| 摘要 |
PURPOSE:To prevent the degradation in picture quality due to erroneous detection of a toner by providing a guide block between a sensor head and a doctor to prevent a developer from being pressed into the space between them. CONSTITUTION:A developer 3 attracted to and carried by a magnet roll 2 is guided downward and to both sides by guide faces 10 and 10 of a guide block 8 when passing a sensor head 6 and is moved. Therefore, the developer 3 is inverted when stopped by a doctor 4 and passes both sides of the sensor head 6 and is returned to a developing tank smoothly. Thus, it is eliminated that the output of a permeability sensor rises abnormally independently of an actual toner concentration because the developer 3 is pressed into the space between the sensor head 6 and the doctor 4 to raise the density. Thus, the degradation in picture quality due to erroneous detection of the toner concentration is prevented. |
