Liquid ejection device, liquid ejection system, and program

Abstract

To provide means that can reduce data amounts of discharge control data, when positions of nozzles deviate for each nozzle row.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 obtains first data showing amounts of ink discharged from the nozzles in the first nozzle row K1 and second data showing amounts of ink discharged from the opposing nozzles in the second nozzle row K2, for each one line of image data, and memorizes the obtained discharge control data in a memory of a printer 10.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device and a liquid ejection system that eject liquid onto a sheet, and a program. [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] To perform a discharge process in a liquid discharger, discharge control data indicating the amount of liquid to be discharged from the nozzles is required. The discharge control data is generated by the liquid discharger, or generated by an external device (for example, a personal computer) and transmitted from the external device to the liquid discharger. In either case, it is preferable that the amount of discharge control data is small in order to reduce the memory size of the liquid discharger. Patent Document 1 does not describe the amount of data required for discharge control data.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide a means for reducing the amount of ejection control data when the nozzle positions are shifted for each nozzle row. [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 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, a control unit, and a memory. 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 the following operations: an acquisition process for acquiring, for each line of image data, ejection control data generated based on one line of image data of an image to be formed, the ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array corresponding to the first nozzle; a storage process for storing the ejection control data acquired in the acquisition process in the memory; and an ejection process for moving the carriage once to eject liquid from the first nozzle based on the first data included in the ejection control data stored in the memory, and to eject liquid from the second nozzle based on the second data included in the ejection control data stored in the memory. The memory stores the ejection control data in an amount not greater than that required for two of the ejection processes.

[0007] According to the liquid ejection device, when the nozzle positions are shifted for each nozzle row, the amount of ejection control data can be reduced.

[0008] (2) Preferably, in the acquisition process, the control unit receives the discharge control data generated by an external device and transmitted from the external device.

[0009] (3) Preferably, a nozzle in the second nozzle row is located between two adjacent nozzles in the first nozzle row in the first direction. In the acquisition process, the control unit receives the ejection control data generated by the external device by alternately allocating a plurality of data included in one line of the image data into the first data and the second data in the order of the data.

[0010] (4) Preferably, in the acquisition process, the control unit receives the image data transmitted from an external device and generates the ejection control data based on the received image data.

[0011] (5) Preferably, a nozzle in the second nozzle row is located between two adjacent nozzles in the first nozzle row in the first direction. In the acquisition process, the control unit generates the ejection control data by dividing a plurality of data included in one line of the image data into the first data and the second data alternately in data arrangement order.

[0012] (6) Preferably, the control unit starts the acquisition process after the discharge process ends, and ends the acquisition process before the next discharge process starts.

[0013] (7) Preferably, in the ejection process, the control unit ejects liquid from the nozzles of the head while the carriage is moving at a constant speed, determines whether the acquisition process will be completed by the start of the next ejection process, and, if it determines that the acquisition process will not be completed, stops the carriage until the acquisition process is completed.

[0014] (8) Preferably, in the ejection process, the control unit ejects liquid from the nozzles of the head while the carriage is moving at a constant speed, accelerating, or decelerating, and determines whether the acquisition process will be completed by the start of the next ejection process. If it determines that the acquisition process will not be completed, the control unit moves the carriage to a direction change position farther away from its original position.

[0015] (9) Preferably, the memory stores the amount of ejection control data required for one ejection process.

[0016] (10) Preferably, when the memory has free space capable of storing more ejection control data than is required for one ejection process, the control unit stores more ejection control data than is required for one ejection process in the free space of the memory.

[0017] (11) Preferably, in the ejection process, the control unit delays the timing at which the second nozzle starts ejecting the liquid compared to the timing at which the first nozzle starts ejecting the liquid.

