GB397514A - Improvements in and relating to photographic sound records and systems for recording sounds on a light sensitive film - Google Patents

Improvements in and relating to photographic sound records and systems for recording sounds on a light sensitive film

Info

Publication number
GB397514A
GB397514A GB5299/32A GB529932A GB397514A GB 397514 A GB397514 A GB 397514A GB 5299/32 A GB5299/32 A GB 5299/32A GB 529932 A GB529932 A GB 529932A GB 397514 A GB397514 A GB 397514A
Authority
GB
United Kingdom
Prior art keywords
current
valve
resistance
recording
condenser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB5299/32A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BRITISH ACOUSTIC FILMS Ltd
Original Assignee
BRITISH ACOUSTIC FILMS Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BRITISH ACOUSTIC FILMS Ltd filed Critical BRITISH ACOUSTIC FILMS Ltd
Publication of GB397514A publication Critical patent/GB397514A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording 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

Landscapes

  • Amplifiers (AREA)

Abstract

397,514. Valve amplifying circuits. BRITISH ACOUSTIC FILMS, Ltd., Film House, Wardour Street, London. Feb. 22, 1932, No. 5299. Convention date, Feb. 26, 1931. [Class 40 (v).] Photographic soundrecords of the variable width or of the variable density - type and in which the position of the zero line of the sound trace in relation to the edge of the record track, or the average transparency, is displaced as the amplitude of the sounds recorded varies are so produced that the displacement of the zero line or the average transparency is varied more rapidly than the amplitudes as these increase. It is further provided that the "displacement" is effected more slowly than the amplitudes as these decrease.' A record so produced not only masks ground noises but avoids sudden changes in passing from reproduction to silence, and vice versa, owing to the zero line in the case of a varying width record being produced with the form o, Fig. 2. This result is attained by diverting and rectifying a portion of the microphone current being recorded and employing this to adjust the coefficients of conductivity in the electrical recording circuit whereby variations in the rectified current are effected more quickly when the current increases than when it decreases. In one arrangement the microphonic recording current influencing through a transformer T, Fig. 3, an oscillograph e or a recording light source has a portion diverted through a transformer T<1> to a rectifying valve S whose plate circuit includes a smoothing condenser u and a resistance t in parallel, a variable connection from the resistance passing to the grid of an amplifier V whose output is superposed on the recording current. The variation of the internal resistance of the valve S by the incoming current variations changes the time constants of the plate circuit during charging and discharging of the condenser, and by suitable selection of the values of the condenser u and resistance t in relation to the internal resistance of the valve S the shape of the curve representing the rectified current is modified so that variation of current due to a given increase in amplitude takes place more rapidly than variation due to a corresponding decrease in amplitude. This effect is superposed on the recording current to effect the corresponding displacement of the zero line or variation of average transparency. To avoid excessive time of discharge of the condenser, an inductance mav be inserted in series with the resistance t, or in series with the grid leak in the input circuit of the valve S. Specifications 377,675 and 384,333, [Group XXXVIII], are referred to.
GB5299/32A 1931-02-26 1932-02-22 Improvements in and relating to photographic sound records and systems for recording sounds on a light sensitive film Expired GB397514A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE397514X 1931-02-26

Publications (1)

Publication Number Publication Date
GB397514A true GB397514A (en) 1933-08-22

Family

ID=6397226

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5299/32A Expired GB397514A (en) 1931-02-26 1932-02-22 Improvements in and relating to photographic sound records and systems for recording sounds on a light sensitive film

Country Status (1)

Country Link
GB (1) GB397514A (en)

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