| 摘要 |
PROBLEM TO BE SOLVED: To perform light control processing for adjusting the light quantity of each light beam in a short time by using one photodetector in a light beam performing a scanning with a plurality of light beams. SOLUTION: On the basis of image data 41-44 whose density changes like signal wave forms 51-54 (frequencies f1-f4), a first to fourth light beams are emitted simultaneously and are detected by one photodetector, then the signals are inputted in a first to forth band pass filters(BPF). The first BPF makes only the signal of f1 pass there through the second BPF makes only the signal of f2, pass there through the third BPF makes only the signal of f3 pass there though and the 4th BPF makes only the signal of f4 pass there though. An outputted signal from each BPF expresses the light quantity of the first to fourth light beans emitted according to the image data 41-44 whose frequencies are f1-f4. The sizes of the outputted signals are detected, and the light quantity of each light beam is adjust so that the value of the size is the value to be outputted when each light beams is emitted with a proper light quantity.
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