Recording device and test pattern formation method

Abstract

To prevent a situation where a defective nozzle which has an ejection failure cannot be detected.SOLUTION: A test pattern includes a plurality of individual patterns along a main scanning direction formed by liquid ejection from each of a plurality of first nozzles. The individual patterns adjacent to each other in a sub-scanning direction are located at positions shifted from each other in the main scanning direction. The plurality of first nozzles include a first continuous nozzle group that is continuous in the sub-scanning direction and a second continuous nozzle group that is continuous in the sub-scanning direction. The test pattern includes a first pattern group derived from liquid ejection from the first continuous nozzle group, and a second pattern group derived from liquid ejection from the second continuous nozzle group. A control unit performs control to form the test pattern in which at least the first pattern group and the second pattern group are arranged in the main scanning direction, by performing sub-scanning between formation of the first pattern group and formation of the second pattern group.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus capable of forming a test pattern that indicates the ejection state of a nozzle, and a test pattern forming method. [Background technology]

[0002] Inkjet printers are known as recording devices that eject liquid ink from a recording head onto a medium. If the viscosity of the ink inside the nozzle increases, air bubbles get trapped in the nozzle, or dust or paper particles adhere to the nozzle, ink droplets may not be ejected from the nozzle or may not land in the correct position on the medium. Here, a nozzle that does not eject ink droplets properly is referred to as a defective nozzle.

[0003] Patent Document 1 discloses that in order to inspect the state of ink ejection from a nozzle array, a test pattern is printed on a printing medium, which shows the ejection state of each nozzle using ruled lines along the main scanning direction, i.e., individual patterns. The length of the test pattern in the sub-scanning direction corresponds to the length of the nozzle array in the sub-scanning direction. For example, if a print head has four nozzle arrays, each for C (cyan), M (magenta), Y (yellow), and K (black), a test pattern is printed in which a C pattern group, an M pattern group, a Y pattern group, and a K pattern group are arranged in the main scanning direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-11429 Summary of the Invention [Problem to be solved by the invention]

[0005] The print head is a "vertical array head" with a color nozzle array in which a C nozzle group, an M nozzle group, and a Y nozzle group are aligned along the K nozzle array. In the color nozzle array, there are unused nozzles between the C nozzle group and the M nozzle group, and there are unused nozzles between the M nozzle group and the Y nozzle group. Because the vertical array head has only two nozzle arrays, a test pattern is printed in which two pattern groups, K and color, are aligned in the main scanning direction. In this case, if a defective nozzle in the K nozzle array and a defective nozzle in the color nozzle array are in the same position, it may be impossible to detect the position corresponding to the defective nozzle from the test pattern. Furthermore, because gaps are created at the color transitions in the patterns resulting from ink ejection from the color nozzle array, it may be impossible to detect the position corresponding to the defective nozzle from the test pattern even if the nozzle corresponding to an individual pattern adjacent to the gap is defective. If the position corresponding to the defective nozzle cannot be detected, the defective nozzle in the nozzle array will not be detected.

[0006] The above-described problem can also occur in recording devices other than inkjet printers with vertically arranged heads, such as monochrome printers that only have a K nozzle row in the recording head. [Means for solving the problem]

[0007] The recording device of the present invention comprises: a recording head having a first nozzle row in which a plurality of first nozzles capable of ejecting liquid onto a medium are arranged; a control unit that controls a main scan that moves the recording head along a main scan direction that intersects with an arrangement direction of the plurality of first nozzles, a sub scan that moves at least one of the medium and the recording head along a sub scan direction that intersects with the main scan direction, and the ejection of the liquid from the recording head, the control unit is capable of controlling formation of a test pattern including a plurality of individual patterns along the main scanning direction by ejecting liquid from each of the plurality of first nozzles, the individual patterns adjacent to each other in the sub-scanning direction are positioned at positions shifted in the main scanning direction, the plurality of first nozzles include a first continuous nozzle group that is continuous in the sub-scanning direction and a second continuous nozzle group that is continuous in the sub-scanning direction, the test pattern includes a first pattern group resulting from liquid ejection from the first continuous nozzle group and a second pattern group resulting from liquid ejection from the second continuous nozzle group, The control unit has an aspect in which it controls the formation of the test pattern in which at least the first pattern group and the second pattern group are aligned in the main scanning direction by performing the sub-scanning between the formation of the first pattern group and the formation of the second pattern group.

[0008] A test pattern forming method of the present invention is a test pattern forming method that forms a test pattern by performing a main scan in which a recording head having a first nozzle row in which a plurality of first nozzles capable of ejecting liquid onto a medium are arranged is moved along a main scan direction that intersects with the arrangement direction of the plurality of first nozzles, and a sub-scan in which at least one of the medium and the recording head is moved along a sub-scan direction that intersects with the main scan direction, the test pattern includes a plurality of individual patterns along the main scanning direction formed by liquid ejection from each of the plurality of first nozzles, the individual patterns adjacent to each other in the sub-scanning direction are positioned at positions shifted in the main scanning direction, the plurality of first nozzles include a first continuous nozzle group that is continuous in the sub-scanning direction and a second continuous nozzle group that is continuous in the sub-scanning direction, The test pattern forming method includes: a first pattern group forming step of forming a first pattern group on the medium by ejecting the liquid from the first continuous nozzle group; a second pattern group forming step of forming a second pattern group on the medium by ejecting the liquid from the second continuous nozzle group; and a sub-scanning step of performing the sub-scanning so that the first pattern group and the second pattern group are aligned in the main scanning direction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of a recording apparatus. [Figure 2] FIG. 2 is a diagram schematically showing an example of a recording head and a test pattern. [Figure 3] FIG. 4 is a diagram schematically showing an example of classification of nozzle groups. [Figure 4] FIG. 10 is a diagram schematically showing an example of a test pattern. [Figure 5] 1A and 1B are diagrams schematically showing an example of a test pattern forming method. [Figure 6] 1A and 1B are diagrams schematically showing an example of a test pattern forming method. [Figure 7] FIG. 10 is a diagram schematically showing an example of a test pattern including individual pattern positions of defective nozzles. [Figure 8] FIG. 10 is a diagram schematically showing another example of a test pattern. [Figure 9] FIG. 10 is a diagram schematically illustrating an example of a test pattern including individual pattern positions of defective nozzles in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention. Of course, the following embodiments are merely examples of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention.

[0011] (1) Summary of the aspects included in the present invention: First, an overview of the embodiments included in the present invention will be described with reference to the examples shown in Figures 1 to 9. The figures in the present application are diagrams showing examples in a schematic manner, and the scale of each part may differ from the actual scale in order to make each part of these figures large enough to be recognizable. The magnification in each direction shown in these figures may differ, and the figures may not be consistent with each other. Of course, each element of the present embodiment is not limited to the specific example indicated by a symbol. In the "Outline of the embodiments included in the present invention," the words in parentheses indicate supplementary explanations for the immediately preceding words.

[0012] [Aspect 1] As illustrated in FIG. 1, a recording apparatus 1 according to one embodiment includes a recording head 30 and a control unit U1. As illustrated in FIGS. 2 to 4, the recording head 30 has a first nozzle row (e.g., a K nozzle row 33K) in which a plurality of first nozzles (e.g., K nozzles 34K) capable of ejecting a liquid 36 onto a medium ME0 are arranged. As illustrated in FIGS. 5 and 6, the control unit U1 controls a main scanning SC1 that moves the recording head 30 along a main scanning direction D1 intersecting with the arrangement direction D4 of the plurality of first nozzles (34K), a sub-scanning SC2 that moves at least one of the medium ME0 and the recording head 30 along a sub-scanning direction D2 intersecting with the main scanning direction D1, and the ejection of the liquid 36 from the recording head 30. As illustrated in FIGS. 2 and 4, the control unit U1 can control the formation of a test pattern TP including a plurality of individual patterns L along the main scanning direction D1 by ejecting liquid from each of the plurality of first nozzles (34K). Here, the individual patterns L adjacent to each other in the sub-scanning direction D2 are offset in the main scanning direction D1. As illustrated in FIGS. 3 and 4, the plurality of first nozzles (34K) include a first continuous nozzle group NG1 that is continuous in the sub-scanning direction D2 and a second continuous nozzle group NG2 that is continuous in the sub-scanning direction D2. The test pattern TP includes a first pattern group PG1 resulting from liquid ejection from the first continuous nozzle group NG1 and a second pattern group PG2 resulting from liquid ejection from the second continuous nozzle group NG2. As illustrated in FIGS. 5 and 6, the control unit U1 performs control to form the test pattern TP in which at least the first pattern group PG1 and the second pattern group PG2 are aligned in the main scanning direction D1 by performing the sub-scan SC2 between the formation of the first pattern group PG1 and the formation of the second pattern group PG2.

