(1) Technical Field
The present invention relates to coin operated telephones and more particularly to coin operated relay device circuitry as used in prepay type telephone paystations.
(2) Background Art
Quite a number of different devices have been used to collect or refund coins deposited in telephone paystations. For example, in the current type 102B telephone paystation as manufactured by GTE Communication Systems, a single coil solenoid is used with a magnetic actuator. Depending on the direction of current supply to the solenoid coil, the magnet is either attracted or repelled from one magnetic pole to the solenoid, thereby causing either the collect or refund operation mode of the device.
Another type of coin relay used on the type 62 and type 82 prepay paystations manufactured by Automatic Electric Company, consisted of two coils, a permanent magnet between the coils and a centrally located armature mounted above the coils and magnet. The armature would then pivot to either side as determined by the polarity of the direct current applied to the relay coils. The position of the armature would then determine the coin collect mode or refund mode.
Both the single-coil solenoid device and the double-coil device require high voltages and currents to operate under control of an operator located at the telephone central office. A minimum of 48 volts and 44 milliamps of current are required to operate the device included in the current type 120B coin telephone referred to above. Another coin relay made by Northern Electric Company type P10E786 is similar in operation and construction to that utilized in the type 120B telephone noted above.
The automatic telephone exchange associated with coin telephones of previous design in prepay operation must of necessity be equipped with coin control repeaters, sources of positive and negative 110 volts DC for use as collect or refund battery and an interrupter that produces intermittent coin-control current for application to the telephone line. Upon lifting the handset in such an arrangement the calling party is connected to the central office and dial tone is usually heard. At this point the calling party now deposits the initial rate deposit and may dial the call in the usual manner. Upon termination of a call, the central office then sends either collect or refund battery to the telephone, depending upon whether the call was completed or was incomplete. If the call was completed, operation of the coin relay directs the coins into the cash vault included in the telephone paystation. If the call, however, was incomplete the coins are then directed into the coin return receptacle for return to the user. After the coins have been collected or refunded, the telephone is returned to its normal condition, that is to say it is ready for another call.
On an operator assisted calls, the initial rate amount is refunded upon connection to the operator. The toll operators then supervise collection of coins by audible signals generated by an audio oscillator located within the telephone. The operator controls the application of the coin collect or refund signals from the central office on all toll calls.
When the calling party deposits coins, the coins are directed into a coin accepter-rejector mechanism. After the coins clear that mechanism, they pass through a coin chute, that contains in modern design units, three trigger switches, one for each of the three denominations of coins utilized (5 cent, 10 cent, and 25 cent). When the coins actuate the trigger switches in the coin chute, the trigger switches close a path to a totalizer. The action of the totalizer is not pertinent to the present invention. However it is noted that the first coin in its path to the coin chute cause the triggering of the coin relay and operates a set of contacts that prepare a ground path to the transmission network. When the initial rate has been deposited, the totalizer causes the two relays to operate thereby enabling the rotary dialer touch calling unit (TCU) and extending coin relay ground to the transmission network. At this time, the central office is prepared to receive address signalling from the dial or touch calling unit.
In existing typical paystations such as the type 120B manufactured by GTE Communication Systems, passage of a coin into the hopper forces the coin trigger downward in the hopper slot, tripping it to permit the coin operated contacts at the rear of the spring pileup to assume their rest position. The first operating set of contacts remove a short circuit from the dial pulse springs or a low resistance shunt from the oscillator of the touch calling unit connected at two fixed terminals. The other contacts connect ground to the line instead of to the relay coil. After the coin is past, the trigger is prevented from restoring fully by the tilt of the lever spring of the make contact set. If a -110 volts DC refund potential is applied to the line, the polarity of the flux generated by the core of the relay coil is such as to cause the left end of a small bar magnet to be attracted to the left extension of the core or pole piece, this tilts a nylon selector card slightly so that as it is moved down by a rocker arm, it moves a cam and therefore a nylon hopper vein to the right. Meanwhile, the downward motion of the card is imparted to a trap lever, which pivots on its pin and moves its upper edge outward. This permits the nylon coin trap pivoted above the lever, to swing down inside the hopper, so the coin deposit falls against the left side of the vein and passes into the refund chute. If a +110 volts DC collect potential is applied to the line, the flux generated at the pole piece extensions are such as to attract the right end of the selector card magnet, against the right side of the vein into the coin receptacle.
As the relay armature operates the selector cards of the rocker arm, it also moves the spring lift to place 1,000 Ohm resistance in series with the coil and then short-circuits the coil. The resistance thus takes the place of the coil in the path of the coin control current, stabilizing the latter to prevent damage to the ground contacts when they open and to resistance lamps in the supply circuit at the central office. At the end of its stroke, the spring lift provides substantial pull to the coin operated ground contacts, so that the tilt of the lever spring no longer interferes with the trigger, which restores completely to normal under the force of a coil spring in torsion. The dial or touch calling unit shunting springs are forced close. With the relay shorted the current induced by the collapsing field tends to retard the decay of the flux in the core and makes the armatures slow to release. As it begins to restore, the spring lift permits the coin operated springs to retrieve from their over travel position. This prevents the break (either from the dial or from the touch calling unit shunt) contacts sets from reopening and allows the make (ground) contact set to open. As the ground path is opened the relay is disconnected from the coin battery circuit, thus extinguishing the coin pilot lamp if collection of refund is being controlled through a manual switchboard and preventing reoperation of the relay if the operator or control circuit continues application of coin batteries to the line. Finally, the transfer context set is restored to remove the short circuit from the relay coil and bypass the series resistor. The upward motion of the selector card during release acts to return the coin trap to horizontal and the hopper vein to its neutral vertical position in preparation for the next deposit.
From the forgoing it will be obvious that existing state-of-the-art coin collect and refund devices and the circuits associated therewith require high voltages and currents to operate and control by an operator or from central office equipment. Accordingly, it is the object of the present invention to provide a new circuit to be included in the telephone instrument for stand alone operation on a two-wire business line (not requiring operator or central office control).