JP2023023519A - inkjet printer - Google Patents

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

The present invention relates to inkjet printers.

2. Description of the Related Art Conventionally, an inkjet printer that prints an image on a recording medium by an inkjet method is known. This type of inkjet printer has, for example, a mounting table on which a recording medium conveyed in the sub-scanning direction is mounted, and a plurality of nozzles for ejecting ink onto the recording medium mounted on the mounting table. and an ink head provided movably in a main scanning direction intersecting the direction. When a plurality of nozzles are clogged, ejection failures such as a decrease in the amount of ink ejected from the nozzles or failure to eject ink from the nozzles may occur. If ink is not properly ejected from the nozzle due to an ejection failure in the nozzle, the quality of the formed image is degraded. For example, Patent Literature 1 discloses a method of inspecting for missing nozzles.

JP 2017-47652 A

However, the method described in Japanese Patent Laid-Open No. 2002-200013 requires a scanner to capture the printed test pattern as an image for inspecting the presence or absence of missing nozzles, which may increase the cost and increase the size of the printer. There is In addition, since the presence or absence of missing nozzles is calculated by image processing, the control becomes complicated, and depending on the resolution of the image, etc., it may not be possible to accurately inspect the presence or absence of missing nozzles.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet printer capable of determining whether or not there is an ejection failure in a nozzle by a simple method.

An inkjet printer according to the present invention includes a mounting table on which a recording medium is mounted; a nozzle array including a plurality of nozzles arranged in a sub-scanning direction and ejecting ink onto the recording medium mounted on the mounting table; an ink head having a nozzle surface on which the nozzles are formed; a carriage on which the ink head is mounted and provided movably in a main scanning direction; An optical sensor for receiving light, a moving mechanism for moving the recording medium in the sub-scanning direction, and a control device are provided. The control device may fill one nozzle row with one rectangular mark or at least two marks offset from each other in the main scanning direction and the sub-scanning direction. a mark forming unit that forms the mark by ejecting ink from all the nozzles of each nozzle row; and moving the recording medium on which the mark is formed relatively to the optical sensor in the sub-scanning direction. and detects the number of edges of the mark in the sub-scanning direction based on the first received amount of light reflected by the recording medium and the second received amount of light reflected by the mark. a detection unit; and a determination unit that determines that an ejection failure has occurred in the nozzle when the number of edges is greater than a first value.

According to the inkjet printer of the present invention, the mark forming section is configured, for example, to eject ink from all the nozzles of each nozzle row to form one rectangular mark. Here, when the nozzles of the nozzle row are not clogged, the rectangular mark is formed as one mark without a break in the sub-scanning direction (that is, a line extending in the main scanning direction). On the other hand, if some of the nozzles in the nozzle row are clogged, the ink will not be properly ejected from the nozzles, and the rectangular mark will have a break in the sub-scanning direction. In addition, since ink is properly ejected from the other nozzles and filled, an attempt to form one rectangular mark results in the formation of a plurality of rectangular marks arranged in the sub-scanning direction as a whole. . Further, the detection section moves the recording medium on which the mark is formed in the sub-scanning direction with respect to the optical sensor. Here, since the first light amount of light reflected by the recording medium and the second light amount of light reflected by the mark are different, the boundary between the mark and the recording medium, that is, the side of the mark, is detected by the optical sensor passing through the mark. Edges in the scanning direction can be detected. Here, when the rectangular mark has no break, the number of ends is two, but the number of ends increases as the number of breaks increases. Therefore, when the number of edges is larger than the first value, the determination unit determines that the nozzle has an ejection failure. In this way, by forming rectangular marks using all the nozzles and detecting the number of ends of the marks, it is possible to easily determine whether or not the nozzles have an ejection failure.

According to the present invention, it is possible to provide an inkjet printer capable of determining the presence or absence of an ejection failure of a nozzle by a simple method.

1 is a front view showing an inkjet printer according to one embodiment; FIG. 4 is a diagram schematically showing the configuration of the lower surface of the carriage according to one embodiment; FIG. FIG. 4 is a diagram showing the configuration around the capping unit according to one embodiment, and is a front view showing a state where the cap is removed from the ink head. FIG. 4 is a diagram showing the configuration around the capping unit according to one embodiment, and is a front view showing a state in which the cap is attached to the ink head. 3 is a block diagram of the control system of the printer according to one embodiment; FIG. 4 is a flow chart showing a procedure for confirming the presence or absence of an ejection failure in the nozzles of the ink head. It is a schematic diagram which shows the state in which a part of rectangular mark was formed. FIG. 10 is a schematic diagram showing a state in which another portion of the rectangular mark is formed; It is an example of a test pattern in which rectangular marks are arranged in the main scanning direction. It is a schematic diagram which shows the movement path|route of an optical sensor. FIG. 10 is a schematic diagram showing an example of a moving path of an optical sensor when detecting the edge of a normally formed mark; FIG. 10 is a schematic diagram showing an example of a moving path of an optical sensor when detecting an edge of a mark that is not formed normally; FIG. 10 is a schematic diagram showing another example of the moving path of the optical sensor when detecting the edge of a normally formed mark; FIG. 11 is a schematic diagram showing another example of the moving path of the optical sensor when detecting the edge of a mark that is not formed normally; It is a schematic diagram which shows the modification of the state in which a part of rectangular mark was formed. FIG. 11 is a schematic diagram showing a modification in which another part of the rectangular mark is formed; This is a modification of the test pattern in which rectangular marks are arranged in the main scanning direction. It is a schematic diagram which shows the modification of the movement path|route of an optical sensor. FIG. 10 is a schematic diagram showing another example of the moving path of the optical sensor when detecting the edge of a normally formed mark; FIG. 11 is a schematic diagram showing another example of the moving path of the optical sensor when detecting the edge of a mark that is not formed normally; FIG. 10 is a schematic diagram showing a moving path of an optical sensor when marks are formed on an underlying layer;

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 embodiments described herein are, of course, not intended to limit the invention in particular. Further, members and portions having the same function are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted or simplified.

