JPS60134265A - Device for preventing winding of sheet member - Google Patents

Abstract

PURPOSE:To prevent damage on the surface of a rotating body and at the tip of a winding preventive piece by making the winding preventive piece movable around the fulcrum shaft thereof and receiving the pressure of a receipt member by a guide member. CONSTITUTION:The fulcrum shaft 2a at the turning center moves along the guide groove 8a of a supporting member 8 when certain force F acts on the bottom surface of a winding preventive piece 2 owing to generation of a jam. The piece 2 retreats in the advancing direction of a sheet member 4 and is hidden in a guide member 8b when the force F increases further to force up the piece 2. Most of the force F by the jammed paper acts to the fixed member 8b in this state and only the force holding the position of the piece 2, i.e., the reaction of the force trying to return said piece by an energizing member 10 acts on said piece and therefore no matter how much the force increases, the force that the piece 2 receives does not change and the piece 2 does not damage the surface of a fixing roller and does not damage itself.

Description

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

Conventionally, in order to prevent this kind of wrapping, wrapping prevention pieces as shown in FIGS. 1, 2, 3, and 4 have been provided. 1st
In the figure, the rotation center axis 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-wrapping piece 2, that is, prevents wrapping. 1/ indicates a so-called bite-like wrapping prevention piece 2 disposed on the opposite side of the fixing roller l from the tangent line 0-O at the tip 2b of the piece 2, and l/ is a pressure roller that presses against the fixing roller l.

As disclosed in Japanese Utility Model Application Publication No. 53-511f18, FIG.
It shows the so-called free-flowing anti-wrapping piece placed on the side.
In the free escape arrangement shown in FIG. 2, when a large upward force is applied to the tip 2a of the wrapping prevention piece 2, the tip 2a of the wrapping prevention piece 2
b escapes in the direction away from the fixing roller 1, and the surface of the fixing roller l coated with a heat-resistant release rubber such as silicone rubber, fluorosilicone rubber, or fluorosilicone rubber, or tetrafluoroethylene coating, etc., or the surface of the fixing roller l for pressure fixing. Damage to the metal surface of the roller and the tip 2b of the anti-wrapping piece 2 can be prevented.

In the device disclosed in Japanese Utility Model Application 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 shows the chain line. Since it is configured to escape as shown in FIG. Since the anti-wrapping piece 2 is pressed against the fixing roller l only by the elastic force of the elastic support 3 that is immovably attached, the tip 2b of the anti-wrapping piece 2 escapes in the direction away from the fixing roller 1 due to a large load, so it is separated. I'm worried about my abilities.

In the device disclosed in Japanese Utility Model Application Publication No. 55-133451 shown in FIG. 4, the wrapping prevention piece 2 has a compression spring 5 inserted into its spring guide 2C, and is guided to a support 6 with the compression spring 5 sandwiched therebetween. The wrapping prevention piece 2 is provided so that the tangent 0-0 connecting the support shaft 6a of the support body 6 and the tip 2b of the wrapping prevention piece 2 is
The distal end 2b is configured to move forward and backward. When the force of the sheet member 4 is applied, the compression spring 5 is bent, and the wrapping prevention piece 2
The distance between the tip 2b of the support 6 and the support shaft 6a of the support 6 decreases, and the support 6 rotates counterclockwise due to the biasing force of the spring 10. Therefore, the tangent line drawn from the support 6a to the fixing roller l From 0-0, the tip 2b of the anti-wrapping piece 2 enters the fixing roller 1, resulting in a so-called biting state, which applies a large amount of force to the tip 2b of the anti-wrapping piece 2 and the surface of the fixing roller l, preventing the wrapping. This has the drawback of significantly increasing wear on the prevention piece 2 and the fixing roller l.

However, in the above-mentioned sheet wrapping prevention device, when a so-called jam condition as shown in FIG. As a result, a large load F is applied from below to the wrapping prevention piece 2, and the tip 2b of the wrapping prevention piece 2 is strongly pressed against the fixing roller, often damaging the fixing roller l and the tip 2b' of the wrapping prevention piece 2. However, there are also restrictions on the material of the anti-wrapping piece 2 itself.

