GB2078466A - Micro-processor controlled coin-box telephone instruments - Google Patents

Abstract

The invention relates to microprocessor controlled coin operated telephone instruments which use only the telephone line to derive power. The instrument is arranged to include means for switching off most of the active components of the instrument when the instrument is idle and power-on restart means adapted to cause power to active components of the instrument to be switched on when the instrument is taken into use. Typically the instrument remains in the powered down state until one of a number of input events occurs as a result of (a) an automatically generated call to report a fault or cash-box full condition, (b) an incoming call is detected, (c) a normal outgoing call is commenced or (d) an insulation line test condition is detected.

Description

SPECIFICATION Micro-processor controlled coin-box telephone instruments The present invention relates to micro-processor controlled coin-operated telephone instruments designed to accept a number of coin denominations through a single slot.

With the advent of micro-processor controlled coin-operated telephone instruments (or payphones) the facilities provided to the users of such instruments have been substantially expanded. The payphone instrument may be operated by the telephone authority and therefore these instruments are located in public places or may be rented to private concerns with the instrument being used by a large number of individuals using the premises of those concerned.

In all cases it is important to ensure that the design of the payphone does not put constraints upon its location. One major feature of such payphone is that it should be powered from the telephone line (using an internal battery charged from line current). While the power consumption of micro-electronic circuitry is by and large not very high it is still important to ensure that the power consumption is kept to a minimum.

It is an aim of the present invention to provide a payphone instrument which is very economical on line power.

According to the invention there is provided a coin-operated telephone instrument including means for monitoring for incoming calls and means for handling incoming calls and outgoing calls wherein the means for handling incoming calls and means for handling outgoing calls are adapted to be powered-down when the telephone is idle and are arranged to be selectively powered-up as required when the instrument is taken into use.

Typically the instrument is micro-processor controlled and remains in the powered down state until one of a number of input events occurs as a result of (a) an automatically generated call to report a fault or a cash-box full condition, (b) an incoming call is detected, (c) a normal outgoing call is commenced or (d) an insulate line test condition is detected.

In addition the payphone instrument includes a line interface equipment which includes line length assessment arrangements which may be adapted to control the amplification level of the speech amplifiers of the instrument.

The invention will be more readily understood from the following description which should be read in conjunction with the accompanying drawings. Of the drawings: Figure 1 shows a block diagram of the equipment required for one embodiment of the invention, Figure 2 shows a typical flow chart of a section of the program, while Figure 3 shows a diagram of the work space memory map.

GENERAL DESCRIPTION The telephone instrument described herein is of a new prepayment type specifically designed to accept four U.K. coin denominations through a single slot with optical and electronic sensors to identify, validate and count the coins. Microprocessor control is employed, enabling coins to be inserted during conversation and credited to the caller. Coins are not collected until the end of the call, when the total fee is evaluated and any surplus coins are refunded as change.

The payphone requires to be of rugged construction to withstand vandalism and theft in public places. It includes facilities such as automatic transmission to the accounting centre giving the value of the cash box contents when this is exchanged for an empty one. The payphone, a detailed description of which is given later, incorporates:: An advanced design of electronic coin validator, Modular softward control of the operational functions, A single coin entry slot for all coin denominations, A visual display showing the stored credit and when to insert coins, A means of returning rejected coins to the user, "Best change" facility, A follow on call facility, A rubbish flushing mechanism, A lockable cash box with a shuttered coin slot to prevent unauthorised coin removal, A keypad highly resistant to mechanical damage, Choice of Decadic or MF4 signalling, A software controlled fully flexible call charging system, Means to re-programme to accommodate changed tariffs, Automatic fault reporting, Powering from the line, Ease of installation and maintenance, Rugged case design.

