| 摘要 |
<p>S01237 S79P109 BEAM INDEX COLOR TELEVISION RECEIVER APPARATUS In a beam index color television receiver of the type having a cathode ray tube which is provided with beam-excitable color elements and index elements disposed on a display screen of the cathode ray tube and which are scanned by an electron beam; color switching is controlled by an index signal generator, comprised of a photo-detector and band-pass filter, for generating a periodic index signal as the index elements are scanned by the beam, color gates which sequentially gate respective color control signals individually to modulate the electron beam as the beam scans the color elements, a gating signal circuit including a phase-locked loop which generates sequential gating signals at a frequency synchronized with the frequency of the periodic index signal and a gate pulse generator which supplies the gating signals in sequence to the color gates to control the latter so as to gate the respective color control signals, and a phase-controlling circuit for imparting a phase shift to the gating signals supplied to the gating pulse generator to compensate for an inherent time delay caused by the photo-detector, band-pass filter and phaselocked loop. Such phase shift may be imparted by a phase shifter connected between the phase-locked loop and the gate pulse generator or at a voltage controlled oscillator in the phase-locked loop itself. -i-</p> |
