Liquid ejection device and program

Abstract

To provide means that can reduce a time elapsing until liquid discharge processing is completed, in a case where some nozzle row includes an abnormal nozzle.SOLUTION: A head 32 includes a plurality of nozzle rows in which a plurality of nozzles 33 are arranged in a sub scanning direction at predetermined pitch. The nozzles 33 are positioned at positions deviated in the sub scanning direction, between the plurality of nozzle rows. A control part 40 determines whether there is an abnormal nozzle row in the plurality of nozzle rows or not; when determining that there is no abnormal nozzle row, performs processing for forming one line of an image with a dot group with ink discharged from the nozzles 33 of two nozzle rows; and when determining that there is an abnormal nozzle row, performs processing for forming one line of an image with a dot group with ink discharged from the nozzles 33 of one nozzle row.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus that ejects liquid onto a sheet, and a program therefor. [Background technology]

[0002] Patent Document 1 describes a liquid ejection device capable of forming dots on a medium at high resolution and high speed. This liquid ejection device includes a first nozzle row in which a plurality of nozzles are arranged at a predetermined pitch, and a second nozzle row in which a plurality of nozzles are arranged at the same pitch but offset in the nozzle arrangement direction from the position of the first nozzle row, and forms dots in either a first mode or a second mode. In the second mode, the first dot row formed by the nozzles in the first nozzle row and the second dot row formed by the nozzles in the second nozzle row are offset in the vertical direction from the nozzle arrangement direction, and the distance between the first dot rows is set larger than in the first mode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-320110 Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid ejection device, nozzle ejection defects occur. In a liquid ejection device having multiple nozzle rows, if an ejection defect occurs in a nozzle included in one of the nozzle rows, a maintenance process is performed to resolve the ejection defect before the instructed liquid ejection process is performed. This increases the time until the liquid ejection process is completed.

[0005] The present invention has been made in view of the above circumstances, and its purpose is to provide a means for shortening the time until the liquid ejection process is completed when some nozzle rows include abnormal nozzles. [Means for solving the problem]

[0006] (1) A liquid ejection device of the present invention includes a first nozzle row in which a plurality of nozzles are arranged at a predetermined pitch in a first direction, a second nozzle row in which a plurality of nozzles are arranged at the predetermined pitch in the first direction, a head including at least the first nozzle row and the second nozzle row, a carriage carrying the head and moving in a second direction intersecting the first direction, and a control unit. The nozzles in the second nozzle row are positioned offset in the first direction from the nozzles in the first nozzle row. the control unit executes a determination process to determine whether the first nozzle row and the second nozzle row include an abnormal nozzle row, a first ejection process to control the first nozzle row, the second nozzle row, and the carriage so as to form one line of an image to be formed with a group of dots formed by liquid ejected from a first nozzle in the first nozzle row and a group of dots formed by liquid ejected from a second nozzle in the second nozzle row that corresponds to the first nozzle, and a second ejection process to control the first nozzle row, the second nozzle row, and the carriage so as to form one line of the image with a group of dots formed by liquid ejected from a nozzle in a normal nozzle row that does not include an abnormal nozzle, in the first ejection process, a distance in the second direction between dots formed by liquid ejected from the first nozzle in the first ejection process is greater than a distance in the second direction between dots formed by liquid ejected from the first nozzle in the second ejection process.

[0007] According to the liquid ejection device, if there is no abnormal nozzle row, liquid is ejected from the nozzles in all nozzle rows to form one line of an image. If there is an abnormal nozzle row, liquid is ejected from the nozzles in the normal nozzle row to form one line of an image. Therefore, if some nozzle rows include abnormal nozzles, the liquid ejection process can be performed without performing maintenance, and the time until the liquid ejection process is completed can be shortened.

[0008] (2) Preferably, the head further includes a third nozzle row in which a plurality of nozzles are aligned at the predetermined pitch in the first direction, and a fourth nozzle row in which a plurality of nozzles are aligned at the predetermined pitch in the first direction. In the determination process, the control unit determines whether or not there is an abnormal nozzle row among the first to fourth nozzle rows, and in response to determining in the determination process that there is no abnormal nozzle row, in the first ejection process, moves the carriage once to form one line of the image with a group of dots formed by liquid ejected from the first nozzles and a group of dots formed by liquid ejected from the second nozzles, and forms adjacent lines of the image with a group of dots formed by liquid ejected from a third nozzle in the third nozzle row that corresponds to the first nozzle, and a fourth nozzle in the fourth nozzle row that corresponds to the first nozzle. and controls the first to fourth nozzle rows and the carriage so that one line of the image is formed with a group of dots made of liquid ejected from nozzles in the first used nozzle row, and the carriage so that an adjacent line of the image is formed with a group of dots made of liquid ejected from the corresponding nozzles in the second used nozzle row, and in response to determining in the determination process that there are one or two abnormal nozzle rows, a first used nozzle row and a second used nozzle row are determined from the normal nozzle rows in the second ejection process, and the carriage is moved once to form one line of the image with a group of dots made of liquid ejected from nozzles in the first used nozzle row, and the carriage so that an adjacent line of the image is formed with a group of dots made of liquid ejected from the corresponding nozzles in the second used nozzle row.

[0009] (3) Preferably, the second nozzles are located at a position shifted from the first nozzles by ¼ of the predetermined pitch in the first direction, the third nozzles are located at a position shifted from the first nozzles by ½ of the predetermined pitch in the first direction, and the fourth nozzles are located at a position shifted from the first nozzles by ¾ of the predetermined pitch in the first direction. In response to determining in the determination process that there are one or two abnormal nozzle rows, the control unit determines the first nozzle row and the third nozzle row, or the second nozzle row and the fourth nozzle row, as the first used nozzle row and the second used nozzle row in the second ejection process.

[0010] (4) Preferably, in response to determining in the determination process that there are three abnormal nozzle rows, the control unit controls the first to fourth nozzle rows and the carriage in the second ejection process by moving the carriage back and forth so as to form one line of the image with a group of dots made of liquid ejected from nozzles in the normal nozzle rows.

[0011] (5) Preferably, in response to determining in the determination process that there is at least one but not more than three abnormal nozzle rows, the control unit compares a first required time when performing the maintenance process and the first ejection process with a second required time when performing the second ejection process without performing the maintenance process, and in response to determining that the first required time is shorter than the second required time, performs the first ejection process after performing the maintenance process, and in response to determining that the second required time is shorter than the first required time, performs the second ejection process before performing the maintenance process.

