JPS59178472A - Sheet winding preventing device - Google Patents

Abstract

PURPOSE:To prevent abrasion or damage of the surface of a rotating body and the top of a winding preventing piece with a simple mechanism by installing a sheet winding preventing piece and a guide member for slidably guiding the turning center of the piece on the winding prevention side of a sheet conveying route. CONSTITUTION:The pivot 2a of a winding preventing piece 2 made of a heat- resistant material, such as polyimide or a metal is turnably and slidably supported with the guide groove 8a of a supporting member 8. The base end 9 of the piece 2 is connected with one end of a spring 10 fixed at the other end. The piece 2 is anti-clockwise energized around the pivot 2a with the spring 10, and the other top end 2b of the piece 2 comes in contact with the circumference of a fixing roller 1. As a result, occurrence of high mutual pressure between the piece 2 and the surface of the roller 1 can be prevented with such a simple mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing wrapping of a sheet-like member from a rotating body, and more particularly to a device for preventing sheet wrapping in a roller fixing device of an electrophotographic copying machine.

In the roller fixing device of an electrophotographic copying machine, after fixing a toner image on an image support material such as paper, the supporting material often remains attached to the roller and wraps around the roller. A winding prevention piece as shown in Figs. 2, 3, and 4 is provided.

FIG. 1 shows that the rotational center support shaft 2a of the anti-wrapping piece 2, which is rotatably supported and biased counterclockwise by a spring 10, contacts the surface of the fixing roller 1 of the anti-wrap piece 2, that is, the anti-wrap piece 2 is rotated. Sticking prevention piece 2
A so-called bite-like anti-wrapping piece 2 is shown, which is disposed on the opposite side of the fixing roller 1 from the tangent at the tip 2b.

Fig. 2 shows the actual Kosho 5 in which the rotation center support shaft 2a is different from Fig. 1.
No. 3-51166 discloses a so-called see-through wrapping prevention piece in which the rotation center support shaft 2a is arranged closer to the fixing roller l side than the tangent at the contact point 2b of the wrapping prevention piece 2 with the fixing roller l. shows. In the arrangement shown in FIG. 2, when a large upward force is applied to the tip 2b of the wrapping prevention piece 2, the tip 2b of the wrapping prevention piece 2 escapes, and the tip 2b of the wrapping prevention piece 2 is made of silicone rubber, fluorosilicone rubber, fluorosilicone rubber, etc. The surface of the fixing roller l coated with heat-resistant releasable rubber such as, or tetrafluoroethylene coating, the metal surface of pressure fixing, and the tip of the anti-wrapping piece 2? It is possible to prevent damage to b.

In the case disclosed in Japanese Utility Model Publication No. 55-12198 shown in FIG. 3, when a force is applied to the tip of the wrapping prevention piece 2 from the sheet member 4 to be separated, the tip 2b of the wrapping prevention piece 2 escapes, and the fixing roller l and prevents damage to the tip 2b of the anti-wrapping piece 2. However, since the anti-wrapping piece 2 is fixed to the tip and the elastic support 3 whose base is firmly attached to the stationary part presses the anti-wrapping piece 2 against the fixing roller 1, the anti-wrapping piece 2 is pressed against the fixing roller 1 by a large load. Since the tip 2b of the anti-wrapping piece 2 is transparent, there is concern about the separation ability.

In the case disclosed in Japanese Utility Model Application Publication No. 55-133451 shown in FIG. 4, the anti-wrapping piece 2 has a compression spring 5 inserted into its spring guide 2C, and is guided by a support 6 with the compression spring 5 sandwiched therebetween. The tip 2b of the wrapping prevention piece 2 is configured to expand and contract on a line connecting the support shaft 6a of the support body 6 and the tip 2b of the wrapping prevention piece 2. When the force of the sheet member 4 is applied, the compression spring 5 is bent, and the tip 2b of the wrapping prevention piece 2 is on the fixing roller 1 side from the cutting line drawn from the fulcrum 6a of the support 6 on the wrapping prevention piece 2 to the fixing roller l. This has the disadvantage of causing a so-called biting condition, which applies a large amount of force to the tip 2b of the anti-wrapping piece 2 and the surface of the fixing roller 1, significantly increasing the wear of the anti-wrapping piece 2 and the fixing roller 1. There is.

However, in the sheet wrapping prevention device described above, when a so-called jam condition as shown in FIG. A large load F is applied from below, and the anti-wrapping piece 2 cannot escape, often damaging the fixing roller l and the tip 2b of the anti-wrapping piece 2. There were also restrictions on the material itself.

