Patent GB-725808-A (GB)
Title: Display indicator and control system
IPC: G05D3/12
Filed: 1953-01-23
Abstract: 725,808. Electric selective signalling systems. WESTINGHOUSE AIR BRAKE CO. Jan. 23, 1953 [Jan. 24, 1952], No. 2065/53. Class 40 (1). An electro-mechanical display indicator is operable to any one of an integral number of positions by an electric motor which drives two sprocket wheels of slightly different size geared to a belt containing the indications, wherein electrical contact fingers can be connected in various combinations by arcuate wipers driven by each sprocket wheel and are associated with the motor energizing circuit so that for each combination of positive or zero potential applied to the contact fingers the motor willl be energized to drive the sprocket wheels into only one possible unenergized rest position. In one embodiment only one sprocket wheel is used, with a plurality of radial contact fingers inter-connected in specific combinations according to the position of a central, shaped, arcuate wiper which can be located in any one of 2<SP>n</SP> positions, where n is the number of contact fingers. Indicator as receiver. As shown (Fig. 1A) two sprocket wheels 10, 11 carry a notched belt 12 whose surface is divided into twelve symbol spaces of equal length, one of which is visible through a window in the housing. The circumference of wheel 10 is equal to three symbol spaces, and that of wheel 11 is equal to four symbol spaces. The wheel 10 is driven by a motor 14, and wheel 11 carries on its shaft a cam 16 and spring biased roller 17 to maintain alignment between a selected symbol and the window. Each wheel carries circuit controllers comprising an outer ring 18, 19 associated with brushes 20, 21 connected to one terminal of the motor 14, arcuate wipers 22, 23 associated with fingers 24, 25 connected to the other side of the motor via a battery and switch S, and two fingers connected via leads A, B, C, D to a four element binary code signal, so that the energization circuit of the motor is dependent on the binary code signal and the position of the wipers 22, 23 and the motor will rotate and drive the wheels 10, 11 and belt 12 to the one only position in which the motor energization circuit is broken. The binary code signal may be applied to leads A, B, C, D by the selective operation of four relays, thereby applying a positive or zero potential to the individual leads. The number of symbols to be indicated by the apparatus may be increased by supplying each wheel with three fingers to give a six-element binary code with 64 possible different symbols, and/or increasing the number of symbol spaces in each wheel circumference. In an embodiment using only one sprocket wheel (Fig. 5), the arcuate wiper is so shaped for cooperation with four contact fingers to give 16 positive combinations, each of which allows the display of a different symbol by a belt driven by the sprocket wheel. Indicator as transmitter. In the rest position the leads A, B, C, D have the same potential at both ends, and after disconnection from the previous signal source and from the motor supply source, the indicator may be used as a transmitter by connection to the control leads of further indicators, or the coded signal may cause relays AR2 &c. (Fig. 4) to be selectively energized to light a lamp with the symbol corresponding to the indicator position. Combined receiver and transmitter. A plurality of indicators in columns and rows having four control leads A, B, C, D may be assembled in a display panel and interconnected as shown in Fig. 9, so that any individual indicator e.g. K1-1 may be actuated by the operation of the appropriate connector relay C1-1, from four bus-wires which may be energized from control relays AR1 -1 1 &c. by energization of relay C5-1. The signal on the bus-wires may be indicated on a lamp bank by connecting relays AR2 &c. by operating switches S6-1 to energize relay C6-1. The appropriate row is selected by a switch RS, energizing relays Rl etc., completing the motor circuits of each row at a time. Thus, to enable the first row of indicators to show the code signal stored in control relays AR1-1 to DR1-1, AR1-2 to DR1-2, &c. rotary switch SS in position 6 operates relays C5-1, C5-2, etc., to connect the control relays to the vertical bus-wires of each column, and switch RS in position 1 causes connector relays C1-1, C1-2, &c., to connect the top row of indicators to the vertical bus-wires, and relay Rl to connect all the motor circuits of the top row. Other positions on switches SS, RS enable individual indicators to be operated separately by pushing the appropriate push button switches S5-1, &c. Indicators operating on a six-element binary code signal may be operated by a five-element code signal such as used with a teletype machine, by first translating the code into its equivalent sixelement signal by the relay system of Fig. 11. Specification 725,807 is referred to.