Safety circuit and driver test procedure for a LiDAR and its driver circuit

Abstract

The present invention relates to a LiDAR, a safety circuit for its driver circuit, and a method for driver detection, wherein the LiDAR comprises a light-generating unit and the driver circuit is suitable for providing a driver voltage to drive the light-generating unit to emit light, wherein one end of the light-generating unit receives this driver voltage, while the other end of the light-generating unit is coupled to a driver switch; wherein the safety circuit comprises: a voltage sensing unit for detecting the voltage value of the driver voltage;and a safety switching unit designed to control the driver circuit such that the supply of the driver voltage is stopped when the voltage value of the driver voltage falls below the threshold voltage, wherein the threshold voltage represents the voltage value of the driver voltage in the event of a failure of the driver switch. The technical approach of the present invention makes it possible to stop the light emission of the light-generating unit in a timely manner in the event of a failure of the driver circuit, thereby reducing the risk of continuous light emission by the LiDAR, which could endanger eye safety.

Description

[0001] This application claims priority to Chinese patent application No. 202210833754X filed with CNIPA on July 15, 2022, entitled Safety circuit and driving test method for a LiDAR and its driving circuit, the entire contents of which are incorporated into the present application by reference. TECHNICAL FIELD

[0002] The present invention relates to the field of LiDARs and, in particular, to a safety circuit and a driver test method for a LiDAR and its driver circuit. TECHNICAL BACKGROUND

[0003] The associated technology, which uses the control switches for the LiDAR's emitted light pulses, is already very mature. For example, driver switches such as gallium nitride (GaN) field-effect transistors have a failure rate of approximately 1 FIT (one failure per billion hours of operation), making them widely accepted due to their high reliability and performance.

[0004] As in Fig. As shown in Figure 1, in the field of LiDARs, the common connection of multiple light-emitting units is typically used to reduce the number of components required in the drive circuits of the laser emission unit and thus minimize the chip area. For example, in a "common cathode structure," these are controlled via switches T1-T4 and the driver switch to regulate the illumination duration and timing of the light-emitting units. Light-emitting units L1-L4 are grounded via driver switch G1, while light-emitting units L5-L8 are grounded via driver switch G2. By ensuring that the emission time (the so-called pulse width) of each light-emitting unit in the array is kept at approximately 10 ns, human eye safety can be effectively guaranteed.

[0005] However, due to the frequent use of driver switches in the LiDAR system, there is a risk that in the event of a driver switch failure, for example, in a breakthrough with a constant conduction state, continuous light emission from a light generating unit could occur, which would pose a potential hazard to eye safety. CONTENT OF THE INVENTION

[0006] The technical problem to be solved by the present invention is to stop the light emission of the light generating unit in time in case of a failure of the driver circuit in order to reduce the risk to eye safety caused by continuous light emission of a LiDAR.

[0007] To solve the above-mentioned technical problem, a first aspect of the present invention comprises a safety circuit for the driver circuit of a LiDAR. The LiDAR comprises a light generating unit, and the driver circuit is capable of providing a driving voltage that excites the light generating unit to illuminate. One terminal of the light generating unit receives the driving voltage, while the other terminal is coupled to a driver switch. The safety circuit comprises: a voltage detection unit used to detect the voltage value of the driving voltage; and a safety switching unit used to control the driver circuit so that the driving voltage is no longer provided when the voltage value of the driving voltage is below a threshold value. The threshold value corresponds to the voltage value of the driving voltage when the driver switch suffers a failure.

[0008] Optionally, during normal operation of the light generating unit, the drive voltage has a maximum voltage value and a minimum voltage value in a voltage repetition period, with the threshold value being smaller than the minimum voltage value.

[0009] Optionally, the difference between the maximum voltage value and the minimum voltage value corresponds to a first voltage change amount, and the threshold value is the difference between the minimum voltage value and a safety voltage change amount; the safety voltage change amount is the product of the first voltage change amount and a predetermined ratio.

[0010] Optionally, the threshold value is less than the minimum voltage value but greater than a safe allowable voltage value, where the safe allowable voltage value corresponds to the drive voltage reached when the emission duration of the light generating unit reaches the safety emission time limit.

[0011] Optionally, the threshold value corresponds to the average of the minimum voltage value and the safely permitted voltage value.

[0012] Optionally, the driver circuit comprises a charging device and an energy storage device, wherein the charging device is used to charge the energy storage device, and the energy storage device provides the drive voltage. The safety switching unit controls the charging device to stop charging the energy storage device and to discharge the energy storage device when the voltage value of the drive voltage drops below the threshold value.

[0013] Optionally, the voltage detection unit comprises: a comparison subunit used to output a first voltage based on the comparison result between the drive voltage and the threshold value, this first voltage indicating whether the drive voltage is abnormal.

[0014] Optionally, the comparison subunit comprises: A first comparator whose positive input terminal is connected to the threshold value, whose negative input terminal is connected to the drive voltage and whose output outputs the first voltage.

[0015] Optionally, the voltage sensing unit comprises: A limiting subunit whose input is coupled to the drive voltage and which serves to limit the drive voltage to a predetermined voltage range.

[0016] Optionally, the voltage sensing unit comprises: a first voltage divider subunit, whose input is coupled to the power supply and whose output is connected to the negative input terminal of the first comparator. This first voltage divider subunit outputs an initial drive voltage higher than the threshold.

[0017] Optionally, the other end of the N light-generating units is coupled to the same driver switch. The number of driver switches is M, where the number of light-generating units in the LiDAR is N × M, and N and M are positive integers greater than 1. The voltage detection unit is used to detect the voltage value of the drive voltage for the N light-generating units.

[0018] Optionally, each light-generating unit is connected to the power supply via a switching device, with the first terminal of the switching device being coupled to the power supply, while the second terminal is coupled to a terminal of the light-generating unit. Each input of the voltage sensing unit is coupled to the second terminal of the switching device.

[0019] Optionally, the safety switching unit comprises: A discharge unit which serves to discharge the energy storage device in the driver circuit when the voltage value of the driver voltage is below the threshold value.

[0020] Optionally, the control terminal of the discharge unit is coupled to the output of the voltage sensing unit, the first terminal of the discharge unit is coupled to the energy storage device, and the second terminal is grounded.

[0021] Optionally, the safety switching unit includes: A controller whose input is coupled to the output of the voltage detection unit and whose output is connected to the input terminal of the discharge unit.

[0022] Optionally, the control terminal of the discharge unit is coupled to the output of the controller, the first terminal of the discharge unit is connected to the energy storage device, and the second terminal is grounded.

[0023] Optionally, the controller controls that if the voltage value of the driver voltage falls below the threshold value, the energy storage device in the driver circuit is no longer charged.

