JP2016093964A - Liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of suppressing occurrence of deviation of a discharge position of droplets due to a fitting state of a head unit.SOLUTION: A liquid discharge device comprises: a head unit including a plurality of nozzles for discharging liquid as droplets; and a control section driving elements for discharging the liquid from the plurality of nozzles and causing the liquid to be discharged from the nozzles while moving the head unit in a first direction with respect to a discharged medium. Individual nozzles are disposed on the head unit such that positions where the liquid discharged from the individual nozzles lands on the discharged medium are disposed side-by-side in a second direction intersecting with the first direction and that the positions have variations set beforehand in a third direction perpendicular to the second direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid ejection apparatus.

  In recent years, head units of ink jet printers have been manufactured using a semiconductor process (for example, see Patent Document 1). Therefore, with the miniaturization and high accuracy of the semiconductor process, the density of nozzles for ejecting ink tends to increase, and the length of the nozzle row tends to increase.

JP 2012-96499 A

  When the length of the nozzle row is increased, the deviation of the landing position of the ink with respect to the print medium increases when the head unit is inclined with respect to the printer, and unevenness is likely to occur. Further, since the number of passes for printing the same area is reduced when the nozzle density is increased, it is difficult to reduce the influence of the deviation of the ink landing position by increasing the number of passes.

  In order to solve such a problem, for example, it is conceivable to correct the deviation of the landing position by controlling the ink ejection timing for each nozzle. Hardware that can adjust timing must be added, resulting in an increase in manufacturing cost. In addition, although it is possible to adjust the ejection timing of ink from each nozzle by image processing, the image processing cannot correct a positional shift of less than one pixel. Therefore, there is a need for a technique that can effectively suppress the occurrence of unevenness in the ink landing position. Such a problem is not limited to ink jet printers, but is a problem common to all liquid ejecting apparatuses capable of ejecting liquid.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a liquid ejection apparatus is provided. The liquid ejection apparatus includes: a head unit including a plurality of nozzles for ejecting liquid as droplets; and ejecting the liquid from the nozzles while moving the head unit in a first direction with respect to a medium to be ejected. A control unit that drives an element for causing the liquid to be discharged from the nozzle. In each of the nozzles, the position where the liquid ejected from each nozzle lands on the medium to be ejected is aligned in a second direction intersecting the first direction, and in the second direction. It arrange | positions at the said head unit so that it may have a predetermined dispersion | variation about the orthogonal | vertical 3rd direction. With such a liquid ejection device, it is possible to vary the landing positions of the liquid ejected from the nozzles, and therefore it is possible to effectively suppress the occurrence of unevenness in the landing positions of the liquid.

(2) In the liquid ejecting apparatus according to the above aspect, the variation is determined such that a landing position of the liquid from each nozzle in the third direction has a blue noise characteristic or a green noise characteristic in a frequency domain. It may be. If it is a liquid discharge device of such a form, it can control that unevenness arises more effectively.

(3) In the liquid ejection device according to the above aspect, the nozzles are arranged in the head unit so as to be aligned in the second direction, and the positions of the nozzles in the third direction have the variation. It may be arranged in the head unit so as to have. With such a configuration, it is possible to vary the landing positions of the liquid by varying the arrangement of the nozzles with respect to the head unit.

(4) In the liquid ejection device according to the above aspect, the nozzles may be formed on the same nozzle plate. With such a liquid ejection device, it is possible to effectively suppress unevenness in the liquid ejection position when the density of nozzles formed on the nozzle plate is high or the length of the nozzle row is long. can do.

  The present invention can be realized in various forms other than the form as a liquid ejection apparatus. For example, the present invention can be realized in the form of a method in which the liquid ejecting apparatus ejects liquid or a computer program for controlling the liquid ejecting apparatus.

FIG. 2 is an explanatory diagram illustrating a schematic configuration of a printer. It is a figure which shows schematic structure of a discharge unit. It is a figure which shows typically arrangement | positioning of the nozzle of a comparative example and embodiment. It is a figure which shows a mode that printing is performed in a comparative example. It is a figure which shows the formation position of the dot in a comparative example. It is a figure which shows the formation position of the dot in 1st Example. It is a figure which shows the formation position of the dot in 2nd Example. It is a figure which shows the position shift of an arch-shaped dot. It is a figure which shows the nozzle arrangement | positioning by which one nozzle row is comprised by four rows.

