JPH0532345A - Carriage device for paper sheet and the like - Google Patents

Abstract

PURPOSE:To ensure a sheet to be properly carried, regardless of the size thereof, by causing a retreat means to shift at least one of carrying rollers as a pair to the retreat position where the inner edge of the roller comes outside a sheet end. CONSTITUTION:At least one roller 14b of carrying rollers 14b and 15 is shifted by a retreat means 20 to the retreat position where the inner edge of the roller 14b comes outside the end of a sheet. As a result, at least one of the carrying rollers 14b and 15 as a pair retreats outside a sheet carriage passage, upon releasing pressed contact. Even when curl is generated in the sheet, therefore, the sheet is prevented from coming in contact with the carrying rollers 14b and 15, and from being bent at a corner or the like. Also, both large-sized and small-sized sheets can be properly carried.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device, for example, a sheet conveying device of an image forming apparatus such as a wet electrophotographic copying machine.

[0002]

2. Description of the Related Art In a conventional wet electrophotographic copying machine, as shown in FIG. 1, a sheet such as a transfer sheet P on which a visible image of a photosensitive drum 1 is transferred is separated from the photosensitive drum 1 by a separating roller 2. Then, it is guided by the separation guide plate 3 and guided and conveyed to the fixing device by the conveyance guide plate 4 and the fixing inlet guide plate 5.

When the fixing device is formed as a fixing roller device having a fixing roller 7 having a heat source 6 and a pressure roller 8, a sheet is nipped between the fixing roller 7 and the pressure roller 8 and heat-fixed. The transferred and fixed transfer paper P is separated from the transfer paper roller 7 by the separation claw 9, and the guide plate 1
After passing 0, the paper is fed by the paper ejection rollers 11 and 12 and ejected to the outside of the machine through the paper ejection guide plate 13.

When the conveying distance from the photosensitive drum 1 to the fixing device is long, a large-sized sheet can be conveyed as it is, but a small-sized sheet has no means for feeding it in the middle. And it will not be transported to the fixing device. Therefore, a pair of conveying rollers including the upper conveying roller 14 and the lower conveying roller 15 is provided in the middle of the conveying path from the photosensitive drum 1 to the fixing device.

When the transfer paper P is a paper with poor water absorption such as OHP base paper or second original paper, if the paper after transfer is passed through the fixing device as it is, the solvent and toner T on the transfer paper are squeezed. There is a problem of causing image deletion.

In order to solve this problem, it has been proposed to provide a blotter roller to absorb the solvent component on the transfer paper to prevent image deletion. The parts are required and the cost becomes high. On the other hand, it is conceivable to provide only the blotter roller without providing the conveying roller pair, but in this case, the solvent is absorbed by the blotter roller even for plain paper with good water absorption, and the blotter roller absorbs the solvent unnecessarily frequently. Then, there is a problem that durability is lowered.

Therefore, as shown in FIG. 2, one roller of the conveying roller pair, for example, the upper conveying roller 14 is formed by a blotter roller, and the other roller, for example, the lower conveying roller 1 is formed.
5, the upper conveying roller 14 is divided into a blotter portion 14a whose main purpose is solvent absorption and a conveying portion 14b which is in contact with both ends of the sheet, and the blotter portion 14a is supported by a movable bracket 16 to absorb water. When the paper is poor in performance, the blotter portion 14a is brought into contact with the backup roller 15, and when plain paper having good water absorption is used as the transfer paper, the blotter portion 14a is movable so as to be separated from the backup roller 15 and is conveyed. The portion 14b is rotatably supported by the side plate 17 and the bracket 18 fixed to the side plate 17, and is formed as a short roller that abuts only at both end portions of the sheet.

The blotter portion 14a is made of a material having a high water absorption property such as a non-woven fabric, and the backup roller 15 is made of a sponge roller or a rigid roller. The contact distance with the blotter roller 14a is lengthened to increase the solvent absorption time. Since it is long, it is desirable to form it as an elastic roller.

When the paper is large in size, the paper may hit the conveying portion 14b which is always in contact with the backup roller 15 and the conveyance may not be successful. Therefore, the conveying portion 14b may also be in contact with the backup roller 15 like the blotter portion 14a. It is formed so that it can be brought into contact with and separated from the backup roller 15 when it is a small size sheet. When a large size sheet is used, the backup roller 15 is retracted upward.

When the paper is a large size, the conveying roller unit 14
Even if b is retracted to the upper side, the curl of the transfer paper after transfer is severe depending on the environment and the type of the transfer paper, so that the transfer paper hits the transport unit 14b, and the paper may be folded. There is a problem in that there is a layout limitation to sufficiently retract the transport unit by an amount that does not hit the curled transfer sheet, and it is not possible to fully retract the transport unit.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems of the prior art and to provide a paper transporting device that can reliably transport paper regardless of its size.

[0012]

According to the present invention, there is provided a paper transporting apparatus having a pair of transport rollers for transporting a paper edge portion, which is normally in a released state and can be switched to a pressurized state as needed, The paper transport apparatus is characterized in that at least one transport roller of the transport roller pair is provided with a retracting means for moving the inner end surface thereof to a retracted position located outside the sheet edge.

[0013]

According to the present invention, at least one of the pair of transport rollers which moves between the state in which they are pressed against each other and the state in which they are released from each other and separated from each other is such that at least one of the pair of transfer rollers has both ends of the paper in the pressed state. Nip the parts to reliably convey the paper. When the size of the paper is large and the transport rollers are not particularly required, the transport rollers are separated from each other and the pressure contact is released. At this time, at least one of the transport rollers is moved to a position where the inner end face is outside the end position of the sheet, that is, the inner end face of the transport roller is aligned with the end portion of the sheet or a position outside thereof. In the case of a large size sheet, the two conveying rollers do not exist on the sheet conveying path in a state of being in pressure contact with each other, so that even if the sheet is curled, it is reliably conveyed without abutting.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in the drawings.

