JPH10250873A - Recording medium carrier device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium carrier device capable of carrying a recording medium while making it flat. SOLUTION: An outer peripheral surface of a pinch roller 42 is covered with urethane rubber, and the hardness of a part near to both ends 34a in the cross direction of a recording medium 34 of this urethane rubber is made higher than the hardness of a part separated from both ends 34a in the cross direction. For example, the hardness of a part nearest to both ends 34a in the cross direction of the recording medium 34 is made 80 deg., the hardness of a part separated most from both ends 34a in the cross direction is made 60 deg., and a difference of 20 deg. is continuously provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type image forming apparatus for forming an image on a recording medium by discharging ink, the recording medium being conveyed while sandwiching both ends in the width direction of the recording medium. Regarding the transport device, for example, A2 size (420.0 mm × 594.0 m
m) The present invention relates to a recording medium transport device suitable for transporting a recording medium having a size equal to or larger than m).

[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 for forming an image on a recording medium by discharging ink. The inkjet type image forming apparatus includes, for example, a print head for discharging ink, a carriage mounted with the print head and reciprocating in a predetermined direction, and a recording medium transport for transporting a recording medium in a direction orthogonal to the predetermined direction. Device.

When an image is formed on a recording medium, the recording medium being conveyed by the recording medium conveying device is temporarily stopped, and while the carriage is reciprocated in the above-described predetermined direction, an image signal carrying image information is generated. Ink is ejected from the print head on the basis of this, and an image for one band is formed on a portion of the recording medium located in the image forming area where the image is formed. After that, the paper is conveyed by the width of one band and stopped, and again,
While the carriage is reciprocating in the predetermined direction, ink is ejected from the print head based on the image signal to form an image on a portion of the recording medium that is newly located in the image forming area. By repeating such an operation, an image is formed on the recording medium.

[0004] In the ink jet type image forming apparatus, the recording medium may swell due to the ink ejected during printing, causing partial unevenness. This phenomenon is called cockling. The unevenness due to the cockling may be formed not only in the portion where the ink is attached but also in the portion where the next image is formed. In this case, the projections formed on the recording medium may come into contact with the print head reciprocating at a high speed and damage the ink ejection ports and the like.

[0005] In an ink jet type image forming apparatus, a recording medium may be conveyed before the ink is completely dried when printing. In this case, if the recording medium transport device comes into contact with a portion where the ink has not dried, the image may be disturbed. By transporting the recording medium after the ink has dried, such a disturbance of the image can be eliminated, but the transport takes a long time and the image formation takes time. In addition, since the drying time of the ink varies depending on the type (paper quality) of the recording medium, the control for efficiently transporting the ink becomes complicated.

In order to prevent the recording medium conveying device from contacting the image forming portion of the recording medium, a technique of arranging the recording medium at both ends in the width direction of the recording medium orthogonal to the conveying direction of the recording medium is generally adopted. In this technique, the recording medium is conveyed while sandwiching both ends in the recording medium width direction with a pair of conveying rollers.

[0007]

However, if the recording medium is conveyed while nipping both ends in the width direction of the recording medium by a pair of conveying rollers, wrinkles are formed at the center and ends in the width direction of the recording medium. May occur. In this case, together with the above-described cockling phenomenon, the image formation is adversely affected.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a recording medium transport device that can transport a recording medium while flattening it.

[0009]

According to a first aspect of the present invention, there is provided a recording medium transporting apparatus for forming an image on a recording medium by discharging ink. (1) The recording medium transport device including a first roller and a second roller that transports the recording medium while nipping both ends.
And, among the portions where the recording medium is clamped by the second roller, a portion closer to both ends in the width direction of the recording medium with a stronger clamping force than a portion far from both ends in the width direction. It is.

Here, the first roller (2) has a portion closer to both ends in the width direction of the recording medium in a portion where the first roller contacts the recording medium than a portion farther from both ends in the width direction of the recording medium. Pressing with a high pressing force may be used.

The first roller has (3) at least an outer peripheral surface covered with rubber, and (4) a recording medium of the rubber which is held between the first and second rollers. The hardness of the portion near both ends in the width direction may be higher than the hardness of the portion away from both ends in the width direction.

Further, the first roller (5) faces the center in the width direction of the recording medium sandwiched between the first and second rollers, and the rotation axis of the first roller is within a range of 5 ° or less. May be inclined upward by the angle of.

