CN101391533A - Liquid ejection device and scanning line forming method - Google Patents

Abstract

A liquid ejecting device and a scanning line forming method. Equipped with: a head unit, which has a plurality of nozzles arranged in the first direction along the first direction and a plurality of nozzles for ejecting liquid to the medium, relatively moves relative to the medium in a second direction intersecting with the first direction, and ejects the liquid , the width of the head unit in the first direction is greater than the width of the medium in the first direction; the moving mechanism causes the head unit to move relative to the medium alternately multiple times in the second direction and the first direction; and the control section makes the The head unit moves relative to the medium alternately multiple times in the second direction and the first direction, and makes two or more different nozzles eject liquid respectively to form each scanning line to form a scanning line group, and performs multiple relative movements according to the head unit When the total movement amount in the first direction is smaller than the effective nozzle width in the first direction of one head, the head unit is relatively moved by the moving mechanism. Accordingly, it is possible to suppress the width of the head unit in the first direction from becoming large and to suppress deterioration of image quality.

Description

Liquid ejection device and scanning line forming method

technical field

The present invention relates to a liquid ejecting device and a raster line forming method.

Background technique

As one type of liquid ejection device, there is known an inkjet printer that ejects liquid (ink) onto various media such as paper, cloth, and film to perform printing. This printer includes a head in which a plurality of nozzles for ejecting liquid onto a medium are arranged in a first direction (sub-scanning direction), and the head moves in a second direction (main scanning direction) intersecting the first direction. One side squirts liquid.

From the viewpoint of improving image quality, the printers described above perform, for example, so-called overlap printing. That is, the printer moves the head alternately multiple times in the second direction and the first direction, and ejects liquid from two or more different nozzles to form one scanning line.

Patent Document 1: Publication of International Publication No. 01/03930

However, from the viewpoint of speeding up printing, a printer includes a head unit having a plurality of the above-mentioned heads along the first direction. In this case, for example, it is conceivable to make the width of the head unit in the first direction larger than the width of the medium in the first direction in order to discharge the liquid to the entire width of the medium at once. However, in such a configuration, when the total amount of movement of the head unit in the first direction during printing is large, in order to eject the liquid to the entire area of the medium width at one time when moving in the second direction, it is necessary to increase the size of the head unit. The width of the cell in the first direction.

In addition, it is known that the ejection characteristics of the liquid vary depending on the individual differences of the heads. For example, one head has a characteristic of being easy to eject liquid, and the other head has a characteristic of being difficult to eject liquid. Therefore, when a plurality of heads constituting the head unit discharge liquid, so-called density unevenness occurs due to differences in discharge characteristics of the respective heads, and as a result, image quality may deteriorate.

Contents of the invention

The present invention has been made in view of this problem, and an object of the present invention is to prevent the width of the head unit from increasing in the first direction and to suppress deterioration of image quality.

In order to solve the above-mentioned problems, the present invention provides a liquid ejection device characterized in that it includes:

(a) a head unit having a plurality of heads arranged along the first direction in which a plurality of nozzles for ejecting liquid to the medium are arranged, and the medium is moved in a second direction intersecting the first direction with respect to the medium. move relatively, and eject the above-mentioned liquid,

The width of the head unit in the first direction is greater than the width of the medium in the first direction;

(b) a moving mechanism that moves the head unit relative to the medium alternately multiple times in the second direction and the first direction; and

(c) A control unit that uses the moving mechanism to move the head unit relative to the medium alternately multiple times in the second direction and the first direction, and causes two or more different nozzles to spray The above-mentioned liquid is formed to form each scanning line to form a scanning line group,

The head unit is relatively moved by the moving mechanism in such a manner that the total amount of movement of the head unit in the first direction when the head unit performs the plurality of relative movements is smaller than the effective nozzle width in the first direction of one head unit. move,

According to the number of the scanning lines formed by ejecting the liquid from the nozzles of only one head in the scanning line group, the scanning lines formed by ejecting the liquid from the nozzles of two or more heads In the following manner, the above-mentioned scan line groups are formed.

Other features of the present invention will be explained through the description of this specification and the accompanying drawings.

Description of drawings

FIG. 1 is a block diagram showing the overall configuration of a printer 1 .

FIG. 2A is a schematic sectional view of the printer 1 , and FIG. 2B is a schematic top view of the printer 1 .

FIG. 3 shows the arrangement of nozzles on the lower surface of the head unit 40 .

4A to 4I are schematic diagrams for explaining the movement state of the head unit 40 during printing.

5A and 5B are diagrams for explaining density unevenness due to differences in discharge characteristics of the respective heads 41 .

FIG. 6A shows the head unit 40 in the case of increasing the total sub-scanning amount. FIG. 6B shows the head unit 40 in the case of reducing the total sub-scanning amount.

FIG. 7 is a flowchart for explaining this printing process.

FIG. 8 is a diagram for explaining overlay printing according to this embodiment.

FIG. 9 is a diagram for explaining overlay printing according to this embodiment.

FIG. 10 shows a head unit 40 according to the second embodiment.

FIG. 11 is a diagram for explaining overlay printing according to the second embodiment.

FIG. 12 is a diagram for explaining overlay printing according to the third embodiment.

Explanation of symbols in the figure: 1...printer; 10...controller; 11...interface; 12...CPU; 13...memory; 14...unit control circuit; 20...transport unit ;21...Transfer roller; 22...Output roller; 23...Adsorption table; 30...Drive unit; 40...Head unit; 41...Head; 50...Detector group; 90...Computer.

Detailed ways

At least the following matters are clarified by the description of this specification and the accompanying drawings.

A liquid ejection device, characterized in that it comprises:

(a) a head unit having a plurality of heads arranged along the first direction in which a plurality of nozzles for ejecting liquid to the medium are arranged, and the medium is moved in a second direction intersecting the first direction with respect to the medium. move relatively, and eject the above-mentioned liquid,

The width of the head unit in the first direction is greater than the width of the medium in the first direction;

(b) a moving mechanism that moves the head unit relative to the medium alternately multiple times in the second direction and the first direction; and

(c) A control unit that uses the moving mechanism to move the head unit relative to the medium alternately multiple times in the second direction and the first direction, and causes two or more different nozzles to spray The above-mentioned liquid is formed to form each scanning line to form a scanning line group,

The head unit is relatively moved by the moving mechanism in such a manner that the total amount of movement of the head unit in the first direction when the head unit performs the plurality of relative movements is smaller than the effective nozzle width in the first direction of one head unit. move,

According to the number of the scanning lines formed by ejecting the liquid from the nozzles of only one head in the scanning line group, the scanning lines formed by ejecting the liquid from the nozzles of two or more heads In the following manner, the above-mentioned scan line groups are formed.

