JPH06242698A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device capable of adjusting the press-contact force of a pressure roller to a fixing roller. CONSTITUTION:A supporting member 3 is provided so as to move in a direction nearer to or away from the pressure roller 1. A pushing up lever 10 acting for pushing up the supporting member 3 and an adjusting lever 13 pivotally attached to the pushing up lever 10 and located on the upper side of the pushing up lever 10 with the outside end of the lever 13 located outside the fixing device are provided on the lower side of the supporting member 3 and an adjusting screw 15 which abuts on the pushing up lever 10 and sets a gap between the adjusting lever and the pushing up lever 10 and an adjusting spring 20 whose one end is attached to a fixing device main body and other end is attached to the outside end 10 of the pushing up lever and acting in a direction where the rear end of the pushing up lever is pushed down are provided on the outside end of the adjusting lever 13.

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 an image forming apparatus such as a copying machine or a printer, and more particularly to a fixing device capable of adjusting the pressure contact force of a pressure roller against a fixing roller.

[0002]

2. Description of the Related Art As a fixing device in an image forming apparatus,
A so-called roller-type fixing device is known in which a transfer material carrying an unfixed toner image is passed between a fixing roller and a pressure roller pressed against the fixing roller to fix the toner image. Such a device has an advantage that the structure is simple and the heating temperature is relatively low and it is easy to control as compared with a fixing device having another structure such as an oven type.
There are problems such as wrinkling of the transfer material and transfer omission.

For this reason, the fixing roller and the pressure roller have a special cross-sectional shape such as a crown or an inverted crown, and they are strictly designed so that they are pressed against each other at an optimum pressure value in which wrinkles are less likely to occur. ing.

[0004]

However, even if such attention is paid, during mass production, the rollers may be manufactured due to dimensional errors in assembly, assembly errors, or errors in spring pressure for pressing the rollers. The pressure contact force between them varies from machine to machine, which may cause wrinkles.

The present invention has been made in such a situation, and an object thereof is to provide a fixing device capable of adjusting the pressure contact force of the pressure roller with respect to the fixing roller with a simple and convenient structure.

[0006]

In order to solve the above problems, the fixing device according to the present invention is capable of pivoting so as to support the pressure roller and to move the roller in a direction of moving toward and away from the fixing roller. A support member provided, a push-up rod having a pivot point in the middle, an outer end outside the fixing device, and an inner end engaged with the support member in the fixing device and acting to push it up; and a push-up rod. An adjusting rod pivotally attached and having an outer end located above the lifting rod outside the fixing device, and an interval between the adjusting rod and the pushing rod by screwing the outer end of the adjusting rod into contact with the pushing rod. It is characterized by having an adjusting screw to be determined and an adjusting spring having one end attached to the main body of the fixing device and the other end attached to the outer end of the push-up rod and acting to push down the rear end of the push-up rod.

[0007]

In such a means, when the pressure contact force of the roller is adjusted, the pressure contact force is changed by operating the adjusting screw exposed outside the fixing device to change the distance between the end portions of the adjusting spring (the action point distance). Adjust the strength.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described with reference to the drawings. FIG. 1 shows a main part of a roller type fixing device. Reference numeral 1 denotes a fixing roller having a heater therein, which is heated and controlled to a predetermined fixing temperature. As is well known, the surface of the fixing roller is coated with a release agent for toner such as Teflon, and although not shown, a device for applying a release agent such as silicone oil and a temperature detector are provided along the peripheral surface. Related devices such as a device and a peeling device are arranged. A pressure roller 2 is disposed below the fixing roller 1 in contact therewith, and a transfer material carrying an unfixed toner image is carried in between these rollers in a direction indicated by an arrow A and is passed between the rollers. The toner image is fixed on. The transfer material after fixing is discharged out of the apparatus according to the arrow B.

The pressure roller 2 is a roller made of an elastic material such as silicon rubber, and its both ends are rotatably supported by a pair of left and right support plates 3 (only one is shown). Each support plate 3 is provided so as to be pivotable with respect to a side plate 5 of the fixing device by means of a pivot shaft 4, whereby the pressure roller 2 is movable in a direction in which it comes in contact with and separates from the fixing roller 1.

