Ricoh Company, Ltd.

Yoshihiro Ogata

Koji Sakamoto

Toshio Kaneko

Toshihiko Takaya

Harumi Takahashi

Koji Hirakura

Yoshihiro Abe

Fuchio Takeda

Shigeru Suzuki

Yoshihiro Sakai

Seiichi Miyakawa

Susumu Tatsumi

Shuichi Endoh

Hiroyuki Matsushiro

Tsuyoshi Yoshimura

Akito Yoshimaru

Harumitsu Mashiko

Shuichi Endo

Atsushi Shinozaki

Hisashi Kuroda

Toyoji Ishikawa

Syoji Hayashi

An image developing device for use in an electrophotographic copying apparatus or a printer includes a developing roller for supplying toner to a latent image formed on a latent image carrier to develop the latent image into a visible toner image. The image developing device also includes a toner supply roller independently rotatable in abutting engagement with the developing roller for supplying the toner onto the developing roller. Each of the toner supply roller and the developing roller is electrically conductive. An electric potential with its polarity dependent on whether the toner is positively or negatively chargeable is applied between the toner supply toner and the developing roller by a bias voltage distributing circuit.

Image developing device

A developing device includes a developing sleeve driven to rotate for transporting a film of charged developer as carried thereon past a developing station where the film of developer is applied to an electrostatic latent image to have it developed. Also provided is a sponge roller pressed against and driven to rotate in the same rotating direction as that of the developing sleeve, so that the developer is supplied to the developing sleeve at one side of the contact between the developing sleeve and the sponge roller and any residual developer on the developing sleeve is removed at the other side of the contact. Preferably, a desired voltage difference is established between the developing sleeve and the sponge roller. Furthermore, the sponge roller is preferably so structured to have a sufficient conductivity level at least at its outer peripheral surface thereby allowing the residual charge on the developing sleeve to be discharged sufficiently.

Thin film developing device

An electrostatic latent image developing apparatus supplies toner to a latent image carrier such as a drum-shaped photosensitive body to visualize a latent image formed thereon. The toner is supplied by a rotating drum-shaped toner carrier having a portion confronting the photosensitive body adjacent thereto and another portion held in contact with toner contained in a toner container. The toner is electrostatically attracted to the toner carrier and transferred therefrom to the photosensitive body. The toner on the toner carrier is regulated into a thin toner layer by a toner layer regulating member that is resiliently held in sliding contact with the toner carrier. To prevent toner deposits from being attached to the toner layer regulating member, the toner layer regulating member is made of a material adapted to wear with the attached toner. In order to provide the toner layer regulating member with an ability to triboelectrically charge toner, whether chargeable to a polarity (-) or (+), or to control the amount of electricity on toner chargeable to a polarity (-) or (+) and prevent toner deposits from being attached to the toner layer regulating member, another material to control the amount of electricity on toner is mixed in the material which can be worn with the attached toner.

Electrostatic latent image developing apparatus

A portable image forming device which is moved on an original in a direction perpendicular to a primary scan direction for subscan, and divides original reflection light beams into picture pickup elements in the primary scan direction through an image forming optical system to imageform the pickup elements on a pickup device for reading. The pickup range of the pickup device in the primary scan direction is designed to be variable, and means for setting the pickup range is provided. With a portable copying machine which houses the pickup device and a printing section including a writing head in a single casing, paper is fed to the printer section as required by making use of the movement of the machine for original scan.

Portable image forming device

An improved copy paper separating device for use in a transfer type electrophotographic copying machine is provided. The separating device includes a conductive carrier member, preferably in the form of a conductive endless belt extended between a pair of pulleys. The conductive carrier member is disposed in the periphery of the photosensitive member to which a copy paper is brought into contact for the transfer of a toner image formed on the photosensitive member. The potential of the conductive carrier member is maintained nearly at zero level during the first step of the separating operation; whereas, the potential of the carrier member is increased to a predetermined value of the polarity opposite to that of the toner image during the second step. Information as to the conditions of separating operation is also supplied and the timing of changing potentials is appropriately adjusted. Moreover, a plurality of voltage sources having different potential levels are provided and the potential is selectively applied to the carrier member as required, which is particularly useful when applied to a duplex copying machine.

Transfer medium separating device

In a copy paper separating device for use in a transfer type electrophotographic copying machine which includes a conductive carrier member, preferably in the form a conductive endless belt extended between a pair of pulleys. The conductive carrier member is disposed in the periphery of the photosensitive member to which a copy paper is brought into contact for the transfer of a toner image formed on the photosensitive member. The potential of the conductive carrier member is maintained nearly at zero level during the first step of the separating operation; whereas, the potential of the carrier member is increased to a predetermined value of the polarity opposite to that of the toner image during the second step.

A transfer sheet separating/conveying member is formed of an electrically conductive material, and has its part disposed close to or in contact with the peripheral surface of a photosensitive drum for movement in the same direction as the drum. The separating/conveying member is applied with a voltage of the same polarity as that of a voltage applied to the transfer sheet. An insulating material covers at least a portion of the laterally opposite sides of the separating/conveying member which are located opposite to the drum surface. A corner of the separating/conveying member which is not covered by the insulating material and remains exposed is shaped into a rounded form.

Transfer sheet separating/conveying apparatus for use in

A toner image of an original document is formed on a photoconductive drum (1) and transferred onto a copy sheet (4) which is moved into contact with the drum (1) by a corona charging unit (5) which applies an electrostatic charge to the copy sheet (4) causing the toner image to be transferred thereto. The copy sheet (4) is separated from the drum (1) by a conductive belt (6). The belt (6) is initially grounded so that the leading edge of the copy sheet (4) is attracted thereto by induced electrostatic charge. A voltage of the same polarity as the transfer charge is then applied to the belt (6) to prevent transfer of the toner image back to the drum (1).

Electrostatic copying apparatus

A powdered toner mixture comprising a non-magnetic toner component and a ferromagnetic carrier component is caused to flow downwardly through a vertical conduit by gravity. An electromagnetic coil is wound around the conduit and energized with an alternating electric signal. An electrically conductive and magnetic mass is disposed inside the conduit. The permeability of the toner mixture decreases as the toner density, or the ratio of the toner component to the carrier component, increases. The lower the permeability of the toner mixture, the greater the proportion of magnetic flux passing through the mass. The flux passing through the mass induces eddy currents therein which, in combination with hysterisis and skin effect losses, dissipate a portion of the electric signal. The amount of power dissipation is a function of the relative proportion of flux through the mass and thereby the toner density and, when measured, provides a measure of the toner density.

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Yokohama, Japan

Yoshihiro Ogata