Abstract: A method and apparatus for selectably retrieving information from any of a plurality of spirally-formed information tracks formed in a video disc by means of controlling a carriage for translating the video disc in a forward or a reverse direction relative to radiant beam information recovery means in a video disc player. Each information track is identified by a unique address and means are provided for selecting the address of a particular track to be retrieved. A prescribed sequence of drive signals is applied to a carriage motor dependent on the distance to be traveled by the carriage to retrieve the selected information, the drive signals being successively stepped downward to intermittently redetermine carriage motor speed as predetermined location thresholds are reached during carriage translation.

Abstract: Method and apparatus for measuring the spacing between adjacent information tracks on a recording medium. A spot of light is projected onto at least a portion of a first track and maintained in a constant spacing from a second track. A photodetector detects the amount of light reflected off of the disc from the spot in a predetermined direction, and provides an electrical signal as an output. The photodetector output provides a measurement of the track-to-track spacing of the recording medium.

Abstract: An improved stamper and method involved in the replication of optically-readable information bearing members by means of an injection molding process utilizing a stamper having a conformal layer of chromium electrolytically deposited over the encoded surface of an existing optically-readable information bearing nickel stamper. Nickel stampers produce replicas having structural and optical defects affecting playability of the replica. The present invention provides improvement in the reduction or elimination of "plowing" and "orange peel" defects through cleaner release at the interface of the master stamper and the stamped article. The invention involves an improved stamper surface comprised of a thin layer of chromium metal deposited over an existing nickel stamper. Such a surface insures a cleaner release at the interface of the master stamper and stamped article.

Abstract: A transparent record disc is provided which may appropriately have video signals optically recorded thereon, the record is composed of a lamination, for example, of pliant transparent plastic on a base of hard transparent plastic. The base provides strength for the record and the pliant plastic permits the video recording to be impressed into the record by simple embossing means, rather than by stamping or molding by which the surface of the record is actually raised above its melting point and caused to flow. An improved process for forming the video recordings on the disc record is also provided.

Abstract: A method and apparatus for monitoring the focus condition of a writing light beam impinging the writing surface of a recording medium. The present invention operates on the recognition of the fact that light from a laser is very slightly divergent as it emerges from the laser. Accordingly, the reflected light from the medium is convergent as it passes in the reverse direction and it forms a real image of the source plane wave. The image is compared to a reference image indicative of proper focus, and the focus is adjusted until the image matches the reference image.

Abstract: A method and apparatus for developing a compressed bandwidth frequency modulation signal format to increase the playing time per side of a videodisc by compressing the signal bandwidth of the recorded information preferably by a factor of two. Method and apparatus are described and shown for modulating a carrier signal with a color video signal, modulating a subcarrier frequency with at least one audio frequency signal, selecting the carrier and subcarrier frequencies such that the upper frequency deviation limit of the frequency modulated carrier signal is lower than the useful upper frequency limit of the recording medium chosen for the disc, and such that there is no overlap of the chroma baseband signal and the second order chroma sideband. At least one audio subcarrier frequency is located between the first order chroma sideband and the chroma baseband signal, or between the chroma baseband signal and the second order chroma sideband, or between the second order chroma sideband and DC.

Abstract: A method and apparatus for encoding a plurality of bytes of digital data into a further plurality of bits suitable for storage in a storage medium, and for recovery therefrom, and for decoding the stored bits retrieved from the storage medium, for the recovery of the encoded bytes. The digital data bytes are arranged into a plurality of code blocks, each having a first predetermined number of columns and a second predetermined number of rows of bytes. A parity block of bytes of data is generated having a number of columns and a number of rows of bytes corresponding to the first predetermined number of columns and to the second predetermined number of rows of bytes, respectively, of the code blocks, the bits of data in the parity block corresponding to the computed parity of the combined corresponding bits in each of the code blocks.

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.

Abstract: A video recorder-playback machine is provided for recording and/or playing back video information from an information disc. The machine includes a "write" laser and a "read" laser respectively for generating record and playback optical beams which are focused upon the disc by an optical record-playback head. An optics carriage movably positions the head with respect to the disc in moving optical alignment with the "write" laser and carries the "read" laser in fixed optical alignment with the head. The machine includes apparatus for monitoring the record optical beam during operation in a record mode, and for substantially simultaneous operation in a playback mode to monitor the playback optical beam during the recording process.

Abstract: A method for recording video and audio information onto a recording medium which involves recording a carrier frequency signal, frequency modulated with composite color video information, and a subcarrier frequency signal, modulated with audio frequency information onto the recording medium and selecting the frequencies of the carrier and subcarrier signals such that the subcarrier frequency is lower than the second lower chroma sideband of the modulated carrier signal.

Abstract: Apparatus for verifying the accuracy of insertion of code signals in the vertical intervals of video signals. The code signals are inserted in accordance with a procedure characteristic of a specified encoding format. The accuracy of insertion is verified by testing the codes against a predetermined set of conditions related to the procedure. Failure to meet one of the conditions results in the generation of an error signal.

