Anzeigevorrichtung mit einem leuchtenden Organ, insbesondere Abstimmanzeiger

776,196. Electroluminescence. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Jan. 12, 1955 [Jan. 14, 1954], No. 968/55. Class 39(1). [Also in Group XL(c)] In an electroluminescent indicating device, the area luminescing is a measure of the voltage fed to the device e.g. a tuning indicator. In the example the tuning pointer of a radio receiver comprises a strip 1 of transparent material e.g. class, on the front of which is a thin line 3 of opaque lacquer. On the rear of the strip are thin transparent conducting layers 5, e.g. of tin oxide, a layer of insulating clear resin 7, a luminescent layer 9 e.g. zinc sulphide, a second insulating resin layer 11 and a conductive layer 13, e.g. of silver. The layers, 7, 9, 11 vary continuously in thickness, giving an increase in distance between the electrodes of from 10-100. The voltage applied is derived from a discharge generator controlled by the signal at the receiver, and where the depth of insulator brings the voltage gradient below the threshold value for the phosphor, there is no luminescence. The layers may be of uniform thickness, with a variation in concentration of luminescent material in the layer 9. In a modification the A.C. is applied to a limited area of one conductive layer e.g. at one end, and the frequency is arranged to vary with the amplitude of the supply voltage. In a preferred form, the electrode spacing is a maximum at the centre of the pointer, and a minimum at the ends giving two luminescing surfaces, one on each side of a dark area.