Laser emission circuit and lidar

Abstract

The application provides a laser emission circuit and a laser radar, wherein the laser emission circuit comprises a laser, a first switch circuit, a second switch circuit and a master control circuit; when the laser emission circuit is triggered, the master control circuit first controls the first switch circuit to be turned on and pulled down in the pulse width of a first pulse control signal; after being pulled down, the voltage of a positive power supply end starts to rise; then a first second pulse control signal is outputted, a laser is driven to emit a weak light laser pulse by a first preset voltage with a small voltage, when a return signal is detected, it is determined that a to-be-measured object is a high reflectivity object, at this time, the laser is not driven to emit light any more; when the return signal is not detected, it is determined that the high reflectivity object is not detected; then a second pulse signal is outputted again, the laser is driven to emit a strong light laser pulse by a second preset voltage with a large voltage, normal ranging is performed, the ghost phenomenon caused by strong light irradiation on the high reflectivity object is reduced, and the ranging precision is improved.

Description

Technical Field

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

[0002] One of the core components of lidar is the semiconductor laser. Generally, a semiconductor laser is driven by a pulsed drive circuit, which uses switching devices to switch high voltage to generate a large current with a narrow pulse width, thereby driving the semiconductor laser to emit light.

[0003] Existing semiconductor laser pulsed drive circuit solutions can produce a "ghosting" phenomenon in the lidar point cloud when dealing with high reflectivity objects at close range during lidar ranging. The "ghosting" phenomenon refers to the fact that when a real high reflectivity object enters any area of ​​the lidar's field of view, the output point cloud may not only have an image at the actual location of the high reflectivity object, but may also have an image of a similar shape and size at other locations.

[0004] Therefore, traditional technical solutions suffer from ghosting issues due to high reflection at close range. Summary of the Invention

[0005] The purpose of this invention is to provide a laser emitting circuit that aims to solve the problem of ghosting caused by high reflection at close range in traditional lidar.

[0006] A first aspect of this invention provides a laser emitting circuit, wherein the laser emitting circuit is disposed opposite to a laser receiving circuit for photoelectric conversion, the laser emitting circuit comprising:

[0007] Laser;

[0008] A first switching circuit is connected in series between the positive power supply terminal and ground. The first switching circuit is configured to be triggered to turn on and off by a first pulse control signal, and to pull down the voltage of the positive power supply terminal when it is on.

[0009] The second switching circuit is connected in series with the laser and then in parallel with the first switching circuit. The second switching circuit is configured to be triggered to turn on and off by a second pulse control signal, and to drive the laser to emit a laser pulse of corresponding power with the voltage of the positive power supply terminal when it is turned on.

[0010] The main control circuit is connected to the first switching circuit, the second switching circuit, and the laser receiving circuit, respectively. The main control circuit is configured as follows:

[0011] The first pulse control signal is output at a first preset time point, and the second pulse control signal is output at a second preset time point when the voltage at the positive power supply terminal reaches the first preset voltage, and the laser receiving circuit determines whether an echo signal is received.

[0012] When an echo signal is received, the output of the second pulse control signal is stopped.

[0013] And when it is determined that the echo signal is not received, the second pulse control signal is output again at a third preset time point when the voltage at the positive power supply terminal reaches the second preset voltage, wherein the second preset voltage is greater than the first preset voltage.

[0014] Optionally, the first switching circuit includes a first electronic switching transistor and a resistive element;

[0015] The first end of the resistive element is connected to the positive power supply terminal, the second end of the resistive element is connected to the first end of the first electronic switch tube, the second end of the first electronic switch tube is grounded, and the control terminal of the first electronic switch tube constitutes the control terminal of the first switching circuit.

[0016] Optionally, the resistive element includes a first resistor, and the first end and the second end of the first resistor respectively constitute the first end and the second end of the resistive element.

[0017] Optionally, the resistive element includes a diode, wherein the anode and cathode of the diode constitute the first and second terminals of the resistive element, respectively.

[0018] Optionally, the second switching circuit includes a second electronic switching transistor;

[0019] The first terminal, the second terminal, and the control terminal of the second electronic switch tube respectively constitute the first terminal, the second terminal, and the control terminal of the second switching circuit.

