JP2009018893A - Ink jet recording device - Google Patents

Abstract

To provide an ink jet recording apparatus in which the distance between a recording medium and a print head is small even when the recording medium is conveyed by only one of a paper feed roller and a paper discharge roller.
A surface 7 serving as a nozzle forming region is disposed between a paper supply side roller 2 and a paper discharge side roller 3. Since the distance in the transport direction of the sheet S between the surface 7 and the sheet feeding side roller 2 and the sheet discharging side roller 3 is also short, the sheet S is separated from the sheet feeding side roller 2 or the sheet discharging side roller 3 to print with the sheet S. By the time the distance to the head 6 changes and banding unevenness starts to occur, printing can be performed up to the vicinity of the edge of the paper S. Accordingly, it is possible to obtain the ink jet printer 1 with less banding unevenness.
[Selection] Figure 2

Description

  The present invention relates to an ink jet recording apparatus that conveys a recording medium using a paper feed roller and a paper discharge roller.

A paper feed roller is used to transport a recording medium used in the ink jet recording apparatus. The paper feed roller includes a paper feed roller and a paper discharge roller, and prints on a recording medium by disposing a print head between the paper feed roller and the paper discharge roller.
When the recording medium is conveyed by the paper feed roller, if the recording medium is conveyed by only one of the paper supply side roller and the paper discharge side roller, the position of the recording medium with respect to the print head due to the deflection of the recording medium etc. It will change. As the distance between the recording medium and the print head changes, streak unevenness (hereinafter referred to as banding unevenness) occurs in the width direction of the recording medium.
A method is known in which the conveyance speed is lowered before and after the recording medium is removed from the paper feed roller (see, for example, Patent Document 1).
In addition, a method is known in which the ink ejection (ejection) timing is controlled in response to a change in the distance between the recording medium and the print head after the roller is removed from the paper feed roller (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2005-75519 (Items 18 to 20) Japanese Patent Laying-Open No. 2004-255752 (Section 5)

  In order to prevent banding unevenness, special control is performed according to a change in the distance between the recording medium and the print head when the recording medium is conveyed by only one of the paper supply side roller and the paper discharge side roller. Must be done separately.

  SUMMARY An advantage of some aspects of the invention is to solve some of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A paper feed side roller, a paper discharge side roller having a rotation axis parallel to the rotation axis of the paper feed side roller, a side surface of the paper supply side roller, and a side surface of the paper discharge side roller A print head provided on the opposite side of the paper feed side roller and the paper discharge side roller with respect to the tangential plane; and a plurality of nozzles opposed to the tangential plane provided on the print head. Nozzle formation area in which the nozzles are formed includes a rotation axis of the feed side roller and a feed side plane including a feed side tangent line where the feed side roller and the tangent plane are in contact with each other. The paper-side roller is disposed between the rotation axis of the paper-side roller and the discharge-side plane including the discharge-side tangent line where the discharge-side roller and the tangent plane are in contact with each other. The radius of the paper discharge side roller is r2, and the paper feed in the nozzle forming area When the direction perpendicular to the tangential length and A, an ink jet recording apparatus characterized by having a relationship of equation (1).
A <2√ (r1 · r2) (1)
Note that the terms “parallel” and “perpendicular” include “substantially parallel” and “substantially orthogonal” that have errors in manufacturing and assembly.
In addition, the tangential plane that contacts the paper feed roller and the paper discharge roller is a tangential plane in which the paper feed roller and the paper discharge roller are on the same side with respect to the tangential plane, and the paper feed roller and the discharge roller. Although there is a tangential plane in which the paper side roller is located on the opposite side, the tangential plane in which the paper supply side roller and the paper discharge side roller are located on the same side. This is also clear from the fact that the print head is provided on the side opposite to the paper supply side roller and the paper discharge side roller.

