JPH046953B2 - - Google Patents

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. The present invention relates to a developing device that performs development by holding the latent image holding member and 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 transferability when transferring the converted toner image to the transfer material is poor,
It is unsuitable for copying machines that use plain paper. On the other hand, 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, and because it is necessary to maintain a uniform charge on the toner, it is also necessary to maintain a uniform toner layer on the sleeve. For 50~400μ on the sleeve surface
It is necessary to apply a thin coating on the order of m. This has a magnetic blade facing the magnet roll, and the gap between the magnetic blade and the sleeve is 100 to 500μ.
m and facing each other.

In such a developing method, it is generally known that the larger the toner charge, the better the image quality. However, if a large triboelectric charge is applied to the toner using the above-described developing method, the thin toner coating on the sleeve becomes uneven. As a result of the toner's charge becoming larger, the adhesion force with the sleeve increases and it is strongly attracted to the sleeve surface, and even if you try to apply a coating with a magnetic blade, it will not be able to be restricted by the magnetic blade, and there will be spots on the sleeve. This is because a thick toner layer is formed.

An object of the present invention is to eliminate uneven coating of toner, provide a stable charge to the toner, and increase the charge held by the toner when forming a thin coating on a sleeve.
A further object of the present invention is to improve development and transfer properties at high humidity and to improve image quality.

In order to achieve the above object, the developing device of the present invention includes: a first non-magnetic sleeve having a magnet therein; a container for supplying a one-component magnetic developer to the first non-magnetic sleeve; A blade that regulates the layer thickness of the one-component magnetic developer supplied to the non-magnetic sleeve and conveyed by the first non-magnetic sleeve, and a blade that receives the one-component magnetic developer conveyed by the non-magnetic sleeve and transfers it to the latent image carrier. a second non-magnetic sleeve having a magnet therein, which is conveyed to a development site where the one-component magnetic developer is applied; and the material of the surface of the second non-magnetic sleeve is a material that is further away from the one-component magnetic developer than the material of the surface of the first non-magnetic sleeve in terms of triboelectrification. and the second
The non-magnetic sleeve is characterized by imparting a higher triboelectric charge to the one-component magnetic developer than the first non-magnetic sleeve.

The present invention will be described in detail below 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, 1 is a developing device, and 2 is a latent image holder, 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 is the first
shows a magnet roll consisting of a non-magnetic sleeve 8 with magnetic poles 7 inside. 9 designates a second magnet roll, which consists of a non-magnetic sleeve 11 with a magnetic pole 10 inside. The first magnet roll 6 is 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 through friction with the sleeve. A second magnetic roll 9 is arranged in contact with or in close proximity to the latent image carrier, that is, the photosensitive drum 2.

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

Here, the toner comes into contact with or comes close to the latent image holding member 2, and the latent image on the latent image holding member 2 is developed by the frictionally charged charge on the toner. The illustrated embodiment shows a so-called jumping development method, in which the sleeve 11 of the second magnetic roll is close to the latent image holding member 2, and the toner is transferred from the surface of the sleeve 11 according to the latent image. Moving on to the holding member 2. Sleeve 11
As shown in FIG.
is applied to make the above-mentioned toner move easily. Furthermore, in order to transfer the toner from the sleeve 8 of the first developing roller to the sleeve 11 of the second developing roller and to thinly coat the surface of the sleeve 11 with the toner, the same method as the above-mentioned jumping development is used. A bias voltage 15 as shown in the figure is applied.

When coating a toner thinly, it is necessary not to make the charge of the toner larger 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 magnet roll is made of stainless steel, steel, aluminum, alumite, hardwood, 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 a metal such as chrome plating or a material relatively similar to the triboelectrification series such as polyethylene, polystyrene, polyurethane, etc. 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 or the like for positive toner, so as to be suitable for high-quality image development.

In this way, the present invention provides sleeve 8 and sleeve 11.
coat the surface with materials of different charge series.

As explained above, in a developing method where the toner is non-conductive and generates an electric charge due to the friction between the magnetic roll and the sleeve, when the toner is thinly applied to the sleeve surface to a thickness of 50 to 1000 μm. , development and transfer properties are improved, and excellent image quality can be obtained. The generation of unevenness on the sleeve can be suppressed, especially in a low humidity environment where the electric charge due to frictional charging becomes large.

This will be explained with reference to FIG. Figure 3 shows the triboelectric charge value of the toner generated by the rotation of the sleeve after toner has been thinly applied onto the sleeve.The horizontal axis shows the number of rotations of the sleeve and the vertical axis shows the triboelectric charge value. There is. As shown in the figure, the triboelectric charge value of the toner gradually increases as the sleeve rotates, and finally reaches saturation. A in the figure shows the triboelectric charge in a normal humidity environment, and B in the figure shows the triboelectric charge in a normal humidity environment.
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, by subjecting the sleeve surface to the treatment of the present invention, stable triboelectric charges can be obtained as shown in C in the figure. The triboelectric charge of the toner is determined by the materials of the toner and sleeve surfaces, so
The saturation value is different from A and B, but the rise shows almost the same tendency as A. Therefore, in the actual developing device of the present invention, since the value of application in the first rotation is almost the triboelectric charge of the toner on the sleeve, the triboelectric charge of the toner becomes low, and uneven toner application occurs on the sleeve. It becomes difficult.

As described above, according to the present invention, excellent image quality can be obtained in a developing 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 diagram showing the application state of bias voltage in the device shown in FIG. 1, and FIG. 3 is a diagram showing the rotational speed of the sleeve in the developing device. FIG. 3 is a diagram showing the relationship between triboelectric charge values. 1...Developing device, 2...Latent image holder (photosensitive drum), 3...Developer container, 4...Magnetic blade,
5... One-component magnetic developer, 6... First magnet roll, 7... Magnetic pole, 8... Non-magnetic sleeve, 9...
Second magnet roll, 10...Magnetic pole, 11...Nonmagnetic sleeve, 14, 15...Bias power supply.

Claims (1)

[Claims] 1 a first non-magnetic sleeve having a magnet therein; a container for supplying a one-component magnetic developer to the first non-magnetic sleeve; and a container for supplying a one-component magnetic developer to the first non-magnetic sleeve; A blade that regulates the layer thickness of the one-component magnetic developer being conveyed, and a second blade having a magnet inside, which receives the one-component magnetic developer conveyed by the non-magnetic sleeve and conveys it to a development site where it is applied to the latent image carrier. the first and second non-magnetic sleeves each have a surface that triboelectrically charges the one-component magnetic developer by friction with the one-component magnetic developer; The surface material is a material that is further away from the one-component magnetic developer than the surface material of the first non-magnetic sleeve in terms of triboelectrification, and the second
A developing device, wherein the non-magnetic sleeve imparts a higher triboelectric charge to the one-component magnetic developer than the first non-magnetic sleeve.