| 摘要 |
PURPOSE:To prevent adhesion of carriers to the no-image area of a photosensitive body, by controlling the absolute value of a bias voltage applied across a developing means when a photosensitive body area is passed through the developing means after passing through an optical recording means at the time when the light is turned off to a level higher than that at the time when the light is turned on. CONSTITUTION:A varister 4c and biasing power source 4b are connected in series with a developing sleeve 4a which carriers a magnetic developing agent (not shown in the figure) and a biasing relay contact 4d is connected in parallel with the varister 4c. While a printing area is passed, the relay contact 4d is short-circuited and an inversional biasing voltage, VB1=-400V, is applied across the developing sleeve 4a and, as a result, negative toner is sufficiently adhered to a low-potential section (section where the micro-shutter is opened with V2=-20V). Thus inversional development is carried out. Even a bit of toner does not adhere to a constant-potential section (section where the micro-shutter is closed). |