According to such a liquid ejection device, it is possible to suppress the width of the head unit in the first direction from becoming large, and to suppress deterioration of image quality.

Furthermore, preferably in the liquid ejection device,

When the number of times of movement of the head unit in the second direction when the head unit performs the plurality of relative movements is m times,

During the above-mentioned m times of movement, all the above-mentioned heads eject the above-mentioned liquid. In this case, it is possible to reduce the total movement amount of the head unit and form the scanning line group with the minimum number of heads.

And, preferably in the liquid ejection device,

When the number of times of movement of the head unit in the first direction when the head unit performs the plurality of relative movements is n times,

The respective movement amounts of the above-mentioned n times of movement have the same magnitude. In this case, degradation of image quality can be effectively suppressed.

In addition, the present invention provides a scanning line forming method,

(a) each scanning line group is formed by causing the head unit to move relative to the medium alternately multiple times in the second direction and the first direction, and two or more different nozzles respectively eject liquid to form each scanning line, Wherein, the head unit has a plurality of heads arranged in the first direction along the first direction with a plurality of nozzles for ejecting liquid to the medium, and faces the medium in a second direction intersecting the first direction. Move and eject the liquid, the width of the head unit in the first direction is greater than the width of the medium in the first direction, characterized in that,

(b) relatively moving the head unit so that the total amount of movement of the head unit in the first direction when the head unit performs the relative movement a plurality of times is smaller than the effective nozzle width in the first direction of one head unit ,

According to the number of the scanning lines formed by ejecting the liquid from the nozzles of only one head in the scanning line group, the scanning lines formed by ejecting the liquid from the nozzles of two or more heads In the following manner, the above-mentioned scan line groups are formed.

According to such a scanning line forming method, it is possible to suppress the width of the head unit in the first direction from increasing, and to suppress deterioration of image quality.

＝＝Inkjet Printer Configuration Example＝＝

An inkjet printer (hereinafter referred to as printer 1) as an example of a liquid ejection device uses a unit image to be cut and used later, such as a film-like printed matter attached to a plastic wrap of fresh food, by an inkjet method. Printing is performed on a tape T which is an example of a medium. Here, the printing tape T is a roll paper (continuous paper) with release paper, and images as printed matter can be continuously printed in the direction in which the printing tape T continues.

<Configuration of printer 1>

FIG. 1 is a block diagram of the overall configuration of a printer 1 . FIG. 2A is a schematic sectional view of the printer 1 , and FIG. 2B is a schematic top view of the printer 1 . FIG. 3 shows the arrangement of nozzles on the lower surface of the head unit 40 .

When the printer 1 receives print data, the controller 10 as an example of a control unit controls each unit (transport unit 20 , drive unit 30 , head unit 40 ) to form an image on the printing tape T. In addition, the condition inside the printer 1 is monitored by the detector group 50, and the controller 10 controls each unit based on the detection result.

The transport unit 20 transports the printing tape T from the upstream side to the downstream side in the direction in which the printing tape T continues (hereinafter referred to as the transporting direction). This transport unit 20 has a transport roller 21, a delivery roller 22, an adsorption table 23, and the like. The transport roller 21 transports the unprinted roll-shaped printing tape T to the suction table 23 serving as a printing area. The suction table 23 vacuum-suctions the printing tape T from below to hold the printing tape T. The output roller 22 outputs the printed printing tape T from the printing area. The printing tape T output from the printing area is wound into a roll by a winding mechanism.

The drive unit 30 is a movement mechanism that freely moves the head unit 40 in the main scanning direction corresponding to the conveyance direction and in the sub scanning direction corresponding to the width direction of the printing tape T. The drive unit 30 is constituted by, for example, an X movable stage for moving the head unit 40 in the main scanning direction, a Y movable stage for moving the X movable stage holding the head unit 40 in the sub-scanning direction, and a motor for moving them (not shown). icon).

Dot columns (scanning lines) are formed on the printing table T by the head unit 40 moving in the main scanning direction and ejecting ink. Since the accumulation of this dot row forms an image, an image is printed by forming the dot row. The head unit 40 has ten heads 41 arranged in a zigzag manner in the width direction (sub-scanning direction). Moreover, ink can be ejected across the entire width of the printing tape T by moving the head unit 40 once in the main scanning direction, that is, the width of the head unit 40 in the sub-scanning direction is larger than the width of the printing tape T. , to configure 10 headers.

Also, formed on the lower surface of each head 41 are a nozzle row Y that ejects yellow ink, a nozzle row M that ejects magenta ink, a nozzle row C that ejects cyan ink, and a nozzle row K that ejects black ink. In each nozzle row, 360 nozzles are arranged at predetermined intervals (360 dpi) in the width direction. Furthermore, among the two adjacent heads in the width direction (here, head 41(1) and head 41(2) will be described as examples), the two nozzles on the frontmost side of head 41(1) on the rear side #359, #360, and the innermost nozzles #1 and #2 of the head 41 (2) on the front side are located on the same line (that is, the nozzles overlap). In addition, in this embodiment, the sub-scanning direction corresponds to the first direction, and the main scanning direction corresponds to the second direction.

<Movement state of head unit 40 at the time of printing>

4A to 4I are schematic diagrams for explaining the movement state of the head unit 40 during printing. The printer 1 forms each dot column (scanning line) by moving the head unit 40 four times in the main scanning direction. In addition, during printing, the printing tape T is held on the suction table 23 without being conveyed.

The head unit 40 before printing is on standby at a home position (position shown in FIG. 4A ). At the time of printing, first the head unit 40 is moved from the downstream side to the upstream side in the main scanning direction by the driving of the driving unit 30 ( FIG. 4B ). In this movement (pass 1), ink is ejected from each nozzle of the head unit 40 across the entire width of the printing tape T, and a dot row of pass 1 is formed on the printing tape T. The head unit 40 after moving in the main scanning direction moves from the inner side to the near side in the sub-scanning direction by the drive of the driving unit 30 ( FIG. 4C ), and then the head unit 40 moves from the upstream side in the main scanning direction again. The downstream side moves (stroke 2) (FIG. 4D), and ink is ejected from the nozzles across the entire width of the printing tape T at the same time to form the dot row of the stroke 2. Here, "stroke" means that the head unit 40 moves once in the main scanning direction, and the numbers following the stroke indicate the order in which the stroke is performed.

