JP2023145153A - Liquid discharge device and program - Google Patents

Abstract

To provide means which reduces a difference in sizes of margins on ends along the conveyance direction of a sheet between the downstream side and the upstream side in the conveyance direction of the sheet.SOLUTION: A control unit 40 of a printer 10 acquires a continuous portion in which images continue between passes from the images recorded on a sheet. The control unit 40 causes a nozzle 33 of a head 32 to discharge ink at reference timing for a central portion in the conveyance direction of the continuous portion, causes the nozzle 33 to discharge ink at timing different from the reference timing such that a recording position on the sheet deviates in a direction along the left-right direction 9 for an upper portion relative to the central portion in the continuous portion, and causes the nozzle 33 to discharge ink at timing different from the reference timing such that the recording position on the sheet deviates in the reverse direction along the left-right direction 9 for a lower portion relative to the central portion in the continuous portion.SELECTED DRAWING: Figure 4

Description

The present invention relates to a liquid ejection device that ejects liquid onto a sheet, and a program.

Patent Document 1 discloses that when the nozzle arrangement direction or the recording paper conveyance direction is tilted with respect to the sub-scanning direction, ink is ejected at a reference timing to the center of the image recording area of the recording paper, and the center An inkjet printer has been disclosed in which the ejection timing is earlier or later than the reference timing to shift the landing position of the ink in the main scanning direction for the upstream and downstream parts of the transport direction.

According to this inkjet printer, the landing position of the ink is made to match between the upstream end in the transport direction of the part where the image is recorded in the preceding pass and the downstream end in the transport direction of the part where the image is recorded in the subsequent pass. When the arrangement direction of the nozzles or the conveyance direction of the recording paper is inclined with respect to the sub-scanning direction, the quality of the recorded image can be improved.

Japanese Patent Application Publication No. 2013-111939

In the conventional inkjet printer described above, the portion where an image is recorded in each pass is sequentially shifted in a specific direction along the main scanning direction. Therefore, there is a difference in position in the main scanning direction between the part where the image is recorded near the downstream end of the recording paper in the transport direction and the part where the image is recorded near the upstream end of the recording paper in the transport direction. growing. Therefore, while the left margin (the area where no image is recorded) is large near the downstream end of the recording paper in the transport direction, the right margin is large near the upstream end of the recording paper in the transport direction, or vice versa. It can happen.

The present invention has been made in view of the above circumstances, and its purpose is to improve the image quality of images recorded on sheets when the nozzle arrangement direction or sheet conveyance direction is not perpendicular to the carriage movement direction. It is an object of the present invention to provide a technique for reducing the difference in size of margins at the edges of a sheet along the conveyance direction between the downstream side and the upstream side of the sheet conveyance direction while improving the paper conveyance direction.

(1) The liquid ejection device of the present invention includes a head having a plurality of nozzles arranged in a first direction, a carriage on which the head is mounted and moves in a second direction intersecting the first direction, and a second The apparatus includes a conveyance section that conveys the sheet in a conveyance direction that intersects with the conveyance direction, and a control section. The head records one pass of an image on the sheet while the carriage moves once in the second direction. The control unit performs an acquisition process of acquiring a continuous portion of the image that is continuous between passes from the image recorded on the sheet, and controls the nozzle at a reference timing for a central portion of the continuous portion in the conveying direction. The reference timing is such that the recording position on the sheet is shifted in the first direction along the second direction for a portion downstream of the central portion of the continuous portion in the conveying direction. ejecting liquid from the nozzles at different timings so that the recording position on the sheet is shifted in a second direction along the second direction for a portion upstream in the conveying direction from the central portion of the continuous portion; A discharge control process for discharging liquid from the nozzle at a timing different from the reference timing is executed.

According to the above-mentioned liquid ejecting device, the first direction or the transport direction is perpendicular to the second direction by acquiring continuous parts of the image and controlling the timing of ejecting the liquid from the nozzle for each continuous part of the image. If there is no margin, it is possible to reduce the difference in the size of the margins at the edges of the sheet along the conveyance direction between the downstream side and the upstream side of the sheet, while improving the image quality of the image recorded on the sheet.

(2) Preferably, the control unit further executes a reception process of receiving the image data of the image for each pass, and the control unit, before executing the acquisition process using the image data of a certain pass, In the above reception process, image data of a plurality of passes subsequent to the current pass may be received.

