JP2015160431A - Liquid ejection device, control method of liquid ejection device, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in quality of an image recorded on a recording medium while reducing discharge of liquid contributing to formation of the image.SOLUTION: When a second discharge mode in which a discharging amount is smaller than a discharging amount in a first discharge mode is selected, dots for an image are formed based on changed discharge data in which at least one of discharged dot elements in which discharge amounts are set to larger than zero is changed to thinning dot elements in which discharge amounts are set to zero. At this time, preliminary discharge dots are formed so that a non-discharge period of each of a plurality of discharge ports does not exceed a predetermined period. With respect to each dot element array corresponding to each of the plurality of discharge ports in the changed discharge data, when the discharge dot elements do not exist and the thinning dot elements exist between certain discharge dot elements and specific dot elements, the preliminary discharge dots are formed at dot positions corresponding to the thinning dot element.

Description

  The present invention relates to a liquid ejection apparatus, a control method for a liquid ejection apparatus, and a control program.

In Patent Document 1, in order to recover the ink ejection characteristics deteriorated by increasing the viscosity of the ink in the nozzle (ejection port) of the inkjet head, the blank area where the image to be printed on the printing paper is not formed An image forming apparatus (liquid ejecting apparatus) that preliminarily ejects ink droplets from nozzles that do not contribute to image formation at predetermined time intervals is disclosed.
Patent Document 2 discloses a technique for setting a thinning ratio for a page on which an image is printed and performing thinning printing at this ratio.

JP 2007-144681 A JP 2007-79816 A

  By the way, in the image forming apparatus disclosed in Patent Document 1, dots are formed in an area completely unrelated to the data relating to the image, although the image is not formed by the preliminary ejection of ink droplets. Therefore, there is a problem that the print quality is deteriorated. Here, in the image forming apparatus disclosed in Patent Document 1, when thinning printing is performed as in the technique disclosed in Patent Document 2, the image forming apparatus contributes to image formation as compared with the case where printing is performed without thinning. The number of ink droplets that are ejected decreases, and the number of preliminary ejections of ink droplets that do not contribute to image formation increases. For this reason, when the thinning printing is performed, the above-described deterioration of the printing quality due to the preliminary ejection becomes more remarkable as compared with the case where the printing is performed without thinning.

  Accordingly, an object of the present invention is to provide a liquid ejecting apparatus and a liquid ejecting apparatus capable of suppressing a decrease in the quality of an image recorded on a recording medium while reducing the ejection of a liquid that contributes to image formation. A control method and a control program are provided.

  In order to solve the above problems, a liquid ejection apparatus according to the present invention is configured to relatively move a liquid ejection head having a plurality of ejection openings for ejecting liquid, a recording medium, and the liquid ejection head along a predetermined direction. And a dot element array comprising a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction on the recording medium, the moving data for causing the recording medium to be discharged, and ejection data for recording an image on the recording medium A plurality of discharge ports corresponding to each of the plurality of discharge ports, and discharge data storage means for storing discharge data in which a discharge amount of liquid to be discharged at a corresponding dot position is set for each dot element; and Control means for controlling the liquid discharge head, wherein the control means is a first discharge mode and liquid discharged from the plurality of discharge ports in the first discharge mode. When a selection process for selecting one discharge mode from at least two discharge modes of the second discharge mode with a small discharge amount is performed, and the first discharge mode is selected by the selection process, the plurality of discharge ports During the first image recording control process and the first image recording control process for controlling the liquid ejection head based on the ejection data so that the ejected liquid lands and image dots are formed on the recording medium. In addition, preliminary discharge for discharging liquid from the plurality of discharge ports so that a non-discharge period from when the liquid is discharged to each of the plurality of discharge ports until the next time the liquid is discharged does not exceed a predetermined period. The first preliminary discharge data generation processing for generating the first preliminary discharge data based on the discharge data and the liquid discharged from the plurality of discharge ports land and record an image And a first preliminary ejection control process for controlling the liquid ejection head based on the first preliminary ejection data so that preliminary ejection dots are formed on the recording medium to be recorded, and the second ejection mode is performed by the selection process. Is selected, at least one discharge dot element among the discharge dot elements whose discharge amount is larger than zero in the discharge data is thinned out with the discharge amount set to zero. Based on the changed discharge data generation process for generating the changed discharge data changed to the dot element and the changed discharge data so that the liquid discharged from the plurality of discharge ports lands and an image dot is formed on the recording medium. In the second image recording control process for controlling the liquid ejection head and the second image recording control process, the non-ejection period for each of the plurality of ejection ports is Second preliminary discharge data generation processing for generating second preliminary discharge data related to the preliminary discharge based on the changed discharge data so that the liquid discharged from the plurality of discharge ports is landed so as not to exceed a predetermined period. A second preliminary ejection control process for controlling the liquid ejection head based on the second preliminary ejection data so that preliminary ejection dots are formed on the recording medium on which the image is recorded, and the second preliminary ejection control process is performed. In the preliminary ejection data generation process, for each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, the ejection dot element and the dot position corresponding to the certain ejection dot element A dot element corresponding to the dot position on the downstream side in a predetermined direction, the dot element having an interval corresponding to the predetermined period with an interval from the certain ejection dot element When the discharge dot element does not exist between the specific dot element and at least one thinning dot element exists, the discharge dot element is between the specific dot element and the specific dot element. The second preliminary ejection data is generated so that the preliminary ejection dots are formed at the dot positions corresponding to at least one of the thinned dot elements.

  The method for controlling a liquid ejection apparatus according to the present invention includes a liquid ejection head having a plurality of ejection openings for ejecting liquid, and a movement for relatively moving the recording medium and the liquid ejection head along a predetermined direction. And a plurality of dot element arrays comprising a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction on the recording medium, the discharge data for recording an image on the recording medium A plurality of discharge ports corresponding to each of the discharge ports, and a discharge data storage means for storing discharge data in which a discharge amount of liquid to be discharged at a corresponding dot position is set for each dot element; An apparatus control method comprising: a first discharge mode; and a second discharge mode in which a discharge amount of liquid discharged from the plurality of discharge ports is smaller than that in the first discharge mode. A selection process for selecting one discharge mode from two discharge modes; and when the first discharge mode is selected by the selection process, the liquid discharged from the plurality of discharge ports is landed and recorded. Each of the plurality of ejection openings in the first image recording control process for controlling the liquid ejection head based on the ejection data and the first image recording control process so that image dots are formed on the medium. The first preliminary discharge data relating to the preliminary discharge for discharging the liquid from the plurality of discharge ports so that the non-discharge period from when the liquid is discharged to the next time the liquid is discharged does not exceed a predetermined period, First preliminary discharge data generation processing generated based on the discharge data, and preliminary discharge dots are formed on a recording medium on which an image is recorded by landing the liquid discharged from the plurality of discharge ports. And a first preliminary ejection control process for controlling the liquid ejection head based on the first preliminary ejection data, and the ejection data when the second ejection mode is selected by the selection process. Generates changed discharge data in which at least one of the discharge dot elements whose discharge amount is greater than zero is changed to a thinned dot element whose discharge amount is set to zero A modified ejection data generation process for controlling the liquid ejection head based on the modified ejection data so that the liquid ejected from the plurality of ejection openings lands and image dots are formed on the recording medium. In the image recording control process and the second image recording control process, the pre-discharge period is set so that the non-ejection period does not exceed the predetermined period for each of the plurality of ejection openings. Second preliminary discharge data generation processing for generating second preliminary discharge data related to preparatory discharge based on the changed discharge data, and a recording medium on which an image is recorded by landing of liquid discharged from the plurality of discharge ports And a second preliminary ejection control process for controlling the liquid ejection head based on the second preliminary ejection data so that the preliminary ejection dots are formed on the second preliminary ejection data. For each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, a certain ejection dot element and the dot located downstream in the predetermined direction from the dot position corresponding to the certain ejection dot element A dot element corresponding to a position, and a specific dot element that is a dot element whose distance from the certain discharge dot element corresponds to the predetermined period. When there is no ejection dot element and at least one thinning dot element exists, it corresponds to at least one thinning dot element between the certain ejection dot element and the specific dot element The second preliminary discharge data is generated so that the preliminary discharge dots are formed at the dot positions.

