Opening detection device

Abstract

An apparatus (100) is disclosed, the apparatus comprising a housing, the housing comprising a component (201); a cover (301) configured to be positioned on the housing to limit access to the component when the cover is in the closed position; a capacitor (303) and a fuse (304) dimensioned such that the fuse fuses when the capacitor is discharged through the fuse; -a capacitor charging circuit configured to charge the capacitor when the device is powered on; a discharge circuit for discharging the capacitor through the fuse, said discharge circuit comprising a first switch (305) cooperating with a portion (302) integral with the cover so as to prevent the capacitor from discharging when the cover is in the closed position; and when the cover is in the open position, the capacitor can be discharged through the fuse.

Description

Technical Field

[0001] The various embodiments described in this disclosure relate to a device equipped with an open detection feature. This device may be, but is not limited to, an electricity meter. Background Technology

[0002] Consumable meters such as electricity meters are easily tampered with for fraudulent purposes. Once a meter is installed and activated in its place of use, detecting that the meter is open indicates that fraud has occurred—this detection may require relevant operators to verify the information.

[0003] Some known meters offer the ability to detect the opening of terminal covers and / or main covers by using a battery to continue powering a microcontroller when the meter is no longer powered. The microcontroller can then continue monitoring the status of the switches connected to the main or terminal covers. Batteries can also be replaced by high-value supercapacitors, typically 1F, which allows the detection function to remain active for five to seven days. However, these components are expensive, and some operators prohibit the use of batteries in meters. Furthermore, the duration of detection is inevitably time-limited, so given sufficient time, the main or terminal cover can be removed without the risk of detection failure.

[0004] Another known practice is to use a monostable relay with a movable core to detect the opening of the cover that closes the meter box. Another known practice is to use an incremental encoder that reacts to the opening of the cover. However, such solutions are expensive and can be mechanically complex, and specifically, for example, are susceptible to mechanical uncertainties for incremental encoders. Using this last solution, the opening can no longer be detected if the initial value is restored.

[0005] An ideal, simple solution would be to detect the opening of the meter housing even when no power is supplied to it. Summary of the Invention

[0006] The first aspect relates to an apparatus comprising: The housing includes components; a cover configured to be positioned on the housing to restrict access to the components when the cover is in a closed position; a capacitor and a fuse sized such that the fuse blows when the capacitor discharges through the fuse; a capacitor charging circuit configured to charge the capacitor when the device is powered on; and a discharge circuit for discharging the capacitor through the fuse, the discharge circuit including a first switch that cooperates with a portion integral with the cover to prevent the capacitor from discharging when the cover is in a closed position and to allow the capacitor to discharge through the fuse when the cover is in an open position.

[0007] Therefore, once the device is installed and powered on for the first time, it is impossible for the cover to be opened without being detected, even when the device is no longer powered on, i.e., no longer connected to an external power source. If necessary, the energy stored in the capacitor is used only to generate current in the fuse. This allows the detection function to remain active for an extended period.

[0008] According to one or more exemplary embodiments, the discharge circuit is configured to electrically connect a capacitor and a fuse via a first switch, the first switch including a conductive portion configured to make electrical contact when the cover is in an open position and to be moved apart from a portion integral with the cover when the cover is in a closed position, thereby breaking the electrical contact between the conductive portions.

[0009] According to one or more exemplary embodiments, the conductive portion includes two metal strips.

[0010] According to one or more exemplary embodiments, the portion integral with the cover is a protruding member integral with the cover.

[0011] By locating or protecting switches and fuses, the security of equipment can be improved to prevent or at least significantly reduce the possibility of tampering by unauthorized personnel (even if they are very familiar with operating the open detection function).

[0012] For example, the switch and fuse can be placed in a compartment of the housing, which is separated from the portion of the housing accessible by opening the cover by a wall. However, the switch is arranged such that it can interact with a protruding member of the cover, for example, via an opening formed in the wall.

[0013] Advantageously, the size of the opening is close to the cross-sectional size of the protruding member. In this way, a malicious third party cannot access the switch before removing the cover, and there is no time to prevent the capacitor from discharging and the fuse from blowing when the cover is removed.

[0014] Either of these components (switches and fuses) can be placed under appropriate discrete protection. This can also restrict tampering on the printed circuit board. Alternatively, these two components can be selected such that their inherent structure limits tampering with them and, depending on the component, restricts access to, removal, or replacement of the terminals.

