inkjet printer

Abstract

To suppress influence of inaccuracy of an image in a test pattern in inspecting a condition of a nozzle.SOLUTION: A test image printing part of an inkjet printer prints, on a recording medium 5, a test image 200 which includes a mark 210 in a predetermined shape for correcting an image photographed by a photographing device and a test pattern 220 for inspecting conditions of a plurality of nozzles. An image obtaining part controls the photographing device so that the device obtains the test image 200 printed on the recording medium 5. A correcting part compares an image of the mark 210 photographed by the photographing device with the predetermined shape of the mark 210 to calculate a correction value, and corrects the image in the test pattern 220 photographed by the photographing device on the basis of the calculated correction value. An inspecting part inspects conditions of the plurality of nozzles from the image in the test pattern 220 corrected by the correcting part.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an inkjet printer.

Background Art

[0002] An inkjet printer that prints a test pattern for inspecting poor ink ejection on a recording medium has been conventionally known. For example, Patent Document 1 discloses an inkjet printer that prints a linear test pattern on a recording medium and reads the test pattern with a scanner unit. According to Patent Document 1, it is possible to determine the presence or absence of nozzles that do not eject ink by comparing the number of lines read by the scanner unit with the number of lines that should be present.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When attempting to perform a more precise inspection than the inkjet printer described in Patent Document 1, for example, an inspection to identify nozzles with poor ejection, precision is required in the image of the test pattern read by the inkjet printer. However, in reality, the image of the test pattern acquired by the imaging device often has, for example, its size enlarged or reduced, or its shape distorted (hereinafter, these differences between the image acquired by the imaging device and the actual object are collectively referred to as "image inaccuracy"). Due to such image inaccuracy, it is difficult to accurately identify the portion of the test pattern corresponding to each nozzle. Therefore, for example, it is difficult to identify nozzles with poor ejection using an inkjet printer.

[0005] The present invention has been made in view of the above, and its object is to provide an inkjet printer that inspects the state of a nozzle based on an image of a test pattern acquired by an imaging device, which can suppress the effects of image inaccuracy and inspect the state of the nozzle more precisely. [Means for solving the problem]

[0006] The inkjet printer disclosed herein comprises a recording head equipped with a plurality of nozzles for ejecting ink onto a recording medium, an imaging device for acquiring an image of the recording medium, and a control device. The control device comprises a test image printing unit, an image acquisition unit, a correction unit, and an inspection unit. The test image printing unit controls the recording head to print a test image onto the recording medium, which includes a mark of a predetermined shape for correcting the image taken by the imaging device and a test pattern for inspecting the state of the plurality of nozzles. The image acquisition unit controls the imaging device to acquire an image of the test image printed on the recording medium. The correction unit compares the image of the mark taken by the imaging device with the predetermined shape of the mark to calculate a correction value, and corrects the image of the test pattern taken by the imaging device based on the calculated correction value. The inspection unit inspects the state of the plurality of nozzles from the image of the test pattern corrected by the correction unit.

[0007] According to the above inkjet printer, inaccuracies in the test pattern image can be corrected by a correction value calculated by comparing the image of the mark captured by the imaging device with the predetermined shape of the mark. Therefore, the above inkjet printer can suppress the effects of image inaccuracies and inspect the nozzle condition more precisely. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of an inkjet printer according to one embodiment. [Figure 2]This is a schematic plan view showing the configuration of the underside of the carriage. [Figure 3] This is a block diagram of a printer. [Figure 4] This flowchart shows an example of automated inspection and cleaning of a recording head. [Figure 5] A planar diagram showing an example of a test image. [Figure 6] This is a plan view of the mark. [Modes for carrying out the invention]

[0009] The following describes an inkjet printer according to one embodiment, with reference to the drawings. It should be noted that the embodiment described herein is not intended to limit the present invention. Furthermore, the same reference numerals are used for components and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate. In the following description, when viewing the inkjet printer from the front, the direction away from the inkjet printer is considered the front, and the direction towards the inkjet printer is considered the rear. Also, the reference numerals F, Rr, L, R, U, and D in the drawings represent front, rear, left, right, up, and down, respectively. However, these are merely directions for the convenience of explanation and do not limit the installation configuration of the inkjet printer.

[0010] [Inkjet printer configuration] Figure 1 is a front view of a large-format inkjet printer (hereinafter referred to as "printer") 10 according to one embodiment. The printer 10 forms an image on the recording medium 5 by moving the roll-shaped recording medium 5 in the front-to-back direction and ejecting ink from a recording head 50 mounted on a carriage 20 that moves in the left-to-right direction. Hereinafter, the direction of movement of the carriage 20 will also be referred to as the main scanning direction Y, and the direction of movement of the recording medium 5 will also be referred to as the sub-scanning direction X (see Figure 2). The main scanning direction Y is here the left-to-right direction. The sub-scanning direction X is here the front-to-back direction. The main scanning direction Y and the sub-scanning direction X are orthogonal.

[0011] The recording medium 5 is the object on which the image is printed. The recording medium 5 is not particularly limited. For example, the recording medium 5 may be paper such as plain paper or inkjet printing paper, or it may be a transparent sheet made of resin or glass. It may also be a sheet made of metal or rubber, or it may be a fabric.

