OPENING DETECTION DEVICE

Abstract

A device (100) is disclosed, comprising a housing containing components (201); a cover (301) configured to be positioned on the housing to restrict access to the components when the cover is closed; a capacitor (303) and a fuse (304), the capacitor and fuse being sized so that the fuse blows when the capacitor discharges through the fuse; a capacitor charging circuit configured to charge the capacitor when the device is energized; and a capacitor discharge circuit through the fuse, said discharge circuit comprising a first switch (305) cooperating with a part (302) integral with the cover to block the discharge of the capacitor when the cover is closed, and to allow the discharge of the capacitor through the fuse when the cover is open. FIG. 3

Description

Title of the invention: OPENING DETECTION DEVICE technical field

[0001] The various embodiments described in this disclosure relate to a device equipped with an opening detection system. The device may include, but is not limited to, an electricity meter. Previous technique

[0002] Consumption meters, such as electricity meters, are susceptible to manipulation in the context of fraud. The detection of the meter being opened, once installed at its place of use and activated, is an element that may indicate that fraud has been committed – this detection may lead to intervention by the operator concerned for verification.

[0003] Some known meters offer a terminal cover and / or cover opening detection function, particularly using a battery that continues to power a microcontroller when the meter is switched off. The microcontroller can then continuously monitor the state of a switch connected to the cover or terminal cover. The battery can also be replaced by a high-value supercapacitor, typically 1F, which allows the detection function to remain active for five to seven days. However, the components are expensive, and some operators prohibit the presence of a battery in a meter. Furthermore, the detection duration is necessarily limited—it is thus possible to remove the cover or terminal cover without risk of detection simply by waiting long enough.

[0004] It is also known to use a monostable relay with a moving core for detecting the opening of a cover closing a meter box. It is also known to use an encoder wheel that reacts to the opening of the cover. However, such solutions are expensive and can be mechanically complex and, in particular, as for the encoder wheel, subject to mechanical uncertainties. Furthermore, with this latter solution, the opening cannot be detected if the initial value is returned.

[0005] A simple solution enabling the detection of the opening of a meter box, even when powered off, is desirable. Summary of the invention

[0006] A first aspect concerns a device comprising:

[0007] a housing containing components; a cover configured to be positioned on the housing to restrict access to the components when the cover is in the closed position; a capacitor and a fuse, the capacitor and the fuse being sized so that the fuse blows when the capacitor discharges through the fuse; a capacitor charging circuit configured to charge the capacitor when the device is energized; a capacitor discharge circuit through the fuse, said discharge circuit having a first switch cooperating with a part integral with the cover to block the discharge of the capacitor when the cover is in the closed position; and permitting the discharge of the capacitor through the fuse when the cover is in the open position.

[0008] Thus, after installation and initial power-up of the device, the cover cannot be opened without being detected, even when the device is no longer powered, i.e., no longer connected to an external power source. The energy stored by the capacitor is used only to create a current in the fuse if necessary. This allows the detection function to remain active for an extended period.

[0009] It is possible to increase the security of the device by placing or protecting the switch and the fuse in such a way as to avoid or at least greatly limit the possibilities of manipulation by an unauthorized person, but who would intimately know the operation of the opening detection.

[0010] For example, the switch and the fuse can be placed in a compartment of the housing isolated by a wall from the part of the housing made accessible by the opening in the cover. The switch is, however, arranged so as to be able to interact with the protruding member of the cover, for example through an opening made in a wall.

[0011] Advantageously, the dimensions of the opening are close to those of the cross-section of the protruding member. Thus, a malicious third party cannot reach the switch before removing the cover, and there is not enough time to prevent the discharge of the capacitor that would blow the fuse when the cover is removed.

[0012] Either of these components (switch and fuse) can also be placed under suitable discrete protection. The specific implementation on a printed circuit board can also limit handling. Furthermore, these two components can be chosen so that their inherent structure limits their handling, and depending on the component, access to its terminals, its removal, or its replacement.

[0013] According to one or more exemplary embodiments, the discharge circuit is configured to electrically connect the capacitor and the fuse through the first switch, the first switch comprising conductive parts configured to be in electrical contact when the cover is in the open position and to be separated by the part attached to the cover when the cover is in the closed position, thus interrupting the electrical contact between the conductive parts.

