10 The effectiveness of using the pattern elements of the sub-TP for the check in step S300 is explained.

[0078] Figure 10 A portion of the printing medium 30 on which TP has been printed in step S100 is shown. Figure 10 In the middle, printed with Figure 5 The TP involved in the first embodiment described herein. Furthermore, Figure 10 The printing medium 30 shown is slightly tilted to the right relative to the transport direction D1. This tilting of the printing medium 30 is also called skew. Figure 10For ease of understanding, the nozzle number of the nozzle 21 used for printing is indicated in parentheses for each pattern element 43C. Furthermore, pattern elements printed through nozzle 21 with nozzle number #n are simply referred to as pattern elements with nozzle number #n. n is an integer greater than or equal to 1.

[0079] Here, we will take the case of detecting the spacing between pattern elements 43C of nozzle number #3 and pattern elements 43C of nozzle number #4 as an example for explanation.

[0080] When only the existing TP, i.e., the main TP 41C, is printed, it is necessary to detect the spacing between the pattern element 43C with nozzle number #3 in the third pattern element group 41C3 and the pattern element 43C with nozzle number #4 in the first pattern element group 41C1, based on the read image data. However, when the printing medium 30 printed with the TP is damaged due to, for example, poor transport... Figure 10 When the pattern is read by the reading unit 19 and the like in the offset state shown, it is difficult to accurately detect the spacing between pattern elements that are in such a positional relationship separated in the main scanning direction D2.

[0081] exist Figure 10 In the example, when detecting the pattern element spacing between pattern element 43C with nozzle number #3 in the third pattern element group 41C3 and pattern element 43C with nozzle number #4 in the first pattern element group 41C1, a spacing narrower than the original spacing, i.e., the spacing without offset, was detected. Furthermore, with... Figure 10 Conversely, when the printing medium 30 is shifted to the left relative to the transport direction D1, when the pattern element spacing between the nozzle number #3 pattern element 43C in the third pattern element group 41C3 and the nozzle number #4 pattern element 43C in the first pattern element group 41C1 is detected, a spacing wider than the original pattern element spacing is detected.

[0082] In this embodiment, when detecting the pattern element spacing between pattern element 43C of nozzle number #3 and pattern element 43C of nozzle number #4, the pattern element spacing between pattern element 43C of nozzle number #3 in the third pattern element group 41C3 and pattern element 43C of nozzle number #4 in the second sub-TP42C can be detected based on the read image data. Since pattern element 43C of nozzle number #3 in the third pattern element group 41C3 and pattern element 43C of nozzle number #4 in the second sub-TP42C are adjacent in the main scanning direction D2, even assuming that there is... Figure 10 Even under the shown offset state, the interval detected is approximately the same as the original pattern element spacing. Therefore, the inspection unit 12c can detect the correct pattern element spacing, excluding the influence of the offset, and perform an inspection of the nozzle 21.

[0083] It should be noted that when the printing control unit 12a prints the TP of the third embodiment, the inspection unit 12c can detect the pattern element spacing of common nozzle number combinations (e.g., a combination of nozzle numbers #3 and #4) based on the relationship between the third pattern element group 41C3 and the second sub-TP 42C, and the relationship between the first pattern element group 41C1 and the first sub-TP 44C, respectively, by reading image data. In this case, the inspection unit 12c only needs to take the average of the two values ​​detected as the pattern element spacing between pattern elements 43C involved in the combination of nozzle numbers #3 and #4 as the pattern element spacing between pattern elements 43C involved in the combination of nozzle numbers #3 and #4.

[0084] Furthermore, the inspection unit 12c can also detect the spacing between pattern elements on the acquired image data after performing tilt correction based on image rotation to reduce the influence of offset. Even when such tilt correction is performed, as shown in this embodiment, when detecting the spacing between a portion of the pattern elements using the pattern elements of the first sub-TP and the pattern elements of the second sub-TP, the spacing between pattern elements in the TP printing result can be detected more accurately.