[0012] As shown in Figure 1, the printer 10 includes a recording head 50, an ink supply device 60 that supplies ink to the recording head 50, a carriage 20 that holds the recording head 50, a carriage moving device 30 that moves the carriage 20 in the main scanning direction Y, a transport device 40 that moves the recording medium 5 in the sub-scanning direction X, a capping device 80 that caps the recording head 50, a wiping device 90 that wipes the recording head 50, an imaging device 70 that captures the image formed by the recording head 50, and a control device 100.

[0013] The carriage movement device 30 comprises a guide rail 31, a belt 32, left and right pulleys 33a and 33b, and a carriage motor 34. The carriage 20 is slidably engaged with the guide rail 31. The guide rail 31 extends in the main scanning direction Y. The guide rail 31 guides the movement of the carriage 20 in the main scanning direction Y. The belt 32 is fixed to the carriage 20. The belt 32 is an endless belt. The belt 32 is wrapped around a pulley 33a located on the right side of the guide rail 31 and a pulley 33b located on the left side. The carriage motor 34 is attached to the right pulley 33a. When the carriage motor 34 is driven, the pulley 33a rotates and the belt 32 moves. As a result, the carriage 20 moves along the guide rail 31 in the main scanning direction Y.

[0014] Below the carriage 20, a platen 11 is positioned. The platen 11 extends in the main scanning direction Y and the sub-scanning direction X. A recording medium 5 is placed on the platen 11. The transport device 40 moves the recording medium 5 on the platen 11 in the sub-scanning direction X. The transport device 40 includes a pinch roller 41, a grit roller 42, and a feed motor 43. The pinch roller 41 is positioned above the platen 11 and presses down on the recording medium 5 from above. The pinch roller 41 is positioned behind the carriage 20. The platen 11 is provided with a grit roller 42. The grit roller 42 is positioned below the pinch roller 41. The grit roller 42 is positioned opposite the pinch roller 41. The grit roller 42 is connected to the feed motor 43. The grit roller 42 is rotatable by the driving force of the feed motor 43. When the grid roller 42 rotates with the recording medium 5 sandwiched between the pinch roller 41 and the grid roller 42, the recording medium 5 is transported in the sub-scanning direction X.

[0015] Figure 2 is a schematic plan view showing the configuration of the lower surface of the carriage 20. The recording head 50 is equipped with a plurality of nozzles NZ for ejecting ink. The plurality of nozzles NZ form a plurality of nozzle rows 51 to 58 extending in the sub-scanning direction X. Each of the plurality of nozzle rows 51 to 58 is composed of a plurality of nozzles NZ arranged at a predetermined pitch in the sub-scanning direction X. The plurality of nozzle rows 51 to 58 are arranged in the main scanning direction Y. The length, number, arrangement of the plurality of nozzle rows, the pitch of the nozzles NZ, the type and color of ink ejected, etc. are predetermined according to the model of the printer 10, for example. Hereinafter, the nozzle rows 51 to 58 will also be referred to as the first nozzle row 51 to the eighth nozzle row 58, respectively. The surface of the recording head 50 on which the plurality of nozzles NZ are formed will also be referred to as the nozzle surface 50S.

[0016] The ink supply device 60 supplies ink to the recording head 50. As shown in Figure 1, the ink supply device 60 comprises a plurality of ink cartridges 61, each containing ink, a plurality of ink channels 62, and a plurality of liquid delivery pumps 63 provided in each of the ink channels 62. One ink cartridge 61 is connected to the nozzle NZ of one nozzle row by one ink channel 62. The liquid delivery pumps 63 deliver the ink in the ink cartridges 61 to the recording head 50. In this case, the ink supply device 60 supplies ink of multiple colors to the recording head 50. The plurality of ink cartridges 61 contain ink of multiple colors. The type of ink is not particularly limited. The ink may be, for example, a solvent-based pigment ink or a water-based pigment ink. Alternatively, it may be a water-based dye ink or a UV-curable pigment ink that hardens when exposed to ultraviolet light.

[0017] The imaging device 70 acquires an image of the recording medium 5. In this embodiment, the imaging device 70 is configured to acquire an image of the recording medium 5 placed on the platen 11. However, the imaging device 70 may be configured to acquire an image of the recording medium 5 located elsewhere than the platen 11. As shown in Figure 1, the imaging device 70 is mounted on a panel 12 above the guide rail 31. The imaging device 70 is positioned opposite the platen 11. The imaging device 70 includes, for example, a camera. In this embodiment, the imaging device 70 acquires an image of a test image 200 (see Figure 5) printed on the recording medium 5 for inspecting the state of the nozzle NZ.

[0018] As shown in Figure 1, a home position P1 is set at the rightmost end of the carriage 20's range of motion. Home position P1 is the position where the carriage 20 is positioned when waiting to print, etc. Below the carriage 20 at home position P1, a capping device 80 is located. As shown in Figure 1, the capping device 80 comprises a cap 81, a cap moving device 82, and a suction pump 83.

