GB762440A - Arrangement for preventing the after-glow of the steady luminous spot after the switching-off of television sets employing cathode-ray tubes - Google Patents

Arrangement for preventing the after-glow of the steady luminous spot after the switching-off of television sets employing cathode-ray tubes

Info

Publication number
GB762440A
GB762440A GB32046/54A GB3204654A GB762440A GB 762440 A GB762440 A GB 762440A GB 32046/54 A GB32046/54 A GB 32046/54A GB 3204654 A GB3204654 A GB 3204654A GB 762440 A GB762440 A GB 762440A
Authority
GB
United Kingdom
Prior art keywords
cathode
switch
potential
tube
grid
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
GB32046/54A
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Publication of GB762440A publication Critical patent/GB762440A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/20—Prevention of damage to cathode-ray tubes in the event of failure of scanning

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)

Abstract

762,440. Cathode-ray tube circuits. STANDARD TELEPHONES & CABLES., Ltd. Nov. 5, 1954 [Dec. 14, 1953], No. 32046/54. Class 40(7) Switch S2 closes when the main supply switch S1 is opened and raises the potential of the grid of cathode-ray tube B (normally determined by brightness potentiometer Pl) towards the cathode potential whereby the increased beam current rapidly discharges the capacity of the tube's anode supply and causes the fluorescent spot to disappear before the scanning circuits have ceased to operate. The arrangement prevents damage to the screen of the tube due to a stationary spot persisting whilst supply circuit capacities discharge and the tube cathode cools. In a second embodiment, Fig. 2 (not shown), the switch is arranged to remove a short-circuit from across a resistor included between the end of the brightness potentiometer and earth so as to cause the grid potential to rise towards H.T. In a third embodiment, Fig. 3 (not shown), the video stage V is directly connected to supply the cathode-ray tube grid instead of the cathode as shown in Fig. 7 (not shown), and the switch is arranged to open the circuit of the brightness potentiometer, which is here connected to the cathode, so that the cathode falls to earth potential whilst the grid remains at the anode potential of the video stage. The switch may be operated by a relay the winding of which is included in the tube heater supply circuit.
GB32046/54A 1953-12-14 1954-11-05 Arrangement for preventing the after-glow of the steady luminous spot after the switching-off of television sets employing cathode-ray tubes Expired GB762440A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DESCH14182A DE1012955B (en) 1953-12-14 1953-12-14 Arrangement to prevent the afterglow of the stationary light spot after switching off devices with cathode ray tubes, especially in television sets

Publications (1)

Publication Number Publication Date
GB762440A true GB762440A (en) 1956-11-28

Family

ID=7427183

Family Applications (1)

Application Number Title Priority Date Filing Date
GB32046/54A Expired GB762440A (en) 1953-12-14 1954-11-05 Arrangement for preventing the after-glow of the steady luminous spot after the switching-off of television sets employing cathode-ray tubes

Country Status (3)

Country Link
AU (1) AU203283B1 (en)
DE (1) DE1012955B (en)
GB (1) GB762440A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112425A (en) * 1959-02-19 1963-11-26 Telefunken Gmbh Protective circuit for cathode ray tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2940004A (en) * 1957-07-01 1960-06-07 Philco Corp Apparatus for quick beam extinction in television receivers
NL235893A (en) * 1959-02-07

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3112425A (en) * 1959-02-19 1963-11-26 Telefunken Gmbh Protective circuit for cathode ray tube

Also Published As

Publication number Publication date
DE1012955B (en) 1957-08-01
AU203283B1 (en) 1955-06-16

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