JP2006069177A - Line dot printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an ink jet printer to perform high speed printing with high image quality. <P>SOLUTION: A drum 2 having a rotating surface SR being fixed with a plurality of sheets P1 and P4 is provided with a blank section BK being fixed with no sheet P. When printing is carried out in the blank section BK while altering the position of an ink jet line head arranged on the rotating surface SR of the drum 2, irregularity due to non-print is prevented, and an ink jet printer can perform high speed printing with high image quality while sustaining maximum operation efficiency of a head. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a line dot recording apparatus using a line head.

  For example, an ink jet printer which is a line dot recording apparatus prints by ejecting minute ink particles from a large number of recording elements (hereinafter referred to as nozzles) formed on a printer head onto a substrate. In particular, in an inkjet line printer in which a large number of nozzles are arranged in a line and printing is performed at once, the ejection volume (amount) and direction of ink from the nozzles vary depending on the individual nozzles. Variations in position occur. This variation results in non-uniform distances between adjacent dots, and the density becomes higher (darker) at closer locations and lower (lighter) at further distances, resulting in white streaks and other degradation of image quality. Arise. Therefore, color unevenness (in the case of color) occurs. In particular, in a line head in which short heads are attached in a staggered manner in the line head (for example, the carriage 10 used in the embodiment of FIG. 2), the difference in position in the scanning direction of the short head (perpendicular to the rotation direction of the drum). There has been a problem that streaky unevenness occurs in the image of the joint portion of the short head.

  As one method for solving this problem, for example, [Patent Document 1] describes a color ink jet printer that performs color printing on a printing material attached to a drum that rotates with a line head. In this printer, on a rotating surface of a drum to which a sheet-like printed material is attached, a line head in which a short head is attached in a staggered manner so as to be orthogonal to the rotation direction of the drum is arranged opposite to the drum. One image is completed by multiple printing (image recording).

That is, at least one of the main scanning direction and the sub-scanning direction is printed (recorded) every n-1 (n> 2) pixels. For example, in one-time (one-round) printing (image recording) in the main scanning direction, Ink is ejected for each of n-1 (n> 2) nozzles. In each printing (image recording), recording is performed so that the dots do not overlap each other, thereby suppressing unevenness due to mixing of the ink and wetting of the printing medium. Furthermore, by moving the line head in the main scanning direction, printing (image recording) is performed while improving non-ejection nozzles and uneven printing due to variations in dots from nozzle to nozzle and improving image quality by multipass. Is.
JP 2002-11865 A

  By the way, in the above-described ink jet printer, if the amount of movement when the line head is moved in the main scanning direction can be increased, the effect of improving the image quality by multipass can be enhanced, and high-quality printing can be performed. For example, assuming a case where unevenness occurs due to non-printing by a non-ejection nozzle, for example, if the amount of movement of the line head is small, the dispersion of unevenness is not sufficient and the human eye can easily recognize it. Because.

  However, the movement of the head takes time as the movement amount increases. In addition, since the movement starts after the completion of printing (image recording) and does not end before the start of the next printing (recording), the printing speed is hindered. Regulated by Therefore, there has been a problem that the rotational speed of the drum has to be reduced and printing cannot be performed at high speed.

  On the other hand, it is conceivable to increase the moving speed of the line head at this time, but if the moving speed is increased, force is applied to the ink in the head, and the discharge performance deteriorates due to fluctuations in pressure in the ink chamber, resulting in high image quality. The problem that it becomes impossible to print smoothly occurs.

  Accordingly, an object of the present invention is to improve a line dot recording apparatus so that high-quality printing by multipass can be performed at high speed.

  In order to solve the above-described problems, in the present invention, recording elements by jet nozzle discharge ports are arranged in a line on the rotation surface of a drum to which a sheet-like printed material is attached so that the rotation direction and the longitudinal direction of the drum are orthogonal to each other. In the line dot recording apparatus in which the line heads are arranged so as to face each other and print on the printing material mounted on the drum rotated by the line head, the line head is supported so as to be movable in the orthogonal direction. At the same time, the drum is configured to mount a plurality (N) of sheet-like printed materials on the rotation surface, and (N−1) sheets of the printed material are mounted on the rotation surface to form a blank section in which the printing material is not mounted. Thus, a configuration is adopted in which printing is performed by moving the line head in the orthogonal direction within a blank section in which the substrate is not mounted.