[0012] (6) The program of the present invention is a program for a liquid ejection device comprising: a first nozzle row in which a plurality of nozzles are arranged in a first direction at a predetermined pitch; a second nozzle row in which a plurality of nozzles are arranged in the first direction at the same predetermined pitch; a head including at least the first nozzle row and the second nozzle row; a carriage carrying the head and moving in a second direction intersecting the first direction; and a control unit, wherein the nozzles in the second nozzle row are positioned offset in the first direction from the nozzles in the first nozzle row. The program causes the control unit to execute a determination process to determine whether the first nozzle array and the second nozzle array include an abnormal nozzle, a first ejection process to control the first nozzle array, the second nozzle array, and the carriage in response to a determination that there is no abnormal nozzle array in the determination process, so that one line of an image to be formed is formed with dots formed by liquid ejected from first nozzles in the first nozzle array and dots formed by liquid ejected from second nozzles in the second nozzle array that correspond to the first nozzles, and a second ejection process to control the first nozzle array, the second nozzle array, and the carriage in response to a determination that there is an abnormal nozzle array in the determination process, so that one line of the image is formed with dots formed by liquid ejected from nozzles in a normal nozzle array that does not include an abnormal nozzle. The distance in the second direction between dots formed by liquid ejected from the first nozzles in the first ejection process is greater than the distance in the second direction between dots formed by liquid ejected from the first nozzles in the second ejection process. [Effects of the Invention]

[0013] According to the present invention, when some nozzle rows include abnormal nozzles, the time until the liquid ejection process is completed can be shortened. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of the appearance of a printer 10 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view that schematically shows the internal structure of the printer 10. As shown in FIG. [Figure 3] FIG. 3 is a block diagram of a printing system including a printer 10 and a computer 100. As shown in FIG. [Figure 4] Figure 4(A) is a diagram showing the arrangement of nozzles 33 in head 32, Figure 4(B) is an enlarged view of an image printed in high-quality mode, and Figure 4(C) is an enlarged view of an image printed in high-speed mode. [Figure 5] FIG. 5 is a flowchart of the high-speed mode printing process. [Figure 6] FIG. 6 is a flowchart of the print time determination process. [Figure 7] FIG. 7A is a flowchart of the process for determining the nozzle array to be used, and FIG. 7B is a flowchart of the image processing. [Figure 8] FIG. 8 is a flowchart of the printing process. [Figure 9] FIG. 9(A) is a diagram showing an example in which the head 32 includes one abnormal nozzle row, and FIG. 9(B) is a diagram showing a method for printing an image in which the head 32 includes one abnormal nozzle row. [Figure 10] Figure 10(A) is a diagram showing an example in which the head 32 includes three abnormal nozzle rows, and Figure 10(B) is a diagram showing a method for printing an image in which the head 32 includes three abnormal nozzle rows. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below. Note that the embodiment described below is merely one example of the present invention, and it goes without saying that the embodiment of the present invention can be modified as appropriate without departing from the spirit of the present invention. In the following description, the direction of travel from the start point of an arrow to the end point is expressed as a "direction," and the direction of travel on the line connecting the start point and end point of an arrow is expressed as a "direction." Furthermore, the up-down direction 7 is defined based on the state in which the printer 10 is installed and ready for use (the state shown in FIG. 1 ), the front-rear direction 8 is defined with the surface of the printer 10 on which the opening 13 is formed as the front, and the left-right direction 9 is defined when viewing the printer 10 from the front. The up-down direction 7, the front-rear direction 8, and the left-right direction 9 are perpendicular to one another.

[0016] [Printer 10 Overview] The printer 10 according to this embodiment is an example of a liquid ejection device that ejects liquid onto a sheet using an inkjet printing method. The printer 10 is a monochrome printer that ejects black ink (an example of a liquid) onto a sheet. The printer 10 may also be a so-called "multifunction device" that has functions such as a facsimile function, a scanning function, and a copying function.

[0017] The printer 10 has a roughly rectangular parallelepiped housing 11. As shown in Figures 1 and 2, inside the housing 11 are located a feed tray 14, a feed roller 21, a transport roller 22, a carriage 31, a head 32 mounted on the carriage 31 and having a plurality of nozzles 33, a platen 23 facing the head 32, a discharge roller 24, a discharge tray 15, a subtank 35, an attachment case 36 into which a cartridge 37 can be attached, and a tube 34 that connects the cartridge 37 attached to the attachment case 36 and the head 32.

[0018] The printer 10 drives the feed roller 21 and the transport roller 22 to transport the sheet supported on the feed tray 14 along the transport path (the path indicated by the dashed line in FIG. 2) to the position of the platen 23. Next, the printer 10 ejects ink, which is supplied from the cartridge 37 mounted in the mounting case 36 via the subtank 35 and the tube 34, from the nozzles 33 of the head 32. This causes the ink to land on the sheet supported on the platen 23, and the image to be formed is printed on the sheet. The printer 10 drives the discharge roller 24 to discharge the sheet on which the image has been printed onto the discharge tray 15.

[0019] The carriage 31 is supported by two guide rails (not shown) extending in the left-right direction 9, and moves back and forth in the left-right direction 9, which intersects with the transport direction (front-rear direction 8) of the transport rollers 22. The printer 10 ejects ink from the nozzles 33 of the head 32 while the carriage 31 moves in the left-right direction 9. This causes an image to be printed on a portion of the sheet facing the head 32. Next, the printer 10 causes the transport rollers 22 to transport the sheet so that the area where the next image is to be printed faces the head 32. By alternately repeating these processes, an image is printed on the sheet.

[0020] As shown in FIG. 1, the housing 11 has a cover 18 on the front surface 12 of the housing 11 and at the right end in the left-right direction 9. An opening (not shown) is formed at the position of the cover 18. The cover 18 is rotatable between a position in which the opening is closed (the position shown in FIG. 1) and a position in which the opening is open. A single mounting case 36 is located in the storage space inside the housing 11 that extends beyond the opening. A cartridge 37 containing black ink is mounted in the mounting case 36.

[0021] The cartridge 37 has a liquid chamber 38 (see FIG. 2) capable of storing ink. When the cartridge 37 is mounted in the mounting case 36, the ink stored in the liquid chamber 38 flows into the subtank 35 via an ink flow path 39 that connects the liquid chamber 38 and the subtank 35. The subtank 35 temporarily stores the ink that has flowed in. The ink stored in the subtank 35 is supplied to the head 32 via a tube 34.

