GB1138820A - Multi-coloured illuminated display means - Google Patents

Abstract

1,138,820. Illuminated displays in colour. CLARKE CHAPMAN & CO. Ltd. 27 Nov., 1967 [28 Nov., 1966], No. 53144/66. Heading G5C. Monogrammic display means comprises for each colour to be displayed: a plurality of light sensitive means (e.g. photo-resistors 4(1), 4(2) ..., Fig. 1); an equal number of lamp bulbs 14 of that colour; a pair of switching devices 12 connected in back-to-back relationship in series with each lamp bulb and a source (a) of alternating voltage, Fig. 2; pulse generating means 11 to switch on in alternating sequence the switching means 12 of each pair; and means for controlling the brilliance of each lamp 14 in proportion to the light energy falling on its corresponding light sensitive means, by determining at what point in each half-cycle of the A.C. source (a) the switching means 12 is activated by the pulse generator 11. As described, the device is controlled either by projectors (18) one for each colour, each of which shines a light image on to a screen (17) covered with an array of light sensitive means corresponding in spatial configuration to the display lamps, Fig. 4 (not shown); or by a single projector (18), the screen (17) being covered by an array of groups of light sensitive means (4) each member of the group having a different colour filter in front of it, Fig. 5 (not shown). Fig. 1 illustrates a first control circuit. A plurality of bridge arms are connected across the A.C. source (a). Point e on the first bridge presents a reference voltage; its level may be determined by varying resistor 2, e.g. resistor 2 may be sensitive to the ambient light. The voltages at points f, g, h ... on the other bridges are determined by the intensity of light falling on photoresistors 4(1), 4(2), 4(3) . . . The devices 10 are measuring amplifiers; according to the " error voltage " received, e.g. the difference between voltages e and f, so the time taken to charge up a capacitor (not shown) varies and so the exact instant of pulse generation by the device 11 varies, hence controlling the brightness of lamp 14. In a second control circuit, Fig. 3, the device 13 is a D.C. generator having a light-sensitive component, e.g. a photo-diode or -transistor. Reference has been directed by the Comptroller to Specification 1,052,372.