[0085] 4. Summary and Explanation of Results:

[0086] Thus, according to this embodiment, the printing apparatus 10 includes: a print head 18 having a plurality of nozzles 21 for ejecting ink; and a control unit 11 that controls the print head 18 to print a TP (printer unit) onto the printing medium 30 for checking the state of ink ejection from the nozzles 21. The TP has a main TP, which is a main TP in which a plurality of pattern elements printed by the nozzles 21 are arranged in a first direction, and is composed of N pattern element groups arranged in a first direction at N periods, which are staggered from each other in a second direction intersecting the first direction. Here, N is an integer of 3 or more.

[0087] Furthermore, the control unit 11 causes the print head 18 to print, as a TP, at least one of a main TP, a first sub-TP disposed in one of two regions sandwiching the main TP in a second direction, and a second sub-TP disposed in the other of the two regions onto the printing medium 30. The first sub-TP is composed of pattern elements printed by a nozzle 21 that prints pattern elements of the pattern element group located furthest from one of the N pattern element groups in the second direction. The second sub-TP is composed of pattern elements printed by a nozzle 21 that prints pattern elements of the pattern element group located furthest from the other of the N pattern element groups in the second direction.

[0088] According to the aforementioned configuration, the control unit 11 serves as at least one of the main TP, the first sub-TP, and the second sub-TP that the TP prints onto the printing medium 30. This allows for a TP that, even when reading is performed while the printing medium 30 is offset, eliminates inaccuracies in pattern element spacing detection caused by the offset, thereby appropriately performing nozzle 21 checks.

[0089] According to this embodiment, the first direction is the transport direction D1 of the printing medium 30, and the printing apparatus 10 may also have a reading unit 19 for reading the printing medium 30 printed with TP at a position further downstream of the print head 18 in the transport direction D1. Furthermore, Figure 6 In the example, the reading unit 19 has multiple sensor chips with image sensors for reading.

[0090] In addition, at least one of the main TP, the first sub-TP, and the second sub-TP constituting the TP can also be configured at a location that can be read by a common sensor chip.

[0091] exist Figure 6 In the example, a TP40C consisting of a main TP41C and a second sub-TP42C is printed at the position read by the sensor chip 191 on the printing medium 30. Furthermore, in Figure 6 In the example, TP40M is printed at the position read by sensor chip 192, TP40Y is printed at the position read by sensor chip 193, and TP40K is printed at the position read by sensor chip 194 on the printing medium 30. Due to the inherent output characteristics of each sensor chip and deviations in their respective positions, the reading values ​​output by each sensor chip may also show deviations in color and position. For example... Figure 6 As shown in the example, since the main TP and sub-TP that make up the TP have a positional relationship that is read by a common sensor chip, the reading values ​​of the main TP and the sub-TP will not produce various deviations caused by the difference in sensor chips. The detection accuracy of the pattern element spacing based on the reading values ​​of the main TP and the sub-TP is improved.

[0092] This embodiment also discloses various types of inventions, such as methods and procedures 12, in addition to printing apparatus 10 and printing system 10.

[0093] The printing method includes a printing step of printing a TP (printing head) for checking the state of ink ejection from the nozzles 21 onto a printing medium 30 by controlling a print head 18 having multiple nozzles 21 that eject ink. The TP has a main TP, which is a main TP in which multiple pattern elements printed by the nozzles 21 are arranged in a first direction, and is composed of N pattern element groups arranged in a pattern element group with multiple pattern elements arranged in a pattern element group at N periods in the first direction, which are staggered from each other in a second direction intersecting the first direction. Here, N is an integer greater than or equal to 3.

[0094] Furthermore, the printing process involves the print head 18 printing a main TP onto the printing medium 30, as a TP, and at least one of a first sub-TP disposed in one of two regions sandwiching the main TP in a second direction, and a second sub-TP disposed in the other of the two regions. The first sub-TP is composed of pattern elements printed by a nozzle 21 that prints pattern elements of the pattern element group located furthest from one of the N pattern element groups in the second direction. The second sub-TP is composed of pattern elements printed by a nozzle 21 that prints pattern elements of the pattern element group located furthest from the other of the N pattern element groups in the second direction.

[0095] 5. Other implementation methods:

[0096] Other methods included in this embodiment will be described.

[0097] Of course, printing medium 30 may not be... Figure 2 Continuous paper wound into a roll, as shown. The printing medium 30 may also be single sheets of paper cut into sheets.