OUTLINE DESCRIPTION OF THE PAYPHONE SOFTWARE System Organisation Electrically, the system is electronic, employing a fully electronic validation process coupled with a centralised microprocessor control. The system organisation will be better understood by reference to the accompanying schematic diagram shown in Fig. 1. The schematic diagram shows how the electronics of the payphone is partitioned into interface circuitry IA validator and coin management control circuitry VCMA, a micro-processor control MPC, analogue and line interface circuitry AILA and a keypad/display K/D.

The interface circuitry IA serves the equipment and device used to detect, validate and control the passage of coins in the runway of the payphone equipment. The devices used comprise (i) a coin entry sensor CES, (ii) two sets of validator coils VC1 and VC2 with a coin passage sensor CVS, (iii) a false operation or coin held sensor CHS and (iv) coin arrangement equipment involving a coin store sensor CISS and three electric magnets EM1, EM2 and EM3 which control the passage of coins into and out of the coin store.

The validator and coin management control circuitry VCMA consists of circuitry which is used to drive the interface circuitry IA from the micro-processor MPC and to communicate information to the micro-processor MPC from the interface circuitry IA. The equipment used in VCMA comprises (i) a coin entry sensor driver CESD and a coin entry sensor receiver CESR, (ii) coin validator circuitry CV, (iii), a coin held sensor drives CHSD and a coin held sensor receiver CHSR, (iv) an accept coin electromagnet driver ACD, (v) a coin in store sensor driver CISD and a coin in store receiver CISR and (vi) a cash-refund electromagnet driver C/DD.

The analogue and line interface circuitry AILA provides various equipment for use in administering telephone linerelated functions. The functions performed by this equipment are (a) the administration of the audio route, (b) a telephone line interface allowing signals to be injected into the telephone line and signals on the telephone line to be recognised by the payphone, (c) a line swiching unit allowing the payphone to handle telephone calls, (d) a multifrequency-loop disconnect signalling unit allowing either m-f signalling or dial-impulse signalling to be provided to the line when setting up outgoing calls (e) a ringing current detector for detecting ringing current when an incoming call is made to the payphone (f) a line insulation test detector arranged to detect that the line insulation for the telephone line connected to the payphone is being tested at the exchange, and (g) a battery regulator. Interfacing to the analogue and line interface circuitry are a number of discrete components which are either external signal generating devices or the like. Typically these components are (i) the line terminal block ITB, (ii) the telephone handset H/S, (iii) the handset switch HSS, (iv) a charge pulse detector CPU, (v) a call follow on button FOB, (vi) an audible incoming call indicator AICI and (vii) the battery BAT.

The keypad and display K/P provides the interface into the micro-processor for these functions allowing a caller to key up the required number which is then passed by the microprocessor to the dial signalling unit in the analogue and line interface circuitry AVILA. The display is used to provide information to the user on the progress of a call including for example the remaining credit available.

The micro-processor MPC is used to control and coordinate the entire activities of the pay phone and it will be appreciated that the micro-processor is effectively at the centre of a star network with bus connections B1, B2, B3 and B4 to points of the network where the validator and coin management control circuitry VCMA, the analogue and line interface circuitry AICA and the keypad-display K/D are positioned. Because of this construction the micro-processor MPC is in a position to control the activation and de-activation of all or parts of the payphone.

Typically each individual equipment within the points of the star network is provided with a power-on switch which is controlled by the micro-processor so that when the corresponding equipment is not in use the micro-processor may power-down that part of the payphone to concerve upon the energy drain from the battery BAT which is line-charge-powered only. In Fig.

1 leads CESVO, VR, VUNR, CHDVO and CISVO indicate voltage on-off control leads which are used under micro-processor control to regulate the powering-on or off of the corresponding equipments. Similarly some of the functions controlled by the analogue and line interface circuitry AILA can be powered down when the payphone is idle. For example, the audio amplifiers in the audio route can be powered-off as can the dial signalling unit and some of the line switching functions. Similarly the charge-pulse-detection equipment CPD, and the audible incoming call indicator can be powered down. However, the line interface equipment and the handset switch detection equipment requires to be powered-up at all times.

