U.S. Philips Corporation

Johannes A Misdom

Dirk J Teuling

A switching device for S correction capacitors includes parallel-arranged branches, each having a series arrangement of an S correction capacitor (Cs) and a switch (S). At one side, the parallel branches are coupled to a horizontal deflection coil (Lh). The switches (S) are controlled by a microcomputer (13) for switching S correction capacitors (Csi) parallel in dependence upon a repetition frequency of horizontal synchronizing pulses (Hs). A hardware frequency detector (11) supplies frequency information (V) related to the horizontal synchronizing pulses (Hs). A frequency change detector (12) coupled to the hardware frequency detector supplies an attention pulse (AP) to an interrupt input (INT) of the microcomputer (13) when a change of the frequency information (V) has been detected.

Switching device for S correction capacitors

An electric voltage generator comprises a transformer (1) having a ferromagnetic core (3), a primary winding (5) and a secondary winding (7). The primary winding (5) includes a first primary coil (31) wound in the form of a solenoid and the secondary winding (7) includes a first secondary coil (33) wound in the form of a solenoid. These coils (31, 33) have the same length, have the same number of turns of wire of the same diameter, and are concentrically disposed on the core (3) in the same axial position. Their winding sense and connection to a primary circuit (9) and a secondary circuit (19), respectively, are chosen so that correspondingly situated ends of these two coils carry alternating voltages of the same polarity in the operating condition. Consequently, correspondingly situated turns of the two coils carry the same alternating voltage and interference signals cannot be transferred via the parasitic capacitance (37) between the primary winding (5) and the secondary winding (7).

Growing community of inventors

Eindhoven, Netherlands

Johannes A Misdom