GB2251155A - Payphone with ring tone detection for deferring payment acceptance - Google Patents

Abstract

Control apparatus for a payphone, especially a cellular telephone 10, includes ring tone detection means 60 for deferring acceptance of payment (eg coin or card) and commencement of call duration timing until ring tone ceases indicating successful connection of a call. The payphone has a power supply 12 connected to a coin controlled mechanism 20. A coin detect terminal D outputs a signal on coin detection through flip flop 24 to provide power from the supply 12 to the transceiver 10. A hook state detector 40 is energised by lifting the transceiver 10 and a coin is placed in a held condition whilst awaiting call connection. The ring tone bursts are detected by detector 60 which starts timers 70, 72 in response to the stop and start of each ring tone burst. When call connection has been made the output 86 energises coin accept means 88 and a call timer 90 associated with an indicator 96 related to elapsed time and coin accepted. When the call is terminated, or further coins are not supplied, the output 98 from the call timer 90 causes flip flop 24 to reset, actuate coin return means 54 and initiate power off procedure. <IMAGE>

Description

PAYPHONES This invention relates to so-called payphones and has particular, but not exclusive, application to cellular telephones.

We are not aware of any cellular telephone units being available for operation on a pay-operated basis, and it is an object of this invention to provide an effective system capable of application to cellular telephones.

According to this invention, there is provided payphone control apparatus comprising payment detection means for successive payments, hook-state detection means for lifting of telephone handpiece, and timing means for limiting call duration according to payments made for and during the call, and ring tone detection means for deferring acceptance of payment and call duration timing until ring tone ceases indicating successful connection for the call and for terminating payphone operation after the handpiece goes on-hook.

The payment and hook-state detection means may be of any suitable nature and light emitting and detecting types will be described and shown.

Operational state of the payphone can conveniently be controlled by way of means performing an Exclusive-OR function relative to payment detection and power-on condition of the payphone, say controlling a switchable power supply for the telephone transceiver.

Payment detection may involve setting the state of bistable means reset by signals from the hook-state detection means and/or call timing means.

Ring tone detection and related control preferably involves producing a control signal at a time beyond normal intervals between ring tone bursts. Such provision can advantageously involve means setting two different time periods both longer than intervals between detected ring tone bursts and providing a control signal only during the difference between said time periods after ring tone bursts cease to be detected. Two separate timers may be used, each started at the trailing end of each ring tone burst and reset at leading edge of next succeeding ring tone bursts. Means performing an Exclusive-OR function can be used for output states of the timers, and bistable means may further usefully effectively staticise the time difference control signal. When set, such bistable means can control both of starting the call timing means and operation of payment accept means.Resetting of such bistable means is preferably before next operation of payment detection means, typically going on-hook.

Provision for coin return can usefully utilise coincidence gate means response to on-hook state, preferably further with an eject provision, and conveniently further in response to payment detection and/or resetting of end-of-dial pulse detection means.

Specific implementation for this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block circuit diagram; Figure 2 is a flow diagram; and Figure 3 is a detailed circuit diagram.

In the drawings, referring first to Figure 1, box 10 represents transceiver equipment of a cellular telephone subscriber's unit, and box 12 its power supply 12 required herein to be of a switched nature (represented by enable terminal E) for payphone operation indicated as controlled by coin mechanism 20.

The coin mechanism 20 has a coin detect output terminal D to line 22 connected to one input of a flip flop 24, which is of bistable type set by energising line 22 and reset by energising line 26 to its other input. Output 28 of the flip flop 24 goes to one input of a two-input Exclusive-OR gate 30 whose other input is connected over line 32 to output of the power supply 12.

Output 34 of the Exclusive-OR gate 30 will have one state when both its inputs are high or low, and another state when those inputs are different, and is used to control the power supply 12 to be on when the Exclusive OR inputs are different. The latter will occur when the power supply 12 is off and a coin-detect signal appears on line 22, also when the power supply 12 is on and there is no signal on line 22. That facilitates operation using a coin mechanism 20 of a type giving only a momentary coin detect output as a coin enters the mechanism on its way to a held position pending establishment of an intended call connection. A capacitor 36 serves to ensure that response of the flip flop 20 to energisation of its reset line 26 is such that the switched power supply 12 will not shuttle between on and off states.

When the power supply 12 is switched on, the transceiver 10 will be operable. For the embodiment of payphone controller being described, however, operation is further made to be possible only if the telephone handpiece is lifted, i.e. off-hook in telephone parlance. That is achieved using an on-hook/off-hook detector 40 having an output 42 that is energised for off-hook conditions. Related circuitry 44 including a coin eject switch 46 is operative to control energisation of line 48 connected to reset line 26 for the flip flop 24 and line 49 connected to one input of AND gate 50. Resetting of the flip flop 24 is thus obtained when the telephone hand-piece is on-hook, also operation (via AND gate 50 and its output 52) of coin return means 54 of the coin mechanism 20.

Once coin entry has been detected with the handpiece off-hook, the power supply 12 will remain switched on while dialing takes place and ring tone bursts are detected by detector 60, indeed through a call connection. Output 62 from the ring-tone detector 60 is shown going to envelope and triggering circuitry 64 operative to produce timer start and reset signals on its output 66 at times corresponding to stop and start of each burst of ring tone, respectively. Two timers 70 and 72 are shown operated by trigger signals on line 66.

Both of the timers 70 and 72 have time constants greater than intervals between ring tone bursts, but those time constants are different so that, after a connection is completed and ring tone bursts cease, there is bound to be an interval corresponding to the difference in time constants of the timers 70 and 72 during which their outputs 74 and 76, respectively, are differently energised.

