Commodity metering systems

Abstract: A multi-rate commodity metering system comprises an electronic key containing an EEPROM, and a meter for metering the commodity and having a receptacle for receiving the key. The meter also contains a real-time clock. The key can operate as a prepayment device, a programming device and a meter-reading device. Thus the key is taken to the commodity supplier's premises, where, in return for a payment, a credit signal representative of the payment is stored in the key. At the same time, a new program for the meter, ie new times for switching between rates and new prices per unit of commodity for each rate, together with the date and time at which the new program is to come into operation, can also be stored in the key. Then, when the key is inserted in the receptacle in the meter, the payment signal and the new program are entered into the meter. Additionally, the current set of meter readings (ie the respective readings for each rate) are read into the key, along with the date and time. The next time the key is presented at the supplier's premises for the entry of a new credit signal, the meter readings, and the date and time they were entered in the key, are read from the key.

Description: This invention relates to commodity metering systems, and is more particularly but not exclusively concerned with a multi-rate prepayment electricity metering system. In United Kingdom Patent Application No. 8401932 (Publication No. 2153573A), there is described and claimed a prepayment electricity metering system in which an electronic key containing a memory co-operates with a receptacle in an electricity meter to control the supply of electricity to a consumer. It is an object of the present invention to provide a commodity metering system based on such an electronic key and receptacle and having enhanced facilities, either in addition to or instead of a prepayment facility. DD-A-150 958 relates to a prepayment system in which memory locations in an external non-volatile memory device are marked each time a predetermined energy amount has been counted. According to the present invention, there is provided a prepayment system for a metered commodity, the system comprising a key with a memory and a meter for metering the commodity and including a receptacle for the key with a circuit for allowing access to the commodity only when authorised by predetermined data in the key memory, wherein the meter further includes memory means for storing at least one signal representative of an accumulated amount of the commodity used, and means responsive to an insertion of the key into the receptacle to read said at least one commodity amount signal into the key memory. Preferably, said meter also includes a real time clock for producing a signal indicative of real time, said reading means being arranged to read said real time signal into said key memory with said at least one commodity amount signal. In this specification, the expression "real time" means the actual time, ie date and time-of-day. The invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a block diagram of part of a multi-rate prepayment electricity metering system in accordance with the present invention; Figure 2 is a block diagram of the remainder of the system of Figure 1; Figures 3 and 4 together form a flow chart useful for explaining the operation of the metering system of Figures 1 and 2. The prepayment electricity metering system of Figures of 1 and 2 has many elements in common with the prepayment system described in the aforementioned United Kingdom Patent Application No. 2153573. Thus the system comprises a key 10 containing a non-volatile memory such as an EEPROM, and a multi-rate electricity meter 11 having a receptacle 12 for receiving the key 10. Associated with the receptacle 12 is a receptacle circuit 14 for allowing access to the electricity only when authorised by predetermined data in the key memory. The data in the key memory is unique to the key 10 and to the corresponding receptacle 12 and includes a code specifying the quantity of electricity to which access is allowed, that is, the amount which has been paid for in advance. The receptacle circuit 14 includes a receptacle memory 16. On the first insertion of the key 10 into the receptacle 12, the memory 16 stores data representing the quantity of electricity which has been paid for in advance. The quantity data is stored in association with data identifying the key 10. On subsequent insertions of the key 10, and/or when an insertion lasts more than a predetermined time, the quantity data is modified so as to decrement the represented quantity of electricity by a predetermined amount and a metering device 18 is set to allow the supply of the predetermined amount of electricity. The key 10 has a read/write memory which, for convenience, is an EEPROM. When the key 10 is inserted in the receptacle 12, a microcomputer 20 can read the contents of the key memory through an interface circuit 22 and thereby through terminals within the receptacle which make contact with terminals on the outside of the key 10, connected to the address and data lines of the key memory. The key memory contains three items of control data, in addition to the quantity data. The three control data items are known as KEY NUMBER, KEYMETER NUMBER and KEYPASS. KEY NUMBER is unique to the key and may be simply a serial number for the key or may incorporate encoded information such as the retail outlet from which the key was bought or the date on which it was bought. KEYMETER NUMBER is unique to the meter apparatus and again may simply be a serial number or may be encoded information such as the address at which the meter is installed. On the first insertion of the key 10 