Inkjet printer

Abstract

To determine whether or not a discharge failure of a nozzle occurs with a simple method.SOLUTION: A printer 10 includes: an ink head 40 and an optical sensor 38 which is mounted on a carriage 17; and a control device 80. The control device 80 includes: a mark formation section 82 which causes all nozzles 41 of each nozzle array 45 to discharge an ink to form marks 50 so that one rectangular mark 50 is painted and formed for one nozzle array 45; a detection section 84 which moves a recording medium 5 formed with the marks 50 relative to the optical sensor 38 to detect an end number N which is the number of ends T in a scanning direction X of each mark 50, based on a first light receiving amount of light reflected on the recording medium 5 and a second light receiving amount of light reflected on the mark 50; and a determination part 86 which determines that a discharge failure occurs in the nozzles 41 when the end number N is larger than a first value.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] Inkjet printers that print images on recording media using an inkjet method have been known for some time. This type of inkjet printer includes, for example, a mounting table on which a recording medium is placed while being transported in a sub-scanning direction, and an ink head having multiple nozzles that eject ink onto the recording medium placed on the mounting table and movable in a main scanning direction intersecting the sub-scanning direction. If any of the multiple nozzles becomes clogged, ejection defects such as a reduction in the amount of ink ejected from the nozzle or no ink ejection from the nozzle may occur. If a nozzle fails to eject ink properly due to a nozzle ejection defect, the quality of the formed image will be reduced. For example, Patent Document 1 discloses a method for inspecting for clogged nozzles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-47652 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method described in Patent Document 1 requires a scanner to capture an image of the printed test pattern in order to check for the presence or absence of clogged nozzles, which increases costs and the risk of the printer becoming larger. Also, because the presence or absence of clogged nozzles is calculated by image processing, control becomes complicated and, depending on the image resolution, etc., it may not be possible to accurately check for the presence or absence of clogged nozzles.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide an inkjet printer that can determine whether or not there is a nozzle ejection defect using a simple method. [Means for solving the problem]

[0006] The inkjet printer according to the present invention comprises: a mounting table on which a recording medium is placed; an ink head having a nozzle array including a plurality of nozzles arranged in a sub-scanning direction and configured to eject ink onto the recording medium placed on the mounting table; and a nozzle surface on which the nozzles are formed; a carriage on which the ink head is mounted and which is movable in the main scanning direction; an optical sensor mounted on the carriage and which irradiates light and receives reflected light; a movement mechanism which moves the recording medium in the sub-scanning direction; and a control device. The control device includes a mark forming unit that ejects ink from all the nozzles in each nozzle row to form the mark so that one rectangular mark or at least two marks that are mutually biased in the main scanning direction and the sub-scanning direction are formed by filling in one nozzle row; a detection unit that moves the recording medium on which the mark has been formed in the sub-scanning direction relative to the optical sensor, and detects the number of ends, which is the number of ends of the mark in the sub-scanning direction, based on a first received amount of light reflected by the recording medium and a second received amount of light reflected by the mark; and a judgment unit that judges that an ejection defect has occurred in the nozzle if the number of ends is greater than a first value.

[0007] In the inkjet printer according to the present invention, the mark forming unit is configured to, for example, eject ink from all nozzles in each nozzle row to form a single rectangular mark. If no nozzles in the nozzle row are clogged, the rectangular mark is formed as a single mark without any gaps in the sub-scanning direction (i.e., lines extending in the main scanning direction). On the other hand, if some nozzles in the nozzle row are clogged, ink is not properly ejected from the nozzles, resulting in gaps in the rectangular mark in the sub-scanning direction. Since ink is properly ejected from the other nozzles to fill in the mark, multiple rectangular marks aligned in the sub-scanning direction are formed instead of a single rectangular mark. The detection unit also moves the recording medium on which the mark is formed in the sub-scanning direction relative to the optical sensor. Because the first light amount of light reflected from the recording medium is different from the second light amount of light reflected from the mark, the optical sensor can detect the boundary between the mark and the recording medium, i.e., the edge of the mark in the sub-scanning direction, by passing through the mark. If no gaps occur in the rectangular mark, the number of edges is two. However, the number of edges increases as the number of edges increases. Therefore, the determination unit determines that a nozzle has an ejection defect if the number of ends is greater than a first value. In this way, by forming a rectangular mark using all nozzles and detecting the number of ends of the mark, it is possible to easily determine whether a nozzle has an ejection defect. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an inkjet printer that can determine whether or not there is a nozzle ejection defect using a simple method. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view illustrating an inkjet printer according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a schematic configuration of a lower surface of a carriage according to an embodiment. [Figure 3]FIG. 2 is a diagram showing the configuration of the vicinity of a capping unit according to an embodiment, and is a front view showing a state in which caps are removed from ink heads. [Figure 4] FIG. 2 is a diagram showing the configuration of the capping unit and its surroundings according to an embodiment, and is a front view showing a state in which a cap is attached to an ink head. [Figure 5] FIG. 2 is a block diagram of a control system of a printer according to an embodiment. [Figure 6] 10 is a flowchart showing a procedure for checking whether or not there is a discharge defect in the nozzles of the ink head. [Figure 7A] FIG. 10 is a schematic diagram showing a state in which a rectangular mark is partially formed. [Figure 7B] FIG. 10 is a schematic diagram showing a state in which another part of the rectangular mark is formed. [Figure 8] This is an example of a test pattern in which rectangular marks are arranged in the main scanning direction. [Figure 9] FIG. 2 is a schematic diagram showing a movement path of an optical sensor. [Figure 10A] FIG. 10 is a schematic diagram showing an example of a movement path of an optical sensor when detecting an edge of a properly formed mark. [Figure 10B] FIG. 10 is a schematic diagram showing an example of a movement path of an optical sensor when detecting an edge of an improperly formed mark. [Figure 11A] FIG. 10 is a schematic diagram showing another example of the movement path of the optical sensor when detecting the edge of a properly formed mark. [Figure 11B] FIG. 10 is a schematic diagram showing another example of the movement path of the optical sensor when detecting the edge of an improperly formed mark. [Figure 12A] FIG. 10 is a schematic diagram showing a modified example in which a part of a rectangular mark is formed. [Figure 12B] FIG. 10 is a schematic diagram showing a modified example in which another part of the rectangular mark is formed. [Figure 13] This is a modified example of a test pattern in which rectangular marks are arranged in the main scanning direction. [Figure 14] FIG. 10 is a schematic diagram showing a modified example of the movement path of the optical sensor. [Figure 15A] FIG. 10 is a schematic diagram showing another example of the movement path of the optical sensor when detecting the edge of a properly formed mark. [Figure 15B] FIG. 10 is a schematic diagram showing another example of the movement path of the optical sensor when detecting the edge of an improperly formed mark. [Figure 16] FIG. 10 is a schematic diagram showing a movement path of an optical sensor when a mark is formed on an underlayer. DETAILED DESCRIPTION OF THE INVENTION

[0010] An inkjet printer (hereinafter simply referred to as "printer") according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Furthermore, members and parts that perform the same function are given the same reference numerals, and duplicate descriptions will be omitted or simplified as appropriate.

