JPH0419685A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the unevenness of fixing and a wrinkle on a recording material from occurring by causing a carrying member for carrying the recording material to a heating part to be combined with a pressure member for causing the recording material to press-contact to a heating part. CONSTITUTION:A driving roller 13 rotates in the direction of an arrow B, so that a fixing film 12 is moved by the frictional force of the film 12 and the roller 13 in the direction of the arrow B. A pressure roller 15 is caused to follow in the direction of an arrow C with such movement, and a carrying belt 16 laid between the roller 15 and a carrying roller 17 moves in the direction of an arrow D. Then, a transfer paper is carried to a nip part by the belt 16 and a toner image on the transfer paper is heated and melted with the heat and the pressure by a heating body 11 and the roller 15 so as to be fixed on the transfer paper. Thus, the unevenness of fixing and the wrinkle on the recording material are prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device used in an image forming apparatus such as a copying machine or a printer.

[Conventional technology]

Conventionally, heat rollers have been commonly used as devices for fixing toner images on recording materials, but they consume a lot of power and require a long wait time, which is the time it takes to reach a temperature that can be fixed. There was a drawback.

Therefore, a fixing method using a heat-resistant film has been proposed to improve the above-mentioned drawbacks.

The fixing method has a configuration as shown in FIG. 3, for example.

In FIG. 3, 1 is a low heat capacity heating element, 2 is a heat-resistant fixing film, 3 is a drive roller that drives the fixing film 2, 4 is a tension roller that applies tension to the fixing film 2, and 5 is the fixing film. 2 is a pressure roller that presses the recording material against a low heat capacity heating element; 6 is an inlet guide that guides the unfixed recording material to the nip; and 7 is an ejector for discharging the fixed recording material. A paper guide, 8 a conveyance belt that guides the unfixed recording material to the fixing section, 9 a conveyance drive roller that drives the conveyance belt 8, and 10 its driven roller.

In the fixing system configured as shown in FIG. 3, since the heating element 1 has a low heat capacity, it instantly generates heat when energized, resulting in low power consumption and zero wait time. It has the advantage of being equal.

(Problem to be Solved by the Invention) However, in the fixing method shown in FIG. 3, the conveyance section including the conveyor belt 8 and the pressure roller 5 are separate, which increases the number of parts and costs. Furthermore, the circumferential speed of the pressure roller 5 and the conveyance drive roller 9 do not match, making it impossible to convey the recording material smoothly, resulting in uneven fixing and wrinkles on the recording material. There is a problem with this.

The present invention aims to solve the above problems. That is, according to the present invention, the number of parts is reduced, thereby reducing costs, and it is possible to easily match the circumferential speed of the pressure roller, the circumferential speed of the conveyance drive roller, and the moving speed of the fixing film. It is an object of the present invention to provide a fixing device that can prevent uneven fixing and wrinkles on a recording material.

[Means for Solving the Problems] In order to achieve the above object, the present invention heats and melts an unfixed toner image formed on a recording material through a heat-resistant film, and transfers the toner onto the recording material. In the fixing device for fixing an image, the conveyance member that conveys the recording material to the heating section also serves as a pressure member that presses the recording material against the heating section.

[For production]

According to the present invention, the conveyance member that conveys the recording material to the nip portion of the fixing device also serves as the pressure member that presses the recording material to the nip portion, so the number of parts is reduced and costs are reduced. can be achieved. In addition, the drive for the heat-resistant film and the transport member that guides the recording material to the fixing device can be driven by the same drive, reducing costs, reducing torque, and easily increasing the moving speed of the heat-resistant film and the transport member. This makes it possible to easily prevent uneven fixing and wrinkles on the recording material.

Example) FIG. 1 shows a first embodiment of the invention.

In FIG. 1, reference numeral 11 denotes a low heat capacity linear heating element, for example, an alumina substrate with a thickness of 1 mm, a width of 7 mm, and a length of 240 mm coated with a resistive material to a width of 1 mm.
Electricity is applied from both ends in the longitudinal direction.

