JP2001146050A - Ink jet type image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet type image forming apparatus preventing the floating of a recording medium caused by a cocking or a winding habit (curl), generating no noise and not lowering an image grade. SOLUTION: Projected surfaces 64 and recessed surfaces 66 are alternately formed to a platen 62 and an edge part 64a higher than the projected surfaces 64 is formed to the part on the upstream side of a feed direction of the platen 62. Further, the positions of first and second holding parts 52, 78 are made lower than the projected surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet type image forming apparatus for forming an image by discharging ink onto a recording medium.

[0002]

2. Description of the Related Art As one of output devices of computers and workstations, there is known an ink jet type image forming apparatus which forms an image on a recording medium such as recording paper by discharging ink. The inkjet type image forming apparatus includes, for example, a print head having an ink ejection surface on which a plurality of ink ejection ports for ejecting ink are formed, and a carriage mounted with the print head and reciprocating in a predetermined main scanning direction. And a recording medium transport device that transports the recording paper in a sub-scanning direction (transport direction) orthogonal to the main scanning direction.

An example of such an ink jet type image forming apparatus will be described with reference to FIG.

FIG. 5 is a schematic view showing an example of a conventional ink jet type image forming apparatus.

In the ink-jet type image forming apparatus 10, the recording medium 12 is conveyed while being sandwiched between a driving roller 14 and a driven roller 16. The recording medium 1 being conveyed is downstream of the driven roller 16 in the conveyance direction (the direction of arrow B).
The platen 18 on which the plate 2 is placed is disposed. An image is formed on a portion (image forming portion) of the recording medium 12 placed on the platen 18. The portion of the recording medium 12 that has passed through the platen 18 is the discharge roller 20 and the spur 2
2 and further transported.

Above the platen 18, a carriage (not shown) on which a print head 24 for discharging ink is mounted and reciprocates in a direction (main scanning direction) perpendicular to the plane of FIG. 5 is arranged. The print head 24 forms an image by discharging ink onto an image forming portion of the recording medium 12 while reciprocating in the main scanning direction. The image forming part where the image is formed,
The paper is discharged while being nipped by the paper discharge roller 20 and the spur 22.

The driving roller 14 and the driven roller 1
A portion where the recording medium 12 sandwiches the recording medium 12 (a portion in contact with the recording medium) is called a nip portion. Similarly, the discharge rollers 20
The portion where the spur 22 sandwiches the recording medium 12 is also called a nip portion. Position of these two nips (nip position)
The platen 18 is fixed such that the upper surface of the platen 18 is located at a position slightly higher than the straight line connecting.

By making the upper surface of the platen 18 slightly higher than the two nip positions, the recording medium 1
The second image forming portion is brought into close contact with the upper surface of the platen 18. As a result, the distance between the image forming portion of the recording medium 12 and the print head 24 is kept constant, and the image quality is kept constant.

In the print head 24, a plurality of ink discharge ports (not shown) for discharging ink are formed in a line in the main scanning direction, and each of the ink discharge ports is perpendicular to the surface of the recording medium 12. It is designed so that ink is ejected. However, the ejection direction of the ink ejected from each ink ejection port may be shifted from the vertical direction due to a manufacturing error or the like. When the ink ejection direction shifts in this manner, the position where the ink (ink droplet) lands on the recording medium 12 (landing position) also deviates (is deviated) from the designed position. As a result, the ink does not land at the designed landing position, and the ink lands at a position slightly deviating from the designed landing position, so that the so-called image quality becomes poor and the image quality is reduced. This shift of the landing position (off)
It becomes larger as the distance between the ink discharge port of the print head 24 and the image forming portion of the recording medium 12 becomes longer.

