Patent GB-669285-A (GB)
Title: Coin control circuits for telephone systems
IPC: H04M17/02
Filed: 1948-09-10
Abstract: 669,285. Automatic exchange coin-freed systems. TELEFON FABRIK AUTOMATIC AKTIESELSKABET, and UNGAR, E. Sept. 10, 1948 [Sept. 15, 1947], No. 23899/48. Class 40 (iv). In multiple coin controlled telephone substation apparatus, the amount paid in and the charge levied for the call are registered by the positions of selective multi-contact switching devices which are respectively pulse-controlled from the coin box and the exchange, and are interconnected in circuit with a relay which is shunted and inoperative to establish or maintain a call connection when the payment is greater than or equal to the charge and is deshunted and operative to interrupt the connection when the payment is less than the charge. Fig. 1 shows apparatus in which A, B, C are the line circuit wires, D is the metering wire and a relay P in line C is operated on establishment of a wire connection to operate relay R closing contacts r. The insertion of coins representing 1 and 10 monetary units impulses the relay O through coin box operated relay contacts v, m, n to impulse the rotary switches MEV, MOV to register the number of units inserted. When MEV registering units is in position 1, MTV registering tens of units is stepped once through contact 1 of MEVa, contacts INTT, and HKT. Subsequently when MEV has registered nine unit pulses, and receives a further unit pulse, MTV is stepped once more through contacts MEVa9 and MEVa0 1  so that MTV and MEV in combination register the sum paid in units and tens. When a connection has been established, relay T receives a number of unit pulses from the exchange indicating the charge to be made and impulses the rotary switch TEV through contact t until it reaches position 9, when the next pulse impulses the rotary switch TTV through contacts TEVa9 and TEVt 1  to step one position for every 10th metering pulse, and TEV and TTV in combination register the charge due. The contacts of switch banks MEVb-e and MOVa-e are connected to the contacts of switch bank TEVb as follows: TEVb1-MEVb1, TEVb2-MEVc2, TEVb3- MEVd3, TEVb4-MEVe4, TEVb5-MOVa5, TEVb6-MOVb6. The contacts of the switch banks MEVb-e and MOVa lying between the 9th contact and the contact in each bank which is connected to a contact in the bank TEVb are interconnected. Contacts MTVa1- 11 are connected to contacts TTV12 and 1-10, and contacts MTVb2, MTVc3, MTVd4, MTVe5 and MTVf6 of switch banks MTVbf are respectively interconnected to contacts 2-6 of switch bank TTVb. The 3rd to 12th contacts of MTVb, the 4th to 12th of MTVc, and the 6th to 12th of MTVc are mutually connected. Consequently when the charge involves units only, exchange closure of the contact h of the checking relay (not shown) completes a circuit through resistance R 1  energizing relay K to energize relay U to interrupt the line B, unless the payment registered is greater than or equal to the charge due, when the appropriate contacts of the registering switches MEV, MOV, MTV, TEV, TTV, combine to short circuit relay K so that the line connection is maintained. When the payment in tens exceeds the charge in tens, the relay is short-circuited through MTV and TTV without checking the unitary registers. The apparatus is also applicable to a tariff system wherein an initial charge is payable for a specific time, which is extensible by payment of subsequent charges. MEV registers the initial payment and relay T is initially pulsed from the exchange so that TEV is in position 1. When payment is checked, relay K is shortcircuited and connection is maintained. Subsequently relay T is pulsed at intervals until the prepaid time has been exceeded when the relay K is de-shunted and the line connection interrupted unless further coins are inserted. In a modification, Fig. 2 (not shown), chains of successively operated relays register the coin box payments, rotary switches register the charge due, and relay K has dual operating windings co-operating with the relays and switches as previously described.