According to this, since the radius of the paper feed side roller and the paper discharge side roller can be reduced according to the formula (1) up to the length A in the direction orthogonal to the paper feed side tangent of the nozzle formation region, The distance between the roller and the paper discharge side roller is shortened. Therefore, the state in which the sheet is conveyed by only one of the paper feed roller and the paper discharge roller is minimized.
In addition, a nozzle formation area is disposed between the paper supply side roller and the paper discharge side roller, and the distance in the conveyance direction of the recording medium between the nozzle formation area, the paper supply side roller, and the paper discharge side roller is also short. Therefore, when the edge of the print medium is detached from the paper feed roller and the distance between the print head and the recording medium starts to change, the nozzle formation area is located close to the end of the print medium and close to both ends of the recording medium. Printing can be performed and an ink jet recording apparatus with less banding unevenness can be obtained. The same applies to the case where the paper is conveyed only by the paper supply side roller before the paper is conveyed by the paper discharge side roller.

Application Example 2 In the ink jet recording apparatus described above, the sheet feeding side subordinate roller driven by the paper feeding side roller and the paper discharge side subordinate roller driven by the paper discharge side roller are provided, and the paper feeding side 2. An ink jet recording apparatus having a relationship of Formula (2), where r3 is a radius of the subordinate roller and r4 is a radius of the discharge side subordinate roller.
A <((2√ (r1 · r2)) − (r3 + r4)) (2)
Here, the term “followed” includes the case where the paper feed side subordinate roller and the paper discharge side subordinate roller are driven by contacting the paper feed side roller and the paper discharge side roller, respectively, and the case of following the recording medium.
According to this, the radius of the paper feed side roller, the paper discharge side roller, the paper feed side subordinate roller, and the paper discharge side subordinate roller can be reduced according to the equation (2) up to the length A of the nozzle formation region. An ink jet recording apparatus that can achieve the effect is obtained.
Further, the recording medium is pressed by the paper supply side roller and the paper discharge side roller by the paper supply side subordinate roller and the paper discharge side subordinate roller, and the recording medium is only one of the paper supply side roller and the paper discharge side roller. Even when the recording medium is conveyed, the recording medium can be supported by the elasticity of the recording medium, so that printing is performed with less change in the distance between the recording medium and the print head.

Application Example 3 In the ink jet recording apparatus described above, the rotation axis of the paper feed side subordinate roller is in the paper supply side plane, and the rotation axis of the paper discharge side subordinate roller is the paper discharge side plane. An ink jet recording apparatus comprising:
According to this, the paper feed side subordinate roller, the paper feed side roller, the paper discharge side subordinate roller, and the paper discharge side roller are arranged in a direction orthogonal to the tangential plane contacting the paper feed side roller and the paper discharge side roller. Has been. Therefore, even if the paper supply side subordinate roller and the paper discharge side subordinate roller press the recording medium against the paper supply side roller and the paper discharge side roller, respectively, the recording medium does not deviate from the tangential plane, and the deformation of the recording medium is small. Thus, an ink jet recording apparatus with less banding unevenness can be obtained. Even when the paper is transported by only one of the paper discharge roller and paper feed roller, the paper is transported along a flat surface, so the distance between the paper and the surface is maintained, and a platen is not required. is there. A platen may be provided to further stabilize the distance between the paper and the head surface.

Application Example 4 In the ink jet recording apparatus described above, an ink jet recording apparatus including a conveyance belt that spans the paper supply side roller and the paper discharge side roller along the tangent plane.
According to this, the recording medium is supported by the conveyance belt along the tangential plane, and printing is performed in a state where the change in the distance between the recording medium and the print head is smaller, and an ink jet recording apparatus with less banding unevenness can be obtained.

Application Example 5 In the inkjet recording apparatus described above, the inkjet recording apparatus is disposed on an opposite side to the nozzle formation region with respect to the tangential plane, and has a surface facing the nozzle formation region, and the opposing surface is An ink jet recording apparatus comprising: a support member located at substantially the same position as the tangential plane.
According to this, since the recording medium can be supported along the tangential plane by the surface facing the nozzle formation region of the support member, printing is performed with less change in the distance between the recording medium and the print head. An ink jet recording apparatus with less banding unevenness can be obtained.

