U.S. Philips Corporation

Gerrit Bosch

Albertus A Sluyterman

Tjebbe R Pasma

Fransiscus M Doomernik

Adriaan J Groothoff

Harmen Giethoorn

Arnoldus W Kok

Steven M Wielink

A picture display device having a display tube and a deflection unit comprising a field deflection coil and a line deflection coil is disclosed. To comply with a predetermined interference radiation standard, the picture display device is provided with one interference suppression coil or with a system of interference suppression coils, which interference supression coil or system of interference suppression coils is oriented and can be energized in such a manner that, measured at a predetermined distance from the picture display device, the strength of the local magnetic dipole field is below a desired standard.

Picture display device with interference suppression means

Picture display device having a display tube (3) and a deflection unit (9) comprising a field deflection coil and a line deflection coil (11). To comply with a predetermined interference radiation standard, the picture display device comprises a first set of (horizontal) interference suppression coils 18, 19 arranged symmetrically relative to the plane of symmetry of the line deflection coil and a second set of (vertical) interference suppression coils 18a, 19a arranged at right angles to the plane of symmetry of the line deflection coil, which coils are oriented in such manner and in operation are energizable in such manner that, measured at a predetermined distance from the picture display device, at least the strength of the local magnetic dipole field is below a desired standard. Each coil of the second set preferably comprises at least two sub-coils arranged parallel to each other at a given distance in order to reduce the energy content of the coil system.

Picture display device having means for compensating line stray fields

Picture display device having a display tube and a deflection unit comprising a field deflection coil and a line deflection coil. To comply with a predetermined interference radiation standard, the picture display device is provided with one interference suppression coil or system of interference suppression coils is orientated and can be energized in such a manner that, measured at a predetermined distance from the picture display device, the strength of the dipole component is below a desired standard.

Picture display device having a display tube and a deflection unit (9) comprising a field deflection coil and a line deflection coil (11). In order to comply with a predetermined interference radiation standard, the picture display device is provided with a compensation coil system having a first set of compensation coils (18, 19) for generating a dipole compensation field and possibly a second set of compensation coils (18a, 19a) for generating a fourpole compensation field, the compensation coil system being preferably arranged in series with the line deflection coil 11 ) and being provided with electric means (R; R.sub.1 ; R.sub.2 ; R.sub.3 ; R.sub.4) to shift the phase of the current through at least a part of the compensation coil system with respect to the phase of the current through the line deflection coil.

Picture display device with stray field compensation means

A method of manufacturing a plate-shaped permanent magnet (7) which is to be arranged in an air gap of a core (1) for a transformer or choke coil and which consists of a number of permanent magnetic portions (29) which are made of a metal alloy having a high magnetic remanence and which are magnetized perpendicularly to the plane of the plate. A plate (11) of the alloy is fixed between two insulating foils (13, 15) after which this assembly is arranged on a flat backing (17) and is rolled in two mutually perpendicular directions (25, 27) by means of a cylinder (19) whose outer surface is provided with grooves (23). The plate (11) is thus very simply fractured to form a very large number of portions (29).

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Eindhoven, Netherlands

Gerrit Bosch