Abstract: An optical beamsplitter comprises a right angle prism having a hypotenuse and two legs wherein the hypotenuse includes an optically selective coating deposited thereon. An optical element is positioned adjacent the hypotenuse such that the hypotenuse and the optical element form a beamsplitting interface. Various optical elements are utilized to achieve the desired spatial and angular relationships between incoming and outgoing light beams. Several embodiments are disclosed wherein the optical element can comprise a flat plate for providing spatial offset, a wedged plate for producing spatial and angular offset, a lens for adding optical power, or a faceted thin plate.

Abstract: An optical tape duplicator is disclosed for making multiple copies of recorded optical tape by continuous contact recording. An information-bearing master tape held in intimate contact with an optical tape are passed through a recording zone exposed to a beam of radiant energy for recording information stored by the master tape to the optical tape. The master tape contains transmissive and non-transmissive portions that represent the information stored by the master tape. The optical tape is sensitive to the beam of radiant energy. The beam of radiant energy passes through the transmissive portions of the master tape while making contact with the optical tape in the recording zone, causing information stored by the master tape to be recorded by the optical tape as indicia where the optical tape was exposed to the beam of radiant energy.

Abstract: A first write encoder encodes digital data in a first, high-density format. A second write encoder encodes digital data in a second, low-density (i.e., ANSI) format. A first read decoder decodes digital data from the first format. A second read decoder decodes digital data from the second format. A disk drive receives a replaceable 90 millimeter optical disk. A read/write head reads encoded data from and writes encoded data to a 90 millimeter optical disk received by the drive. In a first mode, the first write encoder is connected between a source of digital data and the read/write head, and the first read decoder is connected between the read/write head and the utilizing apparatus. In a second mode, the second write encoder is connected between the source and the read/write head, and the second read decoder is connected between the read/write head and the utilizing apparatus.

Abstract: An apparatus for optically reading or recording information on an optical disc which is rotatable about an axis of rotation. The apparatus includes a frame, a carriage, a carriage drive, an objective lens, an objective lens holder, a focus drive and a fine tracking drive. The objective lens is mounted on the objective lens holder so that the optical axis of the objective lens substantially intersects the center of mass of the carriage. The fine motor, used for tracking and focus, has a center of mass that substantially lies on the optical axis and proximate the center of mass of the carriage.

Abstract: A pick-up device for optical recording and playback includes two linear actuators coupled to an optical module and lying in a plane normal to the surface of an optical recording medium. The actuators are obliquely inclined to the optical axis of the optical module. Proportional differential actuation of the linear actuators moves the optical module bi-axially, i.e., normal or parallel to the recording medium surface, permitting control of both focus and tracking of information bits on the surface. The preferred embodiment employs two bi-directional linear actuators, each comprising a pair of back-to-back uni-directional actuators, each of which includes a flexible tubular housing enclosing a stack of thin, perforated disc-shaped electrodes separated by a dielectric fluid. Conductive elastomeric spacer rods support the disks in a parallel, longitudinally, spaced apart arrangement.

Abstract: The invention discloses a method and an apparatus for implementing an L phase clock in conjuction with L counters, where L is an integer, to count at a frequency scalable by L.

Abstract: A pick-up device for optical recording and playback includes two linear actuators coupled to an optical module and lying in a plane normal to the surface of an optical recording medium. The actuators are obliquely inclined to the optical axis of the optical module. Proportional differential actuation of the linear actuators moves the optical module bi-axially, i.e., normal or parallel to the recording medium surface, permitting control of both focus and tracking of information bits on the surface. The preferred embodiment employs two bi-directional linear actuators, each comprising a pair of back-to-back uni-directional actuators, each of which includes a flexible tubular housing enclosing a stack of thin, perforated disc-shaped electrodes separated by a dielectric fluid. Conductive elastomeric spacer rods support the disks in a parallel, longitudinally, spaced apart arrangement.

Abstract: An IDCT, or Inverse Discrete Cosine Transform, method decimates a 2-D IDCT into two 1-D IDCT operations and then operates separately on the even and odd pixel input words. In a common processing step, selected input values are passed directly to output adders and subtractors, while others are multiplied by constant, scaled cosine values. In a pre-common processing step, the lowest-order odd input word is pre-multiplied by .sqroot.2, and the odd input words are summed pairwise before processing in a common processing step. In a post-common processing step, intermediate values corresponding to the processed odd input words are multiplied by predetermined coefficients to form odd resultant values. After calculation of the even and odd resultant values, the high-order and low-order outputs are formed by simple subtraction/addition, respectively, of the odd resultant values from/with the even resultant values. The input values are preferably scaled upward by a factor of .sqroot.2.