[0020] Optionally, the main control circuit includes:

[0021] A voltage detection circuit, wherein the signal input terminal of the voltage detection circuit is connected to the positive power supply terminal, and the voltage detection circuit is configured to be triggered by an enable signal to detect the voltage of the positive power supply terminal and output a voltage detection signal;

[0022] The controller is connected to the signal output terminal of the voltage detection circuit, the first switching circuit, the second switching circuit, and the laser receiving circuit, respectively. The controller is configured to:

[0023] The first pulse control signal is output at the first preset time point, and the enable signal is output and the voltage detection signal is acquired when the falling edge of the first pulse control signal ends. When the voltage of the positive power supply terminal reaches the first preset voltage, the second pulse control signal is output, and the laser receiving circuit determines whether an echo signal is received.

[0024] When an echo signal is received, the output of the second pulse control signal is stopped.

[0025] And when it is determined that the echo signal is not received, the second pulse control signal is output again when the voltage at the positive power supply terminal is detected to reach the second preset voltage.

[0026] Optionally, the voltage detection circuit includes a second resistor, a third resistor, and a third electronic switch.

[0027] The second resistor, the third electronic switch, and the third resistor are connected in series and then in parallel between the positive power supply terminal and ground. The first or second terminal of the third electronic switch constitutes the signal output terminal of the voltage detection circuit, and the control terminal of the third electronic switch constitutes the enable terminal of the voltage detection circuit.

[0028] Optionally, the main control circuit includes a timer and a controller;

[0029] The controller is configured as follows:

[0030] The first pulse control signal is output when the timer reaches a first preset time point, and the second pulse control signal is output when the timer reaches a second preset time point, and the laser receiving circuit determines whether an echo signal is received.

[0031] When an echo signal is received, the output of the second pulse control signal is stopped.

[0032] And when it is determined that the echo signal is not received, the second pulse control signal is output again when the timer reaches the third preset time point.

[0033] Optionally, the laser emitting circuit further includes:

[0034] A charging energy storage circuit, which is connected to the main control circuit and is configured to charge and store energy upon receiving a charging signal;

[0035] The third switching circuit is connected to the charging energy storage circuit, the positive power supply terminal, and the main control circuit. The third switching circuit is configured to be triggered and turned on by a discharge signal, and outputs the stored energy of the charging energy storage circuit to the positive power supply terminal.

[0036] A second aspect of the present invention provides a lidar, including a laser receiving circuit and a laser emitting circuit as described above, wherein the laser receiving circuit and the laser emitting circuit are disposed opposite to each other.

[0037] The beneficial effects of this invention embodiment compared with the prior art are as follows: The laser emitting circuit mentioned above includes a laser, a first switching circuit, a second switching circuit, and a main control circuit. When the laser emitting circuit is triggered, the main control circuit first controls the first switching circuit to conduct with the pulse width of the first pulse control signal and pulls it down. After the pull-down, the voltage at the positive power supply terminal begins to rise, and then the first second pulse control signal is output to drive the laser to emit a weak laser pulse with a small first preset voltage. When an echo signal is detected, it is determined that the object to be measured is a high reflectivity object, and at this time the laser is no longer driven to emit light. When no echo signal is detected, it is determined that no high reflectivity object is detected, and then the second pulse signal is output again to drive the laser to emit a strong laser pulse with a large second preset voltage for normal ranging, reducing the ghosting phenomenon caused by strong light irradiating high reflectivity objects and improving the ranging accuracy. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of a first structure of a laser emitting circuit provided in an embodiment of the present invention;

[0040] Figure 2 A timing diagram of the pulse control signal provided in an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the driving voltage and current of a laser provided for an embodiment of the present invention;

[0042] Figure 4 This is a first circuit diagram of a laser emitting circuit provided in an embodiment of the present invention;

[0043] Figure 5 This is a second circuit diagram of a laser emitting circuit provided in an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of a second structure of the laser emitting circuit provided in an embodiment of the present invention;

[0045] Figure 7A circuit diagram of a voltage detection circuit provided in an embodiment of the present invention;

[0046] Figure 8 This is a schematic diagram of a third structure of the laser emitting circuit provided in an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of a fourth structure of the laser emitting circuit provided in an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of the structure of a lidar provided in an embodiment of the present invention. Detailed Implementation

[0049] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0050] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0051] A first aspect of the present invention provides a laser emitting circuit 100, which is arranged opposite to a laser receiving circuit 200 for photoelectric conversion. The laser emitting circuit 100 includes a laser 110, which emits laser pulses at corresponding angles according to a corresponding timing sequence.