[0019] The cap 81 is a member that is attached to the recording head 50 and protects the recording head 50. The cap 81 has a container-like shape with an open upper surface. The cap 81 is formed of, for example, rubber. When attached to the recording head 50, the upper edge of the cap 81 is brought into close contact with the nozzle surface 50S of the recording head 50. The cap 81 is supported by a cap moving device 82. The cap moving device 82 attaches or separates the cap 81 from the recording head 50. The suction pump 83 is connected to the cap 81. The suction pump 83 reduces the pressure inside the cap 81 in a state where the cap 81 is attached to the recording head 50. The suction pump 83 thereby sucks ink from the recording head 50.

[0020] The wiping device 90 is a device that wipes the nozzle surface 50S of the recording head 50. As shown in FIG. 1, the wiping device 90 includes a wiper 91 and a wiper moving device 92. The wiper 91 here has a plate-like shape extending in the vertical direction and the main scanning direction Y. The wiper 91 is formed of, for example, rubber. The wiper moving device 92 holds the wiper 91 and moves it in the sub-scanning direction X. The wiping device 90 causes the wiper 91 to wipe the nozzle surface 50S by moving the wiper 91 while in contact with the nozzle surface 50S of the recording head 50.

[0021] The capping device 80 and the wiping device 90, together with the recording head 50 itself, constitute a cleaning device for cleaning the recording head 50. The cleaning device can perform several levels of cleaning on the recording head 50 by flushing to discharge ink from the recording head 50, wiping by the wiping device 90, ink suction by the capping device 80, and combinations thereof.

[0022] Figure 3 is a block diagram of the printer 10 according to this embodiment. As shown in Figure 3, the control device 100 is electrically connected to the carriage motor 34, the feed motor 43, the recording head 50, the liquid delivery pump 63, the imaging device 70, the cap moving device 82, the suction pump 83, and the wiper moving device 92, and is configured to control their operation. The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, it includes an interface (I / F) for receiving print data etc. from an external device such as a host computer, a central processing unit (CPU) that executes instructions for the control program, a ROM (read-only memory) that stores the program executed by the CPU, a RAM (random access memory) used as a working area for expanding the program, and a storage device such as memory that stores the program and various data. The control device 100 does not necessarily have to be located inside the printer 10; for example, it may be installed outside the printer 10 and connected to the printer 10 via wired or wireless communication, such as a computer.

[0023] As shown in Figure 3, the control device 100 includes a test image printing unit 101, an image acquisition unit 102, a correction unit 103, an inspection unit 104, a communication unit 105, a model identification unit 106, a color identification unit 107, a cleaning level registration unit 108, a cleaning level selection unit 109, and a cleaning control unit 110 as processing units related to inspecting and cleaning the state of the nozzle NZ. The control device 100 may include other control units, but these are not shown or described here.

[0024] The test image printing unit 101 controls the recording head 50, carriage moving device 30, and transport device 40 to print the test image 200 onto the recording medium 5. The test image 200 includes a predetermined shaped mark 210 for correcting the image taken by the imaging device 70, and a test pattern 220 for inspecting the state of multiple nozzles NZ (see Figure 5). The test image printing unit 101 is configured to form the mark 210 by overlapping ink ejected from two or more nozzle rows NZ of the multiple nozzle rows 51 to 58. This reduces the possibility of part of the mark 210 being missing due to a faulty nozzle NZ.

[0025] In this embodiment, the mark 210 is formed to include a portion with a predetermined length in the main scanning direction Y (hereinafter referred to as the first comparison portion 211, see Figure 6), a portion with a predetermined length in the sub-scanning direction X (hereinafter referred to as the second comparison portion 212, see Figure 6), and a portion with a predetermined extension direction (hereinafter referred to as the third comparison portion 213, see Figure 6). In this embodiment, the test image printing unit 101 prints the mark 210 including a model display portion 214 (see Figure 6) that represents the model of the printer 10. Details of the test image 200 will be described later.

[0026] The image acquisition unit 102 controls the imaging device 70 to acquire an image of the test image 200 printed on the recording medium 5.

[0027] The correction unit 103 compares the image of the mark 210 taken by the imaging device 70 with a predetermined shape of the mark 210 to calculate a correction value, and corrects the image of the test pattern 220 taken by the imaging device 70 based on the calculated correction value. Here, "correcting the image of the test pattern 220 taken by the imaging device 70" means reducing the difference between the image that should be obtained if there were no inaccuracies in the image taken by the imaging device 70 and the actual image taken by the imaging device 70, and includes cases where the corrected image is the "ideal image". "Correction" is a process that brings the difference between the ideal image and the actual image taken by the imaging device 70 relatively closer.

[0028] As shown in Figure 3, the correction unit 103 comprises a first correction unit 103A, a second correction unit 103B, a third correction unit 103C, and a region identification unit 103D. The first correction unit 103A compares the length of the main scanning direction Y of the image of the first comparison unit 211 by the imaging device 70 with a predetermined length of the main scanning direction Y of the first comparison unit 211 and calculates a first correction value to correct the length of the main scanning direction Y of the image of the test pattern 220. The first correction unit 103A is a correction unit that corrects the length of the main scanning direction Y of the image of the imaging device 70. The first correction value is a correction value that corrects the length of the main scanning direction Y of the image of the imaging device 70.

