US-20260126478-A1 - DEVICE WITH OPENING DETECTION

US20260126478A1US 20260126478 A1US20260126478 A1US 20260126478A1US-20260126478-A1

Abstract

Disclosed is a device comprising a housing that comprises 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 fuse being dimensioned 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 powered up; a discharge circuit for discharging the capacitor through the fuse, said discharge circuit comprising a first switch cooperating with a part integral with the cover in order to prevent the discharging of the capacitor when the cover is in the closed position; and to allow the capacitor to discharge through the fuse when the cover is in the open position.

Inventors

Henri TEBOULLE
Christophe GRINCOURT

Assignees

SAGEMCOM ENERGY & TELECOM SAS

Dates

Publication Date: 20260507
Application Date: 20251001
Priority Date: 20241104

Claims (12)

1 . A device comprising: a housing comprising components; a cover configured to be positioned on the housing in order to restrict access to the components when the cover is in a closed position; a capacitor and a fuse, the capacitor and fuse being dimensioned 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 powered up; a discharge circuit for discharging the capacitor through the fuse, said discharge circuit comprising a first switch cooperating with a part integral with the cover in order to: prevent the discharging of the capacitor when the cover is in the closed position; and allow the capacitor to discharge through the fuse when the cover is in an open position.
2 . The device as claimed in 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 configured to be in electrical contact when the cover is in the open position and to be moved apart by the part integral with the cover when the cover is in the closed position, thereby breaking the electrical contact between the conductive parts.
3 . The device as claimed in claim 2 , wherein the conductive parts comprise two metal strips.
4 . The device as claimed in claim 1 , wherein the part integral with the cover is a projecting member integral with the cover.
5 . The device as claimed in claim 1 , wherein the capacitor charging circuit comprises 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 voltage for charging the capacitor when the device is powered up.
6 . The device as claimed in claim 1 , wherein the capacitor is in a discharged state prior to the first time the device is powered up.
7 . The device as claimed in claim 1 , comprising a second switch controlled by a control signal, the second switch being configured to allow the capacitor to be discharged other than via the fuse.
8 . The device as claimed in claim 7 , wherein the second switch is configured to short-circuit the capacitor in response to the control signal.
9 . The device as claimed in claim 7 , comprising a processor configured to generate the control signal under the control of an authorized user.
10 . The device as claimed in claim 1 , the device being an electric meter and the components comprising electrical terminals of the meter.
11 . The device as claimed in claim 1 , comprising a processor configured to determine whether or not the fuse has blown and, if so, to generate an alert signal.
12 . The device as claimed in claim 1 , wherein the fuse is a screen-printed fuse screen-printed on a printed circuit board of the device. ______________________

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority to French Application No. 2412057 filed with the Intellectual Property Office of France on November 4, 2024, which is incorporated herein by reference in its entirety for all purposes. TECHNICAL FIELD The various embodiments described in the present disclosure relate to a device provided with opening detection. The device can be, but is not limited to, an electric meter. PRIOR ART Consumables meters, such as electricity meters, are vulnerable to tampering for fraudulent purposes. The detection of opening of a meter, once it has been installed in its place of use and activated, is an indication that fraud has been committed – detection of this can lead to the operator in question being called in for verification. Some known meters offer a function for detecting the opening of the terminal cover and/or main cover, in particular using a battery that continues to power a microcontroller when the meter is no longer being powered. The microcontroller can then continuously monitor the status of a switch linked to the main cover or terminal cover. The battery can also be replaced by a high-value supercapacitor, typically of 1 F, which allows the detection function to be kept active for five to seven days. The components are expensive, however, and some operators prohibit the use of a battery in a meter. In addition, the duration of detection is necessarily time-limited – so it is possible to detach the main cover or terminal cover without risk of detection simply by waiting long enough. It is also known practice to use a monostable relay with a movable core to detect the opening of a cover closing a meter box. It is likewise known practice to use an incremental encoder that reacts to the opening of the cover. However, such solutions are expensive and can be mechanically complex and in particular, as with the incremental encoder for example, subject to mechanical uncertainties. With this last solution, opening can no longer be detected if the initial value is restored. A simple solution that allows the opening of a meter housing to be detected, even when it is not being powered, is desirable. SUMMARY OF THE INVENTION A first aspect relates to a device comprising: a housing that comprises 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, the capacitor and fuse being dimensioned 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 powered up; a discharge circuit for discharging the capacitor through the fuse, said discharge circuit comprising a first switch cooperating with a part integral with the cover in order to prevent the discharging of the capacitor when the cover is in the closed position; and allowing the capacitor to discharge through the fuse when the cover is in an open position. Thus, once the device has been installed and powered up for the first time, the cover cannot be opened undetected, even when the device is no longer powered up, 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 be kept active for a long time. 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 moved apart by the part integral with the cover when the cover is in the closed position, thereby breaking the electrical contact between the conductive parts. According to one or more exemplary embodiments, the conductive parts comprise two metal strips. According to one or more exemplary embodiments, the part integral with the cover is a projecting member integral with the cover. The security of the device can be increased by positioning or protecting the switch and fuse in such a way as to prevent or at least substantially reduce the possibility of tampering by an unauthorized person who is nonetheless intimately familiar with the operation of the opening detection function. For example, the switch and fuse can be placed in a compartment of the housing separated by a wall from the portion of the housing made accessible by opening the cover. The switch, however, is arranged so that it can interact with the projecting member of the cover, for example via an opening made in a wall. Advantageously, the dimensions of the opening are close to those of the cross section of the projecting member. In this way, a malicious third party cannot reach the switch before removing the cover, and has no time to prevent the capacitor from discharging and blowing the fuse when the cover is removed