| 摘要 |
<p>PURPOSE:To diminish the difference in the degree of deterioration among light emitting elements by a method wherein light emitting elements having minimum lighting times are lit during periods other than optical writing period when the difference between the maximum and minimum lighting times of two or more light emitting elements becomes larger than a set value. CONSTITUTION:When a page of printing has been finished, the lighting times of light emitting elements are counted and stored by a counter circuit 18, and the signals are input to a CPU 19. The CPU 19 compares the light emitting times with one another and detects the maximum lighting times. Then, the CPU 19 compares the maximum lighting times with the lighting times of the other light emitting elements to calculate the differences, and outputs data signals equivalent to the differences so as to turn on the other light emitting elements during periods except printing period. Thereby, all the light emitting elements are lit the same times as the maximum lighting times for every page, so that the difference in the degree of deterioration among the light emitting elements becomes nearly nil.</p> |