Further, the first roller (6) has a diameter of 10% or less as the distance from the portion near the both ends in the width direction of the recording medium sandwiched between the first and second rollers increases. May be reduced.

Here, the width direction of the recording medium refers to a direction crossing the conveying direction of the recording medium, and usually refers to a direction orthogonal to the conveying direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a recording medium transport device according to the present invention will be described with reference to the drawings.

First, with reference to FIG. 1, an external configuration of an ink jet type plotter (hereinafter, referred to as a plotter) using a recording medium transport apparatus of the present invention will be described.

FIG. 1 is a perspective view showing a plotter.

The plotter 10 is fixed on an upper part of a stand 12 with casters 12a. Also, plotter 1
0 is provided with a control panel 14 for operating the plotter 10.
By operating various switches etc. installed in
Paper size, online / offline, commands, etc. are input and instructed. The recording medium is inserted into the recording medium insertion port 16 from the direction of arrow A. Below the recording medium insertion slot 16, a stacker 18 for storing the recording medium discharged in the direction opposite to the arrow A direction is provided as described later.

At both ends of the recording medium insertion slot 16, a pinch roller (this invention is an example of a second roller according to the present invention, which is an example of a second roller according to the present invention) which conveys a recording medium while nipping the recording medium therebetween. It is an example of the first roller referred to in
(See FIG. 2) 42 are arranged. Each of the two pinch rollers has two pinch roller units 40.
Built in. Two pinch roller units 40
One of them is fixed so as to be a reference position of the recording medium, and the other is configured to be movable in a direction orthogonal to the arrow A direction according to the size of the recording medium. The pinch roller 42 can be freely separated from the transport roller 38 as described later. The pinch roller unit 40 is covered with a pinch roller cover 44.
Further, a recording medium detection sensor (not shown) is disposed on the near side of the pinch roller unit 40 in the direction of arrow A.

When the recording medium is inserted into the recording medium insertion slot 16 from the direction of arrow A, the pinch roller unit 40
The recording medium is arranged on the platen 20 and inserted after the pinch roller 42 is released from the conveying roller 38 and separated therefrom.
The recording medium pressed by the pinch roller 42 after insertion is conveyed without being printed in the direction of arrow A based on an instruction from the control panel 14, and when the trailing edge is detected by the recording medium detection sensor, the recording medium is pressed. The transport stops once. Thereafter, the recording medium is conveyed in a direction opposite to the arrow direction A to form an image. The recording medium on which the image has been formed is discharged in the direction opposite to the arrow direction A, and
Is stored in.

Referring to FIG. 2, the internal structure of the plotter 10 and the printing process will be described.

FIG. 2 is a schematic diagram showing the inside of the plotter 10. In this figure, two pinch roller units 40 are shown.
One of them is omitted and not drawn.

The plotter 10 includes a carriage 22 that reciprocates in the direction of arrow B (a direction perpendicular to the direction of arrow A, which is an example of the recording medium width direction in the present invention). The carriage 22 includes a head holder 24, and a print head 26 is detachably mounted on the head holder 24. The carriage 22 is fixed to a belt 28 hung on a drive motor (not shown), and the belt 28 reciprocates in the direction of arrow B by forward and reverse rotation of the drive motor. When the belt 28 reciprocates in the arrow B direction, the carriage 22 reciprocates in the arrow B direction guided by guide rails 30 and 32 provided behind the carriage 28.

In forming an image on the recording medium 34, the recording medium 34 mounted on the platen 20 and conveyed is temporarily stopped. In this state, the carriage 22
Is reciprocated in the direction of arrow B. A print head 26 mounted on the carriage 22 ejects ink based on a print signal while receiving position control by an encoder 36, and prints the recording medium 3.
4, an image for one band is formed in a portion located in the image forming area. Thereafter, the recording medium 34 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. This operation is repeated the required number of times over the entire length of the recording medium 34. Thereby, the recording medium 34
An image is formed on the image. Recording medium 34 on which an image is formed
Are stored in the stacker 18 (see FIG. 1) as described above.

The pinch roller unit 40 will be described with reference to FIGS.