[0024] Optionally, the discharge unit comprises: a first load; and a first switch which conducts when the voltage value of the drive voltage falls below the threshold value, so that the energy storage device is discharged via the first load.

[0025] Optionally, the safety switching unit comprises: a gate subunit which, when the voltage value of the drive voltage falls below the threshold value, outputs a first control signal, this first control signal serving to stop the charging of the energy storage device in the drive circuit; and which, when the voltage value of the drive voltage is above the threshold value, outputs a second control signal, this second control signal serving to enable the charging of the energy storage device in the drive circuit.

[0026] Optionally, the input of the gate subunit is coupled to the output of the voltage sensing unit.

[0027] Optionally, the safety switching unit comprises a controller whose input is coupled to the output of the voltage sensing unit, and the input of the gate subunit is coupled to the output of the controller.

[0028] Optionally, in case the voltage value of the drive voltage falls below the threshold, the controller outputs a third control signal to the input of the gate subunit; and in case the voltage value of the drive voltage rises above the threshold, the controller outputs a fourth control signal to the input of the gate subunit.

[0029] A second aspect of the invention relates to a driver testing method for a LiDAR. The LiDAR comprises a light-generating unit, and the driver circuit is capable of providing a driver voltage to illuminate the light-generating unit. One terminal of the light-generating unit receives the driver voltage, while the other terminal is coupled to a driver switch. The driver testing method comprises the steps of: detecting the voltage value of the driver voltage; and controlling that the driver voltage is no longer provided when the voltage value of the driver voltage falls below the threshold value, wherein the threshold value corresponds to the voltage value that occurs upon failure of the driver switch.

[0030] Optionally, the driver circuit comprises a charging device and an energy storage device, wherein the charging device is used to charge the energy storage device, and the energy storage device provides the driving voltage. Stopping the provision of the driving voltage includes: controlling the charging device to stop charging the energy storage device; and controlling the energy storage device to discharge.

[0031] A third aspect of the invention comprises a LiDAR comprising a light generating unit and the safety circuit described above.

[0032] Compared to the prior art, the technical solution concept of the present invention offers the following advantages:

[0033] The technical solution of the present invention provides a safety circuit comprising a voltage detection unit and a safety switching unit. The voltage detection unit serves to detect the voltage value of the driving voltage, while the safety switching unit controls the driving circuit so that the driving voltage is no longer supplied when the voltage value drops below the threshold. Since, when the driving switch fails, the driving voltage that excites the light-generating unit to illuminate gradually decreases, the present invention makes it possible to determine whether a driving switch has failed by monitoring the relationship between the driving voltage and the threshold.In case of a driver switch failure, the invention controls that the driver circuit no longer provides the drive voltage and thus stops the light emission of the light generating unit, thereby reducing the likelihood of eye safety incidents due to driver switch failure.

[0034] Furthermore, this safety switching unit in the present application is specifically designed for driver circuits in which the high-voltage buses supply power to various light-generating units via associated gate switches and driver switches, and the lighting duration and timing are controlled. The safety switching unit includes a discharge unit that discharges the energy storage device of the driver circuit if the drive voltage falls below the threshold. The embodiment of the present invention enables the discharge unit to discharge the energy storage device in the event of a driver switch failure, thereby quickly stopping the light emission of the light-generating unit and further improving the safety of the LiDAR's light emission. DESCRIPTION OF THE CHARACTERS Fig. 1 is a schematic structural diagram of a laser driver circuit according to the prior art; Fig. 2 shows a timing diagram of a driver circuit according to the prior art; Fig. 3 is a schematic structural diagram of a security circuit according to an embodiment of the present invention; Fig. 4 and Fig. 5 show schematic representations of the threshold voltage according to an embodiment of the present invention; Fig. 6 is a schematic diagram of the energy storage device in a driver circuit according to an embodiment of the present invention; Fig. 7 is a schematic structural diagram of a voltage detection unit according to an embodiment of the present invention; Fig. 8 is a schematic structural diagram of a discharge unit according to an embodiment of the present invention; Fig. 9 is a schematic structural diagram of the specific structure of a security circuit according to an embodiment of the present invention; Fig. 10 is a schematic structural diagram of the specific structure of a security circuit according to an embodiment of the present invention; Fig. 11 is a schematic structural diagram of another specific structure of a security circuit according to another embodiment of the present invention; Fig. 12 is a schematic structural diagram of another specific structure of a security circuit according to another embodiment of the present invention; Fig. 13 is a schematic structural diagram of a further modified specific structure of a safety circuit according to another embodiment of the present invention; Fig. 14 is a schematic structural diagram of a further modified specific structure of a safety circuit according to another embodiment of the present invention; Fig. 15 shows a voltage-time diagram according to an embodiment of the present invention; Fig. 16 shows a flowchart of a driver testing method for a LiDAR according to an embodiment of the present invention. EXECUTION METHOD

[0035] With reference to the Fig. 1 and Fig. 2, the high-voltage bus line HVBUS provides a stable voltage source. After switch T1 is closed by the field-programmable gate array (FPGA), the driver switches are closed sequentially, activating the light-generating units L1, L5, ... Ln (n = 9 ... 125) connected to switch T1 in sequence. The closing time of each driver switch is approximately 10 nanoseconds (ns), meaning the pulse width of the light from each light-generating unit is 10 ns. To realize simultaneous light pulse coding, the lasers L1, L5, ... Ln must pulse at least twice during the closing time t1 of switch T1, and the lasers L1, L5, ... Ln emit their light sequentially with a time delay according to the order of the light emission schedule. The time interval t2 between the pulses is a random coding time, and the time interval t3 between the emissions of the lasers L1, L5 ... Ln (ieThe light emission period of each laser is also defined. Consequently, the closing time t1 of switch T1 must be kept in the microsecond range.

[0036] As discussed in the prior art, driver switches are used extensively in LiDARs. Should a driver switch fail, e.g., by breaking down and becoming permanently conductive, this could cause a light-generating unit to continuously emit light, posing an eye safety risk.

[0037] For example, in Fig. 1 After switch T1 closes, driver switch G1 becomes permanently conductive due to breakdown, causing light-generating unit L1 to emit light. Normally, light-generating unit L1 would stop emitting after 10 ns. However, if driver switch G1 is defective and remains permanently conductive, light-generating unit L1 will continue to emit light until switch T1 is opened. However, the duration t1 during which switch T1 remains closed is approximately microseconds. If a light-generating unit continuously emits light for more than a few dozen nanoseconds, this could lead to an eye safety incident. If a person is nearby at this moment and looks directly into light-generating unit L1, this could cause permanent damage to the cornea of ​​the eye.

