Laser emission circuit, laser emission control method, and laser radar

Abstract

This invention provides a laser emitting circuit, a laser emitting control method, and a lidar. The laser emitting circuit includes: a light emitting module configured to emit a detection beam for detecting a target; an energy storage module coupled to the light emitting module; a driving module adapted to drive the light emitting module to emit light; a pre-charging module coupled to the energy storage module for charging the energy storage module; and a discharge module coupled to both the pre-charging module and the energy storage module, adapted to discharge the energy storage module before the pre-charging module charges it. This invention improves the stability of the lidar's emitted energy, thereby enhancing its detection performance.

Description

Technical Field

[0001] This invention relates to the field of lidar, and more particularly to a laser emitting circuit, a laser emitting control method, and a lidar. Background Technology

[0002] With the development of artificial intelligence, autonomous driving technology has matured significantly. Environmental perception is a necessary prerequisite for autonomous driving, and obstacle detection is a crucial component of environmental perception. Common obstacle detection devices, also known as vehicle-mounted detection equipment, include sensors such as LiDAR, cameras, millimeter-wave radar, and ultrasonic sensors. LiDAR measures the distance to obstacles by analyzing the time difference between the emitted laser signal and the echo signal reflected from the obstacle's surface. It is also less affected by lighting, smoke, and environmental factors, making it widely used in autonomous driving and other fields. Autonomous vehicles utilize vehicle-mounted detection devices such as LiDAR, cameras, millimeter-wave radar, or ultrasonic sensors to detect objects around the vehicle and adjust driving strategies accordingly, such as slowing down, steering, or emergency braking, to achieve safe driving.

[0003] LiDAR (Light Detection and Ranging) systems can detect objects and perceive their surroundings. However, in practical applications, the unstable energy emitted by the LiDAR makes the detected echo signals difficult to identify, thus affecting the detection performance of the LiDAR. Summary of the Invention

[0004] In view of this, the present invention provides a laser emitting circuit, a laser emitting control method, and a lidar for lidar, which can improve the stability of the lidar's luminous energy and thus enhance the lidar's detection performance.

[0005] This specification provides an embodiment of a laser emitting circuit for lidar, comprising:

[0006] The optical emission module is configured to emit a detection beam for detecting targets;

[0007] An energy storage module is coupled to the optical emitting module;

[0008] A driving module, adapted to drive the light emitting module to emit light;

[0009] A pre-charging module, coupled to the energy storage module, is used to charge the energy storage module;

[0010] The discharge module is coupled to the pre-charge module and the energy storage module respectively, and is adapted to discharge the energy storage module before the pre-charge module charges the energy storage module.

[0011] Optionally, the optical emitting module includes at least one laser group, and the laser group includes multiple lasers;

[0012] The energy storage module includes multiple energy storage units, each of which is coupled to a corresponding laser group.

[0013] The driving module includes multiple driving units, each of which is coupled to a corresponding laser. In response to a laser emission trigger signal, the energy storage module and the corresponding laser are selected.

[0014] The pre-charging module includes multiple pre-charging units, each of which is coupled to a power input terminal and at least one energy storage unit.

[0015] Optionally, the laser is adapted to continuously emit multiple laser pulses;

[0016] The discharge unit is adapted to discharge the energy storage unit coupled to the laser before the laser continuously emits the first laser pulse among the plurality of laser pulses.

[0017] Optionally, the discharge module includes: a discharge unit coupled to each pre-charge unit and each energy storage unit, adapted to discharge the coupled energy storage unit before each pre-charge unit charges the coupled energy storage unit.

[0018] Optionally, the discharge module includes: a plurality of discharge units, each discharge unit being coupled between an energy storage unit and at least one pre-charge unit, and is adapted to discharge the coupled energy storage unit before the pre-charge unit charges the coupled energy storage unit.

[0019] Optionally, the discharge unit includes: a first switch, a resistor, and a first diode coupled between the pre-charging unit, the laser module, the energy storage unit, and ground, adapted to form a discharge path before the pre-charging unit charges the energy storage unit, so as to discharge the energy storage unit.

[0020] Optionally, the laser emitting circuit further includes a voltage detection module, comprising multiple voltage detection units, wherein the voltage detection units are adapted to detect the voltage across the coupled energy storage unit, and when the detected voltage is less than a preset threshold, cause the energy storage unit to stop discharging.

[0021] Optionally, the pre-charge unit includes:

[0022] An inductor, the first end of which is coupled to the power input terminal;

[0023] The second diode has its anode coupled to the second terminal of the inductor and its cathode coupled to the energy storage unit and the laser assembly.

[0024] The second switch is coupled between the second terminal of the inductor and ground.

[0025] Optionally, the laser emitting circuit further includes a switching module, which includes multiple switching units coupled between at least one pre-charging unit and the laser group, and is adapted to perform gating control on the laser group.

[0026] Optionally, the voltage at the power input terminal is the turn-on voltage of the laser.

[0027] This specification also provides an embodiment of a lidar, including:

[0028] The laser emitting circuit described in any of the foregoing embodiments;

[0029] The controller is adapted to output control signals to the pre-charging module, the driving module and the discharge module respectively to control the light emitting module to emit light, wherein: before outputting a pre-charging trigger signal to the pre-charging module to charge the energy storage module, the energy storage module is discharged.

[0030] Optionally, the optical emitting module includes at least one laser group, and the laser group includes multiple lasers;

[0031] The controller is adapted to discharge the energy storage module coupled to the laser before outputting a laser emission trigger signal to the drive module to trigger the laser to continuously emit multiple pulses.

[0032] This specification also provides a laser emission control method for controlling an optical emission module to emit a detection beam for detecting a target. The optical emission module is coupled to a driving module and an energy storage module, respectively, and the energy storage module is coupled to a pre-charge module via a discharge module. The control method includes:

[0033] Before the energy storage module is charged, a discharge signal is output to the discharge module to cause the energy storage module to discharge.

[0034] A pre-charge signal is output to the pre-charge module, enabling the pre-charge module to store electrical energy;

[0035] A drive signal is output to the drive module to drive the light emitting module to emit light.