  The control program of the present invention includes a liquid ejection head having a plurality of ejection openings for ejecting liquid, a moving unit for relatively moving the recording medium and the liquid ejection head along a predetermined direction, and recording. Discharge data for recording an image on a medium, and each of the plurality of discharge ports includes a dot element row composed of a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction on the recording medium. And a discharge data storage unit for storing discharge data in which a discharge amount of liquid to be discharged at a corresponding dot position is set for each dot element. In the control program, the liquid ejection device has a first ejection mode and a smaller amount of liquid ejected from the plurality of ejection ports than the first ejection mode. When a selection process for selecting one discharge mode from at least two discharge modes of the second discharge mode is executed, and when the first discharge mode is selected by the selection process, the discharge is performed from the plurality of discharge ports. In the first image recording control process for controlling the liquid ejection head based on the ejection data and the first image recording control process so that the liquid is landed and image dots are formed on the recording medium. The preliminary ejection for ejecting liquid from the plurality of ejection ports is performed so that the non-ejection period from when the liquid is ejected to each of the plurality of ejection ports until the next liquid is ejected does not exceed a predetermined period. First preliminary ejection data generation processing for generating first preliminary ejection data based on the ejection data, and liquid ejected from the plurality of ejection ports land and images are recorded. And a first preliminary ejection control process for controlling the liquid ejection head based on the first preliminary ejection data so that preliminary ejection dots are formed on the recording medium, and the second ejection mode is determined by the selection process. When selected, in the discharge data, at least one discharge dot element among the discharge dot elements whose discharge amount is larger than zero is set as a thinned dot whose discharge amount is set to zero. Based on the changed discharge data generation process for generating changed discharge data changed into elements, and the changed discharge data so that the liquid discharged from the plurality of discharge ports lands and image dots are formed on the recording medium. During the second image recording control process for controlling the liquid ejection head and the second image recording control process, the non-ejection period for each of the plurality of ejection ports is the place. Second preliminary discharge data generation processing for generating second preliminary discharge data related to the preliminary discharge based on the changed discharge data so that the liquid discharged from the plurality of discharge ports is landed so as not to exceed a predetermined period. A second preliminary ejection control process for controlling the liquid ejection head based on the second preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded, and the second preliminary ejection control process is executed. In the preliminary ejection data generation process, for each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, the ejection dot element and the dot position corresponding to the certain ejection dot element A dot element corresponding to the dot position on the downstream side in a predetermined direction, the dot element having an interval corresponding to the predetermined period with an interval from the certain ejection dot element When the discharge dot element does not exist between the specific dot element and at least one thinning dot element exists, the discharge dot element is between the specific dot element and the specific dot element. The second preliminary ejection data is generated so that the preliminary ejection dots are formed at the dot positions corresponding to at least one of the thinned dot elements.

  According to the present invention, in the second discharge mode, since the discharge is performed based on the changed discharge data in which at least one discharge dot element is changed to the thinned dot element, the liquid that contributes to the image compared to the first discharge mode. The number of discharges can be reduced. In the second ejection mode, if there is no ejection dot element and a thinning dot element exists between a certain ejection dot element and the specific dot element, the dot corresponding to this thinning dot element Preliminary ejection dots are formed at the positions. Accordingly, since preliminary ejection dots are formed at the dot positions where image dots are formed in the first ejection mode, it is possible to suppress degradation of the quality of the image recorded on the recording medium.

1 is a schematic side view of an ink jet printer according to an embodiment. It is a schematic sectional drawing of the head main body shown in FIG. It is an electrical block diagram of the inkjet printer shown in FIG. It is explanatory drawing of discharge data. (A) is a figure explaining the change discharge data generation process, (b) is a figure explaining the 2nd preliminary discharge data generation process, (c) is about the 2nd preliminary discharge data generation process which concerns on a modification. It is a figure explaining. It is a flowchart of the inkjet printer shown in FIG. It is a flowchart about the 2nd preliminary discharge data generation process shown in FIG. It is a figure explaining the preliminary discharge dot position determination process which concerns on a modification. It is a flowchart about the preliminary discharge dot position determination process which concerns on a modification.

  A preferred embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the ink jet printer 101 of this embodiment has a substantially rectangular parallelepiped casing 101a. A paper discharge unit 15 is provided on the top plate of the housing 101a. In the internal space of the housing 101a, an inkjet head 1 that discharges black ink (hereinafter referred to as the head 1), a transport mechanism 16 that transports paper P, a paper tray 17 that stores a plurality of paper P in a stacked state, In addition, a control device 100 that controls the entire operation of the printer 101 is disposed. A cartridge (not shown) is mounted in the internal space of the housing 101a. This cartridge stores black ink. The cartridge is connected to the head 1 via a tube and a pump (both not shown), and ink is supplied to the head 1.

  The head 1 has a substantially rectangular parallelepiped shape elongated in the main scanning direction, and is fixed to the support frame 3 below the head 1. That is, the printer 101 is a line type printer. The head 1 has a head body 2 having a discharge surface 2a formed with a plurality of discharge ports 10 (see FIG. 2) on its lower surface. Here, the main scanning direction is a direction parallel to the horizontal plane, which is orthogonal to the conveyance direction (sub-scanning direction) of paper P conveyed by nip rollers 13c and 13d described later.