[0011] FIG. 1 is a front view of a printer 10 according to this embodiment. In the following description, the symbols F, Rr, L, R, U, and D in the drawings represent the front, rear, left, right, top, and bottom, respectively, when the printer 10 is viewed from the front. The symbol Y in the drawings indicates the main scanning direction, and the symbol X (see FIG. 2) in the drawings indicates the sub-scanning direction. In this embodiment, the main scanning direction Y is the left-right direction. The sub-scanning direction X is the front-to-back direction, which is perpendicular to the main scanning direction Y in a plan view. The forward direction Y1 indicates the direction from right to left in the main scanning direction Y, the return direction Y2 indicates the direction from left to right in the main scanning direction Y, the forward direction X1 indicates the direction from upstream to downstream in the sub-scanning direction X (here, the direction from back to front), and the return direction X2 indicates the direction from downstream to upstream in the sub-scanning direction X (here, the direction from front to back). However, these directions are merely defined for the convenience of explanation, and do not limit the installation mode of the printer 10 or the present invention in any way.

[0012] As shown in FIG. 1, the printer 10 prints on a recording medium 5. The recording medium 5 is, for example, recording paper. However, the recording medium 5 is not limited to recording paper. The recording medium 5 may be paper such as plain paper or inkjet printing paper, or may be a sheet or film made of resin such as polyvinyl chloride or polyester, fabric such as woven fabric or nonwoven fabric, or other medium. The recording medium 5 is, for example, white.

[0013] As shown in FIG. 1, the printer 10 includes a printer main body 10A, a platen 13, a guide rail 15, a carriage 17, a moving mechanism 20, a head moving mechanism 30, an optical sensor 38, an ink head 40 (see FIG. 2), a capping unit 60, and a control device 80.

[0014] The printer main body 10A has a casing that extends in the main scanning direction Y. The recording medium 5 is placed on a platen 13. With the recording medium 5 placed on the platen 13, printing is performed on the recording medium 5 on the platen 13. The platen 13 extends in the main scanning direction Y and the sub-scanning direction X. The platen 13 is an example of a mounting table.

[0015] The movement mechanism 20 moves the recording medium 5 placed on the platen 13 in the sub-scanning direction X. The configuration of the movement mechanism 20 is not particularly limited. In this embodiment, the movement mechanism 20 includes a pinch roller 21, a grit roller 22, and a feed motor 23. The pinch roller 21 is disposed above the platen 13 and below the guide rail 15, and presses down on the recording medium 5 from above. The grit roller 22 is provided on the platen 13 with its upper portion exposed above the platen 13. The grit roller 22 faces the pinch roller 21. Note that the installation positions and number of the pinch roller 21 and the grit roller 22 are not particularly limited. In this embodiment, as shown in FIG. 1, the pinch roller 21 and the grit roller 22 are disposed at the left and right ends of the platen 13, respectively.

[0016] Here, a feed motor 23 is connected to the grit roller 22. When the feed motor 23 is driven while the recording medium 5 is sandwiched between the pinch roller 21 and the grit roller 22, the grit roller 22 rotates. As a result, the recording medium 5 is transported in the sub-scanning direction X. The feed motor 23 is controlled by a control device 80.

[0017] The guide rail 15 is disposed above the platen 13. The guide rail 15 is disposed parallel to the platen 13 and extends in the main scanning direction Y. A carriage 17 is engaged with the guide rail 15. The carriage 17 is provided slidably on the guide rail 15.

[0018] The head moving mechanism 30 is a mechanism that moves the carriage 17, the ink head 40 (see FIG. 2), and the optical sensor 38 in the main scanning direction Y. The configuration of the head moving mechanism 30 is not particularly limited. In this embodiment, the head moving mechanism 30 includes a left pulley 31a, a right pulley 31b, a belt 32, and a carriage motor 33. The left pulley 31a is provided near the left end of the guide rail 15. The right pulley 31b is provided near the right end of the guide rail 15. The belt 32 is, for example, endless, and is wound around the left pulley 31a and the right pulley 31b. The carriage 17 is attached and fixed to the belt 32.

[0019] A carriage motor 33 is connected to the right pulley 31b. When the carriage motor 33 is driven, the right pulley 31b rotates, and the belt 32 runs between the left pulley 31a and the right pulley 31b. This causes the carriage 17, ink head 40, and optical sensor 38 to move in the main scanning direction Y along the guide rail 15. The carriage motor 33 is controlled by a control device 80.

[0020] As shown in FIG. 2, the carriage 17 is equipped with multiple ink heads 40. The ink heads 40 eject ink onto the recording medium 5 placed on the platen 13. Each ink head 40 is connected to an ink cartridge (not shown) housed inside the printer main body 10A via a flexible ink tube (not shown). The ink cartridges house, for example, process color ink, white ink, gloss ink, and primer ink. Examples of process color inks include cyan ink, magenta ink, yellow ink, black ink, light cyan ink, and light magenta ink.

[0021] As shown in FIG. 2, the ink heads 40 include a first ink head 40A, a second ink head 40B, a third ink head 40C, and a fourth ink head 40D. The first ink head 40A to the fourth ink head 40D are mounted on a carriage 17. The first ink head 40A to the fourth ink head 40D are aligned in the main scanning direction Y. The first ink head 40A to the fourth ink head 40D are aligned in the sub-scanning direction X. The first ink head 40A to the fourth ink head 40D may be aligned in positions offset from one another in the sub-scanning direction X. The first ink head 40A to the fourth ink head 40D are formed so that the length in the sub-scanning direction X is longer than the length in the main scanning direction Y. The first ink head 40A to the fourth ink head 40D are formed to have the same shape and size. The first ink head 40A to the fourth ink head 40D each have a plurality of nozzles 41 aligned in the sub-scanning direction X, and a nozzle surface 44 on which the nozzles 41 are formed. The nozzles 41 eject ink onto the recording medium 5 placed on the platen 13. A negative pressure (a pressure lower than atmospheric pressure) is set inside the nozzles 41.