[0013] Because the first pattern group PG1 formed by the first continuous nozzle group NG1 in the first nozzle row (33K) and the second pattern group PG2 formed by the second continuous nozzle group NG2 in the first nozzle row (33K) are aligned in the main scanning direction D1, the number of individual patterns L formed at the same position in the sub-scanning direction D2 increases. As a result, even if some of the multiple individual patterns L formed at the same position in the sub-scanning direction D2 are not formed due to nozzle ejection defects, the remaining individual patterns L are formed, allowing the position corresponding to the defective nozzle LN to be detected. Therefore, the above aspect can provide a recording device that can prevent a situation in which a defective nozzle due to an ejection defect cannot be detected.

[0014] Here, the medium includes various materials such as paper, fabric, and film. The control unit may perform control so that the second pattern group is formed after the first pattern group is formed, or may perform control so that the first pattern group is formed after the second pattern group is formed. In this application, the terms "first," "second," etc. are terms for distinguishing between elements among a plurality of elements having similarities, and do not indicate an order. Which elements among a plurality of elements fall under the "first," "second," etc. categories is determined relatively. The above remarks also apply to the following aspects.

[0015] [Aspect 2] 3 and 4, the plurality of first nozzles (34K) may further include a third continuous nozzle group NG3 that is continuous in the sub-scanning direction D2 and a fourth continuous nozzle group NG4 that is continuous in the sub-scanning direction D2. The test pattern TP may include the first pattern group PG1, the second pattern group PG2, a third pattern group PG3 that is derived from liquid ejection from the plurality of third continuous nozzles, and a fourth pattern group PG4 that is derived from liquid ejection from the plurality of fourth continuous nozzles. In the test pattern TP, the number of pattern groups PG that are derived from liquid ejection from the first nozzle row (33K) may be four. As illustrated in Figures 5 and 6, the control unit U1 may perform the sub-scanning SC2 between the formation of the second pattern group PG2 and the formation of the third pattern group PG3, and perform the sub-scanning SC2 between the formation of the third pattern group PG3 and the formation of the fourth pattern group PG4, thereby controlling the formation of the test pattern TP in which at least the first pattern group PG1, the second pattern group PG2, the third pattern group PG3, and the fourth pattern group PG4 are arranged in the main scanning direction D1. After further investigation, it was found that the optimum number of pattern groups PG resulting from liquid ejection from one nozzle row in terms of the speed at which the test patterns TP are formed and the accuracy at which faulty nozzles LN are detected is 4. Therefore, the above aspect can provide a recording device that is suitable in terms of the speed at which test patterns are formed and the accuracy at which faulty nozzles are detected.

[0016] [Aspect 3] 2 to 4, the recording head 30 may have a second nozzle row (e.g., a color nozzle row 33A) aligned with the first nozzle row (33K), the second nozzle row (33A) including a plurality of second nozzles (e.g., color nozzles 34A). The plurality of second nozzles (34A) may include a first continuous color nozzle group NG11 including a plurality of first color nozzles arranged in succession that can eject a first color (e.g., C) liquid 36 onto the medium ME0, a second continuous color nozzle group NG12 including a plurality of second color nozzles arranged in succession that can eject a second color (e.g., M) liquid 36 onto the medium ME0, and a third continuous color nozzle group NG13 including a plurality of third color nozzles arranged in succession that can eject a third color (e.g., Y) liquid 36 onto the medium ME0. The test pattern TP may include a first color pattern group PG11 resulting from liquid ejection from the first continuous color nozzle group NG11, a second color pattern group PG12 resulting from liquid ejection from the second continuous color nozzle group NG12, and a third color pattern group PG13 resulting from liquid ejection from the third continuous color nozzle group NG13. The control unit U1 may perform control to form the test pattern TP in which at least the first pattern group PG1, the second pattern group PG2, and the first color pattern group PG11 are aligned in the main scanning direction D1. In the above case, the individual pattern L resulting from the liquid ejection from the second nozzle (34A) is formed at the same position in the sub-scanning direction D2 as the individual pattern L resulting from the liquid ejection from the first nozzle (34K), thereby further reducing the situation where a defective nozzle cannot be detected.

[0017] [Aspect 4] 3 and the like, the plurality of second nozzles (34A) may include a fifth continuous nozzle group NG5 that is continuous in the sub-scanning direction D2 and a sixth continuous nozzle group NG6 that is continuous in the sub-scanning direction D2. As illustrated in FIG. 4 and the like, the test pattern TP may include a fifth pattern group PG5 resulting from liquid ejection from the fifth continuous nozzle group NG5 and a sixth pattern group PG6 resulting from liquid ejection from the sixth continuous nozzle group NG6. As illustrated in FIGS. 5 and 6, the control unit U1 may perform control to form the test pattern TP in which at least the first pattern group PG1, the second pattern group PG2, the fifth pattern group PG5, and the sixth pattern group PG6 are aligned in the main scanning direction D1 by performing the sub-scan SC2 between the formation of the fifth pattern group PG5 and the formation of the sixth pattern group PG6. In the above cases, the two pattern groups PG resulting from the liquid ejection from the first nozzle row (33K) and the two pattern groups PG resulting from the liquid ejection from the second nozzle row (33A) are formed in the same position in the sub-scanning direction D2, further reducing the likelihood of a defective nozzle being unable to be detected. Note that if the sub-scan SC2 is repeated to align the pattern groups PG in the main scanning direction D1, the time required to form the test pattern TP increases. The effect of improving the accuracy of detecting defective nozzles LN compared to the speed at which the test pattern TP is formed is particularly significant when the number of nozzle rows in the print head 30 is two or less. Therefore, the above-described aspects are suitable when the number of nozzle rows in the print head is two or less.

[0018] [Aspect 5] 2 and 4, the test pattern TP may include a plurality of pattern groups PG including the first pattern group PG1 and the second pattern group PG2. The control unit U1 may perform control to form the test pattern TP in which the plurality of pattern groups PG are arranged in the main scanning direction D1 such that the position of each of the individual patterns L included in each of the pattern groups PG in the sub-scanning direction D2 matches the position of any of the individual patterns L included in the other pattern groups PG in the sub-scanning direction D2. In the above cases, since any of the other individual patterns L exists at the position of each individual pattern L in the sub-scanning direction D2, it is possible to further prevent situations in which a defective nozzle cannot be detected.

[0019] [Aspect 6] One embodiment of the test pattern formation method is a test pattern formation method that forms a test pattern TP by performing a main scan SC1 in which a recording head 30 having a first nozzle row (33K) in which a plurality of first nozzles (34K) capable of ejecting liquid 36 onto a medium ME0 is aligned along a main scan direction D1 that intersects with an alignment direction D4 of the plurality of first nozzles (34K), and a sub-scan SC2 in which at least one of the medium ME0 and the recording head 30 is aligned along a sub-scan direction D2 that intersects with the main scan direction D1. This test pattern formation method includes the following steps, as exemplified in FIGS. (a1) A first pattern group forming step ST1 of forming a first pattern group PG1 on the medium ME0 by ejecting the liquid 36 from the first continuous nozzle group NG1. (a2) A second pattern group forming step ST2 in which the second pattern group PG2 is formed on the medium ME0 by ejecting the liquid 36 from the second continuous nozzle group NG2. (a3) A sub-scanning step ST3 in which the sub-scanning SC2 is performed so that the first pattern group PG1 and the second pattern group PG2 are aligned in the main scanning direction D1.