Therefore, in order to prevent the above-described deterioration in image quality, the distance between the ink ejection port and the recording medium is usually made as short as possible in an ink jet type image forming apparatus. However, in an ink jet type image forming apparatus, since an image is formed by infiltrating ink into a recording medium, the fibers of the recording medium having absorbed the ink partially expand, and irregularities are formed in the expanded portion and its surroundings. (Cockling) may occur. The concavity and convexity due to the cockling may grow not only in the portion where the image formation where the ink is attached is completed but also in the portion where the next image is formed. As described above, in the ink jet type image forming apparatus, the distance between the ink ejection port and the recording medium is made as short as possible. Therefore, when cockling occurs, the recording medium may come into contact with the ink ejection port. Due to this contact, the ink in the ink ejection port adheres to the recording medium, and the recording medium becomes dirty, and paper dust adheres to the ink ejection port, resulting in a poor ink ejection state.

Further, as described above, the platen 18 is fixed such that the upper surface of the platen 18 is located at a position slightly higher than a straight line connecting the two nip positions. Therefore, when a recording medium wound in a roll is used,
A curl occurs in the image forming portion of the recording medium. As a result, similarly to cockling, the image forming portion of the recording medium may come into contact with the ink ejection port. Due to this contact, the ink in the ink ejection port adheres to the recording medium, and the recording medium becomes dirty, or paper dust adheres to the ink ejection port, resulting in a poor ink ejection state.

Various techniques for preventing troubles caused by cockling or curl as described above have been conventionally proposed.

One such technique will be described.

According to this technique, a pressing member that presses the recording medium is arranged on a portion of the platen on which the recording medium is mounted, on the upstream side in the transport direction from the image forming area in front of the ink discharge port, thereby forming a curl ( Curl) and a large number of spurs are arranged on the platen on the downstream side of the image forming area in the conveyance direction from the image forming area, and the recording medium is pressed down by the large number of spurs to reduce the period of the unevenness of the cockling. The recording medium is prevented from contacting the ink ejection ports.

Another technique for preventing troubles caused by cockling or curl will be described.

According to this technique, the recording medium is forcibly pressed against the concave portions of the concave and convex portions by forming the concave and convex portions extending in the transport direction alternately in the image forming area of the platen, and is positioned in the concave portion of the recording medium. This is a technique to generate cockling in a part. In this manner, the recording medium is pressed against the concave portion to generate cockling at this portion, so that the recording medium does not contact the ink ejection port.

Still another technique for preventing trouble caused by cockling or curl will be described.

In this technique, a large number of holes are formed in a platen, a suction device is arranged below the platen, and the suction device is moved to suck a recording medium on the platen. As a result, the recording medium comes into close contact with the platen, so that even if cockling or curl occurs, the recording medium does not come into contact with the ink ejection ports.

[0019]

Among the above-mentioned prior arts, in the technique using a pressing member and a large number of spurs, when the distance between the pressing member and the large number of spurs is short, an image forming area of a recording medium is used. Since the located portion is sufficiently pressed, unevenness due to curling and cockling can be sufficiently suppressed. However, when the width (length in the transport direction) of the image forming area increases, the distance between the pressing member and the plurality of spurs also increases, and the image forming portion of the recording medium cannot be sufficiently pressed. As a result, unevenness due to curling or cockling cannot be sufficiently suppressed, and the recording medium may come into contact with the ink ejection port. In particular, when the density of an image formed on a recording medium is high, cockling is severe because the amount of ink absorbed by the recording medium is large, and the recording medium often comes into contact with the ink ejection ports.

Among the above-mentioned conventional techniques, in the technique of forming irregularities extending in the transport direction alternately in the image forming area of the platen, the recording medium is forcibly pressed into the concaves of the irregularities, so that the curl ( Curl) is corrected. Also,
Even if cockling occurs, cockling is generated in a portion of the printing medium located in the concave portion, so that the printing medium can be prevented from contacting the ink ejection ports. However, since the recording medium is pressed against the recess, the distance between the ink ejection port and the recording medium is not constant depending on the position of the image forming area. For this reason, there is a problem that the landing position of the ink is shifted and the image quality is reduced.

