| 摘要 |
PURPOSE:To prevent the deterioration or destruction of the characteristic of each of LED elements caused by the use at tolerant use temp. or more, by a method wherein the number of LED elements allowed to light are counted and when the count value per a unit time becomes a predetermined value or more, the current supply time rate of an LED array is reduced. CONSTITUTION:The temp. of an LED array 28 rises so as to be almost proportional to the quantity of power consumed in the LED array. Therefore, the present temp. state of the LED array can be estimated on the basis of the past count data for 30min stored in an area 80a. On the basis of this estimation, the current supply rate of the LED element of the LED array 28 lighting at the time of next print-out is controlled at every one line by CPU 76. Further, tolerant temp. data is stored in the area 80b of a memory 80 and temp. data is stored in the area 80c of the memory 80. This temp. data makes the rotation of a photosensitive drum 26 slow and makes the cooling time of the LED array 28 long. Therefore, this data becomes one for operating a main motor 72 at a low speed.
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