| 摘要 |
<p>PURPOSE:To suppress a change in the current consumption considerably small in the pulse radiation system and to prevent adverse effect onto other circuit by using the voltage of a capacitor charged by a constant current for a power supply of a projection light driving circuit and a light emitting diode. CONSTITUTION:When a timing pulse of an H level from a timing generating circuit 2 is not applied to the base of a transistor(TR) 31, a capacitor 12 is charged by a constant current with a constant current circuit 11. When a timing pulse is fed to the base of the TR 31, the TR 31 is turned on and succeedingly a TR 32 is also turned on. Thus, a light emitting diode 4 is connected to the ground via a resistor 33 and a charge from the capacitor 12 is discharged via the diode 4, a TR 32 and the resistor 33. Thus, the diode 4 is lighted for only a time corresponding to the pulse width from the circuit 2. Since the power charged in the capacitor 12 is sued for the power supply for the light projection driving circuit 3 and the light emitting diode 4, the change in the current consumption is much suppressed regardless of the pulse lighting system and the adverse effect onto other circuit is prevented.</p> |
