US1807602A - Sound reproducing system - Google Patents

Sound reproducing system Download PDF

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US1807602A
US1807602A US1807602DA US1807602A US 1807602 A US1807602 A US 1807602A US 1807602D A US1807602D A US 1807602DA US 1807602 A US1807602 A US 1807602A
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light
source
devices
reproducing system
sound reproducing
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor

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  • the present invention is concerned with improvements in amplifiers for use with light sensitive devices such for example, as photoelectric cells.
  • One of the objects of the invention is to eliminate or reduce noises caused by the variation in the intensity oi the light source with which the photo-electric cell is used, for example, due to the heating of the filament of the light source with alternating current, or by variation in the voltage of the anode supply battery.
  • apparatus for the reproduction of recorded sound comprises two light sensitive devices and an amplifier adapted to amplify electrical oscillations derived from said devices and corresponding to the difference between their respective illumination.
  • each of said light sensitive devices is associated with the grid circuit of a thermionic valve, one of said devices being illuminated from a light source by light modulated by a sound record and the other of said devices being illuminated from said source by light which is not modulated by said sound record.
  • the anodes of two thermionic valves V and V are connected through separate high resistances 1, 2 to the positive terminal of a battery 3 the negative terminal of which is connected to the filaments of the valves.
  • the primary winding of a transformer 4 is connected between the two anodes and the secondary winding of this transformer constitutes the output of the amplifier.
  • the filaments are heated in parallel from a low tension battery 5, a variable resistance 6 being included in the filament heating circuit.
  • Each of the grids of the valves V and V is connected to the filament circuit throu h a grid leak 7 and in shunt with each of the grid leaks is a photo-electric cell 8, 9 in series with a battery 10.
  • the two photoelectric cells are arranged with their anodes connected to the grids of the valves.
  • the cell 8 receives the light from the source said devices only.
  • the cell 9 receives the light direct from the source 11.
  • the source 11 may be in the form of a filament lamp heated by alternating current.
  • the film 14 is caused to travel past the slit device 13 producing variations in the illumination of the cell corresponding to the sound markings on the film. Since the other photo-electric cell is illuminated directly by the light source the sound record does not afi'ect it. When the adjustment is correct it will be found that hum due to the alternating current in filaments of the light source is not transmitted to the output circuit but differences in illumination of the two cells 8, 9 is transmitted in the form of electrical oscillations to the output circuit.

