JPH05173445A - Paper peeling device for fixing device - Google Patents

Abstract

PURPOSE:To prevent a finger from being brought into contact with only one place of a fixing roll by reciprocatingly moving the fixing roll in a shaft direction in a device equipped with the finger in order to peel a paper from the fixing roll of a heat roll system fixing device. CONSTITUTION:The fingers 7 are arranged on the fixing roll of the fixing device in order to peel the paper and supported by a supporting arm 9 through a bracket 8. In the fixing device, the roll 2 is supported through bearings 4 and 4a allowing the sliding of a shaft 3 and driven by a roll driving device 10 composed of a motor 11 and a belt 14. Besides, a roll moving device 20 is constituted by arranging a driving mechanism by a lever member 21, a cam 24 and a spring 25 with respect to the roll 2. Then, the roll 2 is set to be at a fixing position only when a fixing action is executed and the position with which the fingers 7 are brought into contact is changed by moving the roll 2 before and after the time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roll type fixing device, and more particularly to a paper peeling device provided with fingers for peeling paper from a fixing roll, and more particularly to a finger supported at a fixed position. The present invention relates to an apparatus that can change a position where a finger contacts a fixing roll by moving the roll in an axial direction.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine or a laser printer, a toner image is formed on an image bearing member such as a photosensitive drum by using an electrophotographic method, and a sheet on which the toner image is transferred is fixed. It uses a means of fixing through the device and making a copy. As the fixing device,
Generally, a heat roll type fixing device is often used. In the heat roll type fixing device, two fixing rolls, a fixing roll provided with a heating source and a pressure roll pressed against the fixing roll, are provided. The rolls are arranged facing each other. Then, when the paper carrying the toner image is passed between the two rolls, the toner is melted by heat, and the melted toner is pressed and fixed on the paper.

In the two rolls constituting the above-mentioned fixing device, the fixing roll is provided with means for coating the surface of a metal roll core with a fluororesin to prevent the fused toner from adhering. In many cases, silicone oil or the like is applied to the surface of the roll to provide releasability. On the other hand, in the pressure roll, a roll core made of metal, on which a coating of an elastic body is formed with a predetermined thickness, is used. Then, in a state in which a predetermined nip pressure is set between the two rolls, the elastic body on the surface of the pressure roll is deformed according to the surface of the fixing roll, and a predetermined nip shape is set between the two rolls. The action of fixing to the paper carrying the image,
It is designed to carry out the paper transport operation.

However, in the fixing device having the above-described structure, the higher the image density is, the more the paper is sometimes wrapped around the fixing roll. Therefore, in order to surely peel the paper from the fixing roll, the fingers are respectively arranged for the two rolls, and the tips of the fingers are lightly contacted with the surface of the roll so that the paper peeling action is performed. ing. In the paper peeling device using the fingers, a mechanism is used in which a plurality of fingers are swingably arranged with respect to a support shaft, and a tip of a claw is brought into contact with a roll via an urging member such as a spring. .. A material having heat resistance such as polyimide amide resin is generally used for the fingers.

However, when the fixing device is operated with the fingers kept in contact with the fixing roll, there arises a problem that both the fingers and the coating of the fixing roll are worn. If scratches are formed on the surface of the fixing roll by fingers, fixing at the scratched portion may be poor, and the copy may become dirty. Further, since the fixing roll is a very expensive member, it is required to use it for as long as possible, but if it is scratched due to contact with the fingers, it needs to be replaced and maintenance is not possible. It also affects the cost.