[0018] (12) A liquid ejection device of the present invention includes: a first nozzle array in which a plurality of nozzles are arranged in a first direction at a predetermined pitch; a second nozzle array 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 array and the second nozzle array; a carriage carrying the head and moving in a second direction intersecting the first direction; a first control unit; a second control unit; and a memory. Nozzles in the second nozzle array are positioned offset in the first direction from nozzles in the first nozzle array. The first control unit executes a generation process to generate ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array that corresponds to the first nozzle, based on one line of image data of an image to be formed. The second control unit executes an acquisition process of acquiring the ejection control data generated in the generation process for each line of the image data, a storage process of storing the ejection control data acquired in the acquisition process in the memory, and an ejection process of moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and to eject liquid from the second nozzles based on the second data included in the ejection control data stored in the memory. The memory stores the ejection control data in an amount equal to or less than that required for two of the ejection processes.

[0019] (13) 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; a control unit; and a memory, 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 the following steps: an acquisition process to acquire, for each line of image data of an image to be formed, ejection control data, the ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array corresponding to the first nozzle; a storage process to store the ejection control data acquired in the acquisition process in the memory; and an ejection process to move the carriage once to eject liquid from the first nozzle based on the first data included in the ejection control data stored in the memory, and to eject liquid from the second nozzle based on the second data included in the ejection control data stored in the memory. The memory stores the ejection control data in an amount not greater than that required for two of the ejection processes.

[0020] (14) A program of the present invention is a program for a liquid ejection system including: a first nozzle array in which a plurality of nozzles are arranged in a first direction at a predetermined pitch; a second nozzle array in which a plurality of nozzles are arranged in the first direction at the predetermined pitch; a head including at least the first nozzle array and the second nozzle array; a carriage carrying the head and moving in a second direction intersecting the first direction; a first control unit; a second control unit; and a memory, wherein the nozzles in the second nozzle array are positioned offset in the first direction from the nozzles in the first nozzle array. The program causes the first control unit to execute a generation process to generate ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array that corresponds to the first nozzle, based on one line of image data of an image to be formed. The second control unit executes an acquisition process of acquiring the ejection control data generated in the generation process for each line of the image data, a storage process of storing the ejection control data acquired in the acquisition process in the memory, and an ejection process of moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and to eject liquid from the second nozzles based on the second data included in the ejection control data stored in the memory. The memory stores the ejection control data in an amount equal to or less than that required for two of the ejection processes. [Effects of the Invention]

[0021] According to the present invention, when the nozzle positions are shifted for each nozzle row, the amount of ejection control data can be reduced. [Brief explanation of the drawings]

[0022] [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. 6A is a diagram showing a first operating state of the printing system, and FIG. 6B is a diagram showing a second operating state of the printing system. [Figure 7] FIG. 7 is a diagram showing a method for generating discharge control data. [Figure 8] FIG. 8A is a diagram showing the ejection period and the acquisition period according to the first example, and FIG. 8B is a diagram showing the ejection period and the acquisition period according to the second example. [Figure 9] Figure 9(A) is a diagram showing an example in which the acquisition process is not completed before the start of the next ejection process, Figure 9(B) is a diagram showing how the carriage 31 moves to a direction change position, and Figure 9(C) is a diagram showing the ejection period and acquisition period for the third example. DETAILED DESCRIPTION OF THE INVENTION

[0023] 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.

[0024] [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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] [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.

[0031] 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.

[0032] An encoder 47 is connected to the ASIC 45. The encoder 47 alternately outputs a first level signal and a second level signal as the carriage 31 moves in the left-right direction 9. The control unit 40 receives the output signal of the encoder 47 via the ASIC 45. The control unit 40 acquires the position and movement speed of the carriage 31 based on the received output signal of the encoder 47.

[0033] 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.

[0034] 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.

[0035] [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.

[0036] The printing system shown in Fig. 3 is an example of a liquid ejection system. The control unit 110 is an example of a first control unit of the liquid ejection system. The control unit 40 is an example of a control unit of the liquid ejection device, and is also an example of a second control unit of the liquid ejection system. The RAM 102 and the storage unit 103 are examples of memory of the liquid ejection system.

[0037] 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.

[0038] [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.

[0039] 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.

