JPH0421882A - Developing device - Google Patents

Abstract

PURPOSE:To make the carrying quantity of toner uniform and the toner a thin layer and to stably form an image that the irregularity of density is small by making the toner held on a thin film member having a magnetic field generation layer the thin layer with the aid of a blade which is made to be in press-contact with a driving roller through the thin film member. CONSTITUTION:A developing roller 2 carrying the toner 1 is constituted of the driving roller 3 and the cylindrical thin film member 4 which is externally provided to the outside circumference of the driving roller 3 by leaving excessive length. The cylindrical thin film member 4 is constituted by disposing the magnetic field generation layer 6 on a substrate 5 having elasticity and electrical conductivity. Then, the magnetic toner 1 is held by a leakage magnetic flux on the outside circumference of the magnetic field generation layer 6 and the toner 1 of the thin layer is carried by rotating the developing roller 2 under a state that the toner is regulated to be a proper quantity by the plate-like elastic blade 7. Since the holding force of the toner is due to a magnetic field formed by the generation layer 6, it has sufficient intensity and it is uniform. As the result, the toner is easily made the thin layer by the blade 7. Thus, the toner of the stable and uniform thin layer is supplied and excellent developing without the irregularity of the density is realized.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a developing device using -component 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 the layer thickness before regulation has large local variations. However, there were also variations in the toner holding power, and it was difficult to make the amount of toner conveyed uniform by the press-contact blade. Therefore, the layer thickness of the toner conveyed to the development area is uneven, causing unevenness in droplet size. Furthermore, since the toner retention force is small, there is a problem in that a smearing phenomenon is likely to occur. In addition, the amount of charge of the ) toner is sensitive to the environment such as humidity, and the toner holding power and toner transport amount are also likely to fluctuate, resulting in poor environmental stability and a lack of reliability.

The present invention is intended to solve these problems, and its purpose is to be able to supply a stable, uniform thin layer of toner to the development area, and to provide a good level of humidity without uneven humidity using -component magnetic toner. An object of the present invention is to provide a developing device that enables development. Another object is to provide a developing device that has a simple structure and can produce a uniform thin layer. Still another object is to provide a developing device that is highly reliable in the face of environmental changes and long-term durability.

[Means for Solving the Problems] The developing device of the present invention includes a developing roller having at least a cylindrical thin film member and a drive roller that contacts at least a portion of the inner peripheral side of the cylindrical thin film member, and the developing roller has a cylindrical thin film member. In a developing device that develops the toner by holding the toner on top, regulating the layer thickness with a blade, and bringing the excess portion of the thin film member into elastic contact with the photoreceptor, the toner is magnetic and the thin film member has at least , it has a magnetic field generation layer, at least one of the drive roller and the blade has elasticity, and the layer thickness of the toner is regulated at the portions that are pressed against each other.

Further, the developing device of the present invention is characterized in that the blade has at least a soft magnetic material as a component.

[Function] According to the above configuration of the present invention, the toner retention force is based on the magnetic field formed by the magnetic field generation layer, so the toner retention force is sufficient and uniform, and it is easy to thin the toner layer using a blade. In other words, since a thin magnetic field generation layer is used that is magnetized at a minute pitch, the magnetic field lines that start from one pole and are guided to the other pole close to the thin film member close to the surface of the magnetic field generation layer. , the layer of toner captured and held by the lines of magnetic force becomes thin, and toner is not held in excess in the first place. Furthermore, magnetization can be performed at a magnetization reversal pitch of 3 around the particle size of the toner, and since the lines of magnetic force are closed in almost one layer of toner, it is also possible to hold almost one layer of toner. Therefore, it is possible to thin the toner layer to some extent during transportation before cutting the toner with the blade, so it is possible to cut the toner into a uniform thin layer by gently cutting the toner with the blade that is softly pressed against the developing roller. At the same time,
There is more leeway in blade settings, and a developing roller that is highly reliable in terms of environmental changes and long-term durability can be obtained.

In other words, it is possible to form a uniform and thin toner layer (or a thin magnetic brush layer with a minute pitch) on the developing roller, reducing density unevenness caused by variations in toner layer thickness, and achieving high resolution development. It can be carried out.

Further, since the toner retention force is achieved by magnetic force and has sufficient strength, it is possible to prevent ground force blurring.

Furthermore, by using magnetic force as the toner holding force, fluctuations in the holding force due to the environment can be reduced, and a highly reliable developing device with excellent environmental stability can be provided.

In addition, by constructing the blade using soft magnetic material,
The blade is pressed against the developing roller by the magnetic force generated by the magnetic field generation layer, which simplifies the configuration of the blade and makes the contact pressure uniform, making it easier to form a uniform thin layer of toner and achieve high moisture content without unevenness. You can obtain high quality images.

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 toner 1 is constituted by a driving roller 3 that is rotationally driven and has a friction portion on its outer periphery, and a cylindrical thin film member 4 that is sheathed with a surplus portion left on the outer periphery of the driving roller 3. The cylindrical thin film member 4 has a structure in which a magnetic field generating layer 6 is disposed on a base body 5 having elasticity and conductivity, and the magnetic toner 1 is retained by the leakage magnetic flux around the outer periphery of the magnetic field generating layer 6, and the non-magnetic toner is retained. Alternatively, a thin layer of toner 1 is conveyed by rotating the developing roller 2 while regulating the appropriate amount with a plate-like elastic blade 7 made of magnetic metal or resin. The toner 1 conveyed to the development gap portion where the latent image carrier 8 composed of the supporting electrode 9 and the electrostatic image holding layer 10 and the developing roller 2 are close to each other is affected by the potential contrast of the latent image carrier 8 and the development bias. In response to the developing electric field formed by the application means 11, the electrostatic latent image adheres to the latent image carrier 8 and is visualized. The elastic blade 7 may be made of a plate-shaped metal, an insulating material that imparts a desired polar charge to the toner, such as PMMA for negatively charged polystyrene toner, or a metal surface coated with an insulating material. or an insulating material with metal plated on its surface.

