JPS56111375A - Picture signal amplifying circuit - Google Patents

Picture signal amplifying circuit

Info

Publication number
JPS56111375A
JPS56111375A JP1396080A JP1396080A JPS56111375A JP S56111375 A JPS56111375 A JP S56111375A JP 1396080 A JP1396080 A JP 1396080A JP 1396080 A JP1396080 A JP 1396080A JP S56111375 A JPS56111375 A JP S56111375A
Authority
JP
Japan
Prior art keywords
picture signal
amplifier
amplification factor
light
amplifying circuit
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
JP1396080A
Other languages
Japanese (ja)
Inventor
Yoshiaki Kamimoto
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.)
Ricoh Co Ltd
Original Assignee
Ricoh Co 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 Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP1396080A priority Critical patent/JPS56111375A/en
Publication of JPS56111375A publication Critical patent/JPS56111375A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4072—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on the contents of the original

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Control Of Amplification And Gain Control (AREA)

Abstract

PURPOSE:To reproduce a picture with high fidelity by controlling the amplification factor of a picture signal amplifier in accordance with the level of a picture signal, which has been varied by a variation of the quantity of light of the light source. CONSTITUTION:A solid scanning element 4 is applied to the variable amplification factor amplifier 6. The peak value of an output signal of the amplifier 6 is held by the peak holding circuit 7, it is compared with the reference voltage from the voltage divider 8 by the error amplifier 9, its error output is fed back to the amplifier 6, and the amplification factor is controlled. In this way, a picture signal level which has been varied by a variation of the quantity of light of the light source is held at a constant value, and a picture signal with high fidelity can be obtained.
JP1396080A 1980-02-07 1980-02-07 Picture signal amplifying circuit Pending JPS56111375A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1396080A JPS56111375A (en) 1980-02-07 1980-02-07 Picture signal amplifying circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1396080A JPS56111375A (en) 1980-02-07 1980-02-07 Picture signal amplifying circuit

Publications (1)

Publication Number Publication Date
JPS56111375A true JPS56111375A (en) 1981-09-03

Family

ID=11847773

Family Applications (1)

Application Number Title Priority Date Filing Date
JP1396080A Pending JPS56111375A (en) 1980-02-07 1980-02-07 Picture signal amplifying circuit

Country Status (1)

Country Link
JP (1) JPS56111375A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58127469A (en) * 1982-01-25 1983-07-29 Matsushita Graphic Commun Syst Inc Automatic contrast compensating circuit

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4983314A (en) * 1972-12-13 1974-08-10

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4983314A (en) * 1972-12-13 1974-08-10

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58127469A (en) * 1982-01-25 1983-07-29 Matsushita Graphic Commun Syst Inc Automatic contrast compensating circuit
JPS6340072B2 (en) * 1982-01-25 1988-08-09 Matsushita Graphic Communic

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