Abstract: A programmable logic output driver includes a bias generator (100), a current mirror (200) and an output stage (300), there being a digital programming feature to maintain the output voltage slew rate at an acceptable value for either high or low values of load capacitances. The driver is programmable and can maintain a constant value of driver output resistance in the circumstances where the load voltage approaches the full swing logic voltage. In the preferred embodiment, the programmed output resistance is independent of variations in process, temperature and VDD supply voltage. TTL loads are driven with the minimum amount of required output current. Because of the constant resistance, the driver supplies a specified amount of current to the load even when the load is pulled down to a specified voltage.

Abstract: A record disc for storing a composite signal that includes segments of audio information and corresponding segments of video information. The disc contains a succession of consecutively arranged substantially circular and concentrical information tracks including audio information-containing tracks and separate video information-containing tracks. Each of the audio information-containing tracks has at least a portion of an audio information segment stored therein in time-compressed digital data format, and each of the audio information segments includes packets of digital data interleaved with conventional video synchronizing signals, with adjacent audio information packets representing a continuous portion of the stored audio information segment. Each of the video information-containing tracks has a video information segment stored therein in real time, and each video information segment contains a single video frame in conventional video format including conventional video synchonizing signals.

Abstract: An improved system for recording and playing back digital information in a special pulse-length modulation format on a disc-shaped record. The digital information is stored in a succession of alternating marks and spaces, both having lengths that are discretely variable in accordance with a succession of multi-bit binary code blocks.

Abstract: A method and apparatus for recording a data signal on a light-reflective record disc, wherein an intensity-modulated write beam of light is focused onto the disc as the disc is rotated in a prescribed fashion, to produce a sequence of spaced non-reflective regions representative of the data signal. Additionally, a relatively low intensity pre-write beam of light scans the disc in advance of, but synchronous with, the write beam to detect the presence of nonreflective defects in the disc that could inhibit the recording of the data signal thereon. Whenever such a defect is detected, a special defect flag code is recorded in advance of and over the defective region, whereby when the data signal is recovered from the disc at a subsequent time, it can be recognized that the data signal is being temporarily interrupted.

Abstract: Method and apparatus 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: 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: Method and apparatus for playing back a plurality of digitally encoded audio messages along with associated video data. The audio messages are combined along with a plurality of corresponding audio message start address signals when recorded on a recording medium. The digitally encoded information can be recorded in the audio domain, i.e. as digitally audio recorded on an audio channel of the medium, or in the video domain, i.e. as digitized audio recorded on the video channel of the medium. In playback, the address and audio data signals are retrieved from the recording medium and stored. The address signals are utilized to access selectable messages for decoding and playback of the selected audio message.

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 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: Apparatus and method for monitoring the optical recording of information on an information storage member using a first beam of light for writing the information and a second beam of light for reading the information. Both the writing beam and the reading beam are focused on the storage member by a single objective lens. The input information signal which is used for modulating the writing beam is also directed to a delaying circuit, and the delayed information signal is compared with the playback signal derived from the reading beam.

Abstract: Method and apparatus for evaluating the audio characteristics of an audio-video program recorded on a storage member in which the video portion of the program contains picture frame code numbers. A predetermined picture frame number at which video evaluation of the audio portion of the program is to commence is initially established. The audio and video portions of the recorded audio-video program are recovered, and the picture frame code numbers are extracted from the video portion thereof. The extracted picture frame numbers from the recovered video portion are then compared with the predetermined picture frame number, and audio evaluation of the audio portion of the program commences upon coincidence of the detected picture frame number and the predetermined picture number. Evaluation is effected by measuring predetermined audio characteristics of the recovered audio portion and comparing the measured characteristics with corresponding audio reference characteristics.

Abstract: Method and apparatus for recovering information at a substantially constant rate from a rotatable information storage disc. The information is stored on the disc in a plurality of substantially circular and concentrically arranged information tracks, with a substantially uniform recording density, and it is recovered by controllably rotating the disc, relative to a transducer, at an angular velocity substantially inversely proportional to the radius of the corresponding track. The apparatus includes a coarse speed control potentiometer for producing a measure of the radius of the particular information track from which information is being recovered, and fine speed control means for comparing the relative phase angles of a periodic signal in the recovered information and a periodic reference signal and for producing a fine speed control signal proportional to the phase difference.