The Rank Organisation Plc

Strand Lighting Limited

John Wright

David R Bertenshaw

John D Millward

Edwin P Lockwood

Richard Williamson

In a lighting power controller having a controllable switch (such as a thyristor), in order to compensate for perturbations in the mains supply waveform, the waveform is analyzed and a table is set up of thyristor firing angle against output RMS voltage. To obtain a desired output RMS voltage, the thyristor is fired at the angle indicated by the table.

Electric lighting and power controllers therefor

An electrical unit such as a lighting dimmer pack incorporating one or more semi-conducting switching devices such as triacs or thyristors, wherein the usual insulated mounting base (18) of the triac (30) is in turn mounted on the unit casing via an electrically insulating heat conductor, and the said mounting base is connected to the phase or neutral conductor (52), preferably the latter. In a preferred arrangement, a plurality of triacs are clamped by a printed circuit board which provides the connection from the triac bases to the neutral conductor.

Interference suppression for semi-conducting switching devices

The invention is concerned with a means of compensating for film shrinkage in a continuous film motion telecine apparatus. A measure of the film shrinkage is obtained by deriving a signal representing the angular speed of a roller in non-slipping contact with the film, the film being driven at a constant frame rate by, for example, a smooth capstan servo-controlled to maintain the constant frame rate. The roller whose angular speed is measured may be the drive capstan itself or a separate roller. The signal so derived is dependent on the film shrinkage and thus is used to automatically control a registration adjusting means to compensate for such shrinkage.

Growing community of inventors

Barnes, United Kingdom

John Wright