JPS641787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoreceptor replacement method in an electrophotographic apparatus such as a copying machine or a printer.

Usually, the photoreceptor in electrophotographic equipment is
Se, CdS, ZnO, OPC (organic photoconductor), etc. are used, but these photoreceptors gradually deteriorate due to charging, erasing, light irradiation, toner adhesion, etc., and cannot match the conditions of electrophotographic equipment. It disappears. Therefore, in general, in electrophotographic devices such as copying machines, the photoreceptor is replaced by visually determining the quality of the copied image obtained, or the photoreceptor is replaced after counting the number of copies and when the number of copies reaches a certain number. We are trying to do the exchange. However, the manner in which the photoconductor deteriorates greatly varies depending on the usage conditions of the copying machine, such as the number of copies per original and the type of document, so it is not practical to judge the degree of deterioration of the photoconductor based on the number of copies. There are problems in terms of copy quality or economy because a photoreceptor that has deteriorated to a certain extent must be used as is, or a photoreceptor that can still be used must be replaced.
Furthermore, although it is certainly reasonable to visually judge the copy quality and replace the photoconductor, the criteria for this judgment are ambiguous, and there is a possibility that the photoconductor may be replaced sooner than necessary. There's a problem.

An object of the present invention is to provide a photoreceptor replacement method that can eliminate these drawbacks.

The present invention will be described below by way of examples with reference to the drawings.

Looking at the changes that occur when a photoreceptor deteriorates in an electrophotographic device, for example, in OPC, the charging potential gradually decreases, the photosensitivity decreases, and the residual potential increases. Therefore, it is time to replace the OPC when at least one of these characteristics falls outside the permissible limits. For example, in the case of an OPC where the change in charged potential is relatively small, a decrease in sensitivity determines when to replace it.
Next, an embodiment of the present invention that performs such OPC exchange will be described.

For example, in a copying machine as shown in FIG. 1, the photosensitive drum 1 is constructed of a winding type in which a part of the OPC sheet 2 is wound around the drum and the used part is replaced by winding up the OPC sheet 2. ing.

The unused portion of the OPC sheet 2 is wound around the roller 21 in the drum 20, the used portion is wound around the roller 22 inside the drum 20, and when the used portion is replaced, the unused portion is rolled up from the roller 17 onto the drum 20. As the portion is pulled out, the used portion is wound onto the roller 22 from the drum 20.

The photoreceptor drum 1 is driven to rotate in the direction of the arrow and is uniformly charged by the charging section 3, and then the original image is exposed at the exposure section to form an electrostatic latent image. The latent image is erased (hereinafter referred to as erase). Next, the electrostatic latent image on the photoreceptor drum 1 is developed in a developing section 5 and transferred to a transfer paper 6 from a paper feeder in a transfer section 7, and this transfer paper 6 is fixed in a fixing section and becomes a copy. It is discharged. Further, the photosensitive drum 1 is neutralized by a light source 18, cleaned by a cleaning section 19, and reused. Here, as the sensitivity of the used portion of the OPC sheet 2 gradually decreases, the background potential during exposure and the potential of the erased portion after erasing increase. If these values exceed certain limits, background stains may occur in the copied image, or erasing may not be performed sufficiently and the erased portion may be developed, resulting in undesirable results. In order to solve these problems, in this embodiment, a surface potential meter using a detector 8 measures the surface potential of the exposed portion of a certain document on the photosensitive drum 1 before the developing section 5, or The surface potential of the portion, that is, the surface potential that changes depending on the degree of deterioration on the OPC sheet 2 is measured. However, for certain documents, a document with a certain density, such as one in which the edge of the contact glass of the document table is painted white, is used. As shown in FIG. 2, the surface electrometer consists of a detector 8 and a surface potential detection circuit 9, and a light amount detection element 14 is provided near a part of the exposure section or the light source 4 for erasing. The amount of light irradiated onto the photoreceptor drum 1 from the photoreceptor drum 1 is measured by a light amount measuring section comprising a light amount detection element 14 and a light amount detection circuit 15, and a signal that changes depending on the amount of light is obtained. The output signal of the surface electrometer is sent to an adder 16
By adding the output signals of the light amount measuring section, a change due to deterioration of the exposure section or the erase light source 4 is corrected. That is, the amount of light irradiated onto the photoreceptor drum 1 from the exposure section or the erase light source 4 and the surface potential of the photoreceptor drum 1 to which this amount of light is irradiated are due to changes in the light amount due to deterioration of the exposure section or the erase light source 4. They change inversely to each other, and if the amount of light decreases due to deterioration of the exposure section or the erase light source 4, the surface potential of the photoreceptor drum 1 will increase. Therefore, the output signal of the surface electrometer and the output signal of the light amount measurement section change inversely to each other due to a change in the light amount due to deterioration of the exposure section or the erase light source, and the output signal of the surface electrometer changes in the adder 16. By adding the output signals of the light amount measuring section, changes due to deterioration of the exposure section or erase light source 4 are removed, and the surface potential that changes depending on the degree of deterioration due to the use of the OPC sheet 2 is accurately measured. It corresponds to The output signal of the adder 16 is compared with the reference voltage from the reference voltage source 11 by the comparator 10, and it is determined whether the degree of deterioration of the OPC has reached the allowable limit. Timer circuit 12 is OPC
When the degree of deterioration of the used portion of the sheet 2 reaches the permissible limit, it is triggered by the output signal of the comparator 10 and the OPC winding motor 13 is operated for a certain period of time to rotate the roller 18.
The OPC sheet 2 is rolled up and its used part is replaced.

