DEVICE FOR CONTROLLING DELIVERY OF A UTILITY

Abstract: The invention concerns a device (10) for controlling the delivery of a utility e.g. electricity to a subscriber. The device comprises a code generator (32) operating according to a certain algorithm, means (20) for loading a value code by the subscriber, means (34) for comparing the generated code and the entered value code and an element (44) for cutting off the supply of a utility. When the subscriber has paid the invoice of the utility company, the utility company supplies the subscriber with a value code which has been generated according to the same algorithm as the code generated in the device. The value code comprises a period length code which bears a relation to the period which has been paid for. The subscriber loads the value code supplied by the utility company into the device (10) where the codes are compared. If the codes coincide, supply of the utility will be continued for the next period. If the codes do not coincide, the supply of utility is cut off automatically.

Description: The present invention relates to a device for controlling delivery of a metered utility such as electric energy, gas, water etc. Generally the domestic supply of energy utilities such as electricity, gas or water etc. is performed through a meter which is provided at the input of the supply installation fitted in the user's house. The meter is used for measuring the quantity of electricity, gas, water etc. which is consumed by the subscriber. This measurement is the basis for the facturation of the supply of the utility. The company which sells electricity, gas or water checks the quantity of utility displayed by the meter and an invoice based on this measured utility consumption is sent to the subscriber. However, the meters are generally provided inside the subscriber's house, so the checking of the meters is time consuming for the company because it is not always possible to have access to the meter. As a result, the checking of each meter is only performed once or twice per year. The subscriber receives an invoice each month or every two months but the amount of the invoice is based on an estimated consumption and not on a checked consumption. For example, if the checking of the meters is performed only once per year, the subscriber will receive eleven invoices in an amount corresponding to 1/12th of last year's checked comsumption and a twelfth invoice the amount of which is equal to the difference between the present year's consump­ tion effectively measured and the cumulated amount of the eleven invoices already sent to the subscriber. However, it is very difficult, and in any case expensive, for the company to check the payment of the monthly invoices and to cut off the supply of utility to the subscriber if he has not paid the invoice at the prescribed date. Several systems have been proposed to overcome this difficulty. One such system, disclosed in EP-A-0 015 120, comprises an electricity meter which is provided with a switch, a computer, a modem and an associated Keyboard. When the user, in whose house such a meter is installed, pays his electricity invoice remotely by means of the keyboard, and the amount is received by the electricity company sends a coded signal to the electri­ city meter of said user. The received signal is decoded and entered into a microprocessor, which on its turn keeps the switch in its closed position so that the user may continue to use electricity. However, when the user has not payed his elec­ tricity invoice, the company will not send a coded signal, and after elapsing of a certain credit period the switch opens so that the user is deprived of the use of the elec­ tric energy. Further devices are known, which make use of a device for controlling the delivery of gas, water or electric energy comprising: - means for generating a first code; - means for entering a second code; - means for comparing said first and said se­ cond code supplying an enabling signal when said first code and said second code coincide; - switching means responsive to said enabling signal for connecting the supply of said utility; - said generating means generating said first code according to a secret algorithm; - said generating means generating a new value of said first code upon coinciding of the preceding value of said first code with the value of the second code; - a counter; - a comparator connected with said counter and supplying said enabling signal to said switching means until said counter has reached a certain counting position, and - a memory, the contents whereof are transferred to said counter each time said memory receives an enabling signal from said comparing means. Such a device is disclosed in EP-A-0 151 874. When such a device is installed with a user, he will be provided with a magnetic coded card provided with a value of said second code to be inserted in the apparatus. When inserting the card, said second code is read by said apparatus, stored in the second memory, and compared with the first code. When both codes coincide, an enabling signal is generated and the flow of electricity is released for a certain length of time. Further, the card is returned to the user who then may send it to the electricity company together with payment for the next period. The electricity company will then, after payment is received, send the card provided with a new value of the second code, generated according to the same secret algorithm back to the user. This system requires that the card must be sent to and fro between the user and the elec­ tricity company which is cumbersome. Alternatively, the user may personally call at the offices of the electricity company and present the card for the generation of a new code, together with the payment, which is inconvenient either. In both cases there is a considerable chance that the card gets lost. Further from EP-A-0 063 893 a system is known, wherein every time the user