JPH02190886A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent such faults as jam paper is caught by a separating claw, torn and left in a device, or the separating claw is damaged, etc., by providing a stopper for controlling a fact that the separating claw is brought to reverse turning exceeding a prescribed value against a spring. CONSTITUTION:As for a separating claw 28, its clockwise turning exceeding a prescribed turning is controlled since its rear end part 28b abuts on a stopper 34. Accordingly, even if a form 50 is jammed and becomes like a bellows in a fixing device 20, and the separating claw 28 is pushed by its jam paper, the separating claw 28 is controlled as to its turning, and it is prevented that its tip 28a descends exceeding a prescribed value. Therefore, even if jam paper is drawn in the A direction, the form 50 can be drawn out smoothly without being caught by the tip 28a of the separating claw 28. In such a way, such faults as jam paper is caught by the separating claw, torn and left in the device, or the separating claw is damaged, etc., are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device in an electrophotographic recording device such as a laser printer or a copying machine.

In the following day's electronic photographic recording apparatus, the sheet I after transfer is conveyed between the fixing roller and the pressure roller of the fixing device.

These rotating rollers apply heat and pressure to fix the visible image. At this time, in order to prevent the paper from wrapping around the fixing roller, the paper is usually separated from the fixing roller by a separating claw.

Fig. 4 shows a conventional fixing device, in which 1 is a fixing roller, 2 is a pressure roller, 3 is a separation claw, 4 is a paper guide plate, and 5 is a pair of paper ejection rollers.1 Separation claw 3 is a part of the fixing device. It is attached to a bracket 7 of the cover 6 so as to be rotatable about a fulcrum 8.

Further, the separation claw 3 is biased counterclockwise by a spring (not shown) so that its tip 3a comes into pressure contact with the surface of the fixing roller 1.

The paper 9 that has been fixed is easily curled due to heat and pressure bonding, and the paper is often jammed without being ejected properly.

However, since the separating claw 3 only presses against the surface of the fixing roller 1 with a small force so as not to damage the surface of the fixing roller 1, if the paper 9 jams in the fixing device as shown in the figure and becomes, for example, bellows-shaped, The paper separation claw 3 is easily rotated clockwise by the jammed paper. If you try to pull out the paper 9 in the direction of arrow A, which is the paper ejection direction, in this state, the paper 9 will be caught by the tip 3a of the separation claw 3, and the paper 9 This caused malfunctions such as the paper being torn and remaining inside the machine, or the separation claw 3 being damaged.

For this reason, conventionally, the direction in which the jammed paper is taken out has been specified in the direction of arrow B, which is the entrance 10 side of the fixing device. However, due to the user's incorrect operation, the paper is pulled out in six directions, or the rear end 9a of the jammed paper is near the entrance 10 and cannot be pulled out in the B direction, and the user is forced to pull it out in the A direction, resulting in the above-mentioned malfunction. It was causing this.

SUMMARY OF THE INVENTION An object of the present invention is to prevent paper from jamming in a bellows-like manner in a fixing device from getting caught on the tip of a separating claw when pulling it out.

In the present invention, in order to prevent the paper after transfer from wrapping around the fixing roller, a separation claw supported so as to be rotatable five times is urged in a predetermined direction by a spring, and the paper is attached to the fixing roller. In the fixing device that is brought into pressure contact with the fixing device, a stopper is provided to prevent the separating claw from rotating in the opposite direction beyond a predetermined value against the spring.

Even if the paper jams in a bellows-like manner in the fixing device and the separation claw is pushed by the jammed paper, the separation claw is prevented from rotating beyond a predetermined degree by the stopper.

