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JPS57208770A - Dc level automatic compensating circuit for analog signal repetitively including reference level signal - Google Patents

Dc level automatic compensating circuit for analog signal repetitively including reference level signal

Info

Publication number
JPS57208770A
JPS57208770A JP56093844A JP9384481A JPS57208770A JP S57208770 A JPS57208770 A JP S57208770A JP 56093844 A JP56093844 A JP 56093844A JP 9384481 A JP9384481 A JP 9384481A JP S57208770 A JPS57208770 A JP S57208770A
Authority
JP
Japan
Prior art keywords
signal
level
amplifier
counter
output
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.)
Pending
Application number
JP56093844A
Other languages
Japanese (ja)
Inventor
Mitsuzo Nakahata
Shinji Hamaguchi
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP56093844A priority Critical patent/JPS57208770A/en
Publication of JPS57208770A publication Critical patent/JPS57208770A/en
Pending 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
    • H04N5/16—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

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Picture Signal Circuits (AREA)

Abstract

PURPOSE:To obtain a circuit setting a DC level stably, by comparing the fluctuation of a reference signal level such as a black signal with a preset permissible value, and shifting the DC level of an original signal through the D/A conversion of a count value of the counter either incremented or decremented depending on the result of the comparison. CONSTITUTION:A video signal Vin outputted from an image sensor is applied to a DC amplifier 10. An output VA of a DC amplifier 10 is compared with a reference set value Vref at a comparator 40, and if the output is greater than the set value, a signal is applied to a down or up input of an up-down-counter 50 from a gate 70 and if smaller, from a gate 80. An output of the counter 50 is converted into an analog signal at a D/A converter 60 and supplied as a level shift input VSF of the DC amplifier to compensate the fluctuation of the reference level of the video signal input Vin.
JP56093844A 1981-06-19 1981-06-19 Dc level automatic compensating circuit for analog signal repetitively including reference level signal Pending JPS57208770A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56093844A JPS57208770A (en) 1981-06-19 1981-06-19 Dc level automatic compensating circuit for analog signal repetitively including reference level signal

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56093844A JPS57208770A (en) 1981-06-19 1981-06-19 Dc level automatic compensating circuit for analog signal repetitively including reference level signal

Publications (1)

Publication Number Publication Date
JPS57208770A true JPS57208770A (en) 1982-12-21

Family

ID=14093705

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56093844A Pending JPS57208770A (en) 1981-06-19 1981-06-19 Dc level automatic compensating circuit for analog signal repetitively including reference level signal

Country Status (1)

Country Link
JP (1) JPS57208770A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59163981A (en) * 1983-03-08 1984-09-17 Canon Inc Image pickup device
JPS6258963U (en) * 1985-10-01 1987-04-11
JPS63278471A (en) * 1987-05-11 1988-11-16 Sony Corp Clamping circuit for video signal
US5036388A (en) * 1988-11-10 1991-07-30 U.S. Philips Corporation Apparatus including an improved device for recovering the d.c. component
US5057920A (en) * 1989-02-28 1991-10-15 Sony Corporation Video signal clamping circuit operating in the digital domain for removing excess noise on the black level and for providing d c restoration

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59163981A (en) * 1983-03-08 1984-09-17 Canon Inc Image pickup device
JPS6258963U (en) * 1985-10-01 1987-04-11
JPS63278471A (en) * 1987-05-11 1988-11-16 Sony Corp Clamping circuit for video signal
US5036388A (en) * 1988-11-10 1991-07-30 U.S. Philips Corporation Apparatus including an improved device for recovering the d.c. component
US5057920A (en) * 1989-02-28 1991-10-15 Sony Corporation Video signal clamping circuit operating in the digital domain for removing excess noise on the black level and for providing d c restoration

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