JPH04142577A - Developing device - Google Patents

Abstract

PURPOSE:To stably form an image of high quality with high resolution by a small-sized, low-cost device by constituting a developing roller which carries magnetic toner nearby the surface of a thin magnetic field producing layer by using a single rotary body, and forming a nonmagnetic layer adjacently to the magnetic field producing layer. CONSTITUTION:The developing roller 9 consists of a driving roller 10 which is driven to rotate and has a friction part, etc., at its outer periphery and a cylindrical nonmagnetic thin film member 11 which covering its outer periphery except excessive length, the magnetic toner 8 is held with leaking magnetic flux at the outer periphery of the magnetic field producing layer 12 on the member 11, and a thin layer of the toner 8 is carried while controlled to a proper amount. When the toner 8 is carried to the development gap part where a latent image carried 1 and the roller 9 come close to each other, a developing bias impressing means 14 produces a developing electric field and the toner 8 which is charged electrostatically sticks on a latent image carrier 1 to visualize an electrostatic latent image. Thus, the nonmagnetic layer is formed adjacently to the magnetic field producing layer to facilitate magnetization and effectively use the magnetic force from the magnetic field producing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing device using magnetic toner, and more specifically, a developing device that conveys and develops magnetic toner by a developing roller having a cylindrical thin film member. Regarding.

[Prior Art] As disclosed in Japanese Patent Application Laid-Open No. 64-65579, a conventional developing device elastically attaches an excess portion of a cylindrical thin film member sleeve having an excess circumferential length to a photoreceptor with respect to a drive roller. By bringing them into close contact, it was possible to transport and develop non-magnetic toner.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the force that holds the toner on the developing roller is based on electrostatic mirror image force and adhesive force, so it is difficult to make the amount of toner conveyed uniform. Ta. Furthermore, when toner is developed on a latent image bearing member such as a photoconductor, uncharged toner or toner with a non-regular polarity adheres to the non-image area, resulting in significant background blur (toner is not deposited on the non-image area) on the latent image bearing member. Since only toner of the correct polarity is transferred to the recording paper, an image without blurring can be obtained on the recording paper, but the toner that is not transferred and is wasted unnecessarily. In many cases, this is not only uneconomical, but also requires a sufficient space for the waste toner container, making the image forming apparatus larger.

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 in which the amount of toner conveyed is stable and density unevenness is reduced. Still another object is to provide a developing device that causes less contamination due to toner scattering and can reduce unnecessary waste toner. Still another object is to provide a developing device that has a simple structure and is applicable to small, low-cost image forming apparatuses. Still another object is to provide a developing device with high resolution and high image quality.

[Means for Solving the Problems] A developing device of the present invention is a developing device that conveys magnetic toner by a developing roller and develops the magnetic toner on a latent image carrier, wherein the developing roller is a cylindrical thin film member and a thin film member. The thin film member has at least a drive roller that contacts at least a portion of the inner circumferential side of the thin film member, and the thin film member has at least a magnetic field generating layer and a nonmagnetic layer.

Further, the developing device of the present invention is characterized in that the thin film member is brought into pressure contact with the latent image carrier.

Furthermore, the developing device of the present invention is characterized in that the thin film member has a conductive layer.

Furthermore, the developing device of the present invention is characterized in that the thin film member has an insulating 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 as a single rotating body. However, it is possible to obtain a small, lightweight, and low-cost developing roller. In addition, by forming a non-magnetic layer adjacent to the thin magnetic field generation layer, when the magnetic field generation layer is magnetized, the magnetizing magnetic flux concentrates on the magnetic field generation layer, making magnetization easy. Since most of the leakage magnetic flux from the layer penetrates into the toner near the magnetic field generation layer, the toner conveying force and restraining force on the surface of the developing roller can be increased, and the magnetic force can be used effectively. Therefore, very common magnetic materials can be used as the material for the magnetic field generation layer. 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. Conductivity unevenness caused by fluctuations can be reduced, toner is held on the developing roller by magnetic force to reduce ground force blur, and development can be performed with high resolution and high print quality. In addition, magnetic binding force reduces contamination caused by toner scattering, and by reducing soil blur and unnecessary waste toner, it is possible to make image forming devices smaller, lower cost, and require less maintenance, reducing toner consumption. It is also possible to reduce running costs.