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

FIG. 3 shows a schematic nitric acid diagram of a laser printer equipped with a fixing device according to the present invention. In FIG.
3 is a paper feed cassette provided in the printer main body 12. Paper 5 fed from the paper feed cassette 12 in the direction of arrow A
0 is conveyed to a drum-shaped photoreceptor 15 at a timing determined by a registration roller 14 . The photoreceptor 15 is
The photoreceptor 15 is driven to rotate clockwise, and its surface is charged by the charger 16 and irradiated with laser light from the laser optical system 17 to form an electrostatic latent image on the photoreceptor 15 . This latent image is made visible by toner when passing through the developing device 18, and this visible image is transferred by the transfer charger 19 to the paper 50 conveyed to the photoreceptor 15, and the visible image on the transferred paper 50 is is fixed by the fixing device 20. Then, the paper 5o that has left the fixing device 20 is discharged, for example, to a paper discharge section 21 in the direction of the arrow. On the other hand, the cleaning device 22 removes residual toner from the photoreceptor 15 after the visible image has been transferred.

In FIG. 1, the transferred paper 50 conveyed by the conveyor belt 24 is fed from the entrance 25 of the fixing device 20 between the fixing roller 26 and the pressure roller 27, and both rollers 26 rotate in the direction of the arrow. - Heat and pressure is applied by 27 to fix the visible image. After fixing, the paper 50 is separated from the fixing roller 26 by a separation claw 28 whose tip 28a is in pressure contact with the circumferential surface of the fixing roller 26, and is discharged by a pair of paper discharge rollers 30 while being guided by a paper guide plate 29. .

The separation claw 28 is the fixing device fl! It is attached to a bracket 32 of a cover 31 of No. 20 so as to be rotatable about a fulcrum 33. Further, the separation claw 28 has its tip 28a connected to the fixing roller 2.
It is biased counterclockwise by a spring (not shown) so as to lightly press against the surface of 6.

The end of the cover 31 on the exit side is bent into an L-shape, and serves as a stopper 34 for the separation claw 28. The rear end 28b of the separation claw 28 comes into contact with the stopper 34, so that the separation claw 28 is prevented from rotating more than a predetermined amount in the clockwise direction.

According to such a configuration, as shown in FIG.
Even if the paper jams in the fixing device $420 and becomes bellows-like and the separation claw 28 is pushed by the jammed paper, the separation claw 28 is prevented from rotating more than a predetermined amount clockwise by the stopper 34, and its tip 28a is prevented from lowering beyond a predetermined level. Therefore, even if the jammed paper is pulled in the direction of arrow A, the paper 50 can be smoothly pulled out without being caught by the tip 28a of the separation claw 28.

Although the stopper 34 is provided integrally with the cover 31 in the above example, it may be formed as a separate member, and the rotation of the stopper 34 may be restricted by providing the separation claw 28 with a protrusion that comes into contact with the cover 31 or the like. You can do it like this.

X-ho! Date tag 4 According to the present invention, even if paper jams in a bellows shape in the fixing device and the separation claw is pushed by the jammed paper,
Since the separation claw is prevented from rotating beyond a predetermined level by a stopper, the jammed paper can be pulled out smoothly in the paper ejection direction, and the jammed paper can be caught in the separation claw and torn, leaving pieces of paper in the fixing device. , problems such as breakage of the separation claw are also solved.

[Brief explanation of the drawing]

FIG. 1 is a mechanical diagram of a fixing device according to the present invention, FIG. 2 is a diagram showing a state in which paper is jammed in the fixing device, and FIG. 3 is a schematic diagram of a laser printer equipped with the fixing device shown in FIG. 1. FIG. 4 is a mechanical diagram of a conventional example. 20...Fixing device 26...Fixing roller 27...Pressure roller 28...Separation claw 34・・・・・・・・・Stopper Co., Ltd. Nakao 3rd figure

Claims (1)

[Claims] In order to prevent the paper after transfer from being wrapped around the fixing roller, in a fixing device, a rotatably supported separation claw is urged in a predetermined direction by a spring and brought into pressure contact with the fixing roller. A fixing device comprising a stopper that prevents reverse rotation beyond a predetermined amount against the spring.