JPH0962138A - Fixing temperature controlling method for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing temperature controlling method of a fixing device where a cleaning member need not be set at a heating roller, and an error in temperature detection is prevented because toner does not stick on a temperature detecting element and the set temperature of the heating roller is not changed. SOLUTION: The thermistor 6 of the fixing device 1 of an image forming device which has the heating roller 2 having a heating element 3 and a thermistor 6 detecting the temperature of the heating roller 2 is provided to be able to come into contact with and to be separated from the heating roller 2, and also it is provided with a controlling means. The temperature control of the heating roller 2 is performed by the controlling means by making the thermistor 6 abut on the heating roller 2 and on/off controlling the energizing of the heating element 3 based on the output of the thermistor 6 during the standby of a copying operation, and the temperature of the heating roller 2 is maintained to be at specified temperature by separating the thermistor 6 from the heating roller 2 and on/off controlling the energizing of the heating element 3 in accordance with a program previously set while the roller 2 is rotated and paper is passed at the time of the copying operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing temperature control method for a fixing device using an electrophotographic method.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus of this type is disclosed in Japanese Utility Model Laid-Open No. 56-18960. This image forming apparatus 1'includes a heat roller 2 as shown in FIG.
The pressure roller 4 that is pressed against the heat roller 2, the temperature detection element 6 ′ that contacts the surface of the heat roller 2 to detect the temperature of the heat roller 2, and the temperature detection element 6 ′ in the rotation direction of the heat roller 2 A cleaning member 20 arranged on the upstream side and longer than the temperature detecting element 6'in the axial direction of the heat roller is provided, and the temperature detecting element 6'and the cleaning member 20 are always in contact with the heat roller 2. .

At the time of its operation, the cleaning member 20 removes stains such as offset toner and paper dust adhered to the surface of the heat roller 2 so that the stains adhere to the surface of the temperature detecting element 6 '. To prevent this, the temperature detecting element 6'detects the temperature of the heat roller 2 and makes the temperature of the heat roller 2 a predetermined value.

[0004]

In the conventional fixing device as described above, since the cleaning member is always in contact with the heat roller, the fixing device stands up and reaches the set temperature and is ready for copying. After that, when the fixing operation is started and the heat roller starts to rotate, the toner adhering to the cleaning member peels off and goes around to the temperature detecting element side and adheres, causing an error in the temperature detection of the heat roller and setting the heat roller. There are problems that the temperature changes and good fixing is not performed, and that the cleaning member must be replaced every time a few thousand copies are made.

Therefore, an object of the present invention is to solve the problems of the fixing device as described above, to eliminate the need to install a cleaning member on the heat roller, to prevent the toner from adhering to the temperature detecting element, and to make an error in temperature detection. Another object of the present invention is to provide a fixing temperature control method for a fixing device that does not occur and the set temperature of the heat roller does not change.

[0005]

In order to achieve the above-mentioned object, the present invention provides a heat roller having a heating element, and a thermistor for detecting the temperature of the heat roller. In the fixing device of the image forming apparatus having the above, the thermistor is provided so as to be able to come in contact with and separate from the heat roller, and a control means is provided, and the control means makes the thermistor abut against the heat roller during the standby of the copying operation. Based on the output, the power supply to the heating element is turned on and off to control the temperature of the heat roller, and during the copy operation, the thermistor is separated from the heat roller while the heat roller rotates and the paper is passing, and it is set in advance. According to a program, the heating element is turned on / off to maintain the temperature of the heat roller at a predetermined temperature. That.

[0007]

1 and 2 showing a fixing device for carrying out a fixing temperature control method for a fixing device according to the present invention.
Is a heat roller having a heating element 3 composed of a halogen lamp therein, 4 is a pressure roller that abuts against the heat roller 2,
Denoted at 5 is a separating claw, and denoted at 6 is a thermistor for detecting the temperature of the heat roller 2, which is attached to one end of a swing arm 8 swinging around a support shaft 7. Further, a solenoid 9 and a tension spring 10 are connected to the other end of the swing arm 8 so as to face each other with the other end of the swing arm 8 interposed therebetween. It is possible to approach and separate from 2. Further, it comprises a control means 11 having a CPU 11a to which the output of the thermistor 6 is inputted, and this CPU 11a is programmed in advance so that a predetermined ON / OFF time of the heating element 3 and a solenoid 9 is turned ON at the time of sheet passing. Is set.

