JP2019006120A - Liquid ejection device and liquid ejection head - Google Patents

Abstract

To provide a liquid ejection device having a plurality of heads of identical structure, the device being configured such that while a position in a direction of nozzle arrangement of the plurality of heads is aligned, positions of nozzles are displaced among the plurality of heads in the direction of the nozzle arrangement.SOLUTION: In each ink jet head 4A and 4B, if distance from an edge Ea of one side in a longitudinal direction of the head to nozzles 13 of an ejection unit 11 at an end on the one side is L1, distance from an edge Eb of the other side to the nozzles 13 of the ejection unit 11 at the end on the other side is L2, and an array pitch of the nozzles 13 is P, |L1-L2|≠P×k (k: natural number) is satisfied. The two ink jet heads 4A and 4B are arranged side by side along a direction parallel to a direction of head width in a posture such that one is rotated through 180 degrees relative to the other.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid ejection apparatus and a liquid ejection head.

  As a liquid ejecting apparatus, Patent Document 1 discloses an ink jet printer including two heads having the same structure. Each head has a plurality of nozzles arranged along the longitudinal direction thereof. The plurality of nozzles of each head are divided into three divided nozzle groups, and the three divided nozzle groups are alternately arranged in the width direction of the head.

  Each head is arranged such that its longitudinal direction is parallel to the main scanning direction (width direction of the recording paper), and the two heads are arranged in the sub-scanning direction (conveyance direction). However, one of the two heads is arranged in a posture rotated 180 degrees in a horizontal plane with respect to the other head. Further, one head is arranged so as to be shifted in the main scanning direction with respect to the other head. This realizes a configuration in which the position of the nozzles is shifted by half the arrangement pitch between the two heads, and dots can be formed on the recording paper at intervals of half the arrangement pitch.

JP2013-146862A (FIG. 2, 0032, 0046)

  In the configuration of Patent Document 1, the position of the nozzles in the main scanning direction is shifted between the two heads in order to shift the position of the nozzles in the main scanning direction.

  An object of the present invention is a liquid ejection apparatus having a plurality of heads having the same structure, wherein the positions of the nozzles in the nozzle arrangement direction are shifted in the nozzle arrangement direction while the positions of the plurality of heads in the nozzle arrangement direction are aligned. Is to realize.

  The liquid discharge apparatus of the present invention includes a plurality of liquid discharge heads, and each liquid discharge head includes a liquid discharge unit having a liquid discharge surface on which nozzles arranged in the first direction are formed, and each liquid The distance from the edge on one side in the first direction of the ejection head to the nozzle located at the end on the one side in the first direction is L1, and the distance from the edge on the other side in the first direction to the first | L1−L2 | = 0.5 × P × k (k) where L2 is the distance to the nozzle located at the other end in the direction and P is the arrangement pitch of the nozzles in the first direction. : The odd number), and the plurality of liquid discharge heads are arranged side by side along a direction parallel to the second direction perpendicular to the first direction and parallel to the liquid discharge surface, Part of the liquid ejection head However, with respect to the other liquid discharge heads, the liquid discharge head is arranged in a posture rotated by 180 degrees in a plane parallel to the liquid discharge surface.

1 is a plan view of a printer 1 according to an embodiment. It is the II-II sectional view taken on the line of FIG. 2 is a plan view of one inkjet head 4. FIG. It is a figure which shows the arrangement | positioning relationship of two inkjet heads 4A and 4B. It is a top view of two inkjet heads 24A and 24B of a modified form. It is a top view of the printer 31 of another modification. It is a figure which shows the arrangement | positioning relationship of the five inkjet heads 4 of the printer of FIG. It is a top view of the inkjet head 44 of another modification.

  Next, an embodiment of the present invention will be described. The present embodiment is an example in which the present invention is applied to an ink jet printer that prints an image on a recording sheet by ejecting ink from a nozzle toward the recording sheet.