into the receptacle 12, the microcomputer stores in the memory 16 data representing the three control data items and the quantity data. This process may be a direct transfer of data from the key memory to the receptacle memory 16, or the data may be processed by the microcomputer 20 before storage. Conveniently, the receptacle memory 16 is also an EEPROM. The quantity data in the memory 16 is then modified to decrement the represented data by a predetermined amount, and the metering device 18 is set to allow the predetermined amount of electricity to flow along the supply line 28. The metering device 18 can be substantially identical to a coin-operated prepayment device, but with the coin-accepting device replaced by a solenoid circuit 24 which is operated by the microcomputer 20. When the solenoid circuit 24 is operated, the user must turn a knob to set a mechanical credit storing device 26 to represent the value of the predetermined amount of electricity, in the same way that a knob is turned in well-known coin-operated devices after a coin has been inserted. The electricity supplied along the power line 28 is measured by a power measurement device 30 which provides a pulse to a tariff circuit 32 each time one unit of power (for instance one kilowatt-hour) is consumed along the line 28. The tariff circuit 32 converts the power unit pulses into monetary unit pulses and partially resets the device 26 each time electricity of a convenient monetary value has been used. When the device 26 is finally reset to its original condition, the electricity supply along the line 28 is cut off, by a switch unit 33 (typically a contactor unit). Alternatively and preferably, the metering device 18 is fully electronic, in which case the solenoid/microswitch circuit 24 can be omitted, and the device 26 can be a reversible counter into which credit is entered as a respective count via the microcomputer 20 and the dotted connection 35, and then decremented by pulses from the tariff circuit 32: for the remainder of this description, it will be assumed that the metering device 18 is of this fully electronic kind. The metering system as described thus far is very similar to that described in the aforementioned United Kingdom Patent Application No. 2 153 573A, and the way in which the key 10 operates in the system as a prepayment key, and in particular the security it provides against fraud, are described in more detail in that application, which is hereby incorporated by reference. However, in addition to operating in conjunction with the prepayment key 10, which is known as a "customer key", in the manner described in the aforementioned United Kingdom Patent Application, the metering system of the present invention also co-operates with the key 10 in an entirely different way, to be described hereinafter, and with a physically similar but electronically more complex key, known as a "meterman" key, which is indicated at 110 in Figure 1. The key 110, in addition to containing a non-volatile memory such as an EEPROM 112, also contains a microprocessor 114 containing a real-time clock 115, and a battery 116. The other principal differences between the metering system of Figures 1 and 2 and that of the aforementioned United Kingdom Patent Application will now be described. Firstly, the metering system is provided with liquid crystal display 34 which is controlled by the microcomputer 20 and can display a plurality of alphanumeric characters, as will hereinafter become apparent. Secondly, the power measurement device 30 of Figure 1 is an electronic device of the kind described in UK Patent No. 1603648, and has an output X which, in addition to supplying pulses to the tariff circuit 32, also supplies these pulses to an electromechanical totalising register 120 (Figure 2), and, via a routing logic circuit 122, to a respective one of N electronic registers (ie electronic memories) 124/1 to 124/N. The respective one of the registers 124/1 to 124/N in use at any given time is selected by an output Y of the microcomputer 20 of Figure 1. To facilitate this, the microcomputer 20 includes a real-time-clock 130, and is associated with a store 132 for storing a plurality of switching times at which the routing logic circuit 122 is intended to switch from one register 124 to the next. The microcomputer 20 continuously compares the time indicated by the real-time clock 130 with the stored switching times in the store 132, and operates the routing logic circuit 122 accordingly. The respective outputs of the registers 124 are connected to an input Z of the microcomputer 20, which can inter alia supply them to the display 34, whereby the respective contents of the registers 124 can be selectively displayed. The tariff circuit 32 comprises an electronic memory containing the respective tariffs appropriate to the various registers 124, each tariff being selected simultaneously with its respective register via the output Y of the microcomputer 20. The credit store 26 also operates an electronic memory, since as already mentioned it is basically a reversible counter, in which credit entered by means of a customer key is stored, and then decremented at a rate determined by the device 30 and the tariff circuit 32. In operation, the meter is loaded via the microcomputer 20, as will hereinafter become apparent, with a program including real time (date, hour, minute, second), the aforementioned switching times and the price per unit of electricity consumed in each successive time period defined between the stored switching times. A consumer inserting a customer key enters credit and obtains electricity generally as described in the aforementioned United Kingdom Patent Application No 2 153 573A (but subject to the minor modifications due to the