Canon Kabushiki Kaisha

Tadashi Furuya

Hideyuki Yano

Harumi Ishiyama

Seiji Mashimo

Yasunori Chigono

Junji Araya

Yasushi Sato

Harumi Kugoh

Osamu Iwasaki

Katsuhiro Sakaizawa

Harumi Kugo

Jun Hirabayashi

Akio Maruyama

Yomishi Toshida

Yukihiro Ohzeki

Shoji Amamiya

Kazushige Nakamura

Norio Hashimoto

Takeo Yamamoto

Takashi Shibuya

Noboru Kashimura

Yukihiro Ozeki

Nobuyuki Ito

An image forming apparatus includes an image bearing body. The image bearing body is charged by a charging device including a magnetic brush which is brought into contact with the image bearing body and which is formed by a magnetic particle layer. The image bearing body is exposed by a pre-exposing device after an image formed on the image bearing body is transferred to an image receiving member and before the photosensitive body is charged by the charging device. The pre-exposing device exposes the image bearing body with an exposure width smaller than a width with which the charging device charges the image bearing body in a longitudinal direction of the charging device. The exposure width is larger than an image formation width in the longitudinal direction of the charging device.

Image forming apparatus with pre-exposed image bearing body

A charging apparatus includes a first charging member of being supplied with a voltage to charge a member to be charged. A first charging member has magnetic particles in the form of a magnetic brush contactable to the member to be charged. A second charging member charges a region of the member to be charged corresponding to an end portion, in a longitudinal direction of the charging member, of the magnetic particles, wherein by the second charging member, the region has a potential of the same charge polarity of the voltage when the region reaches a charging position of this first charging member.

Charging apparatus with first and second charging members

A charging apparatus includes a member to be charged having a charge retaining layer for retaining a charge and an electroconductive base. A charging member capable of being supplied with a voltage is provided to charge the member to be charged. The charging member includes magnetic particles in the form of a magnetic brush contactable to the member to be charged, wherein the member to be charged has an electroconductive member electrically insulated from the electroconductive base in a region corresponding to an end portion, in a longitudinal direction of the charging member.

Charging member, charging device and image forming apparatus wherein deposition of magnetic particles to a member to be charged is effectively prevented

A charging device for charging a member to be charged includes a charging member to which a voltage is applicable to charge the member to be charged, the charging member having a magnetic brush of magnetic particles contactable to the member to be charged, and a supporting member for supporting the magnetic particles; wherein the the magnetic particles have a resistance value of 1.times.10.sup.4 -1.times.10.sup.7 (Ohm) when 1-1000(V) is applied thereto.

Charging device using a magnetic brush contactable to a member to be

An image forming apparatus has an image forming unit for forming a toner image on a recording material, the image forming unit including an image bearing member for bearing a toner image, and a charging device provided with a magnetic particle layer contactable to the image bearing member to charge the image bearing member; and a determining device for determining an image forming condition of the image forming unit in accordance with a physical quantity relating to a toner amount introduced in the magnetic particle layer or deciding prohibition of the image forming operation of the image forming unit.

Image forming apparatus that detects image forming condition

A charging member supporting magnetic particles for charging a member to be charged, including: an electroconductive member to which a voltage is applicable; and a member electrically insulated from the electroconductive member at an end portion, in a longitudinal direction of the charging member, of the magnetic particles, wherein deposition of magnetic particles to the member to be charged from the charging member is effectively prevented.

Charging member, charging device and image forming apparatus

An image forming apparatus includes a movable image bearing member, a charging member, a developer, and an auxiliary member. The charging member contacts the image bearing member to electrically charge the image bearing member. The developer develops, with toner, an electrostatic image formed on the image bearing member using a charging operation of the charging member. The developer is capable or removing residual toner from the image bearing member simultaneously with its developing operation for the electrostatic image. The auxiliary member is disposed upstream of the charging position and downstream of a transfer position where the toner image is transferred from the image bearing member onto a transfer material with respect to a movement direction of the image bearing member. The auxiliary member is supplied with a voltage having a polarity opposite from a charge polarity of the charging member or is supplied with OV so that residual toner is charged to the opposite polarity and reaches the charging position. The voltage applied to the auxiliary member is more toward the opposit polarity side when a region of the image bearing member, which is going to be a non-image region, is at a position of the auxiliary member then when a region of the image bearing member, which is going to be an image region, is at the position of the auxiliary member.