In this way, the head unit 40 alternately performs movement in the main scanning direction of the head unit 40 for forming dots (FIG. 4B, FIG. 4D, FIG. 4F, and FIG. 4H), and movement in the sub-scanning direction of the head unit 40 (FIG. Figure 4E, Figure 4G). As a result, a plurality of dot columns (scanning line groups) are formed over the entire width of the printing tape T. Moreover, after the head unit 40 finishes moving in the main scanning direction for the fourth time (stroke 4, FIG. 4H ), it moves toward the rear side in the sub-scanning direction ( FIG. 4I ), thereby being located at the home position shown in FIG. 4A . . Thereby, the series of movements of the head unit 40 at the time of printing is completed.

== Density unevenness due to the difference in discharge characteristics of each head 41 ==

It is known that the ejection characteristics of ink differ due to individual differences of the heads 41 . For example, ink may be easily ejected from the nozzles of a certain head 41 , whereas it may be difficult to eject ink from the nozzles of another head 41 . Therefore, when printing is performed by the head unit 40 having ten heads 41 having individual differences, so-called density unevenness due to the difference in discharge characteristics of the heads 41 occurs.

Here, among the ten heads 41 , head 41 ( 3 ), head 41 ( 4 ), and head 41 ( 5 ) will be described as examples. Assuming that the head 41(3) has the characteristic of being difficult to eject ink (the ejection amount of ink is less than an appropriate amount), and the head 41(4) has the characteristic of normally ejecting ink (the ejection amount of ink is appropriate), the head 41 (5) It has the characteristic of being easy to eject ink (the ejection amount of ink is more than the appropriate amount). Therefore, assuming that when it is necessary to form a dot with an appropriate discharge amount (hereinafter referred to as a mid-point), the head 41 (3) forms a dot with a discharge amount less than the appropriate amount (hereinafter referred to as a small dot), and the head 41 (4) forms midpoint, and the head 41 (5) forms a dot (hereinafter referred to as a large dot) whose ejection amount is more than an appropriate amount. In addition, it is assumed that most of the other heads 41 among the ten heads 41 form a midpoint similarly to the head 41 (4).

5A and 5B are diagrams for explaining density unevenness due to differences in discharge characteristics of the respective heads 41 . The dot row shown in FIGS. 5A and 5B is a dot row formed by two strokes. FIG. 5A shows the dot row after the stroke 1, and FIG. 5B shows the dot row after the stroke 2.

In the first row of five dot rows, run 1 and run 2 are formed by head 41(3). Therefore, in the first dot column, only small dots are arranged. In the second column, run 1 is made by head 41(3) and run 2 is made by head 41(4). Therefore, in the second dot column, small dots and mid-dots are alternately arranged. In the third row of dots, run 1 and run 2 are formed by the head 41(4), so only the midpoints are arranged. In the fourth column of dots, run 1 is formed by heads 41(4) and run 2 by heads 41(5), so that medium and large dots are alternately arranged. In the fifth dot column, run 1 and run 2 are formed by the head 41 (5), so only large dots are arranged.

In this case, the first dot row is formed of only small dots, and therefore looks lighter compared to the dot row formed of mid-points (dots with an appropriate ejection amount). That is, it can be recognized as density unevenness. Likewise, the fifth column of dots is formed only from large dots and therefore appears denser compared to the column of dots formed from midpoints. That is, it can be recognized as density unevenness. Furthermore, when the numbers of the first dot row and the fifth dot row increase, density unevenness becomes conspicuous, resulting in further degradation of image quality.

On the other hand, since the third column of dots is formed of only midpoints, it is an appropriate concentration. In addition, since half of the second and fourth dot rows are centered, even if small or large dots are included, the density is neutralized as a whole, making it difficult to recognize density unevenness.

Like this, in the structure that forms dot column by a plurality of head 41 that the ejection characteristic of ink is different, when dot column is formed by only one head 41 (above-mentioned head 41 (3), head 41 (5)), can produce density. Significant non-uniform problems.

==Relationship between the total sub-scanning amount of the head unit during printing and the width of the head unit==

In the printer 1 according to the present embodiment, ink is ejected across the entire width of the printing tape T during four movements in the main scanning direction (pass 1 to pass 4). This is because, since the resolution of the image (for example, the resolution in the sub-scanning direction is 720 dpi) is finer than the nozzle pitch ((360 dpi)), moving the head unit 40 in units of 720 dpi in the sub-scanning direction will result in a ratio A row of dots with finer spacing between the nozzles.

On the other hand, between the four strokes of stroke 1 to stroke 4, the head unit 40 moves three times in the sub-scanning direction (FIG. 4C, FIG. 4E, FIG. 4G). Moreover, in order to eject ink across the entire width of the printing tape T in strokes 1 to 4, the sub-scanning amount of the head unit 40 is adjusted according to the total movement amount of these three movements (hereinafter referred to as the total sub-scanning amount). The width in the scanning direction is different. This point will be described using FIGS. 6A and 6B .

FIG. 6A shows the width of the head unit 40 in the case of increasing the total sub-scanning amount. FIG. 6B shows the width of the head unit 40 in the case of reducing the total sub-scanning amount. In addition, the head unit 40 on the left side indicated by the dotted line in FIGS. The state where the fourth movement in the main scanning direction (stroke 4) is about to start. Therefore, the amount of shift in the sub-scanning direction of the head unit 40 indicated by the dotted line and the head unit 40 indicated by the solid line becomes the total sub-scanning amount of the head unit 40 .

As can be seen from FIGS. 6A and 6B , the greater the total sub-scanning amount, the greater the width of the head unit 40 in the sub-scanning direction in order to eject ink across the entire width of the printing tape T. That is, the number of heads 41 constituting the head unit 40 increases. Furthermore, increasing the width of the head unit 40 may increase the size of the printer 1 in order to secure an installation space for the head unit 40 .

==Print processing related to this embodiment==

In order to suppress the above-mentioned problems, that is, the conspicuous density unevenness and the increase in the width of the head unit 40 in the sub-scanning direction, the printer 1 executes the printing process described below.

