| 摘要 |
PURPOSE:To prevent excessive photo power transmission for preventing a short life of an output light source by providing a power generating energy detecting means and a signal overlapping means on a signal processor side and a signal separating means and a light emission amount controlling means on a driving side. CONSTITUTION:A driving device 1 controls a laser light source 11 so that sum of output of a light amount controlling photo diode 13 and output of a signal processing unit 17 is constant, while the laser is modulated by pulse signals and an amplifier circuit 14 controls a peak value. A light signal is sent to a processing circuit II with an optical fiber 30. A conversion processing unit 26 is driven via a photo diode 21 and a transformer 22. With input photo power compared with reference voltage, if the input is smaller, output of a comparator is overlapped with output of the conversion processing unit. When a modulation circuit 27 senses drop in photo power, a sensor outputs and sends frequency signals (b) of double pulses to the driving device I. A separating demodulation circuit 16 separates output (a) of the voltage comparator 24 from the sensor signal (b) and the signal processing unit 17 increases/decreases the signals to a control amplifier according to existence or not of the signal so that the signal is suppressed to be the minimum photo power required for detection of a sensor 25 thereby lengthening laser life. |