[0021] Of the above-mentioned conventional techniques, the technique using a suction device has a problem that the cost is increased due to a large-scale device, and noise is generated due to generation of intake noise and exhaust temperature.

According to the present invention, it is possible to prevent the recording medium from floating due to cockling or curl (curl) formed on the recording medium, generate no noise, and improve the image quality. It is an object of the present invention to provide an ink jet type image forming apparatus which does not reduce the temperature.

[0023]

In order to achieve the above object, an ink jet type image forming apparatus according to the present invention is arranged such that ink is applied to a portion of a recording medium conveyed in a predetermined conveying direction, which is located in a predetermined image forming area. In the ink jet type image forming apparatus for forming an image by discharging, (1) the image forming apparatus is disposed upstream of the image forming area in the transport direction.
(1) a first transport member that transports the recording medium while nipping the recording medium at a first nipping section that nipping the recording medium; (2) a platen on which the recording medium is placed, on which the image forming area is formed;
Disposed downstream of the platen in the transport direction,
A second transport member that transports the recording medium while nipping it,
(4) a reverse warpage generating means disposed between the first conveying member and the image forming area, for curving a portion of the recording medium conveyed therebetween between the first conveying member and the image forming area; A plurality of convex surfaces extending in the transport direction and arranged at predetermined intervals in an orthogonal direction substantially perpendicular to the transport direction, and a plurality of concave surfaces formed between the plurality of convex surfaces. ) The above two transport members are
It is characterized by having a plurality of second holding portions for holding a recording medium, each of which is located in a region where each of the plurality of convex surfaces extends in the transport direction.

The reverse warpage generating means includes: (7) a reverse warp roller that freely rotates while pressing a portion of the recording medium located on the convex surface against the convex surface; It may be constituted by a reverse warpage projection higher than the convex surface formed on the upstream side in the direction.

Further, the first transport member may transport the recording medium at a lower speed than the second transport member.

Further, the first holding portion and the second holding portion may be (10) located below the convex surface.

Further, the length of the convex surface in the orthogonal direction perpendicular to the transport direction is (11) longer than the length of the second holding portion in the orthogonal direction, and the length of the concave surface is It may be shorter than the length in the orthogonal direction.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet type image forming apparatus according to the present invention will be described with reference to the drawings.

Referring to FIGS. 1 and 2, an embodiment of the ink jet type image forming apparatus of the present invention will be described.

FIG. 1 is a color plotter (hereinafter, referred to as an embodiment) of an ink-jet type image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a side view schematically showing a schematic configuration of a plotter). FIG. 2 is a perspective view showing a main part of the plotter shown in FIG.

The plotter 30 has a carriage 32 which reciprocates in the direction of arrow A (an example of an orthogonal direction in the present invention).
It has. The carriage 32 has four types of color inks (for example, cyan, magenta, yellow, and black).
Are mounted on each other. A plurality of ink ejection ports (not shown) for ejecting ink are formed on the ink ejection surface 36 of the print head 34.

The carriage 32 is fixed to a belt (not shown) mounted on a drive motor (not shown), and the belt reciprocates in the direction of arrow A by forward and reverse rotation of the drive motor. When the belt reciprocates in the arrow A direction, the carriage 32 is guided by the guide rail 38 and reciprocates in the arrow A direction. A guide roller 40 is rotatably fixed to the front side of the carriage 32, and the guide roller 40 rolls in the direction of arrow A while being supported by a guide rail (not shown).

A recording medium 42 such as a recording paper has a nip 5 between a driving roller 44 extending in the direction of arrow A and a driven roller 50 rotatably held by a driven roller holder 46.
2 (which is an example of a first holding portion according to the present invention) is conveyed by a feeding mechanism (not shown). Driven roller 50
Is configured to be able to press against the drive roller 44 by a driven roller spring 48 fixed to one end of the driven roller holder 46. Drive roller 44 and driven roller 50
Is disposed upstream of a platen 62 described later in the direction of arrow B. The driving roller 44 and the driven roller 50
Thus, an example of the first transport member according to the present invention is configured.