This printing process is characterized in that (1) the drive unit 30 is moved such that the total movement amount of the head unit 40 in the sub-scanning direction during printing is smaller than the effective nozzle width (described later) of one head 41 in the sub-scanning direction. Head unit 40; (2) according to the number of scan lines (dot columns) formed by the nozzles of one head 41 ejecting ink according to the scan line group (multiple dot columns), for more than two heads 41 Scanning line groups are formed such that the number of scanning lines formed by ejecting ink from the nozzles is equal to or smaller than the number of scanning lines.

Various operations of the printer 1 during printing processing are mainly realized by the controller 10 . Particularly in this embodiment, it is realized by CPU 12 processing a program stored in memory 13 . Furthermore, this program is composed of codes for performing various operations described below.

FIG. 7 is a flowchart for explaining this printing process. The flowchart shown in FIG. 7 starts when the controller 10 receives print data from the computer 90 ( FIG. 1 ) through the interface 11 .

In this printing process, first, the controller 10 transports the printing tape T to the printing area by the transport unit 20 (step S2). That is, the transport roller 21 transports the unprinted printing tape T to the suction table 23 as a printing area.

Then, the controller 10 moves the head unit 40 in the main scanning direction driven by the driving unit 30 ( FIG. 4B ), while ejecting ink from the nozzles (step S4 ). That is, the controller 10 forms the dot row of the pass 1 on the printing tape T held by the suction table 23 . Since an image (printed matter) is formed by four passes, the controller 10 moves the head unit 40 in the sub-scanning direction by a predetermined sub-scanning amount ( Fig. 4C) (step S6: No, step S8).

Then, until the end of the dot forming process, the controller 10 alternately performs the formation of dot rows accompanying the movement of the head unit 40 in the main scanning direction ( FIGS. 4D , 4F, and 4H ), and the movement of the head unit 40 in the sub-scanning direction. Move (FIG. 4E, FIG. 4G) (steps S4 to S8). In addition, in the present embodiment, so-called overlay printing is performed.

Here, the overlay printing according to this embodiment will be described. Overlap printing refers to a printing method in which one dot row (scanning line) is formed by two or more nozzles. Specifically, one nozzle intermittently forms dot rows every several dots in the main scanning direction. Then, another nozzle supplements the already formed intermittent dot row to form a dot row.

8 and 9 are diagrams for explaining overlapping printing according to this embodiment. Wherein, for simplicity of description, only the nozzle row C among the four nozzle rows (nozzle row Y, nozzle row M, nozzle row C, and nozzle row K) of each head 41 is shown, and the number of nozzles of each head 41 is reduced to 16. Therefore, FIG. 8 shows the position of the nozzle rows C of the heads (head 41(1) and head 41(2), etc.) on the inner side in the sub-scanning direction among the ten heads 41 in the passes 1 to 4 and the formation of dots. In FIG. 9 , the position of the nozzle row C of the head (head 41 (10) and head 41 (9), etc.) on the near side in the sub-scanning direction in the stroke 1 to the stroke 4, and the dot formation state are shown. . In addition, in Fig. 8 and Fig. 9, the point that the nozzle of head 41 (1) and head 41 (7) is represented by white circle (○), and the point that head 41 (2) and head 41 ( 8) The dots formed by the nozzles, the dots formed by the nozzles of the head 41 (3) and the head 41 (9) are represented by a white triangle (△), and the head 41 (4) and the head 41 (10) are represented by a black triangle (▲). The point formed by the nozzle.

In pass 1 to pass 4, dots are formed on pixels in the print area by the nozzles of the nozzle row C. FIG. Here, a "pixel" refers to a square on a grid that is assumed to be set on the printing tape T in order to limit the positions where dots are formed. In addition, in order to specify pixels for description, pixels arranged in the main scanning direction are represented by "rows", and pixels arranged in the sub-scanning direction are represented by "columns". In addition, the pixels shown in FIGS. 8 and 9 are arranged at intervals of 720 dpi in both the main scanning direction and the sub scanning direction.

First, in a pass 1, ink is ejected from the nozzles of the heads 41 . Then, in odd-numbered rows (1, 3, 5...rows) shown in FIG. 8 , dot columns are formed for pixels in odd-numbered columns (1, 3, 5...columns). For example, ink is ejected from the nozzle #1 of the head 41 ( 1 ), and dots are formed on the pixels in the odd-numbered columns of the first row. Similarly, ink is ejected from the nozzle #2 of the head 41 ( 1 ), and dots are formed on the pixels in the odd-numbered columns of the third row. In this way, each nozzle forms dots at intervals of one pixel along the main scanning direction on each row corresponding to each position.

In addition, the method of ejecting ink from overlapping nozzles of two adjacent heads in the width direction (here, head 41(1) and head 41(2) will be described as an example) is different from that of non-overlapping nozzles (e.g., head 41(2)). 41(1) The ink ejection method of the nozzle #1) is different. That is, in the stroke 1, the nozzles #15 and #16 of the head 41(1) on the inner side in the width direction form dot columns on the pixels in the 3rd, 7th, 11th... columns, and the head 41(2) on the near side ) nozzle #1 and nozzle #2 form dot columns on the pixels of the 1st, 5th, 9th... columns. In this way, the nozzles of two adjacent heads 41 eject ink alternately to form dot columns on odd-numbered columns of pixels.

After the end of pass 1, as the first movement in the sub-scanning direction during printing, the head unit 40 moves from the inner side to the front side in the sub-scanning direction by a predetermined sub-scanning amount F (specifically, 7/720 dpi).

In the pass 2 after the movement of the head unit 40 , in the even-numbered rows (8, 10, 12 . . . rows), dot columns are formed for the pixels in the even-numbered columns (2, 4, 6 . . . columns). For example, ink is ejected from the nozzle #1 of the head 41(1) to form dots on the pixels in the even-numbered columns of the eighth row. Similarly, ink is ejected from the nozzle #2 of the head 41 ( 1 ), and dots are formed on the pixels in the even-numbered columns of the tenth row. In addition, in the second pass, the nozzles #15 and #16 of the head 41 (1) on the inner side in the width direction among the adjacent heads form dot rows on the pixels of the 4th, 8th, 12th... columns, On the other hand, the nozzles #1 and #2 of the head 41 ( 2 ) on the near side form dot columns on the pixels in the 2nd, 6th, 10th, ... columns. That is, similarly to the first pass, the nozzles of two adjacent heads 41 alternately eject ink to form dots on pixels in even-numbered columns (the same applies to the third and fourth passes described below).

After the stroke 2 is completed, the head unit 40 moves by a predetermined sub-scanning amount F (7/720 dpi) as the second movement in the sub-scanning direction during printing.

