| 摘要 |
An image forming apparatus comprises a photoreceptor (1); plural developer units (2, 3) for giving toner alternatively to the photoreceptor (1) to develop a latent image formed on the photoreceptor (1); toner density sensors (35, 37) for detecting the toner density of the developer units (2, 3); toner supplier for supplying toner to the developer units (2, 3) according to the output of the toner density sensor (35, 37); detector (35, 47) for detecting whether said developer units (2, 3) are attached with respect to the periphery of the photoreceptor (1); and controller (40) for so controlling the image forming operation as to be performed only when a predetermined plural number of developer units (2, 3) are attached. According to the image forming apparatus, it is possible to correct the output of the toner density sensor (35). <IMAGE> |