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

As shown in FIG. 1, the printer 10 prints on the 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 a sheet or film made of a resin such as polyvinyl chloride or polyester, a fabric such as a woven fabric or a nonwoven fabric, or other media other than paper such as plain paper and inkjet printing paper. The recording medium 5 is white, for example.

As shown in FIG. 1, the printer 10 includes a printer 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, and an ink head 40 (see FIG. 1). 2), a capping unit 60, and a control device 80.

The printer main body 10A has a casing extending in the main scanning direction Y. As shown in FIG. A recording medium 5 is placed on the platen 13 . Printing is performed on the recording medium 5 on the platen 13 while the recording medium 5 is placed on the platen 13 . The platen 13 extends in the main scanning direction Y and the sub-scanning direction X. As shown in FIG. The platen 13 is an example of a mounting table.

The moving mechanism 20 moves the recording medium 5 placed on the platen 13 in the sub-scanning direction X. As shown in FIG. The configuration of the moving mechanism 20 is not particularly limited. In this embodiment, the moving mechanism 20 includes pinch rollers 21 , grit rollers 22 and feed motors 23 . The pinch roller 21 is arranged above the platen 13 and below the guide rail 15 to press 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 . The position and number of pinch rollers 21 and grit rollers 22 are not particularly limited. In this embodiment, as shown in FIG. 1, the pinch roller 21 and the grit roller 22 are arranged at the left end and right end of the platen 13, respectively.

Here, a feed motor 23 is connected to the grit roller 22 . When the feed motor 23 is driven with the recording medium 5 sandwiched between the pinch roller 21 and the grit roller 22, the grit roller 22 rotates. As a result, the recording medium 5 is conveyed in the sub-scanning direction X. As shown in FIG. The feed motor 23 is controlled by the controller 80 .

The guide rail 15 is arranged above the platen 13 . The guide rail 15 is arranged parallel to the platen 13 and extends in the main scanning direction Y. As shown in FIG. A carriage 17 is engaged with the guide rail 15 . The carriage 17 is slidably provided on the guide rail 15 .

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. As shown in FIG. Note that the configuration of the head moving mechanism 30 is not particularly limited. In this embodiment, the head moving mechanism 30 includes a left pulley 31 a , a right pulley 31 b , a belt 32 and a carriage motor 33 . The left pulley 31 a is provided near the left end of the guide rail 15 . The right pulley 31 b is provided near the right end of the guide rail 15 . The belt 32 is, for example, endless, and is wound around a left pulley 31a and a right pulley 31b. A carriage 17 is attached and fixed to the belt 32 .

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

As shown in FIG. 2, the carriage 17 has a plurality of ink heads 40 mounted thereon. The ink head 40 ejects ink onto the recording medium 5 placed on the platen 13 . Each ink head 40 communicates with an ink cartridge (not shown) housed in the printer main body 10A through a flexible ink tube (not shown). The ink cartridge contains, for example, process color ink, white ink, gloss ink, primer ink, and the like. Examples of process color inks include cyan ink, magenta ink, yellow ink, black ink, light cyan ink, and light magenta ink.

As shown in FIG. 2, the ink head 40 includes 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 the carriage 17. As shown in FIG. The first ink head 40A to the fourth ink head 40D are arranged in the main scanning direction Y. As shown in FIG. The first ink head 40A to the fourth ink head 40D are arranged at aligned positions in the sub-scanning direction X. As shown in FIG. The first ink head 40A to the fourth ink head 40D may be arranged at positions shifted from each other in the sub-scanning direction X. FIG. The first ink head 40A to the fourth ink head 40D are formed in such a shape that the length in the sub-scanning direction X is longer than the length in the main scanning direction Y. As shown in FIG. The first ink head 40A to fourth ink head 40D are formed in the same shape and size. The first to fourth ink heads 40A to 40D are provided with a plurality of nozzles 41 arranged 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 . The inside of the nozzle 41 is set to a negative pressure (pressure lower than atmospheric pressure).

As shown in FIG. 2, in the first ink head 40A to the fourth ink head 40D, a plurality of nozzles 41 are arranged in a row in the sub-scanning direction X to form a first nozzle row 42 and a second nozzle row 43. there is The first nozzle row 42 is positioned 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 are, respectively, an upstream nozzle row 46A in which a part of the plurality of nozzles 41 are aligned in the sub-scanning direction X, and a downstream side of the upstream nozzle row 46A in the sub-scanning direction ( Here, a central nozzle row 46B positioned at the front) and a part of the plurality of nozzles 41 are aligned in the sub-scanning direction X, and a central nozzle row 46B positioned downstream in the sub-scanning direction (here, forward) from the central nozzle row 46B and having a plurality of and a downstream nozzle row 46C in which some of the nozzles 41 are arranged in the sub-scanning direction X. In this embodiment, the number of nozzles 41 in the upstream nozzle row 46A, the number of nozzles 41 in the central nozzle row 46B, and the number of nozzles 41 in the downstream nozzle row 46C are the same. 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, and yellow ink is ejected from the nozzles 41 of the third ink head 40C. Then, black ink is ejected from the nozzles 41 of the fourth ink head 40D. Although 12 nozzles 41 are shown for each nozzle row 45 in the ink head 40 in FIG. 2, more nozzles (for example, 180) are actually formed. However, the number of nozzles 41 is not limited at all. Further, 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, the first nozzle row 42 and the second nozzle row 43), but the number of nozzle rows 45 may be one or three or more.