pays for a certain amount of energy he receives a coded card, which after insertion releases the use of a certain amount of energy. After the card has been read, its code is extinguished to prevent further use. As this code continues to be the same there is a considerable chance that counterfeit cards may be used, making the system vulnerable to fraud. It is the object of the present invention to provide a device for controlling the delivery of a utility which can be operated at a low level of costs, wherein the negligence of the user does not have the chances that the supply is cut off inadvertentbly and which is difficult to fraud. This aim is reached by such a device, in which the means for entering said second code is a keybord; means are provided for inhibiting said enabling signal to the switching means upon elapsing of a period of time after the start of the enabling signal; and a clock signal from a clock circuit is applied to the counter. In a system employing an apparatus according to the present invention the user is informed of the new value of the second code. He normally enters this code into the apparatus and if the right code has been entered he is en­ sured of a supply for a certain period of time. As the value of the code is changing continuously the chances that fraud will occur are negligible. Further the costs of the apparatus are low, especially in comparison with the apparatus equipped for communication with a central compu­ ter. Further there are no chances of cards getting lost, as the user may key in the new value of the code directly after delivery. In the field of postage meters it is know from US-A-3.792.446 to use a code recharge the postage meter by means of a group of keys According to this system the postage meter comprises a lock which can be unlocked to recharge the registers of the meter. Whenever a user of such a postage meter wishes to recharge his postage meter, he enters the amount to be re­ charged and he phones a central computer of the postal autho­ rities and communicates his account number and the number of the postage meter for identification purposes. When both numbers can be traced back in the memory of the computer, the computer checks whether they are valid. Then, asked by the voice synthesizer of the computer, the user communicates the reading of the registers of the postage meter, and the amount to be recharged. After checking those readings with the rea­ dings of the previous recharching procedure of the meter, the computer checks the caller's account whether he has suffi­ cient credit balance to pay for the increment of postage. As­ suming that the result of these checks is satisfactory, the computer is ready to provide the new combination for the pos­ tage meter concerned. This combination is dependant on the combination of the previous recharging procedure and conse­ quently the identification of the postage meter and on the amount to be recharged. The specification indicates that a random number generator can be used to provide the codes. Such a random number generator has to be provided both in the computer and in the postage meter. After issuing the combination, by means of the voice synthesizer of the computer, the user enters this combination into the postage meter, where it is compared with the combination generated within the postage meter. If both combinations coincide the postage meter is recharged. Postage meters are portable devices and, consequently, can be transferred to other locations. Hence, the identification of the authorised user of the postage meter and/or the postage meter per se is important, to avoid that unauthorised persons have access to the account of the user of the postage meter. In the case of the present invention, there is no need to identify the proper user, as the location of the de­ vice is usually fixed in the proximity of utility counter. Consequently, there is no flow of information from the user to the utility company. This difference is further emphasised by the fact that in the case of US-A-3.792.446 the recharging of the pos­ tage meter is triggered by the user of the postage meter. If he de­ tects that the remaining balance to be used for postage is nearing zero, he will start the procedure by phoning the com­ puter of the postal authorities. In the case of the present invention, the utility company will trigger the procedure by sending an invoice to the user. After paying the invoice the utility company commu­ nicates the combination or code to the user. Further difference resides in the moment at which the calculation of the following combination according to the random sequence takes place. In the case of US-A-3.792.446 this takes place only after the user has entered the amount of the recharging into the postage meter, as the next code is dependent on that amount, while in the present invention this is calculated directly after the successful comparison of the preceding procedure, as the user does not have to enter any amount, of which the code is variable. This is due to the fact that in the situation according to US-A-3.792.446 the user can choose an amount, while in the present invention the amount of utility is either fixed or can be determined by the utility company, but not by the user. Other features and advantages of the present inven­ tion will be better understood by reading the following des­ cription of preferred embodiments of the invention in view of the accompanying drawing wherein show: Fig. 1: a perspective view of a first embodiment of the invention; Fig. 2: a diagram of the first embodiment of the invention; Fig. 3: a diagram of a second embodiment of the in­ vention; Fig. 4: a diagram of a third embodiment of the in­ vention; and Fig. 5: a flow chart showing the operation of the device of Fig. 4. Fig. 1 shows a perspective view of a first embodi­ ment of a device 10 for controlling the delivery of electric energy together with a KWh-meter 11. The control device