  In FIG. 1, the downstream side in the transport direction is defined as the front side of the printer 1, and the upstream side in the transport direction is defined as the rear side of the printer 1. Further, the paper width direction orthogonal to the transport direction is defined as the left-right direction of the printer 1. The left side of the figure is the left side of the printer 1, and the right side of the figure is the right side of the printer 1. Further, a direction perpendicular to the transport direction and the paper width direction (a direction perpendicular to the paper surface of FIG. 1) is defined as the vertical direction of the printer 1. The front side in FIG. 1 is the upper side, and the other side in FIG. 1 is the lower side. Below, it demonstrates using each direction word of front, back, left, right, up and down suitably.

  As shown in FIGS. 1 and 2, the printer 1 includes a platen 3, two inkjet heads 4, two transport rollers 5 and 6, a control device 7, and the like housed in a housing 2.

  A recording sheet 100 is placed on the upper surface of the platen 3. The two inkjet heads 4 (4A, 4B) are arranged side by side in the transport direction above the platen 3. The two transport rollers 5 and 6 are disposed on the upstream side (rear side) and the downstream side (front side) in the transport direction with respect to the platen 3. The two transport rollers 5 and 6 are respectively driven by a motor (not shown) to transport the recording paper 100 on the platen 3 forward.

The control device 7 includes a CPU (Central Processing Unit), a ROM (Read Only Memory),
A random access memory (RAM) and an application specific integrated circuit (ASIC) including various control circuits are provided. The control device 7 controls the motors that drive the transport rollers 5 and 6 to control the ink jet heads 4 </ b> A and 4 </ b> B to control the recording paper 100 while transporting the recording paper 100 in the transport direction to the two transport rollers 5 and 6. Ink is discharged toward As a result, an image is printed on the recording paper 100.

(Details of inkjet head)
Next, the inkjet head 4 will be described in detail. As shown in FIGS. 1 and 2, two head holding portions 8 are attached to the housing 2. The two head holding portions 8 are arranged side by side in front and back at a position above the platen 3 and between the two transport rollers 5 and 6. These two head holding units 8 hold the two inkjet heads 4 (4A, 4B) in a posture in which the width direction (short direction) is parallel to the transport direction.

  The two inkjet heads 4 (4A, 4B) have the same structure and eject the same type of ink (for example, black ink). However, as will be described later, as shown in FIG. 4, the two inkjet heads 4 </ b> A and 4 </ b> B are arranged in a posture in which one of them is rotated 180 degrees in the horizontal plane with respect to the other.

  As shown in FIGS. 2 and 3, each inkjet head 4 includes a holder 10, five discharge units 11, and a reservoir 12. In FIG. 3, the reservoir 12 is not shown. The holder 10 is a member having a rectangular planar shape that is long in the paper width direction. Five discharge units 11 are attached to the holder 10. Since the holder 10 has a rectangular shape, the overall planar shape of each inkjet head 4 is also rectangular, and each inkjet head 4 has a point-symmetric outer shape centered on a symmetry point C located at the center in the paper width direction. Have The “outer shape” is a rectangular contour shape formed by the four edges Ea, Eb, Ec, Ed of the inkjet head 4. In the present embodiment, the symmetry point C coincides with the center of the area of the rectangular holder 10 in plan view.

  The lower surface of each discharge unit 11 is an ink discharge surface 14 on which a plurality of nozzles 13 are formed. The plurality of nozzles 13 are arranged at an arrangement pitch P along the longitudinal direction of the inkjet head 4 (hereinafter referred to as the head longitudinal direction). An ink flow path (not shown) communicating with the plurality of nozzles 13 is formed inside the discharge unit 11, and an ink supply port 15 connected to the ink flow path is formed on the upper surface of the discharge unit 11.

  As shown in FIGS. 1 and 2, the reservoir 12 is disposed above the five discharge units 11. The reservoir 12 is connected to an ink tank (not shown) by a tube 16 and temporarily stores ink supplied from the ink tank. The lower part of the reservoir 12 is connected to the ink supply ports 15 (see FIGS. 3 and 4) of the five ejection units 11, respectively. As a result, the ink stored in the reservoir 12 is supplied to each of the five ejection units 11.

