JPH0820780B2 - Temperature control device for photoconductor drum - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a temperature control device for a photosensitive drum, which uses an amorphous silicon photoconductor as a photosensitive layer.

(Prior Art) A photoconductor drum of an electrophotographic copying machine is used by coating a photoconductive layer of photoconductivity on a cylindrical conductive substrate of aluminum or the like. Heretofore, a selenium-based photoreceptor has been generally used as the photosensitive layer. Since the selenium-based photoconductor has a smaller specific heat than air, the temperature of the photoconductive layer itself becomes lower than that of the atmosphere near the photoconductor drum due to the cooling of the outside air. When the temperature of the photosensitive layer becomes lower than the temperature of the atmosphere, water vapor in the vicinity of the surface of the photoreceptor is condensed and adheres to the surface, so-called condensation phenomenon occurs. This dew condensation phenomenon does not occur during the copying operation, but occurs when the temperature inside the copying machine decreases because the copying machine is not used for a long time, such as at night. For this reason, a dew condensation prevention heater is attached to the photosensitive drum, and when the copier is not used for a long time, the heater prevents the selenium-based photosensitive layer from crystallizing (usually about 30 to 35 ° C). ) Holds the photoconductor drum to prevent condensation.

Recently, amorphous silicon-based photoconductors have been used instead of selenium-based photoconductors for the photosensitive layer of the photoconductor drums of electrophotographic copying machines. The amorphous silicon photoconductor has a high surface hardness and a high sensitivity to light on the long wavelength side, and is therefore suitable for high-speed use.

However, when the amorphous silicon photoconductor is repeatedly used, the surface of the photoconductor becomes sensitive to humidity and it becomes easy to adsorb moisture. For this reason, the surface resistance decreases, the surface charge moves laterally, and a so-called image deletion phenomenon occurs in which a sharp electrostatic latent image cannot be formed. Unlike the above-described selenium-based photoconductor, this image deletion phenomenon occurs when the surface temperature drops to about 45 ° C., so that it also occurs during continuous copying. In order to prevent such an image deletion phenomenon, it is necessary to constantly maintain the surface of the photosensitive layer at a predetermined temperature with a heater provided in the photosensitive drum.

The heater arranged in the photosensitive drum has a heat transfer plate made of stainless steel or the like and a heater wire arranged on the heat transfer plate. The heat transfer plate is arranged so that the heater wire is on the inner peripheral side. Is closely attached to the inner peripheral surface of the photosensitive drum. The heater uniformly transfers the heat of the heater wire to the photoconductor drum by a heat transfer plate, and brings the entire photosensitive layer to a predetermined temperature by the temperature of the heater.

The heater is usually controlled by the control device so as to have a predetermined temperature. The control device has a thermometer such as a thermistor and controls the heater based on the detection result of the thermometer. In the conventional selenium-based photosensitive layer, the control device is
The temperature of the heat transfer plate, which is a uniform temperature, was detected by the thermometer using the heater wire, and the heater was controlled based on the detection result. In this way, when controlling the heater by catching the temperature change of the heat transfer plate, even if the temperature of the heater wire itself changes, the change in temperature will appear on the heat transfer plate.
There will be some time delay. Therefore, it takes time for the temperature measuring device to detect the temperature change of the heater and control the heater to bring the heater to a predetermined temperature, and there is a drawback that the control response is poor. When an amorphous silicon-based photoconductor is used as the photosensitive layer, the photosensitive layer is sensitive to humidity as described above, and if the control response is poor, the temperature of the photosensitive layer decreases and Moisture adheres to the surface, causing the phenomenon of image deletion.

Further, since the heat transfer plate of the heater is designed to rotate together with the photosensitive drum, if a temperature measuring device is attached to the heat transfer plate, the temperature measuring device is affected by the air flow due to the rotation of the heat transfer plate. There are also problems. Therefore, even if the heater is controlled based on the detection result of such a temperature measuring device, the photosensitive layer may not reach a predetermined temperature.

