JP2001318555A - Fixing device - Google Patents

Abstract

(57) [Summary] To provide a fixing device capable of reliably removing jammed paper. A fixing device according to the present invention includes a heat roller (2).
A pressure roller 3 for pressing against the heat roller 2; a pressure means for pressing the pressure roller 3 toward the heat roller 2; and a release lever 7 for releasing the pressing force of the pressure means.
And a release mechanism (4a, 7b) for separating the pressure roller 3 from the heat roller 2 in conjunction with the release operation of the pressing force by the release lever 7. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fixing device in which a pressure roller is pressed against a heat roller.

[0002]

2. Description of the Related Art A fixing device in which a pressure roller is brought into pressure contact with a heat roller is widely known for an image forming apparatus such as a copying machine and a facsimile machine. Some devices have release means for releasing.

FIG. 9 shows a conventional example of a fixing section provided with such a releasing means. FIG. 14A shows the state before the release, and FIG. 14B shows the state after the release. The pressure roller 3 is a movable U-shaped bearing 4 '.
And one end of the bearing 4 'is connected to the first rotating shaft 5a.
And the other end thereof is pressed in the direction of the heat roller 2 by a pressing lever 5 urged by a tension spring 6. As means for releasing the pressurization, the second rotating shaft 7
A release cam 7 for moving the pressure lever 5 is provided on a release lever 7 'supported by the a. As shown in FIG. 2B, when the release lever 7 ′ is pushed down, the pressure lever 5 is lifted via the protruding cam 8, and the pressure roller 4 is released from the elastic force of the tension spring 6. Thereby, jam paper or the like sandwiched between the pressure roller 4 and the heat roller 2 can be removed.

[0004]

However, in the conventional fixing device, when the pressure roller 3 is positioned above the heat roller 2, even if the pressure is released, the pressure on the jammed paper is reduced. The weight of the roller 3 is applied. This becomes a load when removing the jammed paper, and may cause a paper jam again. If the paper is forcibly removed in spite of the weight of the pressure roller 2, the paper is not only torn, the paper fragments remain in the fixing unit, and the paper jam occurs again.
There is a risk of ignition.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to remove jammed paper without resistance, and to remove thin paper or torn paper. However, it is an object of the present invention to provide a fixing device that can surely remove a sheet without leaving a sheet between a pressure roller and a heat roller.

[0006]

In order to achieve the above object, a fixing device according to the present invention comprises a heat roller, a pressure roller pressed against the heat roller, and a pressure roller pressed against the heat roller. In a fixing device including a pressing unit and a releasing unit provided with a releasing lever for releasing the pressing force of the pressing unit, the pressing roller is operated in conjunction with a releasing operation of the pressing force by the releasing lever. And a separating mechanism for separating the heat roller from the heat roller.

[0007] Further, a hooking structure capable of hooking the pressure roller in a direction away from the heat roller is provided on the bearing of the pressure roller, and is brought into contact with the bearing of the pressure roller by interlocking with the release lever. A configuration in which a contact portion that lifts in the separating direction is provided can be provided.

Further, a contact portion for lifting the pressure roller in the separating direction may be provided between the pressure lever and the pressure means of the pressure means interlocked with the release lever.

Further, the pressure roller may have a biasing means for biasing the bearing of the pressure roller in a direction away from the heat roller.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fixing device to which the present invention is applied will be described below with reference to the drawings. 1 and 2
FIG. 2 is a side view illustrating the entire configuration of the fixing device according to the first embodiment.
1 shows the state before the release operation, and FIG. 2 shows the state after the release operation. The fixing device includes a heat fixing roller pair including a heat roller 2 and a pressure roller 3 pressed against the heat roller 2 in a housing 1 having a housing shape. The pressure roller 3 is supported by a bearing 4. I have. The bearing 4 is movable along a bearing rib 4d. A pressure lever 5 is provided at a position opposite to the heat roller 2 with respect to the movable bearing 4, and one end of the pressure lever 5 is supported by a first rotation shaft 5a. The other end of the pressure lever 5
A tension spring 6 for pressure is attached and urged toward the heat roller 2. The first rotation shaft 5a and the tension spring are fixed to the housing 1 side,
A part of the pressure lever 5 presses the bearing 4 toward the heat roller 2 to constitute a pressure means. Bearing 4
On the side of the heat roller 2, a hook structure 4 a for hooking the axis of the pressure roller 3 is provided, whereby the pressure roller 3 is moved in the same direction by the movement of the bearing 4 separated from the heat roller 2. It has become so.