[0052] The laser receiving circuit 200 is used to receive the laser pulse emitted by the laser emitting circuit 100 and convert it into an echo signal through photoelectric detection.

[0053] In order to reduce ghosting caused by strong light illuminating highly reflective objects and improve ranging accuracy, such as... Figure 1 As shown, in this embodiment, the laser emitting circuit 100 includes:

[0054] Laser 110;

[0055] The first switching circuit 120 is connected in series between the positive power supply terminal and ground. The first switching circuit 120 is configured to be triggered to turn on and off by the first pulse control signal Ctr1, and to pull down the voltage HV of the positive power supply terminal when it is turned on.

[0056] The second switching circuit 130 is connected in series with the laser 110 and then in parallel with the first switching circuit 120. The second switching circuit 130 is configured to be triggered to turn on and off by the second pulse control signal Ctr2, and to drive the laser 110 to emit laser pulses of corresponding power with the voltage HV at the positive power supply terminal when it is turned on.

[0057] The main control circuit 140 is connected to the first switching circuit 120, the second switching circuit 130, and the laser receiving circuit 200, respectively. The main control circuit 140 is configured as follows:

[0058] At the first preset time point T1, a first pulse control signal Ctr1 is output, and at the second preset time point T2, when the voltage HV at the positive power supply terminal reaches the first preset voltage, a second pulse control signal Ctr2 is output, and the laser receiving circuit 200 determines whether an echo signal is received.

[0059] When it is confirmed that an echo signal has been received, the second pulse control signal Ctr2 is cut off.

[0060] And when it is determined that no echo signal is received, at the third preset time point T3, when the voltage HV at the positive power supply terminal reaches the second preset voltage, the second pulse control signal Ctr2 is output again, wherein the second preset voltage is greater than the first preset voltage.

[0061] In this embodiment, the laser 110 is a semiconductor laser LD, which can be any type of bar laser, semiconductor quantum well laser, DFB and DBR laser, surface-emitting laser, etc.

[0062] When the laser emitting circuit 100 is working, it selects to emit one or two laser pulses based on the received echo signal. The main control circuit 140 first outputs a first pulse control signal Ctr1 to the first switching circuit 120 at a first preset time point T1. Figure 2 and Figure 3As shown, at this time, the first switching circuit 120 is turned on and pulls down the voltage HV at the positive power supply terminal. After the first pulse control signal Ctr1 ends, the first switching circuit 120 is turned off, and the voltage HV at the positive power supply terminal begins to recover and gradually rises. When the voltage HV at the positive power supply terminal rises to the first preset voltage at the second preset time point T2, the main control circuit 140 outputs the second pulse control signal Ctr2. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on, and the first preset voltage drives the laser 110 to emit laser pulses. The current flowing through the laser 110 is a small current, and the laser 110 emits weak laser pulses with low power. The weak laser pulses can only detect... When a highly reflective object is detected at close range, it reflects a laser pulse. When the reflected laser pulse is input to the laser receiving circuit 200, the laser receiving circuit 200 performs photoelectric conversion and outputs an echo signal to the main control circuit 140. When the main control circuit 140 receives the echo signal during this period, it confirms the presence of a highly reflective object in the target's field of view. At this time, the main control circuit 140 stops outputting the second pulse control signal Ctr2, the ranging ends, and the emission of strong laser pulses stops. This avoids the high-intensity echo signal generated by strong light illuminating a highly reflective object at close range, thus avoiding ghosting in the lidar point cloud.

[0063] At the same time, the main control circuit 140 determines the distance information and reflectivity of the highly reflective object based on the echo signal received at this time.

[0064] Furthermore, when the main control circuit 140 does not receive an echo signal during this period, it determines that there is no high reflectivity object within the target field of view. At this time, the main control circuit 140 selects to output the second pulse control signal Ctr2 again at the set third preset time point T3 and when the voltage HV at the positive power supply terminal rises to the second preset voltage. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on again. The second preset voltage drives the laser 110 to emit laser pulses. The laser 110 has a large current and emits strong laser pulses with high power. The strong laser pulses detect non-high reflectivity objects and realize normal ranging operation. The main control circuit 140 determines the distance information and reflectivity of non-high reflectivity objects based on the echo signal received at this time.

