JPH03259277A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a developing device whose structure is simple and which is miniaturized and made inexpensive and to stably form an image of high resolution and high quality by providing a magnetic field generation layer to a cylindrical thin film member. CONSTITUTION:A developing device 7 carries magnetic toner 8 and executes developing. A developing roller 9 carrying the toner 8 is constituted of a driving roller 10 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 11 which is externally provided to the outside circumference of the roller 10 by leaving excess length. Then, the magnetic field generation layer 12 is disposed on the member 11 and the magnetic toner 8 is directly held on the developing roller 9 by the leakage magnetic flux of the outside circumference of the layer 12. Besides, the thin layer toner 8 is carried by rotating the developing roller 9 in a state that it is regulated to proper quantity by a plate-like blade 13. In such a way, the toner is carried near the surface of the thin magnetic field generation layer 12 and the developing roller 9 is constituted of a single rotating body. Thus, the structure of the developing roller is simplified and miniaturized. Besides, it is made light in weight and inexpensive. Moreover, the developing of the high resolution and the 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, and more specifically, a developing device that conveys the one-component magnetic toner by a developing roller having a cylindrical thin film member. The present invention relates to a developing device that performs development.

[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. Furthermore, when toner is developed on a latent image bearing member such as a photoreceptor, uncharged toner or toner with a non-regular polarity is developed in the non-image area, and there is significant ground blur (toner is not formed in 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 a one-component magnetic toner by a developing roller and develops the one-component magnetic toner onto a latent image carrier, in which the developing roller is a cylindrical thin film. It is characterized in that it has at least a drive roller that contacts at least a portion of the inner peripheral side of the member and the cylindrical thin film member, and the thin film member 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.

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 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 generating 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, and the thickness of the toner layer can be reduced. It is possible to reduce density unevenness due to fluctuations, toner is held on the developing roller by magnetic force, to reduce ground force blur, and to perform development with high resolution and high print quality. moreover,
The magnetic binding force reduces contamination caused by toner scattering, reduces soil burr, and reduces unnecessary waste toner.
The image forming apparatus can be made smaller and lower in cost and requires less maintenance, and it is also possible to reduce toner consumption and 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, frictional charging between the thin film member and the toner can be stably performed, and temporal fluctuations in the developing temperature can be reduced.

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

[Example] FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus using a developing device of the present invention, in which a latent image carrier 1 is coated with an organic or inorganic photoconductive material on a conductive support 2. After the photosensitive layer 3 is charged using a charger 4 such as a corona charger or a charging roller, a laser or L
Light emitted from a light source 5 such as an ED is selectively irradiated onto the photosensitive layer 3 according to an image through an imaging optical system 6 to obtain a potential contrast and form an electrostatic latent image. On the other hand, the developing device 7 conveys and develops the magnetic toner 8, and the developing roller 9 that conveys the toner 8 is rotatably driven and has a friction portion on the outer periphery of the driving roller IO and the driving roller 10. It is composed of a cylindrical thin film member 11 that is covered with an excess length, and a magnetic field generating layer 12 is disposed on the cylindrical thin film member 11.
A plate-shaped blade 1 made of non-magnetic or magnetic metal or resin is arranged to hold the magnetic toner 8 directly on the developing roller 9 by leakage magnetic flux around the outer periphery of the magnetic field generation layer 11.
3, the developing roller 9 is rotated to convey a thin layer of toner 8 with the amount regulated to an appropriate amount. The toner 8 reaches the development gap where the latent image carrier 1 and the development roller 9 are close to each other.
When the latent image carrier 1 is conveyed, 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 8 charged according to the developing electric field adheres to the latent image carrier 1, and the electrostatic latent image is visualized. Imaged. Further, a toner image is transferred onto the recording paper 16 using a transfer device 15 such as a corona transfer device or a transfer roller, and the toner is fixed on the recording paper using heat or pressure to obtain a desired image on the recording paper. It is. 1st
Using an image forming apparatus as shown in the figure, 600 [
When line images, character images, and solid images of [DPI] were continuously formed on 10,000 sheets, the result was 600 [DPI].
PI] 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 with a high density of 4 or more, and there is no ground force blur on the recording paper as well as on the latent image carrier, and waste toner I can be significantly reduced. Ta.