A. Embodiment:
FIG. 1 is an explanatory diagram illustrating a schematic configuration of a printer 10 as a liquid ejection apparatus according to an embodiment of the present invention. The printer 10 of this embodiment is a serial inkjet printer. The printer 10 includes a control unit 30, a head unit 90, and a transport mechanism 70.

  The control unit 30 is connected to a memory card slot 38 in which the memory card MC is inserted and an operation panel 39 for performing operations necessary for the printer 10. Inside the control unit 30, a CPU 40, a ROM 51, a RAM 52, and an EEPROM 60 are provided. The CPU 40, the ROM 51, the RAM 52, and the EEPROM 60 are connected to each other via a bus. The control unit 30 functions as a control unit that controls operations of the transport mechanism 70 and the head unit 90 of the printer 10 by developing a program stored in the ROM 51 and the EEPROM 60 in the RAM 52 and executing the program by the CPU 40.

  The CPU 40 functions as an image data acquisition unit 41, a halftone processing unit 42, and an ejection control unit 43. The image data acquisition unit 41 acquires image data from the memory card MC inserted in the memory card slot 38. The halftone processing unit 42 performs halftone processing on the image data using the dither mask 62 stored in the EEPROM 60. The ejection control unit 43 drives the piezoelectric element 410 (FIG. 2) provided in the head unit 90 based on the halftone processed image data, and controls the ejection of ink from the nozzles 451. At least a part of these functions realized by the CPU 40 may be realized by an electric circuit included in the control unit 30 operating based on the circuit configuration. The image data acquisition unit 41 may acquire image data not only through the memory card MC but also through a computer or network connected to the printer 10.

  The transport mechanism 70 performs transport of the head unit 90 and transport of the recording medium RM as an ejection target medium based on the control from the control unit 30. The head unit 90 is mounted on a carriage 80, and the carriage 80 is slidably attached to the scanning guide 73. When the carriage motor 77 rotates, the rotation is transmitted to the carriage 80 by an endless belt 71 stretched between the carriage 72 and the carriage 80 is reciprocated along the scanning guide 73 in the main scanning direction. The transport mechanism 70 is provided with a medium feed motor 74. The rotation of the medium feed motor 74 is transmitted to the platen 75 and a medium transport roller (not shown). As the platen 75 and the medium transport roller rotate, the recording medium RM is transported in the sub-scanning direction.

  The carriage 80 is mounted with ink storage portions 82 to 85 that store cyan ink C, magenta ink M, yellow ink Y, and black ink K, respectively. The head unit 90 is supplied with ink of each color from these ink storage portions 82 to 85. The number of ink colors and color types can be variously modified. The head unit 90 has a plurality of nozzles 451 on the surface facing the platen 75. Each nozzle 451 is arranged in the head unit 90 along the conveyance direction (sub-scanning direction) of the recording medium RM, and the cyan nozzle row 92, the magenta nozzle row 93, the yellow nozzle row 94, and the black nozzle row 95. Respectively. The printer 10 according to the present embodiment reciprocates (referred to as main scanning) the head unit 90 including the nozzle rows 92 to 95 of the respective colors along the platen 75 and ejects ink from the nozzles 451 in accordance with the main scanning. And print.

  FIG. 2 is a diagram illustrating a schematic configuration of the discharge unit 400 provided in the head unit 90. One discharge unit 400 is provided in the head unit 90 for each nozzle. The discharge unit 400 includes a piezoelectric element 410, a vibration plate 421, a cavity (pressure chamber) 431, a reservoir 441, and a nozzle 451. Ink reservoirs 82 to 85 corresponding to the ejection unit 400 are connected to the reservoir 441. The vibration plate 421 is deformed (bending vibration) by the piezoelectric element 410 provided on the upper surface in the drawing, and functions as a diaphragm that expands / contracts the internal volume of the cavity 431 filled with ink, that is, expands / contracts the cavity 431. . The nozzle 451 is an opening that communicates with the cavity 431. The plurality of nozzles 451 constituting each of the nozzle rows 92 to 95 are formed on the same nozzle plate 432 made of silicon by using a semiconductor process.

