JPH03259285A - Developing device - Google Patents

Abstract

PURPOSE:To reduce the irregularity of density or ground fogging by disposing a magnetic field generation layer to a cylindrical thin film member and holding and carrying toner whose electrostatic charge quantity is stable. CONSTITUTION:A developing roller 2 carrying the magnetic toner 1 is constituted of a driving roller 3 which is driven to be rotated and provided with a frictional part or the like on the outside circumference and the cylindrical thin film member 4 which is externally provided to the outside circumference of the roller 3 by leaving excess length. Then, the member 4 has such constitution that the magnetic field generation layer 6 is disposed on a base body 5 having electric conductivity and an insulating layer 7 whose is dotted with fine electrodes on its surface is disposed on the layer 6. Therefore, the magnetization of a fine pitch is executed on the thin magnetic field generation layer and a uniform and thin toner layer can be formed on the developing roller 2. Thus, the irregularity of the density caused by the change of the thickness of the toner layer is reduced. Besides, the ground fogging is reduced by holding the toner to the developing roller 2 with the aid of magnetic force. As the result, developing of high resolution and high printing quality is realized.

Description

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

[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 drive roller onto a photoreceptor. 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.

In addition, since the toner retention force is small, when toner is developed on a latent image carrier such as a photoreceptor, uncharged toner or toner with a non-regular polarity is developed in the non-image area, and there is a noticeable difference in ground pressure on the latent image carrier. When used in an image forming device such as electrophotography that can only obtain images with a large amount of toner (toner attached to non-image areas), only toner of the correct polarity is transferred to the recording paper; A large amount of toner is unnecessarily discarded, which is not only uneconomical, but also requires a waste toner container that occupies a large amount of space, which increases the size of the image forming apparatus.

In addition, because the toner retention force is weak, even if charged to the correct polarity, toner with a large amount of charge per unit mass will adhere to the non-image area due to image force etc. when it comes into contact with the latent image carrier in the development area. This was the cause of soil blemishes remaining on the recording paper.

Therefore, the present invention is intended to solve these problems, and its purpose is to stabilize the toner transport I by stabilizing t-, w.
To provide a developing device that has little unevenness in density and does not cause burrs. Still another object is to provide a developing device that can reduce unnecessary waste toner. Still other,
An object of the present invention is to provide a developing device that has a simple structure and is applicable to a small, low-cost image forming apparatus. 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 transports a one-component magnetic toner to a developing area by a developing roller having an insulating layer formed by interspersing a plurality of microelectrodes on at least the surface thereof, In a developing device that develops a one-component magnetic toner onto a latent image carrier, the developing roller has at least a cylindrical thin film member and a drive roller that contacts at least a portion of an inner circumferential side of the cylindrical thin film member, is characterized in that it has at least a magnetic field generating 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.

[Operation] According to the above structure of the present invention, the thin magnetic field generating layer is magnetized with a fine pitch, and a uniform thin toner layer (or a thin magnetic brush layer with a fine pitch) is formed on the developing roller. ), reducing temperature unevenness caused by variations in toner layer thickness, holding the toner on the developing roller by magnetic force to reduce ground blur, and developing with high resolution and high print quality. I can do it.

Furthermore, by reducing soil blurring and unnecessary waste toner, it is possible to make the image forming apparatus smaller and lower in cost and maintenance, and by reducing toner consumption I, it is also possible to reduce running costs.

Further, according to the above configuration of the present invention, by rubbing the toner with an insulating layer having microelectrodes dotted on the surface, the toner charge is stabilized and a high density is ensured, and at the same time, the microelectrodes provide a developing electrode effect. It is possible to maintain the temperature not only for line drawings but also for surface drawings.

Hereinafter, the details of the present invention will be shown by examples.