[0022] As shown in FIG. 2, in the first ink head 40A to the fourth ink head 40D, a plurality of nozzles 41 are aligned in a line in the sub-scanning direction X to form a first nozzle row 42 and a second nozzle row 43. The first nozzle row 42 is located to the left of the second nozzle row 43. Hereinafter, the first nozzle row 42 and the second nozzle row 43 may be collectively referred to as a nozzle row 45. The first nozzle row 42 and the second nozzle row 43 each include an upstream nozzle row 46A in which some of the nozzles 41 are aligned in the sub-scanning direction X, a central nozzle row 46B located downstream (forward here) of the upstream nozzle row 46A in the sub-scanning direction and in which some of the nozzles 41 are aligned in the sub-scanning direction X, and a downstream nozzle row 46C located downstream (forward here) of the central nozzle row 46B in the sub-scanning direction and in which some of the nozzles 41 are aligned in the sub-scanning direction X. In this embodiment, the number of nozzles 41 in the upstream nozzle row 46A is the same as the number of nozzles 41 in the central nozzle row 46B, and the number of nozzles 41 in the downstream nozzle row 46C. In this embodiment, for example, cyan ink is ejected from the nozzles 41 of the first ink head 40A, magenta ink is ejected from the nozzles 41 of the second ink head 40B, yellow ink is ejected from the nozzles 41 of the third ink head 40C, and black ink is ejected from the nozzles 41 of the fourth ink head 40D. Note that while FIG. 2 illustrates 12 nozzles 41 per nozzle row 45 in the ink head 40, in reality, many more nozzles (e.g., 180) are formed. However, the number of nozzles 41 is not limited in any way. Also, in this embodiment, the printer 10 has four ink heads 40, but the number of ink heads 40 is not limited to three. Furthermore, the ink head 40 has two nozzle rows 45 (here, a first nozzle row 42 and a second nozzle row 43), but the number of nozzle rows 45 may be one or three or more.

[0023] The optical sensor 38 is provided so as to be movable in the main scanning direction Y over the recording medium 5 placed on the platen 13. The optical sensor 38 is mounted on the carriage 17. In this embodiment, the optical sensor 38 is provided to the left of the ink head 40, but it may be provided to the right. The optical sensor 38 irradiates light and receives reflected light. The optical sensor 38 irradiates light onto the recording medium 5 and receives light reflected by the recording medium 5. The optical sensor 38 irradiates light onto marks 50 (see FIG. 8 ) formed on the recording medium 5, which will be described later, and receives light reflected by the marks 50. The type of the optical sensor 38 is not particularly limited, but examples include a reflective photosensor. In this embodiment, the optical sensor 38 is a color sensor (typically a color sensor that measures RGB values). The optical sensor 38 is connected to the control device 80.

[0024] Next, we will explain the capping unit 60 according to this embodiment. The capping unit 60 prevents the nozzles 41 of the ink head 40 from drying out by attaching a cap 70 (see FIG. 3), which will be described later, to the ink head 40. Furthermore, to prevent the nozzles 41 from clogging, the capping unit 60 forcibly discharges ink from inside the nozzles 41 into the cap 70 using a suction pump 68, which will be described later.

[0025] As shown in FIG. 1, the capping unit 60 is provided inside the printer main body 10A. The capping unit 60 is located to the right of the platen 13. As shown in FIG. 3, the capping unit 60 includes four caps 70 that can be attached to and detached from the ink heads 40, a cap movement mechanism 63, and a suction pump 68. The caps 70 and the cap movement mechanism 63 are located at a home position HP located at the right end of the guide rail 15 (see FIG. 1). Here, the home position HP is the position where the carriage 17, ink heads 40, and optical sensor 38 wait when waiting to print, i.e., when no printing is being performed. However, the location of the home position HP is not particularly limited and may be the left end of the guide rail 15.

[0026] As shown in FIG. 3, the caps 70 are lined up in the main scanning direction Y. The caps 70 are formed in a shape such that the length in the sub-scanning direction X is longer than the length in the main scanning direction Y. The caps 70 are formed to be detachable from the ink heads 40 so as to cover the nozzle faces 44 (see FIG. 2) of the ink heads 40. Note that "covering the nozzle faces 44" is not limited to covering the entire nozzle face 44, but also includes covering at least the entire first nozzle row 42 and the entire second nozzle row 43. Ink is ejected onto the caps 70 from the nozzles 41 of the ink heads 40.

[0027] As shown in FIG. 3, the cap moving mechanism 63 supports the cap 70. The cap moving mechanism 63 moves the cap 70 so that the cap 70 can be attached to and detached from the ink head 40. In this embodiment, the cap moving mechanism 63 moves the cap 70 in the up and down direction. The configuration of the cap moving mechanism 63 is not particularly limited, but may include, for example, a drive motor 63A. By driving the drive motor 63A, the cap moving mechanism 63 moves the cap 70 in the up and down direction. The cap moving mechanism 63 moves the cap 70 upward to the cap position CP (see FIG. 4). Here, the cap position CP is a position where the cap 70 covers the nozzle surface 44 of the ink head 40. In this way, the cap 70 is attached to each ink head 40. When the cap 70 is attached to each ink head 40, a sealed space 67 (see FIG. 4) is formed between the cap 70 and the nozzle surface 44. When printing starts, the cap moving mechanism 63 moves the cap 70 downward, thereby moving the cap 70 from the cap position CP (see FIG. 4) to the separated position DP (see FIG. 3). Here, the separated position DP is a position where the cap 70 is separated from the nozzle surface 44. In this way, the cap 70 is detached from each ink head 40.

[0028] When the caps 70 are attached to the ink head 40, the suction pump 68 performs a suction operation to suck in fluid (e.g., ink) from the sealed space 67 and eject the ink from the nozzles 41 (see FIG. 2). By driving the suction pump 68, the pressure inside the sealed space 67 becomes lower than atmospheric pressure (i.e., negative pressure). As a result, ink is forcibly discharged from the nozzles 41 of the ink head 40. The suction port of the suction pump 68 is connected to the four caps 70 via flexible tubes 65. The discharge port of the suction pump 68 is connected to a waste liquid tank 69. The fluid in the sealed space 67 sucked by the suction pump 68 is stored in the waste liquid tank 69. The suction pump 68 is controlled by a control device 80 (see FIG. 1).

[0029] 1, an operation panel 18 is provided on the right end of the printer main body 10A. The operation panel 18 is provided with a display unit (not shown) that displays the printer status and input keys (not shown) that are operated by the user. The operation panel 18 is connected to a control device 80 that controls various operations of the printer 10.

[0030] As shown in FIG. 5, the overall operation of the printer 10 is controlled by a control device 80. The configuration of the control device 80 is not particularly limited. The control device 80 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but it may include, for example, an interface (I / F) that receives print data and the like from an external device such as a host computer, a central processing unit (CPU) that executes instructions from a control program, a read-only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as a memory that stores programs and various data. As shown in FIG. 1, the control device 80 is provided inside the printer main body 10A. However, the control device 80 does not have to be provided inside the printer main body 10A. For example, the control device 80 may be a computer installed outside the printer 10. In this case, the control device 80 is connected to the printer 10 via a wired or wireless connection so as to be able to communicate with the printer 10.

