| 摘要 |
PURPOSE:To suppress the variance of electric charge density of anion current due to the change of circumstances, the secular change, or the like by directly measuring the electric charge density of the ion current to control the driving frequency or voltage of an electrostatic recording head. CONSTITUTION:A drive electrode 31 is applied with 3kV and a screen electrode 33 is applied with -1,000V, respectively with a light emitting diode array 180 lit and a photosensitive belt 2 conductive, and a negative DC voltage is successively applied to 12 groups of divided units of a control electrode 32 from a control electrode power source 38 through a divisional driving circuit 186. The control electrode voltage is controlled on the basis of a voltage detecting circuit 181 so that the current of a resistance R is 10muA, and this voltage is stored in a RAM as the set voltage for following operations. The ion current of a writing head is controlled on the basis of the set voltage so that the ion current is fixed. |