[0036] Optionally, the step of outputting a drive signal to the drive module to cause the energy storage module to discharge and drive the laser to emit light includes:

[0037] Multiple driving signals are continuously output to the driving module, causing the energy storage module to discharge and driving the optical emitting module to continuously emit multiple detection beams.

[0038] Optionally, the laser emission control method further includes: when the voltage across the energy storage module is detected to be less than a preset threshold, outputting a discharge stop signal to the discharge module, so that the energy storage module stops discharging.

[0039] The laser emitting circuit in the embodiments of this specification, wherein before the pre-charging module charges the energy storage module, the energy storage module is discharged by a discharge module coupled to the pre-charging module and the energy storage module, which can prevent the energy storage module from having residual charge. Therefore, the light emitting energy of the light emitting module can be made more stable and consistent, and the detection performance of the lidar can be improved.

[0040] Furthermore, since each pre-charging unit is coupled to the power input terminal and at least one energy storage unit respectively, before multiple pre-charging units sequentially charge the energy storage unit of any laser group, the discharge unit coupled to the energy storage unit discharges the energy, thus preventing residual charge in the energy storage unit. Therefore, when the laser emits multiple laser pulses continuously, the residual energy after the previous light-emitting channel emits light can be prevented from affecting the subsequent light-emitting channel, thereby avoiding crosstalk between different light-emitting channels and improving the detection performance of the lidar.

[0041] Furthermore, multiple energy storage units share a single discharge unit. Before each pre-charging unit charges the coupled energy storage unit, the coupled energy storage unit is discharged, which can save circuit area.

[0042] The discharge unit includes a first switch, a resistor, and a second diode. The resistor can limit the discharge speed, and the second diode can prevent the parasitic inductance and capacitance in the discharge circuit from causing resonance during the discharge of the energy storage unit, which would cause voltage fluctuations in the energy storage unit, thereby making the entire discharge process very stable.

[0043] Furthermore, by detecting the voltage across the energy storage unit using a voltage detection unit, and stopping the energy storage unit from discharging when the detected voltage is less than a preset threshold, more precise control of the discharge process can be achieved, reducing the proportion of the discharge process in the entire laser emitting circuit operation process, and improving the luminous efficiency of the laser emitting circuit and the corresponding target detection efficiency.

[0044] Furthermore, by connecting the pre-charging unit to the laser group via a switching unit, the laser group can be selected and controlled. More specifically, by turning the switching unit on and off, the laser group coupled to it can be controlled as a whole, thereby simplifying the control logic of the drive module.

[0045] Furthermore, after each laser pulse is emitted, a relatively fixed charge remains in the energy storage unit due to parasitic effects. The greater the deviation between the input voltage and the laser's turn-on voltage, the more residual charge remains. Therefore, the voltage at the power input terminal is set to the laser's turn-on voltage. This improves the consistency of multiple pulses emitted continuously by a single laser, further enhancing the detection performance of the lidar. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of a laser emitting circuit used in lidar.

[0048] Figure 2 This is a structural block diagram of a laser emitting circuit for lidar in an embodiment of this specification;

[0049] Figure 3 This is a schematic diagram illustrating a specific example of a laser emitting circuit for a lidar in an embodiment of this specification.

[0050] Figure 4a This is a schematic diagram of two consecutive pulses emitted by a laser.

[0051] Figure 4b This is a schematic diagram of three consecutive pulses emitted by a laser.

[0052] Figure 5 This is a specific example structural diagram of another laser emitting circuit for lidar in the embodiments of this specification;

[0053] Figure 6 This is a specific example structural diagram of another laser emitting circuit for lidar in the embodiments of this specification;

[0054] Figure 7 for Figure 5 and Figure 6 The diagram shown illustrates the working principle of the laser emitting circuit.

[0055] Figure 8 This is a schematic diagram of the structure of a lidar in one of the embodiments of this specification;

[0056] Figure 9 This is a schematic diagram illustrating the application of an autonomous vehicle in one of the embodiments of this specification;

[0057] Figure 10 This is a flowchart of a laser emission control method in one of the embodiments of this specification. Detailed Implementation

[0058] To enable those skilled in the art to better understand and implement the embodiments of this specification, the light emission principle of the light emission module involved in the embodiments of this specification will be explained below with reference to a structural diagram of a single-pulse laser emitting circuit.

[0059] like Figure 1 The diagram shows a schematic of a laser emitting circuit for lidar, illustrating a single-channel laser emitting circuit structure. Specifically, the laser emitting circuit 10 includes a light emitting module 11, an energy storage module 12, a driving module 13, and a pre-charging module 14. The light emitting module 11 can be configured to emit a detection beam for target detection, and the light emitting module 11 may specifically include a laser. The driving module 13 includes a switch S1, which can be switched on and off under the control of a driver 2. The energy storage module 12 may specifically be an energy storage capacitor C. The pre-charging module 14 includes an inductor L, a diode D connected to the inductor L, and a switch M1, which is used to input voltage VIN and store electrical energy, thereby charging the energy storage capacitor C and establishing a high voltage on the energy storage capacitor C.

[0060] Typically, because there is no safety circuit on the input side, the input voltage VIN is usually not very high, for example, 4V-6V, and cannot be directly used to drive the laser LD; it needs to be boosted. The high voltage established on the energy storage capacitor C can be significantly higher than the input voltage VIN, for example, 60V, and can therefore be used to drive the laser LD. After the high voltage is established, the energy storage capacitor C can drive the laser LD to emit a laser beam.

[0061] The working process is as follows: During the pre-charging stage, the driver 1 controls the switch M1 to close. A closed switch M1 is equivalent to a short circuit in the circuit, so the current generated by the input voltage VIN flows through the inductor L and is grounded through switch M1. As the inductor current increases, energy is stored in the inductor L. When the pre-charging stage is complete, switch M1 opens. At this time, due to the current-holding characteristic of inductor L, the current flowing through inductor L does not immediately become zero, but slowly changes from the current value at the end of charging to zero. During this process, since switch M1 is open, inductor L can only charge the energy storage capacitor C, thus increasing the voltage across capacitor C. Once a high voltage (e.g., 60V) has been established across capacitor C, switch S1 closes. Due to the unidirectional conductivity of diode D, the energy storage capacitor C cannot discharge through diode D, but can only discharge through the circuit of laser LD and switch S1. Therefore, current flows through laser LD, and energy storage capacitor C drives laser LD to emit light. When the energy storage capacitor C is fully discharged, switch M1 is closed again and switch S1 is opened, and the cycle of pre-charging, charging, and discharging is repeated, continuously driving the laser LD to emit light.