[0022] [Control unit 40] The control unit 40 shown in FIG. 3 is located inside the housing 11. The control unit 40 includes a CPU 41, a ROM 42, a RAM 43, an EEPROM 44, and an ASIC 45. The ROM 42 stores programs and the like for the CPU 41 to execute various processes. The RAM 43 is used as a storage area for temporarily recording data, signals, and the like used when the CPU 41 executes a program, or as a working area for data processing. The EEPROM 44 stores information that should be retained even after the power is turned off. The ROM 42, RAM 43, and EEPROM 44 are examples of memory of the printer 10.

[0023] The ASIC 45 is used to operate the feed roller 21, the transport roller 22, the discharge roller 24, and the head 32. The control unit 40 drives a motor (not shown) via the ASIC 45 to rotate the feed roller 21, the transport roller 22, and the discharge roller 24. The control unit 40 outputs a drive signal to a drive element (not shown) of the head 32 via the ASIC 45, thereby causing ink to be ejected from the nozzles 33 of the head 32. The ASIC 45 outputs a drive signal according to the amount of ink to be ejected from the nozzles 33.

[0024] A display 16 and an operation panel 17 are connected to the ASIC 45. The display 16 is, for example, a liquid crystal display, an organic EL display, or the like. The display 16 displays, for example, the status of the printer 10 on a screen. The operation panel 17 outputs an operation signal to the control unit 40 in response to an operation by a user. The operation panel 17 may have, for example, a push button or a touch sensor superimposed on the display 16.

[0025] A communication interface 46 is connected to the ASIC 45. The communication interface 46 is an interface for communication between the printer 10 and other devices. The communication interface 46 is, for example, a wireless or wired communication interface such as USB, Wi-Fi, or Bluetooth (registered trademark). The printer 10 controls the communication interface 46 to communicate with other devices connected to the printer 10.

[0026] [Computer 100] In the printing system shown in FIG. 3, a computer 100 is connected to a printer 10. The computer 100 may be any type of computer connectable to the printer 10. The computer 100 may be, for example, a personal computer or a mobile phone. The computer 100 includes a CPU 101, a RAM 102, a storage unit 103, an input unit 104, a display unit 105, and a communication interface 106. The CPU 101, RAM 102, and storage unit 103 function as a control unit 110 of the computer 100. The storage unit 103 may be, for example, a hard disk or an SSD drive. The storage unit 103 stores programs for the CPU 101 to execute various processes. The programs stored in the storage unit 103 include a printer driver that controls the printer 10. The RAM 102 is used as a storage area for temporarily recording data, signals, and the like used by the CPU 101 when executing programs, or as a work area for data processing. The communication interface 106 is an interface for communicating with the printer 10. The RAM 102 and the storage unit 103 are an example of a memory of the printing system.

[0027] The control unit 40 of the printer 10 performs various processes by having the CPU 41 execute programs stored in the RAM 43. The control unit 110 of the computer 100 performs various processes by having the CPU 101 execute programs stored in the RAM 102. These programs may be stored on a computer-readable storage medium. A computer-readable storage medium is a non-transitory medium. Non-transitory media include recording media such as ROM, RAM, EEPROM, hard disks, and SSD drives, as well as CD-ROMs and DVD-ROMs. Non-transitory media are also tangible media. On the other hand, an electrical signal carrying a program downloaded from a server on the Internet is a computer-readable signal medium, which is a type of computer-readable medium, but is not included in non-transitory computer-readable storage media.

[0028] [Nozzle 33 placement] FIG. 4A shows the arrangement of the nozzles 33 in the head 32. In FIG. 4A, the horizontal direction is the movement direction of the carriage 31, and the vertical direction is the sheet transport direction. In the following description, the former is referred to as the main scanning direction, and the latter is referred to as the sub-scanning direction. In this embodiment, the main scanning direction and the sub-scanning direction are perpendicular to each other. The white circles shown in FIG. 4A indicate the positions of the nozzles 33 when the head 32 is viewed from above.

[0029] The head 32 includes a first nozzle row K1, a second nozzle row K2, a third nozzle row K3, and a fourth nozzle row K4. The first nozzle row K1 has a plurality of nozzles 33 arranged in the sub-scanning direction at a pitch P. The second to fourth nozzle rows K2 to K4 each have the same number of nozzles 33 as the first nozzle row K1 arranged in the sub-scanning direction at the same pitch P. In this embodiment, the pitch P is 1 / 300 inch. The second nozzle row K2 is located to the right of the first nozzle row K1. The third nozzle row K3 is located to the right of the second nozzle row K2. The fourth nozzle row K4 is located to the right of the third nozzle row K3. The distance in the main scanning direction between two nozzle rows is arbitrary.

[0030] The positions of the nozzles 33 in the second nozzle row K2 in the sub-scanning direction are offset by ¼ of the pitch P (i.e., 1 / 1200 inch) from the positions of the nozzles 33 in the first nozzle row K1 in the sub-scanning direction. The positions of the nozzles 33 in the third nozzle row K3 in the sub-scanning direction are offset by ½ of the pitch P from the positions of the nozzles 33 in the first nozzle row K1 in the sub-scanning direction. The positions of the nozzles 33 in the fourth nozzle row K4 in the sub-scanning direction are offset by ¾ of the pitch P from the positions of the nozzles 33 in the first nozzle row K1 in the sub-scanning direction. The sub-scanning direction is an example of a first direction. The main scanning direction is an example of a second direction.

[0031] The nozzles 33 in the first to fourth nozzle rows K1 to K4 are divided into groups of four in the order of arrangement in the sub-scanning direction, and the four nozzles 33 in each group correspond to one another. For example, the nozzles 33 located in the first to fourth rows correspond to one another, and the nozzles 33 located in the fifth to eighth rows correspond to one another.

[0032] 4A shows four nozzles 33 for each nozzle row, but the number of nozzles 33 in each nozzle row is actually more than 4. Also, although the head 32 is described as including four nozzle rows, the head 32 may include two, three, or five or more nozzle rows.

[0033] As a method for arranging multiple nozzles 33 in the manner shown in Figure 4(A), in addition to forming multiple nozzles 33 in head 32 so that the position in the sub-scanning direction differs for each nozzle row, there is also a method in which multiple nozzles 33 are formed in head 32 so that the position in the sub-scanning direction is the same for each nozzle row, and head 32 is attached to carriage 31 at a small angle (rotated a small angle in the horizontal plane).

[0034] [Printer 10 operating mode] The printer 10 operates in either a high-quality mode or a high-speed mode. Fig. 4(B) shows an enlarged image printed in the high-quality mode. Fig. 4(C) shows an enlarged image printed in the high-speed mode. The black circles shown in Figs. 4(B) and 4(C) represent dots formed by ink ejected from the nozzles 33.