The present invention eliminates the problems that occur when the anti-wrapping piece separates the sheet member from the rotating body when the anti-wrapping piece bites into the rotating body and jams when separating the sheet member. Another object of the present invention is to provide a rotating body that is not damaged and is not limited by the material of the anti-wrapping piece itself.

The present invention provides a sheet wrapping prevention device for preventing a sheet member from being wrapped around a rotating body, which includes a member that biases the sheet member in a direction in which the sheet member comes into contact with the rotating body. A separating anti-wrapping piece and a guide member to which the center of rotation of the anti-wrapping piece is movably guided are provided on the anti-wrapping side of the sheet member conveyance path.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a side view showing an embodiment of the present invention, in which the anti-wrapping piece 2
is made of a heat-resistant material such as PPS, polyamideimide, polyimide, or metal, and its support shaft 2a is rotatably attached to the guide groove 8a of the support member 8. One end of a spring 10 is fixed and the other end of a spring 10 is attached to the base end 9 of the anti-wrapping piece 2, and the spring 10 urges the anti-wrapping piece 2 counterclockwise around the support shaft 2a. , anti-wrapping piece 2
The tip 2b is in contact with the circumference and surface of the fixing roller 1. Further, the support member 8 of the anti-wrapping piece 2 is provided with a guide groove 8a so that the support shaft 2a at the center of rotation can be moved. During normal operation, the anti-wrapping piece 2 receives a counterclockwise rotational force due to the biasing force of the spring 10, and the support shaft 2a at the center of rotation maintains a state protruding from the end of the guide groove 8a on the spring 10 side. continue. In this state, the fixing roller l and the pressure roller 1'
The same applies to the case where the transfer paper P, on which the toner image has been fixed by being conveyed between the two, wraps around the fixing roller l and hits the tip 2b of the anti-wrapping piece 2 and is separated. Transfer paper P
When the tip of the wrapping prevention piece 2 hits the tip 2b of the wrapping prevention piece 2, the wrapping prevention piece 2 receives a force in the tangential direction 11, but this force presses the tip 2b of the wrapping prevention piece 2 against the fixing roller 1 and rotates it. It acts in the direction of pressing the support shaft 2a at the center of movement against the end of the guide groove 8a on the spring 10 side.

However, when a certain force F is applied to one lower surface of the anti-wrapping piece 2 due to the occurrence of a jam as shown in FIG. 5, the pivot shaft 2a, which is the center of rotation, moves along the guide groove 8a. At the position where the force F further increases and the support shaft 2a, which is the center of rotation of the anti-wrapping piece 2, butts against the other end 8b of the guide groove 8a, as shown in FIG.
As shown by the dotted chain line, the belly portion 12 of the wrapping prevention piece 2 comes into contact with the surface of the fixing roller l, and the tip 2b of the wrapping prevention piece 2 is completely separated from the surface of the fixing roller l. Therefore, even when a large load is applied to the anti-wrapping piece 2, the sharp tip 2b of the anti-wrapping piece 2 does not press against the surface of the fixing roller l, and the flat surface of the belly portion 12 of the anti-wrapping piece 2 Since the surface of the fixing roller (2) is pressed against the surface of the fixing roller (1), the surface of the fixing roller (1) will not be damaged.

In addition, the leading edge of the transfer paper P strongly adheres to the surface of the fixing roller 1,
Even if a strong force is applied to the tip 2b of the wrapping prevention piece 2, the spindle 2a of the wrapping prevention piece 2 is on the side of the fixing roller l from the cutting line 11 of the fixing roller 1 at the tip 2b, resulting in a so-called escape condition. This is caused by separation of the transfer paper P. Tip 2 of anti-wrapping piece 2
When a strong abutting force occurs between the roller b and the fixing roller l, the anti-wrapping piece 2 can rotate clockwise around the spindle 2a.
Since the tip 2b of the winding prevention piece 2 can escape, wear or damage to each piece can be prevented.

Another embodiment of the invention is shown in FIG. Basically, it is the same as in Fig. 6, but the difference is that the stopper 13 is disposed on the support member 8 as close to the roller l as possible, and the force F is When working, the support shaft 2a of the wrapping prevention piece 2 moves along the guide groove 8a of the support member 8, and the belly portion 12 of the wrapping prevention piece 2 comes into contact with the stopper 13, and the wrapping prevention piece 2 moves against the stopper. 13 in a clockwise direction, and the tip end 2b separates from the surface of the fixing roller l (indicated by a two-dot chain line).

