| 摘要 |
1,224,902. Colour television. SONY CORP. 10 June, 1968 [10 June, 1967], No. 27482/68. Heading H4F. A filter 27 (Fig. 8) and a screen 8 combine to form images of an object O on a photo-conductive screen 2 of an image pick-up tube 3 in such a way that the images comprise a series of coloured areas corresponding to the various colour components of the light from the object, resulting in the production of a chrominance signal comprising component colour signals all included within the same frequency band. Means are also provided for forming index images on the photo-conductive screen 2 and for deriving therefrom amplitude-modulated index signals indicative of the position of the colour components in the chrominance signal, which signals have a frequency band different from that of the chrominance signal. In the embodiment shown the filter 27 comprises an array 27a (Fig. 6) of parallel red, green and blue stripes perpendicular to the line-scanning direction of the tube 3, and the screen 8 comprises a series of spaced cylindrical lenses parallel to these stripes, producing on the photo-conductive screen 2 a series of images of the object O divided into separate colour components. The spaces in the screen between the lenses provide a series of panchromatic images superimposed upon the colour stripes from which images luminance signal is derived. A portion 27c of the filter 27 provides the necessary colour correction for this signal. The index image is formed by a portion 27b of the filter 27, in which transparent areas 27w, 27W produce images on the screen 2 which respectively give rise to the amplitude-modulated index signal and a constant D.C. level superimposed upon this signal. In another embodiment the index signal is amplitude-modulated by a square wave by the provision of a different pattern of transparent areas in the portion (47b), Fig. 9 (not shown), of the filter (47). The composite colour video signal from the pick-up tube 3, Fig. 8, is amplified by a video amplifier 12 and passes to a low-pass filter 13 which selects the luminance signal for frequency correction by a circuit 16 and delay by a delay line 17, to a band pass filter 15 which selects the chrominance signal and applies it to synchronized demodulator circuits 19R, 19G, 19B, and to a band-pass filter 14 which selects the amplitude-modulated index signal. The index signal passes to a demodulator circuit 20 to select the envelope of the index signal, a band-pass filter 21, amplitude limiting means 22, frequency multiplying means 23 to triple the index signal frequency and a phaseshifting circuit 24 to provide three carrier signals of differing phase for application to the respective demodulator circuits 19R, 19G, 19B. Colour difference signals are then obtained at terminals 18R, 18G, 18B, the luminance signal being obtained at terminal 18Y. |
