JPH0529492Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a fixing device used in a copying machine, etc. Specifically, the present invention relates to a fixing device used in a copying machine or the like. The present invention relates to a fixing device having a conveyance guide provided therein.

2. Description of the Related Art Conventionally, a fixing roller has been provided in a copying machine, a reader printer, etc. to heat and fix a transferred toner image onto a sheet of paper. Usually, a separation claw is provided near the fixing roller for peeling off the paper stuck to the circumferential surface of the roller. This separation claw is brought into contact with the circumferential surface of the fixing roller by a biasing means, and is rotatable about a support shaft. When the leading edge of the paper stuck to the roller circumferential surface hits the separating claw, the paper is peeled off and the separating claw itself can escape from the roller circumferential surface.

Problems that the invention aims to solve However, in the above-mentioned fixing device, if a paper jam occurs immediately after the fixing roller, the succeeding part of the paper will continue to be conveyed even though the leading edge of the paper has stopped. Therefore, the paper forms a bellows shape between the upper and lower guide plates. At this time, the separation claw receives pressure from the jam paper and is excessively pressed against the fixing roller, resulting in damage to the roller circumferential surface. If the circumferential surface of the fixing roller is thus scratched, it may cause fixing failure.

Therefore, an object of the present invention is to prevent damage to the circumferential surface of the fixing roller caused by the separation claw.

In order to achieve the above object, in the present invention, the separation claw protrudes in the discharge direction from the first support shaft rotatably supported, has a rear end portion formed along the conveyance guide, and has a rear end portion formed along the conveyance guide. is rotatably supported by a second support shaft provided at a position opposite to the rear end of the separating claw, and is urged toward a position forming a conveyance path by a second urging means. It is characterized by being

When a jam occurs upstream of the first support shaft in the discharge direction, the pressure from the jam paper causes the conveyance guide facing the separation claw to rotate in a direction away from the separation claw. Therefore, the space between the separation claw and the conveyance guide is expanded, and the pressure on the separation claw is released. Further, when a jam occurs on the downstream side of the first support shaft in the discharge direction, the pressure of the paper jam acts on the rear end of the separation claw in a direction that separates the separation claw from the fixing roller.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of a fixing device to which this embodiment is applied, in which an upper fixing roller 1 and a lower fixing roller 2 are in contact with each other, and a sheet of paper passes between both rollers 1 and 2. A toner image is fixed thereon. The upper fixing roller 1 is a roller having a built-in heater, and is rotationally driven in the direction of an arrow in the figure by a driving means (not shown). The lower fixing roller 2 is pressed against the upper roller 1 by a biasing means (not shown) and is driven to rotate.

Of the pair of fixing rollers 1 and 2, the tip 3a of the separation claw 3 is in contact with the circumferential surface of the upper roller 1 to which the paper is attached by the molten toner image by the biasing means 3e.
As shown in the figure, the upper part of the separation claw 3 is supported by a stopper 5.
The separation claw 3 is restricted by the contact with the stopper 5, and in addition to the rotational movement, the elongated hole 3b performs a sliding movement along the support shaft 4.
The separation claw 3 has a shape as shown in the figure, and a protrusion 3d is formed at a position facing the transport path on the downstream side of the tip 3a in the transport direction.

Then, a pair of fixing rollers 1 and 2 and a pair of ejection rollers 6
A conveyance guide 7 is provided at a position facing the separation claw on the conveyance path between the two. This conveyance guide 7 is rotatable around a support shaft 8. FIG. 2 is an exploded perspective view showing the attached state of the conveyance guide 7. A mounting plate 9 is attached to the longitudinal end of the conveyance guide 7 with screws 10. Two mounting holes are formed in the.
On the other hand, a support plate 11 is also provided on the device main body side, and a support shaft 8 is provided on this support plate 11, which becomes a rotation axis of the conveyance guide 7 by engaging with the mounting hole of the guide side mounting plate 9. It is being A spring 12 is fitted around this support shaft 8, and both ends of this spring 12 are stretched between the main body and the conveyance guide 7. The concave portion of the support shaft 8 has an E
A ring 13 is fitted, and the conveyance guide 7 is rotatably mounted. The conveyance guide 7 is biased clockwise in FIG. 1 by a spring 12 with a biasing force to the extent that it is pushed down by the jam paper when a jam occurs, and the conveyance guide 7 is biased clockwise in FIG. 1 by a stopper 14. Positioned to form. The conveyance guide 7 and the lower surface of the separation claw 3 regulate the paper from the top and bottom.