[0029] The second correction unit 103B compares the length of the sub-scanning direction X of the image of the second comparison unit 212 by the imaging device 70 with a predetermined length of the sub-scanning direction X of the second comparison unit 212 and calculates a second correction value to correct the length of the sub-scanning direction X of the image of the test pattern 220. The second correction unit 103B is a correction unit that corrects the length of the sub-scanning direction X of the image of the imaging device 70. The second correction value is a correction value that corrects the length of the sub-scanning direction X of the image of the imaging device 70. The deviation in the lengths of the main scanning direction Y and sub-scanning direction X of the image of the imaging device 70 is mainly caused by distortion of the image of the imaging device 70.

[0030] The third correction unit 103C compares the elongation direction of the image of the third comparison unit 213 by the imaging device 70 with a predetermined elongation direction of the third comparison unit 213 and calculates a third correction value to correct the tilt of the image of the test pattern 220. The third correction unit 103C is a correction unit that corrects the tilt of the image by the imaging device 70. The third correction value is a correction value that corrects the tilt of the image by the imaging device 70. The deviation in the tilt of the image by the imaging device 70 is mainly caused by the misalignment of the imaging device 70. In this embodiment, the correction value calculated by the correction unit 103 includes a first correction value, a second correction value, and a third correction value.

[0031] The region identification unit 103D corrects the coordinates of a predetermined region where the test pattern 220 is printed using a calculated correction value, and identifies the region where the test pattern 220 exists in the image from the imaging device 70. Details of this process will be described later.

[0032] The inspection unit 104 inspects the state of multiple nozzles NZ from the image of the test pattern 220 corrected by the correction unit 103. In this embodiment, the inspection unit 104 determines whether each nozzle NZ is good or bad, and calculates the percentage of defective nozzles in nozzle rows 51 to 58 (hereinafter also referred to as the nozzle defect rate) based on that determination.

[0033] The communication unit 105 is configured to communicate with a communication terminal used by the user of the printer 10. For example, the communication unit 105 transmits the results of the inspection performed by the inspection unit 104 to the user's communication terminal and receives instructions from the user in response. The user's communication terminal is not particularly limited, but could be a smartphone or a personal computer, for example. The information exchanged between the communication unit 105 and the user is also not limited, but an example will be described later.

[0034] The communication unit 105 also communicates with a database containing information about the printer model 10. In this embodiment, the database contains information about the arrangement of the test pattern 220 for each printer model 10. Specifically, the database contains information about the ink color ejected from nozzle NZ of each nozzle row of the recording head 50 for each printer model 10. This allows the printer 10 to understand the order of the colors in the test pattern 220.

[0035] The model identification unit 106 is configured to identify the model of the printer 10 from the image of the model display unit 214 taken by the imaging device 70. The color identification unit 107 identifies the position of each color test pattern 220 based on the model of the printer 10 identified by the model identification unit 106 and the information on the arrangement of test patterns 220 for each model registered in the database. In this case, the color identification unit 107 identifies the order of the colors in the test pattern 220.

[0036] The cleaning level registration unit 108 stores multiple cleaning levels for the cleaning device (in this case, the recording head 50, the capping device 80, and the wiping device 90). The cleaning level selection unit 109 selects one level from the multiple cleaning levels registered in the cleaning level registration unit 108 according to the state of the multiple nozzles NZ inspected by the inspection unit 104. The cleaning control unit 110 controls the recording head 50, the capping device 80, and the wiping device 90 as cleaning devices to clean the recording head 50 at the level selected by the cleaning level selection unit 109.

[0037] [Inspection and cleaning process] The following describes the process of automatic inspection and cleaning of the recording head 50. Figure 4 is a flowchart showing an example of automatic inspection and cleaning of the recording head 50. As shown in Figure 4, in step S01 of the automatic inspection and cleaning of the recording head 50 according to one example, a test image 200 is printed on the recording medium 5. Figure 5 is a plan view showing an example of the test image 200. As shown in Figure 5, the test image 200 includes marks 210 for correcting the image by the imaging device 70 and a test pattern 220 for inspecting the state of the nozzle NZ. Various known test patterns can be used without limitation as the test pattern 220. Here, the test pattern 220 includes a first test pattern 221 formed from the ink ejected from the nozzle NZ of the first nozzle row 51 to an eighth test pattern 228 formed from the ink ejected from the nozzle NZ of the eighth nozzle row 58. The first test pattern 221 to the eighth test pattern 228 are arranged in this order in the main scanning direction Y.

[0038] In the example shown here, magenta ink is ejected from multiple nozzles NZ of the first nozzle row 51. Yellow ink, cyan ink, black ink, black ink, cyan ink, yellow ink, and magenta ink are ejected from the nozzles NZ of the second nozzle row 52 to the eighth nozzle row 58, respectively. The first test pattern 221 includes a first island 221a formed by magenta ink ejected from every third nozzle NZ of the first nozzle row 51 and extending linearly in the main scanning direction Y, a second island 221b formed by magenta ink ejected from the nozzle NZ that ejects ink to the first island 221a and every third adjacent nozzle NZ in the sub-scanning direction, and similarly formed third islands 221c and fourth islands 221d. By checking for the presence or absence of all linear ink patterns included in the first test pattern 221, the nozzle defect rate of the first nozzle row 51 can be calculated. The second test pattern 222 to the eighth test pattern 228 are similarly constructed, except for the ink color.

