Patent GB-1007643-A (GB)
Title: A system for setting a plurality of movable elements step by step
Inventor: GRIJSEELS ROBERT ADRIAAN
IPC: G09F11/28
Filed: 1960-10-04
Abstract: 1,007,643. Selective signalling. HOLLANDSE SIGNAALAPPARATEN N.V. Oct. 4, 1961 [Oct. 4, 1960], No. 33996/60. Drawings to Specification. Heading G4H. [Also in Division H4] The invention provides a system for the simultaneous step-by-step setting of a number of movable elements, there being means for indicating whether or not each element is in the correct or desired position, thereby to determine whether or not to step the element further. In the embodiments described the movable elements are display units. Fig. 1 (not shown), comprising endless belts carrying characters which are visible through a window. An electromagnet moves the belt one character at a time under the action of a stepping pulse. The display units are arranged in a matrix as a display board, and there is a number of such boards. As described, a distant transmitter, having data to be displayed on a particular display board at the receiver, transmits a call signal which is characteristic of that board. The receiver, upon recognition of the call signal, determines whether or not the board in question is presently being operated. If it is not, a signal is sent to the transmitter indicating that the board is free, whereupon the transmitter sends data which is stored in a core matrix at the receiver under the control of rapid synchronization pulses sent with the data. The data stored indicates the line of the selected board on which the data is to be displayed and also the characters to be displayed. When all the data relevant to the line has been stored, the signals indicating the line to be selected are read out and used to control relays arranged in a matrix, there being a relay for each line. This selection is done under the control of slow synchronization pulses and connects into circuit all the stepping magnets of the relevant line. Stepping pulses then cause all the magnets to step the display units of the line simultaneously. The belts in the display units are perforated, and there are feelers and associated electric contacts such that each unit produces a position signal indicative of its position. This signal is, if necessary, converted to the same code as the received data. After each stepping operation the position signal from each unit in the line is compared with the corresponding signal from the core matrix. This is controlled by rapid synchronization pulses. If a data signal is identical with the corresponding display units position signal the display unit is indicating the correct character and is taken out of circuit, i.e. it is no longer stepped. However, if inequality is indicated by any unit that unit is stepped again: a comparison cycle follows. This process is repeated until all units are set in their correct positions, whereupon all synchronization pulses cease. Should it be found impossible to obtain equality between the data and position signals an alarm is actuated. In a modification of the system described above a circuit is provided for checking that the correct line selection relay has been chosen. This is done by two diode matrices from which are obtained signals characteristic of the position of the selected relay. These signals are compared with the selecting signals received from the transmitter and now stored in the core matrix. In a further modification a magnetic drum store replaces the core matrix, and the syncronizing pulse generating circuits are replaced by syncronizing pulse tracks on the drum. Specification 1,007,644 is referred to.