  As shown in FIG. 2, the head body 2 is a laminate including a flow path unit 9 and an actuator unit 21 fixed to the upper surface of the flow path unit 9. A large number of individual ink flow paths 93 are formed in the flow path unit 9 from the outlet of the manifold flow path 91 to the discharge port 10 via the pressure chamber 92. The actuator unit 21 includes a plurality of actuators 22 (see FIG. 3) corresponding to the pressure chambers 92, and has a function of selectively applying ejection energy to the ink in the pressure chambers 92. When a drive signal is supplied from the control device 100 to the actuator 22, pressure is applied to the ink in the pressure chamber 92 and ink is ejected from the ejection port 10. The lower surface of the flow path unit 9 is a discharge surface 2a, and a large number of discharge ports 10 are arranged. The ejection ports 10 are arranged at an interval of 600 dpi, which is the resolution in the main scanning direction with respect to the main scanning direction.

  The head 1 having the head main body 2 having the above-described configuration is controlled by the control device 100 so that the ink discharge interval is controlled so that the ink from the discharge port 10 lands on the paper P at an interval of 600 dpi in the sub-scanning direction. Is done. That is, in the present embodiment, the resolution in the main scanning direction and the resolution in the sub scanning direction are both 600 dpi, and the paper P is partitioned in a grid pattern with an interval of 1/600 inch in the main scanning direction and the sub scanning direction. A plurality of dot positions (dot areas) are defined. Further, in the present embodiment, there are four types of ink discharge amounts (large amount, medium amount, small amount, non-discharge) that can be discharged from the discharge port 10 of the head 1 within one printing cycle. Accordingly, only four levels of density corresponding to the ink discharge amount can be expressed by dots formed on the paper P. Note that the printing cycle is the time required for the paper P to be conveyed by a unit distance corresponding to the sub-scanning direction resolution.

  Returning to FIG. 1, the transport mechanism 16 constitutes a transport path for the paper P that passes from the paper tray 17 between the head 1 and the platen 19 to the paper discharge unit 15. The transport mechanism 16 includes a pickup roller 12, nip rollers 13a to 13f, and guides 14a to 14e. The pickup roller 12 sends out the paper P in the paper tray 17 one by one. The nip rollers 13a to 13f are arranged along the transport path and apply a transport force to the paper P. The guides 14a to 14e are respectively arranged between the pickup roller 12 and the nip rollers 14a to 14e in the transport path, and the sheet P to which the transport force is applied by the nip rollers 14a to 14e reaches the next nip rollers 14a to 14e. The paper P is guided. When the paper P transported by the transport mechanism 16 passes between the ejection surface 2a of the head 1 and the platen 19, ink is ejected from the ejection port 10 of the head 1, and a desired monochrome image is formed on the paper P. The The paper P on which the image is formed is further transported by the transport mechanism 16 and discharged to the paper discharge unit 15.

  Next, the control device 100 will be described in detail with reference to FIG. The control device 100 includes a central processing unit (CPU) 31, a read only memory (ROM) 32, a random access memory (RAM) 33, a control circuit 35, and the like that are connected to each other by a bus. The control circuit 35 is connected to various devices or drive units of the printer 101 such as the head 1 and the conveyance motor 5 that drives the pickup roller 12 and the nip rollers 13 a to 13 f of the conveyance mechanism 16. The control circuit 35 is connected to an external device 39 such as a PC via a communication I / F (Interface) 38 so that data communication is possible. Based on the recording command transmitted from the external device 39, the CPU 31 controls the head 1, the transport motor 5, and the like via the control circuit 35 to record an image on the paper P. In the present embodiment, one CPU 31 performs processes related to various controls, but the present invention is not limited to this. For example, a form in which a plurality of CPUs share processes related to various controls, a form in which a control circuit such as an ASIC performs processes related to various controls, and one or more CPUs and a control circuit such as one or more ASICs cooperate Thus, a form for performing processing related to various controls may be employed.

  The ROM 32 stores a control program 32a for controlling the printer 101. The RAM 33 is used as a work area from which the control program 32a is read or as a storage area for temporarily storing data. The RAM 33 includes a discharge data storage unit 33a, a changed discharge data storage unit 33b, a first preliminary discharge data storage unit 33c, a second preliminary discharge data storage unit 33d, and a thinning pattern data storage unit 33e.

  The ejection data storage unit 33 a stores ejection data received from the external device 39 for recording an image on the paper P. As shown in FIG. 4, the discharge data is a collection of a plurality of dot elements corresponding to each of the plurality of discharge ports 10 in one printing cycle for (time required for printing one frame image) / (one printing cycle). It becomes. For each dot element, a discharge amount of ink discharged from the discharge port 10 within one printing cycle is set. In the present embodiment, the discharge amount set for the dot element is “S” when the amount of ink discharged from the discharge port 10 is small, and the discharge amount set for the dot element is “M” when the amount is medium. ”, The discharge amount set to the dot element in the case of a large amount is represented as“ L ”, and the discharge amount set to the dot element in the case of zero is represented as“ 0 ”.

  Further, the ejection data includes a plurality of dot element rows so as to correspond to each of the plurality of ejection ports 10. Here, in the dot element row, a plurality of dot elements corresponding to a plurality of dot positions arranged along the conveyance direction on the paper P are arranged along a conveyance direction of a plurality of dot positions corresponding to the plurality of dot elements. They are arranged in order. That is, each dot element row is a set of a plurality of dot elements corresponding to one ejection port 10. As described above, the ejection data includes a plurality of dot elements corresponding to a plurality of dot positions arranged in a matrix along the two directions of the main scanning direction and the sub-scanning direction on the paper P. The ink discharge amount set for each dot element is the ink discharge amount discharged at the corresponding dot position. Hereinafter, the arrangement direction of the dot element row will be described as a direction from the dot element corresponding to the dot position on the upstream side in the transport direction to the dot element corresponding to the dot position on the downstream side in the transport direction.

The changed discharge data storage unit 33b stores changed discharge data to be described later. The first preliminary ejection data storage unit 33c stores first preliminary ejection data described later, and the second preliminary ejection data storage unit 33d stores second preliminary ejection data described later. For each of the changed ejection data, the first preliminary ejection data, and the second preliminary ejection data, a plurality of dot element arrays each composed of a plurality of dot elements corresponding to a plurality of dot positions on the paper P are also provided in the same manner as the ejection data. Including.
The thinning pattern data storage unit 33e stores thinning pattern data used for thinning image dots formed on the paper P.

  In accordance with the control program 32 a read from the ROM 32, the CPU 31 performs various processes while storing the calculation result in the RAM 33. In the present embodiment, the CPU 31 performs selection processing, changed ejection data generation processing, first and second image recording control processing, first and second preliminary ejection data generation processing, and first and second preliminary according to the control program 32a. A discharge control process is performed.

  The selection process is a process of selecting an ejection mode when recording an image on the paper P. Specifically, the CPU 31 changes one discharge mode from two discharge modes of the first discharge mode and the second discharge mode in which the amount of ink discharged from the plurality of discharge ports 10 is smaller than that in the first discharge mode. select. In the present embodiment, the CPU 31 selects a discharge mode based on the command content of the recording command transmitted from the external device 39. As a modification, the discharge mode may be selected based on a command input from the user via the touch panel of the printer 101 or operation keys (both not shown).