  By adopting such a configuration, the line head is moved each time the drum rotates, and a plurality of prints mounted on the drum are sequentially printed with different nozzles for each rotation. It is possible to reduce the influence of recording dot variations due to individual nozzle variations. At that time, the blank section is at least one substrate to be printed formed on the rotating surface of the drum without mounting the substrate, so that the movement of the line head is relatively slow without reducing the drum rotation speed. If this is done, the acceleration applied to the line head can be reduced to prevent unnecessary pressure from being applied to the ink in the head, so that the discharge performance can be prevented from deteriorating.

  At this time, the line head is composed of a plurality of line heads for each color ink, and the line head for each color is composed of a unit of a plurality of line heads. For each line head unit constituting each line head, the line head unit or the line head for each color ink is moved sequentially from the blank section or from the part that does not print continuously in the blank section. Can be adopted.

  By adopting such a configuration, the bottom of the paper preceding the blank section under the line head for each color or the line head unit constituting the line head for each color, or printing is not performed, for example, there is a blank space. The movement starts sequentially from the moment it passes, and can be used for movement until just before the next paper head comes across the blank section. Therefore, each line or the unit of the line head can use a blank section equal to the moving period.

  Also, at this time, the drum is to mount N sheets of sheet-like printed material on the rotation surface, and the drum rotates N times and is a multi-pass printing machine that completes one printing by N times of printing. It is possible to adopt a configuration that there is.

  By adopting such a configuration, printing on a single substrate is completed by rotating the drum N times, so printing is performed with different nozzles of the line head moved every rotation, and non-ejection High-quality printing can be achieved by reducing the influence of ejection unevenness that occurs due to nozzle-to-nozzle variation.

  The present invention is configured as described above, so that when a multi-pass printing is performed by a line dot recording apparatus (for example, an ink jet printer), a wasteful time at the time of head movement occurring between the passes is minimized. Therefore, high-quality printing can be efficiently performed at high speed.

The best mode for carrying out the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a line dot recording apparatus (hereinafter referred to as an ink jet printer) of this form includes a drum 2 on which a sheet-like printed material (here, print paper) P is attached, an ink jet line head 1, and a paper feed. It comprises means 3 and paper discharge means 5 and is controlled by the control means.

  The drum 2 rotatably supports a shaft (cylinder shaft) and is connected to motor driving means. The drum 2 has a side surface as a rotation surface SR, and mounting means 4 for attaching the paper P to the rotation surface SR. It is provided.

  The mounting means 4 is composed of a gripper claw 4a and a clamp 4b, and is held by the gripper claw 4a and the clamp 4b.

  The mounting means 4 is provided at four locations on the rotation surface SR of the drum 2. In this embodiment, four print sheets P can be attached. An ink jet line head 1 is provided on the rotation surface SR of the drum 2.

  Ten line heads 1 are provided in total for four colors of yellow 1Y, cyan 1C, magenta 1M, black 1B and 2B (yellow 1Y, cyan 1C and magenta 1M are two, black is 1B and 2B, 4), and the two are divided into two groups so as to cover the upper half of the drum 2 so that the longitudinal direction of the line head 1 is orthogonal to the rotational direction of the drum 2. In this way, black that produces sharpness of printing is doubled as the number of other colors, and the number of nozzles is doubled. For example, black dots can be overprinted once in one rotation of the drum 2, so that high quality Printing can be performed at high speed. Further, by performing overstrike in this way, even if a non-ejection nozzle is generated in one of the line heads 1B and 2B, it is possible to cover, and the influence can be reduced. In addition, since the black dot diameter can be made larger than the specified diameter, for example, when printing a full-color solid image, even if the black landing position accuracy is low, printing a full-color solid image is ensured. Can be done without gaps. Incidentally, it is preferable to set the discharge amount of the nozzle in the case of overprinting to, for example, about 0.5 to 1 times that of the other colors because the dot diameter of the landed ink can be maintained at a predetermined size.

  Furthermore, the black ink line heads 1B and 2B are arranged downstream of the other color line heads 1Y, 1M and 1C with respect to the rotation direction of the drum 2 as shown in FIG. Even when printing is performed separately (for example, multi-pass), the drum half circumference until the next printing can be used as the drying time, so that ink with low permeability is used for black ink. You can also. Further, even when the amount of black ink is increased, it is possible to increase the drying time.