FIG. 3 is a perspective view showing the pinch roller unit 40 from which the pinch roller cover 44 has been removed, and shows a state where the pinch roller 42 is at a position separated from the transport roller 38. 4 is a perspective view showing the pinch roller unit 40 from which the pinch roller cover 44 is removed similarly to FIG. 3, and shows a state where the pinch roller 42 is at a position where the transport roller is pressed. FIG. 5 is a perspective view showing a roller plate shaft and a release spring fixed to the roller plate shaft.

The pinch roller unit 40 includes a main body frame 50, a roller supporting plate 60 fixed to the main body frame 50 so as to be rotatable in the direction of arrow C, and a main body frame 50.
And a lever 70 rotatably fixed in the direction of arrow D, and a mountain-shaped spring 80 having one end fixed to the upper surface 62 of the roller support plate 60. The roller support plate 60 rotates in the direction of arrow C and in the opposite direction so that the pinch roller 42 rotates between a position (release position) indicated by a solid line and a position (pressing position) indicated by a two-dot chain line. . The lever 70
Rotates between the position indicated by the solid line and the position indicated by the two-dot chain line in FIG.

The main body frame 50 has a bottom plate 52 extending in the direction of arrow A, and a pair of trapezoidal side plates 54 and 56 formed from the center to the rear end of the bottom plate 52. A roller plate shaft 64 to which a roller support plate 60 is rotatably fixed is attached to a lower portion of the side plates 54 and 56. A lever shaft 72 to which a lever 70 is rotatably fixed is attached to the upper part of the side plates 54 and 56.

Of the end surfaces of the side plates 54 and 56, a stopper portion 5 is provided above the end surface on the side closer to the pinch roller 42.
4a and 56a are formed. This stopper portion 54
a, 56a, a stopper 70 formed on the lever 70
a, the rotation of the lever 70 in the direction opposite to the direction of arrow D is restricted. Further, stopper portions 54b and 56b (stopper portions 56b are not shown) are formed at the center portions of the inclined end surfaces of the side plates 54 and 56, respectively. A stopper 70b formed on the lever 70 contacts the stoppers 54b and 56b, and the rotation of the lever 70 in the direction of arrow D is restricted.

The pinch roller 42 is attached to an end of the roller support plate 60 opposite to the end fixed to the roller plate shaft 64.
Are rotatably fixed via a rotation shaft 42a. As shown in FIG. 5, the pinch roller 4 is
A release spring 66 that urges the roller support plate 60 so that 2 is located at the release position is fixed. That is, the release spring 6
6 urges the roller support plate 60 in the direction of arrow E.
Therefore, when the lever 70 is at the position shown in FIG. 3, the pinch roller 42 is at the release position.

A handle 74 for operating the lever 70 is formed at the end of the lever 70 opposite to the end fixed to the lever shaft 72. The lever 70
A cam portion 76 for pressing the chevron spring 80 is formed at a portion of the lever shaft 72 opposite to the handle portion 74 with respect to the lever shaft 72.

The angle spring 80 has one end (fixed end) 82 thereof.
Are fixed to the upper surface 62 of the roller support plate 60. The other end (free end) 84 of the chevron spring 80 can move on the upper surface 62 in the directions of arrows A and A '.

When the lever 70 is turned in the direction of arrow D,
The chevron spring 80 is crushed by the cam portion 76 and the chevron spring 8
The free end 84 moves in the direction of arrow A, and the angled spring 80 overcomes the urging force of the release spring 66, so that the roller support plate 60 rotates in the direction of arrow C. Accordingly, the pinch roller 42 moves to the pressing position, and the recording medium 34 (see FIG. 2) is held between the pinch roller 42 and the transport roller 38 (see FIG. 2).

Here, the operation of the angle spring 80 and the cam portion 76 will be described in detail.

A slope 88 from the vertex 86 of the angle spring 80 to the fixed end 82 is formed. The cam portion 76 of the lever 70 comes into contact with the slope 88.