(3) Preferably, the control unit executes the ejection control process in response to the size of the sheet in the transport direction being equal to or greater than a predetermined value, and executes the ejection control process in response to the size of the sheet being less than the predetermined value. Then, a second ejection control process may be executed to eject the liquid from the nozzle at the reference timing for the entire sheet.

(4) Preferably, in the ejection control process, the control unit may control the timing at which the liquid is ejected from the nozzle, depending on the position of the nozzle in the head in the first direction.

(5) Preferably, in the acquisition process, the control unit includes first image data when recording an image at an upstream end portion in a preceding pass, and a subsequent pass following the preceding pass, out of the image data of the image. If both the second image data and the second image data when recording the image at the downstream end portion do not include valid data, it is determined that the images are not continuous between the preceding pass and the succeeding pass, The continuous portion may be acquired from the image using a position where it is determined that the image is not continuous as a boundary.

(6) The program of the present invention includes: a head having a plurality of nozzles arranged in a first direction; a carriage carrying the head and moving in a second direction intersecting the first direction; The head includes a conveyance unit that conveys the sheet in intersecting conveyance directions, and a control unit, and the head conveys one pass to the sheet while the carriage moves once in the second direction. This is a program for a liquid ejection device that performs image recording. The above program causes the control unit to perform an acquisition process to obtain a continuous part of the image recorded on the sheet between passes, and to set a standard for the central part of the continuous part in the transport direction. The liquid is ejected from the nozzle at a timing such that the recording position on the sheet is shifted in the first direction along the second direction in a downstream part in the conveying direction from the central part of the continuous part. The liquid is ejected from the nozzle at a timing different from the reference timing, and the recording position on the sheet is oriented in a second direction along the second direction for a portion upstream in the conveying direction from the central portion of the continuous portion. executing a discharge control process for discharging liquid from the nozzle at a timing different from the reference timing so as to deviate from the reference timing;

According to the present invention, when the first direction or the conveyance direction is not orthogonal to the second direction, while improving the image quality of the image recorded on the sheet, on the downstream side and upstream side of the sheet conveyance direction, Differences in the size of margins at the edges of the sheet along the conveyance direction can be reduced.

FIG. 1 is an external perspective view of a printer 10 according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view schematically showing the internal structure of the printer 10. As shown in FIG. FIG. 3 is a block diagram of a printing system including printer 10 and computer 100. FIG. 4 is a flowchart of print processing by the printer 10. FIG. 5 is a diagram showing a lower end portion 51 of a range Pi where an image is recorded in the preceding pass, and an upper end portion 52 of a range Pi+1 where an image is recorded in the subsequent pass. FIG. 6 is a diagram showing an ideal state of the image printed on the sheet S. FIG. 7 is a diagram showing the margins of a sheet S on which an image has been recorded using a conventional printer. FIG. 8 is a diagram showing the margins of a sheet S on which an image is recorded by the printer 10. As shown in FIG.

Embodiments of the present invention will be described below. Note that the embodiments described below are merely examples of the present invention, and it goes without saying that the embodiments of the present invention can be modified as appropriate without changing the gist of the present invention. In the following explanation, the progress from the starting point of the arrow to the ending point is expressed as the direction, and the movement on the line connecting the starting point and the ending point of the arrow is expressed as the direction. Further, a vertical direction 7 is defined based on the state in which the printer 10 is installed so that it can be used (the state shown in FIG. 1), a front-back direction 8 is defined with the surface where the opening 13 of the printer 10 is formed as the front, and the printer 10 A left-right direction 9 is defined when viewed from the front. The up-down direction 7, the front-back direction 8, and the left-right direction 9 are orthogonal to each other.

[Overview of printer 10]
The printer 10 according to the present 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 liquid) onto a sheet. The printer 10 may be a so-called "multifunction device" having functions such as a facsimile function, a scan function, and a copy function.

The printer 10 has a housing 11 having a generally rectangular parallelepiped shape. As shown in FIGS. 1 and 2, inside the housing 11, there are a feeding tray 14, a feeding roller 21, a conveying roller 22, a carriage 31, and a plurality of nozzles 33 mounted on the carriage 31. a head 32 having a head 32, a platen 23 facing the head 32, an ejection roller 24, an ejection tray 15, a sub-tank 35, a mounting case 36 into which a cartridge 37 can be mounted, and a cartridge 37 mounted in the mounting case 36. A tube 34 communicating with the head 32 is located therein. In the head 32, the plurality of nozzles 33 are lined up in the front-back direction 8.