[0035] In the high-quality mode (FIG. 4(B)), the carriage 31 moves in the main scanning direction at a predetermined speed, and ink is ejected from the nozzles 33 in the first to fourth nozzle rows K1 to K4 every time the carriage 31 moves 1 / 600 inch in the main scanning direction. In this case, one line of an image is formed by a group of dots formed by ink ejected from one nozzle 33. Therefore, in the high-quality mode, an image with a resolution of 600 dpi in the main scanning direction and 1200 dpi in the sub-scanning direction is printed on the sheet.

[0036] In high-speed mode (FIG. 4C), the carriage 31 moves in the main scanning direction at a faster speed than in high-quality mode, and ink is ejected from the nozzles 33 in the first to fourth nozzle rows K1 to K4 every 1 / 300 inch that the carriage 31 moves in the main scanning direction. However, the timing of ink ejection from the nozzles 33 in the second nozzle row K2 and the fourth nozzle row K4 is delayed by the time it takes for the carriage 31 to move 1 / 600 inch in the main scanning direction compared to the timing of ink ejection from the nozzles 33 in the first nozzle row K1 and the third nozzle row K3.

[0037] In this case, one line of the image is formed by a group of dots formed by ink ejected from one nozzle 33 and a group of dots formed by ink ejected from an adjacent nozzle 33. Specifically, odd-numbered lines of the image are formed by a group of dots formed by ink ejected from the nozzles 33 in the first nozzle row K1 and a group of dots formed by ink ejected from the nozzles 33 in the second nozzle row K2. Even-numbered lines of the image are formed by a group of dots formed by ink ejected from the nozzles 33 in the third nozzle row K3 and a group of dots formed by ink ejected from the nozzles 33 in the fourth nozzle row K4. The spacing between dots in the main scanning direction is 1 / 600 inch. Therefore, in high-speed mode, an image is printed with a resolution of 600 dpi in the main scanning direction and 600 dpi in the sub-scanning direction.

[0038] The distance in the main scanning direction between dots formed by ink ejected from the first nozzle row K1 is 1 / 600 inch in high-quality mode and 1 / 300 inch in high-speed mode. Thus, the distance in the main scanning direction between dots formed by ink ejected from the nozzles 33 in the first nozzle row K1 in high-speed mode is greater than the distance in the main scanning direction between dots formed by ink ejected from the nozzles 33 in the first nozzle row K1 in high-quality mode.

[0039] [High-speed mode printing taking into account abnormal nozzles] In the printer 10, an ejection defect occurs in the nozzle 33. In the following explanation, the nozzle in which the ejection defect occurs is referred to as an "abnormal nozzle," a nozzle row that includes one or more abnormal nozzles is referred to as an "abnormal nozzle row," and a nozzle row that does not include an abnormal nozzle is referred to as a "normal nozzle row."

[0040] When the control unit 40 of the printer 10 receives an instruction for high-speed mode printing, it executes the high-speed mode printing process shown in Figures 5 to 8. As will be described below, in the high-speed mode printing process, the control unit 40 obtains the number of abnormal nozzle rows among the first to fourth nozzle rows K1 to K4, and performs processing according to the obtained number.

[0041] The control unit 40 executes a discharge detection process (S11) at the beginning of the high-speed mode printing process (FIG. 5). In S11, the control unit 40 causes all nozzles 33 in the first through fourth nozzle rows K1 through K4 to discharge a small amount of ink, and detects whether or not a discharge defect has occurred in each nozzle 33 based on the current level or voltage level of the drive signal supplied to the head 32 at that time. Based on the discharge defect detection results, the control unit 40 acquires the number of abnormal nozzle rows among the first through fourth nozzle rows K1 through K4 and the degree of discharge defect in each nozzle row. The degree of discharge defect is expressed in three levels, for example, level 1, level 2, and level 3.

[0042] Next, the control unit 40 determines whether the number of abnormal nozzle arrays obtained in the discharge detection process (S11) is 0, 1 to 3, or 4 (S12). If the control unit 40 determines in S12 that the number of abnormal nozzle arrays is 0 (S12: 0), the control unit 40 proceeds to S13. If the first through fourth nozzle arrays K1-K4 are all normal nozzle arrays, the control unit 40 prints the image in high-speed mode using all nozzle arrays. In this case, the control unit 40 sets the delay flag to ON (S13) and then executes the printing process (FIG. 8) (S14).

[0043] If the control unit 40 determines in S12 that the number of abnormal nozzle rows is four (S12: 4), it proceeds to S27. If all of the first through fourth nozzle rows K1-K4 are abnormal nozzle rows, the control unit 40 executes a purge process and then prints an image in high-speed mode using all of the nozzle rows. In this case, the control unit 40 executes the purge process (S27), then sets the delay flag to ON (S28), and then executes the printing process (FIG. 8) (S29). The purge process is a process in which a sufficient amount of ink is ejected from all of the nozzles 33 included in the head 32 to eliminate ejection defects. The purge process is an example of a maintenance process.

[0044] If the control unit 40 determines in S12 that the number of abnormal nozzle arrays is between one and three (S12: between one and three), the control unit 40 proceeds to S21. If the number of abnormal nozzle arrays is between one and three, the control unit 40 prints the image in high-quality mode using normal nozzle arrays among the first through fourth nozzle arrays K1-K4. In this case, the control unit 40 first executes the print time determination process (FIG. 6) (S21).

[0045] At the beginning of the printing time determination process, the control unit 40 obtains a purge time Tpu (S31) based on the degree of ejection defects of each nozzle array obtained in the ejection detection process (S11). The EEPROM 44 pre-stores purge times corresponding to the degree of ejection defects for each of the first through fourth nozzle arrays K1-K4. For example, if the degree of ejection defects of the first nozzle array K1 is level 1, the second nozzle array K2 is a normal nozzle array, the degree of ejection defects of the third nozzle array K3 is level 2, and the degree of ejection defects of the fourth nozzle array K4 is level 3, the purge time Tpu is calculated according to the following equation (1). Tpu = T11 + T32 + T43 … (1) However, in equation (1), T11, T32, and T43 are purge times stored in EEPROM 44, where T11 is the purge time when the degree of ejection failure of the first nozzle row K1 is level 1, T32 is the purge time when the degree of ejection failure of the third nozzle row K3 is level 2, and T43 is the purge time when the degree of ejection failure of the fourth nozzle row K4 is level 3.