Therefore, in order to solve the above-mentioned problems, as shown in Japanese Patent Laid-Open No. 129680/1990, means for reciprocating the fingers in contact with the fixing roll in the axial direction of the roll is provided. Proposed.
In the above-mentioned conventional example, by changing the contact position of the fingers from time to time, the tips of the fingers are not limited to one position, but contact is made over a wide portion, so that scratches on the roll can be suppressed to a minimum. ing. Further, as in the case of the device of the conventional example, a reciprocating mechanism for moving a finger as shown in FIG. 5 is also used as a means for moving the finger. In the example shown in FIG. 5, the finger is arranged with respect to the fixing roll 2, and the roll driving device 1 for driving the fixing roll 2 is shown.
In No. 0, the belt 14 is stretched around the sprocket 12 provided on the motor 11 and the sprocket 13 provided on the roll shaft 3 so as to be driven.

A plurality of fingers 7 are provided on the shaft 31 to separate the paper from the fixing roll 2, and the shaft 3
The finger moving device 30 is configured by providing the cam 33 on one side of the No. 1 and arranging the returning means at the other end. The shaft 31 that supports the fingers is supported via bearings 32 and 32a that slidably support the shaft. The returning means uses a lever member 35 supported by a shaft 36 and a spring 37 to make the lever member 3
5 is used to urge the shaft 31 toward the cam 33. Then, by driving the cam 33, the action of moving the shaft in one direction and the returning action of the lever member are added to reciprocally move the finger along the roll member, and the finger moves relative to the roll member. It is designed to minimize scratches.

[0008]

When the finger reciprocating mechanism as described above is applied to an image forming apparatus using a small size sheet, it is possible to reduce the influence of the finger contact with the fixing roll. However, A
In an image forming apparatus for a wide paper such as 0 size, the shaft needs to be formed very long, and in order to have the strength of the shaft, it is necessary to increase the rigidity of the shaft. Required. Further, in order to provide a large number of fingers on the shaft and accurately set the positions of the fingers with respect to the roll, there is a problem that each member constituting the paper peeling device becomes large.

Also, the device for reciprocating the paper peeling mechanism needs to be large in size, and disposing such a paper peeling device in an electronic copying machine requires a space for the device and other factors. There are many problems that need to be solved in relation to the device. Further, mounting the finger on the shaft having a large rigidity and disposing the large drive mechanism also causes an increase in the manufacturing cost of the device.
Furthermore, in the current situation where many devices are formed in a small size and the manufacturing cost of each device is required to be reduced, incorporating only the sheet peeling device as a large device is not balanced with other devices. Is not preferable.

In order to solve the above problems,
For example, as shown in Japanese Patent Application Laid-Open No. 2-93675, it is possible to provide a groove in the roll member and arrange fingers in the groove. However, in the above-mentioned conventional example, the fixing roll is provided with a means for bringing the finger into contact with a fixed position on the surface of the roll, as in the case of the conventional sheet peeling device, and therefore the fixing roll is fixed by the finger. The problem of damaging the surface coating remains.
Further, if grooves or the like are formed on the fixing roll so as to correspond to the fingers, a problem may occur in fixing property, and it is difficult to apply such means to the fixing roll.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional sheet peeling apparatus. By providing a mechanism for holding the finger at a fixed position and reciprocally moving the fixing roll, a finger supporting mechanism is provided. SUMMARY OF THE INVENTION An object of the present invention is to provide a device that can simplify the above-mentioned process and can change the position where the fingers contact the roll surface, thereby reducing the degree of damage to the coating on the surface of the fixing roll.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a finger for peeling a sheet is arranged with respect to a fixing roll of a fixing device of a heat roll type, and a tip portion of the finger is brought into light contact with the fixing roll. Then, the present invention relates to a fixing device for performing a peeling action of a sheet. In the fixing device of the present invention,
Supporting the roll through means allowing axial movement,
A roll moving device is arranged for the roll member, and the roll moving device is provided with means for pressing the roll to one side and means for acting in the direction of returning the roll. Further, in the fixing device of the present invention, when the fixing action is performed on the paper, both rolls are positioned at the fixing position, and the finger is in contact with another position of the roll during the idle time of the roll before and after the fixing action. The mechanism can be configured.