The printer 10 drives the feed roller 21 and the conveyance roller 22 to convey the sheet supported on the feed tray 14 to the position of the platen 23 along a conveyance path (path indicated by a dashed line in FIG. 2). . Next, the printer 10 causes the nozzle 33 of the head 32 to eject ink supplied from the cartridge 37 mounted in the mounting case 36 via the sub tank 35 and the tube 34 . As a result, the ink lands on the sheet supported by the platen 23, and the image to be recorded is printed on the sheet. The printer 10 drives the ejection roller 24 to eject the sheet with the image printed onto the ejection tray 15.

The carriage 31 is supported by two guide rails (not shown) extending in the left-right direction 9 and reciprocates in the left-right direction 9 intersecting the front-back direction 8 . The printer 10 causes ink to be ejected from the nozzles 33 of the head 32 while the carriage 31 moves in the left-right direction 9 . As a result, an image is recorded on a partial area of the sheet facing the head 32. The head 32 records one pass of an image on the sheet while the carriage 31 moves once in the left-right direction 9 (leftward or rightward). Next, the printer 10 causes the conveyance roller 22 to convey the sheet so that the area where an image is to be recorded next faces the head 32. An image is recorded on the sheet by alternately and repeatedly performing these processes.

As shown in FIG. 1, the housing 11 includes a cover 18 on the front surface 12 of the housing 11 and at the right end in the left-right direction 9. As shown in FIG. An opening (not shown) is formed at the position of the cover 18 . The cover 18 is rotatable between a position where the opening is closed (the position shown in FIG. 1) and a position where the opening is opened. One mounting case 36 is located in the housing space inside the housing 11 that extends deep into the opening. A cartridge 37 storing black ink is attached to the attachment case 36 .

The cartridge 37 has a liquid chamber 38 (see FIG. 2) that can store ink. When the cartridge 37 is attached to the attachment case 36, the ink stored in the liquid chamber 38 flows into the sub-tank 35 via an ink flow path 39 that communicates the liquid chamber 38 and the sub-tank 35. The sub-tank 35 temporarily stores the ink that has flowed into it. Ink stored in the sub tank 35 is supplied to the head 32 via the tube 34.

[Control unit 40]
A control unit 40 shown in FIG. 3 is located inside the casing 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, etc. used when the CPU 41 executes a program, or as a work area for data processing. The EEPROM 44 stores information that should be retained even after the power is turned off.

The ASIC 45 is for operating the feeding roller 21, the conveyance roller 22, the ejection roller 24, and the head 32. The control unit 40 rotates the feeding roller 21 , the conveying roller 22 , and the ejecting roller 24 by driving a motor (not shown) through the ASIC 45 . The control unit 40 causes ink to be ejected from the nozzles 33 of the head 32 by outputting a drive signal to a drive element (not shown) of the head 32 through the ASIC 45 . The ASIC 45 outputs a drive signal according to the amount of ink to be ejected from the nozzle 33.

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 according to a user's operation to the control unit 40. The operation panel 17 may include, for example, push buttons or a touch sensor superimposed on the display 16.

A communication interface 46 is connected to the ASIC 45 . The communication interface 46 is an interface for communicating 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 communicates with other devices connected to the printer 10 by controlling the communication interface 46 .

The feeding roller 21, the conveyance roller 22, and the discharge roller 24 shown in FIG. 2 function as a conveyance unit that conveys the sheet in a conveyance direction that intersects with the left-right direction 9. The printer 10 includes a head 32 having a plurality of nozzles 33, a carriage 31 that moves in a left-right direction 9 that intersects the front-rear direction 8, a conveyance section that conveys sheets in a conveyance direction that intersects the left-right direction 9, and a control section 40. It is equipped with. The direction in which the plurality of nozzles 33 are arranged is an example of a first direction. The left-right direction 9 is an example of a second direction. The direction in which the plurality of nozzles 33 are arranged and the direction in which the sheet is conveyed should originally be parallel to the front-rear direction 8. However, the arrangement direction of the plurality of nozzles 33 and the conveyance direction of the sheet may actually be inclined with respect to the front-rear direction 8.

[Computer 100]
In the printing system shown in FIG. 3, a computer 100 is connected to a printer 10. Computer 100 is any type of computer that can be connected to printer 10. The computer 100 is, for example, a personal computer or a mobile phone. The computer 100 includes a CPU 101, a RAM 102, a storage section 103, an input section 104, a display section 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 is, for example, a hard disk or an SSD drive. The storage unit 103 stores programs and the like 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, etc. used when the CPU 101 executes a program, or as a work area for data processing. The communication interface 106 is an interface for communicating with the printer 10.