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 convey the thin layer of toner 8. The developing roller 9 is pressed against the latent image carrier 1 with a predetermined pressure.
When the upper toner 8 is conveyed to the pressure contact part, the toner 8 charged according to the potential contrast of the latent image carrier 1 and the developing electric field by the developing bias applying means 14 adheres to the latent image carrier 1, forming an electrostatic latent image. is visualized. When we continuously formed 10,000 sheets of 600 [DPI] line images, character images, and solid images using the image forming apparatus shown in Figure 2, the 600 [DPI] line images did not become thick. It is stably formed and has the highest resolution of line pair images, and there is no tailing or blurring at the edges of the image, and high density solid images with an OD value of 1.4 or more can be stably formed and recorded. Not only was there no ground force blur on the paper, but there was also no ground force blur on the latent image carrier, making it possible to significantly reduce waste toner 1.

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, NBR, etc. on the outer periphery of a resin or metal shaft. The thin film member 11 is pressed against the drive roller 10 to transmit rotational driving force. The thin film member 11 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 carrier, it is preferable that the magnetic field generation layer 12 has a thickness of about 10 to 500 [μml].Furthermore, the magnetic field generation layer 12 can be made of a known magnetic recording material or magnet material, and even more For details, please refer to Fe
, Ni, Co, Mn, a magnetic material containing at least one kind of element, for example, y-Fe203,
Ba-Fe, Ni-Co, Co-Cr, Mn-Al, etc. can be used, and the film thickness is preferably 100 [μm] or less, preferably 10
[Thin film around 1 μm, minimum magnetization reversal pitch 100
[μm] or less, the toner can be uniformly made into a thin layer, and at the same time, variations in the amount of toner conveyed on the developing roller due to the formation of the magnetic brush can be suppressed to a minute pitch, thereby reducing density unevenness. Further, as the toner used in the present invention, all toners known as one-component magnetic toners can be used, and the composition of the developer may be either resin-based toner or wax-based toner, as is known in the art. It is made by adding magnetic powder, colorants, external additives, and other additives to resin, 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. 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(a) 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 disposed on a thin film member 31.
is arranged, and the magnetic field generation layer 32 has a magnetization reversal pitch of 100.
By horizontally magnetizing the magnetic field generating layer 32 to a value of [μm] or less, a minute toner chain is formed by the toner 33 on the magnetic field generating layer 32, and a thin and stable toner layer is obtained. In addition, the thin film member 3 is made of a resin thin film in which a conductive metal thin film or a conductive material such as carbon black is dispersed in an elastic resin.
1, a developing bias voltage can be applied to the thin film member 31 to improve the developing electrode effect and obtain a high-resolution image. Furthermore, as shown in FIG. 3(b), by magnetizing the magnetic field generation layer 34 in the perpendicular direction, it is possible to increase the density of the magnetization reversal pitch to about the toner particle size (approximately 10 [μm]). , evenly layered toner-35
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 the toner 35, thereby facilitating the production of the toner and improving its fixing properties. In the example shown in FIG. 3(b), by providing a magnetic circuit made of soft magnetic material on the back surface of the magnetic field generating layer 34, an even larger magnetic field can be obtained on the surface of the magnetic field generating layer 34. still,
The arrows in the figure indicate 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 conductive layer 42 is disposed on a thin film member 41, and a magnetic field generating layer 43 is disposed on the conductive layer 42. , by magnetizing the magnetic field generating layer 43 in the horizontal direction so that the magnetization reversal pitch is 1.00 [μm] or less, the magnetic field generating layer 43
A minute toner chain is formed by the toner 44 on the top, and a stable toner layer is obtained with eight layers. Therefore, by applying a developing bias voltage to the conductive layer 42, it is possible to improve the developing electrode effect and obtain a high-resolution image. As the material for the thin film member 41, a resin thin film is suitable.