  As shown in FIG. 3, the five ejection units 11 are arranged side by side along the longitudinal direction of the head. The five ejection units 11 are alternately divided into one side and the other side in the width direction of the inkjet head 4 (hereinafter referred to as the head width direction) parallel to the ink ejection surface 14 and perpendicular to the head longitudinal direction. Are arranged. That is, the five ejection units 11 are arranged in a zigzag pattern along the longitudinal direction of the head, three ejection units 11 are arranged on one side in the head width direction, and two ejection units 11 are arranged on the other side. Has been placed. Further, the five ejection units 11 are arranged such that the mutual positional relationship and the positional relationship with respect to the outer edges (Ea, Eb, Ec, Ed) of the inkjet head 4 are as follows.

  First, with respect to the longitudinal direction of the head, the distance from the edge Ea on one side of the inkjet head 4 to the nozzle 13 of the discharge unit 11 on the one side is L1, and the distance from the edge Eb on the other side to the end on the other side. When the distance from the discharge unit 11 to the nozzle 13 is L2, the relationship | L1-L2 | = 0.5 × P × k (k: odd number) is established. In the present embodiment, specifically, L1 = 10P, L2 = 5.5P, and k = 9.

  Further, the discharge unit 11 arranged on one side in the head width direction and the discharge unit 11 arranged on the other side in the head width direction are arranged in the head longitudinal direction so that some nozzles 13 overlap in the head width direction. They are offset. Thus, even when a discharge failure such as a discharge bend or non-discharge occurs in the nozzle 13 of one discharge unit 11 at the joint position of the two discharge units 11, the nozzle 13 of the other discharge unit 11 can cover. Therefore, it is possible to suppress the occurrence of white stripes in the image printed on the recording paper 100 between the two ejection units 11. Here, when the length in the head longitudinal direction of the overlapping range 17 where the nozzles 13 overlap between the two ejection units 11 is L3, the relationship | L1-L2 |> L3 is established. In this embodiment, L3 = 1.5P. Further, when the nozzle arrangement length of one discharge unit 11 is L6, the relationship | L1-L2 | <L6-2 × L3 is established. When the number of nozzles of one discharge unit 11 is n, L6 = (n−1) P. In the example shown in the figure, n = 12, that is, L6 = 11P.

  Further, with respect to the head width direction, the distance from the edge Ec on one side of the inkjet head 4 (the side on which the three discharge units 11 are arranged) to the nozzle 13 of the discharge unit 11 at the one end is L4, and the other When the distance from the edge Ed on the side (the side where the two discharge units 11 are arranged) to the nozzle 13 of the discharge unit 11 at the other end is L5, L4> L5. In this embodiment, L4 = 5P and L5 = 3.5P.

  As shown in FIG. 4, the two inkjet heads 4 (4A, 4B) having the above-described configuration are arranged side by side in a direction (conveying direction) parallel to the head width direction. However, one of the inkjet heads 4 is rotated 180 degrees around the symmetry point C in a horizontal plane parallel to the ink ejection surface 14 with respect to the other inkjet head 4. Here, the outer shape of each inkjet head 4 is a point-symmetric shape with respect to the symmetry point C. Therefore, in the paper width direction, the position of the edge Ea of the inkjet head 4A and the position of the edge Eb of the inkjet head 4B match, and the position of the edge Eb of the inkjet head 4A and the position of the edge Ea of the inkjet head 4B match.

  On the other hand, the position of the ejection unit 11 of the front inkjet head 4B is shifted by L1-L2 in the paper width direction with respect to the ejection unit 11 of the rear inkjet head 4A. Here, in each inkjet head 4, a relationship of | L1-L2 | = 0.5 × P × k (k: odd number) is established. Therefore, the position of the nozzle 13 of the rear ink jet head 4A and the position of the nozzle 13 of the front ink jet head 4B are shifted by a half (0.5 P) of the arrangement pitch P in the head longitudinal direction.