[0065] The first switching circuit 120 and the second switching circuit 130 may employ switching devices or circuits with controlled on / off states.

[0066] The magnitudes of the first preset voltage and the second preset voltage can be set according to requirements. For example, the first preset voltage is 3.3V, the second preset voltage is 12V, the first preset time point T1 is ahead of the second preset time point T2, and the second preset time point T2 is ahead of the third preset time point T3.

[0067] The first switching circuit 120 is used to implement a potential pull-down during high pulse width. A corresponding pull-down circuit can be used. In an optional embodiment, optionally, such as... Figure 4 and Figure 5 As shown, the first switching circuit 120 includes a first electronic switch Q1 and a resistive element;

[0068] The first end of the resistive element is connected to the positive power supply terminal, the second end of the resistive element is connected to the first end of the first electronic switch Q1, the second end of the first electronic switch Q1 is grounded, and the control terminal of the first electronic switch Q1 constitutes the control terminal of the first switching circuit 120.

[0069] In this embodiment, the first electronic switch Q1 is turned on under control when it receives a high pulse of the first pulse control signal Ctr1. The resistive element and the first electronic switch Q1 form a pull-down circuit to pull down the voltage HV at the positive power supply terminal to zero potential. The resistance value of the resistive element determines the pulse width of the first pulse control signal Ctr1. The larger the resistance value, the longer the time to pull down to zero potential, and the longer the conduction time of the first switching circuit 120, the larger the pulse width of the first pulse control signal Ctr1. The smaller the resistance value, the shorter the time to pull down to zero potential, and the shorter the conduction time of the first switching circuit 120, the smaller the pulse width of the first pulse control signal Ctr1. The specific pulse width of the first pulse control signal Ctr1 is determined according to the resistance value of the resistive element.

[0070] Among them, the first electronic switch Q1 is triggered to turn on when the level is high and triggered to turn off when the level is low. It can be selected from switch structures such as NPN transistors and NMOS transistors.

[0071] Resistive components can be selected from structures such as resistors with corresponding impedances, such as... Figure 4 As shown, in an optional embodiment, the resistive element includes a first resistor R1. The first end and the second end of the first resistor R1 constitute the first end and the second end of the resistive element, respectively. The first resistor R1 constitutes a pull-down resistor, which pulls down the voltage HV at the positive power supply terminal to zero potential when the first electronic switch Q1 is turned on. The resistance value of the first resistor R1 can be designed accordingly, for example, 0 to 10Ω.

[0072] like Figure 5 As shown, in another optional embodiment, the resistive element includes a diode D1, the anode and cathode of the diode D1 forming the first and second terminals of the resistive element, respectively.

[0073] In this embodiment, the impedance of diode D1 is relatively small. When the first electronic switch Q1 is turned on, diode D1 quickly pulls down the voltage HV at the positive power supply terminal to zero potential, and the pulse width of the corresponding first pulse control signal Ctr1 is small.

[0074] Optionally, the second switching circuit 130 includes a second electronic switch Q2;

[0075] The first terminal, the second terminal, and the control terminal of the second electronic switch Q2 constitute the first terminal, the second terminal, and the control terminal of the second switch circuit 130, respectively.

[0076] In this embodiment, the second electronic switch Q2 is triggered to turn on when it receives the high pulse width of the second pulse control signal Ctr2, and triggered to turn off when it receives the low level. When it is turned on, the laser 110 is driven to emit weak or strong laser pulses with a small or large voltage at the positive power supply terminal.

[0077] The second electronic switch Q2 is triggered to turn on when it receives a high level and to turn off when it receives a low level. Depending on the turn-on method, the second electronic switch Q2 can be selected from switching transistor structures such as NPN transistors and NMOS transistors.

[0078] The main control circuit 140 can output pulse control signals according to the time point and also according to the voltage magnitude.