all-electronic nature of the system and the multi-rate nature of the tariffs outlined above). If it is desired to change the switching times and/or tariffs, two methods are possible. First, if the customer key 10 has sufficient memory available, typically 1K bits as opposed to the 256 bits of early versions of the key 10, then when it is recharged with fresh credit at the electricity supplier's retail premises, as described in the aforementioned application, it is at the same time loaded in the excess part of its memory with the new switching times and tariffs. Then, when the customer inserts the recharged customer key into the receptacle 12 to load the credit, the new switching times and tariffs are loaded into the stores 132 and 32 respectively at the same time via the microcomputer 20. These operations are carried out under the control of the microcomputer 20 in accordance with the flow chart of Figures 3 and 4. Thus the microcomputer 20 first tests for the presence of a key in the receptacle 12 (box 140), and if a key is present, then checks whether it is a customer key (box 142), as indicated by a particular code stored in the key. If the key is a customer key, the microcomputer 20 causes the display 34 to display "TOKEN" (box 144), and then enters the credit stored in the key into the memory 16 (and eventually into the credit store 26) as generally described in the aforementioned United Kingdom Patent Application (boxes 146 to 149). Having entered the credit, the microcomputer 20 then checks whether the key has a 1K memory (box 150). If yes, then as already indicated, that means the key can contain new switching time and tariff data, which has been entered into the key along with a data security check sum. The microcomputer 20 first checks the data security checksum (box 152), and if that is OK, reads the new data into the store 132 (box 154). The second way in which the switching times and tariffs can be changed is by use of the meterman key 110. In this case, the meterman key is loaded with the new switching times and tariffs, at the same time having its real-time clock 115 set to the correct time (date, hour, minute, second). This would normally be done in a device provided specifically for the purpose at the meterman's base in the electricity supplier's premises. Operation of the clock 115 is maintained by the battery 116. Insertion of the meterman key 110 into the receptacle 12 then loads the new switching times and tariffs substantially as already described, but at the same time, also updates the real-time clock 130 in the microcomputer 20 to the correct time. This loading and updating is again carried out under the control of the microcomputer 20 in accordance with the flow chart of Figures 3 and 4. Thus after the key has been identified as a meterman key (block 156), a security protocol check is carried out (block 158), and if the result of this is satisfactory (block 160), the time in the real-time clock 115 is entered into the real-time clock 130 in the microcomputer 20, and then displayed on the display 34 for the meterman to check (block 162). Then the new switching time and tariff data is entered into the store 132 (block 164). In either case, after the new data has been loaded, the contents of the registers 124 are read out into the customer key or the meterman key, as the case may be (see blocks 166 and 168 in Figure 4 and block 170 in Figure 3), and stored as meter readings in the key along with the date and time-of-day at which these readings were read out. In the case where the meter readings are stored in a customer key, the stored readings are read from the key into the credit recharging apparatus at the electricity supplier's premises the next time the customer takes the key there to have its credit recharged. It will be appreciated that where a customer key is also used for reprogramming and meter reading, the frequency at which a meterman has to visit the customer's premises can be drastically reduced, perhaps to as little as once a year. The key 110 can be physically implemented as described in United Kingdom Patent Application No. 86 25 675 (published as GB-A-2 191 883). However, the key need not resemble a mechanical-type key, but can instead be constituted by a "smart card" of the kind which resembles a credit card but has an electronic circuit embedded therein. Also, the meter reading facility can be incorporated in a single rate key operated prepayment metering system. Although the invention has been described in relation to an electricity metering system, it is equally applicable to other commodity metering systems, for example gas or water metering systems.

Claims: A prepayment system for a metered commodity, the system comprising a key (10;110) with a memory (112) and a meter (11) for metering the commodity and including a receptacle (12) for the key with a circuit (14) for allowing access to the commodity only when authorised by predetermined data in the key memory, wherein the meter further includes memory means (16) for storing at least one signal representative of an accumulated amount of the commodity used, and means (20,22) responsive to the insertion of the key into the receptacle to read said at least one commodity amount signal into the key memory. A system as claimed in claim 1, wherein said meter also includes a real time clock (130) for producing a signal indicative of real-time, said reading means being arranged to read said real time signal into said key memory with said at least one commodity amount signal.

Inventors: PATRY BERNARD, VAUGHAN JOHN EDWARD, PATRY, BERNARD, VAUGHAN, JOHN EDWARD
Applicants: SCHLUMBERGER IND LTD, SCHLUMBERGER INDUSTRIES LIMITED
Application year: 1987
Main classification: G07F15
IPC codes: G07F7, G01R22, G07F15