Since the heater is arranged on the inner peripheral surface of the photosensitive drum,
Part of the heat of the heater is radiated into the drum. Therefore, the heating efficiency of the photosensitive drum by the heater is poor,
There is also a problem that it takes a long time until the photosensitive drum is heated to a predetermined temperature.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a photosensitive drum having an amorphous silicon photoconductor as a photosensitive layer with high response. Accordingly, it is to provide a temperature control device capable of controlling a predetermined temperature. Another object of the present invention is to avoid the influence of rotation of the photosensitive drum,
It is an object of the present invention to provide a temperature control device for a photosensitive drum that can control the photosensitive layer to a predetermined temperature. Still another object of the present invention is to provide a heater for a photosensitive drum which has excellent heating efficiency and can raise the temperature of the photosensitive layer to a predetermined temperature in a short time.

(Means for Solving the Problems) The present invention is a temperature control device for a photosensitive drum in which an amorphous silicon photoconductor is laminated as a photosensitive layer on the outer peripheral surface of a cylindrical conductive substrate. A heat transfer plate that is disposed in close contact with the inner peripheral surface of the body drum and rotates with the photosensitive drum, and a heater having a heater wire disposed on the inner peripheral surface of the heat transfer plate, and the heater wire is in contact with the heater wire. And a means for changing the amount of heat generated by the heater wire based on the detection result of the temperature detector, thereby providing the above-mentioned object. To be achieved.

The present invention is also a temperature control device for a photosensitive drum, in which an amorphous silicon photoconductor is laminated as a photosensitive layer on the outer peripheral surface of a cylindrical conductive substrate. And a heater having a heater wire disposed on the inner peripheral surface of the heat transfer plate, and a heater having a heater wire disposed on the inner peripheral surface of the heat transfer plate. The temperature measuring device for directly detecting the temperature of the peripheral surface and the means for changing the heat generation amount of the heater wire based on the detection result of the temperature measuring device are provided, thereby achieving the above object.

(Example) Hereinafter, the present invention will be described with reference to Examples.

The photoconductor drum heater of the present invention is used, for example, in the electrophotographic copying machine shown in FIG. The electrophotographic copying machine includes a photoconductor drum 10 arranged in the central portion, a charging device 20, an exposure device 30, a developing device 40, a transfer / separation device 50 arranged around the photoconductor drum 10. It has a cleaning device 60 and a static eliminator 61.

The photosensitive drum 10 is formed by laminating an amorphous silicon photoconductor as a photosensitive layer 12 on the outer peripheral surface of a conductive substrate 11. The photosensitive drum 10 is rotatable in the direction indicated by arrow B, and a charging device 20 is arranged above it. The charging device 20 uniformly charges the photosensitive layer 12. An exposure device 30 is arranged above the charging device 20. A document table 70 on which a document is placed is arranged on the upper surface of the machine body. The exposure device 30 moves in the direction indicated by the arrow A to expose the document placed on the document table 70, guide the reflected light onto the photosensitive layer 12 of the photoconductor drum 10, and the photosensitive layer 12 is exposed. Form an electrostatic latent image on top.

A developing device 40, a transfer / separation device 50, a cleaning device 60, and a charge eliminating device 61 are sequentially provided on the downstream side in the rotation direction of the photosensitive drum 10 from the position where the original image of the photosensitive layer 12 is exposed.
It is arranged. The developing device 40 develops the electrostatic latent image formed on the photosensitive layer 12 with toner, and transfers the toner image.
It is transferred onto the recording paper by the separating device 50. The cleaning device 60 removes the residual toner on the photosensitive layer 12 and removes the static electricity
Eliminates the residual charge on the photosensitive layer 12.

