Ultra-low power consumption terminal disassembly detection system based on Hall strip and reed switch

Abstract

The invention discloses an ultra-low power consumption terminal disassembly detection system based on a Hall strip and a reed switch. The system comprises a disassembly detection write-in module and a state reading module, the disassembly detection write-in module is used for detecting the disassembly action of the terminal and permanently recording the state, and comprises a reed switch detection unit, an energy storage write-in unit which is connected with the reed switch detection unit and is provided with an independent power supply element, and a Hall strip state storage unit; the pulse output end of the energy storage write-in unit is connected with the pulse input end of the Hall strip state storage unit; in the Hall strip state storage unit, abnormal Hall resistance generates nonvolatile change under the action of pulse current; and the state reading module is connected with the Hall strip state storage unit and is used for reading pulse information of the Hall strip state storage unit and outputting the pulse information to the terminal after obtaining a disassembly state. The device has the advantages of being miniaturized, low in power consumption and capable of recording the non-volatile state when power is off, the unauthorized disassembling condition of the device can be known when the device is maintained, and the key requirement for disassembling detection of the small intelligent terminal is met.

Description

Technical Field

[0001] This invention relates to the field of disassembly and testing technology for electronic devices, and in particular to an ultra-low power terminal disassembly and testing system based on Hall effect sensors and reed switches, and an anti-tampering testing technology based on the non-volatile resistance characteristics of Hall effect sensors and the magnetic sensitivity characteristics of reed switches. Background Technology

[0002] With the rapid development of IoT technology, small smart terminals such as smartphones and smartwatches are evolving towards greater integration and thinner designs. Terminal manufacturers are continuously raising their requirements for waterproof and dustproof ratings and operational safety, making the prevention of unauthorized disassembly a critical need. "Unauthorized disassembly" refers to the disassembly, splitting, or opening of small smart terminals such as smartphones and smartwatches without the permission of the device manufacturer or its authorized agency. Unauthorized disassembly may not only damage the terminal's sealed structure, leading to device damage or malfunction, but may also cause serious risks such as the leakage of core hardware technology and the theft of user privacy data.

[0003] Existing anti-tamper detection systems for small smart terminals mostly employ mechanical contact triggering, conductive foam contact, or ordinary Hall effect sensors combined with magnets. Among these, mechanical contact and conductive foam solutions rely on physical contact, which is prone to poor contact due to material aging and vibration impacts over long-term use. Furthermore, installation requires modification of the original terminal structure, increasing the risk of hardware damage. While ordinary Hall effect sensor solutions are non-contact, they require continuous power to maintain the detection state, consuming additional terminal power and affecting device battery life. In addition, their detection results are not non-volatile, and disassembly behavior cannot be recorded after the terminal is powered off, making it difficult to trace unauthorized disassembly in the power-off state. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the present invention provides an ultra-low power terminal disassembly and detection system based on Hall bars and reed switches. The system features miniaturization, low power consumption, and the ability to record non-volatile states when powered off, enabling equipment manufacturers to understand unauthorized disassembly of equipment during maintenance, thus addressing a key need for disassembly and detection of small smart terminals.

[0005] This invention utilizes the magnetic sensitivity of a reed switch to capture disassembly actions, combines the non-volatile resistance change characteristics of a Hall effect sensor to record the disassembly status, ensures operation during power outages through an independent power supply module, and has no power consumption under normal conditions. In conjunction with a status reading module, it enables the terminal device to read the status of the Hall effect sensor after power-on, ultimately forming a complete disassembly detection closed loop of "trigger-record-read".

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An ultra-low power terminal disassembly detection system based on Hall effect bars and reed switches includes a disassembly detection writing module and a status reading module;

[0008] The disassembly detection and writing module is used to detect the disassembly action of the terminal and permanently record the status. It includes a reed switch detection unit, an energy storage writing unit connected to the reed switch detection unit and having an independent power supply element, and a Hall bar status storage unit. The pulse output terminal of the energy storage writing unit is connected to the pulse input terminal of the Hall bar status storage unit. In the Hall bar status storage unit, the anomalous Hall resistance undergoes a non-volatile change under the action of pulse current.