The recording medium 42 is conveyed in the direction of arrow B while being held between the driving roller 44 and the driven roller 50 at the nip 52. The nip portion 52 is located about 1 mm below the convex surface 64 described later. In addition,
Gears 54 and 56 for rotating the drive roller 44 and the like, a feed motor 58
Is arranged.

In forming an image on the recording medium 42, the recording medium 42 being transported is temporarily stopped, and the carriage 32 is reciprocated in the direction of arrow A, based on the image information input to the print head 34. The ink is ejected from the ink ejection port, and the image forming area 6 of the recording medium 42 is
An image for one band is formed in a portion located at 0. Thereafter, the recording medium 42 is conveyed by a predetermined length, and an image for the next band is formed in a portion newly located in the image forming area 60. This operation is repeated over the entire length of the recording paper. Thus, a color image is formed on the recording medium 42.

A platen 62 extending in the direction of arrow A is disposed in front of the driving roller 44 and the driven roller 50. The platen 62 has a plurality of convex surfaces 64 and concave surfaces 66 extending in the transport direction (the direction of arrow B). The plurality of convex surfaces 64 and concave surfaces 66 are alternately arranged at predetermined intervals in an orthogonal direction (arrow A direction) orthogonal to the arrow B direction. Both the convex surface 64 and the concave surface 66 are parallel to the ink ejection surface of the print head 34 mounted on the carriage 32. Convex surface 6
4 and the concave surface 66 (length in the direction of arrow B) and width (arrow A).
The length in the direction is determined according to the size of the plotter 30.

On the convex surface 64 of the platen 62, the portion of the recording medium 42 placed on the convex surface 64 is
A paper pressing roller 68 (which is an example of a reverse-warping roller according to the present invention) that presses the paper is rotatably arranged. The paper press roller 68 is rotatably held by a paper press roller holder 70 extending in the direction of arrow A, and is configured to be pressed against the convex surface 64 of the platen 62 by a paper press roller spring 72. Here, the convex surface 64 of the platen 62 and the paper pressing roller 68 constitute a reverse warpage generating means according to the present invention. The paper holding roller 68
Are arranged on the upstream side in the direction of arrow B with respect to the portion of the recording medium 42 located in the image forming area 60.

Downstream of the platen 62 in the transport direction,
The second transport member according to the present invention is disposed. The second transport member includes a rotating shaft 72 extending in the direction of arrow A, a paper discharge roller 74 described later, and the like. Both ends of the rotating shaft 72 are rotatably fixed to side walls (not shown) of the plotter 30. A plurality of paper discharge rollers 74 are fixed to the rotation shaft 72 at predetermined intervals. Each paper discharge roller 7
The spurs 76 are in contact with the spurs 4 from above, and the spurs 76 are configured to rotate when the discharge rollers 74 rotate.

The portion where the discharge roller 74 and the spur 76 come into contact is a nip 78 where the recording medium 42 comes into contact
(It is an example of the second holding portion according to the present invention). The nip 78 is located below the convex surface 64 by about H1 mm. Therefore, the convex surface 64 is more suitable for the nip 78
Closer to the print head 34. The width of the convex surface 64 is
It is longer than the width of the nip 78 (the length in the direction of arrow A) and shorter than the width of the concave surface 66. The spur 76 is a gear having a plurality of sharp projections formed over the entire outer periphery, and a small area formed at the tips of the plurality of projections assists the conveyance of the recording medium 42. I do.

