JPS58150980A - Adequate maintaining method of electrophotographically copied picture - Google Patents

Abstract

PURPOSE:To detect an optical system being dirty and to obtain an adequate picture while the optical system is invariably clean, by detecting and comparing the potential of one of potential parts formed based upon the exposure of a reference original with the reference potential of the potential part. CONSTITUTION:On a photoreceptor 15, the reference potential part consisting of a high potential part corresponding to a black part 3, a low potential part corresponding to a white part 4, and a fine streak part 6 with a little bit lower potential than the high potential part is formed separately from a picture part of an original 7. When the amount of exposure is deficient, the potential of the whole part rises and when the amount of charging is deficient, the potential drops, but in such a state, a comparison with a referece signal corresponding to prescribed initial condition is made by a control circuit 21 to supply a necessary control signal from a control circuit 21 according to the result of the comparison. According to whether the thin streak part 6 uses black or white, the reference potential is determined and the dirtying of the optical system 14 is detected by variation in the potential of a corresponding part of the thin streak part 6. Consequently, whether the optical system 14 is cleaned or not is displayed automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for properly maintaining electrophotographic images.

In general, the electrophotographic copying method consists of a step of forming an electrostatic latent image by charging a photoreceptor and exposing it to light, a developing step, a copying step, a fixing step, a cleaning step, and a charge removal step. The copied image may change over time, deviate from various optimal conditions due to environmental changes, etc., and may result in a copied image of poor quality. Among the conditions of each process that result in such poor quality copy images, the electrostatic latent image forming process is the most relevant.

The present invention has been made in view of the above points, and it is possible to maintain the electrostatic latent image in the most appropriate state from the viewpoint of the optical system, thereby improving the suitability of electrophotographically reproduced images to obtain high-quality reproduced images. The purpose is to obtain a maintenance method.

The present invention sets a reference original having regions with different reflectances, and detects the potential of one of the potential parts on the photoreceptor corresponding to each region with different reflectances formed based on the exposure of this reference original. However, at this time, even if the exposure amount, charge amount, etc. are appropriate, if the optical system is dirty, the potential will fluctuate due to the influence of the flexible light. can be detected,
Therefore, the configuration is such that the problem can be dealt with by cleaning the optical system or by cleaning the display.

An embodiment of the present invention will be described with reference to the drawings. First, a contact glass (1) with a predetermined width and a predetermined length is provided, and the end of this contact glass (1) has a reference original (
2) is provided. The reflective surface of this reference original (2) includes a black part (3) with low reflectance and a large area, a white part (4) with high reflectance and a large area, and black stripes (5) formed in this white background. ) by the strip part (6). Further, various types of copy originals (7) are placed on the contact glass (1).

Next, at the bottom of the contact glass (1), there is a lamp (8) with a length υ longer than the width of the contact glass (1), a plurality of reflecting mirrors (9) α1a]) (6), and a lens α3. An optical system 04 is formed, and the optical path of this optical system α reaches the surface of the photoreceptor α formed in the shape of a drum to form an exposure portion αQ. This exposed area 0Q
A charger αη is provided on the front-process side, and a surface potential detector αη for detecting the potential of the electrostatic latent image formed on the surface of the photoreceptor α is provided on the post-process side. A measurement circuit (19), a comparison circuit (e), and a control circuit Q are connected in sequence to this surface potential detector 0■.

Here, the photoreceptor α→ is exposed to the reflected light from the reference original (2) to form an electrostatic latent image on its surface. become that way. That is, a reference potential area is formed on the photoconductor 0 separately from the image area formed by the copy original (7), and a high potential area corresponding to the black area (3) and a white area (
4), and a low potential portion corresponding to 4). In the trench, the part corresponding to the striped part (6) in the low potential part has a high potential, although it is not as high as the root of the high potential part corresponding to the black part (3). Therefore, if the amount of exposure is insufficient, the overall potential becomes high as shown by the dotted line in FIG. 2, and if the amount of charge is insufficient, the overall potential becomes low as shown by the dashed line. Such a state is converted into a predetermined electrical signal in the measuring circuit 09, which is compared with a reference signal corresponding to the initial condition in the comparing circuit (e), and based on the result, the control circuit Q1
) provides the necessary control signals.