[0009] The status reading module is connected to the Hall bar status storage unit and is used to read the pulse information of the Hall bar status storage unit and output the disassembly status to the terminal.

[0010] Preferably, the reed switch detection unit includes a permanent magnet and a reed switch; when the terminal is disassembled, the permanent magnet is displaced and triggers the reed switch to conduct first; as the terminal is completely disassembled, the reed switch moves away from the permanent magnet and disconnects.

[0011] Preferably, the Hall strip state storage unit includes a CoPt multilayer thin-film Hall strip device.

[0012] Preferably, the disassembly detection and writing module further includes a button battery connected to the reed switch detection unit; the energy storage writing unit includes a DC-DC boost circuit, a PMOS transistor, an energy storage capacitor Cp, and a resistor R6 for controlling the output pulse width; when the reed switch is closed, the DC-DC boost circuit operates, and the button battery, after being boosted, charges the energy storage capacitor Cp; when the reed switch is open, the PMOS transistor is turned on, and the energy storage capacitor Cp releases a current pulse to the Hall bar state storage unit.

[0013] Preferably, the status reading module includes a disassembly result output unit and a differential amplifier unit for amplifying the output voltage of the Hall bar status storage unit; the anomalous Hall voltage output terminal of the Hall bar status storage unit is connected to the input terminal of the differential amplifier unit; and the output terminal of the differential amplifier unit is connected to the disassembly result output unit.

[0014] Preferably, the status reading module further includes a constant current source reading unit, a terminal device power supply, and a power management unit that converts the terminal device power input into two different voltages to power the constant current source reading unit and the differential amplifier unit; the output terminal of the constant current source module is connected to the input terminal of the Hall bar status storage unit to provide a stable current to the Hall bar status storage unit.

[0015] Preferably, the constant current source readout unit includes an operational amplifier and a series diode to form a unidirectional path, thus avoiding interference with the write circuit signal.

[0016] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0017] 1. This invention uses Hall effect sensors as the core component. The resistance state of the Hall effect sensor is permanently changed by the pulse current. Even if the system is completely powered off, the "disassembled" state can still be retained. After power-on, it can be accurately traced, and the saved results are non-volatile.

[0018] 2. The reed switch in this invention is a non-contact trigger, which is not affected by material aging or vibration and impact, has no risk of terminal damage, and does not require modification of the original circuit or structure of the terminal. Triggering is achieved only through the displacement of the permanent magnet and the cooperation of the reed switch, thus avoiding hardware damage during the terminal disassembly and testing process.

[0019] 3. This invention has no power consumption under normal conditions, so it will not affect the device's battery life. It is powered by an independent button battery and can still work normally when the terminal device is completely powered off.

[0020] 4. The circuit adaptation of the state writing module of this invention is miniaturized, with a volume of 18.5mm × 13.5mm × 2.7mm (area approximately 250mm²). 2 Only one Hall strip device is required, and the size of a single Hall strip device is 10μm×10μm. It does not occupy extra space in the terminal, nor does it increase the thickness of the terminal or change its appearance. Attached Figure Description

[0021] Figure 1 This is a system framework diagram of Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the energy storage writing unit circuit of Embodiment 1 of the present invention;

[0023] Figure 3 This is a diagram showing the positions of the permanent magnet and reed switch during disassembly of the device in Embodiment 1 of the present invention;

[0024] Figure 4 This is a flowchart of the system judgment and disassembly process in Embodiment 1 of the present invention. Detailed Implementation

[0025] To make the technical means, inventive features, objectives, and effects of the invention readily understandable, the invention is further described below with reference to specific illustrations. However, the invention is not limited to the embodiments described below.