comprises a keyboard 20 including push buttons 22 and an enter push button 24 and a display 36 showing the number of days that electricity supply is assured with the present code. The control device comprises further a green LED 37, a red LED 38 and an emergency push button 39. In the normal situation, when the user has the disposal of electricity for at least the next five days, the green LED 37 emits light continuously and the red LED 38 is extinguished. When the period of disposal is less than five days the green LED 37 emits light intermittently to warn the user. The user can then press the emergency button 39 which will extend the period of disposal by seven days. It is thus possible that the credit (i.e. the number of days which has been paid for) is negative in case the emergency button 39 has been pressed. To show this situation the red LED 38 emits light continuously. When the period of credit has elapsed and the supply of power thus has been cut off, the green LED 37 goes out completely and the LED 38 emits light intermittently. The purpose of this feature is to show whether the power has been cut off or whether there is a general power failure. Fig. 2 shows a diagram of the first embodiment of the control device 10. According to this embodiment the control device 10 comprises discrete logic circuits for performing the various functions. The purpose of this first simplified embodiment is mainly to clarify the invention. The control device which is numbered 10, comprises a first terminal 12 for receiving the domestic electric signal (50 Hz) for clock purposes. The terminal 12 is connected to a filter circuit 13, the output of which is connected to the input of a dividing circuit 14. The circuit 14 divides the number delivering one pulse for each period of 1/10th of day. The 1/10 day signal is applied to the down input 16 a of an up-down counter 16. The control device 10 also comprises the keyboard 20 with push buttons 22 corresponding to Figs. 0 to 9 and an "enter key" push button 24, already referred to in the description of Fig. 1. The keyboard 20 is connected to a decoder 26. The decoder 26 performs two main functions. The first one is to convert the electric signals delivered by the keyboard 20 into digital signals corresponding to the push buttons 22 which are pressed. The second function is to treat the number entered via the keyboard 20 by performing a first predetermined secret algorithm. The entered number is called "value code". This number includes a period code, a period length code and a control number. By performing the first algorithm it is possible to decode from the value code one period code and one period length code. The decoded period code is stored in "period code" memory 28 and then period lenght is stored in a "period length" memory 30. The control device 10 further comprises a generator 32 for delivering numbers according to a second predetermined secret algorithm and an initial number value. In fact these numbers correspond to the successive period code to be entered into the control device. The signal delivered by generator 32 is applied to a first group of inputs 34 a of a comparator 34. A second group of inputs 34 b of comparator 34 is adapted to receive the "period code" stored in memory 28. Comparator 34 compares the data applied at its inputs 34 a and 34 b . If these two data are identical,an output 34 c of comparator 34 delivers a control signal which is applied to the enabling input 30 a of the memory 30. When the control signal is applied to the input 30 a , the period length data is applied to the up input 16 b of the counter 16. That means that a number of pulses equal to the number of 1/10th of a day contained in the period length memory 30, is added to the contents of the counter 16. Considering again comparator 34, if the data applied on its two inputs 34 a and 34 b are different, an error pulse is emitted by the output 34 d of the comparator 34. This error pulse is counted in an error counter 40. When the contents of the error counter 40 become equal to a predetermined number (i.e. 4), the counter 40 delivers a blocking signal applied to the decoding circuit 26. Referring back to the up-down counter 16, it is shown that its output 16 c is connected to a comparator 42. The comparator 42 compares to zero the contents of counter 16. If the contents of the counter 16 become equal to zero or negative the comparator delivers a control signal for opening a relay 44 so that the supply of electricity to the subscriber is interrupted. By pressing the emergency push button 39 the contents of the counter 16 are being compared with minus seven instead of with zero so that in this situation the period of credit is extended by seven days. When a further payment is made and the next value code is inserted, the contents of the counter 16 are increased by the number corresponding to the relative period code. At the same instant the emergency state is erased so that the contents of the counter 16 are again compared with zero as was the case before pressing the emergency push button 39. Finally the control device includes an initialization circuit 46 for supplying the generator 32 with an initial period code. The operation of the control device of Figs. 1 and 2 is as follows: When the subscriber has paid for the next month or next period, he receives a new value code. He enters this value code by means of the keyboard 20 and he presses the enter key push button 24. The decoder 26 processes this number on the basis of the algorithm and elaborates a length period code which is stored in memory 30 and period code data which is stored in the memory 28. The data stored in the memory 28 is compared with the data delivered by the generator 32. If these two data are identical, the comparator 34 delivers an enabling signal so that the period length data is transferred into the counter 16. As a result the counter 16 is increased by a number corresponding with the