US2873413A - Magnetic-field-producing device - Google Patents

Magnetic-field-producing device Download PDF

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Publication number
US2873413A
US2873413A US550115A US55011555A US2873413A US 2873413 A US2873413 A US 2873413A US 550115 A US550115 A US 550115A US 55011555 A US55011555 A US 55011555A US 2873413 A US2873413 A US 2873413A
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US
United States
Prior art keywords
teeth
magnets
magnetic
flux
tube
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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
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US550115A
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English (en)
Inventor
Reynst Maximilien Felix
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.)
US Philips Corp
North American Philips Co Inc
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US Philips Corp
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Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
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Publication of US2873413A publication Critical patent/US2873413A/en
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/64—Magnetic lenses
    • H01J29/68—Magnetic lenses using permanent magnets only

Definitions

  • the device according to the invention is characterized in that an annular soft-iron disc is arranged between the magnets and co-axially therewith, at least one edge of the disc having a particular profile for controlling the magnetic flux, co-operating with a likewise profiled substantially annular and coaxial softiron pole-piece, in such manner that the flux in the gap between the profiles flows substantially between the magnetic rings.
  • the cooperating parts are preferably provided with adjacent toothed portions with the same pitch of teeth.
  • FIG. 1 and 2 show an embodiment, one half in axial section and cross-section, respectively, and the other half in side view and elevation view, respectively.
  • Fig. 3 shows a slightly modified construction in axial section and Fig. 4 shows a detail of another variant.
  • Figs. 1, 2 and 3 show a magnetic electron lens which may surround the neck of a cathode-ray tube 1 (not shown further).
  • the lens substantially comprises two flat rings 3 and 5 which are axially magnetized and-consist of permanent magnetic material, preferably ceramic material of the kind described in British Patent No. 798,127.
  • the two rings 3 and 5 are, co-axially arranged side by side with the poles of like polarity-in this case the north polesadjacent one another.
  • a substantially annular disc 7 of soft iron is arranged coaxially between the two rings 3 and 5 .
  • the assembly 3, 5, 7, is externally covered with two soft-iron discs 9 and 11, constituting flanges on two short soft-iron pieces of tube 13 and 15.
  • the inner edge of disc 7 is provided with teeth 17 and concentrically embraces a soft-iron disc 19 constituting a flange on a mately the same diameter as that of the tube pieces 13 and 15.
  • the flange 19 externally comprises the same number of teeth (indicated by 23) as the disc 7, which teeth thus have the same pitch as the teeth 17 and in the position shown are in opposition to said teeth (that is to say'in straight opposition).
  • the disc 7 is externally provided with teeth 25, the number and the pitch of which are thus equal to those of the teeth 17 and 23.
  • the disc 7 and the magnets 3 and 5 are coaxially surrounded by a soft-iron piece of tube 27 comprising teeth 29 and 31 on the two edges and a series of windows 33 provided centrally on its circumference.
  • the series of teeth 29 and 31 are in opposition to series of teeth 35 and 37 formed on the edges of the flanges 9 and 11.
  • the numbers and the pitches of all these teeth and windows are equal to those of the teeth previously described.
  • Magnetic fields occurs between the piece of tube 21 and the pieces of tube 13, 15, which fields may be used in known manner for concentrating an electron beam passing through the neck of the tube I. Said fields extend wholly symmetrically with respect to the disc 7 and for the sake of convenience only the field at the left of the disc will be considered more fully hereinafter.
  • the teeth 17 and 23 are in straight opposition and it will be evident that at this position the gap is at a minimum and the magnetic reluctance in the circuit of the lines of force 43, 45 is minimum, and maximum at the position at which the parts 7 and 19 have been turned through an angle or equal to the half pitch of the teeth.
  • the magnetic fiux in the neck of the tube 1 is as great and as small as possible at the said two positions, it thus being possible to corn trol the flux (and the field strength) by turning the part 7 or 19 relative to the other.
  • the magnetic connection between the flange 9 (or 11) and the ring 27 extends in the case shown via teeth 35 and 29 (and 37, 31) formed on said parts.
  • the magnetic reluctance resulting from said transition is in series with that resulting from the teeth 25 and 49 and is controlled I in the same sense.
  • Theadditional variation thus obtained is not great, since lines of force (for example line of force 51) can laterally enter the flange 9, but it assists in the variation brought about by the teeth and bridge pieces 25 and '49.
  • the ring 27 may have inwardly directed teeth 53 to substitute the bridge pieces 49.
  • windows 55 cooperating with the teeth 17, similar to the windows 33 in the part 27 (as shown in Fig. 1) and the teeth 25 in the disc 7, to be provided in the piece of tube 2-1.
  • the edges of the'fianges 9, 11 and those of the ring 27 are not provided with teeth.
  • Fig. 4 shows a profile of amodification of the discs 7 and 21 which may be used, for example instead of the teeth 17 and 23.
  • a magnetic-field-producing. device comprising two, annular, coaxial, closely spaced, permanent magnets each magnetized in its axial direction so that like poles face each other, a first annular soft ferromagnetic member disposed between and coaxially with the two magnets, and a second annular soft ferromagnetic member arranged coaxially relative to' the magnets and adjacent the first soft ferromagnetic member and themagnets, said first and second soft ferromagnetic members having portions facing each other in a radial direction and defining an airgap therebetween and forming, in accordance with their relative positions, reluctance paths of different magnitude, said air-gap being located substantially between said two magnets and lying substantially within an area encompassed by the outer and inner diameters of the annular magnets, said first and second soft ferromagnetic membersbeing relatively movable so as to'vary the reluctance path for the flux produced by said magnets,'whereby magnetic fields with a wide range of intensities are obtainable
  • A'device producing: a'variable permanent magnetic field, comprising a pair of continuous, annular, coaxial, closely spaced, permanent magnets each magnetized in its axial direction producing poles of like polarity on facing surfaces, a first annular soft ferromagnetic member mounted between, abutting and coaxially with the two magnets and a second annular soft ferromagnetic mem- bert arranged coaxially with the tWO magnets and within and substantially coplanar with'the first member, said first-and second members having radially-extending, facing, toothed portions of the same pitch defining an annular space lying between and adjacent the magnets and substantially within the spacebounded by the magnets, said two members being relatively axially rotatable to thereby vary the reluctance path for flux produced by the magnets and thereby. vary the strength of an internally-produced permanent magnetic field.
  • a device producing a variable permanent magnetic field comprising a pair of continuous, annular, coaxial, spaced, permanent magnets each magnetized in its axial direction producing poles of like polarity on facing surfaces, said magnets being spaced apart a distance smaller than their radial thickness, a first annular soft ferromagnetic member mounted between, abutting and coaxiallywith the'two magnets, and a second annular soft ferromagnetic member arranged coaxially with the two magnets and substantially coplanar with the first member, said first member having a radially-extending, toothed portion, said second-member having a plurality of circumferentially-arranged apertures aligned with, facing, and of the same p'it'ch as the, teeth on the toothed portion and defining between the two members air-gaps, the airgaps between the facing portions of the first and second members being located substantiallydirectly between the pair of magnets, said two members being relatively axially rotatable to thereby vary the re
  • a device producing a variable permanent magnetic field comprising a pair of continuous, annular,'coaxial, spaced,,permanent magnets each magnetized in its axial direction so that like, poles face one another, a first annular soft ferromagnetic member mounted between, abuttingand coaxially with the two magnets, said first member having inner and outer radially-extending toothed portions of thesame given pitch, a second annular soft ferromagnetic member arranged coaxially with, within, abutting and substantially coplanar with the first member, said second member havingv a radially-extending toothed portion'of said given pitch cooperating with the inner toothed portion of said first member to define reluctance paths for the-flux produced by said magnets, and a third annular soft ferromagnetic member arranged coaxially with the first and second members, saidthird member having a toothed portion of said given pitch cooperating with the outer toothed portion of said first member to define reluctance paths for

