JPH04125663A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a photosensitive body due to ozone by adhering sheets including ozonolyzing solution on a face which is confronted with and parallel to the photosensitive body at the upper part of the photosensitive body in the vicinity of to an electrostatic charging device. CONSTITUTION:A photosensitive body unit 20 is constituted of a photosensitive belt 6, driving roller 14, driven roller 15, and grid plate 16, and is integrally attachable and detachable freely for the main body of a device. Then, activated carbon sheets 24 and 25 are respectively adhered on the lower side faces of A and B parts in the vicinity of an electrostatic charger 7, which are confronted with the photosensitive belt 6 of a casing 20a of the photosensitive unit 20, as the ozonolysis solution sheets. That is, the ozonolysis solution sheets, especially, the activated carbon sheets 24 and 25 are adhered on the face extremely near to the photosensitive body. Therefore, residual ozone being the cause of the deterioration of the photosensitive body can be efficiently resolved. Thus, the photosensitive body can be held to have a high quality for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus having a photoconductive photoreceptor and a charging device.

[Prior Art] In the above-mentioned type of image forming apparatus, charging occurs around the photoconductor.
A charging device consisting of a corona discharger is arranged for each process step of transfer, separation, and static elimination. When corona discharge is performed in the air, a large amount of ozone is generated, and when a copying process is performed continuously, the surface of the photoreceptor is oxidized by this ozone, resulting in deterioration of the sensitivity of the photoreceptor. As deterioration progresses, the charged potential decreases, which appears as background stains in a negative-positive process and as a decrease in density in a positive-positive process. It has already been proposed to discharge the ozone gas generated in this way from a charging device, but these proposals generally involve either sucking out the gas or blowing air onto it.

[Problem to be solved by the invention] All of the above methods require the installation of a fan to discharge ozone gas, which creates new problems such as noise caused by the fan, increased size of the machine, and increased cost. It is occurring. Furthermore, with the method of sucking out gas, it is difficult to generate air flow to the surface layer of the photoreceptor.
Therefore, ozone gas tends to remain in the surface layer. In addition, the method of blowing air to remove the gas has the disadvantage that the toner adhering to the photoreceptor is blown up, which contaminates the wire of the charging device and causes uneven charging.

The present invention eliminates ancillary equipment such as fans, decomposes ozone remaining in the surface layer of the photosensitive zone at low cost, without causing side effects, and stably over a long period of time, reducing its concentration or eliminating it. The objective is to prevent deterioration of the photoreceptor due to

[Means for Solving Problem 1] According to the present invention, a sheet containing an ozone decomposing agent is attached to a surface facing and parallel to the photoreceptor above the photoreceptor near the charging device. It is solved by

In order to solve the above problems, the present invention proposes that the distance between the sheet and the photoreceptor is about 1 to 10 m.

Furthermore, in order to solve the above problems, the present invention proposes that the sheet containing the ozone decomposer is an activated carbon sheet.

[Example] A laser printer to which the present invention is applied will be described below.

In FIG. 1, a paper tray 2 is removably loaded into a laser printer 1. Recording paper is fed by a paper feed roller 3 from one of the paper trays 2, and is sent forward by a conveyance roller 4, and is conveyed to a photoreceptor belt 6 by a pair of registration rollers 5 at a timing. Photoreceptor belt 6
is rotated clockwise as shown by the arrow in Figure 1,
At this time, the surface is uniformly charged by the charger 7,
The photoreceptor belt 6 is irradiated with laser light from the optical unit 8, thus forming an electrostatic latent image on the surface of the photoreceptor belt 6. This latent image is made visible by toner in the developing unit 9, and this visible image is transferred by the transfer charger 10 onto the recording paper fed to the photoreceptor belt 6 as described above. Next, the recording paper passes through a fixing unit 11, where the toner image on the recording paper is fixed, and finally is discharged to a discharge section 12. On the other hand, residual toner is removed from the photoreceptor belt 6 after the visible image has been transferred by a cleaning unit 13, and the photoreceptor belt 6 proceeds to the next copying process. The removed toner is
It is collected by the cleaning unit 13.

