GB1225745A - - Google Patents

Abstract

1,225,745. Symbol display system. SYSTEMES ET PERIPHERIQUES ASSOCIES AUX CALCULATEURS. 24 Jan., 1969 [25 Jan., 1968], No. 4238/69. Heading H4F. A symbol (e.g. alpha-numeric) display system comprises a mask carrying transparencies of different symbols arranged in the form of a raster i.e. in lines and columns, one or more electroluminescent sources which illuminate the mask, and one or more matrices of photo-electric detectors, the detectors of each matrix being arranged in the form of a raster to correspond to a field to be scanned, and a selected symbol being projected on a, or the, matrix from which a video signal in binary form corresponding to the selected symbol is derived for display on a cathode ray tube. The product of the number of sources and matrices is equal to the total number of symbols carried by the mask. In one embodiment, Fig. 5 (not shown), there is provided a column of electro-luminescent sources equal to the number of lines of the mask each illuminating a single line of symbols on the mask, and a line of matrices equal to the number of columns on the mask, the arrangement being such that the symbols on a line of the mask are projected on the line of matrices, and a single symbol is selected by selecting one of the matrices. The mask may be of cylindrical form, for each symbol an objective mounted on a cylindrical support being provided (compound lenticular optics), the axes of the two cylinders being coincident with the line of matrices, Fig. 8 (not shown). In this embodiment adjacent symbols on the mask are spaced apart to overcome optical projection errors. In a further embodiment, Fig. 9 (not shown), a plurality of sources corresponding to the number of symbols are each associated with a respective lenslet of a compound lenticular plate, and a second similar compound lenticular plate is associated with the mask, the selected illuminated symbol being projected by means of an objective lens on to a single matrix. To derive the video signal a line of the matrix is transferred, in parallel, to a register from which the binary signals are read out serially in the desired order for display. To vary the size of the symbol alternate lines or columns may be suppressed or repeated. The Specification includes a detailed explanation of logic and timing means for selecting the desired symbol together with its sequence and position of display in accordance to information derived for example from a computer. Interlaced, spiral or circular scanning may be employed.