Description

June 2, 1931. A RADFQRD ET AL 7 1 ,807,602
SOUND REPRODUCING SYSTEM I Filed Aug. 29. 1929 MW W 1 WW Patented June 2, 1931 UNITED STATES PATENT OFFICE ARTHUR STANLEY RADFORD, OI SOUTHALL, AND MICHAEL BOWMAN-MANIFOLD, OF
HAYES, ENGLAND, ASSIGNORS TO VICTOR TALKING MACHINE COMPANY, A COR- PORATION OF NEW JERSEY sormn nnrnonucme svs'rnn Application filed August 29, 1929, Serial No. 389,280, and in Great Britain September 27, 1928.
The present invention is concerned with improvements in amplifiers for use with light sensitive devices such for example, as photoelectric cells. One of the objects of the invention is to eliminate or reduce noises caused by the variation in the intensity oi the light source with which the photo-electric cell is used, for example, due to the heating of the filament of the light source with alternating current, or by variation in the voltage of the anode supply battery. I
According to the present invention apparatus for the reproduction of recorded sound comprises two light sensitive devices and an amplifier adapted to amplify electrical oscillations derived from said devices and corresponding to the difference between their respective illumination.
According to the present invention in the preferred form, each of said light sensitive devices is associated with the grid circuit of a thermionic valve, one of said devices being illuminated from a light source by light modulated by a sound record and the other of said devices being illuminated from said source by light which is not modulated by said sound record.
The invention is illustrated, by way of example, in the accompanying drawing.
Referring to the drawing, the anodes of two thermionic valves V and V are connected through separate high resistances 1, 2 to the positive terminal of a battery 3 the negative terminal of which is connected to the filaments of the valves. The primary winding of a transformer 4 is connected between the two anodes and the secondary winding of this transformer constitutes the output of the amplifier. The filaments are heated in parallel from a low tension battery 5, a variable resistance 6 being included in the filament heating circuit.
Each of the grids of the valves V and V is connected to the filament circuit throu h a grid leak 7 and in shunt with each of the grid leaks is a photo-electric cell 8, 9 in series with a battery 10. The two photoelectric cells are arranged with their anodes connected to the grids of the valves.
The cell 8 receives the light from the source said devices only.
11 after the light has passed through an optical system 12, a slit device 13 and a sound record film 14. The cell 9 receives the light direct from the source 11. The source 11 may be in the form of a filament lamp heated by alternating current. The film 14 is caused to travel past the slit device 13 producing variations in the illumination of the cell corresponding to the sound markings on the film. Since the other photo-electric cell is illuminated directly by the light source the sound record does not afi'ect it. When the adjustment is correct it will be found that hum due to the alternating current in filaments of the light source is not transmitted to the output circuit but differences in illumination of the two cells 8, 9 is transmitted in the form of electrical oscillations to the output circuit.
In a modification of a circuit above de scribed, high tension is supplied to the anodes of the two valves V and V through the primary winding of the output transformer 4 the centre point of this windin being connected to the positive terminal -0 the battery and the resistances 1 and 2 can then be omitted.
We claim: 1. In apparatus for the reproduction of recorded sound, the combination of two thermionic valve amplifiers arranged in opposition and having a common'output, two light sensitive devices one connected across the input of each amplifier, a common light source for said devices, and means for modulating the light passing from said source to one of 2. In apparatus for the reproduction of recorded sound, the combination of two thermionic valve amplifiers having input and output circuits and arranged in opposition, a resistance in each of said output circuits, a resistance in each of said input circuits, a translating device connected to both output circuits, two light sensitive devices one connected in each input circuit, acommon light source for said light sensitive devices, and means for modulating the light passing from said source to one only of said light sensitive devices.
3. In apparatus for the reproduction of recorded sound, the combination of two thermi-- onic valve amplifiers, a common source of anode potential for saidQamplifiers a resistance connected between said source andeach of said amplifiers, a translating device connected across said resistances, a resistance connected across the input of each of said amplifiers, a light sensitive device in parallel with each input resistance, a common light source for said light sensitive devices, means for modulating the light passing from said source to one only of said devices.
In testimony whereof we have signed our names to this specification.
ARTHUR STANLEY RADFORD.
MICHAEL BOWMAN-MANIFOLD.
and e
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2480835A (en) * 1946-12-10 1949-09-06 Westinghouse Electric Corp Photoelectric control apparatus
US2505420A (en) * 1945-08-28 1950-04-25 Dorris C Mccrary Control system for regulating quantities, forces, or other factors
US2531951A (en) * 1944-08-02 1950-11-28 W I Westervelt Interference reducing method of secret communication
DE916091C (en) * 1939-07-27 1954-08-02 Siemens Ag Arrangement for compensation of the anode quiescent current
US3118067A (en) * 1961-09-29 1964-01-14 George F Masin Circuit for effectively eliminating optical cross-talk inherent between channels of a multi-channel optical detecting device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE916091C (en) * 1939-07-27 1954-08-02 Siemens Ag Arrangement for compensation of the anode quiescent current
US2531951A (en) * 1944-08-02 1950-11-28 W I Westervelt Interference reducing method of secret communication
US2505420A (en) * 1945-08-28 1950-04-25 Dorris C Mccrary Control system for regulating quantities, forces, or other factors
US2480835A (en) * 1946-12-10 1949-09-06 Westinghouse Electric Corp Photoelectric control apparatus
US3118067A (en) * 1961-09-29 1964-01-14 George F Masin Circuit for effectively eliminating optical cross-talk inherent between channels of a multi-channel optical detecting device

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