Circuit arrangement in a color television receiver with a color characteristic signal in order to achieve a stoe of the bearings, free change in color

摘要

1,063,033. Colour television. HITACHI SEISAKUSHO KABUSHIKI KAISHA. April 10, 1964 [April 18, 1963], No. 14967/64. Heading H4F. In a beam-indexing cathode-ray tube the beam indexing signal delay time, that is, the time interval from the instant of detection of the indexing signal due to secondary electrons to the instant when a primary-electron beam which is colour-switch controlled by the indexing signal reaches the phosphor screen, is caused to be equal to an integral number of either line periods or frame periods which is equivalent to the beam indexing signal delay time #g being zero. This causes any phase errors due to variations in the horizontal scanning speed to be reduced and also makes it possible to control the colour-switching circuit during the period of time #g. e.g. 8 micro-seconds, immediately after the start of horizontal deflection of the scanning beam. As shown in Fig. 2 the chrominance signal obtained from the colour-switching circuit 15 (5À5 Mc/sec.) passes to a picture signal amplifier and a pilot carrier oscillator 14 (34 Me/sec) and the chrominance signal is applied to the cathode 4 and the pilot signal to the grid 5 and also to a frequency converter 17. The modulated indexing signal detected from the secondary electron emissive electrode is passed through a side-band amplifier 16, frequency converter 17, an indexing signal amplifier 18, a frequency divider 19, a variable delay element 23 and a fixed delay element 24 and then applied to the colour-switching circuit 15. The sum of the delay time due to the delay element 23 (e.g. variable range of 0À2 micro-second) and due to the delay element 24 (e.g. 60 microseconds) is selected so that it is equal to the difference between the delay time #g of the remainder of the circuit and one line period. To reduce any fluctuation of the delay time of element 24 due to factors such as temperature one portion of the output from the delay element 24 is passed through a delay element 25 having a delay time equal to #g and then phase compared with the input to be applied to the delay element 23 by a phase difference detector 26 which corrects the delay time produced by the variable delay element 23 thereby to cause the indexing signal delay time to coincide with one line period. The Specification includes a description of a known beam-indexing cathode-ray tube having three secondary electron emissive indexing strips for every two phosphor triplets (Fig. 1, not shown).