A heater 80 is arranged on the inner peripheral surface of the conductive substrate 11 of the photosensitive drum 10. As shown in FIG. 4, the heater 80 includes a parallelogram-shaped heat transfer plate 81 made of stainless steel, for example.
And one heater wire 82 bonded to the heat transfer plate 81 so as to meander. On the heat transfer plate 81, the heater wire is
A thermistor 83 is provided as a temperature measuring device that comes into contact with a part of the heater wire 82 and detects the temperature of the heater wire 82 itself.
The thermistor 83 and a part of the heater wire 82 in contact with the thermistor 83 are covered with a synthetic resin 84 such as silicone. The output of the thermistor 83 is given to a voltage control circuit 85 for controlling the voltage applied to the heater wire 82, as shown in FIG. 5, for example. The voltage control circuit 85 is
Based on the temperature of the heater wire 83 detected by the thermistor 83, the voltage applied to the heater wire 83 is controlled, and when the temperature of the heater wire 83 becomes a predetermined value or less, the voltage is increased to increase the temperature of the heater wire 82. On the contrary, when the temperature exceeds a predetermined value, the voltage is lowered and the temperature of the heater wire 82 is lowered.

As shown in FIGS. 2 and 3, a hollow heat insulating material 90 having a hexagonal cross section, for example, is disposed inside the photosensitive drum 10. The heat insulating material 90 is concentrically suspended in the photosensitive drum 10 by two supporting rods 91 and 91 which are erected on the drum flanges 14, 14 fitted to both end surfaces of the photosensitive drum. The heat insulating material 90 divides the inside of the photosensitive drum 10 concentrically. The volume of this void is preferably as small as possible so that the heater 80 can raise the temperature of the photosensitive drum 10 in a short time.
When the ambient temperature of the photoconductor drum 10 is low, it is preferable not to set the temperature too small in order to obtain the heat retaining effect of the photoconductor drum 10. The aforementioned voltage control circuit 85 and the like are arranged in the internal space of the heat insulating material 90.

Since the temperature control device for the photoconductor drum having such a structure uses the amorphous silicon photoconductor as the photoconductor layer 12, it is controlled so that the temperature of the heater wire 82 is not always lower than 46 ° C., for example. It When the thermistor 83 detects that the temperature of the heater wire 82 has dropped to 46 ° C. or less, the voltage control circuit 85 increases the voltage applied to the heater wire 82.
When the thermistor 83 detects that the temperature of the heater wire 82 has risen to about 50 to 60 ° C. or higher, the voltage control circuit 85 reduces the voltage applied to the heater wire 82. The photosensitive layer 12
If the temperature is 46 ° C. or lower, water may adhere to the photosensitive layer 12 to cause an image deletion phenomenon, and if the temperature is 50 to 60 ° C. or higher, the toner adhered to the photosensitive layer 12 may melt. Photosensitive layer
12 is set to a predetermined temperature according to the temperature of the heater wire 82.

In order to keep the temperature of the photosensitive layer 12 constant, the photosensitive drum 10
It is also possible to directly detect the temperature of the inner peripheral surface and control the heater 80 based on the temperature. FIG. 6 is a sectional view showing a state in which a thermistor 83 as a temperature measuring device is brought into close contact with the inner peripheral surface of the photosensitive drum 10 (that is, the inner peripheral surface of the conductive substrate 11). The thermistor 83 is an elastic member 86 such as sponge rubber.
Is pressed against the inner peripheral surface of the conductive substrate 11. A polyimide film is interposed between the elastic member 86 and the inner peripheral surface of the photosensitive drum 10, and the thermistor 83 is in contact with the inner peripheral surface of the photosensitive drum via the film. The elastic member 86
Are attached to the bracket 87. The bracket 87
Is supported by one drum flange 14 fitted to the end portion of the photosensitive drum 10.

The output of the thermistor 83 is also given to the voltage control circuit 85 as shown in FIG. 5, and the voltage applied to the heater wire 82 is changed based on the detection result of the thermistor 83.

