NL7806372A - Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion - Google Patents

Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion

Info

Publication number
NL7806372A
NL7806372A NL7806372A NL7806372A NL7806372A NL 7806372 A NL7806372 A NL 7806372A NL 7806372 A NL7806372 A NL 7806372A NL 7806372 A NL7806372 A NL 7806372A NL 7806372 A NL7806372 A NL 7806372A
Authority
NL
Netherlands
Prior art keywords
switch
output
changeover switch
filter
reference signal
Prior art date
Application number
NL7806372A
Other languages
Dutch (nl)
Original Assignee
Philips 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 Nv filed Critical Philips Nv
Priority to NL7806372A priority Critical patent/NL7806372A/en
Publication of NL7806372A publication Critical patent/NL7806372A/en

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
    • H04N5/18—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit

Landscapes

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

Abstract

The clamping circuit consists of a second device added to a standard reference signal level detection circuit as used in video preamplifiers. A video signal such as brightness control which requires clamping, is applied to the input (1) of an amplifier (3). The amplified signal (5) is applied to the transistor base (7) the emitter of this transistor being connected to earth via a resistor (9) and to a switch (13) via a resistor (11). The output of the switch (13) is connected to a capacitor (15). When the signal received contains a reference component such as brightness control, the switch (13) is closed by an impulse (27) from a control module. Across the condenser (15) occurs a mean DC reference signal free from HF distortion which is applied as feedback to amplifier (3) input (19) and to changeover switch (21) which normally conducts the transitor output (7) to the switch output (23). Switches (13) and (21) are synchronised via control signals (27, 29), thus connecting the clean reference signal to the output (23).
NL7806372A 1978-06-13 1978-06-13 Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion NL7806372A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NL7806372A NL7806372A (en) 1978-06-13 1978-06-13 Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7806372A NL7806372A (en) 1978-06-13 1978-06-13 Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion

Publications (1)

Publication Number Publication Date
NL7806372A true NL7806372A (en) 1979-12-17

Family

ID=19831026

Family Applications (1)

Application Number Title Priority Date Filing Date
NL7806372A NL7806372A (en) 1978-06-13 1978-06-13 Clamp switching for video reference signals - has secondary RC filter and changeover switch to eliminate distortion

Country Status (1)

Country Link
NL (1) NL7806372A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140422A (en) * 1990-07-16 1992-08-18 Eastman Kodak Company Video sync removal circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140422A (en) * 1990-07-16 1992-08-18 Eastman Kodak Company Video sync removal circuit

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Legal Events

Date Code Title Description
A1B A search report has been drawn up
BV The patent application has lapsed