Printing device and printing method

Abstract

To provide a test pattern suitable for detecting a sudden distortion occurring in image data as a result of reading.SOLUTION: A printer includes: a conveyance unit; a print head having a plurality of nozzles for ejecting ink; and a control unit that prints on a printing medium a test pattern for inspecting a state of ink ejection by a nozzle. The test pattern has a first pattern element group in which a plurality of pattern elements to be printed by the nozzle are arranged in a conveying direction and a second pattern element group in which a plurality of pattern elements to be printed by the nozzle are arranged in the conveying direction. The control unit causes the conveyance unit to convey, by a distance equal to or larger than a nozzle pitch, the printing medium with the first pattern element group printed thereon by causing ejection of ink by the plurality of nozzles and thereafter prints a second pattern element group on the printing medium by causing ejection of ink by the plurality of nozzles used for printing the first pattern element group.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a printing apparatus and a printing method. [Background technology]

[0002] A technology has been disclosed for an inkjet printing device in which a test pattern is recorded on printing paper using a recording head, the test pattern is read by a scanner, the read data is interpolated, and nozzle abnormalities are determined based on the read data after the interpolation process (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-54970 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a scanner reads a print medium on which a test pattern is printed, sudden vibrations or external forces can cause distortions such as expansion and contraction in part of the read data of the test pattern. It is difficult to check whether printing by each nozzle was normal from the part of the read data where such distortion occurs. Therefore, a test pattern that makes it easy to detect distortions in the read data as described above is needed. [Means for solving the problem]

[0005] The printing device includes a transport unit that transports a printing medium in a transport direction, a print head having a plurality of nozzles that eject ink, and a control unit that controls the transport unit and the print head to print a test pattern onto the printing medium for inspecting the state of ink ejection by the nozzles, wherein the test pattern has a first pattern element group in which pattern elements printed by the nozzles are arranged in the transport direction, and a second pattern element group in which pattern elements printed by the nozzles are arranged in the transport direction, and the control unit transports the printing medium on which the first pattern element group has been printed by ejecting the ink from the plurality of nozzles by a distance equal to or greater than a nozzle pitch, which is the spacing between the nozzles in the transport direction, to the transport unit, and then prints the second pattern element group onto the printing medium by ejecting the ink from the plurality of nozzles used for printing the first pattern element group.

[0006] The printing method includes a printing step of printing a test pattern onto a printing medium using a print head having a plurality of nozzles that eject ink, the test pattern having a first pattern element group in which pattern elements printed by the nozzles are arranged in a transport direction of the printing medium, and a second pattern element group in which pattern elements printed by the nozzles are arranged in the transport direction, and in the printing step, the printing medium on which the first pattern element group has been printed by ejecting the ink from the plurality of nozzles is transported a distance equal to or greater than a nozzle pitch, which is the spacing between the nozzles in the transport direction, and the second pattern element group is printed onto the printing medium by ejecting the ink from the plurality of nozzles used for printing the first pattern element group. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing a simplified device configuration. [Diagram 2] FIG. 2 is a diagram showing a specific example of a configuration including a print head and a transport unit. [Diagram 3]FIG. 4 is a diagram showing the relationship between the print medium and the print head from an above perspective. [Figure 4] 11 is a flowchart showing the flow from TP printing to nozzle inspection. [Diagram 5] FIG. 13 is a diagram showing how a TP is printed on a print medium in steps S130 to S150. [Figure 6] FIG. 4 is a diagram showing a printing medium on which TPs for each ink color are printed. [Figure 7] FIG. 4 is a diagram showing a part of read image data. [Figure 8] FIG. 13 is a diagram showing a TP according to another example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that each drawing is merely an example for explaining the present embodiment. Since each drawing is an example, the proportions and shapes may not be accurate, the drawings may not match each other, and some parts may be omitted.

[0009] 1.Device configuration: FIG. 1 shows a simplified configuration of a printing device 10 according to this embodiment. The printer 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a communication IF 15, a transport unit 16, a carriage 17, a print head 18, a reading unit 19, etc. IF stands for interface. The control unit 11 includes one or more ICs having a CPU 11a as a processor, a ROM 11b, a RAM 11c, etc., and other non-volatile memories, etc.

[0010] In the control unit 11, a processor, i.e., a CPU 11a, executes arithmetic processing according to one or more programs 12 stored in a ROM 11b or other memory, using a RAM 11c or the like as a work area, thereby realizing various functions such as a print control unit 12a, a read control unit 12b, an inspection unit 12c, etc. The processor is not limited to one CPU, and may be configured to perform processing using multiple CPUs or a hardware circuit such as an ASIC, or may be configured to perform processing in cooperation with a CPU and a hardware circuit.

[0011] The display unit 13 is a means for displaying visual information, and is configured, for example, by a liquid crystal display, an organic EL display, or the like. The display unit 13 may be configured to include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving operations by a user, and is realized, for example, by a physical button, a touch panel, a mouse, a keyboard, or the like. Of course, the touch panel may be realized as one function of the display unit 13.

[0012] The display unit 13 and the operation reception unit 14 may be part of the configuration of the printing device 10, or may be external peripheral devices attached to the printing device 10. The communication IF 15 is a general term for one or more IFs for connecting the printing device 10 to the outside world via wired or wireless communication in compliance with a predetermined communication protocol including a known communication standard.

[0013] The transport unit 16 is a means for transporting the print medium, and includes rollers and a motor for rotating the rollers. The print head 18 performs printing by ejecting ink from nozzles onto the print medium using an inkjet method. The reading unit 19 is a means for reading the print results on the print medium. The reading unit 19 is also called a scanner. However, the printing device 10 may have a configuration that does not include the reading unit 19.

