JPH01156778A - Developing device - Google Patents

Abstract

PURPOSE:To perform high-picture-quality development which is stable for a long period by providing a rotatable metallic sleeve which conveys a developer and a scraper which scrapes off a developer, and forming the scraper of a metal of different kind from the metallic sleeve. CONSTITUTION:A developer control member 4 controls the flow rate of a developer sticking on the sleeve 2 to perform excellent electrostatic charging, and the scraper 5 scrapes off a developer which still remains after an exposure latent image on a photosensitive body 1 is developed reversely. The scraper 5 needs to be brought into strong contact with the sleeve so as to increase the agitation effect of the upper and lower layers of the sleeve 2 by removing a filming material. Therefore, when the material of the same kind with the sleeve is used for the scraper, the surface of the sleeve 2 is flawed to generate an image defect. On the other hand, when a scraper 5 made of phosphor bronze is used in combination with a sleeve 2 of, for example, stainless steel, wear is small and flawing is suppressed. Consequently, high picture quality which is stable for a long period is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a developing device for an electrophotographic copying machine or the like.

BACKGROUND ART Conventionally, as a method for visualizing an electrostatic latent image, for example, in the dry developing process of an electrophotographic device, a plurality of magnetic poles are arranged in a cylindrical shape, and a non-magnetic sleeve is placed close to the outer circumference of the magnetic pole. By rotating, the developer is transported from the developer reservoir to a developing pole located opposite to a latent image carrier such as a photoreceptor, and the developer is made to stand up like a brush at this developing magnetic pole to carry the latent image. A sleeve development method is widely used in which development is performed by lightly rubbing an electrostatic latent image on a body. In developing devices that employ the above-mentioned sleeve development method, a two-component development method using a two-component developer containing a magnetic carrier and toner, or a one-component development method using a one-component developer consisting only of toner, etc. are commonly used. It is used in many ways.

In all three methods, the distance between the developer regulating member and the sleeve (hereinafter referred to as BSD) and the distance between the photoreceptor and the sleeve (hereinafter referred to as D
It is called SD. ), and the set value of the developing bias voltage is important. Also, the above-mentioned BSD.

Comparing the two-component development method and the one-component development method regarding the three elements of DSD and development bias, -B for boat fishing
Regarding SD and DSD, -component development method is narrower,
Furthermore, the developing bias voltage is set higher in the one-component developing method. This is because toner in a two-component development method is easily charged by friction with a carrier, whereas in a widely used one-component development method using an insulating component toner, it is difficult to be charged by friction. For this reason, in the -component development method, the BSD is narrowed to make it easier to charge the toner flowing out from the developer regulating member, and the toner is charged by using not only DC as the development bias (a power supply with AC superimposed on it). In many cases, efforts are being made to ensure quantity and maintain image quality.

Problems to be Solved by the Invention The one-component developing method has many advantages over the two-component developing method, such as eliminating the need for toner density control and making the apparatus more compact.

However, as mentioned above, when BSD and DSD are set narrowly,
Furthermore, when AC is superimposed on the developing bias, the DSD becomes too narrow relative to the applied developing bias, and sometimes electrical leakage occurs between the sleeve and the photoreceptor, causing image defects. This image defect is likely to occur as a white spot in a solid black image, and as a black circle in a solid white image. In order to prevent the above image defects,
It is necessary to prevent electrical leakage between the sleeve and the photoreceptor, but if the BSD or DSD is widened or the developing bias voltage is lowered for this reason, there are problems such as deterioration of image quality.

In view of the above problems, the present invention has been developed to prevent image defects caused by electrical leakage between the sleeve and the photoreceptor, and to develop an electrostatic latent image by satisfactorily charging an insulating component developer. It provides equipment.

Means for Solving the Problems In order to solve the above problems, the developing device of the present invention includes a rotatable metal sleeve for conveying developer, and a developer regulating member for regulating the amount of developer flowing out. , a scraper for scraping off the developer is provided, and the material of the scraper is a metal different from that of the metal sleeve.

Operation The present invention, with the above-described configuration, prevents electrical leakage between the sleeve and the photoreceptor and performs development without image defects even if BSD and DSD are set narrowly.

EXAMPLE A developing device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of essential parts of a developing device in a first embodiment of the present invention.

In the figure, 1 is a photoreceptor, 2 is a non-magnetic sleeve, and 3 is a photoreceptor.
a, 3b, 3c, 3d, and 3e are fixed magnets, 4 is a developer regulating member, 6 is a scraper, 6 is a stirring blade, 7 is a developing bias power source, 8 is a container, 9 is a cover, and 1o is a developer.

The operation of the developing device constructed as described above will be described below with reference to FIG. The drum-shaped photoreceptor 1 is an organic photoreceptor, and rotates at a speed of 120 mm/sec in the direction of the arrow in the figure. Sleeve 2 is made of non-magnetic stainless steel processed to have a surface roughness of 0.5μ, and has a diameter of 115 mm in the direction of the arrow shown in the figure.
It rotates at a speed of rpm. Fixed magnets 3a, 3b within sleeve 2.

