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CN-121995093-A - Opening detection device

CN121995093ACN 121995093 ACN121995093 ACN 121995093ACN-121995093-A

Abstract

A device (100) is disclosed that includes a housing including a component (201), a cover (301) configured to be positioned on the housing to limit access to the component when the cover is in a closed position, a capacitor (303) and a fuse (304) sized 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 up, a discharge circuit for discharging the capacitor through the fuse, the discharge circuit including a first switch (305) that cooperates with a portion (302) integral with the cover to prevent the capacitor from being discharged when the cover is in the closed position, and to allow the capacitor to be discharged through the fuse when the cover is in the open position.

Inventors

  • H. TAYLOR
  • C. Greenkert

Assignees

  • 萨基姆通讯能源及电信联合股份公司

Dates

Publication Date
20260508
Application Date
20251024
Priority Date
20241104

Claims (12)

  1. 1. An apparatus (100), the apparatus comprising: -a housing comprising a component (201); -a cover (301) configured to be positioned on the housing so as to limit access to the component when the cover is in a closed position; -a capacitor (303) and a fuse (304) sized 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 up; -a discharge circuit for discharging the capacitor through the fuse, the discharge circuit comprising a first switch (305) cooperating with a portion (302) integral with the cover so as to: Preventing said capacitor from said discharging when said cover is in said closed position, and When the cover is in an open position, the capacitor is allowed to discharge through the fuse.
  2. 2. The device of claim 1, wherein the discharge circuit is configured to electrically connect the capacitor and the fuse through the first switch, the first switch comprising a conductive portion (305) configured to electrically 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. 3. The device of claim 2, wherein the conductive portion comprises two metal strips (305).
  4. 4. The apparatus of one of the preceding claims, wherein the portion (302) integral with the cover is a raised member integral with the cover.
  5. 5. The device of 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 voltage for charging the capacitor when the device is powered up.
  6. 6. The device of one of the preceding claims, wherein the capacitor is in a discharged state before the device is first powered up.
  7. 7. The device of one of the preceding claims, comprising a second switch (401) controlled by a control signal (402) configured such that the capacitor may not be discharged via the fuse.
  8. 8. The device of claim 7, wherein the second switch is configured to short the capacitor in response to the control signal.
  9. 9. The device of one of claims 7 or 8, comprising a processor (311) configured to generate the control signal under control of an authorized user.
  10. 10. The device according to one of the preceding claims, which is an electricity meter and the component comprises an electrical terminal of a meter.
  11. 11. The device of one of the preceding claims, comprising a processor (311) configured to determine whether the fuse has been blown and if so to generate an alert signal.
  12. 12. The device of one of the preceding claims, wherein the fuse is a screen printed fuse screen printed on a printed circuit board of the device.

Description

Opening detection device Technical Field Various embodiments described in this disclosure relate to a device provided with an open detection. The device may be, but is not limited to, an electricity meter. Background Consumable meters such as electricity meters are easily tampered with for fraud purposes. Once the meter has been installed in its use position and activated, detection of meter opening indicates that fraud has occurred-detection of this condition may result in a requirement for verification by the relevant operator. Some known meters provide a function for detecting the opening of the terminal cover and/or the main cover, in particular by using a battery to continue the power supply to the microcontroller when the meter is no longer being powered. The microcontroller may then continue to monitor the status of the switch coupled to the main cover or the terminal cover. The battery may also be replaced by a high value supercapacitor, typically 1F, which allows the detection function to remain activated for five to seven days. However, these components are expensive and some operators prohibit the use of batteries in the meter. Furthermore, the duration of the detection is inevitably limited in time, so that the main cover or the terminal cover can be detached without risk of detection, as long as it waits for a sufficiently long time. Another known practice is to use a monostable relay with a movable core to detect the opening of the cover closing the meter box. It is also known practice to use an incremental encoder that reacts to the opening of the cover. However, such solutions are expensive and may be mechanically complex and, in particular, for example for incremental encoders, are susceptible to mechanical uncertainties. With this last solution, if the initial value is restored, the opening can no longer be detected. An ideal easy solution would be to detect the opening of the meter housing even without power being supplied to the meter housing. Disclosure of Invention A first aspect relates to an apparatus, the apparatus comprising: The device includes a housing including a component, a cover configured to be positioned on the housing to limit access to the component when the cover is in a closed position, a capacitor and a fuse sized 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 up, a discharge circuit for discharging the capacitor through the fuse, the discharge circuit including a first switch and a portion integral with the cover to cooperate to prevent the capacitor from being discharged when the cover is in the closed position, and to allow the capacitor to be discharged through the fuse when the cover is in the open position. Thus, once the device has been installed and powered up for the first time, it is not possible to open the cover without being detected even when the device is no longer powered up, i.e. is no longer connected to an external power source. The energy stored by the capacitor is used only to generate current in the fuse, if necessary. This allows the detection function to remain active for a long period of time. According to one or more exemplary embodiments, the discharge circuit is configured to electrically connect the capacitor and the fuse through a first switch comprising conductive portions configured to electrically contact when the cover is in the open position and to be moved apart from portions integral with the cover when the cover is in the closed position, thereby breaking the electrical contact between the conductive portions. According to one or more exemplary embodiments, the conductive portion includes two metal strips. According to one or more exemplary embodiments, the portion integral with the cover is a raised member integral with the cover. By locating or protecting the switch and fuse, the security of the device may be increased to prevent or at least greatly reduce the possibility of tampering by unauthorized persons (although they are very familiar with operating the open detection function). For example, the switch and fuse may be placed in a compartment of the housing separated from a portion of the housing accessible by opening the cover by a wall. However, the switch is arranged such that it can interact with the protruding member of the cover, e.g. via an opening made in the wall. Advantageously, the size of the opening approximates the size of the cross-section of the protruding member. In this way, a malicious third party cannot reach 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. Any of these components (switches and fuses) may also be placed under appropriate discrete protection. The implementation on a printed circuit board may also limit tampering. Furthermore, the two components may also be selected su