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US550115A 1954-12-04 1955-11-30 Magnetic-field-producing device Expired - Lifetime US2873413A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL822485X 1954-12-04

Publications (1)

Publication Number Publication Date
US2873413A true US2873413A (en) 1959-02-10

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US550115A Expired - Lifetime US2873413A (en) 1954-12-04 1955-11-30 Magnetic-field-producing device

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US (1) US2873413A (enrdf_load_stackoverflow)
DE (1) DE1031442B (enrdf_load_stackoverflow)
FR (1) FR1139451A (enrdf_load_stackoverflow)
GB (1) GB822485A (enrdf_load_stackoverflow)
NL (1) NL86361C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021458A (en) * 1958-05-13 1962-02-13 Philips Corp Permanent magnet systems
US3146191A (en) * 1961-05-12 1964-08-25 Indiana General Corp Variable magnetic strength permanent magnetic drum
US3387158A (en) * 1965-04-14 1968-06-04 Sony Corp Focus magnet assembly for cathode ray tubes

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2333230A (en) * 1940-12-24 1943-11-02 O S Walker Co Inc Magnetic chuck
US2369769A (en) * 1942-09-04 1945-02-20 American Viscose Corp Apparatus for the liquid treatment of yarn and the like
US2608665A (en) * 1950-07-29 1952-08-26 Gen Electric Permanent magnet focusing device
US2714678A (en) * 1950-09-03 1955-08-02 Siemens Ag Electron microscopes
US2740064A (en) * 1952-08-26 1956-03-27 Hartford Nat Bank & Trust Co Permanent magnet focussing device for cathode ray tubes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2333230A (en) * 1940-12-24 1943-11-02 O S Walker Co Inc Magnetic chuck
US2369769A (en) * 1942-09-04 1945-02-20 American Viscose Corp Apparatus for the liquid treatment of yarn and the like
US2608665A (en) * 1950-07-29 1952-08-26 Gen Electric Permanent magnet focusing device
US2714678A (en) * 1950-09-03 1955-08-02 Siemens Ag Electron microscopes
US2740064A (en) * 1952-08-26 1956-03-27 Hartford Nat Bank & Trust Co Permanent magnet focussing device for cathode ray tubes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3021458A (en) * 1958-05-13 1962-02-13 Philips Corp Permanent magnet systems
US3146191A (en) * 1961-05-12 1964-08-25 Indiana General Corp Variable magnetic strength permanent magnetic drum
US3387158A (en) * 1965-04-14 1968-06-04 Sony Corp Focus magnet assembly for cathode ray tubes

Also Published As

Publication number Publication date
GB822485A (en) 1959-10-28
DE1031442B (de) 1958-06-04
FR1139451A (fr) 1957-07-01
NL86361C (enrdf_load_stackoverflow)

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