Measurement circuit, detection apparatus and terminal device

Abstract

A measurement circuit, a detection apparatus and a terminal device, which relate to the technical field of electronics, and are used for improving the accuracy of temperature measurement for a bridge circuit. The measurement circuit comprises a bridge circuit, a first resistor and a measurement unit, wherein the bridge circuit is connected to the first resistor in series; the measurement unit comprises a first end and a second end, the first end of the measurement unit is connected to a first end of the first resistor, and the second end of the measurement unit is connected to a second end of the first resistor; and the measurement unit is used for acquiring a first voltage across the first resistor, and determining the temperature of the bridge circuit on the basis of the first voltage. The measurement circuit can use the temperature drift characteristic of a bridge resistor of a bridge circuit itself to implement measurement for the temperature of the bridge circuit; and when the bridge resistor of the bridge circuit changes with temperature in real time, a voltage signal in a circuit where the bridge circuit is located also changes in real time, such that the temperature measured by a measurement unit also changes in real time, and the temperature measured by the measurement unit can better represent the temperature of the bridge circuit, thereby achieving a high accuracy with regard to a temperature measurement result.

Description

A detection circuit, a detection device, and a terminal equipment

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410799090.9, filed on June 20, 2024, with the State Intellectual Property Office of the People's Republic of China, entitled "A Detection Circuit, Detection Device and Terminal Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of electronic technology, and in particular to a detection circuit, a detection device, and a terminal equipment. Background Technology

[0004] As one of the most important sensors in autonomous driving systems, LiDAR (Light Detection and Ranging) uses an exposed window to emit and receive laser beams, enabling accurate scanning of the surrounding environment. The point cloud data generated by LiDAR offers advantages such as long detection range, high resolution, wide field of view, and immunity to external interference. In complex and uncertain external driving environments, it provides autonomous driving systems with accurate and stable information about the external environment.

[0005] Currently, scanning lidar based on micro-electro-mechanical system (MEMS) galvanometers is a mainstream lidar architecture. It achieves laser beam scanning by oscillating the MEMS galvanometer, thereby forming 3D point cloud information. The oscillation angle of the MEMS galvanometer is crucial information in the 3D point cloud information. This oscillation angle can be measured using a Wheatstone bridge located at the root of the rotating shaft, as shown in Figure 1a. Simultaneously, to compensate for temperature variations in the measurement results, a negative temperature coefficient thermistor (NTC) needs to be mounted on the flexible printed circuit (FPC) connecting the Wheatstone bridge to the lidar board. Based on the temperature detected by the NTC, error compensation can be applied to the measured oscillation angle of the MEMS galvanometer, thereby improving the accuracy of the 3D point cloud information.

[0006] However, because the NTC is mounted at a certain distance from the Wheatstone bridge, there will be a significant error between the temperature detected by the NTC and the actual temperature of the Wheatstone bridge. This is especially true when the temperature of the Wheatstone bridge changes abruptly; the temperature detected by the NTC cannot accurately represent the real-time temperature of the Wheatstone bridge. The less accurate the temperature detected by the NTC, the less accurate the temperature compensation for angle measurements based on that temperature will be, which is detrimental to improving the accuracy of 3D point cloud information. Summary of the Invention

[0007] This application provides a detection circuit, a detection device, and a terminal device to improve the accuracy of temperature detection of bridge circuits (such as Wheatstone bridges).

[0008] In a first aspect, this application provides a detection circuit, including a bridge circuit, a first resistor, and a detection unit. The bridge circuit is connected in series with the first resistor, and one end of the series link is used to receive a power supply voltage, while the other end of the series link is grounded. The detection unit includes a first terminal and a second terminal. The first terminal of the detection unit is connected to the first terminal of the first resistor, and the second terminal of the detection unit is connected to the second terminal of the first resistor. The detection unit is used to acquire a first voltage across the first resistor and determine the temperature of the bridge circuit based on the first voltage.

[0009] Using the above method, since the first resistor is connected in series with the bridge circuit, the sum of the first voltage across the first resistor and the voltage of the bridge circuit is the supply voltage. When the temperature of the bridge circuit changes, the bridge resistance also changes, causing a change in the bridge circuit voltage, which in turn causes a change in the first voltage across the first resistor. In other words, there is a one-to-one correspondence between the first voltage across the first resistor and the temperature of the bridge circuit. Based on this, the detection unit can determine the temperature of the bridge circuit by detecting the first voltage across the first resistor. Using this method, the temperature detected by the detection unit is obtained from the voltage signal across the first resistor connected in series in the circuit containing the bridge circuit. This method utilizes the temperature drift characteristics of the bridge circuit's resistance to detect its temperature, thus the detected temperature can directly characterize the bridge circuit's temperature. Moreover, when the bridge resistance changes in real time with the temperature, the voltage signal in the circuit containing the bridge circuit also changes in real time. Therefore, the temperature detected by the detection unit also changes in real time, and the temperature detected by the detection unit can accurately characterize the temperature of the bridge circuit, resulting in a high degree of accuracy.

[0010] In one possible design, the bridge circuit is connected in series with the first resistor, and can be any of the following circuit forms: Circuit Form 1, the first end of the bridge circuit is used to receive the supply voltage, the second end of the bridge circuit is connected to the first end of the first resistor, and the second end of the first resistor is grounded; or, Circuit Form 2, the first end of the first resistor is used to receive the supply voltage, the second end of the first resistor is connected to the first end of the bridge circuit, and the second end of the bridge circuit is grounded.

[0011] The above design allows the first resistor to be connected in series at the power supply or ground terminal of the bridge circuit, thereby improving the flexibility of circuit setup and meeting the different needs of practical application scenarios.

[0012] In one possible design, the detection unit can determine the temperature of the bridge circuit in any of the following ways:

[0013] In Method 1, the detection unit determines the temperature of the bridge circuit based on a first voltage and a preset voltage-temperature correlation. In other words, the detection unit only needs to obtain the first voltage inputs at the first and second terminals to determine the corresponding temperature by referring to the preset correlation. Method 1 involves relatively fewer steps and has higher temperature detection efficiency.

[0014] Method Two: The detection unit first determines the current in the bridge circuit based on the first voltage and the resistance value of the first resistor. Then, based on the current in the bridge circuit and the supply voltage, it determines the current bridge resistance. Finally, based on the current bridge resistance and the preset relationship between bridge resistance and temperature, it determines the temperature of the bridge circuit. In other words, the detection unit can first perform some calculations based on the first voltage input to the first and second terminals to obtain the bridge resistance of the bridge circuit. Then, it can use the temperature drift characteristic of the bridge resistance to look up the temperature corresponding to the current bridge resistance. Method Two can directly utilize the temperature drift characteristic for temperature detection, making the temperature detection more direct and accurate.

[0015] In one possible design, the first resistor could be a shunt resistor.

[0016] With the above design, the resistance value of the first resistor is small, so the voltage drop across the first resistor is small. This minimizes the impact on the voltage across the bridge circuit, allowing the voltage of the bridge circuit to approach the supply voltage, thereby avoiding any impact on the function of the bridge circuit itself and ensuring the sensitivity of the output signal of the bridge circuit.

[0017] In one possible design, the detection unit may include a first amplification circuit and a first control unit. The first input terminal of the first amplification circuit is the first terminal of the detection unit, the second input terminal of the first amplification circuit is the second terminal of the detection unit, and the output terminal of the first amplification circuit is connected to the first control unit. The first amplification circuit is used to amplify the first voltage. The first control unit is used to determine the first voltage based on the amplified first voltage and the amplification factor of the first amplification circuit, and to determine the temperature of the bridge circuit based on the first voltage.

[0018] With the above design, even if the resistance of the first resistor is small, resulting in a small first voltage, the first amplifier circuit can amplify the originally very small first voltage into a larger voltage that can be accurately detected. After the first control unit calculates the original first voltage in reverse, the temperature of the bridge circuit can be determined based on the relatively accurate first voltage, thereby improving the accuracy of temperature detection.

[0019] In a further possible design, the first amplifier circuit may include a differential amplifier.

[0020] Through the above design, the differential amplifier has a relatively low cost while maintaining high accuracy, thus saving costs while ensuring accurate temperature detection.

[0021] In one possible design, the detection unit can also determine the current of the bridge circuit based on the first voltage and the resistance value of the first resistor. If the current of the bridge circuit does not meet the preset current condition, a fault alarm will be triggered.

[0022] Through the above design, the detection unit can also detect whether a common-mode failure has occurred in the bridge circuit.

[0023] In further possible designs, the preset current conditions may include at least one of the following: the current of the bridge circuit is less than or equal to the short-circuit current threshold within a set time period; the current of the bridge circuit is greater than or equal to the open-circuit current threshold within a set time period; the absolute value of the change in the current of the bridge circuit relative to the set current is less than or equal to the impedance drift current threshold within a set time period.

[0024] With the above design, the detection unit can detect short-circuit faults, open-circuit faults, and impedance drift faults in the bridge circuit.

[0025] In a further possible design, the current is set to be related to the temperature of the bridge circuit.

[0026] Through the above design, the temperature drift characteristics of the bridge circuit resistor can be used to set current references for different temperature environments. Impedance drift faults are only identified after the measured current exceeds the setting limit of the reference current at a specific temperature, thus improving the detection accuracy of impedance drift faults.

[0027] In one possible design, the bridge circuit may include a second resistor, a third resistor, a fourth resistor, and a fifth resistor, which are connected end to end in sequence. At least one of the second, third, fourth, and fifth resistors is a varistor. The series connection node between the second and third resistors is the first end of the bridge circuit, and the series connection node between the fourth and fifth resistors is the second end of the bridge circuit.

[0028] With the above design, the resistance of the varistor will change with the change of the pressure it is subjected to, which in turn causes the differential voltage output by the bridge circuit to change. Thus, the angle of the bridge circuit can be measured based on the magnitude of the differential voltage output by the bridge circuit.

[0029] In one possible design, at least one of the second, third, fourth, and fifth resistors is a resistor with temperature drift characteristics. For example, the second, third, fourth, and fifth resistors are all resistors with temperature drift characteristics. Thus, the resistance values ​​of the second to fifth resistors will change with temperature variations, consequently causing a change in the bridge resistance of the entire bridge circuit. Therefore, the temperature of the bridge circuit can be measured by utilizing the change in bridge resistance at different temperatures.

