Colour picture projection system - has three CRTs, one for each primary colour, with focussing lens before each phosphor screen

摘要

The projection system has a projection screen (20) and three CRTs (11-13) for forming a colour picture on the screen, each projecting one of the three primary colours. Their phosphor screens (11a- 13a) face the centre (20c) of the projection screen (20), and are at the same distance (H) from it (20c). They are in line with each other, parallel to the vertical scanning direction of the light beams. A focussing lens (14-16) is provided in front of each phosphor screen, between the projection screen (20) and the corresponding CRT. The three principal planes (14a- 16a) of the lenses (14-16) face the centre of the projection screen (20), and are at the same distance from it.