[0020] The above aspect can provide a test pattern forming method that can prevent a situation in which a defective nozzle that has an ejection defect cannot be detected. Here, the second pattern group forming step may be performed after the first pattern group forming step, or the first pattern group forming step may be performed after the second pattern group forming step.

[0021] Furthermore, the above-described aspects are applicable to a recording system including the above-described recording device, a control method for the above-described recording device, a control method for the above-described recording system, a control program for the above-described recording device, a control program for the above-described recording system, a computer-readable recording medium on which any of the above-described control programs is recorded, etc. Furthermore, the above-described recording device may be composed of multiple distributed parts.

[0022] (2) Examples of recording devices: FIG. 1 schematically illustrates a recording device 1. In this example, the recording device 1 is the printer 2 itself; however, the recording device 1 may also be a combination of the printer 2 and a host device HO1. The printer 2 may include a built-in reading unit 60 for reading the print image IM0, or may include additional elements not shown in FIG. 1. FIG. 2 schematically illustrates the nozzle array 33 of the recording head 30 and the test pattern TP on the medium ME0. The recording head 30 shown in FIG. 2 is a "vertical array head" having a color nozzle array 33A in which a C (cyan) nozzle group 33C, an M (magenta) nozzle group 33M, and a Y (yellow) nozzle group 33Y are aligned in a single line along a K (black) nozzle array 33K. FIG. 3 schematically illustrates the classification of the nozzle groups in this example. FIG. 4 schematically illustrates the test pattern TP on the medium ME0.

[0023] The printer 2 shown in FIG. 1 is a serial printer, a type of inkjet printer that ejects a liquid 36 as droplets 37. The printer 2 includes a controller 10, a RAM (Random Access Memory) 21, which is a semiconductor memory, a communication I / F (interface) 22, a storage unit 23, an operation panel 24, a recording head 30, a drive unit 50, a reading unit 60, and the like. The controller 10 and drive unit 50 are examples of a control unit U1. The controller 10, RAM 21, communication I / F 22, storage unit 23, and operation panel 24 are connected to a bus, allowing them to input and output information to and from one another.

[0024] The controller 10 includes a CPU (Central Processing Unit) 11, which is a processor, a color conversion unit 12, a halftone processing unit 13, a rasterization processing unit 14, a drive signal transmission unit 15, and the like. The controller 10 controls the main scanning and sub-scanning by the drive unit 50 and the ejection of droplets 37 by the recording head 30 based on original image data DA1 acquired from either the host device HO1 or a memory card (not shown). It can be said that the controller 10 controls the drive unit 50 and the recording head 30 so that a print image IM0 is formed on the medium ME0. The original image data DA1 may include, for example, two colors, R (red), G (green), and B (blue), for each pixel. 8 Gradation and 2 16 RGB data having integer values ​​of gray scale can be applied. The controller 10 can be configured by a SoC (System on a Chip) or the like.

[0025] The CPU 11 is a device that centrally performs information processing and control in the printer 2. The color conversion unit 12 refers to a color conversion LUT (lookup table) that defines the correspondence between the gradation values ​​of R, G, and B and the gradation values ​​of C, M, Y, and K, and converts the RGB data into two values ​​of C, M, Y, and K for each pixel. 8 Gradation and 2 16 The ink amount data DA2 is converted into ink amount data DA2 having integer values ​​of gradation. The ink amount data DA2 represents the amounts of C, M, Y, and K liquid 36 used in pixel units. Furthermore, if the resolution of the RGB data differs from the printing resolution, the color conversion unit 12 first converts the resolution of the RGB data to the printing resolution, or converts the resolution of the ink amount data DA2 to the printing resolution.

[0026] The halftone processing unit 13 performs halftone processing using a dithering method, error diffusion method, or the like on the gradation values ​​of each pixel that make up the ink amount data DA2 to reduce the number of gradations in the gradation values ​​and generate dot data DA3. The dot data DA3 represents the formation state of dots 38 of droplets 37 on a pixel-by-pixel basis. The dot data DA3 may be binary data that represents the presence or absence of dot formation, or may be multi-value data with three or more gradations that can correspond to dots of different sizes, such as small, medium, and large dots. The rasterization processing unit 14 performs a rasterization process to rearrange the dot data DA3 in the order in which the dots 38 are formed by the driving unit 50, thereby generating raster data RA0.

[0027] The drive signal transmitter 15 generates a drive signal SG1 from the raster data RA0 and outputs it to the drive circuit 31 of the recording head 30. The drive signal SG1 corresponds to a voltage signal applied to the drive elements 32 of the recording head 30. For example, if the dot data DA3 is "dot formation," the drive signal transmitter 15 outputs a drive signal SG1 that causes droplets for dot formation to be ejected. Furthermore, if the dot data DA3 is ternary or higher data, the drive signal transmitter 15 outputs a drive signal SG1 that causes droplets for large dots to be ejected if the dot data DA3 is "large dot formation," and outputs a drive signal SG1 that causes droplets for small dots to be ejected if the dot data DA3 is "small dot formation."

[0028] The above-mentioned elements (11 to 15) may be configured with an ASIC (Application Specific Integrated Circuit), and may directly read data to be processed from the RAM 21 or directly write processed data to the RAM 21.

[0029] The drive unit 50, controlled by the controller 10, includes a carriage drive unit 51 including a servo motor and a roller drive unit 55 including a servo motor. The drive unit 50, under the control of the controller 10, drives the carriage drive unit 51 to reciprocate the carriage 52 along the main scanning direction D1, and drives the roller drive unit 55 to feed the medium ME0 along the transport path 59 in a feed direction D3. As shown in FIG. 2, the main scanning direction D1 is a direction intersecting with the arrangement direction D4 of the nozzles 34 in the nozzle row 33, e.g., a direction perpendicular to the arrangement direction D4. In FIG. 2, the right direction is the forward direction D11 of the main scanning, and the left direction is the return direction D12 of the main scanning. The feed direction D3 is a direction intersecting with the main scanning direction D1, e.g., a direction perpendicular to the main scanning direction D1. In FIG. 1, the feed direction D3 is the right direction, and the left side is referred to as the upstream side and the right side is referred to as the downstream side. The sub-scanning direction D2 shown in FIG. 2 is the opposite direction to the feed direction D3. The carriage drive unit 51 can be said to perform a main scan that changes the relative positional relationship between the recording head 30 and the medium ME0 along the main scanning direction D1. The roller drive unit 55 includes a transport roller pair 56 and a discharge roller pair 57. The roller drive unit 55 performs a sub-scan that feeds the medium ME0 in the feed direction D3 by rotating the drive transport roller of the transport roller pair 56 and the drive discharge roller of the discharge roller pair 57 under the control of the controller 10. The roller drive unit 55 can be said to perform a sub-scan that changes the relative positional relationship between the recording head 30 and the medium ME0 along a sub-scanning direction D2 that intersects with the main scanning direction D1. While the carriage 52 shown in FIG. 2 does not move in the sub-scanning direction D2, the drive unit 50 may also achieve a sub-scan by moving the carriage 52 in the sub-scanning direction D2. At this time, the medium ME0 does not have to move in the sub-scanning direction D2, and the drive unit 50 may achieve sub-scanning by moving both the carriage 52 and the medium ME0 in the sub-scanning direction D2. The medium ME0 is a printing substrate that holds a print image. The material of the medium ME0 is not particularly limited, and various materials such as paper, resin, metal, etc. are possible. The shape of the medium ME0 is also not particularly limited, and various shapes such as rectangular, roll-shaped, etc. are possible, and it may also be three-dimensional.

