Patent GB-647001-A (GB)
Title: Improvements relating to electrical communication systems
IPC: H04M9/00
Filed: 1947-12-19
Abstract: 647,001. Credit-sanctioning telephone systems. DRAKE & GORHAM, Ltd., and SMALLBONE, E. J. Dec. 19, 1947, No. 33675. [Class 40 (iv)] [Also in Group XVIII] In a sanctioning telephone system for enabling shop assistants to make enquiries regarding the state of customers' accounts an automatic impulsing telephone is employed and the wiring is arranged so that speaking, ringing and other operations are all carried out over two wires only, SL and RT, between each department and the counting house with two common wires C1 and C2 from the source of electrical supply to each department which therefore utilizes four terminals in all. The system comprises a telephone and paper marking instrument controlled by a switch PS actuated on inserting a paper slip at each department and a number of boards B1, B2 each furnished with a receiver and microphone AR1, M1 or AR2, M2 at the counting house and each allocated to the accounts of certain customers. An impulse dial TD is provided in each department to connect that department to the counting house at which a number of selecting relays SR1, SR2 each associated with one of the boards are interconnected so as to connect the department to the 'board corresponding to the number of impulses dialled. The line SL between the department and the counting house is employed for carrying the impulses and also for carrying the current for actuating a solenoid PM for marking the paper slip for sanctioning purposes by connecting that line at the department to the telephone dial and through the paper actuated switch to the marking solenoid and by connecting the line at the counting house by a line key LS1 or LS2 alternatively to the winding of the respective selector relay or to a sanctioning button SB1 or SB2. Ringing current and talking current are both carried by the line RT between the department and the counting house by completing the ringing circuit through a ringing button RB1 or RB2 and a hook contact 12 of the telephone set in the department and completing the talking circuit, upon releasing the ringing button and upon lifting the telephone, through a contact 20 of the latter. Operation. The shop assistant puts a sales slip into the paper marking instrument, thereby closing the contacts of the switch PS, and dials one impulse on the dial TD to select the board, e.g. B1, dealing with the particular customer's account, without lifting the telephone T. The impulse operates the selector relay SR1 and thereby causes the lamp DL1 to light and so indicates the department calling. The counting house attendant changes over the line switch LS1 to the position shown for connecting the source of supply AS with the department and presses the ringing button RB1. On hearing the bell BL the shop assistant lifts the telephone T and its hook contacts 12 moving to the position shown complete the circuit of a red lamp WL1 on the board B1 to warn against the operation of the sanctioning button until the account in question has been checked and, since the circuit passes through the contacts of the switch PS, to show that the sales slip has been inserted. The assistant speaks and gives the counting house the required particulars, and if the credit can be sanctioned the counting house attendant presses the sanctioning button SB1 to punch and date the slip by operating the solenoids PM and DM. If the credit cannot be sanctioned the shop assistant is informed accordingly. To select the board B2 the assistant dials two impulses on the dial TD, the first of which operates the relay SR1 and the second of which operates the relay SR2 (through a contact 25 of the relay SRI) and in so doing breaks the maintaining circuit of the relay SR1 at the contact 4. The operations then follow for the board B2 as for the board B1. Other boards may be added, using the same number of lines, by wiring them with similar connections. Specifications 646,999 and 647,000, [Group XVI], are referred to.