JPH0785189B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus utilizing an electrostatic recording process, such as an electrostatic copying machine and a printer.

(Problems to be Solved by Prior Art) In a known image forming apparatus, which repeats the process of forming a transferable toner image on the surface of an image carrier and transferring the toner image onto a sheet-like transfer material mainly composed of paper, It is necessary to remove the residual toner remaining on the surface of the image carrier without transferring to the transfer material at the transfer site every time the transfer is performed.For this reason, the structure is simple, compact and compact, and the toner removing function is excellent. Therefore, as a cleaning means, a cleaning blade made of an elastic material such as rubber is widely used.

However, in general, in the residual toner, in addition to the toner, there are various foreign substances such as fine paper powder, rosin deposited from this, deposits such as talc, corona products due to the presence of the high-pressure member in the apparatus, If these foreign matters adhere to the image bearing member, it is difficult to remove them with a cleaning blade, and the resistance decreases in a high humidity environment, which may lead to deterioration of image quality such as image deletion.

In order to avoid such drawbacks, in recent years, a cleaning roller made of an elastic material such as silicon rubber is rubbed against an image carrier by pressure, and further, a fine abrasive in the toner is added to the surface of the image carrier. Something like polishing a layer has already been proposed.

Such materials have been effective for selenium, cadmium sulfide, OPC, etc., which have been widely used as materials for the photosensitive layer, but have recently been used for awards. It was not very effective for hard photosensitive layers such as amorphous silicon semiconductors.

The present invention has been made in order to cope with such a situation, and provides an image forming apparatus capable of always obtaining a stable cleaning action for a long period regardless of the photosensitive layer and contributing to obtaining a good image. That is the purpose.

(2) Configuration of the Invention (Technical Means for Solving the Problem and Its Action) In order to achieve the above-mentioned object, in the present invention, a toner image is formed on the surface of an image bearing member using the toner, and the toner image is formed. In the image forming apparatus that removes the residual toner remaining on the surface of the image carrier from the surface of the image carrier after transferring the toner to the transfer material, the toner image remains on the surface of the image carrier after transferring the toner image to the transfer material. An elastic cleaning roller provided so as to slide on the surface of the image carrier in order to remove the residual toner from the surface of the image carrier, and a downstream side of the elastic cleaning roller in the rotation direction of the image carrier. In order to scrape off the residual toner remaining on the surface of the image carrier from the surface of the image carrier, a cleaning blade provided so as to contact the surface of the image carrier is provided. The abrasive mixed in the toner for polishing the image bearing member and the elastic cleaning roller are charged to have opposite polarities, and the toner and the elastic cleaning roller are charged to have the same polarity as each other. It is characterized by being configured.

By configuring in this way, with respect to the image carrier,
Stable and good polishing and cleaning performance can be maintained, and high quality images can be obtained.

(Description of Embodiments) The accompanying drawings are side views of essential parts showing an embodiment in which the present invention is applied to a copying machine having a rotating cylindrical photosensitive member that rotates in the direction of arrow A. A cleaning device 2 is arranged in parallel with the longitudinal direction of the body.

A cleaning blade 3 is attached to the cleaning device 2, and one edge of one end of the cleaning blade 3 comes into pressure contact with the surface of the photoconductor and does not contribute to transfer at a transfer position (not shown). Some residual toner shall be removed.

Seen in the running direction of the photoreceptor, on the upstream side of the blade,
A cleaning roller 4 made of an elastic material such as silicone rubber or urethane rubber is pressed against the photoconductor and rubs the photoconductor at a relative speed by an appropriate drive source.

Toner and other foreign matter on the surface of the photoconductor are removed by these cleaning rollers and cleaning blades, and as the rollers rotate, they are sequentially conveyed to the left in the drawing, and are removed by the scraper 5 to be stored in the storage section in the cleaning device. Further, if necessary, it is discharged to the outside by the conveying screw 6.