When the telephone is not being used as mentioned above all logic circuits are powered down, except for a small section of monitoring circuitry and the CMOS memories which provide the long term data store. Various events will automatically switch the system power on: 1. Handset removed from the hookswitch.

2. An incoming call detected.

3. A request for an automatic "fault report" from the monitoring circuitry.

When the CPU has started processing after power up it will check which 'power up' event has occured and carry out the necessary actions.

The CMOS memory mentioned above will hold all cash totals (records) and all charging parameters and free call numbers which are programmed via the external programming unit into leads PI. The ON hook charging switch takes its base current directly from the line, and a bias resistance (1 Meg Ohm) will appear across the line during any insulation tests. Protection against line transients is accomplished by the use of two gas discharge surge arresters and a resistor - zener combination. The batteries used are Nickel - Cadmium with a capacity of 500 mAH so that the maximum charging current that will be experienced when the payphone is situated close to the exchange will not exceed the rated continuous charge current of the batteries.

PAYPHONE OPERATION - COIN ENTRY Coin entry is made via a single slot for all coin denominations of the four coin set. Provision may be made later for any anticipated extension to the coin set range or introduction of a completely new coin set.

VALIDATION PROCESS Coins subjected to the validation process pass along a coin runway and their location relative to the validator are detected by opto-electronic sensors (designated sensors CES and CVS in Fig.

1). Validated coins may only pass into the coin store through coin diversion arrangements responsive to the operation of electromagnet EM1. Non-operation of electromagnet EM1 will result in the coins being directed to a refund channel. Under the validation processs two interrelated tests are made on each coin. The first test provides a measurement which gives an indication of the general bulk and alloy characteristics of the coin whilst the second test provides a relatively precision measurement indicative of the value of the coin. The concept of the validation tests provides for apparatus temperature variations over the specified range. Coins failing the validation process are immediately refunded by the non-operation of electromagnet EM1. It is noteworthy that most conceivable circuit or component malfunctions will result in the immediate refund of any coins inserted.Validated coins diverted into the coin store are retained against the subsequent determination process of encashment or refund unless the coin store becomes full in which case, the coin at the front of the queue will be cashed if, when a further coin is inserted, credit to the value of the coin has been used during the call.

COIN MANGEMENT On termination of a call, by returning the handset to its rest, the payphone calculates which coins to accept and which to refund (from their value and relative position) in order to give "best change" to the user. The cashed coins are assigned a weighted value according to their size and these values are added to an accumulative total (of all previous calls) held in memory and it is this accumulative total which gives an indication of the cash container 75% Full and 100% Full. It is this information which forms part of the Fault Reporting Message. The monetary value of the encashed coins is also added to an accumulative "cash cointainer contents" total (this too is held in memory) and it is this accumulative total which is sent to the appropriate accounting centre on removal of the cash container.Opto sensor Cl55 is strategically positioned so that it monitors the first position in the coin store and detects the presence of a coin. It is used to immobilize the payphone from further chargeable calls, in the event of a malfunction which prevents the payphone from either "cashing" or "refunding" coins. For example, electromagnet failure or coin jamming.

A further sensor is provided (Sensor CH5) which prevents coin manipulation by means of string or the like within the payphone.

The remainder of the operation of the payphone involves the user in using the keyboard to originate outgoing calls which are controlled by the micro-processor software.

The software is structured into a series of modules, sub-routines and interrupts for ease of programming. Typically these modules and sub-routines are: Power-on restart, Main, Background,Line Interface, Tones, Keyboard Interrogate, Display Service, Escrow Interrogate, Timer Service, Coin Acceptor, Charge Handler, End of Call, Power end and Auto Call. Fig. 2 shows the software structure and will be considered later as far as its execution is concerned.

Special sub-routines are provided for (i) cashing a single coin off the escrow, (ii) converting any three bit byte binary number into binary coded decimal, (iii) putting an event from the accumulator into the input stack, and (iv) handling the interrupt routine.

