Laser emission circuit and laser radar

Abstract

The invention provides a laser emission circuit and a laser radar, and the laser emission circuit comprises a laser, a first switching circuit, a second switching circuit and a main control circuit, when the laser emission circuit is triggered, the main control circuit firstly controls the first switching circuit to be switched on and pulled down according to the pulse width of a first pulse control signal; after pull-down, the voltage of the positive power supply end begins to rise, then a first second pulse control signal is output, the laser is driven by a small first preset voltage to emit a weak laser pulse, when an echo signal is detected, the object to be detected is determined to be a high-reflectivity object, the laser is not driven to emit light at the moment, and when the echo signal is not detected, the laser is driven to emit light at the moment. And determining that the high-reflectivity object is not detected, then outputting the second pulse signal again, driving the laser to emit the laser pulse of the strong light at the second preset voltage of the large voltage, carrying out normal distance measurement, reducing the ghosting phenomenon caused by the irradiation of the high-reflectivity object by the strong light, and improving the distance measurement accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of lidar, and particularly relates to a laser emission circuit and a lidar. Background Art

[0002] One of the core components of a lidar is a semiconductor laser. Generally, a pulsed drive circuit for a semiconductor laser switches a high voltage through a switching device to generate a large current with a narrow pulse width, thereby driving the semiconductor laser to emit light.

[0003] In the existing pulsed drive circuit scheme for semiconductor lasers, during the ranging process of a lidar, for a high-reflectivity object at a short distance, in the lidar point cloud, a "ghost" phenomenon will occur. The "ghost" phenomenon refers to that when a real high-reflectivity object enters any area of the lidar field of view, in addition to imaging at the actual position of the high-reflectivity object, the output point cloud may also image a shape and size similar to a "ghost" in other directions.

[0004] Therefore, in the traditional technical solution, there is a problem of ghosting caused by high reflection at short distances. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser emission circuit, aiming to solve the problem of ghosting caused by high reflection at short distances in traditional lidars.

[0006] A first aspect of an embodiment of the present invention provides a laser emission circuit. The laser emission circuit is disposed opposite to a laser receiving circuit for performing optoelectronic conversion. The laser emission circuit includes:

[0007] A laser;

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

[0009] A second switching circuit, which is connected in parallel with the first switching circuit after being connected in series with the laser. The second switching circuit is configured to be triggered to conduct and turn off by a second pulse control signal, and drive the laser to emit a laser pulse with a corresponding power magnitude by the voltage of the positive power supply terminal when conducting;

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

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

[0012] When it is determined that the echo signal is received, stop outputting the second pulse control signal;

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

[0014] Optionally, the first switching circuit includes a first electronic switch tube 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 end of the first electronic switch tube constitutes the control end 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, and the anode and the cathode of the diode respectively constitute the first end and the second end of the resistive element.

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

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

[0020] Optionally, the main control circuit includes:

[0021] A voltage detection circuit, the signal input end 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 at the positive power supply terminal and output a voltage detection signal;

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

[0023] Output the first pulse control signal at a first preset time point, and at the end of the falling edge of the first pulse control signal, output the enable signal and obtain the voltage detection signal. When it is detected that the voltage of the positive power supply terminal reaches a first preset voltage, output the second pulse control signal, and determine whether an echo signal is received through the laser receiving circuit;

[0024] When it is determined that an echo signal is received, stop outputting the second pulse control signal;

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

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

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

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

[0029] The controller is configured to:

[0030] Output the first pulse control signal when the timer counts to a first preset time point, and output the second pulse control signal when the timer counts to a second preset time point, and determine whether an echo signal is received through the laser receiving circuit;

[0031] When it is determined that an echo signal is received, stop outputting the second pulse control signal;

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

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

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

[0035] A third switch circuit, which is connected to the charging and energy storage circuit, the positive power supply terminal, and the main control circuit. The third switch circuit is configured to be triggered to conduct under a discharge signal and output the stored energy of the charging and energy storage circuit to the positive power supply terminal.

[0036] In the second aspect of the embodiments of the present invention, a lidar is proposed, which includes a laser receiving circuit and the laser emitting circuit as described above, and the laser receiving circuit is disposed opposite to the laser emitting circuit.