  The piezoelectric element 410 shown in FIG. 2 is generally called a unimorph (monomorph) type, and has a structure in which a piezoelectric body 411 is sandwiched between a pair of electrodes 412 and 413. In the piezoelectric body 411 having this structure, the central portion in the drawing, along with the electrodes 412 and 413 and the vibration plate 421, bends vertically with respect to both end portions in accordance with the voltage applied between the electrodes 412 and 413. . Specifically, the piezoelectric element 410 is configured to bend upward when the voltage of the drive signal output from the control unit 30 is high, and bend downward when the voltage is low. In this configuration, since the cavity 431 expands when bent upward, the ink is drawn into the cavity 431 from the reservoir 441, while the cavity 431 contracts when bent downward, depending on the degree of contraction. Ink is ejected as droplets from the nozzle 451. Note that the piezoelectric element 410 is not limited to a unimorph type, and may be any type such as a bimorph type or a laminated type that can deform the piezoelectric element 410 and discharge a liquid such as ink. The piezoelectric element 410 is not limited to bending vibration, and may be configured to use longitudinal vibration.

  FIG. 3 is a diagram schematically illustrating the nozzle arrangement of the comparative example and the embodiment. Since all of the nozzle arrays 92 to 95 have the same nozzle arrangement, the nozzle arrangement of the black nozzle array 95 will be described below as a representative example. FIG. 3A shows a comparative example of the arrangement of the nozzles 451. FIG. 3B shows the arrangement of the nozzles 451 in the present embodiment. In the comparative example shown in FIG. 3A, the nozzles 451 are arranged at equal intervals p in the sub-scanning direction. The positions of the nozzles 451 in the main scanning direction are all the same. On the other hand, in the embodiment shown in FIG. 3B, the head unit 90 is attached to be inclined with respect to the carriage 80, so that each nozzle 451 is inclined by a predetermined angle with respect to the sub-scanning direction. Arranged along a second direction intersecting the main scanning direction (first direction). The nozzles 451 are arranged at equal intervals in the second direction, but a predetermined variation is given to the positions of the nozzles 451 in the third direction orthogonal to the second direction. . In this embodiment, this variation has a predetermined frequency characteristic in the spatial frequency domain. Specifically, the variation is determined so that each position of each nozzle 451 in the third direction has a blue noise characteristic in the frequency domain. That is, the frequency characteristic when the position of the nozzle 451 in the second direction is input and the position of the nozzle 451 in the third direction is output is the blue noise characteristic. The blue noise characteristic is a noise characteristic mainly composed of a high-frequency component that has a small amount of low-frequency components whose position changes gently and changes finely. Note that the second direction is, for example, a direction parallel to one side of the nozzle plate 432 in which the nozzle row 95 is formed.

  FIG. 4 is a diagram illustrating a state in which printing is performed by the nozzle row 95 having the nozzle arrangement of the comparative example described above. FIG. 4A schematically shows how the nozzle row 95 moves relatively in the sub-scanning direction. The numbers shown at the top of FIG. 4A are main scanning numbers representing the order of main scanning. As shown in FIG. 4A, in this comparative example, 30 nozzles 451 are arranged in the nozzle row 95, and the interval (pitch) of each nozzle 451 in the sub-scanning direction is 300 npi (number of nozzles / inch). ). In this comparative example, a dot of 300 × 300 dpi (number of dots / inch) is formed by one main scanning in the main scanning direction of the head unit 90, and the recording medium is transported once in the sub scanning direction. That is, the relative movement amount of the head unit 90 in the sub-scanning direction is 15/600 inches. Then, printing is performed on the print medium at an output resolution of 600 × 600 dpi by performing four main scans with three sub-scan feeds in between in the same area on the recording medium. The printing conditions such as the number, pitch, and output resolution of the nozzles 451 are the same in the first and second embodiments described later.

  FIG. 4B shows 16 columns of dots formed on the recording medium when all the pixels are black image data. In this comparative example and the examples described later, even-numbered dots are formed at main scanning numbers 3 and 4, and odd-numbered dots are formed at main scanning numbers 5 and 6. That is, in this comparative example and the examples described later, the positions of the columns forming the dots are switched every two passes (every two main scans). 4B, column numbers are counted as column 1, column 2, column 3... In the right direction with the left end as column 0 (even). In FIG. 4B, in order to make it easier to understand the relationship between the number of main scans and the positions of the dots to be formed, the left half of 8 rows of 16 rows is formed by the 15th nozzle. In the right half of the eight columns, the dots formed by the main scanning number 3 are shown in white. In this comparative example, since the head unit 90 is appropriately attached to the carriage 80 and the nozzles 451 are arranged in a straight line, dots are regularly formed on the recording medium as shown in FIG.

