| 摘要 |
PROBLEM TO BE SOLVED: To reduce the useless consumption of power without imposing burdens on constitution. SOLUTION: For this power unit, the Zener diode ZD for reference voltage formation of a DC stabilized power source circuit 20A for a sub power source is connected to the base of a Q1 interposed serially to a sub power source output line (S+), and the power supply voltage for inverse bias of the ZD is applied from the main power source output line (M+) of a main power source circuit 5 through a resistor R2. Then, when a system controller 31A performs the OFF control of a main power source and opens relay switches 4a and 4b, the voltages +Vm' and -Vm' of the main power source output lines (M+) and (M-) drop down to the ground potential. When the voltage +Vm' becomes the ground potential, a voltage between both terminals of the ZD becomes zero. At the time, since a current does not flow through the resistor R2 to the base of the Q1, the Q1 is completely turned OFF. Thus, sub power source output +E' is completely dropped to zero. |