[0039] However, the configuration of test pattern 220 is not limited to those described above. Test pattern 220 is not particularly limited as long as the ink ejected from all nozzles NZ lands far apart from each other.

[0040] Mark 210 has a predetermined shape and is positioned so as not to overlap with the test pattern 220. Mark 210 is formed by overlapping ink ejected from nozzles NZ of multiple nozzle rows. This reduces the possibility of part of Mark 210 being missing due to a faulty nozzle NZ. Figure 6 is a plan view of Mark 210. As shown in Figure 6, Mark 210 in one example has a rectangular outline. The length of the outer diameter line of Mark 210 in the main scanning direction Y and the length in the sub-scanning direction X are predetermined. Here, a pair of opposing sides 210Y of Mark 210 extend in the main scanning direction Y and are parallel to the elongation direction of the first test pattern 221 to the eighth test pattern 228. The other pair of opposing sides 210X of Mark 210 extend in the sub-scanning direction X and are parallel to the alignment direction of the first test pattern 221 to the eighth test pattern 228.

[0041] As shown in Figure 6, in this example, the side 210Y of the mark 210 extending in the main scanning direction Y is set in the first comparison unit 211, which serves as the basis for correcting the length in the main scanning direction Y. The side 210X of the mark 210 extending in the sub-scanning direction X is set in the second comparison unit 212, which serves as the basis for correcting the length in the sub-scanning direction X. The side 210Y of the mark 210 extending in the main scanning direction Y is also set in the third comparison unit 213, which serves as the basis for correcting the inclination. In this example, the third comparison unit 213 is the same side as the first comparison unit 211. However, the third comparison unit 213 may be common to the second comparison unit 212, or it may be separate from the first comparison unit 211 and the second comparison unit 212. The mark 210 only needs to include a line extending a predetermined length in a predetermined direction and another line extending a predetermined length in a direction intersecting the above direction; its shape is not limited to a rectangle.

[0042] In this embodiment, the mark 210 includes character information. Here, the mark 210 has a model indicator 214 that includes character information representing the model of the printer 10. The model indicator 214 may simply represent, for example, a number. In that case, the model corresponding to the number is predetermined in the database. However, the configuration of the model indicator 214 is not particularly limited. If it is not necessary to specify the colors of the first test pattern 221 to the eighth test pattern 228, the mark 210 does not need to have a model indicator 214.

[0043] Alternatively, the mark 210 may include a portion representing the order of colors in the test pattern 220. That is, the test image printing unit 101 may be configured to print a mark 210 that includes a color display unit 215 (shown by a dashed line in Figure 6, although details are not shown) that represents the color of the ink supplied by the ink supply device 60 and the position of each color in the test pattern 220. The color display unit 215 may include character information representing the order of colors in the test pattern 220. In that case, the color identification unit 107 may be configured to identify the position of each color in the test pattern 220 from the image of the color display unit 215 taken by the imaging device 70.

[0044] As shown in Figure 4, in step S02 following step S01, the imaging device 70 acquires an image of the test image 200. Hereafter, to avoid confusion with images formed by ink, the image captured by the imaging device 70 will also be referred to as the "captured image". In step S03, the length of the main scanning direction Y of the captured image of the first comparison unit 211 by the imaging device 70 is compared with a predetermined length of the main scanning direction Y of the first comparison unit 211, and a first correction value is calculated to correct the length of the main scanning direction Y of the captured image of the test pattern 220.

[0045] For example, if the length of the first comparison section 211 is set to 10 mm, and the length of the first comparison section 211 in the captured image is 12 mm, a first correction value (10 / 12) is calculated to convert the length of the first comparison section 211 in the captured image from 12 mm to 10 mm. Alternatively, a first correction value (12 / 10) is calculated that treats the length of the first comparison section 211 as 12 mm. In either case, the length of the captured image of the test pattern 220 in the main scanning direction Y is corrected based on the first correction value.

[0046] In step S04, the length of the sub-scan direction X of the image captured by the second comparison unit 212 by the imaging device 70 is compared with a predetermined length of the sub-scan direction X of the second comparison unit 212, and a second correction value is calculated to correct the length of the sub-scan direction X of the image captured by the test pattern 220. The length of the sub-scan direction X of the image captured by the test pattern 220 is corrected based on the second correction value. Steps S03 and S04 correct the distortion of the size and shape of the image captured by the test pattern 220.

[0047] In step S05, the elongation direction of the image captured by the third comparison unit 213 by the imaging device 70 is compared with a predetermined elongation direction of the third comparison unit 213 (here, the main scanning direction Y), and a third correction value is calculated to correct the tilt of the image captured by the test pattern 220. In Figure 6, the direction designated as the main scanning direction Y in the image before correction is shown as Ya, and the direction designated as the sub-scanning direction X in the image before correction is shown as Xa. As shown in Figure 6, the main scanning direction Y and the Ya direction, and the sub-scanning direction X and the Xa direction may be misaligned. The third correction value is an angle. The tilt of the image captured by the test pattern 220 is corrected based on the third correction value. Steps S03 to S05 may be performed in any order.