[0030] In a further possible design, the bridge circuit is set on the shaft, and the detection unit also includes a third terminal and a fourth terminal. The third terminal is connected to the series node between the second resistor and the fifth resistor, and the fourth terminal is connected to the series node between the third resistor and the fourth resistor. The detection unit is also used to obtain a second voltage through the third terminal and the fourth terminal, and to obtain a third voltage by temperature compensation of the second voltage using the temperature of the bridge circuit, and to determine the rotation angle of the shaft based on the third voltage.

[0031] Through the above design, the detection unit can also realize the function of detecting the rotation angle of the shaft where the bridge circuit is located.

[0032] In a further possible design, the detection unit can first determine the target voltage compensation value based on the temperature of the bridge circuit and the preset correspondence between temperature and voltage compensation value, then use the target voltage compensation value to compensate the second voltage to obtain the third voltage, and then determine the rotation angle of the shaft based on the third voltage and the preset correspondence between voltage and rotation angle.

[0033] With the above design, since the third voltage is obtained after temperature compensation of the second voltage, the temperature environment used for the correspondence between the third voltage and the calibration is consistent. By using the third voltage to query the preset correspondence between voltage and angle, a relatively accurate angle measurement result can be obtained.

[0034] In a further possible design, the detection unit may include a second amplification circuit and a second control unit. The first input terminal of the second amplification circuit is the third terminal of the detection unit, the second input terminal of the second amplification circuit is the fourth terminal of the detection unit, and the output terminal of the second amplification circuit is connected to the second control unit. The second amplification circuit is used to amplify the second voltage. The second control unit is used to determine the second voltage based on the amplified second voltage and the amplification factor of the second amplification circuit, to perform temperature compensation on the second voltage using the temperature of the bridge circuit to obtain a third voltage, and to determine the rotation angle of the shaft based on the third voltage.

[0035] With the above design, even if the second voltage is small and the difference between the second voltages at different angles is small, the second amplifier circuit can amplify the originally very small second voltage into a larger voltage that can be accurately detected. After the second control unit calculates the original second voltage in reverse, the rotation angle of the shaft where the bridge circuit is located can be determined based on the relatively accurate second voltage, so as to improve the accuracy of angle detection.

[0036] In further possible designs, the second control unit and the first control unit may be the same control unit or different control units.

[0037] The above design allows for the integrated design or separate configuration of different control units, meeting the needs of different scenarios.

[0038] Secondly, this application provides a detection device, including a detection circuit as described in the first aspect or any of the designs in the first aspect.

[0039] In one possible design, the detection device may further include a scanning component and a circuit board. The bridge circuit in the detection circuit is disposed on the scanning component, and the first resistor and the detection unit in the detection circuit are disposed on the circuit board. The circuit board can be any type of circuit board, such as a printed circuit board (PCB), a printed circuit board assembly (PCBA), a ceramic circuit board, an aluminum substrate, a thick copper plate, an impedance board, a circuit board, etc., without specific limitations.

[0040] With the above design, temperature detection of the bridge circuit can be achieved simply by adding a first resistor and a detection unit to the circuit board and connecting them to the existing bridge circuit on the scanning component. This eliminates the need to mount an NTC on the FPC connected to the MEMS galvanometer. Therefore, it can save material and manufacturing costs, does not increase the complexity of the FPC, and also has high reliability.

[0041] Further possible designs also include FPCs, through which electrical components on the scanning assembly and on the circuit board are connected.

[0042] With the above design, corresponding connection lines can be added to the FPC to connect the first resistor and detection unit on the circuit board with the bridge circuit on the scanning component.

[0043] In a further possible design, the scanning component includes a reflector and a rotating shaft. The reflector oscillates around the rotating shaft at a first operating frequency, and the detection unit acquires a first voltage at a first sampling frequency, wherein the first sampling frequency is greater than three times the first operating frequency.

[0044] With the above design, the detection unit can acquire at least three first voltages within one oscillation cycle of the reflector, and determine the temperature of the bridge circuit based on the at least three first voltages. This can eliminate the influence of stress generated during the periodic rotation of the shaft on the bridge resistance of the bridge circuit.

[0045] In a further possible design, the detection unit is specifically used to: acquire multiple first voltages at a first sampling frequency within one swing cycle of the reflector, and determine the temperature of the bridge circuit based on the average voltage of the multiple first voltages.

[0046] With the above design, the detection unit can determine the temperature of the bridge circuit based on the average voltage of multiple first voltages. The temperature of the bridge circuit can be used to characterize the average temperature of the bridge circuit within one oscillation cycle of the reflector. This average temperature is more accurate than the temperature corresponding to a single sampling.

[0047] Thirdly, this application provides a terminal device including the detection device in the second aspect or any of the designs described above.

[0048] The technical effects that can be achieved by the second and third aspects mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0049] Figure 1a illustrates a schematic diagram of the connection structure of a MEMS galvanometer, an FPC, and a radar board.

[0050] Figure 1b illustrates an exemplary method for determining the left-hand rule;

[0051] Figure 2 illustrates a possible application scenario to which this application applies;

[0052] Figure 3a illustrates a schematic diagram of an angle detection circuit provided in the industry.

[0053] Figure 3b illustrates an exemplary scenario of common-mode failure provided in this application;

[0054] Figure 4 illustrates a schematic diagram of a detection circuit provided in this application.

[0055] Figure 5a illustrates a schematic diagram of a specific structure of a detection circuit provided in this application;

[0056] Figure 5b illustrates a schematic diagram of another detection circuit provided in this application.

[0057] Figure 6 illustrates a schematic diagram of the structure of a detection unit provided in this application;

[0058] Figure 7 illustrates a schematic diagram of the structure of a first amplifier circuit provided in this application;

[0059] Figure 8 illustrates an exemplary configuration of a bridge circuit in a rotating shaft according to this application.

[0060] Figure 9 illustrates a schematic diagram of the specific structure of another detection circuit provided in this application;

[0061] Figure 10 illustrates a schematic diagram of another detection unit provided in this application;

[0062] Figure 11a illustrates a schematic diagram of another detection unit provided in this application;

[0063] Figure 11b illustrates a schematic diagram of another detection unit provided in this application;

[0064] Figure 12 illustrates a schematic diagram of the structure of a detection device provided in this application;

[0065] Figure 13a shows an exemplary structural schematic diagram of a MEMS galvanometer provided in this application;

[0066] Figure 13b illustrates, for example, a schematic diagram of the working principle of a MEMS galvanometer provided in this application;

[0067] Figure 13c illustrates a schematic diagram of a bridge circuit configuration in a MEMS galvanometer according to this application.

[0068] Figure 13d illustrates an exemplary connection structure of a MEMS galvanometer, an FPC, and a radar board provided in this application.

[0069] Figure 13e illustrates a schematic diagram of the circuit partitioning method of a detection circuit provided in this application. Detailed Implementation

[0070] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0071] The following provides explanations for some of the terms used in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0072] I. Left-hand rule.

[0073] The left-hand rule can be used to determine the direction of the Lorentz force on a current-carrying conductor in a magnetic field. Referring to Figure 1b, when applying the left-hand rule, extend your left hand so that the magnetic field lines pass perpendicularly through your palm, with your four fingers pointing in the direction of the current I. The direction your thumb points is the direction of the Lorentz force F. When the magnetic field strength is B and the length of the current-carrying conductor is L, the Lorentz force F and the current I satisfy the following relationship: F ​​= BIL. In other words, the Lorentz force F and the current I are positively correlated; the larger the current I, the larger the Lorentz force F, and the smaller the current I, the smaller the Lorentz force F. Therefore, by adjusting the current in the conductor, the magnitude of the Lorentz force on the conductor can be adjusted.

[0074] II. Automotive Safety Integrity Level (ASIL).

[0075] ASIL is a rating system used to assess the safety and reliability of automotive electronics, and it is widely used in the automotive industry. According to ASIL ratings, automotive safety can be divided into four levels: ASIL A, ASIL B, ASIL C, and ASIL D. ASIL A is the lowest level, representing the lowest degree of automotive hazard, while ASIL D is the highest level, representing the highest degree of automotive hazard.

[0076] Typically, airbags, anti-lock braking systems (ABS), and power steering systems must meet ASIL D standards, the most stringent level for safety assurance due to the highest risk of failure. The lowest safety levels, such as taillights, only require ASIL A. Headlights, brake lights, and radar sensors are usually ASIL B, while cruise control is typically ASIL C.

[0077] III. Differential mode failure and common mode failure.

[0078] In a symmetrical circuit structure, differential mode failure refers to the original symmetrical circuit becoming no longer symmetrical, while common mode failure refers to the circuit still being symmetrical, but other faults occurring, such as short circuit faults, open circuit faults, or impedance drift faults.

[0079] The preceding text introduced some of the terms used in this application. The following text introduces the possible application scenarios of this application.

[0080] In one possible implementation, the detection circuit provided in this application can be applied to a detection device, which can be installed on a vehicle. The detection device may include, but is not limited to, lidar. Please refer to Figure 2, which exemplifies a possible application scenario of this application, where the detection device is installed on the front bumper of the vehicle. It is understood that the detection device can also be installed in other locations on the vehicle, such as around the headlights, around the rearview mirrors, near the doors, on the rear bumper, behind the windshield, or on the roof, to capture information about the vehicle's surrounding environment. When the detection device is installed behind the windshield, the requirement for no stone collision is lower, it does not affect the vehicle's appearance, and the windshield itself has window heating and defogging functions as well as wiper cleaning functions.

[0081] It should be understood that the above application scenarios are merely examples, and the detection device provided in this application can also be applied to other possible scenarios, not limited to those listed above. For example, the detection device can also be installed in a roadside unit (RSU) as a roadside traffic detection device to realize intelligent vehicle-road cooperative communication, etc. As another example, the detection device can also be applied to other means of transportation as an information collection source for route planning, to assist drivers in achieving or automatically achieving safe driving. Other means of transportation may include, but are not limited to, ships, airplanes, drones, trains, subways, automated guided vehicles (AGVs), or unmanned transport vehicles. Furthermore, the detection device can also be applied to terminal devices or components installed in terminal devices. Terminal devices may include, for example, smartphones, smart home devices, smart manufacturing equipment, medical devices, industrial equipment, and robots, etc. These will not be listed exhaustively here. It should be noted that the application scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application.

[0082] In addition, the above-mentioned application scenarios can be applied to fields such as autonomous driving, assisted driving, intelligent driving, autonomous driving, connected vehicles, optical communication, security monitoring, biomedicine, surveying and mapping (such as 3D mapping and remote sensing mapping), meteorological research, biomass and vegetation research, air quality monitoring, and aviation and aerospace applications.

