| 摘要 |
679,124. Television receivers. PHILIPS ELECTRICAL, Ltd. July 6, 1949 [July 9, 1948], No. 17873/49. Class 40 (iii). A circuit for centring the beam of a cathoderay tube employing magnetic deflection, comprises two equal resistors 7 and 8, arranged in parallel with a further resistor 9 having an adjustable tapping thereon, the deflecting coil 10 and transformer 4 supplying saw-tooth deflection current being arranged in series between this tapping point and the common point of resistors 7 and 8. A direct current i is fed through the network 7, 8, 9. The resistors 7, 8, 9 are each made small compared to the resistances of coil 10, e.g. resistors 7, 8 and 9 may each have a value of 20 ohms while that of the coil may be 80 ohms. In this event the impedance of the circuit supplied by transformer 4 varies only slightly over the whole range of control by resistor 9. The Specification as open to inspection under Sect. 91 describes a circuit illustrated in Fig. 1 (Cancelled), and used for beam-centring in conjunction with the line-deflection coil 5. In this arrangement, the controlling circuit is shortcircuited to alternating current by condenser 6 to reduce changes in input impedance of the circuit with respect to transformer 4 due to movement of the slider 3. This arrangement would require an excessively large condenser for centring if it were used in conjunction with the frame-deflection circuits. This subject-matter does not appear in the Specification as accepted. |