The release means for releasing the pressurized state by the pressurizing means is configured as follows. The release lever 7 has one end outside the housing 1, the other end inside the housing 1 at a position crossing the pressure lever 5, and the other end supported by the second rotation shaft 7 a. I have.
A protruding cam 8 facing the cutout 5b of the pressure lever 5 is fixed to the release lever 7 at the position of the second rotation shaft 7a, and the protruding cam 8 rotates together with the release lever 7. The notch 5b of the pressure lever 5 has a curvature whose radius with respect to the second rotating shaft 7a gradually changes, and a recess is formed at the lower end thereof so that the tip of the protruding cam 8 can be hooked. This allows
The downward pivoting movement of the release lever 7 about the second pivot shaft 7a causes the upward movement of the pressurizing lever 5 about the first pivot shaft 5a via the protruding cam 8. This is converted into a rotational motion, and the pressurized state on the bearing 4 is released.

The separation mechanism interlocked with the release operation of the pressurized state includes a hooking structure 4 a of the pressure roller 3 provided on the bearing 4 and a contact portion 7 protruding from the other end of the release lever 7.
As shown in FIG. 2, in a released state in which the tip of the protruding cam 8 is engaged with the recess of the notch 5b, the contact portion 7b contacts the hooking structure 4a of the bearing 4 and the pressure roller 3 Is maintained in a state separated from the heat roller 2.

FIG. 3 and FIG. 4 are views showing an embodiment of the hook structure 4a. FIG. 5 is a perspective view of the release lever 7 having the contact portion 7b. FIG. 3 shows a hook structure 4a that wraps around the axis of the pressure roller 3 in the form illustrated in FIGS. In this case, the plate-shaped contact portion 7b shown in FIG.
In this combination, the separated state is maintained by mutual surface contact.

Further, as shown in FIG. 4 (a), the hooking structure 4a may have a curvature so as to make line contact with the contact portion 7b, or as shown in FIG. A key shape may be provided such that the axis of the roller 3 is not completely wrapped and the axis of the pressure roller 3 does not come off.

FIGS. 6A and 6B are diagrams showing the main parts of a fixing device according to a second embodiment. FIG. 6A shows a state before the releasing operation, and FIG. 6B shows a state after the releasing operation. FIG. 7 is a perspective view of the bearing 4. In the second embodiment, a projection 4b is provided on a bearing rib 4d of the bearing 4 as a contact portion for lifting the pressure roller 3 in a separating direction, and a groove 5c for holding the projection 4b is provided on the pressure lever 5 side. I have. As shown in FIG. 6, when the pressure lever 5 rotates upward about the first rotation shaft 5a in conjunction with the downward rotation of the release lever 7, the pressure lever 5 The protrusion 4b in the groove 5c is lifted in a direction away from the heat roller 2. As shown in FIG. 3B, in the released state, the projection 4b is hooked on the groove 5c of the pressure lever 5, and the pressure roller 3 is separated from the heat roller 2 via the hooking structure 4a of the bearing 4. Is maintained. FIG.
FIG. 4B is a perspective view of the bearing 4 of the first embodiment, and FIG. 4B is another example of the bearing 4 functioning as a contact portion. Thus, the form of the contact portion provided on the bearing 4 is an L-shaped bend 4
In any case, the movement of the pressure lever 5 and the movement of the bearing 4 may be linked to each other, so long as the separated state of the pressure roller 3 can be maintained at the time of release.