[0030] The platen 58 is located below the transport path 59 and supports the medium ME0 by contacting the medium ME0 on the transport path 59. The carriage 52 carries the recording head 30. The carriage 52 may also carry a liquid cartridge 35 that supplies the recording head 30 with liquid 36 to be ejected as droplets 37. Of course, the liquid 36 may be supplied to the recording head 30 from a liquid cartridge 35 installed outside the carriage 52 via a tube. The carriage 52 is fixed to an endless belt (not shown) and is movable in the main scanning direction D1 along an elongated guide 53 whose longitudinal direction faces the main scanning direction D1. The recording head 30, controlled by the controller 10, includes a drive circuit 31, a drive element 32, etc., and ejects droplets 37 toward the medium ME0 supported by the platen 58, thereby adhering the liquid 36 to the medium ME0. Therefore, it can be said that the control unit U1 controls the ejection of droplets 37 from the recording head 30.

[0031] The drive circuit 31 applies a voltage signal to the drive element 32 in accordance with the drive signal SG1 input from the drive signal transmission unit 15. The drive element 32 may be a piezoelectric element that applies pressure to the liquid 36 in a pressure chamber communicating with the nozzle 34, or may be a drive element that uses heat to generate bubbles in the pressure chamber and eject droplets 37 from the nozzle 34. The liquid 36 is supplied to the pressure chamber of the recording head 30 from a liquid cartridge 35. The liquid 36 in the pressure chamber is ejected as droplets 37 from the nozzle 34 toward the medium ME0 by the drive element 32. As a result, dots 38 of the droplets 37 are formed on the medium ME0, and a print image IM0 represented by a pattern of dots 38 is formed on the medium ME0. While the recording head 30 moves in the main scanning direction D1, dots 38 are formed according to the raster data RA0, and the medium ME0 is fed in the feed direction D3 by one sub-scanning stroke, and this process is repeated to form the print image IM0 on the medium ME0. Furthermore, the printer 2 may perform bidirectional recording in which the print image IM0 is formed by both the main scan in the forward direction D11 and the main scan in the return direction D12, or may perform unidirectional recording in which the print image IM0 is formed by only one of the main scan in the forward direction D11 and the main scan in the return direction D12.

[0032] The RAM 21 stores original image data DA1 and the like received from the host device HO1 or a memory (not shown), etc. The communication I / F 22 is connected to the host device HO1 by wire or wirelessly, and inputs and outputs information to and from the host device HO1. The host device HO1 includes computers such as personal computers and tablet terminals, mobile phones such as smartphones, digital cameras, digital video cameras, etc. The storage unit 23 may be a non-volatile semiconductor memory such as a flash memory, or a magnetic storage device such as a hard disk. The operation panel 24 includes an output unit 25 such as a liquid crystal panel that displays information, an input unit 26 such as a touch panel that accepts operations on the display screen, etc.

[0033] The reading unit 60 is capable of reading test patterns TP and the like. The reading unit 60 may be a CIS (Contact Image Sensor) or CCD (Charge Coupled Device) image sensor, or a solid-state imaging element such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor or a line sensor or area sensor configured with a CCD. An external scanner may be connected to the printer 2 as the reading unit 60. The reading unit 60 of this specific example includes an analog-to-digital conversion circuit that converts the analog amount of the detected voltage of each pixel into a digital value, and the analog density amount corresponding to each detected voltage is converted into a digital density value by the analog-to-digital conversion circuit and output to the controller 10.

[0034] The recording head 30 has a nozzle array 33 on its nozzle surface 30a, in which a plurality of nozzles 34 capable of ejecting droplets 37 onto the medium ME0 are arranged at a predetermined nozzle pitch in the arrangement direction D4. Here, a nozzle refers to a small hole from which droplets are ejected, and a nozzle array refers to an arrangement of a plurality of nozzles. The nozzle surface 30a is an ejection surface for droplets 37. Of course, a C dot 38 is formed on the medium ME0 from the C droplet 37, an M dot 38 is formed on the medium ME0 from the M droplet 37, a Y dot 38 is formed on the medium ME0 from the Y droplet 37, and a K dot 38 is formed on the medium ME0 from the K droplet 37.

[0035] The print head 30 shown in FIG. 2 has a K nozzle row 33K including a plurality of K nozzles 34K capable of ejecting K liquid 36 onto the medium ME0, and a color nozzle row 33A including a plurality of color nozzles 34A capable of ejecting liquid 36 of colors other than K onto the medium ME0. Here, the K nozzles 34K are an example of first nozzles, the K nozzle row 33K is an example of the first nozzle row, the color nozzles 34A are an example of second nozzles, and the color nozzle row 33A is an example of the second nozzle row. The color nozzle row 33A is parallel to the K nozzle row 33K, and can therefore be said to be aligned with the K nozzle row 33K. Of course, even if they are not strictly parallel, as long as the K nozzle row 33K and the color nozzle row 34A are arranged so that they intersect in the main scanning direction, it can be said that the color nozzle row 33A is aligned with the K nozzle row 33K. 2, a plurality of nozzles 34 are arranged in a single row at a predetermined nozzle pitch in the arrangement direction D4. The plurality of nozzles 34 in each nozzle row (33K, 33A) may be arranged in a staggered manner, i.e., in two rows, at a predetermined nozzle pitch in the arrangement direction D4. Here, the arrangement direction of the plurality of nozzles 34 arranged in a staggered manner is the direction of arrangement of the nozzles in each of the two rows.

[0036] The color nozzle row 33A is divided into multiple color nozzle groups in the arrangement direction D4. In the color nozzle row 33A shown in FIG. 2, a C nozzle group 33C, an M nozzle group 33M, and a Y nozzle group 33Y are arranged in this order in the sub-scanning direction D2. In the sub-scanning direction D2, one or more unused nozzles 34N are located between the C nozzle group 33C and the M nozzle group 33M, and one or more unused nozzles 34N are located between the M nozzle group 33M and the Y nozzle group 33Y. The unused nozzles 34N refer to nozzles that are included in the color nozzle row 33A but are not used. The reason the unused nozzles 34N are located in the color nozzle row 33A is to ensure a certain degree of thickness for the partition walls that separate the flow paths of the liquid 36 by color.

[0037] The test pattern TP represents the ejection status of each nozzle 34 as linear individual patterns L aligned along the main scanning direction D1. Macroscopically, the individual patterns L can be considered lines aligned along the main scanning direction D1. The controller 10 controls the formation of the test pattern TP, which includes multiple individual patterns L aligned along the main scanning direction D1 by ejecting liquid from each of the multiple nozzles 34. The multiple individual patterns L are formed at intervals equal to the nozzle pitch in the sub-scanning direction D2, so that adjacent individual patterns L in the sub-scanning direction D2 are offset in the main scanning direction D1. Figure 2 shows a pattern group PG in which multiple individual patterns L are divided into three groups in the main scanning direction D1 by color and arranged in a staircase pattern. Macroscopically, the pattern group PG can be considered a group of pitch lines. The number of divisions into which the multiple individual patterns L are divided in the main scanning direction D1 is not limited to three and may be, for example, four or more.

[0038] As shown in the comparative example in FIG. 9, a test pattern TP is formed including a pattern group PG having multiple individual patterns L corresponding to the length of each nozzle row (33K, 33A) in the sub-scanning direction D2. Here, multiple individual patterns LK are formed by liquid ejection from the K nozzle row 33K, and multiple individual patterns LC, LM, and LY are formed by liquid ejection from the color nozzle row 33A. The multiple individual patterns LC are formed by liquid ejection from the C nozzle group 33C, the multiple individual patterns LM are formed by liquid ejection from the M nozzle group 33M, and the multiple individual patterns LY are formed by liquid ejection from the Y nozzle group 33Y. For ease of understanding, FIG. 9 shows the K nozzle row 33K with 20 K nozzles 34K, the C nozzle group 33C with 6 color nozzles 34A, the M nozzle group 33M with 6 color nozzles 34A, and the Y nozzle group 33Y with 6 color nozzles 34A. Unused nozzles 34N are omitted from the illustration. 9 also shows pattern groups PG in which a plurality of individual patterns L are divided into two in the main scanning direction D1 and arranged in a stepped pattern. Of course, the number of nozzles 34 included in each nozzle row (33K, 33A) may be greater than the number shown in FIG.

