JP2906544B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using a one-component magnetic toner, and more particularly, to conveying a one-component magnetic toner by a developing roller having a cylindrical thin film member. The present invention relates to a developing device for developing.

2. Description of the Related 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 circumference to a drive roller to a photoconductor. The non-magnetic toner can be conveyed and developed in close contact.

[Problems to be Solved by the Invention] However, in the above-described conventional technology, the force for holding the toner on the developing roller depends on the electrostatic image force and the adhesive force. Was. Further, when the toner is developed on a latent image carrier such as a photoreceptor, an uncharged toner or a toner having a non-standard polarity is developed in a non-image portion,
On the latent image carrier, only an image having a remarkably large amount of background fogging (a state in which toner adheres to the non-image portion) is obtained, and only toner of a normal polarity is transferred to the recording paper. Although an image can be obtained, a large amount of toner is discarded unnecessarily without being transferred, which is not only uneconomical, but also requires a sufficient space occupied by a waste toner container, thus increasing the size of the image forming apparatus.

Therefore, the present invention solves such a problem,
It is an object of the present invention to provide a developing device in which the amount of toner transported is stable and density unevenness is small. Still another object is to provide a developing device which is less contaminated by toner scattering and can reduce unnecessary waste toner.
Still another object is to provide a developing device which can be applied to a small-sized and low-cost image forming apparatus having a simple structure. 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 is a developing device in which a one-component magnetic toner is transported by a developing device and the one-component magnetic toner is developed on a latent image carrier. A thin-film member, and a driving roller for rotating and transporting the thin-film member in partial contact with the inner peripheral surface of the thin-film member. The thin-film member further generates a magnetic field on a side facing the latent image carrier. Having layers,
The magnetic field generation layer is magnetized in a lattice shape in which N poles and S poles appear alternately, and has a magnetization reversal pitch of 100 μm or less.

[Operation] According to the above configuration of the present invention, the structure of the developing roller is simply simplified by conveying the toner near the surface of the thin magnetic field generating layer and forming the developing roller with a single rotating body. Instead, a compact, lightweight and low-cost developing roller can be obtained. Also, the thin magnetic field generating layer is magnetized at a fine pitch to form a uniform thin toner layer (or a fine pitch magnetic brush thin layer) on the developing roller. Reduces uneven density due to fluctuations, reduces toner fog by holding toner on the developing roller with magnetic force,
High resolution and high print quality development can be performed. Furthermore, the magnetic binding force reduces contamination due to toner scattering,
By reducing the background fog and the unnecessary waste toner, the size and cost of the image forming apparatus can be reduced and the maintenance thereof can be reduced, and the toner consumption can be reduced and the running cost can be reduced.

Further, according to the above configuration of the present invention, even when the thin film member is pressed against the latent image carrier and development is performed, development with high resolution and high print quality without background fog can be performed.

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

Further, by providing the insulating layer on the thin film member, the triboelectric charging between the thin film member and the toner can be stably performed, and the time variation of the development density can be reduced.

 Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus using a developing device of the present invention, in which a latent image carrier 1 includes a conductive support 2.
Is coated with a photosensitive layer 3 having organic or inorganic photoconductivity, and the photosensitive layer 3 is charged using a charger 4 such as a corona charger or a charging roller.
Light emitted from a light source 5 such as an LED is selectively irradiated on the photosensitive layer 3 through an imaging optical system 6 in accordance with an image to obtain a potential contrast to form an electrostatic latent image. On the other hand, the developing device 7 transports and develops the magnetic toner 8, and the developing roller 9 that transports the toner 8 is driven to rotate and has a driving roller 10 having a friction portion or the like on the outer periphery and an outer periphery of the driving roller 10. A magnetic field generating layer 12 is provided on the cylindrical thin film member 11 and is provided with an extra length. The magnetic toner 8 is formed by a leakage magnetic flux on the outer periphery of the magnetic field generating layer 11. Transporting the thin layer toner 8 by rotating the developing roller 9 in a state in which the developing roller 9 is held directly on the developing roller 9 and regulated to an appropriate amount by a plate-like blade 13 made of non-magnetic or magnetic metal or resin. It is. When the toner 8 is transported to the developing 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 electric field 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. 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. Using an image forming apparatus as shown in FIG. 1, 600 [DPI] line images, character images and solid images were continuously formed over 10,000 sheets, and the 600 [DPI] line images were not thickened. It is formed stably and has no tailing or background fogging at the edges of the image.It can stably form high-density solid images with an OD value of 1.4 or more. There was no ground fog on the carrier, and the amount of waste toner was significantly reduced.