[0014] According to one or more embodiments, the conductive parts comprise two metal strips.

[0015] According to one or more embodiments, the part attached to the cover is a prominent member attached to the cover.

[0016] According to one or more exemplary embodiments, the charging circuit includes a voltage source connected to a first terminal of the capacitor through a resistor, a second terminal of the capacitor being connected to ground, the voltage source being configured to provide a charging voltage to the capacitor when the device is energized.

[0017] According to one or more embodiment examples, the capacitor is in a discharged state before the device is first powered on.

[0018] According to one or more embodiments, the device includes a second switch controlled by a control signal, the second switch being configured to allow the capacitor to be discharged other than by passing through the fuse.

[0019] According to one or more embodiment examples, the second switch is configured to short-circuit the capacitor in response to the control signal.

[0020] According to one or more embodiments, the device includes a processor configured to generate the control signal under the control of an authorized user.

[0021] According to one or more embodiments, the device is an electric meter and the components include the electric terminals of the meter.

[0022] According to one or more embodiments, the device includes a processor configured to determine whether the fuse has blown or not and, if so, to generate an alert signal.

[0023] According to one embodiment, the fuse is a silkscreened fuse on a printed circuit board of the device. This limits the possibility of an unauthorized person replacing a blown fuse. BRIEF DESCRIPTION OF THE FIGURES

[0024] The implementation examples will be better understood in the light of the detailed description that follows and the accompanying drawings, which are given for illustrative purposes only and are therefore not limiting to this disclosure.

[0025] Figure [Fig.1] is a diagram of a device comprising a removable cover covering the terminals of the meter, according to one embodiment.

[0026] Figure [Fig.2] is a diagram of the device of [Fig.1], with the hood removed.

[0027] Figure [Fig.3] is a diagram of a first example of an embodiment.

[0028] Figure [Fig.4] is a diagram of a second embodiment. DETAILED DESCRIPTION

[0029] Various embodiment examples will now be described in more detail, by way of non-limiting examples, with reference to the drawings which accompany this disclosure and which illustrate certain embodiment examples.

[0030] The specific structural and functional details described herein are non-limiting examples. The embodiments described herein may be subject to various modifications and alternative forms. The subject matter of the disclosure may be realized in many different forms and should not be interpreted as being limited to the embodiments presented herein as illustrative examples. It should be understood that there is no intention to limit the embodiments to the particular forms described later in this document.

[0031] In the following description, identical, similar, or analogous elements will be designated by the same reference numerals. The block diagrams, flowcharts, and message sequence diagrams in the figures illustrate the architecture, functionalities, and operation of computer systems, devices, processes, and program products according to one or more embodiments. Each block in a block diagram or each phase in a flowchart can represent a module or a portion of software code comprising instructions for implementing one or more functions. In some implementations, the order of the blocks or phases can be changed, or the corresponding functions can be implemented in parallel.The process blocks or phases can be implemented using circuits, software, or a combination of circuits and software, either centrally or in a distributed manner, for all or part of the blocks or phases. The systems, devices, processes, and methods described can be modified, supplemented, and / or deleted while remaining within the scope of this description. For example, the components of a device or system can be integrated or separated. Similarly, the described functions can be implemented using more or fewer components or phases, or with different components or through different phases. Any suitable data processing system can be used for implementation. A suitable data processing system or device might include, for example, a combination of software code and circuits, such as a processor, controller, or other circuit suitable for executing the software code.When the software code is executed, the processor or controller directs the system or device to implement all or part of the functionalities of the blocks and / or phases of the processes or methods according to the embodiment examples. The software code can be stored in non-volatile memory or on a non-volatile storage medium (key). USB, memory card or other media) readable directly or through an interface adapted by the processor or controller.

[0032] This disclosure applies to any device with a housing comprising one or more components arranged behind a cover.

[0033] The term 'cover' refers to any part designed to provide access to certain components of the device when the cover is removed and to prevent such access when it is in position on the housing. In the case of an electricity meter, this could be – for example – the meter cover, but also a bulb cover.

[0034] It should be noted that the embodiment examples are not limiting. In particular, components other than those illustrated may be used to implement the described functions, and fewer components or additional components may of course be implemented. Furthermore, the different values ​​given are for clarity of explanation and may also differ.