[0015] According to one or more exemplary embodiments, the charging circuit includes a voltage source connected to a first terminal of a capacitor via a resistor, the second terminal of the capacitor being connected to ground, and the voltage source being configured to provide a voltage to charge the capacitor when the device is powered on.

[0016] According to one or more exemplary embodiments, the capacitor is in a discharged state before the device is first powered on.

[0017] According to one or more exemplary embodiments, the device includes a second switch controlled by a control signal, the second switch being configured to allow the capacitor to be discharged without passing through a fuse.

[0018] According to one or more exemplary embodiments, the second switch is configured to short-circuit the capacitor in response to a control signal.

[0019] According to one or more exemplary embodiments, the device includes a processor configured to generate control signals under the control of an authorized user.

[0020] According to one or more exemplary embodiments, the device is an electricity meter and the components include electrical terminals of the meter.

[0021] According to one or more exemplary embodiments, the device includes a processor configured to determine whether a fuse has blown and, if so, generate a warning signal.

[0022] According to one exemplary embodiment, the fuse is a screen-printed fuse that is screen-printed on the printed circuit board of the device. This limits the possibility of unauthorized personnel replacing a blown fuse. Attached Figure Description

[0023] The embodiments will be better understood from the following detailed description and accompanying drawings, which are given by way of illustration only and therefore do not limit this disclosure.

[0024] Figure 1 This is a view of a device including a removable cover covering the terminals of a meter, according to one embodiment.

[0025] Figure 2 yes Figure 1 The view of the device shown has had its overlay removed.

[0026] Figure 3 This is a schematic diagram of the first exemplary embodiment.

[0027] Figure 4 This is a schematic diagram of a second exemplary embodiment. Detailed Implementation

[0028] Various embodiments will now be described in more detail by way of non-limiting example, with reference to the accompanying drawings which accompany this disclosure and illustrate certain exemplary embodiments.

[0029] The specific structural and functional details disclosed herein are non-limiting examples. Various modifications and alternative forms are possible with respect to the embodiments disclosed herein. The subject matter of this disclosure can be embodied in many different forms and should not be construed as being limited to the embodiments presented herein as illustrative examples. It should be understood that the embodiments are not intended to be limited to the specific forms described in the remainder of this document.

[0030] In the following description, the same, similar, or analogous elements will be referred to by the same reference numerals. The block diagrams, flowcharts, and message sequence diagrams in the drawings illustrate the architecture, functionality, and operation of systems, apparatus, methods, and computer program products according to one or more exemplary embodiments. Each block of a block diagram or each step of a flowchart may represent a portion of a module or software code including instructions for implementing one or more functions. Depending on certain specific embodiments, the order of blocks or steps may be changed, or the corresponding functions may be implemented in parallel. For all or some blocks or steps, method blocks or steps may be implemented in a centralized or distributed manner using circuitry, software, or a combination of circuitry and software. The described systems, devices, processes, and methods may be modified or added to and / or removed while remaining within the scope of this disclosure. For example, components of an apparatus or system may be integrated or discrete. Similarly, the disclosed features may be implemented using more or fewer components or steps, or even together with other components or by means of other steps. Any suitable data processing system may be used in the specific implementation. Suitable data processing systems or devices include, for example, combinations of software code and circuitry, such as processors, controllers, or other circuitry suitable for executing software code. When the software code is executed, the processor or controller causes the system or device to perform all or part of the functions of the blocks and / or steps of the process or method according to the exemplary embodiments. The software code may be stored in non-volatile memory or on a non-volatile storage medium (USB key, memory card or other medium), and may be read directly by the processor or controller or via a suitable interface.

[0031] This disclosure applies to any device with a housing that includes one or more components arranged behind a cover.

[0032] A “cover” is any part that, when removed, is designed to allow access to certain components of the equipment and, when in the proper position on the housing, prevents such access. In the case of an electricity meter, this could be, for example, a meter cover, but it could also be a terminal cover.

[0033] It should be noted that these exemplary embodiments are not limiting. Specifically, the described functions can be achieved using components other than those illustrated, and of course, fewer or additional components can be used. Furthermore, the different given values ​​are for clarification and may also differ.

[0034] Figure 1 This is a non-limiting example of device 100, which in this case is an electricity meter. The illustrated device includes a housing 101 and a cover 102 positioned on the housing to prevent access to the electrical terminals of the meter. In the illustrated example, the cover 102 is mechanically locked to the housing 101 by means of a locking mechanism 103. The illustrated device includes other components, such as a display 104. The display may be a touchscreen configured to implement a human-machine interface.

