| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device which obtains a satisfactory transfer ability for a transfer material of any size in any circumstance and obtains a satisfactory image free from a transfer defect such as explosive or scattering independently of the supply paper width. SOLUTION: The image forming device has a transfer roll 2 of a contact type electrifying means, and a transfer bias is applied from a power source 4 to the transfer roll 2 to transfer a toner image on a photosensitive drum 1 to a transfer material P supplied to a transfer part. The power source 4 is a constant current and constant voltage power source controlled by a CPU 9, and the transfer bias is controlled to a constant current of 3.5 μA in the case of (the length in the lengthwise direction of the transfer roll (312 mm)-(the width of the transfer material)<=40 mm and is controlled to a constant voltage (ATVC control) in the other case that the length in the lengthwise direction of the transfer roll (312 mm)-(the width of the transfer material)>40 mm in accordance with the supply paper width in the direction orthogonal to the supply direction of the transfer material P, which is detected by a width detection means 10. |