Application Example 6 In the ink jet recording apparatus described above, the nozzles are provided at equal intervals in a direction parallel to the tangential line on the paper feed side to form a nozzle row. .
Note that the equal interval includes substantially equal intervals having an error in nozzle formation.
According to this, since the nozzles are provided so as to form a row in a direction parallel to the tangential line on the paper feed side (the width direction of the recording medium), the nozzle formation region in the equations (1) and (2) The length A in the direction perpendicular to the tangent line on the paper feed side becomes shorter. Therefore, the distance between the paper supply side roller and the paper discharge side roller can be shortened, and an ink jet recording apparatus with less banding unevenness can be obtained.

  Application Example 7 The sheet-feeding roller, the sheet-discharging roller having a rotation axis parallel to the rotation axis of the sheet-feeding roller, the side surface of the sheet-feeding roller, and the side surface of the sheet-discharging roller A print head provided on the opposite side of the paper feed side roller and the paper discharge side roller with respect to the tangential plane; and a plurality of nozzles opposed to the tangential plane provided on the print head. Nozzle formation area in which the nozzles are formed includes a rotation axis of the feed side roller and a feed side plane including a feed side tangent line where the feed side roller and the tangent plane are in contact with each other. Nozzle formation in which a plurality of nozzles are formed, arranged between a rotation axis of a paper side roller and a discharge side plane including a discharge side tangent line where the discharge side roller and the tangent plane are in contact with each other Part or all of the area is flat toward the tangential plane. When viewed from an ink jet recording apparatus characterized by overlapping with the sheet feeding side roller.

  According to this, even when the distance between the paper supply side roller and the paper discharge side roller is long, the nozzle forming area is close to the tangential line of the paper supply side. Printing can be performed up to the end of the recording medium. Therefore, an ink jet recording apparatus with less banding unevenness can be obtained.

Application Example 8 In the ink jet recording apparatus described above, a part or all of the nozzle formation region overlaps with the discharge-side roller when viewed in plan toward the tangential plane. Inkjet recording apparatus.
According to this, since the nozzle formation area is close to the tangent line on the paper discharge side, printing can be performed up to both ends of the recording medium even if the recording medium is detached from the paper supply side roller or the paper discharge side roller. Accordingly, an ink jet recording apparatus with less banding unevenness can be obtained.

(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of an inkjet printer 1 according to this embodiment.
The inkjet printer 1 that has received print data from the computer 100 that is an external device controls the transport unit 20 and the print head 6 by the controller 60 to form an image on the paper S that is a recording medium. Further, the detector group 70 monitors the situation in the inkjet printer 1, and the controller 60 controls the transport unit 20 and the print head 6 based on the detection result.

  The controller 60 is a control unit for controlling the ink jet printer 1. The interface unit 61 is for transmitting and receiving data between the computer 100 and the inkjet printer 1. The CPU 62 is an arithmetic processing device for controlling the entire inkjet printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like. The CPU 62 controls the transport unit 20 and the print head 6 by a unit control circuit 64 according to a program stored in the memory 63.

Hereinafter, the transport unit 20 and the print head 6 will be described in detail.
FIG. 2 is a schematic partial perspective view of the ink jet printer 1 which is the ink jet recording apparatus according to the present embodiment. The conveyance direction of the paper S is indicated by a white arrow.
FIG. 3 is a schematic partial cross-sectional view of the ink jet printer 1.

2 and 3, the inkjet printer 1 includes a transport unit 20 and a print head 6.
Further, the transport unit 20 includes a paper feed side roller 2, a paper discharge side roller 3, a paper feed side subordinate roller 4, and a paper discharge side subordinate roller 5.
The shapes of the paper supply side roller 2 and the paper discharge side roller 3 are cylindrical. The rotation shaft 21 of the paper supply side roller 2 and the rotation shaft 31 of the paper discharge side roller 3 are arranged so as to be substantially parallel. In the present embodiment, the size of the paper feed side roller 2 and the size of the paper discharge side roller 3 are different.
The sheet S is conveyed along a tangential plane P that is in contact with the sheet feeding side roller 2 and the sheet discharging side roller 3.

