JPH0675501A - Fixing device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To prevent the permanent set due to fatigue of the silicone rubber of a roller and to prolong the life of a fixing device by rotating an eccentric roller in contact with the shaft of a fixing lower roller interlocked with opening/ closing a main body and turning on/off a power source. CONSTITUTION:The eccentric roller 16 and a spring 15 are provided to be opposed on and under the shaft, 13 of the fixing lower roller 12 for fixing toner on printing paper with heat and pressure. The lower roller 12 is caused to rise and fall by the rotation of the roller 16, but it is fixed at a position where it is raised most in a direction A in the midst of performing printing operation and in the midst of standing by, and its part in contact with a heat roller 11 is deformed to form a nip part 20. When paper jamming occurs at a fixing part, a sensor detects that a main body device is opened and drives the roller 16 to rotate by 180 deg. in order to remove the jammed paper. Thus, the lower roller 12 is pushed downward, and pressure between the roller 11 and the roller 12 is released, then the jammed paper is easily removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic printer, and more particularly, to a heat roller having a heater lamp at its center, and a print sheet being sandwiched between the heat roller and a predetermined pressure applied thereto. The present invention relates to a fixing device for an electrophotographic printer including a lower fixing roller.

[0002]

2. Description of the Related Art FIG. 2 is a front view showing an example of a fixing device of a conventional electrophotographic printer.

A conventional fixing device for an electrophotographic printer is provided with a heat roller having a heater lamp in the center thereof and a lower fixing roller for sandwiching a printing paper between the heat roller and a predetermined pressure, and As shown in FIG. 2, a heat roller 1 having a heater lamp 4 in the center, and a heat roller 1 which is provided so as to face the heat roller 1 and which sandwiches a print sheet with the heat roller 1 to apply a predetermined pressure. A lower fixing roller 2 for fixing the toner on the printing paper with heat and pressure is provided. The lower fixing roller 2 presses the heat roller 1 or releases the pressure from the lower fixing roller 2 with respect to the shaft 3. The spring 5 provided is either compressed by the lever 6 (arrow A) or released from compression (arrow B). The movement of the lever 6 (arrow C or D) is generally linked to the opening / closing operation of the electrophotographic printer (main unit).

As the heat roller 1, an aluminum tube whose surface is coated is used, and both ends thereof are held by bearings. Therefore, its position is not moved. The lower fixing roller 2 is a shaft 3
It is formed by baking silicon rubber on the outer periphery of the columnar body and is pressed against the heat roller 1 by the spring 5 to move its position. That is, when the main body device is closed, the lever 6 is pushed down in the direction of the arrow D, so that the spring 5 is compressed. As a result, the shaft 3 is pushed up in the direction of arrow A, and the lower fixing roller 2 deforms the contact portion with the heat roller 1 to form the nip portion 10. The fixing of the toner on the printing paper is performed when the printing paper passes through the nip portion 10.

When a paper jam occurs at this fixing portion,
The main body device is opened to remove the jammed paper, but at this time, the lever 6 is lifted in the direction of arrow C because the restraining force is released. As a result, the compressed state of the spring 5 is released, the lower fixing roller 2 moves in the direction of arrow B, and the pressure between the heat roller 1 and the lower fixing roller 2 is released, so that the jammed paper can be easily removed. It is possible to remove it.

[0006]

In the conventional fixing device of the electrophotographic printer as described above, since the lower fixing roller is constantly pressed against the heat roller when the main body device is closed, The silicon-based rubber that constitutes the lower fixing roller is worn out, which is a factor that shortens the life of the fixing device.

[0007]

A fixing device for an electrophotographic printer according to the present invention comprises a heat roller having a heater lamp in its central portion, and a fixing member provided facing the heat roller and having an outer peripheral portion made of rubber. In a fixing device for an electrophotographic printer including a lower roller, a spring for pushing up the lower fixing roller, and an eccentric roller provided to face the spring and contacting a shaft of the lower fixing roller are provided. Is rotated 180 degrees in conjunction with opening / closing of the main body device and turning on / off of power.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a front view showing an embodiment of the present invention.