The optical sensor 38 is provided so as to be movable in the main scanning direction Y above the recording medium 5 placed on the platen 13 . The optical sensor 38 is mounted on the carriage 17 . Although the optical sensor 38 is provided to the left of the ink head 40 in this embodiment, it may be provided to the right. The optical sensor 38 emits light and receives reflected light. The optical sensor 38 irradiates the recording medium 5 with light and receives light reflected from the recording medium 5 . The optical sensor 38 irradiates light onto a mark 50 (see FIG. 8) formed on the recording medium 5 and receives light reflected from the mark 50 . Although the type of the optical sensor 38 is not particularly limited, for example, a reflective photosensor can be used. In this embodiment, optical sensor 38 is a color sensor (typically a color sensor that measures RGB values). Optical sensor 38 is connected to controller 80 .

Next, the capping unit 60 according to this embodiment will be described. The capping unit 60 prevents drying of the nozzles 41 of the ink head 40 by attaching a cap 70 (see FIG. 3), which will be described later, to the ink head 40 . In addition, the capping unit 60 forcibly discharges the ink inside the nozzles 41 into the cap 70 by means of a suction pump 68, which will be described later, in order to suppress clogging of the nozzles 41. FIG.

As shown in FIG. 1, the capping unit 60 is provided inside the printer body 10A. The capping unit 60 is arranged 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 removed from the ink head 40 , a cap moving mechanism 63 and a suction pump 68 . The cap 70 and the cap moving mechanism 63 are arranged at the home position HP located at the right end of the guide rail 15 (see FIG. 1). Here, the home position HP is a position where the carriage 17, the ink head 40, and the optical sensor 38 wait when waiting for printing, that is, when printing is not performed. However, the position of the home position HP is not particularly limited, and may be the left end of the guide rail 15 .

As shown in FIG. 3, the caps 70 are arranged in the main scanning direction Y. As shown in FIG. The cap 70 is shaped such that the length in the sub-scanning direction X is longer than the length in the main scanning direction Y. As shown in FIG. The caps 70 are detachably formed on the ink heads 40 so as to cover the nozzle surfaces 44 (see FIG. 2) of the ink heads 40 . Note that "covering the nozzle surface 44" is not limited to the case where the entire nozzle surface 44 is covered, but also includes the case where at least the first nozzle row 42 and the second nozzle row 43 are entirely covered. Ink is ejected from the nozzles 41 of the ink head 40 to the cap 70 .

As shown in FIG. 3, the cap moving mechanism 63 supports the cap 70. As shown in FIG. The cap moving mechanism 63 is a mechanism for moving the cap 70 so as to be detachable from the ink head 40 . In this embodiment, the cap moving mechanism 63 moves the cap 70 vertically. Although the configuration of the cap moving mechanism 63 is not particularly limited, it includes a drive motor 63A, for example. By driving the drive motor 63A, the cap moving mechanism 63 moves the cap 70 vertically. The cap moving mechanism 63 moves the cap 70 to the cap position CP (see FIG. 4) by moving the cap 70 upward. Here, the cap position CP is a position where the cap 70 covers the nozzle surface 44 of the ink head 40 . Thereby, the caps 70 are attached to the ink heads 40 respectively. A closed space 67 (see FIG. 4) is formed between the cap 70 and the nozzle surface 44 when the cap 70 is attached to each of the ink heads 40 . When starting printing, the cap moving mechanism 63 moves the cap 70 downward from the cap position CP (see FIG. 4) to the separated position DP (see FIG. 3). Here, the separation position DP is a position where the cap 70 is separated from the nozzle surface 44 . Thereby, the caps 70 are removed from the ink heads 40 respectively.

The suction pump 68 sucks the fluid (for example, ink) in the sealed space 67 and ejects the ink from the nozzles 41 (see FIG. 2) in a state where the cap 70 is attached to the ink head 40 . By driving the suction pump 68, the pressure inside the sealed space 67 becomes lower than the atmospheric pressure (that is, 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 . A 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 controller 80 (see FIG. 1).

As shown in FIG. 1, an operation panel 18 is provided at the right end of the printer body 10A. The operation panel 18 is provided with a display section (not shown) for displaying the status of the printer and input keys (not shown) operated by the user. The operation panel 18 is connected to a control device 80 that controls various operations of the printer 10 .

As shown in FIG. 5, the overall operation of printer 10 is controlled by 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. central processing unit), ROM (read only memory) that stores programs executed by the CPU, RAM (random access memory) that is used as a working area for developing programs, and memory that stores programs and various data a storage device; As shown in FIG. 1, the control device 80 is provided inside the printer body 10A. However, the control device 80 may not be provided inside the printer body 10A. For example, the control device 80 may be a computer or the like installed outside the printer 10 . In this case, the control device 80 is communicably connected to the printer 10 via wire or wireless.

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

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 notification unit 92, and a specifying unit 88. a portion 94; The function of each part of the control device 80 is implemented by a program. This program is written, for example, into a ROM mounted on a board inside the printer 10 from a PC via a LAN, or written into an FPGA mounted on a board inside the printer 10 from a PC using a dedicated writing jig. I get lost. This program is downloaded to the PC, for example, through the Internet. Also, the function of each unit of the control device 80 may be realized by a processor and/or a circuit or the like. The specific functions of these units will be described later.

Next, a method for checking whether or not there is an ejection failure in the nozzles 41 of the ink head 40 will be described. FIG. 6 is a flow chart showing a procedure for printing a test pattern including predetermined marks on the recording medium 5 before starting printing, and checking for ejection failure of the nozzles 41 of the ink head 40 . Here, an example of forming one rectangular mark 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 will be described.

