Abstract: Apparatus for sharpening a diamond cutting stylus for use in recording video signal information in a metal master includes a source of high energy particles such as an ion milling machine. The high energy source provides a beam of high energy particles having a cross-sectional area perpendicular to the longitudinal axis of the beam that is large compared to a given area on a mounting face of the stylus which is to be bombarded by the beam during the sharpening operation. Further, the apparatus includes a masking block for masking a first portion of the cutting stylus. The masking block is positioned with respect to the high energy source to intercept the particles in the beam directed at the first portion of the cutting stylus. A second portion of the cutting stylus which includes the given area is exposed to the high energy particles such that the second portion of the cutting stylus is removed.

Abstract: A defect detection apparatus is disclosed for optically inspecting a spiral groove of a video disc record by directing a coherent light beam at the grooved surface of the disc. The incident beam illuminates the grooved surface with a light spot that spans a plurality of groove convolutions. The structure of the illuminated region on the grooved surface serves as a diffraction grating for diffracting the incident beam into discrete diffraction orders. Relative motion is established between the disc surface and the incident beam in a manner causing the illuminating spot to rapidly scan the grooved surface in a coarse spiral pattern. A lens system is positioned to collect the light from a single beam of a particular group of non-zero diffraction order beams and to focus this non-zero order beam onto a photodetector. When a defect in the groove pattern exists in the illuminated region the measured power of the non-zero order beam will fall below its normal level.

Abstract: A cutterhead assembly suitable for forming a topographic signal representative pattern in a recording media, such as a disc substrate, is constructed having a base member, a piezoelectric element and a cutting stylus. The piezoelectric element in this structure is asymmetrically assembled to the base member to reduce phase modulation of the recorded signal which would otherwise occur from the transverse motion of the stylus during the cutting operation.

Abstract: Soldering techniques, where a circuit component having a row of closely spaced leads (e.g., dual in-line packages) are to be soldered to a printed circuit board and the leads are oriented on the printed circuit board such that the row of leads is arranged parallel to the direction of motion of the printed circuit board through a wave solder pot, may effect a high incidence of soldering bridging. This bridging may form between the last few adjacent leads in the row which emerges from the solder pot. A printed circuit board is provided with an additional foil pad (or a pair of additional pads in the case of a dual in-line package) arranged in line with the row of leads. This additional foil pad tends to draw off any excess solder to reduce the solder bridging between adjacent leads during the soldering operation.

Abstract: Piezoelectric video disc recording cutterheads have small and intricate geometries that make it difficult to compute or measure their mechanical characteristics, especially during the recording process. A monitoring circuit, for use during recording, for monitoring and measuring the mechanical characteristics of a recording cutterhead takes the form of a bridge network. The motional charge or motional current, which are related to the mechanical characteristics of the cutterhead, is measured by means of the bridge network. One branch of the bridge is arranged to include the piezoelectric cutterhead, the other branch comprises a variable capacitor which is adjusted to compensate for the shunt capacitance of the equivalent electrical circuit of the cutterhead. When the variable capacitance is properly adjusted the combination of the currents through the bridge network provides a signal representative of the displacement characteristics of the cutterhead.

Abstract: A video disc record suitable for use with a video disc player apparatus is provided with a label for identifying the program material stored on the surface of the record. The label is formed in a machine readable format which comprises grooves in the surface of the record. In one format, whorls of a spiral groove on the surface of the record are spaced alternately with ungrooved areas on the surface. A readout apparatus comprises a light beam which is arranged to scan the grooved label and a detecetor which is arranged to sense the light beam reflected from the disc record surface. Light striking an ungrooved section is reflected in a substantially specular direction while light striking a grooved section is substantially scattered out of the specular direction. The detector is arranged to collect the light reflected into the specular direction.