[0062] However, after the energy storage module 12 is discharged, there may be residual charge, which will cause the light emission energy of the light emitting module 11 to be unstable. This will make it difficult for the lidar echo detection device to receive the predetermined echo signal, or to identify the received echo signal, thus affecting the lidar detection performance.

[0063] To address the aforementioned issues, in this embodiment of the specification, before the pre-charging module charges the energy storage module, a discharge module coupled to both the pre-charging module and the energy storage module discharges the energy storage module. This prevents the energy storage module from having residual charge, thereby making the light emission energy of the light emitting module more stable and consistent. This enables the lidar to receive the echo from the predetermined target, improving the lidar's detection performance.

[0064] To enable those skilled in the art to better understand the concept, advantages, and implementation schemes of the solutions provided in this specification, the principles of the laser emitting circuit, laser emitting control method, and lidar solutions provided in the embodiments of this specification will be described in detail and illustrated with reference to the accompanying drawings and specific examples.

[0065] Reference Figure 2 The block diagram of the laser emitting circuit for lidar shown is illustrated in the embodiments of this specification, as follows: Figure 2 The laser emitting circuit 20 shown may include: a light emitting module 21, an energy storage module 22, a driving module 23, a pre-charging module 24, and a discharge module 25, wherein:

[0066] The light emitting module 21 is configured to emit a detection beam for detecting a target;

[0067] The energy storage module 22 is coupled to the optical emitting module;

[0068] The driving module 23 is adapted to drive the light emitting module 21 to emit light;

[0069] The pre-charging module 24 is coupled to the energy storage module 22 and is used to charge the energy storage module 22;

[0070] The discharge module 25 is coupled to the pre-charge module 24 and the energy storage module 22 respectively, and is adapted to discharge the energy storage module 22 before the pre-charge module 24 charges the energy storage module 22.

[0071] The operation of the laser emitting circuit 20 described above can include the following stages: energy discharge from the energy storage module 22, pre-charging and storing energy by the pre-charging module 24, charging the energy storage module 22 by the pre-charging module 24, and discharging by the energy storage module 22 to drive the optical emitting module 21 to operate. These stages can be repeated cyclically according to the laser emission parameters. The working principle of the laser emitting circuit 20 is briefly described below:

[0072] The first stage is the energy discharge phase of the energy storage module 22. Since the energy storage module 22 still retains residual energy after the light emitting module 21 emits light, if it directly enters the next cycle, the energy contained in the energy storage module 22 after the charging process will include not only the energy provided by the pre-charging module 24 during the next cycle, but also the residual energy. Therefore, when the energy storage module 24 discharges to drive the light emitting module 21 to emit light in the next cycle, the laser pulse emitted by the light emitting module 21 may have a wider pulse width or a higher amplitude. If the residual energy in the energy storage module 22 is high, the light energy emitted by the light emitting module 21 in the next cycle will exceed the preset energy parameter. As a result, the echo detection module (not shown) in the lidar may not be able to identify the light emitted by the light emitting module 21. Therefore, before the pre-charging module 24 charges the energy storage module 22, for example, at the beginning of each cycle, the residual energy in the energy storage module 22 can be discharged through the discharge module 25. Specifically, the discharge module 25 can respond to the discharge signal BL to connect the first terminal of the energy storage module 22 to ground, causing the energy storage module 22 to discharge. The discharge signal BL is a signal that triggers the connection between the first terminal of the energy storage module 22 and ground. The discharge signal BL can be issued by a controller (not shown) based on the optical emission control parameters of the optical emission module 21, or by a dedicated driver (not shown).

[0073] The system then enters the pre-charging phase of the pre-charging module 24. In response to the conduction signal K, the pre-charging module 24 establishes a connection between the input power terminal VIN and ground, thus pre-storing energy. The conduction signal K can be issued by a controller (not shown) based on the optical emission control parameters of the optical emission module 21, or by a dedicated driver (not shown).

[0074] Next, the energy storage module 22 enters the charging stage. For example... Figure 2 As shown, the path between the input power terminal VIN and ground is disconnected, and the pre-charging module 24 charges the energy storage module 22.

[0075] Next, we enter the discharge phase of energy storage module 22. (Continue referring to...) Figure 2 In response to the laser emission trigger signal Tr, the path between the energy storage module 22, the light emission module 21, the driving module 23 and the ground is turned on, and the light emission module 21 emits light.

[0076] In specific implementations, the light emitting module 21 can be implemented using a laser, such as a semiconductor laser (LD). Subsequent examples in this specification will use LD lasers as examples.

[0077] As an optional example, the optical emitting module 21 may include one laser or multiple lasers. Depending on the specific configuration, the laser may emit a single pulse or emit multiple pulses continuously.

[0078] For any laser, if it emits a single pulse, as can be seen from the above working process, the energy storage module 22 can be pre-discharged in each cycle. Preferably, if the laser emits multiple pulses continuously, the energy storage module 22 can be discharged through the above-mentioned discharge process before the first pulse of the multiple pulses are emitted.

[0079] As can be seen from the above, when the energy storage module 22 discharges to drive the light emitting module 21 to emit light, there will be no situation where the light emitting module 21 emits light unstably due to excessive energy. This ensures that the light emitting module 21 emits light according to the preset light emission control parameters in each cycle, thus making the light emitting energy of the light emitting module 21 more stable and consistent, thereby improving the detection performance of the lidar.

[0080] It is understandable that, in specific implementations, after the pre-charging stage, the residual electrical energy in the energy storage module 22 can be discharged through the discharge module 25 first, and then the energy storage module can be charged by the pre-charging module, as long as the energy discharge can be completed before the energy storage module is charged.