Furthermore, when a soft magnetic material such as permalloy is used, it is attracted by the magnetic field of the magnetic field generation layer 6 and is pressed against the developing roller 2, so there is no need to mechanically press the elastic blade 7, resulting in low positional accuracy. can also be configured. Furthermore, when the elastic blade 7 is made of a conductive material and a predetermined bias is applied, the amount of charge on the toner 1 is stabilized.

Using a developing device as shown in FIG.
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 tailing or blurring at the edge of the image, and the OD value is 1.
．． It was possible to stably form a solid image with uniform density at a high flow rate of 4 or more.

In FIG. 1, the drive roller 3 has a friction part made of natural rubber, silicone rubber, urethane rubber, etc. on the outer periphery of a resin or metal shaft, and rotates by pressing a thin film member 4 against the drive roller 3. It transmits driving force. Further, the thin film member 4 can be made of a metal thin film such as phosphor bronze, stainless steel, or nickel, or a resin thin film material such as nylon, polyimide, or polyethylene terephthalate. In order to obtain sufficient pressure contact with the body 8, it is preferable that the thickness be about 10 to 500 [μm]. Furthermore, the magnetic field generation layer 6 can be made of a known magnetic recording material or magnet material, and has a film thickness of 100 [μm7-m] or less, preferably around 10 [μm1], and a minimum magnetization reversal pitch. By setting the thickness to 500 [μm] or less, preferably several tens to 100 [μm], it is possible to easily thin the toner layer by the elastic blade 7 and reduce density unevenness. Furthermore, the magnetic field generating layer 6 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.

Further, as the toner used in the present invention, all toners known as component magnetic toners can be used.
Either resin-based toner or wax-based toner may be used. 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 FIG. 1, the present invention is not limited only to the configuration shown in the figure. Further, each arrow indicates the direction of rotation of the member =8-, but this does not limit the present invention. Further, the latent image end holder 9 can also be in the form of a belt, and the developing method can be used regardless of whether it is regular development or reversal development.

FIG. 2 is a diagram showing a state in which the blades are in pressure contact in another embodiment of the present invention. As shown in FIG. 2, when the edge portion of the blade 27 is pressed against the drive roller 3 via the thin film member 4, thinning is efficiently performed. The thickness of the blade does not have to be uniform in both the press-contact state shown in FIG. 1 and the press-contact state shown in FIG. For example, by making the side that contacts the developing roller thinner, the developing roller side will flex more and the contact will be smoother.

FIG. 3 is a diagram showing a state in which the blades are in pressure contact in still another embodiment of the present invention. In FIG. 3, a blade 37 made of acrylic resin with a high modulus of elasticity is pressed against a drive roller 3 made of silicone rubber with a low modulus of elasticity through a thin film member 4. In this embodiment, the blade 37 deforms and presses the drive roller 3, making it possible to uniformly form a thin layer of the toner 1 with a simple structure.

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 held on a thin film member having a magnetic field generating layer magnetized at a minute magnetization reversal pitch is pressed against a drive roller through the thin film member. By forming a thin layer using a blade, it is possible to stably form an image with a uniform toner conveyance amount in a thin layer and less temperature unevenness, even though the developing device has a simple structure, is small, and is low cost. In particular, by forming a magnetic field with a minute pitch and holding the toner on the developing roller with uniform and sufficient holding force, it is easy to thin the toner with the blade, and the allowable range of settings such as blade position and elastic modulus Since the toner is spread out, the amount of toner conveyed can be stabilized against environmental changes and long-term durability, and a highly reliable developing device that can be used for both contact development and pressure development can be provided. In addition, since the toner retention force is based on magnetic force, there is little variation due to environmental factors such as temperature and humidity, and the elastic blade makes it easy to form a uniform thin layer of toner, making it a highly reliable developing device that is stable against the environment. can be provided.

Further, by simultaneously thinning the toner and rubbing the toner with a blade, it is possible to apply a triboelectric charge of a predetermined polarity to the toner, thereby reducing toner that is charged to the opposite polarity. As a result, it is possible to provide a developing device that prevents soil blurring, reduces unnecessary waste toner, and has low running costs.

In addition, by composing the blade with a soft magnetic material and pressing the blade against the developing roller using magnetic force, a uniform thin layer of toner can be formed even if the mechanical precision of the blade is low. This has the effect of providing a developing device that can produce high-quality images.

Therefore, in the -component development method, the developing device of the present invention has the following features:
This has the excellent effect of providing a developing device that can produce high-resolution images with little temperature unevenness.

[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 diagram showing a state of pressure contact of the blade in another embodiment of the present invention, and FIG. It is a figure which shows the press-contact state of the blade in Example. 1... Toner 2... Developing roller 3... Drive roller 4... Thin film member 6... Magnetic field generating layer 7... Elastic blade 8... Latent image carrier and above

Claims (2)

[Claims] (1) The developing roller has at least a cylindrical thin film member and a drive roller that contacts at least a portion of the inner circumferential side of the cylindrical thin film member, holds the toner on the thin film member, and uses a blade to thicken the layer. In the developing device, the toner is magnetic, and the thin film member has at least:
A developing device comprising a magnetic field generating layer, at least one of the driving roller and the blade having elasticity, and regulating the layer thickness of the toner at a portion pressed against each other. (2) The developing device according to claim 1, wherein the blade comprises at least a soft magnetic material.