  FIG. 5 is a diagram illustrating the positions of dots formed on the recording medium when the nozzle array 95 having the nozzle arrangement of the comparative example described above is inclined with respect to the sub-scanning direction. FIG. 5A shows the arrangement of the nozzles, and the 15th nozzle is shown in gray. 5B to 5F show the dot formation positions when the nozzle array 95 is tilted from 0 degree to 2 degrees with respect to the sub-scanning direction in the nozzle arrangement of FIG. Shown at every degree. In FIGS. 5B to 5F, for the 0th and 1st dot rows, the dots formed by the 15th nozzle are shown in gray.

  As shown in FIGS. 5C to 5F, in the nozzle row 95 having the nozzle arrangement of the comparative example, when the nozzle row 95 is inclined with respect to the sub-scanning direction, the sub-scan feed amount of the head unit 90. The overlapping state of dots changes greatly in units, and horizontal stripe-shaped density unevenness occurs at a cycle that is an integral multiple of the sub-scan feed amount. That is, when there is no variation in the position of the nozzle 451 in the third direction (when the variation width is 0) as in the nozzle arrangement of the comparative example, the mounting state of the head unit 90 with respect to the carriage 80 is large in print image quality. Will have an impact.

  FIG. 6 is a diagram showing dot formation positions in the first embodiment. FIG. 6A shows the arrangement of the nozzles 451 in the first embodiment. In the first embodiment, in the third direction, the distance between the centers of the two nozzles 451 located at the farthest positions corresponds to a distance of 0.5 pixels in the output resolution. The positions of the nozzles 451 in the third direction are arranged so as to vary according to the blue noise characteristics. 6B to 6F show the dot formation positions when the nozzle array 95 is tilted from 0 degree to 2 degrees with respect to the sub-scanning direction in the nozzle arrangement shown in FIG. 6A. Shown every 5 degrees.

  FIG. 7 is a diagram showing dot formation positions in the second embodiment. FIG. 7A shows the arrangement of the nozzles 451 in the second embodiment. In the second embodiment, the distance between the centers of the two nozzles 451 located at the farthest positions in the third direction corresponds to the distance of one pixel in the output resolution, and each nozzle 451 in the distance range. The positions in the third direction are arranged so as to vary according to the blue noise characteristics. 7B to 7F show the dot formation positions when the nozzle array 95 is tilted from 0 degree to 2 degrees with respect to the sub-scanning direction in the nozzle arrangement shown in FIG. 7A. Shown every 5 degrees.

  As shown in FIGS. 6 and 7, in the first and second embodiments, the clear density change for each sub-scan feed is less noticeable than in the comparative example shown in FIG. There have been significant improvements. This is because the way in which dots overlap is changed randomly for each raster by giving the blue noise characteristic to the variation in the nozzle position in the third direction. Therefore, according to the above-described embodiment, it is possible to suppress the dot overlapping method from changing at a low frequency in the sub-scanning direction, and to reduce occurrence of unevenness in the ink landing position. As a result, it is possible to greatly suppress the deterioration of the print image quality due to the case where the head unit 90 is mounted inclined with respect to the sub-scanning direction.

  In the above embodiment, since each nozzle 451 is formed on the nozzle plate 432 using a semiconductor process, the nozzle density tends to increase and the length of the nozzle row tends to increase. For example, in FIGS. 5 to 7, for convenience of explanation, the number of nozzles is 30, but in general, the nozzle row includes tens to hundreds of nozzles. Therefore, when the head unit 90 is tilted and attached to the carriage 80, the positions at which dots are formed are greatly shifted at both ends of the nozzle row. However, in the above embodiment, since the positions of the nozzles 451 in the third direction are varied, even if the nozzle density is high and the length of the nozzle row is long, depending on the mounting state of the head unit 90. It is possible to effectively suppress a decrease in print image quality. In the above-described embodiment, each nozzle 451 is formed on the same nozzle plate 432 by a semiconductor process, so that each nozzle 451 can be accurately formed at a position that has been dispersed in advance.

  The human eye is most sensitive to shading unevenness with a cycle of about 1 cycle / mm when the observation distance is 30 cm, but the sensitivity decreases with increasing frequency, and shading unevenness can be recognized at 10 cycles / mm or more. It has the characteristic of disappearing. Therefore, it is preferable that the variation in nozzle position has a frequency characteristic such that a high frequency component of 3 cycles / mm or more is mainly used. As such frequency characteristics, the blue noise characteristics are applied in the above embodiment. Further, when the same region is formed by a plurality of main scanning passes as in the above-described embodiment, it is possible that unevenness of a low frequency may occur due to interference of a plurality of passes by giving blue noise characteristics to variations in nozzle positions. Can also be reduced.