Similarly, in pass 3, in odd-numbered rows (15, 17, 19...rows), dot columns are formed for pixels in even-numbered columns (2, 4, 6...columns). As a result, for example, the dot column of the 23rd row is completed by the pass 1 and the pass 3 .

After the stroke 3 is completed, as the third movement in the sub-scanning direction during printing, the head unit 40 moves by the same sub-scanning amount F (7/720 dpi) as the first and second sub-scanning amounts. In this way, each movement amount F of the three movements in the sub-scanning direction of the head unit 40 has the same magnitude. Furthermore, the total of the three sub-scanning amounts of the head unit 40 (the total sub-scanning amount 3F) is smaller than the effective nozzle width of one head 41 described below.

First, effective nozzles will be described. Regarding effective nozzles, the method of consideration differs depending on the presence or absence of overlapping nozzles (described above) between adjacent heads 41 . In the case of no overlapping nozzles, the effective nozzles of each head 41 are all the nozzles of the nozzle row (see FIG. 11 ). On the other hand, when there are overlapping nozzles, the effective nozzles of each head 41 are determined in consideration of the overlapping nozzles. Specifically, the effective nozzles of a head 41 are composed of nozzles that do not overlap in the nozzle row of the head 41 and nozzles in which the overlapping nozzles of the head 41 are evenly distributed by utilizing the relationship with other heads 41 .

Here, how to evenly distribute overlapping nozzles will be described. For example, in FIG. 8 , nozzle #15 and nozzle #16 of the head 41 ( 1 ) overlap with nozzle #1 and nozzle #2 of the head 41 ( 2 ). At this time, the overlapping nozzles are evenly distributed in such a way that nozzle #15 of the above-mentioned nozzle #15 and nozzle #16 is included in the effective nozzles of the head 41(1), and nozzles of the above-mentioned nozzle #1 and nozzle #2 #2 is included in the active nozzles of head 41(2). In this way, half of the overlapping nozzles of the head 41 are allocated to the head 41 so that the effective nozzles are included.

Each of the ten heads 41 in this embodiment has overlapping nozzles, and the effective nozzles of the respective heads 41 are as follows. The effective nozzles of head 41(1) are nozzle #1 to nozzle #14; and nozzle #15 among nozzle #16 overlapping with nozzle #1 and nozzle #2 of head 41(2) is fifteen in total. nozzle. On the other hand, the effective nozzles of the head 41(2) are nozzle #2 among nozzle #1 and nozzle #2 overlapping with nozzle #15 and nozzle #16 of the head 41(1); nozzle #3 to nozzle #14; There are 14 nozzles in total among nozzle #15 and nozzle #16 overlapping with nozzle #1 and nozzle #2 of the nozzle 41 ( 3 ). The effective nozzles of the heads 41 ( 3 ) to 41 ( 9 ) are the same as the head 41 ( 2 ), and they are the nozzles #2 to the nozzles #15. On the other hand, effective nozzles of the head 41 ( 10 ) are nozzle # 2 among nozzle # 1 and nozzle # 2 overlapping with the nozzles of the head 41 ( 9 );

Next, the effective nozzle width determined based on the above-mentioned effective nozzles will be described. The effective nozzle width is the width of effective nozzles (the effective nozzles are arranged at intervals of 2/720 dpi in the sub-scanning direction) in the sub-scanning direction. In this embodiment, since there are fifteen effective nozzles for the head 41(1) and the head 41(10), the effective nozzle width of the head 41(1) and the head 41(10) is 30/720 dpi. On the other hand, since the effective nozzles of the heads 41 ( 2 ) to 41 ( 9 ) are fourteen, the effective nozzle widths of the heads 41 ( 2 ) to 41 ( 9 ) are 28/720 dpi. Furthermore, in the printer 1 , the total sub-scanning amount 3F (21/720 dpi) of the head unit 40 during printing is set to be smaller than the smaller effective nozzle width (28/720 dpi) of the two effective nozzle widths.

Continue with the instructions for overlay printing. In pass 4, in even-numbered rows (22, 24, 26...rows), dot columns are formed for pixels in odd-numbered columns (1, 3, 5...columns). As a result, for example, the dot column of the 22nd row is completed by the run 2 and the run 4 . In this way, in the overlay printing of this embodiment, one dot row is formed by two different nozzles.

Here, it will be considered which nozzle of the head 41 forms the dot row (scanning line) in the printing area. Here, the dot sequence in the print area refers to the dot sequence completed like the dot sequence in the 22nd row, and in this embodiment refers to the dot sequence from the 22nd row to the L row ( FIG. 9 ).

First, focus on 28 dot columns (scanning lines) from the 22nd row to the 49th row. These dot rows are formed by the nozzles of the head 41(1) and the head 41(2). When observed in detail, the ten dot columns of the 22nd to 28th, 30th, 32nd and 34th rows are formed by two different nozzles of the head 41(1), and the two nozzles of the 47th and 49th rows dot columns, formed only by two different nozzles of the head 41(2). On the other hand, among the 28 dot rows, the other ones (sixteen dot rows) are formed by the nozzles of both the head 41 ( 1 ) and the head 41 ( 2 ). Like this, in the dot row of row 22 to row 49, the number (twelve) of the dot row formed by the nozzle of only one head 41 is less than the quantity (sixteen) of the dot row formed by the nozzle of two heads 41. ).

Next, focus on the 28 dot columns from the 50th row to the 77th row. Among them, the reason for paying attention to 28 dot rows is that the sub-scanning amount F (7/720dpi) of the head unit 40 is 1/4 times the effective nozzle width (28/720dpi), so the dot rows of the printing area are 28 Dot rows are repeatedly formed as one cycle (in other words, the combination of nozzles forming each dot row is determined for 28 dot rows). That is, similarly to the 28 dot columns in rows 50 to 77, the subsequent 28 dot columns (for example, the dot columns in rows 78 to 105) are also formed in the same manner as the 28 dot columns in rows 22 to 49.

Furthermore, the dot columns of the 50th row to the 77th row are formed by the nozzles of the head 41(1), the head 41(2), and the head 41(3). When observed in detail, the eight dot columns of rows 51, 53 to 56, 58, 60, and 62 are formed by two different nozzles of the head 41(2), and the two dot columns of rows 75 and 77 , formed by two different nozzles of the head 41(3). On the other hand, among the 28 dot rows, the dot rows other than the above (18 dot rows) are formed by the nozzles of any two of the heads 41 ( 1 ), 41 ( 2 ), and 41 ( 3 ).