[0014] The carriage 17 is a mechanism that can move back and forth along a predetermined direction by receiving power from a carriage motor (not shown). The predetermined direction in which the carriage 17 moves is also called the main scanning direction. The carriage 17 carries a print head 18 as shown in Figures 2 and 3.

[0015] The configuration of the printing device 10 shown in FIG. 1 may be realized by a single printer, or may be realized by a plurality of devices connected so as to be able to communicate with each other. That is, the printing device 10 may actually be a printing system 10. 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 further a reading unit 19. The printing method of the present embodiment is realized by such a printing device 10 or printing system 10. Furthermore, the part of the control unit 11 that functions as the print control unit 12a and the parts that function as the read control unit 12b and the inspection unit 12c may be separate information processing devices.

[0016] Fig. 2 shows a specific example of a configuration of part of the printing device 10, mainly including the print head 18 and the transport unit 16. The upper part of Fig. 2 shows the specific example from a perspective perpendicular to the transport direction D2 of the print medium 30, and the lower part of Fig. 2 shows a part of the specific example from a perspective from above. The transport unit 16 includes a pay-out spindle 22 on the upstream side of the transport and a take-up spindle 25 on the downstream side of the transport. The upstream and downstream sides of the transport are simply referred to as upstream and downstream. A long print medium 30 wound in a roll around the pay-out spindle 22 and the take-up spindle 25 is stretched along the transport direction D2. The print medium 30 is transported in the transport direction D2. The print medium 30 may be paper, or may be a medium made of a material other than paper.

[0017] In the example of Fig. 2, the printing medium 30 wound around the payout spindle 22 is paid out downstream as the payout spindle 22 rotates clockwise. A front drive roller 23 is provided downstream of the payout spindle 22, and a rear drive roller 24 is provided upstream of the take-up spindle 25. The front drive roller 23 rotates clockwise to transport the printing medium 30 paid out from the payout section 22 downstream. A nip roller 23n is provided for the front drive roller 23. The nip roller 23n comes into contact with the printing medium 30, thereby sandwiching the printing medium 30 between itself and the front drive roller 23.

[0018] The rear drive roller 24 rotates in the clockwise direction, thereby transporting the print medium 30 transported downstream by the front drive roller 23 further downstream. A nip roller 24n is provided for the rear drive roller 24. The nip roller 24n comes into contact with the print medium 30, thereby sandwiching the print medium 30 between itself and the rear drive roller 24.

[0019] A print head 18 that ejects ink from above onto the print medium 30 is disposed between the front drive roller 23 and the rear drive roller 24. As can be seen from Fig. 2, the print head 18 is mounted on a carriage 17. The print head 18 is capable of ejecting ink of multiple colors, such as cyan (C), magenta (M), yellow (Y), and black (K).

[0020] Each nozzle of the print head 18 opens to a nozzle face 20 that faces the print medium 30 of the print head 18, and the print head 18 ejects or does not eject ink from the nozzles based on the print data. The ink ejected from the nozzles is called an ink droplet or a dot. The print head 18 may also be called a print head, an inkjet head, a liquid ejection head, a recording head, etc.

[0021] As the winding shaft 25 rotates in the clockwise direction, the printed print medium 30 transported by the rear drive roller 24 is wound onto the winding shaft 25 . The payout shaft 22, the winding shaft 25, the rollers, and a motor (not shown) for rotating them appropriately are specific examples of the transport unit 16 that transports the print medium 30. The number and arrangement of rollers provided along the transport path for transporting the print medium 30 are not limited to the embodiment shown in FIG. 2. The color of the ink ejected by the print head 18 is not limited to the above-mentioned color. Needless to say, a flat platen or the like may be provided between the front drive roller 23 and the rear drive roller 24 to support the print medium 30 from below, which receives the ink ejected from the print head 18. The portion of the print medium 30 on which printing has been performed by the print head 18 may be cut off from the print medium 30 upstream of that portion by a cutter (not shown) and collected, instead of being wound into a roll by the winding shaft 25.

[0022] 2, the reading unit 19 is provided at a position 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 print medium 30 printed by the print head 18 using an image sensor, and outputs image data as the reading result. In the example of FIG. 2, the reading unit 19 extends in the main scanning direction D1 intersecting the transport direction D2 and has a length sufficient to cover the width of the print medium 30, and reads the print medium 30 transported by the transport unit 16 in a stationary state.

[0023] FIG. 3 shows a simplified view of the relationship between the print medium 30 and the print head 18 from above. The print head 18 mounted on the carriage 17 moves together with the carriage 17 from one end to the other end in the main scanning direction D1 (forward movement) and from the other end to one end (return movement). The main scanning direction D1 and the transport direction D2 intersect. This intersection may be interpreted as being perpendicular. Therefore, in the upper part of FIG. 2, the print head 18 and the like are shown from a perspective parallel to the main scanning direction D1. However, for example, due to various errors in the printer as a product, the main scanning direction D1 and the transport direction D2 may not be strictly perpendicular. The transport direction is also called the sub-scanning direction.

[0024] FIG. 3 shows an example of the arrangement of nozzles 21 on the nozzle surface 20. Each small circle in the nozzle surface 20 is a nozzle 21. The print head 18 has a plurality of nozzle rows 26 in a configuration in which ink of each color is supplied from a liquid holding means (not shown) called an ink cartridge or ink tank and ejected from the nozzles 21. The nozzle row 26 consisting of nozzles 21 ejecting C ink is also referred to as nozzle row 26C. Similarly, the nozzle row 26 consisting of nozzles 21 ejecting M ink is sometimes referred to as nozzle row 26M, the nozzle row 26 consisting of nozzles 21 ejecting Y ink is sometimes referred to as nozzle row 26Y, and the nozzle row 26 consisting of nozzles 21 ejecting K ink is sometimes referred to as nozzle row 26K. The nozzle rows 26C, 26M, 26Y, and 26K are aligned along the main scanning direction D1.

