JPH0290189A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To reduce the deterioration in electrostatic chargeability and to remove the residual charge of a photosensitive body sufficiently by obliquely arranging an eraser with respect to the photosensitive body, and setting a reflecting plate, which irradiates the photosensitive body again with light reflected from the photosensitive body. CONSTITUTION:Detrimental light coming around an electrifier 3 can be restrained because light reflected from the surface of the photosensitive body is reflected to the upstream side in the moving direction of the photosensitive body by irradiating the photosensitive body 1 with the light of the eraser 2 from the downstream side in the moving direction of the photosensitive body to the upstream side. Because the distance between the position in which the photosensitive body 1 is irradiated and the electrifier 3 is extended, the time interval from erasing to charging is also extended, and the drop in electrostatic chargeability at a low temperature is minimized. The amount of reflection of the light with which the surface of the photosensitive body 1 is irradiated is increased because of the arrangement of the eraser 2 inclined in the direction of the normal line of the photosensitive body; however, the residual charge of the photosensitive body 1 is sufficiently removed because the reflecting plate 20 irradiates the photosensitive body 1 with the reflected light again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic copying apparatus having an eraser for erasing residual charges on a photoreceptor with light.

[Prior Art] In an electrophotographic copying apparatus, residual charges on a photoreceptor are usually erased by irradiating the photoreceptor surface with light from a light source, such as a tungsten lamp or a light emitting diode, placed near the photoreceptor surface. It will be done.

In recent years, with the miniaturization of electrophotographic copying apparatuses, photoreceptors have become smaller and larger, and the number of elements disposed around the photoreceptors has increased, such as the provision of two or more developing units for multicolor development. Therefore, the space for disposing the optical eraser for erasing residual charges becomes narrower, and the distance between it and equipment placed before and after it, such as a cleaner or a band TL device, becomes narrower. Therefore,
In order to make the structure simple and compact, some proposals have been made in which the light source is located at a different location and the photoreceptor surface is irradiated with light guided by an optical fiber to erase residual charges (for example, (See Japanese Patent Application Laid-Open No. 127786/1986).

[Problems to be Solved by the Invention] When the distance between the eraser and the charger is narrow, the light irradiated from the eraser to the photoconductor goes around the charger and becomes harmful light that reduces charging performance in the charging process. The charging ability can be improved by increasing the capacity of the transformer, but this is not preferable because it also increases the corona current and the amount of ozone generated.

Furthermore, if the distance between the eraser and the charger is narrow, or
If the rotation speed of the photoreceptor is increased in order to increase the speed of the copying process, a phenomenon may occur in which the charging ability decreases at low temperatures. This is because at low temperatures, it takes longer for the electron-hole pairs generated in excess by the eraser's light to recombine, so the charging process begins before they completely recombine and disappear. It is thought that the charging ability decreases because the movement occurs and the charged charges are canceled out.

[Means for Solving the Problems] An electrophotographic copying apparatus having an eraser for erasing residual charges on a photoreceptor with light according to the present invention is provided such that the eraser is moved from the downstream side to the upstream side in the photoreceptor movement direction with respect to the photoreceptor. It is characterized in that it is arranged diagonally so as to irradiate light toward the eraser, and a reflecting plate is installed upstream in the direction of movement of the photoconductor with respect to the eraser to irradiate the light reflected by the photoconductor back to the photoconductor. do.

Further, the reflecting plate is a reflecting member attached to the cleaning blade or a holding member of the blade, or a reflecting surface formed on one surface of the holding member of the cleaning blade.

Further, the reflecting plate is installed so as to irradiate the reflected light from the photoreceptor irradiation position substantially perpendicularly to the surface of the photoreceptor.

Further, the light source of the eraser is a light emitting diode.

[1 for t'F In the above configuration, when the eraser light is irradiated from the downstream side in the photoconductor movement direction (that is, from the charger side), the reflected light on the photoconductor surface is reflected toward the upstream side in the photoconductor movement direction. As a result, harmful light from passing around the belt to the container can be suppressed, and a decrease in charging performance due to harmful light can be reduced.

Furthermore, since the distance between the photoreceptor irradiation position and the charger becomes longer, the time from erasing to charging becomes longer, and the deterioration in charging ability at low temperatures is also reduced.

