JPH0451272A - Developing device - Google Patents

Abstract

PURPOSE:To stabilize a toner carrying quantity on a magnetic field generating layer and to carry out development so that base fogging and density irregularities are reduced by bringing at least, a part of a developing roller into contact with a drum-like thin film member and its inner peripheral side surface and providing a driving roller generating a magnetic field. CONSTITUTION:The developing roller 9 is rotated/driven and composed of the driving roller 10 generating the magnetic field, and the drum-like thin film member 11 on its outer periphery. Magnetic toner 8 is held on the thin film member 11 by the leakage magnetic flux of the driving roller 10, and regulated to a proper quantity by a thin plate spring-like elastic blade 13. In this state, the developing roller 9 is rotated to carry the thin layer toner 8. It is slid by a magnetic flux, to receive triboelectrification and the injection of a charge, so that the toner on the thin film member has a stable electrifying quantity to carry out sufficient development. The toner 8 is stuck to a latent image carrier 1 to actualize an electrostatic latent image. At this time, a developing electric field can be emphasized by pressing the thin film member to the latent image carrier, and a distance between the latent image carrier and the thin film member is regulated by the thickness of a toner layer, so that the developing electric field is stabilized, and a high-density and high-resolution image can be stably formed without having the base fogging.

Description

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

[Prior Art] As disclosed in Japanese Unexamined Patent Publication No. 63-226676, a conventional developing device elastically attaches a surplus 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.

[Problem M to be solved by the invention] However, in the above-mentioned conventional technology, the force for holding 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. there were.

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, resulting in significant ground force blur on the latent image carrier. However, when used in an image forming device such as electrophotography, only toner of the correct polarity is transferred to the recording paper. This increases the amount of toner that is unnecessarily discarded, which is not only uneconomical, but also requires an excessive amount of space for the waste toner container, which increases the size of the image forming apparatus. In addition, because the toner retention force is weak, even if the toner is charged to the correct polarity, the toner with a large amount of charge per unit mass of light will
When it comes into contact with the latent image carrier in the development area, it adheres to non-image areas due to mirror image force or the like, causing smudges remaining on the recording paper.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and it is an object of the present invention to provide a developing device in which the amount of toner conveyed is stable and there is little ground force blur or density unevenness. Still another object is to provide a developing device that 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] The developing device of the present invention is a developing device that develops a one-component magnetic toner onto a latent image carrier using a developing roller, in which the developing roller has a cylindrical thin film member and a cylindrical thin film member. It is characterized by having at least a drive roller that contacts at least a portion of the inner circumferential side surface and generates a magnetic field.

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 at least a magnetic field generating layer.

[Function] According to the above configuration of the present invention, the developing roller can be configured as a single rotating body, which not only simplifies the structure of the developing roller but also makes it possible to obtain a small, lightweight, and low-cost developing roller. can.

In addition, by configuring the drive roller of the thin film member using a member that generates a magnetic field, the toner can be held on the thin film member by magnetic force, so the amount of toner conveyed is stabilized, and the amount of toner transported is stabilized due to the adhesive force of uncharged toner. It is possible to prevent the toner from adhering to the latent image carrier, and it is possible to oscillate the toner on the thin film member with the leakage magnetic flux and triboelectrically charge it, thereby improving the image density.

Further, according to the above configuration of the present invention, the thin magnetic field generating layer is magnetized at a minute pitch to form a uniform and thin toner layer (or a thin magnetic brush layer at a minute pitch) on the developing roller. It is possible to reduce density unevenness due to variations in toner layer thickness, and toner is retained on the developing roller by magnetic force, reducing ground blurring, allowing development with high resolution and high print quality. . Furthermore, by reducing soil blurring and reducing unnecessary waste toner, it is possible to make the image forming apparatus smaller and lower in cost and maintenance, and it is also possible to reduce toner consumption and running costs.