First, in step S10, the mark forming unit 82 ejects ink from all the nozzles 41 of 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 shape. A mark 50 (see FIG. 8) is formed. The mark forming part 82 is formed by filling each of the first nozzle row 42 and the second nozzle row 43 with one mark 50 for each of the first and second nozzle rows 42 and 43 . Ink is ejected from all the nozzles 41 .

For example, as shown in FIG. 7A, the mark forming unit 82 moves the carriage 17 in the forward direction Y1 of the main scanning direction Y while moving the first nozzle row 42 and the fourth ink head 40A to the fourth ink head 40D. A portion 50A of the mark 50 is formed by ejecting ink from all the nozzles 41 every two nozzle rows 43 . Here, the length of the portion 50A of the mark 50 in the sub-scanning direction X is the length of one pass. As shown in FIG. 7A, one rectangular mark 50 is not formed by moving the carriage 17 once in the main scanning direction Y1. Therefore, as shown in FIG. 7B, after the part 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 return direction X1 of the sub-scanning direction X. Move by the length of one pass. After that, 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. As shown in FIG. The length in the sub-scanning direction X of the portion 50A of the mark 50 and the length in the sub-scanning direction X of the other portion 50B of the mark 50 are the same. By repeating the above control, a test pattern 50P is formed on the recording medium 5 in which rectangular marks 50 formed by filling are arranged in the main scanning direction Y, as shown in FIG. In this example, by reciprocating the carriage 17 four times in the main scanning direction Y (that is, in four passes), one mark 50 is filled (solidly). That is, when the marks 50 are formed, the recording medium 5 is moved in the sub-scanning direction X by the length LX (see FIG. 2) in the sub-scanning direction X between the adjacent nozzles 41 . The mark forming section 82 controls the amount and timing of ink ejected 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. FIG. That is, the mark forming section 82 controls the first ink heads 40A to 40D, the carriage motor 33 and the feed motor 23. FIG. Before forming the mark 50, all the nozzles 41 of the nozzle arrays 45 of the first ink head 40A to the fourth ink head 40D spray ink onto one point of the recording medium 5 (for example, the right end of the recording medium 5). It is preferable to perform a so-called discard printing that causes ink to be ejected.

As shown in FIG. 8, the test pattern 50P includes the first marks 51 formed by the nozzles 41 of the first nozzle row 42 of the first ink head 40A and 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, and 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, and the nozzles 41 of the second nozzle row 43 of the third ink head 40C. A sixth mark 56, 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 57 formed by the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D. a mark 58; Here, the first marks 51 and the second marks 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.

In step S<b>20 , the detection unit 84 detects the number of edges T, which is the number of edges T of the mark 50 in the sub-scanning direction X. The number of edges N is, for example, the total number of edges T of all the marks 50 of the test pattern 50P. Note that the number of ends N may be the number of ends T for each mark 50 . The detection unit 84 moves the recording medium 5 on which the mark 50 is formed relatively to the optical sensor 38 (see FIG. 2) in the sub-scanning direction X, and detects the first amount of received light reflected by the recording medium 5. And the number of edges N is detected based on the second amount of received light reflected by the mark 50 . As shown in FIG. 9, the detection unit 84 moves the carriage 17 in the forward direction Y1 of the main scanning direction Y so that the optical sensor 38 moves along the movement path 38P indicated by the two-dot chain line in FIG. 5 in the sub-scanning direction X in the forward direction X1 and the backward direction X2. That is, the detector 84 controls the optical sensor 38 , carriage motor 33 and feed motor 23 . For example, at one mark 50, the detection unit 84 moves the recording medium 5 in the forward direction X1 or the backward direction X2 with respect to the optical sensor 38 by a first distance, and then moves the carriage 17 in the forward direction Y1 of the main scanning direction Y. is configured to move a second distance to. 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. is. The detection unit 84 controls, for example, the optical sensor 38 to pass over the mark 50 sequentially from right to left in the main scanning direction Y (that is, in the forward direction Y1). Note that the detection unit 84 may control the optical sensor 38 so that it passes over the mark 50 sequentially from left to right in the main scanning direction Y. FIG. In the example shown in FIG. 9, the optical sensor 38 first irradiates light toward the eighth mark 58 and irradiates light toward the first mark 51 last. The light emitted from the optical sensor 38 to the mark 50 differs depending on the color of the mark 50 . Here, the light emitted 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, and green for the fifth mark. For 55 and sixth mark 56 it is blue and for seventh mark 57 and eighth mark 58 it is red. The light emitted from the optical sensor 38 to the mark 50 may be complementary to the color of the mark 50, for example. Note that the light emitted from the optical sensor 38 to the mark 50 may be the same color regardless of the color of the mark 50 .

FIG. 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 from the recording medium 5, the eighth mark 58, and the recording medium 5 in this order. Here, since the first received light amount of the light reflected by the recording medium 5 and the second received light amount of the light reflected by the eighth mark 58 are different, the optical sensor 38 detects the change between the first received light amount and the second received light amount. (that is, change in voltage), the edge T of the eighth mark 58 is detected. The edge T is a boundary portion between the recording medium 5 and the eighth mark 58 (mark 50). In the example shown in FIG. In other words, the number of edges N is 2. Thus, when the eighth mark 58 is normally formed, the optical sensor 38 moves over the eighth mark 58 in the sub-scanning direction X. The number of ends N is 2 when moving once to .

FIG. 10B is a schematic diagram showing an abnormal eighth rectangular mark 58 formed by the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D. As shown in FIG. 10B, when the ejection failure occurs in the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D, the eighth mark 58 is not one rectangular mark but a plurality of Rectangular marks are aligned in the sub-scanning direction X. As shown in FIG. That is, a break (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 detects the recording medium 5, a portion of the eighth mark 58, the recording medium 5, and the rest of the eighth mark 58. A part moves in order of the recording medium 5 . In the example shown in FIG. 10B, the ends T are the front end T3 and the rear end T4 of part of the eighth mark 58, and the front end T5 of the other part of the eighth mark 58. and a rear end T6. That is, the number of edge portions N is four. Thus, when the eighth mark 58 is not formed normally, the number of edges N when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58 is four or more.

