# US 4,398,166 A · Compensator for CRT deflection yokes and the like > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,166 A - Document ID: US4398166A - Status: Granted - Kind: A - Application number: 06/268,730 - Filed: 1981-06-01 - Granted: 1983-08-09 - Earliest claimed: 1981-06-01 - Assignees: Northern Telecom Limited - Inventors: Donald L. Bumgardner - Web page: https://patentgrep.com/patent/US4398166A ## CPC - H01J 29/701: {Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least} - H01J 29/703: {Static convergence systems} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A compensator for CRT deflection yokes and the like comprises a housing shaped for connection with the deflection yoke, and at least one magnet rotatably mounted therein. Selective rotation of the magnet alters the electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display. A detented spring arrangement positively and releasably retains the magnet in a set, adjusted angular position in the housing. ## Claims ### Claim 1 A compensator for CRT deflection yokes and the like, comprising: a housing adapted for fixed mounting adjacent a CRT deflection yoke; at least one magnet; a wheel comprising a manually rotatable carrier for said magnet, said wheel including means for carrying said magnet adjacent to and generally in the same plane with said wheel; means for rotatably mounting said wheel and the said magnet carried therewith upon said housing; and means for positively and releasably engaging said wheel to thereby retain said magnet in a selected position of wheel rotation with respect to said housing, to thereby enhance selective positioning of said magnet altering the effective electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display, and to maintain such selected magnet position; said housing being adapted for mounting in a position in which it at least partially encircles the longitudinal axis of the CRT with the housing disposed in a plane generally perpendicular to said CRT axis, and said magnet having oppositely-disposed poles and being carried by said wheel for rotation about an axis disposed generally perpendicular to said plane of said housing and generally parallel to the said CRT axis. ### Claim 2 A compensator for CRT deflection yokes and the like, comprising: a housing adapted for fixed mounting adjacent a CRT deflection yoke; at least one magnet; a wheel comprising a manually rotatable carrier for said magnet, said wheel including means for carrying said magnet adjacent to and generally in the same plane with said wheel and for mounting said magnet in said wheel generally coaxially therewith; means for rotatably mounting said wheel and the said magnet carried therewith upon said housing; and means for positively and releasably engaging said wheel to thereby retain said magnet in a selected position of wheel rotation with respect to said housing, to thereby enhance selective positioning of said magnet altering the effective electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display, and to maintain such selected magnet position; said means for releasably engaging said wheel means comprising a spring-biased member contacting the circumferential periphery of said wheel. ### Claim 3 (depends on 2) A compensator as set forth in claim 2, wherein: said wheel includes a partially-exposed peripheral edge, and wherein said edge is serrated around the periphery of the wheel. ### Claim 4 (depends on 5) A compensator as set forth in claim 5, including: a second magnet rotatably carried by a second wheel mounted in said housing adjacent said first-named wheel and magnet, for rotation in a substantially parallel plane therewith. ### Claim 5 (depends on 4) A compensator as set forth in claim 4, wherein: said first and second wheel-mounted magnets are disposed side-by-side and coaxial to form a first pair, and wherein said magnet-carrying wheels can be rotated both individually and together. ### Claim 6 (depends on 2) A compensator as set forth in claim 2, including: second and third wheel-mounted magnet devices mounted on said housing and spaced circumferentially with respect to said CRT from said first such wheel-magnet and from each other. ### Claim 7 (depends on 6) A compensator as set forth in claim 6, including: a stationary magnet fixedly mounted in said housing with a lateral central axis thereof positioned along a radially extending line disposed symmetrical with said first, second, and third wheel-mounted magnets. ### Claim 8 A compensator for CRT deflection yokes and the like, comprising: a housing adapted for fixed mounting adjacent a CRT deflection yoke; at least one magnet; a wheel comprising a manually rotatable carrier for said magnet, said wheel including means for carrying said magnet adjacent to and generally in the same plane with said wheel; means for rotatably mounting said wheel and the said magnet carried therewith upon said housing; and means for positively and releasably engaging said wheel to thereby retain said magnet in a selected position of wheel rotation with respect to said housing, to thereby enhance selective positioning of said magnet altering the effective electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display, and to maintain such selected magnet position; said magnet being mounted upon said wheel to rotate therewith; said wheel including a partially-exposed peripheral edge which is serrated; and said wheel-engaging means comprising a spring member engaging said serrated wheel edge to provide ratcheting detented wheel position retention. ### Claim 9 (depends on 8) A compensator as set forth in claim 8, including: a second wheel-mounted magnet rotationally mounted in said housing adjacent said first-named wheel and magnet for rotation in a substantially parallel plane therewith; said first and second wheel-mounted magnets being disposed side-by-side and coaxially, to form a first pair; and second and third pairs of wheel-mounted magnets mounted in said housing and spaced circumferentially with respect to said CRT from said first pair and from each other. ### Claim 10 (depends on 1) A compensator as set forth in claim 1, wherein: said magnet is mounted in a wheel and rotates coaxially therewith; said wheel includes a partially exposed, serrated marginal edge adapted for grasping; and said retaining means comprises a leaf spring member disposed in said housing at the base of said wheel, said leaf spring member including projecting detent means for mating with and releasably engaging the serrated marginal edge of said wheel. ### Claim 11 A compensator for CRT deflection yokes and the like, comprising: a housing adapted for fixed mounting adjacent a CRT deflection yoke; at least one magnet; a wheel comprising a manually rotatable carrier for said magnet, said wheel including means for carrying said magnet adjacent to and generally in the same plane with said wheel; means for rotatably mounting said wheel and the said magnet carried therewith upon said housing; and means for positively and releasably engaging said wheel to thereby retain said magnet in a selected position of wheel rotation with respect to said housing, to thereby enhance selective positioning of said magnet altering the effective electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display, and to maintain such selected magnet position; said housing being split in a plane generally perpendicular to the axis of said CRT and including two portions between which said wheel is disposed. ### Claim 12 (depends on 11) A compensator as set forth in claim 11, wherein: said housing portions are substantially identical half portions. ### Claim 13 A compensator for CRT deflection yokes and the like, comprising: a housing adapted for fixed mounting adjacent a CRT deflection yoke; at least one magnet; a wheel comprising a manually rotatable carrier for said magnet, said wheel including means for carrying said magnet adjacent to and generally in the same plane with said wheel; means for rotatably mounting said wheel and the said magnet carried therewith upon said housing; and means for positively and releasably engaging said wheel to thereby retain said magnet in a selected position of wheel rotation with respect to said housing, to thereby enhance selective positioning of said magnet altering the effective electromagnetic field produced by the deflection yoke to alleviate distortion in the CRT display, and to maintain such selected magnet position; said housing including mounting means comprising a pair of barbed prongs extending from opposite sides of said housing and molded integrally therewith, said prongs having a shape adapting them to engage portions of said CRT deflection yoke, to thereby retain said housing thereupon. ### Claim 14 (depends on 13) A compensator as set forth in claim 13, wherein: said magnet is mounted in a wheel and rotates generally coaxially therewith; said wheel includes a partially exposed, serrated marginal edge adapted for grasping; and said retaining means comprises a spring member disposed in said housing at the base of said wheel, said spring member including projecting detent means for mating with and releasably engaging the serrated marginal edge of said wheel.