Further, according to the above configuration of the present invention, even when the thin film member is pressed against the latent image carrier for development, development can be performed with high resolution and high printing quality without any ground force blur.

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

Further, by providing an insulating layer on the thin film member, the frictional charging between the thin film member and the toner can be stably performed, and temporal fluctuations in the degree of development immersion can be reduced.

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

[Example 1] FIG. 1 is a cross-sectional schematic view of an image forming apparatus using the developing device of the present invention. The latent image carrier 1 has a photosensitive layer 3 coated with an organic or inorganic photoconductive material on a conductive support 2, and the photosensitive layer 3 is coated with a corona charger or a charging roller. After charging using a charger 4 such as a laser or LED, light emitted from a light source 5 such as a laser or LED is selectively irradiated onto the photosensitive layer 3 according to the image through an imaging optical system 6 to obtain a potential contrast. Forms an electrostatic latent image. On the other hand, the developing device 7
The developing roller 9 that conveys the toner 8 is rotatably driven and has a friction portion on its outer periphery, and a driving roller 10 that leaves an extra length on the outer periphery of the driving roller 10. It is composed of a cylindrical non-magnetic thin film member 11 made of a non-magnetic metal or resin, and
A magnetic field generating layer 12 is disposed on the non-magnetic thin film member 11,
The magnetic toner 8 is generated by leakage magnetic flux around the outer periphery of the magnetic field generation layer 12.
is held directly on the developing roller 9, and the thin layer of toner 8 is conveyed by rotating the developing roller 9 while regulating the appropriate amount with a plate-shaped blade 13 made of non-magnetic or magnetic metal or resin. It is. When the toner 8 is conveyed to the development gap where the latent image carrier 1 and the developing roller 9 are close to each other, a developing electric field is formed by the potential contrast of the latent image carrier 1 and the developing bias applying means 14, and the toner is charged according to the developing electric field. The toner 8 adheres to the latent image carrier 1, and the electrostatic latent image is visualized. Furthermore, the toner image is transferred onto the recording paper 16 using a transfer device 15 such as a corona transfer device or a transfer roller,
The toner is fixed on the recording paper using heat or pressure to obtain a desired image on the recording paper. When we continuously formed 10,000 sheets of 600 [DPI] line images, character images, and solid images using the image forming apparatus shown in Fig. 1, the 600 [DPI] line images did not become thick. It is possible to stably form a solid image with a high temperature of 0D (IIL, 4 or higher) without any trailing or ground force blur at the edges of the image, and of course there is no ground force blur on the recording paper. There was no ground force blur on the latent image carrier, and the amount of waste toner could be significantly reduced.

FIG. 2 is a cross-sectional schematic diagram of an image forming apparatus using a developing device according to another embodiment of the present invention, in which members having substantially the same functions, functions, and names as those in FIG. 1 are given the same numbers and explained. omitted. The developing device 21 conveys and develops the magnetic toner 8, and the developing roller 9 that conveys the toner 8 holds the magnetic toner 8 directly on the developing roller 9 by leakage magnetic flux around the outer periphery of the magnetic field generating layer 11. The toner 8 is then thinned to an appropriate amount using a thin plate spring-like elastic blade 22 made of non-magnetic or magnetic metal or resin, and the developing roller 9 is rotated to form a thin layer of toner 8.
It is used to transport. The developing roller 9 is pressed against the latent image carrier 1 with a predetermined pressure, and when the toner 8 on the developing roller 9 is conveyed to the pressure contact portion, the potential contrast of the latent image carrier 1 and the developing bias applying means 14 are applied. Toner 8 charged according to the developing electric field adheres to the latent image carrier 1, and the electrostatic latent image is visualized. When we continuously formed 10,000 sheets of 600 [DPI] line images, character images, and solid images using an image forming apparatus as shown in Fig. 2, the line images of 600 [DPI] did not become thick. It is formed stably and the resolution of the line pair image is the highest, and there is no trailing or blurring at the edges of the image.
It is possible to stably form a high-temperature solid image with an OD value of 1.4 or higher, and there is no ground force blur on the recording paper as well as on the latent image carrier, greatly reducing the amount of waste toner. We were able to.

