JPH09146429A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the corona discharge efficiency of the AC electrostatic eliminator of an electrophotographic printer, and prevent the cleaning failure of untransferred toner without increasing the AC output to provide a regularly stable quality of print. SOLUTION: This device has a photoconductive photoreceptor 1, a charger 2 for charging the photoreceptor 1, an exposing light source 5 for forming an electrostatic latent image on the photoreceptor 1, a developing machine 6 for developing the electrostatic latent image, a transfer device 7 for transferring the developed image to a sheet, and an AC static eliminator having a wire member 10 for performing the static elimination of the photoreceptor 1. The printing process speed is set switchable, and the AC static eliminator 8 is controlled by a static eliminator movable control mechanism 20 in such a manner that the gap between the wire member 10 of the AC static eliminator 8 and the photoreceptor 1 is narrowed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus A
C (alternating current) static eliminator.

[0002]

2. Description of the Related Art FIG. 5 shows a schematic view of a conventional example of an electrophotographic apparatus.

As shown in FIG. 5, a photoconductor 1 which is a photoconductor is uniformly charged by a charger 2. Next, the photoreceptor 1 is exposed by the exposure light source 4 to form an electrostatic latent image,
The developing roller 5 of the developing machine 6 develops the electrostatic latent image on the surface of the photoreceptor 1. The developing device 6 is filled with a developer 16 in which a toner 13 which is a powder ink and a carrier 15 which is frictionally charged with the toner 13 are mixed at a constant ratio.

The developed image on the photosensitive member 1 is transferred onto the sheet 17 by the transfer unit 7 and fixed by a fixing unit (not shown).

The photoconductor 1 to which the untransferred toner 14 after transfer is attached is neutralized and cleaned by the AC static eliminator 8, the erase lamp 11 and the cleaning brush (cleaner) 12, and the above process is repeated.

FIG. 6 shows the relationship between the printing process speed of the electrophotographic apparatus and the required output of the AC static eliminator. The relation between the gap between the AC static eliminator 8 and the photoconductor 1 of the conventional electrophotographic apparatus is as follows.
Even if the process speed of the electrophotographic apparatus changes, it is constant. On the other hand, as the process speed of the electrophotographic apparatus becomes faster, the output of the AC static eliminator 8 is increased by the high voltage power source 3 to enhance the cleaning ability. .

[0007]

In the AC static eliminator of the electrophotographic apparatus, as the printing process speed becomes higher, the cleanable AC output to the untransferred toner 14 of the photoconductor 1 after transfer increases. However, if it is attempted to clean the untransferred toner 14 on the photoconductor 1 by increasing the AC output, discharge failure increases, which causes a shortened life of the AC static eliminator.

It is an object of the present invention to improve the above points, increase the reliability of an electrophotographic apparatus, and always provide stable print quality.

[0009]

In order to achieve the above object, the present invention provides an electrophotographic apparatus as described above, wherein the gap condition between the wire member of the AC static eliminator and the photoconductor is set according to the printing process speed. Was set to be different.
As a result, the gap between the wire member of the AC static eliminator and the photoconductor can be set to be narrower as the printing process speed is faster.

The faster the printing process speed, the narrower the wire between the AC neutralizer and the photoreceptor,
AC corona discharge for static elimination is efficiently performed on the photoconductor. As a result, the untransferred toner on the photoconductor 1 can be cleaned with a lower AC corona voltage than that of the conventional technique.

In the case of the low speed process, the gap between the wire member of the AC static eliminator and the photoconductor becomes wider than that in the high speed process. The reason is that for slow processes,
The fact that a relatively high AC output is not required and that the gap is constantly narrowed increases the probability that the wire member / photoreceptor comes closer than allowable to cause spark discharge for some reason such as vibration (spark discharge). Causes damage to the photoconductor). Therefore, in order to minimize the probability of occurrence of such a defect, the gap is narrowed under the minimum necessary conditions such as in a high speed process.

[0012]

1 to 4 show an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a block diagram showing the electrophotographic apparatus of the present embodiment, in which a photoconductor 1, a charger 2, a high voltage power source 3, an exposure light source 4, a developing roll 5, a developing machine 6, a transfer device 7 and an AC. It is composed of a static eliminator 8, an erase lamp 11, and a cleaning brush 12, and its basic printing process (a series of steps of charging, electrostatic latent image, development, transfer and static erasing cleaning)
The operation is similar to that of the conventional example shown in FIG. 5, and the description thereof is omitted here.