In FIGS. 2 and 3, the shapes of the paper feed side subordinate roller 4 and the paper discharge side subordinate roller 5 are also cylindrical. The paper feed side subordinate roller 4 is disposed at a position facing the paper feed side roller 2 with the tangential plane P interposed therebetween, and the paper discharge side subordinate roller 5 is disposed at a position facing the paper discharge side roller 3 across the tangential plane P. Has been.
Specifically, the rotation shaft 41 of the paper feed side dependent roller 4 and the rotation shaft 51 of the paper discharge side dependent roller 5 are also arranged so as to be substantially parallel to the rotation shafts 21 and 31. The rotation axis 41 of the sheet feeding side subordinate roller 4 is in the sheet feeding side plane P1 including the rotation axis 21 of the sheet feeding side roller 2 and the sheet feeding side tangent L1 where the sheet feeding side roller 2 and the tangent plane P are in contact with each other. The rotation shaft 51 of the discharge side subordinate roller 5 is in the discharge side plane P2 including the rotation axis 31 of the discharge side roller 3 and the discharge side tangent L2 in contact with the discharge side roller 3 and the tangent plane P. . Accordingly, the paper feed side roller 2 and the paper feed side subordinate roller 4 are arranged in a direction orthogonal to the tangential plane P, and the paper discharge side roller 3 and the paper discharge side subordinate roller 5 are arranged.

  The paper feed side subordinate roller 4 and the paper feed side roller 2 may be in contact with each other or may be arranged with a gap therebetween. Similarly, the paper discharge side subordinate roller 5 and the paper discharge side roller 3 may be in contact with each other, or may be arranged with a space therebetween. When the interval is set, the interval is narrower than the thickness of the sheet S. In either case of contact or separation, when the paper supply side roller 2 and the paper discharge side roller 3 are driven, the paper supply side subordinate roller 4 and the paper discharge side subordinate roller 5 respectively supply paper. It follows the side roller 2 and the paper discharge side roller 3.

In FIG. 3, the radius of the paper feed side roller 2 is r1, the radius of the paper discharge side roller 3 is r2, the radius of the paper feed side subordinate roller 4 is r3, the radius of the paper discharge side subordinate roller 5 is r4, and the print head 6 When the width of the surface 7 facing the tangential plane P in the sheet S conveyance direction is a length A, the relationship of Expression (2) is satisfied.
It is preferable that the gap between the paper supply side roller 2 and the paper discharge side roller 3 is narrow, but a gap may be left. Further, the surface 7 facing the tangent plane P of the print head 6 should be close to the paper feed side roller 2.

Here, when the radius r3 of the paper supply side dependent roller 4 and the radius r4 of the paper discharge side dependent roller 5 are sufficiently smaller than the radius r1 of the paper supply side roller 2 and the radius r2 of the paper discharge side roller 3, the equation (1) ).
In this embodiment, as a specific example of the radius r1 of the paper supply side roller 2 and the radius r2 of the paper discharge side roller 3, if the length A is 4 mm, for example, the radius r1 may be 4 mm and the radius r2 may be 3 mm. it can.

The print head 6 is disposed on the opposite side of the paper feed side roller 2 and the paper discharge side roller 3 with respect to the tangential plane P. Nozzles 8 are formed on a surface 7 that is a nozzle formation region facing the tangential plane P of the print head 6.
FIG. 4 shows a layout of the nozzles 8 on the surface 7.
In FIG. 4, as in FIG. 3, the conveyance direction of the sheet S as a recording medium is indicated by an arrow. Further, the width direction of the paper S is indicated by an arrow. The transport direction of the paper S and the width direction of the paper S are substantially orthogonal.
The nozzles 8 are arranged at equal intervals over the length in parallel with the sheet-feeding side tangent L1 where the sheet-feeding roller 2 and the tangent plane P shown in FIG. . That is, the sheets S are arranged in the width direction. The length of the nozzle row 81 can be determined by the width of the maximum paper S that can be used in the inkjet printer 1.