On the opposite side of the longitudinal end of the rotary shaft 72 from the feed motor 58, a paper discharge gear unit 80 for transmitting the rotational force of the feed motor 58 to the rotary shaft 72 is arranged. . The discharge gear unit 80 includes the driving roller 44.
, A feed-side drive gear 82 fixed to the rotary shaft 72, a discharge gear 84 meshing with the feed-side drive gear 82, a discharge-side drive gear 86 fixed to the rotary shaft 72, and the like.
The feed-side drive gear 82 is fixed to a portion of the rotation shaft of the drive roller 44 opposite to the feed motor 34 and rotates together with the drive roller 44. The paper discharge gear 84 is rotatably fixed to the plotter 30. The paper discharge drive gear 86 meshes with the paper discharge gear 84, and the rotational force of the feed motor 58 is transmitted to the rotating shaft 72 via the paper supply drive gear 82 and the paper discharge gear 84.

The gear ratios of the gears 82, 84, 86 are set such that the rotation speed of the rotating shaft 72 is slightly higher than the rotation speed of the drive roller 44. Therefore,
The portion of the recording medium 42 located between the nip 52 and the nip 78 is pulled in the transport direction (arrow B direction). In addition, the nip portions 52 and 78 are located about H1 mm below the convex surface 64. For this reason, the portion of the recording medium 42 lying on the convex surface 64 is pulled downward and the paper pressing roller 68 causes the convex surface 6.
It is pressed against 4. Therefore, even if cockling occurs at least in this portion, this portion does not rise, and the distance between this portion and the print head 34 is kept constant.

Referring to FIG. 3 and FIG. 4, a mechanism for preventing the floating of the recording medium will be described.

FIG. 3 shows a state before an image is formed on a recording medium.
FIG. 3 is a side view schematically illustrating a recording medium when the density of an image formed on the recording medium is low. FIG. 4 shows a case where the density of an image formed on a recording medium is low.
(A) is a schematic diagram showing a platen viewed from a direction opposite to the transport direction, and (b) is a schematic diagram showing a second transport member viewed from above. In these figures, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

As shown in FIG. 3, the recording medium 42 on which the image starts to be formed is pulled between the nip 52 and the nip 78. The positions of the nip portion 42 and the nip portion 78 are lower than the edge portion (side) 64b of the convex surface 64 located on the downstream side in the transport direction. Edge portion 64b
Extend in a direction (arrow A direction) orthogonal to the transport direction. On the upstream side of the convex surface 64 in the transport direction, an edge portion (side) 64a higher than the convex surface 64 (an example of a reverse warpage projection according to the present invention) is formed. The edge portion (side) 64a extends in a direction (arrow A direction) orthogonal to the transport direction, and is located about H2 mm above the edge portion 64b.

As described above, since the convex surface 64 is formed with the two edge portions 64a and 64b, the recording medium 42 is pulled slightly strongly at these two edge portions 64a and 64b, and the edge portion 64a of the recording medium 42 is formed. ,
Portions on the side of the nip portions 52 and 78 beyond 64b are bent downward. Further, the edge portion 64a is replaced with the edge portion 64b.
H2 mm higher than (higher)
The recording medium 42 is bent downward in the direction of the image forming area 60 by the paper pressing roller 68, and the recording medium 4
2 is prevented from floating from the convex surface 64. As a result, the “hip” of the portion of the recording medium 42 located on the convex surface 64 of the platen 62 (the image forming area 60) becomes stronger in the direction substantially perpendicular to the transport direction, and
, The distance between the portion located on the concave surface 66 and the print head 34 is kept constant.

Also, when the roll-shaped recording medium 42 is used, the recording medium 42 is bent downward by the paper pressing roller 68 toward the image forming area 60. Therefore, the curl of the roll-shaped recording medium 42 is curled in a direction opposite to the curl (reverse curl).
The portion of the recording medium 42 located in the image forming area 60 is prevented from rising from the convex surface 64. As a result,
The ink landing position does not deviate from the designed position, and the image quality does not deteriorate. Further, no noise is generated because a suction device for sucking the recording medium 42 into the platen 62 is not used.

Next, the case where the density of the image formed on the recording medium 42 is high will be described.