[0026] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0027] Example 1:

[0028] This invention proposes an ultra-low power terminal disassembly detection system based on Hall effect sensors and reed switches. It utilizes the magnetic sensitivity of reed switches to capture disassembly actions and combines the non-volatile resistance change characteristics of Hall effect sensors to record the disassembly status. An independent power supply module ensures operation during power outages and that the system consumes no power under normal conditions. In conjunction with a status reading module, the system reads the status of the Hall effect sensors after the terminal device is powered on, ultimately forming a complete disassembly detection closed loop of "trigger-record-read".

[0029] like Figure 1 The system shown is an ultra-low power terminal disassembly detection system based on Hall effect bars and reed switches, including a disassembly detection writing module and a status reading module.

[0030] The disassembly detection and writing module is used to detect terminal disassembly actions and permanently record the status, including a reed switch detection unit, an energy storage writing unit, and a Hall bar status storage unit.

[0031] The reed switch detection unit includes a permanent magnet and a reed switch. The reed switch is fixed near the permanent magnet, which is mounted on the device housing. The permanent magnet can be fixed in different positions on the terminal device according to its anti-tampering requirements. It must be ensured that when the terminal device is disassembled, the displacement of the permanent magnet triggers the reed switch to first conduct and then disconnect. Figure 3 During the disassembly process shown, the relative position of the reed switch and the small magnet is required to be such that the reed switch can be engaged in a short time during the disassembly of the terminal equipment, and not engaged when not disassembled.

[0032] The energy storage writing unit is connected to the reed switch detection unit. The energy storage writing unit includes a DC-DC boost circuit, a PMOS transistor, an energy storage capacitor Cp, and a resistor R6. For example... Figure 2 As shown, when the reed switch is closed, the DC-DC boost circuit operates, and the boosted button battery charges Cp. Due to the small capacitance, the charging process is extremely short, requiring only microseconds. When the terminal device is completely disassembled, the reed switch opens, the PMOS turns on, and Cp releases a 24mA current pulse with a pulse width of tens of microseconds to the Hall bar device in the Hall bar state storage unit. Resistor R6 is used to control the pulse width of the output pulse.

[0033] The output of diode D3 in the energy storage writing unit is connected to the Hall bar input of the Hall bar state storage unit. The Hall bar state storage unit can receive the current pulses generated by the energy storage writing unit. The output current of the energy storage writing unit is sufficient to completely change the anomalous Hall resistance state of the Hall bar device, and the direction of this current is unidirectional. Whether the terminal power supply is interrupted or not will not affect the anomalous Hall resistance state of the Hall bar, and even when the terminal device is powered off, the state of the Hall bar device can still be changed because the energy storage writing unit has an independent button battery power supply system.

[0034] The Hall strip state storage unit uses a CoPt multilayer thin-film Hall strip device (with an off-cut Al2O3 substrate). Under the action of a pulsed current, the anomalous Hall resistance (AHR) produces a non-volatile change, which is used to record the disassembly state. The CoPt multilayer thin-film Hall strip device has a size of 10μm×10μm. After testing with professional equipment, the AHR change of the device is approximately 2.3Ω. The device is connected to the circuit by ultrasonic wire bonding, with a soldering temperature ≤80℃.

[0035] The status reading module includes a terminal device power supply, a power management unit, a constant current source reading unit, a differential amplifier unit, and a disassembly result output unit.

[0036] The power management unit converts the power supplied by the terminal device to meet the operational requirements of the status reading module. The power management unit converts the terminal power input into two different voltages: a constant current source reading unit provides a stable, weak current to the Hall effect sensor; and a differential amplifier amplifies the Hall effect sensor's output voltage, which is sufficient to display two distinct states that can be identified by the disassembly result output unit. The disassembly result output unit identifies the output voltage value of the differential amplifier unit and determines whether the device has been disassembled. The constant current source reading unit's current output is connected to the input of the Hall effect sensor's status storage unit, the two inputs of the differential amplifier unit are connected to the abnormal Hall voltage output of the Hall effect sensor's status storage unit, and the disassembly result output unit is connected to the output of the differential amplifier unit.