[0025] Each nozzle row 26 is composed of a plurality of nozzles 21 with a constant or nearly constant nozzle pitch, which is the distance between the nozzles 21 in the transport direction D2. The direction in which the plurality of nozzles 21 constituting the nozzle row 26 are arranged is called the nozzle row direction D3. In the example of FIG. 3, the nozzle row direction D3 is parallel to the transport direction D2. In a configuration in which the nozzle row direction D3 is parallel to the transport direction D2, the nozzle row direction D3 and the main scanning direction D1 are perpendicular to each other. However, the nozzle row direction D3 may not be parallel to the transport direction D2 and may be configured to obliquely intersect with the main scanning direction D1.

[0026] The positions of the nozzle rows 26C, 26M, 26Y, and 26K in the transport direction D2 are aligned with one another. The printing device 10 prints an image on the printing medium 30 by combining the transport of the printing medium 30 in the transport direction D2 with the ejection of ink by the print head 18 accompanying the movement of the carriage 17 along the main scanning direction D1. The operation of the print head 18 ejecting ink as the carriage 17 moves forward and backward is called a "scan" or "pass."

[0027] 2. Test pattern printing: FIG. 4 is a flowchart showing the flow of steps executed by the control unit 11 in accordance with the program 12, from printing the TP to inspecting the nozzles 21 based on the TP. TP is an abbreviation for test pattern. The flowchart roughly includes a TP printing process (step S100), obtaining a reading result of the printed TP (step S200), detecting sudden misalignment based on the reading result of the TP (step S300), and inspecting the nozzles 21 based on the reading result of the TP (step S400). Step S100 corresponds to the printing process of the TP. In FIG. 4, step S100 is shown in detail, divided into steps S110 to S150.

[0028] In step S110, the print control unit 12a acquires TP image data, which is image data expressing the TP, from a storage source such as a predetermined memory or storage device with which the control unit 11 can communicate. The TP image data is, for example, image data in a bitmap format that defines the color of each pixel in a predetermined color system. The color system referred to here can be, for example, the RGB (red, green, blue) color system, the CMYK color system, or various other systems.

[0029] In step S120, the print control unit 12a generates print data for printing the TP from the TP image data. The print control unit 12a performs predetermined image processing, such as color conversion processing and halftone processing, on the TP image data as necessary to generate print data that specifies ink ejection (dot on) or ink non-ejection (dot off) for each pixel and for each ink color. As described with reference to FIG. 3, assuming that the print head 18 uses four colors of ink, CMYK, in step S120, the print control unit 12a generates print data that specifies dot on / off for each pixel and for each CMYK based on the TP image data.

[0030] The TP of this embodiment has a "first pattern element group" in which a plurality of "pattern elements" printed by the nozzles 21 are arranged in the transport direction D2, and a "second pattern element group" in which a plurality of such pattern elements are arranged in the transport direction D2. One pattern element is printed by one nozzle 21. Furthermore, the first pattern element group and the second pattern element group are printed on the print medium 30 in a positional relationship in which they are shifted by a distance equal to or greater than the nozzle pitch in the transport direction D2. Steps S130 to S150 will be specifically described with reference to FIG.

[0031] FIG. 5 shows how the TP is printed on the print medium 30 through steps S130 to S150. In step S130, the print control unit 12a controls the movement of the carriage 17 along the main scanning direction D1 and the ink ejection by the print head 18 to print the first pattern element group on the print medium 30 based on the print data. On the left side of FIG. 5, a part of the nozzle row 26C used to print the first pattern element group 41C and a part of the print medium 30 are shown, and further, a state in which the first pattern element group 41C has been printed on the print medium 30 by step S130 is shown. By passing the print head 18, C ink is ejected from each nozzle 21 of the nozzle row 26C to print a plurality of pattern elements 51C. The first pattern element group 41C is configured by arranging a plurality of pattern elements 51C in the transport direction D2.

[0032] One pattern element 51C is a ruled line parallel to the main scanning direction D1, formed by dots of C ink discharged by one nozzle 21 in the nozzle row 26C. In FIG. 5, the symbol "P" indicates the nozzle pitch. That is, the multiple pattern elements 51C are ideally printed side by side at the same interval as the nozzle pitch P in the transport direction D2. Also, in FIG. 5, in order to distinguish the nozzles 21 in the nozzle row 26C, a nozzle number is assigned to each nozzle 21 for convenience. Specifically, the nozzles 21 are numbered in order from downstream to upstream, such as nozzle numbers #1, #2, #3, .... In FIG. 5, five nozzles 21 with nozzle numbers #1 to #5 are shown due to space limitations, but the nozzle row 26C is naturally composed of more nozzles 21, and each nozzle 21 in the nozzle row 26C prints the pattern element 51C. The pattern elements 51C constituting the first pattern element group 41C may be called "first pattern elements".

[0033] After printing the first pattern element group in step S130, in step S140, the print control unit 12a controls the transport unit 16 to transport the print medium 30 by a predetermined shift amount. Here, the predetermined shift amount is set to a distance twice the nozzle pitch P. In other words, the print medium 30 is transported downstream by a distance of nozzle pitch P×2. As a result of this transport, as can be seen from FIG. 5, the pattern element 51C printed by the nozzle 21 with nozzle number #3 in step S130 coincides or nearly coincides with the position of the nozzle 21 with nozzle number #1 in the transport direction D2.