In step S30, the determination unit 86 determines whether or not the number of fractions N is greater than the first value. The determination unit 86 determines that the nozzle 41 has an ejection failure when the number of edges N is greater than the first value. 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 2, for example. In the example shown in FIG. 10B, the determination unit 86 determines that the ejection failure has occurred in the nozzle 41 when the number of edge portions N is 4 or more. The identifying unit 94 identifies the nozzle row for which the determining unit 86 has determined that the nozzle 41 has an ejection failure. For example, in the example shown in FIG. 10B, the specifying unit 94 specifies that the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D have an ejection failure. The specifying unit 94 determines 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 number of times the carriage 17 moves in the main scanning direction Y) when the optical sensor 38 detects the number N of edges of the mark 50 . position), it is possible to identify the nozzle 41 of which nozzle row 45 has an ejection failure. On the other hand, the determination unit 86 determines that the ejection failure has not occurred in the nozzle 41 when the number of edge portions N is equal to or less than the first value. Then, the control for confirming the presence or absence of ejection failure of the nozzles 41 ends.

In step S<b>40 , the notification unit 92 notifies the user that the nozzle 41 has an ejection failure when the determination unit 86 determines that the nozzle 41 has an ejection failure. A method of notification by the notification unit 92 is not particularly limited, and examples thereof include notification by visual display, sound, and the like. In this embodiment, the notification unit 92 visually notifies the user through the operation panel 18 . The notification unit 92 may notify, for example, the ink head 40 and its nozzle row 45 in which the ejection failure of the nozzle 41 is occurring.

In step S50, the determination unit 86 determines whether or not the number of edge portions N is greater than or equal to the second value. The second value is greater than the first value. The determination unit 86 determines that at least the flushing operation is necessary when the number of edge portions N is equal to or greater than the second value. In this case, the process proceeds to step S60. On the other hand, when the number of edges N is less than the second value, the determining unit 86 determines that although some of the nozzles 41 are defective in ejection, there is almost no effect on the print quality. Determine that no action is required. Then, the control for confirming the presence or absence of ejection failure of the nozzles 41 ends.

In step S60, the determination unit 86 determines whether or not the number of edge portions N is equal to or greater than a third value. The third value is greater than the second value. The determination unit 86 determines that the flushing operation and the suction operation are necessary when the number of edge portions N is equal to or greater than the third value. In this case, the process proceeds to step S70. On the other hand, if the number of ends N is less than the third value, the judgment unit 86 judges that the clogging of the nozzles 41 can be eliminated only by the flushing operation, although ejection failure has occurred in some of the nozzles 41 . do. In this case, the process proceeds to step S80.

In step S<b>70 , the first cleaning operation section 88 performs a flushing operation for ejecting ink from the nozzles 41 . When the flushing operation is performed, the cap 70 is normally arranged directly below the nozzle 41 and the ink ejected from the nozzle 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 section 88 controls the ink head 40 and the drive motor 63A. Then, the second cleaning operation section 90 performs a suction operation of forcibly ejecting ink from the nozzles 41 by sucking the fluid in the sealed space 67 with the suction pump 68 . Thereby, clogging of the nozzle 41 can be eliminated. A cap 70 is normally attached to the ink head 40 when a suction operation is performed. The second cleaning operation section 90 controls the ink head 40 , drive motor 63 A and suction pump 68 .

In step S<b>80 , the first cleaning operation section 88 performs a flushing operation for ejecting ink from the nozzles 41 . Thereby, clogging of the nozzle 41 can be eliminated.

In step S20 described above, the optical sensor 38 is configured to move once in the sub-scanning direction X with respect to one mark 50 as indicated by the movement path 38P in FIG. not. For example, at one mark 50, the detection unit 84 moves the recording medium 5 by a first distance in the forward direction X1 with respect to the optical sensor 38, and moves the recording medium 5 by a first distance in the return direction X2. The carriage 17 may be configured to move the second distance in the forward direction Y1 of the main scanning direction Y later (the outward direction X1 and the return direction X2 may be reversed). For example, as shown in FIG. 11A, the optical sensor 38 may be configured to move twice in the sub-scanning direction X with respect to one mark 50 (that is, move back and forth once). 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 edges N is four. Thus, when the eighth mark 58 is normally formed, the number of edge portions N is four when the optical sensor 38 reciprocates once in the sub-scanning direction X over the eighth mark 58 . On the other hand, in the example shown in FIG. 11B, the number of edge portions N is eight. As described above, when the eighth mark 58 is not formed normally, the number of edges N when the optical sensor 38 reciprocates once in the sub-scanning direction X over the eighth mark 58 is eight or more. In the example shown in FIG. 11B, the determination unit 86 determines that the nozzle 41 has an ejection failure when the number of edge portions N is 8 or more.