The timer outputs 74 and 76 comprise inputs of a second two-input Exclusive-OR gate 80 whose output 82 goes to one input of a second flip flop 84 of a bistable type thus set to energise its output 86 for operating coin accept means 88 of the coin mechanism and starting operation of a call timer 90 over branch 92. Because of the bistable nature of the flip flop 84, the coin accept means 88 will remain enabled to accept further coins for the duration of a telephone call.

The call timer 90 is shown cascaded with a second call timer 94, though the latter can conveniently be a last stage of a single timer if desired. An indicator 96, such as a light emitting diode, is associated with the second call timer 94 and serves to indicate that time paid for is running out and that further payment is required if the call is to continue. Otherwise, the call will be terminated automatically by way of output 96 of the second call timer 94 shown going to reset the first flip flop 24, thus producing similarity of inputs to the first Exclusive-OR gate 30 and causing power-down of the transceiver 10.

The coin accept means 88 can conveniently be of a type that goes automatically to a state in which coins are not accepted at power-down of the transceiver 10.

However, positive resetting of the second bistable 84 is preferred and advantageous, and is shown achieved over branch line 97 at next setting of the first flip flop 24 on detection of coin entry at next attempted use of the equipment, which is entirely safe as electronics responses will be much shorter than coin travel speed and distance involved in the coin mechanism.

The AND gate 50 for controlling coin return is shown with another input fed by branch 98 from the set output 28 of the first flip flop 24, and also by reset output from the second bistable 84. So, once a call has started no coins can be returned before the call is completed, in fact conveniently only when the telephone handpiece on-hook. Other arrangements can be provided and may be preferred. For example, with the handpiece off-hook but before ring tone is established, and/or employing a coin cumulation facility from which coins are taken by the coin accept means only successively but automatically at or just before timing-out by the call timer or stage 94 and then unused coins returned in the on-hook condition either automatically or on operation of the eject provision 46.Moreover, tokens could be used instead of coins, even progressively cancelled call credit cards by ready variation of known systems.

Figure 2 is a flow diagram representing operation of a system hereof illustrated in detail in Figure 3, and is believed to be self-explanatory.

Turning to Figure 3, boxes generally equivalent to those of Figure 1 are superimposed and similarly referenced. It will be noted that both of the coin detection means and the handpiece off-hook detection means at 20 and 40 are shown utilising light emitting diodes and phototransistors as convenient practical implementations. The flip flops 24 and 84 can conveniently be in a dual integrated circuit, as can a pair of 4-input NAND gates shown connected up for the three-input AND gate 10 of Figure 1. Indeed, so far as possible, it is generally advantageous these days to use semiconductor integrated circuits readily available with plural circuitry on each.

In Figure 3, various diodes and coupling, voltage dropping or load resistors are indicated outside boxes for which they serve,but that is not fully consistent, for example particularly for the ring tone detector 60 where various ancillary components are shown connected to an appropriate integrated circuit within the box 60, and for leading and trailing edge trigger circuitry 64, timers 70 and 72, call timer stages 90 and 94, output conditioning circuitry referenced 100 for output of the second Exclusive-OR gate 80, and referenced 102 for output from the handset on/off hook detector 40, also buffer circuitry 104 for output from the first Exclusive-OR gate 30. Relays are shown with associated circuitry for the coin return and accept means 54 and 84, and a power supply is indicated at 110.

It will be appreciated that payphone controllers hereof are not limited in application to telephones of cellular type.

Figure 3 shows a diode 99 in line 98 that shorts out the capacitor of timer 90 when a further coin is entered, so as to reset the timers 90 and 94. Resetting of the flip flop 84 similarly involves a diode in line 97 upon hand-set going on-hook and/or coin ejection.

Claims (13)

1. Payphone control apparatus comprising payment detection means for successive payments, hook-state detection means for detecting lifting of telephone handpiece, timing means for limiting call duration according to payments made for and during the call, and ring tone detection means for deferring acceptance of payment and commencement of call duration timing until ring tone ceases indicating successful connection of the call and for terminating payphone operation after the handpiece goes on-hook.

2. Apparatus as claimed in claim 1 in which the payment detection means further includes means to control the operational state of the payphone by operation of a switchable power supply for the telephone transceiver.

3. Apparatus as claimed in claim 1 or claim 2 in which the payment detection means includes bistable means whose state is set on detection of payment and reset by signals from the hook-state detection means.

4. Apparatus as claimed in claims 1 or 2 in which the payment detection means includes bistable means whose state is set on detection of payment and reset by signals from the call timing means.

5. Apparatus as claimed in any preceding claim in which ring tone detection produces a control signal at a time beyond normal intervals between ring tone bursts.

6. Apparatus as claimed in claim 5 which includes means to set two different time periods, both longer than intervals between detected ring tone bursts and provide a control signal only during the difference between said time periods and after ring tone bursts cease to be detected.

7. Apparatus as claimed in claim 6 in which two separate timers are provided, each started at the trailing end of each ring tone burst and reset at leading edge of next succeeding ring tone bursts.

8. Apparatus as claimed in claim 6 or claim 7 in which bistable means are provided to staticise the time difference control signal.

9. Apparatus as claimed in claim 8 in which the bistable means controls both starting of the call timing means and operation of payment acceptance means.

10. Apparatus as claimed in claim 8 or claim 9 in which the bistable means is reset before next operation of payment detection means.

11. Apparatus as claimed in any preceding claim further including coin return means utilising coincidence gate means responsive to an on-hook state.

12. Apparatus as claimed in claim 11 in which the coin return means includes an eject provision, in response to payment detection and/or resetting of endof-dial pulse detection means.

13. Payphone control apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.