Abstract: A rotary recording medium has at least one surface on which a spiral main track is formed with a reference signal track disposed centrally between mutually adjacent track turns. The track turns of the main track have an information signal recorded thereon. First and second reference signals are recorded alternately on the reference signal track, and a third reference signal is recorded at changeover positions on the recording medium. The three reference signals control a pickup guiding servo system. To identify specific places on the recorded disc, the third reference signal is recorded during extra long periods, with identification being made on a basis of the lengths of those long periods.

Abstract: An information signal recording medium of rotary type has a flat surface with first succession of pits formed therein as respective concavities in response to a first signal and with second succession of pits formed therein as respective concavities in response to a second signal. The second succession of pits are formed at positions substantially intermediate between the centerlines of adjacent tracks formed by the first succession of pits. Each pit of the first succession of pits and each pit of the second succession of pits respectively have widths W1 and W2 and depths D1 and D2, wherein the relationships between the widths and said depths are so selected that the levels L1 and L2 of the first and second signals which are reproduced when the first and second succession of pits are traced and thereby reproduced by reproducing means will be such that the level L1 is greater than the level L2, and the difference between the levels L1 and L2 will be greater than a specific level difference.

Abstract: Nickel stampers used for the molding of capacitive electronic discs are treated prior to use in the molding process by heating the stamper in the presence of an oxygen containing gas, at a temperature from about 220.degree. C. to about 300.degree. C. for 2 to 5 hours until a continuous protective oxide layer approximately 10-40 angstroms thick is formed on the surface of the stamper.

Abstract: Disclosed herein is an optical information recording disk comprising as a base material thereof a polymer or copolymer having a glass transition temperature of at least 50.degree. C. and a structural unit derived from a monomer which is an ester of an .alpha.,.beta.-unsaturated carboxylic acid and an alicyclic alcohol represented by the general formula: ##STR1## wherein n is an integer of 1-5, R denotes a hydrogen or an alkyl or alkenyl group, and, when n stands for an integer of 2-5, the Rs may be the same or different.The above disk does not develop deformation such as warping or twisting by changes in humidity and is uniform optically.

Abstract: An information signal recording system records an information signal, a first and a second reference signals for tracking control, and a third reference signal for switching the first and second reference signals at the time of reproduction on a recording disc. The first and second reference signals of different frequencies are alternately recorded on intermediate parts of the recording disc, at positions between centerlines of adjacent information signal tracks. The third reference signal of a still different frequency is recorded at a predetermined position on every information signal track. A reproducing system reproduces the information signal together with the third reference, and the first and second reference signals by a single reproducing element. A tracking control signal is produced from the first and second reference signals switched by the third reference signal separated from the reproduced information signal.

Abstract: High density information discs comprising a conductive carbon-loaded polyvinylchloride disc are lubricated with a polyphenylene ether containing a polar dopant substituted with a long chain alkyl group in amounts sufficient to reduce surface tension of the polyphenylene ether to enable adequate wetting of the disc surface. The successful application of this doped lubricant provides the discs with excellent lubrication, highly resistant to oxidation, moisture and shear stress.

Abstract: An improved molding composition having a high thermal stability, including a vinyl chloride/vinyl acetate copolymer-based resin, sufficient finely divided conductive particles to obtain the desired conductivity, and from 3 to 20 weight percent of the modifying additive BLENDEX 586, which is a three-component blend of polyvinyl chloride, a graft copolymer of acrylonitrile, styrene and polybutadiene, and a copolymer of alpha-methyl styrene and acrylonitrile, as described in U.S. Pat. No. 3,053,800. High density information discs fabricated from this molding composition have improved dimensional stability and increased resistance to environmental temperature changes.

Abstract: A test disc record suitable for use in testing a capacitive playback stylus, which includes a stylus shoe which contacts a capacitive information disc record during playback and a stylus electrode which is used to recover information recorded in the capacitive information disc record by means of capacitance variations between the capacitive information disc record and the stylus electrode, wherein the test disc record includes in a major surface a continuous spiral groove which comprises an arrangement of a plurality of spiral groove turns wherein the width of a first spiral groove turn or portion thereof and signal information which can be read out by capacitance means contained in a second spiral groove turn or portion thereof which is contiguous with the first spiral groove turn or portion thereof may be used to test the width of the stylus electrode.A method and an apparatus for testing the capacitive playback stylus which employs the test disc record.

Abstract: A rotary recording medium has an information signal along a spiral main track comprising a multiplicity of successively adjacent track turns of respective track turn numbers, first and second reference signals of different frequencies are recorded alternately in the radial direction of the recording medium and along reference signal tracks disposed centrally between the centerlines of mutually adjacent track turns, and a third reference signal is recorded at points where the track turn numbers change at every revolution of the recording medium. The rotary recording medium comprises, over a plurality of track turns in a specific part of the main track, displacement part for displacement of a reproducing tracing element in which displacement parts only either one of the first and second reference signals has been recorded along reference signal tracks on both sides of each of said plurality of track turns.

Abstract: High density information discs comprising a conductive carbon-loaded polyvinylchloride disc lubricated with a fractionated methyl alkyl siloxane lubricant which contains a hexaalkyldisilazane additive.

Abstract: High density information discs comprising a conductive carbon-loaded polyvinylchloride disc lubricated with a fractionated methyl alkyl siloxane lubricant which contains a tetrakis(dialkylamino)silane additive.

Abstract: High density information discs comprising a conductive carbon loaded polyvinylchloride disc is lubricated with a fractionated methyl alkyl siloxane lubricant which contains an alkyl-substituted-(trialkoxysilyl)alkyl quaternary ammonium salt additive.

Abstract: An information recording medium comprises a silicon substrate, a silicon dioxide film formed on one principal surface of the semiconductor substrate and a silicon nitride film formed on the silicon dioxide film. A recording electrode stylus is moved relative to and along the surface of the silicon nitride film while applying a recording signal voltage between the stylus and substrate, thus causing charges corresponding to the recording signal voltage to be passed through the silicon dioxide film by the tunnel effect and stored in the silicon nitride film.

Abstract: An information signal recording medium of rotary type has a flat surface with successions of pits formed therein as respective concavities in response to an information signal. The successions of pits constitute respective circular tracks of a specific pitch. Each it is formed with a width, equal to the width of a track, which is substantially equal to or greater than said pitch of the track.

Abstract: An information signal recording system records both an information signal and at least one kind of reference signal for providing a tracking control on a recording medium. The reference signal is recorded on an intermediate part of the recording medium. That part is located between the center lines of adjacent tracks on which the information signal is recorded.

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: A conductive video disc replica is cleaned by washing with an aqueous solution comprising an oxidizing agent, a base and a surfactant of a fluorocarbon added in an amount so that the solution has a surface energy of about 35 dynes/cm.sup.2 or less. This solution removes metallic and oxygen-containing impurities from the surface of the disc and leaves a fluorinated surface.

Abstract: Molecular distillation of methyl alkyl siloxanes of the formula ##STR1## wherein R.sub.1 and R.sub.2 are alkyl groups of 4-20 carbon atoms and m and p are integers to produce a distillate having a molecular weight fraction wherein the sum of m and p is about 4, produces an improved lubricant for the video disc, a lubricant that is stable to long term storage and to wide variations in temperature and relative humidity.