US2640103A - Synchronizing signal separator - Google Patents

Synchronizing signal separator Download PDF

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Publication number
US2640103A
US2640103A US271362A US27136252A US2640103A US 2640103 A US2640103 A US 2640103A US 271362 A US271362 A US 271362A US 27136252 A US27136252 A US 27136252A US 2640103 A US2640103 A US 2640103A
Authority
US
United States
Prior art keywords
pulses
valve
frame
grid
synchronizing signal
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
US271362A
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English (en)
Inventor
Clements Desmond Reginald
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric 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
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2640103A publication Critical patent/US2640103A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/08—Separation of synchronising signals from picture signals
    • H04N5/10—Separation of line synchronising signal from frame synchronising signal or vice versa

Definitions

  • This invention relates to television receivers and in particular to separating circuits for deriving line and frame synchronising pulses for controlling the scanning of the screen of the cathode ray tube.
  • the present invention provides a separating circuit which is capable of producing steepfronted positive pulses which may be applied directly to such time base circuits.
  • the time constant of the input network RI .CI is such that the valve is cut off by black level and picture signals while the line and frame pulses appear with negative polarity at the screen grid.
  • the suppressor grid is connected via a resistor R5 to a negative potential large enough to cut 011 the anode current.
  • the anode and screen grid are connected to the positive H. T. supply via appropriate dropping resistors R6 and R1 respectively.
  • the separated pulses appearing at the screen grid of valve VI are applied via a resistancecapacity network C2.R2 to the control grid of a second valve V2.
  • This second valve is in this embodiment a pentode having its anode and screen grid connected to the positive H. T. supply via appropriate dropping resistors R8 and R9 respectively and having its suppressor grid at cathode (earth) potential.
  • the valve VZ acts as a phase-changing device to convert the pulses to positive polarity.
  • Line synchronising pulses may be conveniently derived from the screen grid of valve V2 as shown or, if desired, from the anode.
  • the frame and line pulses appearing at the anode of valve V2 are fed back via a resistancecapacity network R3.C3 and a decoupling capacitor C5 to the suppressor grid of valve VI.
  • the network R3 .03 forms an integrating circuit, the time-constant of which is such as to give a large difference between the voltages produced respectively at the suppressor grid of valve VI by line pulses and frame pulses.
  • the voltages applied to the suppressor grid of valve VI are determined by the length of the pulses and the longer frame pulses therefore produce the greater potential buildup.
  • the negative bias on the suppressor grid of valve VI is of such magnitude that an integrated line pulse does not drive the suppressor grid sufficiently positive to allow anode current to flow.
  • an integrated frame pulse drives the suppressor grid above its cut-off voltage and allows the anode to draw current and thus become more negative.
  • valve VI At the end of the first frame pulse the valve VI is cut off at the control grid and a steep positive pulse is produced at the anode which is taken via the resistance-capacity network C434, to synchronise the frame time base.
  • a circuit for separating line and frame synchronising pulses in a television receiver comprising means for applying all the said pulses to one input circuit of a pentode electric discharge device, means for feeding an output from said pentode to the input circuit of a second electric discharge device, means for applying the output from said second device to another input circuit of said pentode through an integrating circuit such that the combination of a frame pulse and an integrated frame pulse produces a second output from said pentode, means for deriving line synchronising pulses from an output of said second device and means for deriving frame synchronising pulses from an output of said pentode.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Picture Signal Circuits (AREA)
  • Synchronizing For Television (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Details Of Television Scanning (AREA)
US271362A 1951-02-19 1952-02-13 Synchronizing signal separator Expired - Lifetime US2640103A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB303105X 1951-02-19

Publications (1)

Publication Number Publication Date
US2640103A true US2640103A (en) 1953-05-26

Family

ID=10305619

Family Applications (1)

Application Number Title Priority Date Filing Date
US271362A Expired - Lifetime US2640103A (en) 1951-02-19 1952-02-13 Synchronizing signal separator

Country Status (4)

Country Link
US (1) US2640103A (fr)
CH (1) CH303105A (fr)
DE (1) DE972808C (fr)
GB (1) GB701985A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2845530A (en) * 1953-09-28 1958-07-29 Elmer J Wade Pulse sorter
US2898458A (en) * 1955-04-12 1959-08-04 Hazeltine Research Inc Phase detector
US2904680A (en) * 1954-06-14 1959-09-15 Du Mont Allen B Lab Inc Retriggered direct coupled sweep circuit
US2910581A (en) * 1954-06-09 1959-10-27 Hazeltine Research Inc Phase detector
US3080532A (en) * 1960-01-14 1963-03-05 Collins Radio Co Voltage variable gain circuit with gate correction

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB629504A (en) * 1947-11-08 1949-09-21 Ferranti Ltd Improvements relating to apparatus for discriminating between electrical pulses

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2845530A (en) * 1953-09-28 1958-07-29 Elmer J Wade Pulse sorter
US2910581A (en) * 1954-06-09 1959-10-27 Hazeltine Research Inc Phase detector
US2904680A (en) * 1954-06-14 1959-09-15 Du Mont Allen B Lab Inc Retriggered direct coupled sweep circuit
US2898458A (en) * 1955-04-12 1959-08-04 Hazeltine Research Inc Phase detector
US3080532A (en) * 1960-01-14 1963-03-05 Collins Radio Co Voltage variable gain circuit with gate correction

Also Published As

Publication number Publication date
DE972808C (de) 1959-10-01
CH303105A (fr) 1954-11-15
GB701985A (en) 1954-01-06

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