[0040] 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 nozzles 33 in the second nozzle row K2 are positioned between two adjacent nozzles 33 in the first nozzle row in the sub-scanning direction. The nozzles 33 in the fourth nozzle row K4 are positioned between two adjacent nozzles 33 in the third nozzle row 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.

[0041] 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.

[0042] 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 nozzle rows, or an even number of nozzle rows of six or more.

[0043] 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).

[0044] [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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] [High-speed mode printing] 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 Fig. 5. As will be described below, in the high-speed mode printing process, the control unit 40 executes the following processes: acquires ejection control data for each line of image data; stores the acquired ejection control data in RAM 43; and moves the carriage 31 once to eject ink from the nozzles 33 of the head 32 based on the ejection control data. The ejection control data is data that indicates the amount of ink ejected from each nozzle 33.

[0050] At the beginning of the high-speed mode printing process (Figure 5), 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 compared 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 (S11).

[0051] Next, the control unit 40 feeds the sheet supported on the feed tray 14 (S12). In S12, 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.

[0052] Next, the control unit 40 acquires the ejection control data required for printing one pass (S13). The ejection control data is generated based on one line of image data for the image to be formed. The ejection control data includes data indicating the amount of ink ejected from the nozzles 33 of each nozzle row. Details of S13 will be described later.

[0053] Next, the control unit 40 stores the discharge control data acquired in S13 in the RAM 43. The RAM 43 has a storage area for storing the discharge control data acquired in S13. The size of the storage area is equal to or less than the amount of discharge control data used for two passes of printing (two discharge processes). The RAM 43 stores an amount of discharge control data equal to or less than the amount necessary for two passes of printing.

[0054] Next, the control unit 40 prints one pass on the sheet (S15). 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 S15, the control unit 40 moves the carriage 31 and ejects ink from all the nozzles 33 included in the head 32.

[0055] Next, the control unit 40 determines whether printing for one sheet has been completed (S16). If the control unit 40 determines in S16 that printing for one sheet has not been completed (S16: No), the control unit 40 proceeds to S17. In this case, the control unit 40 conveys the sheet by a predetermined amount (S17). In S17, 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 S13.

[0056] If the control unit 40 determines in S16 that printing for one sheet has been completed (S16: Yes), the control unit 40 proceeds to S18. In this case, the control unit 40 discharges the sheet (S18). In S18, the control unit 40 causes the conveyance rollers 22 and the discharge rollers 24 to convey the sheet by a predetermined amount and discharge the sheet onto the discharge tray 15.

[0057] Next, the control unit 40 determines whether all printing has been completed (S19). If the control unit 40 determines in S19 that all printing has not been completed (S19: No), it proceeds to S12. In this case, the control unit 40 executes S12 to S18 to print the next page. If the control unit 40 determines in S19 that all printing has been completed (S19: Yes), it ends the high-speed mode printing process.

[0058] 5, S13 is an example of an acquisition process, S14 is an example of a storage process, and S15 is an example of an ejection process.

[0059] [How to obtain discharge control data] The original image used for printing in the printer 10 is, for example, an RGB color image with a resolution of 600 dpi in the main scanning direction and 600 dpi in the sub-scanning direction. In order for the printer 10 to print a monochrome image in high-speed mode, the control unit 110 of the computer 100 performs color conversion processing, multi-value processing, and generation processing on the RGB color image (see FIG. 6(A)).

[0060] The color conversion process is a process of converting image data of an original image into image data of a YCMK image of the same resolution. The multi-value process is a process of performing area gradation conversion process, error diffusion process, etc. on image data of a K image (black image) included in the image data of the YCMK image to obtain image data (hereinafter referred to as multi-value image data) that has the same format as the image data of the K image and indicates the amount of ink ejected from each nozzle 33. The generation process is a process of generating ejection control data that indicates the amount of ink ejected from each nozzle 33 of the head 32 based on the multi-value image data.