The first image recording control process, the first preliminary ejection data generation process, and the first preliminary ejection control process are processes that are executed when the first ejection mode is selected as the ejection mode by the selection process.
The first image recording control process is based on the discharge data stored in the discharge data storage unit 33a so that the ink discharged from the discharge ports 10 of the head 1 lands and image dots are formed on the paper P. This is a process for controlling the head 1.

  In the first preliminary ejection data generation process, in the first image recording control process, a non-ejection period from the ejection of ink to each of the plurality of ejection openings 10 until the next ejection of the ink is a predetermined period (hereinafter referred to as the first ejection data generation process) The first preliminary ejection data for preliminary ejection for ejecting ink from the plurality of ejection ports 10 is generated based on the ejection data stored in the ejection data storage unit 33a so as not to exceed the allowable range excess period). It is. Specifically, the ink based on the first image recording control process is performed after the ink ejection or the preliminary ejection (previous ejection) based on the first image recording control process is performed on each ejection port 10 based on the ejection data. Is calculated as a non-ejection period (a period in which ink is not continuously ejected from the ejection port 10) until the next ejection. When the non-ejection period is equal to or longer than the allowable range excess period, a predetermined preliminary ejection period from when the previous ejection is performed until ink is ejected next based on the first image recording control process. First preliminary discharge data is generated so that preliminary discharge is performed every time. Here, the allowable range excess period is a minimum period of a non-ejection period in which an abnormality may occur in ink ejection based on the first image recording control process. That is, even if the preliminary ejection is performed after the allowable range exceeding period from the previous ejection, the ink ejection based on the first image recording control process thereafter is abnormal due to the thickening of the ink in the ejection port 10. Can occur. The preliminary ejection period is a period obtained by subtracting a period corresponding to one printing cycle from the allowable range excess period. In the present embodiment, the pre-recording ejection in which ink is ejected from all the ejection ports 10 immediately before the image recording on the paper P is started (the front end of the paper P reaches the area facing the head 1). Do. Therefore, the non-ejection period from the previous pre-recording ejection until the ink based on the first image recording control process is ejected on the paper P is calculated from the start of image recording on the paper P.

  The first preliminary ejection control process is stored in the first preliminary ejection data storage unit 33c such that preliminary ejection dots are formed on the paper P on which the ink ejected from the plurality of ejection ports 10 has landed and an image is recorded. In this process, the head 1 is controlled based on the first preliminary ejection data. The first preliminary ejection control process is executed in parallel with the first image recording control process.

On the other hand, the changed ejection data generation process, the second image recording control process, the second preliminary ejection data generation process, and the second preliminary ejection control process are executed when the second ejection mode is selected as the ejection mode by the selection process. Process.
The changed ejection data generation process will be described with reference to FIG. FIG. 5A is a diagram illustrating a dot element row in each of the ejection data and the modified ejection data. In FIG. 5A, for convenience of explanation, among the dot elements of the ejection data, dot elements corresponding to dot positions where image dot formation is not permitted in the thinning pattern data are filled with vertical lines. Show. In addition, among the dot elements of the changed ejection data, the thinned dot elements are shown by being shaded.

  In the changed ejection data generation processing, in the ejection data, at least one ejection dot element among the ejection dot elements that are the dot elements having a set ejection volume larger than zero is thinned out with the ejection volume set to zero. This is processing for generating changed ejection data changed to elements. In the present embodiment, the changed ejection data is generated using the thinning pattern data stored in the thinning pattern data storage unit 33e.

The thinning pattern data is data that determines whether or not image dot formation is allowed for each dot position on the paper P. In the present embodiment, in the thinning pattern data, the ratio of the total number of dot positions that allow the formation of image dots (thinning rate) to the number of all dot positions on the paper P is set to 50%.
In the modified ejection data generation process, as shown in FIG. 5A, the ejection dot element corresponding to the dot position where image dot formation is not permitted in the ejection data is changed to a thinned dot element, and the modified ejection data is changed. Generate data. The changed discharge data generated in this way is stored in the changed discharge data storage unit 33b.

  The second image recording control process is based on the changed discharge data stored in the changed discharge data storage unit 33b so that the ink discharged from the discharge ports 10 of the head 1 lands and image dots are formed on the paper P. This is a process for controlling the head 1. Here, as described above, the changed ejection data is data in which at least one ejection dot element is changed to a thinned dot element in the ejection data. Therefore, the second image recording control process for ejecting ink from the plurality of ejection ports 10 based on the changed ejection data is more than the first image recording control process for ejecting ink from the plurality of ejection ports 10 based on the ejection data. The amount of ink discharged that contributes to the formation of an image (image dot) can be reduced.

In the second preliminary ejection data generation process, in the second image recording control process, the second preliminary ejection data related to the preliminary ejection is changed to a changed ejection data storage unit so that the non-ejection period does not exceed the allowable range excess period. This is a process that is generated based on the changed ejection data stored in 33b.
The second preliminary ejection control process is stored in the second preliminary ejection data storage unit 33d so that preliminary ejection dots are formed on the paper P on which the ink ejected from the plurality of ejection ports 10 is landed and an image is recorded. This is a process for controlling the head 1 based on the second preliminary ejection data. The second preliminary ejection control process is executed in parallel with the second image recording control process. In the second preliminary ejection control process and the first preliminary ejection control process described above, the second smallest ink amount (zero in this embodiment) that is the second smallest ink from the ejection port 10 is formed at the dot position where the preliminary ejection dot is formed. The head 1 is controlled so that preliminary ejection dots are formed.

  Next, the second preliminary ejection data generation process will be described in detail with reference to FIG. FIG. 5B is a diagram showing a certain dot element row of the changed discharge data, and second preliminary discharge data for the dot element row. In FIG. 5B, for the convenience of explanation, among the dot elements of the changed ejection data, the thinned dot elements are shown by hatching, and the thinned dot elements are set to the ejection dot elements before the change. The discharge amount that has been recorded is shown in parentheses. In the second preliminary ejection data, the dot element corresponding to the dot position where the preliminary ejection dot is formed is represented by “F”, and the dot element corresponding to the dot position where the preliminary ejection dot is not formed is represented by “0”. .

  By the way, in the second image recording control process, the number of times ink droplets contributing to image formation are ejected is reduced and ink droplets not contributing to image formation are preliminary ejected as compared to the first image recording control process. Will be increased. Therefore, when the second preliminary discharge data is generated by the same method as the first preliminary discharge data generation process, many preliminary discharge dots are formed at positions irrelevant to the image recorded on the paper P, and the preliminary discharge data is generated. There is a possibility that the image quality deterioration due to the image becomes more remarkable.