The programm modules are provided in order of priority and a frequency of service in milliseconds as shown in the following table.

INTERRUPTS ORDER OF PRIORITY FREQUENCY OF SERVICE Line Interface 32 ms Coin Acceptor 8 ms Escrow 16 ms Tones 1 28 ms RestSwitch 32 ms Charge Handler 64 ms Timers 64 ms Keyboard 32 ms Display 256 ms The software is organised to operate upon input and output events and these are listed as follows:- OUTPUT EVENTS HEX 01 CONNECT LINE 02 DISCONNECT LINE FOR 1.25s LINE 03 DISCONNECT LINE FOR 12.5s 04 DISC.LINE 05 START/CONTINUE DIALLING 06 AUDIO OFF 10 CLEAR DIGIT START 11 FREE/OP CALL TEST KEYBOARD 12 KEYBOARD OFF 14 KEYBOARD ON 20 DISPLAY OFF 21 DISPLAY FLASH 00.00 22 DISPLAY CREDIT DISPLAY 23 INSERT MONEY ON 24 999 CALL ONLY ON 25 DISPLAY CASHBOX CONTENTS () 26 TEXTS OFF 30 COIN ACCEPTOR OFF CACCPT 31 COIN ACCEPTOR ON 40 CASH/REFUND 41 CASH EVERYTHING ESCROW 42 MINIMUM CALL CHARGE REQUEST 44 ADD COIN VALUE TO O.C.E. STACKS 48 CASH ALL WITH 3 SEC DELAY 60 TONES OFF 61 I DENT TON E ON 62 CREDIT LOW TONE ON TONES 63 START/CONTINUE COINTONES 64 N.U. TONE ON 70 END OF CALL ROUTINE SERVICE 81 1 SECOND TIMER START 82 11 SECOND TIMER START TIMERS 84 40 SECOND TIMER START 88 3 SECOND TIMER START CHARGE 90 CALL CHARGE HANDLER OFF HANDLER 91 RESET a TURN ON CALL CHARGE HANDLER POWER CO POWER - DOWN ROUTINE CALL END AUTO C1 AUTO-CALL ROUTINE BACKGROUND C2 INSULATE TEST ROUTINE CALL INPUT EVENTS HEX 01 AUTO CALL 02 INCOMING CALL 03 INSULATE POWER UP 04 HANDSET LIFTED (HS) 05 HANDSET DOWN (HS) 06 CHARGE PULSE 07 CREDIT LOW 08 STOP CREDIT LOW 09 CREDIT EXPIRED OA FREECALL OB OPERATOR CALL OC N T FREE/OP CALL OD COIN VALIDATED OE LINE RECONNECTED OF F.O.C.PRESSED 10 F.G.C. RELEASED 11 DIGIT KEYED 12 FOURTH DIGIT IN MIN CALL CHARGE 13 THIRD DIGIT IN 4 COIN COLLECTION COMPLETE 15 LSCROWFULL 16 SPACE IN ESCROW 17 MIN. CALL CHARGE AVAILABLE (MCA) 18 OPERATOR ANSWER SIGNAL RECEIVED 19 ONE OR ELEVEN SECOND TIMER FINISHED 1A FORTY SECOND TIMER FINISHED 1 B NINE-NINE-NINE CALL KEYED 1C FOURTH DIGIT IN WITHM.C.A.

1 D THREE SECOND TIMER FINISHED The above arrangement gives rise to a state node list as follows: STATE NONE LIST 1. POWERED DOWN 2. STANDBY 3. HANDSET LIFTED O.G.