Abstract: A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser, which dielectric material is coated with a thin layer of a material absorptive for light of the frequency supplied by the recording laser (e.g., titanium). The coating parameters are chosen to establish an anti-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated. With the peak intensity of the focused light sufficient to at least cause melting of the absorptive layer, an information track is formed as a succession of spaced pits in which the reflective layer is effectively exposed through the layer of dielectric material.

Abstract: In a method for determining the machinability of a metal substrate for use in an electromechanical recording apparatus a surface of a foundation is coated with a layer of metal. The metal layer is machined such that the metalized surface of the foundation is substantially flat and smooth. After the machining step, the metal surface is inspected for depressions with a microscope using a differential interference contrast technique. The number of depressions observed is indicative of the machinability of the coated foundation.

Abstract: A diamond stylus for electromechanically recording short wavelength video signal information in a metal disc master is supported in a cutterhead suspension apparatus. A set of parallel spring steel suspension members are used to mount a cutting stylus assembly including the diamond stylus to an electromechanical recording lathe. A cutterhead suspension velocity control apparatus couples the cutterhead suspension apparatus to the main frame of the electromechanical recording lathe. When the cutterhead suspension is lowered onto the disc master surface the velocity control apparatus controls the rate at which the cutterhead suspension descends to the disc master surface.

Abstract: A method of producing an information storage disc by optical techniques includes the steps of coating a flat, reflective disc surface with a thin coating of radiant energy sensitive material, moving the coated disc relative to a coherent light beam, which is intensity modulated with the information to be recorded, to expose the radiant energy sensitive material, and developing the radiant energy sensitive material to form a track having geometric variations in the disc representative of the modulated information signals.

Abstract: In a video disc playback system non-linear intermodulation distortions are effected during playback by the pick-up stylus. These distortions cause disturbing visual beats in the reproduced images. A first signal path at the output of the pick-up circuitry transfers the main video signal with negligible phase shift over a given band of frequencies. A second signal path which parallels the first path effects a modulation of the video signals by the interferring signals (i.e., sound signals). The signals from the first and second paths are combined to effect a substantial removal of the interfering intermodulation products.

Abstract: In a video disc system, geometric variations are recorded on the surface of the record and are representative of recorded picture and sound information. In a video disc playback apparatus for recovering picture and sound information from such a prerecorded record, a playback stylus is utilized to detect the geometric variations. Sound interference in the video signals may be produced by the non-linear characteristics of the playback stylus. A non-linear aperture correction circuit interposed between the playback stylus and the demodulator circuitry of the playback apparatus effects a substantial control of the intermodulation products.

Abstract: A cutting stylus assembly for electromechanically recording short wavelength video signal information in a metal master is supported in a cutterhead suspension apparatus. In the suspension head apparatus the cutting stylus assembly is supported by an air puck device so that the stylus cuts an information track having a given quiescent depth. Two sets of parallel spring steel suspension members are used to mount the cutting stylus assembly and air puck to an electromechanical recording lathe. These suspension members are used to control the cutting stylus assembly and air puck motion, to maintain a fixed stylus assembly to air puck plane relationship and to effect a variable preload for the cutting stylus system.

Abstract: Recovery from a record of data recorded in an elongated information track, comprising depressed areas of various lengths alternating with non-depressed areas, is effected by an optical playback system. The playback system employs apparatus for focusing a laser source as a light spot on the information track. A light detector, responsive to light diffracted by the information track as relative motion is established between the light spot and the information track, is used in the playback apparatus to translate the depressions in the information track into frequency-modulated electrical signals. When the light spot size or depression spacing becomes comparable to the wavelength of the laser source, the signal strength at the detector output becomes dependent upon the polarization of the light spot incident on the information track. In the playback system, apparatus is provided for orienting the polarization of the light spot on the information track to enhance the signal strength of the detector output.

