Patent GB-731811-A (GB)
Title: Electrical equipment for handling individual demands for attention from a number of circuits
Inventor: HARTLEY GEORGE CLIFFORD
IPC: H04Q3/00
Filed: 1951-12-17
Abstract: 731,811. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. Jan. 16, 1953 [Dec. 17, 1951], No. 29468/51. Class 40 (4). In a call queueing system in which calls are extended for attention in the order of their arrival a periodic check is made of the incoming lines to determine which have calls requiring to be extended for attention. Three arrangements are described. In the first, which is described below, the queue is controlled by a common circuit which displays the calls in batches to the operators and ensures that no call is dealt with unduly out of turn. The second is similar to the first, but displays one call at a time. In the third, each call is allotted a serial number which is stored in a circuit individual to the associated incoming line and only one call is displayed at a time. First arrangement. When a line incoming to a manual board is seized, contact l enables a tube Tl, whereupon a pulse in a time position characterizing the line are applied to a comparator E, from a generator C through tube T1 and gate D. The first pulse is passed over lead XY and an incoming distributer G to the first free unit of a chain of storage units F, which applies the pulse over wire Y to the comparator E to prevent further pulses in the same time position seizing another storage unit. The generator C applies a marking code characteristic of and in the time position of each line to all the storage units and in combination with the pulse applied over lead XY this effects the registration of the identity of the line in the storage unit. Assuming that the maximum number of calls is being displayed, switch L indicates the storage unit associated with the first call, counter R records the number of calls extended and counter K records the number of calls of the last batch that have been displayed and switch H indicates the storage unit associated with the call next to be displayed. When a call other than the first is attended to by an operator, contact l opens and T1 ceases to pass pulses. As a result the pulses on lead Y corresponding to the attended call are fed by the comparator E to lead YX to clear the associated storage unit and to return the counter R one step. When the first call is attended to similar operations take place and also switch L hunts for the next occupied storage unit, the call associated with it becoming the first call. Switch L resets the counter K to zero. A release control circuit J causes the storage unit indicated by switch H to pass a pulse in the time position of the associated line through gate S and tube T2 to operate relay LL which causes the call to be displayed and counters R and K step forward one step. Switch H steps on causing further calls'to be displayed until counter R indicates that the maximum number has been reached. If now calls other than the headof the queue are attended to, for each call counter R steps back, a further call is released and counters R and K step forward. However, should counter K in this way be stepped to indicate the predetermined maximum number no further calls are released until the head of the queue is attended to. In the event of power failure, all relays LL are operated to extend calls to the manual board.