JPS623273A - Cleaning device - Google Patents

Abstract

PURPOSE:To obtain an invariably excellent image by forming a toner layer by coating nearby the part where an elastic cleaning roller is pressed against the surface of an image carrier when a device is no used, and cleaning the surface. CONSTITUTION:Toner which remains on the surface of the image carrier without being transferred reaches a cleaning device 9 is provided with a cleaning blade 10 and the cleaning roller 11 which is made of silicone rubber on the upstream side in the running direction of the image carrier and rubbed against the image carrier. Residual toner and other foreign matter are removed by the cleaning roller and cleaning blade, scraped by a scraper 12, and discharged by a screw conveyor 13. Consequently, images of excellent quality are obtained stably for a long period by using a small amount of toner while roller tracks due to the pressing of the elastic cleaning roller against the image carrier are prevented from being formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus using an electrophotographic process, such as an electrophotographic copying machine or a printer, and particularly to a cleaning apparatus therefor.

(Joro technology and issues to be solved) A transferable toner image is formed on a continuously running image carrier, and a sheet-like transfer material mainly made of paper is transferred in close proximity to or in contact with the toner image, and then the image is transferred. Image forming apparatuses that repeat the process of separating toner from a carrier and cleaning residual toner remaining on the image carrier without contributing to transfer using an appropriate cleaning means are conventionally well known.

In such devices, it is essential to sufficiently remove residual toner in order to obtain high-quality images, and for this purpose, cleaning blades made of elastic materials such as rubber have traditionally been used. It is widely used.

However, although cleaning blades have an excellent toner removal function, they do not remove toner particles that adhere to the image bearing member due to paper dust, precipitates such as rosin, talc, etc., corona products generated by corona discharge, and toner particles that have fused and solidified. It was not very effective in removing foreign substances such as.

Therefore, in order to remove the above-mentioned foreign substances, a method has already been proposed in which an elastic cleaning roller made of an elastic material such as silicone rubber, urethane rubber, fluorine rubber, or polyethylene rubber is rubbed against the surface of the image carrier. It is effective in removing toner and other foreign substances.

However, for example, in the case of a cleaning roller using silicone rubber, if the roller is left in pressure contact with the image carrier without using the device for a long time, unreacted low molecular weight oil that is contained in the silicone rubber at several weight percent may be removed. The particles may leach out and adhere to the surface of the image carrier, resulting in deterioration of image quality that appears as black streaks in the corresponding portions of the image.

If you do not use the copying machine for 4 days and then operate it, such black streaks may not disappear from the beginning on about 10 to 20 copies.

The present invention has been made in order to cope with such a situation, and an object of the present invention is to provide an image forming method that can always obtain good images without the appearance of black streaks as described above. It is something.

(2) Structure of the invention (technical means for solving the problem, its operation) In order to achieve the above object, in this invention, when the image forming apparatus is not in use during the preliminary rotation of the image carrier before copying is possible, The elastic cleaning roller is configured to coat the toner layer near the portion where the surface of the image carrier was in pressure contact for cleaning.

With this configuration, it is possible to always obtain high-quality images by cleaning unreacted oil contained in the cleaning roller adhering to the surface of the image carrier during preliminary rotation of the image carrier.

(Description of Embodiments) FIG. 1 is a side view of the main parts of a copying machine to which the present invention can be applied, in which a photoconductive layer on the surface of a rotating cylindrical image carrier l rotating in the direction of the arrow is shown first. After the residual charge is removed by the exposure means 2, a uniform charge is applied by the negative charger, and a light image of the original is irradiated onto this, forming an electrostatic latent image. This latent image becomes a transferable toner image by the developing device 5, and the toner image is
Separately, the transfer material is supplied via the conveyance path 6 and transferred to a transfer material that is close to or in contact with the image carrier, and this transfer material moves away from the image carrier, while it does not contribute to the transfer and is transferred to the surface of the image carrier. The remaining toner reaches the cleaning device 9 as the image carrier rotates.

