Methods and devices for recording, engraving and reproducing modulated information in tetraphony
OwnerAndre Marie Bernard Charlininventor
Life of this patent
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Abstract
A microgroove disk record for monophonic, stereophonic and tetraphonic reproduction of modulated information recorded on four separated tracks one of which corresponds to a left fore channel, another one to a right fore channel, another one to a left rear channel and another one to a right rear channel, comprising two adjacent parallel grooves one of which carries the tracks corresponding to the left fore and right fore channels and the other one carries the tracks corresponding to the left rear and right rear channels, the spacing between both channels being variable according to the modulation.
Claims7
A method of engraving a microgroove disk for recording modulated information such as music which may be reproduced in tetraphony and previously recorded on four tracks of a magnetic tape, comprising the steps of engraving a first groove including two separated tracks corresponding to a left front channel and a right front channel, respectively;
- simultaneously engraving a second groove to extend in substantially parallel and adjacent relation to the first one and including two separated tracks corresponding to a left rear channel and a right rear channel, respectively;
- and simultaneously with the engraving of the first groove and the engraving of the second groove varying the spacing between the first and second grooves being engraved in accordance with the amplitude of the modulation of information, the spacing being varied greater than and less than a predetermined mean spacing between the first and second grooves.
In a microgroove disk engraving apparatus for recording stereophonic signals wherein a first stereophonic recording stylus and first coils are controlled by two first information signals,
- the improvement comprising the attachment thereto of a second stereophonic recording stylus and second coils controlled by two second information signals, and
- means for varying the spacing between said first and second recording styluses comprising,
- means for generating a direct current signal proportional to the amplitude of said information being recorded, and
- means for applying said direct current signal to said first and second coils, this direct current signal causing the spacing between the first and second recording styluses to vary as a function of the direct current signal.
A device for tetraphonically engraving a microgroove disk with information from four separate sources of electrical information signals, the signals varying at least in response to the magnitude of the information, the device comprising
- first means for cutting a groove in the disk including
- a first sterophonic recording stylus,
- first drive coils for operating the stylus in response to electrical information signals from the two of the sources, the operating of the first stylus including movement thereof transversely with respect to the length of the first groove, and
- first means for adjusting the depth of the first groove,
- second means for simultaneously cutting a second groove adjacent and parallel to the first groove in the disk including
- a second sterophonic recording stylus positioned at a predetermined mean distance from the first stylus in a direction transverse to the length of the grooves, second drive coils for operating the stylus in response to electrical information signals from the remaining two sources, the operating of the second stylus including movement thereof transversely with respect to the length of the second groove, and
- second means for adjusting the depth of the second groove,
- means for sensing the amplitude of the information represented by the electrical information signals, and
- means for varying the distance between the first stylus and the second stylus as a function of the amplitude of the information being sensed by the sensing means, the distance being varied greater and less than the predetermined mean distance between the first stylus and the second stylus.
Dependencies are inferred from the claim text.