A portion of the recording medium 42 located between the edge portion 64a and the nip portion 52, and an edge portion 64b
The portion between the nip 78 and the nip 78 is relatively strongly pulled by these. Therefore, cockling is unlikely to occur in these portions even when the density of the image formed on the recording medium 42 is high.

However, when the density of the image formed on the recording medium 42 is high, the portion of the recording medium that has expanded with ink gathers between the nip 52 and the nip 78, and cockling occurs. easy. When cockling occurs, the portion expanded by the ink is bent downward by the paper pressing roller 68 toward the image forming area 60. Therefore, as shown by the broken line in FIG. 4A, the portion 42a expanded by the ink projects so as to approach the concave surface 66, and the recording medium 42 does not float. Therefore, even if cockling occurs, the recording medium 42 becomes convex downward and is prevented from floating.

Further, since the expansion of the recording medium 42 caused by the ink is dispersed above the plurality of concave surfaces 66, uniform cockling occurs. For this reason, each cockling can be lowered. Further, as described above, the portion of the recording medium 42 that is placed on the convex surface 64 is the nip 5
Since the recording medium 42 is pressed against the convex surface 64 by the paper pressing roller 68 at the same time as the recording medium 42 is pulled by a certain force between the nip portion 2 and the nip portion 78, the recording medium 42 does not float on the print head 34 side. As a result, the above-described suction device is not required, and the device configuration of the plotter 30 does not need to be large. Note that a roller or the like may be used instead of the spur 76 to form the nip 78.

[0051]

As described above, in the ink jet type image forming apparatus of the present invention, the recording medium conveyed while being nipped by the first and second conveying members is formed by the convex surface of the platen and the second nipping portion. Will be pulled between. For this reason, the recording medium is pulled slightly strongly at the edge of the end of the convex surface (the end on the downstream side in the transport direction), and is slightly bent downward. The portion of the recording medium between the first transport member and the image forming area is warped downward by the reverse warpage generating means. As a result, the "hip" of the recording medium is strengthened in a direction substantially perpendicular to the conveying direction, preventing the recording medium from floating from the convex surface, and maintaining a constant distance from the print head even in a portion of the recording medium on the concave surface. Is kept. In addition, since the curl generated when the roll-shaped recording medium is used is corrected by the reverse warpage generating means, the recording medium is more reliably prevented from rising from the convex surface. In addition, since the portion of the recording medium between the convex surface and the second holding portion is pulled, cockling does not occur on the convex surface. However, cockling is likely to occur in a portion of the recording medium that is located above the concave surface, but the recording medium is warped downward by the reverse warpage generating means. Can be prevented. As a result, the print head is not damaged without the ink ejection port from which the ink is ejected coming into contact with the recording medium. In addition, since no suction device is used, no noise is generated. Furthermore, since the recording medium is pulled, the landing position of the ink does not shift, and the image quality does not deteriorate.

Here, the reverse warpage generating means is formed of a reverse warp roller that freely rotates while pressing a portion of the recording medium located on the convex surface against the convex surface, and a roller upstream of the roller in the transport direction. In the case where the projection is constituted by the projection for reverse warpage higher than the convex surface, a reverse warp generating means having a relatively simple configuration can be obtained.

When the first transport member transports the recording medium at a lower speed than the second transport member, the second transport member transports the recording medium at a higher speed than the first transport member. It will be transported. Therefore, the recording medium is pulled between the first transport member and the second transport member. Since the recording medium is pulled in this way, even if the image formed on the recording medium has a high density and violent cockling occurs, the recording medium hardly rises due to the cockling. As a result, the contact between the ink ejection port from which the ink is ejected and the recording medium can be more reliably prevented, and the print head can be prevented from being damaged.