[0031] As shown in FIG. 5, the control device 80 is communicably connected to the operation panel 18, ink head 40, carriage motor 33, feed motor 23, optical sensor 38, drive motor 63A, and suction pump 68, and controls these.

[0032] As shown in FIG. 5, the control device 80 includes a mark forming unit 82, a detecting unit 84, a determining unit 86, a first cleaning operation unit 88, a second cleaning operation unit 90, a notifying unit 92, and an identifying unit 94. The functions of each unit of the control device 80 are realized by a program. This program is written, for example, from a PC via a LAN to a ROM mounted on a circuit board inside the printer 10, or written from a PC to an FPGA mounted on a circuit board inside the printer 10 using a dedicated writing tool. This program is downloaded to the PC via the Internet, for example. The functions of each unit of the control device 80 may also be realized by a processor and / or circuit. The specific functions of these units will be described later.

[0033] Next, a method for checking for ejection defects in the nozzles 41 of the ink head 40 will be described. Figure 6 is a flowchart showing the procedure for checking for ejection defects in the nozzles 41 of the ink head 40 by printing a test pattern including predetermined marks on the recording medium 5 before printing begins. Here, the description will be given taking as an example a case where one rectangular mark is formed for each of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A to the fourth ink head 40D.

[0034] First, in step S10, the mark forming unit 82 ejects ink from all the nozzles 41 in each of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A to the fourth ink head 40D to form a rectangular mark 50 (see FIG. 8). The mark forming unit 82 ejects ink from all the nozzles 41 in each of the first nozzle row 42 and the second nozzle row 43 so that one mark 50 is formed by filling in one of the first nozzle row 42 and the second nozzle row 43.

[0035] For example, as shown in FIG. 7A, the mark forming unit 82 ejects ink from all nozzles 41 in each of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A to the fourth ink head 40D while moving the carriage 17 in the forward direction Y1 of the main scanning direction Y, thereby forming a portion 50A of the mark 50. Here, the length of the portion 50A of the mark 50 in the sub-scanning direction X is defined as the length of one pass. As shown in FIG. 7A, a single rectangular mark 50 is not formed by simply moving the carriage 17 once in the forward direction Y1 of the main scanning direction Y. Therefore, as shown in FIG. 7B, after the portion 50A of the mark 50 is formed, the carriage 17 is moved in the return direction Y2 of the main scanning direction Y, and the recording medium 5 is moved in the forward direction X1 of the sub-scanning direction X by the length of one pass. Thereafter, the carriage 17 is moved in the forward direction Y1 of the main scanning direction Y to form another portion 50B of the mark 50. The length of one portion 50A of the mark 50 in the sub-scanning direction X is the same as the length of the other portion 50B of the mark 50 in the sub-scanning direction X. By repeatedly performing the above control, a test pattern 50P is formed on the recording medium 5, in which rectangular marks 50 formed by filling in each other are arranged in the main scanning direction Y, as shown in FIG. 8. In this example, one mark 50 is formed by filling in each other (solid color) by moving the carriage 17 back and forth four times in the main scanning direction Y (i.e., four passes). That is, when forming the mark 50, the recording medium 5 is moved in the sub-scanning direction X by the length LX (see FIG. 2) between adjacent nozzles 41. The mark forming unit 82 controls the amount and timing of ink ejection from the nozzles 41 of the ink head 40, the movement of the carriage 17 in the main scanning direction Y, and the movement of the recording medium 5 in the sub-scanning direction X. That is, the mark forming unit 82 controls the first ink heads 40A to 40D, the carriage motor 33, and the feed motor 23. Before forming the mark 50, it is advisable to perform so-called waste printing, in which ink is ejected from all nozzles 41 in the nozzle rows 45 of the first ink head 40A to the fourth ink head 40D onto one location on the recording medium 5 (for example, the right end of the recording medium 5).

[0036] 8, the test pattern 50P includes a first mark 51 formed by the nozzles 41 of the first nozzle row 42 of the first ink head 40A, a second mark 52 formed by the nozzles 41 of the second nozzle row 43 of the first ink head 40A, a third mark 53 formed by the nozzles 41 of the first nozzle row 42 of the second ink head 40B, a fourth mark 54 formed by the nozzles 41 of the second nozzle row 43 of the second ink head 40B, a fifth mark 55 formed by the nozzles 41 of the first nozzle row 42 of the third ink head 40C, a sixth mark 56 formed by the nozzles 41 of the second nozzle row 43 of the third ink head 40C, a seventh mark 57 formed by the nozzles 41 of the first nozzle row 42 of the fourth ink head 40D, and an eighth mark 58 formed by the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D. Here, the first mark 51 and the second mark 52 are formed with cyan ink. The third mark 53 and the fourth mark 54 are formed with magenta ink. The fifth mark 55 and the sixth mark 56 are formed with yellow ink. The seventh mark 57 and the eighth mark 58 are formed with black ink. The first mark 51 is an example of a first color mark. The third mark 53 is an example of a second color mark.

[0037] In step S20, the detection unit 84 detects the number of end portions N, which is the number of end portions T of the marks 50 in the sub-scanning direction X. The number of end portions N is, for example, the total number of end portions T of all marks 50 in the test pattern 50P. Note that the number of end portions N may also be the number of end portions T for each mark 50. The detection unit 84 moves the recording medium 5 on which the marks 50 are formed relative to the optical sensor 38 (see FIG. 2) in the sub-scanning direction X, and detects the number of end portions N based on a first received amount of light reflected by the recording medium 5 and a second received amount of light reflected by the marks 50. As shown in FIG. 9, the detection unit 84 controls the movement of the carriage 17 in the forward direction Y1 in the main scanning direction Y and the movement of the recording medium 5 in the forward direction X1 and return direction X2 in the sub-scanning direction X so that the optical sensor 38 moves along a movement path 38P indicated by the two-dot chain line in FIG. 9. That is, the detection unit 84 controls the optical sensor 38, the carriage motor 33, and the feed motor 23. For example, the detection unit 84 is configured to move the recording medium 5 a first distance in the forward direction X1 or the return direction X2 relative to one mark 50 with respect to the optical sensor 38, and then move the carriage 17 a second distance in the forward direction Y1 of the main scanning direction Y. Here, the first distance is a distance longer than the length of the mark 50 in the sub-scanning direction X, and the second distance is, for example, the distance in the main scanning direction Y between the adjacent first nozzle row 42 and second nozzle row 43. For example, the detection unit 84 controls the optical sensor 38 so that it passes over the marks 50 sequentially from right to left in the main scanning direction Y (i.e., in the forward direction Y1). Note that the detection unit 84 may also control the optical sensor 38 so that it passes over the marks 50 sequentially from left to right in the main scanning direction Y. In the example shown in FIG. 9, the optical sensor 38 first irradiates light toward the eighth mark 58 and last irradiates light toward the first mark 51. The light irradiated from the optical sensor 38 onto the mark 50 varies depending on the color of the mark 50. Here, the light irradiated from the optical sensor 38 is red for the first mark 51 and the second mark 52, green for the third mark 53 and the fourth mark 54, blue for the fifth mark 55 and the sixth mark 56, and red for the seventh mark 57 and the eighth mark 58. The light irradiated from the optical sensor 38 onto the mark 50 may be, for example, a complementary color to the color of the mark 50.The light irradiated from the optical sensor 38 onto the mark 50 may be the same color regardless of the color of the mark 50 .

