GB1076997A - Improvements in or relating to television amplifying circuits - Google Patents

Improvements in or relating to television amplifying circuits

Info

Publication number
GB1076997A
GB1076997A GB355667A GB355667A GB1076997A GB 1076997 A GB1076997 A GB 1076997A GB 355667 A GB355667 A GB 355667A GB 355667 A GB355667 A GB 355667A GB 1076997 A GB1076997 A GB 1076997A
Authority
GB
United Kingdom
Prior art keywords
diode
variation
bandwidth
image
collector
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
GB355667A
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 Electronics UK Ltd
Original Assignee
Philips Electronic and Associated Industries 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
Priority claimed from NL296951A external-priority patent/NL296951A/xx
Application filed by Philips Electronic and Associated Industries Ltd filed Critical Philips Electronic and Associated Industries Ltd
Publication of GB1076997A publication Critical patent/GB1076997A/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • H04N5/20—Circuitry for controlling amplitude response
    • H04N5/205—Circuitry for controlling amplitude response for correcting amplitude versus frequency characteristic
    • H04N5/208—Circuitry for controlling amplitude response for correcting amplitude versus frequency characteristic for compensating for attenuation of high frequency components, e.g. crispening, aperture distortion correction
    • 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
    • H04N5/20—Circuitry for controlling amplitude response
    • H04N5/205—Circuitry for controlling amplitude response for correcting amplitude versus frequency characteristic

Abstract

1,076,997. Television. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Aug. 18, 1964 [Aug. 21, 1963], No. 3556/67. Divided out of 1,076,996. Heading H4F. A video amplifier T 1 has a collector load circuit including capacitance C c and a diode D 2 which has a non-linear current-voltage characteristic, whereby at low signal levels corresponding to dark portions of an image the diode internal resistance is high and the amplifier bandwidth is small, and at high signal levels corresponding to light portions of the image the diode internal resistance is low and the bandwidth is large. The invention, which is particularly applicable to camera channels, is intended to reduce the effect of noise which is most apparent in dark portions of the image and is based on the assumption that noise is proportional to a function (the square root) of bandwidth. The variation of the diode resistance also brings about a variation of amplifier gain, such that the collector gain falls with increase of frequency, and this is offset by an emitter circuit R e , C e which provides degenerative feedback which decreases with increase of frequency. The variation of diode resistance may also be utilized to introduce gamma correction. The characteristic of the collector circuit is made adjustable by the inclusion of a variable resistor 6 in series with diode D 2 . The video signal is applied to the base of transistor T 1 from an emitter follower stage T 2 and has the D.C. component established by a switched clamp stage T 3 . Thermionic tubes may replace the transistors.
GB355667A 1963-08-21 1964-08-18 Improvements in or relating to television amplifying circuits Expired GB1076997A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL296951A NL296951A (en) 1963-08-21 1963-08-21
GB33696/64A GB1076996A (en) 1963-08-21 1964-08-18 Improvements in or relating to television amplifying circuits

Publications (1)

Publication Number Publication Date
GB1076997A true GB1076997A (en) 1967-07-26

Family

ID=26261979

Family Applications (1)

Application Number Title Priority Date Filing Date
GB355667A Expired GB1076997A (en) 1963-08-21 1964-08-18 Improvements in or relating to television amplifying circuits

Country Status (1)

Country Link
GB (1) GB1076997A (en)

Similar Documents

Publication Publication Date Title
US4651210A (en) Adjustable gamma controller
US2760008A (en) Amplifier having controllable signal expansion and compression characteristics
US4298884A (en) Chroma amplifier and color killer
JPS60117880A (en) Dc recoverying circuit
GB1125847A (en) Electronic colour picture system
US4187537A (en) Full-wave rectifier
US4473780A (en) Amplifier circuit and focus voltage supply circuit incorporating such an amplifier circuit
GB1514220A (en) Beam current limiting circuit for a cathode-ray tube
US4250463A (en) Overload protection to prevent saturation of video amplifiers
US3633121A (en) Gamma control circuit
US3783190A (en) Aperture correction circuit for low light level television camera
US3921008A (en) Wide dynamic range logarithmic amplifier arrangement
US3533005A (en) Highly linear gain-controlled video amplifier circuit
US4249208A (en) Gamma correction circuit for a video signal and television camera suitable therefor
GB2117584A (en) Amplifier including cascaded amplifying stages
CA1078504A (en) Video amplifier including an a-c coupled voltage follower output stage
US3737796A (en) Linearly controlled amplifier
WO1989002189A1 (en) Temperature compensated logarithmic amplifier
US3421102A (en) Direct coupled temperature compensated amplifier
US3651339A (en) Feedback clipper
GB1076997A (en) Improvements in or relating to television amplifying circuits
US4015079A (en) Gamma correction circuit
US2848603A (en) Automatic gain control system
US3582800A (en) Low-noise video amplifier
US2954475A (en) Television camera or like head amplifier arrangements