[0039] If the viscosity of the liquid 36 in the nozzle 34 increases, if air bubbles get into the nozzle 34, or if dust or paper powder adheres to the nozzle 34, the droplets 37 may not be ejected from the nozzle 34, or the droplets 37 ejected from the nozzle 34 may not land in the correct position on the medium ME0. If a defective nozzle LN occurs, which does not eject droplets 37 properly, an individual pattern L is not formed at the individual pattern position LP of the defective nozzle LN. When the reading unit 60 reads the test pattern TP and the control unit U1 determines which individual pattern L was not formed in the sub-scanning direction D2, the control unit U1 can detect the position of the defective nozzle LN corresponding to the individual pattern position LP. However, if a defective nozzle LN is located at the same position in both nozzle rows (33K, 33A), such as the top end position 901 shown in FIG. 9, the control unit U1 may not be able to recognize the individual pattern position LP of the defective nozzle LN and may not be able to detect the position of the defective nozzle LN. In particular, if a faulty nozzle LN exists at the end of both nozzle rows (33K, 33A), the control unit U1 cannot identify the first individual pattern L in the sub-scanning direction D2 and cannot detect the position of the faulty nozzle LN. Furthermore, since the pattern group PG formed by liquid ejection from the color nozzle row 33A includes a portion where an individual pattern L is not formed by the unused nozzle 34N, if the individual pattern position LP of the faulty nozzle LN is adjacent to the individual pattern position of the unused nozzle 34N, as in adjacent position 902 shown in FIG. 9 , the control unit U1 may not be able to recognize the individual pattern position LP of the faulty nozzle LN. As a result, the control unit U1 may not be able to detect the position of the faulty nozzle LN. Furthermore, even if the K nozzle 34K in the K nozzle row 33K corresponding to the unused nozzle 34N in the color nozzle row 33A is a faulty nozzle LN, the control unit U1 may not be able to recognize the individual pattern position LP of the faulty nozzle LN and may not be able to detect the position of the faulty nozzle LN.

[0040] 4, the pattern group PG formed by the liquid ejection from the nozzle rows (33K, 33A) is divided into multiple groups and aligned in the main scanning direction D1, thereby improving the reliability of detecting the position corresponding to the defective nozzle LN. This reduces the chance of the defective nozzle LN being unable to be detected.

[0041] First, an example of nozzle group classification will be described with reference to Fig. 3. For ease of understanding, the nozzle row 33 shown in Fig. 3 is also aligned with the nozzle row 33 shown in Fig. 9. That is, the K nozzle row 33K has 20 K nozzles 34K, the C nozzle group 33C has six color nozzles 34A, the M nozzle group 33M has six color nozzles 34A, and the Y nozzle group 33Y has six color nozzles 34A. The multiple K nozzles 34K include a first continuous nozzle group NG1 that are continuous in the sub-scanning direction D2, a second continuous nozzle group NG2 that are continuous in the sub-scanning direction D2, a third continuous nozzle group NG3 that are continuous in the sub-scanning direction D2, and a fourth continuous nozzle group NG4 that are continuous in the sub-scanning direction D2. In Fig. 3, the first continuous nozzle group NG1, the second continuous nozzle group NG2, the third continuous nozzle group NG3, and the fourth continuous nozzle group NG4 are arranged in this order in the sub-scanning direction D2. In the example shown in Fig. 3, the number of K nozzles 34K in each of the continuous nozzle groups (NG1 to NG4) is five.

[0042] The multiple color nozzles 34A include a C nozzle group 33C in which multiple nozzles 34 capable of ejecting C liquid 36 onto medium ME0 are arranged in succession, an M nozzle group 33M in which multiple nozzles 34 capable of ejecting M liquid 36 onto medium ME0 are arranged in succession, and a Y nozzle group 33Y in which multiple nozzles 34 capable of ejecting Y liquid 36 onto medium ME0 are arranged in succession. In the example shown in FIG. 3, there are six nozzle groups (33C, 33M, 33Y). In the sub-scanning direction D2, there is one unused nozzle 34N between the C nozzle group 33C and the M nozzle group 33M, and there is one unused nozzle 34N between the M nozzle group 33M and the Y nozzle group 33Y. In FIG. 3, the C nozzle group 33C, the unused nozzle 34N, the M nozzle group 33M, the unused nozzle 34N, and the Y nozzle group 33Y are arranged in this order in the sub-scanning direction D2. The C nozzle group 33C is an example of the first continuous color nozzle group NG11 and is also an example of the fifth continuous nozzle group NG5 that is continuous in the sub-scanning direction D2. The M nozzle group 33M is an example of the second continuous color nozzle group NG12 and is also an example of the sixth continuous nozzle group NG6 that is continuous in the sub-scanning direction D2. The Y nozzle group 33Y is an example of the third continuous color nozzle group NG13 and is also an example of the seventh continuous nozzle group NG7 that is continuous in the sub-scanning direction D2.

[0043] Next, an example structure of the test pattern TP will be described with reference to Fig. 4. For ease of understanding, Fig. 4 shows pattern groups PG in which a plurality of individual patterns L are divided into two in the main scanning direction D1 and arranged in a stepped pattern. The test pattern TP includes a pattern group (PG1 to PG4) resulting from liquid ejection from the K nozzle row 33K and a pattern group (PG11 to PG13) resulting from liquid ejection from the color nozzle row 33A. The first pattern group PG1 is derived from liquid ejection from the first continuous nozzle group NG1 and includes multiple individual patterns LK. The second pattern group PG2 is derived from liquid ejection from the second continuous nozzle group NG2 and includes multiple individual patterns LK. The third pattern group PG3 is derived from liquid ejection from the third continuous nozzle group NG3 and includes multiple individual patterns LK. The fourth pattern group PG4 is derived from liquid ejection from the fourth continuous nozzle group NG4 and includes multiple individual patterns LK. The first color pattern group PG11 is derived from liquid ejection from the first continuous color nozzle group NG11 and includes multiple individual patterns LC. The first color pattern group PG11 can also be referred to as the fifth pattern group PG5 derived from liquid ejection from the fifth continuous nozzle group NG5. The second color pattern group PG12 is derived from liquid ejection from the second continuous color nozzle group NG12 and includes multiple individual patterns LM. The second color pattern group PG12 can also be referred to as the sixth pattern group PG6 derived from liquid ejection from the sixth continuous nozzle group NG6. The third color pattern group PG13 is derived from the liquid ejection from the third continuous color nozzle group NG13 and includes multiple individual patterns LY. The third color pattern group PG13 can also be said to be a seventh pattern group PG7 derived from the liquid ejection from the seventh continuous nozzle group NG7.

[0044] As shown in FIG. 4, the position of each individual pattern L in each pattern group PG in the sub-scanning direction D2 matches the position of any individual pattern L in any other pattern group PG. For example, the seven individual patterns L1, L2, L3, L4, L5, L6, and L7 shown in FIG. 4 can be said to match their positions in the sub-scanning direction D2. Focusing on each individual pattern LK in the first pattern group PG1 reveals that the other pattern groups (PG2 to PG6) contain individual patterns L with the same position in the sub-scanning direction D2. Focusing on each individual pattern LC in the fifth pattern group PG5 reveals that at least the sixth pattern group PG6 contains an individual pattern LM with the same position in the sub-scanning direction D2, and the seventh pattern group PG7 contains an individual pattern LY with the same position in the sub-scanning direction D2. Since any other individual pattern L exists at the position of each individual pattern L in the sub-scanning direction D2, the situation where a faulty nozzle LN cannot be detected is reduced.