  As shown in FIG. 6, the variation width of the nozzle position can be sufficiently improved even with 0.5 pixels. However, as shown in FIG. However, if the variation width is excessively widened, the graininess of the dots may be deteriorated or the vertical ruled lines may be disturbed. Therefore, the variation width is preferably 0.2 pixels or more, and more preferably in the range of 0.5 pixels to 1 pixel. If it is an actual distance range, it is preferable that the position of each nozzle 451 is varied within a range of plus or minus 100 μm.

  Further, the deviation amount of each nozzle 451 within the above-described variation width may not be a continuous value. That is, any one of a plurality of predetermined deviation amounts may be applied to the position of each nozzle 451. For example, when the variation width is 0.75 pixels, one of the four shift amounts of 0, 0.25, 0.5, and 0.75 is set for each nozzle. Can be given. For example, two variations of the deviation amount may be 0 and 0.5, but it is desirable to use three or more deviation amounts in order to enhance the effect.

B. Variations:
<Modification 1>
In the above embodiment, it is assumed that the head unit 90 is tilted with respect to the sub-scanning direction in a state parallel to the recording medium. However, the distance to the recording medium is different between the front end and the rear end of the nozzle row. That is, even when the head unit 90 is attached to the carriage 80 so that the head unit 90 is not parallel to the recording medium RM, the positional deviation of dots occurs as in FIGS. This is because a nozzle that is far from the recording medium has a longer time until the ink lands on the recording medium than a nozzle that is short from the recording medium, and the amount of deviation in the main scanning direction is large. Therefore, even when the head unit 90 is attached to the carriage 80 so that the head unit 90 is not parallel to the recording medium, density unevenness occurs if the positions of the nozzles are varied as in the above embodiment. This can be suppressed. In the recording mode in which dots are recorded both in the forward movement and in the backward movement in the main scanning direction, when the head unit 90 is attached to the carriage 80 so as to be non-parallel to the recording medium, the scanning direction Depending on, the direction of dot displacement is reversed. However, even in this case, unevenness occurs at a cycle that is an integral multiple of the sub-scan feed amount, similar to the unevenness due to the inclination in the above embodiment. Therefore, even in such a recording mode, giving a variation in the position of the nozzle in the third direction exhibits the same effect as in the above embodiment.

<Modification 2>
FIG. 8 is a diagram showing the positional deviation of arched dots. 8A shows the arrangement of the nozzles 451, and FIG. 8B shows one row of dots formed on the recording medium by the nozzles shown in FIG. 8A. When the ink ejection speed differs between the nozzles near the center of the nozzle row and the nozzles near both ends due to the structure of the head unit 90, the nozzles 451 are arranged in one row as shown in FIG. Even if they are lined up, dots may be formed in an arch shape as shown in FIG. Even in the case where such a positional deviation occurs, it is possible to effectively suppress the occurrence of density unevenness if the positions of the nozzles are varied as in the above embodiment. It is. FIG. 8 shows an example in which the positional deviation of dots occurs in an arch shape. However, the position of the dots in the third direction is not limited to the arch shape, and according to the position of the nozzle in the second direction. The same applies to various misalignments that change gradually.

<Modification 3>
FIG. 9 shows a nozzle arrangement in which one nozzle row is constituted by four rows. FIG. 9 shows the positions of four rows of nozzles on a grid with an interval of 1/600 inch so that the positions of the nozzles 451 can be easily understood. The distance between the columns shown in FIG. 9 is an integer multiple of one pixel in the output resolution. Even in such a nozzle arrangement, it is effective to provide variation in the position of each nozzle as in the above embodiment. In this case, the position of each nozzle varies so that the respective deviations (differences) from the position of each nozzle shown in FIG. 9 (that is, the ideal position) to the actual nozzle position become blue noise characteristics. Give it. The same idea can be applied not only when the nozzle row is composed of four rows but also when one nozzle row is composed of two or more rows, for example, in a staggered manner. It is.

<Modification 4>
In the above embodiment, the variation in the position of each nozzle in the third direction has the blue noise characteristic, but it may have the green noise characteristic. The green noise characteristic is a noise characteristic having the largest frequency component on a slightly lower frequency side than the blue noise characteristic. Even with the green noise characteristics, since low frequency components are reduced due to variations in the positions of the respective nozzles, it is possible to suppress the occurrence of density unevenness as in the above embodiment.