[0037] The constant current source readout unit is built upon an operational amplifier, outputting a stable current to read the state of the Hall effect sensor. A series diode creates a unidirectional path to avoid interference with the write circuit signal. The amplitude of the current signal output by the constant current source readout unit will not exceed the critical current value that changes the Hall resistor value. The constant current source readout circuit, through the cooperation of two operational amplifiers, converts the input voltage into a constant current output, and the magnitude of the output current can be adjusted by controlling the input voltage value. The input voltage value can be adjusted by selecting the values ​​of resistors R10 and R11. The output terminal of the constant current source readout unit is connected to the Hall effect sensor input terminal of the Hall effect sensor state storage unit.

[0038] The differential amplifier unit employs a precision instrumentation amplifier. By controlling the external resistor of the precision instrumentation amplifier, a high gain is achieved, amplifying the read millivolt-level voltage to hundreds of millivolts, which is sufficient for the main control of the terminal device to read the voltage difference change. The two input terminals of the differential amplifier unit are respectively connected to the voltage output terminals of the Hall strip state storage unit. The output voltage is the state detection result. The amplification factor of the differential amplifier unit can be adjusted by adjusting the operational amplifier resistor.

[0039] When the terminal device is not disassembled, the reed switch is in the open state and normally consumes no power. After the terminal device is disassembled, the reed switch is triggered and then disconnected. The energy storage writing unit injects pulses into the Hall strip device through capacitor charging and discharging, changing the anomalous Hall resistance of the Hall strip device, that is, changing the state stored in the Hall strip state storage unit. This state is non-volatile. After the terminal body is powered on, the power management unit and the constant current source reading unit start working after receiving the terminal body's command. They begin to detect changes in the Hall strip resistance. This change is output in the form of an anomalous Hall voltage. This output is then passed through the differential amplification unit. The disassembly result output unit judges and displays the disassembly status based on the amplified anomalous Hall voltage value. The disassembly status recorded by the Hall strip device is not restored when the power is turned off or the component is reset. The disassembly result output unit can be the terminal device main controller with voltage detection capability.

[0040] In steady state, the entire writing system consumes zero power because the reed switch disconnects the button battery. During disassembly, the permanent magnet first approaches and then moves away from the reed switch. During this movement, the energy storage writing unit completes the power-on, voltage boost, pulse generation, and power-off operations. The structure-sensor-circuit-storage system completes the disassembly state detection and writing function, and the circuit design enables ultra-long standby time.

[0041] The disassembly detection writing system has a size of 18.5mm×13.5mm×2.7mm. It has no normal power consumption, and the power consumption is about 80mW when disassembly is triggered, with a duration of less than 500ms.

[0042] like Figure 4 As shown, the implementation principle of this invention is as follows:

[0043] s1. To enable disassembly and testing even when the terminal device is powered off, the energy storage writing unit has an independent button battery power supply. For example... Figure 3 As shown, during the disassembly of the terminal device, the permanent magnet briefly passes near the reed switch and attracts the reed switch. As the terminal device is completely disassembled, the permanent magnet mounted on the outer casing moves away from the reed switch and disconnects.

[0044] s2. When the reed switch is closed, as Figure 1As shown, the boost circuit operates, and the boosted button battery power charges C3. When the reed switch is off, D1 conducts, and C3 releases a 24mA current pulse with a pulse width of tens of microseconds to the Hall effect sensor. Under the influence of this pulse, the state of the Hall effect sensor undergoes a non-volatile change, which is used to record the disassembly status of the terminal device.

[0045] s3. When the terminal device is powered on, the terminal device can send a control signal to control the power management unit circuit to work. The power management unit generates power supplies of different voltages to drive the constant current source reading unit to generate a constant 1mA reading current, which is then fed into the Hall bar input terminal of the Hall bar state storage unit. This 1mA current will not change the state of the Hall bar device, but the state of the Hall bar device can be read by reading the abnormal Hall voltage of the current device, i.e., whether the device has been disassembled.