When the lever 70 is rotated clockwise (in the direction of arrow D) toward the plane of FIG. 5, the slope 88 of the chevron spring 80 bends inward while being pushed by the cam portion 76, and Of the roller support plate 60 slides in the direction of arrow A. Further, the cam section 76
Is rotated clockwise, the angle spring 80 of the cam portion 76 is rotated.
Since the contact portion of the lever 70 comes above the line connecting the lever shaft 72 and the angled spring 80, the lever 70 is moved by the spring force of the angled spring 80 to the stopper portions 54b and 56b provided on the end faces of the side plates 54 and 56. The lever 70 rotates until the stopper 70b of the lever 70 abuts. Further, in the embodiment of the present invention, the cam portion 76 for the chevron spring 80
Is set to be small so that the vicinity of the apex 86 of the chevron spring 80 is hardly deformed by work hardening, and when the portion near the apex 86 is pressed by the cam portion 76, the free end 84 slides. We take advantage of small quantities.

By the way, when each portion of the pinch roller 42 in the axial direction presses the recording medium 34 (see FIG. 2) with an equal pressure, the recording medium 34 being conveyed is wrinkled or the recording medium 34 is There is a possibility that it may shift to one side of the direction. Once such a trouble occurs, it is likely to occur continuously and expand not only near the pinch roller 42 but also over a wide range. Therefore, of the portions where the recording medium 34 is nipped by the transport roller 38 and the pinch roller 42, a portion closer to both ends in the width direction of the recording medium 34 is held with a stronger holding force than a portion farther from both ends in the width direction. did.

As a result, the following effects are obtained.

When the recording medium 34 is sandwiched between the transport roller 38 and the pinch roller 42, a portion (high pressure portion) near both ends in the width direction of the recording medium 34 is stronger than a portion (low pressure portion) apart from both ends in the width direction. By clamping with the clamping force, a force that pulls the recording medium 34 outward acts on the high pressure portion.

As a result, the recording medium 34 can be conveyed without causing the recording medium 34 to float or wrinkle. Therefore, all surfaces of the recording medium 34 are maintained microscopically flat, and an accurate image can be formed, so that image quality is improved.

Of the portion where the recording medium 34 is held between the transport roller 38 and the pinch roller 42, the recording medium 34
A technique of clamping a portion near both ends in the width direction with a stronger clamping force than a portion far from both ends in the width direction will be described with reference to FIG.

FIG. 6A is a schematic diagram showing a technique in which the outer peripheral surface of the pinch roller 42 is covered with rubber and the hardness of the rubber is changed, and FIG.
FIG. 4 is a schematic diagram showing a technique of tilting the recording paper 34 with respect to the recording paper 34;
(C) is a schematic diagram showing a technique in which the diameter of the pinch roller 42 is changed.

The technique shown in FIG.
2 is a technique in which the outer peripheral surface of the recording medium 34 is covered with urethane rubber, and the hardness of a portion of the urethane rubber near the both ends 34a in the width direction of the recording medium 34 is higher than the hardness of portions away from both ends 34a in the width direction. For example, the hardness of the portion of the urethane rubber closest to both ends 34a in the width direction of the recording medium 34 is set to 8
0 °, and the hardness of the portion farthest from the both ends 34a in the width direction was 60 °, and a difference of 20 ° was continuously provided.

There are two types of hardness testers for measuring the hardness of rubber: a constant load type and a spring type.
It was measured using a constant load rubber hardness tester shown in 5 of 6301 (1962). Hardness is Olsen hardness (H
₀ ) or Puseijons hardness (H _P ).

The technique shown in FIG.
This is a technique in which the second rotation shaft 42a is inclined upward by an angle て toward the center in the width direction of the recording medium. here,
Θ was set to an angle within a range of 5 ° or less. In consideration of the margins at both ends 34a in the width direction of the recording medium 34, the width of the pinch roller is about 10 mm. In order to increase or decrease the pressure in the range of 10 mm in width, it is preferable to set the above-mentioned inclination angle to an angle in the range of 2 ° to 3 °. In this case, the pinch roller 42 can be used without any particular processing.

The technique shown in FIG.
2 is a technique in which the diameter of the recording medium 34 is smoothly reduced by 10% or less as the distance from the portion near the both ends 34a in the width direction of the recording medium 34 increases. In this case, the pinch roller 42 is made of an elastic material such as rubber, and the rotation shaft 42a is made parallel to the recording medium 34. As a result, the pinch roller 42 is crushed in the vicinity of both ends 34a in the width direction of the recording medium 34, and the vicinity is strongly pressed. This technology has the same idea as the technology shown in (b),
Since the pinch roller 42 itself has an inclination, the rotating shaft 42a does not have to be inclined.