[0035] Figure 2 It shows Figure 1 The device shown is without a cover 102. Figure 2 The electrical terminals 201 (phase and neutral) of the meter are shown. For safety reasons or to prevent fraud, these terminals are not accessible when the cover is in the proper position on the meter.

[0036] According to one or more exemplary embodiments, the device includes circuitry for detecting the opening of a cover. The underlying principle of various embodiments is that a capacitor is charged when the device is powered on. When the cover is opened, the capacitor is triggered to discharge by closing a discharge circuit. Discharge occurs through a fuse. The capacitor and fuse are designed such that the fuse blows as the capacitor discharges.

[0037] According to one implementation, the capacitor is typically charged after the device has been powered on for the first time, and then installed in its operating position, as attempts are usually made to detect any fraud from the moment of installation.

[0038] According to one embodiment, when the cover is in the closed position on the housing, the discharge circuit can be closed by means of a switch that remains open through a portion of the cover in order to prevent contact with the component. The switch is configured to close when the cover is no longer in the closed position on the housing.

[0039] The state of the fuse, i.e., whether it is conducting or not conducting, can be easily detected and a warning can be issued at the appropriate time.

[0040] According to one implementation, the processor determines the state of the fuse based on the voltage at one of its terminals.

[0041] Capacitors are not used to power active circuits that would consume the stored energy. This allows the use of capacitors with relatively low capacitance (e.g., 10µF), resulting in low cost and the ability to retain their charge for extended periods.

[0042] The switch and fuse are designed to limit the possibility of tampering by unauthorized personnel. For example, to prevent attempts to keep the switch open or to short-circuit the fuse (or replace the fuse if appropriate). For example, the switch and fuse may be placed on a printed circuit board located in a closed compartment of housing 101 and properly separated from the accessible portion of the housing (made of openings in the walls of the compartment) when the cover is open, so that when the cover is closed, the protruding members of the cover can access the switch.

[0043] Figure 3 This is a view of a first exemplary embodiment of a circuit for detecting the opening of a cover.

[0044] In the illustrated example, the cover is referenced as 301. When the cover is in the closed position on the housing, it disrupts the continuity of the circuit configured to discharge capacitor 303 via fuse 304.

[0045] According to one embodiment, one possible implementation includes providing a protruding member 302, such as a pin, for the cover, which causes two resilient metal strips 305 to move apart when the cover is in the closed position on the housing. The pin is made of a non-conductive material, such as the same insulating material as the cover. Thus, the strips and the protruding member thus form a switch. The strips are configured to make electrical contact in the absence of the protruding member. They connect a first terminal (in this case, the positive terminal) of a capacitor 303 and a first terminal of a fuse 304. When electrical continuity between the strips is restored, if the capacitor is charged, the capacitor discharges through the fuse. Other embodiments of the switch are contemplated, provided that the switch is open when the cover is in the closed position on the housing and closed when the cover is open.

[0046] According to one embodiment, the capacitor charging circuit includes a voltage source 306 connected to the first terminal of the capacitor via a resistor 307. The second (negative) terminal of the capacitor 303 is connected to ground 309. The voltage source 306 is only effective when the device 100 is powered on. In principle, the device is powered on after installation and once the cover is closed. Charging of the capacitor begins at this time. The value of the resistor 307 is chosen to limit the charging current of the capacitor 303. An example value for the resistor 307 is 100kΩ. The voltage of the voltage source 306 is, for example, 3.3V.

[0047] according to Figure 3 The exemplary embodiment shown uses a processor, such as a microcontroller 311, to determine the state (on or off) of the fuse based on the voltage at the first terminal of the fuse.

[0048] In one possible implementation, resistor 308 is connected to voltage source 313 on one side and to the first terminal of a fuse on the other. The second terminal of the fuse is connected to ground via resistor 310. Resistor 310 is designed to force the first terminal of the fuse to zero voltage when the fuse is conducting. When the fuse is no longer conducting, the voltage at the first terminal of the fuse is determined by voltage source 313. The value of resistor 308 is chosen to be very large so as to reduce the current that can flow from source 313 through the fuse and then through resistor 310 to ground when the fuse is conducting. The value of resistor 310 is chosen to be low, specifically so that the fuse can blow when the capacitor discharges. The value of resistor 308 is, for example, 100kΩ, and the value of resistor 310 is, for example, 10Ω. When the fuse is conducting, the high ratio between the two resistors 308 and 310 biases the first terminal of the fuse to ground. The voltage of voltage source 313 is, for example, 3.3V.