[Example] 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 driven by a driving roller 3 that is rotationally driven and has a friction portion on the outer periphery.
and a cylindrical thin film member 4 that is wrapped around the drive roller 3 with an extra length left on its outer periphery. The cylindrical thin film member 4 has a structure in which a magnetic field generating layer 6 is disposed on a conductive base 5, and an insulating layer 7 having microelectrodes dotted on the surface thereof is disposed on the magnetic field generating layer 6. be. Insulation M dotted with microelectrodes
7 holds the magnetic toner 1 by leakage magnetic flux, gives a charge of a predetermined polarity to the toner 1 by frictional charging, and at the same time, the microelectrode obtains a charge of the opposite polarity. The toner 1 held on the insulating layer 7 is conveyed by the rotation of the developing roller 2 while being controlled in an appropriate amount by a plate-shaped blade 12 made of non-magnetic or magnetic metal or resin. Then, the toner 1 is transported to the development area where the latent image carrier 8 and the developing roller 2, which are composed of the supporting electrode 9 and the electrostatic image holding layer 10'''C, are in close proximity to each other. 8 and the developing electric field formed by the developing bias applying means 11, the electrostatic latent image adheres to the latent image carrier 8 and becomes visible.At this time, the microelectrode on the surface layer of the developing roller 2 The toner is charged by triboelectric charging and exhibits the same effect as the carrier in the two-component development method, so that the developing electric field is enhanced and the toner 1 is efficiently developed.

11] using a developing device as shown in 600[
When line images, character images, and solid images of [DPI] were continuously formed on 10,000 sheets, the result was 600 [DPI].
DPI] line image is stably formed without line thickening, there is no trailing or blurring at the edge of the image, and the OD value is 1.
．． It is possible to stably form a solid image at a high temperature of 4 or higher, and there is no ground force blur in the image transferred to the recording paper, and there is also no ground force blur on the latent image carrier, significantly reducing the amount of waste toner. We were able to.

FIG. 2 is a cross-sectional schematic view of another embodiment of the developing device according to the present invention, and members having substantially the same functions, names, and names as those in FIG.

The insulation J17 dotted with microelectrodes holds the magnetic toner 1 due to leakage magnetic flux, and jl! A charge of a predetermined polarity is applied to the toner 1 by triboelectric charging, and at the same time, the microelectrode obtains a charge of the opposite polarity. The toner 1 held on the insulating layer 7 is
The film is thinned to an appropriate amount by a thin plate spring-like elastic blade 22 made of non-magnetic or magnetic metal or resin, and transported to the development area by the rotation of the development roller 2 . The developing roller 2 is in pressure contact with the latent image carrier 8 at a predetermined pressure, and when the toner 1 on the developing roller 2 is conveyed to the pressure contact part, the potential contrast and development of the latent image carrier B in the presence of microelectrodes occur. The electrostatic latent image is adhered to the latent image carrier 8 according to the developing electric field applied by the bias applying means 11, and the electrostatic latent image is visualized.

The developing electrode effect of the microelectrode is similar to that of the embodiment shown in FIG. Using a developing device as shown in FIG.
When 10,000 sheets of line images, character images, and solid images of 600 [D
The line image of [P engineering] is stably formed without line thickening, the resolution of the line bare image is the highest, there is no trailing or ground blurring at the edge of the image, and it is a high-density solid image with an OD value of 1.4 or more. was able to be stably formed, and there was no background blur in the image transferred onto the recording paper, and there was also no background blur on the latent image carrier, making it possible to significantly reduce the amount of waste toner.

In Figures 1 and 2, the drive roller 3 has a friction part made of natural rubber, silicone rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, NBR, etc. on the outer periphery of a resin or metal shaft. The thin film member 4 is pressed against the drive roller 3 to transmit rotational driving force.

The thickness of the thin film member 4 varies depending on the material, but in order to obtain sufficient pressure contact with the latent image carrier, the thickness of the thin film member 4 is 10 to 500 [
μm] is preferable.

In addition, the thickness of the magnetic field generation layer 6 is 100 [μm] or less, preferably around 10 [μm], and the minimum magnetization reversal pitch is 100 [μm] or less to uniformly thin the toner layer and at the same time form a magnetic brush. It is possible to reduce density unevenness by suppressing fluctuations in the amount of toner conveyed on the developing roller to a minute pitch.

Further, as the toner used in the present invention, all toners known as one-component magnetic toners can be used, including resin-based toners, wax-based toners, etc.
As is well known, the composition of the developer is a mixture of resin, magnetic powder, colorant, external additives, and other additives, and is produced by a pulverization method, a polymerization method, or the like.

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. The latent image carrier 8 can also be in the form of a belt,
The developing method can be used regardless of whether it is regular development or reversal development.