In FIGS. 1 and 2, the drive roller 10 has a friction portion made of natural rubber, silicone rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, isoprene rubber, NBR, etc. on the outer periphery of a shaft made of resin or metal. The non-magnetic thin film member 11 is pressed against the drive roller 10 to transmit rotational driving force. Further, the nonmagnetic thin film member 11 can be made of a nonmagnetic material such as a metal thin film such as phosphor bronze, copper, or stainless steel, or a resin thin film material such as nylon, polyimide, or polyethylene terephthalate. The film thickness of the non-magnetic thin film member 11 varies depending on the material, but in order to obtain sufficient pressure contact with the latent image carrier, the film thickness is 10 to 10.
It is desirable to have a thickness of about 500 [μm]. When the non-magnetic thin film member 11 is thin, if the drive roller 10 is also made non-magnetic, the effect of concentrating the magnetic flux from the magnetic field generation layer on the toner layer can be further enhanced. Furthermore, for the magnetic field generation layer 12, a known magnetic recording material or magnet material can be used.
More specifically, Fe, Ni, Co, Mn,
Magnetic materials containing at least one element among Cr, such as yFe2O3, Ba-Fe, Ni-Co
, Co-Cr, Mn-A1, etc. can be used, and the film thickness is 10
The film is thinned to 0 [μm] or less, preferably around 10 [μm], and the minimum magnetization reversal pitch is made to be 100 [μm] or less to make the toner a uniformly thin layer, and at the same time, the variation in the amount of toner conveyed on the developing roller due to the formation of a magnetic brush is reduced. Density unevenness can be reduced by keeping the pitch to a minute pitch. Further, as the toner used in the present invention, all toners known as magnetic toners can be used, and either resin-based toner or wax-based toner may be used. It is made by adding magnetic powder, coloring agents, external additives, and other additives to the powder, and is created by pulverization or polymerization methods.

In addition, in FIGS. 1 and 2, the present invention is not limited to the configurations shown in the figures, and although the arrows indicate the rotation directions of the respective members, the present invention is not limited to the configurations shown in the figures.

Furthermore, the developing method can be used regardless of whether it is regular development or reversal development.

FIGS. 3 to 8 show diagrams of the layer structure of thin film members in embodiments of the present invention.

FIG. 3 is a diagram showing the layer structure of a thin film member in an embodiment of the present invention, in which a magnetic field generating layer 32 is placed on a nonmagnetic thin film member 31.
, and the magnetic field generating layer 32 is formed so that the layer thickness d is 100 [μm] or less, preferably around 10 [μm],
By magnetizing in the horizontal direction so that the magnetization reversal pitch p is 100 μm or less, a minute toner chain is formed by the toner 33 on the magnetic field generation layer 32, and a thin and stable toner layer is obtained. Since the non-magnetic thin film member 31 is non-magnetic, when magnetizing the magnetic field generating layer 32, the magnetizing magnetic flux concentrates on the magnetic field generating layer 32, so it can be easily magnetized, and leakage magnetic flux from the magnetic field generating layer 32 can be easily magnetized. contributes to the formation of toner chains, increasing the efficiency of magnetic force utilization. In addition, conductive non-magnetic metal thin films based on copper, stainless steel, aluminum, etc., and resin thin films made by dispersing conductive materials such as the aforementioned conductive non-magnetic metal powder or carbon black in elastic resin are also available. By forming the magnetic thin film member 31, the developing bias voltage can be applied to the non-magnetic thin film member 31.
can be applied to improve the developing electrode effect and obtain high-resolution images. Note that the arrow in the figure indicates the direction of magnetization.

FIG. 4 is a diagram showing the layer structure of a thin film member in another embodiment of the present invention, in which a nonmagnetic layer 42 is disposed on a thin film member 41, and a magnetic field generating layer 43 is disposed on the nonmagnetic layer 42. The magnetic field generation layer 43 is formed to have a layer thickness d of 100 [μm] or less, preferably around 10 [μm], and is magnetized in the horizontal direction so that the magnetization reversal pitch p is 100 [μm] or less. By doing so, a minute toner chain is formed by the toner 44 on the magnetic field generating layer 43, and a thin and stable toner layer is obtained. As the material of the thin film member 41, various materials such as metal or resin can be used as materials capable of forming a thin film structure. The material of the non-magnetic layer 42 includes non-magnetic metals such as aluminum, copper, gold, silver, platinum, etc., and resin.
The nonmagnetic layer 42 can be formed by plating, coating, adhesion, welding, or other means. Note that the arrow in the figure indicates the direction of magnetization.