[0049] Capacitor 303 is, for example, a multilayer capacitor of 10μF±20% / 10V.

[0050] For example, fuse 304 is a screen-printed fuse designed to definitely blow at 330mA and definitely not blow at 33μA. To ensure that the capacitor blows during its discharge, a blowing threshold of 200mA < 1ms can be selected, for example. Special copper traces at least 10mm long, 35μm thick, and 100μm wide can be provided. Another example of a fuse is an ultrafast fuse (FF fuse) designed to blow at 200mA < 1ms. Other types of fuses will be considered by those skilled in the art.

[0051] according to Figure 3In the example shown, the device may optionally also include a communication interface 312. This modem may be, for example, but is not limited to, a CPL modem, an RF modem, a Wi-Fi wireless interface, or a cellular network interface.

[0052] According to an exemplary implementation, Figure 3 The operation of the device shown may include the following steps: a) At the time of manufacture, capacitor 303 is in a discharged state. For example, strip 305 is in contact with cover 301 that is not in the proper position. The high ratio between resistor 307 and resistor 310 means that the charge level of capacitor 303 is negligible and practically equal to 0V.

[0053] (b) After the cover is installed and closed (in this case, the closed cover or terminal cover), capacitor 307 will be charged when the device is first powered on. A component integral with the cover is inserted between the two strips, and then the two strips are no longer in contact.

[0054] c) When the ratio between resistor 308 and resistor 310 is high, the first terminal of the fuse that is conducting in this stage is biased low (zero voltage). Processor 311 detects the low level and notices that the cover has not yet been opened.

[0055] d) When the cover is opened, the capacitor discharges through the fuse.

[0056] e) The fuse blows and becomes non-conductive. Then, the voltage at the first terminal of the fuse is higher (via voltage source 313).

[0057] f) The processor 311 detects a high level and therefore detects that the cover is open.

[0058] g) The processor 311 may trigger one or more actions after detecting that the cover is open.

[0059] In principle, the device will be powered off before the cover is opened. Then, no more power will be supplied to the processor 311. When the device is powered on again, the processor 311 can detect that the cover has been opened, even if it has subsequently closed again.

[0060] According to one implementation, if the processor detects that the cover is open, it triggers one or more of the following actions: - An alert message can be transmitted via communication interface 312. For example, this message can be sent to a power grid operator.

[0061] - Open the meter's shut-off device to stop all electricity supplied to the customer via the meter.

[0062] Preferably, the interrupting device and the component integrated with the cover are configured such that the interrupting device cannot be accessed if the cover is removed before the interrupting device has triggered the capacitor to discharge.

[0063] According to a non-limiting exemplary embodiment, this can be achieved, for example, by placing the interrupting device behind an opening or passage formed in the inner wall of the housing, such as... Figure 2 As shown (reference numeral 202), the integral member with the cover is positioned such that when the cover is removed, the integral member also prevents access to the opening, even if the member has been moved sufficiently to trigger the capacitor to discharge. According to another non-limiting exemplary embodiment, the interrupting device can also simply be placed close to the inner wall of the cover. In another exemplary embodiment that can be combined with the above, the interrupting device and the integral member are arranged such that even a very brief removal of the cover will trigger the capacitor to discharge.

[0064] According to one variant, the device includes an additional discharge circuit for discharging capacitor 303. The purpose of the additional discharge circuit is to allow the capacitor to discharge without passing through a fuse. This allows the cover to be opened even if the fuse has not blown, for example, for maintenance purposes.

[0065] One non-limiting exemplary embodiment of this variation is to provide a controllable switch for short-circuiting capacitor 303.

[0066] Figure 4 use Figure 3 The system includes components and also includes a switch 401 that connects the two terminals of capacitor 303 when closed. In the example shown, the switch is controlled by a control signal 402 generated by processor 311. Depending on the implementation, the control signal may be generated in response to actions on a local human-machine interface (e.g., entering a password) or in response to commands received via a communication interface, such as commands from a power grid operator.

[0067] According to an exemplary implementation, Figure 4 The operation of the device shown may include the following steps: a) When the cover is to be opened, the processor 311, which generates the closing command signal, closes the switch 401 in advance.

[0068] b) Discharge capacitor 303.