  Therefore, in the second preliminary ejection data generation process, for each dot element row in the modified ejection data, there is no ejection dot element between a certain ejection dot element (target ejection dot element) and the specific dot element, and When at least one thinned dot element exists, the preliminary discharge dots are formed so that the preliminary discharge dots are formed at dot positions corresponding to at least one thinned dot element between the target discharge dot element and the specific dot element. 2 Preliminary ejection data is generated. Here, the specific dot element is a dot element corresponding to a dot position downstream of the dot position corresponding to the target ejection dot element in the transport direction, and the interval with the target ejection dot element is within the allowable range excess period. It is a dot element having a corresponding interval. That is, when it is assumed that the specific dot element is an ejection dot element, the ink is not ejected between the ejection of the ink related to the target ejection dot element and the ejection of the ink related to the specific dot element In this case, due to the thickening of the ink in the ejection port 10, an abnormality may occur in the ink ejection related to the specific dot element.

By generating the second preliminary discharge data as described above, image dots are not formed in the second discharge mode, but many preliminary discharge dots are formed at the dot positions where the image dots are formed in the first discharge mode. The possibility of being formed is increased. As a result, the number of preliminary ejection dots formed at a position unrelated to the image recorded on the paper P can be reduced, so that it is possible to suppress deterioration in the quality of the image recorded on the paper P. it can.
Further, in the present embodiment, when there is no ejection dot element between the target ejection dot element and the specific dot element and there are a plurality of thinning dot elements, as shown in FIG. The dot position corresponding to the thinned dot element (the thinned dot element at the most downstream in the arrangement direction) whose corresponding dot position is the most downstream in the transport direction is determined as the preliminary discharge dot position for forming the preliminary discharge dots. By doing so, the non-ejection period from when the preliminary ejection related to the preliminary ejection dots is performed to when the ink based on the second image recording control process is next ejected can be shortened. Is less likely to exceed the permissible range period. As a result, since the number of preliminary ejection dots recorded on the paper P can be reduced, it is possible to further suppress the deterioration of the quality of the image recorded on the paper P.

As a modification, when there is no ejection dot element between the target ejection dot element and the specific dot element and there are a plurality of thinning dot elements, as shown in FIG. You may determine the dot position corresponding to the thinning dot element with the largest discharge amount set to the discharge dot element as a preliminary discharge dot position. In this case, an image dot is not formed in the second discharge mode, but a preliminary discharge dot is formed at a dot position where an image dot having a large density value is formed in the first discharge mode. It is possible to further suppress the deterioration of the quality of the image.
If there are multiple thinning dot elements with the largest discharge amount set for the discharge dot element before the change, among these thinning dot elements, the thinning dot whose corresponding dot position is the most downstream in the transport direction It is preferable to determine the dot position corresponding to the element as a preliminary discharge dot position for forming the preliminary discharge dot.

  Hereinafter, an example of processing executed by the CPU 31 according to the control program 32a will be described with reference to FIG. First, when receiving a recording command from the external device 39, the CPU 31 stores the ejection data included in the recording command in the ejection data storage unit 33a (S1). Next, the CPU 31 selects one of the first discharge mode and the second discharge mode based on the content of the recording command received from the external device 39 (S2: selection process). When the discharge mode selected by the selection process is the first discharge mode (S3: YES), the CPU 31 generates first preliminary discharge data based on the discharge data stored in the discharge data storage unit 33a. (S4: First preliminary ejection data generation process). Next, the CPU 31 controls the transport motor 5 so that the paper P stacked on the paper tray 17 is transported to the paper discharge unit 15 along the transport path, and image dots are formed on the paper P. As described above, the head 1 is controlled based on the ejection data stored in the ejection data storage unit 33a, and the first preliminary ejection data stored in the first preliminary ejection data storage unit 33c so that the preliminary ejection dots are formed on the paper P. The head 1 is controlled based on the ejection data (S5: first image recording control process, first preliminary ejection control process). As a result, a desired monochrome image is formed on the paper P. At this time, since the non-ejection period does not exceed the allowable range excess period for each ejection port 10, it is possible to normally eject ink based on the first image recording control process. As a result, it is possible to suppress the deterioration of the quality of the image recorded on the paper P. When the process of step S5 ends, this process ends.

  On the other hand, when the discharge mode selected by the selection process in step S2 is the second discharge mode (S3: NO), the CPU 31 stores the discharge data stored in the discharge data storage unit 33a and the thinning pattern data storage unit. Based on the thinning pattern data stored in 33e, the changed discharge data is generated (S5: changed discharge data generation process). Next, the CPU 31 generates second preliminary discharge data based on the changed discharge data stored in the changed discharge data storage unit 33b (S6: second preliminary discharge data generation process). Next, the CPU 31 controls the transport motor 5 so that the paper P stacked on the paper tray 17 is transported to the paper discharge unit 15 along the transport path, and image dots are formed on the paper P. In this way, the head 1 is controlled based on the changed discharge data stored in the changed discharge data storage unit 33b, and the second preliminary discharge data storage unit 33d stores the preliminary discharge dots so that the preliminary discharge dots are formed on the paper P. 2. The head 1 is controlled based on the preliminary ejection data (S7: second image recording control process, second preliminary ejection control process). As a result, a desired monochrome image is formed on the paper P with a smaller amount of ink than in the first ejection mode. Also at this time, since the non-ejection period does not exceed the allowable range excess period for each ejection port 10, ink ejection based on the second image recording control process can be performed normally. When the process of step S7 ends, this process ends.

Next, the second preliminary ejection data generation processing in step S6 described above will be described in detail with reference to FIG.
First, the CPU 31 sets one of a plurality of dot element rows of the changed discharge data stored in the changed discharge data storage unit 33b as a target dot element row (A1). Next, the CPU 31 sets a noticeable ejection dot element and a specific dot element from the dot elements belonging to the noticeable dot element row (A2). The noticeable ejection dot element is an ejection dot element corresponding to the dot position on the most upstream side in the transport direction (ejection dot element on the most upstream side in the arrangement direction) among the ejection dot elements that are not yet set as the noticeable ejection dot elements. In step A2, when the discharge dot element corresponding to the most upstream dot position in the transport direction is set as the target discharge dot element among the discharge dot elements in the target dot element row, the attention set from the pre-recording discharge is set. When the non-ejection period until the ink related to the ejection dot element is ejected is equal to or longer than the allowable range, the preliminary ejection period from the pre-recording ejection until the ink related to the target ejection dot element is ejected. A preliminary ejection dot position for forming a preliminary ejection dot is determined upstream of the dot position corresponding to the target ejection dot element so that preliminary ejection is performed every time.

  Next, the CPU 31 determines whether or not there is a discharge dot element between the target discharge dot element and the specific dot element (A3). If it is determined that there is a discharge dot element (A3: YES), a preliminary discharge dot is placed at a dot position between the dot position corresponding to the target discharge dot element and the dot position corresponding to this discharge dot element. Assuming that there is no need to form them, the process returns to step A2, and a target ejection dot element and a specific dot element are newly set.