[0038] 10A is a schematic diagram showing a normal rectangular eighth mark 58 formed by the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D. As shown in FIG. 10A, when the optical sensor 38 passes over the eighth mark 58 along the movement path 38P, the optical sensor 38 moves in the following order: recording medium 5, 8th mark 58, and recording medium 5. Here, the first received amount of light reflected by the recording medium 5 is different from the second received amount of light reflected by the 8th mark 58, so the optical sensor 38 detects the end T of the 8th mark 58 based on the change between the first received amount and the second received amount of light (i.e., the change in voltage). The end T is the boundary between the recording medium 5 and the eighth mark 58 (mark 50). In the example shown in FIG. 10A, the end T includes an end T1 on the front side of the eighth mark 58 and an end T2 on the rear side thereof. That is, the number of end portions N is 2. In this way, if the eighth mark 58 is formed normally, the number of end portions N when the optical sensor 38 moves once over the eighth mark 58 in the sub-scanning direction X is 2.

[0039] FIG. 10B is a schematic diagram showing an abnormal rectangular eighth mark 58 formed by a nozzle 41 of the second nozzle row 43 of the fourth ink head 40D. As shown in FIG. 10B, when a discharge defect occurs in a nozzle 41 of the second nozzle row 43 of the fourth ink head 40D, the eighth mark 58 is not a single rectangular mark, but rather multiple rectangular marks aligned in the sub-scanning direction X. That is, a gap (a line extending in the main scanning direction Y) is formed in the eighth mark 58. Therefore, when the optical sensor 38 passes over the eighth mark 58 along the movement path 38P, the optical sensor 38 moves in the following order: the recording medium 5, a portion of the eighth mark 58, the recording medium 5, another portion of the eighth mark 58, and the recording medium 5. In the example shown in FIG. 10B, the end T includes a front end T3 and a rear end T4 of the portion of the eighth mark 58, and a front end T5 and a rear end T6 of the other portion of the eighth mark 58. That is, the number of end N is four. In this way, if the eighth mark 58 is not formed normally, the number of end portions N when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58 will be 4 or more.

[0040] In step S30, the determination unit 86 determines whether the number of end portions N is greater than a first value. If the number of end portions N is greater than the first value, the determination unit 86 determines that a discharge defect has occurred in the nozzle 41. In this case, the process proceeds to step S40. The first value may be set for each mark 50, or may be set for the entire test pattern 50P. The first value is, for example, 2. In the example shown in FIG. 10B, the determination unit 86 determines that a discharge defect has occurred in the nozzle 41 if the number of end portions N is 4 or greater. The identification unit 94 identifies the nozzle row in which the determination unit 86 determines that a discharge defect has occurred in the nozzle 41. For example, in the example shown in FIG. 10B, the identification unit 94 identifies that a discharge defect has occurred in the nozzle 41 of the second nozzle row 43 of the fourth ink head 40D. The identification unit 94 can identify which nozzle 41 of the nozzle row 45 is experiencing a discharge defect, based on the number of times the recording medium 5 moves in the sub-scanning direction X and the number of times the carriage 17 moves in the main scanning direction (the position of the carriage 17 in the main scanning direction Y) when the optical sensor 38 detects the number N of end portions of the mark 50. On the other hand, the determination unit 86 determines that no discharge defect is occurring in the nozzle 41 when the number N of end portions is less than or equal to the first value. Then, the control for checking whether or not the nozzle 41 has a discharge defect is terminated.

[0041] In step S40, when the determination unit 86 determines that a discharge defect has occurred in a nozzle 41, the notification unit 92 notifies the user that a discharge defect has occurred in the nozzle 41. The notification method used by the notification unit 92 is not particularly limited, and examples include notification by visual display, audio, etc. In this embodiment, the notification unit 92 notifies the user visually via the operation panel 18. The notification unit 92 may, for example, notify the user of the ink head 40 and its nozzle row 45 in which a discharge defect has occurred in a nozzle 41.

[0042] In step S50, the judgment unit 86 judges whether the number of end portions N is equal to or greater than a second value. The second value is greater than the first value. If the number of end portions N is equal to or greater than the second value, the judgment unit 86 judges that at least a flushing operation is necessary. In this case, the process proceeds to step S60. On the other hand, if the number of end portions N is less than the second value, the judgment unit 86 judges that although ejection defects have occurred in some of the nozzles 41, this has little effect on print quality and therefore a flushing operation and a suction operation are unnecessary. Then, the control for checking whether or not there is an ejection defect in the nozzles 41 ends.

[0043] In step S60, the judgment unit 86 judges whether the number of end portions N is equal to or greater than a third value. The third value is greater than the second value. If the number of end portions N is equal to or greater than the third value, the judgment unit 86 judges that a flushing operation and a suction operation are necessary. In this case, the process proceeds to step S70. On the other hand, if the number of end portions N is less than the third value, the judgment unit 86 judges that ejection defects have occurred in some of the nozzles 41, but that clogging of the nozzles 41 can be cleared by the flushing operation alone. In this case, the process proceeds to step S80.

[0044] In step S70, the first cleaning operation unit 88 performs a flushing operation to eject ink from the nozzles 41. When the flushing operation is performed, a cap 70 is typically placed directly below the nozzles 41, and ink ejected from the nozzles 41 is contained in the cap 70. In this embodiment, the flushing operation is performed with the cap 70 attached to the ink head 40. The first cleaning operation unit 88 controls the ink head 40 and the drive motor 63A. The second cleaning operation unit 90 then performs a suction operation to suck fluid from the sealed space 67 using the suction pump 68, forcibly ejecting ink from the nozzles 41. This can clear clogging of the nozzles 41. When the suction operation is performed, the cap 70 is typically attached to the ink head 40. The second cleaning operation unit 90 controls the ink head 40, the drive motor 63A, and the suction pump 68.

[0045] In step S80, the first cleaning operation unit 88 executes a flushing operation to eject ink from the nozzles 41. This can clear clogging of the nozzles 41.

