JP2960738B2 - Fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device such as a printer or a copying machine using an electrostatic copying process.

Prior art As a fixing device of the above type, an unfixed toner image is heated and
A pair of rollers that press and fix the transfer material, a separation claw for separating the transfer material from the roller, a spring that urges the separation claw in a direction in which the separation claw comes into contact with the roller surface, and are mounted on the device frame; An apparatus having a paper ejection guide member for guiding the transfer material to the outside of the apparatus is already known. An apparatus of this type in which a separation claw is held by a paper discharge guide member is also known, and is described in Japanese Utility Model Laid-Open No. 59-33052.

This fixing device is provided with hinge portions at both ends of the discharge guide plate so that the discharge guide plate can be opened and closed with respect to the roller pair for the purpose of facilitating jam paper processing, and the hinge portion is attached to the frame. It is held so that it can rotate freely. In this case, the paper discharge guide plate is fixed to the frame through screws or pins in the hinge portion. The separation claw attached to the paper ejection guide plate is in contact with a regular position of the fixing roller. In order to perform this contact accurately, it is necessary to fix the position of the paper discharge guide plate, and although not described in the above publication, the paper discharge guide plate is biased by a spring or the like to be positioned at a predetermined position. Means of holding fixed must be used.

However, the use of the above-mentioned screw of the hinge portion and the holding means of the paper discharge guide plate has a problem that the number of components increases and the assembly becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a fixing device that can reduce the number of parts and can be easily assembled without impairing the easiness of jam paper processing. And

Means for Solving the Problems In order to achieve the above object, the present invention provides a pair of rollers for fixing an unfixed toner image to a transfer material by heating and pressing, and a separation claw for separating the transfer material from the rotor. And a spring for urging the separation claw in a direction in which it comes into contact with the roller surface,
A sheet discharge guide member mounted on an apparatus frame and guiding the transfer material to the outside of the apparatus, wherein the separation claw is held by the sheet discharge guide member via a rotation shaft.
A shaft portion having a portion having a width smaller than that of a direct line, a notch formed in a side plate of the device frame, having a width smaller than the diameter of the shaft portion and larger than the small width portion, and inserting a shaft portion of the notch; A stopper portion provided on the downstream side in the direction, and the discharge guide member is configured such that when the narrow width portion of the shaft portion is fitted into the notch and the separation claw contacts the roller,
The separation claw is rotated by a reaction force of the spring that urges the separation claw in a direction in which the separation claw contacts the roller, and the shaft portion hits the stopper portion and is held by the apparatus frame.

Operation According to the above configuration. Since the sheet discharge guide member is held by the apparatus frame by the reaction force of the spring that urges the separation claw against the roller, a fixing tool such as a screw and a spring for holding the position are not required, and the number of parts can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view of a laser printer provided with a fixing device according to the present invention.

In FIG. 1, a recording sheet 2 fed from a sheet feeding device 1 in the direction of arrow A is conveyed to a latent image carrier composed of a drum-shaped photosensitive member 4 at a timing by a pair of registration rollers 3. The photoconductor 4 is driven to rotate clockwise, and the surface thereof is charged by the charging charger 5 at that time. Then, a laser beam L from the laser optical system 6 is irradiated to form an electrostatic latent image on the photoconductor. This latent image is stored in the developing device 7
When the recording paper 2 passes through the photoconductor 4, the visible image is transferred to the recording paper 2 conveyed to the photoconductor 4 by the transfer / separation charger 8, and the recording paper 2 adhered to the photoconductor 4 is electrostatically charged. Separated. Thereafter, the recording paper 2 is transferred to the fixing device 9.
Thus, the visible image is fixed, fed in the direction of arrow B, and discharged to the discharge unit 10. On the other hand, the residual toner is removed from the photoconductor 4 after the transfer of the visible image by the cleaning device 11 having the cleaning blade 12. The toner removed from the photoconductor is collected in a toner collection tank 13 and stored therein.

As shown in FIG. 2, the fixing device 9 has a configuration in which the transfer material 2 passes through the upper surface of the photoreceptor 4 in this embodiment, so that the image surface of the transfer material 2 entering the fixing device 9 is on the lower side. The configuration of the roller pair also makes the upper side a pressure roller
15, the fixing roller 14 is disposed on the lower side.
A heater 16 is built in the fixing roller 14, and a temperature control element such as a thermistor 17 and a thermostat 18 is in contact with the surface.

The fixing device 9 has an entrance guide 19 for guiding the transferred transfer material 2, a separation claw 20 for separating the transfer material wound around the fixing roller 14, and a discharge guide member for guiding the transferred transfer material 2 to be discharged. An outlet guide 21 and a separation claw 20
Is urged by a spring 22 in a direction in which it comes into contact with the fixing roller 14.

