JPH11202660A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device preventing the breaking of a heater caused by the collision of the inner periphery of a roller main body with a heater at a color fixing device provided with the heater at the inside of a pressing roller brought into press-contact with a heating roller and constituting the pressing roller of the roller main body which is freely movable and the heater arranged at the inside of the roller main body. SOLUTION: As for the fixing device provided with the heating roller 3 provided with the heater at the inside, the pressing roller 4 provided with the heater at the inside and a pressing lever 5 bringing the pressing roller 4 into press-contact with the heating roller 3 and heating and fixing a toner image on transfer paper while pressing it at the time of passing the transfer paper holding the toner image through the nip part of both rollers; the pressing roller 4 is provided with a hollow roller main body 15 movable back and forth to the heating roller 3 and the heater 16 arranged at the center part of the roller main body 15, and a holder 20 positioning and holding the heater 16 at the inside of the roller main body 15 is attached at the pressing lever 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an improvement in a heat fixing device used in an image forming apparatus such as a printer and a facsimile apparatus, and more particularly, to an improvement in a support structure of a heater arranged in a pressure roller constituting a fixing device used in a color image forming apparatus.

[0002]

2. Description of the Related Art In a color image forming apparatus, after a color toner image is transferred onto a transfer sheet in an image forming section, the transfer sheet is heated while being pressed while passing through a fixing device. The toner image is fixed.
As is well known, the fixing device is heated by pressing a pressure roller against a heating roller having a heater therein, and passing a transfer paper holding an unfixed toner image through a nip portion of both rollers. While pressing, the toner image is fixed on the transfer paper. Incidentally, a fixing device used in a color image forming apparatus is different from a fixing device of a normal monochrome copying machine in that a heater is provided not only in a heating roller but also in a pressure roller. That is, the pressure roller has a hollow cylindrical roller main body and an infrared heater arranged at the center thereof, and the holder is positioned and held at the center position of the roller main body by the holder. FIG. 2 is a configuration diagram of a conventional color fixing device.
The heating roller 3 is located on the upper side of the paper passing path 2 in the case 1.
The pressure roller 4 is urged toward the heating roller by a pressure lever 5 and a pressure spring 6. The heating roller 3 has a fixing heater 11 at the center of the roller body 10. The pressure roller 4 has a pressure heater (infrared heater) 16 at the center of the roller body 15.
The pressure heater 16 is located at the center of the roller body 15 in the optimum pressure state. The fixing heater 11 is fixedly held at a fixed position by a holder 12 having one end fixed to the case 1, and the pressure heater 16 is fixedly held at a fixed position in the roller body 15 by a holder 17. That is, the pressure roller 4
On the side, only the roller body 15 can move up and down, and the heater 16 is in a fixed state. Accordingly, for example, when the pressing force from the pressing lever 5 to the pressing roller 4 changes or when the pressing is released by replacing the roller, the roller body 15 of the pressing roller 4 advances and retreats in the pressing releasing direction. Since the position of the pressurizing heater 16 is fixed by the holder 17, the heater 16 collides with the inner wall of the roller main body 15, and a trouble such as breakage of the heater occurs.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a color fixing device having a heater inside a pressure roller which is in pressure contact with a heating roller, wherein the roller body has a movable pressure roller. Another object of the present invention is to provide a fixing device including a heater disposed in a roller body and capable of preventing breakage of the heater caused by collision of the inner periphery of the roller body with the heater.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, a first aspect of the present invention is a heating roller having a heater inside, a pressure roller having a heater inside, and a heating roller having a heating roller. A pressure lever for pressing the toner image on the transfer paper while pressing the toner image on the transfer paper while passing the transfer paper holding the toner image through the nip portion of both rollers. The pressure roller includes a hollow roller body that can advance and retreat toward the heating roller, and a heater disposed at the center of the roller body, and a holder that positions and holds the heater in the roller body is attached to the pressure lever. Was.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is an explanatory view showing a configuration of a color fixing device according to an embodiment of the present invention. In this fixing device, a heating roller 3 is pressed upward with a paper passing path 2 in a case 1 therebetween, and a pressing roller is pressed downward. The pressure roller 4 is urged toward the heating roller by a pressure lever 5 and a pressure spring 6. The heating roller 3 has a fixing heater 11 at the center of the roller body 10. The heating roller 3 is, for example, a roller body 1 by a bearing 1a provided in the case 1.
The 0 shaft portion 10a is rotatably supported. The pressure roller 4 is rotatably supported on a shaft 15 a of a roller body 15 by a bearing 1 b provided on the case 1, for example. The pressure roller 4 includes a pressure heater (infrared heater) 16 at the center of the roller body 15, and is configured such that the pressure heater 16 is located at the center of the roller body 15 in an optimum pressure state. ing. Further, the fixing heater 11
Is fixedly held at a fixed position by a holder 12 having one end fixed to the case 1. The pressure heater 16 is moved by the holder 20 fixed to the pressure lever 5 by the roller body 1.
5. That is, since the pressurizing heater 16 of this embodiment is integrated with the pressurizing lever 5 via the holder 20, when the roller main body 15 moves up and down in the vertical direction, the heater 16 also moves integrally up and down. It is configured to be. Therefore, there is no room for collision to occur due to the relative movement between the roller body 15 and the heater 16, and damage to the heater due to the collision is prevented. Further, when the pressing roller 4 advances and retreats, the heater 16 always moves at the center position of the roller main body 15 and moves integrally with the roller main body. Positioning allows proper heating.

[0006]

As described above, according to the present invention, there is provided a color fixing device provided with a heater inside a pressure roller which is in pressure contact with a heating roller, wherein the roller body has a movable pressure roller, , The breakage of the heater caused by the collision of the inner periphery of the roller body with the heater can be prevented.
That is, in the fixing device of the present invention, since the heater is fixed to the pressure lever that presses the pressure roller, the roller body and the heater always move up and down in a fixed positional relationship, and the collision caused by the relative movement between the two companies. Thus, breakage of the heater can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of a fixing device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a conventional fixing device.

[Explanation of symbols]

1 case, 2 paper path, 3 heating roller, 4 pressure roller, 5 pressure lever, 6 pressure spring, 10
Roller body, 11 Fixing heater, 15 Roller body, 1
6 Pressurized heater, 20 holders.

Claims (1)

[Claims] 1. A heating roller having a heater inside, a pressure roller having a heater inside, a pressure lever for pressing the pressure roller against the heating roller, and a toner image is formed in a nip portion between both rollers. A fixing device that heats and fixes the toner image on the transfer paper while applying pressure when passing the transfer paper holding the transfer paper, wherein the pressure roller is a hollow roller body that can advance and retreat toward the heating roller; A fixing device comprising: a heater disposed at a central portion of a roller main body; and a holder for positioning and holding the heater in the roller main body attached to the pressure lever.