[0046] Next, the control unit 40 acquires the ISO print times Tpr_300 and Tpr_600 per sheet based on the sheet size (S32). The ISO print time is the time required to print a standard image defined by the ISO. The EEPROM 44 pre-stores, for each sheet size, such as A3, B4, A4, and B5, the time required to print an ISO standard image at a resolution of 300 dpi and the time required to print an ISO standard image at a resolution of 600 dpi. For example, if the sheet size is A4, the control unit 40 in S32 determines the time required to print an A4 ISO standard image at a resolution of 300 dpi as the ISO print time Tpr_300 and the time required to print an A4 ISO standard image at a resolution of 600 dpi as the ISO print time Tpr_600.

[0047] Next, the control unit 40 calculates the time T1 required to perform the purge process according to the following equation (2) (S33). T1 = Tpr_300 × number of prints + Tpu … (2) The required time T1 calculated in S33 is an example of a first required time.

[0048] Next, the control unit 40 determines whether the number of abnormal nozzle arrays obtained in the discharge detection process (S11) is three (S34). If the control unit 40 determines in S34 that the number of abnormal nozzle arrays is three (S34: Yes), the control unit 40 proceeds to S35. In this case, the control unit 40 calculates the required time T2 when the purge process is not executed according to the following equation (3) (S35). T2 = Tpr_600 × number of prints × 2 … (3)

[0049] If the control unit 40 determines in S34 that the number of abnormal nozzle arrays is not three (that is, it is one or two) (S34: No), the control unit 40 proceeds to S36. In this case, the control unit 40 calculates the required time T2 when the purge process is not executed according to the following equation (4) (S36). T2 = Tpr_600 × number of prints … (4)

[0050] As will be described later, when there are one or two abnormal nozzle rows, the control unit 40 performs one pass of printing using two normal nozzle rows. On the other hand, when there are three abnormal nozzle rows, the control unit 40 performs two passes of printing using one normal nozzle row. For this reason, the required time T2 when there are three abnormal nozzle rows is twice the required time T2 when there are one or two abnormal nozzle rows. The required time T2 calculated in S35 or S36 is an example of the second required time.

[0051] Next, the control unit 40 determines whether the required time T2 is shorter than the required time T1 (S37). If the control unit 40 determines in S37 that the required time T2 is shorter than the required time T1 (S37: Yes), the control unit 40 proceeds to S38. In this case, the control unit 40 determines the result of the printing time determination process as "time-saving effect achieved" (S38).

[0052] If the control unit 40 determines in S37 that the required time T2 is equal to or greater than the required time T1 (S37: No), the control unit 40 proceeds to S39. In this case, the control unit 40 determines that the result of the printing time determination process is "no time-saving effect" (S39). Thereafter, the control unit 40 ends the printing time determination process and returns to the state immediately after S21 shown in FIG. 5.

[0053] Returning to FIG. 5, next, the control unit 40 determines whether the result of the printing time determination process is "time-saving effective" (S22). If the control unit 40 determines in S22 that the result of the printing time determination process is "time-saving ineffective" (S22: No), the control unit 40 proceeds to S27. In this case, the control unit 40 executes the purge process (S27), as in the case where the control unit 40 determines in S12 that the number of abnormal nozzle arrays is four, then sets the delay flag to ON (S28), and then executes the printing process (FIG. 8) (S29).

[0054] If the control unit 40 determines in S22 that there is a time-saving effect (S22: Yes), the control unit 40 proceeds to S23. In this case, the control unit 40 executes the nozzle array determination process (FIG. 7A) (S23), and then executes the image processing (FIG. 7B) (S24).

[0055] 7(A), at the beginning of the use nozzle array determination process, the control unit 40 determines whether the number of abnormal nozzle arrays acquired in the discharge detection process (S11) is one, two, or three (S41). If the control unit 40 determines in S41 that the number of abnormal nozzle arrays is one (S41: 1), the control unit 40 proceeds to S42. In this case, the control unit 40 determines whether at least one of the second nozzle array K2 and the fourth nozzle array K4 is an abnormal nozzle array (S42).

[0056] If the control unit 40 determines in S42 that the second nozzle row K2 and the fourth nozzle row K4 are not abnormal nozzle rows (S42: No), the control unit 40 proceeds to S43. In this case, the control unit 40 sets the number of nozzle rows to 2, and determines the second nozzle row K2 and the fourth nozzle row K4 to be the nozzle rows to be used (S43).

[0057] If the control unit 40 determines in S42 that at least one of the second nozzle row K2 and the fourth nozzle row K4 is an abnormal nozzle row (S42: Yes), the control unit 40 proceeds to S44. In this case, the control unit 40 sets the number of active nozzle rows to two, and determines the first nozzle row K1 and the third nozzle row K3 to be the active nozzle rows (S44). In this way, when the number of abnormal nozzles is one or two, the control unit 40 determines the first nozzle row K1 and the third nozzle row K3, or the second nozzle row K2 and the fourth nozzle row K4, as the two active nozzle rows.

[0058] In response to determining in S41 that the number of abnormal nozzle arrays is two (S41: 2), the control unit 40 proceeds to S45. In this case, the control unit 40 sets the number of active nozzle arrays to 2, and determines the two active nozzle arrays to be the active nozzle arrays (S45).

[0059] In response to determining in S41 that the number of abnormal nozzle arrays is three (S41: 3), the control unit 40 proceeds to S46. In this case, the control unit 40 sets the number of active nozzle arrays to 1, and determines the single active nozzle array to be the single normal nozzle array (S46). After executing any of S43 to S46, the control unit 40 ends the active nozzle array determination process and returns to the state immediately after S23 shown in FIG. 5.

[0060] As shown in Fig. 7(B), at the beginning of the image processing, the control unit 40 determines whether the number of usable nozzle arrays determined in the usable nozzle array determination process (Fig. 7(A)) is two (S51). If the control unit 40 determines in S51 that the number of usable nozzle arrays is two (S51: Yes), the control unit 40 proceeds to S52. In this case, the control unit 40 assigns ejection control data to the two usable nozzle arrays determined in the usable nozzle array determination process (S52).

[0061] For example, if the nozzle arrays to be used are the first nozzle array K1 and the third nozzle array K3, in S52 the control unit 40 determines the ejection control data to be assigned to the nozzles in the first nozzle array K1 based on the ejection control data originally assigned to the nozzles in the first nozzle array K1 and the ejection control data originally assigned to the nozzles in the second nozzle array K2. The control unit 40 also determines the ejection control data to be assigned to the nozzles in the third nozzle array K3 based on the ejection control data originally assigned to the nozzles in the third nozzle array K3 and the ejection control data originally assigned to the nozzles in the fourth nozzle array K4.