Hereinafter, the details of the present invention will be shown by 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 has a conductive support section 2.
A photosensitive layer 3 having organic or inorganic photoconductivity is coated on top of the photosensitive layer 3, and after the photosensitive layer 3 is charged using a charger 4 such as a corona charger or a charging roller, it is charged with a laser, LED, etc. The light emitted from the light source 5 is selectively irradiated onto the photosensitive layer 3 according to the image through the 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.
The developing roller 9 that conveys the developing roller 9 is composed of a driving roller 10 that is rotationally driven and generates a magnetic field, and a cylindrical thin film member 11 that is wrapped around the outer periphery of the driving roller 10 that generates a magnetic field, leaving an extra length, and generates a magnetic field. Drive roller 1
The magnetic toner 8 is held on the thin film member 11 by a leakage magnetic flux of 0, and the developing roller 9 is rotated while the amount is regulated to an appropriate amount by a thin plate spring-like elastic blade 13 made of non-magnetic or magnetic metal or resin. The magnetic toner 8 is oscillated by the leakage magnetic flux of the drive roller 10 that generates a magnetic field at the part that is pressed against the elastic blade 13 and the developing roller 9, and is triboelectrically charged or charged. In the areas where the thin film member 11 and the drive roller 10 are not in contact with each other after receiving the injection, frictional charging occurs due to the rotation or slipping of the magnetic brush, and a stable charge amount sufficient to develop the toner on the thin film member is obtained. . When the toner 8 is conveyed to the development gap portion where the developing roller 9 is pressed against the latent image carrier 1, a developing electric field is formed by the potential contrast of the latent image carrier 1 and the developing bias applying means 14, The charged toner 8 is transferred to the latent image carrier 1
The electrostatic latent image is visualized. At that time, the developing electric field can be emphasized by pressing the thin film member, which is the developing electrode, against the latent image carrier, and since the distance between the latent image carrier and the thin film member is defined by the toner layer thickness, the developing electric field is stabilized, and the toner is held by the leakage magnetic flux of the drive roller 10 that generates the magnetic field, so even in contact development, high-temperature, high-resolution images can be stably formed without any ground force blur. The toner image formed on the latent image carrier is transferred to a transfer device 15 such as a corona transfer device or a transfer roller.
The toner is transferred onto the recording paper 16 using heat and pressure, and the desired image is obtained on the recording paper by fixing the toner onto the recording paper.

Using a developing device as shown in FIG.
PI] line image, character image, and solid image 1
When continuously formed over 0,000 sheets, 600 [D
PI] line image is stably formed without line thickening, there is no trailing or blurring at the edges 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 onto 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 reduce this.

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 22 that develops the toner 8 leaves an extra length on the outer periphery of the drive roller 1o that generates a magnetic field and the drive roller 10 that generates a magnetic field. A magnetic field generating layer 24 is disposed on the cylindrical thin film member 23, and the leakage magnetic flux of the drive roller 10 that generates a magnetic field and the outer periphery of the magnetic field generating layer 24 are The magnetic toner 8 is held on the developing roller 22 by leakage magnetic flux, and the developing roller 22 is rotated with the amount regulated to an appropriate amount by a thin plate spring-like elastic blade 13 to convey a thin layer of the toner 8. The toner 8 is oscillated by the leakage magnetic flux of the drive roller 10 that generates a magnetic field at the portion that is pressed against the elastic blade 13 and the developing roller 22, and is subjected to frictional electrification or charge injection, and is connected to the thin film member 23 and driven to generate a magnetic field. In the areas where the roller 10 is not in contact, frictional charging is performed by the rotation or slipping of the magnetic brush, and a stable charge amount sufficient to develop the toner on the thin film member is obtained.

Further, the amount of toner conveyance, which is unstable due to the electrostatic adhesion force due to toner charging, is stabilized by the leakage magnetic flux of the magnetic field generation layer 24 and the drive roller 10 that generates the magnetic field. The developing roller 22 is pressed against the latent image carrier 1 with a predetermined pressure, and when the toner 8 on the developing roller 22 is conveyed to the pressure contact portion, the potential contrast of the latent image carrier 1 and the developing bias applying means 14 are applied. Toner 8 charged according to the developing electric field adheres to the latent image carrier 1, and the electrostatic latent image is visualized. At that time, the developing electric field can be emphasized by pressing the thin film member, which is the developing electrode, against the latent image carrier, and since the distance between the latent image carrier and the thin film member is defined by the toner layer thickness, the developing electric field is stabilized, and the toner is held by the leakage magnetic flux of the magnetic field generation layer 24 and the drive roller 10 that generates the magnetic field, so even in contact development, high-temperature, high-resolution images can be stably formed without any ground force blur due to the adhesive force of uncharged toner or the like.

Using a developing device as shown in FIG.
PI] line image, character image, and solid image 1
When continuously formed over 0,000 sheets, 600 [D
PI] line images are stably formed without line thickening, the resolution of the line bare image is the highest, there is no tailing or blurring at the image edges, and high temperature solid images with an OD value of 1.4 or more are produced. It was possible to form the toner stably, 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.

1 and 2, a drive roller 10 that generates a magnetic field 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 shaft that generates a magnetic field. The thin film member 11.23 is pressed against the drive roller 10 that generates a magnetic field to transmit rotational driving force.

Further, the drive roller 10 that generates a magnetic field can also have a structure in which a friction member is disposed on the surface of a mag roller consisting of a rotatable conductive non-magnetic sleeve and a magnetic field generating means included therein. The generating means may be anything that generates a magnetic field, such as a permanent magnet or an electromagnet. Furthermore, the magnetization direction may be arbitrary, such as the normal direction of the drive roller or the axial direction, and the magnetization pattern may also be linear, grid-like, spiral, etc. Optional. Further, the thin film member 11.23 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, and the film thickness of the thin film member varies depending on the material. In order to obtain sufficient pressure contact with the image carrier, 10~
The magnetic field generation layer 24 is desirably about 500 [μm]. Furthermore, the magnetic field generation layer 24 can be made of a material known as a magnetic recording material or a magnet material. More specifically, Fe, N,
A magnetic material containing at least one element among i, C0lMn, for example, 7'-Fe203, Ba-
Fe, Ni-Co, Co-Cr, Mn-Al, etc. can be used, and the film thickness is 100 [μm] or less, preferably 10 [μm].
] before and after, and the minimum magnetization reversal pitch is 100 [μm
By doing the following, the toner can be uniformly made into a thin layer, and at the same time, fluctuations 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 -component magnetic toners can be used, including resin-based toners and wax-based toners.