[0038] The technical solution of the present invention provides a safety circuit comprising a voltage detection unit and a safety switching unit. The voltage detection unit serves to detect the voltage value of the driving voltage, while the safety switching unit controls the driving circuit so that the driving voltage is no longer supplied when the voltage value drops below the threshold. Since, when the driving switch fails, the driving voltage that excites the light-generating unit to illuminate gradually decreases, the present invention makes it possible to determine whether a driving switch has failed by monitoring the relationship between the driving voltage and the threshold.In case of a driver switch failure, the invention controls that the driver circuit no longer provides the drive voltage and thus stops the light emission of the light generating unit, thereby reducing the probability of eye safety incidents due to driver switch failure.

[0039] The safety switch unit further comprises a discharge unit used to discharge the energy storage device in the driver circuit when the voltage value of the driver voltage drops below the threshold. In one embodiment of the present invention, in the event of a driver switch failure, the discharge unit discharges the energy storage device of the driver circuit, thereby dissipating the remaining charge in the energy storage device in a timely manner. This enables rapid control of the light emission of the light generation unit to further ensure the safety of the LiDAR's light emission.

[0040] In order to illustrate the above-mentioned objects, features and advantages of the present invention more clearly and understandably, the concrete embodiments of the invention are described in detail below with reference to the accompanying figures.

[0041] Fig. Figure 3 shows a schematic structural diagram of a safety circuit according to an embodiment of the present invention. The safety circuit 32 according to an embodiment of the present invention is used in the LiDAR to ensure safe light emission of the LiDAR.

[0042] The LiDAR comprises a driver circuit 30 and a light-generating unit 31. The light-generating unit 31 can emit light, while the driver circuit 30 can provide a driving voltage that drives the light-generating unit 31 to emit light. The light-generating unit 31 can specifically be a laser, in particular a vertical-cavity surface-emitting laser (VCSEL). However, it can also be any other light-generating unit that can be implemented in practice. In practical application, the number of light-generating units 31 can be multiple. The present invention is not limited in this respect.

[0043] The driver circuit 30 includes driver switches, such as GaN. The light-generating unit 31 is grounded via the switch. However, a failure of the switch causes the light-generating unit 31 to continuously emit light.

[0044] In this embodiment, the safety circuit 32 may include a voltage detection unit 321 and a safety switching unit 322. The voltage detection unit 321 is used to detect the voltage value of the driving voltage. The safety switching unit 322 serves to control the driving circuit 30 and stop the supply of the driving voltage when the voltage value of the driving voltage drops below the threshold value. Here, the threshold value represents the voltage value of the driving voltage when the driving switch fails. In other words, a voltage value of the driving voltage below the threshold value means that the driving switch has failed. The threshold value may be set in advance according to the voltage value of the driving voltage in the event of a driver switch failure. In this regard, there are no restrictions imposed by the present application.

[0045] Since the drive voltage driving the light-generating unit gradually decreases in the event of a drive switch failure, the embodiment of the present invention makes it possible to judge whether the drive switch has failed based on the relationship between the drive voltage value and the threshold value. In the event of a drive switch failure, the invention controls the drive circuit to stop supplying the drive voltage, thus stopping the light emission of the light-generating unit, thereby reducing the likelihood of eye safety incidents caused by the drive switch failure.

[0046] The concrete configuration of the threshold value of the driving voltage can be done as follows.

[0047] Method 1: During normal light emission of the light generating unit 31, the driving voltage has a maximum voltage value and a minimum voltage value within one voltage repetition cycle. The threshold value is smaller than the minimum voltage value.

[0048] See Fig. 4: If the driver switch has not failed and the light-generating unit 31 is emitting light normally, the change in the driving voltage exhibits the behavior of curve 1. The voltage repetition cycle includes the time periods T1 and T2. T1 denotes the light-emitting time of the light-generating unit 31; during this period, the light-generating unit 31 emits light. The driving voltage drops or changes by the first voltage change amount ΔV1. T2 denotes the voltage recovery time after the voltage drop, which can be realized by a regulated voltage source (voltage-stabilized source) or a low-dropout regulator (LDO). Within the voltage repetition cycle, the maximum voltage value is Vmax and the minimum voltage value is Vmin. Each time the light-generating unit emits a laser pulse, the driving voltage varies between the maximum voltage value Vmax and the minimum voltage value Vmin.In the event of a permanent conduction of the driver switch due to a failure, the light generating unit 31 continuously emits light. The behavior of the driver voltage in such a case is shown in curve 2. The driver voltage decreases continuously.

[0049] In one embodiment of the present invention, the threshold is set to be lower than the minimum voltage value Vmin. Once the voltage detection unit 321 detects that the drive voltage falls below the threshold, it is recognized that the drive voltage deviates from curve 1 and continues to fall, indicating a failure of the drive switch.

[0050] It should be noted that T1 in Fig. 4 represents the time for the emission of a single laser pulse by the light generating unit 31. When the light generating unit 31 emits coded multiple pulses, a multiple voltage drop occurs during the duration of T1.

[0051] Method 2: The difference between the maximum voltage value Vmax and the minimum voltage value Vmin corresponds to the first voltage change amount ΔV1. The threshold value is the difference between the minimum voltage value Vmin and a safety voltage change amount ΔV2, where the safety voltage change amount ΔV2 is the product of the first voltage change amount ΔV1 and a predetermined ratio.

[0052] See also Fig. 4. In a concrete example, the specified ratio can be 20%, i.e. the safety voltage change amount ΔV2 is 20% of the first voltage change amount ΔV1.

[0053] By establishing a safety margin between the threshold value and the minimum voltage value Vmin, i.e., the safety voltage change amount ΔV2, embodiments of the present invention ensure that no incorrect measurements of the drive voltage occur due to spikes or other disturbances. This prevents false triggering of the eye safety mechanism and ensures normal operation of the LiDAR.

[0054] Method 3: The threshold value is less than the minimum voltage value Vmin but greater than the safe allowable voltage value. The safe allowable voltage value is the voltage value of the drive voltage when the emission duration of the light-generating unit 31 reaches the safe emission time limit.

[0055] With reference to Fig. 5, the safety emission time limit t0 can be set in advance as the eye-safe emission time of the LiDAR, meaning that the continuous light emission of the LiDAR within this time limit is safe for the human eye. Specifically, the safety emission time limit t0 can be in the range of several tens of nanoseconds. The safe allowable voltage value V0 describes the voltage value of Curve 2 at time t0 of the safety emission time limit. The threshold value can be selected within the voltage range between the minimum voltage value Vmin and the safe allowable voltage value V0, meaning that the threshold value can be any voltage value within this range.

[0056] Furthermore, the threshold value can represent the average of the minimum voltage value Vmin and the safely permissible voltage value V0. In this embodiment, the threshold value is defined as 1 / 2(Vmin + V0).

[0057] In a non-limiting embodiment of the present invention, the safety switching unit 322 controls that the charging device stops charging the energy storage device when the voltage value of the drive voltage drops below the threshold value and that the energy storage device is discharged.

