| 摘要 |
PURPOSE:To obviate a signal processing by means of a digital circuit other than the circuit concerned by connecting a sub-signal as an analog signal to the drain electrode or source electrode of a second FET driving a light emitting element. CONSTITUTION:The cathode electrode of a level shifting Zener diode 3 is connected to the drain electrode of a first FET(field effect transistor) 1, whose gate electrode terminal (a) a main digital data signal is inputted to. Further, the gate electrode of a second FET 4 is connected to the anode electrode of the Zener diode 3, and the cathode electrode of a light emitting element 5 is connected to the drain electrode of the second FET 4, a drain electrode terminal (b) of the second FET 4 is inputted, and a sub-signal amplifying circuit 12 is connected through a choke coil 11. In such a way, the sub-signal is superimposed on the main digital data signal of a light emitting element driving circuit. Thus, the signal processing by the different digital circuit is obviated, the circuit can be comparatively simplified, and energy consumption can be reduced. |