14 is a driving roller of the photoreceptor belt 6, 15 is a driven roller thereof, and 16 is a grid plate provided on the photoreceptor unit 20, which will be described later.

2 and 3, the photoreceptor unit 20 includes a photoreceptor belt 6, a driving roller 14, a driven roller 15. It is composed of a grid plate 16. The photoconductor unit 2o has 1
It is physically removable from the device body and therefore replaceable. The grid plate 16 is located below the charger 7 when the photoreceptor unit 20 shown in FIG. 1 is mounted.

In portions A and B near the charger 7 shown in FIGS. 2 and 3, the casing 2 of the photoreceptor unit 20
Activated carbon sheets 24 and 25 are attached as ozone decomposer sheets to the lower surface of Oa facing the photoreceptor belt 6. activated carbon sheet.

For example, it can be a sheet impregnated with powdered activated carbon, a sheet woven with activated carbon fibers (ACF), a sheet mentioned above to which an ozone-decomposing catalyst is added, or a sheet containing only the catalyst.

[Experimental Example] Experiments were conducted using a conventional laser printer and a laser printer in which activated carbon sheets were attached to the photoreceptor surface at a distance of 3 m at sections A and B in Fig. 3 according to the present invention. The results are shown in Figure 4.

For each predetermined number of prints, measure the difference between the surface potential of the normal part of the photoreceptor surface of each laser printer and the surface potential of the part deteriorated by ozone, and record these values in the graph shown in Figure 4. did. In the same graph, the vertical axis represents the potential difference on the surface of the photoreceptor.

The horizontal axis indicates the number of prints, the 0 mark indicates an experimental value using a conventional laser printer, and the x mark indicates an experimental value using a laser printer according to the present invention.

In this case, at the initial stage when the number of sheets is 0, the theoretical potential difference is O
However, in reality, the voltage is 20 to 30 V due to the unevenness of the surface of the photoreceptor.
The potential difference is about! 1JiiIllI is done. As the potential difference due to the influence of ozone increases, it appears as a density difference on the image. In this experiment, since a potential difference of 100 V resulted in a density difference rank 4 (evaluated with 2×2 images, density difference approximately 0.1 using a Macbeth densitometer), the life of the photoreceptor was determined to be a potential difference of 100 V. As a result, when comparing the lifespan of the photoreceptor in the conventional laser printer and the laser printer according to the present invention, as shown in the graph in Figure 4, the photoreceptor in the conventional laser printer reaches the end of its lifespan after about 4,500 prints. On the other hand, the photoreceptor of the laser printer of the present invention reached the end of its life after printing 13,000 sheets.

In other words, the present invention has the effect of extending the life three times.

[Effects of the Invention] In the present invention, since an ozone decomposer sheet, especially an activated carbon sheet, is attached to the surface extremely close to the photoreceptor, it becomes possible to efficiently decompose accumulated ozone, which is a cause of deterioration of the photoreceptor. A photoreceptor can be maintained in high quality for a long period of time, and additional equipment such as a fan is not required for this purpose.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a laser printer to which the present invention is applied, FIG. 2 is a perspective view showing a photoreceptor unit of the printer, and FIG.
The figure is a cross-sectional view of the photoreceptor unit taken along line 11-1 in FIG. 2, and FIG. 4 is a graph showing the experimental results. 1... Laser printer 6... Photoconductor belt 7... Charger 20... Photoconductor unit 24. 25... Activated carbon sheet No. Figure Figure Figure

Claims (3)

[Claims] (1) In an image forming apparatus having a photoconductive photoreceptor and a charging device, a sheet containing an ozone decomposing agent is attached to a surface facing and parallel to the photoreceptor above the photoreceptor near the charging device. An image forming apparatus characterized by: (2) The image forming apparatus according to claim 1, wherein a distance between the sheet and the photoreceptor is about 1 to 10 mm. (3) The image forming apparatus according to claim 1 or 2, wherein the sheet containing the ozone decomposer is an activated carbon sheet.