| 摘要 |
PURPOSE:To correctly deal with various kinds of originals and to prevent the occurrence of fogging by selecting two control modes and controlling a development bias output according to the control procedures of a storage means based on the selected control modes. CONSTITUTION:Development bias control procedures stored in a ROM 42 have two modes; one is a continuous AE mode, wherein density information (latent image potential) covering the leading edge to trailing edge of an original is detected to control a development bias based on the sequential information. A latent image formed in an exposure area by an optical system comes to a potential sensor 21 owing to the rotation of a drum-like photosensitive body 15, and latent image potentials are detected at fixed interval as a spot. The detected latent image potential information is inputted to a CPU 40 via an A/D converter 43. The CPU 40 executes calculation to determine a development bias voltage, and its timing is controlled so that when a point to detect the latent image comes to a position facing a developing roll 32a, a development bias voltage corresponding to the position is applied. Thus, the occurrence of fogging is prevented. |