<Modification 5>
In the above embodiment, the nozzles 451 are arranged in the head unit 90 so as to be aligned in the second direction, and the nozzles 451 are arranged in the head unit 90 so that the positions in the third direction vary. That is, the ink landing positions are varied by varying the arrangement of the nozzles 451 with respect to the head unit 90. However, the arrangement of the nozzles 451 with respect to the head unit 90 may be in any form as long as the position of the ink that has landed on the recording medium is aligned in the second direction and varies in the third direction. For example, each nozzle 451 may be arranged in the head unit 90 in a straight line as in the comparative example. Even when each nozzle 451 is arranged in a straight line, it is possible to vary the position of the ink that lands on the recording medium by changing the ink ejection direction of each nozzle 451. In addition, as long as density unevenness can be suppressed, the arrangement of the nozzles 451 in the second direction or the arrangement of the ink landed on the recording medium in the second direction may not be equally spaced.

<Modification 6>
In the above embodiment, in the so-called serial type printer 10 in which the head unit 90 moves in the main scanning direction to perform printing, the positions of the nozzles vary, but the width direction of the recording medium (the main scanning in the above embodiment) In the line printer in which the nozzles are arranged in the direction), the positions of the nozzles may vary. In the case of a line printer, the recording medium conveyance direction corresponds to the first direction, and the direction that intersects the first direction and the nozzles are arranged at equal intervals corresponds to the second direction. The direction orthogonal to the second direction corresponds to a third direction that gives position variations. The line printer is not limited to a configuration in which all the nozzles are arranged in a row, but is a configuration in which small head units in which a plurality of nozzles are arranged are alternately arranged in a plurality of rows along the width direction of the recording medium. May be. With such a configuration, it is possible to suppress the occurrence of uneven density depending on the mounting state of each head unit.

<Modification 7>
The present invention is not limited to a printer that ejects ink by driving a piezoelectric element, but can also be applied to a printer that ejects ink by driving another element such as a heating element.

<Modification 8>
In the above-described embodiment, a printer has been described as an example of a liquid ejection device. However, the present invention is not limited to a printer and can be applied to various devices as long as the device can eject liquid. For example, an apparatus equipped with a color material ejection head such as a liquid crystal display, an apparatus equipped with an electrode material (conductive paste) ejection head used for forming an electrode such as an organic EL display or a surface emitting display (FED), and a biochip manufacturing The present invention can be applied to an apparatus including a bio-organic matter ejecting head, a device including a sample ejecting head as a precision pipette, a liquid ejecting apparatus such as a printing apparatus and a microdispenser.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Printer 30 ... Control unit 38 ... Memory card slot 39 ... Operation panel 40 ... CPU
DESCRIPTION OF SYMBOLS 41 ... Image data acquisition part 42 ... Halftone process part 43 ... Discharge control part 62 ... Dither mask 70 ... Conveyance mechanism 71 ... Endless belt 72 ... Pulley 73 ... Scanning guide 74 ... Motor 75 ... Platen 77 ... Carriage motor 80 ... Carriage 82 ... Ink container 90 ... Head unit 92 ... Cyan nozzle row 93 ... Magenta nozzle row 94 ... Yellow nozzle row 95 ... Black nozzle row 400 ... Discharge unit 410 ... Piezoelectric element 411 ... Piezoelectric elements 412 and 413 ... Electrode 421 ... Vibration plate 431 ... Cavity 432 ... Nozzle plate 441 ... Reservoir 451 ... Nozzle MC ... Memory card RM ... Recording medium

Claims (4)

A head unit including a plurality of nozzles for discharging liquid as droplets;
A control unit for driving the element for discharging the liquid from the nozzle and discharging the liquid from the nozzle while moving the head unit in the first direction with respect to the discharge target medium;
With
In each of the nozzles, the position where the liquid ejected from each nozzle lands on the medium to be ejected is aligned in a second direction intersecting the first direction and orthogonal to the second direction. Arranged in the head unit so as to have a predetermined variation in the third direction,
Liquid ejection device. The liquid ejection device according to claim 1,
The variation is a liquid ejection apparatus in which the landing position of the liquid from the nozzles in the third direction is determined to have a blue noise characteristic or a green noise characteristic in a frequency domain. The liquid ejection device according to claim 1 or 2, wherein
The nozzles are arranged in the head unit so as to be aligned in the second direction, and are arranged in the head unit so that the positions of the nozzles in the third direction have the variation. Yes,
Liquid ejection device. The liquid ejection apparatus according to any one of claims 1 to 3, wherein:
A liquid ejection apparatus, wherein each of the nozzles is formed on the same nozzle plate.

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