The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 08, 1996
Filed:
Jul. 29, 1992
Kenneth G Smith, Eastleigh, GB;
John Beeteson, Romsey, GB;
International Business Machines Corporation., Armonk, NY (US);
Abstract
A display comprising a cathode ray display tube (1) having an electromagnetic deflection yoke (2) is described. A pair of first deflection coils (7,6) are located symmetrically about the longitudinal axis of the tube (1) on opposite sides of the yoke (2) for producing within the tube (1) a first magnetic deflection field. A pair of second deflection coils (8,20) are similarly located symmetrically about the longitudinal axis on opposite sides of the yoke (2) for producing within the tube (1) a second magnetic deflection field at right angles to the first deflection field. The display is further provided with a pair of first cancellation coils (4,3) connected to the first deflection coils (7,6) for producing a first cancellation field which tends to cancel a first stray field produced by the first deflection coils (7,6). Support means (10,11) secure the first cancellation coils symmetrically about the longitudinal axis. The display additionally comprises a pair of second cancellation coils (50,32) coupled to the second deflection coils (8,20) for producing a second cancellation field which tends to cancel a second stray field produced by the second deflection coils (8,20). Further support means (51,52) are provided for positioning the second cancellation coils (50,32) symmetrically about the longitudinal axis in such a way that a plane containing a second cancellation coil (50) is perpendicular to any plane containing a first cancellation coil (4). Preferably, the display also comprises control means (64) for generating a predetermined cancellation current in the second cancellation coils (50,32) in response to a particular second deflection current in the second deflection coils (8,20).