Hereinafter, the arrangement of the nozzles 8 will be described in detail.
In FIG. 4, the nozzle row 81 of the nozzle 8 has two rows of paper corresponding to black (B), cyan (C), magenta (M), and yellow (Y) as the colors of ink ejected from the nozzle 8. They are arranged side by side in the transport direction of S. Dots are formed on the paper S by the ink ejected from each nozzle 8.
FIG. 4 shows an enlarged view of the two nozzle rows 81 corresponding to black (B). The nozzles 8 in one row are arranged in a so-called zigzag pattern, shifted from the other nozzles in the width direction of the paper S. The dot density in the width direction of the paper S can be increased by ejecting ink from the nozzles in accordance with the transport of the paper S. The nozzles of cyan (C), magenta (M), and yellow (Y) are arranged in the same manner as black (B).

  The print head 6 can be a high nozzle density head formed by MEMS (Micro Electro Mechanical Systems) technology or the like. In this case, the width A in the transport direction of the paper S can be about 4 mm, and the width in the transport direction of the paper S in all nozzle rows can be about 1 mm. The nozzle density can be set to, for example, 800 dpi and 1600 dpi in two rows, but is not limited thereto.

According to this embodiment, there are the following effects.
(1) The radii r1 and r2 of the paper feed side roller 2 and the paper discharge side roller 3 according to the formula (1) up to the length A in the direction perpendicular to the paper feed side tangent L1 of the surface 7 that is the nozzle formation region Therefore, the distance between the paper supply side roller 2 and the paper discharge side roller 3 can be shortened. Therefore, it is possible to minimize the state where the sheet is conveyed by only one of the paper supply side roller 2 and the paper discharge side roller 3.
Further, the surface 7 is disposed between the paper supply side roller 2 and the paper discharge side roller 3, and the distance in the transport direction of the paper S between the surface 7 and the paper supply side roller 2 and the paper discharge side roller 3 is also short. Therefore, when the edge of the paper S is removed from the paper supply side roller 2 and the distance between the print head 6 and the paper S begins to change, the surface 7 is located close to the edge of the paper S, and near the both ends of the paper S. Ink jet printer 1 can be obtained with less banding unevenness. The same applies to the case where the paper is conveyed only by the paper supply side roller 2 before the paper is conveyed by the paper discharge side roller 3.

(2) The radii r3 and r4 of the paper feed side roller 2, the paper discharge side roller 3, the paper feed side subordinate roller 4 and the paper discharge side subordinate roller 5 are reduced to the length A of the surface 7 according to the equation (2). Therefore, the ink jet printer 1 that can achieve the above-described effect can be obtained.
Further, the paper S is pressed by the paper supply side roller 2 and the paper discharge side roller 3 by the paper supply side dependent roller 4 and the paper discharge side dependent roller 5, and the paper S is fed to the paper supply side roller 2 or the paper discharge side roller 3. Even when the paper S is being transported by only one of them, the paper S can be supported by the elasticity of the paper S, so that printing can be performed with a smaller change in the distance between the paper S and the print head 6.

  (3) The sheet feeding side dependent roller 4 and the sheet feeding side roller 2 and the sheet discharging side dependent roller 5 and the sheet discharging side roller 3 are in contact with the contact plane P that contacts the sheet feeding side roller 2 and the sheet discharging side roller 3. On the other hand, they are arranged in the orthogonal direction. Therefore, even if the paper supply side subordinate roller 4 and the paper discharge side subordinate roller 5 press the paper S against the paper supply side roller 2 and the paper discharge side roller 3, respectively, the paper S does not deviate from the tangential plane P. The deformation of S is reduced, and the ink jet printer 1 with less banding unevenness can be obtained. Even when the paper is transported by only one of the paper discharge side roller 3 and the paper feed side roller 2, the paper is transported along the plane P, so that the distance between the paper and the surface 7 is maintained. No platen is required. A platen may be provided to further stabilize the distance between the paper and the head surface.

  (4) Since the nozzles 8 are provided so as to form rows in a direction parallel to the paper feed side tangent segment L1 (the width direction of the paper S), the surface 7 in the equations (1) and (2) The length A in the direction perpendicular to the sheet-feeding side tangent segment L1 can be shortened. Therefore, the distance between the paper supply side roller 2 and the paper discharge side roller 3 can be shortened, and the ink jet printer 1 with less banding unevenness can be obtained.

