JPS6383784A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory image by providing an elastic cleaning roller sliding to an image holding body as a cleaning means and electrifying a substance having a grinding function mixed into a toner and an elastic cleaning roller to a reverse polarity mutually. CONSTITUTION:An elastic cleaning roller 4 is used by a cleaning means, abrasives, for example, silica, strontium titanate, etc., are contained into a toner, and the cleaning roller 4 and the abrasive are electrified to the reverse polarity by the friction. The toner of the sensitizing body front surface and other foreign matters are removed by these cleaning roller 4 and cleaning brade 3, conveyed successively in the left direction accompanying the rotation of the roller, removed by a scraper 5, and discharged from the storage part in a cleaning device to the external part by a conveying screw 6. Thus, a high quality image can be always obtained.

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 electrostatic recording process, such as an electrostatic copying machine and a printer thereof.

(Prior art and problems to be solved) In a well-known image forming apparatus, a process of forming a transferable toner image on the surface of an image carrier and transferring it to a sheet-like transfer material mainly made of paper is repeated. For each transfer, it is necessary to remove the residual toner that does not transfer to the transfer material and remains on the surface of the image carrier at the transfer site.For this reason, it has traditionally been easy to configure, small and compact, and has an excellent toner removal function. Therefore, as cleaning means, cleaning blades made of elastic materials such as rubber are widely used.

However, in general, residual toner contains various foreign substances other than toner, such as fine paper powder, precipitates such as rosin and talc, and corona products due to the presence of high-pressure parts in the device. When these foreign substances adhere to the image bearing member, it is not only difficult to remove them with a cleaning blade, but also there is a risk that the resistance decreases in a high humidity environment, resulting in deterioration of image quality such as image deletion.

In order to avoid such drawbacks, recently, a cleaning roller made of an elastic material such as silicone rubber is brought into contact with the image carrier, and fine particles of abrasive material are added to the toner to make the surface of the image carrier photosensitive. Something like polishing the layers has already been proposed.

These materials have been effective for selenium, cadmium sulfide, OPC, etc., which have traditionally been widely used as materials for photosensitive layers, but they have recently become more popular, such as amorphous silicon semiconductors. It was not very effective for hard photosensitive layers.

The present invention has been made in order to cope with such a situation, and provides an image forming apparatus that can always provide a stable cleaning effect over a long period of time, regardless of the type of photosensitive layer, and that contributes to obtaining good images. The purpose is to

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides an image carrier, a means for forming an electrostatic latent image on the image carrier, and a means for forming an electrostatic latent image on the image carrier. In an image forming apparatus equipped with a means for developing a toner image, a means for transferring a developed toner image onto a transfer material, a cleaning means for removing residual toner, etc., an elastic cleaning roller is used as the cleaning means, and an abrasive material is applied to the toner. In addition to containing
The present invention is characterized in that the cleaning roller and the abrasive material are configured to be charged to opposite polarities due to friction.

With this configuration, stable and good polishing and cleaning functions can be expected at all times, and high-quality images can be obtained, regardless of the configuration of the surface of the image carrier.

(Description of the Embodiment) The attached drawing is a side view of essential parts showing an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical photoreceptor that rotates in the direction of arrow A. A cleaning device 2 is arranged parallel to the longitudinal direction of the body.

A cleaning blade 3 is attached to the cleaning device 2, and one edge of the cleaning blade 3 is in pressure contact with the surface of the photoreceptor at a transfer position (not shown), and does not contribute to the transfer, but mainly acts on the surface of the photoreceptor. Some residual toner shall be removed.

On the upstream side of the blade as seen in the traveling direction of the photoreceptor,
A cleaning roller 4 made of an elastic material such as silicone rubber or urethane rubber is in pressure contact with the photoreceptor, and is rubbed against the photoreceptor at a relative speed by an appropriate drive source.

Toner and other foreign substances on the surface of the photoconductor are removed by the cleaning roller and the cleaning blade, and as the rollers rotate, they are sequentially conveyed to the left in the figure, and are removed by the scraper 5 and stored in the storage section in the cleaning device. Once the material has reached the desired state, it is discharged to the outside by the conveying screw 6, if necessary.

It should be noted that, as is well known, around the photoreceptor 1 there are of course the members necessary for image formation such as a primary charger, an image signal applying means, a developing device, and a transfer charger. , all of which are omitted since they are not directly related to the present invention.

An example of an experiment conducted using a copying machine equipped with a cleaning device configured as described above and with the following specifications will be described.

(Experiment example) Photoreceptor: An amorphous silicon layer with a thickness of 30 μl was formed on the surface of an aluminum cylinder base with a diameter of 180 mm, and a SiC film with a thickness of 500 OA was further formed on the surface.
It was run at 45III/SeC.

