US2539156A - Ion trap magnet - Google Patents

Description

Jan. 23 1951 w, osTRElCHER 2,539,156

ION TRAP MAGNET Filed Jan. 19, 1949 FIG. 2

INVEN TOR.

WARREN J, cams/cum.

Patented Jan. 23, 1951 ION TRAP MAGNET Warren J. Ostreicher, New York, N. Y., assignor to Telc-Tone Radio corporation, a corporation of New York' Application January 19, 1949, Serial No. 71,570

I Claim. 1

This invention relates to the correction of the path of an electron beam in cathode ray tubes, such as are used in television receivers, and more specifically to the elimination or diversion of ions caused by the electron beam.

It is an object of the invention to provide a beam correcting unit which is simple in construction, inexpensive in manufacture and which can be easily mounted on or demounted from the associated cathode ray tube.

It is a further object of the invention to provide a magnetic unit permitting the simultaneous production of at least two fields of different field intensities and/or polarities, both spaced from each other so as to apply the different intensities to different, preferably successive, portions of the path of the electron beam. In this way, an effective elimination or deviation of the ions is provided without affecting the correct movement of the electrons.

A more specific object of the invention is to provide a magnetic unit which is light in construction and yet strong enough to be secured to the neck of a cathode ray tube to produce the different field intensities required at the different tube portions, without mechanically straining the envelope of the tube.

Another feature of the invention is accurately to dimension the different magnetic fields without complicating the construction of the magnetlc unit.

It is, therefore, one object of the invention to derive two different fields from a common magnet.

Still another object of the invention is to produce the different field intensities by differently dimensioning the pole pieces guiding the flow of the magnetic field lines.

'Additional feature of the invention is to give the pole pieces such a form as to secure effective gripping of the unit around the neck of the cathode ray tube while guiding the different field lines to the appropriate portions of the electron path.

More specifically, the different pole pieces are constructed to assume the form of a rectangular parallelepiped, with two pairs of legs that convey two different fields, forming the four parallel sides of that parallelepiped.

In another embodiment of the invention the different magnet poles or legs of the unit are coupled directly or indirectly to a single per manent magnet and provided with different cross-sections corresponding to the different field 2 intensities required at the appropriate portions of the electron path.

These and other objects of the invention will be more clearly described in connection with the accompanying drawing in which:

Fig. 1 shows perspectively and more or less schematically, a beam correcting magnetic unit embodying the invention.

Figs. 2 and 3 represent front and side views, respectively, of a more elaborate magnetic unit adapted to be applied to the neck of the cathode ray tube of television receiver.

In Fig. 1, l is a permanently magnetized slug of cylindrical shape which is held between a pair of magnetically conductive metal strips 2 and 3 of substantially L-shape except as to arms 4 and 5 which hold slug I between them. Screws 6 and I, of preferably non-magnetic material, serve to assure the mutual attachment of parts I, 2 and 3. A smaller intensity field is derived from the common magnet l by attachinga'pair of legs 8, 9 to legs 2, 3, respectively, in a crosswise manner so as to obtain different magnetic fields of opposite directions in leg pairs 2, 3 and 8, 9 respectively. Legs 8 and .9 may be attached, re-

. spectively, to legs 3 and 2 at points It and H by welding or any other fixing operation assuring magnetic conductivity.

All the legs forming the pole pieces are preferably substantially of L-shape as shown in Fig. 1 but legs 8 and 9 have a smaller cross-section corresponding to the lower intensity required for re-deviating the electron beam after it has been deviated by legs or pole pieces 2 and 3.

A washer I2 of magnetically insulating or nonconductln material is inserted at the crossing point of legs 8 and 9.

Figs. 2 and 3 show an arrangement similar to that of Fig. 1 and specially adapted to fit around the neck of a cathode ray tube such as is used in a television receiver. The four legs or pole pieces are indicated at l3, l4 and l5, l6 respectively. The legs are also substantially L-shaped but slightly curved at central portions l1, l8 thereof. in accordance with the curvature of the neck of the cathode ray tube to which the magnetic unit is to be fitted. At these curved portions, the legs are provided with sleeves [9 of felt, plastic or the like flexible or elastic material so as to assure proper setting of the unit without damage to the wall of the tube.

Nut and bolt 20, 2|, preferably also of nonmagnetic material, serve to secure the attachment of the unit on the neck of a television tube schematically indicated at 22.

Furthermore, legs or pole pieces may be given any desired shape, cross-section or arrangement in space, and the sequence of the different magnetic fields-may also be changed in any appropriate manner, without exceeding the scope; or

this invention.

The invention .may be applied not only to cathode raytubes for television reception but also to any type of cathode ray apparatus which is to be subjected to difierentially dimensioned or difierentially directed magnetic fields; and not only to deviation and re-deviation but also to all sorts of deflection purposes, Without exceeding the scope of the invention.

What is claimed is:

1. In a cathode ray tube apparatus, means for producing a relatively strong magnetic field for deviating the ray to a relatively strong extent and means for producing a relatively weak magnetic field of such a direction as to compensate a portion of the first mentioned deviation; both said deviating means being Outside the tube having a single common magnet and pole pieces connected to said magnet and having different crosssections corresponding to the ditl'erent fields.

2. Apparatus according to claim 1 in which the pole pieces are arranged in the form or legs at least some of which are adapted to grip around the neck of the cathode ray tube.

3. Apparatus according to claim 1 in which the pole pieces are arranged in the form of legs at least some 01 which are adapted to grip around the neck of the cathode ray tube, said legs having diiTerent cross-sections and extending at one end in substantially the same direction and at the other end coupled to the common magnet, one pair of legs being coupled directly to said common magnet and another pair being coupled to said first pair.

4. In a cathode ray apparatus, at least two means for producing magnetic fields of two difterent constant intensities, respectively, the two means being arranged at a distance from each other along the path of the cathode ray; both said means including a single common magnet and magnetic conductors of diflerent cross-sections corresponding to the diflerent field intensities.

5. Apparatus according to claim 4 whereinthe conductors are 01 substantially L-shape forming the sides 0! a rectangular parallelepiped.

6. Apparatus according to claim 4 wherein there are two pairs of conductors having difierent cross-sections and the conductors of one pair are crossed so as to produce not only a field of an intensity different from that of the other pair but also of a direction opposite to that of the other pair of conductors, and wherein at the crossing point of said pair of crossed conductors,

'the latter are magnetically insulated from each other.

'7. In apparatus including a cathode ray tube which produces a composite beam including elec-' trons and ions, a device for producing a magnetic field for separating the electrons from the ions comprising, a permanent magnet, a first pair 01 pole pieces connected to said magnet and positioned about a portion of said cathode ray tube for producing a first magnetic field through said portion, and a second pair of pole pieces connected to said magnet and positioned about an adjacent portion 0! said cathode ray tube for producing a second magnetic field through said adjacent portion, said pairs of pole pieces being of such configuration that said first and second fieilds are of opposite polarity and said first field is stronger than said second field.

W. J. OS'I'REICI-IER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,181,850 Nlcoll Nov. 28, 1939 2,188,579 Schlesinger Jan. 30, 1940 2,211,613 Bowie Aug. 13, 1940 2,274,586 Branson Feb. 24, 1942 2,472,766 Woodbridge June 7, 1949 2,496,127 Kelar Jan. 31, 1950 2,499,065 Heppner Feb. 28, 1950 2,500,455 Fisher Mar. 14, 1950 2,513,929 Gethmann July 4, 1950 2,522,872 Heppner Sept. 19, 1950

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