JP2000137405A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of easily performing replacement of a fixing unit, and obtaining a stable paper sheet transport and the fixing strength. SOLUTION: This fixing device is provided with a fixing base 14 equipped with the fixing unit mounting part 14a mounting the fixing unit 10 and bearing holding parts 14b holding the bearing 10c respectively disposed on heating roller both ends, between the attach/detaching position and the fixing position of the fixing unit 10 allowed to freely open/close, arm parts 15 and 16 furnished with the bearing holding parts 15a holding the bearing 10d disposed at pressure roller both ends in a state of closing the fixing base 14 at the fixing position, disposed in freely swingingly with regard to a frame 23 with the fulcrum at the shaft 25 in parallel with the rotary shaft of respective rollers, and pressing means 21, 22 and 24 capable of holding the pressure roller in contact with/apart from with regard to the heating roller by turning the arm parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in which a heating roller and a pressure roller are integrally treated as a fixing unit.

[0002]

2. Description of the Related Art A fixing device in which a heating roller and a pressure roller are handled integrally as a fixing unit is described below.
Conventionally, various proposals have been made.

[0003]

In this type of fixing device, a variation in pressure of a pressure roller due to a cumulative error of component accuracy, a fixing base for fixing a position of a fixing unit and a component constituting a housing of the fixing unit. Due to the change in the position of the pressure roller due to the accumulated error of the component accuracy, the paper conveyed between the heating roller and the pressure roller meanders or wrinkles, resulting in poor fixing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device in which a fixing unit can be easily replaced and a stable sheet conveyance and fixing strength can be obtained.

[0005]

An object of the present invention is to provide a heating roller
(10a) and a fixing unit (10) including a pressure roller (10b),
Fixing unit mounting section (14a) for mounting the fixing unit
And a first bearing holding portion (14b) for holding a bearing (10c) provided at both ends of the heating roller, and is provided so as to be openable and closable between a fixing position and a fixing position of the fixing unit. A fixing base (14), and a second bearing holding portion (15a) for holding bearings (10d) provided at both ends of the pressure roller in a state where the fixing base is closed at the fixing position; Arm portions (15, 15) provided rotatably with respect to the frame (23) around a shaft (25) provided in parallel with the rotation axis of each roller.
16) and pressing means (21,22,2) for rotating the arm part to press / separate the pressure roller from / to the heating roller.
4) is achieved.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. First, a mounting example of the fixing device of the present invention will be described with reference to FIG.
In FIG. 1, a photosensitive drum 1 is supported so as to be rotatable in an arrow direction. As the photosensitive drum 1 rotates, the photosensitive drum 1
The surface is uniformly charged to a predetermined potential by the charger 2, and receives an irradiation beam from the exposure device 3 to form an electrostatic latent image on the photosensitive drum 1. Toner is supplied to the electrostatic latent image that has reached the developing area of the developing device 4, and the electrostatic latent image is visualized as a toner image. The toner image formed on the surface of the photosensitive drum 1 is electrostatically attracted to the paper 6 in a transfer area by the transfer device 5 and is transferred to the paper 6.

The paper 6 is a continuous paper that is continuous in a long form, and has feed holes (not shown) formed at both edges in the width direction at predetermined intervals along the paper transport direction. The paper 6 is transported by the transport puller 7, the paper transport tractor 8, the fixing unit 10, and the fixing puller 11.
The feed holes provided in the paper 6 are mainly used for transport by the paper transport tractor 8. Reference numeral 9 denotes a buffer for absorbing slack or tension generated in the paper 6 due to a difference in the paper transport speed between the paper transport tractor 8 and the fixing unit 10.

The toner image transferred on the paper 6 in the transfer area is conveyed while being heated and pressed between the heating roller 10a and the pressure roller 10b constituting the fixing unit 10, and is fixed on the paper 6. Is done. Pressure roller 10b
Is configured to be in a pressure contact state with the heating roller 10a as shown by a solid line during a printing operation, and to be released from a pressure contact state with the heating roller 10a as shown by a dashed line when stopped.

The paper 6 sent out from the fixing unit 10
Is discharged to the stacker 12 through the fixing puller 11. On the other hand, the toner remaining on the surface of the photosensitive drum 1 without being transferred onto the sheet 6 in the transfer area is removed from the surface of the photosensitive drum 1 by the cleaner 13. The printing operation is continued by repeating the above operation.

Next, the structure of the fixing device will be described in detail with reference to FIGS. The fixing unit 10 includes a heating roller 10
a and a pressure roller 10b. Heating roller 10a
As shown in FIG. 4, bearings 10c are provided at both ends in the axial direction so as to travel from the end face of the heating roller 10a. As shown in FIG. 5, bearings 10d are provided at both ends in the axial direction of the pressure roller 10b so as to protrude from the end surface of the pressure roller 10b.