[0083] Currently, MEMS galvanometer-based scanning systems are the most common type of scanning system in detection devices. This scanning system scans the target area by driving a mirror (also called a galvanometer) in the MEMS to oscillate, thereby changing the direction of the emitted beam. To measure the oscillation angle of the mirror, as shown in Figure 1a, a Wheatstone bridge can be placed at the root of the mirror's shaft, and an angle detection unit can be placed on the radar board. The Wheatstone bridge and the angle detection unit are electrically connected via an FPC. The relevant circuit structure can be seen in Figure 3a. The Wheatstone bridge may include four silicon-based piezoresistors connected end-to-end, i.e., R... 01 R 02 R 03 R 04 R 01 ~R 04 The four arms of the Wheatstone bridge constitute the electrical system. Referring to Figures 1a and 3a, in the initial setup, when the reflector is not rotating, the shaft does not twist, and R... 01 R 02 R 03 R 04 Since all four arms have the same resistance, they are symmetrical, and the voltage difference V between node C and node D is constant. out (i.e. V) C -V D The differential voltage (also known as the differential voltage) is 0. When the mirror rotates to different angles, the shaft twists to varying degrees, causing R to... 01 R 02 R 03 R 04 Having different stress states, R 01 R 02 R 03 R 04 The resistance values ​​are no longer the same, and the voltage difference V between node C and node D is... out (i.e. V) C -V D The value is not zero. Based on this, the angle detection unit detects the voltage difference V between node C and node D. out This allows us to determine the degree of rotation of the shaft, and consequently, the swing angle of the reflector.

[0084] However, because the resistance of silicon-based piezoresistors is significantly affected by temperature, the resistance of a silicon-based piezoresistor under the same stress state will have very significant differences under different temperature conditions (also known as temperature drift). Therefore, the output signal of the Wheatstone bridge (i.e., V) outThe output signal can become inaccurate due to temperature variations, requiring temperature compensation. However, as described in the background section, the current industry standard for temperature measurement is to mount a separate NTC on the FPC. This method has the following problems:

[0085] Problem 1: Poor accuracy of temperature detection. Specifically, referring to Figure 1a, since the NTC is mounted on the FPC, and there is a certain distance between the FPC and the root of the shaft, there will be a certain difference between the temperature detected by the NTC and the actual temperature of the Wheatstone bridge at the root of the shaft. In particular, when the temperature of the Wheatstone bridge changes abruptly, the NTC cannot detect the real-time temperature of the Wheatstone bridge in time, and the temperature detected by the NTC cannot accurately represent the temperature of the Wheatstone bridge.

[0086] The second issue is increased costs. For example, additional NTCs increase material costs. Furthermore, mounting NTCs onto the FPC requires a separate surface-mount technology (SMT) process, which significantly increases assembly costs.

[0087] Thirdly, the problem is its high complexity and poor reliability. Specifically, mounting NTCs onto FPCs not only increases the complexity of FPC manufacturing but also poses a risk of NTC detachment. For example, when NTCs are mounted onto FPCs via soldering, the solder joints are prone to detachment, resulting in reliability risks.

[0088] In addition to the problems with existing temperature measurement methods, existing angle measurement methods also have some issues. For example, current angle measurement methods can only detect differential mode failure faults in Wheatstone bridges, but cannot detect common mode failure faults. Specifically, according to the initial design, the output signal V of the Wheatstone bridge... out The value should be 0 when the reflector is not oscillating, but if the angle detection unit detects V... out When the reflector is not oscillating, a value that is not zero indicates that the four arms of the Wheatstone bridge are no longer symmetrical, and the Wheatstone bridge has experienced differential mode failure. In other words, the angle detection unit detects the output signal V of the Wheatstone bridge. out This can determine whether a Wheatstone bridge has experienced a differential-mode failure. However, when the reflector is not wobbling (or the shaft is stationary in its equilibrium position), if a common-mode failure occurs in the Wheatstone bridge, the output signal V of the Wheatstone bridge will be affected. out It will remain at 0, but other electrical signals in the Wheatstone bridge (such as current or bridge resistance) will become abnormal.

[0089] For example, a typical common-mode failure is illustrated in Figure 3b. Combining Figures 3a and 3b, when the pin of ground node B of the Wheatstone bridge is corroded, rust spots (dense small dots as shown in Figure 3b) will appear on the pin. The presence of these rust spots creates additional impedance at ground node B. This additional impedance diverts a portion of the supply voltage, causing the voltage across the Wheatstone bridge to decrease, and consequently, the current in the Wheatstone bridge to decrease. This phenomenon is known as impedance drift. Impedance drift affects the current in the Wheatstone bridge; in some scenarios, it can cause the current to exceed the set value, while in others, it can cause it to fall below the set value. Whether the current exceeds or falls below the set value, it will affect the differential voltage v of the bridge circuit in the unbalanced position (i.e., when the mirror is oscillating). out This has an impact, which in turn leads to the differential voltage v out The detected angle exhibits a bias voltage. When the impact is severe, it can even render the angle detection scheme based on the Wheatstone bridge unusable, seriously affecting the function of the detection device. In addition to common-mode failure due to impedance drift, other common-mode failures exist, such as a short circuit between node A and node B, which causes the current in the Wheatstone bridge to suddenly become a very large value (usually greater than 5A); or an open circuit between node A and the power supply terminal, or an open circuit between node B and the ground terminal, which causes the current in the Wheatstone bridge to suddenly drop to a very small value (nearly 0), and so on.

[0090] Understandably, any type of common-mode failure will affect the angle detection scheme of the Wheatstone bridge. The functional safety level requirement for radar is ASIL-B; theoretically, when a common-mode failure occurs in the Wheatstone bridge, it must be able to detect and report the fault to maintain the radar's safety level. However, the currently available angle detection scheme only detects the output signal V. out Based on this, there is no way to detect the above-mentioned anomalies. In other words, the current angle detection solution does not have an effective fault monitoring method for the common mode failure anomaly of Wheatstone bridge.

[0091] In view of this, this application provides a detection circuit that, while measuring the temperature of a bridge circuit (such as a Wheatstone bridge), achieves the effects of improving measurement accuracy, saving costs, reducing complexity, and improving reliability. Furthermore, it can also detect whether a common-mode failure has occurred in the Wheatstone bridge.

[0092] The detection circuit proposed in this application will be described in detail below with reference to the accompanying drawings.

[0093] In the description of this application, "connection" can refer to an electrical connection, which can be a direct or indirect connection between two electrical components. For example, the connection between M and N can be a direct connection between M and N, or an indirect connection between M and N through one or more other electrical components, such as the connection between M and N. Alternatively, it can be a direct connection between M and G, with G directly connected to N, and M and N connected through G. In some scenarios, "connection" can also be understood as coupling, such as electromagnetic coupling between two inductors. In short, the connection between M and N enables the transfer of electrical energy between them.

[0094] Furthermore, the terminal names of electronic components in this application are merely exemplary descriptions and can be understood as connection terminals or connection points used for connecting to other circuit components. In other examples, other terminal names, connection terminal names, or connection point names may also be used. For example, in some scenarios, a terminal may also be referred to as a communication terminal, information transmission terminal, terminal, connection terminal, communication connection terminal, information connection terminal, connection point, communication connection point, information connection point, or electrode, etc.

[0095] Please refer to Figure 4, which shows a schematic diagram of a detection circuit provided in this application. The detection circuit includes a bridge circuit 410, a first resistor R1, and a detection unit 420. The bridge circuit 410 is connected in series with the first resistor R1, with one end of the series link used to receive the supply voltage (VCC) and the other end grounded. The detection unit 420 includes a first terminal (a1) and a second terminal (a2). The first terminal a1 of the detection unit 420 is connected to the first terminal (b1) of the first resistor R1, and the second terminal a2 of the detection unit 420 is connected to the second terminal (b2) of the first resistor R1.

[0096] In this circuit, bridge circuit 410 is connected in series with the first resistor R1, for example, as shown in Example 1 or Example 2:

[0097] Example 1: Bridge circuit 410 is located at the position indicated by the dashed line in Figure 4. That is, the first terminal (A) of bridge circuit 410 is used to receive the supply voltage VCC, the second terminal (B) of bridge circuit 410 is connected to the first terminal b1 of the first resistor R1, and the second terminal b2 of the first resistor R1 is grounded. In this circuit configuration, the current generated by the supply voltage VCC first flows through bridge circuit 410, and then flows through the first resistor R1;

[0098] Example 2: Bridge circuit 410 is located at the position indicated by the solid line in Figure 4. That is, the first terminal b1 of the first resistor R1 is used to receive the supply voltage VCC, the second terminal b2 of the first resistor R1 is connected to the first terminal A of bridge circuit 410, and the second terminal B of bridge circuit 410 is grounded. In this circuit configuration, the current generated by the supply voltage VCC first flows through the first resistor R1, and then flows through bridge circuit 410.

[0099] Based on the above detection circuit, the detection unit 420 can obtain the first voltage (V1) across the first resistor R1 through its first terminal a1 and second terminal a2, and can determine the temperature of the bridge circuit 410 based on the first voltage V1. It is understandable that since the first resistor R1 is connected in series with the bridge circuit 410, the sum of the first voltage V1 across the first resistor R1 and the voltage of the bridge circuit 410 is the supply voltage VCC. When the temperature of the bridge circuit 410 changes, the bridge resistance of the bridge circuit 410 also changes, causing a change in the voltage of the bridge circuit 410, which in turn causes a change in the first voltage V1 across the first resistor R1. In other words, there is a one-to-one correspondence between the first voltage V1 across the first resistor R1 and the temperature of the bridge circuit 410. Based on this, the detection unit 420 can determine the temperature of the bridge circuit 410 by detecting the first voltage V1 across the first resistor R1.

[0100] For example, in one instance, the detection unit 420 can determine the temperature of the bridge circuit 410 based on the first voltage V1 across the first resistor R1 and a preset first voltage-temperature correspondence. This preset voltage-temperature correspondence can be pre-calibrated. For instance, the entire detection circuit can be placed in different temperature environments with the same supply voltage VCC (typically 3.3V in automotive applications) input. Then, the voltage across the first resistor R1 is measured in each temperature environment, and a preset voltage-temperature correspondence is established based on these measurements. This first correspondence indicates the voltage change across the first resistor R1 when the bridge circuit 410 is in different temperature environments. Therefore, the detection unit 420 can obtain the current temperature of the bridge circuit 410 by querying the preset voltage-temperature correspondence based on the current first voltage V1 across the first resistor R1 during use.