[0037] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: The above-mentioned laser emitting circuit includes a laser, a first switch circuit, a second switch circuit, and a main control circuit. When the laser emitting circuit is triggered, the main control circuit first controls the first switch circuit to conduct and pull down with the pulse width of the first pulse control signal. After the pull-down, the voltage at the positive power supply terminal starts to rise, and then the first second pulse control signal is output to drive the laser to emit a weak light laser pulse with a first preset voltage of a small 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 light laser pulse with a second preset voltage of a large voltage for normal ranging, reducing the ghosting phenomenon caused by strong light irradiating high-reflectivity objects and improving the ranging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 It is the first structural schematic diagram of the laser emitting circuit provided by the embodiments of the present invention;

[0040] Figure 2 It is the timing schematic diagram of the pulse control signal provided by the embodiments of the present invention;

[0041] Figure 3 It is the waveform schematic diagram of the driving voltage and current of the laser provided by the embodiments of the present invention;

[0042] Figure 4 It is the first circuit schematic diagram of the laser emitting circuit provided by the embodiments of the present invention;

[0043] Figure 5 It is the second circuit schematic diagram of the laser emitting circuit provided by the embodiments of the present invention;

[0044] Figure 6 It is the second structural schematic diagram of the laser emitting circuit provided by the embodiments of the present invention;

[0045] Figure 7Schematic diagram of the voltage detection circuit provided by an embodiment of the present invention;

[0046] Figure 8 Schematic diagram of the third structure of the laser emission circuit provided by an embodiment of the present invention;

[0047] Figure 9 Schematic diagram of the fourth structure of the laser emission circuit provided by an embodiment of the present invention;

[0048] Figure 10 Schematic diagram of the structure of the lidar provided by an embodiment of the present invention. Detailed implementation manners

[0049] In order to make the technical problems, technical solutions and beneficial effects to be solved by 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 only used to explain the present invention and are not used to limit the present invention.

[0050] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0051] In a first aspect of an embodiment of the present invention, a laser emission circuit 100 is proposed. The laser emission circuit 100 is disposed opposite to a laser reception circuit 200 for performing photoelectric conversion. A laser 110 is provided in the laser emission circuit 100, and the laser 110 is configured to emit laser pulses at corresponding angles according to corresponding time sequences.

[0052] The laser reception circuit 200 is configured to receive the laser pulses emitted by the laser emission circuit 100 and perform photoelectric and detection conversions into echo signals.

[0053] Among them, in order to reduce the ghosting phenomenon caused by strong light irradiating high-reflectivity objects and improve the ranging accuracy, as Figure 1 shown, in this embodiment, the laser emission circuit 100 includes:

[0054] A laser 110;

[0055] A first switch circuit 120. The first switch circuit 120 is connected in series between the positive power supply terminal and the ground. The first switch circuit 120 is configured to be triggered to conduct and turn off by a first pulse control signal Ctr1, and pull down the voltage HV of the positive power supply terminal when conducting;

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

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

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

[0059] When it is determined that the echo signal is received, stop outputting the second pulse control signal Ctr2;

[0060] And when it is determined that the echo signal is not received, output the second pulse control signal Ctr2 again at the third preset time point T3 when the voltage HV at the positive power supply terminal reaches the second preset voltage, where the second preset voltage is greater than the first preset voltage.

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

[0062] When the laser emitting circuit 100 works, it selects to emit one laser pulse or two laser pulses according to the received echo signal. The main control circuit 140 first outputs the first pulse control signal Ctr1 to the first switch circuit 120 at the first preset time point T1, as Figure 2 and Figure 3As shown, at this time, the first switch 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 switch circuit 120 is turned off, and the voltage HV at the positive power supply terminal starts 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 switch circuit 130 to be turned 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 detect objects with high reflectivity at close range. When there is an object with high reflectivity in the target field of view, the object with high reflectivity reflects the laser pulses. When the reflected laser pulses are 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 determines that there is an object with high reflectivity in the target field of view. At this time, the main control circuit 140 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 the strong light irradiating an object with high reflectivity at close range, and thus avoiding the ghost phenomenon in the lidar point cloud.

[0063] Meanwhile, the main control circuit 140 determines the distance information and reflectivity of the object with high reflectivity based on the echo signal received at this time.