[0058] In this embodiment, the driver circuit comprises a charging device and an energy storage device. The charging device serves to charge the energy storage device, while the energy storage device provides the drive voltage. See Fig. 6. The energy storage device includes a capacitor Cn, while the charging device includes a power source VH and VL, and a switch Tn. While the capacitor Cn is being charged by the charging device, it is connected to the power source VH via the switch Tn. Once charging is stopped, the capacitor Cn is connected to the power source VL via the switch Tn, that is, the capacitor Cn is grounded via the switch Tn.

[0059] With reference to Fig. 7, in one embodiment of the present invention, each drive voltage HV1-HV4 is coupled to a separate energy storage device, ie, each drive voltage is connected to a capacitor Cn.

[0060] The embodiment of the present invention enables the discharge unit to discharge the energy storage device in the event of a failure of the driver switch, thereby quickly stopping the light emission of the light generating unit and further improving the safety of the light emission of the LiDAR.

[0061] The concrete structure of the safety circuit is explained in detail below. In one embodiment of the present invention, the voltage referred to as the driving voltage may be the voltage applied to the anode of the light generating unit, ie, the voltage Fig. 6 shown voltage HV.

[0062] In a non-limiting embodiment of the present invention, see Fig. 7 and Fig. 9, the voltage detection unit 321 includes a comparison subunit 3214, which is used to output a first voltage based on the comparison result between the drive voltage and the threshold voltage. This first voltage indicates whether the drive voltage is abnormal.

[0063] The comparison subunit 3214 may be the first comparator U5. The first comparator U5 has a first input to which the voltage UA is connected, and a second input to which the voltage UB is connected. The voltage UA is the drive voltage, while the voltage UB is the threshold voltage.

[0064] In this embodiment, the first comparator U5 outputs a low level when the voltage UA is higher than the voltage UB; when the voltage UA is lower than the voltage UB, the first comparator U5 outputs a high level.

[0065] Those skilled in the art should understand that the first comparator U5 can also be configured to output a low level at a voltage UA lower than the voltage UB and a high level at a voltage UA higher than the voltage UB. This application is not limited in this respect.

[0066] In a specific implementation, the voltage detection unit 321 comprises a first divider subunit 3211, which serves to generate an initial drive voltage. The first voltage divider subunit 3211 comprises resistors R4, R5, and R6. One end of the resistor R4 is coupled to the first input of the first comparator U5, while the other end of the resistor R4 is coupled to one end of the resistor R5. The other end of the resistor R5 is connected to the power source VCC. One of the ends of the resistor R5 is also connected to one end of the resistor R6, while the other end of the resistor R6 is grounded. By dividing the power source VCC by means of the resistors R4, R5, and R6, an initial value for the voltage UA is generated (i.e., the initial drive voltage). The initial value of UA is a constant voltage value to ensure that the voltage value of UA is higher than the voltage value of UB.

[0067] In a specific implementation, the threshold voltage UB can be generated by a threshold voltage generation subunit 3212. The threshold voltage generation subunit 3212 includes resistors R2 and R3. The threshold voltage is generated by dividing the current source VCC by resistors R2 and R3. The specific method for determining the threshold voltage has been described in the previous embodiments and will not be repeated here.

[0068] Furthermore, the voltage detection unit 321 includes a limiting subunit 3213. The input of the limiting subunit 3213 is connected to the drive voltage. The limiting subunit 3213 is used to limit the drive voltage UA within a predetermined voltage range. The limiting subunit 3213 ensures that the boosting process (i.e., the increase in voltage) of the drive voltage does not damage the first comparator U5 due to excessive voltage, while simultaneously preventing spikes, disturbances, or the like that could erroneously trigger the eye safety mechanisms.

[0069] See also Fig. 9. The clamping subunit 3213 includes two series-connected diodes D1 and D2 and a capacitor C2. The cathode of diode D1 is connected to the power source VCC, while the anode of diode D1 is coupled to the cathode of diode D2. The anode of diode D2 is grounded. One terminal of capacitor C2 is connected to the anode of the series-connected diode D1 and the cathode of diode D2. The other terminal of capacitor C2 is connected to the drive voltage. Specifically, capacitor C2 can block direct current and conduct alternating current. When one of the diodes D3-D6 conducts and the drive voltage connected to it increases, the corresponding voltage value of UA increases. In this case, the voltage UA is higher than the voltage UB, and the first comparator U5 outputs a low level. However, when the drive voltage decreases, the voltage value of UA also decreases accordingly.If a significant disturbance occurs that leads to a larger drop in UA, a false alarm could be triggered, i.e., UA is smaller than UB, and the voltage detection unit 321 detects an anomaly in the drive voltage. To avoid such false alarms, the voltage UA is limited within a certain range, for example, within the difference between the voltage value of the power source VCC and the forward voltage of the diodes.

[0070] Accordingly, the safety switching unit 322 can be a controller 3222, for example, an FPGA. If the voltage UA is lower than the voltage UB, this means that the driver switch has failed. In this case, the first comparator U5 outputs a high signal to the controller 3222, which controls the driver circuit to stop providing the driver voltage.

[0071] In a specific embodiment, Fig. 9 the concrete structure of a safety circuit. In Fig. 9, the LiDAR comprises eight light-generating units (L1-L8). In practice, however, the LiDAR may comprise more light-generating units, e.g., 128. This application is not limited in this regard. The driver switches G01 and G02 may be arranged at the cathodes of the light-generating units L1-L8, while the switching devices T1-T4 may be arranged at the anodes of the light-generating units L1-L8.

[0072] Specifically, the driver circuit includes the components shown by dashed line 30, except for the light-generating units L1-L8. The safety switching unit 322 includes a controller 3222. In the driver circuit, the high-voltage bus line HVBUS serves as a stable power source. When the controller 3222 controls the switching device T1 to close it, the driver switches G01 and G02 close sequentially, thereby activating the light-generating units L1 and L5 connected to the switching device T1 in turn. Specifically, the switching device T1 closes when a high signal level is received. Each closing time of a GaN is approximately 10 ns. Each switching device is coupled to the controller 3222 via a pulse length control subunit 3223.The controller 3222 outputs control pulse signals, and the pulse length control subunit 3223 is capable of controlling the maximum width of the high levels of the control pulse signal sent to the switching device and thus controlling the maximum closing time of each switching device.

[0073] Specifically in the example, the high-voltage bus line HVBUS can Fig. 6 include the current sources VH and VL.

[0074] Furthermore, the safety switching unit 322 can include a filter subunit 3224. The filter subunit 3224 serves to filter out peaks and interference from the control pulse signal. Furthermore, the transmission speed of the control pulse signal can be further increased after filtering.