[0081] To enable those skilled in the art to better understand and implement the embodiments of this specification, a specific example structure of a laser emitting circuit is described in detail below.

[0082] Reference Figure 3 The diagram shows a specific example of a laser emitting circuit for a lidar. The laser emitting circuit 30 can be used in a lidar and specifically includes: a light emitting module 31, an energy storage module 32, a driving module 33, a pre-charging module 34, and a discharge module 35.

[0083] like Figure 3 As shown, the optical emitting module may include a laser, such as a semiconductor laser. In specific implementations, the laser LD may be a vertical-cavity surface-emitting laser (VCSEL) or an edge-emitting laser (EEL), and the scope of protection of this invention is not limited by the type of laser. Furthermore, the laser used may be a laser array.

[0084] The energy storage module 32 can specifically be an energy storage capacitor C.

[0085] The drive module 33 may include a drive switch S1, which is turned on under the drive signal input by the driver 2, so that the laser LD can emit light.

[0086] The pre-charging module 34 may include: an inductor L, a second diode D2 connected to the inductor L, and a second switch M2, which are used to input voltage VIN and store electrical energy, thereby charging the energy storage capacitor C and establishing a high voltage on the energy storage capacitor C.

[0087] In some embodiments of this specification, such as Figure 3 As shown, the discharge module 35 may include a resistor R, a first diode Db, and a first switch Mb coupled between the pre-charge module 34, the energy storage module 32, and ground. The resistor R limits the discharge speed, and the first diode Db prevents parasitic inductance and capacitance in the discharge circuit from causing resonance during the discharge of the energy storage module 32, thus preventing voltage fluctuations in the energy storage module 32 and ensuring a very smooth discharge process.

[0088] The following is a brief description of its working process:

[0089] First, driver 3 controls the first switch Mb to close, forming a current-carrying circuit between the energy storage capacitor C, resistor R, first diode Db, and the first switch Mb to ground, which can discharge the residual charge in the energy storage capacitor C. Then, driver 1 controls the second switch M2 to close. The closed second switch M2 is equivalent to a short circuit in the circuit, so the current generated by the input voltage VIN flows through the inductor L and is grounded through the second switch M2. As the inductor current increases, energy is stored in the inductor L. When the pre-charging stage is complete, the second switch M2 opens. At this time, due to the current-holding characteristic of the inductor L, the current flowing through the inductor L does not immediately become zero, but slowly decreases from the current value at the end of charging to zero. During this process, since the second switch M2 is open, the inductor L can only charge the energy storage capacitor C, thus increasing the voltage across the energy storage capacitor C. Once a high voltage (e.g., 60V) has been established on the energy storage capacitor C, driver 2 controls the drive switch S1 to close. Due to the unidirectional conductivity of the first diode Db and the second diode D2, the energy storage capacitor C cannot discharge through the first diode Db and the second diode D2. It can only discharge through the circuit of the laser LD and the drive switch S1. Therefore, current flows through the laser LD, and the energy storage capacitor C discharges to drive the laser LD to emit light. When the energy storage capacitor C has finished discharging, the first switch Mb is closed again, and the drive switch S1 is opened. The cycle of discharging, pre-charging, charging, and discharging is repeated, continuously driving the laser LD to emit light.

[0090] In the field of lidar, there is a concept of pulse coding. Each laser can continuously emit multiple pulses to achieve multi-pulse coding of the laser. Specifically, regarding coding, it means that each laser emits n (n≥2) pulses at a time, which is a method to prevent crosstalk.

[0091] During encoding, there are several ways to change the parameters. For example, the pulse widths of two pulses can be different (e.g., ...). Figure 4a As shown, the pulse width of pulse 1 is slightly smaller than that of pulse 2, and the time interval between the preceding and following pulses can be different (e.g., Figure 4b As shown, where Δt1≠Δt2), the amplitudes of the pulses are different (e.g. Figure 4a As shown, pulse 2 has a higher amplitude than pulse 1, and the number of pulses is different (e.g., Figure 4a The image shows a double pulse. Figure 4b (The diagram shows a three-pulse pattern). For example, lidar A emits a double pulse, and lidar B also emits a double pulse. The time interval Δt between the double pulses of the two lidars is... A ≠Δt B In this way, lidar A will only receive and process the interval Δt between the two pulses. A It will recognize the echo of LiDAR B, rather than taking the echo of LiDAR B as its own echo.

[0092] However, in practical applications, when a laser in a certain channel CH1 of a laser array emits multiple laser pulses in succession, its coupled energy storage unit may still have residual charge. When a pre-charging unit charges the energy storage unit, and the energy storage unit continues to drive the laser in the next channel CH2 to emit light, according to the preset settings, the laser in channel CH2 should emit multiple pulses with very weak energy (e.g., 3 pulses). However, because there is residual charge in the energy storage unit, and the charge stored in the energy storage unit may even be more than the charge required to make the laser in CH2 emit light, the first pulse in the next series of pulses emitted by the laser in CH2 may have very high energy, possibly one to two times more energy than the subsequent pulses. As a result, the echo detection circuit cannot identify the echo signal of CH2.

[0093] Therefore, a discharge unit can also be set in the multi-pulse laser emitting circuit to discharge any residual charge in the energy storage unit before the pre-charging unit charges the energy storage unit.

[0094] In practice, since the high voltage required to generate laser light needs to be used for a pre-charging process of hundreds of nanoseconds, if it is necessary to realize that a laser can continuously emit multiple light pulses, it can be achieved through a multi-pulse laser driving circuit, wherein the pre-charging module can include multiple pre-charging units.

[0095] Furthermore, a lidar system may have multiple emission channels, each corresponding to a laser, and each channel emits a detection beam. For each emission channel, there will be different detection requirements, thus corresponding to different emission intensities. For example, for the channel in the middle beam, it may be desirable to detect farther, and correspondingly, a stronger light intensity is desired, while the channels on the sides would be the opposite.

