JPH04172382A - Image formation device - Google Patents

Abstract

PURPOSE:To enable a stable image without uneven development density to be obtained by causing a latent image carrier to have a soft magnetic member, and attracting a thin film member to the latent image carrier via a magnetic force. CONSTITUTION:A latent image carrier 1 has an organic or inorganic photoconductive sensitive layer 3 formed on a soft magnetic material 2. After the sensitive layer 3 is electrified by a charging unit 4, light is irradiated from a light source 5 to the sensitive layer 3 through an imaging optical system 6 selectively depending upon an image, thereby obtaining potential contrast and forming an electrostatic latent image. On the other hand, toner 8 is directly retained on a development roller 9 via the electrostatic mirror image force and adhesion of the surface of a cylindrical thin film material 11, and the aforesaid roller 9 is rotated under appropriate restriction with a plate-like elastic blade 13, thereby carrying a thin layer of the toner 8. According to the aforesaid constitution an image having stable density and less development irregularity can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an image forming apparatus that forms an image by supplying toner to an electrostatic latent image formed on the surface of an electrostatic latent image carrier, and further relates to Specifically, the present invention relates to an image forming apparatus that conveys toner using a developing roller having a cylindrical thin film member to form a developed image on a latent image carrier.

[Prior Art] As disclosed in Japanese Patent Laid-Open No. 63-226676, a conventional image forming apparatus has a drive roller on which a developing roller is rotationally driven, and a circumference that is longer than the circumference of the drive roller. and a thin film member, the driving roller is at least partially in contact with the inner circumferential surface of the thin film member, and at a portion where the driving roller and the electrostatic latent image carrier face each other, there is a gap between the driving roller and the thin film member. In addition to forming a space, a thin layer of charged toner is formed on the outer peripheral surface of the thin film member, and a developed image is formed on the latent image carrier.

[Problems to be Solved by the Invention] However, the developing ability of the image forming apparatus according to the above-mentioned prior art decreases as the length of the contact area between the latent image carrier and the thin film member (hereinafter referred to as the developing nip width) increases. It is stable, and the developing nip width is determined by the difference in circumferential length between the thin film member and the drive roller, and the hardness and thickness of the thin film member. If the circumference of the thin film member is increased and the thickness of the thin film member is made thinner in order to increase the width of the developing nip, loosening, sagging, and twisting will occur between the drive roller and the thin film member, and wrinkles will also occur in the thin film member. Deterioration was observed, toner transport was not stable, a partially thick toner layer was formed, and a uniform thin developer layer was not formed.

This has led to deterioration in image quality, such as development unevenness. Further, if the thin film member is made thinner in order to increase the width of the developing nip, it causes deterioration such as wrinkles in the thin film member and shortens the life of the thin film member such as damage.

The present invention is intended to solve these problems, and its purpose is to form a stable developing nip width without making the thin film member extremely thin, to stabilize the amount of toner conveyed, and to improve the development speed. The purpose is to prevent unevenness and provide extremely stable images.

Another objective is to form a wide developing nip width and provide a high-speed, high-resolution image forming apparatus.

[Means for Solving the Problems] The image forming apparatus of the present invention includes a drive roller that is rotationally driven by a developing roller, and a thin film member having a circumference longer than the circumference of the drive roller. The roller at least partially contacts the inner circumferential surface of the thin film member, and forms a space between the drive roller and the thin film member at the opposing portion of the drive roller and the electrostatic latent image carrier, and further contacts the outer circumference of the thin film member. In an image forming apparatus comprising at least means for forming a thin layer of charged toner on a surface and forming a developed image on a latent image carrier, the latent image carrier has a soft magnetic member, and the thin film member has a magnetic field generating layer. It is characterized by

[Operation] According to the above-described structure of the present invention, the latent image carrier has a soft magnetic member, and by attracting the thin film member to the latent image carrier by magnetic force, the thin film member is not made extremely thin. A stable developing nip width can be formed, extremely stable images without uneven development can be obtained, a wide developing nip width can be formed, and a high-speed, high-resolution image forming apparatus can be provided.

