| 摘要 |
PROBLEM TO BE SOLVED: To always perform optimum density correction without being influenced by the characteristic of a density sensor in an automatic density mode. SOLUTION: The density of an original is detected by an ADS sensor 1 and the surface potential of a photoreceptor is detected by a potential sensor 2. When the minimum value of the surface potential is equal to or under a reference value, a developing bias correction part 3 prevents overcorrection by selecting fixed developing bias previously set without depending on the density of the original. When the minimum value of the surface potential exceeds the reference value, the correction part 3 decides the developing bias by setting the minimum value of the surface potential as reference in the case a difference between a developing bias correction value in accordance with the density of the original and the minimum value of the surface potential is equal to or under the reference value, and it decides the developing bias by setting the developing bias correction value as the reference in the case the difference between them exceeds the reference value. |
