JPH02115862A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To detect that the life of an electrophotographic photosensitive body is shortened due to damage before picture defect appears by providing a detecting means detecting the surface coarseness of the electrophotographic sensitive body. CONSTITUTION:After a visual picture is transferred onto a transfer sheet 10, a destaticizing means 7 removes residual charges on the electrophotographic sensitive body 1, and then a cleaning means 2 removes an after image on the sensitive body 1. At the end of stopping the rotation of the sensitive body 1, a surface coarseness detector 9 detects the surface coarseness of the sensitive body 1. Thus, the body 1 can be fully used regardless of the variance of the number of copied sheets in endurance limit which is caused by environmental difference and mechanical difference. Alarming is issued before a picture is damaged, whereby reliability on the picture quality can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic apparatus such as an electrophotographic copying machine or an electrophotographic printer.

[Conventional technology]

The electrophotographic method, generally known as the Carlson method, involves a series of steps such as charging, exposure, development, transfer, and cleaning, and by repeating these steps, a large number of copies (
(reproduced image) can be obtained. The surface of an electrophotographic photoreceptor used in such an electrophotographic method is constantly subjected to electrical, chemical, and mechanical stress during the series of processes described above, and when this process is repeated many times, the various stresses mentioned above are In particular, mechanical stress causes scratches on the surface of the electrophotographic photoreceptor. It is known that if the depth of these scratches exceeds a certain limit value, defects will occur in the copies.

Conventionally, the durability life of an electrophotographic photoreceptor due to scratches has been considered to be until the point at which an image defect occurs in a copy, and the electrophotographic photoreceptor has been replaced at this point.

[Problems to be Solved by the Invention] As shown in the above-mentioned conventional example, as the number of durable sheets increases, the scratches on the surface of the electrophotographic photoreceptor become deeper. The durability lifespan of a photographic photoreceptor was determined. However, detecting the lifespan of an electrophotographic photoreceptor in this way had the drawback of significantly impairing quality reliability for users.

As a means to avoid this problem, a method can be considered in which the life of the electrophotographic photoreceptor due to scratches is predicted based on the number of durable sheets, and the electrophotographic photoreceptor is replaced before image defects occur. However, since the depth of scratches per unit number of electrophotographic photoreceptors is not constant due to environmental and mechanical differences, it is necessary to set a smaller number to account for variations in the maximum number of sheets used as the lifespan. has the disadvantage that still available electrophotographic photoreceptors that have reached the end of their lifespan must also be replaced.

[Means for solving problems]

The present invention has been made in view of the above-mentioned drawbacks, and provides a detection means for detecting the surface roughness of an electrophotographic photoreceptor.

By using this detection means, it is possible to detect the lifespan due to scratches on the electrophotographic photoreceptor before image defects occur at the point when a certain limit value of scratches has occurred on the electrophotographic photoreceptor, thereby increasing the user's confidence in quality. (The electrophotographic photoreceptor can be replaced without damage.) Also, since the surface roughness of the electrophotographic photoreceptor used in the machine can be detected as an absolute value under different environments, the electrophotographic photoreceptor can be replaced. You can make the most of your body.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

[Example] l Figure 1 is a schematic diagram of an electrophotographic process. The configuration will be explained with reference to the figure. 1 is an electrophotographic photosensitive member configured to rotate in the direction of the arrow. A cleaning means 2 is disposed near the outer periphery. 3 is a primary charger that uniformly charges the surface of the electrophotographic photoreceptor l before forming a latent image; 4 is an exposure means that forms a latent image on the surface of the electrophotographic photoreceptor l; 5 is a latent charger of the electrophotographic photoreceptor l; A developing device for visualizing the image, 6 a transfer charger for transferring the visible image on the electrophotographic photoreceptor 1 onto a transfer paper 1O, and 7 a static eliminating lamp for exposing the entire surface of the electrophotographic photoreceptor 1 A static eliminating means for removing residual charges, a surface potential detecting means 8 for detecting the surface potential of the electrophotographic photoreceptor, and a detecting means 9 for detecting the surface roughness of the electrophotographic photoreceptor l.

Next, the operation of the electrophotographic process shown in FIG. 1 will be explained. In the figure, the electrophotographic photoreceptor l is the primary charger 3.
After being uniformly charged, the exposure means 4 lowers the potential on the electrophotographic photoreceptor l to form a latent image. Furthermore,
After the latent image becomes a visible image by the developing device 5, it is transferred to the transfer charger 6.
The image is transferred onto the transfer paper IO by the following steps. The transfer paper 10 is then conveyed to a heat fixing device (not shown) and heat-fixed thereon. After the visible image is transferred to the transfer paper 10, the residual charge on the electrophotographic photoreceptor l is removed by the charge eliminating means 7, and then the afterimage on the electrophotographic photoreceptor l is removed by the cleaning means 2.