The control unit 40 of the printer 10 executes various processes by having the CPU 41 execute programs stored in the RAM 43. The control unit 110 of the computer 100 executes various processes by causing the CPU 101 to execute programs stored in the RAM 102. These programs may be stored in a computer readable storage medium. A computer readable storage medium is a non-transitory medium. Non-transitory media include ROM, RAM, EEPROM, hard disk, SSD drive, and other recording media such as CD-ROM and DVD-ROM. Furthermore, non-transitory media are also tangible media. On the other hand, electrical signals that carry programs downloaded from servers on the Internet are a type of computer-readable signal medium, but non-transitory computer-readable storage Not included in media.

[Print processing by printer 10]
The control unit 40 performs the printing process shown in FIG. 4 in response to receiving image data of an image to be recorded on a sheet. Hereinafter, it is assumed that each pass of the print process is numbered sequentially starting from 1 in the order of execution. The image recorded on the sheet is divided into multiple parts corresponding to multiple passes.

The control unit 40 performs acquisition processing and ejection control processing in the printing processing shown in FIG. 4 . The acquisition process is a process of acquiring a continuous part of the image recorded on the sheet, where the image is continuous between passes. The ejection control process is a process for ejecting ink from the nozzle 33 for the acquired continuous portion. In the ejection control process, the control unit 40 controls the ink ejection timing to be earlier or later than the reference timing.

The control unit 40 uses two variables N and A in the printing process. The variable N is a number assigned in the above execution order and indicates the number of the path to be processed. Variable A indicates the number of paths corresponding to the continuous portion.

In the printing process, the control unit 40 first sets the value of the variable N to 1 (S11). Next, the control unit 40 sets the value of variable A to 1 (S12). Next, the control unit 40 determines whether or not the images are continuous between the Nth pass and the (N+1)th pass (S13, details will be described later). In response to determining that the images are continuous (S13: Yes), the control unit 40 proceeds to S14. In this case, the control unit 40 adds 1 to the value of variable N and the value of variable A (S14), and proceeds to S13.

In response to determining that the images are not continuous in S13 (S13: No), the control unit 40 proceeds to S15. Here, if the variable N is a value indicating the number of the final pass of the image recorded on one page of sheets, the determination is No in S13. When the control unit 40 reaches S15, of the image recorded on the sheet, the portion printed in the (NA+1)th to Nth passes has been acquired as a continuous portion. In S12 to S14, the control unit 40 acquires a continuous portion from the image recorded on the sheet.

In S15, the control unit 40 determines whether the value of variable A is 1 (S15). In response to determining that the value of variable A is 1 (S15: Yes), the control unit 40 proceeds to S16. In this case, the continuous portion includes only the portion printed in the Nth pass of the image recorded on the sheet. In S16, the control unit 40 performs printing for the Nth pass by ejecting ink from the nozzle 33 according to the reference timing.

In response to determining in S15 that the value of variable A is not 1 (S15: No), the control unit 40 proceeds to S17. In this case, the continuous portion includes a portion of the image recorded on the sheet that is printed in the (NA+1)th to Nth passes. In S17, the control unit 40 performs printing from the (NA+1)th to the Nth pass by ejecting ink from the nozzle 33 while controlling the ink ejection timing. Details of S17 will be described later.

After executing S16 or S17, the control unit 40 proceeds to S18. The control unit 40 adds 1 to the value of the variable N in S18. Next, the control unit 40 determines whether all paths have been processed (S19). In response to determining that not all paths have been processed (S19: No), the control unit 40 proceeds to S12. In this case, the control unit 40 again executes the processing from S12 onwards.

In response to determining that all passes have been processed in S19 (S19: Yes), the control unit 40 ends the printing process. Note that, among the printing processes shown in FIG. 4, S12 to S14 are an example of an acquisition process, and S15 to S17 are an example of an ejection control process.

[Details of S13]
Hereinafter, details of S13 will be explained with reference to FIG. 5. In FIG. 5, Pi indicates the range in which an image is recorded in the i-th pass on the sheet S. Pi+1 indicates a range on the sheet S in which an image is recorded in the (i+1)th pass. The two ranges Pi and Pi+1 are vertically adjacent to each other with the boundary 50 in between. The lower end portion 51 is a portion of the range Pi that is within a predetermined distance (hereinafter referred to as d) from the boundary 50. The upper end portion 52 is a portion of the range Pi+1 that is within a distance d from the boundary 50. The distance d is, for example, about several mm.

