Rca Inc.

Jon K Clemens

Michael D Ross

Jack S Fuhrer

Richard C Palmer

Frank B Lang

Thomas Y Chen

Victor Auerbach

A video disc record system having a stylus for recovering information effects kicks which induce limited stylus translations across a disc record surface. Control circuitry responsive to a desired stylus translation are coupled to kicker means for inducing the stylus translation. Actual stylus translations are used to calibrate the kicker activation signals to minimize the kick used to induce stylus translations thereby reducing damage to the disc surface incurred during a stylus translation.

Stylus kicker having kick energy minimization means

Luminance and chrominance components of a video input signal are stored at one rate and recovered at a lesser rate, 1/N, by means of a frame store to effect video signal bandwidth reduction. Burst is not stored but rather is regenerated and added to the video output signal to conserve memory space. To avoid undesirable hue changes and the necessity of rephasing the regenerated burst signal when switching between different video sources, the burst regenerator includes means for forming a product signal from two signals. One signal is locked to incoming burst, and the other signal is derived from a reference source having a phase related to that of burst. The latter signal is reduced in frequency by a factor (N-1)/N prior to forming the product signal and phase shift is added to a signal path such that the resultant difference component of the product signal exhibits a phase relative to that of the recovered chrominance component which equals the chroma-burst phasing of the video signal supplied to the frame store by any of the video sources. The difference component is then added as a burst component to the recovered chrominance component to form a composite output signal.

Color subcarrier regenerator for slow down processor

Under certain conditions a video disc player can be responsive to externally applied interference signals to provide a defect in the display of the information recovered from the disc. Apparatus is provided between the pickup circuits and the normal defect compensation apparatus of the player to reduce the influence of the modulated carrier in order to enhance the ability to detect the presence of the extraneous signal and take corrective action. The apparatus includes circuits to subtractively combine the signals from the pickup circuits with an amplitude limited version of the signals from the pickup circuits.

Video disc player with RFI reduction circuit including signal subtraction

Under certain conditions a video disc player can be responsive to externally applied interference signals to provide a defect in the display of the information recovered from the disc. Apparatus is provided between the pickup circuits and the normal defect compensation apparatus of the player to detect the presence of the external signals and to activate the normal defect compensation apparatus when the external signals are of a relatively high frequency and above a certain amplitude level.

Video disc player with RFI reduction circuit

Samples of the amplitude of a quadrature amplitude modulated (QAM) subcarrier signal are taken at times corresponding to each axis crossing of each of the two quadrature related signal components. The polarity of alternate ones of the samples is inverted and the signal is reconstructed from the inverted and non-inverted samples whereby the phase of one of the signal components is reversed without alteration of the phase of the other. Where the QAM signal is a television chrominance signal, means are provided for periodically inhibiting inversion of the samples on alternate lines whereby type chrominance signals may be converted to or from NTSC or NTSC 'like' chrominance signals.

Transcoder

In a video disc playback apparatus, an active tracking control system is provided using a single pilot signal. The pilot signal is recorded on an information track of a video disc record such that each convolution of the track contains a non-integral number of cycles of the pilot signal. The phase of the pilot signal in a given convolution bears a known relationship to the phase of the pilot signals in the convolutions preceding and succeeding the given convolution. The given convolution includes information representing a reference phase signal. The phase of the recovered reference signal is compared to the phase of the recovered pilot signal which may include phase information from adjacent convolutions to provide an error signal. Pickup positioning apparatus is made responsive to the error signal for maintaining the pickup on the desired path along the information track.

Recording/playback apparatus using a single pilot tone for active

Composite color video signals, of the PAL format, are applied to the input of a 1H delay line (exhibiting a 64 microsecond delay, when f.sub.H = 15,625 Hz.). Output of a first comb filter, using additive combination of delay line input and output signals, is applied to a lowpass filter having a cutoff frequency below the lowest color subcarrier sideband frequency. Output of a second comb filter, using subtractive combination of delay line input and output signals, is applied to: (1) a second 1H delay line; (2) a delay device, providing delay correpsonding to a quarter-cycle at the color subcarrier frequency; and (3) a low pass filter having a cutoff frequency below the lowest buried subcarrier sideband frequency. Outputs of two low pass filters are combined to form luminance signal. Outputs of quarter-cycle delay device and second 1H delay device are additively combined to obtain 'V' component of PAL signal, and subtractively combined to obtain 'U' component thereof. 'V' component is synchronously detected, de-switched, and remodulated on R-Y phase of buried subcarrier (e.g., with frequency at (189/2) f.sub.H + 1/2 f.sub.V), while ' U' component is synchronously detected, and remodulated on B-Y phase of buried subcarrier. Remodulator outputs are combined with luminance signal to form composite color video output signal.

Transcoding apparatus

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.

Defect detection and compensation apparatus for use in an FM signal

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.

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Skillman, NJ, United States of America

Jon K Clemens