Each of the color line heads 1Y, 1C, 1M, 1B, and 2B includes two line head units (hereinafter, carriage 10) as shown in FIG. 2 (for example, the yellow 1Y line head). 10, 14 short line heads 1Y _1-7 are arranged in a staggered manner on the support frame 1F to form a long line head unit having a printing range larger than that of the paper P as shown in FIG. It is what I did. Further, the support frame 1F has a structure in which a rod 10G is inserted vertically as shown in FIG. 2 and a ball screw 10S is screwed in the center, and the ball screw 10S is rotated by a stepping motor 10m so It can move in the direction. At this time, the position detection switch S is provided on the fixed frame 11 of the carriage 10 so as to avoid the collision of the support frame 1F and to return to the zero point, so that it can be controlled by connecting to the control means. is there.

  That is, as shown in FIG. 3, the stepping motor 10m of the carriage 10 for each color is connected to a control means (a controller such as a personal computer or the like) via a motor driver, and individual control can be performed for each color carriage 10. It is like that. For this reason, the encoder of the drum 2 can be used as a position sensor such as an encoder (optical type: absolute address or one that generates a serial pulse and can output a relative address from the origin in combination with a counter. The encoder output (origin signal, pulse signal proportional to the rotation amount, etc.) is input to the control means.

  In this way, for example, the origin position of the drum 2 is calculated based on the origin signal, and the respective movement timings of the line heads 1Y, 1C, 1M, 1B, and 2B of the respective colors are calculated based on the calculated origin position. be able to.

  Therefore, the calculated position of the carriage 10 of the current line heads 1Y, 1C, 1M, 1B, and 2B for each color, and the preset movement timing parameters for the line heads 1Y, 1C, 1M, 1B, and 2B for each color are described. , The carriages 10 of the corresponding color line heads 1Y, 1C, 1M, 1B, and 2B can be moved.

  The sheet feeding means 3 includes a sheet feeding roller 3c and a swinging gripper 3b. The swinging gripper 3b holds the end of the sheet P supplied one by one from the sheet feeding tray 6a by the conveyor 3a, and the arrow in FIG. And is fed to the paper feed roller 3c.

  That is, the paper feed tray 6a is provided with a suction arm 6b, and the paper P is supplied to the conveyor 3a one by one by the suction arm 6b (in response to a command from the control means). In the conveyor 3a, the registration means 3d is provided to align the position of the paper P in the width direction and the vertical direction, so that the paper P supplied from the conveyor 3a is fed to the paper feed roller 3c together with the gripper 3b. On the other hand, in the paper feed roller 3c to which the paper P is fed, the end of the paper P is added by the claw 3e provided on the paper feed roller 3c and rotated as indicated by the arrow in FIG. Deliver.

  The paper discharge means 5 includes a paper discharge roller 5a and a chain 5b attached to the roller 5a, and a gripper claw 5c is attached to the chain 5b. Therefore, the printed paper P is taken out by the gripper claw 5c and is carried out to the storage tray 7 by the rotation of the paper discharge roller 5a.

  Although not shown, the paper feed roller 3c, the paper discharge roller 5a, etc. are provided with sensors (for example, optical encoders, potentiometers) and are connected to control means so that control can be performed. The encoder provided on the shaft of the drum 2 is used not only for controlling the line head 1 but also for controlling the speed of the drum 2 and controlling the timing of paper feed and paper discharge.

  This embodiment is configured as described above, and the operation thereof will be described below with reference to FIGS.

  In this inkjet printer, when printing is started, the carriages 10 of the line heads 1Y, 1C, 1M, and 1B of the respective colors move in the main scanning direction (the width direction of the drum 2). The movement of the carriage 10 in the main scanning direction takes four positions as shown in FIG. 4. Thus, if the total movement amount is increased, high-quality printing can be performed. This is because, for example, assuming a case where unevenness due to non-ejection has occurred, if the movement of the carriage 10 is small, dispersion of unevenness is not sufficient and the human eye can easily recognize it.