The cleaning device 9 includes a cleaning blade 10;
A cleaning roller 11 made of silicone rubber that rubs against the image carrier is disposed on the upstream side when viewed in the running direction of the image carrier.

It is assumed that the aforementioned residual toner and other foreign matter are removed by the cleaning roller and cleaning blade, then scraped off by the scraper 12, and further discharged by the screw conveyor 13.

In the present invention, a part of the surface of the image carrier is coated with toner in the above-mentioned apparatus.

FIG. 2 shows a sequence in which toner is applied to an image carrier using only a developing bias.

The time point at which the image carrier starts rotating is t. When closing, points A and B on the surface of the image carrier are n after the image carrier starts rotating.
The time when the developer passes through the developing device position P point is 1.
1, and a toner An Bn layer can be formed between AB.

FIG. 3 shows a sequence in which the surface of the image carrier is charged and then toner is similarly applied using a developing bias.

Next, an experimental example based on the above conditions will be described.

The image carrier (photoreceptor) is an amorphous silicon photoreceptor with a diameter of 108 m+s, and one elastic roller has a sponge layer on the outside of the core metal, and one surface layer is 1! I11
The material used had a thick silicone rubber layer (unreacted oil content of 2 to 3 wt%) and a diameter of 20 mm. This roller is approximately 1
Press against the photoreceptor with a pressure of kg, and the nip width is approximately 2+w+
The toner application width was approximately 50 mm.

Further, in the sequence shown in FIG. 2, DC-100V was applied as a developing bias.

In the sequence shown in FIG. 3, the surface of the photoreceptor is charged to +200V by the primary charger, the development bias DC+100V is applied to the area where toner is applied, and the potential of the photoreceptor is 200V to the area where toner is not applied, i.e. 400
Applying a developing bias of V, the Act portion is 1800H.
,1400,.

was applied.

The number of rotations during the pre-rotation of the photoreceptor was 15 rotations.

Under the above conditions, we stopped the copying machine for a week and brought the elastic cleaning roller into close contact with the photoconductor, and then performed image forming operations. As a result, there were no black streaks caused by the contact of the rollers as described above. There wasn't.

In addition, in the Siganas shown in Figure 3, AC is used as the developing bias.
, DC were both used, but if sufficient effects can be obtained,
Only DC bias may be used.

Preliminary rotation is also performed in abnormal situations such as when clearing a jam, but in such cases, of course, the above sequence is not performed because the vehicle condition such as black streaks due to oil leakage does not occur. Good too.

Furthermore, since new elastic cleaning rollers are prone to black streaks, it is recommended that the above sequence be turned on and off externally so that they can be activated as needed, or that the without continuing.

It may be configured to be performed only for a certain valid period of time.

According to the embodiment described above, since the toner is applied only to a part of the photoreceptor, the amount of toner consumed can be significantly reduced. For example, the toner is applied to the entire surface of the photoreceptor to prevent the occurrence of roller marks. Approximately 5g of toner was required for
When using the above-mentioned sequence, this amount could be kept below 1 g.

Although the present invention has been described above using an amorphous silicon photoreceptor, it is easy to understand that the present invention is not limited thereto and can be applied to photoconductive layers of other types. Probably.

(Effects of the Invention) Since the present invention has the configuration described above, it is possible to prevent roller marks caused by pressure contact with the image bearing member during elastic cleaning with a very small amount of toner, and to maintain high quality images over a long period of time. It is effective to obtain stable results.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing the main parts of a copying machine to which the present invention is applied. FIG. 2 is a sequence diagram showing a case in which toner is applied to an image carrier using only a developing bias, and FIG. 3 is a sequence diagram showing a case in which a photosensitive layer is charged and then toner is applied thereto by a developing bias. No. 1: Photoconductor, 3: Charger, 5: Developing device, 7: Φ: Transfer charger, 9: Cleaning device,

Claims (1)

[Claims] In a cleaning device equipped with an elastic cleaning roller that rubs against a traveling image carrier, a toner layer is formed on a part of the surface of the image carrier and near the pressure contact portion with the roller during preliminary rotation of the image carrier before copying is possible. A cleaning device equipped with a means for cleaning.