[0048] In step S06, the coordinates of a predetermined area where the test pattern 220 is printed are corrected using calculated correction values ​​(here, the first correction value, the second correction value, and the third correction value), thereby identifying the area in the image captured by the imaging device 70 where the test pattern 220 exists. In the actual test image 200, the coordinates of the four corners of the first test pattern 221 to the eighth test pattern 228, relative to the mark 210 (distances from the mark 210 in the main scanning direction Y and sub-scanning direction X), are defined. By correcting the directions of the main scanning direction Y and sub-scanning direction X, the length of the main scanning direction Y, and the length of the sub-scanning direction X of these coordinates using the third correction value, the first correction value, and the second correction value, respectively, the area in the image captured by the imaging device 70 where the test pattern 220 exists can be identified. Figure 5 illustrates the process of identifying the area R3 in the captured image where the third test pattern 223 exists.

[0049] If the region where the test pattern 220 exists is not identified in the captured image, it is impossible to distinguish between the absence of a pattern in the first place and the pattern being missing due to a nozzle NZ ejection failure in the area where the test pattern 220 exists. Therefore, it is impossible to identify which nozzle NZ is malfunctioning. Conversely, if the region where the test pattern 220 exists is identified in the captured image, it is possible to identify which nozzle NZ is malfunctioning, even if the pattern at the outermost edge of the area where the test pattern 220 exists is missing due to a nozzle NZ ejection failure.

[0050] In step S07, the model of the printer 10 is identified from the image captured by the imaging device 70 on the model display unit 214. In step S08, the order of colors in the test pattern 220 is identified from the identified model of the printer 10 and the information on the arrangement of the test patterns 220 for each model registered in the database. If the areas in which each color exists in the test pattern 220 cannot be identified, a process of analyzing the colors of the first test pattern 221 to the eighth test pattern 228 from the image captured by the imaging device 70 occurs. This is because the method of determining the presence or absence of a pattern may differ for each color (for example, the determination threshold may differ). Steps S07 and S08 are intended to shorten the inspection time by omitting the process of analyzing the colors of the first test pattern 221 to the eighth test pattern 228 from the image captured by the imaging device 70.

[0051] In step S09, the state of multiple nozzles NZ is inspected from the images captured of the corrected test pattern 220. In this embodiment, the nozzle defect rate for the first test pattern 221 to the eighth test pattern 228 is calculated. In this embodiment, since the images captured of the test pattern 220 are corrected, if there is a nozzle NZ with a discharge defect, it is possible to identify which nozzle NZ it is.

[0052] In step S10, one level is selected from among several cleaning levels registered in the cleaning level registration unit 108, depending on the condition of the nozzle NZ inspected in step S09. The nozzle failure rate is divided into several levels, and the higher the nozzle failure rate, the more thorough the cleaning selected. For example, if the nozzle failure rate is lower than the first threshold, no cleaning is performed. If the nozzle failure rate is higher than the first threshold but lower than the second threshold, cleaning by flushing only with the recording head 50 is selected. If the nozzle failure rate is higher than the second threshold but lower than the third threshold, cleaning including ink suction, flushing, and wiping is selected. However, the above is just an example.

[0053] In step S11, the cleaning device cleans the recording head 50 to the level selected in step S10. This automatic inspection of the nozzle NZ condition and automatic cleaning of the recording head 50 enables good printing even when the user is away from the printer 10. Although not shown in the diagram, the nozzle NZ condition may be inspected again after cleaning. The results of the first and second nozzle NZ inspections may be sent to the user. If the nozzle NZ condition does not improve after cleaning, the user may be notified of this. In that case, the printer 10 may wait for the user's instructions on whether to continue printing.

[0054] [Effects of the Embodiment] The following describes the effects and advantages that can be achieved by the printer 10 according to this embodiment.

[0055] The printer 10 according to this embodiment includes a recording head 50 equipped with a plurality of nozzles NZ for ejecting ink onto a recording medium 5, an imaging device 70 for acquiring an image of the recording medium 5, and a control device 100. The control device 100 includes a test image printing unit 101, an image acquisition unit 102, a correction unit 103, and an inspection unit 104. The test image printing unit 101 controls the recording head 50 to print a test image 200 onto the recording medium 5, which includes a mark 210 of a predetermined shape for correcting the image from the imaging device 70, and a test pattern 220 for inspecting the state of the plurality of nozzles NZ. The image acquisition unit 102 controls the imaging device 70 to acquire an image of the test image 200 printed on the recording medium 5. The correction unit 103 compares the image of the mark 210 from the imaging device 70 with the predetermined shape of the mark 210 to calculate a correction value, and corrects the image of the test pattern 220 from the imaging device 70 based on the calculated correction value. The inspection unit 104 inspects the state of multiple nozzles NZ from the image of the test pattern 220 corrected by the correction unit 103.

[0056] With this printer 10, any inaccuracies in the image of the test pattern 220 can be corrected by a correction value calculated by comparing the image of the mark 210 captured by the imaging device 70 with a predetermined shape of the mark 210. Therefore, with the printer 10 according to this embodiment, the influence of inaccuracies in the captured image can be suppressed, and the state of the nozzle NZ can be inspected more precisely.

