The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 28, 1999
Filed:
Jan. 11, 1996
Mehrdad Nayebi, Palo Alto, CA (US);
Duc Ngo, Jan Jose, CA (US);
Sony Corporation, Tokyo, JP;
Sony Electronics, Inc., Park Ridge, NJ (US);
Abstract
A backporch soft-clamp circuit using a servo loop clamps the blank or DC level of a composite video signal to a known value without altering the other components of the signal. The values of the components of the composite video signal are determined by determining their amplitude with respect to the blank level. The backporch soft-clamp circuit sets the blank level to a known value for determining the true value of the components. An output composite video signal is generated which represents the input composite video signal with the blank or pedestal level set to a known DC level. Preferably, the DC level is set to two volts. A burst gate pulse representing the presence of a burst signal within the composite video signal is received by the circuit. During the burst period, the circuit soft clamps the blank level of the output signal to the appropriate level without altering the content of the burst signal. The DC level of the output signal is compared to the appropriate level by a comparator circuit. During the burst period, if the DC level of the output signal is less than the appropriate level, it is raised by a charging circuit. During the burst period, if the DC level of the output signal is greater than the appropriate level, it is lowered by a discharging circuit. During non-burst periods, when the burst signal is not present within the composite video signal, the charging and discharging circuits are disabled and the DC level of the output signal is maintained at a constant level.