(19)
(11) EP 0 266 154 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.07.1989 Bulletin 1989/29

(43) Date of publication A2:
04.05.1988 Bulletin 1988/18

(21) Application number: 87309433.8

(22) Date of filing: 26.10.1987
(51) International Patent Classification (IPC)4: H01J 29/86, H01J 29/89
(84) Designated Contracting States:
AT BE CH DE ES FR GR IT LI LU NL SE

(30) Priority: 29.10.1986 GB 8625804
04.12.1986 GB 8629007

(71) Applicant: RANK BRIMAR LIMITED
London W2 2EZ (GB)

(72) Inventors:
  • Mead, T. W.
    Hertford (GB)
  • Mumford, Ronald Walter John
    Hitchin Herts (GB)

(74) Representative: Smith, Janet Frances et al
Beresford & Co. 2-5 Warwick Court High Holborn
London WC1R 5DJ
London WC1R 5DJ (GB)


(56) References cited: : 
   
       


    (54) Improvements in cathode ray tubes


    (57) A face plate for a cathode ray tube comprises a plate (50) of transparent material, the thickness of which, relative to its transverse dimension is such that at least some of the light entering it at any point on one of its transverse surfaces (54), and internally reflected within the plate (50), is incident on the edge surface (58) of the plate before striking the surface (54) where it entered again. The edge surface (58) diverges away from the transverse surface (54) so that any light directly incident on it is reflected into a peripheral area of the opposite transverse surface (52) of the plate (50). The plate (50) may, for example, be frusto-conical or may have a plurality of triangular-section grooves (80) formed in its edge surface (78) (see Figure 6).







    Search report