[0045] In the test pattern TP shown in FIG. 4, the number of K pattern groups PG resulting from the liquid ejection from the K nozzle array 33K is four. If the number of K pattern groups PG resulting from the liquid ejection from the K nozzle array 33K is three or less, the pattern groups PG will be longer in the sub-scanning direction D2 than the color pattern groups (PG11 to PG13) resulting from the liquid ejection from the color nozzle array 33A. In this case, the K pattern groups PG will have individual patterns LK whose positions in the sub-scanning direction D2 do not match the individual patterns LC, LM, and LY of the color pattern groups (PG11 to PG13). If the number of K pattern groups PG resulting from the liquid ejection from the K nozzle array 33K is four, the length of the pattern groups PG in the sub-scanning direction D2 can be made shorter than the color pattern groups (PG11 to PG13). This allows the positions of the individual patterns LK to match the positions of the individual patterns LC, LM, and LY in the sub-scanning direction D2. However, if the number of K pattern groups PG resulting from the liquid ejection from the K nozzle row 33K is five or more, the number of main scans SC1 and sub-scans SC2 increases, slowing down the formation of the test pattern TP. Therefore, in terms of the speed at which the test pattern TP is formed and the accuracy of detecting defective nozzles LN, it is optimal for the number of pattern groups PG resulting from the liquid ejection from one nozzle row to be four.

[0046] (3) Specific examples of test pattern formation methods: 5 and 6 schematically show a specific example of a test pattern forming method for printing the test pattern TP shown in Fig. 4. The test pattern forming method includes a first pattern group forming process ST1, a sub-scanning process ST3, and a second pattern group forming process ST2. The controller 10 performs control to form the test pattern TP on the medium ME0 in accordance with the test pattern data for forming the test pattern TP. Therefore, it can be said that the printer 2 performs the test pattern forming method under the control of the controller 10.

[0047] First, the control unit U1 performs control to form a fourth pattern group PG4 on the medium ME0 while performing a main scan SC1 with the fourth continuous nozzle group NG4 of the K nozzle row 33K within the range of the medium ME0 in the sub-scanning direction D2 (state 501 in FIG. 5). The controller 10 causes the carriage drive unit 51 to execute the main scan SC1, which moves the recording head 30 along the main scanning direction D1, and causes the fourth continuous nozzle group NG4 to eject K droplets 37 in accordance with the test pattern data, thereby forming the fourth pattern group PG4 of K at a set position on the medium ME0. The main scan SC1 may be a main scan in the forward direction D11 or a main scan in the backward direction D12. The same applies below. Next, the control unit U1 performs a sub-scan SC2 in the sub-scanning direction D2 until the top end of the third continuous color nozzle group NG13, i.e., the seventh continuous nozzle group NG7, of the color nozzle row 33A is aligned with the top end of the fourth pattern group PG4. The controller 10 causes the roller drive unit 55 to perform the sub-scan SC2, which moves the medium ME0 in the feed direction D3. Therefore, it can be said that the control unit U1 moves the medium ME0 along the sub-scanning direction D2. The same applies below.

[0048] Next, the control unit U1 performs control to form the third color pattern group PG13, i.e., the seventh pattern group PG7, on the medium ME0 while performing a main scan SC1 that moves the recording head 30 along the main scanning direction D1 (state 502 in FIG. 5 ). The controller 10 causes the carriage drive unit 51 to perform the main scan SC1, and causes the seventh continuous nozzle group NG7 to eject Y droplets 37 in accordance with the test pattern data, thereby forming the seventh pattern group PG7 of Y at a set position on the medium ME0. Next, the control unit U1 performs a sub-scan SC2 in the sub-scan direction D2 until the upper end of the third continuous nozzle group NG3 of the K nozzle row 33K is aligned with the upper ends of the pattern groups (PG4, PG7). The controller 10 causes the roller drive unit 55 to perform the sub-scan SC2, which moves the medium ME0 in the feed direction D3.

[0049] Next, the control unit U1 performs control to form the third pattern group PG3 on the medium ME0 while performing a main scan SC1 that moves the recording head 30 along the main scanning direction D1 (state 503 in FIG. 5). The controller 10 causes the carriage drive unit 51 to perform the main scan SC1, and causes the third continuous nozzle group NG3 to eject K droplets 37 in accordance with the test pattern data, thereby forming the third pattern group PG3 of K at a set position on the medium ME0. Next, the control unit U1 performs a sub-scan SC2 in the sub-scan direction D2 until the top end of the second continuous color nozzle group NG12, i.e., the sixth continuous nozzle group NG6, of the color nozzle row 33A is aligned with the top end of the pattern group (PG3, PG4, PG7). The controller 10 causes the roller drive unit 55 to perform the sub-scan SC2, which moves the medium ME0 in the feed direction D3.

[0050] Next, the control unit U1 performs control to form the second continuous color nozzle group NG12, i.e., the sixth pattern group PG6, on the medium ME0 while performing a main scan SC1 that moves the recording head 30 along the main scanning direction D1 (state 504 in FIG. 6 ). The controller 10 causes the carriage drive unit 51 to perform the main scan SC1, and ejects M droplets 37 from the sixth continuous nozzle group NG6 in accordance with the test pattern data, thereby forming the sixth pattern group PG6 of M at a set position on the medium ME0. Next, the control unit U1 performs a sub-scan SC2 in the sub-scan direction D2 until the upper end of the second continuous nozzle group NG2 of the K nozzle row 33K is aligned with the upper end of the pattern group (PG3, PG4, PG6, PG7). The controller 10 causes the roller drive unit 55 to perform the sub-scan SC2, which moves the medium ME0 in the feed direction D3.

[0051] Next, the control unit U1 performs control to form the second pattern group PG2 on the medium ME0 while performing a main scan SC1 that moves the recording head 30 along the main scanning direction D1 (state 505 in FIG. 6). The controller 10 causes the carriage drive unit 51 to perform the main scan SC1, and causes the second continuous nozzle group NG2 to eject K droplets 37 in accordance with the test pattern data, thereby forming the second pattern group PG2 of K at a set position on the medium ME0. In this way, the printer 2 performs the second pattern group formation process ST2. Next, the control unit U1 performs a sub-scan SC2 until the top end of the first continuous nozzle group NG1 of the K nozzle row 33K is aligned with the top end of the pattern groups (PG2, PG3, PG4, PG6, PG7) in the sub-scanning direction D2. In other words, the control unit U1 performs a sub-scan SC2 until the top end of the first continuous color nozzle group NG11, i.e., the fifth continuous nozzle group NG5, of the color nozzle row 33A is aligned with the top end of the pattern groups (PG2, PG3, PG4, PG6, PG7) in the sub-scanning direction D2. The controller 10 causes the roller drive unit 55 to perform a sub-scan SC2 that moves the medium ME0 in the feed direction D3. In this way, the printer 2 performs a sub-scan step ST3 in which the sub-scan SC2 is performed so that the first pattern group PG1 and the second pattern group PG2 are aligned in the main scanning direction D1.

[0052] Finally, the control unit U1 performs main scanning SC1, which moves the recording head 30 along the main scanning direction D1, while controlling the formation of the first pattern group PG1 and the first-color pattern group PG11, i.e., the fifth pattern group PG5, on the medium ME0 (state 506 in FIG. 6). The controller 10 causes the carriage drive unit 51 to execute the main scanning SC1, ejecting K droplets 37 from the first continuous nozzle group NG1 and C droplets 37 from the fifth continuous nozzle group NG5 in accordance with the test pattern data, thereby forming the first pattern group PG1 of K and the fifth pattern group PG5 of C at set positions on the medium ME0. In this way, the printer 2 performs the first pattern group formation step ST1. This completes printing of the test pattern TP shown in FIG. 4.