period which has been paid for. The memory 28 and the memory 30 are cleared and the generator 32 is controlled for elaborating a new period code based on said algorithm. As a result the control device 10 is ready for receiving a new value code for the next supply period. If the data applied to the inputs 34 a and 34 b of the comparator 34 are not identical, the error counter 40 is incremented by one. Then the subscriber enters again a number which is deemed to be the correct value code. The same steps are performed again until either the result of the comparison is correct or the number of erroneous attempts counted by the error counter 40 equals four. This means that the subscriber does not have the disposition over the correct value code, so that either the subscriber has been supplied with a wrong value code or the subscriber has not paid and has entered numbers by hazard. It is of course also possible that the subscriber makes subsequent mistakes. To avoid further attempts the entry of further numbers is blocked for one hour. Fig. 3 shows another embodiment of the invention, which differs from the embodiment shown in Fig. 2 in that the contents of the memory 30 relate to a certain amount of electric energy, and not to a certain length of time. Consequently the consumed energy has to be measured by an electricity meter device 15. Said electricity meter device 15 supplies pulses to the counter 16, the frequency of said pulses being proportional to the amount of electric energy being consumed. In this second embodiment the value code comprises an energy value instead of a period value. This energy value is - after decoding by decoder 26 - stored in memory 30, from where it will be transferred to the counter 16 when the relative period codes coincide. The other elements of this embodiment are identical to those belonging to the embodiment shown in Fig. 2. Referring now to Figs. 4 and 5 another embodiment of the invention will be described in more detail. As the main part of this embodiment is a microprocessor, the following description will mainly refer to the flow chart of Fig. 5. According to this second embodiment the control device comprise a keyboard 102 including push buttons 104 corresponding to figures 0 to 9 and an "enter key" push button 106. The device also comprises a display panel 108 having two display cells. As will be explained hereafter the display panel 108 is used for displaying the amount of consumptiom days still allowed. The control device further comprises a current relay 110 for controlling the electricity supply line 112. Finally the device includes an electronic circuit 114 including a microprocessor 116, a program memory 118, a system watchdog 120, a phase lock loop circuit 122, a rectifier 124, a supply watcher circuit 126 and a non-volatile memory 128. The input 130 of the microprocessor is connected with the keyboard outputs for entering into the microprocessor the number corresponding to the pressed push buttons 104. The output 132 of the microprocessor 116 is connected to the display panel 108 for driving the display elements. The output 134 of the microprocessor 116 is connected to the relay 110 for controlling the state of this relay. The microprocessor is fed by the network through the rectifier 124. The network supply is also applied to the phase lock loop circuit 122 for delivering a pulse signal having a substantially constant period. This signal is treated by the microprocessor 116 for generating the 1/10th of a day pulses. The non-volatile memory 128 can be activated by the supply watcher for storing the most important data in the case of failure of the electricity power supply. Referring now to Fig. 5, the normal operation of the control device will be described, that is, when the new period code is stored in the memory of the device, and the subscriber has to enter the new value code he received after having paid the corresponding amount of money. The program of the microprocessor 116 is at the step 200 awaiting for the input of a value code. The subscriber enters his value code by means of the keyboard 102 (step 202). A first test is performed on the entered number for controlling the number of figures of the entered value code (step 204). If this number is equal to 8, the program goes on. If this number is different to 8, the-program returns to the step 200. If the result of the test 204 is positive, an error counter program is incremented by one (step 206). Then the value code is decoded to a corresponding value code (step 210). This value code is tested in 212 to verify that the value code obeys the control number. If the result of test 212 is negative the program returns to the step 200. If the result of the test of positive the value code is decoded, according to a predetermined algorithm, to yield a period code and a period length code (step 214). Then according to step 216, the decoded period code is compared with the period code stored in the memory of the control device. If the two period codes are identical the program goes on. If they are different, the program returns to the initial step 200. Then the step 218 of the program decodes the period length from the period length code elaborated at the step 214. A counting sub-program is incremented at step 220 with a number new allowed days corresponding to the number of 1/10th of days included in the period length. A detection sub-program 222 tests permanently the number of 1/10th of days still allowed. If the number of 1/10th of days is positive the relay 110 remains closed and electricity is supplied to the subscriber. If the number of 1/10th of days is negative the relay is opened. As shown in Figs. 1 and 4 the number of supplying days still available is displayed by the display panel 108. It is to be underlined that if the results of the tests 212 or 216 are negative the program returns to the initial step 200. That means that each time the subscriber has to enter a new value code. However