With the above-described structure, in the paper peeling device of the present invention, the position where the fingers contact the fixing roll can be changed, so that the degree of damage to the surface coating of the fixing roll can be reduced. Therefore, the life of the fixing roll can be extended. Further, it is possible to prevent the means for supporting the fingers from becoming large and complicated with respect to a large-sized fixing device for a large-sized sheet. Further, since the mechanism for driving the fixing roll in the axial direction can also be simplified, the fixing device does not become large in size, and the fixing roll has a sufficient margin in terms of strength. By providing the reciprocating mechanism, the movement of the roll can be performed without difficulty.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet peeling device of a fixing device according to the present invention will be described with reference to the illustrated example. FIG. 1 shows a fixing device 1 applicable as a sheet peeling device of the present invention. The fixing device 1 is provided with a heating source as in the case of a conventional general heat roll type fixing device. Fixing roll 2
And a pressure roll 5 provided with or without a heating source are arranged to face each other. Then, the toner image formed on the photosensitive drum 15 of the image forming apparatus is transferred to a sheet,
The sheet is conveyed by the conveying device 16 and introduced between the both rolls of the fixing device through the inlet chute 17,
The paper is nipped by a roll, and heat and pressure are applied to fix it to make a copy. In the fixing device, the fingers 7 are arranged in the discharge portion in order to separate the paper from the fixing roll, so that the paper can be prevented from rotating while being wound around the fixing roll.

In the fixing device shown in FIG. 1, as shown in FIG. 2, a plurality of fingers 7 ... Are arranged with respect to the fixing roll, and the fingers 7 are supported via brackets 8 to support arms. It is supported by 9. The support arm 9 can be arranged, for example, at a fixed position of the frame of the fixing device, and the plurality of fingers are
Each bracket is swingably provided. Further, as in the case of FIG. 5, a roll driving device 10 is arranged for the fixing roll of the fixing device, and the fixing roll 2 is driven via a driving force transmission mechanism including a motor 11 and a belt 14. Then, the pressure roll in contact with the fixing roll 2 is driven in conjunction.

In the example of the present invention shown in FIG. 2, the roll moving device 20 is arranged for the fixing roll 2 of the fixing rolls, and the bearing 4 for supporting the roll shaft 3 of the fixing roll 2 is provided. 4a is configured as a mechanism that allows the shaft to slide. In addition, the roll moving device 20 arranged to reciprocate in the axial direction with respect to the fixing roll 2 includes a driving unit including a lever member 21 and a cam 24 and a returning unit including a pressing spring 25. It is arranged corresponding to both sides of.

As shown in FIG. 3, in the roll moving device 20, the lever member 21 is supported by the support shaft 22, the cam 24 is arranged on the back surface of the lever member, and the cam is rotated. , One end of the fixing roll 2 is pressed via the lever member 21 to move the roll in the axial direction. Further, the roller 23 is arranged at the contact portion of the lever member 21 with the roll, and the lever member is used in a state in which excessive friction or the like is not given to the rotating fixing roller. It is configured so that the pressing action can be performed well.

Further, at the other end of the fixing roll 2,
A spring 25 is arranged between the bearing 4 and the bearing 4 so that the cam 25 rotates so that the fixing roll is returned by the spring 25 after the top dead center has passed.
Further, even when the fixing roll 2 is moved in the axial direction, the timing belt 14 is used and the sprocket 13 around which the belt is wound is made wide so that the driving of the fixing roll 2 can be continued. Can be configured.

Therefore, when the sprocket has a wide width, the driving force can be transmitted in a good condition even when the roll reciprocates. In addition,
As the driving force transmitting means, besides using a timing belt, a gear device or other driving force transmitting means such as a chain can be used. For example, by configuring the roll gear to have a wider width than the output gear of the motor provided at the fixed position, it is possible to cope with the movement of the roll. Further, in the roll driving device using the chain, the reciprocating movement of the fixing roll can be dealt with by using the spring tension idler means or the like.