  At this time, there are ten actual carriages 10, but in order to perform the same operation, only one is schematically represented here. Further, the line heads 1Y, 1C, 1M, 1B, and 2B of the respective colors constituted by the carriage 10 cover the upper half of the drum 2 as shown in FIG. Since it is in one of the left and right quarters, the section E will be described as a printing section for convenience as shown in FIG. Therefore, if the carriage 10 is a left section, the left section is a printing section.

  First, the first sheet P1 is supplied to the drum 2 as shown in FIG. That is, the paper is supplied from the paper feed tray 6a to the paper feed means 3 using the suction arm 6b and the conveyor 3a, and is delivered from the paper feed means 3 to the grip claw 4a of the drum 2 and mounted on the drum 2. At this time, the carriage 10 is at position 1.

  Now, when the first sheet P1 is mounted on the drum 2 and reaches the printing section E of the carriage 10, the first rotation printing is performed on the first sheet P1. Here, this printer adopts a multi-pass printing method, and forms one image by rotating the drum 2 four times. Therefore, the printing on the first sheet P1 of the first rotation is performed, for example, as shown in FIG. 9A, (a, 1), (c, 1), (b, 3), (d, 3). Thus, every other dot is printed so that it does not overlap with the dots of the adjacent nozzles and does not overlap with the dots of the adjacent lines.

  Here, FIG. 9 and FIG. 10 schematically show one image model for explaining the multipath method of the present application. Also, circles and triangles that indicate dots in the figure. . . The numbers (1 to 13) are given for convenience in order to easily distinguish the nozzles used for printing the dots, and the same numbered dots are printed using the same nozzles. .

  Thus, when the first rotation is completed and the first sheet P1 passes through the printing section E, the blank section BK in which the first sheet P1 is not loaded as shown in FIGS. Therefore, the movement in the main scanning direction (the width direction of the drum 2) is performed as shown in FIG.

  When the drum 2 finishes the first rotation and starts the second rotation as shown in FIG. 5 (ka), the second pass printing on the first sheet P1, that is, one sheet as shown in FIG. 9B. The printing is performed on the eye paper P1 as in (b, 1) (d, 1) (a, 3) (c, 3). Also, the second sheet P2 is mounted on the drum 2 and the first (first pass) printing is performed on the second sheet P2 mounted as shown in FIG. That is, as shown in FIG. 9B, printing is performed on the second sheet P2 as shown in (a, 1) (c, 1) (b, 3) (d, 3). Since the nozzles used at this time are different from the nozzles that performed the first rotation printing, the non-printing by the non-ejection nozzles can be dispersed to obtain the multi-pass printing effect.

  As shown in FIG. 5 (ki), when printing on the second sheet P2 is completed, a blank section BK in which the first and second sheets P1, P2 are not mounted is formed. Move in the main scanning direction. For example, it is moved as shown in FIG.

  When the drum 2 finishes the second rotation and starts the third rotation as shown in FIG. 5 (ke), the third pass is printed on the first sheet P1 as shown in FIG. In 6 (sa), the second pass printing is performed on the second sheet P2. That is, the first sheet P1 is (a, 2) (c, 2) (b, 4) (d, 4) as shown in FIG. 9C, and the second sheet P2 is (b , 1) (d, 1) (a, 3) (c, 3).

  Also, the third sheet P3 is loaded in FIG. 6 (sa), and the first (first pass) printing is performed on the third sheet P3 loaded in FIG. 6 (shi). That is, as shown in FIG. 9C, the printing of (a, 1), (c, 1), (b, 3), (d, 3) is performed on the third sheet P3.

  The nozzles used for printing the first, second, and third sheets P1, P2, and P3 are shown in FIG. 9C because the carriage 10 is advanced in FIG. Thus, the numbers are different from those in FIGS. 9A and 9B, and non-printing by non-ejection nozzles can be dispersed using different nozzles.

  When the printing on the third sheet P3 is completed, a blank period BK in which sheets P1, P2, and P3 are not mounted is entered as shown in FIG. Therefore, the carriage 10 is moved as shown in FIGS.

