Rca Inc.

Richard C Palmer

Michael Allen Plotnick

Jon K Clemens

Michael E Miller

Jack E James

Gunter John

James C Rustman

Jerome Barth Halter

Richard M Castle

Michael J Mindel

John E Economou

Edward J Freeman

John G Pecorari

A method is provided for determining the magnitude of flatness deviation in high density information discs, such as video discs, manifesting irregularities in playback. Such flatness deviations are known as 'orange-peel.' A stylus riding over a relatively large area (4-5 grooves) of the disc surface provides a vertical velocity signal within a given spatial or temporal frequency band. The signal in velocity or displacement form is the quantitative measure of deviation. The method is useful for other type discs where quantitative measurements in flatness deviation are desired.

Method for determining variations from flatness in the topography of a

An analog-to-digital converter/demodulator consists of n delay elements, each of which has a delay period longer than a preceding delay element by a fixed amount, and n pulse coincidence detectors. A ONE-SHOT responsive to the FM signal generates a pulse for each zero crossing of the FM signal, which pulses are applied to one input of each detector and to the input terminals of the n delay elements. The output terminals of the delay elements are coupled to respective second input terminals of the coincidence detectors. The output terminals of the coincidence detectors are applied to a DECODER which provides a binary output signal corresponding to the instantaneous frequency defined by the period between successive pulses i.e., between successive zero crossings.

Analog-to-digital converter/demodulator for FM signals

Video disc track numbers are conveyed during each video line by means of data subcarriers present in the recorded stereo audio channels. Upon playback, the data sequence is processed to identify tracking errors occurring within each video field to thereby enable immediate correction of disc tracking errors on a line-by-line basis thus minimizing picture and sound interruption caused by intra-field tracking errors.

Video disc encoding and decoding system providing intra-field track

A video disc record of the constant angular velocity type (CAV) includes a spiral groove of constant pitch formed in a band on a surface thereof. The groove has a substantially constant nominal vertical dimension and vertical displacements which taper monotonically from an outer radius of the band to an inner radius. One component of the vertical displacement of the groove conveys an FM carrier wave of constant amplitude and relatively high frequency representative of picture information. A second component of the vertical displacement conveys one or more lower frequency FM carrier waves representative of sound information. The amplitude of the second component varies monotonically as a function of the groove radius within the record band to provide a disc having an improved audio FM carrier-to-noise ratio with no substantial perceptible increase in undesirable sound beat effects in images displayed when the disc is played. A mastering system exemplary of the method of forming the grooved disc includes variable gain units in an audio FM carrier wave processing path of the system.

Disc record with tapered groove

In a video disc player intermodulation distortion can occur during signal recovery and is manifested as the modulated sound carrier appearing in the baseband video. To reduce such distortion, a portion of the signal recovered from the disc record is filtered to extract the modulated sound carrier. This signal is applied to a phase shifting circuit having a predetermined frequency response to condition the modulated sound carrier to have a phase characteristic substantially similar to the phase response of the modulated sound carrier appearing as distortion in the baseband video. The phase conditioned sound carrier is then amplitude adjusted and linearly subtracted from the baseband video signal.

Video disc player noise reduction circuit

The quality of the low frequency signals recovered by a playback stylus may be improved by removing non-electrode metal deposits. A stream slurry lapper with a slurry of alumina in water can be used.

Method for improving the quality of low frequency output of a video disc

A recording signal containing a main carrier modulated in accordance with picture signal information inclusive of synchronizing components, and an auxiliary carrier modulated in accordance with sound signal information and a pilot signal, is impressed on a video disc record along a spiral track on the surface thereof. The frequencies of the synchronizing components and the pilot signal are such that an integral number of synchronizing components and a non-integral number of pilot signal cycles occupy each convolution of the spiral track. The playback apparatus includes circuitry coupled to the output of a player stylus for recovering the pilot signal, and further includes circuitry responsive to the deviations in the phase of the recovered pilot signal for developing an error signal indicative of the magnitude and sense of a disruption in the regular progression of the stylus along the spiral track due to a sudden shift in the radial location of the stylus. A suitable track skipper mechanism is activated in response to the error signal to radially shift the stylus in a manner that offsets the disruption in the regular progression thereof.

Recording/playback apparatus facilitating track skip detection

A signal pickup stylus which cooperates with an information storing spiral track on a video disc record is caused to selectively skip track convolutions of the disc record. To cause selective track skipping, the playback system includes an apparatus, responsive to an actuating signal, for twisting a stylus-carrying arm about its longitudinal axis, and the offset of the stylus tip from the rotational axis results in consequent radial motion of the stylus tip across track convolutions on the record. According to a further aspect of the invention, the lateral motion of the stylus-carrying end of the stylus arm is substantially restrained while the stylus arm is rotated to assure that the twisting of the stylus arm results in rotation of the stylus about the stylus arm axis, rather than rotation of the stylus arm about the stylus tip.

Track skipper for a video disc player

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.

Color-picture/multichannel-sound record and recording/playback apparatus

Frequency modulated sound carrier waves and frequency modulated picture carrier waves are combined in an adder, and the sum is clipped to develop a recording signal input for an electron beam disc recorder. To reduce possible sound carrier interference in pictures reproduced from signals recovered during disc playback, sound carrier waves, in quadrature phase relation to those applied to the adder, are combined with composite video signals to form the modulating signal input to the picture carrier frequency modulator.

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Blawenburg, NJ, United States of America

Richard C Palmer