Furthermore, since the eraser is arranged at an angle with respect to the normal direction of the photoconductor, the amount of reflected light on the surface of the photoconductor increases, but by providing a reflector, the reflected light can be irradiated onto the photoconductor again. Therefore, the residual charge on the photoreceptor is sufficiently erased.

[Example] The present invention will be described in detail below based on the drawings.

FIG. 2 is a sectional view schematically showing the structure of an electrophotographic copying apparatus to which the present invention is applied.

A photoreceptor drum (
1) is rotatably supported in the counterclockwise direction in the figure, and around it is an eraser (2).

Charger (3), machine end and inter-image eraser (5).

A developing device t (6), a transfer charger (7), a single separation charger (8), a cleaning device (9), etc. are arranged in this order. The photoreceptor drum (1) is provided with a photoreceptor layer on its surface, and this photoreceptor is uniformly charged by passing through the eraser (2) and charger (3), and then passed through the scanning optical system (10) through the slit. An electrostatic latent image is formed on the surface by image exposure through the section (4), and charges outside the image forming area are erased by the end and image-to-image eraser (5). The electrostatic latent image formed in this manner is converted into a toner image by the developing device R (6), and is transferred by the transfer charger (7) I onto the copy paper conveyed from the paper feed device (11). Separate charger (8) for unifying copy paper
is separated from the photoreceptor drum (1) by the conveyor belt 1.
- (12), it is sent to the fixing device (13), and after the image is fixed, it is discharged to the tray (14). After the transfer, the photoreceptor drum (1) is cleaned by a cleaning device (9) to remove toner remaining on its surface, and is again treated by an eraser (2).
The remaining charges are erased and the copying process is prepared for the next copying process.

Before explaining the present invention in detail, the phenomenon of poor charging at low temperatures mentioned above will be explained.

FIG. 4 is an enlarged view of the vicinity of a conventional eraser (2) using a single tungsten lamp as a light source. When this eraser was used and an OPC photoreceptor was used as the photoreceptor drum (1), the charging potential V0 by the charger (3) was -440V. Furthermore, the tungsten lamp (1) is connected to the charger (3).
In order to eliminate the light leakage in 5), a light shielding plate (3a) indicated by a broken line in the figure was used as a countermeasure, and a charging potential V of -47 Ova was obtained. Here, the above light shielding plate (3a
) installed in a low-temperature environment of 5°C, a charging potential V0 of -390VL could not be obtained.

This decrease in the charging potential V0 at low temperatures is considered to be due to the following reason. That is, residual charges on the photoreceptor are erased by the eraser (2), but at this time, free charges are generated inside the photoreceptor layer due to excess light from the eraser (2). At low temperatures, the time for these free charges to recombine and disappear, that is, the lifetime of the carriers, becomes longer, so even when they reach the next charger (3), there are many free carriers, and the charged charges are not exposed to light. When applied to a body, the charging potential Vo decreases to neutralize the charge.

To deal with this, the light from the eraser (2) is transferred to the charger (3).
) may be irradiated to a position separated by light. As a result, the effect of light leakage is small, and the eraser (2) is not generated by excessive light from the eraser (2). It is preferable to arrange the photoreceptor obliquely so that the light is irradiated from the downstream side to the upstream side in the direction of movement of the photoreceptor. By arranging it in this manner, it becomes possible to easily remove not only the light reflected on the surface of the photoreceptor but also other harmful light.

FIG. 1 is an enlarged view of the vicinity of an eraser (2) according to a first embodiment of the present invention. The cleaning device (9) includes a cleaning blade (16), a holding member (17) of the blade (16), and a mechanism (1) for discharging residual toner removed from the surface of the photoreceptor drum (1) by the blade (16).
8). Between the cleaning device (9) and the charger (3), a light source for the eraser (2) is a light emitting diode (hereinafter referred to as LED) (19) that emits light from the downstream side to the upstream side in the direction of photoconductor movement. It is placed diagonally to illuminate the area. At this time, when the irradiation angle of the LED (+9) becomes too large with respect to the normal to the surface of the photoreceptor drum (1), the amount of reflection on the photoreceptor surface increases, and direct irradiation light alone is insufficient to erase the residual charge. However, there is a reflector plate (20) that re-irradiates the light reflected by the photoreceptor onto the photoreceptor.
By installing the LED (19,), the light from the LED (19,) can sufficiently illuminate the photoreceptor. The above reflector (
20) uses a reflective member with an aluminum reflective surface as a blade (
16) is attached to the holding member (17) with bolts. Although this reflective surface can be installed at any angle with respect to the photoreceptor drum (1),
) In order to improve the efficiency of erasing the residual charge on the surface of the photoconductor and not adversely affect the charging process, the reflected light from the photoconductor irradiation position of the LED (19) is directed in the normal direction of the photoconductor surface or slightly upstream. It is installed so that it illuminates at an angle that is tilted to the side.

