GB618976A - Improvements in or relating to photo-electric devices - Google Patents

Improvements in or relating to photo-electric devices

Info

Publication number
GB618976A
GB618976A GB28915/46A GB2891546A GB618976A GB 618976 A GB618976 A GB 618976A GB 28915/46 A GB28915/46 A GB 28915/46A GB 2891546 A GB2891546 A GB 2891546A GB 618976 A GB618976 A GB 618976A
Authority
GB
United Kingdom
Prior art keywords
sound
signal
films
cell
current
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
GB28915/46A
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.)
Philips Lamps Ltd
Koninklijke Philips NV
Original Assignee
Philips Lamps Ltd
Philips Gloeilampenfabrieken NV
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 Philips Lamps Ltd, Philips Gloeilampenfabrieken NV filed Critical Philips Lamps Ltd
Publication of GB618976A publication Critical patent/GB618976A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/3084—Automatic control in amplifiers having semiconductor devices in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G7/00—Volume compression or expansion in amplifiers
    • H03G7/002—Volume compression or expansion in amplifiers in untuned or low-frequency amplifiers, e.g. audio amplifiers

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

618,976. Noise reduction in sound-films. PHILIPS LAMPS, Ltd. Sept. 27, 1946, No. 28915. Convention date, April 6, 1943. Drawings to Specification. [Class 40 (ii)] [Also in Group XXXIX] In a sound-reproducing apparatus for optical sound-films, the unfavourable signal/cell-noise ratio at low levels is improved by the use of a contrast compression system in which the amplified signal-current is rectified and the resulting voltage used to oppose the D.C. potential of the light source, or that of the sound cell. The resulting contrast compression may be neutralized for correct reproduction of the acoustic signal by subsequent contrast expansion controlled by the voltage produced by the rectified signal-current.
GB28915/46A 1943-04-06 1946-09-27 Improvements in or relating to photo-electric devices Expired GB618976A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL618976X 1943-04-06

Publications (1)

Publication Number Publication Date
GB618976A true GB618976A (en) 1949-03-02

Family

ID=19788368

Family Applications (1)

Application Number Title Priority Date Filing Date
GB28915/46A Expired GB618976A (en) 1943-04-06 1946-09-27 Improvements in or relating to photo-electric devices

Country Status (3)

Country Link
US (1) US2591977A (en)
DE (1) DE961031C (en)
GB (1) GB618976A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2839601A (en) * 1950-09-27 1958-06-17 Julius Cato Vredenburg Inglesb Methods of and apparatus for rendering visible magnetic and electric field patterns
US3158852A (en) * 1960-08-23 1964-11-24 Gordon E Schacher Apparatus and procedure for sensing passage of moving thread or the like

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1692904A (en) * 1926-08-06 1928-11-27 American Telephone & Telegraph Amplification of photo-electric call response
DE580638C (en) * 1927-01-28 1933-07-14 Tobis Tonbild Syndikat Akt Ges Method for changing the volume when reproducing optical sound recordings
DE535881C (en) * 1928-09-16 1931-10-16 Zeiss Ikon Ag Device for reproducing or duplicating sound recordings
US1888724A (en) * 1928-11-23 1932-11-22 Westinghouse Electric & Mfg Co Sound recording and reproducing system
USRE18400E (en) * 1930-05-24 1932-03-29 of new yobk
US1946404A (en) * 1930-12-04 1934-02-06 Konemann Heinrich Reproduction of sound from sound film records
DE579784C (en) * 1930-12-05 1933-06-30 Heinrich Koenemann Dr Process for the automatic expansion of the volume range when reproducing optical sound recordings
US1912415A (en) * 1931-03-30 1933-06-06 Bell Telephone Labor Inc Photo electric system
US2082627A (en) * 1931-05-04 1937-06-01 Gen Electric Feedback amplifying circuit for light sensitive devices
DE611613C (en) * 1931-05-04 1935-04-04 Aeg Arrangement for amplifying the currents supplied by a photoelectric device using an amplifier tube connected to the photoelectric device
US1894023A (en) * 1931-12-30 1933-01-10 Bell Telephone Labor Inc Circuits for photo-electric cells
US1974900A (en) * 1932-10-08 1934-09-25 Rca Corp Photophonographic apparatus
DE663973C (en) * 1932-10-08 1938-08-18 Rca Corp Device for regulating the volume of light sounders
DE632958C (en) * 1933-03-22 1936-07-16 Cie Radio Cinema Sa Playback device for optical sound recordings
US2158193A (en) * 1937-09-30 1939-05-16 Eastman Kodak Co Sound reproduction
US2207243A (en) * 1938-04-14 1940-07-09 Rca Corp Volume compression device for sound reproducers
US2169405A (en) * 1938-06-21 1939-08-15 John R Cooney Photoelectric system
US2258762A (en) * 1938-11-10 1941-10-14 Rca Corp Television system
US2253976A (en) * 1938-12-02 1941-08-26 Radio Patents Corp Electrical oscillation translating system
DE719395C (en) * 1939-06-06 1942-04-08 Karl Otto Schmidt Dr Ing Arrangement to reduce the basic noise in sound recordings
US2299398A (en) * 1941-04-30 1942-10-20 Rca Corp Noiseless sound reproducing system

Also Published As

Publication number Publication date
DE961031C (en) 1957-03-28
US2591977A (en) 1952-04-08

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