IMAGE FORMING DEVICE

PURPOSE:To set the light-off timing of a blank lamp automatically in a short time with no consumption of recording paper by determining a span of time till the blank lamp is made to go out since a reference point of time on the basis of preset first time and light-off timing compensation time. CONSTITUTION:After a sensitizer 1 is driven and a blank lamp 3 is lighted, when the preset first time since a reference point of time has elapsed, the blank lamp 3 is put out. Time till a blank part rear end cut position of a sensitizer surface is detected by a blank part rear end cut position detector 4 from the reference point of time is measured by a timer means 13, and light-off timing compensation time is calculated on the basis of the preset second time and another time measured by the timer means 13 by a centrap processing unit 10. In addition, time till the lamp 3 is put off from the reference point of time is determined on the basis of the first time and the light-off timing compensation time. With this constitution, the light-off timing of the lamp 3 is determined automatically in a short time, with no consumption of recording paper.