JPS6328301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to measures against moisture absorption in an electrophotographic photoreceptor whose latent image potential decreases due to moisture absorption.

Measures against moisture absorption applied to conventional electrophotographic devices include: (a) A heater means is provided inside the support shaft of the drum-shaped photoreceptor, and this heater means is installed to keep the surface temperature of the photoreceptor always higher than the ambient temperature. There is a way to keep the power on all the time. In this method, the heater means is always energized even at night and on days when the device is not driven, resulting in wasted power consumption. Furthermore, once the power is turned off and the photoreceptor absorbs moisture, there is a problem that the dehumidifying effect is not easily achieved even when the power is turned on again. Yet another method is
(b) There is one in which temperature is controlled by attaching a sheet-like heater means to the back surface of the drum-like photoreceptor. Although this method has better thermal efficiency than method (a) above, there is a problem in that it takes about an hour to become effective unless electricity is constantly applied.

The purpose of the present invention is to solve the problems of the above-mentioned prior art.More specifically, it is an object of the present invention to dry the dehumidifying means in a short period of time after the start of electricity supply to the dehumidifying means. The goal is to minimize power consumption.

To achieve the above object, the present invention provides an electrophotographic apparatus that forms an image using a photoreceptor whose latent image potential decreases when it absorbs moisture, which includes a potential sensor means for measuring the potential of the photoreceptor, and a photoreceptor. a heating means disposed near the body surface and heating the photoreceptor;
control means for controlling the operation of the heating means based on a detection signal from the potential sensor means;
When the potential sensor means detects that the photoreceptor has absorbed moisture and is no longer able to maintain a constant potential level, the control means operates the heating means until the constant potential level is restored. This method is characterized by heating and drying the photoreceptor.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Figure 1 is an explanatory diagram showing the outline of an electrophotographic device.
The photosensitive drum 1 rotates in the direction of the arrow, and forms an image by repeating the conventionally known general processes of forming a latent image, developing, transferring, and cleaning. In the above apparatus, the latent image on the photosensitive drum 1 is measured by the potential sensor 2 after the latent image is formed. Further, the infrared heater 3 is provided near the photosensitive drum 1. For example, when the main body of the apparatus is turned on in the morning of a day with high humidity, the photosensitive drum 1 rotates and the potential sensor 2 applies a certain amount of charge to measure the potential of the model latent image formed. If this latent image is higher than the predetermined latent image potential, the copying operation will start as is, and if it is lower, the infrared heater will be turned on immediately and the photoreceptor will be moved until the potential of the model latent image rises to a certain value. Rotate drum 1. In this way, the present invention has good thermal efficiency because it heats from the surface of the photoreceptor drum, and because the potential sensor measures the potential of the model latent image every time the drum rotates, it can be heated immediately after the latent image potential recovers. Since power is turned off to the infrared heater, power consumption and time required for the device to start operating can be saved. Furthermore, by applying an infrared heater, the time for which electricity is applied to the photoreceptor can be shortened, so that the burden on the photoreceptor caused by heating can also be reduced.

Example 1 In FIG. 2, the photosensitive drum 4 consists of a conductive layer base, a CdS photoconductive layer, and a surface insulating layer.
A latent image is formed on the drum 4 by primary charging with (+) polarity by the charger 5, secondary charging with negative (-) polarity by the charger 6, simultaneous image exposure, and overall exposure by the lamp 7. In the copy cycle, the latent image is developed by a developer 8 and transferred to a transfer material 10 by a transfer corona discharger 9. Further, residual toner on the photosensitive drum 4 is cleaned by a cleaner 11. In the above device, the potential sensor 1
2 is located near the photoreceptor drum 4 between the full-surface exposure lamp 7 and the developing device 8, and measures a model latent image formed by lighting an image exposure lamp (not shown).
It is connected to a circuit that controls the input to the corona dischargers 5 and 6 so as to bring this latent image potential close to a target value (for example, 500V). Then, when the main body of the apparatus is powered on, the drum 4 starts rotating, a predetermined reference current is passed through the primary and secondary chargers 5 and 6, and a model latent image is created. The contrast of this model latent image is at a predetermined detection level (e.g. 400V)
If it is higher, it will be in a copyable state as is.
If it is low, the infrared heater 13 is turned on, a model latent image is created again with the amount of primary and secondary corona discharge unchanged (reference current), and the process of measuring this is repeated, and the potential of the model latent image is When the amount exceeds a predetermined detection level, the device becomes ready for copying. In addition, the above drum 4 was heated to 25℃100
After leaving it in %RH overnight, I carried out each of the above steps, and the first time the detected potential was 120V, but
400V after 5 minutes with the infrared lamp turned on
At that point, the potential of the primary and secondary charges was controlled by the control means to reach approximately 500V. In the above embodiment, the infrared heater 13 is
When 300W was used, the surface temperature of the drum 14 5 minutes after lighting was 5° C. higher than room temperature. Further, the lighting time of the infrared lamp is controlled by the control means 14.

The above device allows the photoreceptor to recover in a short time even if it absorbs moisture. However, if the photoreceptor changes due to its durability and a reference current is applied to the discharger for latent image formation, the model latent If the image no longer reaches a predetermined potential level, the infrared heater will remain on, which is disadvantageous. Therefore,
As a countermeasure to this problem, in order to prevent the infrared heater from increasing the temperature of the surrounding area, it is better to turn off the infrared heater after it has been turned on for a certain period of time. As a specific control method, it is preferable to control the lighting time using a timer so that the lighting time is within 15 minutes. Regarding the use of an infrared heater as a heating means for the photoreceptor, especially when the photoreceptor is made of CdS, there is almost no sensitivity in the infrared region with a wavelength of about 800 nm or more. Since there is no change in the image between the area where is lit and the other area, it is easy to control the blinking of the heater and set the image forming conditions. Note that when the photoreceptor reacts to infrared rays, it may be corrected by deteriorating the image forming conditions.

Applicable infrared heaters include nichrome heaters and halogen heaters. Further, as the potential sensor, there are an AC rotation type potential sensor, an AC vibration type potential sensor, and the like.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram for explaining the principle of the present invention, and FIG. 2 is a sectional view of a device showing an embodiment of the present invention. In the figure, 1 and 4 are photoreceptors, 2 and 12
3 and 13 are infrared lamp means, and 14 is a control means.

Claims (1)

[Claims] 1. In an electrophotographic apparatus that forms an image using a photoreceptor whose latent image potential decreases when it absorbs moisture, a potential sensor means for measuring the potential of the photoreceptor; The photoreceptor has a heating means for heating the photoreceptor, and a control means for controlling the operation of the heating means based on a detection signal from the potential sensor means, and can maintain a constant potential level as the photoreceptor absorbs moisture. An electrophotographic apparatus characterized in that, when the potential sensor means detects that the photoreceptor has run out, the heating means is operated by the control means to heat and dry the photoreceptor until the constant potential level is restored.