The control unit 40 determines whether the images are continuous based on whether the image data includes valid data. For example, the control unit 40 sets white data as invalid data and sets other data as valid data. Alternatively, the control unit 40 may set the sheet color data or data of a color that is difficult to recognize on the sheet as invalid data, and set other data as valid data.

In S13, if the first image data used to record an image in the lower end portion 51 and the second image data used to record an image in the upper end portion 52 do not include valid data, If it is determined that the images are not continuous between the i-th pass and the (i+1)-th pass, and at least one of the first image data and the second image data contains valid data, the i-th pass It is determined that the images are continuous between the path and the (i+1)th pass. Then, the control unit 40 acquires a continuous portion from the image recorded on the sheet, using the position where it is determined that the image is not continuous as a boundary. Note that the i-th path is an example of a preceding path, and the (i+1)-th path is an example of a subsequent path. The lower end portion 51 is an example of an upstream end portion, and the upper end portion 52 is an example of a downstream end portion.

[Details of S17]
Details of S17 will be explained below. In S17, the control unit 40 classifies the continuous portion acquired in S12 to S14 into a central portion, an upper portion, and a lower portion. The continuous portion corresponds to A paths from (NA+1)th to Nth. When the number A of passes is an odd number, the control unit 40 sets M=N-(A-1)/2, sets the part printed in the Mth pass to the central part, and prints the part printed in the Mth pass from the (NA+1)th to (M The portion printed in the -1)th pass is classified as an upper portion, and the portion printed in the (M+1)th to Nth passes are classified as a lower portion.

When the number A of passes is an even number, the control unit 40 sets M1=NA/2, M2=NA/2+1, and prints the part printed in the M1th pass and the M2th pass as the central part, The portion printed in the (NA+1)th to (M1-1)th passes is classified as the upper portion, and the portion printed in the (M2+1)th to Nth passes is classified as the lower portion.

Note that when the number A of passes is an even number, the control unit 40 sets one of the above M1 and M2 to M, and sets the part printed in the Mth pass to the center part, and prints the parts printed in the (NA+1)th to (N-A+1)th to ( The portion printed in the M-1)th pass may be classified as the upper portion, and the portion printed in the (M+1)th to Nth passes may be classified as the lower portion.

In the printer 10, in order to match the recording position of the image between the lower end of the part where the image is recorded in the preceding pass and the upper end of the part where the image is recorded in the subsequent pass, The amount by which the image recording position is shifted in the left-right direction 9 (hereinafter referred to as shift amount X) is determined. In the case where the image recording position is shifted leftward in the subsequent pass compared to the preceding pass, the shift amount X is, for example, a negative value. In the case where the image recording position is shifted to the right in the subsequent pass compared to the preceding pass, the shift amount X is, for example, a positive value. The shift amount X is determined in advance, for example, based on the results of printing a test image with the printer 10.

Specifically, the EEPROM 44 stores the arrangement direction of the plurality of nozzles 33 and the inclination of the sheet conveyance direction by the conveyance roller 22 with respect to the front-rear direction 8. As described above, the arrangement direction of the plurality of nozzles 33 and the conveyance direction of the sheet should originally be parallel to the front-rear direction 8. However, in reality, the arrangement direction of the plurality of nozzles 33 and the conveyance direction of the sheet are different from the front-rear direction 8 due to tolerances of the parts constituting the printer 10 and errors in the installation of parts during the manufacture of the printer 10. Sometimes it's tilted. The EEPROM 44 stores the arrangement direction of the plurality of nozzles 33 and the angle of the sheet conveyance direction with respect to the front-rear direction 8, respectively. Note that the arrangement direction of the plurality of nozzles 33 and the angle of the sheet conveyance direction with respect to the front-rear direction 8 are obtained, for example, by recording a test image including a line segment extending in the vertical direction on the sheet when manufacturing the printer 10. be able to.

The control unit 40 acquires the position of the seat. Specifically, the control unit 40 acquires which portion of the sheet faces the head 32 based on the distance that the sheet is conveyed by the conveyance roller 22 and the like. The control unit 40 determines the shift amount X based on the arrangement direction of the plurality of nozzles 33, the inclination in the sheet conveyance direction, and the obtained sheet position stored in the EEPROM 44.