As described above, according to the printer 10 of the present embodiment, the mark forming section 82 is configured, for example, to eject ink from all the nozzles 41 of each nozzle row 45 to form one rectangular mark 50. It is Here, when the nozzles 41 of the nozzle row 45 are not clogged, the rectangular mark 50 is regarded as one mark 50 without a break in the sub-scanning direction X (that is, a line extending in the main scanning direction X). It is formed. On the other hand, if some of the nozzles 41 of the nozzle row 45 are clogged, the ink is not properly ejected from the nozzles 41 , and the rectangular mark 50 has a discontinuity in the sub-scanning direction X. In addition, since the other nozzles 41 are properly ejected and filled with ink, an attempt was made to form one rectangular mark 50, but a plurality of rectangular marks 50 aligned in the sub-scanning direction X were formed as a whole. will be Further, the detection unit 84 moves the recording medium 5 on which the mark 50 is formed in the sub-scanning direction X with respect to the optical sensor 38 . Here, since the first amount of light reflected by the recording medium 5 and the second amount of light reflected by the mark are different, the boundary between the mark 50 and the recording medium 5 is detected by the optical sensor 38 passing through the mark 50 . That is, the end T of the mark 50 in the sub-scanning direction X can be detected. Here, when the rectangular mark 50 has no break, the number of ends N is two, but the number of ends N increases as the number of breaks increases. Therefore, the determination unit 86 determines that the nozzle 41 has an ejection failure when the number of edges N is greater than the first value. Thus, by forming the rectangular mark 50 using all the nozzles 41 and detecting the number N of the ends of the mark 50, it is possible to easily determine whether or not the nozzle 41 has an ejection failure. can be done.

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 optical sensor 38 detects the first mark The color of light irradiated toward 51 and the color of light irradiated toward third mark 53 are different. In this manner, by varying the color of the light emitted from the optical sensor 38 for each mark 50 having a different color, the difference between the first received light amount and the second received light amount can be increased, and the mark 50 can be sub-scanned. The number of edges N, which is the number of edges T in the direction X, can be detected more reliably.

According to the printer 10 of the present embodiment, the control device 80 performs the flushing operation of ejecting ink from the nozzles 41 when the number of edges N is equal to or greater than the second value, which is greater than the first value. 88 is provided. In this way, when ejection failures of the nozzles 41 are relatively frequent, the ejection failures of the nozzles 41 can be improved by executing the flushing operation by the first cleaning operation unit 88 .

According to the printer 10 of the present embodiment, the controller 80 sucks the fluid in the sealed space 67 from the nozzle 41 by using the suction pump 68 when the number of edges N is equal to or greater than the third value, which is larger than the second value. A second cleaning operation unit 90 is provided for executing a suction operation for forcibly ejecting ink. In this way, when the ejection failures of the nozzles 41 are very frequent, the suction operation is performed by the second cleaning operation unit 90, so that the ejection failures of the nozzles 41 can be improved more effectively.

According to the printer 10 of the present embodiment, the control device 80 informs the user that the ejection failure of the nozzles 41 has occurred when the determination unit 86 determines that the ejection failure of the nozzles 41 has occurred. is provided with a notification unit 92 for notifying. As a result, the user can recognize that the nozzle 41 has an ejection failure without directly checking the mark 50 formed on the recording medium 5 .

According to the printer 10 of the present embodiment, the detection unit 84 moves the recording medium from one side to the other side in the five sub-scanning directions X by the first distance with respect to the optical sensor 38 at one mark 50, and then moves the carriage. 17 is moved from one side to the other side in the main scanning direction Y by a second distance, and the number of ends N is detected for each mark 50 from one side to the other side in the main scanning direction Y; The determination unit 86 determines that an ejection failure has occurred in the nozzle 41 when the number of ends N is 4 or more, and the control device 80 determines that the ejection failure has occurred in the nozzle 41 by the determination unit 86 . A specifying unit 94 for specifying the nozzle row 45 that has been processed is provided. When forming one rectangular mark 50 , if even one of the nozzle rows 45 has an ejection failure in the nozzle 41 , the number of ends N is 4 or more. 38, when the recording medium 5 is moved from one side to the other side in the sub-scanning direction X by the first distance, the number of edges N is 4 or more. It is possible to identify that an ejection failure has occurred in

According to the printer 10 of the present embodiment, the detection unit 84 moves the recording medium 5 from one side to the other side in the sub-scanning direction X by the first distance with respect to the optical sensor 38 at one mark 50, and performs recording. After the medium 5 is moved from the other side in the sub-scanning direction X by a first distance to one side, the carriage 17 is moved from one side to the other side in the main scanning direction Y by a second distance, and The edge number N is detected for each mark 50 from one side to the other side in the main scanning direction Y, and the determination unit 86 determines that the nozzle 41 has an ejection failure when the edge number N is 8 or more. You can judge. When forming one rectangular mark 50 , if even one of the nozzle rows 45 has an ejection failure in the nozzle 41 , the number of ends N is 4 or more. 38, when the recording medium 5 is reciprocated from one side to the other side in the sub-scanning direction X and the number of end portions is eight or more, the specifying unit 94 determines that the nozzle row 45 forming the mark 50 has an ejection failure. You can identify what is happening. In addition, since the optical sensor 38 scans one mark 50 twice in the sub-scanning direction X, it is possible to suppress the occurrence of erroneous detection. That is, the nozzle row 45 including the nozzle 41 in which the ejection failure has occurred can be specified more reliably.

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

In the above-described embodiment, the mark forming section 82 is formed by filling one first nozzle row 42 and one second nozzle row 43 with one mark 50, respectively. Although the ink is ejected from all the nozzles 41 every two nozzle rows 43, the present invention is not limited to this. The mark forming portion 82 is formed by filling at least two marks 150 mutually offset in the main scanning direction Y and the sub-scanning direction X with respect to one first nozzle row 42 and one second nozzle row 43 . Alternatively, ink may be ejected from all the nozzles 41 of each of the first nozzle row 42 and the second nozzle row 43 . Here, 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. A case of forming three marks 150 for each of the first nozzle row 42 and the second nozzle row 43 will be described as an example.