As shown in FIG. 3, the output of the thermistor 6 and the output of the copy start button 12 are input to the control means 11, and the solenoid 9 is turned on and off via the driver 13 by the output of the control means 11. Then, the heating element 3 is turned on and off, and the heat roller 2 is rotated or stopped via the driving means 14 for performing the copying operation of the fixing device 1.

In such a configuration, the control means 11 brings the thermistor 6 into contact with the heat roller 2 and outputs the thermistor 6 according to the output of the thermistor 6 while the image forming apparatus is turned on and warming up and waiting for the copy operation. When the copy start button 12 is pressed, the control means 11 sends a signal to the drive means 14 to start the rotation of the heat roller 2 by turning on and off the heating element 3 and maintaining the heat roller 2 at a predetermined temperature. The sheet is started to pass through, and the solenoid 9 is turned on via the driver 13 to separate the thermistor 6 from the heat roller 2. From this time, the control means 11 ignores the signal from the thermistor 6 and controls the preset ON / OFF of the heating element 3 for a predetermined time. The on time of the heating element 3 is set to 5 seconds and the off time is set to 3 seconds.
During the copy operation, the ON / OFF operation is repeated during the passage of the paper to maintain the temperature of the heat roller 2 at a predetermined temperature. When the copy number detecting means (not shown) detects that the paper has passed, the control means 11 stops the rotation of the heat roller 2 and turns off the solenoid 9 via the driver 13 to set the thermistor 6 to the heat roller 2. The heating element 3 of the control means 11 is turned on and off by detecting the temperature of the heat roller 2 of the thermistor 6 by stopping the on / off control of the heating element 3 by the program of the control means 11 as described above. And the heat roller 2 is maintained at a predetermined temperature.

[0010]

The present invention is as described above, and the invention according to claim 1 is a fixing device for an image forming apparatus having a heat roller having a heating element and a thermistor for detecting the temperature of the heat roller. , The thermistor is provided so as to be able to come in contact with and separate from the heat roller, and a control means is provided, and the control means brings the thermistor into contact with the heat roller and energizes the heating element based on the output of the thermistor while the copying operation is waiting. The temperature of the heat roller is controlled by turning it on and off, and during the copy operation, while the heat roller is rotating and the paper is passing, the thermistor is separated from the heat roller, and the heating element of the heating element is moved according to a preset program. Since the temperature of the heat roller is maintained at a predetermined temperature by turning the power on and off, the offset toner, paper dust, etc. adhering to the thermistor There is no need to install the cleaning member to be removed on the heat roller, the maintenance fee can be reduced, and the set temperature of the heat roller can be changed without causing an error in temperature detection because the offset toner or paper dust does not adhere to the thermistor. The effect is not to.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a state in which a thermistor according to an embodiment of the present invention is in contact with a heat roller.

FIG. 2 is a schematic vertical sectional view showing a state in which the thermistor of the above is separated from a heat roller.

FIG. 3 is a block diagram showing a circuit configuration of the above.

FIG. 4 is a perspective view of a main part of a heat roller and a temperature detection element of a conventional fixing device.

[Explanation of symbols]

 1 Fixing Device 2 Heat Roller 3 Heating Element 6 Thermistor 7 Spindle 8 Swing Arm 9 Solenoid 10 Tension Spring 11 Control Means

Claims (1)

[Claims] 1. A fixing device for an image forming apparatus, comprising: a heat roller having a heating element; and a thermistor for detecting the temperature of the heat roller. During the copying operation, the control means controls the temperature of the heat roller by turning on / off the power supply to the heating element based on the output of the thermistor by bringing the thermistor into contact with the heat roller while waiting for the copying operation. While the roller is rotating and paper is passing, the thermistor should be separated from the heat roller, and the heating element should be turned on and off according to a preset program to maintain the temperature of the heat roller at a predetermined temperature. And a fixing temperature control method.