US2269540A - Television signal-translating system - Google Patents

Television signal-translating system Download PDF

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Publication number
US2269540A
US2269540A US276594A US27659439A US2269540A US 2269540 A US2269540 A US 2269540A US 276594 A US276594 A US 276594A US 27659439 A US27659439 A US 27659439A US 2269540 A US2269540 A US 2269540A
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US
United States
Prior art keywords
signal
tube
frequency
control
components
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 - Lifetime
Application number
US276594A
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English (en)
Inventor
Arthur V Loughren
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.)
BAE Systems Aerospace Inc
Original Assignee
Hazeltine Corp
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
Priority to NL70278D priority Critical patent/NL70278C/xx
Application filed by Hazeltine Corp filed Critical Hazeltine Corp
Priority to US276594A priority patent/US2269540A/en
Priority to FR864885D priority patent/FR864885A/fr
Priority to DEH5886D priority patent/DE929973C/de
Application granted granted Critical
Publication of US2269540A publication Critical patent/US2269540A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/57—Control of contrast or brightness
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/165—Circuitry for reinsertion of DC and slowly varying components of signal; Circuitry for preservation of black or white level to maintain the black level constant

Definitions

  • This invention relates to television signaltranslating systems and more particularly to an arrangement for stabilizing a video-frequency television signal and controlling the' contrast ratio of the repeated signal in a single vacuumtube amplifier circuit.
  • the invention is, therefore, especially directed to the provision of an improved background-illumination insertion and contrast-adjustingv system fortelevision receivers.
  • the means for adjusting the gain of the amplifier stage comprises means for adjusting degeneration in the stage, while the grid circuit of the tube acts as apeak rectifier stabilizer substantially independent of the circuit for providing a degenerative control, thus to provide stabilization which is substantially unresponsive to the gain control utilized for contrastratio control.
  • A. line-frequency generator II and a field-frequency generator 32 are also provided, coupled to the output circuit of detector l5 for synchronization and connected to scanning coils and 21, respectively, of the cathode-ray tube in a conventional manner. Suitable means are included in the circuits of generators 3i and 32 for selecting the synchronizing-signal components from other modulation components and from each other in a conventional manner.
  • the stages or units just described, with the exception of videofrequency amplifier Ii, presently to be described, may all be of conventional well-known construction so that detailed illustrations and descriptions thereof are unnecessary herein.
  • the radio-frequency 2 and 21 are selected and amplified in the radio-frequency 2 and 21 are disposed about the tube for deamplifier I2 and supplied to the oscillator-modulator 13, wherein they are converted to intermediate-frequency signals which, in turn, are selectively amplified in the intermediate-frequency amplifier I4 and delivered to the detector I5.
  • the modulation components of the signal are derived by the detector l5 and are supplied to the video-frequency amplifier lfi'wherein they are amplified and from which they are supplied to the control grid 2
  • the detected signal components are also supplied to the generators II and 32 to synchronize the operation thereof. Under proper operating conditions of the tube ll, an electron beam is emitted from the cathode I! and accelerated and focused on its fluorescent screen and its intensity is controlled by the control grid 2
  • Saw-tooth current waves are generated in linefrequency and field-frequency generators 3
  • This wave form illustrated corresponds, in general, to the video-frequency wave tom of conventional television practice with the direct-current component removed. Due to the action of the coupling condenser'dd, the unidisectional component of the signal supplied by detector 23 is lost, if it is present in the output signal derived from detector i5, and the signal tends to center itself about the zero axis and to appear, therefore, as illustrated by curve $2. In order for a signal of the wave form of that of curve 42 to be useful at the reproducing device l'i, it must be stabilized, as explained above.
  • the signal is thus stabilized at the output circuit of tube 35 as shown by curve it; that is, the synchronizing peaks of modulation are established at a substantially fixed level as they appear in the output circuit of the tube, and the unidirectional background-illumination component is thereby reinserted in the signal as applied to the cathode-ray reproducing devic ll.
  • a television signal-translating system comprising, a signal-translating channel adapted to have applied thereto an unstabilized television modulation signal having trace and retrace in-' tervals and varying during trace intervals in accordance with video-frequency components having a wide range of frequencies and during retrace intervals in accordance with synchronizingsignal components, a video-frequency stage in said channel including a single vacuum-tube amplifier having an input circuit, means for adjusting the effective transconductance of said vacuum tube to control the gain of said amplifier over the frequency range of said components, and means comprised within said stage and substantially unresponsive to said gain control for stabilizing the translated modulation signal at the input circuit of said amplifierat the level of the peaks of said synchronizing components.
  • a television signal-translating system comprising, a signal-translating channel adapted to have applied thereto an unstabilized television modulation signal having trace and retrace intervals and varying during trace intervals in acprising, a signal-translating channel adapted to have applied thereto an unstabilized television modulation signal having trace and retrace intervals and varying during trace intervals in accordance with video-frequency components having a wide range of frequencies and during retrace intervals in accordance with synchronizingsignal components, a video-frequency stage in said channel including a single degenerative vacuum-tube amplifier having an input circuit, means for adjusting the degeneration of said vacuum-tube amplifier to control the gain of said amplifier over the frequency range of said components, and means comprised within said stage and substantially unresponsive to said gain control for stabilizing the translated modulation si nal at the input circuit of said amplifier at a predetermined level thereof,
  • a television signal-translating system comprising, a signal-translating channel adapted to have applied thereto an unstabilized television modulation signal having trace and retrace intervals and varying during trace intervals in accordance with video-frequency components having a wide range of frequencies and during re-' trace intervals in accordance with synchronizing-signal components, a video-frequency stage in said channel including a.
  • an amplifier in said channel comprising a vacuum tube having a cathode, a control electrode, and an anode, means for adjusting the effective transconductance between said control electrode and said anode to control the gain of said amplifier over the frequency range of said components, and means including said control electrode and said cathode connected to operate as a peak rectifier and substantially unresponsive to said gain control for stabilizing the translated modulation signal at the input circuit of said vacuum tube at a predetermined level thereof.
  • a television signal-translating system comprising, a signal-translating channel adapted to have applied thereto an unstabillzed television modulation signal having trace and retrace intervals and varying during trace intervals in accordance with video-frequency components having a wide range of frequencies and during retrace intervals in accordance with synchronizingsignal components, a vacuum-tube amplifier in said channel including a cathode, a control electrode, and an anode, means including an unbypassed cathode resistor for said vacuum tube ,75 8.
  • a television signal receiver comprising a video-frequency translating channel adapted to V have applied thereto an unstabillzed television modulation signal having trace'and retrace intervals and varying during trace intervals in accordance with video-frequency components having a wide rangepf irequenciesandduring-retrace intervals in accordance with synchronizingsignal components, a video-frequency stage in said channel including a single vacuum tube amplifier having an input circuit, a contrast-ratio 10 control means for said receiver including means for adJusting the etlective transconductance of said vacuum tube to control the gain of said amplifier over the frequency range of said components. andm'eans comprised within said stages I "and substantially unresponsive to said contrast ratio control for stabilizing the translated modulation signal'atthe input circuit of said vacuum tube at a predetermined level thereof.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Receiver Circuits (AREA)
US276594A 1939-05-31 1939-05-31 Television signal-translating system Expired - Lifetime US2269540A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL70278D NL70278C (en, 2012) 1939-05-31
US276594A US2269540A (en) 1939-05-31 1939-05-31 Television signal-translating system
FR864885D FR864885A (fr) 1939-05-31 1940-04-08 Système de translation de signaux en télévision
DEH5886D DE929973C (de) 1939-05-31 1940-11-12 Fernsehempfangseinrichtung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US276594A US2269540A (en) 1939-05-31 1939-05-31 Television signal-translating system