[0034] After step S140, in step S150, the print control unit 12a prints the second pattern element group on the print medium 30 based on the print data by controlling the movement of the carriage 17 along the main scanning direction D1 and the ink ejection by the print head 18. On the right side of FIG. 5, a part of the nozzle row 26C used for printing the second pattern element group 42C and a part of the print medium 30 are shown, and further, a state in which the second pattern element group 42C is printed on the print medium 30 by step S150 is shown. That is, after the first pattern element group 41C is printed by the nozzle row 26C, the second pattern element group 42C is printed by the same nozzle row 26C after a predetermined shift amount of transport. C ink is ejected from each nozzle 21 of the nozzle row 26C by the pass of the print head 18, and a plurality of pattern elements 52C are printed. The second pattern element group 42C is configured by arranging a plurality of pattern elements 52C in the transport direction D2.

[0035] Like pattern element 51C, pattern element 52C is a ruled line parallel to main scanning direction D1 formed by dots of C ink ejected by one nozzle 21 in nozzle row 26C. Similar to the relationship between pattern elements 51C, multiple pattern elements 52C are ideally printed side by side at intervals equal to the nozzle pitch P in transport direction D2. Pattern elements 52C constituting second pattern element group 42C may be referred to as "second pattern elements." As a result of printing the second pattern element group 42C by step S150, as can be seen from FIG. 5, the pattern element 52C printed by nozzle 21 with nozzle number #1 is in the same or nearly the same position in the transport direction D2 as the pattern element 51C printed by nozzle 21 with nozzle number #3 in step S130.

[0036] As described above, a TP having the first pattern element group and the second pattern element group is printed on the printing medium 30. Naturally, the nozzle rows 26M, 26Y, and 26K other than the nozzle row 26C also print the first pattern element group in step S130 and print the second pattern element group in step S150.

[0037] 6 shows the printing medium 30 on which TP40C, 40M, 40Y, and 40K for each ink color are printed as a result of step S100. TP40C is composed of the first pattern element group 41C and the second pattern element group 42C printed by each nozzle 21 of the nozzle row 26C ejecting C ink as described with reference to FIG. 5. Similarly, TP40M is composed of the first pattern element group 41M and the second pattern element group 42M printed by each nozzle 21 of the nozzle row 26M ejecting M ink. TP40Y is composed of the first pattern element group 41Y and the second pattern element group 42Y printed by each nozzle 21 of the nozzle row 26Y ejecting Y ink. TP40K is composed of the first pattern element group 41K and the second pattern element group 42K printed by each nozzle 21 of the nozzle row 26K ejecting K ink.

[0038] That is, in step S130, first pattern element group 41C, first pattern element group 41M, first pattern element group 41Y, and first pattern element group 41K are printed by a pass of print head 18. Then, after the transport of step S140, in step S150, second pattern element group 42C, second pattern element group 42M, second pattern element group 42Y, and second pattern element group 42K are printed by a pass of print head 18.

[0039] 5 and 6, the first pattern element group and the second pattern element group constituting one TP, that is, the TP of one ink color, are arranged in adjacent positions in the main scanning direction D1. For example, in the main scanning direction D1, no TPs of other inks are printed between the first pattern element group 41C and the second pattern element group 42C of C ink.

[0040] 3. After printing the test pattern: In step S200, the reading control unit 12b controls the reading unit 19 to read the print medium 30 after the TP is printed in step S100, and obtains read image data, which is image data as the reading result, from the reading unit 19. Of course, the transport unit 16 transports the print medium 30 after printing by an amount necessary for the reading unit 19 to read it.

[0041] Fig. 6 shows the reading unit 19 downstream of the print medium 30. When the print medium 30 transported downstream by the transport unit 16 passes below the reading unit 19, the print medium 30 is read by the reading unit 19. In the example of Fig. 6, the reading unit 19 is configured with multiple sensor chips 191, 192, 193, and 194 arranged in series in the main scanning direction D1. Each of the multiple sensor chips 191, 192, 193, and 194 has an image sensor and reads a predetermined range of the print medium 30 being transported.

[0042] However, in step S200, it is sufficient for the control unit 11 to obtain the result of reading the print medium 30 on which the TP is printed. Therefore, the user may have an external scanner read the print medium 30 on which the TP is printed, and the printing device 10 may obtain the read image data from the scanner via the communication IF 15.

[0043] In step S300, the inspection unit 12c detects "sudden misalignment" based on the read image data acquired in step S200. The sudden misalignment is a distortion such as expansion and contraction that occurs in a part of the read image data due to sudden vibration or external force occurring to the print medium 30 or the reading unit 19 when the print medium 30 on which the TP is printed is read by the reading unit 19 or the scanner. The sudden vibration or external force may occur, for example, when the user touches the printing device 10 or the scanner or walks near them during the reading period of the print medium 30, or due to the shape of the conveying path of the print medium 30. Step S300 is executed so that the sudden misalignment is not confused with the positional misalignment of the pattern elements caused by an abnormality in the nozzle 21 in the inspection in the later step S400.

[0044] Fig. 7 shows a portion of the read image data 60 acquired in step S200. Fig. 7 shows a portion of the read result of TP of a certain ink color. Specifically, symbols 51a and 52a are images as the read result of pattern elements printed on the print medium 30, and these are called pattern element images 51a and 52a. For example, the multiple pattern element images 51a are the read result of multiple pattern elements 51C constituting the first pattern element group 41C shown in Fig. 5, and the multiple pattern element images 52a are the read result of multiple pattern elements 52C constituting the second pattern element group 42C.

[0045] The inspection unit 12c detects sudden misalignment by evaluating the differences between a plurality of pattern element images 51a, which are images of a first pattern element group, and a plurality of pattern element images 52a, which are images of a second pattern element group, in the read image data 60. A specific example of a method for detecting a sudden deviation will be described below.