[0062] If the control unit 40 determines in S51 that the number of active nozzle arrays is not two (is one) (S51: No), the control unit 40 proceeds to S53. In this case, the control unit 40 assigns ejection control data to the one active nozzle array determined in the active nozzle array determination process (S53).

[0063] For example, if the nozzle row to be used is the first nozzle row K1, in S53 the control unit 40 determines the ejection control data to be assigned to the nozzles in the first nozzle row K1 based on the ejection control data originally assigned to the nozzles in the first nozzle row K1, the ejection control data originally assigned to the nozzles in the second nozzle row K2, the ejection control data originally assigned to the nozzles in the third nozzle row K3, and the ejection control data originally assigned to the nozzles in the fourth nozzle row K4.

[0064] After executing S52 or S53, the control unit 40 ends the print process and returns to immediately after S24 shown in Figure 5. Next, the control unit 40 executes the print process (S25), followed by the purge process (S26). After executing any of S14, S25, and S29, the control unit 40 ends the high-speed mode print process.

[0065] 8, at the beginning of the printing process, the control unit 40 determines whether the delay flag is ON (S61). If the control unit 40 determines in S61 that the delay flag is ON (S61: Yes), the control unit 40 proceeds to S62. In this case, the control unit 40 delays the ink ejection timing from the nozzles 33 in the second nozzle row K2 and the fourth nozzle row K4 relative to the ink ejection timing from the nozzles 33 in the first nozzle row K1 and the third nozzle row K3 by the time it takes for the carriage 31 to move 1 / 600 inch (S62). If the control unit 40 determines in S61 that the delay flag is not ON (S61: No), the control unit 40 proceeds to S63 without executing S62.

[0066] Next, the control unit 40 feeds the sheet supported on the feed tray 14 (S63). In S63, the control unit 40 drives a feed motor (not shown). As a result, the feed rollers 21 feed the sheet supported on the feed tray 14 to the conveyance path. The control unit 40 also drives a conveyance motor (not shown). As a result, when the leading edge of the sheet fed to the conveyance path by the feed rollers 21 reaches the conveyance rollers 22, the conveyance rollers 22 convey the sheet forward along the conveyance path.

[0067] Next, the control unit 40 prints one pass on the sheet (S64). In printing one pass, the control unit 40 ejects ink from the nozzles 33 of the head 32 while moving the carriage 31 once in the left-right direction 9. In S64, the control unit 40 executes a process of controlling the first to fourth nozzle rows K1 to K4 and the carriage 31 so that one line of the image is formed with ink ejected from the nozzles in the normal nozzle rows.

[0068] In S64 (S64 when the delay flag is set ON) in the printing process of S14 and S29, the control unit 40 performs printing in high-speed mode. In this case, two lines of an image are formed by groups of dots formed by ink ejected from four nozzles 33 belonging to the same group in the first to fourth nozzle rows K1 to K4. For example, as shown in FIG. 4C, the first line of the image is formed by groups of dots formed by ink ejected from the nozzles 33 located in the first row and groups of dots formed by ink ejected from the nozzles 33 located in the second row. The second line of the image is formed by groups of dots formed by ink ejected from the nozzles 33 located in the third row and groups of dots formed by ink ejected from the nozzles 33 located in the fourth row.

[0069] In S64 of the printing process of S25 (S64 when the delay flag is not set ON), the control unit 40 performs printing in high-quality mode. In S64 when the number of abnormal nozzles is one or two, two lines of the image are formed by groups of dots made by ink ejected from two nozzles 33 belonging to the same group in the two working nozzle arrays determined in the working nozzle array determination process (S23).

[0070] 9(A) and 10(A), the nozzles 33 marked with a cross are abnormal nozzles where ejection defects have occurred. In the example shown in Fig. 9(A), the second nozzle row K2 is the abnormal nozzle row. In this case, the first nozzle row K1 and the third nozzle row K3 are determined to be the nozzle rows to be used, and the first line of the image is formed by a group of dots formed by ink ejected from the nozzles 33 located in the first row, and the second line of the image is formed by a group of dots formed by ink ejected from the nozzles 33 located in the third row (see Fig. 9(B)).

[0071] In S64, when the number of abnormal nozzles is three, odd-numbered lines of the image are formed with groups of dots made of ink ejected from the nozzles 33 in one active nozzle array determined in the active nozzle array determination process (S23). Even-numbered lines of the image are formed with groups of dots made of ink ejected from the same nozzles 33 the next time the control unit 40 reaches S64. In the example shown in FIG. 10(A), the second to fourth nozzle arrays K2-K4 are abnormal nozzle arrays. In this case, the first nozzle array K1 is determined to be the active nozzle array, and in the preceding pass, the first line of the image is formed with groups of dots made of ink ejected from the nozzles 33 located in the first row, and in the subsequent pass, the second line of the image is formed with groups of dots made of ink ejected from the same nozzles 33 (nozzles 33 located in the first row) (see FIG. 10(B)).

[0072] Next, the control unit 40 determines whether printing for one sheet has been completed (S65). If the control unit 40 determines in S65 that printing for one sheet has not been completed (S65: No), the control unit 40 proceeds to S66. In this case, the control unit 40 conveys the sheet by a predetermined amount (S66). In S66, the control unit 40 drives the conveyance motor to cause the conveyance rollers 22 and the discharge rollers 24 to convey the sheet by the predetermined amount. Thereafter, the control unit 40 proceeds to S64.

[0073] If the control unit 40 determines in S65 that printing for one sheet has been completed (S65: Yes), the control unit 40 proceeds to S67. In this case, the control unit 40 discharges the sheet (S67). In S67, the control unit 40 causes the conveying rollers 22 and the discharge rollers 24 to convey the sheet by a predetermined amount and discharge it onto the discharge tray 15.

[0074] Next, the control unit 40 determines whether all printing has been completed (S68). If the control unit 40 determines in S68 that all printing has not been completed (S68: No), it proceeds to S63. In this case, the control unit 40 executes S63 to S67 to print the next page. If the control unit 40 determines in S68 that all printing has been completed (S68: Yes), it ends the printing process and returns to immediately after any of S14, S25, and S29 shown in FIG. 5.

[0075] 5, S11 is an example of a determination process, S14 is an example of a first ejection process, S25 and S29 are examples of a second ejection process, and S26 and S27 are examples of a maintenance process.