(Second Embodiment)
FIG. 5 shows a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In this embodiment, the radius r1 of the paper supply side roller 12 and the radius r2 of the paper discharge side roller 13 are equal. Other configurations are the same as those of the first embodiment.

According to this embodiment, in addition to the above-described effects, the following effects can be obtained.
(5) Since the radius r1 of the paper supply side roller 12 and the radius r2 of the paper discharge side roller 13 are equal, the parts can be shared and the inkjet printer 1 with less banding unevenness can be obtained easily. In this case, since r1 = r2 in Expression (2), A <2r1- (r3 + r4) (r3: radius of the feeding side dependent roller 4 and r4: radius of the discharging side dependent roller 5).

(Third embodiment)
FIG. 6 shows a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, the conveyance belt 16 is laid along the tangential plane P between the paper supply side roller 12 and the paper discharge side roller 13.
Further, the radius r3 of the paper feed side dependent roller 4 and the radius r4 of the paper discharge side dependent roller 15 are different, and r4 is larger than r3. Furthermore, the shape of the print head 6 is different. The width A of the surface 7 of the print head 6 is smaller than that of the second embodiment. Other configurations are the same as those of the second embodiment.

According to this embodiment, in addition to the above-described effects, the following effects can be obtained.
(6) The sheet S is supported by the conveyance belt 16 along the tangent plane P, and printing can be performed with less change in the distance between the sheet S and the print head 6, and the inkjet printer 1 with less banding unevenness can be obtained. it can.

(Fourth embodiment)
FIG. 7 shows a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, the radius r3 of the paper supply side subordinate roller 14 and the radius r4 of the paper discharge side subordinate roller 15 are the same size. Furthermore, the shape of the print head 6 is different. The width A of the surface 7 of the print head 6 is larger than that of the second embodiment.

The ink jet printer 1 according to the present embodiment includes a support member, a so-called platen 17, which is located on the opposite side of the tangential plane P and faces the surface 7 and has a surface 18 facing the surface 7. The surface 18 is substantially at the same position as the tangent plane P.
In the present embodiment, the surface 18 is a flat surface, but may be a curved surface. The shape of the platen 17 is not limited to a plate shape, and may be a cylindrical shape.

According to this embodiment, in addition to the above-described effects, the following effects can be obtained.
(7) Since the sheet S can be supported along the tangential plane P by the surface 18 facing the surface 7 of the platen 17, printing can be performed with less change in the distance between the sheet S and the print head 6. The ink jet printer 1 with less banding unevenness can be obtained.

(Fifth embodiment)
FIG. 8 shows a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, the rotation shaft 41 of the paper feed side subordinate roller 4 and the rotation shaft 51 of the paper discharge side subordinate roller 5 are disposed between the paper supply side plane P1 and the paper discharge side plane P2. Specifically, the rotation axis 41 of the sheet feeding side subordinate roller 4, the rotation axis 121 of the sheet feeding side roller 12, and the sheet feeding side tangent L1 (shown in FIG. 2) in contact with the sheet feeding side roller 12 and the tangent plane P are shown. The feeding-side plane P1 that is included is inclined toward the print head 6 side. In addition, the rotation axis 51 of the discharge side subordinate roller 5, the rotation axis 131 of the discharge side roller 13, and the discharge side tangent L2 (shown in FIG. 2) in contact with the discharge side roller 13 and the tangent plane P are included. The paper discharge side plane P2 is inclined toward the print head 6 side. In addition, the difference from the second embodiment is that the distance between the paper supply side roller 12 and the paper discharge side roller 13 is slightly different from that of the second embodiment and that the platen 17 is provided. Other configurations are the same as those of the second embodiment.

According to this embodiment, there are the following effects.
(8) The paper feed side subordinate roller 4 and the paper discharge side subordinate roller 5 are arranged between the paper feed side plane P1 and the paper discharge side plane P2 by shifting them from the paper feed side plane P1 and the paper discharge side plane P2, respectively. Therefore, it is possible to apply tension to the paper S between the paper supply side subordinate roller 4 and the paper discharge side subordinate roller 5. Therefore, the deformation of the paper S is reduced, and the ink jet printer 1 with less banding unevenness can be obtained.