As described above, according to the present invention, a photoreceptor that is used repeatedly, a charging means for charging the photoreceptor,
In an electrophotographic apparatus that has a light source that irradiates the photoreceptor with light to erase unnecessary electrostatic latent images or an exposure section that exposes the photoreceptor, the surface potential that changes depending on the degree of deterioration of the photoreceptor used is In addition to measuring with an electrometer, a light amount measuring section measures the amount of light from the light source or the exposure section to obtain an output signal that changes according to the change in the light amount, and the output signal of this light amount measuring section is converted to the surface electrometer. It is added to the output signal to correct the change due to the change in the amount of light, and by comparing this corrected signal with a reference value, it is determined whether the degree of deterioration of the photoreceptor used has reached the allowable limit. , when the signal after the above correction reaches the reference value and it is determined that the degree of deterioration of the used photoreceptor has reached the allowable limit, a photoreceptor replacement signal is generated, and the used photoreceptor is replaced by this photoreceptor replacement signal. It becomes possible to accurately replace the photoreceptor according to the degree of deterioration of the photoreceptor, and it becomes possible to solve the problems of quality and economic efficiency of electrophotography. Moreover, by adding the output signal of the light amount measuring section to the output signal of the surface electrometer and correcting the change due to the change in the light amount, deterioration of the photoreceptor can be accurately detected.
The photoreceptor can be replaced at a more accurate time, which is more effective in terms of quality and economy of electrophotography.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a copying apparatus, and FIG. 2 is a block diagram showing an example of an implementation circuit of the present invention. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 8... Detector, 9... Surface potential detection circuit, 10... Comparator, 11... Reference voltage source, 14... Light amount detection element, 15... Light amount detection circuit, 16... ...Adder.

Claims (1)

[Claims] 1. A photoreceptor that is used repeatedly, a charging means that charges the photoreceptor, and a light source that irradiates the photoreceptor with light to erase unnecessary electrostatic latent images or an exposure unit that exposes the photoreceptor to light. In an electrophotographic apparatus having a photoreceptor, a surface potential that changes depending on the degree of deterioration of the photoreceptor used is measured by a surface potentiometer, and a light amount measurement section measures the amount of light from the light source or exposure section, and changes in accordance with changes in the amount of light. By obtaining an output signal from the light intensity measurement section, adding the output signal from the light intensity measurement section to the output signal from the surface electrometer to correct the change due to the change in light intensity, and comparing the corrected signal with the reference value. Then, it is determined whether the degree of deterioration of the photoconductor used has reached the permissible limit, and when it is determined that the signal after the correction has reached the reference value and the degree of deterioration of the photoconductor used has reached the permissible limit, the photoconductor A photoconductor replacement method characterized in that a photoconductor replacement signal is generated, and a used photoconductor is replaced based on the photoconductor replacement signal.