The control unit 40 causes ink to be ejected from the nozzles 33 of the head 32 at the reference timing for the central portion of the continuous portion. The reference timing is the timing when the arrangement direction of the nozzles 33 and the sheet conveyance direction are perpendicular to the moving direction of the carriage 31. For the upper part of the continuous part, the control unit 40 sets the standard according to the distance from the center part so that the recording position on the sheet is shifted in a certain direction (one of leftward and rightward) along the left-right direction 9. Ink is ejected from the nozzle 33 at a different timing. The control unit 40 controls the lower part of the continuous part according to the distance from the center part so that the recording position on the sheet is shifted in the opposite direction (the other of leftward and rightward) along the left-right direction 9. , ink is ejected from the nozzle 33 at a timing different from the reference timing. Note that one of the leftward and rightward directions is an example of the first direction along the second direction, and the other of the leftward and rightward directions is an example of the second direction along the second direction.

Assume that when the ink ejection timing is advanced or delayed by a time T, the recording position on the sheet is shifted leftward or rightward by an amount X. If a part included in the upper part or lower part of the continuous part and which is printed in a certain pass is separated from the central part of the continuous part by I pass, the control unit 40 controls the recording position of that part on the sheet. In order to shift the distance (I×X) from the recording position in the central portion, the ink ejection timing is advanced or delayed by the time (I×T) from the reference timing.

More specifically, when the shift amount During this period, the ink ejection timing is delayed by the time (I×T), and the carriage 31 moves leftward to print the upper part, and the carriage 31 moves rightward to print the lower part. advances the ink ejection timing by time (I×T).

When the shift amount The ink ejection timing is advanced by time (I x T), and the ink is ejected while the carriage 31 moves leftward to print the upper part and while the carriage 31 moves rightward to print the lower part. The timing is delayed by time (I×T).

[Example of print result]
Examples of printing results by the printer 10 will be described with reference to FIGS. 6 to 8. FIG. 6 shows images printed at the standard timing over all passes from the 1st to the 14th in an ideal state in which the arrangement direction of the nozzles 33 and the conveyance direction of the sheet S are both parallel to the front-rear direction 8. An example of the print result is shown below. In the example shown in FIG. 6, the image printed on sheet S has three consecutive parts R1, R2, R3. The continuous portion R1 includes portions printed in the first to fifth passes. The continuous portion R2 includes the portion printed in the 6th to 10th passes. The continuous portion R3 includes the portion printed in the 11th to 14th passes. FIG. 6 shows an ideal state in which the nozzle arrangement direction and the sheet conveyance direction are perpendicular to the carriage movement direction. A case in which the nozzle arrangement direction or sheet conveyance direction is not orthogonal to the carriage movement direction will be described below.

In the conventional inkjet printer described above, the above image is printed on a sheet S as shown in FIG. In this printer, among the 1st to 14th passes, the 7th pass prints the center part of the entire image recorded on sheet S, the image is printed at the standard timing, and the 1st pass prints the upper part of the entire image. The 6th to 6th passes each print the image at a position offset to the right with respect to the subsequent pass, and the 7th to 14th passes, which print the lower part of the entire image, respectively, with respect to the preceding pass. The image is recorded at a position shifted to the left. In addition, in the entire image recorded on the sheet S, the recording position of the image matches between the lower end of the part where the image is recorded in the preceding pass and the upper end of the part where the image is recorded in the subsequent pass. Therefore, in FIG. 7, the upper side of the image recorded on the sheet S is shifted to the right from the original position, and the lower side is shifted to the left from the original position.

In FIG. 7, the sizes of the left margin SL11 near the top edge of the sheet S and the right margin SR12 near the bottom edge of the sheet are the same as the size of the right margin SR11 near the top edge of the sheet S and the left margin SL12 near the bottom edge of the sheet. larger than the size of. In this way, near the top end of the sheet S, the left margin SL11 is large, but near the bottom end of the sheet S, the right margin SR12 is large.