Abstract: Apparatus for generating a map of detectable characteristics of a disc. A scanning signal display device has a detector coupled to the intensity input thereof. The detector detects the characteristics at a location on the disc which is scanned in a spiral pattern and provides a signal representative of the detected characteristics to the display device. A signal is generated and provided to the drive inputs of the display device to cause the trace of the device to follow a spiral pattern corresponding to the scan pattern of the predetermined location.

Abstract: A video recorder-playback machine is provided for recording and/or playing back video information from an information disc. The machine includes a "write" laser and a "read" laser respectively for generating record and playback optical beams which are focused upon the disc by an optical record-playback head. An optics carriage movably positions the head with respect to the disc in moving optical alignment with the "write" laser and carries the "read" laser in fixed optical alignment with the head. The machine includes apparatus for monitoring the record optical beam during operation in a record mode, and for substantially simultaneous operation in a playback mode to monitor the playback optical beam during the recording process.

Abstract: A hot sprue valve assembly is provided for controlling flow of molten material through a hot sprue bushing of an injection molding machine. The valve assembly is particularly designed for use with an injection molding machine for molding centrally apertured record discs, such as video information discs, and the valve assembly includes means for forming the central aperture in the disc. In one embodiment, the aperture-forming means comprises a sleeve valve for molding the aperture in the disc prior to solidification of the disc-forming melt, whereas in another embodiment the aperture-forming means comprises a punch for punching the aperture subsequent to solidification of the disc-forming melt.

Abstract: A drop-out detector for detecting the absence of a pulse in either of first and second pulse trains, especially for use with the spindle servo error generator of a videodisc mastering machine. Prior attempts at providing a drop-out detector function for the spindle servo error generator rely on the use of RC based timing circuits to create time windows within which to look for the presence or absence of a reference or tach pulse, as the case may be. Such arrangements provide satisfactory performance in connection with constant angular velocity type discs, since reference and tach frequencies remain constant throughout the mastering process. However, problems arise in utilizing such RC based circuits in connection with constant linear velocity type discs. The present invention overcomes these problems by operating on a pulse width modulation technique for controlling the spindle motor speed.

Abstract: An improved method and apparatus for recording and playing back a video signal on a video disc, such that selected video frames can be played back in a stop-motion fashion, with accompanying audio. Each stop-motion video frame is recorded on a single recording track on the disc, and an associated digitized stop-motion audio signal is combined with a continuous-play video signal and recorded on a plurality of preceding tracks. During playback, the tracks recording the continuous-play video signal are first scanned, to recover and display the continuous-play video frames, and to recover and enter into a memory the digitized stop-motion audio signal. The track recording the corresponding stop-motion video signal is then scanned, in a repeated fashion, to provide a stop-motion display of the video frame, while the stop-motion audio signal is extracted from the memory and converted back to its original analog format, for playback along with the stop-motion video frame.

Abstract: Apparatus and process for writing information using a laser light writing beam focused on a light sensitive layer having a threshold power level above which the layer reacts to the laser write beam. The intensity of the writing beam is adjusted relative to the threshold power level. In one embodiment, the peak intensity of the writing beam is adjusted so that one-half of the peak intensity is equal to the threshold power level. In a second embodiment, the average intensity of the writing beam is adjusted to equal the threshold power level.

Abstract: A method for measuring the size of dimple-type defects in an area of the surface of a flat piece of transparent material, such as an optical disc. A large beam of collimated light is provided and passed through the piece of material in a normal orientation with respect to the surface being inspected. A screen is placed in the path of the beam emerging from the disc and circular shadows generated by refraction are measured to determine the size of the defects which produces them.

Abstract: Method and means for evaluating the quality of audio and/or video transfer characteristics of a device upon which, or through which, audio and/or video information is contained, or passes, respectively. Both method and apparatus concern the evaluation of the quality of information transfer in the recording and playing back of a recording medium or in the transferring of audio and/or video information through an information handling device referred to as a throughput device. Unit evaluation is accomplished by establishing an input signal of known content, measuring selected parameters of selected parts of the input signal, feeding the input signal to the unit under test, measuring the parameters of parts of the output signal from the unit under test corresponding to the same selected parts of the input signal, and comparing the selected parameters of the input signal with the corresponding parameters of the output signal.

Abstract: A video signal play back device derives video signals from successive tracks formed as a continuous spiral on a video disc using a light source and a lens system, which is carried by a rotatable element at a predetermined spacing from the surface of the disc and which defines a folded optical path. The rotatable element translates the lens system in the radial direction relative to the disc for "coarse" steering of the light beam along the information tracks as the disc is rotated by a turntable. The optical path includes a mirror which is articulated for rotational motion about an axis which shifts the point of impingement of the transmitted light beam upon the disc in the radial direction. The returned beam is directed to a photosensitive pick-up which provides input signals to a circuit which generates a "fine" servo control signal to drive the articulated mirror.