US 4,358,796 AGranted

Spindle servo system for videodisc player

AssigneeDiscovision Associates

InventorsLudwig Ceshkovsky, Wayne R. Dakin

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Abstract

A video disc player is described for use with a video disc having frequency modulated video information recorded thereon in the form of a plurality of concentric circles or a single spiral. The information track comprises successively positioned light reflective and light non-reflective regions. A focused light beam is caused to be positioned over the center of an information track and the light reflected from the information track is gathered by an objective lens for application to electronic circuitry for recovering the recorded frequency modulated video signals. Radial tracking means are described for maintaining the focused light spot to impinge upon the center of an information track. Lens focusing means are described for positioning the objective lens at the optimum focused position above the information track for gathering the maximum amount of reflected light from the information track. FM processing means are described for reconstructing the recovered frequency modulated video information such that the ratio between the amplitude of the signals as recorded is essentially the same in the signals as recovered from the video disc member. Further servo means are described for handling the selective change of the intersection of the reading beam with the video disc member in a predetermined preferred mode of operation.

Claims7

Dependent claims

A spindle servo system for use in an apparatus for recovering an information signal from an information track arranged on an information bearing surface of a disc, wherein the information signal includes a signal defining a time base, and the apparatus includes optical system means for directing a source beam of radiation to the information track and for directing a modulated beam of radiation containing the information signal to signal recovery means for recovering the information signal from the modulated beam, the spindle servo system comprising:

spindle motor means for rotating the disc to impart relative motion between the disc and the source beam and thereby produce the modulated beam;
spindle tachometer means including first and second tachometer elements coupled to the spindle motor means, for producing first and second spindle tachometer signals indicative of the actual angular rate of rotation of the spindle motor means;
spindle reference signal means for producing a spindle reference signal representing a desired angular rate of rotation of the spindle motor means;
means for comparing each of the first and second spindle tachometer signals with the spindle reference signal, to produce first and second error signals representative of the detected differences therebetween;
and
means for summing together the first and second error signals to produce a spindle motor control signal for coupling to the spindle motor means, to produce the desired angular rate of rotation.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/130,901Filed 17 Mar 1980 · division
Priority: 27 Mar 1978
Granted: 9 Nov 1982
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H04N 5/93
Television signal processing therefor: regeneration of the television signal or of selected parts thereof
G11B 7/0037
Recording, reproducing or erasing systems characterised by the shape or form of the carrier: with discs
G11B 7/0941
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B 21/10
Driving or moving of heads: track finding or aligning by moving the head ; Provisions for maintaining alignment of the head relative to the track…