In the printer 10 according to this embodiment, the above image is printed on the sheet S as shown in FIG. In the printer 10, among the 1st to 14th passes, the images are printed at the reference timing in the 3rd, 8th, 12th, and 13th passes, which print the center portions of the continuous portions R1, R2, and R3 of the image, respectively. In the 1st, 2nd, 6th, 7th, and 11th passes that print the upper parts of the continuous parts R1, R2, and R3, the images are printed at positions shifted to the right from the center of the continuous parts R1, R2, and R3. The image is printed and the 4th, 5th, 8th, 10th and 14th passes print the lower part of each of the image contiguous parts R1, R2, R3 for the middle part of the image contiguous parts R1, R2, R3. The image is recorded at a position shifted to the left. In addition, for each continuous portion R1, R2, and R3 of the image recorded on the sheet S, the image is The recording positions match. For this reason, there is a size difference between the left margin SL1 near the top edge of the sheet S and the left margin SL2 near the bottom edge of the sheet S, and the difference in size between the right margin SR1 near the top edge of the sheet S and the right margin SL1 near the bottom edge of the sheet S. The difference in size from the margin SR2 is smaller than that of the conventional printer. As described above, in the printer 10 according to the present embodiment, the difference in the size of the margin at the left end of the sheet S and the size of the margin at the right end of the sheet S between the upper end side and the lower end side of the sheet S in the conveyance direction are determined. The difference becomes smaller.

[Operations and effects of embodiment]
As shown above, the printer 10 according to the present embodiment includes a head 32 having a plurality of nozzles 33 arranged in the front-rear direction 8, a carriage 31 carrying the head 32 and moving in the left-right direction 9, and a carriage 31 in the transport direction. The apparatus includes a conveyance section that conveys the sheet, and a control section 40. The head 32 records one pass of an image on the sheet while the carriage 31 moves once leftward or rightward. The control unit 40 executes the above-described acquisition process and ejection control process.

According to such a printer 10, by acquiring continuous portions of an image and controlling the timing of ejecting ink from the nozzles 33 for each continuous portion of the image, the arrangement direction of the nozzles 33 or the conveyance direction of the sheet is aligned with the carriage 31. To reduce the difference in the size of the margins at the left and right edges of the sheet between the upper end and the lower end of the sheet while improving the quality of the image recorded on the sheet when the moving direction is not perpendicular to the moving direction of the sheet. This effect becomes particularly noticeable when the size of the sheet in the conveying direction is long, for example, when performing long printing or roll paper printing.

In addition, in the acquisition process, the control unit 40 controls, among the image data, first image data when recording the image on the lower end portion 51 in the preceding pass, and second image data when recording the image on the upper end portion 52 in the subsequent pass. If both the image data and the image data do not contain valid data, it is determined that the images are not continuous between the preceding pass and the subsequent pass, and the images recorded on the sheet are determined to be not continuous. Obtain a continuous portion using the determined position as a boundary. Therefore, it is possible to detect a discontinuous part of the image based on the image data and obtain a continuous part of the image.

[Modified example]
The printer 10 according to this embodiment can be configured in various modifications. In the printer according to the first modification, the control unit 40 executes a reception process of receiving image data of an image to be recorded on a sheet for each pass. Before executing an acquisition process using image data of a certain pass, the control unit 40 receives image data of a plurality of passes subsequent to the pass in a reception process. According to the printer according to the first modification, by receiving necessary image data in advance, the acquisition process can be executed smoothly.

In the printer according to the second modification, the control unit 40 executes the above-described acquisition process and ejection control process in response to the size of the sheet in the conveying direction being equal to or larger than a predetermined value, and is less than a predetermined value, instead of the above-described acquisition process and ejection control process, a second ejection control process is executed to eject ink from the nozzles 33 on the entire sheet at the reference timing. According to the printer according to the second modification, when the size of the sheet in the conveyance direction is small, the processing of the control unit 40 can be simplified.

In the printer according to the third modification, the control unit 40 controls the timing at which ink is ejected from the nozzle 33 in accordance with the position of the nozzle 33 in the head 32 in the front-rear direction 8 in the ejection control process. For example, the control unit 40 divides the plurality of nozzles 33 lined up in the front-rear direction 8 into two or more groups in the front-rear direction 8, and divides the nozzles 33 included in one group and the nozzles 33 included in another group. to switch the ink ejection timing. According to the printer according to the third modification, when the arrangement direction of the nozzles 33 or the conveyance direction of the sheet is not perpendicular to the moving direction of the carriage 31, the image quality of the image recorded on the sheet can be further improved.

In the printer 10 according to the present embodiment, in S13, the control unit 40 sets the first image data when recording an image on the lower end portion in the preceding pass and the second image data when recording the image on the upper end portion in the subsequent pass. When both of the data do not include valid data, it is determined that the images are not continuous between the preceding pass and the subsequent pass. In the printer according to the modified example, the control unit 40 may determine whether or not images are continuous between the preceding pass and the subsequent pass using a method other than the above.