[0064] Moreover, when the main control circuit 140 does not receive an echo signal during this period, it determines that there is no object with high reflectivity in 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 switch circuit 130 to be turned on again. The second preset voltage drives the laser 110 to emit laser pulses. The current of the laser 110 is a large current, and the laser 110 emits strong laser pulses with high power. The strong laser pulses detect non-high-reflectivity objects to achieve normal ranging operation. The main control circuit 140 determines the distance information and reflectivity of the non-high-reflectivity object based on the echo signal received at this time.

[0065] Among them, the first switch circuit 120 and the second switch circuit 130 can adopt switch devices or circuits with controlled on-off.

[0066] Among them, 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 realize the potential drop at high pulse widths. A corresponding pull-down circuit can be adopted. In an alternative embodiment, optionally, as Figure 4 and Figure 5 shown, the first switching circuit 120 includes a first electronic switching tube 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 switching tube Q1, the second end of the first electronic switching tube Q1 is grounded, and the control end of the first electronic switching tube Q1 constitutes the control end of the first switching circuit 120.

[0069] In this embodiment, the first electronic switching tube Q1 is controlled to conduct when receiving a high pulse of the first pulse control signal Ctr1. The resistive element and the first electronic switching tube Q1 form a pull-down circuit and 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, the longer the conduction time of the first switching circuit 120, and 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, the shorter the conduction time of the first switching circuit 120, and the smaller the pulse width of the first pulse control signal Ctr1. The pulse width of the first pulse control signal Ctr1 is specifically determined according to the resistance value of the resistive element.

[0070] Among them, the first electronic switching tube Q1 is triggered to conduct at a high level and triggered to turn off at a low level. Switch tube structures such as NPN triodes and NMOS tubes can be selected.

[0071] The resistive element can be selected as a structure such as a resistor with a corresponding impedance. As Figure 4 shown, in an alternative embodiment, the resistive element includes a first resistor R1. The first end and the second end of the first resistor R1 respectively constitute the first end and the second end of the resistive element. The first resistor R1 constitutes a pull-down resistor and pulls down the voltage HV at the positive power supply terminal to zero potential when the first electronic switching tube Q1 conducts. The resistance value of the first resistor R1 can be designed correspondingly, for example, 0 to 10 Ω.

[0072] As Figure 5 shown, in another alternative embodiment, the resistive element includes a diode D1. The anode and the cathode of the diode D1 respectively constitute the first end and the second end of the resistive element.

[0073] In this embodiment, the impedance of the diode D1 is small. When the first electronic switch Q1 is turned on, the diode D1 quickly pulls down the voltage HV of 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 switch 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 respectively constitute the first terminal, the second terminal, and the control terminal of the second switch circuit 130.

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

[0077] The second electronic switch Q2 is triggered to turn on when receiving a high level, and is triggered to turn off when receiving a low level. According to the conduction mode, the second electronic switch Q2 can select switch tube structures such as NPN transistors and NMOS transistors.

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

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

[0080] A voltage detection circuit 142, the signal input terminal of the voltage detection circuit 142 is connected to the positive power supply terminal. The 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 a voltage detection signal V1;

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

[0082] Output the first pulse control signal Ctr1 at the first preset time point T1, and when the falling edge of the first pulse control signal Ctr1 ends, output an enable signal and obtain the voltage detection signal V1. When it is detected that the voltage HV of the positive power supply terminal reaches the first preset voltage, output the second pulse control signal Ctr2, and determine whether a return signal is received through the laser receiving circuit 200;

[0083] When it is determined that a return signal is received, stop outputting the second pulse control signal Ctr2;

