JP2585400Y2 - Pressing mechanism for fixing unit of electrostatic copying machine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing unit pressing mechanism of an electrostatic copying machine.

[0002]

2. Description of the Related Art In an electrostatic copying machine, a fixing unit for fixing an image transferred onto a transfer sheet is a heating roller (fixing roller) 1 having a built-in heating heater as shown in FIG.
The pressure roller 2 is brought into pressure contact with the
The image is fixed by passing the transfer paper 3 through a nip formed between the two. 1a denotes a heating roller shaft, and 2a denotes a pressure roller shaft. The heating roller 1
Is provided with a pressure mechanism for pressing the pressure roller 2 into pressure. That is, an L-shaped pressing lever 5 whose one end is rotatably supported on a substrate (not shown) by a pressing lever shaft 4 is brought into contact with the lower surface of the pressing roller shaft 2a. A lever 6 having a bent portion 6a is arranged below a bent portion 5a formed at the other end of the
Is vertically slidable on a guide pin 7 fixed to the substrate via a guide hole 6b, and a pressure spring 8 is mounted between the bent portions 5a, 6a. The pressurizing roller 5 is urged by the pressure roller 2 and the adjusting force is adjusted by an adjusting screw 9 screwed between the both bending portions 5a and 6a. Reference numeral 10 denotes a washer.

[0003]

However, in the above-mentioned pressurizing mechanism, when an attempt is made to form a gap between the rollers 1 and 2 in order to remove the transfer paper 3 that has been jammed between the rollers 1 and 2, Although the lever 5 has to be pushed down, since the pressing lever 5 receives the pressing force of the pressing spring 8 properly, the pressing lever 5 must be operated with a greater force than that. It was difficult. for that reason,
If a jam occurs in the fixing unit, the transfer paper 3 may be pulled and broken.
In some cases, the paper pieces were heated, causing a smoke accident.

In order to solve this problem, Japanese Patent Application Laid-Open Nos. 62-164077 and 62-133474 have been proposed. However, in the former case, since the operating lever is operated according to the lever principle, a pressing force higher than the normal pressing force of the spring acts on the pressing roller in the process of releasing the pressure, and the roller is released. This causes a problem of lack of reliability due to the occurrence of distortion and the like. On the other hand, the latter also has a similar problem because a crank mechanism having the same principle is employed.

Therefore, the present invention can easily and reliably engage and disengage the heating roller and the pressure roller with a simple structure and without receiving the strong pressing force of the pressure spring. Moreover, it is an object of the present invention to provide a stable fixing unit pressing mechanism that is easy to maintain.

[0006]

According to the present invention, in order to solve the above-mentioned problems, a pressure lever to which a pressure is applied by a pressure spring is brought into contact with a pressure roller shaft, and the pressure roller is moved. In a fixing unit pressing mechanism of an electrostatic copying machine which is brought into pressure contact with a heating roller, a pressing lever shaft rotatably supporting the pressing lever is connected to the pressing lever shaft and the pressing roller.
The heating roller is interposed between the heating roller shaft and the center of the pressure roller shaft and the heating roller shaft.

Further, when the pressure lever comes into pressure contact with the pressure roller shaft, the pressure lever shaft may be loosely supported in a vertical direction in a long hole provided in the pressure lever. .

Further, the contact point of the pressure lever with the pressure roller shaft may be formed as a curved surface having a radius centered on the pressure lever shaft or a curvature of an approximate value thereof.

[0009]

[Function] Since the pressure lever shaft is provided near a straight line connecting the centers of the heating roller shaft and the pressure roller shaft, the pressing force of the pressure spring does not work properly, and the pressure lever is pressed with a small force. At this time, a clearance can be formed between the pressing lever and the pressing roller shaft, and the pressing roller can be separated from the heating roller.

Further, the pressure lever shaft is loosely fitted and supported in the long hole of the pressure lever, so that the pressure lever can be easily assembled using the clearance with the pressure spring removed.