[0096] To achieve, for example, the cyclic emission of multiple lasers in a lidar system, the optical emission module can be configured with one or more laser groups. Each laser group includes at least one laser branch, and each laser branch corresponds to a emission channel. Correspondingly, the energy storage module can include multiple energy storage units, with one energy storage unit configured for each laser or laser group. Similarly, each module in the laser emission driving circuit can adaptively configure multiple circuit units for different lasers or laser groups. Specifically, the driving module can include multiple driving units, each of which can be coupled to a corresponding laser branch. Each laser can perform single-pulse emission or multi-pulse emission.

[0097] To enable those skilled in the art to better understand and implement the embodiments of this specification, the following provides a detailed description through specific example circuit structures and their working principles.

[0098] Reference Figure 5 The diagram shows a specific example structure of a laser emitting circuit for lidar, wherein only one discharge unit B1 is provided, which is coupled to each pre-charging unit and each energy storage unit, and is adapted to discharge the coupled energy storage unit before each pre-charging unit charges the coupled energy storage unit.

[0099] First, refer to Figure 5 A detailed description is provided. The laser emitting circuit 50 includes multiple pre-charging units E1, E2, ..., Em, and multiple laser groups LD1, LD2, ..., LDn. Each laser group LD1, LD2, ..., LDn includes one or more parallel laser branches, and each laser branch is controlled by a corresponding drive switch S11, S12, ..., S1n.

[0100] As a specific example, such as Figure 5 The discharge unit B1 may include: a switch Mb, a resistor R, and a first diode Db coupled between the plurality of pre-charge units E1, E2, ..., Em, laser modules LD1, LD2, ..., LDn, energy storage units C1, C2, ..., Cn and ground. It is adapted to charge any one of the energy storage units C1, C2, ..., Cn from any one of the pre-charge units E1, E2, ..., Em, so that the laser coupled to the energy storage unit forms a discharge path before the first pulse in a series of pulses, thereby discharging the energy storage unit.

[0101] Taking the pre-charge unit E1 as a specific example, such as Figure 5 As shown, the circuit may include an inductor L1, with its first terminal coupled to an input voltage VIN. The second terminal of the inductor L1 is connected to the anode of a second diode D1 and the drain of a second switch M1. The cathode of the second diode D1 can be coupled to energy storage capacitors C1, C2, ..., Cn and laser arrays LD1, LD2, ..., LDn via switching units A1, A2, ..., An. The source of the second switch M1 is grounded, and its gate is turned on or off based on a received control signal gate1. When the second switch M1 is closed, the inductor L1 can be pre-charged. When switching unit A1 is closed and the second switch M1 is open, the inductor L1 can discharge to the energy storage unit C1.

[0102] In some embodiments of this specification, such as Figure 5As shown, the discharge unit B1 may include a resistor R, a first diode Db coupled to the resistor R, and a first switch Mb, wherein the drain of the first switch Mb is connected to the cathode of the diode Db, the source of the first switch Mb is grounded, the first switch Mb can be turned on based on the discharge signal BL input to the gate, and can form a discharge path between the energy storage capacitors C1, C2, ..., Cn and ground.

[0103] To simplify the control logic of the drive module, the laser emitting circuit 50 may also include a switching module, such as... Figure 5 As shown, the switching module may include multiple switching units A1, A2, ..., An. These switching units A1, A2, ..., An are respectively coupled between at least one pre-charging unit (e.g., one of pre-charging units E1, E2, ..., Em) and at least one laser group (e.g., at least one of laser groups LD1, LD2, ..., LDn), and are suitable for selecting and controlling the coupled laser group (e.g., at least one of laser groups LD1, LD2, ..., LDn). As a specific example, the switching units A1, A2, ..., An can be implemented using MOSFETs, for example, through third switches N1, N2, ..., Nn. Thus, the switching units A1, A2, ..., An and the energy storage capacitors C1, C2, ..., Cn correspond to the corresponding laser groups LD1, LD2, ..., LDn, respectively. The specific correspondence can be found in [reference needed]. Figure 5 For example, the switching unit may include an NMOS transistor. Taking the third switch N1 and the energy storage capacitor C1 as an example, the drain of the third switch N1 is connected to the output terminal of each of the plurality of pre-charge units, i.e. Figure 5 In each pre-charge unit, the cathode of the diode and the source of the third switch N1 are respectively connected to the laser group LD1 and the energy storage capacitor C1, as shown below. Figure 5 As shown, the third switch N1 is coupled between diode D1 and energy storage capacitor C1. Switch N1 can be turned on based on the gate gating control signals pl1, pl2, ..., pln.

[0104] More specifically, the plurality of third switches N1, N2, ..., Nn can each be independently controlled by the gating control signals pl1, pl2, ..., pln of their respective drivers, and configured so that only one of the third switches is allowed to be turned on at any given time. This allows one or more of the plurality of pre-charging units to charge the energy storage capacitor connected to the turned-on third switch, establishing a high voltage, and the charged energy storage capacitor drives the laser array connected to it. The turning on and off of the third switch N1 can only affect all the lasers in the laser array LD1.

[0105] When the third switch N1 is turned on, pre-charging can be performed through one of the multiple pre-charging units E1, E2, ..., Em (e.g., pre-charging unit E1). Specifically, by controlling the closure of one of the second switches M1, M2, ..., Mm (e.g., the second switch M1), the corresponding pre-charging unit E1, E2, ..., Em (e.g., pre-charging unit E1) can be turned on and store energy in an inductor (e.g., inductor L1), charging the energy storage capacitor C1 connected to the third switch N1, causing the energy storage capacitor C1 to output a high voltage. After the energy storage capacitor C1 is fully charged, by controlling the closure of one of the drive switches S11, S12, S13, S14, one of the lasers LD11, LD12, LD13, LD14 can be driven. Next, by controlling the next closing of the second switches M1, M2, ..., Mm (e.g., the second switch M2), the next pre-charging unit (e.g., the pre-charging unit E2) stores energy and charges the energy storage capacitor C1, outputting a high voltage. Then, by controlling the closing of one of the drive switches S11, S12, S13, S14 (e.g., drive switch S12), one of the lasers (which can be the same laser driven previously or a different laser) is driven to emit light.