[0069] c) Power off device 100. Switch 401 is designed to open automatically in this situation.

[0070] d) Then, the cover 302 can be opened.

[0071] e) Fuse 308 remains intact.

[0072] f) Once one or more operations have been completed, close the cover 302 again.

[0073] g) Power on device 100 again.

[0074] h) Processor 311 detected that the fuse is intact.

[0075] i) Recharge capacitor 303.

[0076] j) Protect the device again from unauthorized opening of the cover.

[0077] For example, a MOSFET can be used to implement switch 401.

[0078] exist Figure 3 and Figure 4 In the example shown, device 100 includes a processor. Some meters include multiple processors, such as an application processor and a metering processor. Any of them can perform the functions of processor 311.

[0079] Another advantage of the exemplary embodiment shown is that the installer does not necessarily need to be familiar with the operation of the equipment. In fact, the installation is the same as for a conventional meter.

[0080] The example above has already taken into account the example of an electricity meter. However, device 100 can be any other type of meter (gas, water, etc.) or any device that includes a housing with an open cover and is intended to detect its openness.

[0081] In one implementation, open detection is achieved for multiple components of the device. Advantageously, a single fuse is used, and multiple switches are placed in parallel, each switch used to detect the open of each component.

[0082] As a non-limiting example, in the case of an electricity meter, the opening of both the main cover and the terminal cover can be detected independently. According to one possible implementation, two pairs of strips are placed side-by-side and a single fuse is used. The first pair of strips is moved apart by positioning the terminal cover, and the second pair is moved apart by positioning the main cover. If the capacitor 303 is charged, opening either the terminal cover or the main cover when it is opened without power will cause the fuse 304 to blow.

[0083] List of reference numerals 100-equipment 101-Shell 102-Cover Parts 103-lock 104-monitor 201-Electrical Terminal 202-Opening 301-Cover Parts 302-Protruding component 303-Capacitor 304 - Fuse Article 305 306-Voltage Source 307-Resistor 308 Resistor 309-land 310-Resistor 311-processor 312-Communication Interface 313-Voltage Source 401-Switch 402 - Control signal.

Claims

1. An apparatus (100) comprising: - Housing, the housing including component (201); - Cover (301), the cover being configured to be positioned on the housing so as to restrict access to the component when the cover is in a closed position; - A capacitor (303) and a fuse (304), the capacitor and the fuse being sized such that the fuse blows when the capacitor discharges through the fuse; - A capacitor charging circuit, configured to charge the capacitor when the device is powered on; - A discharge circuit for discharging the capacitor via the fuse, the discharge circuit including a first switch (305) that cooperates with a portion (302) integral with the cover to: When the cover is in the closed position, it prevents the capacitor from discharging; and When the cover is in the open position, the capacitor can be discharged through the fuse.

2. The device according to claim 1, wherein, The discharge circuit is configured to electrically connect the capacitor and the fuse via a first switch, the first switch including a conductive portion (305) configured to make electrical contact when the cover is in the open position and to be moved apart from the portion (302) integral with the cover when the cover is in the closed position, thereby breaking the electrical contact between the conductive portions.

3. The device according to claim 2, wherein, The conductive part includes two metal strips (305).

4. The device according to any one of the preceding claims, wherein, The portion (302) integral with the cover is a protruding member integral with the cover.

5. The device according to any one of the preceding claims, wherein, The charging circuit includes a voltage source (306) connected to a first terminal of the capacitor via a resistor (307), and a second terminal of the capacitor connected to ground (309). The voltage source is configured to provide a voltage to charge the capacitor when the device is powered on.

6. The device according to any one of the preceding claims, wherein, The capacitor is in a discharged state before the device is first powered on.

7. The device according to any one of the preceding claims, the device comprising a second switch (401) controlled by a control signal (402), the second switch being configured such that the capacitor can be discharged without passing through the fuse.

8. The device according to claim 7, wherein, The second switch is configured to short-circuit the capacitor in response to the control signal.

9. The device according to any one of claims 7 or 8, the device comprising a processor (311) configured to generate the control signal under the control of an authorized user.

10. The device according to any one of the preceding claims, wherein the device is an electricity meter and the component includes electrical terminals of the meter.

11. The device according to any one of the preceding claims, the device comprising a processor (311) configured to determine whether the fuse has blown, and if so, to generate a warning signal.

12. The device according to any one of the preceding claims, wherein, The fuse is a screen-printed fuse that is screen-printed on the printed circuit board of the device.

Images