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

[Example] FIG. 1 is a cross-sectional schematic view of an image forming apparatus in an example of the present invention, in which a latent image carrier 1 has a soft magnetic member 2 and a photosensitive layer 3 having organic or inorganic photoconductivity. After 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 a laser or an LED is passed through an imaging optical system 6 to the photosensitive layer 3. A latent electrostatic image is formed by selectively irradiating light according to the image to obtain potential contrast. On the other hand, the developing device 7 conveys the toner 8 and develops it. The cylindrical thin film member 11 and the magnetic field generating layer 12 are packaged with the exception of
The toner 8 is held directly on the developing roller 9 by the electrostatic image force and adhesive force on the surface of the cylindrical thin film member 11, and the plate-shaped elastic blade 13 is made of non-magnetic or magnetic metal or resin. A thin layer of toner 8 is conveyed by rotating the developing roller 9 while regulating the amount to an appropriate amount. In the development gap area where the latent image carrier 1 and the developing roller 9 are close to each other, the latent image carrier 1 is attracted by the leakage magnetic flux on the outer periphery of the thin film member 11, and the latent image carrier 1 and the thin film member 11 are brought into pressure contact to form a developing area. Form. When the toner 8 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, forming an 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. When 10,000 line images, character images, and solid images of 600 [DPI] were continuously formed using the image forming apparatus shown in Fig. 1, the line images of -600 [DPI] became line thick. It is possible to stably form a high-density solid image with an OD value of 1°4 or more without any trailing or afterimages at the edge of the image, and to avoid loosening, sagging, or twisting of thin film members. No wrinkles were observed even after printing 10,000 sheets, and it was possible to obtain an image with stable density without any uneven development on the recording paper or on the latent image carrier.

In FIG. 1, the soft magnetic member 2 is made of Fe or a steel material containing Fe, a high magnetic permeability soft magnetic material such as Ni, permalloy, permendur, or nylon, polyimide, or polyethylene terephthalate containing magnetic powder. Resin materials such as can be used. The drive roller 10 has a friction part made of natural rubber, silicone rubber, urethane rubber, butadiene rubber, chloroprene rubber, neoprene rubber, NBR, etc. on the outer periphery of a resin or metal shaft.
The thin film member 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 body, it is preferable to have a thickness of about 10 to 500 [μm].Furthermore, the magnetic field generation layer 12 can be made of a known magnetic recording material or magnet material; For details, please refer to Fe
, Ni, Co, Mn, Cr, a magnetic material containing at least one element among the following, for example, γ-F
e203, Ba-Fe%Ni-Co, Co-Cr, Mn
- Al, etc. can be used, and the film thickness is 100 [μm] or less, preferably around 10 [μm]. The minimum magnetization reversal pitch is 100 [μm] or less, and the toner is uniformly thinned and a magnetic brush is formed at the same time. It is possible to reduce density unevenness by suppressing fluctuations in the amount of toner conveyed on the developing roller to a minute pitch. Further, as the toner used in the present invention, all toners known as magnetic and non-magnetic toners can be used, and 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, the latent image carrier may be cylindrical or belt-shaped, and a thin film member may be formed of a magnetic material and integrated.Furthermore, the arrows indicate the rotation direction of each member, but this does not limit the present invention. Furthermore, the developing method can be used regardless of whether it is regular development or reversal development.

FIG. 2 is a schematic diagram of a magnetized state of a magnetic field generating layer of an image forming apparatus according to still another embodiment of the present invention, in which a latent image carrier 21 is coated with organic or inorganic light on a soft magnetic member 22. A photosensitive layer 23 having conductivity is formed, and the magnetic field generating layer 25 is magnetized in a lattice shape so that N poles and S poles appear alternately, forming a magnetic circuit as shown by the arrow. The thin film member 26 is sucked, and the latent image carrier 21 and the thin film member 2 are
6 contact areas are formed. The toner 24 conveyed to this contact area is pressed against the latent image carrier 21 with a stable developing nip width, and is developed according to the latent image. The magnetization state of the magnetic field generation layer 25 is not limited to a lattice shape, and the thin film member 26 can be attracted even if it is magnetized in various ways, such as a line magnetization.

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, a stable developing nip width can be formed without making the thin film member extremely thin, good toner replenishment performance can be maintained, and development unevenness can be maintained. It is possible to provide an image forming apparatus that can obtain stable images with low density, and has the effect of stably obtaining high-resolution images at high speed.

Further, it is possible to provide an image forming apparatus in which the developing roller has a long life, easy maintenance, and low running costs, and it is possible to provide an image forming apparatus with a simple structure and small size and low cost.

Therefore, the developing device of the present invention forms an image forming device that can form a stable developing nip width without making the thin film member extremely thin, and can obtain high-speed, high-resolution images with few image defects such as uneven development. It has the excellent effect of being able to provide

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a magnetized state of a magnetic field generating layer of the image forming apparatus according to an embodiment of the present invention. l, 21...Latent image carrier 2.22...Soft magnetic member 7...Developing device 8...Toner 9...Developing roller 10...Drive roller 11.26...Thin film member 12.25 ... Magnetic field generation layer and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (1st name) Figure 1

Claims (1)

[Claims] The developing roller includes a cylindrical thin film member and a drive roller that contacts at least a portion of the inner circumferential surface of the thin film member, and in a portion facing the drive roller and the electrostatic latent image carrier, the thin film member and Image formation comprising a thin film forming means for forming a space between the drive roller and a thin layer of charged toner on the outer peripheral surface of the thin film member, and at least means for forming a developed image on the latent image carrier. An image forming apparatus characterized in that the latent image carrier has a soft magnetic member, and the thin film member has a magnetic field generating layer.