GB1424031A - Cathode ray tubes for multicolour display systems and to such display systems - Google Patents

Abstract

1424031 Colour television FERRANTI Ltd 22 Jan 1974 [13 Jan 1973] 3371/73 Heading H4F A colour display system for producing a display in a plurality, n, of colours (in the embodiment shown n=2: read and green) uses a cathode-ray tube 10 having n cathodes 16, 16<SP>1</SP> producing n electron beams for impingement on a screen 17 having n different coloured phosphors, different levels of E.H.T. voltage supplied from a generator 24 to a contact 23 causing the n electron beams to have energies in different energy ranges to cause light to be emitted from different phosphors, a switch 30 being operated at the end of each line period to consecutively change the E.H.T. voltage fed to contact 23 between n different levels; a switch 27 receiving n colour signals is operated in synchronism with switch 30 and supplies signals to storage means 15 having (n - 1) delay lines 32 having respective delays of 1, 2 ... (n - 1) line periods. The n electron beams thus scan, at any instant, n adjacent lines in the same colour, each line being successively scanned by the n electron beams in the n colours. Switches 28 and 29, ganged with switches 27 and 30, are provided for focusing control means 25 and deflection control means 26. The screen 17 may be formed of superimposed layers of the different phosphors separated by electrically insulating layers or of particles formed of superimposed layers of the different phosphors separated by electrically insulating layers; alternatively particles of the different phosphors coated with different thicknesses of insulating material may be used.