In this way, even in dot columns of 50 to 77 rows (that is, 28 dot columns corresponding to one period in the case of using a combined periodic repetition of nozzles), only the dot columns formed by the nozzles of one head 41 The number (ten) is also less than the number (eighteen) of the dot rows formed by the nozzles of the two heads 41. Furthermore, in this printing process, the number of dot rows formed by the nozzles of only one head 41 among the dot rows included in the print area is smaller than the number of dot rows formed by the nozzles of two heads 41 .

The overlay printing according to this embodiment has been described above. Next, returning to the flowchart shown in FIG. 7 , the description of this printing process is continued. When the dot forming process is completed by forming a dot row of 4 runs (step S6: Yes), in other words, when a printed matter (image) is printed on the printing tape T, the controller 10 causes the head 40 to drive Driven by the unit 30, it moves in the sub-scanning direction (FIG. 4I) to be located at the home position (step S10).

Then, the controller 10 outputs the dot-formed printing tape T (printed printing tape T) from the printing area by the transport unit 20 (step S12 ). That is, the output roller 22 outputs the printed printing tape T from the printing area.

Then, when there is still print data to be printed (step S14: Yes), the controller 10 repeats the above-mentioned operations (steps S2 to S12) to print on the printing tape. On the other hand, when there is no print data (step S14: NO), the controller 10 ends this print process.

<Validity of this print processing>

In the above-mentioned printing process, the total sub-scanning amount 3F (21/720dpi) of the sub-scanning direction of the head unit 40 by the controller 10 is smaller than the effective nozzle width (28/720dpi) of the sub-scanning direction of one head 41. In this way, the width of the head unit 40 in the sub-scanning direction can be suppressed from increasing by moving the head unit 40 .

That is, as described above, the larger the total sub-scanning amount of the head unit 40 is, the larger the width of the head unit 40 in the sub-scanning direction is (see FIG. 6 ). Therefore, by making the total sub-scanning amount of the head unit 40 smaller than the effective nozzle width of one head 41, the total sub-scanning amount of the head unit 40 can be reduced and overlapping printing can be realized (FIG. 8, FIG. 9). As a result, even when ink is ejected across the entire width of the printing tape T in each pass of the overlapping printing, it is possible to suppress the width of the head unit 40 from increasing (the number of heads 41 increases).

In addition, the number of scanning lines formed by ejecting ink from only one nozzle of the head 41 in the scanning line group (scanning lines in the printing area of FIGS. 8 and 9 ) by the controller 10 is two or more. The scanning line group is formed so that the number of scanning lines formed by ejecting ink from the nozzles of the head 41 is equal to or smaller than that of the scanning line group, thereby suppressing deterioration of image quality.

That is, as described above, the number of scanning lines formed by the nozzles of only one head 41 (as explained in FIG. The more there is, the more conspicuous the density unevenness becomes (see FIG. 5 ). Therefore, by setting the number of scanning lines formed by the nozzles of only one head 41 to be equal to or less than the number of scanning lines formed by the nozzles of two or more heads 41, the number of scanning lines formed by only one head 41 (ten heads 41) can be reduced. The ratio of scanning lines formed by the nozzles of the head 41 with a small discharge amount or the head 41 with a large discharge amount (scanning lines with uneven density) in the scanning line group ( FIGS. 8 and 9 ). Therefore, it is possible to suppress density unevenness from becoming conspicuous, and as a result, deterioration of image quality can be suppressed.

In addition, by making the total sub-scanning amount 3F smaller than the effective nozzle width of one head 41 , it is possible to suppress the problem that density unevenness due to connection points of adjacent heads 41 becomes conspicuous. That is, it is known that since the head unit 40 is a unit in which ten heads 41 are connected in the sub-scanning direction, density unevenness occurs when the positional accuracy of the connection point is low. Also, in the case of forming an image by a plurality of passes, for example, when the connection point in pass 1 and the connection point in pass 2 coincide in the sub-scanning direction, density unevenness due to the connection point becomes conspicuous. On the other hand, as in this printing process, by making the total sub-scanning amount 3F smaller than the effective nozzle width of one head 41, as shown in FIG. 8 and FIG. The problem of conspicuous concentration unevenness can be suppressed.

Therefore, according to the printing process described above, it is possible to suppress the width of the head unit 40 in the sub-scanning direction from becoming large, and to suppress deterioration of image quality.

In addition, in the printing process described above, the controller 10 ejects ink from all the heads 41 in four passes (equivalent to m movements) of passes 1 to 4 . Thereby, with the minimum number of heads 41, it is possible to reduce the total sub-scanning amount of the heads 40 and realize overlapping printing.

In addition, in the printing process described above, the controller 10 sets the movement amounts (sub-scanning amount F) to be the same for three movements of the head unit 40 in the sub-scanning direction (corresponding to n times of movement). Therefore, dot rows can be periodically formed, and the locations where density unevenness occurs are also regularly dispersed, thereby effectively suppressing concentration unevenness from becoming conspicuous.

==Second Embodiment==

FIG. 10 shows a head unit 40 according to the second embodiment. In this head unit 40 , unlike the head unit 40 according to the first embodiment shown in FIG. 3 , there are no overlapping printing nozzles. In addition, since other configurations are the same as those of the first embodiment, description thereof will be omitted.

In the second embodiment, the controller 10 also (1) makes the head unit 40 move in such a way that the total movement amount of the head unit 40 in the sub-scanning direction during printing is smaller than the effective nozzle width of one head 41 in the sub-scanning direction. Move under the driving of the drive unit 30; (2) according to the number of scan lines formed by only making the nozzles of one head 41 eject ink in the scan line group, for making the nozzles of more than two heads 41 eject ink The scanning line group is formed in the following manner while the number of scanning lines is formed.

FIG. 11 is a diagram for explaining overlay printing according to the second embodiment. In FIG. 11 , as in FIG. 8 , only the nozzle row C is shown, and the number of nozzles of each head 41 is also fourteen. And, the dots formed by the nozzles of the head 41 (1) are indicated by white circles (○), the dots formed by the nozzles of the head 41 (2) are indicated by black circles (●), and the heads 41 (3) are indicated by white triangles (△). The dots formed by the nozzles of the head 41 (4) are indicated by black triangles (▲). In addition, the effective nozzles of each head 41 shown in FIG. 11 are fourteen nozzles #1 to #14, respectively, and the effective nozzle width of each head 41 is 28/720dpi, which is equal.

