Mitsubishi Denki Kabushiki Kaisha

Ikuo Ookuma

Sadayuki Inoue

Toshifumi Fujii

Kenji Tsunashima

Hideki Kaneko

Yoshiyuki Sasaki

A video signal clamping circuit capable of maintaining a DC level of a digital video signal at a fixed level, in which a pedestal level in a vertical blanking period of the digital video signal after an A/D conversion is sampled, and an average value of a plurality of sampling data in a plurality of fields is calculated by an average value calculator. The average value is compared with a predetermined clamp level reference value by a comparison output circuit, and depending on the comparison result, a signal either added or subtracted by a certain width to or from an output signal of a predetermined period before is output for automatically controlling a clamp voltage.

Video signals clamping circuit for maintaining DC level of video signals

A characteristics corrector in a video signal processing system is described for correcting characteristics of the video signal processing system at the time of recording and/or reproducing a video signal. The corrector includes a reference pulse generating circuit for generating reference pulses of varying amplitude corresponding to gradations from a black level to a white level of a video signal to be recorded during a blanking period of the video signal to be recorded. It further includes a pulse amplitude data generating circuit for generating quantified data used for the discrimination of the amplitudes of the reference pulses. Also, a reference data interleaving circuit is included for interleaving, as a reference data, the reference pulses and pulse amplitude data indicative of the amplitudes thereof during the blanking period. Finally, a level correcting circuit is included for correcting the level of a reproduced video signal by the utilization of a plurality of reference pulses and pulse amplitude data obtained from the reproduced video signal.

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Nagaokakyo, Japan

Ikuo Ookuma