[0106] Regarding the aforementioned signal crosstalk problem between different light-emitting channels, the embodiments in this specification continue to refer to... Figure 5 and combined Figure 7 The following is a detailed explanation of the voltage change process across the energy storage capacitor C1, based on the emission control timing of lasers LD11 and LD12 corresponding to two adjacent emission channels in laser group LD1.

[0107] First, during time period T0, the first switch Mb is closed, discharging the energy storage capacitor C1 through the discharge unit B1. Then, the first switch Mb is opened, and the second switch M1 is closed based on the control signal gate1. A path is formed between the input power terminal VIN, inductor L1, the second switch M1, and ground. The inductor L1 stores energy, and the voltage across the energy storage capacitor C1 remains constant. Next, the second switch M1 is opened, and switch N1 is closed, charging the energy storage capacitor C1 through the second diode D1 via inductor L1, increasing the voltage across the capacitor. Then, at time t1, based on the drive signal tr11, switch S11 is closed, and other drive switches S12, S13, and S14 are opened, forming a power-on loop between the energy storage capacitor C1, laser LD11, drive switch S11, and ground. The laser LD11 emits pulse 1. Because this discharge process is extremely fast, the high voltage on the energy storage capacitor C1 drops significantly instantaneously. Figure 7 The process of voltage gradually decreasing over time is not shown in the figure.

[0108] Assuming that at time t2, the pre-charging unit E2 has completed energy storage, the third switch N1 is closed while the second switch M2 is open. The inductor L2 in the pre-charging unit E2, due to its characteristic of maintaining current, will discharge through the second diode D2, switch N1, and energy storage unit C1, thereby charging the energy storage unit C1 and gradually building up a high voltage. At time t3, the high voltage on energy storage unit C1 is fully established. At this time, based on the drive signal tr11, the drive switch S11 is closed, and the other drive switches S12, S13, and S14 are opened, re-establishing a power loop between the energy storage capacitor C1, the laser LD11, the drive switch S11, and ground. The laser LD11 then emits pulse 2.

[0109] Similarly, assuming that the pre-charging unit Em has completed energy storage at time t4, the third switch N1 is closed while the switch Mm is open. The inductor Lm in the pre-charging unit Em, due to its characteristic of maintaining current, will discharge through the second diode Dm, the third switch Nn-1, and the energy storage unit C1, thereby charging the energy storage unit C1 and gradually building up a high voltage. At time t5, the high voltage on the energy storage unit C1 is established. At this time, based on the drive signal tr11, the drive switch S11 is closed, and the other drive switches S12, S13, and S14 are opened, forming another power-on loop between the energy storage capacitor C1, the laser LD11, the drive switch S11, and ground. The laser LD11 then emits pulse 3.

[0110] At time t1, the pre-charge unit E1 enters the pre-charge process, such as Figure 7 As shown, this process lasts for time period T1. Similarly, pre-charging unit E2 enters the pre-charging process after time t3, and pre-charging unit Em enters the pre-charging process after time t5. The pre-charging and energy storage time for each pre-charging unit may be the same, for example, T1, or they may be different.

[0111] After laser LD11 finishes emitting light, assuming the next light-emitting channel is laser LD12, the following describes the light emission control process for the corresponding channel of laser LD12.

[0112] Similar to the light-emitting channel corresponding to laser LD11, firstly, during time period T2, the first switch Mb is closed, discharging the energy storage capacitor C1 through the discharge unit B1. Then, the first switch Mb is opened, and the second switch M1 is closed based on the control signal gate1. A path is formed between the input voltage VIN, inductor L1, the second switch M1, and ground. The inductor L1 stores energy, and the voltage across the energy storage capacitor C1 remains constant. Next, the control switch M1 is opened, and the third switch N1 is closed, charging the energy storage capacitor C1 through the second diode D1 via inductor L1, increasing the voltage of the energy storage capacitor. Then, at time t6, based on the drive signal tr12, switch S12 is closed, and other drive switches S11, S13, and S14 are opened, forming a power-on loop between the energy storage capacitor C1, laser LD12, drive switch S12, and ground. The laser LD12 emits pulse 1. Because this discharge process is extremely fast, the high voltage on the energy storage capacitor C1 drops significantly instantaneously. Figure 7 The process of voltage gradually decreasing over time is not shown in the figure.

[0113] Assuming that at time t7, the pre-charging unit E2 has completed energy storage, the third switch N1 is closed while the second switch M2 is open. The inductor L2 in the pre-charging unit E2, due to its characteristic of maintaining current, will discharge through the second diode D2, switch N1, and energy storage unit C1, thereby charging the energy storage unit C1 and gradually building up a high voltage. At time t8, the high voltage on the energy storage unit C1 is established. At this time, based on the drive signal tr12, the drive switch S12 is closed, and the other drive switches S11, S13, and S14 are opened, re-establishing a power loop between the energy storage capacitor C1, the laser LD12, the drive switch S12, and ground. The laser LD12 then emits pulse 2.

[0114] Similarly, assuming that the pre-charging unit Em has completed energy storage at time t9, the third switch N1 is closed while the second switch Mm is open. The inductor Lm in the pre-charging unit Em, due to its characteristic of maintaining current, will discharge through the second diode Dm, switch Nn-1, and energy storage unit C1, thereby charging the energy storage unit C1 and gradually building up a high voltage. At time t10, the high voltage on the energy storage unit C1 is established. At this time, based on the drive signal tr12, the drive switch S12 is closed, and the other drive switches S11, S13, and S14 are opened, forming another power-on circuit between the energy storage capacitor C1, the laser LD11, the drive switch S11, and ground. The laser LD12 then emits pulse 3.

[0115] This process is repeated continuously, allowing each laser in the laser emitting circuit 50 to emit light sequentially. Before emitting the first pulse of a series of pulses, each laser first discharges the charge in the energy storage unit coupled to the laser through the discharge unit B1.

[0116] In practice, the discharge time T0 of the energy storage capacitor C1 before the laser LD11 emits light can be the same as or different from the discharge time T2 of the energy storage capacitor C1 before the laser LD12 emits light.