In FIG. 3, the pair of conveying rollers provided on the sheet conveying path has a short upper conveying roller 14b and a short lower conveying roller 15. In the case of a wet copying machine as in the example shown in FIGS. 1 and 2, the blotter roller and the upper conveying roller 14b can be arranged side by side, but when it is not necessary to absorb the solvent or the like, a small size sheet is used. Forming a pair of short conveying rollers that are short enough to press both ends of
It can be formed as a pair of a short conveying roller and a long conveying roller extending over the entire sheet, and provision of the blotter roller can be omitted.

At least one of the transport rollers, that is, the upper transport roller 14b, which is a short roller in the figure, is rotatably supported by a bearing portion 19a supported by an arm 19.

The arm 19 is moved to the position shown in FIG.
The upper conveyance roller 14b is moved between a pressure contact position in contact with the lower conveyance roller 15 shown in FIG. 4 and a pressure contact release position apart from the lower conveyance roller 15 as shown in FIG. At the press-contact release position, the inner end surface (the left end surface in the drawing) of the upper conveying roller 14b is located at a position that coincides with the end portion of the largest size sheet to be conveyed or outside thereof.

The retracting means 20 is, for example, a solenoid 21.
And the plunger 22 of the solenoid 21 has a lever 23
It is attached to the arm 19 via.

The solenoid 21 applies a pressing force to the upper conveying roller 14b in a direction perpendicular to the axes of the conveying rollers 14b and 15 at the pressure contact position, and moves the upper conveying roller 14b obliquely with respect to the axis to the pressure release position. Deploy.
A structure in which two solenoids are used in consideration of the action direction of force can be applied. In the figure, one solenoid is arranged so that the plunger 22 extends and contracts obliquely with respect to the axis.

A lever 23 and an arm 19 are attached to the plunger 22.
By fixing and, when the plunger 22 is de-energized,
The arm is pulled by the force of the spring 24 and the upper transport roller 14
b can move diagonally and can move to the press-contact release position. The spring 24 has one end engaged with the arm 19 and the other end engaged with the machine frame.

When the sheet to be conveyed has a small size, an electric current is applied to the coil of the solenoid 21 and the plunger 22 is pulled so that the upper conveying roller 14b comes into pressure contact with the lower conveying roller 15 and, eventually, the force in the direction orthogonal to the axis. Pressed by the components.

In order to make the movement of the upper conveying roller 14b smooth, a cam 25 is provided in the retracting means 20, and the cam 25 has, for example, a first cam groove 26a for guiding the arm 19 and a second cam for guiding the lever 23. A projection (not shown) provided on the arm 19 when the lever 23 is provided with the groove 26b and moves by the operation of the solenoid 21 along the second cam groove 26b.
Is guided by engaging with the first cam groove 26a, and the upper conveying roller 14b moves away from the lower conveying roller 15 in the direction orthogonal to the axis along the cam grooves 26a, 26b in the vicinity of the pressure contact position without changing its posture. Allows to move diagonally to the axis.

At the press-contact release position, the inner end surface of the upper conveying roller 14b is located at a position that coincides with the side edge of the sheet or outside thereof, so that the sheet conveyed along the lower conveying roller 15 hits the upper conveying roller 14b. Contact was completely avoided and ear breakage was prevented.

The lower carrying roller 15 can also be configured to be obliquely retracted similarly to the upper carrying roller 14b.
The upper transport roller 14b may be fixed and the lower transport roller 15 may be obliquely retracted.

[0025]

According to the present invention, since at least one of the pair of conveying rollers retracts from the sheet conveying path to the outside when the pressure contact is released, it is possible to prevent the sheet from hitting the conveying rollers even if the sheet is curled, and the sheet is prevented from hitting. It is possible to prevent folds in the ears and to reliably transport large and small size paper.

By diagonally moving the upper conveying roller to the retracted position, it is possible to move a short distance in a short time.

By guiding the upper conveying roller by the cam, the movement can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a sheet conveyance path of a conventional wet type copying machine.

FIG. 2 is a schematic view showing a structure of an end portion of a conventional blotter roller.

FIG. 3 is a partial explanatory view showing a pressure contact state of a conveyance roller pair according to the present invention.

FIG. 4 is a view corresponding to FIG. 3 showing a state where pressure contact is released.

[Explanation of symbols] 14b Upper transport roller 15 Lower transport roller 20 Evacuation means 21 solenoid 25 cams 26a, 26b Cam groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shozo Shimomura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Kazuo Ogawa             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh

Claims (3)

[Claims] 1. A paper transporting device having a transport roller pair for transporting a paper edge portion, which is normally in a released state and is switched to a pressure state as necessary, wherein at least one transport roller of the transport roller pair has an inner end surface thereof. A sheet conveying device, characterized in that it is provided with an evacuation means for moving the sheet to an evacuation position located outside the edge of the sheet. 2. The retracting means moves the carrying roller obliquely with respect to the axis of the carrying roller, and presses the carrying roller in a direction orthogonal to the axis when the pair of carrying rollers come into contact with each other. 1. The sheet conveying device according to 1. 3. The sheet conveying apparatus according to claim 2, wherein the retracting means has a cam, and the cam guides the conveying roller to an oblique movement with respect to an axis and a pressing movement orthogonal to the axis.