[0101] For example, in another example, the detection unit 420 can first determine the current in the series link based on the first voltage V1 across the first resistor R1 and the resistance value of the first resistor R1. Then, based on the current in the series link, the supply voltage VCC, and the resistance value of the first resistor R1, it can determine the bridge resistance of the bridge circuit 410. Afterward, it can determine the temperature of the bridge circuit 410 based on the bridge resistance of the bridge circuit 410 and a preset correspondence between bridge resistance and temperature. The preset correspondence between bridge resistance and temperature can be pre-calibrated. For example, the bridge circuit 410 can be placed in different temperature environments in advance, and the bridge resistance of the bridge circuit 410 can be measured in each temperature environment. Then, a preset correspondence between bridge resistance and temperature can be established based on the bridge resistance measured in each temperature environment. This correspondence indicates the change in bridge resistance of the bridge circuit 410 when it is in different temperature environments. Therefore, the detection unit 420 can obtain the current temperature of the bridge circuit 410 by querying the preset correspondence between bridge resistance and temperature based on the current bridge resistance of the bridge circuit 410 during use.

[0102] In the above example, the bridge resistor of bridge circuit 410 can be implemented through the following steps 1.1 to 1.3:

[0103] Step 1.1, the detection unit 420 calculates the resistance value of the first resistor R1 according to Ohm's law based on the first voltage V1 across the first resistor R1 and the resistance value of the first resistor R1.

[0104] Calculate the current I1 flowing through the first resistor R1: Since the first resistor R1 is connected in series with the bridge circuit 410, the current I1 flowing through the first resistor R1 is also the current of the bridge circuit 410, which is the current of the series link.

[0105] Step 1.2, the detection unit 420 calculates the resistance R of the series link according to Ohm's law based on the current I1 flowing through the first resistor R1 and the supply voltage VCC:

[0106] Step 1.3, the resistance R of the series link is the bridge resistance R of the bridge circuit. 410 The sum of the resistance values ​​of the detection circuit and the first resistor R1 is used to calculate the bridge resistance R of the bridge circuit. 410 :R 410 =R-R1.

[0107] Based on steps 1 to 3 above, it can be seen that the bridge resistance R of bridge circuit 410 is... 410 It satisfies the following formula (1.1):

[0108] For example, in another example, the detection unit 420 can determine the voltage of the bridge circuit 410 based on the first voltage V1 across the first resistor R1 and the supply voltage VCC. Then, it can determine the temperature of the bridge circuit 410 based on the voltage of the bridge circuit 410 and a preset second voltage-temperature correspondence. This preset voltage-temperature correspondence can be pre-calibrated. For instance, the entire detection circuit can be placed in different temperature environments with the same supply voltage VCC input. The voltage across the bridge circuit 410 can then be measured in each temperature environment, and a preset voltage-temperature correspondence can be established based on the measured voltages. This second correspondence indicates the voltage change across the bridge circuit 410 when it is in different temperature environments. Therefore, the detection unit 420 can obtain the current temperature of the bridge circuit 410 by querying the preset voltage-temperature correspondence based on the current voltage of the bridge circuit 410 during use.

[0109] It should be noted that the above content only exemplifies three possible temperature detection methods. Actual detection circuits may employ other temperature detection methods. For example, in another example, the detection unit 420 may first determine the current in the series link based on the first voltage V1 across the first resistor R1 and the resistance value of the first resistor R1, and then directly obtain the current temperature of the bridge circuit 410 based on the current in the series link and a preset correspondence between current and temperature. Alternatively, in yet another example, the detection unit 420 may first determine the current in the series link based on the first voltage V1 across the first resistor R1 and the resistance value of the first resistor R1, then determine the resistance value of the series link based on the current in the series link and the supply voltage VCC, and then directly obtain the current temperature of the bridge circuit based on the resistance value of the series link and a preset correspondence between resistance value and temperature. And so on, there are many other possible temperature detection schemes, which will not be listed here.

[0110] Understandably, regardless of the temperature detection scheme, the temperature detected by the detection unit 420 is obtained from the voltage signal of the first resistor R1 connected in series in the circuit containing the bridge circuit 410. This temperature can be used to directly characterize the temperature of the bridge circuit 410. Moreover, when the bridge resistance of the bridge circuit 410 changes in real time with the temperature, the voltage signal in the circuit containing the bridge circuit 410 also changes in real time. Therefore, the temperature detected by the detection unit 420 also changes in real time. The temperature detected by the detection unit 420 can well characterize the temperature of the bridge circuit 410, and the accuracy of this temperature detection result is high.

[0111] To further illustrate the solution, the components involved in Figure 4 will be described below to provide an exemplary implementation scheme.

[0112] I. Bridge circuit

[0113] Bridge circuit 410, also known as a bridge circuit, is a bridge-shaped circuit composed of four resistors connected end-to-end. The four resistors are also called the four arms of the bridge. A typical example of bridge circuit 410 is the Wheatstone bridge. However, it should be understood that bridge circuit 410 can also be any bridge circuit with four resistors, and this application does not specifically limit it.

[0114] For example, taking the case where current flows through bridge circuit 410 first and then through first resistor R1 (corresponding to Example 1 above), please refer to Figure 5a, which shows a specific structural diagram of a detection circuit provided in this application. In this example, bridge circuit 410 may include a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5, which are connected end-to-end in sequence. The series connection node between the second resistor R2 and the third resistor R3 is the first terminal A of bridge circuit 410, used to receive the supply voltage VCC. The series connection node between the fourth resistor R4 and the fifth resistor R5 is the second terminal B of bridge circuit 410, used to connect to the first terminal b1 of the first resistor R1, and the second terminal b2 of the first resistor R1 is grounded.

[0115] Optionally, at least one of the second resistor R2 to the fifth resistor R5 is a resistor with temperature drift characteristics, such as a varistor (also known as a silicon-based piezoresistor). The resistance of the silicon-based piezoresistor drifts with temperature changes, which in turn causes a change in the bridge resistance of the entire bridge circuit 410. Therefore, the temperature of the bridge circuit 410 can be measured based on the bridge resistance change produced by at least one silicon-based piezoresistor at different temperatures.

[0116] Specifically, when the bridge circuit 410 is a Wheatstone bridge, the second resistor R2 to the fifth resistor R5 can all be resistors with temperature drift characteristics. In this case, the change in the bridge resistance of the entire bridge circuit 410 is related to the temperature drift characteristics of the second resistor R2 to the fifth resistor R5.

[0117] Optionally, when the bridge circuit 410 is in a balanced state (e.g., the silicon-based piezoresistors in the bridge circuit 410 are not under voltage), the resistance values ​​of the second resistor R2 to the fifth resistor R5 can be the same or different. For example, when the bridge circuit 410 is a Wheatstone bridge, in the balanced state of the bridge circuit 410, the resistance values ​​of the second resistor R2 to the fifth resistor R5 are all the same. In this case, the output voltage at either end of any diagonal of the bridge circuit 410 is 0. For example, referring to Figure 5a, assuming that the series connection point between the second resistor R2 and the fifth resistor R5 is the third terminal C of the bridge circuit, and the series connection point between the third resistor R3 and the fourth resistor R4 is the fourth terminal D of the bridge circuit, then the second voltage V2 between the third terminal C and the fourth terminal D is 0 in the balanced state of the bridge circuit 410.

[0118] It is understandable that since the second terminal b2 of the first resistor R1 is grounded, the second terminal a2 of the detection unit 420 is connected to the second terminal b2 of the first resistor R1. It can also be considered that the second terminal a2 of the detection unit 420 is grounded, as shown in Figure 5b.

[0119] II. First Resistor

[0120] Optionally, the first resistor R1 can be a shunt resistor. A shunt resistor is a high-precision ammeter resistor used to measure current in a circuit, characterized by high accuracy, low temperature drift, and small resistance. Therefore, when the temperature change is small, the resistance of the shunt resistor can be considered essentially constant, and this resistance is very low relative to the bridge resistance of bridge circuit 410, typically less than 10 ohms. Using a small-value first resistor R1 reduces the voltage drop across it, minimizing its impact on the voltage across bridge circuit 410. In other words, it allows the voltage across bridge circuit 410 to approach the supply voltage VCC, thus avoiding any impact on the function of bridge circuit 410 itself and ensuring the sensitivity of its output signal (such as the second voltage V2).

[0121] III. Detection Unit

[0122] Here, the detection unit 420 can be any unit capable of realizing temperature detection, such as a control unit or logic gate circuit.

[0123] Understandably, when the resistance of the first resistor R1 is very small, the first voltage V1 across the first resistor R1 is also very small, resulting in a small voltage change in the first voltage V1 under different temperature conditions. This voltage change may not be accurately detected by the voltmeter, which may affect the accuracy of temperature detection of the bridge circuit 410.

[0124] To address the aforementioned issues, in one possible implementation, as shown in Figure 6, the detection unit 420 may include a first amplifier circuit 421 and a first control unit 4221. The first input terminal of the first amplifier circuit 421 is the first terminal a1 of the detection unit 420 (or it may be connected to the first terminal a1 via a line). The second input terminal of the first amplifier circuit 421 is the second terminal a2 of the detection unit 420 (or it may be connected to the second terminal a2 via a line). The output terminal of the first amplifier circuit 421 is connected to the first control unit 4221. The first amplifier circuit 421 can obtain the first voltage V1 across the first resistor R1 through the first and second input terminals, amplify the first voltage V1, and then output it to the first control unit 4221. The first control unit 4221 can calculate the first voltage V1 across the first resistor R1 based on the amplified first voltage V1 and the amplification factor of the first amplifier circuit 421, and then determine the temperature of the bridge circuit 410 based on the first voltage V1.

[0125] By adopting the above implementation method, even if the resistance value of the first resistor R1 is small, resulting in a small first voltage V1, the first amplifier circuit 421 can amplify the originally very small first voltage V1 into a larger voltage that can be accurately detected. After the first control unit 4221 calculates the original first voltage V1 in reverse, the temperature of the bridge circuit 410 can be determined based on the relatively accurate first voltage V1, thereby effectively improving the accuracy of temperature detection.