[0117] In practical implementation, if the switching unit uses an NMOS transistor, it is only necessary to ensure that the pre-charge unit is conducting when charging the energy storage unit coupled to it, while the energy storage unit can be in a closed state when discharging charge through the discharge unit. This is because the NMOS transistor contains a reverse body diode (not shown in the figure), and the electrical energy in the energy storage unit can be transferred to the discharge unit for discharge through the body diode in the NMOS transistor. Based on the selection control signals pl1, pl2, ..., pln of the driver, the NMOS transistor can only turn off the current from the pre-charge unit to the energy storage unit, but cannot block the reverse current from the energy storage unit to the discharge unit. During the discharge process, the switching unit can be approximated as a short circuit. Furthermore, the laser does not emit light during the discharge process of the energy storage unit, and the discharge time is independent of the encoding time, having been completed before the laser emits light.

[0118] Using the above embodiments, multiple energy storage units share a single discharge unit. Before each pre-charging unit charges the coupled energy storage unit, the coupled energy storage unit is discharged, which can save circuit area.

[0119] like Figure 6 The diagram shows a specific example structure of a laser emitting circuit for a lidar system. The laser emitting circuit 60 includes multiple pre-charging units E1, E2, ..., Em, laser modules LD1, LD2, ..., LDn, and energy storage units C1, C2, ..., Cn. Each laser module LD1, LD2, ..., LDn includes one or more parallel laser branches, and each laser branch is controlled by corresponding drive switches S11, S12, ..., S1n. Figure 5 The difference is that, Figure 6The discharge module used includes multiple discharge units, such as discharge units B1, B2, ..., Bn. Each discharge unit B1, B2, ..., Bn is coupled between an energy storage unit (at least one of energy storage units C1, C2, ..., Cn) and at least one pre-charging unit (at least one of pre-charging units E1, E2, ..., Em). This is suitable for discharging the coupled energy storage unit before the pre-charging unit charges it. In this way, during the circumambulation of laser light, before emitting the first pulse of multiple laser pulses, each laser group can discharge excess electrical energy in its corresponding energy storage unit through the discharge unit coupled to it.

[0120] Understandable Figure 5 and Figure 6 The laser emitting circuit shown is for illustrative purposes only. The specific examples in this specification are not intended to limit the specific structure of the laser emitting circuit to which this invention applies, and can be implemented according to application requirements. For example, multiple lasers can be driven to emit light simultaneously by a single drive switch, or multiple laser groups can be controlled by a third switch.

[0121] In specific implementation, in order to achieve more precise control of the discharge process, reduce the proportion of the discharge process in the entire laser emitting circuit operation process, and improve the luminous efficiency of the laser emitting circuit and the corresponding target detection efficiency, the laser emitting circuit may also include a voltage detection module (not shown). The voltage detection module may include multiple voltage detection units (not shown). The voltage detection unit is adapted to detect the voltage across the coupled energy storage unit, and when the detected voltage is less than a preset threshold, it triggers the first switch Mb in the discharge unit to close, so that the energy storage unit stops discharging.

[0122] In practice, it has been found that after each laser pulse is emitted, a relatively fixed charge remains in the energy storage unit due to parasitic effects. The greater the deviation between the input voltage VIN and the laser's turn-on voltage, the more residual energy remains. Therefore, in the embodiments of this specification, the input voltage VIN at the power input terminal can be set as the laser's turn-on voltage. This improves the consistency of multiple pulses emitted continuously by a single laser, further enhancing the detection performance of the lidar. For semiconductor lasers, the turn-on voltage refers to the voltage drop when the forward voltage drop of its PN junction remains essentially constant after a forward voltage is applied and it is turned on. It should be noted that the turn-on voltage may vary for semiconductor lasers of different materials and models.

[0123] This specification also provides an embodiment of a lidar, such as... Figure 8 The lidar 80 shown only illustrates the laser emitting circuit control system, which may specifically include a laser emitting circuit 81 and a controller 82, wherein:

[0124] The laser emitting circuit 81 may specifically include an optical emitting module 811, an energy storage module 812, a driving module 813, a pre-charging module 814, and a discharge module 815, etc.

[0125] The controller 82 is adapted to output control signals to the pre-charge module 814, the drive module 813 and the discharge module 815 in the laser emitting circuit 81, respectively, to control the light emitting module 811 to emit light, wherein: before outputting a pre-charge trigger signal to the pre-charge module 814 to charge the energy storage module 812, the energy storage module is discharged.

[0126] The specific module structure, circuit connections and signal relationships between modules, and working principle of the laser emitting circuit 81 can be found in the aforementioned embodiments, and will not be elaborated here.

[0127] The control timing of the specific control signals issued by the controller 82 can be found in the foregoing embodiments. In specific implementations, the controller can be coupled to each module through matched driving devices and output control signals.

[0128] In specific implementations, the controller can be implemented using a microcontroller, FPGA chip, digital logic chip, mixed-signal chip, or processor chip capable of executing computer instructions. The embodiments in this specification do not limit its specific structure.

[0129] In practical applications, LiDAR can be used in multiple fields. Specifically, LiDAR has become a core sensor device in many fields such as autonomous driving, mapping, smart cities / V2X, robotics, and security. Figure 9 The unmanned vehicle 90 shown includes a vehicle body 91 and a lidar 92 located on top of the vehicle body 91.

[0130] It is understood that, in specific implementations, depending on the application requirements, LiDAR can be set in different locations such as the front, rear, or side of the vehicle, or multiple LiDARs can be set in different locations on a single vehicle. The embodiments in this specification do not limit the application scenarios or specific application schemes of LiDAR.

[0131] This specification also provides a laser emission control method, which can be used to control an optical emission module to emit a detection beam for detecting a target. The optical emission module is coupled to both a drive module and an energy storage module, and the energy storage module is coupled to a pre-charge module via a discharge module. (Refer to...) Figure 10 The control method includes:

[0132] S101, before the energy storage module is charged, a discharge signal is output to the discharge module to cause the energy storage module to discharge.

[0133] As an optional step, when the voltage across the energy storage module is detected to be less than a preset threshold, a discharge stop signal can be output to the discharge module to stop the energy storage module from discharging.