[0084] And when it is determined that no echo signal is received, when it is detected that the voltage HV of the positive power supply terminal reaches 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 according to the magnitude of the voltage HV of the positive power supply terminal. The controller 141 first outputs the first pulse control signal Ctr1 to the first switch circuit 120 at the first preset time point T1. At this time, the first switch circuit 120 is turned on and pulls down the voltage HV of the positive power supply terminal. After the first pulse control signal Ctr1 ends, the first switch circuit 120 is turned off, and the controller 141 enables the voltage detection circuit 142 to start the voltage detection work. The voltage detection circuit 142 outputs a voltage detection signal V1 to the controller 141, and the voltage HV of the positive power supply terminal starts to recover and gradually rises. When the voltage HV of the positive power supply terminal rises to the 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 switch circuit 130 to be turned on. The first preset voltage drives the laser 110 to emit a laser pulse. The current flowing through the laser 110 is a small current, and the laser 110 emits a weak laser pulse with a small power. The weak laser pulse can only detect objects with a high reflectivity at a short distance. When there is an object with a high reflectivity in the target field of view, the object with a high reflectivity 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 is determined that there is an object with a high reflectivity 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 the strong laser pulse stops, thereby avoiding the high-intensity echo signal generated by the strong light irradiating an object with a high reflectivity at a short distance, and thus avoiding the ghost phenomenon in the lidar point cloud.

[0086] At the same time, the controller 141 determines the distance information and reflectivity of the object with a high reflectivity according to the echo signal received at this time.

[0087] And when the controller 141 does not receive an echo signal during this period, it is determined that there is no object with a high reflectivity in 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 of the positive power supply terminal rises to the second preset voltage. The high pulse of the second pulse control signal Ctr2 controls the second switch circuit 130 to be turned on again. The second preset voltage drives the laser 110 to emit a laser pulse. The current of the laser 110 is a large current, and the laser 110 emits a strong laser pulse with a large power. The strong laser pulse detects non-high-reflectivity objects to realize normal ranging work. The controller 141 determines the distance information and reflectivity of the non-high-reflectivity object according to the echo signal received at this time.

[0088] Among them, the voltage detection circuit 142 can adopt a resistor voltage division circuit and a switching circuit, or a voltage detection chip and other structures. Optionally, as Figure 7 shown, the voltage detection circuit 142 includes a second resistor R2, a third resistor R3, and a third electronic switching tube Q3;

[0089] The second resistor R2, the third electronic switching tube Q3, and the third resistor R3 are connected in series in sequence and then connected in parallel between the positive power supply terminal and the ground. The first end or the second end of the third electronic switching tube Q3 constitutes the signal output end of the voltage detection circuit 142, and the control end of the third electronic switching tube Q3 constitutes the enable end 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 switching tube Q3. The third electronic switching tube Q3 is turned on, and the second resistor R2 and the third resistor R3 form a resistor voltage division circuit. The first end or the second end of the third electronic switching tube Q3 constitutes 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 according to the magnitude of the voltage detection signal V1. At the same time, after the ranging ends, the controller 141 is enabled again to control the third electronic switching tube Q3 to turn off, and the voltage detection circuit 142 stops working.

[0091] The enable signal can be set correspondingly according to the type of the third electronic switching tube Q3. The third electronic switching tube Q3 can adopt switching tube structures such as a triode and a MOS tube.

[0092] In another alternative embodiment, the main control circuit 140 obtains the voltage HV pull-down and then rising curve of the positive power supply terminal before ranging, determines the time points and time intervals corresponding to the first preset voltage and the second preset voltage according to the rising curve, and outputs the second pulse control signal Ctr2 according to the time points and time intervals.

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

[0094] The controller 141 is configured to:

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

[0096] When it is determined that an echo signal is received, stop outputting the second pulse control signal Ctr2;

[0097] and when it is determined that the echo signal is not received, the second pulse control signal Ctr2 is output again when the timer 143 counts up to the third preset time point T3.

[0098] In this embodiment, the controller 141 first outputs the first pulse control signal Ctr1 to the first switching circuit 120 at the first preset time point T1. As Figure 2 and Figure 3 shown, at this time, the first switching circuit 120 is turned on, and the voltage HV of the positive power supply terminal is pulled down. 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 of the positive power supply terminal starts to recover and gradually rises. When the timer 143 counts up 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 be turned 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 detect high-reflectivity objects at close range. When there is a high-reflectivity object in the target field of view, the high-reflectivity object reflects the laser pulses. When the reflected laser pulses are 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 is determined 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 the strong light irradiating the high-reflectivity object at close range, and thus avoiding the ghost phenomenon in the lidar point cloud.

[0099] At the same time, the controller 141 determines the distance information and reflectivity of the high-reflectivity object according to the echo signal received at this time.

