JPH04343381A - Fixing device - Google Patents

Abstract

PURPOSE:To maintain stable traveling by making at least one end diameter of a traveling endless type fixing film smaller than the diameter of an area where the film is made to contact with a recording member and providing a film position controlling member. CONSTITUTION:A stay 3 is provided with a long sideways base part 10, a front wall panel 11 whose section is curved outward in the shape of an arc and a similar rear wall panel 12 which are made to serially and respectively stand up from both longitudinal sides of the base part 10, and the film position controlling member 13 for controlling so that the fixing film 1 can be prevented from approaching moreover the side of the fixing film whose size is made smaller and a pair of right and left horizontal projecting lug parts projecting outward from both end parts on right and left sides of the base part 10. That means, the diameter of the one end of the fixing film 1 is made smaller, and then the film position controlling means 13 for holding the film so as to actively move in a direction where the diameter of the one end of the film 1 is not made lower. And also, the calorific value of the heat generating part 6 of a heating body 5 on the opposite side of the controlling member 13 is increased so as to move the film 1 to the end side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film heating type fixing device used in image forming apparatuses such as electrophotographic printers and copying machines.

0002

2. Description of the Related Art Conventionally, as a heat fixing device, there is a roller fixing device which is composed of a fixing roller controlled to a predetermined temperature and a pressure roller having an elastic layer on its surface and in pressure contact with the fixing roller. Common.

However, in the roller fixing device,
The fixing roller uses a metal roller several millimeters thick with a halogen heater installed inside as a heat source, so it takes several millimeters to reach the predetermined temperature in terms of heat transfer from the heat generating element and heat capacity of the fixing roller. Disadvantages include requiring a 10 second warm-up time and consuming power even when the device is not in operation due to being maintained in a standby state.

Therefore, in recent years, a film heating type fixing device has been proposed to improve the above-mentioned disadvantages of the roller fixing device and to save energy and provide a quick start.

This film heating type fixing device includes a fixed heating element, a heat-resistant fixing film that is conveyed while being in pressure contact with the heating element, and a heating element that brings the unfixed recording material into close contact with the heating element through the film. and a pressure member, and heat from the heating body is applied to the recording material via the film to fix the recording material.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned film heating type fixing device, from the viewpoint of heat conductivity and low heat capacity of the fixing film, a thin film of about 100 μm or less and a material with a high elastic modulus such as polyimide are used. For,
Under the influence of the temperature distribution of the fixing film, fluctuations in the coefficient of friction, or mechanical vibrations, the fixing film is displaced in the direction of the drive shaft, and there is a risk that the fixing film may wrinkle or tear.

[0007] Therefore, there is a problem in that an optical or mechanical detection means must be provided at the end of the fixing film to constantly detect and correct the displacement of the fixing film to ensure drive stability. Ta.

The present invention is an attempt to solve the above-mentioned problems. That is, an object of the present invention is to provide a fixing device that has a simple configuration, can prevent the fixing film from wrinkling and damage, and can stabilize the running of the fixing film.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention fixes and supports a heating element on the inner surface of a running endless fixing film, and disposes it on the outer surface facing the heating element. and a pressure member that guides and brings the recording material into close contact with the heating body through the fixing film, wherein the diameter of at least one end of the fixing film is smaller than the diameter of the area that contacts the recording material. A film position regulating member is provided which is slidably fixed to the inner surface of the film.

0010

[Operation] According to the present invention, the diameter of at least one end of the running endless fixing film is smaller than the diameter of the area that contacts the recording material, and the film is fixed so as to slide on the inner surface of the fixing film. Since the position regulating member is provided, while the fixing film is running, the inner surface of the portion where the diameter is reduced slides into contact with the film position regulating member, and the film tends to move toward the side where the diameter is not reduced. Therefore, stable running is maintained at a predetermined position with balanced bias.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a central sectional view showing a first embodiment of the present invention, and FIG. 2 is a perspective view of the fixing film shown in FIG.

In FIG. 1, 1 is an endless fixing film, 2 is a pressure roller as a pressure member, 3 is a stay to be described later, 5 is a heating element, and 6 is a heat generating part of the heating element 5.

That is, as shown in FIG. 2, the fixing film 1 is made of a heat-resistant material with a smaller diameter at the right end.
As shown in FIG. 1, it is fitted onto the stay 3.

The stay 3 has a horizontally long flat bottom part 10 and a front wall plate 11 having an outwardly curved cross section and extending in series from both longitudinal sides of the bottom part 10. A rear wall plate 12, a film position regulating member 13 that regulates the fixing film 1 so that it does not come closer to the side where the diameter of the fixing film 1 is made smaller, and a bottom surface part 1.
It has a pair of left and right horizontally protruding lug portions that project outward from both left and right ends of the 0, respectively.