  Further, when the third rotation of the drum 2 is completed and the fourth rotation is started as shown in FIG. 6 (s), the fourth (fourth pass) printing is performed on the first sheet P1 in FIG. 6 (se). The third printing (third pass) is performed on the second sheet P2 in FIG. 6 (so), and the second (second pass) printing is performed on the third sheet P3 in FIG. I do. That is, as shown in FIG. 10 (d), after printing (b, 2) (d, 2) (a, 4) (c, 4) on the first sheet P1, the second sheet (A, 2) (c, 2) (b.4) (d, 4) is printed on the paper P2. Further, printing such as (b, 1) (d, 1) (a, 3) (c, 3) is performed on the third sheet P3. Since the printing on the first sheet P1 is completed, the sheet is discharged by the sheet discharge means 5 when the discharge point is reached as shown in FIG. At the same time, the fourth sheet P4 is loaded.

  In FIG. 6C, the drum 2 finishes the fourth rotation, starts the fifth rotation, and performs the first (first pass) printing on the fourth sheet P4 loaded ((e) in FIG. 10 (e)). b, 1) (d, 1) (b, 3) (d, 3)

  When the first printing (first pass) is performed on the fourth sheet P4 mounted in FIG. 6C, the blank section BK is obtained as shown in FIG. Move. When the movement of the carriage 10 to the position 1 is completed, the fourth printing (fourth pass) is performed on the second sheet P2 in FIG. 6 (t), and the third sheet P3 in FIG. 6 (and). Print the third time (3rd pass). That is, as shown in FIG. 10E, the printing of (b, 2), (d, 2), (a, 4), (c, 4) on the second sheet P2, and the third sheet P3. (A, 2), (c, 2), (b, 4), and (d, 4) are printed.

  At this time, since the printing on the second sheet P2 that has been printed for the fourth time is completed, the sheet is discharged by the discharge means 5 in FIG. 7 (N), and at the same time the fourth sheet P4 in FIG. 7 (N). The second printing (second pass) is performed, and the fifth sheet P1 ′ is loaded.

  In FIG. 7 (ni), printing is performed on the fifth sheet P1 '. At this time, the carriage 10 is at position 1, and multipass printing starts from position 1 as shown in FIG. 9 (a) → FIG. Repeat the pattern of e).

  Thus, the movement of the position of the carriage 10 moves in the order of positions 1 → 3 → 4 → 2 → 1 as in the above example. Unlike this example, for example, if you try to move in the order of position 1 → 2 → 3 → 4 → 1, the movement amount when moving from 1 → 2, 2 → 3, 3 → 4 is small, but 4 → The amount of movement when moving to 1 becomes extremely large, and the acceleration value during this time also becomes extremely large. On the other hand, when the movement is made as 1 → 3 → 4 → 2 → 1, the maximum value of the movement amount by one movement can be reduced, and the maximum acceleration can be kept low. As a result, the maximum value of acceleration due to carriage movement during printing can be made as low as possible, and the influence of acceleration during movement of the carriage 10 on the ejection of the head can be minimized. As described above, when the paper feeding at the start is completed, the drum 2 is always loaded with three sheets of paper P and printed.

  From here, the movement of the carriage 10 of the line heads 1Y, 1C, 1M, 1B, and 2B will be mainly described.

  That is, in FIG. 7 (ni), when the first printing on the fifth sheet P1 ′ is completed, the blank section BK is reached, so the carriage 10 is moved to the third sheet P3 as shown in FIG. Is moved before reaching the printing section E (position 3).

  As shown in FIGS. 11 (a) to 11 (e), this movement starts from the moment when the paper bottom of the preceding paper P1 ′ (for example, FIG. 7 ()) passes under one carriage 10, The movement is completed in the blank section BK up to the last minute just before the head of the next sheet P4 comes. Similarly, the remaining carriages 10 start moving from the moment when the paper bottom passes, and the movement is completed immediately before the next paper head arrives. Thus, each carriage 10 starts moving sequentially from the moment when the paper edge of the paper preceding the blank section BK passes, and moves immediately before the next paper head comes across the blank section BK. A blank interval BK can be used equal to movement. In the blank section BK, each carriage 10 moves relatively slowly (originally, a sufficient time is required for the line heads 1Y, 1C, 1M, 1B, and 2B to move using the printing section). Therefore, the acceleration applied to each carriage 10 is reduced, and unnecessary pressure is prevented from being applied to the ink inside the line heads 1Y, 1C, 1M, 1B, and 2B, and the ejection performance is deteriorated. The high-quality and high-quality printing is made possible.

