Hitachi, Ltd.

Nobuo Tokoro

Toru Miyasaka

Akira Shimada

Shin-ya Sato

In an image forming apparatus using an electro-photographic process, using a plurality of colors of toner including black toner, a reflectance of a base medium on which a toner image is formed is higher than that of black toner itself and lower than that of color toner. A toner deposit amount sensor provided in the image forming apparatus has a light-receiving element provided in the regular reflection direction from a toner image on the base medium. The light-receiving element has a wide light-receiving area so as to receive at least a part of irregularly reflected light besides regularly reflected light. The light-receiving element is then stored in a container for preventing the element from being contaminated by scattered toner, except the time of toner deposit amount measurement. Measurement characteristics of the toner amount sensor are corrected when being stored in the container by using a correction plate provided in the container. Furthermore, the deposit amount of each color of toner is controlled by relations between image forming control parameters and the deposit amount of each color of toner is controlled by relations between image forming control parameters and the deposit amount of each one of the plurality of colors of toner and black toner, the relations being memorized in advance.

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Hitachi, Japan

Nobuo Tokoro