[0075] As in Fig. 10, the pulse length control subunit 3223 specifically includes capacitors C4-C7. The filter subunit 3224 includes capacitors C4-C7 and resistors R11-R14. The switching device T1 is coupled to the controller 3222 via capacitor C4 and resistor R14. One terminal of the switching device T1 is connected to the high-voltage bus line HVBUS, while the control terminal of the switching device T1 is coupled to one terminal of capacitor C4, and the other terminal of capacitor C4 is connected to the controller 3222. Similarly, the switching device T2 is coupled to the controller 3222 via capacitor C5 and resistor R13, the switching device T3 via capacitor C6 and resistor R12, and the switching device T4 via capacitor C7 and resistor R11. When the 3222 controller is not outputting control signals, the level sent to each switching device is low.Capacitors C4-C7 act as AC coupling, transmit the control pulse signals from the 3222 controller, and limit the maximum width of the high levels of the control pulse signal. By adjusting the capacitance of C4-C7, the maximum width of the high levels of the control pulse signal sent from the 3222 controller to the switching devices can be limited, thereby limiting the maximum closing time of the switching devices T1-T4.

[0076] In this embodiment, four light-generating units are grounded via the same GaN driver switch, e.g., light-generating units L1-L4 are grounded via the same driver switch G01. The voltage detection unit 321 is capable of monitoring the voltages HV1-HV4 of the driver voltage. Since Fig. 9, the eight light-generating units share the same drive voltages HV1-HV4, which means that in one embodiment of the present invention, only a single voltage detection unit 321 is required. Even if the number of light-generating units is higher, for example, 64 or 128, and all light-generating units share the same drive voltages HV1-HV4, the safety circuit according to the embodiments of the present invention requires only a single voltage detection unit 321, thereby simplifying the circuit structure of the safety circuit and reducing the space requirement.

[0077] Specifically, with reference to Fig. 7, the voltage detection unit 321 detects the voltage values ​​of the driving voltages HV1-HV4 of the light-generating units. The voltage detection unit 321 includes diodes D3-D6, wherein the diodes D3-D6 serve to prevent mutual coupling interference between the plurality of driving voltages HV1-HV4. Here, the driving voltage HV1 of the light-generating unit L1 is coupled to the first input of the first comparator U5 via the diode D3 and the capacitor C2; Similarly, the driving voltage HV2 of the light generating unit L2 is coupled to the first input of the first comparator U5 via the diode D4 and the capacitor C2, the driving voltage HV3 of the light generating unit L3 is coupled to the first input of the first comparator U5 via the diode D5 and the capacitor C2, and the driving voltage HV4 of the light generating unit L4 is coupled to the first input of the first comparator U5 via the diode D6 and the capacitor C2.

[0078] In this embodiment, the safety switching unit 322 further comprises a discharge unit 3221, wherein the discharge unit 3221 serves to discharge the energy storage device in the driver circuit when the voltage of the driver voltage drops below the threshold value.

[0079] Specifically, with reference to Fig. 8 and Fig. 9, the discharge unit 3221 comprises a first load R8 and a first switch T5, wherein the first switch T5 is capable of conducting when the voltage values ​​of the drive voltage fall below the threshold voltage, so that the energy storage device (e.g., the capacitor Cn) is discharged via the first load R8.

[0080] In a specific embodiment, see further Fig. 9, the control terminal of the discharge unit 3221 is coupled to the output of the voltage detection unit 321, which means that the control terminal of the discharge unit 3221 is connected to the output of the first comparator U5. The first terminal of the discharge unit 3221 is coupled to the energy storage device, while the second terminal of the discharge unit 3221 is grounded.

[0081] Specifically, the discharge unit 3221 further includes diodes D7-D10, wherein the diodes D7-D10 serve to prevent mutual coupling interference between a plurality of drive voltages HV1-HV4. For example, the drive voltage HV1 of the light generation unit L1 is coupled to one terminal of the switch T5 via the diode D7 and the resistor R8; similarly, the drive voltage HV2 of the light generation unit L2 is coupled to one terminal of the switch T5 via the diode D8 and the resistor R8, the drive voltage HV3 of the light generation unit L3 is coupled to one terminal of the switch T5 via the diode D5 and the resistor R8, while the drive voltage HV4 of the light generation unit L4 is coupled to one terminal of the switch T5 via the diode D6 and the resistor R8. The other terminal of the switch T5 is grounded.

[0082] The discharge unit 3221 further comprises a filter subunit 32211, wherein the filter subunit 32211 serves to filter out reverse spikes and interference from the output signal of the first comparator U5. The filter subunit 32211 comprises a capacitor C3 and a resistor R9. One terminal of the capacitor C3 is coupled to the output of the first comparator U5, while the other terminal of the capacitor C3 is connected to the control terminal of the switch T5. One terminal of the resistor R9 is connected to the control terminal of the switch T5, while the other terminal of the resistor R9 is grounded.

[0083] In one embodiment of the present invention, the discharge unit 3221 is directly controlled by the output signal of the voltage detection unit 321 to perform rapid discharge, thereby causing the light generating units to stop emitting light in time, thus ensuring eye safety.

[0084] With reference to Fig. 9, taking the light emission of the light generating unit L1 as an example, the controller 3222 outputs a high-level control signal, which controls the switching device T1 to close. At the same time, the controller 3222 controls the opening and closing of the GaN driver switch G01 to cause the light generating unit L1 to emit multiple random, coded laser pulse trains, thereby completing normal light emission. In the event of a failure of the GaN driver switch G01, which results in its failure to interrupt, the corresponding driver voltage HV1 continuously drops, causing the voltage UA at the first input of the first comparator U5 to become lower than the voltage UB at the second input (i.e., the threshold voltage), and the first comparator U5 outputs a high level, thereby triggering the eye safety mechanism.

[0085] As part of the eye safety mechanism, the controller 3222 outputs a low-level signal based on the high-level output of the first comparator U5, which opens the switching device T1 to interrupt the power supply to the light generating unit L1. At the same time, the high-level signal of the first comparator U5 controls the switch T5 to close and quickly discharge the remaining charge in the energy storage device coupled to the drive voltage HV1 through the resistor R8, thereby ensuring that the light emission of the light generating unit L1 stops immediately after the switching device T1 is opened. In this embodiment of the present invention, the first comparator U5 outputs a high signal to the controller 3222 when the eye safety mechanism is triggered. The controller 3222 monitors the output signal of the first comparator U5 to control whether the eye safety mechanism has been triggered.

[0086] Furthermore, the controller 3222 can use delayed control signals to control the opening of the switching devices T1-T4 to interrupt the power supply to the light-generating units. During the delay time, the voltage detection unit 321 can repeatedly or continuously check for the occurrence of an eye safety mechanism trigger signal (i.e., the high-level signal of the first comparator U5) to prevent unwanted triggering due to disturbances or reverse spikes.

