U.S. Philips Corporation

Jan Van Der Waal

Johannes M Compen

Adrianus J Van Denderen

Mathias A Peters

Gerard Vermeulen

Marianus A Van De Kerkhof

A color cathode ray tube having a shadow mask comprising columns of vertically elongate apertures separated by bridges. In order to obtain smooth north and south edges to the cathodoluminescent screen and the desired mask transmission, at least some of the apertures which terminate at the top and bottom mask edges are longer and narrower than the adjacent apertures in the same column. These longer, narrower apertures are provided in those cases where normal width apertures would have been excessively foreshortened by the mask edge, for example their lengths are less than their widths, and where columns would have terminated in a bridge or a part thereof.

Color cathode ray tube having shadow mask with some long, narrow

A method of producing a color picture tube screen particularly for a high definition tube. In producing a high definition screen light from a point source (S) is directed through a segmented lens (18) and a shadow mask (24) onto a layer of photoresist applied to the internal surface of a faceplate panel (12). The segmented lens (18) comprises a rectilinear array of differently inclined facets (F). In order to obtain a substantially uniform illumination of the faceplate panel (12), the segmented lens (18) is wobbled in an oblique direction such that in moving from one extreme position to another, the image of a facet on the panel occupies substantially the previous position of the image of another facet obliquely adjacent the first mentioned facet when at the one extreme position.

Method of producing a color picture tube screen

The invention relates to a color display tube having a shadow mask (12) positioned in front of a display screen (8). The shadow mask (12) is coated at least on the side remote from the display screen with a heavy metal layer (14) of selectively varied thickness. The heavy metal has an atomic number exceeding 70 and has a high electron reflection coefficient, thus minimizing energy absorbed by the shadow mask from electrons impinging on the mask. Because of the selectively-varied thickness of the layer, reflection of electrons intercepted by the mask toward the screen is minimized without sacrificing the reduction in thermal expansion of the mask afforded by such a reflective layer.

Color display tube having heavy metal coating on color selection

A method of manufacturing a pair of associated reproduction masks for manufacturing shadow masks for display tubes. In order to obtain elongate apertures which are enlarged in width on the side of the mask facing the screen, the second reproduction mask is formed by reproducing the first reproduction mask on a photographic plate by means of light rays which have a substantially greater divergence in a plane perpendicular to the long dimension of the apertures than in the plane parallel thereto.

Method of manufacturing reproduction masks for producing a pattern of

A method of drape drawing a shadow mask from a foraminous, or apertured, metal sheet that has a greater tensile in one direction than another and has edges extending in the one direction. During the drape procedure, the edges of the sheet that extend substantially in the direction in which the sheet has the greater tensile strength are allowed to slip relative to the draw ring and the pressure. As a result of this, the sheet is prevented from tearing.

Method of drawing a shadow mask

In a color CRT, the mislanding of electron beams due to thermal effects in the shadow mask is compensated for by means of an electron-absorbing insulating layer on the display screen, which layer has apertures which are in registration with the luminescent regions of the display screen.

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Eindhoven, Netherlands

Jan Van Der Waal