Video signal processing circuit

Abstract

Abstract PURPOSE: To prevent fluctuation of the black level dependent upon irregularity of a set-up level, by detecting the level in the most black side in the video period and by regarding this level as black to set this level as the cut-off level of the Braun tube. CONSTITUTION: Video signal S 1 is supplied from a video detecting ciruit to input terminal 1 and is input to blanking circuit 2 and a section wider than the horizontal blanking time is blanked by blanking pulse P 1 from terminal 3, and output signal S 2 is supplied to peak hold circuit 4 to form hold output S 3 corresponding to the level in the most black side in the video period, and this output S 3 is supplied to next comparator 5 and compared with video signal S 1 , and signal S 4 which is more white-side level one of both signals is generated and is supplied to next clamp circuit 6. Clamp pulse P 2 is supplied to circuit 6 from terminal 7, and video signal S 5 with the blanking time arranged into a prescribed level is obtained from output terminal 8. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Takafumi Okada
• 👤 Atsushi Matsuzaki

Bibliographic Details