[0087] Furthermore, the controller 3222 can issue warning messages when the eye safety mechanism is triggered to facilitate subsequent maintenance and replacement.

[0088] See Fig. 11. In this embodiment, the input of the controller 3222 is coupled to the output of the voltage detection unit 321, while the output of the controller 3222 is coupled to the input of the discharge unit 3221.

[0089] In contrast to the Fig. 9, in which the discharge unit 3221 is controlled directly by the output signal of the voltage detection unit 321, in this embodiment the control of the discharge unit 3221 is carried out by the controller 3222.

[0090] With reference to Fig. 11, the controller 3222 outputs a high-level control signal from the light-generating unit L1, thereby closing the switching device T1. At the same time, the controller 3222 controls the emission of multiple random coded laser pulses by the light-generating unit L1 by opening and closing the driver switch G01 to complete normal light emission. In the event of a failure of the GaN driver switch G01, which results in its failure to interrupt, the corresponding driver voltage HV1 continuously drops, causing the voltage UA at the first input of the first comparator U5 to become smaller than the voltage UB at the second input (i.e., the threshold voltage), and the first comparator U5 outputs a high level, triggering the eye safety mechanism.

[0091] As part of the eye safety mechanism, the controller 3222 outputs a low-level signal based on the high-level output of the first comparator U5, thereby opening the switching device T1 to cut off the power supply to the light-generating unit L1. At the same time, after detecting the high-level output of the first comparator U5, the controller 3222 outputs a high-level control signal to close the switch T5, so that the remaining charge in the energy storage device coupled to the drive voltage HV1 is quickly discharged through the resistor R8, thereby stopping the light emission of the light-generating unit L1 immediately after the switching device T1 is opened.

[0092] With reference to Fig. 12 shows Fig. 12 an alternative specific structure of a safety circuit.

[0093] In contrast to Fig. In the embodiment illustrated in Figure 9, the safety switching unit 322 further comprises a gate subunit 3223, wherein the gate subunit 3223 serves to output a first control signal when the drive voltage drops below the threshold voltage. This first control signal is used to stop the charging of the energy storage device in the drive circuit; further, the gate subunit 3223 outputs a second control signal when the drive voltage is above the threshold voltage. This second control signal is used to enable the charging of the energy storage device in the drive circuit. In the specific embodiment, each gate subunit 3223 corresponds to a switching device in the drive circuit, wherein the number of gate subunits 3223 is equal to the number of switching devices.

[0094] Specifically, with simultaneous reference to Fig. 6, when the gate sub-unit 3223 outputs the first control signal, the switching device Tn is controlled by the first control signal to be connected to the power source VL, the capacitor Cn is grounded via the switching device Tn and the charging of the capacitor Cn is stopped; however, when the gate sub-unit 3223 outputs the second control signal, the switching device Tn is controlled by this second control signal to be connected to the power source VH, so that the capacitor Cn is connected to the power source VH via the switching device Tn and charged.

[0095] With specific reference to Fig. 13, the gate subunit 3223 comprises the comparators U1-U4, wherein the output of the comparator U1 is coupled to the control input terminal of the switching device T1, the output of the comparator U2 is coupled to the control input terminal of the switching device T2, the output of the comparator U3 is coupled to the control input terminal of the switching device T3, and the output of the comparator U4 is coupled to the control input terminal of the switching device T4.The first inputs of comparators U1-U4 are each connected to the output of voltage detection unit 321; the second input of comparator U1 is connected to the control signal of controller 3222 that controls switching device T1; the second input of comparator U2 is connected to the control signal of controller 3222 that controls switching device T2; the second input of comparator U3 is connected to the control signal of controller 3222 that controls switching device T3, and the second input of comparator U4 is connected to the control signal of controller 3222 that controls switching device T4.

[0096] In a specific embodiment, the second inputs of the comparators U1-U4 can be directly coupled to the outputs of the controller 3222.

[0097] In another specific embodiment, the second input of the comparator U1 is coupled to a terminal of the capacitor C4, the second input of the comparator U2 is coupled to a terminal of the capacitor C5, the second input of the comparator U3 is coupled to a terminal of the capacitor C6, and the second input of the comparator U4 is coupled to a terminal of the capacitor C7. Further possible connection configurations of the capacitors C4-C7 and the resistors R11-R14 can be described with reference to the embodiment according to Fig. 9, although a detailed repetition is omitted here.

[0098] In one non-limiting embodiment, the first inputs of comparators U1-U4 may be coupled directly to the output of voltage sensing unit 321. Alternatively, the first inputs of comparators U1-U4 may be coupled to the output of voltage sensing unit 321 via capacitor C1, with the first inputs of comparators U1-U4 also being grounded via resistor R1. Resistor R1 acts as a pull-down resistor, ensuring that the first inputs of comparators U1-U4 always receive a low signal when the eye safety mechanism is not triggered, thereby ensuring that controller 3222 can control the proper closing and opening of switching devices T1-T4.

[0099] In one embodiment of the present invention, the light emission of the light generation unit L1 can be described as follows: The controller 3222 outputs a high signal to the positive input of the comparator U1. Since the drive voltage UA (applied to the negative input of the first comparator U5) is greater than the threshold voltage UB (applied to the positive input of the first comparator U5), the first comparator U5 outputs a low signal to the negative input of the comparator U1. This causes the comparator U1 to output a high signal, thus controlling the closure of the switching device T1. At the same time, the controller 3222 controls the opening and closing of the driver switch G01 to cause the light generation unit L1 to emit several random, coded laser pulse trains, thus completing normal light emission.

[0100] In the event of a failure of the driver switch G01, which results in its failure to interrupt operation, the driver voltage HV1 of the light-generating unit L1 continuously drops. As a result, the voltage UA (at the negative input of the first comparator U5) becomes lower than the voltage UB (at the positive input of the first comparator U5), whereupon the first comparator U5 outputs a high signal, which is also higher than the voltage that the controller 3222 outputs to the positive input of the comparator U1. As a result, the comparator U1 outputs a low signal, which opens the switching device T1 and stops the light emission of the light-generating unit L1. At the same time, the high signal of the first comparator U5 causes the switch T5 to close, quickly dissipating the residual charge in the energy storage device coupled to the driver voltage HV1 via the resistor R8.This ensures that the light emission of the light generating unit L1 ends immediately after the switching device T1 is opened.

[0101] Furthermore, the output signal of the voltage detection unit 321 not only directly controls the opening of the switching devices T1-T4 and thus the interruption of the power supply, but also the rapid discharge of the discharge unit 3221. This enables the eye safety mechanism to be triggered without delay, thereby increasing the reaction speed and stopping the light emission of the light generating unit in time to further ensure eye safety.