As is well known, toner has a composition in which magnetic powder, colorants, external additives, and other additives are added to resin, 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 1 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(a) is a diagram showing the layer structure of the thin film member of the developing roller in FIG.
By horizontally magnetizing the magnetic toner 33 to a value of 00 [μm] or less, a minute toner chain of the magnetic toner 33 is formed on the magnetic field generating layer 32, and a thin and stable toner layer is obtained. Furthermore, by forming the thin film member 31 with 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, a developing bias voltage can be applied to the thin film member 31 to obtain a developing electrode effect. It is possible to obtain high-resolution images.

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]). It is also possible to uniformly form a single thin toner layer, and since a strong magnetic field can be obtained on the surface of the magnetic field generation layer, the magnetic powder content of the magnetic toner 33 can be reduced to facilitate toner production and improve fixing properties. It is possible to improve In addition, the magnetic field generation layers 32 and 34 can be used in various magnetized states such as line magnetization, grid magnetization, and spiral magnetization, and the magnetization is directly applied to the developing roller. Alternatively, a magnetic field generating layer in the form of a film which has been magnetized in advance may be appropriately disposed on the developing roller by means such as adhesion.Also, the arrow in the figure indicates the direction of magnetization.

Although FIG. 3 shows an example in which a magnetic field generating layer is arranged on the thin film member 31 to stabilize the amount of toner conveyed, it is also possible to arrange a friction member such as natural rubber on the inner periphery of the film member. It is possible to effectively transmit the driving force without disposing a friction member around the outer circumference of the drive roller that generates the magnetic field, and toner can be transferred to the surface of the thin film member or magnetic field generation layer by charge injection or contact charging series. It is also possible to make the thin film member have a multilayer structure and provide additional functions, such as by disposing a charge control layer for charging to stabilize the charge amount of the toner.

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] According to the above structure of the present invention, the developing roller can be constructed of a single rotating body, which not only simplifies the structure of the developing roller but also provides a small, lightweight, and low-cost developing roller. be able to.

In addition, by configuring the drive roller of the thin film member using a member that generates a magnetic field, the toner can be held on the thin film member by magnetic force, so the amount of toner conveyed is stable, and the latent image due to the adhesive force of uncharged toner etc. It is possible to prevent the toner from adhering to the carrier, and the leakage magnetic flux causes the toner on the thin film member to be oscillated and triboelectrically charged, thereby improving the image quality.

Furthermore, the developing electric field can be emphasized by pressing the thin film member, which is the developing electrode, against the latent image carrier, and since the gap between the latent image carrier and the thin film member is determined by the toner layer thickness, the developing electric field is stabilized and the magnetic Since the toner is held by force, it is possible to prevent uncharged toner from adhering to the latent image carrier due to adhesive force even in contact development, and it is possible to stably form images with a high temperature layer and high resolution without blurring.

Furthermore, by arranging a magnetic field generation layer on the thin film member,
Because the toner can be transported directly on the surface of the magnetic field generation layer, the amount of transport is stable, and by making the minimum magnetization reversal interval extremely narrow, a minute toner chain is formed and a thin and stable toner layer is obtained, which allows the toner to be transported magnetically. By forcefully holding the toner on the developing roller, it is possible to reduce the smudge caused by the adhesive force of uncharged toner, and to perform development with high resolution and high printing quality. Furthermore, by reducing soil blurring and reducing unnecessary waste toner, it is possible to make the image forming apparatus smaller and lower in cost and maintenance, and it is also possible to reduce toner consumption and running costs.

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 and high-temperature layer images with few image defects such as ground blur and trailing in the -component magnetic development method. It is something.

[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. It is a figure which shows the layer structure of the thin film member of the developing roller in . 1......Latent image carrier 8, 33......Toner 9.22
...Developing roller 10 ... Drive roller thin film members 11 and 23 that generate magnetic fields. 31 13 ...... Elastic blade 14 ...
... Development bias applying means 24, 32. 34
... Magnetic field generation layer and above Applicant: Seiko Epson Corporation

Claims (3)

[Claims] (1) In a developing device that develops a one-component magnetic toner onto a latent image carrier using a developing roller, the developing roller contacts at least a portion of a cylindrical thin film member and an inner peripheral side surface of the cylindrical thin film member, and A developing device comprising at least a drive roller that generates a magnetic field. (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 at least a magnetic field generating layer.