For example, the current is 100V DC with a cycle of 20mm5ec.
The pulse width or frequency is controlled by a temperature measuring element (not shown) to maintain a constant temperature.

Reference numeral 12 denotes a fixing film, which is made of a heat-resistant resin such as polyimide, polyetherimide, or PES and has a thickness of 20 μm, and one side of the film is coated with a release layer such as PTFE. The total thickness of the fixing film 12 is generally 100 μm or less, more preferably 50 μm or less.

The fixing film 12 is endless and is stretched between a drive roller 13 and a tension roller 14, and together with the heating element 11, forms a film transport path. Further, the fixing film 12 is applied tension in the direction of arrow A to the tension roller 14 by the urging means, and is rotated in the direction of arrow B by the drive roller 13.

The drive roller 13 has a core metal made of iron or the like, and a coating layer of Si rubber or the like is provided on the surface of the core metal. , 15 are pressure rollers that apply pressure to the fixing film 12 and the heating element 11. Further, the pressure roller 15 is supported by a bearing (not shown) so as to be rotatable as a result of the fixing film 12 .

A conveyor belt 16 conveys the unfixed transfer paper to the nip portion of the fixing device, and has a rubber elastic layer made of Si rubber or the like having good release properties. Reference numeral 17 represents a transport roller for transporting the transport belt 16, and 18 represents a paper ejection guide that helps eject the transfer paper from the nip portion of the fixing device.

Next, the driving method of this fixing device will be described.

First, the drive roller 13 rotates in the direction of arrow B in response to rotation of a main motor of an image forming apparatus such as a copying machine (not shown). The rotation moves the fixing film 12 in the direction of arrow B due to the frictional force between the fixing film 12 and the drive roller 13. Due to this movement, the pressure roller 15
is driven in the direction of arrow C, and the tension roller 14 is driven in the direction of arrow E. As a result, the pressure roller 15 and the conveyor belt 16 placed on the conveyor roller 17 move in the direction of the arrow.

The transfer paper is conveyed to the nip portion by the conveyor belt 16, and the toner image on the transfer paper is transferred to the heating element 11 and the pressure roller 15.
The transfer paper is heated and melted by heat and pressure, and is fixed onto the transfer paper, and then the transfer paper is ejected from the apparatus by a paper ejection roller (not shown).

FIG. 2 shows a second embodiment of the invention.

This second embodiment differs from the first embodiment described above in that a conveyance drive roller 19 is provided to drive the conveyance belt 16.
The point is that the paper ejection guide 18 is omitted. That is, the conveyor belt 16 extends to the paper discharge section, and the conveyor belt 16
The transfer paper is designed to perform three functions: transport leading to the fixing nip, transport leading from the fixing nip to the outside of the fixing device, and acting as a pressure member that presses the transfer paper against the heating element 1.

(Effects of the Invention) As described above, according to the present invention, the conveyance member that conveys the recording material to the heating section also serves as the pressure member that presses the recording material against the heating section, so that the number of parts is reduced. Cost reduction due to reduction in torque, reduction in torque due to simplification of drive means,
It is possible to prevent uneven fixing and wrinkles on the recording material.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view similarly showing the second embodiment, and FIG. 53 is a sectional view showing an example of a conventional technique. 11... Heating element 12... Fixing film 13
... Drive roller 14 ... Tension roller 15
... Pressure roller 16 ... Conveyor belt 17 ...
Conveyance roller 18...Paper discharge guide 9...Conveyance drive roller 4 people Figure Figure

Claims (1)

[Scope of Claims] 1. In a fixing device that heats and melts an unfixed toner image formed on a recording material through a heat-resistant film and fixes the toner image on the recording material, the recording material is placed in a heating section. A fixing device characterized in that a conveyance member that conveys the recording material also serves as a pressure member that presses the recording material against the heating section.