  In this way, the edge of the two inkjet heads 4A and 4B in the paper width direction (Ea) can be obtained simply by arranging one of the two inkjet heads 4 having the same structure in a posture rotated by 180 degrees with respect to the other. , Eb), a pitch smaller than the arrangement pitch P in each inkjet head 4 can be realized. That is, a printer capable of high resolution printing can be realized.

  Further, as described above, in each inkjet head 4, since some of the nozzles 13 overlap in the ejection unit 11 on one side and the ejection unit 11 on the other side in the head width direction, white streaks of the image are generated. Can be suppressed. However, when there are differences in the discharge characteristics (discharge amount and discharge speed) of the nozzles 13 between the different discharge units 11, the image portion formed by the nozzles 13 located in the overlapping range 17 of the two discharge units 11. And a density difference occurs between the image portions formed by the other nozzles 13. Due to this density difference, band-shaped density unevenness occurs in the image formed on the recording paper 100.

  In this respect, in the present embodiment, the ejection unit 11 of the front inkjet head 4B is displaced by L1-L2 in the longitudinal direction of the head with respect to the ejection unit 11 of the rear inkjet head 4A. It shifts in the same way. Further, each inkjet head 4 has a relationship of | L1-L2 |> L3 (L3: length of the overlapping range 17). Therefore, as shown in FIG. 4, the overlapping ranges 17 do not overlap between the two inkjet heads 4. As a result, the band-like density unevenness generated in the image by the nozzles 13 in the overlapping range 17 is dispersed in the paper width direction, and the deterioration of the print quality can be suppressed. However, if | L1-L2 | is too large, it overlaps with another overlapping range 17 adjacent thereto. Therefore, when the nozzle arrangement length of one discharge unit 11 is L6, | L1-L2 | <L6-2 × L3.

  In the above-described | L1-L2 | = 0.5 × P × k (k: odd number) relationship, the smaller the value of k, the smaller the nozzle in the paper width direction between the two inkjet heads 4A and 4B. The positional deviation amount | L1-L2 | That is, if the amount of positional deviation is small, the number of nozzles 13 that are not used in each inkjet head 4 can be reduced, which is advantageous in terms of downsizing. However, if the amount of positional deviation is too small, the relationship | L1-L2 |> L3 cannot be satisfied, and the overlapping range 17 overlaps between the two inkjet heads 4.

  In the head width direction, a distance L4 from one edge Ec of each inkjet head 4 to the nozzle 13 of the discharge unit 11 and a distance L5 from the other edge Ed to the nozzle 13 of the discharge unit 11 are different. . And each inkjet head 4 is arrange | positioned so that the edge Ec which the distance with the nozzle 13 is separated may become an outer side. In this configuration, the distance between the nozzles 13 of the discharge unit 11 can be reduced between the two inkjet heads 4. Accordingly, even when the ink landing position on the recording paper 100 is shifted due to the attachment of the ink jet head 4 in an inclined manner, the amount of ink landing misalignment between the two ink jet heads 4A and 4B is suppressed to be small. Can do.

  Further, the gap to the recording paper 100 may slightly differ between the two inkjet heads 4A and 4B due to the warp of the recording paper 100 during conveyance. In that case, when ink is ejected from the two inkjet heads 4A and 4B to the same region of the recording paper 100, the gap between the two inkjet heads 4A and 4B causes the recording paper 100 between the two inkjet heads 4A and 4B. The size and shape of the formed dots will be different. Also in this regard, the gap difference can be reduced by reducing the distance between the nozzles 13 of the discharge unit 11 between the two inkjet heads 4A and 4B, and the difference in the size and shape of the dots can be suppressed. It becomes.

  In the present embodiment, the number of ejection units 11 of each inkjet head 4 is five, that is, an odd number. Thereby, the following effects are also obtained.