[0079] In an alternative embodiment, such as Figure 6 As shown, the main control circuit 140 includes:

[0080] Voltage detection circuit 142, the signal input terminal of voltage detection circuit 142 is connected to the positive power supply terminal, voltage detection circuit 142 is configured to be triggered by an enable signal to detect the voltage HV of the positive power supply terminal and output voltage detection signal V1;

[0081] Controller 141 is connected to the signal output terminal of voltage detection circuit 142, first switching circuit 120, second switching circuit 130, and laser receiving circuit 200, respectively. Controller 141 is configured to:

[0082] At the first preset time point T1, a first pulse control signal Ctr1 is output, and at the end of the falling edge of the first pulse control signal Ctr1, an enable signal is output and a voltage detection signal V1 is acquired. When the voltage HV at the positive power supply terminal is detected to reach the first preset voltage, a second pulse control signal Ctr2 is output, and the laser receiving circuit 200 determines whether an echo signal is received.

[0083] When it is confirmed that an echo signal has been received, the second pulse control signal Ctr2 is cut off.

[0084] And when it is determined that no echo signal is received, when the voltage HV at the positive power supply terminal is detected to reach the second preset voltage, the second pulse control signal Ctr2 is output again.

[0085] In this embodiment, the controller 141 determines the output time of the second pulse control signal Ctr2 based on the magnitude of the voltage HV at the positive power supply terminal. The controller 141 first outputs the first pulse control signal Ctr1 to the first switching circuit 120 at a first preset time point T1. At this time, the first switching circuit 120 is turned on and pulls down the voltage HV at the positive power supply terminal. After the first pulse control signal Ctr1 ends, the first switching circuit 120 is turned off, and the controller 141 enables the voltage detection circuit 142 to start voltage detection. The voltage detection circuit 142 outputs a voltage detection signal V1 to the controller 141, and the voltage HV at the positive power supply terminal begins to recover and gradually rises. When the voltage HV at the positive power supply terminal rises to a first preset voltage, the controller 141 outputs the second pulse control signal Ctr2. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on, and the first preset voltage... Assume that the voltage-driven laser 110 emits laser pulses, and the current flowing through the laser 110 is small. The laser 110 emits weak laser pulses with low power. The weak laser pulses can only detect objects with high reflectivity at close range. When there is a high reflectivity object in the target field of view, the high reflectivity object reflects the laser pulse. When the reflected laser pulse is input to the laser receiving circuit 200, the laser receiving circuit 200 performs photoelectric conversion and outputs an echo signal to the main control circuit 140. When the controller 141 receives the echo signal during this period, it determines that there is a high reflectivity object in the target field of view. At this time, the controller 141 no longer outputs the second pulse control signal Ctr2, the ranging ends, and the emission of strong laser pulses stops, thereby avoiding the high-intensity echo signal generated by strong light illuminating a high reflectivity object at close range, thus avoiding the ghosting phenomenon in the lidar point cloud.

[0086] At the same time, the controller 141 determines the distance information and reflectivity of the highly reflective object based on the echo signal received at this time.

[0087] Furthermore, when the controller 141 does not receive an echo signal during this period, it determines that there is no high reflectivity object within the target field of view. At this time, the controller 141 selects to output the second pulse control signal Ctr2 again when the voltage HV at the positive power supply terminal rises to the second preset voltage. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on again. The second preset voltage drives the laser 110 to emit laser pulses. The laser 110 has a large current and emits strong laser pulses with high power. The strong laser pulses detect non-high reflectivity objects and realize normal ranging operation. The controller 141 determines the distance information and reflectivity of non-high reflectivity objects based on the echo signal received at this time.

[0088] The voltage detection circuit 142 can employ a resistor divider circuit and a switching circuit, or a voltage detection chip, etc., optionally, as follows: Figure 7 As shown, the voltage detection circuit 142 includes a second resistor R2, a third resistor R3, and a third electronic switch Q3;

[0089] The second resistor R2, the third electronic switch Q3, and the third resistor R3 are connected in series and then in parallel between the positive power supply terminal and ground. The first or second terminal of the third electronic switch Q3 constitutes the signal output terminal of the voltage detection circuit 142, and the control terminal of the third electronic switch Q3 constitutes the enable terminal of the voltage detection circuit 142.