After the electrophotographic photoreceptor stops rotating, the surface roughness detector 9 detects the surface roughness of the photoreceptor.

A stylus-type surface roughness detector was used as the surface roughness detector 9. In this detector, as shown in FIG. 2, the stylus 9a is made of diamond and has a 90° cone with a diameter of 5 μm. Press this against the object to be measured with a certain pressure
By moving the needle in the y direction, the needle moves up and down in the y direction according to the surface roughness and shape. This amount of displacement in the y direction is converted into an electrical signal and detected as a surface roughness value. Then, the detection value is compared with the limit value of surface roughness that does not produce a scratch image, which is stored in the software built into the main unit, and when the two values are equal, an alarm installed on the main unit is activated. It starts and emits a warning sound.

In the above configuration, the surface of the electrophotographic photoreceptor is subjected to mechanical stress at the cleaning means 2 and the transfer portion that comes into contact with the paper. By repeating this operation, the surface roughness value of the electrophotographic photoreceptor increases. Therefore, the surface roughness detector 9 measures the surface roughness of the actual electrophotographic photoreceptor, and an alarm is generated when the surface roughness, that is, the depth of the scratches, reaches 1 or 2 (μm), which indicates an image defect. Then, the electrophotographic photoreceptor was replaced.

This will be explained in detail below.

When an electrophotographic copying machine equipped with an organic photoconductor (OPC) and a stylus-type surface roughness detector was used to pass 190,000 sheets, the surface roughness was 1.2 (μm). ), I was able to stop the operation of the electrophotographic copying machine. The images at that time were of high quality.

[Comparative example]■ When the same device as in Example 1 was used except that the stylus-type surface roughness detector was not used, white streaks appeared on the halftone image after 200,000 prints, and there were no scratches on the drum. The flaws were revealed. The surface roughness of the photoreceptor at that time was 1.6 (μm)
Met.

[Example] 2 In Example 1, the electrophotographic photoreceptor was changed from OPC to 5eTe.
Durability was carried out using the same apparatus as in Example 1 except that the electrophotographic photoreceptor was used. However, in this example, the surface roughness is 1.6
(μm) is set so that a warning can be issued. It was possible to obtain high-quality images up to a durability of 65,000 sheets.

[Comparative Example] 2 When the same device as in Example 1 was used except that the stylus-type surface roughness detector was not used in Example 2, scratches occurred in the halftone image after 67,000 sheets. did. The surface roughness of the photoreceptor at that time was 1.7 (μm).

[Example] 3 The surface roughness detector used in Example 1 was applied to an electrophotographic copying machine NP.
-1502 (manufactured by Canon Co., Ltd.), and using 10 of these machines, all the settings were set to 2.0 (μm).
The durability of 0 photoreceptors was carried out. The results are shown in Table 1.

Endurance number (number of display lights) 18500 17800
19000 18100 15300 table
1 From the above results, a total of 175,600 high-quality images could be obtained with 10 photoreceptors.

[Comparative Example] 3 The same machine as in Example 3 was used except that a surface roughness detector was not used, and as a result of durability testing with 10 machines, the results were as follows.
The minimum number of sheets that can be used with image defects due to drum scratches is 15.
It was 600 pieces. Therefore, from the viewpoint of quality assurance in the market, all drums must be replaced after the number of durable sheets is 15,600 or less, and it is only possible to obtain a maximum of 156,000 images with 10 drums.

〔Effect of the invention〕

As explained above, according to the present invention, since the detection means for detecting the surface roughness of the electrophotographic photoreceptor is provided, it is not affected by variations in the number of sheets that the electrophotographic photoreceptor can last for due to environmental differences or machine differences. It is possible to make maximum use of the electrophotographic photoreceptor.

Furthermore, since it is possible to warn before a false image occurs without determining the lifespan due to the occurrence of image defects due to scratches, the quality reliability of the image can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for explaining the electrophotographic process, and FIG. 2 is a diagram of the operating principle of the surface roughness detector. In the figure, 1 is an electrophotographic photoreceptor, and 9 is a surface roughness detection means.

Claims (1)

[Claims] An electrophotographic apparatus comprising a detection means for detecting surface roughness of an electrophotographic photoreceptor.