(Effect of the Invention) As described above, the temperature control device of the present invention directly detects the temperature of the heater wire, controls the temperature of the heater wire based on the detection result, and controls the temperature of the photosensitive layer to a predetermined value. Since it is a value, it has excellent responsiveness to changes in the temperature of the heater wire and can be controlled with high accuracy. Therefore, there is no possibility that the temperature of the photosensitive layer will drop and moisture will adhere to the surface of the photosensitive layer. If the temperature measuring device is covered with synthetic resin or the like, it is not affected by the air flow due to the rotation of the photosensitive drum.

Further, in the temperature control device of the present invention, the temperature measuring device is closely attached to the inner peripheral surface of the photosensitive drum to directly detect the temperature of the inner peripheral surface of the photosensitive drum. The temperature of the photosensitive layer can be accurately detected without being affected by. Since the temperature measuring device is covered with the elastic member, it is possible to perform highly accurate control without being affected by the air flow due to the rotation of the photosensitive drum. By concentrically dividing the inside of the photoconductor drum with a heat insulating material, the volume of gas in the photoconductor drum heated by the heater is reduced, and the heating efficiency of the photoconductor drum of the heater is increased.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electrophotographic copying machine, FIG. 2 is a partially cutaway perspective view of a photosensitive drum, FIG. 3 is a transverse sectional view thereof, FIG. 4 is a developed perspective view of a heater, and FIG. Is a control circuit diagram of the heater, and FIG. 6 is a vertical cross-sectional view of the photosensitive drum showing a mounting state of the temperature measuring device. 10 ... Photosensitive drum, 12 ... Photosensitive layer, 80 ... Heater, 81
...... Heat transfer plate, 82 …… Heater wire, 83 …… Thermistor, 84
…… Synthetic resin, 85 …… Voltage control circuit, 90 …… Insulation material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area G03G 21/20

Claims (7)

[Claims] 1. A temperature control device for a photosensitive drum, wherein an amorphous silicon photoconductor is laminated as a photosensitive layer on an outer peripheral surface of a cylindrical conductive substrate, the temperature control device being in close contact with the inner peripheral surface of the photosensitive drum. A heater having a heat transfer plate that is disposed and rotates together with the photosensitive drum, and a heater wire that is disposed on the inner peripheral surface of the heat transfer plate, and a temperature that is provided in contact with the heater wire. A temperature control device for a photoconductor drum, comprising: a temperature detector for directly detecting the temperature, and means for changing the amount of heat generated by the heater wire based on the detection result of the temperature detector. 2. A temperature control device for a photosensitive drum according to claim 1, wherein a heat insulating material for concentrically dividing the inside of the photosensitive drum is provided in the photosensitive drum. 3. The temperature control device for a photosensitive drum according to claim 1, wherein the temperature measuring device is a thermistor that contacts a heater wire. 4. The temperature control device for a photosensitive drum according to claim 3, wherein a part of the thermistor and a heater wire that is in contact with the thermistor is covered with a synthetic resin. 5. A temperature control device for a photosensitive drum, wherein an amorphous silicon photoconductor is laminated as a photosensitive layer on an outer peripheral surface of a cylindrical conductive substrate, the temperature control device being in close contact with the inner peripheral surface of the photosensitive drum. Arranged heat transfer plate,
And a heater having a heater wire disposed on the inner peripheral surface of the heat transfer plate, and a measuring unit which is disposed in close contact with the inner peripheral surface of the photosensitive drum and directly detects the temperature of the inner peripheral surface of the photosensitive drum. A temperature control device for a photoconductor drum, comprising: a warmer; and means for changing a heat generation amount of the heater wire based on a detection result of the temperature detector. 6. A temperature control device for a photosensitive drum according to claim 5, wherein a heat insulating material for concentrically dividing the inside of the photosensitive drum is provided in the photosensitive drum. 7. The temperature control device for a photosensitive drum according to claim 5, wherein the temperature measuring device is a thermistor that contacts a heater wire.