[0053] As described above, the control unit U1 controls the formation of a test pattern TP in which pattern groups (PG1 to PG7) are aligned in the main scanning direction D1 by appropriately performing sub-scanning SC2. In this case, the control unit U1 controls the formation of a test pattern TP in which multiple pattern groups PG are aligned in the main scanning direction D1 so that the position in the sub-scanning direction D2 of each individual pattern L included in each pattern group PG matches the position in the sub-scanning direction D2 of any individual pattern L included in the other pattern groups PG. Sub-scanning SC2 is performed between the formation of the fourth pattern group PG4 and the formation of the third pattern group PG3, between the formation of the third pattern group PG3 and the formation of the second pattern group PG2, and between the formation of the second pattern group PG2 and the formation of the first pattern group PG1. Sub-scanning SC2 is also performed between the formation of the third color pattern group PG13 and the formation of the second color pattern group PG12, and between the formation of the second color pattern group PG12 and the formation of the first color pattern group PG11.

[0054] 4, the multiple pattern groups (PG1 to PG4) formed by the K nozzle row 33K are aligned in the main scanning direction D1, so the number of K individual patterns L formed at the same position in the sub-scanning direction D2 increases. Also, the multiple pattern groups (PG5 to PG7) formed by the color nozzle row 33A are aligned in the main scanning direction D1, so the number of individual patterns LC, LM, LY formed at the same position in the sub-scanning direction D2 increases.

[0055] FIG. 7 schematically illustrates a test pattern TP including an individual pattern position LP of a faulty nozzle LN. FIG. 7 shows that the presence of a faulty nozzle LN at the ends of both nozzle rows (33K, 33A) results in an individual pattern position LP where an individual pattern L is not formed in the first pattern group PG1 and the fifth pattern group PG5. Even in this case, because individual patterns L exist in the remaining pattern groups (PG2 to PG4, PG6, PG7), the control unit U1 can identify the first individual pattern L in the sub-scanning direction D2. FIG. 7 also shows that the presence of a faulty nozzle LN in the Y-color nozzle 34A of the color nozzle row 33A results in an individual pattern position LP where an individual pattern LY is not formed in the seventh pattern group PG7. Even in this case, because individual patterns L exist in the remaining pattern groups (PG1 to PG6), the control unit U1 can identify the individual pattern position LP. By identifying the individual pattern position LP, the control unit U1 can detect the position corresponding to the defective nozzle LN. Therefore, this specific example can prevent a situation in which the defective nozzle LN cannot be detected.

[0056] 4 to 6, if the sub-scanning direction D2 and the feed direction D3 are interchanged, the K pattern groups (PG1 to PG4) will be formed in the order of first pattern group PG1, second pattern group PG2, third pattern group PG3, and fourth pattern group PG4. In this case, a first pattern group forming step ST1 is performed when the first first pattern group PG1 is formed, a sub-scanning step ST3 is performed between the formation of the first pattern group PG1 and the formation of the second pattern group PG2, and a second pattern group forming step ST2 is performed when the next second pattern group PG2 is formed.

[0057] When a defective nozzle LN is detected, the controller 10 determines whether cleaning of the nozzle row 33 is necessary based on the detection information for the defective nozzle LN, and if it determines that cleaning is necessary, it causes the output unit 25 to display information urging cleaning. For this reason, the printer 2 may be equipped with a cleaning unit that can perform cleaning of the recording head 30. When the controller 10 receives a cleaning instruction from the input unit 26, it causes the cleaning unit to clean the recording head 30. Furthermore, the controller 10 may automatically cause the cleaning unit to clean the recording head 30 when it determines that cleaning is necessary.

[0058] (4) Variation: The present invention can be modified in various ways. For example, the printer 2 may be a monochrome printer whose recording head only has a K nozzle row. Even in this case, the K nozzle row has multiple continuous nozzle groups, and multiple pattern groups resulting from liquid ejection from the multiple continuous nozzle groups are aligned in the main scanning direction, thereby providing the effect of preventing situations where defective nozzles cannot be detected. Some of the above-described processing may be performed by the host device HO1. In this case, the combination of the controller 10, drive unit 50, and host device HO1 is an example of a control unit U1, and the combination of the printer 2 and host device HO1 is an example of a recording device 1. In the test pattern TP, for example, if the first pattern group PG1, the second pattern group PG2, and the first color pattern group PG11 are aligned in the main scanning direction D1, then even if the other pattern groups PG are not aligned in the main scanning direction D1, it is possible to prevent a situation in which defective nozzles LN occurring in the first continuous nozzle group NG1, the second continuous nozzle group NG2, and the first continuous color nozzle group NG11 cannot be detected. Also, if the first pattern group PG1, the second pattern group PG2, the fifth pattern group PG5, and the sixth pattern group PG6 are aligned in the main scanning direction D1, it is possible to prevent a situation in which defective nozzles LN occurring in the first continuous nozzle group NG1, the second continuous nozzle group NG2, the fifth continuous nozzle group NG5, and the sixth continuous nozzle group NG6 cannot be detected, even if the other pattern groups PG are not aligned in the main scanning direction D1.

[0059] As illustrated in FIG. 8, even if the recording head 30 is a vertically arranged head, the number of K pattern groups PG resulting from liquid ejection from the K nozzle array 33K may be two, and the number of pattern groups PG resulting from liquid ejection from the color nozzle array 33A may be two. The multiple K nozzles 34K shown in FIG. 8 include a first continuous nozzle group NG1 that is continuous in the sub-scanning direction D2 and a second continuous nozzle group NG2 that is continuous in the sub-scanning direction D2. The number of K nozzles 34K in each continuous nozzle group (NG1, NG2) is ten. The first pattern group PG1 resulting from liquid ejection from the first continuous nozzle group NG1 includes ten individual patterns LK, and the second pattern group PG2 resulting from liquid ejection from the second continuous nozzle group NG2 includes ten individual patterns LK. The multiple color nozzles 34A shown in FIG. 8 include a fifth continuous nozzle group NG5 that is continuous in the sub-scanning direction D2 and a sixth continuous nozzle group NG6 that is continuous in the sub-scanning direction D2. The fifth continuous nozzle group NG5 includes all of the color nozzles 34A capable of ejecting the C liquid 36 onto the medium ME0, and half of the color nozzles 34A capable of ejecting the M liquid 36 onto the medium ME0. The sixth continuous nozzle group NG6 includes the remaining half of the color nozzles 34A capable of ejecting the M liquid 36 onto the medium ME0, and all of the color nozzles 34A capable of ejecting the Y liquid 36 onto the medium ME0. The fifth pattern group PG5 resulting from the liquid ejection from the fifth continuous nozzle group NG5 includes all of the individual patterns LC and half of the individual patterns LM. The sixth pattern group PG6 resulting from the liquid ejection from the sixth continuous nozzle group NG6 includes half of the individual patterns LM and all of the individual patterns LY.

[0060] The test pattern TP shown in FIG. 8 can be formed by two main scanning passes SC1 and one sub-scanning pass SC2, as exemplified below. (First main scanning SC1) The control unit U1 forms the second pattern group PG2 and the sixth pattern group PG6 on the medium ME0 (second pattern group forming step ST2). (Sub-scanning SC2) The control unit U1 performs sub-scanning SC2 so that the first pattern group PG1, the second pattern group PG2, the fifth pattern group PG5, and the sixth pattern group PG6 are aligned in the main scanning direction D1 (sub-scanning step ST3). (Second main scanning SC1) The control unit U1 forms the first pattern group PG1 and the fifth pattern group PG5 on the medium ME0 (first pattern group forming step ST1). Therefore, the speed at which the test pattern TP is formed can be improved. Of course, if the sub-scanning direction D2 and the feed direction D3 are interchanged in the example shown in Figure 8, the first pattern group PG1 and the fifth pattern group PG5 will be formed, and then the second pattern group PG2 and the sixth pattern group PG6 will be formed.

