# US 4,393,361 A · Variable magnetically biased linearity control

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- Number: US 4,393,361 A
- Document ID: US4393361A
- Status: Granted
- Kind: A
- Application number: 06/304,817
- Filed: 1981-09-23
- Granted: 1983-07-12
- Earliest claimed: 1981-09-23
- Assignees: Prem Magnetics, Inc.
- Inventors: Stanley K. Horton
- Web page: https://patentgrep.com/patent/US4393361A

## CPC

- H01J 29/701: {Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least}
- H01F 21/06: by movement of core or part of core relative to the windings as a whole
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A variable magnetically biased coil assembly for providing a linear display on the screen of a cathode ray tube.

## Claims

### Claim 1

A variable magnetically biased linearity coil assembly for use such as with a cathode ray tube display device, comprising, in combination, an essentially I-shaped core, a coil wound on said core, a first permanent magnet stationarily mounted adjacent one end of said I-shaped core, a second permanent magnet mounted adjacent the opposite end of said core, said first and second magnets providing a magnetic field having flux lines extending through said core, a non-magnetizable support mounted adjacent said one end of said core, a cylindrically shaped element having a magnetized substantially flat surface thereon mounted on said support in spaced relation to said core and said magnets with said magnetized flat surface facing said core and said magnet, a mounting shaft extending outwardly from said support in a direction transverse to the axis of said I-shaped core for mounting said element in rotatable relation to said core and said magnets, and rotatable adjustment of said element selectively adjusting the magnetic strength of said second magnet to thereby provide an adjustable linearity coil.

### Claim 2 (depends on 1)

An apparatus as in claim 1, wherein said first and second magnets are mounted on respective ends of said core and said support forms a cap having downwardly extending walls.

### Claim 3 (depends on 1)

An apparatus as in claim 1, wherein the support is generally circular, with one flatted side, in top view and has a flat surface on which said magnet may be mounted in frictional rotatable engagement.

### Claim 4 (depends on 1)

An apparatus as in claim 1, wherein said surface of said cylindrical magnet is polarized to have one North Pole and one South Pole.

### Claim 5 (depends on 1)

An apparatus as in claim 1, further including a base, said second magnet mounted on said base, terminal pins mounted on said base and extending therethrough, two of said pins being connected with said coil for providing electrical connection means to associated electronic circuitry.