US RE40,689 E1
Method and apparatus for disabling anti-copy protection system in video signals
Ronald Quan, Cupertino, Calif. (US); and John F. Peruzzi, Redwood City, Calif. (US)
Assigned to Macrovision Corporation, Santa Clara, Calif. (US)
Filed on Mar. 16, 1995, as Appl. No. 8/405,482.
Application 08/614185 is a continuation in part of application No. 06/935055, filed on Nov. 21, 1986, granted, now 5,130,810.
Application 06/935055 is a continuation of application No. 06/554697, filed on Nov. 23, 1983, abandoned.
Application 08/405482 is a reissue of application No. 08/614185, filed on Nov. 13, 1990, now 5,194,965, filed on Mar. 16, 1993.
Int. Cl. H04N 5/76 (2006.01); H04N 5/93 (2006.01); H04N 7/00 (2006.01); H04N 7/167 (2006.01); H04N 9/00 (2006.01); H04N 9/79 (2006.01); G11B 15/04 (2006.01); G11B 19/04 (2006.01)
U.S. Cl. 386—94  [386/1; 386/45; 386/46; 386/83; 386/E5.004; 386/93; 360/60; 380/201; 380/203; 380/204] 41 Claims
OG exemplary drawing
 
[ 18. A method for reducing effects of copy-protect signals in vertical blanking intervals of a video signal, said copy-protect signals including pulses added to said vertical blanking intervals, said method comprising the steps of:
receiving a video signal having said pulses added thereto;
detecting a vertical blanking interval of said video signal;
shifting a voltage level of at least a part of said video signal in said vertical blanking interval, wherein the only negative-going pulses present in said vertical blanking interval extending below a voltage reference level are horizontal sync pulses, thereby enabling copying of said video signal.]