Incidentally, as is well known, it is needless to say that members required for image formation such as a primary charging device, an image signal giving means, a developing device and a transfer charging device are arranged around the photoconductor 1. , They are not directly related to the present invention, so they are all omitted.

An example of an experiment performed by the following specifications using a copying machine equipped with a cleaning device having such a configuration will be described.

(Experimental example) Photoreceptor: An aluminum cylinder substrate with a diameter of 180 mm was used to form an amorphous silicon layer with a thickness of 30 μ on the surface, and a Sic film with a thickness of 5000 Å was formed on the surface, and the peripheral speed was 445 mm.
It was run at / sec.

Elastic cleaning roller; core metal diameter: 10 mm, elastic outer layer 4a; LT
V Silicon rubber having a thickness of 1 mm, elastic inner layer 4b; silicon sponge, having an outer diameter of 20 mm was rubbed on the photoreceptor at a peripheral speed of 270 mm / sec.

The silicone rubber hardness of the roller was JIS A 40 °, the hardness of the entire roller was Asker C 34 °, and the pressing force on the photoconductor was 33 g / ce (nip width 2.5 mm).

Scraper: The edge of a stainless steel plate having a thickness of 50 μ was brought into contact with the roller.

Toner; Binder resin 100 parts polyester, 60 parts magnetic material 2 parts charge control agent 3 parts release agent In addition to 0.4% silica and 3% strontium titanate as external additives.

Use the photoconductor (positive charging), cleaning roller, and toner (negative charging) as described above to create a low-humidity environment (15
℃, 10% RH), normal environment (23 ℃, 60% RH) and high humidity environment (32.5 ℃, 85% RH) 100,000 sheets paper feed test was performed, all good images were obtained It was

(Comparative Example 1) A similar paper passing test was conducted using the above-described configuration in which the cleaning roller was removed (a scooping sheet was attached to the roller-corresponding portion to prevent toner overflow). Black streaks occurred in the image.

Observation of the photoconductor revealed that strontium titanate passed through the cleaning blade, and because it was insulative, it was charged during the primary charging and then developed at the development site without being neutralized, resulting in deterioration of image quality. It turned out to be a thing.

In a high-humidity environment, image deletion occurred in all cases, and this situation was not recovered even when the surface temperature of the photoconductor was heated to 50 ° C.

(Comparative Example 2) A similar test was performed using the toner obtained by removing strontium titanate from the above-described example.

As a result, some image deletion occurred in a high-humidity environment.
The image deletion disappeared when kept at ℃.

Therefore, the paper passing test was continued, but after passing about 50,000 sheets, rain-like black spots appeared on the image.

When the photoconductor was observed, toner fusion was observed in the form of rain.

Further, in this case, the image density was low in all the environments, and the fog was observed in the image. Especially, in the high humidity environment, the D _max was decreased, and in the low humidity environment, the fog was large.

What caused this situation is that the toner is negatively charged by contact with the developing sleeve and strontium titanate at the developing site, but strontium titanate (charges positively by contact with the toner). It is considered that since it is difficult to maintain proper tribo due to the removal of the toner, the chances of contact between the toners are increased, the toner having unstable polarity is increased, and the fog is increased.

On the other hand, in the case of the embodiment, the cleaning roller which is rubbed in pressure contact with the photoreceptor is negatively charged (about -1500 to 4000 V) and the strontium titanate is positively charged, so that the strontium titanate in the residual toner is charged. The particles are attracted to and maintain this state in the pressure contact nip portion with the cleaning roller, and this acts as an abrasive during sliding of the photoreceptor and the cleaning roller to effectively remove foreign matter on the surface of the photoreceptor. This will contribute to the prevention of image deletion and fog.

Further, since the strontium titanate is positively adsorbed by the cleaning roller and does not reach the cleaning blade, only the toner is mainly present on the blade and the fluidity of the toner is maintained well, and the cleaning is performed. It is possible to prevent defects and blade turning.