The difference from the conventional example is that the gap condition between the wire member 10 of the AC static eliminator 8 and the photoconductor 1 is set to be different according to the printing process speed. Therefore, the AC static eliminator 8 has a static eliminator movement control mechanism 20 that narrows the gap between the wire member 10 and the photoconductor 1 as the printing process speed increases. Static eliminator movable control mechanism 20
Has a function of automatically adjusting the gap between the wire member 10 and the photoconductor 1 as described above when the speed condition of the printing process is set. The AC static eliminator 8
Is composed of a wire member 10 and a shield member 9.

2A and 2B, the AC static eliminator 8 with respect to the printing process speed of the electrophotographic apparatus in this embodiment is shown.
The relationship between the wire member 10 and the gap a between the photosensitive member 1 is shown.

The wire member 10 of the AC static eliminator 8 and the photoconductor 1
2, the gap a is set to be narrower as the process speed of the electrophotographic apparatus becomes higher.

FIG. 3 shows the AC output (current) and A of the high-voltage power supply 3.
The relationship of C corona voltage is shown in comparison with the prior art. As is apparent from FIG. 3, even if the output (current) of the high voltage power supply 3 is the same as that of the conventional technique, it can be used at a low AC corona voltage. That is, the efficiency of AC corona discharge is increased in the present invention.

FIG. 4 shows a relationship between the gap a and the efficiency of AC corona discharge. This indicates that the narrower the gap a between the wire member 10 and the photoconductor 1 is, the better the efficiency of AC corona discharge is. That is, as the speed of the electrophotographic process becomes faster, the gap a is narrowed, so that the efficiency of AC corona discharge is increased and the cleanability can be maintained without increasing the AC corona voltage.

In the low speed process, the gap a between the wire member 10 of the AC static eliminator 8 and the photosensitive member 1 is controlled to be wider than in the high speed process. The reason is,
As described above, in the case of a slow process, a relatively high A
The fact that the C output is not required and that the gap a is always narrowed increases the probability that the wire member 10 and the photoconductor 1 approach each other more than the allowable value to induce spark discharge for some reason such as vibration (spark discharge). Causes damage to the photoconductor), so that the above-mentioned gap is narrowed under the minimum necessary condition such as a high-speed process in order to minimize the probability of occurrence of such a defect.

By adopting the above-described variable system of the gap a, even in a higher speed electrophotographic apparatus, the AC
Since the cleaning performance can be maintained without increasing the corona output,
It is possible to increase the reliability of the electrophotographic apparatus and always maintain stable print quality.

[0021]

According to the present invention, the efficiency of AC corona discharge can be improved by setting the gap between the wire member of the AC static eliminator and the photoconductor in accordance with the process speed of the electrophotographic apparatus, and narrowing the higher the speed. Since cleaning failure can be prevented without increasing the AC output and the AC output, it is possible to increase the reliability of the electrophotographic apparatus and always maintain stable print quality.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing the relationship between the AC static eliminator of this embodiment and the gap between the photoconductors.

FIG. 3 is an AC of a high-voltage power supply 3 of the electrophotographic apparatus of this embodiment.
Explanatory drawing which shows the relationship between an output and AC corona voltage.

FIG. 4 is an explanatory diagram showing the relationship between the gap between the wire member of the AC static eliminator and the photoconductor and the AC corona discharge efficiency.

FIG. 5 is a schematic diagram of a conventional electrophotographic apparatus.

FIG. 6 is an explanatory diagram showing a process speed of a conventional electrophotographic apparatus and a required output of an AC static eliminator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive member, 2 ... Charging device, 3 ... High-voltage power source, 4 ... Exposure light source, 5 ... Developing roll, 6 ... Developing device, 7 ... Transfer device, 8 ... A
C static eliminator, 9 ... Shield member, 10 ... Wire member, 11
... Erase lamp, 12 ... Cleaning brush, 13 ...
Toner, 14 ... Untransferred toner, 15 ... Carrier, 16 ...
Developer, 17 ... Paper, 20 ... Static eliminator movable control mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kohei Katayama 1060 Takeda, Hitachinaka City, Ibaraki Prefecture Hitachi Koki Co., Ltd.

Claims (2)

[Claims] 1. A photoconductor having photoconductivity, a charger for charging the photoconductor, an exposure light source for forming an electrostatic latent image on the photoconductor, and a development for developing the electrostatic latent image. Machine,
An electrophotographic apparatus capable of switching the printing process speed, which includes a transfer device for transferring an image after development to a sheet, an AC neutralizer having a wire member for neutralizing the photoconductor, and a cleaner for cleaning the surface of the photoconductor. In the electrophotographic apparatus, the gap condition between the wire member of the AC static eliminator and the photoconductor is set to be different according to the printing process speed. 2. The electrophotographic apparatus, wherein the AC static eliminator has a static eliminator movement control mechanism that narrows the gap between the wire member and the photoconductor as the printing process speed increases.