| 摘要 |
1,224,862. Colour television. A. LIEBSCHER. 17 Jan., 1969, No. 2883/69. Heading H4F. [Also in Division H1] The invention relates to a colour television tube for the simultaneous display of a number of colour signals without the need for a shadow mask. As shown, the tube comprises a means for generating three electron beams R, G, B, which are modulated at grids 3, 4 and 5 by signals representing the red, green and blue components of an image. The beams then pass through apertures in a plate 19, which serve to define the beam width, and on to a screen 11 via accelerating anodes 6 and 10 and beamdeflecting means 8 and 9. The screen comprises a number of strips of colour phosphors, alternating red, green and blue, at right angles to the direction of horizontal scan. Between each set of three colour strips a fourth non- luminous conductive strip 11a is placed, all such strips 11a being connected together and fed to a phase detector 18. The phase of the feedback pulses obtained when the electron beams scan the screen is compared with the phase of the third harmonic of a subcarrier oscillator 14. The resultant output of detector 18 is used to synchronize a 10À7 Mc/s. sawtooth generator 16 which applies a deflecting voltage to plates 8 for simultaneous horizontal deflection of the three beams. The coil 9 is provided with a raster deflection signal to control both horizontal and vertical deflection of the beams, the resultant of the deflections provided by plates 8 and coil 9 providing a simultaneous stepped horizontal deflection of the beams. The phase of subcarrier oscillator 14 is locked to the phase of the incoming colour subcarrier. In a modification (not shown), the striped colour phosphor screen is replaced by a uniform white phosphor screen which produces three white light beams corresponding to the three electron beams R, G, B and these light beams are projected on to: (1) a striped colour filter corresponding to the colour phosphor strrips described above or (2) a corresponding striped colour screen, the beam indexing signals being produced by an infra-red photo-electric detector responsive to thermal radiation produced when the light beams scan across indexing strips located between adjacent sets of three colour strips. |