As shown in FIG. 11 , the sub-scanning amount F per one head unit 40 is 7/720 dpi as in the first embodiment ( FIG. 8 ), and the total sub-scanning amount 3F is 21/720 dpi. Also, the total sub-scanning amount 3F (21/720dpi) is smaller than the effective nozzle width (28/720dpi). Therefore, similarly to the first embodiment, it is possible to suppress the width of the head unit 40 in the sub-scanning direction from increasing.

In addition, unlike FIG. 8, in FIG. 11, the number of scanning lines formed by ejecting ink from the nozzles of only one head 41 is different from the number of scanning lines formed by ejecting ink from the nozzles of two or more heads 41. equal. This is because in the second embodiment, there are no overlapping nozzles.

First, focus on the 28 dot columns from row 22 to row 49. Ten dot columns in rows 22 to 28, 30, 32, and 34 are formed only by the nozzles of head 41(1), and four dot columns in rows 43, 45, 47, and 49 , formed only by the nozzles of head 41(2). That is, the number of dot rows formed only by the nozzles of the head 41 is fourteen. On the other hand, among the 28 dot rows, the other ones (fourteen dot rows) are formed by the nozzles of both the head 41 ( 1 ) and the head 41 ( 2 ). Likewise, among the 28 dot columns from rows 50 to 77, the number of dot columns formed by the nozzles of one head 41 is also fourteen, and the number of dot columns formed by the nozzles of two heads 41 is fourteen.

In this way, the scanning line group is formed so that the number of scanning lines formed by ejecting ink from the nozzles of only one head 41 is equal to or less than the number of scanning lines formed by ejecting ink from the nozzles of two or more heads 41. , like the first embodiment, it is possible to reduce the number of scan lines formed by the nozzles of only one head 41 (as illustrated in FIG. 5 , the head 41 with a small discharge amount or the head 41 with a large discharge amount). ratio in . Therefore, even if it is a scanning line formed by only one nozzle of the head 41 , the number of scanning lines causing density unevenness can be reduced, and as a result, it is possible to suppress the density unevenness from becoming conspicuous.

==Third Embodiment==

Next, overlay printing according to the third embodiment will be described. FIG. 12 is a diagram for explaining overlay printing according to the third embodiment.

In the third embodiment, as shown in FIG. 12 , one scanning line is also completed by four passes (overlapping printing). That is, between four passes, ink is ejected from each head to complete one scanning line. Specifically, the points in the 1st and 5th columns are formed by run 1, the points in the 2nd and 6th columns are formed by run 2, the points in the 3rd and 7th columns are formed by run 3, and the points in the 4th and 6th columns are formed by run 3. The points of column 8 are formed by run 4. In addition, in FIG. 12, the dots up to the eighth column are shown, but actually more columns form dots.

In addition, the head unit 40 of this embodiment is the same as the head unit 40 (FIG. 3) of 1st Embodiment. That is, there are overlapping nozzles in two adjacent heads 41 . Moreover, the nozzle pitch of each nozzle is 1/360dpi.

The scan line intervals of the first and second embodiments are 1/720dpi (see FIGS. 8 and 11 ), whereas the scan line intervals shown in FIG. 12 are 2/720dpi (=1/360dpi) (that is, , the same size as the nozzle pitch). Therefore, in the third embodiment, unlike the first and second embodiments, interlace printing is not performed. Here, interlaced printing refers to a printing method in which scanning lines not formed are interposed between scanning lines formed in one pass as shown in FIGS. 8 and 11 .

In addition, in FIG. 12, similarly to FIG. 8, only the nozzle row C is shown, and the number of nozzles of each head 41 is also sixteen. In addition, here, for convenience of description, the head unit 40 will be described as having three heads 41 ( 1 ) to 41 ( 3 ). And, the dots formed by the nozzles of the head 41 (1) are indicated by white circles (○), the dots formed by the nozzles of the head 41 (2) are indicated by black circles (●), and the heads 41 (3) are indicated by white triangles (△). The point formed by the nozzle.

Moreover, the effective nozzles of each head 41 shown in FIG. 12 are the same as those of the first embodiment, and will be described below. The effective nozzles of the head 41 ( 1 ) are fifteen nozzles from nozzle #1 to nozzle #15, and the effective nozzle width thereof is 30/720 dpi. The effective nozzles of the head 41 ( 2 ) are fourteen nozzles from nozzle #2 to nozzle #15, and the effective nozzle width is 28/720 dpi. The effective nozzles of the head 41 ( 3 ) are fifteen nozzles from nozzle #2 to nozzle #16, and the effective nozzle width is 30/720 dpi.

In addition, in the third embodiment, the one-time sub-scanning amount F of the head unit 40 is 8/720 dpi, and the total sub-scanning amount 3F in four strokes is 24/720 dpi. Also in the third embodiment, the total sub-scanning amount 3F (24/720 dpi) is set smaller than the width of the smaller effective nozzle (28/720 dpi) among the widths of the two effective nozzles. Therefore, similarly to the first embodiment, it is possible to suppress the width of the head unit 40 in the sub-scanning direction from increasing.

Here, it will be considered which nozzle of the head 41 forms each scanning line in the printing area. Here, as shown in FIG. 12 , the scanning lines of the printing area in this embodiment refer to the scanning lines from row R1 to row R30 .

First, the scanning lines of row R1 to row R3 are formed only by the nozzles of the head 41(1). The scanning lines of the R4 row to the R15 row are formed by the nozzles of the head 41(1) and the head 41(2). The scanning lines of the R16 and R17 rows are formed only by the nozzles of the head 41(2). The scanning lines of the R18 row to the R29 row are formed by the nozzles of the head 41(2) and the head 41(3). Also, the scanning lines of row R30 are formed only by the nozzles of the head 41(3).

In addition, when viewed in the range of the above-mentioned effective nozzle width (28/720dpi) (here, the scanning lines from row R4 to row R27 are described as an example), only one nozzle of the head 41 ejects ink to form a The number of scanning lines is twelve from row R4 to row R15, and the number of scanning lines formed by ejecting ink from the nozzles of the two heads 41 is two for row R16 and row R17.

In this way, the number of scanning lines formed by ejecting ink from the nozzles of only one head 41 is smaller than the number of scanning lines formed by ejecting ink from the nozzles of two or more heads 41 . Thus, as in the first embodiment, even if the scanning lines are formed by only one nozzle of the head 41 , the number of scanning lines causing density unevenness can be reduced, and as a result, it is possible to suppress the density unevenness from becoming conspicuous.