[0126] Optionally, the first amplifier circuit 421 can be any circuit capable of amplification, such as an operational amplifier, differential amplifier, or instrumentation amplifier circuit. Taking a differential amplifier as an example, please refer to Figure 7, which shows a specific structural schematic of the first amplifier circuit. In this example, the first amplifier circuit 421 may include a comparator 4211 and a resistor R. 61 Resistance R 62 Resistance R 63 and resistance R 64 The power supply terminal of comparator 4211 (port "5" in the diagram) is connected to the supply voltage VDD on one branch, and grounded after being connected in series with capacitor C1 on the other branch. The ground terminal of comparator 4211 (port "2" in the diagram) is grounded. The first input terminal of comparator 4211 (port "3" in the diagram) is connected in series with resistor R on one branch. 61 After grounding, a resistor R is connected in series on another branch. 64 Then it is connected to the first terminal b1 of the first resistor R1. The second input terminal of comparator 4211 (port "4" in the diagram) is connected in series with resistor R in one branch. 63 Then connect it to the second terminal b2 of the first resistor R1, and connect it in series with resistor R in another branch. 62Then it is connected to the output terminal of comparator 4211 (port "1" in the figure). The output terminal "1" of comparator 4211 is connected in series with resistor R7 and then connected to the first control unit 4221. The series node between resistor R7 and the first control unit 4221 is connected in series with capacitor C2 and then grounded.

[0127] Furthermore, optionally, to reduce the complexity of the first amplifier circuit 421, resistor R can be configured as follows: 61 The resistance value and resistance R 62 The resistance values ​​are the same, resistor R 63 The resistance value and resistance R 64 The resistance values ​​are the same. In this case, the amplification factor of the first amplifier circuit 421 is: In other words, after the first voltage V1 across the first resistor R1 is amplified, the voltage output by the "1" terminal of comparator 4211 satisfies the following formula (1.2):

[0128] Furthermore, as shown in Figure 7, the output "1" of comparator 4211 will convert the amplified voltage V 4211 The output is sent to the first control unit 4221, which determines the voltage V based on the known amplification factor and the voltage V received from the output terminal "1" of the comparator 4211. 4211 The unamplified voltage, i.e., the first voltage V1, can be calculated. Thus, the first control unit 4221 can calculate the temperature of the bridge circuit 410 based on the first voltage V1, referring to Examples 1 to 3 above, as well as other examples not shown, which will not be repeated here.

[0129] It should be noted that in the first amplifier circuit 421 shown in Figure 7, capacitor C1, resistor R7, and capacitor C2 are provided for filtering. For example, capacitor C1 can be used to filter the supply voltage VDD, so that the filtered and more stable supply voltage VDD is input to the power supply terminal "5" of comparator 4211. As another example, resistor R7 and capacitor C2 form an RC filter circuit, which can be used to amplify the voltage V output from the output terminal "1" of comparator 4211. 4211 Filtering is performed to achieve a more stable voltage V after filtering. 4211 The input is sent to the first control unit 4221. However, it should be understood that in the actual first amplifier circuit 421, filtering may not be performed, that is, capacitor C1, resistor R7 and capacitor C2 may not be present. In other words, capacitor C1, resistor R7 and capacitor C2 are optional.

[0130] Understandably, the type of the first amplifier circuit 421 can be set according to requirements. For example, when the detection circuit is set in an automotive radar, the first amplifier circuit 421 can be a differential amplifier. Differential amplifiers are relatively inexpensive while also having high accuracy, which can save costs while ensuring the accuracy of temperature detection.

[0131] The foregoing content mainly introduced how the detection unit 420 realizes temperature detection. The following section will introduce other functions of the detection unit 420.

[0132] Common mode failure detection

[0133] In one possible implementation, the detection unit 420 can also detect common-mode failure. More specifically, the detection unit 420 can also detect whether a common-mode failure has occurred in the bridge circuit 410 based on the first voltage V1 across the first resistor R1. As discussed in the background analysis above, common-mode failure of the bridge circuit 410 usually leads to abnormal current in the bridge circuit 410, such as excessive short-circuit current, insufficient open-circuit current, or current that is too large or too small after impedance drift. Therefore, to detect common-mode failure of the bridge circuit 410, the detection unit 420 can also be pre-configured with one or more preset current conditions. After obtaining the first voltage V1 across the first resistor R1, the detection unit 420 can first calculate the current flowing through the first resistor R1 based on the first voltage V1 and the resistance value of the first resistor R1. This current is the current flowing through the bridge circuit 410. When the current meets any preset current condition, it can be determined that the bridge circuit 410 has a common-mode failure. In this case, the detection unit 420 can issue a fault alarm, for example, by displaying the alarm on a page or by giving a voice broadcast to the user who is currently using the detection circuit.

[0134] Specifically, one or more preset current conditions may include one or more of the following conditions:

[0135] Condition 1: The current flowing through bridge circuit 410 exceeds the short-circuit current threshold for a set period of time. Here, the short-circuit current threshold is a current threshold used to indicate a short-circuit fault between the first terminal A and the second terminal B of bridge circuit 410. This current threshold can be set to a relatively large value, such as 5A. When the current flowing through bridge circuit 410 is consistently greater than 5A for the set period of time, the current flowing through bridge circuit 410 satisfies condition 1, and bridge circuit 410 is highly likely to experience a short-circuit fault.

[0136] Condition two: The current flowing through bridge circuit 410 is less than the open-circuit current threshold within a set time period. Here, the open-circuit current threshold is used to indicate whether an open-circuit fault occurs between the first terminal A of bridge circuit 410 and the power supply terminal (i.e., the terminal to which the power supply voltage VCC is input), or between the second terminal B of bridge circuit 410 and the ground terminal. This current threshold can be set to a relatively small value, such as close to 0, for example, 0.1mA. When the current flowing through bridge circuit 410 is consistently less than 0.1mA within the set time period, the current flowing through bridge circuit 410 satisfies condition two, and bridge circuit 410 is highly likely to experience an open-circuit fault.

[0137] Condition 3: The absolute value of the change in current of bridge circuit 410 relative to the set current is greater than the impedance drift current threshold within the set time period. Here, the set current refers to the current when bridge circuit 410 has not experienced impedance drift, that is, the current when only the four resistors R2 to R5 of bridge circuit 410 and the first resistor R1 exist in the detection circuit, and no other resistors are present. The impedance drift current threshold can specifically include a first current threshold when the total resistance of the detection circuit decreases after impedance drift (e.g., the bridge resistance of bridge circuit 410 decreases or the resistance of the first resistor R1 decreases) and a second current threshold when the total resistance of the detection circuit increases after impedance drift (e.g., other impedances besides R1 to R5 appear). The first current threshold and the second current threshold can be the same or different. For example, in one example, assuming the set current is 100mA, the first current threshold is 10mA, and the second current threshold is 20mA, then if the current flowing through bridge circuit 410 is consistently greater than 110mA or consistently less than 80mA within a set time period, the current flowing through bridge circuit 410 satisfies condition three, and bridge circuit 410 is highly likely to experience impedance drift. In another example, assuming the set current is 100mA, and both the first and second current thresholds are 10mA, then if the current flowing through bridge circuit 410 is consistently greater than 110mA or consistently less than 100mA within a set time period, the current flowing through bridge circuit 410 satisfies condition three, and bridge circuit 410 is highly likely to experience impedance drift.

[0138] Optionally, in condition three above, the set current can also be related to the temperature of the bridge circuit 410. In other words, different temperatures can correspond to different set currents. This is mainly due to the temperature drift characteristics of the bridge circuit 410. Under the temperature drift characteristics, the bridge resistance of the bridge circuit 410 is positively correlated with the temperature; therefore, the set current and temperature can be negatively correlated. For example, the set current corresponding to 25°C is 100mA, the set current corresponding to 30°C is 99mA, the set current corresponding to 50°C is 95mA, and so on. Thus, before determining whether the current flowing through the bridge circuit 410 satisfies condition three, the detection unit 420 needs to first determine the temperature of the bridge circuit 410 according to the aforementioned temperature measurement scheme, and then find the set current corresponding to that temperature. Based on this set current, it then determines whether the absolute value of the difference between the current flowing through the bridge circuit 410 and the set current exceeds the first current threshold or the second current threshold. For example, assuming that both the first and second current thresholds are 10mA, and the detection unit 420 measures the current temperature of the bridge circuit 410 to be 30°C, then if the current flowing through the bridge circuit 410 is always greater than 109mA within a set time period, the detection unit 420 can determine that the bridge circuit 410 has a fault where the total resistance of the detection circuit decreases after impedance drift. If the current flowing through the bridge circuit 410 is always less than 89mA within a set time period, then the detection unit 420 can determine that the bridge circuit 410 has a fault where the total resistance of the detection circuit increases after impedance drift.

[0139] By employing the above implementation method, a first resistor is connected in series at one end of the bridge circuit. Utilizing the principle that series components have the same current, the current across the first resistor can be used to estimate the bridge circuit current, thus allowing for the prediction of whether an abnormal current fault has occurred in the bridge circuit, i.e., whether a common-mode failure has occurred. When this implementation method is applied to a detection device, common-mode failures of the Wheatstone bridge can be detected and reported promptly, thereby maintaining the safety level of the detection device and improving its reliability.

[0140] It should be noted that the above implementation is only an example of the detection process of common-mode failure executed by the detection unit 420. In some scenarios, when the resistance value of the first resistor R1 is relatively small, the detection unit 420 may also include a first amplifier circuit 421 and a first control unit 4221 as shown in Figure 6. The first amplifier circuit 421 is used to amplify the first voltage V1 across the first resistor R1 and send it to the first control unit 4221. The first control unit 4221 is used to determine the first voltage V1 based on the amplified voltage and the amplification factor of the first amplifier circuit 421, and then, based on the first voltage V1, detect whether a common-mode failure has occurred in the bridge circuit 410 according to the detection process shown in the above implementation. Optionally, the first control unit 4221 may include a current detection circuit, and the common-mode failure detection process may be implemented in the current detection circuit. This current detection circuit may be, for example, a dedicated current detection chip, a transistor circuit, or other devices or combinations of devices capable of current detection. This application does not specifically limit this.