[0047]

As described above, according to the recording medium transport apparatus of the present invention, of the portions where the recording medium is sandwiched by the first and second rollers, the portions near both ends in the width direction of the recording medium are removed. Since the sheet is nipped with a stronger holding force than a part separated from both ends in the width direction, a force acts to pull the recording medium outward in a part near both ends in the width direction of the recording medium. As a result, the recording medium can be conveyed while being flattened, thereby preventing the recording medium from being lifted or wrinkled, and improving the image quality.

Here, the first roller presses a portion of the portion where the first roller comes into contact with the recording medium, closer to both ends in the width direction of the recording medium with a higher pressing force than a portion separated from both ends in the width direction. In the case of pressing, similarly to the above,
The recording medium can be conveyed while being flat, and the image quality can be improved.

The first roller has at least the outer peripheral surface covered with rubber, and the hardness of a portion of the rubber near the both ends in the width direction of the recording medium sandwiched between the first and second rollers. However, when the hardness is higher than the hardness of the portion away from both ends in the width direction, the recording medium can be conveyed while being flat, and the image quality can be improved by changing the rubber hardness.

Further, the first roller faces the center in the width direction of the recording medium sandwiched between the first and second rollers, and
When the rotation axis of the first roller is inclined upward by an angle within the range of 5 ° or less, the recording medium can be conveyed while being flat, and the image quality can be improved by a simple design change.

Further, the first roller comprises first and second rollers.
The diameter of the recording medium held by the rollers is 10%
If the recording medium is smoothly reduced, the recording medium can be conveyed while being flat, without inclining the rotation axis of the first roller, and the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external configuration of a plotter in which an embodiment of a recording medium transport device of the present invention is used.

FIG. 2 is a schematic diagram showing the inside of the plotter of FIG. 1;

FIG. 3 is a perspective view showing the pinch roller unit with the pinch roller cover removed, showing a state in which the pinch roller is at a release position separated from a conveyance roller.

FIG. 4 is a perspective view showing the pinch roller unit with a pinch roller cover removed from the pinch roller unit;
5 shows a state where the pinch roller is at a position where the pinch roller presses the transport roller.

FIG. 5 is a perspective view showing a roller plate shaft and a release spring fixed to the roller plate shaft;

FIG. 6A is a schematic diagram showing a technique in which the outer peripheral surface of a pinch roller is covered with rubber and the hardness of the rubber is changed;
(B) is a schematic diagram showing a technique of tilting the rotation axis of the pinch roller with respect to the recording paper, and (c) is a schematic diagram showing a technique in which the diameter of the pinch roller is changed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plotter 34 Recording medium 34a Both ends in the width direction of recording medium 38 Transport roller 40 Pinch roller unit 42 Pinch roller 42a Rotation axis of pinch roller

Claims (5)

[Claims] A first roller and a second roller that convey the recording medium while nipping both ends in a width direction of the recording medium in an ink jet image forming apparatus that forms an image on the recording medium by discharging ink; In the recording medium transporting device, a portion closer to both ends of the recording medium in the width direction of the portion where the recording medium is sandwiched by the first and second rollers is more than a portion separated from both ends in the width direction of the recording medium. A recording medium transport device characterized in that the recording medium is clamped with a strong clamping force. 2. The first roller has a higher pressing force at a portion of the portion where the first roller comes into contact with the recording medium, at a portion near both ends in the width direction of the recording medium than at a portion separated from both ends in the width direction. 2. The recording medium transport apparatus according to claim 1, wherein the recording medium is pressed by a button. 3. The first roller, at least an outer peripheral surface of which is covered with rubber, wherein the rubber is located near both ends in the width direction of the recording medium sandwiched between the first and second rollers. 3. The recording medium transport device according to claim 1, wherein the hardness of the portion is higher than the hardness of the portion away from both ends in the width direction. 4. The first roller is directed to a central portion in the width direction of the recording medium sandwiched between the first and second rollers, and a rotation axis of the first roller is within a range of 5 ° or less. 3. The recording medium transport device according to claim 1, wherein the recording medium transport device is inclined upward by an angle. 5. The diameter of the first roller smoothly decreases by 10% or less as the distance from a portion near the both ends in the width direction of the recording medium sandwiched between the first and second rollers increases. The recording medium transport device according to claim 1, wherein