Minolta Camera Kabushiki Kaisha

Kuniki Seino

Shoji Kondo

Yoshihiro Ozaki

Takashi Sugiyama

Susumu Tanaka

Hisashi Myochin

An electrical charging apparatus which includes a confronting electrode formed by a metallic plate, a heat-resistant electrically insulative member for covering a surface of the confronting electrode, an exciting electrode in the form of a thin wire fixed to a surface of the heat-resistant electrically insulative member so as to face the confronting electrode through the heat-resistant electrically insulative member, a power source for applying a high voltage AC current between the confronting electrode and the exciting electrode, and a control electrode in the form of a mesh provided to confront the exciting electrode.

Electrical charging apparatus for electrophotography

A residual charge erasing step in the electrophotographic process in which a transparent conductor backed photoconductor layer positioned in virtual contact with a conductor backed dielectric layer is exposed to a light image while a first voltage is applied between the conductors to produce on the dielectric layer an electrostatic latent image, the erasing step which is applied after the transfer of the latent image includes positioning the photoconductor and dielectric layers in virtual contact, illuminating the full surface of the photoconductor layer and applying between the conductors a second voltage of a polarity opposite to the first voltage and whose value is

Electrophotographic copying method with residual charge erasing step

An electrophotographic copying method in which there are employed a photosensitive member including a photoconductor layer backed by a conductive electrode and a dielectric layer backed by a conductive electrode comprises the steps of positioning the members with the layers in face-to-face virtual contact and while so positioned applying a voltage of a first polarity between the electrodes under dark conditions to cause gaseous discharges in the gaps between the layers and the charging of the dielectric layer and short circuiting the electrodes while illuminating the photoconductive layer until the electric field therein is zero, and then applying a voltage of reverse polarity between the electrodes while exposing the photoconducted layer to a light image to produce an electrostatic latent image thereof on the dielectric layer which is then separated from the photoconductor layer and the latent image developed and transferred to copy paper. Follower transfer of the developed image the dielectric layer is cleaned of residual toner and residual charges are removed by repositioning the dielectric layer in virtual contact with the photoconductor layer and alternately applying voltages of opposite polarities between the electrodes while illuminating the photoconductor layer. Equations setting forth the values of the applied voltages are given.

Electrophotographic image forming method

A method of producing an electrostatic latent image of an original includes the successive steps of positioning of face-to-face virtual contact a photoconductor layer superimposed on a conductive backing electrode and a dielectric layer superimposed on another conductive backing electrode, applying a direct current voltage of a first polarity between the electrodes of a value to produce gas discharges between the layers to charge the dielectric layer while the photoconductor layer is unexposed to any light, short circuiting the electrodes while exposing the full surface of the photoconductor layer to light until the electric field across the photoconductor layer is substantially zero and applying a voltage between the electrodes at a polarity opposite to the first polarity while exposing the photoconductor layer to the light image of an original. The dielectric layer may be a coating on a conductive copy paper or may be a driven endless conductive belt along which are located an image developing device, an image transfer device and a device for erasing residual toner and charges from the belt dielectric layer.

Method for forming an electrostatic latent image

An electrophotographic process including the step of pre-exposing the surface of a photosensitive member to light at an exposure of no less than 10.sup.3 lx-sec, followed by the uniform charging of the same. The photosensitivity of this type photosensitive member in an image exposing step varies according to its prior history. This process further includes the step of exposing an image by projecting an optical image, corresponding to an original image, onto the photosensitive member thus charged for forming a clear electrostatic latent image, corresponding to the original image, on the surface of the photosensitive member.

Electrophotographic processes using a pre-exposure

In an electrophotographic process in which a photosensitive member such as CdS.nCdCO.sub.3 -resin photosensitive member having peculiar hysteresis characteristics is sequentially subjected to pre-charging step, hysteresis charging step, hysteresis exposure step, charging step and image-wise light exposure step, the adjustment of photosensitivity of the photosensitive member by variation of the amount of light in the hysteresis exposure step results in an improvement in image formation.

Electrophotographic process using a cadmium sulfide photoconductor

An improved electrophotographic copier is disclosed. The copier includes a rotatable photosensitive member, a first charging means for charging the photosensitive member uniformly with a specific polarity of charges to a predetermined surface potential, an image exposing means for exposing the uniformly charged photosensitive member, an image transfer means for transferring an image onto a copying material and an erasing means for erasing charges on the photosensitive member after transfer by the image transfer means, the improvement which comprises that said photosensitive member is of material which exhibits a hysteresis effect in which the photosensitivity of the photosensitive member when exposed by said image exposing means varies in accordance with the variance of the surface potential at the start of light decay by said erasing means, and a second charging means is provided at a position preceding said erasing means for uniformly applying charges of a polarity the same as the polarity of said first charging means to the photosensitive member.

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Aichi, Japan

Kuniki Seino