Hereinafter, a state in which the paper S is conveyed by only one of the paper supply side roller 12 and the paper discharge side roller 13 will be described.
A state of the sheet S when the platen 17 does not exist is shown by a dotted line in the drawing. In a state where there is no platen 17, the sheet S itself tends to be in a state along a plane perpendicular to the paper supply side plane P1 or the paper discharge side plane P2. If the platen 17 is present in this state, the end of the paper S is pressed against the platen 17, and the distance between the paper S on the platen 17 and the surface 7 is kept more constant.

(Sixth embodiment)
FIG. 9 shows a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, a part of the surface 7 that is a nozzle formation region overlaps with the paper feeding side roller 12 when viewed in plan toward the tangential plane P. Further, the distance between the paper supply side roller 12 and the paper discharge side roller 13 is long. Furthermore, the shape of the print head 6 is different. Other configurations are the same as those of the second embodiment.

According to this embodiment, there are the following effects.
(9) Even when the distance between the paper supply side roller 12 and the paper discharge side roller 13 is long, the sheet 7 is supplied because the surface 7 is close to the paper supply side tangent L1 (shown in FIG. 2). Even if the roller is separated from the side roller 12, printing can be performed up to the vicinity of the end of the paper S. Accordingly, it is possible to obtain the ink jet printer 1 with less banding unevenness.

(Seventh embodiment)
FIG. 10 is a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, the shape of the print head 6 is different from that of the sixth embodiment. Further, a part of the surface 7 which is a nozzle forming region overlaps with the paper supply side roller 12 and the paper discharge side roller 13 when viewed in plan toward the tangential plane P.

According to this embodiment, there are the following effects.
(10) Since the nozzle formation region is close to the paper discharge side tangent L2 (shown in FIG. 2), even if the paper S is detached from the paper supply side roller 12 or the paper discharge side roller 13, it reaches to both ends of the paper S. Printing can be performed. Therefore, the ink jet printer 1 with less banding unevenness can be obtained.

(Eighth embodiment)
FIG. 11 is a schematic partial cross-sectional view of the inkjet printer 1 according to the present embodiment.
In the present embodiment, the shape of the print head 6 is different from that of the seventh embodiment, and the width A of the surface 7 that is the nozzle formation region is narrow. Further, the distance between the paper supply side roller 12 and the paper discharge side roller 13 is so short that the two rollers do not contact each other.

According to this embodiment, there are the following effects.
(11) Since the distance between the paper feed side roller 12 and the paper discharge side roller 13 is short and the surface 7 is close to the paper feed side tangent L1 (shown in FIG. 2), the paper S is fed to the paper feed side roller 12 Even if it is off, the printing can be performed up to the vicinity of the edge of the paper S. Therefore, the ink jet printer 1 with less banding unevenness can be obtained.

(Comparative example)
FIG. 12 shows a schematic partial cross-sectional view of an inkjet printer according to a comparative example.
When the distance between the paper supply side roller 12 and the paper discharge side roller 13 is increased, the paper S is transported only by the paper discharge side roller 13, and the position of the paper S relative to the print head 6 changes due to the deflection of the paper S or the like. . As the distance between the paper S and the print head 6 changes, streaky unevenness (hereinafter referred to as banding unevenness) occurs in the width direction of the paper S.

The embodiment is not limited to the above, and various modifications other than those described above can be made without departing from the spirit of the embodiment.
For example, the ink jet recording apparatus may be a serial printer. Either thermal ink jet or piezo ink jet may be used.