[0046] In step S20 described above, the optical sensor 38 is configured to move once in the sub-scanning direction X relative to one mark 50, as shown by the movement path 38P in FIG. 9 . However, this is not limiting. For example, the detection unit 84 may be configured to move the recording medium 5 a first distance in the forward direction X1 relative to one mark 50, and then move the recording medium 5 a first distance in the return direction X2 relative to the optical sensor 38 (the forward direction X1 and the return direction X2 may be reversed), and then move the carriage 17 a second distance in the forward direction Y1 of the main scanning direction Y. For example, as shown in FIG. 11A , the optical sensor 38 may be configured to move twice in the sub-scanning direction X relative to one mark 50 (i.e., one reciprocating movement). In FIGS. 11A and 11B, the movement path 38Q of the optical sensor 38 is indicated by a two-dot chain line. In the example shown in FIG. 11A , the number of end portions N is 4. In this way, if the eighth mark 58 is formed normally, the number of end portions N when the optical sensor 38 moves back and forth once in the sub-scanning direction X over the eighth mark 58 is 4. On the other hand, in the example shown in FIG. 11B, the number of end portions N is 8. In this way, if the eighth mark 58 is not formed normally, the number of end portions N when the optical sensor 38 moves back and forth once in the sub-scanning direction X over the eighth mark 58 is 8 or more. In the example shown in FIG. 11B, if the number of end portions N is 8 or more, the determination unit 86 determines that an ejection defect has occurred in the nozzle 41.

[0047] As described above, in the printer 10 of this embodiment, the mark forming unit 82 is configured to, for example, eject ink from all nozzles 41 in each nozzle row 45 to form one rectangular mark 50. If no nozzles 41 in the nozzle row 45 are clogged, the rectangular mark 50 is formed as a single mark 50 without any gaps in the sub-scanning direction X (i.e., lines extending in the main scanning direction X). On the other hand, if some nozzles 41 in the nozzle row 45 are clogged, ink is not properly ejected from the nozzles 41, resulting in gaps in the rectangular mark 50 in the sub-scanning direction X. Note that, because ink is properly ejected from the other nozzles 41 to fill in the gap, multiple rectangular marks 50 aligned in the sub-scanning direction X are formed, even though a single rectangular mark 50 was intended to be formed. The detection unit 84 also moves the recording medium 5 on which the mark 50 has been formed in the sub-scanning direction X relative to the optical sensor 38. Here, because the first light amount of light reflected by the recording medium 5 is different from the second light amount of light reflected by the mark 50, the optical sensor 38 passes through the mark 50, thereby detecting the boundary between the mark 50 and the recording medium 5, i.e., the end T of the mark 50 in the sub-scanning direction X. Here, if there are no gaps in the rectangular mark 50, the number of end portions N is two, but the number of end portions N increases as the number of gaps increases. Therefore, the determination unit 86 determines that a discharge defect has occurred in a nozzle 41 if the number of end portions N is greater than the first value. In this way, by forming a rectangular mark 50 using all of the nozzles 41 and detecting the number of end portions N of the mark 50, it is possible to easily determine whether a discharge defect has occurred in a nozzle 41.

[0048] According to the printer 10 of this embodiment, the marks 50 include a first mark 51 formed from a first color and a third mark 53 formed from a second color, and the color of light irradiated from the optical sensor 38 toward the first mark 51 is different from the color of light irradiated toward the third mark 53. By varying the color of light irradiated from the optical sensor 38 for each of the different colored marks 50 in this way, the difference between the first amount of received light and the second amount of received light can be increased, and the number of ends N, which is the number of ends T of the marks 50 in the sub-scanning direction X, can be detected more reliably.

[0049] According to the printer 10 of this embodiment, the control device 80 includes a first cleaning operation unit 88 that, when the number of end portions N is equal to or greater than a second value that is greater than the first value, executes a flushing operation to cause ink to be ejected from the nozzles 41. In this way, when there are relatively many ejection defects in the nozzles 41, the ejection defects in the nozzles 41 can be improved by executing a flushing operation using the first cleaning operation unit 88.

[0050] According to the printer 10 of this embodiment, the control device 80 is provided with a second cleaning operation unit 90 that, when the number of end portions N is equal to or greater than a third value greater than the second value, performs a suction operation by using the suction pump 68 to suck the fluid in the sealed space 67 and forcibly eject ink from the nozzles 41. In this way, when there are a large number of ejection defects in the nozzles 41, the ejection defects in the nozzles 41 can be more effectively improved by performing a suction operation using the second cleaning operation unit 90.

[0051] According to the printer 10 of this embodiment, the control device 80 is provided with a notification unit 92 that notifies the user that a discharge defect has occurred in the nozzle 41 when the determination unit 86 determines that a discharge defect has occurred in the nozzle 41. This allows the user to recognize that a discharge defect has occurred in the nozzle 41 without having to directly check the mark 50 formed on the recording medium 5.

[0052] In the printer 10 of this embodiment, the detection unit 84 is configured to move the recording medium a first distance from one side to the other in the sub-scanning direction X relative to the optical sensor 38 at one mark 50, and then move the carriage 17 a second distance from one side to the other in the main scanning direction Y, and detects the number of end portions N for each mark 50 from one side to the other in the main scanning direction Y, and the judgment unit 86 judges that a nozzle 41 has an ejection defect when the number of end portions N is 4 or more, and the control device 80 is equipped with an identification unit 94 that identifies the nozzle row 45 for which the judgment unit 86 has judged that a nozzle 41 has an ejection defect. When forming one rectangular mark 50, if there is a discharge defect in even one nozzle 41 in the nozzle row 45, the number of end portions N will be 4 or more. Therefore, when the number of end portions N is 4 or more for one mark 50 when the recording medium 5 is moved a first distance from one side to the other in the sub-scanning direction X relative to the optical sensor 38, the identification unit 94 can identify that there is a discharge defect in the nozzle row 45 that formed the mark 50.

[0053] In the printer 10 of this embodiment, the detection unit 84 is configured to move the recording medium 5 a first distance from one side to the other in the sub-scanning direction X relative to the optical sensor 38 for one mark 50, and after moving the recording medium 5 the first distance from the other side in the sub-scanning direction X to the one side, move the carriage 17 a second distance from one side to the other in the main scanning direction Y. The detection unit 84 detects the number of end portions N for each mark 50 from one side to the other in the main scanning direction Y, and the determination unit 86 may determine that a discharge defect has occurred in a nozzle 41 if the number of end portions N is 8 or more. When forming one rectangular mark 50, if a discharge defect has occurred in even one nozzle 41 in the nozzle rows 45, the number of end portions N will be 4 or more. Therefore, if the number of end portions is 8 or more when the recording medium 5 is moved back and forth from one side to the other in the sub-scanning direction X for one mark 50 relative to the optical sensor 38, the identification unit 94 can identify that a discharge defect has occurred in the nozzle row 45 that formed the mark 50. Furthermore, because the optical sensor 38 scans one mark 50 twice in the sub-scanning direction X, it is possible to prevent erroneous detections from occurring. In other words, it is possible to more reliably identify the nozzle row 45 that includes the nozzle 41 in which the ejection defect is occurring.