That is, if only the exposure amount has changed, a signal for changing the lamp voltage or slit opening width is output, and these are automatically corrected or corrected display is performed.

Further, if only the amount of charge is insufficient, the voltage of the charger α is automatically increased or a display is made. Furthermore, if both the exposure amount and the charge amount fluctuate, it becomes a little complicated, but by correcting either one and copying several times, both can be corrected to appropriate values.

As for the potential of the strip portion (6), there is a relationship as shown in FIG. In other words, the horizontal axis represents the density, specifically the Kodak gray scale density. When the photoreceptor surface potential is taken as , the exposure slit opening angle is 0°, 5°, 1
Regarding 0° and 15°, there is a relationship as shown in the figure for the optical system 0→ before and after cleaning. Of course, the optical system α→
The state before cleaning means that 40,000 to 50,000 copies have been made, and toner and dust have accumulated.

Therefore, when the concentration is high, the dirt on the optical system α causes diffuse reflection of light, and part of the reflected light from the white part (4) becomes flexible light, which should correspond to the striped part (6). The area on the photoreceptor is also irradiated, and the potential before cleaning is low and the potential after cleaning is high.

Furthermore, when the density is low, the amount of light to the photoreceptor is reduced due to dirt, so the potential is high before cleaning and low after cleaning. Therefore, the strip part (6
), a reference potential is determined depending on whether black or white is used, and dirt on the optical system α4 is detected by potential fluctuations of the portion corresponding to the strip portion (6) with respect to the reference potential. In this regard, FIG. 3 shows that when black or white with a high Kodak gray scale density is used, the difference from the reference potential becomes noticeable due to dirt. Depending on the result, the optical system 0→ is automatically cleaned or a message indicating that it should be cleaned is displayed.

In addition, the potential detection of each part according to the standard original (2) is as follows:
When the photoreceptor is made of αυ material with a large residual potential change, such as zinc oxide or organic photoconductor (OPC), it is desirable to perform automatic detection each time each copy is made. In addition, a photoreceptor α such as 84 with small residual potential change
In the case of υ material, the reference original (
To prevent the formation of electrostatic latent images caused by
) detection may be performed. In this case, the reference original (2) may be set in the main body or may be placed on the contact glass (1). Further, when the reference original (2) is provided in the main body, the lamp (8) may have a large overall length, and the reference original (2) may be always set on the side of the contact glass (1).

In addition, when using a 0υ photoreceptor such as 84, which has less fatigue phenomenon, the main purpose is to correct the initially set charge amount and exposure amount as described above, and to correct changes over time. Ramp (8) due to input voltage fluctuation by detecting the potential of the electrostatic latent image based on the reference original (2) every time.
A function is added to correct fluctuations in the amount of charge due to the amount of light and charge α force, as well as fluctuations in the amount of charge due to environmental changes. Furthermore, in addition to the above-mentioned functions, in addition to the above-mentioned functions, when using a photoreceptor α made of zinc oxide or an organic photoconductor that has a large fatigue phenomenon, or when performing high-speed copying even if the fatigue phenomenon is small, it is necessary to keep the contrast charging potential constant. This has the function of apparently eliminating fatigue phenomena.

As described above, the present invention detects the potential of one of the potential parts formed based on the exposure of the reference original and compares it with the reference potential of that potential part, thereby detecting contamination of the optical system. Therefore, the cleaning of the optical system or the display to be cleaned can be dealt with, and a proper copy image can be obtained under a clean optical system.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a side view, Fig. 2 is a characteristic diagram showing the relationship between the reference original and the latent image potential of the photoconductor, and Fig. 3 is a diagram showing the relationship between the reference original and the latent image potential of the photoreceptor, and Fig. 3 shows the optical system after cleaning. FIG. 3 is a characteristic diagram showing the relationship between density and photoreceptor surface potential. 2...Reference original, 4...White part (area), 6
...Striped portion (area), 14...Optical system, 15...
Photosensitive body 665-

Claims (1)

[Claims] Set up a reference original with regions of different reflectance,
The optical system detects the potential of one of the potential parts on the photoreceptor corresponding to the regions with different reflectances formed based on the exposure of this reference original, and compares it with the reference potential of that potential part. A method for properly maintaining an electrophotographic image, characterized by detecting dirt.