Image forming apparatus

An image forming apparatus comprising:

• a latent image holding body on which an electrostatic latent image is formed;
• a developing device developing said electrostatic latent image to produce a visible developed toner image, said developing device being detachably loaded in said image forming apparatus;
• a transfer device transferring said developed toner image onto a printing medium;
• a fixing device for fixing said transferred image;
• means for preventing an incorrect developing device loaded in the image forming apparatus from being placed in a development enabled condition;
• means for detecting an operating state of said preventing means;
• and
• a detecting device for detecting the presence or absence of a developing device in a redundant manner for restricting operation of said image forming apparatus under a non-loaded condition of the developing device.

An image forming apparatus comprising:

• a latent image holding body on which an electrostatic latent image is formed;
• at least one developing device developing said electrostatic latent image to produce a visible developed toner image, said developing device being detachably loaded in said image forming apparatus;
• a transfer device transferring said developed toner image onto a printing medium;
• a fixing device for fixing said transferred image;
• means for preventing an incorrect developing device loaded in the image forming apparatus from being placed in a development enabled condition;
• and
• means for detecting an operating state of said preventing means;
• wherein said detecting means is provided in a loading portion of said developing device in a main body of said image forming apparatus and is electrically opened and closed only upon operation of said developing device, and
• when said image forming apparatus is loaded with a plurality of said developing devices, said detecting means detects variation of one electric signal as output of a plurality of detecting means connected in parallel.