[0102] With reference to Fig. 14 shows another specific structure of a safety circuit.

[0103] In contrast to the embodiment according to Fig. 13, in which the discharge unit 3221 is controlled by the output signal of the voltage detection unit 321, takes place in the Fig. 14, the control of the discharge unit 3221 by the controller 3222.

[0104] With reference to Fig. 14, taking the emission of the light-generating unit L1 as an example, the controller 3222 outputs a high signal to the positive input of the comparator U1. Since the drive voltage UA (applied to the negative input of the first comparator U5) is greater than the threshold voltage UB (applied to the positive input of the first comparator U5), the first comparator U5 outputs a low signal to the negative input of the comparator U1, whereupon the comparator U1 outputs a high signal, thereby closing the switching device T1. At the same time, the controller 3222 controls the opening and closing of the drive switch G01 to cause the light-generating unit L1 to emit multiple random, coded laser pulse trains and complete normal light emission.

[0105] In the event of a failure of the driver switch G01, which results in its failure to interrupt operation, the driver voltage HV1 of the light-generating unit L1 continuously drops. As a result, the voltage UA (at the negative input of the first comparator U5) becomes lower than the voltage UB (at the positive input of the first comparator U5), whereupon the first comparator U5 outputs a high signal, which is also higher than the voltage that the controller 3222 outputs to the positive input of the comparator U1. As a result, the comparator U1 outputs a low signal, which opens the switching device T1 and stops the light emission of the light-generating unit L1. At the same time, the controller 3222, based on the high signal of the first comparator U5, sends a high signal to the switch T5, causing it to close and discharge the energy storage device coupled to the driver voltage HV1.The resulting residual charge is discharged as quickly as possible via the resistor R8 to ensure that the light generating unit L1 stops emitting light immediately after the switching device T1 opens.

[0106] Further detailed configurations of the Fig. 14 can be described with reference to the safety circuits shown in the Fig. 8 and Fig. 9, although a detailed repetition is omitted here.

[0107] In a specific application scenario, with simultaneous reference to the Fig. 12 and Fig. 15 and the Fig. 14 and Fig. 15, before time t5, the drive voltage UA (applied to the negative input of the first comparator U5) is greater than the threshold voltage UB (applied to the positive input of the comparator U5), causing the output voltage VC of the first comparator U5 to be low. After time t5, the drive voltage UA of the first comparator U5 becomes lower than the threshold voltage UB, indicating that the GaN drive switch has failed, and the output voltage VC of the first comparator U5 becomes high. The high output voltage VC represents a trigger signal for the eye safety mechanism.

[0108] With reference to Fig. 16, an embodiment of the present invention also discloses a driver testing method for a LiDAR. This driver testing method specifically includes the following steps:

[0109] Step 1601: Detect the voltage value of the drive voltage.

[0110] Step 1602: Upon detecting that the voltage value of the drive voltage falls below the threshold value, controlling the drive circuit to stop providing the drive voltage.

[0111] It should be understood that, in a specific embodiment, the driver testing method may be implemented by a software program, wherein this software program is executed on a processor integrated into a chip or chip module. Alternatively, this method may be implemented as a mixture of software and hardware solutions, with the present application imposing no restrictions in this regard.

[0112] In a specific implementation of step 1601, it is not mandatory to detect the exact value of the drive voltage; instead, the comparison result between the drive voltage and the threshold voltage may be detected.

[0113] In a specific implementation of step 1602, controlling the driver circuit to stop providing the drive voltage may specifically consist of instructing the charging device in the driver circuit to stop charging the energy storage device and, at the same time, discharging the energy storage device.

[0114] Further specific implementations of the driver test method can be found in the previously described embodiments, although a detailed repetition is omitted here.

[0115] An embodiment of the present invention further discloses a LiDAR comprising at least one light-generating unit. The LiDAR is capable of emitting detection light beams using multiple light-generating units. Furthermore, the LiDAR comprises the safety circuit described in one of the aforementioned embodiments. The LiDAR can use the safety circuit to control whether the light-generating units safely emit light or completely stop emitting light to ensure eye safety.

[0116] Furthermore, the LiDAR comprises a plurality of light receiving units, wherein these light receiving units are used to detect reflected light beams from obstacles, which correspond to the respective light generating units.

[0117] It should be understood that the term and / or, as used in this description, simply denotes a logical connection between the connected objects and represents three possible relations, namely: the sole presence of A, the simultaneous presence of A and B, and the sole presence of B. Furthermore, the term / used in this description shows that the connected objects are in an or relationship.

[0118] The term multiple as used in this specification means a number of two or more.

[0119] In the present embodiments, the terms "first," "second," and similar designations serve merely to distinguish and clarify the respective objects and do not imply any order of precedence. These terms do not limit the number of devices described in the embodiments in any way and do not constitute any limitations on this application.

[0120] The term "connection" used in this description describes various connection types, including direct connections and indirect connections, as long as the connection serves the purpose of enabling communication between the devices. The connection types described in the embodiments are not limited in this context.

[0121] The embodiments described above may be implemented in whole or in part by software, hardware, firmware, or any combination of these technologies. If the described embodiments are implemented in software, they may be realized in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions or computer programs that, when loaded onto or executed by a computer, perform the operations or functions in whole or in part according to the embodiments described in this application. The computer referred to in the context of this document may be a general-purpose computer, a specialized computer, a computer network, or another programmable device.The computer instructions mentioned may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center, either wired or wirelessly. The computer-readable storage medium may be any computer-accessible medium or a database storage device such as a server, data center, or other configuration consisting of one or more accessible media.

[0122] In several embodiments provided by this application, it should be understood that the disclosed methods, devices, and systems may be implemented in other ways. For example, the device embodiments described above are for illustrative purposes only; the illustrated division of units represents only a logical functional division, which may be designed differently in practical implementation; for example, multiple units or components may be combined or integrated into another system, some features may be omitted or not implemented. Furthermore, the couplings shown or discussed, direct couplings, or communication links may also be indirect couplings or communication links via some interfaces, devices, or units, which may be implemented either electrically, mechanically, or in another form.

[0123] The units described as separate components may or may not be physically separated from each other. Likewise, the units depicted as individual units may or may not be physical units, ie, they may be located at one location or distributed across multiple network units. It is possible to select some or all of the units to achieve the objective of the present embodiments, depending on practical requirements.

[0124] Furthermore, the functional units described in the various embodiments of the present invention may be integrated into a single processing unit, exist as separate physical units, or be integrated as two or more units into a single unit. The above-mentioned integrated units may be implemented either in hardware or in hardware with software-based functional units.

[0125] The above-mentioned integrated units implemented in the form of software-based functional units can be stored in a computer-readable storage medium. The above-mentioned software-based functional units stored in a storage medium include a plurality of instructions that enable a computing device (such as a personal computer, server, or network device) to perform some of the method steps described in the various embodiments of the present invention.

