| 摘要 |
PURPOSE:To separate transfer paper stably without any light irradiating means which reduce the potential difference between an image and a no-image part even when the potential difference is large by controlling a separation current according to the value of a developing current near the front end of an image formation area. CONSTITUTION:When the circumference of the front end part of the image formation area reaches a development part, development is performed by a magnetic brush 3a and at the same time, a voltage is developed across a resistance 11 with the current developing current. The voltage is proportional to image density almost at said front end part. A DC bias setting circuit 12 generates a DC bias voltage corresponding to the terminal voltage across the resistance 11 when the circumference of the front end part reaches the development part, and the bias voltage is outputted to an AC high voltage generating circuit 13. This AC high voltage generating circuit 13 superposes the DC bias voltage upon an AC high voltage, and supplies the resulting voltage to a separation charger 5. At this time, when the developing current detected almost at the front end part of the image formation area from the terminal voltage across the resistance 11 corresponds to low image density, a separating current suitable for a low density image flows. When the developing current corresponds to a high density image, a separation current suitable for the high density image flows. |
