JPH0451275A - developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device using a one-component magnetic toner.

[Prior Art] As disclosed in Japanese Patent Publication No. 58-32375, a conventional developing device uses a developing roller having a fixed or rotatable magnetic roller inside a non-magnetic cylindrical sleeve to produce one-component magnetic toner. This method is known as a jumping development method, in which a magnetic brush is formed on the sleeve to convey one-component magnetic toner, and an alternating electric field is formed in the development gap to perform development.

[Problems to be Solved by the Invention] However, in the conventional developing method described above, the developing roller is composed of a developing sleeve and a magnetic roller, and the structure is complicated, large, and expensive, and it is difficult to miniaturize the magnetic pole pitch. There are limitations, and it is difficult to form a thin and uniform toner layer, and there are many causes of image quality deterioration, such as temperature unevenness due to fluctuations in the magnetic field of the magnet roller and trailing at the edges of line images.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and an object of the present invention is to provide a developing device suitable for developing one-component magnetic toner. Still another object is to provide a developing device that is simple in structure, small in size, and low in cost. Still another object is to provide a developing device with high resolution and high image quality.

[Means for Solving the Problems] The developing device of the present invention has a developing roller that conveys one-component magnetic toner and a latent image carrier facing each other in a developing area with a gap larger than the thickness of the developer layer. , a developing device that develops a one-component magnetic toner while forming an alternating electric field in a developing area, characterized in that the developing roller has at least a magnetic field generating layer.

Further, the developing device of the present invention is characterized in that the developing roller has an insulating layer.

Further, the developing device of the present invention is characterized in that the developing roller has a conductive layer.

[Function] According to the above structure of the present invention, the structure of the developing roller is simplified by conveying the toner near the surface of the thin magnetic field generating layer and configuring the developing roller with a single rotating body. However, it is possible to obtain a small, lightweight, and low-cost developing roller. In addition, by magnetizing the thin magnetic field generation layer at a minute pitch, it is possible to form a uniform and thin toner layer (or a thin layer of magnetic brush at a minute pitch) on the developing roller, which prevents fluctuations in the magnetic field. Reduces density unevenness caused by variations in toner layer thickness,
High-resolution development can be performed.

Further, according to the above configuration of the present invention, by applying an alternating electric field to the developing area and at the same time applying a uniform magnetic restraining force of the magnetic field generating layer, the effect of scraping the toner back from the latent image carrier to the developing roller is increased. , it is possible to reduce the background fog that occurs significantly when toner comes into contact with the latent image carrier, and to perform high-resolution development.

Furthermore, by providing a conductive layer on the developing roller, a high-resolution image can be obtained due to the developing electrode effect.

Further, by providing an insulating layer on the developing roller, it is possible to stably perform frictional charging between the developing roller and the toner and reduce temporal fluctuations in the developer density.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Example 1] FIG. 1 is a cross-sectional schematic diagram of an example of the developing device of the present invention. The developing roller 2 that conveys the magnetic toner 1 is connected to the base 3
The magnetic field generating layers 4 are arranged concentrically around the outer periphery of the magnetic toner 1 due to leakage magnetic flux on the outer periphery of the magnetic field generating layer 4.
A thin layer of magnetic toner 1 is conveyed by rotating the developing roller 2 while directly holding the toner and regulating the appropriate amount with a plate-shaped blade 5 made of non-magnetic or magnetic metal or resin. The magnetic toner 1 is eventually transferred to a latent image carrier 8 having an electrostatic image holding layer 7 formed on a supporting electrode 6 and a developing roller 2.
is conveyed to a development area arranged with a gap larger than the layer thickness of the magnetic toner 1. The magnetic toner 1 adheres to the latent image carrier 8 and forms an electrostatic latent image depending on the potential contrast of the latent image carrier 8 and the developing electric field formed by the DC developing bias applying means 9 and the AC developing bias applying means IO. is visualized. When lines, characters, and solid latent images with a resolution of 600 [DPI] were each developed 10,000 times in succession using the developing device shown in Figure 1, the line images were stable without line thickening. It was possible to stably form a high-temperature solid image with an OD value of 1.4 or more without trailing or background fog at the image edges.

FIG. 2 is a cross-sectional schematic view of another embodiment of the developing device of the present invention. Components having substantially the same functions, names, and names as those in FIG. The magnetic toner 1 on the developing roller 2 is made into a thin layer by a thin spring-like elastic blade 11 made of non-magnetic or magnetic metal or resin.
The magnetic toner 1 is transported to a development area arranged with a gap larger than the layer thickness of the magnetic toner 1 . The magnetic toner 1 is applied to the potential contrast of the latent image carrier 8 and the DC developing bias applying means 9.
In response to the developing electric field formed by the AC developing bias applying means 10, the electrostatic latent image attached to the latent image carrier 8 is visualized. When line, character, and solid latent images with a resolution of 600 [DP] were developed 10 and ooo times each in succession using a developing device as shown in Fig. 2, the results were as follows.
A line image was stably formed without line thickening, there was no trailing or background fogging at the edges of the image, and a high-temperature solid image with an oD value of 1.4 or more could be stably formed.

