| 摘要 |
PURPOSE:To decrease the projection frequency and to increase the peak value of the pulse beam by driving the light emitting diode in synchronization with the AC power source, thus improving the S/N. CONSTITUTION:Light emitting element 57 and the main electrode of PUT51 containing two main electrodes and one control electrode are connected forward, and then discharged electric charge storage capacitor 52 is connected. Furthermore, resistance 54 is connected between the control electrode of PUT51 and element 57. At the same time, the anode of PUT51 is connected to AC power source 60 via resistances 55 and 56 plus semiconductor rectifier 59, and capacitor 53 is connected to the joint between the control electrode of PUT51 and resistances 55 and 56. Then PUT51 is driven by the electric charge stored in capacitor 52 and in synchronization with power source 60 with the duty factor of the driving current decreased and the peak value set to a high level. Thus the S/N can be improved. |