Further, when the contact point of the pressure lever with the pressure roller shaft is formed into a curved surface, high pressure contact accuracy can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show an embodiment of the present invention, in which, similarly to the embodiment shown in FIG. 7, a pressing lever provided with a pressing force by a pressing spring 8 is brought into contact with a pressing roller shaft 2a. In a fixing unit pressing mechanism for pressing the pressing roller 2 against the heating roller 1, a C-shape including an upper side portion 11, a lower side portion 12, and a vertical side portion 13 connecting one end of the upper side portion 11 and one end of the lower side portion 12. The upper side 11 of the pressure lever 14 is disposed on or near a straight line L connecting the center of the heating roller shaft 1a and the center of the pressure roller shaft 2a. The pressure lever shaft 4 such as an attached stepped screw is rotatably supported through a vertically long hole 16 and is disposed at the upper end position on the straight line L of the upper side portion 11 and above it. A pressure spring (between the spring hook 17 on the substrate 15 side) Multiplied by Zhang spring) 8, the pressure of the spring 8 (tension), the upper surface of the lower side portion 12 and a pressure roller shaft 2a in the contact point A of the pressing lever 14
The gaps B and C are formed above and below the pressure lever shaft 4 at this time. The vertical position of the lever shaft 4 is determined by the distance r from the center of the pressure roller shaft 2a to the contact point A because the heating roller is interposed between the pressure lever shaft 4 and the pressure roller shaft 2a. And the distance R from the center of the pressure lever shaft 4 to the contact point A is r <
R relationship.

Reference numeral 18 denotes an attraction portion for a magnet 19 fixed to the substrate 15 so as to hold the pressing position of the pressing lever 14, and reference numeral 20 denotes a rotating operation of the pressing lever 14 about the pressing lever shaft 4 as a fulcrum. Reference numeral 21 denotes a stopper for regulating the amount of rotation of the pressure lever 14, reference numeral 22 denotes a relief portion for facilitating the release of the pressure roller shaft 2a when the pressure lever 14 is rotated, and reference numeral A beam portion for integrally connecting the pressure lever 14, 24 is a passage hole portion of the transfer paper 3 formed by the beam portion 23, 25 is a tilt stopper of the pressure lever 14, and 26 is for adjusting the pressing force of the pressure spring 8. , A groove provided on the spring hook 17; 27, a bearing of the pressure lever shaft 4; and 28, a washer for preventing the pressure lever shaft 4 from loosening.

The transfer paper 3 on which the image has been transferred enters the nip between the heating roller 1 and the pressure roller 2 from the right side in FIG.
When the paper jam occurs between the rollers 1 and 2 at this time, the operator holds the operation unit 20 and rotates the pressure lever 14 clockwise in FIG. . In this case, as shown in FIG.
The suction portion 18 is detached from the magnet 19, and the lower portion 12 is supported by the
Is rotated to the position corresponding to. As a result, a clearance is formed between the relief portion 22 of the pressure lever 14 and the pressure roller shaft 2a, so that the pressure roller 2 descends by its own weight, and the gap between the rollers 1 and 2 opens, thereby causing jam paper. Can be easily removed. At this time, the pressure lever 14
Is lifted up by the pressing spring 8 by an amount corresponding to the gap C in the long hole 16 supporting the pressing lever shaft 4.

In the above description, the pressure lever shaft 4 is set near a straight line L connecting the center of the heating roller shaft 1a and the center of the pressure roller shaft 2a. 8, the pressing lever 14 can be easily rotated. This is the same principle as lifting the bell and moving it sideways. A distance r from the center of the pressure roller shaft 2a to a contact portion A with the pressure lever 14,
Since the distance R from the center of the pressure lever shaft 4 to the contact portion A is in a relationship of r <R, when the pressure lever 14 is rotated as shown in FIG. It goes far away from the outer circumference of 2a, and a clearance can be formed between them. Moreover, since the relief portion 22 is provided in the lower side portion 12 of the pressure lever 14, the pressure lever 1
This clearance can be increased with only four movements. Further, the length of the long hole 16 is selected so that gaps B and C are formed above and below the pressure lever shaft 4 when the lower side portion 12 of the pressure lever 14 is in contact with the pressure roller shaft 2a. Therefore, if only the pressure spring 8 is removed, it is possible to easily assemble using the clearance, which is advantageous in terms of assemblability.