In the above-described experimental example, 300,000 sheets of paper were passed under each of the low-humidity, normal, and high-humidity environments. Up to the end, high-quality images with high density were obtained without fog.

At this time, the scraped amount of the SiC film on the surface of the photoconductor is also 2250Å
However, it was still in a condition that it could be used sufficiently.

FIG. 2 shows a cleaning device having a configuration basically similar to that described above. As a configuration of the cleaning roller, as shown in FIG.
A magnetic roller 40c was formed on the outer circumference of the roller, and a silicon sponge layer 40b was formed on the outer side of the magnetic roller 40c, and an LTV silicon rubber layer having a thickness of 0.5 mm was formed on the outermost layer.

The magnetic flux density on the surface of the roller was 200 gauss, and a 100-μm-thick stainless scraper was abutted against the roller and used.

When such a roller was used to pass 100,000 sheets of paper in each of the low-humidity, normal and high-humidity environments described above, a very good image was obtained, and the SiC film scraped amount was 1400Å. Even better results were obtained.

This is because when the scraper is brought into contact with the cleaning roller in an abdominal contact shape, a coating film of a mixture of toner and strontium titanate is formed on the roller surface, and the SiC film on the photoconductor surface is relatively softly slid. It is thought to be because they rub.

Although the embodiment in which the present invention is applied to the copying machine has been described above, it is easily understood that the present invention is not limited to this and can be applied to other image forming apparatuses.

(3) Effects of the Invention Since the present invention has the configuration described above, it is possible to effectively remove foreign matter other than toner existing on the surface of an image bearing member regardless of the environment. Yes, it is very useful for obtaining good quality images.

That is, according to the present invention, the abrasive mixed in the toner for polishing the image bearing member and the elastic cleaning roller are charged to have opposite polarities, and the toner and the elastic cleaning roller are charged to have the same polarity. With this configuration, the abrasives are attracted to each other and maintained on the surface of the elastic cleaning roller, so that the effect of polishing the surface of the image carrier can be improved. In addition, the toner repels the surface of the elastic cleaning roller and is not maintained on the surface of the elastic cleaning roller. By acting as a lubricant with the body surface, it is possible to improve the cleaning action and prevent the cleaning blade from turning over.

Therefore, according to the present invention, in a configuration in which the cleaning roller and the cleaning blade are used together to clean the image carrier, each performance can be significantly improved and maintained.

[Brief description of drawings]

FIG. 1 is a side view of essential parts showing an embodiment in which the present invention is applied to a copying machine, and FIG. 2 is an example showing another cleaning roller. 1 ... photoreceptor, 2 ... cleaning device, 3 ... cleaning blade, 4,40 ... elastic cleaning roller, 5
...... Scraper,

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 61-156272 (JP, A) JP-A 60-107677 (JP, A) JP-A 60-221784 (JP, A) JP-A 55- 57874 (JP, A)

Claims (1)

[Claims] 1. A toner image is formed on the surface of an image carrier using toner, the toner image is transferred to a transfer material, and the residual toner remaining on the surface of the image carrier is removed from the surface of the image carrier. In the image forming apparatus, after the toner image is transferred to the transfer material, in order to remove the residual toner remaining on the surface of the image carrier from the surface of the image carrier, the surface of the image carrier is rubbed. An elastic cleaning roller provided and the image carrier for scraping off residual toner remaining on the surface of the image carrier from the surface of the image carrier on the downstream side of the elastic cleaning roller in the rotation direction of the image carrier. A cleaning blade provided so as to come into contact with the surface of the body; and an abrasive mixed in the toner for polishing the image carrier and the elastic cleaning roller. The image forming apparatus is characterized in that the toner and the elastic cleaning roller are charged with opposite polarities, and that the toner and the elastic cleaning roller are charged with the same polarity.