4. WAIT FOR CALL TYPE TEST RESULT 5. WAIT FOR 4th DIGIT 6. AWAIT CALLED SUB ANSWER 7. CALLED SUB ANSWER, 1st METER PULSE, CALL IN PROG 8. CREDIT LOW INSERT MORE COINS 9. CREDIT EXPIRED 10. WAIT FOR F.O.C. RELEASE 11. CASHING 12. WAIT FOR RECONNECT 13.1/C CALL 14. ALL COINS CASHED 15. WAIT BEFORE POWER DOWN 20. FREE CALL 30. OPERATOR CALL a INDENT. CALL 31. WAITING FOR F.O.C. RELEASE 32. WAITING 33. OPERATOR CALL TO TONE 34. CASHING BEFORE OPERATOR CALL 36. CASHING COINS 37. CASHING COINS 50. AUTO CALL 59. AUTO/999 CALLS 60. INSULATE TEST The work place memory map for such an arrangement is shown in Fig. 3.

The method of programming is best described by taking an example of one section, this is from the "Rest State" to "Hand set Lifted" (State 03).

It may be seen (In Fig. 3) that there are 4 input events which can cause the Micro Computer to 'Power on Restart' (PORS) There are: 01 Auto Call An automatically generated call to report, for example a fault or coin box full.

02 Incoming call - Ringing detected.

03 Insulate Power Up - Insulate Line Test conditions detected.

04 Handset Lifted i.e.Normal O/G Call.

Assuming that PCRS has been caused by Handset lifted (Fig. 3). This segment of Program sets various pointers in the workplace memory (RAM), clears this memory and does various Housekeeping activities.

When 'PORS' is completed the System State is set to 02 which together with Input Event 04 (Handset Lifted) in the input event stack (set by the Instack sub routine), causes 'Main' to look up the output event table.

'Back ground' then looks at the first event loaded in the output event stack - in this case 01.

The next program module is 'Line' so it acts on this to send a bit via an output latch to switch on the line transistors on the Line Interface Printed Circuit Board. The remaining program modules are then cycled through and return to 'Back Ground' (BCKGRD) the next output event is set in the event stack, in this case 21 which refers to 'Display', the processors step through to the Display Module and actions this instruction. This sequence is repeated until the output event stack is exhausted and then the next system State is set.

If an interrupt occurs, it is handled at the end of the module of program then being used. The delay before handling an interrupt does not exceed 100 microsecs.

At the start of each program module operation the micro-processor is arranged to power up the required electronics for the particular function and at the completion of each program module the electronics is powered down to the stand by conditions.

The above description has been of one embodiment only and is intended to be exemplory only. Alternative arrangement will be seen by those skilled in the art for example although a micro-processor has been used descrete logic arrays could have been produced to achieve the program modules of the embodiment shown.

Claims (6)

1. A coin operated telephone instrument including means for monitoring for incoming calls and means for handling incoming calls and outgoing calls, wherein the means for handling incoming calls and means for handling outgoing calls are adapted to be powered down when the telephone is idle and are arranged to be selectively powered-up as required when the instrument is taken into use.

2. A coin operated telephone instrument according to claim 1 in which the means for monitoring incoming calls and means for handling incoming and outgoing calls are controlled by a micro-processor.

3. A coin operated telephone instrument according to claim 2 in which the micro-processor is connected through a bus system to act as the centre of a star network and the points of the star network are connected to (a) coin validator and coin management equipment (b) analogue and telephone line interface equipment and (c) keypad and display equipment and each equipment on the points of the star include micro-processor controlled power switching arrangements allowing the micro-processor selectively to power-on or off the equipments at the points of the star.

4. A coin operated telephone instrument according to claim 3 in which the micro-processor operates under the control of software which is structured into a series of program modules which are handled on an interrupt basis and include steps for powering on and powering off as required the equipment they administer.

5. A coin operated telephone instrument according to claim 4 in which the micro-processor includes a memory and part of the memory is used to store a state map and each program module is arranged to be activated by an entry in an input event stack and to mark an output event stack according to the module required to process the result of that module.

6. A coin operated telephone instrument substantially as herein described with reference to the accompanying drawings.