[0076] Thus, when the number of abnormal nozzles is zero, the control unit 40 prints the image in high-speed mode using the four normal nozzle rows (see FIG. 4C). One line of the image is formed by a group of dots made of ink ejected from a nozzle 33 in an odd-numbered nozzle row and a group of dots made of ink ejected from nozzles 33 belonging to the same group in an even-numbered nozzle row. For example, the first line of the image is formed by a group of dots made of ink ejected from the nozzles 33 in the first row and a group of dots made of ink ejected from the nozzles 33 in the second row. The second line of the image is formed by a group of dots made of ink ejected from the nozzles 33 in the third row and a group of dots made of ink ejected from the nozzles 33 in the fourth row. The fifth and subsequent lines of the image are formed in the same manner.

[0077] If the number of abnormal nozzles is four, or if the number of abnormal nozzles is between one and three and there is no time-saving effect, the control unit 40 performs a purge process (S27) and then prints the image in high-speed mode using the four nozzle rows whose ejection problems have been resolved. Each line of the image is formed in the same way as when the number of abnormal nozzles is zero.

[0078] If the number of abnormal nozzles is one or two and there is a time-saving effect, the control unit 40 prints the image in high-quality mode using the two active nozzle arrays determined in the active nozzle array determination process (see FIG. 9). Odd-numbered lines of the image are formed with groups of dots made of ink ejected from the nozzles 33 in one active nozzle array, and even-numbered lines of the image are formed with groups of dots made of ink ejected from the nozzles 33 belonging to the same group in the other active nozzle array. For example, in the example shown in FIG. 9, the first line of the image is formed with groups of dots made of ink ejected from the nozzles 33 in the first row, and the second line of the image is formed with groups of dots made of ink ejected from the nozzles 33 in the third row. The first and second lines of the image are formed in the same pass (one ejection process). The third and subsequent lines of the image are formed in the same way.

[0079] If the number of abnormal nozzles is three and there is a time-saving effect, the control unit 40 prints the image in high-quality mode using the single nozzle row to be used determined in the nozzle row to be used determination process (see FIG. 10). The odd-numbered lines of the image are formed with dots made of ink ejected from the nozzles 33 in the nozzle row to be used in the preceding pass, and the even-numbered lines of the image are formed with dots made of ink ejected from the same nozzles 33 in the subsequent pass. For example, in the example shown in FIG. 10, the first line of the image is formed with dots made of ink ejected from the nozzles 33 in the first row in the preceding pass, and the second line of the image is formed with dots made of ink ejected from the nozzles 33 in the first row in the subsequent pass. The first and second lines of the image are formed in different passes (two ejection processes). The third and subsequent lines of the image are formed in the same way.

[0080] [Action and effect] As described above, the printer 10 according to this embodiment includes first to fourth nozzle rows K1 to K4, each having a plurality of nozzles 33 aligned in the sub-scanning direction at a pitch P, a head 32 including the first to fourth nozzle rows K1 to K4, a carriage 31 that carries the head 32 and moves in the main scanning direction, and a control unit 40. The control unit 40 determines whether or not there is an abnormal nozzle row among the first to fourth nozzle rows K1 to K4, and if there is no abnormal nozzle row, performs a process of forming one line of an image with a group of dots made of ink ejected from nozzles in two nozzle rows, and if there is an abnormal nozzle row, performs a process of forming one line of an image with ink ejected from nozzles in a normal nozzle row.

[0081] According to the printer 10, if there is no abnormal nozzle row, liquid is ejected from the nozzles 33 in all nozzle rows to form one line of an image. If there is an abnormal nozzle row, liquid is ejected from the nozzles 33 in the normal nozzle row to form one line of an image. Therefore, if some nozzle rows include abnormal nozzles, the liquid ejection process can be performed without performing maintenance process, and the time until the liquid ejection process is completed can be shortened.

[0082] If there are one or two abnormal nozzles, the control unit 40 determines two working nozzle rows from the normal nozzle rows, moves the carriage 31 once, and performs a process of forming two adjacent lines of the image with dot groups made of ink ejected from the nozzles in the two working nozzle rows. Therefore, if one or two of the four nozzle rows are abnormal nozzle rows, the liquid ejection process can be performed without performing a maintenance process, and the time until the liquid ejection process is completed can be shortened.

[0083] When there are one or two abnormal nozzles, the control unit 40 determines the first nozzle row K1 and the third nozzle row K3, or determines the second nozzle row K2 and the fourth nozzle row K4, as the two nozzle rows to be used. Therefore, when one or two of the four nozzle rows are abnormal nozzle rows, the two nozzle rows to be used are determined so that the spacing in the sub-scanning direction of the nozzles 33 to be used is the same, making it possible to form a high-quality image.

[0084] If there are three abnormal nozzles, the control unit 40 moves the carriage 31 back and forth and performs a process of forming one line of an image with a group of dots made of liquid ejected from the nozzles in the normal nozzle row. Therefore, if three of the four nozzle rows are abnormal, the liquid ejection process can be performed without performing a maintenance process, and the time until the liquid ejection process is completed can be shortened.

[0085] If the number of abnormal nozzles is between one and three, the control unit 40 compares the time T1 required to execute the purge process with the time T2 required to not execute the purge process, and if the required time T1 is shorter than the required time T2, executes the print process after executing the purge process (executes S29 after S27), and if the required time T2 is shorter than the required time T1, executes the print process before executing the purge process (executes S25 before S26). Therefore, if between one and three or less of the four nozzle rows are abnormal nozzle rows, it is possible to determine whether to execute maintenance processing before the ejection process and shorten the time until the liquid ejection process is completed.

[0086] [Variations] The printer 10 according to the above embodiment has a subtank 35. A printer according to a modified example may not have a subtank 35. In the printer 10, the cartridge 37 is mounted in an attachment case 36 outside the carriage 31. In the printer according to the modified example, the cartridge 37 may be mounted in an attachment case on the carriage 31. The printer 10 is a cartridge-type printer in which the cartridge 37 is detachably mounted in the attachment case 36. The printer according to the modified example may be a tank-type printer in which a tank is provided and ink is poured into the tank.

[0087] The present invention can also be applied to liquid ejection devices in which the head 32 includes two, three, or five or more nozzle arrays. In a liquid ejection device including N nozzle arrays (N is a natural number), the pitch in the sub-scanning direction of the nozzles 33 in each nozzle array (hereinafter referred to as the nozzle pitch) may be the same, and the nozzles in the first to Nth nozzle arrays may be sequentially shifted in the sub-scanning direction by 1 / N of the nozzle pitch. For example, in a liquid ejection device including two nozzle arrays, the nozzles in the second nozzle array may be shifted in the sub-scanning direction from the nozzles in the first nozzle array by 1 / 2 of the nozzle pitch. In a liquid ejection device including three nozzle arrays, the nozzles in the second nozzle array may be shifted in the sub-scanning direction from the nozzles in the first nozzle array by 1 / 3 of the nozzle pitch, and the nozzles in the third nozzle array may be shifted in the sub-scanning direction from the nozzles in the first nozzle array by 2 / 3 of the nozzle pitch.

