| 摘要 |
PURPOSE:To obtain picture image free from concentration changes, by controlling the charge injection amount depending on the potential of the developer and keeping constant the potential of toner particles, in a developing apparatus designed to charge the one-pack developer by charge injection. CONSTITUTION:Magnetic toner particles 3 of a one-pack developer on a developing sleeve 1 supplied from a toner supply device 2 are defined to a specified height by means of a conductive blade 5, and are dielectrically charged by the charge injected from the blade 5, and an electrostatic latent image is formed by contacting with a photosensitive drum 6. The potential of the toner particles on the sleeve 1 is detected by a detector P which comprises a capacitive probe, and is amplified by an amplifier A1, then compared with a reference voltage VREF by a comparator comprising an amplifier A2. This output signal is applied to said blade 5 through a circuit consisting of resistors R3, R4, diode D1, and capacitor C1. Therefore, the charge injection amount is controlled according to the potential of the toner particles is maintained at a constant level, so that concentration changes of the developed image may be prevented. |
