| 摘要 |
PURPOSE:To control an oscillatory mirror driving current to its reference amplitude even if the amplitude varies owing to variation in load and to stabilize the amplitude by calculating the integral value of the difference between a reference amplitude pulse width and an amplitude detection pulse width and controlling variation of the oscillatory mirror driving current and its variation width on the basis of the integral value. CONSTITUTION:An oscillation detection system 2 detects the amplitude of an oscillatory mirror and outputs its amplitude as a pulse width at every period, a comparing circuit 4 calculates the difference between the detected pulse width and a reference pulse width outputted by a reference pulse width generator 3, and an integration circuit 10 integrates the difference, whose integral value is converted into a voltage by a voltage converting circuit 5. A composing circuit 7 composes a signal of the output of the voltage conversion circuit 5 and the detected period of an amplitude detection system 2 and the composite signal is shaped by a waveform shaping circuit 8 into a sine wave, which is applied to an oscillatory mirror driving coil 1 through an amplifier 9 to control the driving circuit to the oscillatory mirror. Consequently, the reference value is controlled to a command even if the load varies.
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