Auto-pedestal level clamp circuit
AssigneeCitizen Watch Co., Ltd.
InventorsFuminori Suzuki, Kiyoshi Kamiya
Life of this patent
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Abstract
An auto-pedestal level clamp circuit, which clamps a pedestal level of a television signal input through a DC blocking capacitor using a pedestal level clamp switch to automatically adjust the pedestal level, includes a level detecting circuit for detecting a luminance signal level of the television signal, and an A/D converter for judging a luminance of a frame based on the output from the level detecting circuit. The level detecting circuit includes first and second gates, first and second switches controlled by the first and second gates, and a smoothing circuit. The pedestal level of the television signal input to the level detecting circuit through the pedestal level clamp switch is adjusted based on an integral potential level of the output from the A/D converter.
Claims11
An auto-pedestal level clamp circuit, which clamps a pedestal level of a television signal input through a DC blocking capacitor using a pedestal level clamp switch to automatically adjust the pedestal level of the television signal, comprising:
- level detecting means for detecting a luminance signal level of the clamped television signal, said level detecting means comprising an A/D converter for converting the luminance signal into a digital signal;
- and
- judging means for judging a luminance of a frame based on the output from said level detecting means, said pedestal level clamp switch having means to adjust the pedestal level of the television signal input to said level detecting means based on an integral potential level of the output from said judging means.
An auto-pedestal level clamp circuit for automatically adjusting and clamping a pedestal level of a television signal, said circuit including means to detect the luminance level of said television signal, said luminance level detection means comprising means to determine when said luminance level is below a pre-determined minimum and above a pre-determined maximum, including a plurality of comparators, a first one of said comparators having means to define the pre-determined minimum, and a second one of said comparators having means to define the pre-determined maximum, means responsive to said luminance level detection means to automatically adjust and clamp the pedestal level of said television signal when said luminance level is outside said pre-determined minimum and maximum, and said detection means further includes means to convert the television signal into a digital signal comprising an A/D converter, said digital signal being input to the adjusting and clamping means.
Dependencies are inferred from the claim text.