FIG. 3 is a diagram showing the layer structure of the N-layer member of the developing roller in an example of the present invention. The N-layer member has a magnetic field generating layer M32 formed on a conductive base 31, and further an insulating layer 34 having minute microelectrodes 33 dotted on the surface thereof formed on the magnetic field generating layer 32. Base body 31 of thin film member 4
A metal thin film such as phosphor bronze, stainless steel, or nickel can be used. Further, only when the magnetic field generating Jli 32 is vertically magnetized, it is possible to obtain a large magnetic field on the surface of the insulating layer 34 by making the base body 31 include a soft magnetic material and providing a magnetic circuit of the magnetic field generating layer 32. can. Further, the magnetic field generation layer 32 can be made of a known magnetic recording material or magnet material.
Magnetic material containing at least one element among e, Ni, Co, and Mn, for example, γ-Fe2
O3, Ba-Fe, Ni-Co, Co-Cr, Mn-A
1st class is available. Also, a magnetic field is generated! By magnetizing the fi 32 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, a minute toner chain of the magnetic toner 1 is formed on the magnetic field generation layer 32, resulting in a thin and stable toner layer. can get. Furthermore, by magnetizing the magnetic field generation layer 32 in the perpendicular direction (not shown), the magnetization reversal pitch can be made denser to about the toner particle size (10 [μm] gL). It is also possible to form a thin toner 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 the magnetic toner 1, making it easier to manufacture the toner and improving fixing properties. be. still,
- The arrows in the figure indicate the direction of magnetization. Furthermore, the insulating layer 34 has a structure in which a large number of microelectrodes made of a conductive material such as iron are scattered on the surface, and the microelectrodes are electrically connected to each other by the insulating material. It is in an insulated state.

The Jl structure of the developing roller in the developing device of the present invention is as follows:
Consists of a V# layer member 4 that includes at least an insulating layer and a magnetic field generation layer on the surface of which are dotted with microelectrodes, and a drive roller 3 that drives the thin layer member 4, and an independent conductive layer as a component. In addition, it is possible to add conductivity to the magnetic field generation layer, and in addition, it is possible to provide a protective FiM to improve durability, and to provide an intermediate layer to improve moldability. It is also possible to combine the functions of multiple layers into a single layer. Furthermore, the magnetic field generation layer 32 can be used in various magnetized states such as line magnetization, grid magnetization, and spiral magnetization. Alternatively, a magnetic field generating layer in the form of a film that has been magnetized in advance may be appropriately disposed on the developing roller by means such as adhesion.

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, toner conveyed by a developing roller consisting of a cylindrical NNi member having an insulating layer on which microelectrodes are dotted on at least the surface and a driving roller is developed. In the developing device, by arranging a magnetic field generation layer on a cylindrical thin film member, toner with a stable charge amount is stably held and transported by leakage magnetic flux at a minute pitch.
It is possible to provide a developing device with less temperature unevenness and soil blurring. Further, it is possible to reduce unnecessary waste toner, provide a developing device with low running cost, and have the effect of providing a small, low-cost developing device with a simple structure. In particular, it has a great effect on reducing the phenomenon of soil strain, which occurs significantly depending on the environment. In addition, we can provide a developing device that is compatible with both contact development and pressure development.In particular, when pressure development is used, it is possible to maximize the development electrode effect of the microelectrodes and form the highest resolution image. .

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 one-component magnetic development. .

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of the developing device of the present invention, FIG. 2 is a schematic cross-sectional diagram of another embodiment of the developing device of the present invention, and FIG. 3 is a schematic cross-sectional diagram of another embodiment of the developing device of the present invention. FIG. 3 is a diagram showing the layer structure of the N-layer member of the developing roller in FIG. l...Toner; 2...Developing roller 3.
... Drive roller; 4 ... Thin layer member 5 ... Base body
6...Magnetic field generation layer 7...Insulating layer;
8...Latent image carrier 33...Microelectrode or more

Claims (2)

[Claims] (1) One-component magnetic toner is conveyed to a development area by a developing roller having an insulating layer formed by dotting a plurality of microelectrodes on at least the surface, and the one-component magnetic toner is developed on a latent image carrier. In the developing device, the developing roller has at least a cylindrical thin film member and a drive roller that contacts at least a portion of an inner circumferential side of the cylindrical thin film member, and the thin film member has at least a magnetic field generating layer. Characteristic developing device. (2) The developing device according to claim 1, wherein the thin film member is pressed against the latent image carrier.