Patent GB-241600-A (GB)
Title: Improvements in and relating to pathfinders or route or position indicators for street or road maps, exhibition plans, railway maps, and the like
IPC: G09B29/10
Filed: 1924-04-28
Abstract: 241,600. Waller, P. H., and Emms, S. April 28, 19 Maps and charts.-In electrically - illuminated route, position, and like indicating apparatus for maps, charts, plans &c, applicable to indicating the route from the indicator station to another place or between two places in maps of towns, roads, exhibitions, buildings and ships, and to indicating groups of places at which certain supplies are available, the illumination is controlled by multipl switches, one switch or unit of which is normally closed, and which are so arranged that closure of any other switch causes the switch already closed to open. Means are provided to prevent operation of more than one switch at a time, to retain an operated switch automatically in closed position, and to close a circuit automatically if all the switches are open. The map 3, Fig. 6, may be mounted between the glazed part of a frame 1 and an opaque sheet 4 perforated to indicate routes &c. The electric lamps are accommodated in a cellular structure 5 and are carried by a wiring board 7 carrying the switch mechanism and removable from the frame 1 by means of sliding bearings 8 under steady pin or like control. At one or both sides of the frame 1, push button switches 12, Figs. 1 and 3, are arranged adjacent to an index-key viewed by reflected or transmitted light, or adjacent to numbers corresponding to numbers in a separate key. Each button 12 operates a switch comprising a blade 9 pivoted at 10 and normally pressed away from contacts 11 by springs 14, 15. The operated blade 9 is retained in engagement with the contacts 11 by a locking bar 13 common to the switches, pivoted at 16 and engaging the end itself of the blade 9 as well as a catch 18 pivoted to the blade 9. The catch 18 is normally maintained in the position shown by a slight pullspring 19 and an abutment 18<a> bearing against the blade 9. On depression of a blade 9, the catch 18 moves the bar 13 against the action of a spring 17 to release the end itself of the blade of the switch previously operated, after which the catch 18 of this blade is turned anticlockwise by the bar 13 and springs 14, 15 to shorten and complete the release of this blade. The support 20 for the switches is at an angle to the front of the frame 1 to give a simple push action to the switches. When a row of switches is arranged at each side of the frame, the corresponding bars 13 are interconnected by a bar 33, Fig. 1, so that operation of any switch releases a previouslyoperated switch on either side. To prevent operation of more than one switch at a time, the parts 24 of the blade 9 co-operate with a common member opening or yielding to receive one part 24 only at a time. The common member may comprise a flexible part becoming effectively rigid when one switch is operated, for instance, a flexible air tube 25, Fig. 9, in a rigid outer tube 26 notched to receive the parts 24, or a chain 27, Fig. 10. In the form shown in Fig. 1, the common member comprises a row of balls 22 in a notched tube 23 with space to receive one part 24 only, spring means being provided to maintain the balls so that normally the angles between the balls are opposite the wedge-shaped parts 24. If none of the switches 12 are operated, a circuit is closed automatically by contacts carried by two parts of a bar 28 pressed apart by a spring 29 but pressed together on the operation of any switch by bell-crank levers 30 acting on plungers 31 pressing on the two rows of balls 22 corresponding to the two rows of switches at the sides of the frame. A push button moving the bar 33 through an inclined-plane action or other means is provided to release the blades 9 from the bar 13 and so allow manual closure of the switch 28. Any switch 9 may close several circuits or several gaps in one circuit. Specification 241,599 is referred to.