FIGS. 8A and 8B are diagrams showing the main components of a fixing device according to a third embodiment. FIG. 8A shows the state before the release operation, and FIG. 8B shows the state after the release operation. In the third embodiment, as a separating mechanism, an urging means including a compression spring 9 for urging the bearing 4 of the pressure roller 3 in a direction away from the heat roller 2 is provided. The distal end of the compression spring 9 has a hooking structure 4 for the bearing 4.
The base is fixed to the housing 1 (not shown) via a spring base 10. Before the release of FIG. 8A, the compression spring 9 is in a compressed state between the bearing 4 and the spring base 10, and in the released state, as shown in FIG. The pressure roller 3 released from the opening is lifted by the elastic force of the compression spring 9, and the separated state is maintained. The compression spring 9 is weaker than the tension spring 6 for applying pressure and does not affect the fixing pressure.
An elastic force sufficient to lift the pressure roller 3 and its bearing 4 in the direction of the arrow is set. In addition, such an urging means may be used in combination with each of the above embodiments.

[0017]

As is apparent from the above description, the fixing device of the present invention has a separation mechanism for separating the pressure roller from the heat roller in conjunction with the release operation of the pressing force by the release lever. Jam paper etc. can be pulled out without resistance, and even if the user pulls thin paper or tearing paper forcibly or diagonally, there is no torn paper piece between the pressure roller and heat roller, and it is sure. It can be removed.

[Brief description of the drawings]

FIG. 1 is a side view showing a state before a releasing operation of a fixing device of a first embodiment.

FIG. 2 is a side view showing a state after a releasing operation of the fixing device of the first embodiment.

FIGS. 3A and 3B show an embodiment of a bearing provided with a hooking structure, wherein FIG. 3A is a state in which the bearing is assembled in a fixing device, and FIG. 3B is a perspective view of the bearing.

4A and 4B show another embodiment of a bearing provided with a hooking structure. FIG. 4A is a perspective view of a bearing provided with a curvature, and FIG. 4B is a perspective view of a bearing provided with a partial hooking structure. is there.

FIG. 5 is a perspective view showing a release lever having a contact portion.

FIGS. 6A and 6B are diagrams illustrating a main configuration of a fixing device according to a second embodiment, in which FIG. 6A illustrates a state before the release operation, and FIG. 6B illustrates a state after the release operation.

FIGS. 7A and 7B are perspective views of a bearing functioning as a contact portion. FIG. 7A is a diagram showing the bearing of FIG. 6, and FIG.

8A and 8B show a main configuration of a fixing device according to a third embodiment. FIG. 8A shows a state before the releasing operation, and FIG. 8B shows a state after the releasing operation.

FIG. 9 is a main part configuration diagram showing a release unit of a conventional fixing device.

[Explanation of symbols]

 Reference Signs List 2 heat roller 3 pressure roller 4 pressure roller bearing 4a hooking structure 5 pressure lever 7 release lever 7b, 4b, 4c contact part 9 compression spring (biasing means)

Claims (4)

[Claims] 1. A heat roller, a pressure roller pressed against the heat roller, pressure means for pressing the pressure roller against the heat roller, and a release lever for releasing the pressure of the pressure means And a releasing mechanism for releasing the pressing roller from the heat roller in conjunction with the release operation of the pressing force by the releasing lever. 2. A pressure roller bearing having a hooking structure capable of hooking the pressure roller in a direction away from the heat roller, and interlocking with the pressure roller bearing in cooperation with the release lever. The fixing device according to claim 1, further comprising a contact portion that is lifted in a separating direction. 3. The pressure lever according to claim 1, wherein a contact portion that lifts the pressure roller in a separating direction is provided between the pressure lever and the pressure unit of the pressure unit that interlocks with the release lever. 3. The fixing device according to 2. 4. The fixing device according to claim 1, further comprising an urging unit that urges a bearing of the pressure roller in a direction away from the heat roller.