[0088] In the above embodiment, the nozzle pitch is 1 / 300 inch, and in high-speed mode, an image is formed with a resolution of 600 dpi in the main scanning direction and 600 dpi in the sub-scanning direction, but the nozzle pitch in the liquid ejection device and the resolution of the images formed are not limited to the above values. The present invention can also be applied to liquid ejection devices having other nozzle pitches and liquid ejection devices that form images with other resolutions. [Explanation of symbols]

[0089] 10. Printer (liquid ejection device) 31. Carriage 32...head 33 Nozzle 40 Control unit

Claims

1. a first nozzle row in which a plurality of nozzles are arranged at a predetermined pitch in a first direction; a second nozzle row in which a plurality of nozzles are arranged at the predetermined pitch in the first direction; a head including at least the first nozzle row and the second nozzle row; a carriage that carries the head and moves in a second direction that intersects with the first direction; a control unit; the nozzles in the second nozzle row are positioned at positions shifted in the first direction from the nozzles in the first nozzle row, The control unit a determination process for determining whether or not there is an abnormal nozzle row including an abnormal nozzle among the first nozzle row and the second nozzle row; a first ejection process that controls the first nozzle row, the second nozzle row, and the carriage in response to determining in the determination process that there is no abnormal nozzle row, so that one line of an image to be formed is formed by a group of dots made of liquid ejected from first nozzles in the first nozzle row and a group of dots made of liquid ejected from second nozzles in the second nozzle row that correspond to the first nozzles; executing a second ejection process that controls the first nozzle row, the second nozzle row, and the carriage in response to determining that there is an abnormal nozzle row in the determination process, so that one line of the image is formed with a group of dots made of liquid ejected from nozzles in a normal nozzle row that does not include an abnormal nozzle; A liquid ejection device in which the distance in the second direction between dots formed by liquid ejected from the first nozzle in the first ejection process is greater than the distance in the second direction between dots formed by liquid ejected from the first nozzle in the second ejection process.

2. the head further includes a third nozzle row in which a plurality of nozzles are aligned in the first direction at the predetermined pitch, and a fourth nozzle row in which a plurality of nozzles are aligned in the first direction at the predetermined pitch, The control unit In the determination process, it is determined whether or not there is an abnormal nozzle row among the first to fourth nozzle rows, in response to determining in the determination process that there is no abnormal nozzle row, in the first ejection process, the carriage is moved once to form one line of the image with a group of dots made of liquid ejected from the first nozzle and a group of dots made of liquid ejected from the second nozzle, and the first to fourth nozzle rows and the carriage are controlled so as to form one adjacent line of the image with a group of dots made of liquid ejected from a third nozzle in the third nozzle row that corresponds to the first nozzle, and a group of dots made of liquid ejected from a fourth nozzle in the fourth nozzle row that corresponds to the first nozzle, 2. The liquid ejection device according to claim 1, wherein, in response to determining in the determination process that there are one or two abnormal nozzle rows, in the second ejection process, a first used nozzle row and a second used nozzle row are determined from the normal nozzle rows, and the carriage is moved once to form one line of the image with a group of dots made of liquid ejected from nozzles in the first used nozzle row, and to control the first to fourth nozzle rows and the carriage so that one adjacent line of the image is formed with a group of dots made of liquid ejected from corresponding nozzles in the second used nozzle row.

3. the second nozzle is located at a position shifted from the first nozzle in the first direction by ¼ of the predetermined pitch, the third nozzle is located at a position shifted from the first nozzle in the first direction by ½ of the predetermined pitch, the fourth nozzle is located at a position shifted from the first nozzle in the first direction by ¾ of the predetermined pitch, The liquid ejection device described in claim 2, wherein the control unit determines, in the second ejection process, the first nozzle row and the third nozzle row as the first used nozzle row and the second used nozzle row, or the second nozzle row and the fourth nozzle row, depending on whether the control unit determines in the judgment process that there are one or two abnormal nozzle rows.

4. The liquid ejection device described in claim 2 or 3, wherein the control unit, in response to determining in the judgment process that there are three abnormal nozzle rows, controls the first to fourth nozzle rows and the carriage in the second ejection process by moving the carriage back and forth so as to form one line of the image with a group of dots made of liquid ejected from nozzles in the normal nozzle rows.

5. The control unit In response to determining that there are one or more and three or less abnormal nozzle rows in the determination process, a first required time when the maintenance process and the first ejection process are performed is compared with a second required time when the second ejection process is performed without performing the maintenance process; In response to determining that the first required time is shorter than the second required time, the first ejection process is performed after the maintenance process is performed; 5. The liquid ejection device according to claim 2, wherein, in response to a determination that the second required time is shorter than the first required time, the second ejection process is executed before the maintenance process is executed.

6. a first nozzle row in which a plurality of nozzles are aligned in a first direction at a predetermined pitch; a second nozzle row in which a plurality of nozzles are aligned in the first direction at the predetermined pitch; a head including at least the first nozzle row and the second nozzle row; a carriage carrying the head and moving in a second direction intersecting the first direction; and a control unit, wherein the nozzles in the second nozzle row are positioned offset in the first direction from the nozzles in the first nozzle row, The control unit a determination process for determining whether or not there is an abnormal nozzle row including an abnormal nozzle among the first nozzle row and the second nozzle row; a first ejection process that controls the first nozzle row, the second nozzle row, and the carriage in response to determining in the determination process that there is no abnormal nozzle row, so that one line of an image to be formed is formed by a group of dots made of liquid ejected from first nozzles in the first nozzle row and a group of dots made of liquid ejected from second nozzles in the second nozzle row that correspond to the first nozzles; a second ejection process that controls the first nozzle row, the second nozzle row, and the carriage in response to determining that there is an abnormal nozzle row in the determination process, so that one line of the image is formed with a group of dots made of liquid ejected from nozzles in a normal nozzle row that does not include an abnormal nozzle; A program in which the distance in the second direction between dots formed by the liquid ejected from the first nozzle in the first ejection process is greater than the distance in the second direction between dots formed by the liquid ejected from the first nozzle in the second ejection process.

Images