[0046] The differential amplifier unit of S4 is used to amplify the abnormal Hall voltage value. Since the input reading current is 1mA, the generated abnormal Hall voltage value is relatively small (several millivolts). Therefore, the abnormal Hall voltage output terminal of the Hall strip device is connected as follows: Figure 4 The differential amplifier unit shown has two input terminals, V+ and V-, which use differential amplification to enable the terminal device's main controller to read the current state of the Hall effect sensor. The operational amplifier resistor R... G Used to control the differential amplification factor, the differential amplification gain coefficient is calculated using the formula G = 1 + (49.4kΩ / R) G ).

[0047] s5. The disassembly result output unit determines the current disassembly status of the device based on the output of the differential amplifier unit. If the terminal device's main control has voltage reading capability, the output of the differential amplifier unit can be directly input to the terminal main control. The anomalous Hall resistance of the Hall strip device is a physical property of the device itself and is non-volatile, meaning its state is not lost due to power loss. When the device is not disassembled, the output voltage of the differential amplifier unit is 0-50mV. When the device is disassembled and the state of the Hall strip device is changed, the output voltage of the differential amplifier unit is 400-500mV. Reading the output value of the differential amplifier unit allows the reader to read the device disassembly status recorded in the Hall strip device.

Claims

1. A low-power terminal disassembly and detection system based on Hall effect bars and reed switches, characterized in that, Includes a disassembly detection and writing module and a status reading module; The disassembly detection and writing module is used to detect the disassembly action of the terminal and permanently record the status. It includes a reed switch detection unit, an energy storage writing unit connected to the reed switch detection unit and having an independent power supply element, and a Hall bar status storage unit. The pulse output terminal of the energy storage writing unit is connected to the pulse input terminal of the Hall bar status storage unit. In the Hall bar status storage unit, the anomalous Hall resistance undergoes a non-volatile change under the action of pulse current. The status reading module is connected to the Hall bar status storage unit and is used to read the pulse information of the Hall bar status storage unit and output the disassembly status to the terminal.

2. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 1, characterized in that, The reed switch detection unit includes a permanent magnet and a reed switch; when the terminal is disassembled, the permanent magnet is displaced and triggers the reed switch to conduct first; as the terminal is completely disassembled, the reed switch moves away from the permanent magnet and disconnects.

3. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 1, characterized in that, The Hall bar state storage unit includes a CoPt multilayer thin-film Hall bar device.

4. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 2, characterized in that, The disassembly detection and writing module also includes a button battery connected to the reed switch detection unit; the energy storage writing unit includes a DC-DC boost circuit, a PMOS transistor, an energy storage capacitor Cp, and a resistor R6 for controlling the output pulse width; when the reed switch is closed, the DC-DC boost circuit operates, and the button battery, after being boosted, charges the energy storage capacitor Cp; when the reed switch is open, the PMOS transistor is turned on, and the energy storage capacitor Cp releases a current pulse to the Hall bar state storage unit.

5. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 1, characterized in that, The status reading module includes a disassembly result output unit and a differential amplifier unit for amplifying the output voltage of the Hall bar status storage unit; the anomalous Hall voltage output terminal of the Hall bar status storage unit is connected to the input terminal of the differential amplifier unit; the output terminal of the differential amplifier unit is connected to the disassembly result output unit.

6. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 5, characterized in that, The status reading module further includes a constant current source reading unit, a terminal device power supply, and a power management unit that converts the terminal device power input into two different voltages to power the constant current source reading unit and the differential amplifier unit; the output terminal of the constant current source module is connected to the input terminal of the Hall bar status storage unit to provide a stable current to the Hall bar status storage unit.

7. The ultra-low power terminal disassembly and detection system based on Hall effect bars and reed switches according to claim 6, characterized in that, The constant current source readout unit includes an operational amplifier and a series diode to form a unidirectional path, avoiding interference with the write circuit signal.

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