Image forming apparatus

An electrophotographic apparatus which simultaneously performs image exposure and development, including an electrophotographic photosensitive body having a conductive layer, an electrophotoconductive layer, and an electric charge supply layer for contacting a developer sequentially formed on a translucent substrate, wherein a value of the surface energy of the outer layer of the photosensitive body is 30 dyne/cm or less in order to present fogging generated during development.

Electrophotographic apparatus performing image exposure and development

An electrophotographic apparatus includes a movable photosensitive member having a photoconductive layer, and a charging member for charging the photosensitive member. A latent image forming device forms an image on the photosensitive member, and an electric charge applying device applies an electric charge of a polarity opposite from a charging property of the charging member to the photosensitive member. The photosensitive member includes a rectifying layer on the photoconductive layer to provide, at an interface between the photoconductive layer and the rectifying layer, a p-n junction preventing electric charge of the opposite polarity from entering the photoconductive layer.

Electrophotography having photosensitive member with charge blocking

A charging device includes a charging member for charging a movable member to be charged; the charging member including a carrying member for carrying a magnetic particle layer contactable to the member to be charged, the carrying member being adapted to be supplied with a voltage; wherein a direction of a magnetic force acting on magnetic particles in the magnetic particle layer at a downstream end position with respect to a movement direction of the member to be charged at a portion where the member to be charged and the magnetic particle layer are contacted, is opposite from the member to be charged with respect to a tangent line of the member to be charged at the end position.

Magnetic charging brush having particular magnetic fields

An image forming apparatus includes an image bearing device, a charger contactable to the image bearing device for effecting contact charging of the image bearing device, the charger being supplied with a voltage having a DC component and an AC component, and the charger being provided with an electrode for receiving the voltage; wherein the following is satisfied: when an electric field formed between the image bearing device and the electrode is not more than .vertline.E/d.sub.SD .vertline. (V/m), a resistance of the charger per unit area of contact between the image bearing device and the charger is larger than

Contact charger for charging a photosensitive member

This invention relates to a charging system for charging a body to be electrified, comprising a body to be electrified, and a charging member which can be applied with voltage to brush the surface of said body to be electrified and charge it. Wherein the surface of the body to be electrified exhibits a contact angle of 90.degree. or more for water.

Charging system and electrophotography apparatus

A charging member for charging a member to be charged, includes a magnet member and a surface electroconductive layer for supporting electroconductive magnetic particles, the layer being supported by the magnet member and rotating together with the magnet member in a region supporting the magnetic particles.

Charging member and image forming apparatus

The image forming method comprises, electrostatically charging an image bearing member using a contact charging assembly, forming an electrostatic latent image on the image bearing member thus charged, developing the electrostatic latent image with a magnetic toner to form a toner image and transferring the toner image to a transfer medium, wherein the charging assembly comprises a magnetic brush formed from conductive magnetic particles magnetically bound, and the charging assembly comes into contact with the image bearing member to charge the surface of the image bearing member by directly injecting charges into the electron level present on the surface of the image bearing member and the magnetic toner has a value of .sigma..D..delta. of 150 or less, where the value is obtained by multiplying i) a magnetization quantity .sigma. (Am.sup.2 /kg) in a magnetic field of 1K oersted as measured by a vibration magnetometer, ii) a weight average particle diameter (D.sub.4) D (.mu.m) of the magnetic toner and iii) a density .delta. (g/cm.sup.3) thereof.

Image forming method, image forming apparatus and process cartridge

An electrophotographic apparatus for simultaneously performing image exposure and development including an electrophotographic photosensitive body comprising a conductive layer and an electrophotographic photosensitive layer formed on the translucent substrate. An optical system is provided for exposing the image from the side of the translucent substrate of the photosensitive body, and a developer apparatus is arranged opposing to the side of photosensitive layer of the exposure position of the photosensitive body for supplying developer charged with the developing bias.

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Kawasaki, Japan

Tadashi Furuya