GB1419084A - Coin operated telephone apparatus and electric circuit arrangements therefor - Google Patents

Abstract

1419084 Coin box telephones ASSOCIATED AUTOMATION Ltd 16 Feb 1973 [17 Feb 1972] 7306/72 Heading H4K [Also in Division G4] A prepayment coin box telephone of multicoin type is presettable to handle any one of a plurality of sets of coin denominations and any one of a plurality of tariffs. As described the invention provides a MOS integrated circuit chip for use with coin storage mechanism as described in Specification 1,334,157. The circuit comprises three cyclic stores 1, 2, 3 for storing the number of uncollected coins in respective denominational channels, a cyclic store 4 in which is stored the total residual credit and a cyclic store 19 in which is stored residual credit from the cashed coins only. In a first clock cycle after a coin is inserted a corresponding signal on a line 5, 6 or 7 increments a counter 1, 2 or 3 and primes a corresponding set of AND gates in a block 8, the other inputs of which gates are connected to separate outputs of a store 9 preset to the coin denominations involved, thus producing at the output of the primed set of gates a code characteristic of the associated coin. The resulting code is registered at 10 and gated at 15 to an adder/subtractor 16 where the value added to the content of store 4. During the next clock cycle the metering tariff as decoded at 13 is transferred to register 10 and compared at 16 firstly with the content of store 4. If sufficient credit for a further metering period is not available a warning is given to the user and the call is cut off if a metering pulse arrives without insertion of a further coin. If sufficient credit is available and a meter pulse arrives the charge rate is compared with any residual value in store 19 due to collected coins and if this value is sufficient the charge is deducted therefrom. If the residual value is insufficient comparator 17 signals to a circuit 20 which initiates cashing in of further coins the value of which are added to the value in store 19 until sufficient credit is stored for the charge to be deducted. At the end of the call any coins not cashed may be returned to the caller. It is also suggested that in a modification the credit and debit information may be stored until the end of the call and appropriate coins cashed at that time.