[0098] Furthermore, N can also be an integer greater than 3. The larger N is, that is, the more pattern element groups that constitute the main TP, the greater the drawback of pattern element spacing detection caused by the offset through the existing TP configuration. Therefore, it can be said that this embodiment becomes more useful.

[0099] The printing apparatus 10 may also be a serial inkjet printer that does not have the print head 18 mounted on a carriage 17 that moves in the main scanning direction D2, as previously described.

[0100] A so-called line inkjet printer, as described below, can also be conceived: ink is ejected by a printhead 18 having a nozzle array 26 corresponding to each ink color, extending in a main scanning direction D2 that intersects the transport direction D1, and whose length is sufficient to cover the width of the printing medium 30. In a line inkjet printer, the nozzle array direction D3 can also be understood as being parallel to the main scanning direction D2, not the transport direction D1. If this embodiment is described assuming that the printing apparatus 10 is a line inkjet printer, then TP is printed on the printing medium 30 in a direction where each pattern element, which serves as a grid, is parallel to the transport direction D1, not the main scanning direction D2. That is, the main scanning direction D2 can also be considered as the first direction, and the transport direction D1 as the second direction.

[0101] The reading unit 19 does not need to be positioned downstream of the printing medium 30, but can be positioned upstream of the printing medium 30.

[0102] The reading unit 19 does not need to be a fixed line scan; for example, it can be a moving serial scan in which the reading unit 19 moves along the main scan direction D2 to read data.

[0103] A pattern element 43C does not need to be a grid line; it can also be a dot.

Claims

1. A printing apparatus, characterized in that, have: The printhead has multiple nozzles that eject ink; The control unit, by controlling the print head, prints a test pattern onto the printing medium to check the state of ink ejection from the nozzles. N is an integer greater than or equal to 3. The test pattern has the following characteristics: The main test pattern is a stepped main test pattern in which multiple pattern elements printed by the nozzle are arranged in a first direction. It is also the main test pattern composed of N pattern element groups arranged in a second direction that intersects the first direction and are staggered from each other. The pattern element groups are formed by arranging multiple pattern elements printed by the nozzle at intervals of the nozzle spacing in the first direction. as well as At least one of a first sub-test pattern disposed in one of two regions sandwiching the main test pattern in the second direction and a second sub-test pattern disposed in the other of the two regions. The first sub-test pattern is composed of pattern elements printed by a nozzle that prints the pattern element group located furthest from the region in the second direction among N pattern element groups. The second sub-test pattern is composed of pattern elements printed by a nozzle that prints the pattern elements of the pattern element group located furthest from the other region in the second direction among the N pattern element groups.

2. The printing apparatus according to claim 1, characterized in that, The first direction is the transport direction of the printing medium. A reading section is provided at a position further downstream of the print head in the conveying direction to read the printing medium on which the test pattern is printed. The reading unit has multiple sensor chips, each of which has an image sensor for reading. At least one of the main test pattern, the first sub-test pattern, and the second sub-test pattern constituting the test pattern is configured at a position that can be read by a common sensor chip.

3. A printing method, characterized in that, have: In the printing process, a test pattern is printed onto the printing medium by controlling a print head with multiple nozzles that eject ink, used to check the state of ink ejection from the nozzles. N is an integer greater than or equal to 3. The test pattern has the following characteristics: The main test pattern is a stepped main test pattern in which multiple pattern elements printed by the nozzle are arranged in a first direction. It is also the main test pattern composed of N pattern element groups arranged in a second direction that intersects the first direction and are staggered from each other. The pattern element groups are formed by arranging multiple pattern elements printed by the nozzle at intervals of the nozzle spacing in the first direction. as well as At least one of a first sub-test pattern disposed in one of two regions sandwiching the main test pattern in the second direction and a second sub-test pattern disposed in the other of the two regions. The first sub-test pattern is composed of pattern elements printed by a nozzle that prints the pattern element group located furthest from the region in the second direction among N pattern element groups. The second sub-test pattern is composed of pattern elements printed by a nozzle that prints the pattern elements of the pattern element group located furthest from the other region in the second direction among the N pattern element groups.

Images