[0134] S102, output a pre-charge signal to the pre-charge module so that the pre-charge module stores electrical energy.

[0135] S103, output a drive signal to the drive module to cause the energy storage module to discharge and drive the light emitting module to emit light.

[0136] In a specific implementation, multiple driving signals can be continuously output to the driving module to cause the energy storage module to discharge and drive the optical emitting module to continuously emit multiple detection beams.

[0137] In specific implementation, the laser emission control method described above can be used to control the laser emission circuit introduced in the foregoing embodiments. For the specific control process of the aforementioned laser emission circuit, please refer to the foregoing specific embodiments and corresponding figures.

[0138] It should be noted that, for ease of distinction, the terms "first," "second," and "third" are used in this specification to differentiate between different objects. For example, diodes contained in different modules or functional units are distinguished as "first diode," "second diode," etc. The terms "first," "second," etc., do not indicate differences in quantity, order, or priority, nor are they technical terms with specific meanings. In the embodiments of this specification, they are only used to distinguish different modules and components.

[0139] While the embodiments of the present invention have been disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A laser emitting circuit for lidar, characterized in that, include: An optical emitting module configured to emit a detection beam for detecting a target, the optical emitting module including at least one laser group, the laser group including multiple lasers; An energy storage module is coupled to the optical emitting module. The energy storage module includes multiple energy storage units, each of which is coupled to a corresponding laser group. A driving module is adapted to drive the light emitting module to emit light. The driving module includes multiple driving units, each of which is coupled to a corresponding laser. In response to a laser emission trigger signal, the driving module selects the energy storage module and the corresponding laser. A pre-charging module, coupled to the energy storage module, is used to charge the energy storage module. The pre-charging module includes multiple pre-charging units, each of which is coupled to a power input terminal and at least one energy storage unit. The discharge module is coupled to the pre-charge module and the energy storage module respectively, and is adapted to discharge the energy storage module before the pre-charge module charges the energy storage module; A switching module comprising multiple switching units coupled between at least one pre-charging unit and the laser group, adapted to perform gating control on the laser group.

2. The laser emitting circuit according to claim 1, characterized in that, The laser is adapted to continuously emit multiple laser pulses; The discharge module is adapted to discharge the energy storage unit coupled to the laser before the laser continuously emits the first laser pulse among the plurality of laser pulses.

3. The laser emitting circuit according to claim 1, characterized in that, The discharge module includes: a discharge unit coupled to each pre-charge unit and each energy storage unit, adapted to discharge the coupled energy storage unit before each pre-charge unit charges the coupled energy storage unit.

4. The laser emitting circuit according to claim 1, characterized in that, The discharge module includes multiple discharge units, each discharge unit being coupled between an energy storage unit and at least one pre-charge unit, and is adapted to discharge the coupled energy storage unit before the pre-charge unit charges the coupled energy storage unit.

5. The laser emitting circuit according to claim 3 or 4, characterized in that, The discharge unit includes a first switch, a resistor, and a first diode coupled between the pre-charging unit, the laser group, the energy storage unit, and ground, and is adapted to form a discharge path to discharge the energy storage unit before the pre-charging unit charges the energy storage unit.

6. The laser emitting circuit according to claim 3 or 4, characterized in that, Also includes: The voltage detection module includes multiple voltage detection units, which are adapted to detect the voltage across the coupled energy storage unit and stop the energy storage unit from discharging when the detected voltage is less than a preset threshold.

7. The laser emitting circuit according to any one of claims 1 to 4, characterized in that, The pre-charging unit includes: An inductor, the first end of which is coupled to the power input terminal; The second diode has its anode coupled to the second end of the inductor and its cathode coupled to the energy storage unit and the laser assembly. The second switch is coupled between the second terminal of the inductor and ground.

8. The laser emitting circuit according to any one of claims 1 to 4, characterized in that, The voltage at the power input terminal is the turn-on voltage of the laser.

9. A lidar, characterized in that, include: The laser emitting circuit according to any one of claims 1 to 8; The controller is adapted to output control signals to the pre-charging module, the driving module and the discharge module respectively to control the light emitting module to emit light, wherein: before outputting a pre-charging trigger signal to the pre-charging module to charge the energy storage module, the energy storage module is discharged.

10. The lidar according to claim 9, characterized in that, The optical emitting module includes at least one laser group, and the laser group includes multiple lasers; The controller is adapted to discharge the energy storage module coupled to the laser before outputting a laser emission trigger signal to the drive module to trigger the laser to continuously emit multiple pulses.

11. A laser emission control method, characterized in that, This control method is used to control an optical emitting module to emit a detection beam for detecting a target. The optical emitting module is coupled to a driving module and an energy storage module, respectively. The energy storage module is coupled to a pre-charging module via a discharge module. A switching module is also coupled between the pre-charging module and the optical emitting module. Specifically: the optical emitting module includes at least one laser group, which includes multiple lasers; the energy storage module includes multiple energy storage units, each coupled to a corresponding laser group; the driving module includes multiple driving units, each coupled to a corresponding laser, and selects the energy storage module and the corresponding laser in response to a laser emission trigger signal; the pre-charging module includes multiple pre-charging units, each coupled to a power input terminal and at least one energy storage unit; the switching module includes multiple switching units, each coupled between at least one pre-charging unit and the laser group, suitable for selecting and controlling the laser group; the control method includes: Before the energy storage module is charged, a discharge signal is output to the discharge module to cause the energy storage module to discharge. A pre-charge signal is output to the pre-charge module, enabling the pre-charge module to store electrical energy; A drive signal is output to the drive module to drive the light emitting module to emit light.

12. The laser emission control method according to claim 11, characterized in that, The step of outputting a drive signal to the drive module to cause the energy storage module to discharge and drive the laser to emit light includes: Multiple driving signals are continuously output to the driving module, causing the energy storage module to discharge and driving the optical emitting module to continuously emit multiple detection beams.

13. The laser emission control method according to claim 11 or 12, characterized in that, Also includes: When the voltage across the energy storage module is detected to be less than a preset threshold, a discharge stop signal is output to the discharge module, causing the energy storage module to stop discharging.

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