As shown in FIG. 12A, the mark forming unit 82 moves the carriage 17 in the forward direction Y1 of the main scanning direction Y while moving the upstream nozzles of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A. A portion 150A of the mark 150 is formed by ejecting ink from all the nozzles 41 in each of the row 46A, the central nozzle row 46B, and the downstream nozzle row 46C. Here, ink is ejected from the nozzles 41 of the upstream nozzle row 46A to form a part 150AA of the mark 150, ink is ejected from the nozzles 41 of the central nozzle row 46B to form a part 150AB of the mark 150, A portion 150AC of the mark 150 is formed by ejecting ink from the nozzles 41 of the downstream nozzle row 46C. The portion 150AA, the portion 150AB and the portion 150AC are mutually offset in the main scanning direction Y and the sub-scanning direction X. Then, as shown in FIG. 12B, after the portion 150A of the mark 150 is formed, another portion 150B of the mark 150 (ie, the portion 150BA, the portion 150BB and the portion 150BC) is formed. By repeating the above control, a plurality of (here, three types of) rectangular marks 150 formed by filling are mutually offset in the main scanning direction Y and the sub-scanning direction X, as shown in FIG. A test pattern 150</b>P is formed on the recording medium 5 .

As shown in FIG. 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 and a second mark 151 of the first ink head 40A. A second mark 152 formed by the nozzles 41 of the upstream nozzle row 46A of the nozzle row 43, and 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. , the 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, and 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 to sixth marks 151 to 156 are formed with cyan ink.

As shown in FIG. 14, the detection unit 84 moves the carriage 17 in the main scanning direction Y in the forward direction Y1 so that the optical sensor 38 moves along the movement path 138P indicated by the two-dot chain line in FIG. 5 in the sub-scanning direction X in the forward direction X1 and the backward direction X2. Thereby, the detection unit 84 can detect the number of edges N for each mark 150 . That is, by forming the test pattern 150P, the upstream nozzle row 46A, the central nozzle row 46B and the downstream nozzle row of the first nozzle row 42 and the second nozzle row 43 of the first ink head 40A to the fourth ink head 40D It is possible to detect the presence or absence of ejection failure of the nozzles 41 every 46C.

In the above-described embodiment, the recording medium 5 is moved in the sub-scanning direction X by the length LX in the sub-scanning direction X between the adjacent nozzles 41 when forming the marks 50, but the present invention is not limited to this. For example, one mark 50 is formed by 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, and then further sub-scanning of the first nozzle row 42 and the second nozzle row 43. The recording medium 5 is moved in the sub-scanning direction X by the length LY in the scanning direction X (see FIG. 2), and then 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 . may be formed by moving to In this case, as shown in FIG. 15A, one rectangular eighth mark 58 is formed when there is no ejection failure in the nozzles 41 of the second nozzle row 43 of the fourth ink head 40D. That is, when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58, the number of edge portions N is two. On the other hand, as shown in FIG. 15B, when the ejection failure occurs in the most upstream nozzle 41 of the upstream nozzle row 46A of the second nozzle row 43 of the fourth ink head 40D, the eighth mark 58 is a form in which a plurality of rectangular marks are arranged in the sub-scanning direction X instead of one rectangular mark. That is, when the optical sensor 38 moves once in the sub-scanning direction X over the eighth mark 58, the number of edges N is four. In this way, the nozzle 41 positioned furthest upstream in the sub-scanning direction X and/or the nozzle 41 positioned furthest downstream in the sub-scanning direction X among the first nozzle row 42 and the second nozzle row 43 has an ejection failure. If it occurs, not one rectangular mark but a plurality of rectangular marks are arranged in the sub-scanning direction X, so that the ejection failure of the nozzle 41 can be reliably detected. When forming the marks 150, one mark 150 is formed by moving the recording medium 5 by the length LX in the sub-scanning direction X, and then the length LZ of the upstream nozzle row 46A in the sub-scanning direction X (Fig. 2) is moved in the sub-scanning direction X, and then the recording medium 5 is moved in the sub-scanning direction X by the length LX.

In the above-described embodiment, process color ink such as cyan ink is ejected onto the white recording medium 5 to form the marks 50 and the marks 150 . 41 may eject white ink. Therefore, when the color of the recording medium 5 and the color of the mark 50 are the same (for example, when the color of the mark 50 is white), as shown in FIG. A base layer 59 formed of a color (for example, black) different from the color of the recording medium 5 and the color of the marks 50 may be formed in an area wider than the area where the marks 50 are formed. Then, the detection unit 84 may detect the number of edges N based on the second amount of light received and the third amount of light reflected by the underlying layer 59 . As the optical sensor 38 passes over the mark 50 along the movement path 238P, the optical sensor 38 moves through the underlying layer 59, the mark 50, and the underlying layer 59 in this order. Here, since the third received light amount of the light reflected by the base layer 59 and the second received light amount of the light reflected by the mark 50 are different, the optical sensor 38 detects the change between the second received light amount and the third received light amount (that is, The edge T of the mark 50 is detected based on the change in voltage). By forming the base layer 59 on the recording medium 5 in advance in this way, even if the color of the recording medium 5 and the color of the mark 50 are the same, the number of edges N can be accurately detected. The color of the base layer 59 is preferably complementary to the color of the mark 50 .

In the above-described embodiment, the color of the light emitted from the optical sensor 38 toward the first mark 51 is different from the color of the light emitted toward the third mark 53, but the present invention is not limited to this. For example, the color of the light emitted from the optical sensor 38 toward the first mark 51 and the third mark 53 is the same, and the color of the light reflected by the first mark 51 and received by the optical sensor 38 is the same as that of the third mark. The color of the light reflected at 53 and received by optical sensor 38 may be different. By making the color of the light received by the optical sensor 38 different for each mark 50 in this way, the difference between the first received light amount and the second received light amount can be increased, and the end of the mark 50 in the sub-scanning direction X can be detected. The number of edge portions N, which is the number of portions T, can be detected more reliably.