In addition, in the above description, the sub-scanning amount F of each time when four passes are performed is 8/720 dpi of the same size, however, the sub-scanning amount of each time may be different. Also, in the above, the dots in the 1st column (column 5) are formed by the 1st stroke, the dots in the 2nd column (column 6) are formed by the 2nd stroke, and the dots in the 3rd column (column 7) are formed by the Three passes are formed, and the dots in the fourth column (eighth column) are formed by the fourth pass, but the present invention is not limited thereto. It is only necessary that at least points in adjacent columns are formed by different runs.

In addition, in the above description, one scan line is formed by four passes, but the present invention is not limited thereto. It is only necessary to form one scanning line by at least two passes (integer times of two or more passes), for example, one scanning line may be formed by three passes (the same applies to the first and second embodiments).

==Other implementations==

As above, the liquid ejection device and the like according to the present invention have been described based on the above-mentioned embodiments, but the above-mentioned embodiments of the present invention are for the purpose of facilitating understanding of the present invention and do not limit the present invention. The present invention can be changed and improved without departing from the gist, and it goes without saying that equivalents thereof are all included in the protection scope of the present invention.

Moreover, in the above-mentioned embodiments, the liquid ejection device is embodied as an inkjet printer, but it is not limited to this, and it may also be embodied as ejecting (jetting) other liquids (for example, particles with functional materials dispersed therein) than ink. A liquid ejection device for fluids such as liquids and gels). For example, it may be a liquid ejection that includes liquid crystal displays, color filters, EL (electroluminescence) displays, and surface emission displays, in which materials such as electrode materials and color materials are used in the manufacture of dispersed or dissolved materials. A device; a liquid ejection device that ejects biological organisms used in the production of biochips; a liquid ejection device that is used as a precision pipette and ejects a liquid that becomes a sample. In addition, it can also be a liquid ejection device that ejects lubricating oil from dotted holes on precision machines such as clocks and cameras; in order to form micro hemispherical lenses (optical lenses) used in optical communication elements, etc., spray on the substrate A liquid ejection device that ejects transparent resin liquids such as ultraviolet curable resins; a liquid ejection device that ejects etching solutions such as acids or alkalis for etching substrates; and a fluid ejection device that ejects gels. Also, the present invention can be applied to any of these devices for ejection.

Also, in the above-described embodiment, the scanning line is formed by moving the head unit 40 four times in the main scanning direction and three times in the sub scanning direction while the printing tape T is stopped ( FIGS. 8 and 9 ). , but is not limited to this. For example, it is also possible to move the head unit 40 only in the main scanning direction, and move the printing tape T in the sub-scanning direction to form a scanning line. In addition, the head unit 40 may not move, but pass the printing tape T in the main scanning direction. direction and sub-scanning direction to form scanning lines. That is, the scanning lines can be formed by relatively moving the head unit 40 with respect to the printing tape T in the main scanning direction and the sub scanning direction.

In addition, in the above-mentioned embodiment, the overlapping nozzles of the adjacent heads 41 (for example, the nozzle #15 of the head 41(3), and the nozzle #1 of the head 41(4)) alternately eject ink to form one A scanning line (ie, two overlapping nozzles both eject ink), however, is not limited thereto.

For example, ink may be ejected from only one of the overlapping nozzles of adjacent heads 41 . Specifically, for the head 41 (3), ink is ejected from the nozzles #1, #2 of the overlapping nozzles (nozzles #1, #2, #15, #16), and ink is not ejected from the nozzles #15, #16. 16 ejects ink. Likewise, for the head 41 (4), ink is ejected from the nozzles #1, #2 of the overlapping nozzles (nozzles #1, #2, #15, #16), but not from the nozzles #15, #16. Squirt ink. In this case, the number of effective nozzles (fourteen) of each head 41 is equal.

In addition, in the above case, since the usage states of the nozzles (mainly overlapping nozzles) located at the connection points of the adjacent heads 41 are the same, the scanning lines corresponding to the connection point portions of the heads 41 are also formed at equal intervals. (that is, formed regularly), therefore, it is also possible to suppress concentration unevenness due to connection points.

Claims (4)

1. A liquid ejection device, characterized in that, possesses: (a) a head unit having a plurality of heads arranged along a first direction in which a plurality of nozzles for ejecting liquid to a medium are arranged, and opposite to each other in a second direction intersecting the first direction. The medium is relatively moved, and the liquid is ejected, A width of the head unit in the first direction is greater than a width of the medium in the first direction; (b) a moving mechanism that moves the head unit relative to the medium alternately multiple times in the second direction and the first direction; and (c) a control unit that moves the head unit relative to the medium alternately multiple times in the second direction and the first direction by using the moving mechanism, and makes two or more different The nozzles eject the liquid respectively to form scanning lines to form scanning line groups, Said The moving mechanism moves the head unit relatively, According to the number of the scanning lines formed by causing the nozzles of only one head to eject the liquid in the scanning line group, the nozzles of two or more heads eject the liquid. The scan line group is formed in such a manner that the number of the scan lines formed by the liquid is less than or equal to that of the scan line. 2. The liquid ejection device according to claim 1, wherein: When the number of times the head unit moves in the second direction when the head unit performs the multiple relative movements is m times, During the m movements, all the heads eject the liquid. 3. The liquid ejection device according to claim 1 or 2, wherein: When the number of times the head unit moves in the first direction when the head unit performs the multiple relative movements is set to n times, Each movement amount of the n times of movement is the same size. 4. A scanning line forming method, (a) Each scanning line group is formed by making the head unit relative to the medium alternately move multiple times in the second direction and the first direction, and making two or more different nozzles respectively eject liquid to form each scanning line , wherein the head unit has a plurality of heads arranged along the first direction with a plurality of nozzles for ejecting liquid to the medium, and in a second direction intersecting the first direction Relatively moving relative to the medium, and ejecting the liquid, the width of the head unit in the first direction is larger than the width of the medium in the first direction, characterized in that, (b) in such a manner that the total amount of movement of the head unit in the first direction when the head unit performs the plurality of relative movements is smaller than the effective nozzle width of one head in the first direction, causing the head unit to move relatively, According to the number of the scanning lines formed by causing the nozzles of only one head to eject the liquid in the scanning line group, the nozzles of two or more heads eject the liquid. The scan line group is formed in such a manner that the number of the scan lines formed by the liquid is less than or equal to that of the scan line.

Images