Elastic Cleaner: Core metal diameter: 10 mm, elastic outer layer 4 roller a; LTV silicone rubber thickness 1 mm, elastic inner layer 4b: Silicone sponge, outer diameter 20 mm, is slid and rubbed on the photoreceptor at a circumferential speed of 270 mm/sec. Ta.

The silicone rubber hardness of the roller is JISA 40', the hardness of the entire roller is Asker C34', the pressing force on the photoreceptor is 33 g/c+*, and the tongue width is 2.5
mm).

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

Toner; Binder resin: 100 parts of polyester, Magnetic material 60 parts Charge control agent 2 parts Mold release agent 3 parts In addition, as an external additive, silica 0.4 %, strontium titanate 3% added.

Using the photoreceptor (positively charged), cleaning roller, and toner (negatively charged) as described above, a low humidity environment (15
We conducted a 100,000 sheet feeding test under normal conditions (23°C, 60% RH) and high humidity environments (32.5°C, 85% RH), but all results showed good images. Obtained.

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

When observing the photoreceptor, it was found that strontium titanate passed through the cleaning blade, and since this material is insulating, it was charged during the next charging, and was then developed at the developing area without being neutralized, resulting in deterioration of image quality. It turned out that it was.

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

(Comparative Example 2) A similar test was performed using the same toner as in the above-described experimental example from which strontium titanate was removed.

As a result, some image blurring occurred in a high-humidity environment, so a planar heating element was attached to the photoreceptor to increase its surface temperature.
When the temperature was maintained at 8°C, image blur disappeared.

So we continued the paper feeding test, but after about 50,000 sheets, raindrop-like black spots appeared on the images.

When the photoreceptor was observed, it was found that the toner was fused in a rain-like pattern.

Further, in this case, the image density was low in all environments, and fogging was observed in the image, and in particular, a decrease in D was observed in a high-temperature environment, and fogging was large in a low-humidity environment.

The reason for this situation is that the toner becomes negatively charged when it comes into contact with the developing sleeve and strontium titanate at the development site, but strontium titanate (which becomes positively charged when it comes into contact with the toner) ) was removed, it became difficult to maintain a proper tripo, and the chances of contact between toners increased, resulting in an increase in the amount of toner with unstable polarity and increased fogging.

On the other hand, in the case of the experimental example, the cleaning roller that presses and rubs against the photoreceptor has a negative charge of -1,500 to 40
00V), strontium titanate is positively charged, so the strontium titanate in the residual toner is attracted to the cleaning roller at the pressure nip and maintains this state. When the cleaning roller rubs against the photoreceptor, it acts as an abrasive and effectively removes foreign matter from the surface of the photoreceptor, contributing to preventing image deletion and fogging.

Furthermore, since the titanium-ugly strontium is actively adsorbed by the cleaning roller and does not reach the cleaning blade, the blade mainly contains only toner, maintaining good toner fluidity and cleaning. It is possible to prevent defects and blade curling from occurring.

In the above-mentioned experimental example, a total of 300,000 sheets were passed under each environment of low humidity, normal humidity, and high humidity, and high-quality, high-density images with no fog were obtained until the end.

At this time, the amount of abrasion of the SiC film on the surface layer of the photoreceptor was also 22
It was still in a usable condition at 50A.

FIG. 2 shows a cleaning device having basically the same configuration as the one described above, and the cleaning roller has a stainless steel core material 40 as shown in the figure.
A magnetic roller 40C is formed on the outer periphery of d, a silicon sponge layer 40b is formed on the outside thereof, and an LT with a thickness of 0.5 mm is formed as the outermost layer.
A roller having an outer diameter of 20φ and having a V silicone rubber layer formed thereon was used.

The magnetic flux density on the roller surface was 200 Gauss, and a stainless steel scraper having a thickness of 100 JL was brought into contact with this roller in a padded manner.

Using such a roller, when 100,000 sheets were passed under each of the low humidity, normal humidity, and high humidity environments described above, extremely high quality images were obtained, and the amount of abrasion of the SiC film was 140 OA, which was the same as in the experimental example described above. Even better results were obtained.

This is because by bringing the scraper into contact with the cleaning roller, a film of a mixture of toner and strontium titanate is formed on the surface of the roller, and the SiC film on the surface of the photoreceptor is relatively softly rubbed. This is thought to be due to rubbing.

Although an embodiment in which the present invention is applied to a copying machine has been described above, it will be 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 present on the surface of the image carrier regardless of the environment. , which greatly contributes to obtaining high-quality images.

[Brief explanation of the drawing]

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 a cleaning roller of the same function.

Claims (1)

[Scope of Claims] An image forming apparatus comprising a cleaning means for forming a transferable toner image on the surface of an image carrier and removing residual toner on the surface of the image carrier after transferring the image to a transfer material, An image forming apparatus characterized in that the cleaning means includes an elastic cleaning roller that rubs against the image bearing member, and the elastic cleaning roller and the substance having an abrasive function mixed in the toner are charged to opposite polarities. .