A push-up rod 10 is provided to adjustably press the pressure roller 2 to the fixing roller 1. The following configurations are provided for both left and right ends of the pressure roller 2, but one side will be described for convenience of description. Figure 1
As shown in FIGS. 2 and 2, the push-up rod 10 is rotatably supported by a pivot 11 at its axial center, and its outer end 10a is located outside the fixing device and its inner end 10b is located inside the fixing device. And extends in a direction orthogonal to the generatrix of the fixing roller. In the illustrated example, the pivot 11 is the side plate 5 of the fixing device.
Is protruded substantially in parallel with the generatrix of the fixing roller, and the L-shaped cut groove 10c formed in the push-up rod 10 is fitted to the shaft 11 (FIG. 1) so that the push-up rod 10 can move the shaft 11 up. It is supposed to be able to pivot in the center. With this configuration, the push-up rod 10 can be easily assembled to the shaft 11 and can be removed. A rod 12 parallel to the pivot 11 is fixed to the inner end 10b of the push-up rod 10, and one end of the rod 12 abuts on the lower end of the support plate 3 of the pressure roller 2 and acts to push up the support plate 3.
It should be noted that positioning the outer end 10a of the push-up rod 10 outside the fixing device is important for simplifying the work of adjusting the pressure contact force, as will be described later.

An adjusting rod 13 is provided in parallel with the push-up rod 10 so as to bias the push-up rod 10 and adjust the biasing force thereof. An inner end 13b of the adjusting rod 13 is pivotally attached to the push-up rod 10 by a pivot shaft 14, and an outer end 13a thereof extends outside the fixing device, and the outer end 1 of the push-up rod 10 is extended.
It is located above 0a. An adjusting screw 15 is screwed onto the outer end 13a of the adjusting rod 13 from the upper side to the lower side, and the tip of the screw is pushed up and brought into contact with the upper surface of the rod 10. Code 1
6 is a set screw for preventing loosening of the screw.

The adjusting screw 15 has an outer end 13a of the adjusting rod 13 and an outer end 10a of the pushing-up rod 10 depending on the degree of screwing.
Determine the interval between. An adjusting spring (tension spring) 2 having one end attached to the main body of the fixing device is attached to the outer end 13a of the adjusting rod 13.
The other end of 0 is operatively attached and the adjustment spring 20
Through the adjusting rod 13 and thus through the adjusting screw 15,
It acts in the direction of pushing down the rear end 10a of the push-up rod 10. As a result, the inner end 10b of the push-up rod 10 pushes up the support plate 3 of the pressure roller 2 based on the principle of leverage to bring the pressure roller 2 into pressure contact with the fixing roller 1.

In the above structure, when it is necessary to adjust the pressure contact force between both rollers, the adjusting screw 15 is rotated to change the degree of screwing, so that the distance between the ends of the adjusting spring 20 (the distance between the action points). Adjust the pressure contact force to the optimum value.

[0014]

As described above, according to the present invention, the pressure contact force of the pressure roller can be appropriately adjusted by operating the adjusting screw after the apparatus is assembled, and the adjusting screw can be operated outside the fixing device. The adjustment work can be easily performed because the configuration is performed in. Further, since the pressure contact force is adjusted by changing the distance of the action point of the spring, the adjustment spring can be used while ignoring some variation in manufacturing.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a main part of a fixing device according to the present invention.

FIG. 2 is a top view showing a pressure contact force adjustment mechanism of the apparatus shown in FIG.

3 is a plan view of a portion of the apparatus of FIG.

[Explanation of symbols]

 1 Fixing Roller 2 Pressure Roller 3 Support Plate 10 Push-up Rod 13 Adjusting Rod 15 Adjusting Screw 20 Adjusting Spring

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideaki Takigawa 4-21-3 Shimomaruko, Ota-ku, Tokyo Katsurakawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A support member pivotally provided so as to support a pressure roller and to move the roller in a direction of moving toward and away from the fixing roller, and an outer end having a pivot point at a center portion thereof. A push-up rod that engages with the support member and pushes it up outside the device and inside the fixing device,
An adjusting rod pivotally attached to the push-up rod and having an outer end located above the push-up rod outside the fixing device, and an adjusting rod and a push-up rod that are screwed onto the outer end of the adjusting rod and have their tips abutting against the push-up rod. Fixing device for determining the distance between the fixing device and the fixing device, one end of which is attached to the fixing device main body and the other end of which is attached to the outer end of the push-up lever, and an adjusting spring which acts to push down the rear end of the push-up rod. .