摘要:
An electroluminescent apparatus produces an area of light on an indicator surface, the position of which is controllably variable with respect to one co-ordinate of a system of co-ordinates defining points on the surface, the other coordinate appropriate to position of the area having a constant value. As shown Fig. 1 a wedged-shaped electroluminescent capacitor 1 is bounded by conductive surfaces 9 10 which have a voltage from a source 2 applied to them. Disposed adjacent the light transparent conductor 9 is a set of pairs of similar light-sensitive resistors 3, 3a, the mid-points 4 of which are each connected to an electroluminescent capacitor 5. Upon excitation of the capacitor 1, which may contain a polaristor layer, light is emitted from the phosphor from the narrow end up to a certain point, the adjacent capacitor 5 to this point being excited due to its associated resistors 3, 3a receiving differing incident light intensities. In an alternative method of obtaining a variation of the field intensity, one of the conductive surfaces is made resistive and disposed parallel to the other surface. The light output from the second electroluminescent capacitor may be viewed directly or allowed to fall on one of a set of photo-conductive elements so as to alter the potential of a conductor attached to one side of the element. In using the apparatus for television pick-up or display apparatus, a plurality of parallel conductors are each associated with a photoconductive element, and are disposed at right angles to a similar set of conductors, thus forming a cartesian coordinate system, a further electroluminescent layer being interposed between the sets. In voltage measuring apparatus, a scale may be provided along the set of capacitors 5 of Fig. 1, and the voltage of the source 2 directly read off. Alternatively, the voltage measured may be displayed on a digital display device consisting of a number of electroluminescent strips, the energizing of which is controlled by connecting each to a photo-conductive strip which is illuminated through an apertured mask by the spot of light produced in the second set of electroluminescent capacitors. The apparatus may be used to convert an infra-red or an X-ray image into a visible image. Copper activated zinc sulphide or copper activated cadmium selenide embedded in an epoxy resin may be used as the electroluminescent phosphor.