[0090] In this embodiment, after the falling edge of the first pulse control signal Ctr1 ends, the controller 141 outputs an enable signal to the third electronic switch Q3, turning on the third electronic switch Q3. The second resistor R2 and the third resistor R3 form a voltage divider circuit. The first or second terminal of the third electronic switch Q3 forms a voltage node and outputs a voltage detection signal V1 to the controller 141. The controller 141 determines the output of the second pulse control signal Ctr2 based on the magnitude of the voltage detection signal V1. At the same time, after the ranging ends, the controller 141 enables the signal again, turns off the third electronic switch Q3, and the voltage detection circuit 142 stops working.

[0091] The enable signal can be set according to the type of the third electronic switch Q3, which can be a transistor, MOSFET or other switching transistor structure.

[0092] In another optional embodiment, the main control circuit 140 obtains the voltage HV at the positive power supply terminal after pull-down and rise curve before ranging, determines the time point and time interval corresponding to the first preset voltage and the second preset voltage according to the rise curve, and outputs the second pulse control signal Ctr2 according to the time point and time interval.

[0093] like Figure 8 As shown, optionally, the main control circuit 140 includes a timer 143 and a controller 141;

[0094] Controller 141 is configured as follows:

[0095] When the timer 143 counts to the first preset time point T1, the first pulse control signal Ctr1 is output, and when the timer 143 counts to the second preset time point T2, the second pulse control signal Ctr2 is output, and the laser receiving circuit 200 determines whether an echo signal is received.

[0096] When it is confirmed that an echo signal has been received, the second pulse control signal Ctr2 is cut off.

[0097] And when it is determined that no echo signal is received, the second pulse control signal Ctr2 is output again when the timer 143 counts to the third preset time point T3.

[0098] In this embodiment, the controller 141 first outputs a first pulse control signal Ctr1 to the first switching circuit 120 at a first preset time point T1, such as... Figure 2 and Figure 3 As shown, at this time, the first switching circuit 120 is turned on and pulls down the voltage HV at the positive power supply terminal. The timer 143 starts timing. After the first pulse control signal Ctr1 ends, the first switching circuit 120 is turned off, and the voltage HV at the positive power supply terminal begins to recover and gradually rises. When the timer 143 counts to the second preset time point T2, the controller 141 outputs the second pulse control signal Ctr2. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on. The first preset voltage drives the laser 110 to emit laser pulses. The current flowing through the laser 110 is a small current, and the laser 110 emits weak laser pulses with low power. The weak laser pulses can only... When a high-reflectivity object is detected at close range, it reflects a laser pulse. When the reflected laser pulse is input to the laser receiving circuit 200, the laser receiving circuit 200 performs photoelectric conversion and outputs an echo signal to the controller 141. When the controller 141 receives the echo signal during this period, it determines that a high-reflectivity object exists in the target field of view. At this time, the controller 141 no longer outputs the second pulse control signal Ctr2, the ranging ends, and the emission of strong laser pulses stops. This avoids the high-intensity echo signal generated by strong light illuminating a high-reflectivity object at close range, thus avoiding ghosting in the lidar point cloud.

[0099] At the same time, the controller 141 determines the distance information and reflectivity of the highly reflective object based on the echo signal received at this time.

[0100] Furthermore, when the controller 141 does not receive an echo signal during this period, it determines that there is no high reflectivity object within the target field of view. At this time, the controller 141 selects to output the second pulse control signal Ctr2 again at the third preset time point T3 when the timing is reached. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to turn on again. The second preset voltage drives the laser 110 to emit laser pulses. The laser 110 has a large current and emits strong laser pulses with high power. The strong laser pulses detect non-high reflectivity objects and realize normal ranging operation. The controller 141 determines the distance information and reflectivity of the non-high reflectivity object based on the echo signal received at this time.

[0101] The positive voltage at the positive power supply terminal can be provided by the power module or by another energy storage unit, and the specific source is not limited.

[0102] In an alternative embodiment, such as Figure 9 As shown, the laser emitting circuit 100 also includes:

[0103] The charging energy storage circuit 150 is connected to the main control circuit 140 and is configured to charge and store energy upon receiving a charging signal.

[0104] The third switching circuit 160 is connected to the charging and energy storage circuit 150, the positive power supply terminal, and the main control circuit 140. The third switching circuit 160 is configured to be triggered and turned on by a discharge signal, and outputs the stored energy of the charging and energy storage circuit 150 to the positive power supply terminal.