The operation of each part in this embodiment will be explained below.

First, to explain the operation during normal conveyance, a sheet of paper with a toner image fixed by the pair of fixing rollers 1 and 2 is stuck to the upper fixing roller 1 by the melted toner image. As it rotates, it hits the tip 3a of the separation claw 3 and is peeled off.

Next, a case where a jam occurs behind the paper separation position by the separation claw 3 will be described.

In this case, even though the leading edge of the paper is stopped on the conveyance path, the succeeding part of the paper is conveyed, so that the paper is deformed into a bellows shape. This deformed paper applies pressure to the conveyance guide 7 and separation claw 3 due to the stiffness of the paper. Here, if the pressure from the paper pushes up the protrusion 3d of the separation claw 3, the separation claw 3 will move counterclockwise around the support shaft 4, as shown by the dashed line in FIG. The claw tip 3a separates from the upper fixing roller 1 due to the force in the direction. However, if the deformation of the paper progresses further and reaches the tip 3a of the claw, or if a jam occurs at the tip 3a of the claw, the paper tries to push the tip 3a of the claw upward. Even after the tip 3a of the claw comes into contact with the upper fixing roller 1, the pressure from this paper further tries to push the tip 3a of the claw into the upper fixing roller 1, but as described above, the conveyance guide 7 is centered around the spindle 8. Therefore, the deformed paper presses the transport guide 7 downward against the biasing force of the spring 12 that biases the transport guide 7 clockwise (first
one-dot chain line in the figure). Therefore, the conveyance path is expanded in the vertical direction by the deformed paper, and the pressure on the claw tip 3a is released toward the conveyance guide 7, and the claw tip 3a is released.
will not get wedged into the circumferential surface of the upper roller.

Note that the spring 1 that biases the conveyance guide 7
The urging force No. 2 is weaker than the pressure applied by the sheet of paper deformed into a bellows shape, but stronger than the pressure applied by the sheet of paper during normal operation. Therefore, the conveyance guide 7 is not rotated in a normal conveyance state.

Effects of the invention As explained above, in the present invention, since the conveyance guide provided at a position facing the separation claw is rotatably supported, jamming occurs upstream of the first support shaft in the discharge direction. In some cases, the pressure that tends to cause the separating claw to sink into the fixing roller can be absorbed by rotating the conveyance guide in a direction away from the separating claw. In addition, since the separation claw protrudes downstream from the first support shaft in the discharge direction and has a rear end portion formed along the conveyance guide, when a jam occurs downstream from the first support shaft in the discharge direction, the jam Due to the pressure of the paper, a force is applied to the rear end of the separating claw in the direction of separating the separating claw from the fixing roller, so the separating claw does not get wedged in the fixing roller, ensuring that the roller circumferential surface is not damaged. This can further prevent fixing failure due to damage to the peripheral surface of the roller.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention;
FIG. 2 is an exploded perspective view showing how the conveyance guide is attached to the apparatus main body in the embodiment. 1... Upper fixing roller, 2... Lower fixing roller, 3
...Separation claw, 3e...Biasing means (first biasing means),
4, 8... Support shaft, 7... Conveyance guide, 12... Spring (second biasing means).

Claims (1)

[Claims for Utility Model Registration] A fixing roller for fixing a toner image on paper, and a first biasing roller rotatably supported around a first support shaft for peeling the paper from the fixing roller. A fixing device comprising: a separation pawl that is in contact with the peripheral surface of the roller by a means; and a conveyance guide provided at a position opposite to the separation pawl for conveying the separated paper in a discharge direction, The separation claw protrudes downstream from the first support shaft in the discharge direction and has a rear end portion formed along a conveyance guide, and the conveyance guide faces the rear end portion of the separation nail. A fixing device characterized in that it is rotatably supported by a second support shaft provided at a position and is urged by a second urging means toward a position where a conveyance path is formed.