  On the other hand, when it is determined that there is no ejection dot element between the target ejection dot element and the specific dot element (A3: NO), the CPU 31 corresponds to the dot position corresponding to the target ejection dot element and the specific dot element. It is determined that it is necessary to form a preliminary ejection dot at least at any dot position between the dot position to be performed. Then, the CPU 31 determines whether or not a thinned dot element exists between the target ejection dot element and the specific dot element (A4). When it is determined that a thinning dot element exists (A4: YES), as shown in FIG. 5B, the thinning dot elements between the target ejection dot element and the specific dot element correspond. The dot position corresponding to the thinned dot element whose dot position is the most downstream in the transport direction is determined as the preliminary discharge dot position (A5: preliminary discharge dot position determination process). When the process of step A5 is completed, the process proceeds to step A7.

  On the other hand, when it is determined that there is no thinned dot element between the target ejection dot element and the specific dot element (A4: NO), the preliminary ejection is performed after the ink related to the target ejection dot element is ejected. The dot position one upstream of the dot position corresponding to the specific dot element is determined as the preliminary discharge dot position so that the preliminary discharge is performed when the period elapses (A6). When the process of step A6 is completed, the process proceeds to step A7.

  In the processing of step A7, it is determined whether or not all the ejection dot elements are set as the attention ejection dot elements in the attention dot element row. When it is determined that there is an ejection dot element that is not set as the target ejection dot element (A7: NO), after preliminary ejection is performed on the preliminary ejection dot position determined in step A5 or step A6, Until the ink related to the next ejection dot element is ejected, the preliminary ejection dot position is determined so that the preliminary ejection is performed for each preliminary ejection period (A8). When the process of step A8 ends, the process returns to step A2, and a target ejection dot element and a specific dot element are newly set.

  On the other hand, when it is determined that all the ejection dot elements have been set as the target ejection dot elements (A7: YES), the CPU 31 performs preliminary ejection on the preliminary ejection dot positions determined in step A5 or step A6. The remaining preliminary ejection dot positions are determined so that preliminary ejection is performed for each of the preliminary ejection periods from when the recording is performed until image recording on the paper P is completed (A9). Next, the CPU 31 determines whether or not all the dot element rows of the changed ejection data are set as the attention dot element row (A10). If it is determined that there is a dot element row that is not set as the target dot element row (A10: NO), the process returns to step A1, and a new target dot element row is set. On the other hand, when it is determined that all the dot element rows are set as the target dot element row (A10: YES), the preliminary ejection dots are formed at the dot positions determined as the preliminary ejection dot positions at the dot positions of the paper P. In this way, the second preliminary ejection data is generated (A11), and this process is terminated.

As described above, according to the present embodiment, in the second ejection mode, ink is ejected based on the changed ejection data in which the ejection dot element is changed to the thinned dot element, and thus contributes to the image compared to the first ejection mode. The number of ink ejections can be reduced. In the second ejection mode, if there is no ejection dot element between the target ejection dot element and the specific dot element, and there is a thinning dot element, the dot position corresponding to this thinning dot element Thus, preliminary ejection dots are formed. Accordingly, since preliminary ejection dots are formed at the dot positions where image dots are formed in the first ejection mode, it is possible to suppress deterioration in the quality of the image recorded on the paper P.
In addition, when the preliminary ejection dots are formed at the dot positions corresponding to the thinned dot elements, the ejection amount of the ejected ink is the second smallest amount after zero. Thus, the amount of ink discharged from 10 can be reduced.

  Next, a modified example related to the second preliminary ejection generation process of the present embodiment will be described with reference to FIGS. This modification is different from the above-described embodiment in the preliminary ejection dot position determination process in step A5 described with reference to FIG.

  As described above, in the changed ejection data, among the ejection dot elements in the ejection data, ejection dot elements corresponding to dot positions where image dot formation is not permitted in the thinning pattern data are changed to thinning dot elements. It is data. For this reason, when the image recording range of the paper P is divided into a plurality of areas, it corresponds to the ejection dot elements in the changed ejection data with respect to the total number of dot positions corresponding to the ejection dot elements in the ejection data in each area. The ratio of the total number of dot positions (hereinafter referred to as “thinning ratio”) may be different for each region. That is, the rate at which the image dots are thinned out by the changed ejection data generation process varies from region to region. As described above, there is a difference in image density (image density) of formed images between regions having different thinning ratios.

  Here, since the dot position corresponding to the thinned dot element is the dot position where the image dot is formed in the first discharge mode, when the preliminary discharge dot is formed at the dot position corresponding to this thinned dot element, This preliminary ejection dot contributes at least to the image formation on the paper P and affects the image density of the formed image.

  Therefore, when preliminary ejection dots are formed at the dot positions corresponding to the thinned dot elements in the area where the thinning ratio is larger than the thinning ratio of the thinning pattern data, the total number of dot positions corresponding to the ejection dot elements in the ejection data Dot positions where dots contributing to image formation are formed (dot positions where image dots are formed, or dot positions corresponding to thinned-out dot elements and where pre-ejection dots are formed) The ratio of the total number of becomes larger. As a result, compared to the area where the thinning rate is lower than the thinning rate of the thinning pattern data, the image density of the formed image is further increased, and the image quality of the image is greatly different due to a large difference in the image density of each other area. May be reduced.

  Therefore, in the preliminary ejection dot position determination process of this modification, as shown in FIG. 8, in the unit area centered on the dot position corresponding to a certain thinned dot element in the changed ejection data, the unit area is thinned out. If the value obtained by subtracting the thinning rate (50% in this embodiment) of the thinning pattern data from the ratio is equal to or greater than a predetermined value (10% in this embodiment), the dot position corresponding to the certain thinning dot element Is not determined as the preliminary ejection dot position.

Hereinafter, the preliminary ejection dot position determination process according to this modification will be described with reference to FIG.
First, in the attention dot element row, the CPU 31 corresponds to a thinning dot element that is not yet set as a attention thinning dot element among thinning dot elements existing between the attention ejection dot element and the specific dot element. The thinned dot element whose dot position to be moved is the most downstream in the carrying direction is set as a focused thinned dot element (B1). Then, the CPU 31 provisionally determines the dot position corresponding to this noticed thinning dot element as the preliminary ejection dot position (B2). Next, the thinning ratio of the unit area centered on the dot position corresponding to the noticed thinning dot element (in this embodiment, a 3 × 3 area centered on the dot position corresponding to the noticeable thinning dot element) Is calculated (B3). Then, the CPU 31 determines whether or not the value obtained by subtracting the thinning rate of the thinning pattern data from the calculated thinning rate is equal to or greater than a predetermined value (B4). If it is determined that it is less than the predetermined value (B4: NO), the CPU 31 formally determines the preliminary ejection dot position provisionally determined in step B2 as the preliminary ejection dot position (B5), and ends this process. .