[0046] The inspection unit 12c obtains the amount of deviation ΔP(n) and the amount of deviation ΔP(nN) as follows. ΔP(n)=P(n)-P(n)´ ΔP(nN)=P(nN)-P(nN)´ The amount of deviation ΔP(n) and the amount of deviation ΔP(nN) correspond to the difference between the pattern element image 51a and the pattern element image 52a.

[0047] In each formula, n is an integer equal to or greater than 1. P(n) is the n-th "pattern element pitch" counting from the downstream side in the read result of the first pattern element group. The pattern element pitch in the read result of the first pattern element group is the interval between the pattern element images 51a in the transport direction D2. In FIG. 7, the nozzle numbers are given in parentheses to each of the pattern element images 51a and 52a. This indicates which nozzle 21 printed the read pattern element for each of the pattern element images 51a and 52a. In this embodiment, for the first pattern element group, the interval between the pattern element image 51a of the pattern element printed by the nozzle 21 with nozzle number #n and the pattern element image 51a of the pattern element printed by the nozzle 21 with nozzle number #n+1 is set to P(n). Therefore, for example, the interval between the pattern element image 51a of the pattern element 51C printed by the nozzle 21 with nozzle number #3 and the pattern element image 51a of the pattern element 51C printed by the nozzle 21 with nozzle number #4 is the pattern element pitch P3. Figure 7 shows examples of pattern element pitches P1, P2, P3, and P4.

[0048] P(n)' is the n-th pattern element pitch counting from the downstream side in the read result of the second pattern element group. The pattern element pitch in the read result of the second pattern element group is the interval between the pattern element images 52a in the transport direction D2. In this embodiment, for the second pattern element group, the interval between the pattern element image 52a of the pattern element printed by the nozzle 21 with nozzle number #n and the pattern element image 52a of the pattern element printed by the nozzle 21 with nozzle number #n+1 is P(n)'. For example, the interval between the pattern element image 52a of the pattern element 52C printed by the nozzle 21 with nozzle number #3 and the pattern element image 52a of the pattern element 52C printed by the nozzle 21 with nozzle number #4 is the pattern element pitch P3'. FIG. 7 illustrates pattern element pitches P1', P2', P3', and P4'. The deviation amount ΔP(n) is the difference between such pattern element pitch P(n) and pattern element pitch P(n)'.

[0049] Similarly, P(nN) is the nNth pattern element pitch, counting from the downstream side, in the read result of the first pattern element group, and P(nN)' is the nNth pattern element pitch, counting from the downstream side, in the read result of the second pattern element group. N is a numerical value corresponding to the predetermined shift amount adopted in step S140. The unit of the predetermined shift amount is the nozzle pitch P, and as described above, the predetermined shift amount is the nozzle pitch P×2, so here, N=2. Therefore, the pattern element pitch P(n) and the pattern element pitch P(nN)' have a relationship in which they share a common position in the transport direction D2 in the read image data 60, like, for example, the pattern element pitch P3 and the pattern element pitch P1'. The deviation amount ΔP(nN) is the difference between such pattern element pitch P(nN) and pattern element pitch P(nN)′.

[0050] Because the pattern element pitch P(n) and the pattern element pitch P(n)' are the distance between pattern elements printed by the same combination of two nozzles 21, ideally, that is, if there is no sudden misalignment, the misalignment amount ΔP(n) is 0. Similarly, because the pattern element pitch P(nN) and the pattern element pitch P(nN)' are the distance between pattern elements printed by the same combination of two nozzles 21, ideally, the misalignment amount ΔP(nN) is 0. Furthermore, the pattern element pitch P(n) and the pattern element pitch P(nN)' are in a relationship in which they have a common position in the transport direction D2, and therefore may similarly include sudden deviations.

[0051] Therefore, the inspection unit 12c determines that there is an accidental deviation in the pattern element pitch P(n) and the pattern element pitch P(nN)' when all of the following conditions 1 to 3 are met. Condition 1: The sign of ΔP(n) is opposite to the sign of ΔP(nN). Condition 2: The absolute value of ΔP(n)+ΔP(nN) is smaller than a predetermined first threshold value. Condition 3: The absolute value of ΔP(n) and the absolute value of ΔP(nN) are both greater than a predetermined second threshold value, where the first threshold value is smaller than the second threshold value.

[0052] For example, when n=3, the sign of ΔP3=P3-P3' is positive and the sign of ΔP1=P1-P1' is negative, so condition 1 is satisfied. Furthermore, if the absolute value of (P3-P3')+(P1-P1') is smaller than the first threshold value and the absolute values ​​of (P3-P3') and (P1-P1') are each greater than the second threshold value, then conditions 2 and 3 are also satisfied. When conditions 1 to 3 are satisfied with n=3, inspection unit 12c determines that there is an accidental deviation in pattern element pitch P3 and pattern element pitch P1'.

[0053] 5 and 7, after pattern element 51C printed by nozzle 21 with nozzle number #3 and pattern element 52C printed by nozzle 21 with nozzle number #1 are simultaneously read, it takes longer than necessary to read pattern element 51C printed by nozzle 21 with nozzle number #4 and pattern element 52C printed by nozzle 21 with nozzle number #2, and pattern element pitch P3 and pattern element pitch P1', which are part of read image data 60, are elongated in transport direction D2. Such elongation is a type of sudden deviation.

[0054] In step S400, the inspection unit 12c inspects the state of ink ejection by the nozzles 21 of the print head 18 based on the read image data acquired in step S200 and the result of the detection of the sudden deviation in step S300. The state of ink ejection is classified as normal or abnormal. Abnormality refers to a landing position deviation in which the landing position of a dot is deviated from an ideal position. The inspection unit 12c compares each pattern element pitch in the read image data with a predetermined reference value for the pattern element pitch, and may determine that a nozzle 21 involved in printing a pattern element pitch that is narrower or wider than the reference value is abnormal. However, the inspection unit 12c excludes the pattern element pitch determined to have a sudden deviation in step S300 from the inspection in step S400.