[0057] In this embodiment, the mark 210 includes a first comparison unit 211 with a predetermined length in the main scanning direction Y and a second comparison unit 212 with a predetermined length in the sub-scanning direction X. The first correction unit 103A of the correction unit 103 compares the length in the main scanning direction Y of the image of the first comparison unit 211 by the imaging device 70 with the predetermined length in the main scanning direction Y of the first comparison unit 211 and calculates a first correction value to correct the length in the main scanning direction Y of the image of the test pattern 220. The second correction unit 103B compares the length in the sub-scanning direction X of the image of the second comparison unit 212 by the imaging device 70 with the predetermined length in the sub-scanning direction X of the second comparison unit 212 and calculates a second correction value to correct the length in the sub-scanning direction X of the image of the test pattern 220. With this configuration, distortion of the size and shape of the image of the test pattern 220 by the imaging device 70 can be corrected.

[0058] In this embodiment, the mark 210 includes a third comparison section 213 whose extension direction is predetermined. The third correction section 103C of the correction section 103 compares the extension direction of the image of the third comparison section 213 obtained by the imaging device 70 with the predetermined extension direction of the third comparison section 213 and calculates a third correction value that corrects the tilt of the image of the test pattern 220. With this configuration, the tilt of the captured image of the test pattern 220 can be corrected.

[0059] In this embodiment, the correction unit 103 corrects the coordinates of a predetermined area where the test pattern 220 is printed using a calculated correction value, and includes an area identification unit 103D that identifies the area where the test pattern 220 exists in the image from the imaging device 70. With this configuration, for the reasons mentioned above, even if the pattern at the outermost edge of the area where the test pattern 220 exists is missing due to a nozzle NZ ejection failure, it is possible to identify which nozzle NZ is having the ejection failure.

[0060] The printer 10 according to this embodiment includes an ink supply device 60 that supplies multiple colors of ink to the recording head 50. The test image printing unit 101 is configured to print a mark 210 including a model display unit 214 that represents the model of the printer 10. The model identification unit 106 identifies the model of the printer 10 from the image of the model display unit 214 taken by the imaging device 70. The color identification unit 107 identifies the position of each color test pattern 221 to 228 from the model of the printer 10 identified by the model identification unit 106 and the information on the arrangement of test patterns 220 for each model registered in the database. With this configuration, the process of analyzing the colors of the first test pattern 221 to the eighth test pattern 228 from the image taken by the imaging device 70 can be omitted, and the inspection time can be shortened.

[0061] In this embodiment, the recording head 50 is equipped with multiple nozzle rows 51 to 58, each consisting of multiple nozzles NZ. The test image printing unit 101 is configured to form a mark 210 by overlapping the ink ejected from two or more nozzle rows NZ of the multiple nozzle rows 51 to 58. With this configuration, the possibility of a portion of the mark 210 being missing due to a faulty nozzle NZ can be reduced.

[0062] The printer 10 according to this embodiment is equipped with a cleaning device capable of cleaning the recording head 50. The control device 100 includes a cleaning level registration unit 108, a cleaning level selection unit 109, and a cleaning control unit 110. Multiple levels of cleaning by the cleaning device are registered in the cleaning level registration unit 108. The cleaning level selection unit 109 selects one level from the multiple cleaning levels registered in the cleaning level registration unit 108 according to the state of multiple nozzles NZ inspected by the inspection unit 104. The cleaning control unit 110 controls the cleaning device to clean the recording head 50 at the level selected by the cleaning level selection unit 109. With this configuration, since the cleaning level is used according to the state of the nozzles NZ, it is possible to suppress wasting time by performing unnecessarily thorough cleaning. Such control is made possible by accurately inspecting the state of the nozzles NZ by correcting the captured image.

[0063] [Other embodiments] A preferred embodiment has been described above. However, the embodiment described above is merely illustrative, and the technology disclosed herein can be implemented in various other forms.

[0064] For example, in the embodiment described above, the mark 210 was configured as a two-dimensional shape occupying a portion of the recording medium 5, but it may also be configured as a one-dimensional shape composed of the necessary lines. The printer only needs to correct the captured image of the test pattern to the extent necessary, and does not need to perform all of the corrections described above.

[0065] The configuration of an inkjet printer is not limited to those described above. For example, an inkjet printer does not have to be a so-called roll-to-roll type inkjet printer that prints on a platen onto a roll-shaped recording medium. Alternatively, an inkjet printer may be a so-called flatbed type inkjet printer that prints on a recording medium placed on a movable support.