FIGS. 3 to 8 show diagrams of the layer structure of the developing roller in the embodiment of the present invention. The developing roller in the developing device of the present invention includes at least the magnetic field generating layer 22 as a component, and in addition, any one or more layers of the base 21, the conductive layer 23, and the insulating layer 24 are added as a component. Is possible. Although it is desirable that the base body 21 has electrical conductivity, this is not the case when the base body 21 includes the conductive layer 23 as a component.

FIG. 3 is a layer configuration diagram of a developing roller in an embodiment of the present invention, in which a magnetic field generating layer 22 is provided on a base 21 such as a shaft.
A developing roller is formed by forming a developing roller. By magnetizing the magnetic field generation layer 22 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, a minute toner chain is formed by the toner 1 on the magnetic field generation layer 22, resulting in a thin and stable toner layer. is obtained. Furthermore, by magnetizing the magnetic field generation layer 22 in the perpendicular direction (not shown), the magnetization reversal pitch can be made denser to about the particle size of the toner (approximately 10 [μm]), and a single layer of toner can be uniformly distributed. -1 It is also possible to form a thin layer, and since a strong magnetic field can be obtained on the surface of the magnetic field generation layer, it is possible to reduce the magnetic powder content of toner 1, making toner manufacturing easier and improving fixing properties. . Note that the arrow in the figure indicates the direction of magnetization.

FIG. 4 is a layer configuration diagram of a developing roller in another embodiment of the present invention, in which a conductive layer 23 and a magnetic field generating layer 22 are formed in this order on a base 21 to form a developing roller.

The direction of magnetization of the magnetic field generation layer 22 is as in the example of FIG.
Both horizontal and vertical directions are possible, and it is also possible to form a thin layer of toner 1. Furthermore, in this embodiment, a developing bias voltage is applied to the conductive layer 23 to improve the developing electrode effect and obtain a high-resolution image. As the material of the conductive layer 23, in addition to materials containing conductive metals such as A1 and Ni, conductive materials such as carbon black can be used, and it can be formed by means such as adhesion, coating, plating, etc. . Further, when the direction of magnetization is perpendicular, the conductive layer 23 is configured to include a soft magnetic material, and a magnetic circuit of the magnetic field generation layer 22 is provided.
A large magnetic field can be obtained on two surfaces.

FIG. 5 is a layer structure diagram of a developing roller in still another embodiment of the present invention, in which a magnetic field generating layer 2 is sequentially formed on a base 21.
2. A developing roller is formed by forming a conductive layer 23. The direction of magnetization of the magnetic field generating layer 22 can be both horizontal and vertical directions, as in the embodiment shown in FIG.
It is also possible to form a thin layer of the conductive layer 23 with the development bias.
The same applies to the effect of intensifying the developing electrode effect by applying it to . Furthermore, if the conductive layer 23 is formed of a metal thin film containing Ni, Cr, etc., it will function as a protective film for the magnetic field generation layer 22, and the life of the developing roller can be extended.

FIG. 6 is a layer structure diagram of a developing roller in still another embodiment of the present invention, in which a magnetic field generating layer 2 is formed on a base 21 in order.
2. A developing roller is formed by forming an insulating layer 24. In addition to the effects of the embodiment shown in FIG. 3, by providing the insulating layer 24 at the contact area with the toner 1, it is possible not only to control the charging polarity and the amount of charge of the toner 1, but also to improve the wear resistance of fluorocarbon resin and the like. By using a resin with excellent properties for the insulating layer 24, it can also be used as a protective layer for the magnetic field generating layer 22.

FIG. 7 is a layer structure diagram of a developing roller in still another embodiment of the present invention, in which a magnetic field generating layer 2 is sequentially formed on a base 21.
2. A developing roller is formed by forming a conductive layer 23 and an insulating layer 24. In addition to the effects of the embodiment shown in FIG. 5, by providing the insulating layer 24 in the contact area with the toner 1, it is possible not only to control the charge polarity and the amount of charge of the toner 1, but also to make it possible to The insulating layer 24 is made of resin with excellent properties.
By using it, it becomes a protective layer for the conductive layer 23, and the stable development electrode effect of the conductive layer 23 can be maintained.