  On the other hand, if it is determined in step B4 that the value is equal to or greater than the predetermined value (B4: YES), the thinned dots that have not yet been set as the focused thinned dot element between the focused ejection dot element and the specific dot element. It is determined whether or not the element exists (B6). If it is determined that a thinned dot element exists (B6: YES), the CPU 31 returns to the process of step B1 and newly sets a focused thinned dot element.

  On the other hand, if it is determined in step B6 that there is no thinned dot element (B6: NO), the CPU 31 sets the preliminary ejection dot position as a dot position corresponding to a dot element other than the thinned dot element. Then, the dot position is changed to any one of the dot positions upstream of the dot position corresponding to the specific dot element (B7), and this process is terminated. The preliminary ejection dot position determination process according to this modification has been described above.

  As described above, according to the present modification, for the unit area in which the value obtained by subtracting the thinning rate of the thinning pattern data from the thinning ratio is equal to or larger than the predetermined value, the dot position corresponding to the thinning dot element in the unit area is reserved. Discharge dots are not formed. As a result, the change in image density of the image recorded on the paper P can be reduced, so that the image quality can be prevented from deteriorating.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. Is. For example, in the above-described embodiment, in the second preliminary ejection data generation process, when there are no ejection dot elements between the target ejection dot element and the specific dot element, and there are a plurality of thinning dot elements, The dot position corresponding to the thinned dot element corresponding to the dot position on the downstream side in the transport direction has been determined as the preliminary discharge dot position, but is not limited to this, and the target discharge dot element and the specific dot element A dot position corresponding to another thinned-out dot element between and may be determined as a preliminary ejection dot position.

Further, in the above-described embodiment, the first preliminary ejection data generation processing is performed based on the first image recording control processing after the previous ejection is performed when the non-ejection period is equal to or longer than the allowable range excess period. Until the next discharge, the first preliminary discharge data is generated so that the preliminary discharge is performed every preliminary discharge period. However, the first preliminary discharge data is not limited to this. That is, if the non-ejection period is less than the allowable range excess period, the preliminary ejection is performed at irregular intervals after the previous ejection until the next ejection of ink based on the first image recording control process. The discharge may be performed. In the second preliminary ejection data generation process, the second preliminary ejection is performed so that preliminary ejection is performed at irregular intervals between the time when the previous ejection is performed and the time when the ink based on the second image recording control process is next ejected. Discharge data may be generated.
In addition, the amount of ink ejected from the ejection port 10 of the head 1 within one printing cycle is four types, but is not particularly limited to this and may be two or more types. Further, it may be a head that discharges liquid other than ink.
In the above-described embodiment, the two ejection modes selected by the selection process are the first ejection mode and the second ejection mode. However, the present invention is not particularly limited to this. There may be three or more types of discharge modes with different amounts.

In the above-described embodiment, the changed ejection data generation processing is performed using the thinning pattern data. However, the present invention is not limited to this, and at least one ejection dot element in the ejection data is used as the thinning dot element. Any process that can generate changed changed ejection data may be used.
In the above-described embodiment, the line type ink jet printer that records an image with the head fixed is described. However, the present invention is a serial type that records an image by moving the head in the main scanning direction. It can also be applied to an ink jet printer. In this case, the dot element row of the ejection data includes a plurality of dot elements corresponding to a plurality of dot positions arranged along the moving direction of the head on the paper P, and a plurality of dot positions corresponding to the plurality of dot elements. They are arranged in the order according to the order of arrangement along the moving direction.

1 Inkjet head (liquid ejection head)
10 Discharge port 16 Transport mechanism (moving means)
33a Discharge data storage unit (Discharge data storage means)
100 Control device (control means)

Claims (7)