[0054] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

[0055] In the above-described embodiment, the mark forming unit 82 ejects ink from all nozzles 41 in each of the first nozzle row 42 and the second nozzle row 43 so that one mark 50 is formed by filling in each of the first nozzle row 42 and the second nozzle row 43. However, this is not limited to this. The mark forming unit 82 may eject ink from all nozzles 41 in each of the first nozzle row 42 and the second nozzle row 43 so that at least two marks 150 that are offset from each other in the main scanning direction Y and the sub-scanning direction X are formed by filling in each of the first nozzle row 42 and the second nozzle row 43. Here, an example will be described in which the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A are each divided into three equal parts: an upstream nozzle row 46A, a central nozzle row 46B, and a downstream nozzle row 46C, and three marks 150 are formed for each of the first nozzle row 42 and the second nozzle row 43.

[0056] 12A, the mark forming unit 82 ejects ink from all nozzles 41 in the upstream nozzle row 46A, the central nozzle row 46B, and the downstream nozzle row 46C of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A while moving the carriage 17 in the forward direction Y1 of the main scanning direction Y, thereby forming a portion 150A of the mark 150. Here, ink is ejected from the nozzles 41 of the upstream nozzle row 46A to form a portion 150AA of the mark 150, ink is ejected from the nozzles 41 of the central nozzle row 46B to form a portion 150AB of the mark 150, and ink is ejected from the nozzles 41 of the downstream nozzle row 46C to form a portion 150AC of the mark 150. The portions 150AA, 150AB, and 150AC are biased from one another in the main scanning direction Y and the sub-scanning direction X. 12B, after a portion 150A of the mark 150 is formed, another portion 150B of the mark 150 (i.e., portion 150BA, portion 150BB, and portion 150BC) is formed. By repeating the above control, a test pattern 150P is formed on the recording medium 5, in which a plurality of (here, three types of) rectangular marks 150 formed by filling in are mutually biased in the main scanning direction Y and the sub-scanning direction X, as shown in FIG.

[0057] 13, the test pattern 150P includes a first mark 151 formed by the nozzles 41 of the upstream nozzle row 46A of the first nozzle row 42 of the first ink head 40A, a second mark 152 formed by the nozzles 41 of the upstream nozzle row 46A of the second nozzle row 43 of the first ink head 40A, a third mark 153 formed by the nozzles 41 of the central nozzle row 46B of the first nozzle row 42 of the first ink head 40A, a fourth mark 154 formed by the nozzles 41 of the central nozzle row 46B of the second nozzle row 43 of the first ink head 40A, a fifth mark 155 formed by the nozzles 41 of the downstream nozzle row 46C of the first nozzle row 42 of the first ink head 40A, and a sixth mark 156 formed by the nozzles 41 of the downstream nozzle row 46C of the second nozzle row 43 of the first ink head 40A. Here, the first mark 151 to the sixth mark 156 are formed with cyan ink.

[0058] 14, the detection unit 84 controls the movement of the carriage 17 in the forward direction Y1 in the main scanning direction Y and the movement of the recording medium 5 in the forward direction X1 and return direction X2 in the sub-scanning direction X so that the optical sensor 38 moves along a movement path 138P indicated by the two-dot chain line in FIG. 14. This allows the detection unit 84 to detect the number N of ends for each mark 150. That is, by forming the test pattern 150P, it is possible to detect the presence or absence of ejection defects in the nozzles 41 for each of the upstream nozzle row 46A, the central nozzle row 46B, and the downstream nozzle row 46C of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A to the fourth ink head 40D.

[0059] In the above-described embodiment, when forming the mark 50, the recording medium 5 is moved in the sub-scanning direction X by the length LX in the sub-scanning direction X between adjacent nozzles 41. However, this is not limiting. For example, one mark 50 may be formed by first moving the recording medium 5 in the sub-scanning direction X by the length LX in the sub-scanning direction X between adjacent nozzles 41, then further moving the recording medium 5 in the sub-scanning direction X by the length LY (see FIG. 2) of the first nozzle row 42 and the second nozzle row 43 in the sub-scanning direction X, and then moving the recording medium 5 in the sub-scanning direction X by the length LX in the sub-scanning direction X between adjacent nozzles 41. In this case, as shown in FIG. 15A , if no ejection defects occur in the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D, a single rectangular eighth mark 58 is formed. That is, the number of end portions N when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58 is two. 15B , if a discharge defect occurs in the nozzle 41 located most upstream in the upstream nozzle row 46A of the second nozzle row 43 of the fourth ink head 40D, the eighth mark 58 will have a form in which multiple rectangular marks are lined up in the sub-scanning direction X, rather than a single rectangular mark. That is, the number of ends N when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58 will be four. In this way, if a discharge defect occurs in the nozzle 41 located most upstream in the sub-scanning direction X and / or the nozzle 41 located most downstream in the sub-scanning direction X, of the first nozzle row 42 and the second nozzle row 43, the form in which multiple rectangular marks are lined up in the sub-scanning direction X, rather than a single rectangular mark, makes it possible to reliably detect the discharge defect of that nozzle 41. When forming the marks 150, one mark 150 is formed by moving the recording medium 5 in the sub-scanning direction X by a length LX, then further moving the recording medium 5 in the sub-scanning direction X by a length LZ (see FIG. 2) of the upstream nozzle row 46A, and then moving the recording medium 5 in the sub-scanning direction X by the length LX.

[0060] In the above-described embodiment, the marks 50 and 150 are formed by ejecting process color inks such as cyan ink onto a white recording medium 5. However, for example, white ink may be ejected from the nozzles 41 of the ink head 40 onto a white recording medium 5. Therefore, when the color of the recording medium 5 and the color of the mark 50 are the same (e.g., white), the mark forming unit 82 may form an underlayer 59 of a color different from the color of the recording medium 5 and the color of the mark 50 (e.g., black) on an area of ​​the recording medium 5 that is larger than the area on which the mark 50 will be formed, as shown in FIG. 16 . The detection unit 84 may then detect the number N of end portions based on the second amount of received light and the third amount of light reflected by the underlayer 59. When the optical sensor 38 passes over the mark 50 along the movement path 238P, the optical sensor 38 moves in the order of the underlayer 59, the mark 50, and the underlayer 59. Here, since the third amount of light received of light reflected by the base layer 59 is different from the second amount of light received of light reflected by the mark 50, the optical sensor 38 detects the end T of the mark 50 based on the change between the second amount of light received and the third amount of light received (i.e., the change in voltage). In this way, by forming the base layer 59 on the recording medium 5 in advance, the number N of end portions can be accurately detected even if the color of the recording medium 5 and the color of the mark 50 are the same. It is preferable that the color of the base layer 59 is complementary to the color of the mark 50.

