JPH0611992A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent any injury on the surface of a heating roller by a separation claw, when jam is generated. CONSTITUTION:A separation piece 8 is supported with a guide pipe 10 through a slide shaft 9, and set to be movable in the direction in parallel with the transport direction of transfer paper P. A compression spring 11 is provided between the slide shaft 9 and the guide pipe 10, and the separation piece 8 is energized to contact with the surface of a heating roller 1. The fitting form of the slide shaft 9 and the guide pipe 10 is formed into a non-circular shape. Because the separation piece 8 can not move except the transport direction of the transfer paper P, even at generating bellows-like jam on the transfer paper P, the separation piece 8 is moved in the direction of separating from the heating roller 1 accompanying increase of friction force against the transfer paper P, and hence its bite-in on the surface of the heating roller 1 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an electrophotographic copying machine or the like.

[0002]

2. Description of the Related Art In a conventional fixing device used in an electrophotographic copying machine or the like, as shown in FIG. 5, a heating roller 1 having a built-in heater and a heating roller 1 are brought into pressure contact with each other. It has a roller pair consisting of a pressure roller 2 and
Transfer paper P in a toner unfixed state sent from the transport section
Is the nip N between the heating roller 1 and the pressure roller 2.
The toner is fixed by guiding it to the nip N, and the transfer paper P after the toner is fixed is discharged to the paper discharge portion by the paper discharge roller 5 pair through the upper and lower outlet guide plates 3 and 4. .

Further, in order to prevent the transfer paper P from wrapping around the heating roller 1, the tension spring 6 generates a turning force around the rotation support shaft 7 at the exit of the nip N to heat the transfer paper P. Separation claw 8 that is brought into contact with the surface of the roller 1
Has been placed. At this time, as for the mounting position of the rotation support shaft 7, the end of the separation claw 8 that abuts the heating roller 1 is tangentially generated by the rotation of the heating roller 1 so that the separation claw 8 is attached to the heating roller 1.
The separation claw 8 is usually located at a position where the separation claw 8 acts so that the separation claw 8 is prevented from being caught in the heating roller 1 to prevent the surface of the heating roller 1 from being scratched.

Further, the bottom of the separating claw 8 is the upper outlet guide plate 3.
The lower exit guide plate 4 also serves as a guide plate, and guides the transfer of the transfer paper P to the pair of discharge rollers 5 on the downstream side of the transfer.

[0005]

However, in the case of the above-mentioned conventional fixing device, as shown in FIG. 6, the transfer paper P is carried out in the carry-out direction through the nip N between the heating roller 1 and the pressure roller 2. If the leading end of the transfer paper P that has passed through the nip portion N is caught by the upper exit guide plate 3 or the like during the operation, and the transfer paper P has a bellows-like jam, the bottom portion 11a having the guide function of the separation claw 8 is generated. Receives a force from the bellows-shaped transfer paper P in a direction perpendicular to the transport direction (direction A), so that the separation claw 8 receives a moment of force in a direction in which the contact end with the heating roller 1 is pushed into the heating roller 1. As a result, the separation claws 8 are pushed into the heating roller 1 and scratch the surface of the heating roller 1.

Therefore, the present invention is intended to prevent the surface of the heating roller from being scratched by the separating claw when the transfer paper is jammed.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention uses a slide shaft so that a separation claw for preventing winding of transfer paper can be moved in parallel in the same direction as the transfer paper transport direction. The separation claw is supported by the guide member via the guide shaft, and a compression spring is interposed between the slide shaft and the guide member to urge the separation claw into contact with the surface of the heating roller.

Further, the guide member has a pipe shape, and the fitting shape of the guide member and the slide shaft is a non-circular shape that cannot be moved except in the transfer paper conveying direction.