[0061] The ejection control data generated by the control unit 110 is transmitted from the computer 100 to the printer 10. The control unit 40 of the printer 10 receives the ejection control data transmitted from the computer 100 in the acquisition process. The control unit 40 stores the received ejection control data in the RAM 43. Based on the ejection control data stored in the RAM 43, the control unit 40 causes the nozzles 33 of the head 32 to eject an amount of ink according to the ejection control data.

[0062] Depending on the type of computer 100, the printer 10 operates in the state shown in Fig. 6(B) instead of the state shown in Fig. 6(A). In this case, the computer 100 transmits image data of an RGB color image to the printer 10. The control unit 40 of the printer 10 performs color conversion processing and multi-value processing on the image data of the RGB color image transmitted from the printer 10 to generate multi-value image data. In the acquisition processing, the control unit 40 generates ejection control data based on the multi-value image data.

[0063] 6(A), the memory (RAM 102 and storage unit 103) of the computer 100 stores a program such as a printer driver that causes the control unit 110 to execute a series of processes including the generation process. The control unit 110 executes this program to execute the series of processes including the generation process. The control unit 40 of the printer 10 executes the program stored in the memory (RAM 43 and EEPROM 44) of the printer 10 to execute the acquisition process, storage process, and ejection process.

[0064] 6(B), the memory of the printer 10 stores a program that causes the control unit 110 to execute the acquisition process, storage process, and discharge process. The control unit 110 executes this program to execute the acquisition process, storage process, and discharge process.

[0065] An example of multi-value image data is shown in Fig. 7. Xij (j is a natural number) shown in Fig. 7 indicates the multi-value image data for the ith line and jth column. In the generation process shown in Fig. 6(A), the control unit 110 of the computer 100 distributes the odd-numbered column image data Xi1, Xi3, Xi5, ... of the ith line of multi-value image data Xi1, Xi2, Xi3, Xi4, ... into first data indicating the amount of ink ejected from the nozzles 33 in the odd-numbered nozzle arrays K1 and K3 of the first to fourth nozzle arrays K1 to K4, and distributes the even-numbered column image data Xi2, Xi4, Xi6, ... into second data indicating the amount of ink ejected from the nozzles 33 in the even-numbered nozzle arrays K2 and K4 of the first to fourth nozzle arrays K1 to K4, thereby generating the ith line of ejection control data including the first data and the second data. The control unit 40 of the printer 10 generates ejection control data based on the multi-value image data in the same manner in the acquisition process shown in Fig. 6(B). In this way, the ejection control data is generated by dividing the multiple data included in one line of the multi-value image data into first data and second data alternately in the order of the data arrangement.

[0066] The ejection control data may be generated by generating high-resolution multi-value image data with a resolution of 600 dpi in the main scanning direction and 1200 dpi in the sub-scanning direction based on the multi-value image data, and then thinning out the data from the high-resolution multi-value image data. However, according to the process shown in FIG. 7, the ejection control data can be generated based on multi-value image data with a lower resolution, thereby reducing the amount of memory required for processing. The nozzles 33 in the first nozzle row K1 are an example of first nozzles. The nozzles 33 in the second nozzle row K2 are an example of second nozzles. The ejection control data for the odd-numbered rows is an example of first data. The ejection control data for the even-numbered rows is an example of second data.

[0067] In S13, the control unit 40 acquires, for each line of image data, ejection control data generated based on one line of image data of the image to be formed, the ejection control data including first data indicating the amount of ink ejected from the nozzles 33 in the first nozzle row and second data indicating the amount of ink ejected from the nozzles 33 in the second nozzle row corresponding to the first nozzles. In S14, the control unit 40 stores the ejection control data acquired in S13 in the RAM 43.

[0068] In S15, the control unit 40 moves the carriage 31 once in the left-right direction 9, and ejects ink from the odd-numbered rows of nozzles 33 based on the first data included in the ejection control data stored in RAM 43, and ejects ink from the even-numbered rows of nozzles 33 based on the second data included in the ejection control data stored in RAM 43.