It is also possible to add electrical conductivity to the nonmagnetic layer 42 in the embodiment of FIG. By applying a developing bias voltage to the nonmagnetic layer 42, the developing electrode effect can be improved and a high resolution image can be obtained. As the material of the non-magnetic layer 42, in addition to materials containing non-magnetic conductive metals such as aluminum, copper, gold, silver, and platinum, conductive materials such as carbon black can be used. The nonmagnetic layer 42 can be formed by means such as the following.

FIG. 5 is a diagram showing the layer structure of a developing roller in still another embodiment of the present invention, in which a magnetic field generating layer 52 is provided on a non-magnetic thin film member 51, and a non-magnetic conductive layer 52 is provided on the magnetic field generating layer 52. A layer 53 is provided, and the magnetic field generation layer 52 has a layer thickness d of 100 μm.
] Thereafter, by forming the non-magnetic conductive layer 53 so that it is preferably around 10 [μm1] and horizontally magnetizing it so that the magnetization reversal pitch p is 100 [μm] or less, the non-magnetic conductive layer 53 is coated with minute particles of toner 54. A thin toner chain is formed and a stable toner layer is obtained. Therefore, the non-magnetic conductive layer 53 can be formed of a metal thin film containing Ni, Cr, etc., which can improve the development electrode effect and obtain a high-resolution image by applying a developing bias voltage to the non-magnetic conductive layer 53. For example, the nonmagnetic conductive layer 53 functions as a protective film for the magnetic field generation layer 52, and the life of the developing roller can be extended. Note that the arrow in the figure indicates the direction of magnetization.

FIG. 6 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention, in which a magnetic field generating layer 62 is disposed on a nonmagnetic thin film member 61, and a nonmagnetic insulating layer is provided on the magnetic field generating layer 62. layer 6
3, and the magnetic field generation layer 62 has a layer thickness d of 100 [μm].
Thereafter, by forming the non-magnetic insulating layer 63 so that it is preferably around 10 [μm] and magnetizing it in the horizontal direction so that the magnetization reversal pitch p becomes 100 [μm] or less, the toner 64 forms microscopic particles on the non-magnetic insulating layer 63. A thin toner chain is formed and a stable toner layer is obtained. By providing the non-magnetic insulating layer 63 in the contact area with the toner 64, it is possible not only to control the charging polarity and the amount of charge of the toner 64, but also to use a resin with excellent wear resistance such as fluorocarbon resin as the non-magnetic insulating layer. 63
It can also be used as a protective layer for the magnetic field generation layer 62.

Note that the arrow in the figure indicates the direction of magnetization.

FIG. 7 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention, in which a nonmagnetic conductive layer 72 is provided on a thin film member 71, and a magnetic field generating layer is provided on the nonmagnetic conductive layer 72. 73 is disposed, a non-magnetic insulating layer 74 is disposed on the magnetic field generation layer 73, and the magnetic field generation layer 73 is formed to have a layer thickness d of 100 [μm] or less, preferably around 10 [μm]. By magnetizing in the horizontal direction so that the magnetization reversal pitch p is 100 [μm] or less, the toner 7 is formed on the nonmagnetic insulating layer 74.
5, a minute toner chain is formed and a thin and stable toner layer is obtained. In this case, the nonmagnetic conductive layer 72 not only has a developing electrode effect, but also smoothes the surface of the thin film member 71 with the nonmagnetic conductive layer 72, thereby facilitating the formation of the magnetic field generating layer 73. By providing the non-magnetic insulating layer 74 in the contact area with the toner 75, it is possible not only to control the charging polarity and the amount of charge of the toner 75, but also to use a resin with excellent wear resistance such as fluorocarbon resin as the non-magnetic insulating layer. By using it in 74, it can also be used as a protective layer for the magnetic field generation layer 73. Note that the arrow in the figure indicates the direction of magnetization.