In the case where the first holding portion and the second holding portion are located below the convex surface,
Since the recording medium on the platen is pulled downward by the first holding portion and the second holding portion, the portion of the recording medium located above the convex and concave surfaces of the platen is pulled downward and does not float. Therefore, the lifting of the recording medium due to the cockling generated on the convex surface and the concave surface of the platen is more reliably eliminated. As a result, the contact between the ink ejection port from which the ink is ejected and the recording medium can be more reliably prevented, and the print head can be prevented from being damaged.

Further, the length of the convex surface in the direction orthogonal to the transport direction is longer than the length of the second sandwiching portion in the orthogonal direction, and is greater than the length of the concave surface in the orthogonal direction. Is shorter, the length of the portion where the second holding portion holds the recording medium is shorter than the length in the orthogonal direction of the convex surface. Is stronger, and on the concave surface, the recording medium protrudes in the direction (downward) toward the concave surface. Therefore, the lifting of the recording medium due to the cockling generated on the convex surface and the concave surface of the platen can be more reliably prevented. As a result, the contact between the ink ejection port from which the ink is ejected and the recording medium can be more reliably prevented, and the print head can be prevented from being damaged, so that deterioration in image quality can be prevented.

[Brief description of the drawings]

FIG. 1 is a side view schematically illustrating a schematic configuration of a color plotter (hereinafter, referred to as a plotter) which is an embodiment of an inkjet type image forming apparatus according to the present invention.

FIG. 2 is a perspective view showing a main part of the plotter of FIG.

FIG. 3 is a schematic diagram showing a state before an image is formed on a recording medium or a case where the density of an image formed on the recording medium is low.

FIG. 4A is a schematic diagram illustrating a platen viewed from a direction opposite to a transport direction, and FIG. 4B illustrates a case where the density of an image formed on a recording medium is low. FIG. 7 is a schematic diagram illustrating a second transport member.

FIG. 5 is a side view schematically showing a conventional plotter.

[Explanation of symbols]

 Reference Signs List 30 plotter 44 drive roller 50 driven roller 52 first holding portion 60 image forming area 62 platen 64 convex surface 64a, 64b edge portion 66 concave surface 68 paper pressing roller 74 paper discharge roller 76 spur

Claims (5)

[Claims] An ink jet type image forming apparatus that forms an image by ejecting ink to a portion of a recording medium conveyed in a predetermined conveyance direction that is located in a predetermined image forming area; A first transport member disposed on the upstream side in the transport direction and transporting the recording medium while clamping the recording medium by a first clamping portion for clamping the recording medium; and a platen on which the recording medium is placed and on which the image forming area is formed. A second transport member that is disposed downstream of the platen in the transport direction and that transports the recording medium while nipping the recording medium; and a recording medium that is disposed between the first transport member and the image forming area. Wherein the platen extends in the transport direction and has a predetermined interval in an orthogonal direction substantially orthogonal to the transport direction. A plurality of convex surfaces, and a plurality of concave surfaces formed between the plurality of convex surfaces, wherein the second conveying member is provided in a region where each of the plurality of convex surfaces is extended in the conveying direction. An ink jet type image forming apparatus, comprising: a plurality of second holding portions that sandwich a recording medium. 2. The reverse warpage generating means, comprising: a reverse warp roller that freely rotates while pressing a portion of the recording medium located on the convex surface against the convex surface; and a reverse warp roller formed upstream of the roller in the transport direction. 2. The ink jet type image forming apparatus according to claim 1, wherein the ink jet type image forming apparatus comprises a reverse warpage projection higher than the convex surface. 3. The image forming apparatus according to claim 1, wherein the first conveying member conveys a recording medium at a lower speed than the second conveying member. 4. The ink jet image forming apparatus according to claim 1, wherein the first holding portion and the second holding portion are located below the convex surface. . 5. The length of the convex surface in the orthogonal direction perpendicular to the transport direction is longer than the length of the second holding portion in the orthogonal direction, and the length of the concave surface in the orthogonal direction. The inkjet image forming apparatus according to any one of claims 1 to 4, wherein the inkjet image forming apparatus is shorter.