[0141] Angle detection

[0142] In one possible implementation, the detection unit 420 may also have an angle detection function. This angle detection function may detect, for example, the torsion angle of the shaft. That is, the bridge circuit 410 may be located on the shaft. For example, referring to Figure 8, assuming that end L2 of the shaft is a fixed end and end L1 is a free end, the bridge circuit 410 may be located at the root of end L2. Thus, combining Figures 8 and 5a, when end L1 of the shaft rotates, end L1 twists relative to end L2, causing pressure on the bridge circuit 410 located at the root of end L2. This pressure causes a change in the resistance of at least one varistor in the bridge circuit 410, which in turn causes a change in the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410. In other words, there is a one-to-one correspondence between the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 and the torsion angle of the shaft. Based on this, the detection unit 420 can determine the torsion angle of the shaft by detecting the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410.

[0143] For example, please refer to Figure 9, which shows a specific structural schematic diagram of a detection circuit provided in this application. In this example, the detection unit 420 may further include a third terminal a3 and a fourth terminal a4. The third terminal a3 is connected to the third terminal C of the bridge circuit 410 (i.e., the series node between the second resistor R2 and the fifth resistor R5), and the fourth terminal a4 is connected to the fourth terminal D of the bridge circuit 410 (i.e., the series node between the third resistor R3 and the fourth resistor R4). When implementing the angle detection scheme, the detection unit 420 can obtain the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 through the third terminal a3 and the fourth terminal a4, and can determine the torsion angle of the shaft according to the second voltage V2 and the preset correspondence between voltage and rotation angle.

[0144] The preset voltage-to-angle correspondence can be pre-calibrated. For example, referring to Figures 8 and 9, the bridge circuit 410 can be placed at the root of the L2 end of the shaft in advance, and the shaft can be rotated at different torsion angles by rotating the L1 end. Then, at each torsion angle, the voltage between the third terminal C and the fourth terminal D of the bridge circuit 410 is measured, and a preset voltage-to-angle correspondence is established based on the voltage measured at each torsion angle. This correspondence indicates the voltage change between the third terminal C and the fourth terminal D of the bridge circuit 410 when the shaft is at different torsion angles. Therefore, the detection unit 420 can obtain the current torsion angle of the shaft by querying the preset voltage-to-angle correspondence based on the current second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 during use.

[0145] Furthermore, since the preset voltage-angle correspondence is calibrated under a fixed temperature environment, while the bridge circuit 410 may be in different temperature environments during actual use, there will be a difference between the current second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 and the standard voltage corresponding to the temperature environment used for calibration. If the current second voltage V2 is directly used to look up the preset voltage-angle correspondence, the angle detection result may have a certain error. Based on this, to improve the accuracy of angle detection, in one example, the detection unit 420 can first determine the temperature of the bridge circuit 410 based on the first voltage V1 across the first resistor R1, then use the temperature of the bridge circuit 410 to perform temperature compensation on the second voltage V2 to obtain the third voltage, and then look up the preset voltage-angle correspondence based on the third voltage to obtain the current torsion angle of the shaft.

[0146] For example, the current torsion angle of the shaft can be determined through the following steps 2.1 to 2.4:

[0147] Step 2.1, the detection unit 420 determines the temperature of the output bridge circuit 410 according to the first voltage V1 across the first resistor R1 and the aforementioned temperature detection scheme.

[0148] Step 2.2: The detection unit 420 determines the target voltage compensation value based on the temperature of the bridge circuit 410 and the preset correspondence between temperature and voltage compensation values. The preset correspondence between temperature and voltage compensation values ​​can be pre-calibrated. For example, assuming the preset voltage-to-angle correspondence is calibrated at a temperature of 25°C, the bridge circuit 410 can be placed sequentially in various temperature environments up to 25°C, and the same supply voltage can be applied to the bridge circuit 410. The voltage between the third terminal C and the fourth terminal D of the bridge circuit 410 is measured at each temperature environment, and the voltage difference between the voltage measured at 25°C and the voltage measured at each other temperature environment is calculated as the voltage compensation value for each temperature environment relative to the calibration temperature environment. Then, the preset correspondence between temperature and voltage compensation values ​​is established based on the voltage compensation values ​​for each temperature environment relative to the calibration temperature environment. This correspondence indicates the error of the voltage between the third terminal C and the fourth terminal D of the bridge circuit 410 at any given temperature environment relative to the standard voltage at the calibration temperature environment. Based on this, the detection unit 420 can obtain the target voltage compensation value of the current second voltage V2 compared with the standard voltage corresponding to the calibrated temperature environment by querying the preset correspondence between temperature and voltage compensation values, according to the current second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 under the current temperature environment.

[0149] Step 2.3: The detection unit 420 acquires the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410, and compensates the second voltage V2 using the target voltage compensation value to obtain the third voltage. For example, if the voltage compensation value corresponding to any temperature environment is the difference between the voltage measured at the calibrated temperature environment and the voltage measured at that temperature environment, the detection unit 420 can use the sum of the second voltage V2 and the target voltage compensation value as the third voltage. Conversely, if the voltage compensation value corresponding to any temperature environment is the difference between the voltage measured at that temperature environment and the voltage measured at the calibrated temperature environment, the detection unit 420 can use the difference between the second voltage V2 and the target voltage compensation value as the third voltage.

[0150] Step 2.4, the detection unit 420 determines the torsion angle of the shaft based on the third voltage and the preset voltage-rotation angle correspondence.

[0151] Here, since the third voltage is obtained after temperature compensation of the second voltage, the temperature environment used for the correspondence between the third voltage and the calibration is consistent. By using the third voltage to query the preset correspondence between voltage and angle, a relatively accurate angle measurement result can be obtained.

[0152] Understandably, when the shaft is not rotating, the bridge circuit 410 is in a balanced state, and the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 is 0. When the shaft rotates, although the resistance values ​​of the four arms of the bridge circuit 410 change, the difference is usually small. That is, although the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 is not 0, it is usually small, and this small voltage value cannot be detected accurately. Based on this, in one example, referring to Figure 10, the detection unit 420 may also include a second amplifier circuit 423 and a second control unit 4222. The first input terminal of the second amplifier circuit 423 is the third terminal a3 of the detection unit 420 (or it may not be the third terminal a3, but connected to the third terminal a3 via a line), the second input terminal of the second amplifier circuit 423 is the fourth terminal a4 of the detection unit 420 (or it may not be the fourth terminal a4, but connected to the fourth terminal a4 via a line), and the output terminal of the second amplifier circuit 423 is connected to the second control unit 4222. The second amplifier circuit 423 can obtain the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 through the first and second input terminals, amplify the second voltage V2, and then output it to the second control unit 4222 through the output terminal. The second control unit 4222 can calculate the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410 based on the amplified second voltage V2 and the amplification factor of the second amplifier circuit 423, and then determine the torsional angle of the shaft where the bridge circuit 410 is located based on the second voltage V2.

[0153] Optionally, the second amplifier circuit 423 can be any circuit capable of amplification, such as an operational amplifier, differential amplifier, or instrumentation amplifier circuit. The type of the second amplifier circuit 423 can be set according to requirements. For example, when the detection circuit is installed in an automotive radar, the second amplifier circuit 423 can be an instrumentation amplifier. Instrumentation amplifiers have high detection accuracy, which can meet the requirements for angle detection accuracy and improve the accuracy of shaft rotation control based on angle detection results.

[0154] Optionally, the amplification factor of the second amplifier circuit 423 can be determined by its circuit structure, and this amplification factor can also be pre-configured in the second control unit 4222. Therefore, when the second amplifier circuit 423 outputs the amplified second voltage V2 to the second control unit 4222, the second control unit 4222 can calculate the unamplified second voltage V2 based on the known amplification factor and the amplified second voltage V2 received from the output terminal of the second amplifier circuit 423. Thus, based on this second voltage V2, the second control unit 4222 can calculate the torsional angle of the shaft where the bridge circuit 410 is located, referring to the angle detection scheme described above; further details will not be repeated here.

[0155] Referring to Figures 6 and 10 above, it can be understood that the second control unit 4222 and the first control unit 4221 can be the same control unit or different control units. For example, referring to Figure 11a, when they are different control units, the first control unit 4221 can execute the aforementioned temperature detection scheme based on the first voltage V1 across the first resistor R1 to determine the temperature of the output bridge circuit 410, and can send this temperature to the second control unit 4222; the second control unit 4222 can execute the aforementioned angle detection scheme based on the second voltage V2 between the third terminal C and the fourth terminal D of the bridge circuit 410, combined with the temperature sent by the first control unit 4221, to determine the torsion angle of the shaft where the output bridge circuit 410 is located. Optionally, the first control unit 4221 can also execute the aforementioned scheme for detecting common-mode failure. For example, please refer to Figure 11b. When both are the same control unit 422, the control unit 422 can have two input terminals. One input terminal is connected to the output terminal of the first amplifier circuit 421, and the other input terminal is connected to the output terminal of the second amplifier circuit 423. The control unit 422 can not only execute the aforementioned temperature detection scheme to determine the temperature of the output bridge circuit 410 based on the amplified first voltage V1 output by the first amplifier circuit 421, but also execute the aforementioned angle detection scheme to determine the torsion angle of the shaft where the output bridge circuit 410 is located based on the amplified second voltage V2 output by the second amplifier circuit 423. Of course, it can also execute the aforementioned scheme for detecting common mode failure.

[0156] The above detection circuit can achieve one or more of the following: temperature detection, common-mode failure detection, and angle detection. When performing temperature detection, by connecting a first resistor in series at one end of the bridge circuit, the correlation between the temperature drift characteristic of the bridge circuit's resistance and the voltage change across the first resistor can be utilized to detect the temperature of the bridge circuit. The detected temperature accurately reflects the real-time temperature of the bridge circuit, resulting in high accuracy. When performing common-mode failure detection, by connecting a first resistor in series at one end of the bridge circuit, the characteristic that series devices have the same current flow can be utilized to detect the current flowing through the bridge circuit in real time. This allows for fault reporting when the measured current exceeds the set limit of the rated current at a specific temperature, enabling monitoring of common-mode failure phenomena such as short circuits, open circuits, or impedance drift in the bridge circuit, ensuring that the device meets functional safety requirements. When performing angle detection, the angle originally being detected can be temperature-compensated by combining the highly accurate temperature measurement to obtain a more accurate shaft rotation angle. Based on this more accurate shaft angle, closed-loop control of the shaft rotation can be completed, improving control accuracy.

[0157] The above detection circuit can be applied to any device, apparatus, or equipment with a bridge circuit. For example, it can include, but is not limited to: detection devices, projectors, head-up display (HUD) devices, or other vehicle-mounted devices, non-vehicle-mounted devices, terminal devices, display devices, communication devices, etc.