the number of erroneous enters of value code is counted by the error counter function 206. If the contents of this counter function become equal to 4 the next enter will be considered as a number entered by hazard, and the program is put in stand by for one hour. As a result the subscriber who has not paid for electricity supply can enter only three hazard numbers assumed to be value code. Obviously it is very unlikely that one of these hazard numbers equals the correct value code. Now the initialization of the control device will be explained i.e. the entering of the first period code by the employee of the utility company when the device is used for the first time. With a personal computer or the like, the employee of the utility company will elaborate an initializing code which is to be entered in the memory of the control device and a first value code corresponding to this first period length. Preferably this period length corresponds to the number of days of the month which are left when the electricity meter is installed. The initializing code is elaborated with three numbers, for example an "apparatus number", a "client number" and a starting number having the same number of figures as the period code. These three numbers are processed in accordance with a first predetermined algorithm for delivering the first period code. This first period code is also stored in the program memory of the control device. With the personal computer the first value code is also elaborated. For this purpose, the number of days of the considered period is processed with a second predetermined algorithm for elaborating a period length code. This period length code and the first period code are processed in accordance with a third predetermined algorithm for generating a code. Finally, this code is processed with a fourth predetermined algorithm including a control figure for generating the value code. It is to be understood, that the program memory of the control device includes the predetermined algorithms so that the control device can elaborate the successive period codes starting from the preceding period code, the "client number" and the "apparatus number". Similarly the utility company can elaborate with the personal computer the successive value codes which the subscriber receives when he pays the required amount of money.

Claims: 1. Device for controlling delivery of gas, water or electric energy comprising: - means (32) for generating a first code; - means (20) for entering a second code; - means (34) for comparing said first and said second code supplying an enabling signal when said first code and said second code coincide; - switching means (44) responsive to said ena­ bling signal for connecting the supply of said utility; - said generating means (32) generating said first code according to a secret algorithm; - said generating means (32) generating a new value of said first code upon coinciding of the preceding value of said first code with the value of the second code; - a counter (16); - a comparator (42) connected with said counter (16) and supplying said enabling signal to said switching means (44) until said counter (16) has reached a certain counting position, and - a memory (30), the contents whereof are trans­ ferred to said counter (16) each time said memory (30) receives an enabling signal from said comparing means (34); characterized in that - the means for entering said second code is a keybord (20) and - means (16, 30, 42) are provided for inhibiting said enabling signal to the switching means (44) upon elap­ sing of a period of time after the start of the enabling signal; - a clock signal from a clock circuit (14) is applied to the counter (16). 2. Device according to claim 1, characterized by said second code comprising a period length code, and by means (26) for transferring the number corresponding with the appropriate period length to said memory (30). 3. Device according to claim 1 or 2, characteri­ zed by displaying means (36), displaying the remaining length of time until disconnecting the supply of said utillity. 4. Device according to one of the preceding claims, characterized by the counter (16) being a down coun­ ter and said certain counting position being zero. 5. Device according to one of the preceding claims, characterized by means (26) connected to the entering means (20) for decoding said second code according to a secret algorithm. 6. Device according to claim 5, characterized by the decoding means (26) comprising means for testing the entered second code by means of a check digit contained in said second code. 7. Device according to one of the preceding claims, characterized by means (40) for inhibiting further entry of codes after entering a number of defective codes. 8. Device according to one of the preceding claims, characterized by means for overriding the inhibiting signal supplied to the switching means for a limited period, which means can be put into use only once in every period by pushing an emergency button (39). 9. Device according to claim 8, characterized by indicating means (37, 38), showing whether or not the emer­ gency button (39) has been used and whether the supply of utility has been cut off. 10. Device according to one of the preceding claims, characterized by means for resetting and starting the device after a failure. 11. Device according to one of the preceding claims, characterized by means for periodically copying the contents of the memories in a non-volatile memory. 12. Method of using a device according to one of the preceding claims, characterized in that an initializa­ tion value of the first code is entered (into 46) by the company sup­ plying the utility and that the subsequent values of the first code are calculated from the preceding value of said code.

Inventors: BOES, IZAAK CORNELIS
Applicants: METERFABRIEK SCHLUMBERGER B.V.
Application year: 1985
Main classification: G07F15
IPC codes: G07C9, G07F7, G07F15