Abstract: In a capacitance distance sensor apparatus in a focus servo loop for an optical disc playback and record system, stable high servo loop gain and small closed-loop error correction signals are achieved despite surface variations of the disc by compensating for the periodic error command signals generated by the surface variations.A comb filter is provided in the loop tuned to major error component frequencies. The comb filter is formed of a plurality of parallel, bandpass filters that are tuned to frequencies substantially corresponding to the disc rotation frequency and several harmonics thereof. In the distance sensor servo focus control loop, the loop gain can be maintained at a high value to achieve proper beam focus within 0.5 micron (0.5.times.10.sup.-6 meters) for disc surface amplitude variation of three mils (0.0075 centimeters) peak-to-peak.

Abstract: A monitoring circuit for monitoring and measuring the mechanical characteristics of a piezoelectric video disc recording cutterhead takes the form of a bridge network. The motional charge or motional current, which are related to the mechanical characteristics of the cutterhead, is measured by providing signals of a first polarity to one leg of the bridge and signals of a polarity opposite to the first to another leg of the bridge.One leg of the bridge includes the cutterhead and a sensing capacitor connected in series while the other leg includes the sensing capacitor and a balancing capacitor connected in series. When the capacitance value of the balancing capacitor is properly chosen, the voltage drop across the sensing capacitor is proportional to certain mechanical characteristics of the cutterhead (e.g., displacement).

Abstract: A high speed data storage and retrieval system includes a storage module, a reader and a changer apparatus. Disc records enclosed in protective cartridges are transported between the reader and the storage module by the changer apparatus. The reader includes two mechanical systems--a system for receiving, securing and spinning a disc while it is enclosed in the cartridge and a pair of read heads which retrieve data stored on the surface of the disc. The storage module includes a plurality of storage locations for storing the discs. The changer apparatus comprises a carriage with a drive mechanism for driving the carriage to a desired position along the length of the storage module and at least two carriers for transporting discs with independent drive mechanisms. The carrier drive mechanisms drive the carriers in a direction normal to the direction which the carriage is driven. Simultaneous movement of the carriage and carriers permits high speed access of data.

Abstract: A surface acoustic wave (SAW) pickup and record stylus is constructed from an elongated substrate which supports the propagation of SAW. The substrate is tapered to a tip at one end and a fan-shaped interdigital electrode structure having curved fingers is formed thereon. During operation in the pickup mode a beam of SAW is focused to the tip of the stylus which is arranged in contact with a record medium. During playback, the beam reflected by the record medium generates a signal in the interdigital electrode of the stylus representative of the acoustic conditions at the stylus tip and, correspondingly, of the information recorded on the record medium surface. In the record mode the stylus is brought into contact with a record medium. During recording, the input power applied to the interdigital electrode is increased to effect a deformation of the surface of the record medium representative of the information to be recorded.

Abstract: A high speed data storage and retrieval system includes a storage module, a reader and a changer apparatus. A protective cartridge is provided for storing, protecting and transporting an optical disc enclosed therein. The storage module includes pins for insertion into corresponding holes in one surface of the cartridge during storage. During transport the changer apparatus having electromagnetic means grips the cartridge by spring clips attached to the cartridge. A window cut in the side of the protective cartridge effects readability of the disc enclosed therein without removing the disc from the cartridge during the reading operation. The cartridge also includes a set of holes in another surface of the cartridge for receiving a corresponding set of pins when the enclosed optical disc is placed in the read position.

Abstract: In a video disc playback apparatus, a playback stylus is utilized for the recovery of information from prerecorded disc records. In one system, geometric variations are recorded on the surface of the record and are representative of recorded picture and sound information. As these geometric variations pass beneath the stylus, the capacitance between the stylus electrode and the surface of the disc varies in accordance with the recorded representations. The capacitive variations are converted to electrical signal variations in the playback apparatus. In such a video disc playback apparatus, sound interference in the video and video interference in the sound can be produced by the non-linearity of the aforementioned pickup stylus. Use of a non-linear aperture corrector between the pickup circuitry and the demodulator circuitry of the playback apparatus reduces these interferences.