[0158] The following section uses the example of a detection circuit used in a detection device to introduce a specific application scenario of the detection circuit.

[0159] Based on the above detection circuit, this application can also provide a detection device, which may include the detection circuit described in any of the foregoing embodiments, such as the detection circuit shown in Figures 4, 5a, 5b, 6, 9, 10, 11a, or 11b. The detection device may exemplarily be a lidar.

[0160] In one possible implementation, please refer to Figure 12, which shows a schematic diagram of a detection device provided in this application. The detection device 1200 may include a scanning component 1210, and all or part of the detection circuit (including at least the bridge circuit 410) is disposed in the scanning component 1210. Optionally, please refer to Figure 12, the detection device 1200 may also include a circuit board 1220 and an FPC 1230, and the electrical components on the scanning component 1210 and the electrical components in the circuit board 1220 are electrically connected through the FPC 1230. The circuit board 1220 may be any type of circuit board, such as a PCB, PCBA, ceramic circuit board, aluminum substrate, thick copper plate, impedance board, circuit board, etc., without specific limitations.

[0161] Understandably, when the detection device 1200 includes a scanning assembly 1210, a circuit board 1220, and an FPC 1230, the various components in the detection circuit can be integrated into the same component or distributed across at least two components. For example:

[0162] In example K1, all the components in the above detection circuit are integrated into the scanning assembly 1210. That is, the bridge circuit 410, the first resistor R1, the detection unit 420, and the connection lines between these components are all located in the scanning assembly 1210. In other words, the scanning assembly 1210 can independently perform the temperature detection, angle detection, and common-mode failure detection described above.

[0163] In example K2, the components in the above detection circuit are distributed in the scanning assembly 1210 and the circuit board 1220. For instance, the bridge circuit 410 in the above detection circuit is disposed in the scanning assembly 1210, the first resistor R1 and the detection unit 420 are disposed in the circuit board 1220, and the connection lines between the bridge circuit 410 and the first resistor R1, and between the bridge circuit 410 and the detection unit 420 are disposed in the FPC 1230. In other words, the circuit board 1220 can obtain voltage signals related to the bridge circuit 410 disposed on the scanning assembly 1210 and the first resistor R1 disposed on the circuit board 1220 through the FPC 1230, and can realize the temperature detection, angle detection and common-mode failure detection described above based on the obtained voltage signals;

[0164] In example K3, the components in the above detection circuit are distributed across the scanning assembly 1210, the circuit board 1220, and the FPC 1230. For instance, the bridge circuit 410 is located in the scanning assembly 1210, the first resistor R1 is located in the FPC 1230, the detection unit 420 is located in the circuit board 1220, and the connection lines between the bridge circuit 410 and the first resistor R1, and between the bridge circuit 410 and the detection unit 420, are located in the FPC 1230. In other words, the circuit board 1220 can obtain the voltage signals related to the bridge circuit 410 located on the scanning assembly 1210 and the voltage signals related to the first resistor R1 located on the FPC 1230 through the FPC 1230, and can realize the temperature detection, angle detection, and common-mode failure detection described above based on the obtained voltage signals.

[0165] Of course, other configurations are also possible. For example, in another example, the bridge circuit 410 could be located in the scanning component 1210, and the first resistor R1 and the detection unit 420 could be located in the FPC 1230. Or, in yet another example, the bridge circuit 410 and the first resistor R1 could be located in the scanning component 1210, and the detection unit 420 could be located in the circuit board 1220. Or, in yet another example, the bridge circuit 410 could be located in the scanning component 1210, the detection unit 420 could be located in the FPC 1230, and the first resistor R1 could be located in the circuit board 1220. And so on, which will not be listed here.

[0166] To facilitate understanding of the scheme, the following section uses the example K2 mentioned above as an example to introduce the specific layout of the detection circuit in the detection device 1200.

[0167] Optionally, the detection device 1200 can be a scanning lidar based on a MEMS galvanometer, meaning that the scanning component 1210 may include a MEMS galvanometer. This MEMS galvanometer can be a one-dimensional scanning MEMS galvanometer or a two-dimensional scanning MEMS galvanometer. A one-dimensional scanning MEMS galvanometer refers to a MEMS galvanometer with only one axis of rotation, while a two-dimensional scanning MEMS galvanometer refers to a MEMS galvanometer with two axes of rotation.

[0168] Taking a two-dimensional scanning MEMS galvanometer as an example, please refer to Figure 13a, which shows a schematic diagram of the structure of a MEMS galvanometer provided in this application. This MEMS galvanometer can be considered as being obtained by etching a corresponding shape onto a silicon wafer and then fabricating it using the corresponding process. The etched structure includes parts A1, A2, and A3. Conductive coils are printed on the surface of part A2, and the surface of part A3 is made into a reflective surface (or mirror) through electroplating gold or other processes. Parts A1 and A2 are connected by a first rotating shaft, and parts A2 and A3 are connected by a second rotating shaft. The first and second rotating shafts are perpendicular. If it is a one-dimensional scanning lidar, parts A1 and A2 shown in Figure 13a can be fixed together, or parts A2 and A3 can be fixed together; that is, only the second rotating shaft exists and the first rotating shaft does not exist, or only the first rotating shaft exists and the second rotating shaft does not exist.

[0169] Furthermore, please refer to Figure 13b, which illustrates a schematic diagram of the working principle of the MEMS mirror shown in Figure 13a, illustrating an example of driving the mirror rotation by applying an electromagnetic field. Combining Figures 13a and 13b, the MEMS mirror may also include magnetic elements (not shown in the figure). For example, an N-pole magnet can be placed in the upper right corner of Figure 13b, and an S-pole magnet can be placed in the lower left corner, thus generating a magnetic field pointing from the upper right to the lower left. At this time, if a current I is applied to the conductive coil in section A2, the MEMS mirror will experience a Lorentz force in the magnetic field. The direction of this Lorentz force is determined according to the left-hand rule. For example, when the direction of current I is counterclockwise as shown in Figure 13b, the direction of the Lorentz force is direction F as shown in Figure 13b, and this Lorentz force will drive the MEMS mirror to swing back and forth. Since the position of part A1 is fixed, part A2, under the influence of the Lorentz force, will cause part A3 to swing relative to part A1 in a direction from top to front and then down. Part A3, under the influence of the Lorentz force, will swing relative to part A2 in a direction from right to front and then left. In other words, the first axis of rotation rotates from top to front and then down, and the second axis of rotation rotates from right to front and then left.

[0170] Understandably, since the MEMS galvanometer is constantly oscillating, accurately controlling its oscillation at the desired angle requires measuring the actual oscillation angle to achieve closed-loop control. Furthermore, the information scanned by the lidar at different times corresponds to different oscillation angles; fusing information from different moments to obtain a single image also necessitates measuring the oscillation angle of the MEMS galvanometer. Measuring the oscillation angle of the MEMS galvanometer can be equivalent to measuring the rotation angles of the first and second axes. Following the setup of Example K2 described above, and referring to Figures 13c and 13d, a bridge circuit 410 can be mounted at the root of the first and second axes of the MEMS mirror, respectively. (For a one-dimensional scanning MEMS mirror, the bridge circuit 410 can be set only at the root of one axis; other settings are described below.) A first resistor R1 and a detection circuit 420 can be mounted on the processing chip of circuit board 1220, and corresponding connection lines can be set in FPC 1230. One end of the connection line is connected to the relevant port of the bridge circuit 410, and the other end is connected to the relevant port of the processing chip of circuit board 1220. In this way, the processing logic related to temperature detection, angle detection, and common-mode failure detection can be encapsulated within the processing chip of circuit board 1220 for centralized execution.

[0171] For example, please refer to Figure 13e, which shows a circuit diagram of the above-described configuration. It should be noted that FPC 1230 is not labeled in the figure; it can be assumed that the connection lines between the scanning component 1210 and the circuit board 1220 are all located in FPC 1230. One end of FPC 1230 is connected to the scanning component 1210 via gold fingers, and the other end is connected to the circuit board 1220 via gold fingers. Figure 13e shows an example where the detection unit 420 includes only one control unit 422. This control unit 422 may include two analog-to-digital converter (ADC) terminals, namely ADC1 and ADC2. ADC1 is connected to the output of the first amplifier circuit 421, and ADC2 is connected to the output of the second amplifier circuit 422. Therefore, the control unit 422 can receive the amplified first voltage V1 through ADC1 and the amplified second voltage V2 through ADC2. Both the first voltage V1 and the second voltage V2 are analog signals.

[0172] Understandably, to achieve temperature detection, angle detection, or common-mode failure detection, analog signals need to be converted into digital signals. Therefore, in one example, the control unit 422 can discretize the amplified first voltage V1 received at the ADC1 terminal according to a first sampling frequency, thereby converting the analog first voltage V1 into individual first voltage values, which can then be used for temperature detection or common-mode failure detection. Similarly, the control unit 422 can discretize the amplified second voltage V2 received at the ADC2 terminal according to a second sampling frequency, thereby converting the analog second voltage V2 into individual second voltage values, which can then be used for angle detection. The first and second sampling frequencies can be the same or different. For example, in one example, considering that the angle detection result needs temperature compensation based on the temperature detection result, the first and second sampling frequencies can be set to the same sampling frequency.

[0173] Furthermore, when the MEMS galvanometer is operating, the resistance of the four arms of the bridge circuit 410 located at the root of the shaft changes periodically, and the corresponding bridge resistance of the bridge circuit 410 also changes periodically. To avoid the influence of this periodic change on temperature detection or common-mode failure detection, the control unit 422 can also perform an average calculation on the sampled voltage signal. For example, assuming the MEMS galvanometer oscillates around the shaft at a first operating frequency, the control unit 422 can set the first sampling frequency to be greater than three times the first operating frequency. In this way, during one oscillation cycle of the MEMS galvanometer, the control unit 422 can sample voltage values ​​at at least three points. By averaging these voltage values ​​at least three points, an average voltage value within one oscillation cycle can be obtained. Based on this average voltage value, the accuracy of temperature detection or common-mode failure detection can be improved. For example, taking temperature detection as an example, the control unit 422 can acquire at least three first voltages according to the first sampling frequency within one swing cycle of the MEMS galvanometer, and can determine the temperature of the bridge circuit 410 based on the average voltage of the at least three first voltages. The temperature of the bridge circuit 410 can be used to characterize the average temperature of the bridge circuit 410 within one swing cycle of the MEMS galvanometer. This average temperature is more accurate than the temperature corresponding to a single sampling, and can minimize the influence of stress generated during the periodic rotation of the shaft on the bridge resistance of the bridge circuit.