As the material of the conductive layer 42, in addition to materials containing conductive metals such as A1 and Ni, conductive materials such as carbon black can be used, and the conductive layer 42 is formed by means such as adhesion, coating, plating, etc. can do. Note that the arrows in the figure indicate the direction of magnetization, and the magnetic field generation layer 43 may be a perpendicularly magnetized film.

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 disposed on a thin film member 51, and a conductive layer 53 is disposed on the magnetic field generating layer 52. and the magnetic field generation layer 52 has a magnetization reversal pitch of 100 [μm]
By magnetizing in the horizontal direction as shown below, a minute toner chain is formed by the toner 54 on the conductive layer 53, resulting in a thin and stable toner layer. Therefore, by applying a developing bias voltage to the conductive layer 53, it is possible to improve the developing electrode effect and obtain a high-resolution image.

If the conductive layer 53 is formed of a metal thin film containing Ni, Cr, etc., the conductive layer 53 will serve as a protective film for the magnetic field generation layer 52. As a result, the life of the developing roller can be extended. Note that the arrows in the figure indicate the direction of magnetization, and the magnetic field generation layer 52 may be a perpendicularly magnetized film.

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 6 is disposed on a thin film member 61.
2 is disposed, an insulating layer 63 is disposed on the magnetic field generation layer 62,
By magnetizing the magnetic field generation layer 62 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, the insulating layer 6
A minute toner chain is formed by the toner 64 on the toner 3, resulting in a thin and stable toner layer. By providing the insulation N63 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 by using a resin with excellent wear resistance such as fluorocarbon resin for the insulation layer 63. It can also be used as a protective layer for the magnetic field generation layer 62. Note that the arrows in the figure indicate the direction of magnetization, and the direction of the magnetic field generation layer 6
2 may be a perpendicular magnetization film.

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 conductive layer 72 is disposed on a thin film member 71, and a magnetic field generating layer 73 is disposed on the conductive layer 72. However, by disposing an insulating layer 74 on the magnetic field generating layer 73 and magnetizing the magnetic field generating layer 73 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, the toner 7 is formed on the insulating layer 74.
5, a minute toner chain is formed and a thin and stable toner layer is obtained. In this case, the conductive layer 72 not only has a developing electrode effect, but also covers the surface of the thin film member 71 with the conductive layer 72.
2, the magnetic field generating layer 73 can be formed easily. By providing the insulating layer 74 at the contact portion 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 for the insulating layer 74. It can also be used as a protective layer for the magnetic field generation layer 73. Note that the arrows in the figure indicate the direction of magnetization, and the magnetic field generation layer 73 may be a perpendicularly magnetized film.

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 8 is disposed on a thin film member 81.
2 is disposed, a conductive layer 83 is disposed on the magnetic field generation layer 82,
By disposing an insulating layer 84 on the conductive layer 83 and magnetizing the magnetic field generation layer 82 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, toner 8 is formed on the insulating layer 84.
5, a minute toner chain is formed and a thin and stable toner layer is obtained. In this case, not only can a high-resolution image be obtained by using the conductive layer 83 as a developing electrode close to the latent image carrier, but also by providing the insulating layer 84 in the contact area with the toner 85, the charging polarity of the toner 85 can be changed. In addition to being able to control the amount of charge and the amount of charge, it also functions as a protective layer for the conductive layer 83, which is the development electrode, and can maintain a stable development electrode effect.

Note that the arrows in the figure indicate the direction of magnetization, and the magnetic field generation layer 82 may be a perpendicularly magnetized film.

In addition to the above examples of layer configurations, it is also possible to create a structure in which the functions of multiple layers are combined into a single layer, or a layer structure in which an intermediate layer is provided between each layer to facilitate bonding between the layers. A configuration is also possible in which the developing electrode effect is improved by disposing it in a predetermined layer.

FIGS. 9 to 11 are schematic diagrams showing the magnetized state of the magnetic field generating layer of the developing roller in the embodiment of the present invention.