FIG. 2 is a schematic cross-sectional view 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 and the same names as those in FIG. I do. The developing device 21 transports and develops the magnetic toner 8, and the developing roller 9 that transports the toner 8 directly holds the magnetic toner 8 on the developing roller 9 by the leakage magnetic flux on the outer periphery of the magnetic field generation layer 11. Then, the layer is appropriately thinned by a thin leaf 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 toner 8. The developing roller 9 is pressed against the latent image carrier 1 at a predetermined pressure, and when the toner 8 on the developing roller 9 is conveyed to the pressing portion, the potential contrast of the latent image carrier 1 and the developing bias applying means 14 are used. The toner 8 charged in accordance with the developing electric field adheres to the latent image carrier 1, and the electrostatic latent image is visualized. When an image forming apparatus as shown in FIG. 2 was used to continuously form a line image of 600 [DPI], a character image and a solid image over 10,000 sheets, the line image of 600 [DPI] was not thickened. It is possible to stably form a high-density solid image with an OD value of 1.4 or more with no line tailing or ground fogging at the edge of the image. As a matter of course, there was no ground fog, and there was no ground fog on the latent image carrier, so that the amount of waste toner could be greatly reduced.

In FIGS. 1 and 2, the drive roller 10 is provided with a friction portion on the outer periphery of a resin or metal shaft using natural rubber, silicon rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, NBR, or the like. The thin film member 11 is pressed against the driving roller 10 to transmit a 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. 10-500 to obtain sufficient pressure contact with
[Μm] is preferable. Furthermore, a magnetic field generating layer
12, known materials can be used as a magnetic recording material or a magnet material, more specifically, Fe, Ni, Co, Mn, a magnetic material containing at least one element of, for example,
γ-Fe ₂ O ₃ , Ba-Fe, Ni-Co, Co-Cr, Mn-Al, etc. can be used, and the film thickness is 100 [μm] or less, preferably 10 [μm].
The thickness of the toner is reduced before and after, and the minimum magnetization reversal pitch is set to 100 [μm] or less to uniformly thin the toner. be able to. Further, as the toner used in the present invention, all toners known as one-component magnetic toner can be used, and any of resin-based toner and wax-based toner may be used. As is known, the composition of the developer is obtained by adding a magnetic powder, a colorant, an external additive, and other additives to a resin, and is prepared by a pulverization method, a polymerization method, or the like.

In FIGS. 1 and 2, the present invention is not limited only by the configuration shown in the drawings. Arrows indicate the rotation directions of the respective members, but do not limit the present invention.
Further, the developing method can be used regardless of whether it is regular development or reversal development.

FIGS. 3 to 8 show the layer configuration of the thin film member in the embodiment of the present invention.

FIG. 3 (a) is a view showing a layer structure of a thin film member according to an embodiment of the present invention, in which a magnetic field generating layer 32 is provided on a thin film member 31, and the magnetic field generating layer 32 is provided with a magnetization reversal pitch P of 100. [Μ
m] or less so as to be less than or equal to
A minute toner chain of the toner 33 is formed on the magnetic field generating layer 32, and a thin and stable toner layer is obtained. Also,
By dispersing a conductive material such as a conductive metal thin film or carbon black in an elastic resin to form a thin film member 31 with a resin thin film, a developing bias voltage is applied to the thin film member 31 to improve a developing electrode effect. To obtain a high-resolution image. Further, as shown in FIG.
By magnetizing 34 in the vertical direction, the magnetization reversal pitch can be increased to the particle size of the toner (around 10 [μm]), and a uniform thin layer of toner 35 can be formed. In addition, since a strong magnetic field is obtained on the surface of the magnetic field generating layer, it is possible to reduce the content of the magnetic powder in the toner 35, thereby facilitating the production of the toner and improving the fixing property. In the example of FIG. 3 (b), a larger magnetic field can be obtained on the surface of the magnetic field generating layer 34 by providing a magnetic circuit of a soft magnetic material on the back surface of the magnetic field generating layer 34. The arrow in the figure indicates the direction of magnetization.

FIG. 4 is a view showing a layer structure of a thin film member according to another embodiment of the present invention, in which a conductive layer 42 is provided on a thin film member 41, and a magnetic field generating layer 43 is provided on the conductive layer 42. , Magnetic field generation layer 43
Is magnetized in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, so that the toner is
A minute toner chain is formed by 44, and a thin and stable toner layer is obtained. Therefore, a developing bias voltage is applied to the conductive layer 42 to improve the developing electrode effect, and a high-resolution image can be obtained. As a material of the thin film member 41, a resin thin film is preferable. As a material for the conductive layer 42, a conductive material such as carbon black can be used in addition to a material containing a conductive metal such as Al or Ni, and the conductive layer 42 is formed by means such as adhesion, coating, plating, or the like. can do. The arrow in the figure indicates the direction of magnetization, and the magnetic field generating layer 43 may be a perpendicular magnetization film.

