JPS60156069A - Electrophotographic apparatus - Google Patents

Abstract

PURPOSE:To prevent an electrostatic latent image formed on a photosensitive body from being affected by electrostatic charge by preventing accumulation of electrostatic charge around the photosensitive body. CONSTITUTION:The circumference of the photosensitive drum 1 of a transfer type electrophotographic copying machine having a photoconductive layer on the surface is surrounded with a series of image-forming process means, and further, their casings 10, 10a opposite to each other. When they are made of plastics in order to reduce weight and cost, electrostatic charge accumulates on account of their insulating properties, and affects an electrostatic latent image formed on the drum 1. To prevent it, conductive film 11, 11a are formed on the surfaces of the casings 10, 10a by coating or the like and such charge is allowed to escape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a copying apparatus that utilizes an electrophotographic process called the Carlson process, and particularly relates to an electrophotographic apparatus for obtaining high-quality copies. be.

Conventional Structures and Problems With the demand for smaller and lighter copying apparatuses, the casing and other constituent members of the apparatus are being replaced from metal materials to lighter plastic materials. These plastic materials are generally highly insulating, tend to collect static electricity, and are easily charged.

In electrophotographic copying machines, is it possible to charge an electrostatic image on the main surface of the photoreceptor? This is the first necessary process in forming a vessel. In addition to the above-mentioned charging, the magnitude of the surface potential formed on the photoreceptor and its fluctuations affect the quality of the copied image. In particular, fluctuations during one process are
Is there a clear deterioration in the image quality? bring.

Electrophotography necessarily involves the processes of discharging, charging, and eliminating static electricity. In each of these processes, the peripheral portion of the photoreceptor is easily charged due to the above-mentioned reasons, and the charge is difficult to be removed. As a result, it is considered that the peripheral portion has a high possibility of secondarily exerting an electrostatic influence on the main surface curve of the photoreceptor. However, to date, the above-mentioned broad-based problems have not received sufficient attention and research, and therefore, no methods or means for solving them have been specified.

OBJECTS OF THE INVENTION The present invention seeks to provide an electrophotographic apparatus that solves the above-mentioned problems.

Structure of the Invention In order to achieve the above-mentioned object, the present invention provides a housing in which the main surface of a highly insulating casing located around a photoconductor and facing the surface of the photoconductor is coated with an antistatic film. As a result, fluctuations in the potential of the photoreceptor (Table (2)) can be reduced.

DESCRIPTION OF EMBODIMENTS The structure of an electrophotographic apparatus according to the present invention will be described below with reference to the drawings. Electrophotographic methods currently in practical use are based on the rotation of a photoreceptor, and include (1) a one-rotation, one-process method and (2) a two-rotation, one-process method. Therefore, the embodiments of the present invention in each method are shown in FIGS. 1 and 2.
Each is shown in the figure.

First, Figure 1 is a cross-sectional view of the main parts of the photoreceptor and its surroundings in case (1) above, and 1 is a photoconductive material such as selenium or cadmium sulfide on the lower surface! 2 is a charging corona discharger that applies 2 charges to the main surface of 1; 3 is a halogen lamp for exposure; 4 is a short focus imaging array t15 on the main surface of 1; 6 is a transfer corona discharger that transfers the visible image on the above 1 onto a copy paper (not shown); 7 is a device for peeling off the copy paper from the above 1; 8 is a cleaning blade for scraping off the residual developer on said 1, 9 is a static elimination lamp for removing residual charge on said 1, 10 is a stripping corona discharger t among said 4 and 5. A part of the casing located in between and close to the lower surface of 1 1 Similarly, 10a is a part of another casing located between 7 and 8 t111 is on the main surface opposite to the 1 side of 10. The provided antistatic film 11a also represents the antistatic film provided on the main surface opposite to 1 of 10a.

FIG. 2 is a cross-sectional view of the main part of the photoreceptor and its surroundings in the case of @'+1 (2), where 12 is a belt photoreceptor having an organic optical semiconductor on its lower surface, and 13 is a belt photoreceptor having an organic optical semiconductor on its lower surface. The rotation driving roller t114 is a rotation driven roller t114 that smoothes the rotation by the 12 and 13, and 15 is the rotation driven roller t114 that smooths the rotation by the 12 and 13.
A support plate t116 is used to apply the necessary tension to the film and to attach the skin to the surface.A corona discharger t117 is a halogen lamp for exposure.118 is a short focus imaging array.19 is a developing device similar to 6 above. i, 20 is 1 with respect to the photoreceptor surface
A cleaning blade which repeats separation and N every rotation and has the same action as 8 above, 21 a static elimination lamp similar to 9 above, and 22 a part of the casing close to and facing the upper surface of 12 above. 22a is also a part of another casing located between 18 and 2Q and close to the upper surface of 12, and 22b is located close to the main surface of 12 above 14 as a king. 23. 23a is a part of another casing that faces the casing 22c, which is located between the 16 and 19 and close to the lower surface of the 12.

23b and 23c are the above-mentioned 22, 22a, and 22, respectively.
The antistatic film 2 provided on the main surface facing the above-mentioned 12 of b22c is shown, respectively.