The fixing device shown in FIG. 1 includes a heat roller 11 having a heater lamp 14 at the center, and the heat roller 1
1, a lower fixing roller 12 for fixing the toner on the print sheet by heat and pressure by sandwiching the print sheet between the heat roller 11 and the heat roller 11 and applying a predetermined pressure thereto. . An eccentric roller 16 and a spring 15 are provided above and below the shaft 13 of the lower fixing roller 12 so as to face each other.

The eccentric roller 16 raises and lowers the shaft 13, that is, the lower fixing roller 12 by the rotational movement (arrow B). The rotational movement is different from the drive system for driving the rotational movement of the lower fixing roller 12 and the heat roller 11. It is driven by a separate drive system.

As in the conventional example of FIG. 2, the heat roller 11 is formed by coating the surface of an aluminum tube, and both ends are held by bearings. Therefore, its position is not moved. The lower fixing roller 12 also has a shaft 13 similar to the conventional example shown in FIG.
It is formed by baking silicone rubber on the outer circumference of the column to form a columnar shape, and is pressed against the heat roller 11 by the spring 15 to move its position.

The eccentric roller 16 is in the state shown in FIG. 1, that is, the lower fixing roller 12 is in the most lifted state in the direction of arrow A during the printing operation and the standby state, and is fixed at that position. . Therefore, the portion of the lower fixing roller 12 that contacts the heat roller 11 is deformed to form the nip portion 20. The fixing of the toner on the printing paper is performed when the printing paper passes through the nip portion 10.

When a paper jam occurs at this fixing portion,
The main unit is opened to remove the jammed paper, and at this time, a sensor (not shown) provided in the main unit senses it. When the sensor senses that the main body device is opened, the drive system of the eccentric roller 16 is driven to move the eccentric roller 16 to 1
Rotate 80 degrees. As a result, the lower fixing roller 12 is pushed downward, and the heat roller 11 and the lower fixing roller 12 are pressed.
Since the pressure between and is released, the jammed paper can be easily removed.

When the jammed paper is easily removed and the main body unit is closed again, the eccentric roller 16 rotates 180 degrees again, and FIG.
Return to the state of.

When the main unit is powered off after the printing operation is completed, the eccentric roller 16 is driven by the condenser provided in the main unit, rotates 180 degrees immediately after the power is turned off, and is fixed to the heat roller 11. The pressure between the lower roller 12 is released. When the power of the main body apparatus is turned on, the eccentric roller 16 rotates 180 degrees to be in the state of FIG. 1 and ready for printing.

[0017]

As described above, the fixing device of the electrophotographic printer of the present invention is provided with an eccentric roller at a position in contact with the shaft of the lower fixing roller and facing the spring for pushing the lower fixing roller. By rotating the roller 180 degrees in conjunction with opening / closing of the main body device and turning on / off of the power supply, the pressure on the heat roller of the lower fixing roller can be released except during the printing operation and the printing standby. Therefore, there is an effect that it is possible to prevent the silicone rubber that constitutes the lower fixing roller from settling and extend the life of the fixing device.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a front view showing an example of a fixing device of a conventional electrophotographic printer.

[Explanation of symbols]

 1 ・ 11 Heat roller 2 ・ 12 Lower fixing roller 3 ・ 13 Shaft 4 ・ 14 Heater lamp 5 ・ 15 Spring 6 Lever 10 ・ 20 Nip part 16 Eccentric roller

Claims (1)

[Claims] 1. A fixing device of an electrophotographic printer, comprising: a heat roller having a heater lamp in a central portion thereof; and a lower fixing roller having an outer peripheral portion formed of rubber and facing the heat roller. A spring for pushing up the lower roller and an eccentric roller provided to face the spring and in contact with the shaft of the fixing lower roller are provided. The eccentric roller is interlocked with opening / closing of the main body device and turning on / off of a power source. A fixing device for an electrophotographic printer characterized by being rotated once.