  When printing an image on the recording paper 100 transported in the transport direction, the ejection unit 11 on the upstream side (rear side) in the transport direction of each inkjet head 4 discharges ink first, and then the transport direction. The discharge unit 11 on the downstream side (front side) discharges ink. Here, there may be a difference in the amount of ink discharged from each nozzle 13 between the upstream discharge unit 11 that discharges first and the downstream discharge unit 11 that discharges later. For example, as shown in FIG. 2, when ink is commonly used from the common reservoir 12 for the five ejection units 11 of each inkjet head 4, the reservoir is determined by ejection (ink consumption) of the upstream ejection unit 11. The ink pressure in 12 temporarily decreases. Due to this pressure drop, the supply of ink to the downstream discharge unit 11 that discharges ink next time may be delayed for a moment, and the discharge amount may decrease. The difference in the discharge amount between the discharge unit 11 on the upstream side in the transport direction and the discharge unit 11 on the downstream side also causes a band-like density unevenness in the image.

  In this regard, in the present embodiment, the number of ejection units 11 of each inkjet head 4 is an odd number. Therefore, the number of ejection units 11 located on the upstream side in the transport direction between the two inkjet heads 4 and the position in the paper width direction thereof are different, and the number of ejection units 11 located on the downstream side in the transport direction. And their positions in the paper width direction are also different. More specifically, the ink discharged from the discharge unit 11 downstream of the front inkjet head 4B is landed on the area where the ink discharged from the upstream discharge unit 11 of the rear inkjet head 4A has landed. To do. Therefore, in one ink jet head 4, even when the discharge amount of the nozzle 13 is different between the discharge unit 11 on the upstream side in the transport direction and the discharge unit 11 on the downstream side, the discharge between the two ink jet heads 4. The difference in quantity is offset. Thereby, the density unevenness of the image is suppressed.

  The printer 1 of the present embodiment realizes high-resolution printing with one color ink by arranging one of the two inkjet heads 4 having the same structure in a posture rotated by 180 degrees with respect to the other. Is. Here, the positions of the edges E1 and E2 in the longitudinal direction of the head in the paper width direction are the same between the rotated posture and the non-rotated posture of each inkjet head 4. Therefore, the inkjet head 4 can be attached to one head holding unit 8 in any of the above two postures.

  Accordingly, the two inkjet heads 4 can be attached to the two head holding portions 8 in the same direction. In this case, the position of the nozzle 13 matches between the two inkjet heads 4. In addition, it is possible to configure a printer that supplies inks of different colors to the two inkjet heads 4 and discharges the inks of the two colors. That is, between the printer for monochrome high-resolution printing described in the present embodiment and the printer for ejecting the above-described two colors of ink, the casing 2, the platen 3, the transport rollers 5, other than the inkjet head 4. Since the configuration such as 6 can be shared, the cost can be reduced.

  In the embodiment described above, the ink jet printer 1 corresponds to the “liquid ejecting apparatus” of the invention. The inkjet head 4 corresponds to the “liquid discharge head” of the present invention. The discharge unit 11 corresponds to the “liquid discharge unit” of the present invention. The ink discharge surface 14 corresponds to the “liquid discharge surface” of the present invention. The head longitudinal direction in FIG. 3 corresponds to the “first direction” of the present invention. The head width direction corresponds to the “second direction” of the present invention.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] In the above embodiment, the number of ejection units 11 of each inkjet head 4 is an odd number, but the number of ejection units 11 may be an even number, as in the inkjet head 24 of FIG. In this case, in each inkjet head 24, the number of ejection units 11 arranged on one side in the head width direction is the same as the number of ejection units 11 arranged on the other side. For this reason, when one inkjet head 24 is rotated 180 degrees with respect to the other inkjet head 24 and the two inkjet heads 24A, 24B are arranged side by side in the transport direction, the two inkjet heads 24A, The arrangement relationship of the plurality of discharge units 11 is the same with 24B. In this case, when the control device 7 generates data for causing each inkjet head 24 to eject ink, the data is transferred between the two inkjet heads 24A and 24B according to the arrangement of the ejection unit 11. There is no need to make them different. Therefore, the data generation process in the control device 7 is simplified.

