Patent GB-727581-A (GB)
Title: Improvements in and relating to a prepayment station in an automatic telephone system
IPC: G07F1/04
Filed: 1952-01-10
Abstract: 727,581. Automatic exchange systems. SODECO SOC. DES COMPTEURS DE GENEVE. Jan. 10, 1952 [Jan. 15, 1951], No. 773/52. Class 40 (4). [Also in Group XVIII] In a prepayment telephone system; the caller inserts a provision of coins and at the end of the call surplus coins are refunded. The amount retained is determined by metering pulses transmitted from the exchange during the conversation at evenly spaced intervals determined by the connection obtained. If coins of different denominations are inserted, the refund is made as far as possible in coins of the highest value. The prepayment apparatus shown takes 10 and 25 cent coins and each metering pulse corresponds to a charge of 5 cents. When the handset 35 is raised, the switch-hook 36 moves a member 34 to close the outlet slots 30, 31 of the coin trays 24, 25, operates a switch 39 to prepare for the insertion of coins and through gearing disengages a stop 49 from a projection 50 rigid with the refund indicator 97. Relay 9 opens the coin slots 14, 15. A 10 or 25 cent coin when inserted passes through a checking device 16 or 17 into a slot in a disc 20 or 21 and actuates a switch 26 or 27 to cause a motor 67 or 68 to rotate the disc 20 or 21 and to set the refund indicator 97 through differential gears 73 and 75. A cam-controlled switch 55 or 56 takes control of the motor 67 or 68 before the switch 26 or 27 releases to ensure that the disc 20 or 21 is rotated through one slit interval, whereupon a switch 28 or 29 is operated by the coin. The driving shaft of the refund indicator 97 carries a number of cams controlling switches 88, 90, 92, 94 and 96 and when the refund indicator shows 150 cents, switch 90 releases relay 9 to close the coin slots. The first metering pulse operates a relay 78 which causes a relay 80 to lock up to prepare for cashing-in the coins. Relay 78 responds to each metering pulse to act on the differential gear 75 to return the indicator 97 by a distance equivalent to 5 cents. Should the refund indicator 97 reach 10 cents, switch 92 operates a warning device and if this is ignored, switch 88 breaks the connection when the indicator shows less than 7¢ cents. When the handset 35 is replaced, the outlet slots of the trays 24, 25 are freed, switch 39 prepares for refunding and cashing-in and the stop 49 is moved to its normal position. If not less than 25 cents is to be refunded in which case switches 94, 96 are operated and if switch 29 is operated showing that a 25-cent coin has been inserted, the motor 68 is driven in reverse to drop coins in the refund shoot 106 until either the tray 25 is emptied or the switch 96 releases, whereupon 10 cent coins are similarly refunded until either tray 24 is emptied or the switch 94 releases to indicate that less than ten cents remains due to the caller. A circuit is completed for relay 102 which actuates the flap 103 to direct coins into the box 107 and causes the motors 67, 68 to drive the discs 20, 21 until the switches 28, 29 remain open. Thus the remaining coins are cashed in. When the refund indicator 97 feaches zero, it is retained by the stop 49. If it is desired to charge a fee for setting up a connection additional to that corresponding to the metering pulses, the cams controlling switches 88 to 96 are set forward by the corresponding angle.