| 摘要 |
PURPOSE:To prevent the interference with other circuits, by feeding power from a power source circuit in complementary phases in parallel with a series circuit, which includes a light emitting element, a switching element, and the power source circuit, to keep a current constant. CONSTITUTION:A shunt consisting of a transistor TRQ2 and a resistance R3 is provided besides a light emitting element LD and an LD driving circuit consisting of a current limiting resistance R1 and TRQ1. A high frequency driving signal vi is applied to this LD driving circuit through a resistance R2, and meanwhile, the signal vi is inverted by an inverter I and is applied to the TRQ2. The high frequency pulse driving signal vi shown in figure (b) is applied to the base of the TRQ1 to control turn-on and off of the TRQ1, and a current i1 shown in figure (b) is flowed, and the driving signal vi is inverted by the inverter I and is applied to the base of the TRQ2 to control turn-on and off of the TRQ2, and a current i2 shown in figure (b) is flowed. Thus, currents i1 and i2 are complementary, and the sum of them becomes constant approximately, thus preventing the inductive interference with other circuit devices. |
