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Patent Abstract
Image forming apparatus having an intermediate transfer member and method of forming of image using the transfer member
Patent number: 5715510
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Takashi Kusaba (Kawasaki, JP), Hiroyuki Kobayashi (Fuji, JP), Akihiko Nakazawa (Kanagawa-ken, JP), Atsushi Tanaka (Yokohama, JP), Tsunenori Ashibe (Yokohama, JP)

An image forming apparatus having a first image supporting member and an intermediate transfer member for transfer of an image from the first image supporting member and means for transferring the transferred image on the intermediate transfer member to a second image supporting member; characterized in that the contact angle between a surface of the intermediate transfer member and water is 60.degree. or above, and the sliding resistance of the surface is 200 g or below. The above image forming apparatus has excellent durability and good image forming properties under overall environmental conditions, and produces images without toner-filming.

Toner for developing electrostatic image containing higher and lower molecular weight polymer components
Patent number: 5744276
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Manabu Ohno (Funabashi, JP), Hiroyuki Suematsu (Yokohama, JP), Akihiko Nakazawa (Kanagawa-ken, JP), Nobuyuki Okubo (Yokohama, JP), Shunji Suzuki (Tokyo, JP)

An electrophotographic toner composition suitable for heat-fixation and showing good storage characteristics is constituted by polymer components, a colorant and a metal-containing organic compound. The toner composition shows a melt index (at 125.degree. C., 10 kg-load) of 5-25 g/10 min., and the polymer components are characterized by (a) containing substantially no THF (tetrahydrofuran)-insoluble content, (b) including a THF-soluble content thereof providing a GPC (gel permeation chromatography) chromatogram showing i) a main peak in a molecular weight region of 2.times.10.sup.3 -3.times.10.sup.4, and a sub-peak or shoulder in a molecular weight region of at least 10.sup.5, and ii) an areal percentage of 3-10% in a molecular weight region of at least 10.sup.6, and (c) including a polymer component (H) in a molecular weight region of at least 10.sup.5 obtained by polymerization using a polyfunctional polymerization initiator and a monofunctional polymerization initiator.

Process cartridge, electrophotographic apparatus and image-forming method
Patent number: 6615015
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Akihiko Nakazawa (Shizuoka, JP), Hiroyuki Kobayashi (Shizuoka, JP), Atsushi Tanaka (Shizuoka, JP), Tsunenori Ashibe (Kanagawa, JP), Takashi Kusaba (Shizuoka, JP), Hidekazu Matsuda (Shizuoka, JP)

A process cartridge is disclosed integrally supporting an electrophotographic photosensitive member, an intermediate transfer belt, a primary-transfer member for transferring a toner image primarily from the electrophotographic photosensitive member to the intermediate transfer belt and a charge-providing member for providing the toner on the intermediate transfer belt with electric charges having a polarity reverse to the polarity the toner has at the time of the primary transfer and returning the toner on the intermediate transfer belt to the electrophotographic photosensitive member at the contact zone to clean the intermediate transfer belt. The intermediate transfer belt has a modulus of elasticity of from 500 MPa to 4,000 MPa at elongation from 0.5% to 0.6% in the peripheral direction, a breaking extension of from 5% to 850% in the peripheral direction and a surface roughness Ra of 1 .mu.m or less.

Image forming method with surface potential control of intermediate transfer member
Patent number: 5991566
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Atsushi Tanaka (Yokohama, JP), Hiroyuki Kobayashi (Fuji, JP), Akihiko Nakazawa (Shiroyamamachi, JP), Tsunenori Ashibe (Yokohama, JP), Takashi Kusaba (Kodaira, JP)

An image forming apparatus and method includes a first image-bearing member, a latent image-forming device for forming an electrostatic latent image on the first image-bearing member, developer for developing the electrostatic latent image with a toner to form a toner image, an intermediate transfer member for receiving the toner image by primary transfer and transferring the toner image onto a second image-bearing member by secondary transfer, a charging member for charging a residual toner remaining on the intermediate transfer member after the secondary transfer, and a recovery member for recovering the charged residual toner at a recovery position by voltage application. The intermediate transfer member exhibits a charging characteristic such that it has a surface potential of at most 500 volts as an absolute value at the recovery position. The intermediate transfer member having such a charging characteristic is effective in suppressing an occurrence of electric discharge at the recovery position of the residual toner to provide an excellent cleaning performance.

Magnetic developer for developing electrostatic images
Patent number: 5364720
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Inventors: Akihiko Nakazawa (Kanagawa, JP), Masayoshi Kato (Iruma, JP), Manabu Ohno (Funabashi, JP), Nobuyuki Okubo (Yokohama, JP), Shunji Suzuki (Yokohama, JP)

A magnetic developer for developing electrostatic images is constituted by magnetic toner particles, each containing a binder resin having a melt viscosity of at most 5.0.times.10.sup.6 poise at 150.degree. C. and a magnetic material. The magnetic material is blended with a proportion (C) [wt. %] of inorganic fine particles based on the magnetic material to carry 0.2-5 wt. % of the inorganic fine particles secured to the magnetic material surface. The magnetic material has a specific surface area (A) [m.sup.2 /g] before securing of the inorganic fine particles and is provided with an increase in surface area (B) [m.sup.2 /g] by the securing of the inorganic fine particles; wherein the parameters A, B and C satisfy the following formulae (1) and (2): As a result, the magnetic developer is provided with an improved low-temperature fixability without causing problems accompanying the use of a low-temperature softening binder resin, such as deterioration of anti-offset characteristic, storage characteristic, developing characteristic.