U.S. Philips Corporation

Jacob Koorneef

Robert H Fastenau

Johannes T Klomp

Johannes T Van Roosmalen

Paulus J Van Der Heijden

Antonius J Der Kinderen

Matthijs J Baan Hofman

A method of manufacturing a color display tube having a magnetic quadrupole post-focusing mask, in which the mask is magnetized by magnetic field shaping means of soft iron, or the magnetic equivalent, having raised portions, for example strips placed against opposite sides of the mask sheet and subjected to an external strong magnetic field by an electromagnet to induce magnetic poles through the thickness of the mask sheet. The geometric arrangement of the raised portions of the field shaping means is such that cyclically a north pole, a south pole, a north pole and a south pole are induced into the sheet material surrounding each aperture. Using this technique, the entire area of a mask sheet can be magnetized in one operation. Also masks for small tubes and high definition tubes can be made.

Method of manufacturing a color display tube having a magnetic

In a method of manufacturing a color cathode-ray tube comprising a magnetic quadrupole post-focusing mask (7) the mask (7) is formed by a plate of permanent magnetizable material in which apertures (9) are provided arranged according to rows. Sections of the plate are successively magnetized by positioning parallel conductors (21, 22, 23) on at least one side of the plate in such manner that each time two conductors through which an electric current flows in opposite directions are situated between two rows of apertures (9) and a magnetic quadrupole is formed along the circumference of each of the apertures (9). A number of outermost conductors (30, 31, 32, 33) determines an edge area of the section. In order to prevent the occurrence of disturbing magnetization errors in the edge area, the edge area is made to coincide with a part of a preceding section already magnetized according to the desired strength. A magnetic induction is generated in the edge area according to a pattern corresponding to the existing pattern in the preceding section but having a strength which decreases towards the outermost conductor (30 ).

Method of manufacturing a color cathode-ray tube comprising a magnetic

An apparatus for fabricating a quadrupole shadow mask includes a reel for storing a web of insulating material having a conductive layer on one side thereof, a reel for storing a long metal strip having a plurality of spaced apertures arranged in parallel rows, means for cutting the web into strips and a roller having circumferential grooves for positioning and then pressing the insulating strips onto the surface of the metal strip between the rows. The resulting strip is guided through a heating device and then is cut into sheets of predetermined length.

Apparatus for manufacturing a color display tube

A method of manufacturing a color display tube of the refocusing type in which supports of insulation material are secured against an apertured metal plate. The supports are provided with a conductor at least on the side remote from the plate, so that the plate constitutes a first set of lens electrodes and the conductors constitute a second set of lens electrodes. The two sets of lens electrodes form a quadrupole lens in each aperture in the metal plate when a voltage difference is applied between the first set and the second set. The defocusing direction of the quadrupole lens is parallel to the phosphor strips of the display screen.

Method of manufacturing a color display tube shadow mask

A color display tube having a quadrupole post-focusing electrode consisting of two crossing sets of parallel conductors, the first set of conductors consisting of wires and the second set of conductors consisting of metal stripes secured pairwise against each other and clamping the wires at the crossings, said wires being surrounded coaxially at the area of the crossings by a layer of insulation material, has the advantage that already at a comparatively low focusing voltage between the sets of conductors a sufficiently strong focusing influence is exerted on the electron beams.

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Eindhoven, Netherlands

Jacob Koorneef