Coin telephone circuit for dial-tone-first service

Claim 2

In a coin telephone set, operable selectively in both the prepay and dial-tone-first mode, in combination, means responsive to an off-hook condition for initiating the flow of loop current and establishing thereby a dial-tone-first mode without a coin deposit, means responsive to a battery polarity reversal for shifting said set from said dial-tone-first mode of operation to said prepay mode of operation, and means operative in the on-hook condition responsive to the deposit of a coin for establishing a refund request condition.

Claim 3

In a dial-tone-first coin telephone set adapted to enable a customer to dial preselected numbers without requiring a coin deposit while requiring a coin deposit for all other numbers, in combination, first and second terminals for connecting to the ring and tip leads of a telephone line, respectively, dial signal generating means, a coin signal generating circuit, a first relay including a coil, a telephone speech network, a plurality of contacts operated by a totalizer mechanism, and means responsive to an off-hook condition for initiating a loop current flow from said first to said second terminals, thereby to alert a connecting central office to said off-hook condition, the path for said current including said coil, a normally closed pair of the contacts, normally closed contacts of said dial signal generating means, operated closed switch hook contacts and a portion of said speech network.

Claim 4

In a dial-tone-first coin telephone set adapted to enable a customer to dial preselected numbers without requiring a coin deposit while requiring a coin deposit for all other numbers, in combination, first and second terminals for connecting to the ring and tip leads of a telephone line, respectively, dial signal generating means, a coin signal generating circuit, a first relay including a coil, a telephone speech network, a plurality of contacts operated by a totalizer mechanism, and means responsive to an off-hook condition for initiating a loop current flow from said first to said second terminals, thereby to alert a connecting central office to said off-hook condition, the path for said current including said coil, a normally closed pair of the contacts, normally closed contacts of said dial signal generating means, operated closed switch hook contacts and a portion of said speech network.

Claim 5

Apparatus in accordance with claim 2 further including, a source of reference potential, and means including normally closed contacts of said relay and a portion of said speech network for connecting said source to said second terminal, said last named connecting means being rendered inoperative by the operation of said relay by said current and the associated opening of said normally closed contacts of said relay, thereby ensuring the flow of said current to said second terminal rather than to said source.

Claim 6

Apparatus in accordance with claim 2 further including, a source of reference potential, means for connecting said source to said second terminal via a portion of said speech network, said last named means comprising a conductive path including, in series circuit relation, a set of coin hopper trigger make contacts, a resistive device, the operating coil of a coin relay, a set of break contacts operated by said first relay, a set of make contacts operated by the totalizer mechanism of said set and the reset electromagnet of said coin totalizer.

Claim 7

Apparatus in accordance with claim 4 wherein said resistive device is shunted by a set of break contacts of said coin relay, wherein said coil of said coin relay is shunted by a pair of make contacts of said coin relay, and wherein said make contacts of said coin totalizer are shunted by a first path including an SCR device, by a second path including the series combination of a first nonlinear impedance device and a thermistor and by a third path including a second nonlinear impedance device, said SCR device providing a low impedance current sustaining path to ensure the completion of refund and collect operations after said reset electromagnet operates.

Claim 8

A circuit for a coin telephone set operable, selectively, in both the prepay and dial-tone-first mode comprising, in combination, first and second terminals each connectable to the ring and tip leads, respectively, of a telephone line, a voice circuit including third and fourth terminals, a transmitter and a receiver, means directly connecting said second terminal to said fourth terminal, a coin totalizer including a plurality of sets of contacts, a first relay having a first coil, a second relay having a second coil, means connecting said first terminal to said third terminal including, in series relation, said first coil, one of said sets of contacts, dial pulse contacts and first switch hook contacts, a source of reference potential, means including a portion of said voice network connecting said source to said fourth terminal, said last named means further including contacts operated by said first relay, a coin signal generator circuit, and means responsive to the operation of said second relay for isolating said voice circuit from said generator circuit thereby to preclude customers from hearing signals produced by said generator circuit.

Claim 9

A circuit for a coin telephone set operable, selectively, in both the prepay and dial-tone-first mode comprising, in combination, first and second terminals each connectable to the ring and tip leads, respectively, of a telephone line, a voice circuit including third and fourth terminals, a transmitter and a receiver, means directly connecting said second terminal to said fourth terminal, a coin totalizer including a plurality of sets of contacts, a first relay having a first coil, a second relay having a second coil, means connecting said first terminal to said third terminal including, in series relation, said first coil, one of said sets of contacts, dial pulse contacts and first switch hook contacts, a source of reference potential, means including a portion of said voice network connecting said source to said fourth terminal, said last named means further including contacts operated by said first relay, a coin signal generator circuit, and means responsive to the operation of said second relay for isolating said voice circuit from said generator circuit thereby to preclude customers from hearing signals produced by said generator circuit.