[0069] [Action and effect] As described above, the printer 10 according to this embodiment includes a first nozzle row K1 and a second nozzle row K2 in which a plurality of nozzles 33 are arranged in the sub-scanning direction at a pitch P, a head 32 including the first nozzle row K1 and the second nozzle row K2, a carriage 31 that carries the head 32 and moves in the main scanning direction, a control unit 40, and a RAM 43. The control unit 40 executes an acquisition process (S13), a storage process (S14), and an ejection process (S15). The RAM 43 stores an amount of ejection control data equal to or less than the amount required for two ejection processes.

[0070] According to the printer 10 of this embodiment, the amount of ejection control data can be reduced when the positions of the nozzles 33 are misaligned for each nozzle row. In the operating state shown in Fig. 6(A), an image can be generated based on the ejection control data generated by the computer 100 (an example of an external device). In the operating state shown in Fig. 6(B), an image can be generated based on the ejection control data generated by the printer 10.

[0071] [Timing control of acquisition and discharge processes] In order to write and read ejection control data to RAM 43 while minimizing memory usage, it is preferable that the period during which the control unit 40 acquires the ejection control data (hereinafter referred to as the acquisition period) does not overlap with the period during which the control unit 40 uses the ejection control data to eject ink from the nozzles 33 of the head 32 (hereinafter referred to as the ejection period).

[0072] 8 and 9, three examples will be described below in which the acquisition period and the ejection period do not overlap when the RAM 43 stores the amount of ejection control data required for printing one pass. Figures 8(A), 8(B), 9(A), and 9(C) show a waveform indicating the movement speed of the carriage 31 and a waveform indicating the period during which ink is ejected. The latter waveform is high during the ejection period and low outside the ejection period.

[0073] Hereinafter, the period from the end of the ejection period in a preceding pass to the start of ejection in a subsequent pass is referred to as the non-ejection period. The length of the non-ejection period varies depending on the image data. For example, if the carriage 31 is moved rightward in a preceding pass to print an image up to the right edge of the sheet, and then the carriage 31 is moved leftward in a subsequent pass to print an image starting from the right edge of the sheet, the non-ejection period is short. On the other hand, if the carriage 31 is moved rightward in a preceding pass to print an image up to the right edge of the sheet, and then the image is printed in a subsequent pass from a position away from the right edge of the sheet, the non-ejection period is long. To prevent the acquisition period and the ejection period from overlapping, for example, the acquisition period should start when the ejection period ends, and the non-ejection period should be longer than the acquisition period.

[0074] In the first example (FIG. 8(A)), the control unit 40 starts the acquisition process after the discharge process is completed, and ends the acquisition process before the next discharge process starts. In the operating state shown in FIG. 6(A), the control unit 40 of the printer 10 outputs an interrupt signal to the computer 100 when the discharge process is completed. The control unit 110 of the computer 100 starts the generation process using the interrupt signal output from the printer 10 as a trigger. After the control unit 110 completes the generation process and the control unit 40 completes the acquisition process, the control unit 40 starts the next discharge process. According to the first example, the discharge control data can be acquired in time for the start of the next discharge process.

[0075] In the second example (FIG. 8(B)), the control unit 40 causes ink to be ejected from the nozzles 33 of the head 32 during the ejection process while the carriage 31 is moving at a constant speed. The control unit 40 determines whether the acquisition process will be completed before the start of the next ejection process. If the control unit 40 determines that the acquisition process will not be completed, it stops the carriage 31 until the acquisition process is completed. When the carriage 31 is stopped, the non-ejection period becomes longer than the original period. Therefore, by stopping the carriage 31 for as long as necessary, the non-ejection period can be made longer than the acquisition period.

[0076] According to the second example, when ink is ejected while the carriage 31 is moving at a constant speed, the start of the next ejection process is delayed until the acquisition process is completed, and the ejection control data can be acquired in time for the start of the next ejection process.