The present invention has been proposed in view of the above, and is caused when the anti-wrapping piece that separates the sheet member from the rotating body bites into the rotating body and jams when the sheet member is separated. It is an object of the present invention to provide an anti-wrapping piece which is free from damage to the anti-wrapping piece and the rotating body, and which is not subject to limitations on the material of the anti-wrap piece itself.

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, and FIG. 7 is a plan view thereof.

The anti-wrapping piece 2 is made of a heat-resistant material such as PPS, polyamideimide, or polyimide, metal, or a metal surface coated with a releasable coating such as a fluororesin coating, and its spindle 2a is rotatably attached to a support member. 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 0-wrap prevention piece 2 inserted into the guide groove 8a of 8. 2a in the counterclockwise direction, the tip 2b of the anti-wrapping piece 2 comes into contact with the circumferential surface of the fixing roller l, and the support shaft 2a remains in contact with the end of the guide groove 8a on the sheet conveyance path side. Continue to do so.

This state does not change even when the sheet member 4, which is conveyed between a fixing roller and a pressure roller and has a toner image fixed thereon, wraps around the fixing roller, hits the tip 2b of the anti-wrapping piece 2, and is separated. .

When the tip of the sheet member 4 hits the tip 2b of the wrapping prevention piece 2 (the central wrapping prevention piece in FIG. 7), the wrapping prevention piece 2 receives a force in the tangential line o-o direction. The force acts in the direction of pressing the tip 2b of the anti-wrapping piece 2 against the fixing roller, and the support shaft 2a is held in its position by the biasing force of the spring 10.

Further, the support member 8 is a guide member 8 that is located close to the wrapping prevention piece 2 and guides the sheet member P separated from the fixing roller by the wrapping prevention piece 2 to the pair of paper discharge rollers 12 and 13.
It also serves as b. The guide groove 8a is connected to the wrapping prevention piece 2.
until it is completely hidden by the guide member 8b, and
A line P-P connecting the tip 8b of the guide member 8b/ and the center of the fixing roller
The movement range is such that the tip end 2b of the anti-wrapping piece comes to the side opposite to the sheet conveyance path.

Note that the mounting of the support members 8 is structured such that, in the illustrated example, a pair of support members 8 are mounted at a predetermined interval on a long and narrow fixing plate 80 disposed parallel to the axis of the fixing roller l, and one of the support members 8 is supported. The member 8 is made long so that it also serves as a guide member 8b for the sheet member 4. Then, the hole 2 of the anti-wrapping piece 2
The support shaft 2a is inserted into the support shaft 2a, and both ends of the support shaft 2a are loosely fitted into the guide grooves 8a of the pair of support members 8.

The embodiment of the present invention has the above-mentioned configuration; - When a certain force F is applied to the lower surface of the anti-wrapping piece 2 due to occurrence of a jam as shown in FIG. Move along the guide 1ll18a.

When the force F increases further and pushes up the wrapping prevention 2,
The wrapping prevention piece retreats in the advancing direction of the sheet member 4 and is in the state shown in FIG. 8 where it is hidden behind the guide member 8b. In this state, most of the force F due to the jammed paper acts on the fixed guide member 8b, and the anti-wrapping piece 2 has a force that maintains its position, that is, a reaction force of the force that tries to return it by the biasing member 10. Only the light is on. Therefore, no matter how much the force F increases, the force applied to the wrapping prevention piece 2 does not change, and the wrapping prevention piece 2 may damage the surface of the fixing a-te 1, or the wrapping prevention piece itself may be damaged. Not at all. The operator manually removes the jammed paper as usual by looking at the jam display.