[0100] And when the controller 141 does not receive the echo signal during this period, it is determined that there is no high-reflectivity object in 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 counted up. The high pulse of the second pulse control signal Ctr2 controls the second switching circuit 130 to be turned on again. The second preset voltage drives the laser 110 to emit laser pulses. The current of the laser 110 is a large current, and the laser 110 emits strong laser pulses with high power. The strong laser pulses detect non-high-reflectivity objects to realize normal ranging work. The controller 141 determines the distance information and reflectivity of the non-high-reflectivity object according to the echo signal received at this time.

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

[0102] In an alternative embodiment, as Figure 9 shown, the laser emission circuit 100 further includes:

[0103] A charging and energy storage circuit 150, which is connected to the main control circuit 140 and is configured to charge and store energy under a charging signal;

[0104] A third switch circuit 160, which is connected to the charging and energy storage circuit 150, the positive power supply terminal, and the main control circuit 140. The third switch circuit 160 is configured to be triggered to conduct under a discharge signal and output the stored energy of the charging and energy storage circuit 150 to the positive power supply terminal.

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

[0106] Among them, the charging and energy storage circuit 150 can be composed of a diode D1, a switching tube, an inductor, and a capacitor. The diode D1, the switching tube, and the inductor form a boost circuit or a buck circuit, and the capacitor constitutes an energy storage unit. After the power supply is converted by the boost circuit or the buck circuit, the capacitor is charged and stored with energy and discharges after the third switch circuit 160 is turned on.

[0107] The third switch circuit 160 can adopt a switching device with controlled on-off, such as a triode, a MOS tube, etc., 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 above-mentioned laser emission circuit 100 includes a laser 110, a first switch circuit 120, a second switch circuit 130, and a main control circuit 140. When the laser emission circuit 100 is triggered, the main control circuit 140 first controls the first switch circuit 120 to conduct and pull down with the pulse width of the first pulse control signal Ctr1. After the pull-down, the voltage HV at the positive power supply terminal starts to rise, and then the first second pulse control signal Ctr2 is output to drive the laser 110 to emit a weak-light laser pulse with a first preset voltage of a small voltage. When an echo signal is detected, it is determined that the object to be measured 1 is a high-reflectivity object, and 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, and then the second pulse signal is output again to drive the laser 110 to emit a strong-light laser pulse with a second preset voltage of a large voltage for normal ranging, reducing the ghosting phenomenon caused by strong light irradiating a high-reflectivity object and improving the ranging accuracy.

[0109] The present invention also provides a lidar, as Figure 10 shown. The lidar includes a laser receiving circuit 200 and a laser emission circuit 100. The specific structure of the laser emission circuit 100 refers to the above-mentioned embodiments. Since this lidar adopts all the technical solutions of the above-mentioned all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be elaborated here one by one.

[0110] The laser emission circuit 100 is correspondingly arranged with the laser receiving circuit 200. The laser emission circuit 100 includes a corresponding laser 110, a first switch circuit 120, and a second switch circuit 130. The laser 110 is used to emit laser pulses when powered. The second switch circuit 130 is connected to the laser 110 and is used to be controlled to conduct and output a driving power supply to the laser 110, and control the laser 110 to emit laser pulses at a corresponding angle according to the corresponding time sequence.

[0111] The laser receiving circuit 200 is used to receive the laser pulses emitted by the laser emission circuit 100 and perform detection and conversion into pulse echo signals. The pulse echo signals are output to the processing circuit, and the processing circuit determines the distance information and reflectivity of the object to be measured 1 according to the pulse echo signals.

[0112] The laser receiving circuit 200 can select corresponding photodetectors and signal processing circuits. The photodetector is used to realize the photoelectric conversion of laser pulses to echo signals. At the same time, the signal processing circuit is used to realize signal isolation, amplification, detection and other processes, and corresponding isolation circuits, amplification circuits, detection circuits, etc. can be selected according to the signal processing method.

[0113] The lidar may further include a control module, which is configured to drive the laser emission circuit 100 to emit laser pulses, and at the same time receive the echo signal output by the laser reception circuit 200, and determine the flight time of the echo signal, as well as the distance information and reflectivity according to the echo pulse width and the arrival time of the pulse of the echo signal.

