Patent ID: 6941070

Claim:
A flash device including a charging circuit for charging a main capacitor by boosting a primary voltage of a battery to a high secondary voltage and a discharging tube for emitting flash light by discharging charges stored in said main capacitor, said charging circuit comprising: an oscillation transformer having at least a primary coil and a secondary coil that are inductively coupled, said primary coil being connected to said battery, said secondary coil being connected to said main capacitor; an oscillation transistor connected to said oscillation transformer, said oscillation transistor oscillating at a current returned from said secondary coil and increasing/decreasing a current from said battery to said primary coil to generate said secondary voltage in said secondary coil, said oscillation transistor satisfying the following conditions; 330≦h FE1 ≦430 220≦h FE2 ≦240 wherein, h FE1 is a DC current gain when a collector-emitter voltage V CE of said oscillation transistor is 2V and a collector current I C of said oscillation transistor is 0.5 A, h FE2 is a DC current gain when said collector-emitter voltage V CE of said oscillation transistor is 2V and said collector current I C of said oscillation transistor is 5.0 A.