Patent GB-595708-A (GB)
Title: Improvements to a prepayment telephone apparatus
IPC: H04M17/02
Filed: 1943-03-24
Abstract: 595.708. Coin-freed telephone apparatus. SODECO SOC. DES COMPTEURS DE GENEVE. March 24, 1943, No. 4807. Convention date, Jan. 15, 1942. [Class 27] [Also in Group XXXIX] A paystation from which can be set up connections having different basic charges with additional duration charges, is provided with devices for making speech unintelligible if the coin value is less than the value represented by metering impulses plus a fixed charge, and for releasing the connections after a delay if sufficient additional coins are not inserted. The paystation has provision for setting up local, surburban and inter-urban calls, the two last mentioned being dealt with on a duration basis and the charge for the local call being the abovementioned fixed charge for other calls which, however have increased initial charges. Circuit arrangements. In Fig. 2 the impulse springs 26 are shunted by contact 25 until coins at least equal to the local charge have been inserted. On a suburban call, the sufficiency of the coins is determined on the receipt of the first train of metering impulses when the called party replies, and if they are insufficient, contact 64 is operated to connect an interrupter 65 or interference in the form of commercial supply or current from a gramophone pick-up (which may be verbal) to the connection so that both parties are warned. Figs. 7 and 8 (not shown) have modified interference arrangements. The connection is re1eased at 78, after a delay, if sufficient additional coins are not inserted. In the case of inter-urban calls a further precaution, taken initially, consists in the closure of a further shunt 80 on the impulse springs 26 due to dialling an increased number of digits unless contact 79 has previously been opened by the insertion of coins of the required value. Metering magnet is operated by A.C. impulses over a simplex circuit and relay 81 connected to the loop starts motor 67 which drives some mechanism and winds springs for driving the devices; 126 are switch hook contacts. Coin and metering impulse actuation, Figs. 3a and 3b. Coins inserted at 1 each actuate lever 10 which releases shaft 7 for one revolution under drive from spring 8, gears 12 and shaft 9 being driven for a portion of a revolution of 7 dependent on the value of the coin. Shaft 9 drives shaft 14 carrying fixed and friction clutched wheels 15, 16 which drive respectively the planet and sun wheels 30, 32 of a differential, the other sun wheel 33 of which controls credit or debit indicating mechanism 55, 58 differentially by gear 37 in conjunction with control from ratchet wheel 54 driven by metering magnet 47. The coin value of the call is absorbed before coins have any effect on the 1st differential 30-33 the gear ratios of 15, 28 and 16, 18 being suitable for this purpose provided that both wheels 18, 28 are driving the differential, Wheel 18 is, however, stopped by cam 22 when 18 has driven it through an angle representing the local charge. Cam 22 is normally biassed in one direction against a stop 27 which also limits its movement in the other direction in which limiting position contacts 25 shunting the impulse springs are opened. The output shaft 40 differential gear 37 drives shaft 55 of the credit and debit indicator 58 which is biassed to zero indication by spring 59. The shaft carries a cam 56 which if a debt is indicated, operates lever 63 whereby a contact 64 is operated to make speech unintelligible and by means of an interrupter 65 driven by constant speed motor 67 started by relay 81 in the loop circuit and (b) shaft 75 is driven by the motor and after a predetermined time opens contacts 78 to release the connection. Shaft 55 carries also a second cam 57 which if the credit is initially insufficient for an inter-urban call prevents the transmission extra digits by failing to open contacts 79. The above described arrangements are applicable to systems in which local calls are metered on release and others on reply but if local calls are also metered on reply, the metering impulse must not cause the interference arrangement to operate. To deal with this cam 56 is modified and provided with a masking sector as in Figs. 4 to 6 (not shown) to prevent actuation of the interference by the single impulse received in local calls. Coins cashing-in and refund; release of apparatus. When a call is initiated, loop relay 81, in addition to starting the motor 67 releases a lever 93 on a shaft 87 geared to a cam shaft 85 driven by spring drum 86. The cam shaft is driven only a fraction of a revolution since the shaft 87 is carried at one end by a lever 90 controlled by cam 92 on shaft 85 so that lever 93 is again engaged by the armature of relay 94 now in its operated position. During this fractional rotation of the cam shaft, lever 101 disengages itself from a lever 102 which starts the duration indicator but lever 102 remains held until cam 108 on shaft 109 is withdrawn by meter magnet 47 on reply of the called party. Lever 102 thereupon engages gears 103, 104 and indicator 105 is driven by motor 67 through a friction clutch 106, the indicator being restored by spring 107 when the connection is released. Also during the movement of the cam shaft, shutter 117 is moved to close the cashing-in chute 5 and is held in this position by member 119 until the operation of the metering magnet, so that if the call is not effective the coins are ultimately refunded down chute 6. The cam shaft remains in this position until the connection is released and relay 81 falls back whereupon shaft 87 is released and cam shaft 85 completes the revolution with the following results:-(a) lever 97 disengages gears 43, 45 for a period to allow the credit and debit indicator to restore, (b) lever 99 withdraws clutch 20 to allow restoration of cam 22, (c) lever 101 effects disconnection of the drive of the duration indicator, (d) lever 112 releases catch 113 of the coin support 113 to cash-in or refund the coins.