[0035] Figure 1 is a non-limiting example of a device 100, in this case an electricity meter. The illustrated device comprises a housing 101 and a cover 102 that is positioned over the housing to prevent access to the meter's electrical terminals. In the example shown, the cover 102 is mechanically locked onto the housing 100 by means of a locking mechanism 103. The illustrated device includes other components, such as a display screen 104. The screen may be a touchscreen configured to implement a human-machine interface.

[0036] Fig. 2 shows the device of Fig. 1 without the cover 102. Fig. 2 thus shows the electrical terminals 201 of the meter (phases and neutrals), which are not accessible when the cover is in place on the meter, whether for reasons of security or to limit fraud.

[0037] According to one or more embodiments, the device includes a circuit for detecting when the cover is open. The principle underlying the various embodiments is that a capacitor is charged when the device is energized. The discharge of this capacitor is triggered by closing a discharge circuit when the cover is opened. The discharge is carried out through a fuse. The capacitor and the fuse are designed so that the fuse blows during this discharge.

[0038] According to one embodiment, the capacitor is typically charged after the device has been first switched on, following its installation in its place of operation, since it is - generally - from the installation that one will seek to detect any possible fraud.

[0039] According to one embodiment, the discharge circuit can be closed using a switch held open by a part of the cover when the latter is in the closed position on the housing to prevent access to the components, the switch is configured to close when the cover is no longer in the closed position on the case.

[0040] The state - conductive or non-conductive - of the fuse is easily detectable and can give rise to a warning at the appropriate time.

[0041] According to one embodiment, the state of the fuse is determined by a processor from the voltage at one terminal of the fuse.

[0042] The capacitor is not used to power an active circuit that would consume the stored energy. This allows the use of a capacitor with a relatively low capacitance (for example 1 OpF), and therefore inexpensive, and to maintain its charge for a very long time.

[0043] The switch and fuse are positioned to restrict the possibility of tampering by an unauthorized person. This includes, for example, preventing an attempt to hold the switch open or to short-circuit (or, where applicable, replace) the fuse. For example, the switch and fuse may be located on a printed circuit board within a closed compartment of the housing 101 and separated from the part of the housing accessible when the cover is open by suitable partitions, with an opening provided in one of the compartment partitions to allow the protruding part of the cover to reach the switch when the cover is closed.

[0044] Fig. 3 is a diagram of a first example of an embodiment of a circuit for detecting the opening of the cover.

[0045] In the illustrated example, the cover bears the reference 301. When the cover is in the closed position on the housing, the cover interrupts the continuity of a circuit configured to discharge a capacitance 303 through a fuse 304.

[0046] According to one embodiment, a possible implementation consists of providing the cover with a prominent member 302, for example a pin, which separates two elastic metal strips 305 when the cover is in the closed position on the housing. The pin is formed from a non-conductive material, for example the same insulating material as the cover. The strips and the prominent member thus form a switch. The strips are configured to make electrical contact in the absence of the prominent member. They connect a first terminal of the capacitor 303 (in this case the positive terminal) and a first terminal of the fuse 304. When electrical continuity between the strips is restored, the capacitor, if charged, discharges through the fuse. Other embodiments of the switch can be envisaged, provided that the switch is open when the cover is in the closed position on the housing and closed when the cover is open.

[0047] According to one embodiment, the capacitor charging circuit comprises a voltage source 306 connected to the first terminal of the capacitor through a resistor 307. The second (negative) terminal of the capacitor 303 is connected to the Ground 309. The voltage source 306 is only active when the device 100 is powered on. The device is generally powered on after installation and once the cover is closed. It is then that the capacitor charges. The value of resistor 307 is chosen to limit the charging current of capacitor 303. An example of a value for this resistor 307 is 100 kΩ. The voltage source 306 is, for example, at a voltage of 3.3 V.

[0048] According to the embodiment example in [Fig.3], the state (conducting or non-conducting) of the fuse is determined by a processor, for example the microcontroller 311, from the voltage at the first terminal of the fuse.

