Abstract: An image forming apparatus is provided with a developing device for developing a latent image formed on the surface of the photosensitive drum. The developing device includes a first developing unit for developing the latent image by use of a first color developing agent and a second developing unit for developing the latent image by use of a second color developing agent. The first and second developing units are selectively driven and devices for inserting/removing the first and second development units are also provided. The image forming apparatus has a selecting device for interrupting an image forming process which is in progress to automatically select an image forming process which uses the second developing unit.

Abstract: An image forming apparatus is provided with a developing device for developing a latent image formed on the surface of a photosensitive drum. The developing device includes a first developing unit for developing the latent image by use of a first colon developing agent and a second developing unit for developing the latent image by use of a second colon developing agent. The first and second developing units are selectively driven and devices for inserting/removing the first and second development units are also provided. The inserting/removing device includes a handle on the developing unit having first and second hooks which are rotated by the handle to engage pins on the housing of the image-forming apparatus to lock the developing unit in operative relationship with the photosensitive drum.

Abstract: An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a color developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units are alternatively driven by a switch provided on a control panel which is located on the housing. The first developing unit is in the form of a cartridge which can be removably set in the housing. A pair of positioning members are attached to the front and rear walls of the developing agent supply section of the first developing unit. Both end support portions of the handle are swingably mounted on the positioning members by supporting shafts, individually. Each support portion of the handle is fitted with a hook which can rock around its corresponding supporting shaft.

Abstract: An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a first red developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units, each of which includes a developing roller and a magnet roll, are alternatively driven by a switch provided on a control panel which is located on the housing. The respective magnet rolls of the first and second developing units are allowed to rock through about 25 degrees each. As the magnet rolls rock within this range, magnetic brushes of the developing agents can be formed on the surfaces of the developing rollers, respectively, or removed therefrom.

Abstract: An image-forming apparatus is provided with a photosensitive drum rotatably located in a housing, and a developing device for developing the latent image formed on the surface of the photosensitive drum. A first developing unit of the developing device develops the latent image by a first red developing agent. A second developing unit develops the latent image by a second black developing agent. The first and second developing units are alernatively driven by a switch provided on a control panel which is located on the housing. A copy mode for black is automatically established when the power is turned on or if no operation is performed for a prescribed time after a foregoing copying operation, in a mode for any other color than black, is ended.