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Luminescent screen of a color television tube
| Details |
Inventors: Duinker, Hans Dignus; Vermeulen, Gerardus Antonius Wilhelmus;
Assignee: U.S. Philips Corporation (New York, NY)
Primary Examiner: Husack; Ralph
Assistant Examiner:
Attorney, Agent or Firm: Trifari; Frank R., Berka; George B.
A method of manufacturing a luminescent screen of a shadow mask color tube. The phosphor dots on the screen which are separated by a light-absorbing material are smaller than the apertures in the shadow mask. The light-absorbing layer is first provided on the window and the luminescent materials are then provided successively. The inner surface of the window is such that undulations having a spatial frequency from 5 to 50 cm.sup.-.sup.1 or, in other words, wavelengths between 0.2 cm and 0.02 cm, show a depth of less than 1 micron. |
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DETAILED DESCRIPTION What is claimed is: 1.
A cathode-ray tube for displaying color pictures, comprising: a transparent window having an undulated inner surface including undulations with a wavelength between 0.
2 and 0.
02 cm; a luminescent screen provided on said inner surface and including a plurality of luminescent areas which upon excitation by electrons luminesce in different colors, said areas being separated by light absorbing material, a shadow mask having a plurality of apertures, said apertures exceeding at least one dimension of assigned luminescent areas, said surface undulations with wavelengths between 0.
2 cm and 0.
02 cm having a depth less than 1 micron.
Description:
The invention relates to a method of manufacturing a luminescent screen of a cathode-ray tube for displaying colour pictures, comprising a shadow mask having a multitude of apertures, said luminescent screen comprising, in a multitude of separate areas, materials which upon excitation by electrons luminesce in different colors, said areas being separated by a light-absorbing material, the apertures in the shadow mask being larger than the effective areas of the luminescent materials, an apertured layer of the light-absorbing material being first provided on the window of the cathode-ray tube while using a photo-sensitive lacquer, the materials which upon excitation by electrons luminesce in different colours being then provided successively.
The invention is further relative to a cathode-ray tube with a screen manufactured by this method.
A luminescent screen in which the surfaces of the luminescent materials are separated by a light-absorbing material has the advantage that, with the contrast remaining the same, the tinting of the window glass may be omitted or may at least be less.
As a result of this the observed brightness of the picture increases.
Since furthermore the apertures in the shadow mask are larger than the surfaces of the luminescent material, the electron spots are larger than the surfaces of the luminescent materials during operation of the tube with the same potential of the mask and the screen
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