[0077] FIG. 9A illustrates an example in which ink is ejected from the nozzles of the head while the carriage is moving at a constant speed, accelerating, or decelerating, and the acquisition process is not completed before the start of the next ejection process. In a third example (FIG. 9C), the control unit 40 ejects liquid from the nozzles 33 of the head 32 during the ejection process while the carriage 31 is moving at a constant speed, accelerating, or decelerating. The control unit 40 determines whether the acquisition process will be completed before the start of the next ejection process. If the control unit 40 determines that the acquisition process will not be completed, it moves the direction change position of the carriage 31 away from its original position (see FIG. 9B). When the direction change position of the carriage 31 is moved away from its original position, the timing at which the carriage 31 starts to decelerate is delayed in the preceding pass compared to when the direction change position of the carriage 31 is located at its original position, and the movement speed of the carriage 31 at the ejection end position is faster, so the ejection period ends earlier. Furthermore, in subsequent passes, the distance from the direction change position of the carriage 31 to the position where the nozzles 33 start to eject ink is longer, so the ejection period starts later. As a result, the non-ejection period is longer than the original period. Therefore, by moving the direction change position of the carriage 31 farther away as necessary, the non-ejection period can be made longer than the acquisition period.

[0078] According to the third example, when liquid is ejected while the carriage 31 is moving at a constant speed, accelerating, or decelerating, the direction change position of the carriage 31 can be set farther away from the original position, and the ejection control data can be acquired in time for the start of the next ejection process.

[0079] In addition, if RAM 43 has free space that can store more ejection control data than is required for one ejection process, control unit 40 can simply store more ejection control data than is required for one ejection process in the free space of RAM 43.

[0080] [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.

[0081] The present invention is applicable to a liquid ejection device in which the head 32 includes an even number of nozzle rows. In a liquid ejection device including N (N is an even number) nozzle rows, the pitch in the sub-scanning direction of the nozzles 33 in each nozzle row (hereinafter referred to as the nozzle pitch) may be the same, and the nozzles in the first to Nth nozzle rows 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 rows, the nozzles in the second nozzle row may be shifted in the sub-scanning direction from the nozzles in the first nozzle row by 1 / 2 of the nozzle pitch. In a liquid ejection device including six nozzle rows, the nozzles in the second nozzle row may be offset in the sub-scanning direction from the nozzles in the first nozzle row by 1 / 6 of the nozzle pitch, the nozzles in the third nozzle row may be offset in the sub-scanning direction from the nozzles in the second nozzle row by 1 / 6 of the nozzle pitch, the nozzles in the fourth nozzle row may be offset in the sub-scanning direction from the nozzles in the third nozzle row by 1 / 6 of the nozzle pitch, the nozzles in the fifth nozzle row may be offset in the sub-scanning direction from the nozzles in the fourth nozzle row by 1 / 6 of the nozzle pitch, and the nozzles in the sixth nozzle row may be offset in the sub-scanning direction from the nozzles in the fifth nozzle row by 1 / 6 of the nozzle pitch.

[0082] In the above embodiment, the nozzle pitch is 1 / 300 inch, and 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, but the nozzle pitch in the liquid ejection device and the resolution of the image formed are not limited to the above values. The present invention can also be applied to liquid ejection devices with other nozzle pitches and liquid ejection devices that form images with other resolutions. [Explanation of symbols]

[0083] 10. Printer (liquid ejection device) 31. Carriage 32...head 33 Nozzle 40... Control unit (second control unit) 100 Computer (external device) 110 Control unit (first 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; a memory; 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 an acquisition process for acquiring, for each line of image data, ejection control data generated based on one line of image data of an image to be formed, the ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array corresponding to the first nozzle; a storage process of storing the discharge control data acquired in the acquisition process in the memory; moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and ejecting liquid from the second nozzles based on the second data included in the ejection control data stored in the memory; The memory stores the ejection control data in an amount not greater than that required for two ejection processes in the process executed by the control unit.

2. The liquid ejection device according to claim 1 , wherein the control unit receives the ejection control data generated by an external device and transmitted from the external device in the acquisition process.