  Moreover, it is not essential that each inkjet head has a plurality of ejection units, and the number of ejection units may be one. Even in this case, the inkjet heads are configured to satisfy the relational expression | L1-L2 | = 0.5 × P × k described above, while aligning the positions of the edges of the two inkjet heads in the paper width direction. A pitch smaller than the arrangement pitch P can be realized.

2] The number of inkjet heads is not limited to two. That is, three or more inkjet heads may be arranged in the transport direction, and some of the inkjet heads may be arranged in a posture rotated by 180 degrees with respect to other inkjet heads.

  For example, the printer 31 in FIG. 6 includes five inkjet heads 4 (4c, 4m, 4y, 4k1, and 4k2) arranged in the transport direction. As shown in FIG. 7, among the five inkjet heads 4, the four inkjet heads 4 (4c, 4m, 4y, 4k1) arranged on the upstream side in the transport direction are cyan (C), magenta (M), and yellow. (Y) and black (K) inks of four colors are respectively ejected. The inkjet head 4k2 on the downstream side in the transport direction also ejects black ink, but is arranged in a posture rotated 180 degrees with respect to the inkjet head 4k1.

  Since the four inkjet heads 4c, 4m, 4y, 4k1 on the upstream side in the transport direction are arranged in the same direction, the nozzle 13 of the discharge unit 11 is between these four inkjet heads 4c, 4m, 4y, 4k1. The positions in the paper width direction are the same. By using these four inkjet heads 4c, 4m, 4y, and 4k1, color printing using four colors of ink on the recording paper 100 is possible.

  On the other hand, the inkjet head 4k2 on the downstream side in the transport direction is rotated 180 degrees with respect to the inkjet head 4k1. Here, as in the above-described embodiment, if the relationship of | L1-L2 | = 0.5 × P × k (k: odd number) is established, the paper between the two black inkjet heads 4k1 and 4k2 The edge positions in the width direction are aligned, and the position of the nozzle 13 in the sheet width direction is shifted by 0.5 P. Therefore, as a whole of the two black inkjet heads 4k1 and 4k2, the arrangement pitch of the nozzles 13 is 0.5P. Therefore, by using these two inkjet heads 4k1 and 4k2, monochrome high-resolution printing can be performed on the recording paper 100.

  6 and 7, in the same manner as in the above-described embodiment, in each inkjet head 4, the distance (L4) from one edge Ec to the nozzle 13 in the head width direction> the other edge Ed to the nozzle. In the case of the distance (L5) up to 13, the four inkjet heads 4c, 4m, 4y, 4k1 and the inkjet head 4k2 are preferably arranged so that the edge Ec side is the outside. Accordingly, when monochrome printing is performed using the two black inkjet heads 4k1 and 4k2, the distance in the transport direction between the nozzle 13 of the inkjet head 4k1 and the nozzle 13 of the inkjet head 4k2 can be shortened. it can.

3] In the above-described embodiment, the distance L4 from one edge Ec to the nozzle 13 of one inkjet head 4 and the distance L5 from the other edge Ed to the nozzle 13 are different in the head width direction. , L4 and L5 may be equal.

4] As shown in FIG. 8, in each inkjet head 44, the nozzle 13 of the discharge unit 11 on one side and the nozzle 13 of the discharge unit 11 on the other side in the head width direction do not have to overlap. In FIG. 8, the nozzles 13 at the ends of the two ejection units 11 adjacent to each other in the longitudinal direction of the head are arranged with an interval equal to the arrangement pitch P in each ejection unit 11.

5] In the above-described embodiment, the plurality of discharge units 11 are attached to the holder 10. That is, the “liquid ejecting portion” of the present invention is configured as an individual unit. On the other hand, it is also possible to adopt a configuration in which the “liquid ejection part” of the present invention is not unitized. For example, some members, such as a flow path member, a nozzle formation member, or an actuator substrate, may be shared between a plurality of liquid ejection portions arranged in a staggered manner in one inkjet head.