In the above-described embodiment, the judgment unit 86 judges that the nozzle 41 has an ejection failure when the number N of edges is 4 or more, but when the number N of edges is 0, It is determined that all the nozzles 41 of the nozzle row 45 are defective in ejection with respect to the mark 50 to be detected.

The notification unit 92 may notify the user that the ejection failure of the nozzle 41 has not occurred when the determination unit 86 has determined that the ejection failure has not occurred in the nozzle 41 .

Crop marks for positioning the optical sensor 38 may be previously formed on the recording medium 5 when the optical sensor 38 is moved along the movement path 38P, the movement path 138P, and the movement path 238P. As a result, the optical sensor 38 can accurately detect the edge T of the mark 50 .

In the above-described embodiment, the printer 10 includes the platen 13 on which the recording medium 5 is placed, and the recording medium 5 is conveyed in the sub-scanning direction X by the grit roller 22, but is not limited to this. . For example, the printer 10 may be a so-called flatbed type printer. That is, the printer 10 may include a table on which the recording medium 5 can be moved in the sub-scanning direction X as a mounting table.

5 recording medium 10 printer (inkjet printer)
13 Platen (mounting table)
17 Carriage 38 Optical sensor 38P Moving path 40 Ink head 41 Nozzle 42 First nozzle row 43 Second nozzle row 45 Nozzle row 50 Mark 80 Control device 82 Mark forming unit 84 Detecting unit 86 Judging unit 92 Notifying unit 94 Identifying unit

Claims (10)

a mounting table on which the recording medium is mounted;
an ink head having a nozzle row including a plurality of nozzles that eject ink onto the recording medium mounted on the mounting table and arranged in a sub-scanning direction; and a nozzle surface on which the nozzles are formed;
a carriage on which the ink head is mounted and which is movable in a main scanning direction;
an optical sensor mounted on the carriage for emitting light and receiving reflected light;
a moving mechanism for moving the recording medium in the sub-scanning direction;
a controller;
The control device is
One rectangular mark or at least two marks offset from each other in the main scanning direction and the sub-scanning direction are painted over each nozzle row. a mark forming unit that forms the mark by ejecting ink from all the nozzles;
By moving the recording medium on which the marks are formed relatively to the optical sensor in the sub-scanning direction, a first amount of light reflected by the recording medium and a second amount of light reflected by the marks are detected. a detection unit that detects the number of ends of the mark in the sub-scanning direction based on the amount of light received;
an inkjet printer, comprising: a determination unit that determines that an ejection failure has occurred in the nozzle when the number of edges is greater than a first value. 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 light emitted from said optical sensor toward said first color mark is different from the color of light emitted toward said second color mark. 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 light reflected by said first color mark and received by said optical sensor is different from the color of light reflected by said second color mark and received by said optical sensor. 2. The control device comprises a first cleaning operation section for executing a flushing operation for ejecting ink from the nozzles when the number of edge portions is equal to or greater than a second value larger than the first value. 4. The inkjet printer according to any one of items 3 to 3. a cap that is detachably attached to the ink head and that covers the nozzle surface and forms a closed space with the nozzle surface when attached to the ink head;
a suction pump that sucks the fluid in the sealed space;
The control device causes the suction pump to suck the fluid in the sealed space and forcibly eject ink from the nozzle when the number of ends is equal to or greater than a third value larger than the second value. 5. The inkjet printer of claim 4, comprising a second cleaning operation for performing the operation. The control device includes a notification unit that notifies a user that an ejection failure has occurred in the nozzle when the determination unit determines that an ejection failure has occurred in the nozzle. An inkjet printer according to any one of claims 1 to 5. a plurality of marks arranged in the main scanning direction are formed on the recording medium;
The detection unit moves the carriage to one side in the main scanning direction after moving the recording medium from one side to the other side in the sub-scanning direction by a first distance with respect to the optical sensor at one mark. and detecting the number of edges for each mark from one side to the other side in the main scanning direction;
The judging unit judges that an ejection failure has occurred in the nozzle when the number of ends is four or more,
The inkjet according to any one of claims 1 to 6, wherein the control device includes a specifying unit that specifies the nozzle row in which the determining unit determines that the ejection failure of the nozzle has occurred. printer. a plurality of marks arranged in the main scanning direction are formed on the recording medium;
The detection unit moves the recording medium from one side to the other side in the sub-scanning direction by a first distance with respect to the optical sensor at one mark, and moves the recording medium to the other side in the sub-scanning direction. after the carriage is moved from one side to the other side by the first distance, the carriage is moved from one side to the other side in the main scanning direction by a second distance; Detecting the number of ends for each mark toward the other side,
The judging unit judges that an ejection failure has occurred in the nozzle when the number of ends is 8 or more,
7. The inkjet according to any one of claims 1 to 6, wherein the control device includes an identification unit that identifies the nozzle row determined by the determination unit to have an ejection failure of the nozzle. printer. When the color of the recording medium and the color of the mark are the same, the mark forming section, before forming the mark, forms the mark on the recording medium in an area wider than the area where the mark is formed on the recording medium. forming an underlayer formed of a color different from the color of the mark and the color of the mark;
The inkjet printer according to any one of claims 1 to 8, wherein the detection unit detects the number of edges based on the second amount of light received and the third amount of light reflected by the base layer. After moving the recording medium in the sub-scanning direction by the length of the sub-scanning direction between the adjacent nozzles, one mark moves the recording medium by the length of the nozzle row in the sub-scanning direction. 10. The recording medium is formed by moving in the sub-scanning direction and then moving the recording medium in the sub-scanning direction by a length between adjacent nozzles in the sub-scanning direction. The inkjet printer described in .

Images