US2748305A - Cathode ray tubes for television and like purposes - Google Patents

Cathode ray tubes for television and like purposes Download PDF

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Publication number
US2748305A
US2748305A US476667A US47666754A US2748305A US 2748305 A US2748305 A US 2748305A US 476667 A US476667 A US 476667A US 47666754 A US47666754 A US 47666754A US 2748305 A US2748305 A US 2748305A
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US
United States
Prior art keywords
tube
screen
television
neck
coils
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
US476667A
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English (en)
Inventor
Davies Eric
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.)
Marconis Wireless Telegraph Co Ltd
BAE Systems Electronics Ltd
Original Assignee
Marconi 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 Marconi Co Ltd filed Critical Marconi Co Ltd
Application granted granted Critical
Publication of US2748305A publication Critical patent/US2748305A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/867—Means associated with the outside of the vessel for shielding, e.g. magnetic shields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement

Definitions

  • This invention relates to cathode ray tubes for television and like purposes and more specifically to such tubes in which electro-magnetic scanning and focussing coils are provided side by side around the neck of the tube.
  • the present invention seeks to reduce or substantially eliminate mutual interference between adjacent focussing and deflecting coils without introducing any but very small energy losses.
  • a television or like cathode ray tube of the kind having focussing and deflection coils next to one another about the neck thereof, wherein at least one magnetic screen is mounted between said coils and said neck, the screen being sub-divided and constructed so as to provide a large number of magnetic paths, said paths together presenting relatively low reluctance to magnetic lines of force running substantially radially with respect to the neck of the tube, and relatively high reluctance to mag netic lines of force running substantially parallel to the axis of the tube.
  • a magnetic screen constituted by a fine wire of flattened toroidal form and made of material having ferro-magnetic properties.
  • the fine wire may be of a suitable resistive alloy, but ordinary soft iron is quite satisfactory.
  • the wire may be wound on an annular former which may be of insulating material and has an inner diameter such as to pass the neck of the tube andan outer diameter large enough to extend radially beyond the coils. The thickness of the former (if used) is made quite small so that the focussing and deflecting coils can be quite close together.
  • a former of conductive material for example, copper
  • a former of conductive material for example, copper
  • Fig. l is a schematic representation showing a wound screen, in position round the neck of a tube
  • Fig. 2 is a schematic perspective view of the screen removed from the tube.
  • Figs. 3 and 4 show stages in the manufacture of a modified form of screen.
  • FIG. 1 is a neck of a television cathode ray tube (shown broken away at both ends of the neck) on which is mounted a focussing coil assembly 2 and a deflecting coil assembly 3. Between these two coil assemblies and acting as a screen to prevent mutual interference is a wound screen 4.
  • the screen 4 consists of an annulus 4a (Fig. 2) which may be either of insulating material or of conductive material such as copper, on which is wound a winding db of fine ferromagnetic and preferably resistive wire, for example, enamel or oxide covered Nichrome wire of 38 S. W. G.
  • the two adjacent ends of the winding may be left open or may be connected together.
  • the turns of the winding are substantially radial with respect to the neck of the tube and, accordingly, each side of it presents a very large number of radial ferromagnetic paths for lines of force running radially so that there is a relatively low reluctance magnetic path for the fringing fields of both coils to prevent each from coupling materially with the other.
  • Suitable dimensions for a screen 4 as fitted to an existing high quality monitor tube are:
  • the annulus 4a is dispensed with and the winding 41; is wound back and forth in a zigzag so that it occupies a rectangular area as shown in Fig. 3.
  • the winding is then bent round into an annulus as shown in Fig. 4.
  • a suitable impregnating material not shown
  • a television or like cathode ray tube of the kind having focusing and deflection coils next to one another about the neck thereof, wherein at least one magnetic screen is mounted between said coils and said neck, the screen being sub-divided and constructed so as to provide a large number of magnetic paths, said paths together presenting relatively low reluctance to magnetic lines of force running substantially radially with respect to the neck of the tube, and relatively high reluctance to magnetic lines of force running substantially parallel to the axis of the tube.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Geophysics And Detection Of Objects (AREA)
US476667A 1954-01-15 1954-12-21 Cathode ray tubes for television and like purposes Expired - Lifetime US2748305A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1329/54A GB769401A (en) 1954-01-15 1954-01-15 Improvements in or relating to television and like cathode ray tube apparatus having magnetic screens

Publications (1)

Publication Number Publication Date
US2748305A true US2748305A (en) 1956-05-29

Family

ID=9720104

Family Applications (1)

Application Number Title Priority Date Filing Date
US476667A Expired - Lifetime US2748305A (en) 1954-01-15 1954-12-21 Cathode ray tubes for television and like purposes

Country Status (5)

Country Link
US (1) US2748305A (enrdf_load_stackoverflow)
ES (1) ES218620A1 (enrdf_load_stackoverflow)
FR (1) FR1115306A (enrdf_load_stackoverflow)
GB (1) GB769401A (enrdf_load_stackoverflow)
NL (2) NL99008C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2834901A (en) * 1954-05-06 1958-05-13 Rca Corp Cathode ray tube adjunct
US3061753A (en) * 1958-12-06 1962-10-30 Philips Corp Indicating system comprising a cathode ray tube
US4806894A (en) * 1986-12-09 1989-02-21 Mitsubishi Denki Kabushiki Kaisha Apparatus for cancelling leakage magnetic field

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2414925A (en) * 1944-01-26 1947-01-28 Farnsworth Television & Radio Scanning and focusing yoke
US2463720A (en) * 1947-02-19 1949-03-08 Rca Corp Electron beam influencing apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2414925A (en) * 1944-01-26 1947-01-28 Farnsworth Television & Radio Scanning and focusing yoke
US2463720A (en) * 1947-02-19 1949-03-08 Rca Corp Electron beam influencing apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2834901A (en) * 1954-05-06 1958-05-13 Rca Corp Cathode ray tube adjunct
US3061753A (en) * 1958-12-06 1962-10-30 Philips Corp Indicating system comprising a cathode ray tube
US4806894A (en) * 1986-12-09 1989-02-21 Mitsubishi Denki Kabushiki Kaisha Apparatus for cancelling leakage magnetic field

Also Published As

Publication number Publication date
ES218620A1 (es) 1955-04-16
FR1115306A (fr) 1956-04-23
GB769401A (en) 1957-03-06
NL99008C (enrdf_load_stackoverflow)
NL193774A (enrdf_load_stackoverflow)

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