| 摘要 |
PROBLEM TO BE SOLVED: To appropriately control grain and sharpness in a formed image by providing a control means for changing the frequency of dormant periods while making the ratio of the dormant periods in a fixed period constant. SOLUTION: The state of AC voltage applied from an AC power supply 15 is controlled by a control means 16. Action periods of making the AC electric field act by applying AC voltage, and dormant periods of not making the AC electric field act without applying AC voltage, are alternately repeated to perform development. At the time of controlling the image quality of formed images, the frequency of the dormant periods is changed by shortening the length of one dormant period to increase the frequency of the dormant periods or lengthening the length of one dormant period to reduce the frequency of the dormant periods while making the ratio of the dormant periods in a fixed period constant. Appropriate image quality control corresponding to the formed image can therefore be performed without large fluctuation of image density. |