[0105] In this embodiment, before the laser emitting circuit 100 emits a laser pulse, the main control circuit 140 outputs a charging signal to the charging and energy storage circuit 150, which charges and stores energy. At the same time, the main control circuit 140 outputs a discharge signal to the third switching circuit 160, which discharges to the power supply terminal so that the voltage HV at the positive power supply terminal reaches the peak voltage. The peak voltage can be a second preset voltage or a third preset voltage that is greater than the second preset voltage.

[0106] The charging and energy storage circuit 150 can be composed of diode D1, switching transistor, inductor and capacitor. Diode D1, switching transistor and inductor form a boost circuit or buck circuit, and capacitor forms an energy storage unit. After the boost circuit or buck circuit performs power conversion, it charges and stores energy in the capacitor, and discharges it after the third switching circuit 160 is turned on.

[0107] The third switching circuit 160 can use a switching device with controlled on / off switching, such as a transistor or MOSFET, and the specific structure is not limited.

[0108] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: The laser emitting circuit 100 mentioned above includes a laser 110, a first switching circuit 120, a second switching circuit 130, and a main control circuit 140. When the laser emitting circuit 100 is triggered, the main control circuit 140 first controls the first switching circuit 120 to conduct with the pulse width of the first pulse control signal Ctr1 and pulls it down. After the pull-down, the voltage HV at the positive power supply terminal begins to rise. Then, the first second pulse control signal Ctr2 is output to drive the laser 110 to emit weak laser pulses with a small voltage first preset voltage. When an echo signal is detected, it is determined that the object to be measured 1 is a high reflectivity object. At this time, the laser 110 is no longer driven to emit light. When no echo signal is detected, it is determined that no high reflectivity object is detected. Then, the second pulse signal is output again to drive the laser 110 to emit strong laser pulses with a large voltage second preset voltage for normal ranging, reducing the ghosting phenomenon caused by strong light irradiating high reflectivity objects and improving the ranging accuracy.

[0109] This invention also proposes a lidar, such as Figure 10 As shown, the lidar includes a laser receiving circuit 200 and a laser emitting circuit 100. The specific structure of the laser emitting circuit 100 is as described in the above embodiments. Since this lidar adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0110] The laser emitting circuit 100 is configured to correspond to the laser receiving circuit 200. The laser emitting circuit 100 includes a corresponding laser 110, a first switching circuit 120 and a second switching circuit 130. The laser 110 is used to receive power and emit laser pulses. The second switching circuit 130 is connected to the laser 110 and is used to control the laser to conduct and output driving power to the laser 110, and control the laser 110 to emit laser pulses at the corresponding angle according to the corresponding timing sequence.

[0111] The laser receiving circuit 200 is used to receive the laser pulse emitted by the laser emitting circuit 100, and convert it into a pulse echo signal. The pulse echo signal is output to the processing circuit, which determines the distance information and reflectivity of the object under test 1 based on the pulse echo signal.

[0112] The laser receiving circuit 200 can be equipped with a corresponding photodetector and signal processing circuit. The photodetector is used to realize the photoelectric conversion of laser pulse to echo signal. At the same time, the signal processing circuit is used to realize signal isolation, amplification, detection and other processing. Depending on the signal processing method, isolation circuit, amplification circuit, detection circuit, etc. can be selected accordingly.

[0113] The lidar may also include a control module, which drives the laser emitting circuit 100 to emit laser pulses and simultaneously receives the echo signal output by the laser receiving circuit 200. Based on the echo pulse width and pulse arrival time of the echo signal, the flight time of the echo signal, as well as distance information and reflectivity, are determined.

[0114] The control module can share the same processor with the main control circuit 140 in the laser emitting circuit 100, and output drive signals to drive the laser emitting circuit 100 to emit laser pulses. At the same time, it receives echo signals, obtains the echo pulse width and pulse arrival time, and then determines the flight time of the echo signal, as well as distance information and reflectivity.

