| 摘要 |
<p>1323903 Cathode-ray tube circuits LICENTIA PATENT - VERWALTUNGS - GmbH 22 July 1970 [28 July 1969] 35409/70 Heading H4T In an arrangement for correcting corner convergence errors in a multiple beam cathode-ray tube the line scanning coils, comprising two similar portions symmetrically positioned about the tube neck, are connected in parallel and supplied with a convergence correction current in such manner that it is superimposed additively on the scanning current in one portion and subtractively on the scanning current in the other coil. Fig. 3 shows an embodiment in which the scanning coil portions 5, 6 are (effectively) connected in parallel across the windings 7 on the line scan transformer 8 via the centre-tapped secondary winding 9 of a transformer 10. The convergence correction current, comprises a 3 kHz component which is amplitude modulated at frame frequency and effective during line trace periods and a 40 kHz component effective during line fly-back periods and is produced by respective oscillatory circuits which have the primary winding 13 of transformer in common. During line trace periods the inductance of winding 13 is loaded by capacitors 14, 23 and 25, 26 and a resonant circuit (3 kHz) is formed between tapping 15 on winding 16 (also on the line transformer 8) to which a frame frequency sawtooth wave is supplied via amplifier 17 from the frame scan generator 18 and during line fly-back periods the fly-back pulses 21, 22 cutoff diodes 19, 20 thereby removing the capacitors 25, 26 from the resonant circuit which now oscillates at 40 kHz. Because the convergence errors increase from the centre towards the ends of the line scans close coupled windings 27, 28 resonant at 18-20 kHz are connected in series with the coils 5, 6 to "distribute" the correction effect appropriately.</p> |