  At this time, the position of the sheet P mounted on the drum 2 and the position of the blank section BK formed by mounting the sheet P are detected from, for example, the value of the encoder at the time of sheet feeding (for each carriage 10 of each color) Since the position is predetermined, the control means can control it.

  Next, the fourth printing is performed on the third sheet P3 in FIG. In FIG. 7 (), the third printing is performed on the fourth sheet P4. In FIG. 7 (ha), the third sheet P3 for which the fourth printing has been completed is discharged, the second printing of the fifth sheet P1 ′ is performed, and the sixth sheet P2 ′ is loaded. . Further, in FIG. 7H, when the sixth sheet P2 'is printed, the blank section BK is reached, so the carriage 10 is moved before the fourth sheet P4 reaches the printing section E.

  Thereafter, each time the drum 2 rotates 1 + 1 / N, printing is performed by supplying a new sheet P after the loaded sheet P. Further, when the blank section BK comes (under the carriage 10), the carriage 10 is moved. The state of the operation is shown in FIGS.

  Thus, in this ink jet printer, since the blank section BK is provided, the carriage 10 can be moved without reducing the speed of the drum 2. At that time, one printing is completed by a plurality of times of printing (multi-pass), the carriage 10 is moved for each printing, and the printing is performed with a large total movement amount, so that no discharge occurs. Since the non-printing by the nozzles is sufficiently dispersed and printed, the image quality can be improved by the multi-pass effect. Therefore, even if the total movement amount of the carriage 10 is increased and unevenness due to, for example, non-ejection occurs, if the carriage movement amount is small, the dispersion of unevenness is not sufficient and the human eye can easily recognize it. There is no such thing and high quality printing is possible. In addition, since the carriages 10 are sequentially moved so that the carriages 10 can be moved relatively slowly, unnecessary pressure can be prevented from being applied to the ink in the head, and high-definition printing can be performed. Therefore, for example, even with a line head in which the short heads used in this form are mounted in a staggered manner, streak-like unevenness can be prevented from occurring in the images of the joint portions of the short heads, so high-quality printing is performed at high speed. be able to. Further, it is possible to minimize a wasteful time when the head is moved between the passes. For this reason, it is possible to perform printing while keeping the operating efficiency of the head to the maximum.

  In the embodiment, the case where the carriage of the line head of each color is moved has been described. However, the present invention is not limited to this. The line head is provided with moving means by a motor such as a carriage. You may make it move.

  Furthermore, the carriage and line head can be moved by using the margin of the paper following the preset blank section (the part where printing is not performed). Alternatively, the printing speed can be improved by increasing the rotational speed of the drum.

Overall view of the embodiment Front view of the main part of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment

Explanation of symbols

P Sheet P1 First sheet P2 Second sheet P3 Third sheet P4 Fourth sheet 2 Drum SR Rotating surface 10 Carriage 1 Line head 1 Y Line head 1 C Line head 1 M Line head 1 B Line head 2 B Line Head BK Blank section

Claims (3)

On the rotating surface of the drum to which the sheet-like printed material is attached, a line head in which recording elements by jet nozzle discharge ports are arranged in a line shape so as to be orthogonal to the rotating direction of the drum and the longitudinal direction is arranged to face each other. In a line dot recording apparatus configured to perform printing on the printing material mounted on a drum that rotates with a head,
The line head is supported so as to be movable in the orthogonal direction, and the drum mounts a plurality (N) of sheet-like printed materials on a rotating surface, and (N-1) printed materials are mounted on the rotating surface. A line dot recording apparatus in which a blank section in which a substrate is not mounted is formed, and the line head is moved in the orthogonal direction in the blank section in which the substrate is not mounted.   The line head is composed of a plurality of line heads for each color ink, and the line head for each color is composed of a plurality of line head units, and the line head for each color ink or the line for each color ink. The line head for each color ink or the line head unit for each color ink is sequentially moved from one that reaches a blank section or a portion that does not print continuously in the blank section. The line dot recording apparatus according to 1.   The drum is a multi-pass printing machine in which N sheets of sheet-like substrates are mounted on a rotating surface, and the drum rotates N times to complete one printing in N times. 2. A line dot recording apparatus according to 2.

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