3. a nozzle in the second nozzle row is located between two adjacent nozzles in the first nozzle row in the first direction; The liquid ejection device described in claim 2, wherein the control unit receives the ejection control data generated in the external device by alternately distributing multiple data contained in one line of the image data into the first data and the second data in the order of the data arrangement during the acquisition process.

4. 2. The liquid ejection device according to claim 1, wherein the control unit receives the image data transmitted from an external device in the acquisition process, and generates the ejection control data based on the received image data.

5. a nozzle in the second nozzle row is located between two adjacent nozzles in the first nozzle row in the first direction; The liquid ejection device described in claim 4, wherein the control unit generates the ejection control data by distributing multiple data included in one line of the image data alternately into the first data and the second data in the order of the data arrangement in the acquisition process.

6. 6. The liquid ejection device according to claim 1, wherein the control unit starts the acquisition process after the ejection process ends, and ends the acquisition process before the next ejection process starts.

7. The control unit In the ejection process, liquid is ejected from the nozzles of the head while the carriage is moving at a constant speed; determining whether the acquisition process will be completed by the start of the next discharge process; 6. The liquid ejection device according to claim 1, wherein, in response to determining that the acquisition process has not been completed, the carriage is stopped until the acquisition process is completed.

8. the control unit causes the liquid to be ejected from the nozzles of the head during constant speed movement, acceleration movement, and deceleration movement of the carriage in the ejection process; determining whether the acquisition process will be completed by the start of the next discharge process; 6. The liquid ejection device according to claim 1, wherein the direction change position of the carriage is moved away from the original position in response to a determination that the acquisition process has not been completed.

9. 9. The liquid ejection apparatus according to claim 1, wherein the memory stores an amount of the ejection control data required for one ejection process.

10. A liquid ejection device as described in any one of claims 1 to 8, wherein when the memory has free space capable of storing more ejection control data than is required for one of the ejection processes, the control unit stores more ejection control data than is required for one of the ejection processes in the free space of the memory.

11. 11. The liquid ejection device according to claim 1, wherein the control unit delays the timing at which the second nozzle starts ejecting the liquid compared to the timing at which the first nozzle starts ejecting the liquid in the ejection process.

12. 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 first control unit; A second control unit; a memory; 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 first control unit executes a generation process to generate, based on one line of image data of an image to be formed, ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle row and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle row corresponding to the first nozzle; The second control unit is an acquisition process of acquiring the discharge control data generated in the generation process for each line of the image data; a storage process for storing the discharge control data acquired in the acquisition process in the memory; moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and ejecting liquid from the second nozzles based on the second data included in the ejection control data stored in the memory; The memory stores the discharge control data in an amount not greater than that required for two discharge processes in the process executed by the second control unit.

13. 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; a control unit; and a memory, 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 an acquisition process for acquiring, for each line of image data, ejection control data generated based on one line of image data of an image to be formed, the ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array corresponding to the first nozzle; a storage process of storing the discharge control data acquired in the acquisition process in the memory; moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and ejecting liquid from the second nozzles based on the second data included in the ejection control data stored in the memory; The memory is a program for storing the ejection control data in an amount not greater than that required for two ejection processes in the process executed by the control unit.

14. 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; a first control unit; a second control unit; and a memory, wherein the nozzles in the second nozzle row are positioned offset in the first direction from the nozzles in the first nozzle row, causing the first control unit to execute a generation process to generate, based on one line of image data of an image to be formed, ejection control data including first data indicating an amount of liquid to be ejected from a first nozzle in the first nozzle array and second data indicating an amount of liquid to be ejected from a second nozzle in the second nozzle array corresponding to the first nozzle; The second control unit is an acquisition process of acquiring the discharge control data generated in the generation process for each line of the image data; a storage process for storing the discharge control data acquired in the acquisition process in the memory; moving the carriage once to eject liquid from the first nozzles based on the first data included in the ejection control data stored in the memory, and ejecting liquid from the second nozzles based on the second data included in the ejection control data stored in the memory; The memory is a program for storing the ejection control data in an amount not greater than that required for two ejection processes in the process executed by the second control unit.

Images