JP3164687B2 - Fixing device - Google Patents

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 and a printer, and more particularly to a fixing device capable of adjusting a pressure contact force of a pressure roller with respect to a fixing roller.

[0002]

2. Description of the Related Art As a fixing device in an image forming apparatus,
There is known a so-called roller-type fixing device 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, thereby fixing the toner image. Such a device has the advantages of a simpler configuration, a relatively low heating temperature, and easy control, as compared to an oven type or other fixing device.
There are problems such as generation of wrinkles of the transfer material and transfer omission.

For this reason, the fixing roller and the pressure roller have special cross-sectional shapes such as a crown and an inverted crown, and are strictly designed so that these rollers are pressed against each other with an optimum pressure value at which wrinkles hardly occur. ing.

[0004]

However, even if such precautions are taken, during mass production, the roller may be damaged due to dimensional errors or assembly errors in manufacturing the rollers or errors in the spring pressure for pressing the rollers. In some cases, the pressing force varies between machines, which may cause wrinkles.

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

[0006]

In order to solve the above-mentioned problems, a fixing device according to the present invention supports a pressure roller and is pivotally movable so that the roller can be moved in a direction of moving toward and away from the fixing roller. A support member provided, having a pivot point in the middle, having an outer end protruding outside the fixing device, and an inner end engaging with the support member in the fixing device and acting to push up the fixing member, detachable from the fixing device. Push-up rod and push-up
An adjusting rod pivotally attached to the rod at a position different from the pivot point and pushing the outer end outside the fixing device and positioned above the outer end of the rod;
An adjusting screw that is screwed to the outer end of the adjusting rod and that determines the distance between the adjusting rod and the raising rod by abutting the leading end of the adjusting rod; one end is outside the fixing device and the other end is the outer end of the adjusting rod; An adjusting spring that is attached and acts in a direction to push down the outer end of the push-up rod.

[0007]

In such a means, when adjusting the pressing force of the roller, the adjusting screw exposed outside the fixing device is operated to change the distance between the ends of the adjusting spring (the operating point distance) to thereby adjust the pressing force. Adjust the strength.

[0008]

Next, a preferred embodiment of the present invention will 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. Although not shown, a release agent application device such as a silicone oil is provided along the peripheral surface thereof, Related devices such as a device and a peeling device are arranged. A pressure roller 2 is disposed below and in contact with the fixing roller 1, and when a transfer material carrying an unfixed toner image is carried in between these rollers in a direction indicated by an arrow A and passes between the rollers. Is fixed to the toner image. The transfer material after fixing is discharged out of the apparatus according to arrow B.

The pressure roller 2 is composed of a roller made of an elastic material such as silicon rubber, and both ends thereof 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 4, whereby the pressure roller 2 can be moved in the direction of coming and going with respect to the fixing roller 1.

A push-up rod 10 is provided to adjustably press the pressure roller 2 against the fixing roller 1. The following configuration is provided for each of the left and right ends of the pressure roller 2, but for convenience of description, only one side will be described. FIG.
As shown in FIGS. 2 and 3, the push-up rod 10 is pivotally supported at its axial center by a pivot 11 so that 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 perpendicular to the generatrix of the fixing roller. In the illustrated example, the pivot 11 is the side plate 5 of the fixing device.
The L-shaped cut groove 10c formed on the push-up rod 10 fits into the shaft 11 (FIG. 1), so that the push-up rod 10 attaches the shaft 11 to the shaft 11. It is pivotable to 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 10 b 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 is important to position the outer end 10a of the push-up rod 10 outside the fixing device in order to simplify the operation of adjusting the pressing force as described later.

An adjusting rod 13 is provided in parallel with the push-up rod 10 so as to urge the push-up rod 10 and adjust the urging force. The adjusting rod 13 has an inner end 13b pivotally connected to the push-up rod 10 by a pivot 14, and an outer end 13a extends out of the fixing device.
0a. An adjusting screw 15 is screwed to the outer end 13 a of the adjusting rod 13 from above to below, and the tip of the screw is pushed up to contact the upper surface of the rod 10. Sign 1
Reference numeral 6 denotes a set screw for preventing the screw from loosening.

The adjusting screw 15 has an outer end 13a of the adjusting rod 13 and an outer end 10a of the pushing rod 10 depending on the degree of screwing.
To determine the interval. An outer end 13a of the adjusting rod 13 has an adjusting spring (tensile spring) 2 having one end attached to the fixing device main body.
0 is operatively attached to the other end of the adjusting spring 20.
Moves the adjusting rod 13 downward, and thus via the adjusting screw 15,
It acts in the direction of pushing down the rear end 10a of the push-up rod 10. Accordingly, 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, and presses the pressure roller 2 against the fixing roller 1.

In the above configuration, when it is necessary to adjust the pressure contact force between the two rollers, the distance between the ends of the adjustment spring 20 (the distance of the action point) is changed by turning the adjustment screw 15 to change the degree of screwing. And adjust the pressing force to the optimal value.

[0014]

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

[Brief description of the 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 pressing force adjusting mechanism of the apparatus shown in FIG. 1;

FIG. 3 is a plan view of a part of the apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Support plate 10 Push-up rod 13 Adjusting rod 15 Adjusting screw 20 Adjusting spring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 61-112360 (JP, U) Japanese Utility Model Sho 60-68564 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] 1. A supporting member which supports a pressure roller and is rotatably provided so as to be able to move in a direction of moving toward and away from the fixing roller, and has a pivot point at a middle portion to fix an outer end. A push-up rod detachable from the fixing device and protruding out of the device and having an inner end engaged with the support member in the fixing device to act to push up the support member; and a pivot at a position different from the pivot point on the push-up rod. And the outer end thereof is located above the outer end of the push-up rod outside the fixing device.
An adjustment rod located in said screwed to the outer end of the adjusting rod, an adjusting screw which determines the distance between the push rod and the adjusting rod by abutting the tip in the push rod, one end of the fixing device outside A fixing spring attached at the other end to the outer end of the adjusting rod and acting in a direction to push down the outer end of the push-up rod.