FIG. 4 shows another embodiment of the present invention, in which a connecting shaft 29 is provided at the upper and lower portions of the vertical side portion 13 instead of the beam portion 23 in the above embodiment. As shown in FIG. 5 where only the lower portion is provided, only one of the upper and lower portions may be provided.

FIG. 6 shows still another embodiment of the present invention. In the embodiment shown in FIG. 4 or 5, the pressure roller shaft 2a on the upper surface of the lower side 12 of the pressure lever 14 is shown.
And a curved surface 30 having a radius of curvature equal to the distance R1 from the center of the pressure lever shaft 4 to the contact point A or an approximate value thereof, and a lower side portion of the pressure lever 14. The connecting shaft 29 is also provided near the front end of the reference numeral 12.

In the case of the embodiment shown in FIG. 6, if the contact point A of the pressure lever 14 with respect to the pressure roller shaft 2a is formed as a curved surface 30, even if the position of the magnet 20 is slightly shifted, There is an advantage that the pressure contact force between the heating roller 1 and the pressure roller 2 can be maintained with high accuracy without substantially affecting the tension pressure, and thus a stable structure can be achieved. Further, since the connecting shaft 29 is provided at a position close to the suction portion 18, there is no twist or bending in operation, and the suction portion 18 is stabilized in a state in which the pressure lever 14 is sucked again from a state away from the magnet 19. It can be adsorbed on the magnet 19.

It should be noted that the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the present invention.

[0020]

As described above, according to the fixing unit pressing mechanism of the electrostatic copying machine of the present invention, the following various excellent effects are exhibited. (1) Since the pressing lever shaft is located near the straight line connecting the center of the heating roller shaft and the center of the pressing roller shaft, the pressing lever can be rotated without receiving the pressing force of the pressing spring. In addition, the distance from the contact point between the pressure roller and the pressure lever to the center of the pressure roller is smaller than the distance from the contact point to the center of the pressure lever shaft. A large clearance can be formed between the pressure lever contact point and the pressure roller shaft, and the engagement and disengagement of the pressure roller with respect to the heating roller can be easily performed. (2) Since the long hole provided in the pressure lever is loosely fitted and supported on the pressure lever shaft, assembly to the fixing unit can be easily performed. (3) Since the pressure lever contact point has a curved surface, the pressure contact accuracy of the pressure roller against the heating roller can be improved, and a stable structure can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a fixing unit pressing mechanism of an electrostatic copying machine according to the present invention.

FIG. 2 is a partially cut-away side view of FIG.

FIG. 3 is a schematic diagram showing an operation state.

FIG. 4 is a schematic view of another embodiment of the present invention.

FIG. 5 is a schematic diagram showing a modification of FIG.

FIG. 6 is a schematic view showing still another embodiment of the present invention.

FIG. 7 is a schematic diagram showing an example of a conventional device.

[Explanation of symbols]

 Reference Signs List 1 heating roller 2 pressure roller 2a pressure roller shaft 4 pressure lever shaft 8 pressure spring 14 pressure lever 16 long hole 30 curved surface L straight line R, R1, r distance A contact point

Claims (3)

(57) [Scope of request for utility model registration] 1. A fixing device for an electrostatic copying machine in which a pressing lever to which a pressing force is applied by a pressing spring is brought into contact with a pressing roller shaft to press the pressing roller against a heating roller. A pressure lever shaft rotatably supporting the pressure lever, wherein a heating roller is interposed between the pressure lever shaft and the pressure roller shaft; A fixing unit pressing mechanism of an electrostatic copying machine, wherein the fixing unit pressing mechanism is set to be located near a straight line connecting a center of a roller shaft and a center of a pressing roller shaft. Wherein the pressure lever is Ka圧Ro - when pressure contact with the La axis and configured to long holes formed in the pressing lever is loosely fitted supported vertically on the pressure lever shaft, wherein Item 2. A fixing unit pressing mechanism of the electrostatic copying machine according to Item 1. 3. A pressing lever pressurized圧Ro - the part of the point of contact with La shaft, and a radius or curved surface having a curvature of the approximate value around the pressure lever shaft, according to claim 1 Pressing mechanism for fixing unit of electrostatic copying machine.