| 摘要 |
PURPOSE:To put tops for recording in order with a simple constitution irrespective of the rotating speed of a rotating mirror by controlling a optical modulation element drive circuit based on the detection signal of a photodetecting element arranged in the vicinity of a recording medium and switching a supply signal to the optical modulation element. CONSTITUTION:When the rotating mirror 3 begins to rotate, a detection element signal (a) denoting a start point in a synchronizing signal detection area is transmitted to an area designation circuit 9 from a switching detection element 6. A circuit 11 sets a flip flop signal Q at 'H' based on the detection element signal (a) to control a signal switching part 111, and supplies a reference voltage (g) to the optical modulation element 2. After said element 2 increases and decreases the luminous energy of a laser tube 1 to a fixed luminous energy with the aid of the reference voltage (g) of the optical modulation element drive circuit 11, said element 2 irradiates the photodetecting element 7 on a scan route. A synchronizing signal generator circuit 8 generates a synchronizing signal (c) from a signal obtained in the photodetecting element 7, and outputs it to a picture information output circuit 10 and the area designation circuit 9.
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