[0055] For example, if the inspection unit 12c has succeeded in detecting the sudden misalignment in the pattern element pitch P3 and the pattern element pitch P1' as described above, the inspection unit 12c does not inspect the pattern element pitch P3 and the pattern element pitch P1' and the pattern element pitch P4 and the pattern element pitch P2' adjacent to them on the upstream side in step S400. In the example of FIG. 7, the inspection unit 12c performs the inspection in step S400 on the pattern element pitches P1, P2, P3', and P4' in the read image data 60. This makes it possible to avoid erroneously judging that some nozzles 21 are abnormal by inspecting whether the nozzles 21 are normal or abnormal based on the pattern element pitch that is likely to be an inappropriate interval due to the sudden misalignment. The inspection unit 12c stores the inspection result in step S400. This is the end of the flow chart in FIG.

[0056] 4. Summary and effect description: Thus, according to this embodiment, the printing device 10 includes a transport unit 16 that transports the printing medium 30 in the transport direction D2, a print head 18 having a plurality of nozzles 21 that eject ink, and a control unit 11 that controls the transport unit 16 and the print head 18 to print a TP on the printing medium 30 for inspecting the state of ink ejection by the nozzles 21. The TP includes a first pattern element group 41C in which a plurality of pattern elements 51C printed by the nozzles 21 are arranged in the transport direction D2, and a second pattern element group 42C in which a plurality of pattern elements 52C printed by the nozzles 21 are arranged in the transport direction D2. The control unit 11 then transports the printing medium 30 on which the first pattern element group 41C has been printed by ejecting ink from the plurality of nozzles 21 by a predetermined shift amount in the transport direction D2, using the transport unit 16, and prints the second pattern element group 42C on the printing medium 30 by ejecting ink from the plurality of nozzles 21 used for printing the first pattern element group 41C.

[0057] The predetermined shift amount is at least a distance equal to or greater than the nozzle pitch P. With this configuration, the printing device 10 can print a TP suitable for detecting sudden misalignment. That is, in this embodiment, a first pattern element group and a second pattern element group, which are substantially the same image, are printed by using a common plurality of nozzles, shifted by the nozzle pitch P or more in the transport direction D2. Therefore, by comparing the pattern element pitch corresponding to the first pattern element group and the pattern element pitch corresponding to the second pattern element group in the read image data of the TP, it is possible to appropriately detect where in the read image data a sudden misalignment occurs due to a defect during reading. Then, by appropriately detecting the sudden misalignment, it is possible to improve the accuracy of the inspection of whether the nozzle 21 is normal or abnormal, which is performed based on the read image data of the TP.

[0058] As described above, by setting the predetermined shift amount to a distance equal to or greater than the nozzle pitch P, a difference due to accidental shift may occur between the pitch of one pattern element in the first pattern element group and the pitch of one pattern element in the second pattern element group, which should be the same in the scanned image data. In other words, by evaluating the shift amount ΔP(n) and the shift amount ΔP(nN), it is possible to determine whether or not there is accidental shift. As a suitable example, control unit 11 may cause transport unit 16 to transport printing medium 30, on which the first pattern element group has been printed, a distance equal to or greater than twice the nozzle pitch P, and then print the second pattern element group on printing medium 30. In other words, as shown in FIG. 5 etc., the predetermined shift amount may be nozzle pitch P×2.

[0059] If the predetermined shift amount is set to a distance of twice or more the nozzle pitch P, even if the pattern element pitch at which the sudden shift was detected and the pattern element pitch adjacent to this pattern element pitch on the upstream side are excluded from the inspection of step S400, the inspection of each nozzle 21 from the entire read image data can be properly performed in step S400. In other words, according to the example of Fig. 7, even if the pattern element pitches P3 and P4 are excluded from the inspection of step S400, the nozzles 21 with nozzle numbers #3 and #4 can be inspected by referring to the pattern element pitches P3' and P4' instead.

[0060] The printing medium 30 on which the TP is printed may be transported in a tilted position with respect to the transport direction D2 when transported by the transport unit 16. When the printing medium 30 is tilted, the greater the distance between the first pattern element group and the second pattern element group in the main scanning direction D1, the greater the positional relationship between them in the transport direction D2 exceeds a predetermined shift amount, making it difficult to detect the sudden misalignment using the above-mentioned method for detecting the sudden misalignment. Therefore, in this embodiment, as shown in FIG. 6 and other figures, the first pattern element group and the second pattern element group constituting the TP may be arranged at positions adjacent to each other in the main scanning direction D1. With this configuration, even if the printing medium 30 on which the TP is printed is read in a tilted state, the positional relationship between the read image of the first pattern element group and the read image of the second pattern element group in the transport direction D2 is maintained almost normally, making it possible to detect the sudden misalignment.

[0061] According to this embodiment, the printing device 10 may have a reading unit 19 that reads the print medium 30 on which the TP is printed, located downstream of the print head 18 in the transport direction D2. In the example of Fig. 6, the reading unit 19 has multiple sensor chips each having an image sensor for reading. The first pattern element group and the second pattern element group that constitute the TP may be arranged at positions that can be read by a common sensor chip.