1 is an overall configuration block diagram of an ink jet printer according to a first embodiment. 1 is a schematic partial perspective view of an ink jet printer according to a first embodiment. 1 is a schematic partial cross-sectional view of an ink jet printer. FIG. FIG. 6 is a schematic partial cross-sectional view of an ink jet printer according to a second embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to a third embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to a fourth embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to a fifth embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to a sixth embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to a seventh embodiment. FIG. 10 is a schematic partial cross-sectional view of an ink jet printer according to an eighth embodiment. 1 is a schematic partial cross-sectional view of an ink jet printer according to a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2,12 ... Paper feed side roller, 3,13 ... Paper discharge side roller, 4,14 ... Paper feed side subordinate roller, 5,15 ... Paper discharge side subordinate roller, 6 ... Print head, 7 ... Surface that is a nozzle forming area, 8... Nozzle, 16... Conveyor belt, 17... Platen as a support member, 18. Rotating shaft of the paper discharge side roller, 41... Rotating shaft of the paper feeding side subordinate roller, 51... Rotating shaft of the paper discharging side subordinate roller, 81. Paper side plane, L1... Paper feed side tangent, L2.

Claims (8)

A feed roller,
A paper discharge side roller having a rotation axis parallel to the rotation axis of the paper supply side roller;
A print head provided on a side opposite to the paper supply side roller and the paper discharge side roller with respect to a tangential plane contacting the side surface of the paper supply side roller and the side surface of the paper discharge side roller;
A plurality of nozzles opposed to the tangential plane provided in the print head,
The nozzle forming region in which the plurality of nozzles are formed includes a rotation axis of the sheet feeding side roller and a sheet feeding side plane including a sheet feeding side tangent line in contact with the sheet feeding side roller and the tangent plane, It is arranged between the rotation axis of the discharge side roller and the discharge side plane including the discharge side tangent line where the discharge side roller and the tangent plane are in contact,
When the radius of the paper feed side roller is r1, the radius of the paper discharge side roller is r2, and the length of the nozzle forming region in the direction orthogonal to the paper feed side tangent is A, the relationship of Equation (1) is satisfied. A <2√ (r1 · r2) (1)
An ink jet recording apparatus. The inkjet recording apparatus according to claim 1, wherein
A paper feed side subordinate roller driven by the paper feed side roller;
A discharge-side subordinate roller driven by the discharge-side roller,
A <((2√ (r1 · r2)) − (r3 + r4)) where the radius of the paper feeding side dependent roller is r3 and the radius of the paper discharge side dependent roller is r4. (2)
An ink jet recording apparatus. The inkjet recording apparatus according to claim 2,
The rotation axis of the feeding side dependent roller is in the feeding side plane,
The inkjet recording apparatus, wherein a rotation axis of the discharge side subordinate roller is in the discharge side plane. In the inkjet recording device according to any one of claims 1 to 3,
An ink jet recording apparatus comprising: a transport belt that spans the paper supply side roller and the paper discharge side roller along the tangential plane. In the ink jet recording apparatus according to any one of claims 1 to 4,
With respect to the tangential plane, disposed on the opposite side facing the nozzle formation region,
Having a surface facing the nozzle forming region;
An ink jet recording apparatus comprising: a support member having the opposing surface substantially in the same position as the tangential plane. In the ink jet recording apparatus according to any one of claims 1 to 5,
The ink jet recording apparatus, wherein the nozzles are provided at equal intervals in a direction parallel to the tangent line on the paper feed side to form a nozzle row. A feed roller,
A paper discharge side roller having a rotation axis parallel to the rotation axis of the paper supply side roller;
A print head provided on a side opposite to the paper supply side roller and the paper discharge side roller with respect to a tangential plane contacting the side surface of the paper supply side roller and the side surface of the paper discharge side roller;
A plurality of nozzles opposed to the tangential plane provided in the print head,
The nozzle forming region in which the plurality of nozzles are formed includes a rotation axis of the sheet feeding side roller and a sheet feeding side plane including a sheet feeding side tangent line in contact with the sheet feeding side roller and the tangent plane, It is arranged between the rotation axis of the discharge side roller and the discharge side plane including the discharge side tangent line where the discharge side roller and the tangent plane are in contact,
An ink jet recording apparatus, wherein a part or all of a nozzle forming region in which the plurality of nozzles are formed overlaps with the paper supply side roller when viewed in plan toward the tangential plane. The inkjet recording apparatus according to claim 7, wherein
An ink jet recording apparatus, wherein a part or all of the nozzle formation region overlaps with the paper discharge side roller when viewed in plan toward the tangential plane.

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