FIG. 5 is a diagram showing a layer configuration of a developing roller according to still another embodiment of the present invention, in which a magnetic field generating layer 52 is provided on a thin film member 51, and a conductive layer 53 is provided on the magnetic field generating layer 52. By magnetizing the magnetic field generating layer 52 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, a minute toner chain of the toner 54 is formed on the conductive layer 53, and the thin layer is stable. A toner layer is obtained. Therefore, a high-resolution image can be obtained by applying a developing bias voltage to the conductive layer 53 to improve the developing electrode effect. If the conductive layer 53 is formed of a metal thin film containing Ni, Cr, or the like, the conductive layer 53 functions as a protective film for the magnetic field generating layer 52, and the life of the developing roller can be extended. The arrow in the figure indicates the direction of magnetization, and the magnetic field generation layer 52
May be a perpendicular magnetization film.

FIG. 6 is a view showing a layer structure of a thin film member according to still another embodiment of the present invention.
Is disposed on the insulating layer 63 by disposing the insulating layer 63 on the magnetic field generating layer 62 and magnetizing the magnetic field generating layer 62 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less. In this case, a minute toner chain is formed by the toner 64, and a thin and stable toner layer is obtained. By providing the insulating layer 63 at the contact portion with the toner 64, it is possible to control not only the charge polarity and the charge amount of the toner 64, but also to use a resin having excellent wear resistance such as a fluorine resin for the insulating layer 63. Due to magnetic field generation layer
62 protective layers can also be used. The arrow in the figure indicates the direction of magnetization, and the magnetic field generation layer 62 may be a perpendicular magnetization film.

FIG. 7 is a diagram showing a layer structure of a thin film member according to still another embodiment of the present invention, in which a conductive layer 72 is provided on a thin film member 71, and a magnetic field generating layer 73 is provided on the conductive layer 72. And the magnetic field generating layer
An insulating layer 74 is provided on the insulating layer 74, and the magnetic field generating layer 73 is horizontally magnetized so that the magnetization reversal pitch becomes 100 [μm] or less. 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 allows the surface of the thin film member 71 to be smoothed by the conductive layer 72, thereby facilitating the formation of the magnetic field generating layer 73. Insulation layer 74
Not only can control the charge polarity and charge amount of the toner 75, but also generate a magnetic field by using a resin with excellent abrasion resistance such as fluoro resin for the insulating layer 74. The protective layer of the layer 73 can also be used.
The arrows in the figure indicate the direction of magnetization, and the magnetic field generation layer 73 may be a perpendicular magnetization film.

FIG. 8 is a view showing a layer structure of a thin film member according to still another embodiment of the present invention.
The conductive layer 83 is provided on the magnetic field generating layer 82, and the conductive layer 83 is provided.
An insulating layer 84 is provided on the insulating layer 83, and the magnetic field generating layer 82 is horizontally magnetized so that the magnetization reversal pitch is 100 [μm] or less. Is formed, and a thin and stable toner layer is obtained. In this case, not only can the conductive layer 83 be used as a developing electrode in the vicinity of the latent image carrier to obtain a high-resolution image, but also the insulating layer
By providing 84 at the contact portion with toner 85, toner 85
Control of the charge polarity and charge amount of
It functions as a protective layer for the conductive layer 83, which is a developing electrode, and can maintain a stable developing electrode effect. The arrows in the figure indicate the direction of magnetization, and the magnetic field generating layer 82 may be a perpendicular magnetization film.

In addition to the above layer configuration examples, various layer configurations such as a configuration in which the functions of a plurality of layers are integrated into one layer and a layer configuration in which an intermediate layer is provided between layers to facilitate bonding between layers are possible. It is also possible to adopt a configuration in which the developing electrode effect is improved by disposing the developing layer in a predetermined layer.

FIGS. 9 to 11 are schematic views 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 generating layer in the embodiment of the present invention. The magnetic field generating layer 91 is magnetized in a lattice shape such that N poles and S poles appear alternately. When magnetized in the horizontal direction so that the minimum magnetization reversal pitch becomes 50 to 100 [μm], a magnetic flux density of 500 [Gauss] or more is obtained on the magnetic field generating layer 91, and the toner can be stably held. Further, when magnetized in the vertical direction, it is possible to obtain magnetization at a narrower pitch and higher magnetic flux density. Note that the magnetized state is not limited to the lattice shape, and a thin toner layer can be stably formed even when the lattice is inclined or a part of the lattice is magnetized.

FIG. 10 is a schematic view of a magnetized state of a magnetic field generating layer in another embodiment of the present invention. In the magnetic field generating layer 101, N poles and S poles appear alternately in the circumferential direction or axial direction of the developing roller. Magnetized. Minimum magnetization reversal pitch is 50 to 10
When magnetized in the horizontal direction so as to be 0 [μm], a magnetic flux density of 500 [Gauss] or more is obtained on the magnetic field generation layer 111, and the toner can be stably held. With such a magnetized state, the number of magnetized poles is relatively small, and magnetizing is easy. Further, when magnetized in the vertical direction, it is possible to obtain magnetization at a narrower pitch and higher magnetic flux density.

