DIRECT CURRENT RESTORATION CIRCUIT

摘要

PURPOSE:To eliminate signal distortion near a vertical synchronizing signal and to prevent variation in DC restoration level due to an input signal by utilizing the switching operation of a transistor (TR) when the DC component of a video signal is restored. CONSTITUTION:The video signal impressed to an input terminal 16 is applied to the base of a TR17. The emitter terminal of the TR17 is connected to a constant current power source 25 through a capacitor 18 and also connected to the emitter of the 2nd TR19 for clamping. The capacitor 18 blocks unnecessary low frequency components. The TR19 has the base voltage held constant by the bias circuit consisting of resistance 20 and 21 and a capacitor 22, and its connector is connected to the base of a TR24. Those TRs 19 and 24 restores the DC component of the input video signal into a bias voltage V1.