[0174] Compared to the existing solution shown in Figure 1a, the above detection circuit setup only requires adding a first resistor R1 and corresponding detection logic to the circuit board (the radar board in Figure 1a) and adding corresponding connection lines to the FPC. It does not require mounting an NTC on the FPC connected to the MEMS galvanometer. Therefore, it can save material and manufacturing costs, does not increase the complexity of the FPC, and also has high reliability.

[0175] It should be noted that the detection device architecture shown in Figure 12 is only an example. In other examples, the detection device may include more, fewer, or different structures, and each structure may include more, fewer, or different components. The components shown or not shown may be combined or divided in any way, and this application does not make any specific limitation in this regard.

[0176] For example, in one embodiment, the detection device may include, in addition to the components described above, one or more other components, such as a transmitting component, a receiving component, or a viewing window. The transmitting component can emit a light beam, which is transmitted to the scanning component 1210, reflected by the scanning component 1210, and then transmitted through the viewing window to the detection space. The light beam reflected back from the target in the detection space is transmitted to the receiving component, where it is processed to obtain point cloud information.

[0177] In a further example, the detection device may also include a processing component that can obtain target association information based on point cloud information. For example, when the detection device is installed in a vehicle, the processing component can acquire the vehicle's position, speed, orientation, or association information (e.g., target distance, target speed, and / or target attitude) of targets within a certain range (e.g., other vehicles, pedestrians, or obstacles) in real time or periodically. Further, optionally, the processing component can also send this acquired information to a control device in the vehicle, enabling the control device to perform path planning, braking, or starting of the vehicle based on this information. For example, latitude and longitude can be used to determine the vehicle's position, or speed and orientation can be used to determine the vehicle's direction of travel and destination over a future period, or the distance to surrounding objects can be used to determine the number and density of obstacles around the vehicle. Further, optionally, it can also be combined with the functions of an advanced driving assistance system (ADAS) to achieve assisted driving or autonomous driving of the vehicle.

[0178] Based on the structure and functional principles of the detection device described above, this application can also provide a terminal device. This terminal device may include any of the detection devices described above, such as the detection device shown in Figure 12.

[0179] For example, the terminal device may be a vehicle (e.g., driverless car, smart car, electric car, or digital car), robot, surveying equipment, drone, smart home device (e.g., television, robot vacuum cleaner, smart lamp, audio system, smart lighting system, electrical control system, home background music, home theater system, intercom system, or video surveillance), smart manufacturing equipment (e.g., industrial equipment), smart transportation equipment (e.g., AGV, driverless vehicle, or truck), or smart terminal (mobile phone, computer, tablet, PDA, desktop computer, headphones, audio equipment, wearable device, in-vehicle device, virtual reality device, augmented reality device, etc.).

[0180] Understandably, the above detection circuit can be extended to any device or system with a bridge circuit. For example, it can be applied to other in-vehicle devices, such as camera devices, seat adjustment devices, or other types of sensors, or to other means of transportation besides vehicles, including but not limited to ships, airplanes, high-speed trains, trains, helicopters, lawnmowers, and mobile robots. Alternatively, it can be applied to other terminal devices, such as projectors, surveillance cameras, printers, smart home devices, smart industrial equipment, and so on.

[0181] Furthermore, as system architecture evolves and new scenarios emerge, the solutions provided in this application are also applicable to similar technical problems, and this application does not impose any specific limitations on them.

[0182] In the above embodiments, unless otherwise specified or there is a logical conflict, the terms and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0183] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, E and / or F can represent: E alone, E and F simultaneously, or F alone, where E and F can be singular or plural. In the textual description of this application, terms such as "resistance," "bridge resistance," "temperature," "voltage value," and "current value" do not refer to absolute values ​​and allow for a certain measurement deviation. The words "optionally" and "exemplary" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "optional" or "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Alternatively, it can be understood that the use of the words "exemplary" or "optional" is intended to present concepts in a specific manner and does not constitute a limitation on this application.

[0184] It is understood that the various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and inherent logic. Terms such as "first," "second," and similar expressions are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

Claims

1. A detection circuit, characterized in that, include: Bridge circuit, first resistor and detection unit; The bridge circuit is connected in series with the first resistor, and one end of the series link is used to receive the power supply voltage, while the other end is grounded. The detection unit includes a first end and a second end. The first end of the detection unit is connected to the first end of the first resistor, and the second end of the detection unit is connected to the second end of the first resistor. The detection unit is used to acquire a first voltage across the first resistor and determine the temperature of the bridge circuit based on the first voltage.

2. The detection circuit as described in claim 1, characterized in that, The first terminal of the bridge circuit is used to receive the supply voltage, and the second terminal of the bridge circuit is connected to the first terminal of the first resistor, the second terminal of the first resistor being grounded; or... The first end of the first resistor is used to receive the supply voltage, the second end of the first resistor is connected to the first end of the bridge circuit, and the second end of the bridge circuit is grounded.

3. The detection circuit as described in claim 1 or 2, characterized in that, The detection unit is specifically used for: The temperature of the bridge circuit is determined based on the first voltage and the preset voltage-temperature correspondence.

4. The detection circuit as described in claim 1 or 2, characterized in that, The detection unit is specifically used for: The current of the bridge circuit is determined based on the first voltage and the resistance value of the first resistor. The current bridge resistance of the bridge circuit is determined based on the current of the bridge circuit and the supply voltage. The temperature of the bridge circuit is determined based on the current bridge resistance and the preset relationship between bridge resistance and temperature.

5. The detection circuit as described in any one of claims 1 to 4, characterized in that, The first resistor is a shunt resistor.

6. The detection circuit as described in any one of claims 1 to 5, characterized in that, The detection unit includes a first amplifier circuit and a first control unit. The first input terminal of the first amplifier circuit is the first terminal of the detection unit, the second input terminal of the first amplifier circuit is the second terminal of the detection unit, and the output terminal of the first amplifier circuit is connected to the first control unit. The first amplifier circuit is used to amplify the first voltage; The first control unit is configured to determine the first voltage based on the amplified first voltage and the amplification factor of the first amplification circuit, and to determine the temperature of the bridge circuit based on the first voltage.

7. The detection circuit as described in claim 6, characterized in that, The first amplifier circuit includes a differential amplifier.

8. The detection circuit as described in any one of claims 1 to 7, characterized in that, The detection unit is also used for: The current of the bridge circuit is determined based on the first voltage and the resistance value of the first resistor. If the current in the bridge circuit does not meet the preset current condition, a fault alarm will be triggered.

9. The detection circuit as described in claim 8, characterized in that, The preset current conditions include at least one of the following: The current in the bridge circuit is less than or equal to the short-circuit current threshold within a set time period. The current in the bridge circuit is greater than or equal to the current threshold of the circuit breaker within a set time period. The absolute value of the change in current of the bridge circuit relative to the set current is less than or equal to the current threshold of impedance drift within a set time period.

10. The detection circuit as described in claim 9, characterized in that, The set current is related to the temperature of the bridge circuit.

11. The detection circuit as described in any one of claims 1-10, characterized in that, The bridge circuit includes a second resistor, a third resistor, a fourth resistor, and a fifth resistor, which are connected end to end in sequence. At least one of the second resistor, the third resistor, the fourth resistor, and the fifth resistor is a varistor. The series connection point between the second resistor and the third resistor is the first end of the bridge circuit, and the series connection point between the fourth resistor and the fifth resistor is the second end of the bridge circuit.

12. The detection circuit as described in claim 11, characterized in that, The bridge circuit is disposed on the rotating shaft, and the detection unit further includes a third terminal and a fourth terminal. The third terminal is connected to the series node between the second resistor and the fifth resistor, and the fourth terminal is connected to the series node between the third resistor and the fourth resistor. The detection unit is further configured to obtain a second voltage through the third terminal and the fourth terminal, and use the temperature of the bridge circuit to perform temperature compensation on the second voltage to obtain a third voltage, and determine the rotation angle of the shaft based on the third voltage.

13. The detection circuit as described in claim 12, characterized in that, The detection unit is specifically used for: The target voltage compensation value is determined based on the temperature of the bridge circuit and the preset correspondence between temperature and voltage compensation value; The third voltage is obtained by compensating the second voltage using the target voltage compensation value; The rotation angle of the shaft is determined based on the third voltage and the preset correspondence between voltage and rotation angle.

14. The detection circuit as described in claim 12 or 13, characterized in that, The detection unit includes a second amplifier circuit and a second control unit. The first input terminal of the second amplifier circuit is the third terminal of the detection unit, the second input terminal of the second amplifier circuit is the fourth terminal of the detection unit, and the output terminal of the second amplifier circuit is connected to the second control unit. The second amplifier circuit is used to amplify the second voltage; The second control unit is used to determine the second voltage based on the amplified second voltage and the amplification factor of the second amplification circuit, to perform temperature compensation on the second voltage using the temperature of the bridge circuit to obtain a third voltage, and to determine the rotation angle of the shaft based on the third voltage.

15. The detection circuit as described in claim 14, characterized in that, The second control unit and the first control unit may be the same control unit or different control units.

16. A detection device, characterized in that, Includes the detection circuit as described in any one of claims 1 to 15.

17. The detection device as described in claim 16, characterized in that, It also includes a scanning component and a circuit board, wherein the bridge circuit in the detection circuit is disposed in the scanning component, and the first resistor and the detection unit in the detection circuit are disposed in the circuit board.

18. The detection device as described in claim 17, characterized in that, It also includes a flexible printed circuit board (FPC), through which the electrical components on the scanning assembly and the electrical components on the circuit board are connected.

19. The detection device as described in claim 17 or 18, characterized in that, The scanning component includes a reflector and a rotating shaft. The reflector oscillates around the rotating shaft at a first operating frequency. The detection unit acquires the first voltage at a first sampling frequency, wherein the first sampling frequency is greater than three times the first operating frequency.

20. The detection device as described in claim 19, characterized in that, The detection unit is specifically used for: During one swing cycle of the reflector, a plurality of first voltages are acquired according to the first sampling frequency; The temperature of the bridge circuit is determined based on the average voltage of the plurality of first voltages.

21. A terminal device, characterized in that, Includes the detection device as described in any one of claims 16 to 20.

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