FIG. 11 is a schematic view of a magnetized state of a magnetic field generating layer according to still another embodiment of the present invention. In the magnetic field generating layer 111, N poles and S poles alternately appear spirally along a developing roller. It is magnetized. Minimum magnetization reversal pitch is 50-100 [μ
m], the magnetic field generating layer
A magnetic flux density of 500 [Gauss] or more is obtained on 111, and the toner can be stably held. With such a magnetized state, the number of magnetized poles is relatively small, and magnetizing is easy. Further, when magnetized in the vertical direction, it is possible to obtain magnetization at a narrower pitch and higher magnetic flux density.

In addition to the above-mentioned magnetized state, a method of magnetizing the magnetization in a state in which the magnetization reversal directions are nearly random, a method of magnetizing the magnetic pole in accordance with the shape of the magnetized yoke such as a circle, and the like are possible. In this case, a stable toner thin layer can be formed on the developing roller by magnetizing the magnetic field generating layer so that the minimum magnetization reversal pitch is sufficiently small (for example, 100 [μm] or less). do not do. Further, the magnetization may be performed directly on the developing roller, or a film obtained by magnetizing the film-shaped magnetic field generating layer in advance may be appropriately disposed on the developing roller by bonding or the like.

Although the embodiments have been described above, the present invention can be widely applied not only to the above-described embodiments but also to a developing device such as an electrophotograph, and is particularly effective when applied to a printer, a copying machine, a facsimile, and a display.

[Effects of the Invention] As described above, according to the present invention, by providing a magnetic field generating layer on a cylindrical thin film member, it is possible to provide a developing device having a stable toner conveyance amount and less density unevenness. To provide a developing device that is easy to maintain and has a low running cost by reducing contamination caused by toner scattering, reducing unnecessary waste toner, and providing a compact, low-cost developing device with a simple structure. Therefore, there is an effect that a high-resolution and high-quality image can be stably formed. Further, it is possible to provide a developing device which can cope with any of the contact development and the pressure contact development. In particular, when the pressure contact development is used, the development electrode effect can be maximized to form the highest resolution image. Further, by providing a conductive layer or an insulating layer, the development electrode effect and the durability can be improved.

Therefore, the developing device of the present invention has an excellent effect of providing a developing device capable of obtaining a high-resolution image with less image defects such as background fogging and tailing in a one-component magnetic developing method. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus using a developing device of the present invention, FIG. 2 is a schematic cross-sectional view of an image forming apparatus using a developing device according to another embodiment of the present invention, and FIG. FIG. 4 is a diagram illustrating a layer configuration of a thin film member according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a layer configuration of a thin film member according to another embodiment of the present invention.
FIG. 5 is a view showing a layer structure of a thin film member according to still another embodiment of the present invention, FIG. 6 is a view showing a layer structure of a thin film member according to still another embodiment of the present invention, and FIG. FIG. 8 is a diagram showing a layer configuration of a thin film member in still another embodiment of the present invention, FIG. 8 is a diagram showing a layer configuration of a thin film member in still another embodiment of the present invention, and FIG. FIG. 10 is a schematic view of a magnetized state of a layer, FIG. 10 is a schematic view of a magnetized state of a magnetic field generating layer according to another embodiment of the present invention, and FIG. The schematic diagram of a magnetic state. DESCRIPTION OF SYMBOLS 1 ... Latent image carrier 7 ... Developing device 8 ... Toner 9 ... Developing roller 10 ... Driving roller 11 ... Thin film member 12 ... Magnetic field generating layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-37577 (JP, A) JP-A-63-226676 (JP, A) JP-A-64-65579 (JP, A) JP-A-1- 257882 (JP, A) JP-A-1-281476 (JP, A) JP-A-58-49969 (JP, A) JP-A-52-73044 (JP, A) JP-A-60-250376 (JP, A) JP-A-61-83565 (JP, A) JP-A-61-141468 (JP, A) JP-A-61-66371 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/08-15/095

Claims (1)

(57) [Claims] 1. A developing device which transports a one-component magnetic toner by a developing means and develops the one-component magnetic toner on a latent image carrier, wherein the developing means comprises a cylindrical thin film member, and A drive roller for rotating and transporting the thin film member in partial contact with the peripheral surface, the thin film member further has a magnetic field generating layer on a side facing the latent image carrier, and the magnetic field generating layer is A developing device characterized in that the N pole and the S pole are magnetized in a lattice pattern appearing alternately, and the magnetization reversal pitch is 100 μm or less.