Publications (1)

Publication Number Publication Date
US2269540A true US2269540A (en) 1942-01-13

Family

ID=23057291

Family Applications (1)

Application Number Title Priority Date Filing Date
US276594A Expired - Lifetime US2269540A (en) 1939-05-31 1939-05-31 Television signal-translating system

Country Status (3)

Country Link
US (1) US2269540A (en, 2012)
FR (1) FR864885A (en, 2012)
NL (1) NL70278C (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2550960A (en) * 1947-05-21 1951-05-01 Hazeltine Research Inc Television receiver contrast and brightness control
US2910550A (en) * 1956-04-27 1959-10-27 Bell Telephone Labor Inc Wide-range automatic gain control
US2983787A (en) * 1958-10-24 1961-05-09 Gen Electric Automatic gain control system for a television receiver

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE517826A (en, 2012) * 1952-02-21

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2550960A (en) * 1947-05-21 1951-05-01 Hazeltine Research Inc Television receiver contrast and brightness control
US2910550A (en) * 1956-04-27 1959-10-27 Bell Telephone Labor Inc Wide-range automatic gain control
US2983787A (en) * 1958-10-24 1961-05-09 Gen Electric Automatic gain control system for a television receiver

Also Published As

Publication number Publication date
NL70278C (en, 2012)
FR864885A (fr) 1941-05-07

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