A liquid discharge head having a plurality of discharge ports for discharging liquid;
A moving means for relatively moving the recording medium and the liquid discharge head along a predetermined direction;
It is ejection data for recording an image on a recording medium, and a dot element row composed of a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction on the recording medium is represented by the plurality of ejection openings. Discharge data storage means for storing discharge data in which a plurality of liquid discharge amounts are set so as to correspond to each, and a discharge amount of liquid to be discharged at a corresponding dot position for each dot element is set;
Control means for controlling the liquid discharge head,
The control means includes
A selection process for selecting one discharge mode from the first discharge mode and at least two discharge modes of the second discharge mode in which the discharge amount of the liquid discharged from the plurality of discharge ports is smaller than that in the first discharge mode is executed. And
When the first discharge mode is selected by the selection process,
A first image recording control process for controlling the liquid ejection head based on the ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the first image recording control process, the plurality of the plurality of ejection ports are configured so that a non-ejection period from when the liquid is ejected to when the liquid is ejected next does not exceed a predetermined period. First preliminary discharge data generation processing for generating first preliminary discharge data related to preliminary discharge for discharging liquid from the discharge port based on the discharge data;
First controlling the liquid ejection head based on the first preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection openings. Pre-discharge control processing,
When the second discharge mode is selected by the selection process,
In the discharge data, a changed discharge in which at least one discharge dot element among the discharge dot elements whose discharge amount is larger than zero is changed to a thinned dot element whose discharge amount is set to zero Change discharge data generation processing for generating data,
A second image recording control process for controlling the liquid ejection head based on the changed ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the second image recording control process, the second preliminary ejection data related to the preliminary ejection is changed to the changed ejection data so that the non-ejection period does not exceed the predetermined period for each of the plurality of ejection ports. A second preliminary discharge data generation process generated based on the second preliminary discharge data generation process;
A second control unit that controls the liquid ejection head based on the second preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection ports. Pre-discharge control processing,
The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of discharge ports in the changed discharge data, a certain discharge dot element and the dot position corresponding to the certain discharge dot element are located downstream in the predetermined direction. The ejection dot element does not exist between the dot element corresponding to the dot position and the dot element that is the dot element having an interval corresponding to the predetermined period with the interval between the certain ejection dot element. And when there is at least one thinned dot element,
The second preliminary ejection data is generated so that the preliminary ejection dots are formed at the dot positions corresponding to at least one of the thinned dot elements between the certain ejection dot element and the specific dot element. A liquid discharge apparatus characterized by that. The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, the ejection dot element does not exist between the certain ejection dot element and the specific dot element, and the thinning is performed. If there are multiple dot elements,
Among the thinned dot elements between the certain discharge dot element and the specific dot element, the dot position corresponding to the thinned dot element having the largest discharge amount set in the discharge dot element before change The liquid ejection apparatus according to claim 1, wherein the second preliminary ejection data is generated so that the preliminary ejection dots are formed on the surface. The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, the ejection dot element does not exist between the certain ejection dot element and the specific dot element, and the thinning is performed. If there are multiple dot elements,
Among the thinned dot elements between the certain ejection dot element and the specific dot element, the spare dot position corresponding to the thinned dot element whose corresponding dot position is the most downstream in the predetermined direction is the spare. The liquid ejection apparatus according to claim 1, wherein the second preliminary ejection data is generated so that ejection dots are formed. In the changed ejection data generation process, the formation of the image dots in the ejection data is allowed based on thinning pattern data that determines whether or not the image dots are allowed to be formed at each dot position of the recording medium. A process of generating the changed ejection data by changing the ejection dot element corresponding to the dot position not to the thinned dot element;
The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of ejection openings in the changed ejection data, the ejection dot element does not exist between the certain ejection dot element and the specific dot element, and the thinning is performed. If there is a dot element,
An arbitrary thinning dot element between the certain ejection dot element and the specific dot element is set as a noticed thinning dot element, and the dot position of the recording medium corresponding to the noticed thinning dot element is set as a center. From the ratio of the total number of dot positions corresponding to the ejection dot elements in the changed ejection data to the total number of dot positions corresponding to the ejection dot elements in the ejection data in the area, the dots of the recording medium When a value obtained by subtracting the ratio of the total number of dot positions allowing the formation of the image dots in the thinning pattern data to the total number of positions is equal to or larger than a predetermined value, it corresponds to the focused thinning dot element. The second preliminary discharge data is generated so that the preliminary discharge dots are not formed at the dot positions. Re or liquid ejecting apparatus according to an item. The liquid discharge head has three or more discharge amounts of liquid that can be discharged to one dot position of the recording medium, including zero,
Each dot element of the ejection data is set to any one of the three or more types of liquid ejection amounts,
The second preliminary discharge control process includes
The liquid ejection head is controlled such that the preliminary ejection dots are formed by ejecting a liquid having the second smallest ejection amount from the ejection port to the dot position where the preliminary ejection dots are formed. The liquid discharge apparatus according to any one of claims 1 to 4. A liquid discharge head having a plurality of discharge ports for discharging liquid, a moving means for relatively moving the recording medium and the liquid discharge head along a predetermined direction, and discharge for recording an image on the recording medium Data, including a plurality of dot element arrays composed of a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction in the recording medium so as to correspond to each of the plurality of ejection openings, A discharge data storage means for storing discharge data in which a discharge amount of liquid to be discharged at a corresponding dot position for a dot element is stored, and a control method for a liquid discharge apparatus comprising:
A selection process of selecting one discharge mode from at least two discharge modes of a first discharge mode and a second discharge mode in which a discharge amount of liquid discharged from the plurality of discharge ports is smaller than that of the first discharge mode; ,
further,
When the first discharge mode is selected by the selection process,
A first image recording control process for controlling the liquid ejection head based on the ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the first image recording control process, the plurality of the plurality of ejection ports are configured so that a non-ejection period from when the liquid is ejected to when the liquid is ejected next does not exceed a predetermined period. First preliminary discharge data generation processing for generating first preliminary discharge data related to preliminary discharge for discharging liquid from the discharge port based on the discharge data;
First controlling the liquid ejection head based on the first preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection openings. Pre-discharge control processing,
When the second discharge mode is selected by the selection process,
In the discharge data, a changed discharge in which at least one discharge dot element among the discharge dot elements whose discharge amount is larger than zero is changed to a thinned dot element whose discharge amount is set to zero Change discharge data generation processing for generating data,
A second image recording control process for controlling the liquid ejection head based on the changed ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the second image recording control process, the second preliminary ejection data related to the preliminary ejection is changed to the changed ejection data so that the non-ejection period does not exceed the predetermined period for each of the plurality of ejection ports. A second preliminary discharge data generation process generated based on the second preliminary discharge data generation process;
A second control unit that controls the liquid ejection head based on the second preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection ports. Pre-discharge control processing,
The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of discharge ports in the changed discharge data, a certain discharge dot element and the dot position corresponding to the certain discharge dot element are located downstream in the predetermined direction. The ejection dot element does not exist between the dot element corresponding to the dot position and the dot element that is the dot element having an interval corresponding to the predetermined period with the interval between the certain ejection dot element. And when there is at least one thinned dot element,
The second preliminary ejection data is generated so that the preliminary ejection dots are formed at the dot positions corresponding to at least one of the thinned dot elements between the certain ejection dot element and the specific dot element. A control method for a liquid ejection apparatus. A liquid discharge head having a plurality of discharge ports for discharging liquid, a moving means for relatively moving the recording medium and the liquid discharge head along a predetermined direction, and discharge for recording an image on the recording medium Data, including a plurality of dot element arrays composed of a plurality of dot elements corresponding to a plurality of dot positions arranged along the predetermined direction in the recording medium so as to correspond to each of the plurality of ejection openings, A control program to be executed by a liquid discharge apparatus comprising: discharge data storage means for storing discharge data in which a discharge amount of liquid to be discharged at a corresponding dot position for a dot element is set;
One ejection mode is selected from at least two ejection modes of the first ejection mode and the second ejection mode in which the amount of liquid ejected from the plurality of ejection ports is smaller than that in the first ejection mode. To execute the selection process
further,
When the first discharge mode is selected by the selection process,
A first image recording control process for controlling the liquid ejection head based on the ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the first image recording control process, the plurality of the plurality of ejection ports are configured so that a non-ejection period from when the liquid is ejected to when the liquid is ejected next does not exceed a predetermined period. First preliminary discharge data generation processing for generating first preliminary discharge data related to preliminary discharge for discharging liquid from the discharge port based on the discharge data;
First controlling the liquid ejection head based on the first preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection openings. Pre-discharge control processing,
When the second discharge mode is selected by the selection process,
In the discharge data, a changed discharge in which at least one discharge dot element among the discharge dot elements whose discharge amount is larger than zero is changed to a thinned dot element whose discharge amount is set to zero Change discharge data generation processing for generating data,
A second image recording control process for controlling the liquid ejection head based on the changed ejection data so that the liquid ejected from the plurality of ejection ports lands and image dots are formed on a recording medium;
In the second image recording control process, the second preliminary ejection data related to the preliminary ejection is changed to the changed ejection data so that the non-ejection period does not exceed the predetermined period for each of the plurality of ejection ports. A second preliminary discharge data generation process generated based on the second preliminary discharge data generation process;
A second control unit that controls the liquid ejection head based on the second preliminary ejection data so that preliminary ejection dots are formed on a recording medium on which an image is recorded by landing of liquid ejected from the plurality of ejection ports. Pre-discharge control processing,
The second preliminary ejection data generation process includes:
For each dot element row corresponding to each of the plurality of discharge ports in the changed discharge data, a certain discharge dot element and the dot position corresponding to the certain discharge dot element are located downstream in the predetermined direction. The ejection dot element does not exist between the dot element corresponding to the dot position and the dot element that is the dot element having an interval corresponding to the predetermined period with the interval between the certain ejection dot element. And when there is at least one thinned dot element,
The second preliminary ejection data is generated so that the preliminary ejection dots are formed at the dot positions corresponding to at least one of the thinned dot elements between the certain ejection dot element and the specific dot element. A control program characterized by that.

Images