In this case, the tangent line 11 to the fixing roller l at the position 2b in the figure where the tip 2b of the anti-winding piece 2 initially contacts the fixing roller l.
It is no longer necessary to provide the spindle 2a of the anti-wrapping piece 2 on the side of the fixing roller l, and it is possible to prevent the anti-wrapping piece 2 from digging into the fixing roller 1 by restraining it with the stopper 13. .

Still another embodiment is shown in FIG. The leading edge of the transfer paper P is separated from the fixing roller l, and the leading edge of the anti-wrapping piece 2 is stuck.
When the anti-wrapping piece 2 collides with the tip 2b, the anti-wrapping piece 2 is supported by the spindle 2a like a bin joint. Apply a force R on the straight & i14. If the intersection angle between this - line 14 and the cutting line 11 of the fixing roller 1 at the tip 2b of the anti-wrapping piece 2 is α, then Ra=Rcosα is the force that opposes and separates the transfer paper P, and Rb=Rsinα is the force of the fixing roller 1. This acts as a pressure or biting force on the roller 1, and if this force is excessive, it will wear or damage the tip 2b of the anti-wrapping piece 2 and the surface of the fixing roller 1, respectively.

However, the direction of the guide groove 8a of the support member 8 is aligned with the straight line 14.
The angle θ between the guide groove 8a and the straight line 15 passing orthogonally through the center of the support shaft 2a at the end of the guide groove 8a on the spring JO side is on the opposite side of the fixing roller l with the straight line 15 in between. As shown in FIG. 9, the support shaft 2a slides along the guide groove 8a with the force of Rs in
When reaching b, the wrapping prevention piece 2 is on the fixing roller 1 side with respect to the tangent 11' to the fixing roller l at the tip 2'b of the wrapping prevention piece 2, and the wrapping prevention piece 2 becomes free to escape. It is possible to prevent a large amount of pressure from being generated between the tip 2b of the fixing roller 2 and the surface of the fixing roller l. Of course, the tensile force of the spring 10 impedes the above-mentioned R51nθ, so the tensile force of the spring 1o must be appropriately selected.

Furthermore, it is necessary to consider the relationship between the angle θ and the tensile force of the spring 10, as well as the frictional force between the guide groove 8a and the support shaft 2a. In this embodiment, of course, when the force F due to the jam is received, the prevention piece 2 will be wrapped around the support shaft 2a and will escape in the direction of the two-dot chain line in FIG. This is the same as the previous example, and the final result is
In this state, the fish is fished in an escapist attitude.

As explained in each of the three embodiments above, in order to separate a sheet member that is clinging to the surface of a rotating body such as a fixing roller and trying to be transferred from the rotating body, the urging member is applied in the direction of contacting the rotating body. With a simple structure in which a support member that guides the spindle of the anti-wrapping piece, such as a biased separation claw, is provided on one side of the sheet member conveyance path for preventing wrapping, it is possible to prevent so-called jams caused by sheet members. Even when it is difficult to separate the windings, a large amount of mutual pressure is prevented from occurring between the winding preventive piece and the surface of the rotating body, and the tip of the winding preventing piece is worn out or It was possible to provide a sheet wrapping prevention device that prevents damage and alleviates restrictions on the material of the wrapping prevention piece itself.

[Brief explanation of drawings]

1, 2, 3, 4, and 5 are side views showing the conventional example, FIG. 6 is a side view showing the embodiment of the present invention, and FIG.
The figure is a side view showing another embodiment of the present invention, FIG. 8 is a side view showing still another embodiment of the present invention, and FIG. 9 is a side view showing another embodiment of the present invention.
4 is a principle diagram showing state No. 4. FIG. 1... Fixing roller 2... Wrap prevention piece 2a...
Support shaft 2b...Tip 8...Support member 8a...
Guide groove 11. 11'... Tangent line 12... Belt part 13... Stopper. Patent Applicant Canon Co., Ltd. Agent Arai - Figure 6 Figure 7

Claims (1)

[Claims] 1. In a sheet wrapping prevention device that prevents a sheet member such as paper from wrapping around a rotating body, the wrapping device is equipped with a member that biases one end of the wrapping prevention piece in a direction where it comes into contact with the surface of the rotating body. A guide member that guides the center of rotation of the prevention piece and the wrapping prevention piece is provided on one side of the sheet member conveyance path to prevent wrapping, and when a load higher than normal is applied, the tip of the prevention piece is released from the rotating body. Composition sheet wrapping prevention device.