[Other variations]
The printer 10 according to the embodiment described above includes a sub-tank 35. The printer according to the modified example does not need to have the sub tank 35. In the printer 10, the cartridge 37 is mounted in a mounting case 36 outside the carriage 31. In the printer according to the modification, the cartridge 37 may be mounted in a mounting case on the carriage 31. Further, the printer 10 is a cartridge type printer in which a cartridge 37 is attached to and detached from a mounting case 36. The printer according to the modification may be a tank-type printer that includes a tank and injects ink into the tank. Further, the printer 10 according to the above embodiment is a monochrome printer that discharges black ink. The printer according to the modification may be a color printer that ejects ink of multiple colors.

10... Printer (liquid ejection device)
21... Feeding roller (part of the conveying section)
22... Conveyance roller (part of the conveyance section)
24...Discharge roller (part of the conveyance section)
31... Carriage 32... Head 33... Nozzle 40... Control section 51... Lower end portion (upstream end portion)
52... Upper end part (downstream end part)

Claims (6)

a head having a plurality of nozzles arranged in a first direction;
a carriage carrying the head and moving in a second direction intersecting the first direction;
a conveyance unit that conveys the sheet in a conveyance direction that intersects the second direction;
comprising a control unit;
The head records one pass of an image on the sheet while the carriage moves once in the second direction;
The above control section is
an acquisition process of acquiring continuous portions of the image that are continuous between passes from the image recorded on the sheet;
The liquid is ejected from the nozzle at the reference timing for the central portion of the continuous portion in the conveying direction, and the recording position on the sheet is set to the second position for the downstream portion of the continuous portion in the conveying direction from the central portion. The liquid is ejected from the nozzle at a timing different from the reference timing so as to be shifted in a first direction along the direction, and the recording on the sheet is performed for a portion upstream in the conveyance direction from the center portion of the continuous portion. A liquid ejection device that executes ejection control processing for ejecting liquid from the nozzle at a timing different from the reference timing so that the position is shifted in a second direction along the second direction. The control unit further executes a reception process of receiving image data of the image for each pass,
The liquid ejecting apparatus according to claim 1, wherein the control unit receives image data of a plurality of passes subsequent to a certain pass in the receiving process, before executing the acquisition process using the image data of a certain pass. . The control unit executes the ejection control process in response to the size of the sheet in the conveyance direction being equal to or larger than a predetermined value, and executes the discharge control process in response to the size of the sheet being less than the predetermined value. 3. The liquid ejection apparatus according to claim 1, wherein a second ejection control process is executed to eject the liquid from the nozzle at the reference timing. 4 . The control unit according to claim 1 , wherein in the ejection control process, the control unit controls timing at which liquid is ejected from the nozzle according to a position of the nozzle in the head in the first direction. Liquid discharge device. In the acquisition process, the control unit includes first image data when recording an image at an upstream end portion in a preceding pass, and an image at a downstream end portion in a subsequent pass following the preceding pass, out of the image data of the image. If both the second image data and the second image data when recording do not contain valid data, it is determined that the images are not continuous between the preceding pass and the following pass, and the images are not continuous. 5. The liquid ejecting apparatus according to claim 1, wherein the continuous portion is acquired from the image using a position determined as a boundary. a head having a plurality of nozzles arranged in a first direction; a carriage carrying the head and moving in a second direction intersecting the first direction; and conveying a sheet in a conveyance direction intersecting the second direction. A program for a liquid ejecting device comprising: a conveyance section; and a control section, wherein the head records an image for one pass on the sheet while the carriage moves once in the second direction. And,
In the above control section,
an acquisition process of acquiring continuous portions of the image that are continuous between passes from the image recorded on the sheet;
The liquid is ejected from the nozzle at the reference timing for the central portion of the continuous portion in the conveying direction, and the recording position on the sheet is set to the second position for the downstream portion of the continuous portion in the conveying direction from the central portion. The liquid is ejected from the nozzle at a timing different from the reference timing so as to be shifted in a first direction along the direction, and the recording on the sheet is performed for a portion upstream in the conveyance direction from the center portion of the continuous portion. A program for executing a discharge control process for discharging liquid from the nozzle at a timing different from the reference timing so that the position is shifted in a second direction along the second direction.

Images