[0049] According to one possible implementation, a resistor 308 is connected on one side to a voltage source 313 and on the other side to the first terminal of the fuse. The second terminal of the fuse is connected to ground through a resistor 310. The resistor 310 is intended 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 across the first terminal of the fuse is determined by the voltage source 313. The value of the resistor 308 is chosen to be very large to reduce the current that can flow from the source 313 to ground through the fuse and then through the resistor 310 when the fuse is conducting. The value of the resistor 310 is chosen to be small, in particular to allow the fuse to blow when the capacitor discharges. The resistor 308 has, for example, a value of 100 kΩ and the resistor 310 has, for example, a value of 10Ω.The large ratio between the two resistors 308 and 310 allows the first terminal of the fuse to be biased to ground when the fuse conducts. The voltage source 313 is, for example, at a voltage of 3.3V.

[0050] Capacitor 303 is for example a multilayer capacitor of lOpF ± 20% / 10V.

[0051] Fuse 308, for example, is a screen-printed fuse sized to blow reliably at 330 mA and reliably not at 33 pA. To ensure blowing during capacitor discharge, a breakdown threshold of 200 mA < 1 ms can be chosen, for example. A dedicated copper trace with a minimum length of 10 mm, a thickness of 35 µm, and a width of 100 µm can be provided. Another example of a fuse is an ultra-fast fuse (type 'FF') sized to blow at 200 mA < 1 ms. Other types of fuses may be considered by those skilled in the art.

[0052] According to the example in [Fig.3], the device also optionally includes a communication interface 312. This modem is, for example and without limitation, a PLC modem, or an RF modem, or a 'Wi-Fi' type wireless interface or a cellular network interface.

[0053] According to one embodiment, the operation of the device in [Fig.3] may include the following steps: a. As it leaves the factory, capacitor 303 is in a discharged state. For example, the contacts 305 are in contact, as the cover 301 is not yet fitted. The large ratio between resistances 307 and 310 means that the charge level of capacitor 303 is negligible and practically equal to 0V. b. Capacitor 307 will be charged upon initial power-up, after installation and closure of the cover (in this case, the closing of the hood or boom cover). The part attached to the cover is inserted between the two strips, which are then no longer in contact. c. The first terminal of the fuse, which is conductive at this stage, is biased to the low level (zero voltage), given the large ratio between resistors 308 and 310. The processor 311 detects the low level and determines that the cover has not been opened. d. When the cover is open, the capacitor discharges through the fuse. e. The fuse blows and becomes non-conductive. The voltage at the first terminal the fuse is then at the high level (via the voltage source 313). f. The 311 processor detects the high level and therefore the opening of the cache. g. The 311 processor can trigger one or more actions following the detection of the opening of the cache.

[0054] In principle, the device will have been powered off before the cache was opened. The processor 311 is then no longer powered. When the device is powered on again, the processor 311 can detect that the cache has been opened, even if it has since been closed.

[0055] According to one embodiment, if the processor detects that the cache has been opened, one or more of the following actions are triggered: - The transmission of an alert message via the communication interface 312. For example, the transmission can be made to the electricity network operator. - Opening the meter's shut-off device so as to stop all power supply to the subscriber via the meter.

[0056] Preferably, the interrupt means and the attached member of the cache are configured so that it is not possible to access the interrupt means if the cache is removed before the interrupt means have triggered the discharge of the capacitor.

[0057] According to a non-limiting embodiment, this can, for example, be achieved by placing the interrupting means behind an opening or channel made in an internal wall of the housing, as illustrated in [Fig. 2] (reference 202), and in which The member attached to the cover is positioned so that it always blocks access to the opening when the cover is being retracted, even after the member has already been moved sufficiently to trigger the capacitor discharge. In another, non-limiting embodiment, it is also possible to simply place the interrupting means close to the inner wall of the cover. In yet another embodiment that can be combined with the above, the interrupting means and the attached member are arranged so that even a very short retraction of the cover triggers the capacitor discharge.

[0058] According to one embodiment, the device includes an additional discharge circuit for the capacitor 303. The purpose of this additional discharge circuit is to allow the capacitor to discharge without this discharge occurring through the fuse. This then allows the cover to be opened without the fuse blowing, for example, to allow for maintenance operations.

[0059] A non-limiting example of an implementation of this variant is to provide a controllable switch to short-circuit capacitor 303.