In addition, as shown in FIG.
In the case of a jam caused by the sheet member passing through the tip 2b of the fixing roller 1, the sheet member in that part tries to move in the direction of rotation of the fixing roller l due to friction with the fixing roller l, but as shown in FIG. Since the wrapping prevention piece 2 is already separated from the surface of the fixing roller 1, the wrapping prevention piece 2 is already separated from the surface of the fixing roller 1.
′ prevents progress. Therefore, the wrapping prevention piece 2
The vicinity 2b of the tip of I is subjected to a load approximately in the tangential 0-0 direction. In this case as well, if the guide member 8b is extended close to the fixing roller l, the anti-wrapping piece 2 will move smoothly under the load from the sheet member, and its tip will be at the center of the tip of the guide member 8b and the fixing roller l. When the guide member 8b is retracted above the line PP connecting the sheet members, the load from the sheet member is received by the guide member 8b, so that damage to the surface of the fixing roller 1 can be prevented. In FIGS. 9 and 10, a dash is added to the reference numeral of the anti-wrapping piece to indicate that the position is different in the axial direction of the fixing roller l.

FIG. 11 shows another embodiment of the present invention, in which the anti-wrapping piece 2 leaves only the minimum necessary tip portion to separate the sheet member from the fixing roller l, and the other portions are used for normal operation. It is also configured to be hidden behind the guide member 8b as much as possible, that is, located behind the guide member in the traveling direction of the sheet member.

With this configuration, the wrapping prevention piece 2 can receive all the load caused by the jammed sheet member on the guide member 8b, except when the load is applied to the tip of the anti-wrapping piece 2 in various jams. Furthermore, safety can be improved.

As detailed above, according to the present invention, in order to separate the sheet member that is clinging to the surface of the rotating body and is about to be transferred from the rotating body, the sheet member is urged in the direction of contacting the rotating body by the urging member. The support shaft of the anti-wrapping piece is made movable, and the anti-wrapping piece retreats behind the adjacent guide member in response to pressure from the sheet member that occurs when a jam occurs, and the pressure from the sheet member is received by the guide member. This has the effect of providing a sheet wrapping prevention device that prevents damage to the surface of the rotating body and the tip of the wrapping prevention piece and eases restrictions on the material of the wrapping prevention piece itself.

The fixing roller has a heat-resistant elastic layer 12 such as silicone rubber, fluorosilicone rubber, or fluorosilicone rubber, or a heat-resistant resin layer 12 such as PTFE or PFA on the outer peripheral surface of a hollow roller core 11 made of aluminum, stainless steel, or an equivalent metal. 2
It is provided with a thickness of 0 to 1000 #L. Pressure loaf l
For example, a metal roller/core 11 has a relatively thick elastic layer 12/ made of silicone rubber, fluorosilicone rubber, fluorosilicone rubber, etc. on the outer peripheral surface of the core 11 (for example,
1 fat to 10m servings). Heaters H,)(' are built into the axes of these fixing rollers and pressurizing rollers a and fl.

Further, in this embodiment, a heating fixing rope is used as an example of a rotating body, but the present invention can be applied to prevent a sheet member from being wrapped around various other rotating bodies such as a roller for pressure fixing.

[Brief explanation of drawings]

1, 2, 3, and 4 are schematic diagrams of the conventional wrapping prevention device, FIG. 5 is an explanatory diagram when a jam occurs, and FIG. 6 is a first diagram of the wrapping prevention device of the present invention. 7 is a plan view of a part of the embodiment, FIG. 8, FIG. 9, and FIG. 10 are explanatory diagrams when a jam occurs, and FIG. 11 is a second view of the wrapping prevention device of the present invention.
It is a front view showing an example. l is a fixing roller, l is a pressure roller, 2 is a wrapping prevention piece, 2
a is a support shaft, 8 is a support member, 8a is a guide groove, and 10 is a biasing spring. JP-A-6O-I (42 (i5 (4)

Claims (1)

[Claims] (1) An anti-wrapping piece that prevents the sheet member from wrapping around the rotating body is rotatably provided around a fulcrum shaft, and one end of the anti-wrapping piece is biased in the direction of contacting the rotating body. A wrapping prevention device for a sheet member comprising a member and a guide member for the sheet member separated from the surface of the rotating body, wherein the fulcrum shaft of the wrapping prevention piece is movably provided, and the wrapping prevention piece guides the sheet member. A wrapping prevention device for a sheet member, characterized in that the movement range of the fulcrum shaft is determined so that it can move to the rear of the member.