| 摘要 |
PURPOSE:To attain high-speed response of a light emitting element and to reduce current consumption by connecting an FET in parallel with the light emitting element to bring the FET to the pinch-off state at the lighting of the light emitting element and the FET to the operating state at the extinction of the light emitting element. CONSTITUTION:An anode of a light emitting diode PD2 and a drain of the FET5 are connected to a positive power supply terminal 1, a cathode of the PD2 is connected to the source of the FET5 and a resistor 6, a gate of the FET5 and a collector of a transistor (Tr)3 is connected respectively to the other end of the resistor 6. When the Tr3 is turned on, a current flows to the PD2 and the resistor 6, the PD2 is lighted, the FET5 is brought into the pinch-off state by a voltage drop across the resistor 6 and no current flows to the FET5. When the Tr3 is turned off and the PD2 is extinguished, the source and gate of the FET5 reach the equi-potential, the FET5 is operative, the electric charge stored in the capacity of the PD2 is discharged through the FET5 and high-speed response is attained. |