In addition, the thin arrows common to both figures indicate the rotational direction of the drum that supports and drives each sensor, and the thick arrows and the Roman letters C, B, C, and p attached to them indicate surface electrometers. The measurement points at which the potential of the lower surface of each photoreceptor was measured are shown below. As can be easily understood from the above,
The electrophotographic device based on the present invention has a simple structure in which an antistatic film, which is indicated by diagonal lines in both figures, is only provided at a predetermined location, and is practical for reducing potential fluctuations on the surface of the photoreceptor, which is the main part. It can have a very effective effect.

Below, the measurement results at the measurement points will be described in more detail.

(2) Table 1 shows variations in the photoreceptor surface potential in specific examples. However, the measurements at 8 points and 0 point were made without exposure, and the so-called dark decay of the potential at mermaid and 0 points, respectively.
This corresponds to what was observed. The meaning of Table 1 will be explained below. First, in the top row (first line), t and nu completely indicate the material of the photosensitive material, and represent selenium (Se) and organic photoconductor (OPC), respectively. Upper row (2nd
Lines 8 to D are the same as symbols A to D shown in FIGS. 1 and 2, and correspond to the points at which the predetermined surface potential of each photoreceptor was measured using a commercially available surface potentiometer.

However, regardless of whether the photoreceptor is drum-shaped or belt-shaped, the position is related to the lengthwise position, that is, the valley process of the copying process, and the position difference in the width direction (for example, in the center) There was almost no difference (difference between the measured values at both ends) (less than 1 inch) and could be completely ignored in practical terms. The numbers in the leftmost column indicate the discharge pressure of the corona discharger in kilovolts (KV).
). For each discharge pressure, the results are divided into upper and lower two stages, with the upper stage corresponding to the conventional example and the lower stage corresponding to the example of the present invention.

Furthermore, q! The r stage consists of two rows, upper and lower, and shows specific changes in potential.
The position expressed by the J-boruto position (V) is shown in parentheses on the bottom line.

The difference in potential between the entry point and the B point and between the 0 point and the 0 point is
This corresponds to a change in the surface potential of the photoreceptor over a relatively long period of time (a kind of change over time during the copying process), so to speak, it monitors a single point within the copied image. Therefore, overall unevenness in image quality (disturbance in spatial image quality in one copy image) is not affected. Rather, the factor that influences the unevenness in image quality is the pulsation of the potential at each of the points (minor fluctuations within a relatively short period of time).

This is because it corresponds to the longitudinal spatial distribution of the copied image. The pulsation rate (η) is defined by the following equation. That is,...(1) In order to explain formula (1) in an easy-to-understand manner, the numerical values in Table 1 are used.

For example, from the upper left column of Table 1, vMa! =720V
, V, , n=710V and 7ip, fluctuation range (ΔvP-P
) Ic1oV (near 20V-710V), pressure 4 at the center L<B720+710 Average! Pressure (VM) 'I'171 sv (=: V
). Therefore, from equation (1), the pulsation rate in this case is η:10V/715V=0.01399.

The above fluctuation width expressed as a percentage of the total fluctuation with respect to the center voltage is given in the upper row. Incidentally, in the example of the present invention shown in Table 1, a commercially available electrostatic shielding cloth material (with a surface resistance value of 1089 based on a predetermined measurement method) was used on the main surface of the predetermined casing described in the explanation of the drawings. (ohm) or less). As can be seen from Table 1, the variation rate of the photoreceptor surface potential in the example of the present invention is reduced compared to the conventional example. This is due to electrostatic induction caused by charges generated on the surface of the casing facing the surface of the photoreceptor ball! It is thought that the changed potential on the surface of the photoreceptor is due to the electric charge on the surface of the casing being reduced or eliminated due to the conductivity of the electrostatic shielding coating, making it difficult to fluctuate.

Unlike frequency electromagnetic shielding, etc., the surface resistance on the insulator becomes a major problem in removing surface charges on the insulator and making antistatic effects effective.

Therefore, the thickness of the electrostatic shielding film is not a particular problem. In other words, as long as the surface resistance is sufficiently low, the film thickness of the conductive material may be as thin as possible. Therefore, the anti-static film of the present invention can be used as described above. Without being limited to lJ, 1) a gold maple film formed by various methods;
2) Various conductive plastics, rubbers and paints, 3
) Antistatic paint, antistatic liquid, etc. can be used.

In this way, the electrophotographic apparatus having the structure based on the present invention discovers and solves the problem of the interlens point, which was hitherto unknown.
A stable photoreceptor surface potential can be obtained.

Effects of the Invention As can be understood from the above explanation, the electrophotographic apparatus based on the present invention is superior to conventional ones in the following respects.

That is, (i) a very simple construction and therefore a relatively low cost;
A stable photoreceptor surface potential can be obtained.

(2) Since the potential change on the surface of the photoreceptor during the copying process is reduced, copies with the same image quality as mentioned above can be obtained.

In short, it is possible to provide an electrophotographic copying apparatus with a simple configuration and high reliability in image quality.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of a photoreceptor and its surroundings in a one-rotation, one-process electrophotographic apparatus according to an embodiment of the present invention, and FIG. 2 is a two-rotation diagram according to another embodiment of the present invention. 1
FIG. 2 is a sectional view illustrating a main part of a photoconductor and its surroundings in an electrophotographic process apparatus. 10.10a, 22.22a, 22b, 220・
...Antistatic film.

Claims (1)

[Claims] 2. An electrophotographic apparatus, wherein the main surface of a highly insulating casing located around a photoreceptor and facing the surface of the photoreceptor is coated with an antistatic film.