| 摘要 |
PROBLEM TO BE SOLVED: To provide a power source unit for presenting a system with an optical source capable of feeding excessive power, which is provided with a protecting circuit momentary surge on an input line at the time of feeding excessive power for the light source. SOLUTION: A power source unit is provided with an input line 38 which is connected to an external AC power source 40, two output lines 42, 44 and a relay 58 selectively connecting the input line to one of the output lines. The relay is controlled indirectly by a voltage-detecting circuit 50, converting the voltage value of an AC power source into a DC output voltage, which is tested to decide whether the input line is in a low or high voltage state. The high- voltage state is equivalent to a surge on the input line. The output lines 42 and 44 are connected to a light source to show by the light source a voltage lower than a voltage, when the AC voltage is applied to the second output line 44, when the AC voltage is applied to the first output line 42. Then, when the relay connects the input line to the second output line, the light source is fed with an excessive power. |