[0009]

Since the separating claw cannot move in a direction other than the conveying direction, the separating claw does not move up and down even if a bellows-shaped jam occurs on the transfer sheet, and the frictional force with the transfer sheet increases. Along with this, a moving force in a direction away from the heating roller on the downstream side of the conveyance acts on the separation claw, so that the separation claw is prevented from being caught in the heating roller surface.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention,
Similar to that shown in FIG. 5, heating roller 1 and pressure roller 2
The transfer paper P is made to enter the nip N formed by the above to fix the transfer paper P, and the separation claw 8 for preventing the transfer paper P from being wrapped around the heating roller 1 is arranged at the exit of the nip N. In a certain fixing device, a slide shaft 9 is provided at the upper end of the separation claw 8 so as to extend downstream in the transport direction of the transfer paper P, and the slide shaft 9 slides on a guide pipe 10 fixed as a guide member. The separation claw 8 is supported as much as possible so that the separation claw 8 can be moved in a direction substantially parallel to the conveyance direction of the transfer paper P, and a compression spring (coil) is provided between the slide shaft 9 and the guide pipe 10.
11 is interposed so that the separation claw 8 is pressed against the surface of the heating roller 1.

Further, as shown in FIGS. 2 to 4, the axial cross section of the slide shaft 9 attached to the upper portion of the separation claw 8 has a D shape.
The hollow vertical section of the guide pipe 10 supporting the slide shaft 9 is also D-shaped similar to the above-mentioned shaft section, and the rotational movement of the separating claw 8 about the slide shaft 9 is restricted so that the guide pipe 10 is provided in a direction other than the transfer paper conveyance direction. It is not movable.

Now, while the transfer paper P is passing through the nip N between the heating roller 1 and the pressure roller 2, the leading end of the transfer paper P is caught by the upper outlet guide plate 3 or the like and the transfer paper P is bellows-shaped. When a jam occurs, the load acts on the bottom portion of the separation claw 8 having the guide function from the bellows-shaped transfer paper P in the transfer direction of the transfer paper P and in the direction perpendicular to the transfer direction (direction A). The separation claw 8 is attached to the guide pipe 10 via the slide shaft 9.
It is supported by and cannot move in a direction perpendicular to the transport direction of the transfer paper P. However, since the separation claw 8 can move in the conveyance direction of the transfer sheet P, the tangential force (B direction) due to the rotation of the heating roller 1 and the downstream side in the conveyance direction, that is, as the frictional force with the transfer sheet P increases, By moving in a direction away from the heating roller 1, it is possible to prevent the heating roller 1 from being caught in the surface.

Although the slide shaft 9 and the guide pipe 10 have a D-shaped vertical cross section in the above embodiment, any other non-circular shape that can move in a direction other than the conveying direction may be used instead. Needless to say, various changes can be made without departing from the scope of the invention.

[0014]

As described above, according to the fixing device of the present invention, the separation claw for preventing the transfer paper from wrapping is guided through the slide shaft so as to be movable substantially parallel to the transfer paper conveying direction. Since the separation claw is pressed against the surface of the heating roller by a compression spring, even if the transfer paper causes a bellows-shaped jam at the fixing portion, the separation claw is moved to the downstream side in the transfer paper conveyance direction. Can be released to the heating roller surface, the separation claws do not bite into the heating roller surface, the generation of scratches on the heating roller surface can be prevented, and the cross-sectional shapes of the guide member and the slide shaft are the same non-circular shape. By
It is possible to easily control the rotation of the separation claw around the slide shaft and to enhance the reliability of the operation.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a fixing device of the present invention.

FIG. 2 is an enlarged view showing an essential part of FIG. 1 in an exploded manner.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is a view taken along the line BB of FIG.

FIG. 5 is a schematic view showing an example of a conventional fixing device.

FIG. 6 is a schematic view showing an example in which a bellows jam occurs in a conventional fixing device.

[Explanation of symbols]

 1 Heating Roller 2 Pressure Roller 8 Separation Claw 9 Slide Shaft 10 Guide Pipe (Guide Member) 11 Compression Spring N Nip P Transfer Paper

Claims (2)

[Claims] 1. A fixing device in which a separation claw for preventing the transfer paper from being wrapped around the heating roller is arranged at an exit of a nip formed by a heating roller and a pressure roller. Is supported by a guide member so as to be movable in a direction substantially parallel to the transfer paper conveyance direction, and a compression spring for biasing the separation claw against the surface of the heating roller is arranged in contact with the separation claw. A fixing device characterized by the following. 2. The guide member is hollow, and the hollow guide member is supported by a separation claw via a slide shaft, and the hollow cross-sectional shape of the guide member and the cross-sectional shape of the slide shaft are non-circular. The fixing device according to claim 1, which has the same shape.