  The embodiments described above and the modifications thereof are applied to an ink jet printer that prints an image or the like by ejecting ink onto a recording sheet, but can be used for various purposes other than printing an image or the like. The present invention can also be applied to a liquid ejecting apparatus. For example, the present invention can also be applied to an industrial liquid discharge apparatus that discharges a conductive liquid onto a substrate to form a conductive pattern on the substrate surface.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 4 Inkjet head 11 Ejection unit 13 Nozzle 14 Ink ejection surface 17 Overlapping range 24 Inkjet head 31 Printer 44 Inkjet head C Symmetry point Ea, Eb Edge Ec, Ed Edge

Claims (12)

A plurality of liquid discharge heads,
Each liquid discharge head
A liquid ejection part having a liquid ejection surface on which nozzles arranged along the first direction are formed;
The distance from one edge of each liquid ejection head in the first direction to the nozzle located at the one end in the first direction is L1, and the distance from the other edge in the first direction is When the distance to the nozzle located at the other end in the first direction is L2, and the arrangement pitch of the nozzles in the first direction is P, | L1-L2 | ≠ P × k (k: natural number) ) And
The plurality of liquid ejection heads are arranged side by side along a direction parallel to the liquid ejection surface and parallel to a second direction orthogonal to the first direction,
A part of the plurality of liquid ejection heads is disposed in a posture rotated by 180 degrees in a plane parallel to the liquid ejection surface with respect to the other liquid ejection heads. A liquid ejection device. Each liquid discharge head has a plurality of the liquid discharge units,
2. The liquid according to claim 1, wherein the plurality of liquid ejection units are arranged along the first direction and are alternately arranged on one side and the other side in the second direction. Discharge device. In each liquid discharge head, the liquid discharge portion on one side in the second direction and the liquid discharge portion on the other side in the second direction are arranged in the first direction so that some nozzles overlap in the second direction. Are displaced and
When the length in the first direction of the range in which the nozzles of the one-side liquid ejection section and the nozzles of the other-side liquid ejection section overlap each other in the second direction is L3. 3. The liquid ejection apparatus according to claim 2, wherein | L1-L2 |> L3.   The liquid ejection apparatus according to claim 2, wherein the number of the liquid ejection units of one liquid ejection head is an odd number.   The liquid ejection apparatus according to claim 2, wherein the number of the liquid ejection units of one liquid ejection head is an even number. The distance L4 from the edge on the one side in the second direction to the nozzle of the liquid discharge part on the one side in the second direction of each liquid discharge head, and the edge on the other side in the second direction L4> L5, where L5 is the distance from the liquid ejection part on the other side in the second direction to the nozzle.
The said some liquid discharge head and said other liquid discharge head are respectively arrange | positioned so that the said one side in the said 2nd direction may become an outer side. Liquid discharge device. Each liquid discharge part has a supply port in the one side of a 1st direction, The liquid discharge apparatus in any one of Claims 2-6 characterized by the above-mentioned. Multiple liquid ejection heads
A first liquid discharge head and a second liquid discharge head;
The supply port of the first liquid discharge head is
The liquid ejection apparatus according to claim 7, wherein the liquid ejection apparatus overlaps the supply port of the second liquid ejection head in the second direction. | L1-L2 | = 0.5 × P × k,
The liquid ejecting apparatus according to claim 1, wherein k is an odd number. A liquid ejection part having a liquid ejection surface on which nozzles arranged along the first direction are formed;
The distance from one edge in the first direction to the nozzle located at the one end in the first direction is L1, and from the other edge in the first direction to the other in the first direction | L1-L2 | ≠ P × k (k: natural number), where L2 is the distance to the nozzle located at the end on the side, and P is the arrangement pitch of the nozzles in the first direction. Liquid discharge head. A plurality of the liquid ejection portions;
The plurality of liquid ejection portions are arranged along the first direction, and are alternately arranged on one side and the other side in a second direction parallel to the liquid ejection surface and orthogonal to the first direction. The liquid discharge head according to claim 10, wherein the liquid discharge head is a liquid discharge head. | L1-L2 | = 0.5 × P × k,
The liquid ejection apparatus according to claim 10, wherein k is an odd number.

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