Ricoh Company, Ltd.

Shuichi Tsushima

Fuyuhiko Matsumoto

Kunihiko Ikeda

Shuichi Karasawa

Tsutomu Sato

Masao Yoshikawa

Tsutomu Ishida

Masatoshi Saitou

A photoelectric conversion apparatus comprises an insulating and transparent substrate, a plurality of photoelectric conversion elements formed on the substrate in a line, selection switches made up of thin film transistors formed on the substrate for selecting the photoelectric conversion elements, a driving circuit made up of thin film transistors formed on the substrate for driving the selection switches, and a wear-resistant and transparent protecting layer formed at least on the photoelectric conversion elements.

Contact photoelectric conversion apparatus having plurality of

In an electrophotographic system in which latent images of negative and positive polarities formed electrostatically on a photoconductive member or a dielectric member are successively developed with two different kinds of toners and then transferred onto a transfer medium, an image transfer and sheet separation apparatus comprises a precharger for uniformalizing the different polarities of the toners carried on the photoconductive member or the dielectric member, a transfer charger for transferring the toners onto the transfer medium, and a conductive member for image transfer and sheet separation located to become intimately engaged by the transfer medium and provided with means for applying a voltage.

Image transfer and sheet separation apparatus for electrophotographic

A two-component type dry developer for use in dichromatic electrophotography comprising two kinds of developers, said developers each consisting of a toner and a carrier therefor and adapted for the production of a dichromatic image by developing a both positively and negatively electrified electrostatic latent image successively with toners different in polarity and color from each other, wherein one carrier has a triboelectrification property of being electrified positively by friction with either of two toners while the other carrier has a triboelectrification property of being electrified negatively by friction with either of two toners.

Dichromatic electrophotography using two developer compositions applied

A copying method for producing duplicates of an original of at least two colors by using a composite photosensitive member including more than two photosensitive layers, wherein the photosensitive member is subjected to charging more than twice and exposed to an optical image of the original more than once by changing charging and exposing conditions, to vary charge carried on the surface and in the interior of the photosensitive member. This causes two types of electrostatic image to be formed on the surface of the photosensitive member; one type includes image regions having a positive surface potential, a negative surface potential and a substantially zero surface potential respectively and the other type includes two image regions having different surface potentials of same polarity respectively, and one image regions of substantially zero surface potential, depending on differences in color between image regions of the original corresponding to the image regions on the photosensitive member. By suitably selecting charging and exposing conditions, it is possible to selectively carry out, by using a single copying apparatus, a copying mode in which duplicates are produced in several colors, a copying mode in which duplicates are produced in one color and a copying mode in which image regions of one color are erased.

Copying method and apparatus

An improved two-color electrophotographic copying apparatus comprising a non-magnetic sleeve for supplying magnetic toner to latent electrostatic images formed on a photoconductor, for the development of said images, for use in one or both of the development section for the two colors, whereby, by means of the so-called counter electrode effect, two-color copies can be obtained in which the so-called edge effect has been completely or substantially eliminated. In one category of embodiments, a series of ridges and grooves are formed on the outer peripheral surface of the non-magnetic sleeve. The peaks of those ridges serve to decrease the effective distance between the non-magnetic sleeve and the surface of the photoconductor, which decrease in distance is advantageous in enhancing the counter electrode effect. At the same time, the grooves provide means for the carrying of sufficient toner past a doctor in the apparatus, whereas, heretofore, getting sufficient toner past said doctor was the difficulty in decreasing the aforesaid distance from the non-magnetic sleeve to the photoconductor. In another category of embodiments, the ridges and grooves are formed spirally or in some similar orientation around the surface of the magnetic sleeve, with the effect that toner carried by the sleeve and deposited on the photoconductor is also moved in a lateral direction (axially along the surface of the sleeve), which movement serves to dislodge toner lightly held in unwanted fringe portions of the image due to incomplete, though enhanced, operation of the counter electrode effect, whereby the final traces of the edge effect are eliminated.

Improved developing device for two-color electrophotographic copying

First and second developing units (66), (67) apply toners of first and second colors respectively to a photoconductive drum (61) carrying a bipolar electrostatic image to form a bicolor toner image. A small amount of the first toner is scraped off the drum (61) in the second developing step and becomes mixed with the second toner in the second developing unit (67). The admixed first toner is separated and removed from the second toner by a separation member in the form of a roller, belt or mesh covered electrode (81) which is charged to a polarity opposite to the first toner and electrostatically attracts the same while repelling the second toner.

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Tokyo, Japan

Shuichi Tsushima