Patent GB-897260-A (GB)
Title: Improvements in or relating to apparatus for converting an information signal from one form to another
IPC: G09F9/37
Filed: 1960-05-20
Abstract: 897,260. Electric selective signalling systems. GUMPERTZ, D. G. May 20, 1960, No. 17810/60. Class 40 (1). An alphanumeric display device comprises a translucent display screen, a plurality of movable plates, a fixed plate, the movable plates and fixed plate having corresponding uniform patterns of transparent and opaque areas, a source of light, the plates being positioned in parallel relation to each other between the source of light and the display screen with the opaque areas of the plates in alignment with each other, each plate having a modified pattern such that when a plate is shifted relative to the fixed plate by a predetermined amount the light pattern on the screen is modified to correspond to some identifiable alphanumeric character, and means for selectively shifting one of said movable plates, whereby a selected alphanumeric character image is produced on the screen. A visual indicator device is described in which each decimal digit, for example the digit 7, is so represented by transparent and opaque regions on a plate Fig. 2 (A) that when the plate is viewed via a mask Fig. 2 (B) one column out of registration with the digit plate only the chess-board pattern of the mask is visible, but when the digit plate is viewed in registration with the mask the digit becomes visible, Fig. 3. In the indicator the digit plates (one for each digit) are arranged behind each other, Fig. 4, and are normally displaced by one column from a mask 54. To display a selected digit the appropriate plate 62 is displaced so as to be on line with the mask and the digit is projected on to a screen 53. A desired plate is specified by a combination of four electric signals. In a first construction, Fig. 5, the presence of one of these four signals causes an associated shaft 71, 72, 73, 74 to rotate by about a quarter of a revolution. The four shafts 71, 72, 73, 74 are arranged (in a vertical plane as shown) parallel to the edges of the plates and each shaft carries cams so arranged that in the normal positions of the shafts all the plates are displaced leftwards out of line with the mask while for every different combination of input signals (and hence of shaft rotations), one plate is allowed to move rightwards under the action of springs 84 to thereby display a selected digit. In a second construction (Figs. 7 to 12, not shown) each plate carries a pattern of four notches on its bottom edge. For checking purposes, Fig. 14, each plate could carry a metallic strip 214 arranged to close a circuit when the plate is displaced. In a circuit, Fig. 15, for entering three digits units three of the indicators described, the three digits are registered on switches 225, 226, 227 so arranged as to correspondingly mark four leads 230 and the switches are energized in succession, by a control switch 232, to enter the numbers successively into three indicators 12, 13, 14. After entry of the first digit into indicator 12, switch 232 advances to its second contact and the number actually being displayed by the indicator 12, which is represented by markings on leads B, is compared by relays 233, with the number registered on switch 225 and any disagreement causes an alarm to be indicated by a device 250.