[0115] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A laser emitting circuit, wherein the laser emitting circuit is disposed opposite to a laser receiving circuit for photoelectric conversion, characterized in that, The laser emission circuit comprises: a laser; a first switch circuit connected in series between a positive power supply end and a ground, configured to be triggered on and off by a first pulse control signal and to pull down the voltage of the positive power supply end when turned on; a second switch circuit connected in parallel with the first switch circuit after being connected in series with the laser, configured to be triggered on and off by a second pulse control signal and to drive the laser to emit a laser pulse of a corresponding power size when turned on; a master control circuit connected with the first switch circuit, the second switch circuit and a laser receiving circuit, configured to: output the first pulse control signal at a first preset time point and output the second pulse control signal when the voltage of the positive power supply end reaches a first preset voltage at a second preset time point, and determine whether a return signal is received through the laser receiving circuit; stop outputting the second pulse control signal when it is determined that the return signal is received; and output the second pulse control signal again when it is determined that the return signal is not received, at a third preset time point when the voltage of the positive power supply end reaches a second preset voltage, wherein the second preset voltage is greater than the first preset voltage.

2. The laser firing circuit of claim 1, wherein, The first switch circuit comprises a first electronic switch tube and a resistive element; a first end of the resistive element is connected with the positive power supply end, a second end of the resistive element is connected with a first end of the first electronic switch tube, a second end of the first electronic switch tube is grounded, and a control end of the first electronic switch tube constitutes a control end of the first switch circuit.

3. The laser firing circuit of claim 2, wherein, The resistive element comprises a first resistor, and a first end and a second end of the first resistor constitute a first end and a second end of the resistive element, respectively.

4. The laser firing circuit of claim 2, wherein, The resistive element comprises a diode, and an anode and a cathode of the diode constitute a first end and a second end of the resistive element, respectively.

5. The laser firing circuit of claim 2, wherein, The second switch circuit comprises a second electronic switch tube; a first end, a second end and a control end of the second electronic switch tube constitute a first end, a second end and a control end of the second switch circuit, respectively.

6. The laser firing circuit of claim 1, wherein, The master control circuit comprises: a voltage detection circuit, a signal input end of which is connected with the positive power supply end, configured to detect the voltage of the positive power supply end and output a voltage detection signal when triggered by an enable signal; a controller connected with a signal output end of the voltage detection circuit, the first switch circuit, the second switch circuit and the laser receiving circuit, configured to: output the first pulse control signal at a first preset time point, output the enable signal and acquire the voltage detection signal when the first pulse control signal ends at a falling edge, output the second pulse control signal when it is detected that the voltage of the positive power supply end reaches a first preset voltage, and determine whether a return signal is received through the laser receiving circuit; stop outputting the second pulse control signal when it is determined that the return signal is received; and when it is determined that the echo signal is not received, the second pulse control signal is output again when it is detected that the voltage of the positive power supply end reaches a second preset voltage.

7. The laser firing circuit of claim 6, wherein, The voltage detection circuit comprises a second resistor, a third resistor and a third electronic switch tube; The second resistor, the third electronic switch tube and the third resistor are connected in series and then connected in parallel between the positive power supply end and the ground, a first end or a second end of the third electronic switch tube constitutes a signal output end of the voltage detection circuit, and a control end of the third electronic switch tube constitutes an enable end of the voltage detection circuit.

8. The laser firing circuit of claim 1, wherein, The main control circuit comprises a timer and a controller. The controller is configured to: output the first pulse control signal when a first preset time point is timed by the timer, and output the second pulse control signal when a second preset time point is timed by the timer, and determine whether an echo signal is received by the laser receiving circuit; when it is determined that the echo signal is received, the output of the second pulse control signal is cut off; and when it is determined that the echo signal is not received, the second pulse control signal is output again when a third preset time point is timed by the timer.

9. The laser firing circuit of claim 1, wherein, The laser emitting circuit further comprises: a charging and energy storage circuit, which is connected with the main control circuit and is configured to be charged and store energy by a charging signal; a third switch circuit, which is connected with the charging and energy storage circuit, the positive power supply end and the main control circuit, and is configured to be triggered to be turned on by a discharging signal and output the energy storage capacity of the charging and energy storage circuit to the positive power supply end.

10. A lidar, comprising: The laser receiving circuit and the laser emitting circuit as claimed in any one of claims 1-9 are included, and the laser receiving circuit is arranged opposite to the laser emitting circuit.

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