The fixing base 14 is provided to be openable and closable between a position indicated by a dashed line in FIG. 3, ie, a fixing unit attaching / detaching position, and a position indicated by a solid line in FIGS. 2 and 3, ie, a fixing position. The fixing base 14 is provided with a fixing unit mounting portion 14a on which the fixing unit 10 is mounted, and a bearing holding portion 14b which holds the bearing 10c by engaging with an outer peripheral surface of a bearing 10c provided at both ends of the heating roller. . In FIGS. 2 and 3, reference numeral 26 denotes the fixing base 1.
4 is a latch means for locking in a closed state.

On the other hand, a fixing base 14 is
Arm 1 having a bearing holding portion 15a for holding bearings 10d provided at both ends of the pressure roller in a state where the arm is closed.
5 are provided. The arm 15 is provided rotatably with respect to the frame 23 around a shaft 25 provided in parallel with the rotation axis of each roller. Further, similarly to the arm 15, the frame 23 is provided around the shaft 25 as a fulcrum.
An arm 16 that is rotatable with respect to 3 is provided. At the free end sides of the arm portions 15 and 16, the arm portion 1 is provided.
5, a coil spring 20 sandwiched between a spring holder 19 and the arm portion 16, a pressure adjusting screw 17 attached to the spring holder 19 and adjusting the elastic force of the coil spring 20, and a lock nut 18 are provided. ing.

The frame 23 is provided with a camshaft 21 which is in contact with a cam floor 22 provided on a part of the arm 16. The camshaft 21 is rotated by a motor 24 to The arm unit 15 is rotated via 16 to press / separate the pressure roller 10b from / to the heating roller 10a.

In the above configuration, during printing, the cam shaft 21 is rotated by the motor 24, and pressure is applied to the pressure roller 10b via the cam floor 22, the arm 16, the coil spring 20, and the arm 15. In this state, the heating roller 10a is fixed to the fixing base 14 via the bearings 10c at both ends of the roller by this pressure, and the pressure roller 10b is connected to the arm 1 via the bearings 10d at both ends of the roller.
5 is fixed.

A bearing holding portion 14b of the fixing base 14 for restraining the bearings 10c at both ends of the heating roller 10a, and an arm portion 1 for restraining the bearings 10d at both ends of the pressure roller 10b.
The bearing accuracy of the bearing holding portion 15 a is ensured so as to be parallel to the photosensitive drum 1 and the paper transport tractor 8.
During non-printing, the pressure roller 10b is separated from the heating roller 10a as shown in FIG. In this state, the pressure roller 10b is placed on the arm portion 16 but is not fixed. Therefore, when the fixing base 14 is opened, the fixing unit 10 is simultaneously opened. When the pressure applied from the arm unit 15 to the pressure roller 10b fluctuates for each device, or when imbalance occurs between left and right values, the pressure is adjusted by turning the pressure adjusting screw 17.

According to the above configuration, the heating roller 10a and the pressure roller 10b of the fixing unit 10 and the photosensitive drum 1
And the position accuracy with the paper transport tractor 8 is ensured, and the pressure of the pressure roller 10b can be kept constant. Therefore, occurrence of fixing defects such as meandering and wrinkling of the paper can be prevented, and the fixing unit 10 Exchange can be performed.

[0017]

As described above, according to the present invention, it is possible to provide a fixing device in which the replacement of the fixing unit can be easily performed, and the sheet conveyance and the fixing strength can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an embodiment of a fixing device according to the present invention.

FIG. 3 is a configuration diagram illustrating an embodiment of a fixing device according to the present invention.

FIG. 4 is a perspective view showing an end of a heating roller.

FIG. 5 is a perspective view showing a state of an end of a pressure roller.

[Explanation of symbols]

10: fixing unit, 10a: heating roller, 10b: pressure roller, 10c, 10d: bearing, 14: fixing base,
15, 16: arm portion, 17: pressure adjusting screw, 18: lock nut, 19: spring holder, 20: coil spring, 21: cam shaft, 22: cam floor, 2
3 ... frame, 24 ... motor.

Claims (1)

[Claims] A fixing unit having a heating roller and a pressure roller; a fixing unit mounting portion for mounting the fixing unit; and a first bearing holding portion for holding bearings provided at both ends of the heating roller. A fixing base provided so as to be openable and closable between a fixing position and a fixing position of the fixing unit; and a state in which the fixing base is closed at the fixing position.
A second arm having a second bearing holding portion for holding bearings provided at both ends of the pressure roller, the arm being provided rotatably with respect to a frame around a shaft provided in parallel with a rotation axis of each roller. And a pressing unit configured to rotate the arm unit to press / separate the pressure roller from / to the heating roller.