FIG. 8 is a layer structure diagram of a developing roller in still another embodiment of the present invention, in which a conductive layer 23, a conductive layer 23,
A developing roller is formed by forming a magnetic field generating layer 22 and an insulating layer 24. In addition to the effects of the embodiment shown in FIG. 3, by providing the insulating layer 24 in the contact area with the toner 1, it is possible not only to control the charge polarity and the amount of charge of the toner 1, but also to make it possible to Insulating layer 24
By using it as a protective layer for the conductive layer 23, a stable developing electrode effect can be maintained. Furthermore, when the direction of magnetization is perpendicular, a large magnetic field can be obtained on the surface of the magnetic field generating layer 22 by providing a magnetic circuit for the magnetic field generating layer 22 with the conductive layer 23 containing a soft magnetic material. .

FIG. 9 is a layer structure diagram of a developing roller in still another embodiment of the present invention, in which an insulating layer 24, an insulating layer 24,
A developing roller is formed by forming a magnetic field generating layer 22 and a conductive layer 23. By having the insulating layer 24, it is possible to control the charging polarity and the amount of charge of the toner 1, and by providing the conductive layer 23 on the surface of the developing roller, it is possible to improve the developing electrode effect and produce high-resolution images. Obtainable.

Although examples of the layer structure have been described above, the developing roller in the developing device of the present invention has at least a magnetic field generating layer, and the magnetic field generating layer is electrically conductive or has an independent electrically conductive layer. It is possible to add as constituent elements a base that ensures the strength of the roller and an insulating layer that controls the charging state of the toner. In addition, a protective layer can be provided to improve durability, an intermediate layer can be provided to improve moldability, and it is also possible to combine the functions of multiple layers into a single layer. It is. In addition, the magnetic field generation layer can be magnetized in various states such as line magnetization, lattice magnetization, and spiral magnetization, and the magnetic pole shape can also be in various shapes such as circular and rectangular. The magnetization may be carried out directly on the developing roller, or a film-like magnetic field generating layer which has been previously magnetized may be appropriately provided on the developing roller by means such as adhesion.

Furthermore, although the present invention has been described using an example in which the latent image carrier is a photosensitive drum, the present invention is not limited to this, and it goes without saying that, for example, a photosensitive belt or the like may be used.

Although the embodiments have been described above, the present invention can be applied not only to the above embodiments but also to a wide range of developing devices such as electrophotography.
It is especially effective when applied to printers, copiers, facsimiles, and displays.

[Effects of the Invention] As described above, according to the present invention, by using a developing roller having at least a magnetic field generating layer and developing while applying an alternating electric field in a non-contact developing area,
It is possible to provide a small, lightweight, and low-cost developing device with a simple structure, and because the toner is held within the range of the magnetic field of the magnetic field generating layer magnetized at a minute pitch, the toner layer on the developing roller can be easily made thin. It reduces density unevenness due to variations in magnetic field and toner layer thickness, and uses elastic blades to uniformly hold and transport toner in a thin layer.
Since the development gap can be made small, it is possible to arrange the development electrode very close to the electrostatic latent image, which has the effect of stably forming a high-resolution, high-quality image. Furthermore, by providing a conductive layer or an insulating layer, it is possible to improve the developing electrode effect and durability.

In addition, by applying an alternating electric field to the developing area and simultaneously applying a uniform magnetic restraining force of the magnetic field generating layer, it is possible to increase the effect of scraping the toner back from the latent image carrier to the developing roller and reduce ground force blur. It is possible to obtain high-resolution, high-quality images.

Therefore, the developing device of the present invention has the excellent effect of providing a developing device that can obtain high-resolution images with few image defects such as ground blur and trailing in the -component m-based developing method. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional schematic diagram of an embodiment of the developing device of the present invention. FIG. 2 is a cross-sectional schematic diagram of another embodiment of the developing device of the present invention. FIG. 3 is a diagram showing the layer structure of a developing roller in an example of the present invention. FIG. 4 is a diagram showing the layer structure of a developing roller in another embodiment of the present invention. FIG. 5 is a layer structure diagram of a developing roller in still another embodiment of the present invention. FIG. 6 is a diagram showing the layer structure of a developing roller in still another embodiment of the present invention. FIG. 7 is a diagram showing the layer structure of a developing roller in still another embodiment of the present invention. FIG. 8 is a layer structure diagram of a developing roller in still another embodiment of the present invention. FIG. 9 is a diagram showing the layer structure of a developing roller in still another embodiment of the present invention. Latent image carrier conductive layer insulating layer Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (1 person) 1
: Magnetic toner 2 : Developing roller 4.22 : Magnetic field generating layer Fig. 2 Fig. 6 Fig. 7 Fig. 8

Claims (3)

[Claims] (1) A latent image carrier and a single-rotating developing roller that conveys one-component magnetic toner are held facing each other in a developing area with a gap larger than the thickness of the developer layer, and an alternating electric field is applied to the developing area. A developing device for developing the one-component magnetic toner while forming a magnetic toner, wherein the developing roller has at least a magnetic field generating layer. (2) The developing device according to claim 1, wherein the developing roller has an insulating layer. (3) The developing device according to claim 1 or 2, wherein the developing roller has a conductive layer.