Claim 10

Apparatus in accordance with claim 6 wherein said isolating means includes contacts operated by said second relay, the operation of said last named contacts connecting a shunt capacitor across said generator circuit.

Claim 11

In a circuit for a coin telephone set operable selectively in both the prepay and dial-tone first modes, a coin refund-collect ground test comprising, in series circuit relation, a ground terminal, resistive means, a coin relay coil, contact means operatively responsive to the flow of loop current in said circuit for opening said path, a set of normally open coin totalizer contacts and a totalizer reset electromagnet, a first set of normally closed contacts of the coin relay shunting resistive means, and a second set of normally open contacts of said coin relay shunting said coin relay coil, a first path including an SCR device shunting said coin totalizer contacts, a second path including the series combination of a nonlinear impedance device and a thermistor shunting said coin totalizer contacts, and a third path including a nonlinear impedance device shunting said coin totalizer contacts.

Claim 12

In a circuit for a coin telephone set operable selectively in both the prepay and dial-tone first modes, a coin refund-collect ground test comprising, in series circuit relation, a ground terminal, resistive means, a coin relay coil, contact means operatively responsive to the flow of loop current in said circuit for opening said path, a set of normally open coin totalizer contacts and a totalizer reset electromagnet, a first set of normally closed contacts of the coin relay shunting resistive means, and a second set of normally open contacts of said coin relay shunting said coin relay coil, a first path including an SCR device shunting said coin totalizer contacts, a second path including the series combination of a nonlinear impedance device and a thermistor shunting said coin totalizer contacts, and a third path including a nonlinear impedance device shunting said coin totalizer contacts.

Claim 13

Apparatus in accordance with claim 8 including first and second terminals each connectable, respectively, to the ring an tip leads of a telephone line, a voice network including a third terminal and said second terminal, a coin signal generating circuit, means including said coin signal generating circuit connecting said first and third terminals, and means including a portion of said voice network connecting said ground test path to said second terminal.

Claim 14

Apparatus in accordance with claim 9 wherein said means connecting said first and third terminals includes the relay coil associated with the contact means operatively responsive to the flow of loop current.

Claim 15

In a dial-tone-first coin telephone set, in combination, first and second terminals for connecting to the ring and tip leads of a telephone line, respectively, dial signal generating means, a coin signal generating circuit, a first relay including a coil, a telephone speech network, a plurality of contacts operated by a totalizer mechanism, means responsive to an off-hook condition for initiating a loop current flow from said first to said second terminals, thereby to alert a connecting central office to said off-hook condition, the path for said flow including said coil, a normally closed pair of said contacts, normally closed contacts of said dial signal generating means, operated closed switch hook contacts and a portion of said speech network, a source of reference potential, means for connecting said source to said second terminal via a portion of said speech network, said last named means comprising a conductive path including, in series circuit relation, a set of coin hopper trigger make contacts, a resistive device, the operating coil of a coin relay, a set of break contacts operated by said first relay, a set of said contacts operated by said totalizer and the reset electromagnet of said coin totalizer, and means for bypassing said last named contacts thereby to facilitate the detection of a ground signal indicative of an overtime deposit and to facilitate coin return.

Claim 16

In a dial-tone-first coin telephone set, in combination, first and second terminals for connecting to the ring and tip leads of a telephone line, respectively, dial signal generating means, a coin signal generating circuit, a first relay including a coil, a telephone speech network, a plurality of contacts operated by a totalizer mechanism, means responsive to an off-hook condition for initiating a loop current flow from said first to said second terminals, thereby to alert a connecting central office to said off-hook condition, the path for said flow including said coil, a normally closed pair of said contacts, normally closed contacts of said dial signal generating means, operated closed switch hook contacts and a portion of said speech network, a source of reference potential, means for connecting said source to said second terminal via a portion of said speech network, said last named means comprising a conductive path including, in series circuit relation, a set of coin hopper trigger make contacts, a resistive device, the operating coil of a coin relay, a set of break contacts operated by said first relay, a set of said contacts operated by said totalizer and the reset electromagnet of said coin totalizer, and means for bypassing said last named contacts thereby to facilitate the detection of a ground signal indicative of an overtime deposit and to facilitate coin return.