U.S. Philips Corporation

Dirk J A Teuling

Hendrik Ten Pierick

Friedrich E Hahn

Johannes A C Misdom

Roger P H Kennis

Johannes L M Verhees

Franky M M E Vaneerdewegh

Gianlorenzo Paoletti

John H P Moors

In a driving circuit ( ) for a semiconductor switching element ( ), a storage time (Ts) of the semiconductor switching element ( ) is measured ( ) to control the semiconductor switching element ( ) such that the storage time (Ts) is kept substantially constant.

Driving circuit for a semiconductor switching element

A deflection circuit includes a deflection correction circuit (Vs) with a controllable active voltage source (Vs) arranged in a loop formed by a deflection coil (Ld), an S-capacitor (Cs), and a flyback capacitor (Cf). The voltage source (Vs) receives a further power supply voltage (Vb,) and a modulating signal (M) to supply a modulating voltage (Vm) varying in response to the modulating signal (M). The active voltage source (Vs) includes a switching element (S,) which is switched on and off with a frequency which is substantially higher than the deflection frequency to to enable waveforms of the modulating voltage (Vm) with a frequency content which is substantially higher than the deflection frequency such that any desired waveform can be generated within the deflection period (Td).

Deflection correction

The cut-off level (Vcod) of a drive signal (Vd) of a cathode ray tube (,) is (Ib,, Ib,) occurring at these two levels (Vd,, Vd,).

Cut-off level setting

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Eindhoven, Netherlands

Dirk J A Teuling