[0062] In the example of FIG. 6, TP40C consisting of the first pattern element group 41C and the second pattern element group 42C is printed at a position on the printing medium 30 that is read by the sensor chip 191. In addition, in the example of FIG. 6, TP40M is printed at a position on the printing medium 30 that is read by the sensor chip 192, TP40Y is printed at a position on the printing medium 30 that is read by the sensor chip 193, and TP40K is printed at a position on the printing medium 30 that is read by the sensor chip 194. Since each sensor chip has its own output characteristics and a deviation in the installation position, the read values ​​output by each sensor chip may have a deviation in color or position. As in the example of FIG. 6, the first pattern element group and the second pattern element group constituting TP are in a positional relationship that allows them to be read by a common sensor chip, so that various deviations due to differences in the sensor chips do not occur between the read values ​​of the first pattern element group and the read values ​​of the second pattern element group, and the accuracy of detecting sudden deviations based on the read values ​​of the first pattern element group and the read values ​​of the second pattern element group is improved.

[0063] This embodiment also discloses inventions in each category, such as methods and programs 12 other than the printing device 10 and the printing system 10. The printing method includes a printing step of using a print head 18 having a plurality of nozzles 21 that eject ink to print a TP onto a printing medium 30 for inspecting the state of ink ejection by the nozzles 21, the TP having a first pattern element group in which pattern elements printed by the nozzles 21 are arranged in a transport direction D2 of the printing medium 30, and a second pattern element group in which pattern elements printed by the nozzles 21 are arranged in the transport direction D2, and in the printing step, the printing medium 30 on which the first pattern element group has been printed by ejecting ink from the plurality of nozzles 21 is transported a distance greater than or equal to the nozzle pitch P, which is the spacing between the nozzles 21 in the transport direction D2, and the second pattern element group is printed onto the printing medium 30 by ejecting ink from the plurality of nozzles 21.

[0064] 5. Other embodiments: Other aspects included in this embodiment will be described. The pattern elements constituting the first pattern element group of TP do not all need to be at the same position in the main scanning direction D1. Similarly, the pattern elements constituting the second pattern element group of TP do not all need to be at the same position in the main scanning direction D1. The pattern elements constituting the first pattern element group may be arranged with a shift in the main scanning direction D1 so that their positions in the main scanning direction D1 match at a predetermined number of cycles, and similarly, the pattern elements constituting the second pattern element group may be arranged with a shift in the main scanning direction D1 so that their positions in the main scanning direction D1 match at the predetermined number of cycles.

[0065] FIG. 8 illustrates a part of TP printed on the printing medium 30. Like the right diagram in FIG. 5, FIG. 8 illustrates a state where printing of the second pattern element group by step S150 is completed. As explained above, the first pattern element group 41C is composed of a plurality of pattern elements 51C whose interval in the transport direction D2 corresponds to the nozzle pitch P, and the second pattern element group 42C, which is shifted by a predetermined shift amount along the transport direction D2 with respect to the first pattern element group 41C, is composed of a plurality of pattern elements 52C whose interval in the transport direction D2 corresponds to the nozzle pitch P. Also, according to FIG. 8, each pattern element 51C is arranged with its position shifted in the main scanning direction D1 so that its position in the main scanning direction D1 coincides every three elements. Similarly, each pattern element 52C is also arranged with its position shifted in the main scanning direction D1 so that its position in the main scanning direction D1 coincides every three elements. That is, FIG. 8 illustrates a case where the predetermined number is 3. The predetermined number may be 2 or 4 or more. By printing the pattern elements shifted in the main scanning direction D1, it becomes easier for the inspection unit 12c to identify each individual pattern element when detecting sudden misalignment based on the read image data or inspecting the nozzles 21, and the user can also easily visually identify each individual pattern element.

[0066] Needless to say, the print medium 30 does not have to be continuous paper wound in a roll as illustrated in Fig. 2. The print medium 30 may be cut sheets of paper cut into page units.

[0067] If the detection of sudden misalignment is successful in step S300, the control unit 11 may re-scan the TP printed in step S100 instead of executing the inspection in step S400. For example, if the detection of sudden misalignment is successful in step S300, the control unit 11 causes the conveying unit 16 to backfeed the print medium 30. Backfeeding is a process of conveying the print medium 30 from downstream to upstream. When the portion of the print medium 30 on which the TP is printed returns to a position upstream of the reading unit 19 by backfeeding, the control unit 11 starts conveying the print medium 30 downstream again and causes the reading unit 19 to read the print medium 30 on which the TP is printed. This allows the control unit 11 to obtain read image data again (step S200) and execute step S300 based on this read image data.

[0068] The TP may further include a third pattern element group in which a plurality of pattern elements printed by the nozzles 21 are arranged in the transport direction D2, the third pattern element group being shifted by a predetermined shift amount in the opposite direction to the second pattern element group with respect to the first pattern element group. That is, in step S100, the print control unit 12a prints the TP on the print medium 30 by performing processing in the following order: printing the third pattern element group by a pass of the print head 18, transporting the print medium 30 by the predetermined shift amount, printing the first pattern element group, transporting the print medium 30 by the predetermined shift amount, and printing the second pattern element group. The third pattern element group is also substantially the same image as the first pattern element group and the second pattern element group. In this case, if the predetermined shift amount is the nozzle pitch P×2, the pattern elements printed by the nozzle 21 with nozzle number #5 in the third pattern element group, the pattern elements printed by the nozzle 21 with nozzle number #3 in the first pattern element group, and the pattern elements printed by the nozzle 21 with nozzle number #1 in the second pattern element group will be positioned in the same position in the transport direction D2 on the printing medium 30. The third pattern element group, the first pattern element group, and the second pattern element group are also aligned in this order in the main scanning direction D1.

[0069] According to this configuration, in the read image data of the TP, the pattern element pitches between the pattern element images 51a corresponding to the first pattern element group all match in position in the conveying direction D2 with either the pattern element pitches between the pattern element images 52a corresponding to the second pattern element group or the pattern element pitches between the pattern element images corresponding to the third pattern element group. Therefore, in step S300, the inspection unit 12c can detect sudden deviations for all of the pattern element pitches P1, P2, P3, and P4 between the pattern element images 51a corresponding to the first pattern element group.