[0061] In the above-described embodiment, the color of the light irradiated from the optical sensor 38 toward the first mark 51 is different from the color of the light irradiated toward the third mark 53. However, this is not limiting. For example, the color of the light irradiated from the optical sensor 38 toward the first mark 51 and the third mark 53 may be the same, and the color of the light reflected from the first mark 51 and received by the optical sensor 38 may be different from the color of the light reflected from the third mark 53 and received by the optical sensor 38. In this way, by varying the color of the light received by the optical sensor 38 for each mark 50, the difference between the first amount of received light and the second amount of received light can be increased, and the number of end portions N, which is the number of end portions T of the mark 50 in the sub-scanning direction X, can be more reliably detected.

[0062] In the above-described embodiment, the judgment unit 86 judges that a nozzle 41 has an ejection defect when the number of end portions N is 4 or more, for example, but when the number of end portions N is 0, it judges that all nozzles 41 in the nozzle row 45 have an ejection defect for the mark 50 being detected.

[0063] When the determining unit 86 determines that no ejection defects have occurred in the nozzles 41, the notifying unit 92 may notify the user that no ejection defects have occurred in the nozzles 41.

[0064] When moving the optical sensor 38 along the movement path 38P, the movement path 138P, and the movement path 238P, crop marks for positioning the optical sensor 38 may be formed in advance on the recording medium 5. This allows the optical sensor 38 to detect the end T of the mark 50 with high accuracy.

[0065] In the above-described embodiment, the printer 10 is configured to include a platen 13 on which the recording medium 5 is placed, and the recording medium 5 is transported in the sub-scanning direction X by the grit roller 22, but this is not limiting. For example, the printer 10 may be a so-called flatbed type printer. That is, the printer 10 may include a table as a mounting base that can move the recording medium 5 in the sub-scanning direction X. [Explanation of symbols]

[0066] 5. Recording media 10 Printer (inkjet printer) 13 Platen (mounting table) 17 Carriage 38 Optical Sensor 38P Travel Route 40 Ink head 41 nozzle 42 1st nozzle row 43 Second nozzle row 45 nozzle rows 50 marks 80 Control device 82 Mark forming section 84 Detector 86 Judgment Department 92 Notification Department 94 Specific part

Claims

1. a mounting table on which a recording medium is placed; an ink head having a nozzle row including a plurality of nozzles arranged in a sub-scanning direction and configured to eject ink onto the recording medium placed on the placement table, and a nozzle surface on which the nozzles are formed; a carriage that carries the ink head and is movable in a main scanning direction; an optical sensor mounted on the carriage, emitting light and receiving reflected light; a moving mechanism that moves the recording medium in the sub-scanning direction; a control device; The control device a mark forming unit that forms the mark by ejecting ink from all the nozzles for each nozzle row so that one mark is formed by filling one nozzle row; a detection unit that moves the recording medium on which the mark is formed relative to the optical sensor in the sub-scanning direction, and detects the number of ends of the mark in the sub-scanning direction based on a first received light amount of light reflected by the recording medium and a second received light amount of light reflected by the mark; a determination unit that determines that a discharge defect has occurred in the nozzle when the number of the end portions is greater than a first value, an inkjet printer in which one of the marks is formed by performing control multiple times to eject ink from all of the nozzles in each of the nozzle rows to form a part of the mark, and then to move the recording medium in the sub-scanning direction by the length in the sub-scanning direction between adjacent nozzles, thereby forming one rectangular mark; then to move the recording medium in the sub-scanning direction by the length of the nozzle row in the sub-scanning direction, and then to eject ink from all of the nozzles in each of the nozzle rows to form another part of the mark, and then to move the recording medium in the sub-scanning direction by the length in the sub-scanning direction between adjacent nozzles, thereby forming another rectangular mark.

2. the marks include a first color mark formed from a first color and a second color mark formed from a second color; 2. The inkjet printer according to claim 1, wherein the color of the light emitted from said optical sensor toward said first color mark is different from the color of the light emitted toward said second color mark.

3. the marks include a first color mark formed from a first color and a second color mark formed from a second color; 2. The inkjet printer according to claim 1, wherein a color of light reflected by the first color mark and received by the optical sensor is different from a color of light reflected by the second color mark and received by the optical sensor.

4. 4. The inkjet printer according to claim 1, wherein the control device is provided with a first cleaning operation unit that executes a flushing operation to eject ink from the nozzles when the number of end portions is equal to or greater than a second value that is greater than the first value.

5. a cap that is detachably attached to the ink head and that covers the nozzle surface when attached to the ink head and forms a sealed space between the nozzle surface and the cap; a suction pump that sucks the fluid in the sealed space, 5. The inkjet printer according to claim 4, wherein the control device is provided with a second cleaning operation unit that performs a suction operation to suck fluid from the sealed space using the suction pump and forcibly eject ink from the nozzles when the number of ends is equal to or greater than a third value greater than the second value.

6. 6. The inkjet printer according to claim 1, wherein the control device includes a notification unit that notifies a user that a discharge defect has occurred in the nozzle when the determination unit determines that a discharge defect has occurred in the nozzle.

7. A plurality of the marks are formed on the recording medium, the marks being aligned in the main scanning direction, the detection unit is configured to move the recording medium a first distance from one side to the other side in the sub-scanning direction relative to the optical sensor at one of the marks, and then move the carriage a second distance from one side to the other side in the main scanning direction, and detect the number of end portions for each of the marks from one side to the other side in the main scanning direction; the determining unit determines that a discharge defect has occurred in the nozzle when the number of the ends is four or more, 7. The inkjet printer according to claim 1, wherein the control device further comprises an identifying unit that identifies the nozzle row in which the determining unit has determined that a nozzle ejection defect is occurring.

8. A plurality of the marks are formed on the recording medium, the marks being aligned in the main scanning direction, the detection unit is configured to move the recording medium by a first distance from one side to the other side in the sub-scanning direction relative to the optical sensor at one of the marks, and after moving the recording medium by the first distance from the other side to the one side in the sub-scanning direction, move the carriage by a second distance from one side to the other side in the main scanning direction, and detect the number of end portions for each of the marks from one side to the other side in the main scanning direction; the determining unit determines that a discharge defect has occurred in the nozzle when the number of the ends is 8 or more, 7. The inkjet printer according to claim 1, wherein the control device further comprises an identifying unit that identifies the nozzle row in which the determining unit has determined that a nozzle ejection defect is occurring.

9. when the color of the recording medium and the color of the mark are the same, the mark forming unit forms an underlayer made of a color different from the color of the recording medium and the color of the mark in an area on the recording medium that is larger than an area on which the mark is to be formed before forming the mark; The inkjet printer according to claim 1 , wherein the detection section detects the number of end portions based on the second amount of received light and a third amount of received light that is reflected by the base layer.

Images