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

[0115] The above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A laser emitting circuit, wherein the laser emitting circuit is arranged opposite to a laser receiving circuit for performing photoelectric conversion, characterized in that: The laser emission circuit comprises: Lasers; A first switch circuit, wherein the first switch circuit is connected in series between the positive power supply terminal and the ground, and the first switch circuit is configured to be turned on and off by a first pulse control signal, and to pull down the voltage of the positive power supply terminal when turned on; a second switch circuit, the second switch circuit being connected in series with the laser and then connected in parallel with the first switch circuit, the second switch circuit being configured to be turned 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 at the positive power supply terminal when turned on; A main control circuit, wherein the main control circuit is connected to the first switch circuit, the second switch circuit and the laser receiving circuit respectively, and the main control circuit is configured as follows: outputting the first pulse control signal at a first preset time point, and outputting the second pulse control signal at a second preset time point when the voltage of the positive power supply terminal reaches the first preset voltage, and determining whether an echo signal is received through the laser receiving circuit; When it is determined that the echo signal is received, stopping outputting the second pulse control signal; 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 of the positive power supply terminal reaches a second preset voltage, wherein the second preset voltage is greater than the first preset voltage.

2. The laser emitting circuit according to claim 1, characterized in that: The first switch circuit includes a first electronic switch tube and a resistive element; The first end of the resistive element is connected to the positive power supply end, 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 end of the first electronic switch tube constitutes the control end of the first switch circuit.

3. The laser emitting circuit according to claim 2, characterized in that: The resistive element comprises a first resistor, wherein 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 emitting circuit according to claim 2, characterized in that: The resistive element comprises a diode, an anode and a cathode of the diode respectively constitute a first end and a second end of the resistive element.

5. The laser emitting circuit according to claim 2, characterized in that: The second switch circuit includes a second electronic switch tube; The first end, the second end and the control end of the second electronic switch tube respectively constitute the first end, the second end and the control end of the second switch circuit.

6. The laser emitting circuit according to claim 1, characterized in that: The main control circuit comprises: A voltage detection circuit, wherein a 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; A controller, wherein the controller is respectively connected to the signal output end of the voltage detection circuit, the first switch circuit, the second switch circuit and the laser receiving circuit, and the controller is configured as follows: Output the first pulse control signal at a first preset time point, and when the falling edge of the first pulse control signal ends, output the enable signal and obtain the voltage detection signal, output the second pulse control signal when it is detected that the voltage of the positive power supply terminal reaches the first preset voltage, and determine whether the echo signal is received through the laser receiving circuit; When it is determined that the echo signal is received, stopping outputting the second pulse control signal; 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 terminal reaches a second preset voltage.

7. The laser emitting circuit according to claim 6, characterized in that: The voltage detection circuit includes 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 in sequence and then in parallel between the positive power supply terminal and the ground. The first end or the second end of the third electronic switch tube constitutes the signal output end of the voltage detection circuit, and the control end of the third electronic switch tube constitutes the enable end of the voltage detection circuit.

8. The laser emitting circuit according to claim 1, characterized in that: The main control circuit includes a timer and a controller; The controller is configured to: outputting the first pulse control signal when the timer reaches a first preset time point, and outputting the second pulse control signal when the timer reaches a second preset time point, and determining whether an echo signal is received by the laser receiving circuit; When it is determined that the echo signal is received, stopping outputting the second pulse control signal; And when it is determined that the echo signal is not received, the second pulse control signal is output again when the timer reaches a third preset time point.

9. The laser emitting circuit according to claim 1, characterized in that: The laser emission circuit also includes: A charging energy storage circuit, the charging energy storage circuit is connected to the main control circuit and is configured to be charged and stored by a charging signal; A third switch circuit is connected to the charging energy storage circuit, the positive power supply terminal and the main control circuit. The third switch circuit is configured to be turned on by a discharge signal and output the energy storage quantity of the charging energy storage circuit to the positive power supply terminal.

10. A laser radar, characterized in that: It comprises a laser receiving circuit and a laser emitting circuit as claimed in any one of claims 1 to 9, wherein the laser receiving circuit is arranged opposite to the laser emitting circuit.

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