PURPOSE: To control a photosensitive body optionally dependent on a treating process of the photosensitive body or detect information from the photosensitive body by providing an array head wherein working elements for controlling an energized state of a control electrode for controlling the photosensitive body in the vertical scanning direction are arranged in the same direction.

CONSTITUTION: When working elements 43 emit light, a switching element is made to be conductive, a bias voltage is applied to a control electrode 23 from an external electrode 31, and a signal current is taken out to the electrode 31. By providing an array head 41 wherein the working elements 43 are arranged in the vertical scanning direction, a photosensitive body 11 can be controlled at a unit of the vertical scanning direction. By adjusting the length of the vertical scanning direction of the array head 41 and ON/OFF of the working elements 43, the photosensitive body can be controlled by dividing it at an optional unit in the vertical scanning direction. Further, by setting emitting strength, temperature, current, and voltage of the working elements 43 properly, the conductive degree of the switching element can be controlled, and magnitude of output for the control electrode can be set optionally.