[0060] The [Fig.4] reproduces the elements of the [Fig.3], and also includes a switch 401 which connects the two terminals of the capacitor 303 when it is closed. In the example shown, the switch is controlled by a control signal 402 generated by the processor 311. The generation of the control signal can, depending on the implementation, be obtained in response to a manipulation on the local human-machine interface (for example, the entry of a secret code) or in response to the reception of a command via the communication interface, for example, a command from the electric network operator.

[0061] According to one embodiment, the operation of the device in [Fig.4] may include the following steps: a. When the cover is to be opened, switch 401 is closed beforehand by generating a closing control signal by processor 311. b. Capacitor 303 is discharged. c. Device 100 is switched off. Switch 401 is designed to open automatically in this case. d. Cache 302 can then be opened. e. Fuse 308 remains intact. f. Once the planned operation(s) have been carried out, cover 302 is closed. g. Device 100 is powered back on. h. Processor 311 detects that the fuse is intact. i. Capacitor 303 is recharging. j. The device is again protected against unauthorized opening of the cover.

[0062] The switch 401 is - for example - implemented using a MOSFET type transistor.

[0063] In the examples in Figures 3 and 4, the device 100 includes one processor. Some counters include several processors—for example, an application processor and a metrology processor. Either one can perform the function of the processor 311.

[0064] An additional advantage of the embodiments presented is that an installer does not necessarily need to be familiar with the operation of the device. Indeed, the installation is carried out in the same way as for a conventional meter.

[0065] In the examples above, the example of an electricity meter was considered. However, device 100 could be another type of meter (gas, water, etc.) or any device comprising a housing fitted with an opening cover and for which an opening must be detected.

[0066] According to one embodiment, opening detection is implemented for several elements of a device. Advantageously, a single fuse is used, and several switches placed in parallel, one for each element whose opening is to be detected.

[0067] For example, by way of non-limiting agreement, in the context of an electricity meter, the opening of both the cover and the terminal cover can be detected independently. According to one possible implementation, two pairs of contacts are placed in parallel, and a single fuse is used. The first pair of contacts is separated by the installation of the terminal cover, and the second by the installation of the cover. The opening of either of the two components will cause fuse 304 to blow when the terminal cover or the de-energized cover is opened, provided capacitor 303 is charged. List of reference signs

[0068] 100 - Device

[0069] 101 - Housing

[0070] 102 - Cache

[0071] 103-Lock

[0072] 104 - Display

[0073] 201 - Electric terminals

[0074] 202 - Opening

[0075] 301 - Cache

[0076] 302 - Prominent member

[0077] 303 - Capacitor

[0078] 304 - Fuse

[0079] 305 - Lamellae

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] 306 - Voltage source 307 - Resistor 308 - Resistor 309 - Ground 310 - Resistor 311 - Processor 312 - Communication interface 313 - Voltage source 401 - Switch 402 - Control signal

Claims

Demands

1. Device (100) comprising: - a housing containing components (201); - a cover (301) configured to be positioned on the housing to restrict access to the components when the cover is in the closed position; - a capacitor (303) and a fuse (304), the capacitor and the fuse being sized so that the fuse blows when the capacitor discharges through the fuse; - a capacitor charging circuit configured to charge the capacitor when the device is energized; - a capacitor discharge circuit through the fuse, said discharge circuit comprising a first switch (305) cooperating with a part (302) integral with the cover to: block the discharge of the capacitor when the cover is in the closed position; and allow the discharge of the capacitor through the fuse when the cover is in the open position.

2. Device according to claim 1, wherein the discharge circuit is configured to electrically connect the capacitor and the fuse through the first switch, the first switch comprising conductive parts (305) configured to be in electrical contact when the cover is in the open position and to be separated by the part (302) integral with the cover when the cover is in the closed position, thus interrupting the electrical contact between the conductive parts.

3. Device according to claim 2, wherein the conductive parts comprise two metal strips (305).

4. Device according to any one of the preceding claims, wherein the part (302) integral with the cover is a prominent member integral with the cover.

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

6. 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. Device according to any one of the preceding claims, comprising a second switch (401) controlled by a control signal (402), the second switch being configured to allow the capacitor to be discharged other than through the fuse.

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

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

10. Device according to any one of the preceding claims, the device being an electric meter and the components comprising the electric terminals of the meter.

11. Device according to any one of the preceding claims comprising a processor (311) configured to determine whether the fuse has blown or not and, if so, to generate an alert signal.

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

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