[0066] The correction and inspection of the test patterns described above may be performed by an inspection device separate from the inkjet printer used to print the test images. Unless otherwise specified, the embodiments are not limited to the present invention. [Explanation of symbols]

[0067] 5. Recording media 10 Inkjet Printers 50 recording heads 60 Ink supply device (supply device) 70 Imaging device 80. Capping device (cleaning device) 90 Wiping device (cleaning device) 100 Control device 101 Test Image Printing Section 102 Image acquisition unit 103 Correction Unit 103A 1st correction section 103B 2nd correction section 103C Third correction section 103D area identification part 104 Inspection Department 106 Model identification section 107 Color identification section 108 Cleaning Level Registration Section (Registration Section) 109 Cleaning level selection section (selection section) 110 Cleaning Control Unit 200 test images 210 marks 211 1st comparison part (1st part) 212 Second Comparison Part (Second Part) 213 Third comparison part (3rd part) 214 Model display section 215 Color display section 220 test patterns

Claims

1. A recording head equipped with multiple nozzles that eject ink onto a recording medium, A supply device that supplies multiple colors of ink to the recording head, An imaging device for acquiring an image of the aforementioned recording medium, A control device is provided, The control device is A test image printing unit controls the recording head to print a test image onto the recording medium, which includes a predetermined shaped mark for correcting the image taken by the imaging device and a test pattern for inspecting the state of the multiple nozzles. An image acquisition unit controls the imaging device to acquire an image of the test image printed on the recording medium, A correction unit that compares the image of the mark taken by the imaging device with a predetermined shape of the mark to calculate a correction value, and corrects the image of the test pattern taken by the imaging device based on the calculated correction value, The system includes an inspection unit that inspects the state of the plurality of nozzles from the image of the test pattern corrected by the correction unit, The aforementioned test image includes one mark for each of the multiple test patterns consisting of test patterns of each color. The correction unit includes a region identification unit that corrects the coordinates of the marks in a predetermined area where the test patterns of each color are printed, using the calculated correction value, and identifies the area in the image captured by the imaging device where the test patterns of each color exist. Inkjet printer.

2. A recording head having a plurality of nozzles for ejecting ink onto a recording medium, A supply device that supplies multiple colors of ink to the recording head, An imaging device for acquiring an image of the aforementioned recording medium, A control device is provided, The control device is A test image printing unit controls the recording head to print a test image onto the recording medium, which includes a predetermined shaped mark for correcting the image taken by the imaging device and a test pattern for inspecting the state of the multiple nozzles. An image acquisition unit controls the imaging device to acquire an image of the test image printed on the recording medium, A correction unit that compares the image of the mark taken by the imaging device with a predetermined shape of the mark to calculate a correction value, and corrects the image of the test pattern taken by the imaging device based on the calculated correction value, The system includes an inspection unit that inspects the state of the plurality of nozzles from the image of the test pattern corrected by the correction unit, The test image printing unit is configured to print the marks, which include a color display unit that indicates the color of the ink supplied by the supply device and the position of the test pattern for each color. The control device further includes a color identification unit that identifies the position of each color test pattern from the image of the color display unit obtained by the imaging device. Inkjet printer.

3. A recording head having a plurality of nozzles for ejecting ink onto a recording medium, A supply device that supplies multiple colors of ink to the recording head, An imaging device for acquiring an image of the aforementioned recording medium, A control device is provided, The control device is A test image printing unit controls the recording head to print a test image onto the recording medium, which includes a predetermined shaped mark for correcting the image taken by the imaging device and a test pattern for inspecting the state of the multiple nozzles. An image acquisition unit controls the imaging device to acquire an image of the test image printed on the recording medium, A correction unit that compares the image of the mark taken by the imaging device with a predetermined shape of the mark to calculate a correction value, and corrects the image of the test pattern taken by the imaging device based on the calculated correction value, The system includes an inspection unit that inspects the state of the plurality of nozzles from the image of the test pattern corrected by the correction unit, The test image printing unit is configured to print the mark, which includes a model display unit that indicates the model of the inkjet printer. The control device is A model identification unit that identifies the model of an inkjet printer from the image of the model display unit taken by the imaging device, The system further includes a color identification unit that identifies the model identified by the aforementioned model identification unit and the information on the arrangement of test patterns for each model registered in the database, and identifies the position of the test pattern for each color. Inkjet printer.

4. The aforementioned mark is, A first part having a predetermined length in a first direction, It includes a second portion whose length in a second direction intersecting the first direction is predetermined, The correction unit, A first correction unit calculates a first correction value for correcting the length of the image of the test pattern in the first direction by comparing the length of the image of the first portion obtained by the imaging device in the first direction with a predetermined length of the first portion in the first direction, The system includes a second correction unit that compares the length in the second direction of the image of the second portion obtained by the imaging device with a predetermined length in the second direction of the second portion, and calculates a second correction value to correct the length in the second direction of the image of the test pattern. An inkjet printer according to any one of claims 1 to 3.

5. The aforementioned mark includes a third portion whose extension direction is predetermined, The correction unit includes a third correction unit that compares the elongation direction of the image of the third portion by the imaging device with a predetermined elongation direction of the third portion and calculates a third correction value to correct the tilt of the image of the test pattern. An inkjet printer according to any one of claims 1 to 4.

6. The recording head comprises multiple nozzle rows, each consisting of multiple nozzles, The test image printing unit is configured to form the mark by overlapping ink ejected from two or more nozzle rows among the plurality of nozzle rows. An inkjet printer according to any one of claims 1 to 5.

7. The device further comprises a cleaning device capable of cleaning the recording head, The control device is A registration unit in which multiple levels of cleaning by the cleaning device are registered, A selection unit selects one level from among several cleaning levels registered in the registration unit, according to the state of the multiple nozzles inspected by the inspection unit. The system includes a cleaning control unit that controls the cleaning device to clean the recording head at a level selected by the selection unit. An inkjet printer according to any one of claims 1 to 6.

Images