Video signal processor

TL;DR: In this paper, a direct current level correction circuit, a sink chip detection circuit, an integrator, a subtractor, a low order bit integration circuit, and a second coefficient multiplication circuit are used to remove line flicker.

Abstract: PURPOSE:To freely set clamp precision at the time of applying PWM, and to remove line flicker by providing a direct current level correction circuit, a sink chip detection circuit, a subtracter, a first coefficient multiplication circuit, a low order bit integration circuit, a second coefficient multiplication circuit, a pulse width modulation circuit, and an integrator. CONSTITUTION:The direct current level of an input analog video signal is corrected by the output of the integrator 508 by the correction circuit 501, and the input analog video signal is A/D-converted 502. The sink chip level of the converted output is detected by the detector 503, and a reference level is subtracted 504 from it. The output of the subtracter is multiplied by a prescribed coefficient by the coefficient multiplication circuit 505, and the portion of the signal of the prescribed number of bits from the least significant bit is integrated by the low order bit integration circuit 101 before this portion is rejected by the coefficient multiplication circuit 505, and a carrier signal is added to a high order bit, and the output of the integration circuit is multiplied by the prescribed coefficient by the coefficient multiplication circuit 506. As the result, the clamp precision can be set freely and correctly independently of clock frequency at the time of the PWM. If RWM input is fixed to '0' at the time of using a steady state, the direct current level of the output of the correction circuit never varies, and the flicker is never caused.