Ricoh Company, Ltd.

Ricoh Corporation

Hideo Yoo

Kohji Suzuki

Koji Suzuki

Hajime Oyama

Noboru Sawayama

Shinichi Namekata

Takashi Bisaiji

Yuji Sawai

Yoshio Takamiya

Tsutomu Shoji

In a multicolor image-forming apparatus having a photoelectric sensor for detecting the amount of toner of an unfixed toner image adhering onto a photosensitive element, and a toner density sensor for detecting the density of a developer in a developing machine to form a multicolor image by overlapping the toner images having a plurality of colors, a color-balance control method comprises the steps of correcting a setting value of an output of the toner density sensor of the developing machine in accordance with the change in amount of toner adhering onto a photosensitive element detected by the photoelectric sensor with respect to a high density section; setting an allowable range of the toner density in advance in the developing machine with respect to the toner having at least one color; setting the amount of toner adhering onto a photosensitive element of the at least one color as a reference when the toner density is changed outside the allowable range; and correcting the amount of toner adhering onto a photosensitive element of the other color in accordance with the reference. With respect to a half-tone section, the output of the photoelectric sensor may be corrected by controlling the exposure amount. With respect to the high density section, the output of the toner density sensor may be corrected in a predetermined way when the toner density is changed.

Color-balance control method

A device for controlling the density of toner of different colors individually stored in a plurality of developing units which are arranged around a photoconductive element senses toner density at a predetermined period which differs from one of the developing units to another. Each of the developing units is associated with a different kind of toner density sensing device.

Toner density control for multicolor electrophotographic copier

In an image recording device, particularly suitable for the reproduction of colored images, two images are superimposed on a recording sheet. The second image is so designed that it compensates the undesirable saturation of density under an ordinary condition and that the superimposed image has an improved tone reproduction. The superimposed toner images are heat-fixed together on the print.

Colored image recording device

A cleaning apparatus is disclosed which removes residual toner particles from a photoconductor by use of magnetic carrier particles. The carrier particles form magnetic brushes which adsorb and thereby remove the residual toner particles from the photoconductor. Two relay sleeves each having permanent magnets thereinside cause the removed toner particles to circulate together with the carrier particles. A toner collector roller and a counter electrode face each other at opposite sides of a circulation path for the carrier particles which are carrying the toner particles therewith. The toner collector roller collects the toner particles adsorbed by the carrier particles. The counter electrode comprises a relatively narrow and grounded conductive electrode portion and a relatively wide insulator portion.

Photoconductor cleaning apparatus

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Tokyo, Japan

Hideo Yoo