FIG. 9 is a schematic diagram of the magnetized state of the magnetic field generation layer in the embodiment of the present invention, and the magnetic field generation layer 91 is magnetized in a lattice shape so that N poles and S poles appear alternately. When magnetized in the horizontal direction so that the minimum magnetization reversal pitch is 50 to 100 [μm], 500 [Gaus] on the magnetic field generation M91
It is possible to obtain a magnetic flux density greater than or equal to [s] and to stably hold the toner. Further, by magnetizing in the perpendicular direction, it is possible to obtain magnetization with an even narrower pitch and even higher magnetic flux density. Note that the magnetization state is not limited to a lattice shape, and a thin toner layer can be stably formed even if the lattice is magnetized at an angle or a portion of the lattice is magnetized.

FIG. 10 is a schematic diagram of the magnetized state of the magnetic field generating layer in another embodiment of the present invention, in which the magnetic field generating layer 101 has N poles and S poles arranged alternately in the circumferential direction or axial direction of the developing roller. It is magnetized so that it appears.

When magnetized in the horizontal direction so that the minimum magnetization reversal pitch is 50-100 [μm], 50
A magnetic flux density of 0 [Gauss] or more can be obtained and the toner can be stably held. By creating such a magnetized state, the number of magnetized poles is relatively small and magnetization is easy.

Further, by magnetizing in the perpendicular direction, it is possible to obtain magnetization with an even narrower pitch and even higher magnetic flux density.

FIG. 11 is a schematic diagram of the magnetized state of the magnetic field generating layer in still another embodiment of the present invention, and the magnetic field generating layer 111 is arranged so that north and south poles appear alternately in a spiral along the developing roller. It is magnetized to. Minimum magnetization reversal pitch is 50 to 10
When magnetized in the horizontal direction so as to have a magnetic flux density of 0 [μm], a magnetic flux density of 500 [Gauss] or more can be obtained on the magnetic field generation layer 111, and the toner can be stably held. By creating such a magnetized state, the number of magnetized poles is relatively small and magnetization is easy. Further, by magnetizing in the perpendicular direction, it is possible to obtain magnetization with an even narrower pitch and even higher magnetic flux density.

In addition to the f-magnetic state described above, other methods are possible, such as a method of magnetizing the magnetization reversal direction in a state close to random, or a method of magnetizing the shape of the magnetic pole in accordance with the shape of the magnetizing yoke, such as a circular shape. By magnetizing the magnetic field generation layer so that the minimum magnetization reversal interval is sufficiently small (for example, 100 [μm] or less), a stable thin toner layer can be formed on the developing roller. Alternatively, the magnetization may be carried out directly on the developing roller, or a film-like magnetic field generating layer may be previously magnetized and then appropriately disposed on the developing roller by means of adhesion or the like.

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, it is possible to provide a developing device in which the amount of toner conveyed is stable and there is little density unevenness by disposing a magnetic field generation layer in a cylindrical thin film member. is possible,
It is possible to provide a developing device that reduces contamination caused by toner scattering, reduces unnecessary waste toner, is easy to maintain, and has low running costs, and it is possible to provide a developing device that is simple in structure and small in size and low in cost. 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 and 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 one-component magnetic development. .

[Brief explanation of drawings]

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 the thin film member in still another embodiment of the present invention, and FIG. 9 is a diagram showing the layer structure of the thin film member in still another embodiment of the present invention. FIG. 1O is a schematic diagram of the magnetized state of the magnetic field generating layer in another embodiment of the present invention, and FIG. 11 is a schematic diagram of the magnetized state of the magnetic field generating layer in another embodiment of the present invention. Schematic diagram of magnetic states. 2... Above the magnetic field generation layer

Claims (4)

[Claims] (1) One-component magnetic toner is conveyed by a developing roller,
In the developing device for developing the one-component magnetic toner onto a latent image carrier, the developing roller includes at least a cylindrical thin film member and a drive roller that contacts at least a portion of an inner circumferential side surface of the cylindrical thin film member. . A developing device, wherein the thin film member has at least a magnetic field generating 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.