U.S. Philips Corporation

Willem Hendrik Amsen

Wouter Smeulers

Paulus J Hovens

Miloslav Tryzna

In a television picture display device wherein a cathode of a picture display tube is driven by an emitter-follower and a control signal for a beam current reference level control circuit is obtained from the collector circuit of this emitter-follower, measures are taken to compensate for leakage currents from and to the cathode. To this end a blacker-than-black current compensation circuit is provided while furthermore it is ensured that the blacker-than-black curent can be processed by the beam current reference level control circuit.

CRT Beam current control apparatus

A coupling device for adaptation of I.sup.2 L transistors to a transistor operating with a higher bias current setting on a semiconductor body, said coupling device formed in one island from the combination of a current injector and a normally operated vertical transistor.

Device for coupling transistors operated in I.sup.2 L to a transistor

A circuit measures the beam current of a cathode ray tube and derives a control signal from it to prevent overdriving and defocussing of the CRT. The circuit can measure both peak and average values and has an isolation circuit, such as an emitter follower, to prevent loading of the cathode circuit of the CRT.

Television receiver including a beam current limiting circuit

A circuit arrangement in a picture display apparatus including an integrator having a time constant which is of the same order as one field period and which integrates the control voltage generated by the line phase discriminator. The voltage thus integrated is applied by means of a switch to the output terminal of the discriminator during each field blanking period. As a result both the flickering effect and the shift which may occur at the upper edge of the screen of the picture display tube as a result of the broad field synchronizing pulses and the equalizing pulses disappear. The circuit arrangement also includes a circuit which separates the discriminator from the integrator and which may be constituted as a long-tailed pair arrangement.

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Eindhoven, Netherlands

Willem Hendrik Amsen