The surface magnetic flux density of 3c, 3d and 30 is 7oOG~900G
It is. The developer regulating member 4 is made of a non-magnetic material made of stainless steel and is adjustably installed at a position facing the fixed magnet 3a while maintaining a gap of 0.15 mm from the sleeve 2. The scraper 6 is made of thin bronze with a thickness of 0.1 SrnM and is held in contact with the sleeve 2, and has the function of scraping off the developer on the sleeve 2. The developing gap distance between the photoreceptor 1 and the sleeve 2 is 0.3 km, and an output in which AC and DC voltages are superimposed is applied to the sleeve 2 from the developing bias power supply 7, and the AC output is 1.5 KHz. 70
0 V (rmS), and the DC output is -550 V.

The developer 10 in the container 8 has an average particle size of 10. It is an insulating component developer made of synthetic resin and magnetic powder as basic materials and externally added with silica.

The photoreceptor 1 is first charged in a negative manner (e.g., negative) by a DC corona discharger (not shown), and then subjected to a light image projection using a laser beam or the like (not shown). produces a high-contrast electrostatic image that corresponds to the image information. On the other hand, the developer 10 in the developer reservoir is attracted to the sleeve by the magnetic force of the fixed magnet in the sleeve 2, and is conveyed in the direction of rotation of the sleeve 2. On the way, the developer 10 is regulated in flow by the developer regulating member 4, and the operating height is increased. A uniform layer of developer is formed on the sleeve. Due to the above-mentioned action and the action of the developing bias, the developer is well charged (eg, negatively charged).

This developer layer is conveyed by the sleeve 2 and fixed magnet 3
The electrostatic latent image on the photoreceptor 1 is reversely developed at the position b, and the remaining toner is further conveyed, scraped off by a scraper 6, conveyed to a developer reservoir, and collected.

- In the development method using a one-component developer for boat fishing, BSD, D
In many cases, the SD is set narrowly, and sometimes electrical leakage occurs between the sleeve and the photoreceptor, resulting in image defects. One way to prevent electrical leakage is to cover the sleeve surface with an insulating film, but the volume resistance is 10.
Even just covering it with a material having a resistance of about 5 Ω caused a decrease in image density and was not an effective means. Therefore, in the developing device according to this embodiment, it was effective to reduce the surface roughness of the sleeve 20 as a means for preventing the occurrence of electrical leakage. It was difficult to prevent electrical leakage when the surface roughness of the sleeve 2 was set to 2.0a or higher;
When the thickness is less than μ, the effect of preventing electrical leakage can be seen, and preferably it is less than 0.6μ.

Due to repeated image reproduction, the developer tends to generate layers with different amounts of charge on the upper and lower layers of the sleeve, which can sometimes lead to filming on the sleeve, resulting in inconveniences such as a decrease in image density. may occur. In order to prevent this kind of phenomenon, the scraper 6 should be placed in the sleeve 2.
It is installed in contact with the sleeve to scrape off the collected developer, remove filming substances, and enhance the stirring effect of the developer in the upper and lower layers of the sleeve. In order to have a sufficient scraper effect as described above, it is necessary to bring the scraper 5 into strong contact with the sleeve 2. As described above, the scraper 5 is required to have appropriate elasticity and strength, as well as compactness and cost efficiency. Therefore, stainless steel, which is often used as a part of a scraper, is the most suitable material. However, if the same type of material as the sleeve material is used for the scraper, the surface of the sleeve is likely to be damaged, and as a result, electrical leakage between the sleeve and the photoreceptor is likely to occur, resulting in image defects. However, sleeves and dissimilar metals (e.g. phosphor bronze)
If you use this scraper, there will be less wear on the sleeve and it will slide better and there will be less scraping. In this example, JISSUS316 was used as the sleeve material and JIS C5210P...3AH was used as the scraper material, but the sleeve was hardly scratched and exhibited good scraper function, resulting in good image quality with no image defects over a long period of time. I was able to maintain it.

In the developing method using the developing device of this embodiment, contact development is performed using an insulating component developer, but non-contact development (for example, a magnetic developer regulating member is used when a magnetic component developer is used) is used. It is also effective in a non-contact developing method using a non-contact developing method using a non-magnetic component developer, or a non-contact developing method using an elastic developer regulating member made of rubber or metal using a non-magnetic component developer.

Effects of the Invention As detailed above, according to the developing device according to the present invention, -
By using a component developer and a sleeve with a small surface roughness, it is possible to prevent electrical leakage between the sleeve and the photoconductor, maintain good charging of the developer, and easily produce high-quality images without defective images. It becomes possible to obtain image quality.

Further, by using a scraper material different from the sleeve material, the surface of the sleeve can be protected for a long period of time, so that stable high-quality image development can be performed for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of a developing device in an embodiment of the present invention. 1...Photoreceptor, 2...Sleeve, 3a
. 3b, 3c, 3d, 3e...Fixed magnet, 4...
...Developer regulating member, 5... Soufflé soba
, 6... Stirring blade, 7... Development bias, 8... Container, 9... Cover, 10
...Developer.

Claims (3)

[Claims] (1) It is equipped with a rotatable metal sleeve for conveying developer, a developer regulating member for regulating the amount of developer flowing out, and a scraper for scraping off the developer, and the scraper is not a metal sleeve. A developing device characterized by being made of different metals. (2) The developing device according to claim 1, wherein the scraper is made of phosphor bronze. (3) The developing device according to claim 1 or 2, wherein the metal sleeve has a surface roughness of 1.0 μm or less.