JPH0145636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device, and more particularly to a temperature control device for an endless moving body equipped with a heating source.

Conventionally, in electrophotographic apparatuses in which a photoreceptor is used repeatedly, the photoreceptor is maintained at a temperature slightly higher than room temperature.

This is because the photoconductive materials generally used in the photoreceptors of electrophotographic devices tend to be difficult to charge during the charging process at low temperatures or high humidity, and in such cases, the photoconductive materials used in the photoreceptor of electrophotographic devices tend to be difficult to charge during the charging process. It may be difficult for the charge to escape from the area that is hit. For this reason, the image quality is degraded by fogging on the background, which should be white, and a decrease in density in the character image area, but this is an effective countermeasure. .

Specific methods for controlling the temperature of the photoreceptor in this way include a fixed heating source method in which a heating source is installed in the support shaft of the photoreceptor drum, and a method in which a heating source is installed on the inner surface of the photoreceptor drum. There is a so-called moving heating source system in which a heating source is attached to the drum so that it can rotate together with the drum. In particular, the latter method was preferable for the purpose of temperature control because it directly transmitted heat to the photoreceptor.

As a temperature control device for such a heating source, there are two types: one that can be called an indirect control system that measures and controls the ambient temperature around the photoreceptor drum, and the other that uses a temperature sensing element fixed inside the rotating photoreceptor drum. What can be called a direct control system has been put into practical use in which the drum temperature is measured and controlled by the drum.

Although the former method is simple, it has the problem that accurate temperature control cannot be expected. Although the latter method can be expected to provide good temperature control, it requires a movable connection part (for example, a connection using a sliding electrode) on the wiring due to the provision of a temperature sensing element in the rotating drum, resulting in a complicated configuration. . Furthermore, if sufficient noise countermeasures were not taken, there was a risk that this operation would occur.

The present invention has been made in view of the above-mentioned points, and provides a temperature control device that enables good temperature control.

The present invention provides a temperature control device for a heated endless moving body, which includes: a heating source for the endless moving body; a temperature sensing element; It is characterized by comprising means for switching and moving the support member so that the element is in a contact position with the surface of the endless moving body or a detached position, and means for controlling the heating source in accordance with the detection signal of the temperature sensing element. .

Hereinafter, details of the present invention will be explained using specific examples with reference to the drawings.

FIG. 1 is a perspective view of essential parts of a specific example temperature control device based on the present invention.

In FIG. 1, numeral 1 is a photosensitive drum, and a drum heating source 3 (H) is disposed inside a rotating support shaft 2. As shown in FIG.
Reference numeral 4 denotes a temperature sensing element, which is fixed on the support arm 5. The support arm 5 is swingably supported by a support shaft 6, and allows the temperature sensing element 4 to come into contact with and separate from the surface of the photoreceptor drum 1.

A spring 7 is engaged with the end of the support arm 5 opposite to the end to which the temperature sensing element 4 is fixed, and urges the support arm clockwise. Also, at the end of this support arm, there is a solenoid 8 (SOL) that swings the support arm counterclockwise.
The actuation rod of is engaged.

In the illustrated example, the photosensitive drum is heated and the temperature is controlled at the beginning of a day's use of the electrophotographic apparatus or during standby after a pause, so the solenoid 8 is in an OFF state during standby. At this time, the support arm 5 is rotated clockwise by the bias of the spring 7 to bring the temperature sensing element 4 into contact with the surface of the photoreceptor drum 1. In this state, the temperature of the drum heating source 3 is controlled.

On the other hand, at the start of the copying operation, the solenoid 8 is turned on and the temperature sensing element 4 is separated from the surface of the photoreceptor drum 1, so that there is no rubbing on the rotating surface of the photoreceptor drum during the copying operation. At this time, the temperature inside the electrophotographic apparatus is rising due to heating by the heating source, and is maintained above room temperature even if the drum heating source is turned off due to heat from each low-drive motor or high-voltage transformer.

Therefore, in the above structure, since the temperature sensing element is not always pressed against the surface of the photoreceptor drum, wear and tear on the surface of the photoreceptor drum is prevented.

FIG. 2 is an electrical circuit diagram of the device according to the embodiment of the invention described above.

Rt is a temperature sensing element such as a thersistor, and corresponds to 4 in FIG. 1 above. This temperature sensing element Rt and resistance R ₁ ,
A bridge circuit is composed of variable resistor RV ₁ , resistors R ₂ and R ₃ , and variable resistor RV ₂ , and each output is sensed.
Connected to amplifier 9. When the temperature detected by the temperature sensing element Rt4 is lower than the set value, the sense amplifier 9 turns on its output and gives an on signal to the relay driver 10.

Relay driver 10 receiving the on signal turns on relay RL ₁ . Since the drum heating source H3 is connected to the AC power source via the switch _K1 controlled by the relay _RL1 , the switch _K1 is turned on when the relay _RL1 is turned on.

On the other hand, when the temperature detected by the temperature sensing element Rt4 becomes higher than the set value, the output of the sense amplifier 9 is turned off. This will also turn off relay driver 10, so turn off relay RL ₁ and turn off the switch.
_K1 is turned off. The drum heating source is then turned off and heating is stopped. After a certain period of time, if the temperature falls below the set temperature, the heating source is turned on as described above. Temperature control is achieved by turning on and off the switch.

Furthermore, a second relay driver 11 is turned on upon receiving a copy operation start signal from an electrophotographic apparatus control circuit (not shown). This on signal turns on relay RL ₂ , and solenoid SOL (Fig. 1 8)
Turn on switch _K2 . As a result, the solenoid SOL8 is energized, and the first support arm shown in the figure is rotated in a direction away from the photoreceptor drum. On the other hand, the switch SW inserted in the drum heating source circuit is
It works in conjunction with the copy button, and turns off when the copy operation turns on. In this way, the standby state is transferred to the copy operation, and the drum heating is stopped.
This causes the temperature sensing element to separate from the drum surface.

Although the above-mentioned specific example has been explained using a drum-shaped photoreceptor, it goes without saying that an endless photoreceptor may also be used. It goes without saying that the apparatus of the present invention can be applied not only to heated photoreceptors but also to other surfaces to be heated.

As described above in detail in the specific examples, the apparatus of the present invention performs temperature control by directly contacting the temperature sensing element with the surface of the endless moving body to be heated, so that extremely accurate and excellent temperature control is possible.

Furthermore, since the device of the present invention allows the temperature sensing element to be freely moved into and out of contact with the surface of the endless moving body, there is no risk of unnecessary wear and tear on the surface.

Moreover, since the device of the present invention can be constructed without requiring electrical connection devices such as sliding electrodes, the device is simple in construction and highly stable.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of a specific example temperature control device based on the present invention. FIG. 2 is an electrical circuit diagram of a device according to an embodiment of the present invention. In the figure, 1: photoreceptor drum (endless moving body), 2:
Rotating shaft, 3; drum heating source, 4; temperature sensing element,
5; Support arm.

Claims (1)

[Claims] 1. In a temperature control device for an endless moving body that is heated, a heating source for the endless moving body, a temperature sensing element, a support member that supports the temperature sensing element so as to be able to come into contact with and separate from the surface of the endless moving body, and a temperature control device for controlling the temperature of the endless moving body so that the temperature sensing element moves endlessly. A temperature control device comprising: means for switching and moving the support member so that it is in a contact position with a body surface or a detached position; and means for controlling a heating source in response to a detection signal from the temperature sensing element.