JPS58120281A - Developing device - Google Patents

Abstract

PURPOSE:To improve the picture quality, by providing the first magnet roll, which gives a low frictional charge to a developer to apply a thin layer to the developer in, and the second magnet roll which gives a high frictional charge to the developer transferred from the first magnet roll. CONSTITUTION:The first magnet roll 6 consists of a nonmagnetic sleeve 8 which has a magnet pole 7 internally. The second magnet roll 9 consists of a nonmagnetic sleeve 11 which has a magnetic pole 10 internally. The first magnet roll 6 is so constituted that a low frictional charge is given to a toner by friction to the sleeve 8. The second magnet roll 9 is so constituted that a high frictional charge caused by friction to the sleeve is given to the toner transferred from the first magnet roll. By this constitution, the variance of application of the toner is hardly caused on the sleeve to obtain an excellent picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing a latent image on a latent image carrier using a one-component magnetic developer, and particularly a developing device for developing a latent image on a latent image carrier using a one-component magnetic developer. The present invention relates to a developing device that holds a developer on a magnetic roll consisting of a magnetic roll, and performs development by bringing the magnetic roll into contact with or close to the latent image holding member.

Developing devices using one-component magnetic developer include those that use conductive toner and those that use non-conductive toner, but since the former is conductive toner, it cannot be visualized on the latent image carrier in high humidity. The toner image has poor transferability when transferred to a transfer material, and is unsuitable for copying devices using plain paper. - In the latter case, there are no transfer defects at high humidity and the image quality is good. However, because it is necessary to generate an electric charge on the toner by applying frictional electrification on a single sleeve,
Since it is necessary to maintain a uniform electric charge in the toner and also to maintain a uniform layer of toner on the sleeve, it is necessary to coat the sleeve surface with a thin layer of about 50 to 400 μm.

A magnetic grade is provided facing the magnet roll, and the gap between the magnetic blade and the sleeve is set to 100 to 500 μm.
Obtained by fleas.

In such a developing method, it is generally known that the larger the toner charge, the better the image quality.

However, when trying to impart a large triboelectric charge to the toner using the above-described developing method, the thin layer of toner coating on the sleeve becomes uneven. This is because the charge of the toner increases, and the adhesion force with the sleeve increases, which causes it to strongly adsorb to the sleeve surface, and even if you try to coat it thinly with a magnetic blade, it cannot be controlled by the magnetic blade. This is because a toner layer is formed.The purpose of the present invention is to eliminate uneven toner coating, give a stable charge to the toner, and increase the charge held by the toner when forming a thin layer coating on the sleeve. There is a particular thing. Furthermore, an object of the present invention is to improve development and transfer properties at high temperatures and to improve image quality.

For this purpose, the present invention provides a first method for applying a thin layer of a developer by imparting a low triboelectric charge to the developer through friction with a sleeve in a developing device using a one-component magnetic developer of the above type. Due to the friction between the magnet roll and the sleeve, the first
and a second magnet roll that imparts a high triboelectric charge to the developer transferred from the magnet roll, and the second magnet roll is disposed in contact with or in close proximity to the latent image holder. do. That is, in the present invention, in a developing device using a -component magnetic developer, two magnetic rolls are combined so that one roll measures, collects, and stirs the developer, and the other roll performs development. be.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an example of a developing device according to the present invention.

In the figure, l indicates a developing device, and 2 indicates a latent image holding member, that is, a photosensitive drum. The developing device 1 includes a container 3 for replenishing developer and a magnetic blade 4 for measuring the developer, and a one-component magnetic developer (hereinafter referred to as toner) 5 for replenishment is stored in the container 3. 6 indicates a first magnet roll, which consists of a non-magnetic sleeve 8 with a magnetic pole 7 inside. 9 is the second
1 shows a magnet roll consisting of a non-magnetic sleeve 11 with magnetic poles 10 inside. The first magnet roll 6 is configured and configured to apply a thin layer of toner by imparting a low triboelectric charge to the toner through friction with the sleeve, and the second magnet roll 9 is configured to apply a thin layer of toner by applying a low triboelectric charge to the toner through friction with the sleeve. roll 6
The second magnetic roll 9 is arranged in contact with or in close proximity to the latent image carrier, that is, the photosensitive drum 2, and is configured to impart a high triboelectric charge to the toner transferred from the toner.

In the above-mentioned developing device, toner 5 is stored in a container 3, measured by a magnetic blade 4, and is repeatedly frictionally charged with the sleeve surface by a first magnetic roll 6, and then transported as shown at 12. The toner is transferred to the second magnet roll 9 and reaches the development area 13 while being repeatedly charged by friction with the sleeve surface.