In the fixing device of the present invention configured as described above, as shown in the timing chart of FIG.
Each member can be driven. In the timing chart shown in FIG. 4, the power source of the electronic copying machine is always turned on.
The time for performing the fixing action is relatively short. In the copying machine, when the copy switch is turned on, driving of the fixing device to the fixing roll is started before the sheet carrying the toner image reaches the fixing device, and the fixing roll stands by in an idle state. After the waiting time x of the fixing roll, the fixing action is continued for y hours, and after the sheet has passed through the fixing device, the fixing roll is driven so as to idle for a predetermined time z. Timing is set.

Therefore, in the fixing device of the present invention, the fixing roll can be set at the fixing position at time y when the paper is actually fixed, and the fixing roll is moved before and after the time y. The timing of driving by the moving device is set. Therefore, in the apparatus of the present invention, until the copying switch is turned on and the predetermined time x has elapsed, the cam 24 is made to stand by in a state in which the pressing action by the cam is not applied, as shown in FIG. deep.

Immediately before the waiting time x elapses and the sheet is nipped, the cam 24 is rotated by a half turn to move the fixing roll 2 to the right side in FIG. 3 and set to the fixing position. And the nip pressure between the pressure roll and
Set the nip shape and the normal state to perform the fixing action. When the fixing operation ends, the cam 24
Is rotated a half turn again to return the fixing roll to the standby position. The reciprocating movement of the roll is such that the cam is driven every time the copying switch is turned on. When a large number of copies are continuously taken, the fixing roll is fixed at the fixing position. Remains set to.

As described above, by reciprocating the fixing roll while the roll of the fixing device is rotating, the positions where the fingers contact the fixing roll are set at two positions. You can Therefore,
Compared to the case of a device that performs fixing with the conventional fingers and the fixing roll held at fixed positions,
The degree of wear of the coating of the fixing roll can be halved, and the life of the fixing roll can be extended. In addition, in the above-described embodiment, the description is given of the example in which the action of the reciprocating movement of the fixing roll is performed in the state where the fingers are arranged with respect to the fixing roll, but even when the fingers are arranged with respect to the pressure roll, The pressure roll can be moved back and forth with respect to the fingers.

[0024]

Since the fixing device of the present invention is configured as described above, it is possible to change the position at which the finger contacts the fixing roll, so that the degree of damage to the surface coating of the fixing roll is reduced. Therefore, the life of the fixing roll can be extended. Further, it is possible to prevent the means for supporting the fingers from becoming large and complicated even for a large-sized fixing device intended for a large-sized sheet. Further, since the mechanism for driving the fixing roll in the axial direction can also be simplified, the fixing device does not become large in size, and the fixing roll has a sufficient margin in terms of strength. By providing the reciprocating mechanism, the movement of the roll can be performed without difficulty.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fixing device to which a paper peeling device of the present invention can be applied.

FIG. 2 is an explanatory diagram of a roll driving device and a roll moving device of the present invention.

FIG. 3 is an enlarged explanatory diagram of the device shown in FIG.

FIG. 4 is a timing chart showing driving of a fixing roll and reciprocating movement.

FIG. 5 is an explanatory diagram showing a configuration of a conventional paper peeling device.

[Explanation of reference numerals] 1 fixing device, 2 fixing rolls, 4.4a
Bearing, 5 pressure rolls, 7 fingers, 9
Support arm, 10 roll driving device, 14 belt, 20 roll moving device, 21 lever member,
24 cams, 25 springs, 30 finger moving devices.

Claims (1)

[Claims] 1. A fixing unit for arranging a paper peeling finger on a fixing roll of a heat roll type fixing device, and for causing a peeling action of a paper in a state where the tip end of the finger is lightly contacted with the fixing roll. In the apparatus, the roll is supported via a means for allowing movement in the axial direction, a roll moving device is arranged with respect to the roll member, and the roll moving device has means for pressing the roll to one side, A sheet peeling device of a fixing device, which is provided with a means for acting in the direction of returning the roll.