Abstract: A color image forming apparatus wherein a plurality of developing devices or units are supported on a supporting member or turret which is rotatable to revolve the developing devices to move a desired one of the developing devices to a developing station where the developing operation is effected with the desired one of the developing devices so that a color image is formed. The presence, absence or the amount of the developer within the developing devices are detected. When the detection indicates that the toner is to be supplied into a developing device, the developing device is moved to a predetermined developer supplying position, and then is stopped so that the developing device is supplied with the developer at the developer supplying position.

Abstract: A color image forming apparatus wherein a plurality of developing devices or units are supported on a supporting member or turret which is rotatable to revolve the developing devices to move a desired developing device to a developing station where the developing operation is effected with the desired one of the developing devices so that a color image is formed. The position of the developing device is detected, and the detected position is compared with a datum of a target movement scheme predetermined for the developing apparatus. A driving motor for the apparatus is controlled to correct the difference therebetween which is the result of the comparison.

Abstract: The present invention provides an apparatus wherein image fixing means is controlled for different fixing conditions under which a toner image is fixed on a recording material to adapt it to a synthetic resin sheet as the recording material or to a color image to be fixed, including at least one of fixing temperature, fixing speed and actuation of cleaning means. The present invention is particularly effective in use for a recording system in which the fixing temperature and speed are decreased and the cleaning means is actuated when a color image is to be formed on a transparent or resin sheet. The present invention is most useful for a color image recording system.

Abstract: Heating unit capable of generating heat upon the passing of an electric current, which comprises a matrix of a hardened hydraulic material and electrically conductive fibers dispersed therein in an amount sufficient to impart electric conductivity and a method for producing the heating unit, which comprises kneading a hydraulic material, water and conductive fibers, optionally molding the kneaded mixture, and then hardening the mixture. The heating unit can be used in various applications such as general household applications, civil engineering applications, industrial applications and railroad applications.