The fixing device 9 according to the present invention relates to the structure of the device frame 23 that supports the outlet guide 21, the spring 22, the separation claw 20, and the outlet guide 21 described above.
This will be described in detail with reference to the drawings.

As shown in FIG. 3, the outlet guide 21 is provided integrally with a shaft portion 24 having a substantially oval cross section at both ends in the longitudinal direction, and the shaft portion 24 has a small width portion smaller in width than its diameter. The notch 25 formed in the device frame 23 is fitted. That is, the width of the notch 25 is set to be smaller than the diameter of the shaft portion 24 but larger than the small width portion, and the space where the shaft portion 24 can rotate at the tip side of the notch portion 25 and the small width portion correspond to the rotation. A contacting stopper 25a is formed. Exit guide 2
In FIG. 1, holding portions 26 for holding the separation claws 19 are formed at appropriate intervals in the longitudinal direction, and a U-shaped groove 27 is formed in the holding portion 26, and the rotation of the separation claw 20 is formed in the groove 27. Shaft
28 is inserted. When the separating claw 20 is fitted, a torsion coil-shaped spring 22 is fitted on the rotary shaft 28, and one end 22a of the spring 22 is locked in a slot 29 of the outlet guide 21 as shown in FIG. The other end 22b of the spring 22
The separation claw 20 is locked by the claw so as to urge the separation claw 20 in a direction of contacting the fixing roller 14. The shaft 24 is formed so as to be substantially coaxial with the rotation shaft 28 of the separation claw 20 fitted in the groove 27.

Thus, when the separation guide 20 and the outlet guide 21 on which the spring 22 is mounted are attached to the device frame 23, the straight portion of the oval shaft portion of the shaft portion 24 is adjusted to the notch width of the notch portion 25 of the device frame 23. And insert it diagonally and hit the back of the cutout 25. By this insertion butting operation, the separation claw 20 abuts against the fixing roller 14, and the outlet guide 21 receives a reaction force in the counterclockwise direction in FIGS. 4 and 5 by the spring 22.
Due to this reaction force, the exit guide 21 rotates counterclockwise,
It is held at a regular position by hitting a positioning stopper 25a provided on the device frame 23.

According to this configuration, the exit guide 21 holding the separation claw 20
Can be assembled to the apparatus frame 23 with a simple operation, and the number of parts can be reduced because screws are not used.

By the way, the exit guide 21 is not opened with respect to the roller pair as in the related art, but a load is applied to the side of the exit guide 21 close to the fixing roller 14 due to the separation failure due to the transfer material trying to enter under the separation claw 20. In this case, by rotating the exit guide 21 clockwise against the action of the spring 22, the interval between the fixing roller 14 and the exit guide 21 is increased, and the jammed paper can be easily processed.

Note that the present invention can naturally be applied to a fixing device in which the fixing roller is disposed above and the pressure roller is disposed below.

According to the above configuration, the present invention can hold the exit guide holding the separation claw in a proper position without using a screw or a biasing spring, and can easily perform the attaching / detaching operation. Therefore, the cost is low and the assembling work is easy,
Service and maintenance are also improved.

[Brief description of the drawings]

1 is an overall view of a printer to which a fixing device according to the present invention is applied, FIG. 2 is an enlarged view of the fixing device, FIG. 3 is a perspective view of an exit guide and a device frame, and FIG. FIG. 5 is a side view of the exit guide mounted on the apparatus frame. 2 Transfer paper 14 Fixing roller 15 Pressure roller 20 Separating claw 21 Exit guide 22 Spring 23 Device frame

Claims (1)

(57) [Claims] A pair of rollers for fixing an unfixed toner image to a transfer material by applying heat and pressure to the transfer material; a separation claw for separating the transfer material from the roller; and a separation claw in a direction in which the separation claw contacts the roller surface. A spring that biases and is attached to the device frame,
A discharge guide member for guiding the transfer material to the outside of the apparatus, wherein the separation claw is held by the discharge guide member via a rotating shaft; provided at both longitudinal ends of the discharge guide member A shaft portion provided with a portion having a width smaller than the diameter, a notch formed on the side plate of the device frame, having a width smaller than the diameter of the shaft portion and larger than the small width portion, and a shaft of the notch. A stopper provided on the downstream side in the part insertion direction, wherein the discharge guide member is configured such that a small width portion of the shaft portion is fitted into the notch and the separation claw contacts the roller. A fixing device configured to rotate by a reaction force of the spring that urges the separation claw in a direction in which the separation claw contacts the roller, so that the shaft portion hits the stopper portion and is held by the apparatus frame.