FIG. 3 shows an eraser (2) according to the second embodiment of the present invention.
It is an enlarged view of the vicinity. In the second embodiment, the reflector (20)
is directly glued to the blade (16). For this reason,
Mounting the reflector (20) requires no space, resulting in a compact configuration.

Furthermore, there is little influence on the arrangement of other elements. here,
Since the angle of the reflector (20) is the same as the angle of the blade (16), the light source of the eraser (2) is used so that the reflector (20) re-irradiates the light reflected by the photoconductor onto the photoconductor. It is necessary to properly place certain LEDs (19). When an LED (19) is used as a light source, the spread and directionality of the light is fixed, so it should be installed in a way that does not produce harmful light, and a reflector (
20) facilitates proper installation for re-irradiating the photoreceptor (1).

In addition, the reflecting plate (20) can also have the - side of the blade (16) or the holding member (17) as a reflecting surface by, for example, vapor deposition of aluminum.

In addition, in each of the above embodiments, the cleaning device (9)
If the reflective plate is removable, dirt on the reflective plate can be easily cleaned.

[Effects of the Invention] As explained above, by irradiating the eraser light onto the photoconductor from the downstream side to the upstream side in the photoconductor movement direction, the reflected light on the photoconductor surface is directed to the upstream side in the photoconductor movement direction. reflect. This makes it possible to suppress harmful light from entering the charger.

Furthermore, since the distance between the photoreceptor irradiation position and the charger becomes longer, the time from erasing to charging becomes longer, and the deterioration in charging ability at low temperatures is also reduced.

Furthermore, since the eraser is arranged at an angle with respect to the normal direction of the photoconductor, the amount of reflected light on the surface of the photoconductor increases, but the reflected light is irradiated onto the photoconductor again by the reflection plate. , the residual charge on the photoreceptor is sufficiently erased.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of essential parts of a first embodiment using an eraser according to the present invention, FIG. 2 is a sectional view schematically showing the structure of an electrophotographic copying apparatus of the present invention, and FIG. 3 is a second embodiment. FIG. 4 is an enlarged view of the vicinity of a conventional eraser using a tungsten lamp as a light source. l...Photosensitive drum, 2...Eraser, 3...
Charger. 9... Cleaning device t, 16... Cleaning blade, 17... Holding member, 19... LED,
20...Reflector applicant Minolta Camera Co., Ltd.

Claims (5)

[Claims] (1) In an electrophotographic copying apparatus having an eraser for erasing residual charges on a photoreceptor with light, the eraser is tilted so as to irradiate the photoreceptor with light from the downstream side to the upstream side in the direction of movement of the photoreceptor. What is claimed is: 1. An electrophotographic copying apparatus characterized in that a reflecting plate is disposed on the upstream side of the eraser in a direction in which the photoconductor moves, and that reflects light reflected by the photoconductor and irradiates the photoconductor again. (2) The electrophotographic copying apparatus according to claim 1, wherein the reflective plate is a reflective member attached to a cleaning blade or a blade holding member. (3) The electrophotographic copying apparatus according to claim 1, wherein the reflective plate is a reflective surface formed on one surface of a holding member of a cleaning blade. (4) The electrophotographic copying apparatus according to claim 1, wherein the reflection plate is installed so as to irradiate the reflected light from the photoreceptor irradiation position substantially perpendicularly to the surface of the photoreceptor. (5) The electrophotographic copying apparatus according to claim 1, wherein the light source of the eraser is a light emitting diode.