FIG. 8 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention, in which a magnetic field generating layer 82 is disposed on a nonmagnetic thin film member 81, and a nonmagnetic conductive layer 82 is provided on the magnetic field generating layer 82. layer 8
3 is disposed, a nonmagnetic insulating layer 84 is disposed on the nonmagnetic conductive layer 83, and the magnetic field generation layer 82 is formed so that the layer thickness d is 100 [μm] or less, preferably around 10 [μm]. However, by magnetizing in the horizontal direction so that the magnetization reversal pitch p is 100 [μm] or less, a minute toner chain is formed by the toner 85 on the nonmagnetic insulating layer 84, and a thin and stable toner layer is formed. can get. In this case, the nonmagnetic conductive layer 8
3 as a developing electrode close to the latent image carrier, not only can a high-resolution image be obtained, but also the non-magnetic insulating layer 84 can be used as a toner 8.
5, it is possible not only to control the charging polarity and the amount of charge of the toner 85, but also to function as a protective layer for the non-magnetic conductive layer 83, which is the developing electrode, and maintain a stable developing electrode effect. be able to. Note that the arrow in the figure indicates the direction of magnetization.

In addition to the above examples of layer configurations, stacked layer configurations are possible, such as a configuration in which the functions of multiple layers are combined into a single layer, and a layer configuration in which an intermediate layer is provided between each layer to facilitate the connection between the eyebrows. It is also possible to provide a structure in which the developing electrode effect is improved by arranging it in a predetermined layer.

In the present invention, a stable toner thin layer can be formed on the developing roller by magnetizing the magnetic field generation layer so that the minimum magnetization reversal pitch is sufficiently small (for example, 100 [μm] or less).
In particular, it does not depend on the magnetization state, and in order to perform magnetization with such a minute pitch, the layer thickness of the magnetic field generation layer must be 100 mm.
[μm] or less, preferably around 10 [μm].Also, the magnetization may be carried out directly on the developing roller, or by adhering a film-shaped magnetic field generating layer in advance to the developing roller as appropriate. It may be arranged.

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, a magnetic field generating layer is provided in a cylindrical thin film member, and the adjoining layer of the magnetic field generating layer is made of a nonmagnetic layer. It is possible to provide a developing device that facilitates magnetization, effectively uses the magnetic force from the magnetic field generation layer, has a stable toner conveyance amount, and has little temperature unevenness.
It is possible to provide a developing device that reduces contamination due to toner scattering, reduces unnecessary waste toner, is easy to maintain, and has low running costs, and it is possible to provide a compact, low-cost developing device with a simple structure. This has the effect of stably forming high-resolution, high-quality images. Further, it is possible to provide a developing device that is compatible with both contact development and pressure development, and in particular, when pressure development is used, it is possible to maximize the development electrode effect and form an image with the highest resolution. Furthermore, by providing a conductive layer or an insulating layer, it is possible to improve the developing electrode effect and durability.

Therefore, the developing device of the present invention has an excellent effect in that it can provide a developing device that can obtain high-resolution images with few image defects such as ground blur and trailing in the magnetic development method.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus using a developing device of the present invention, FIG. 2 is a cross-sectional schematic diagram of an image forming device using a developing device according to another embodiment of the present invention, and FIG. A diagram showing the layer structure of a thin film member in an embodiment of the invention, FIG. 4 is a diagram showing a layer structure of a thin film member in another embodiment of the invention,
FIG. 5 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention, FIG. 6 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention, and FIG. 7 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention. FIG. 8 is a diagram showing the layer structure of a thin film member in still another embodiment of the present invention. FIG. 1...Latent image carrier 7...Developing device Toner developing roller drive roller Non-magnetic thin film member Magnetic field generating layer Applicant Seiko Epson Corporation Representative Patent attorney Kizobe Suzuki (@! 1 person) Figure 2 Figure 3 Figure 4 Figure 5

Claims (4)

[Claims] (1) In a developing device that conveys magnetic toner by a developing roller and develops the magnetic toner onto a latent image carrier, the developing roller contacts at least a portion of a cylindrical thin film member and an inner peripheral side surface of the thin film member. What is claimed is: 1. A developing device comprising at least a drive roller for generating a magnetic field, the thin film member having at least a magnetic field generating layer and a nonmagnetic layer. (2) The developing device according to claim 1, wherein the thin film member is pressed against the latent image carrier. (3) The developing device according to claim 1 or 2, wherein the thin film member has a conductive layer. (4) The developing device according to claim 1, 2 or 3, wherein the thin film member has an insulating layer.