| 摘要 |
PROBLEM TO BE SOLVED: To provide a flash charging circuit of which charging period of a capacitor does not fluctuate even if a battery voltage fluctuates. SOLUTION: A blocking oscillation circuit is constructed by serially connecting the battery Batt, a primary winding N1 of an oscillation transformer TF1 and an oscillation transistor Q4, and connecting an output of a feedback coil N3 to a base of the Q4 through a serial circuit of the capacitor C1 and a resistor R5, and connecting a diode D1 between the base and emitter of the Q4 in the direction of discharging the electric charge accumulated by a positive feedback current. The fluctuation of the charging period of the C1 generated by the fluctuation of the battery voltage is reduced by making the voltage of a base current supply source constant by taking out a direct current voltage by connecting a main capacitor C2 to a secondary coil N2 of the TF1 through a rectifying diode D2, and connecting a circuit composed by serially connecting a resistor R4 and a diode D3 in forward direction, in parallel with the Batt, and connecting the connection point of the R4 and the D3 to the base of the oscillation transistor through a resistor R9. COPYRIGHT: (C)2004,JPO |
