公开(公告)号：US4001496A

公开(公告)日：1977-01-04

申请号：US594429

申请日：1975-07-09

申请人： Jon Kaufmann Clemens ,  Jack Selig Fuhrer ,  Michael David Ross

发明人： Jon Kaufmann Clemens ,  Jack Selig Fuhrer ,  Michael David Ross

IPC分类号： H04N9/882 ,  H04N5/76 ,  G11B9/06

CPC分类号： H04N9/882

摘要： In playback of a video record (e.g., in video disc form) employing a FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered. The current video signals are obtained from the output of the player's pickup-responsive FM detector (illustratively of the zero-crossing detector type) via appropriate frequency responsive circuitry comprising a low pass filter (encompassing the recorded video signal bandwidth: e.g., 0-3 MHz.). To detect the occurrence of a defect, the FM detector output is also supplied to additional frequency responsive circuitry having a wideband response which desirably extends from DC to an upper frequency limit (e.g., 0-6 MHz.) well above the highest frequency of the video signal subject to recording. The wideband circuit output is supplied to pair of voltage level comparators, one supplying an output pulse of a given polarity whenever the wideband circuit output voltage level exceeds a level representative of the FM detector output for the maximum frequency of the FM carrier deviation range employed in recording, and the other supplying an output pulse of the given polarity whenever the wideband circuit output voltage level falls below a level representative of the FM detector output for the deviation range's minimum frequency. The comparator outputs are added together to form a defect indication signal. Switching between current and delayed video signals is controlled in response to the defect indication signal. Operation in the delayed signal mode is maintained for a short period after defect indication pulse termination (to allow video circuitry stabilization following the defect transient) by rendering a retriggerable one-shot responsive to the defect indication signal, and combining the output of the one-shot with the defect indication signal to form the switching control signal.

公开(公告)号：US3969756A

公开(公告)日：1976-07-13

申请号：US522811

申请日：1974-11-12

申请人： Richard Claxton Palmer ,  Jon Kaufmann Clemens

发明人： Richard Claxton Palmer ,  Jon Kaufmann Clemens

IPC分类号： G11B9/06 ,  G11B20/06 ,  H04N5/76 ,  H04N9/82 ,  H04N9/85 ,  H04N5/82

CPC分类号： H04N5/7605 ,  H04N5/903 ,  H04N9/8222 ,  H04N9/85

摘要： Color picture information is recorded on a video disc together with multiple channels of sound information (e.g., a pair of stereo sound signal components). Each audio signal to be recorded modulates the frequency of a respectively different sound carrier over a respectively different low frequency deviation range. Picture carrier waves are frequency modulated in accordance with composite color video signals, including a luminance component and a chrominance component (the latter comprising a modulated color subcarrier buried in the midband of the luminance component). The duty cycle of the modulated picture carrier waves is varied in accordance with the sum of the respective frequency modulated sound carriers to form a recording signal. The color subcarrier frequency, and the respective sound carrier center frequencies correspond to different odd multiples of half the line frequency. The sound carrier deviation ranges lie below (but near) the band occupied by the chrominance component, and below the first order sideband of the modulated picture carrier. The black-representative picture carrier frequency is separated from the chrominance band upper boundary by a frequency substantially corresponding to the highest video signal frequency. A disc record is developed with a pattern of depressed and non-depressed regions in its groove bottom representative of the recording signal. Playback apparatus recovers from the disc record a playback signal of the general form of the recording signal. Respective bandpass filters, with passbands centered about the respective sound carrier deviation ranges, select playback signal portions for application to respective sound carrier FM demodulators. Additional filter, with passband encompassing picture carrier deviation range and first order sideband therefor, supplies input to picture carrier FM demodulator. Video signal processing circuits, responsive to output of picture carrier FM demodulator, include respective comb filters for selectively passing respective luminance and chrominance components.