[0070] The position of the reading unit 19 does not have to be downstream of the print medium 30 , but may be upstream of the print medium 30 . The reading unit 19 does not need to be a fixed line scan unit, but may be, for example, a moving serial scan unit in which the reading unit 19 reads while moving in the main scanning direction D1. One pattern element 51C does not have to be a ruled line, but may be, for example, a dot. It is not necessary to print the second pattern element group for all ink colors, and it is sufficient to print the second pattern element group in, for example, just one ink color. [Explanation of symbols]

[0071] 10...printing device, 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, 40C, 40M, 40Y, 40K...TP, 41C, 41M, 41Y, 41K...first pattern element group, 42C, 42M, 42Y, 42K...second pattern element group, 51C, 52C...pattern elements, 51a, 52a...pattern element images, 60...read image data

Claims

1. a conveying unit that conveys the print medium in a conveying direction; A print head having a plurality of nozzles for ejecting ink; By controlling the transport unit and the print head, ink is ejected from the nozzles. A control unit that prints a test pattern on the printing medium to check the state of the Based on the test pattern, vibration and external force generated when reading the test pattern are detected. An inspection unit that detects a sudden deviation caused by the occurrence of The test pattern has pattern elements printed by the nozzles overlapping in the transport direction. A first pattern element group in which the number of pattern elements is aligned, and the pattern elements printed by the nozzles are aligned in the conveying direction. a second pattern element group arranged in the direction The control unit is The first pattern element group is printed by discharging the ink from the plurality of nozzles. The printed print medium is then transported to a nozzle pitch that is equal to or greater than the nozzle pitch in the transport direction. and then the plurality of pattern elements used in printing the first pattern element group are transported by the transport unit by the distance of The ink is ejected from the nozzles to print the second pattern element group. Print on the media, The inspection unit includes: When the sudden deviation occurs, the putter in which the sudden deviation occurs is The ink ejection state inspection is performed by excluding the ink ejection state from the ink ejection state inspection. A printing device comprising:

2. n is an integer of 1 or more, The n-th pattern from the downstream direction in the first pattern element group reading result The spacing between the n element and the (n+1)-th pattern element is P(n), The n-th pattern element from the second pattern element group reading result is The spacing between the line element and the (n+1)th pattern element is P(n)', The n-Nth pattern element from a predetermined direction in the first pattern element group reading result The spacing between the pattern element and the (n-N+1)th pattern element is P(n-N), The n-Nth pattern element from the second pattern element group reading result, counting from a predetermined direction The distance between the pattern element and the (n-N+1)th pattern element is defined as P(n-N)'. Then, the deviation amount ΔP(n) and the deviation amount ΔP(n−N) are expressed by the following relational expressions: ΔP(n)=P(n)-P(n)' ΔP(n-N)=P(n-N)-P(n-N)' The inspection unit determines that there is a sudden misalignment when all of the following conditions 1 to 3 are met:

2. The printing device according to claim 1. Condition 1: The sign of ΔP(n) is opposite to the sign of ΔP(n−N). Condition 2: The absolute value of the sum of ΔP(n) and ΔP(n−N) is smaller than a predetermined first threshold value. Condition 3: The absolute value of ΔP(n) and the absolute value of ΔP(n−N) are both equal to or smaller than the first value. greater than a second predetermined threshold.

3. The control unit rotates the printing medium on which the first pattern element group is printed at the nozzle pitch and then the second pattern element group is transferred to the transfer unit by a distance equal to or greater than twice the distance of the printing 3. The printing device according to claim 1, wherein the printing device prints on a medium.

4. Each pattern element constituting the first pattern element group is aligned in a main scanning direction intersecting the transport direction. The positions of the first and second electrodes are shifted in the main scanning direction so that the positions of the first and second electrodes coincide with each other in a predetermined number of cycles. And, The pattern elements constituting the second pattern element group have a position in the main scanning direction of The predetermined number of periods are shifted in the main scanning direction so as to coincide with each other. A printing device according to any one of claims 1 to 3.

5. The first pattern element group and the second pattern element group are arranged along a main running direction intersecting the transport direction. Any one of claims 1 to 4, characterized in that the two are arranged adjacent to each other in the scanning direction. The printing device according to any one of the preceding claims.

6. The test pattern is printed at a position downstream of the print head in the transport direction. a reading unit that reads the print medium, the reading unit has a plurality of sensor chips each having an image sensor for reading; The first pattern element group and the second pattern element group are arranged on a common sensor chip. Any one of claims 1 to 5, characterized in that the mark is arranged in a more readable position.

2. The printing apparatus according to claim 1 .

7. A print head having a plurality of nozzles for ejecting ink is used, and ink is ejected from the nozzles. a printing step of printing a test pattern on a printing medium to inspect the state of ejection; Based on the test pattern, vibration and external factors that occur when reading the test pattern are detected. An inspection step of detecting a sudden deviation caused by the occurrence of a force, The test pattern is a pattern element printed by the nozzles, the pattern element being A first pattern element group arranged in a feed direction and a pattern element printed by the nozzle a second pattern element group arranged in the transport direction; In the printing step, the ink is ejected from the plurality of nozzles to print the first pattern. The printing medium on which the turn element group is printed is After conveying the nozzles by a distance equal to or greater than the nozzle pitch, the composite material used in printing the first pattern element group is The ink is ejected from a number of the nozzles to print the second pattern element group. Print on the printing medium, When the sudden deviation occurs, the pattern in which the sudden deviation occurs Excluding the element from the inspection of the ink ejection state A printing method comprising:

Images