The pressure roller 2 forms a nip portion by sandwiching the fixing film 1 between the heat generating portions 6 of the heating body 5, and operates as a pressure roller or a backup roller as a rotating body that drives the fixing film 1. , the central axis and
It consists of a roller part made of a rubber elastic body with good mold releasability, such as silicone rubber, wrapped around the shaft, and the left and right ends of the central shaft are rotatably supported by bearing members on the left and right sides, respectively.

During operation, when the pressure roller 2 is driven to rotate at a predetermined circumferential speed by a drive device (not shown),
At the nip portion, a feeding force is applied to the fixing film 1 due to frictional force with the rotating pressure roller 2, and the fixing film 1
The inner surface of the film 1 is driven to rotate at approximately the same speed as the circumferential rotational speed of the pressure roller 2 while sliding on the surface of the heat generating portion 6 of the heating body 5.

The fixing film 1 has a thickness of 100 μm or less, preferably 20 to 40 μm, in order to reduce heat capacity and improve quick start properties, and has good heat resistance, mold releasability, strength, and durability. In this example, a 20 μm thick polyimide film coated with 10 μm of PTFE on the image contact side is used. In this way, when using a thin film, the film does not run stably for a long period of time during rotational drive, and
It is necessary to control the deviation by some means.

In this embodiment, in order to avoid complication of the conventional device, the diameter of one end of the fixing film 1 is made small, and a film position regulating member 1 is attached to the stay 3 in order to hold it.
3 is provided so that the diameter of one end of the film 1 is actively moved in the direction in which it is not reduced.

Further, in this embodiment, the amount of heat generated on the opposite side of the regulating member 13 of the heat generating portion 6 of the heating body 5 is increased, and the film fixing is performed such that the film 1 approaches the side where the temperature of the fixing film 1 is higher. Taking advantage of this characteristic, a method was taken to actively move the film 1 toward the end in one direction.

By doing this, the position of the fixing film 1 is determined by the regulating member 13, and the film 1 is not wrinkled, and the film 1 is stable even when about 100,000 sheets are passed through. It is possible to construct an inexpensive and highly reliable device that can run, and has a simplified, smaller, and lower cost device configuration.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

In this second embodiment, the same fixing device as in the first embodiment is used, and the pressure roller 4 is tapered in its outer diameter in the longitudinal direction of the pressure roller 4, as shown in FIG. I used something similar.

Furthermore, in this second embodiment, the regulating member 1
The side where the pressure roller 4 has a smaller diameter is installed on the side where the pressure roller 4 is located.

By taking the above means, in the film heat fixing device, the fixing film 1 has the characteristic of being pulled toward the larger side of the fixing nip, so that the film 1 is pulled to the opposite side of the film position regulating member 13 ( (direction of arrow A), and the effects of the present invention can be utilized more effectively. The pressure roller 4 is designed in consideration of the durability of the fixing film 1, image fixability, printing accuracy, etc., and for example, the difference in outer diameter at both ends of the pressure roller 4 with a roller rubber length of 230 mm is 0.005 to 0.1%. and preferably 0.02 to 0.05%.

[0025]

As explained above, the present invention provides a film heating type fixing device in which the diameter of at least one end of the running endless fixing film is smaller than the diameter of the area that contacts the recording material. Since a film position regulating member is provided that is fixed so as to slide on the inner surface of the fixing film, while the fixing film is running, the film is
The inner surface of the part where the diameter has been reduced slides into contact with the film position regulating member, and the film tends to move toward the side where the diameter is not reduced, and stable running is maintained at a predetermined position with a balanced shift. . Therefore, equipment simplification, miniaturization,
Cost reduction can be achieved, and an inexpensive and highly reliable fixing device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the fixing film of FIG. 1;

FIG. 3 is a perspective view showing a second embodiment of the present invention.

[Explanation of symbols]

1: Fixing film 2: Pressure roller 3: Stay 4: Pressure roller 5: Heating body 13: Film position regulating member

Claims (2)

[Claims] 1. A heating body is fixedly supported on the inner surface of a running endless fixing film, and a recording material is placed on the outside facing the heating body through the fixing film. and a pressure member that guides and brings the fixing film into close contact with the recording material, the diameter of at least one end of the fixing film being smaller than the diameter of the area that contacts the recording material,
A fixing device comprising a film position regulating member slidably fixed to the inside of the fixing device. 2. The fixing device according to claim 1, further comprising a member on the opposite side of the film position regulating member to which a force for displacing the fixing film acts.