[0061] 8, the number of individual patterns L formed at the same position in the sub-scanning direction D2 is also increased. As a result, even if some of the individual patterns L formed at the same position in the sub-scanning direction D2 are not formed due to defective nozzle ejection, the remaining individual patterns L are formed, allowing the position corresponding to the defective nozzle LN to be detected. This prevents the occurrence of a situation where the defective nozzle LN cannot be detected.

[0062] (5) Conclusion: As explained above, according to the present invention, it is possible to provide a configuration that can prevent a situation in which a defective nozzle that is causing an ejection defect cannot be detected through various aspects. Of course, even in an aspect that consists only of the elements according to the independent claims, the basic functions and effects described above can be obtained. Furthermore, it is possible to implement configurations in which the components disclosed in the above examples are substituted with each other or the combination is changed, or configurations in which the components disclosed in the publicly known techniques and the above examples are substituted with each other or the combination is changed, etc. The present invention also includes these configurations. [Explanation of symbols]

[0063] 1...recording device, 2...printer, 10...controller, 30...recording head, 33...nozzle array, 33A...color nozzle array, 33C...C nozzle group, 33M...M nozzle group, 33Y...Y nozzle group, 33K...K nozzle array, 34...nozzle, 34A...color nozzle, 34K...K nozzle, 34N...unused nozzle, 36...liquid, 37...droplet, 38...dot, 50...drive unit, 52...carriage, 60...reading unit, D1...main scanning direction, D2...sub-scanning direction, D3...feed direction, D4...arrangement direction, D11...forward direction, D12...return direction, HO1...host device, IM0...printed image, L, LC, LM, LY, LK...individual patterns, LN...defective nozzle, LP...individual pattern position, ME0...medium, NG1...first continuous nozzle group, NG2...second continuous nozzle group, NG3...third continuous nozzle group, NG4...fourth continuous nozzle group, NG5...fifth continuous nozzle group, NG6...sixth continuous nozzle group, NG7...seventh continuous nozzle group, NG11...first continuous color nozzle group, NG12...second continuous color nozzle group, NG13...third continuous color nozzle group, PG...pattern group, PG1...first pattern group, PG2...second pattern group, PG3...third pattern group, PG4...fourth pattern group, PG5...fifth pattern group, PG6...sixth pattern group, PG7...seventh pattern group, PG11...first color pattern group, PG12...second color pattern group, PG13...third color pattern group, TP...test pattern, SC1...main scanning, SC2...sub-scanning, ST1...first pattern group forming step, ST2...second pattern group forming step, ST3...sub-scanning step, U1...control unit.

Claims

1. a recording head having a first nozzle row in which a plurality of first nozzles capable of ejecting liquid onto a medium are arranged; a control unit that controls a main scan that moves the recording head along a main scan direction that intersects with an arrangement direction of the plurality of first nozzles, a sub scan that moves at least one of the medium and the recording head along a sub scan direction that intersects with the main scan direction, and the ejection of the liquid from the recording head, the control unit is capable of controlling formation of a test pattern including a plurality of individual patterns along the main scanning direction by ejecting liquid from each of the plurality of first nozzles, the individual patterns adjacent to each other in the sub-scanning direction are positioned at positions shifted in the main scanning direction, the plurality of first nozzles include a first continuous nozzle group that is continuous in the sub-scanning direction and a second continuous nozzle group that is continuous in the sub-scanning direction, the test pattern includes a first pattern group resulting from liquid ejection from the first continuous nozzle group and a second pattern group resulting from liquid ejection from the second continuous nozzle group, The control unit controls the formation of the test pattern in which at least the first pattern group and the second pattern group are aligned in the main scanning direction by performing the sub-scan between the formation of the first pattern group and the formation of the second pattern group.

2. the plurality of first nozzles further include a third continuous nozzle group that is continuous in the sub-scanning direction and a fourth continuous nozzle group that is continuous in the sub-scanning direction, the test patterns include the first pattern group, the second pattern group, a third pattern group resulting from liquid ejection from the plurality of third continuous nozzles, and a fourth pattern group resulting from liquid ejection from the plurality of fourth continuous nozzles; In the test pattern, the number of pattern groups resulting from liquid ejection from the first nozzle row is four, 2. The recording device according to claim 1, wherein the control unit performs the sub-scan between the formation of the second pattern group and the formation of the third pattern group, and performs the sub-scan between the formation of the third pattern group and the formation of the fourth pattern group, thereby controlling the formation of the test pattern in which at least the first pattern group, the second pattern group, the third pattern group, and the fourth pattern group are arranged in the main scanning direction.

3. the recording head has a second nozzle row aligned with the first nozzle row, the second nozzle row including a plurality of second nozzles arranged therein; the plurality of second nozzles include a first continuous color nozzle group in which a plurality of first color nozzles capable of ejecting a liquid of a first color onto the medium are arranged in succession, a second continuous color nozzle group in which a plurality of second color nozzles capable of ejecting a liquid of a second color onto the medium are arranged in succession, and a third continuous color nozzle group in which a plurality of third color nozzles capable of ejecting a liquid of a third color onto the medium are arranged in succession, the test patterns include a first color pattern group resulting from liquid ejection from the first continuous color nozzle group, a second color pattern group resulting from liquid ejection from the second continuous color nozzle group, and a third color pattern group resulting from liquid ejection from the third continuous color nozzle group, 3. The recording apparatus according to claim 1, wherein the control unit controls to form the test pattern in which at least the first pattern group, the second pattern group, and the first color pattern group are arranged in the main scanning direction.

4. the recording head has a second nozzle row aligned with the first nozzle row, the second nozzle row including a plurality of second nozzles arranged therein; the plurality of second nozzles include a fifth continuous nozzle group that is continuous in the sub-scanning direction and a sixth continuous nozzle group that is continuous in the sub-scanning direction, the test patterns include a fifth pattern group resulting from liquid ejection from the fifth continuous nozzle group and a sixth pattern group resulting from liquid ejection from the sixth continuous nozzle group, 3. The recording device according to claim 1, wherein the control unit controls the formation of the test pattern in which at least the first pattern group, the second pattern group, the fifth pattern group, and the sixth pattern group are arranged in the main scanning direction by performing the sub-scan between the formation of the fifth pattern group and the formation of the sixth pattern group.

5. the test pattern includes a plurality of pattern groups including the first pattern group and the second pattern group; 3. The recording device according to claim 1, wherein the control unit controls the formation of the test pattern in which the plurality of pattern groups are arranged in the main scanning direction so that the position in the sub-scanning direction of each of the individual patterns included in each of the pattern groups matches the position in the sub-scanning direction of any of the individual patterns included in the other pattern groups.

6. A test pattern forming method for forming a test pattern by performing a main scan in which a recording head having a first nozzle row in which a plurality of first nozzles capable of ejecting liquid onto a medium are arranged is moved along a main scan direction intersecting with the arrangement direction of the plurality of first nozzles, and a sub scan in which at least one of the medium and the recording head is moved along a sub scan direction intersecting with the main scan direction, the test pattern includes a plurality of individual patterns along the main scanning direction formed by liquid ejection from each of the plurality of first nozzles, the individual patterns adjacent to each other in the sub-scanning direction are positioned at positions shifted in the main scanning direction, the plurality of first nozzles include a first continuous nozzle group that is continuous in the sub-scanning direction and a second continuous nozzle group that is continuous in the sub-scanning direction, The test pattern forming method includes: a first pattern group forming step of forming a first pattern group on the medium by ejecting the liquid from the first continuous nozzle group; a second pattern group forming step of forming a second pattern group on the medium by ejecting the liquid from the second continuous nozzle group; a sub-scanning step of performing the sub-scanning so that the first pattern group and the second pattern group are aligned in the main scanning direction.

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