Gec Avionics Limited

Elliott Brothers (london) Limited

Martin W Redfern

Peter Chapman

A cathode ray tube (CRT) display arrangement including protection means for protecting the screen of the CRT (1) against excessive heating, by the electron beam, e.g. due to failure of the beam deflection drive circuits (5), the protection means comprising an electronic storage means (27 to 41) having storage locations in which are stored values indicative of the temperature at different locations on the CRT screen, and means (7) for controlling the electron beam current in dependence on the contents of the storage means.

Cathode ray tube display arrangements

A linear high power amplifier suitable for low voltage operation comprising a push-pull output stage (Q1, Q2) arranged to control the voltage supplied to a load (Z.sub.L) in dependence on an input signal (V.sub.IN) applied to the amplifier. Means (L.sub.S, S) is provided for separately supplying to said load (.sub.Z L) a current (I.sub.S) which changes at a rate faster than the maximum rate of change of current (I.sub.L) in the load (Z.sub.L) required by the input signal (V.sub.IN) thereby to produce a corresponding change in the current (I.sub.A) required to be supplied by the output stage (Q1, Q2) to the load (Z.sub.L) in order to maintain the voltage across the load (Z.sub.L) at the value required by said input signal (V.sub.IN). Switching means (Q3, Q4, C) operated in dependence on the value of the current (I.sub.A) supplied to the load (Z.sub.L) by the output stage (Q1, Q2) causes the sense in which said changing current (I.sub.S) changes to reverse when said current (I.sub.A) supplied by said output stage (Q1, Q2) exceeds a predetermined positive value (I.sub.AP) or a predetermined negative value (I.sub.AN) which predetermined values are less than the total current (I.sub.L) required by the input signal (V.sub.IN) to be supplied to the load (Z.sub.L), thereby to restrict the current (I.sub.A) supplied to the load (Z.sub.L) by the output stage (Q1, Q2) to values between said predetermined values (I.sub.AP, I.sub.AN).

Electric signal amplifiers

A circuit for driving a deflection coil comprising a capacitor (3) in series with the coil (2), a circuit (1) which drives a saw-tooth waveform current through the coil and capacitor, and a switchable resonant circuit (5, 6, 7, 8, 9) which generates across the capacitor a saw-tooth waveform voltage equal and opposite to the voltage drop attributable to a resistive component (4) of the capacitor/coil series circuit, thereby to effect loss correction.

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Maidstone, United Kingdom

Martin W Redfern