The toner comes into contact with or comes close to the latent image holding member 2, and the toner is triboelectrically charged and the latent image on the latent image holding member 2 is developed by nine charges.The illustrated embodiment shows a so-called jumping development method. , the sleeve lla of the second magnet roll is close to the latent image holding member 2, and the toner moves from =m of the sleeve 11 to the latent image holding member 2 according to the latent image. As shown in the figure, AC bias voltage 1
4 is applied, making it easier for the above-mentioned toner to move. Further, the toner is transferred from the sleeve 8 of the first developing roller to the sleeve 11 of the second developing roller.
To coat the surface of the toner thinly with toner, the same method as the above-mentioned shampooing development is used, and a/guinea pressure 15 as shown in FIG. 2 is applied.

When coating a toner thinly, it is necessary not to increase the charge of the toner more than necessary, and at the time of development, it is necessary to make the charge of the toner sufficiently large.

According to the present invention, the first magnet roll 6 is configured to impart a low triboelectric charge to the toner through friction with the sleeve 8. For this purpose, the surface of the sleeve 8 of the first magnetic roll is made of stainless steel, steel, aluminum, anodized aluminum, or a similar material, such as stainless steel, steel, aluminum, anodized aluminum, etc., so as not to impart too much triboelectric charge to the toner while the toner is being conveyed by the surface of the sleeve 8. It is composed of chrome-plated gold maple or materials relatively similar to the triboelectric series such as polyethylene, polysterene, and polyurethane. That is, the sleeve 8 of the first magnet roll 6 is configured to coat the toner in a thin layer rather than imparting a charge to the toner.

Further, the second magnet roll 9 is configured to impart a high triboelectric charge to the toner transferred from the first magnet roll by friction with the sleeve. For this purpose, the surface of the sleeve 11 is coated with a material that imparts a large amount of triboelectric charge to the toner, such as silicone resin or glass for negative toner, or Teflon for Bottonner, in order to be suitable for high-quality image development.

In this way, the present invention works by coating the surfaces of the sleeve 8 and the IJ-F 11 with materials of different charging series. When a toner is thinly applied to the sleeve surface to a thickness of 50 to 1000 μm in a developing method that generates electric charges, developing and rolling properties are improved and excellent image quality can be obtained. Particularly in low-humidity environments where frictional electrification generates a large amount of charge, the occurrence of unevenness in sleep mode can be suppressed.

This will be explained with reference to FIG. Figure 3 shows the toner umbrella charge value generated by the rotation of the sleeve after toner has been thinly applied onto the sleeve, with the horizontal axis showing the number of rotations of the sleeve and the vertical axis showing the frictional charge value. As shown in Figure 0, the triboelectric charge value of the toner gradually increases as the sleeve rotates, and finally reaches saturation.A in the figure indicates the triboelectric charge in a normal humidity environment, and B in the figure
shows triboelectric charges in a low-humidity environment.

The lower the humidity, the faster the toner rises, and the lower the humidity, the greater the triboelectric charge of the toner in the first rotation, and therefore the toner is more likely to be applied unevenly on the sleeve. However, S1
7 From the trap of applying the treatment of the present invention to the f surface, C in the figure
A stable *supercharged charge can be obtained. * of toner
*Charging is determined by the toner and the material of the sleeve surface, so the rise of saturated blood is different from A and B, and the rise is almost the same as A. Therefore, in the actual developing device of the present invention, the value of the application in the first rotation is almost the same as the friction band of the toner on the sleeve [because it is an electric charge, the frictional charge of the toner is low and 1
This reduces the possibility of uneven toner application on the sleeve.

As described above, according to the present invention, excellent image quality can be obtained in a visual imaging device using a one-component magnetic developer.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the developing device according to the present invention, FIG. 2 is a view showing the application state of bias voltage in the device shown in FIG. 1, and FIG. FIG. 3 is a diagram showing the relationship between the number and the triboelectric charge value.

Claims (1)

[Claims] When developing a latent image on a latent image carrier using a one-component magnetic developer, the developer is held on a magnetic roll consisting of a non-magnetic sleeve having magnetic poles inside, and the magnetic roll is used to hold the latent image. In an apparatus that performs development in contact with or in close proximity to a body, a first magnetic roll applies a thin layer of developer by imparting a low triboelectric charge to the developer through friction with a sleeve;
a second magnet roll that imparts a high frictional charge to the developer transferred from the first magnet roll due to friction with the sleeve, and the second magnet roll is arranged in contact with the latent image carrier or in close proximity to the latent image carrier at t:F. A developing device characterized by: