| 摘要 |
PROBLEM TO BE SOLVED: To prevent a change in a concentration, without causing the increase of an image forming time and overflow and excess of toner by detecting the density of a reference toner image after being developed and changing the target value of the ratio of the toner to carriers. SOLUTION: An image density detecting means 19 is provided to face a photoreceptor drum 40 behind the development of an image forming device and a transfer member 49 and detects the reflection density of a patch image 28 on the drum. In other words, the density of the patch image 28 expected to show the concn. of the toner on a developing sleeve best is calculated from patch detection ATR and an excess or shortage of the toner obtained by the calculation is fed back to the current developing concentration obtained from developer reflection ATR, to prevent a runaway. Thus, when a signal from the patch detection ATR requires threshold control, the target value of the developer reflection ATR is changed again to obtain an excellent concentration transition. |