[0126] Although the invention has been disclosed in the form described above, it is not limited thereto. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the scope of the invention should be determined by the ranges defined in the claims.

Claims

[1] A safety circuit for a driver circuit of a lidar, characterized by that the lidar comprises a light generating unit, wherein the driver circuit is capable of providing a drive voltage to drive the light generating unit to emit light, wherein one end of the light generating unit receives the drive voltage and the other end of the light generating unit is coupled to a driver switch; wherein the safety circuit comprises: a voltage detection unit for detecting the voltage value of the driving voltage; and a safety switching unit used to control the driver circuit so that the supply of the driver voltage is stopped when the voltage value of the driver voltage falls below the threshold voltage, the threshold voltage representing the voltage value of the driver voltage in the event of a driver switch failure. [2] Safety circuit according to claim 1, characterized by that the drive voltage has a maximum and a minimum voltage value during normal light emission of the light generating unit within a voltage repetition cycle, wherein the threshold voltage is smaller than the minimum voltage value. [3] Safety circuit according to claim 2, characterized by that the difference between the maximum voltage value and the minimum voltage value is defined as the first voltage change and the threshold voltage is calculated by the difference between the minimum voltage value and a safety voltage change, the safety voltage change being the product of the first voltage change and a predetermined ratio. [4] Safety circuit according to claim 2, characterized bythat the threshold voltage is less than the minimum voltage value and greater than the safe permissible voltage value, where the safe permissible voltage value is the drive voltage value reached when the duration of light emission of the light generating unit exceeds the specified safety time range of light emission. [5] Safety circuit according to claim 4, characterized by that the threshold value corresponds to the average of the minimum voltage value and the safely permitted voltage value. [6] Safety circuit according to claim 1, characterized byin that the driver circuit comprises a charging device and an energy storage device, wherein the charging device serves to charge the energy storage device, and wherein the energy storage device provides the drive voltage; wherein the safety switching unit serves to control the charging device so that, when the drive voltage is below the threshold voltage, it stops charging the energy storage device and, at the same time, the energy storage device is discharged. [7] Safety circuit according to claim 1, characterized by that the voltage detection unit includes: a comparison subunit used to output a first voltage based on the comparison result between the drive voltage and the threshold voltage, this first voltage indicating whether the drive voltage is abnormal. [8] Safety circuit according to claim 7, characterized by that the comparison unit includes: a first comparator whose positive input terminal is connected to the threshold voltage, whose negative input terminal is connected to the drive voltage, and whose output outputs the first voltage. [9] Safety circuit according to claim 8, characterized by that the voltage detection unit includes: a limiting subunit whose input is coupled to the drive voltage and which serves to limit the drive voltage to a predetermined voltage range. [10] Safety circuit according to claim 8, characterized by that the voltage detection unit includes: a first voltage divider subunit having an input coupled to the power supply and an output connected to the negative input terminal of the first comparator, the first voltage divider subunit outputting an initial drive voltage higher than the threshold voltage. [11] Safety circuit according to claim 1, characterized by that the other end of N light generation units is each coupled to a common driver switch, wherein the number of driver switches is M, the total number of light generation units in the lidar is N × M, and where N and M are positive integers greater than 1; and the voltage detection unit serves to detect the voltage values ​​of the driver voltage that drives N light generation units. [12] Safety circuit according to claim 11, characterized by that each light generating unit is connected to a power source via a switching device, wherein the first terminal of the switching device is coupled to the power source and the second terminal of the switching device is coupled to one end of the light generating unit, and each input of the voltage detecting unit is coupled to the second terminal of the respective switching device. [13] Safety circuit according to claim 1, characterized by that the safety switching unit includes: a discharge unit which serves to discharge the energy storage device in the driver circuit when the voltage value of the driver voltage is below the threshold voltage. [14] Safety circuit according to claim 13, characterized by that the control terminal of the discharge unit is coupled to the output of the voltage detection unit, the first terminal of the discharge unit is coupled to the energy storage device, and the second terminal is grounded. [15] Safety circuit according to claim 13, characterized by that the safety switching unit includes: a controller whose input is coupled to the output of the voltage sensing unit and whose output is connected to the input terminal of the discharge unit. [16] Safety circuit according to claim 15, characterized bythat the control terminal of the discharge unit is coupled to the output of the controller, the first terminal of the discharge unit is connected to the energy storage device, and the second terminal is grounded. [17] Safety circuit according to claim 15, characterized by that the controller controls the energy storage device such that the charging of the energy storage device in the driver circuit is stopped when the driver voltage falls below the threshold voltage. [18] Safety circuit according to claim 13, characterized by that the unloading unit includes: a first burden; a first switch which conducts when the voltage value of the drive voltage falls below the threshold value, so that the energy storage device is discharged via the first load. [19] Safety circuit according to claim 1, characterized by that the safety switching unit includes: a gate subunit that outputs a first control signal when the drive voltage falls below the threshold voltage, the first control signal being used to stop charging of the energy storage device in the drive circuit; wherein the gate subunit outputs a second control signal when the drive voltage is above the threshold voltage, said second control signal controlling the charging of the energy storage device. [20] Safety circuit according to claim 19, characterized by that the safety circuit is coupled to the output of the voltage detection unit. [21] Safety circuit according to claim 19, characterized by that the safety switching unit comprises a controller whose input is coupled to the output of the voltage detection unit, and the input of the gate subunit is coupled to the output of the controller. [22] Safety circuit according to claim 21, characterized by that in the event that the voltage value of the drive voltage falls below the threshold value, the controller outputs a third control signal to the input of the gate subunit; and in the event that the voltage value of the drive voltage rises above the threshold value, the controller outputs a fourth control signal to the input of the gate subunit. [23] A method for driver detection for a lidar, characterized by that the lidar comprises a light generating unit, wherein the driver circuit can provide the drive voltage to operate the light generating unit, wherein one end of the light generating unit receives the drive voltage and the other end of the light generating unit is coupled to a drive switch, the method comprising: detecting the voltage value of the driver voltage; and, when the drive voltage falls below the threshold voltage, controlling the drive circuit so that the drive voltage is no longer provided, where the threshold voltage refers to the voltage value of the drive voltage in the event of a drive switch failure. [24] Method for driver detection according to claim 23, characterized by that the driver circuit comprises a charging device and an energy storage device, wherein the charging device serves to charge the energy storage device, wherein the energy storage device provides the driver voltage, and wherein controlling the driver circuit such that the driver voltage is no longer provided comprises: Controlling the charging device to stop charging the energy storage device; and Control that the energy storage device is discharged. [25] A lidar, characterized bythat it comprises a light generating unit and further a safety circuit according to one of claims 1 to 22.

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