Constant current emission circuit and lidar
By controlling the charging and discharging process of the energy storage element through a constant current power adjustable module and control circuit, the problem of laser mis-emission was solved, the reliability and accuracy of the lidar were improved, the circuit structure was simplified, and energy loss was reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUTENG INNOVATION TECHNOLOGY CO LTD
- Filing Date
- 2023-09-04
- Publication Date
- 2026-06-09
Smart Images
Figure CN122178744A_ABST
Abstract
Description
[0001] This application is a divisional application. The original application has the application number 202311138862.6 and the filing date is September 4, 2023. The entire contents of the original application are incorporated herein by reference. Technical Field
[0002] This application relates to the field of lidar technology, and in particular to a constant current transmitting circuit and lidar. Background Technology
[0003] In related technologies, a switch control module is placed between the constant voltage power supply and the laser to adjust the driving voltage provided by the constant voltage power supply to the laser. However, when charging by the constant voltage power supply, the charging current is infinitely large, which may exceed the current threshold required for the laser to emit light, causing the laser to emit light erratically. Summary of the Invention
[0004] This application provides a constant current emitting circuit and a lidar. The constant current emitting circuit can provide a constant current to the energy storage element, avoiding the problem of accidental emission of the laser and ensuring the reliability and accuracy of the laser emitted by the laser.
[0005] In a first aspect, embodiments of this application provide a constant current emission circuit, including a constant current power adjustable module and a constant voltage emission module; the constant current power adjustable module includes an energy storage element, the input terminal of the constant current power adjustable module is used to connect to the emission power supply with the output power supply voltage, so as to charge the energy storage element with the power supply voltage, the constant current power adjustable module is used to provide a constant current to the energy storage element, and to adjust the amount of energy stored in the energy storage element; the constant voltage emission module includes a laser, the laser is connected to the energy storage element, the laser is used to emit laser light when the energy storage element releases energy, and different energies stored in the energy storage element correspond to different laser emission powers.
[0006] The constant current power adjustable module provided in this application includes an energy storage element, a first control circuit, and a second control circuit. By controlling the conduction state and conduction time of the first and second control circuits, the constant current emitting circuit can enable the laser to emit lasers of different powers based on the power supply voltage. The first control circuit ensures that the charging current flowing into the energy storage element is constant, thereby guaranteeing the stability of the current connected to the energy storage element. This avoids damage to the laser connected in parallel with the energy storage element due to large current surges and prevents the laser from emitting light erroneously, ensuring the reliability of the laser emitted by the constant current emitting circuit. Furthermore, the second control circuit has a fast switching response speed, ensuring the overall reliability of the constant current emitting circuit and making it suitable for different lidar and detection scenarios. The constant current emitting circuit in this application does not require additional charging elements and boost circuits, resulting in a simple overall structure. Moreover, the constant current emitting circuit does not have a boost process, leading to low energy loss.
[0007] In one possible design, the constant current power adjustable module further includes: a first control circuit and a second control circuit; one end of the first control circuit is connected to the transmitting power supply, and the other end is connected to the energy storage element; one end of the second control circuit is connected to the second end of the energy storage element, and the other end is grounded; wherein, when the energy storage element is charging, both the first control circuit and the second control circuit are turned on and the on-time is controllable, so as to charge the energy storage element through the transmitting power supply and control the amount of energy stored in the energy storage element, and the current flowing through the first control circuit and into the energy storage element is a constant current; when the energy storage element releases energy, at least the first control circuit is turned off.
[0008] Based on the aforementioned optional method, the first control circuit can ensure that the current flowing through it and into the energy storage element is constant. This allows the constant current power adjustable module to not only maintain a constant charging current during the charging phase, preventing damage to the energy storage element, but also to adjust the amount of energy stored in the element. This ensures the reliability and accuracy of the laser's emitted laser, and consequently, the reliability and accuracy of the lidar detection using this constant current emission circuit.
[0009] In one possible design, the first control circuit includes: a first high-side switch, the drain of which is connected to the transmitting power supply, the source of which is connected to the first end of the energy storage element, and the controlled end of which is connected to the power control signal.
[0010] Based on the above-mentioned optional method, a large voltage difference exists between the energy storage element and the transmitting power supply, thereby causing the first high-side switch to operate in the saturation region. In this way, the current flowing through the first high-side switch and to the energy storage element is a constant current, ensuring the reliability of the laser during the charging phase.
[0011] In one possible design, the first control circuit includes a first switch connected in series between the transmitting power supply and a first terminal of the energy storage element.
[0012] Based on the above optional methods, the charging state of the energy storage element and the amount of energy stored in the energy storage element can be precisely controlled by controlling the conduction state and conduction time of the first switch, thereby ensuring the reliability of laser emission.
[0013] In one possible design, the second control circuit includes: a first low-side switch and a second low-side switch; the drain of the first low-side switch is connected to the second terminal of the energy storage element, and the controlled terminal is used to receive the energy storage control signal; the drain of the second low-side switch is grounded, and the source is connected to the source of the first low-side switch, and the controlled terminal is used to receive the energy storage control signal.
[0014] Based on the above optional methods, the first low-side switch and the second low-side switch can be used to quickly control the ground conduction loop of the energy storage element when the energy storage element releases energy, thereby enabling precise control of the charging energy of the energy storage element.
[0015] In one possible design, the second control circuit includes a diode, the anode of which is connected to the second terminal of the energy storage element, and the cathode is grounded.
[0016] Based on the above optional methods, the diode plays a role in voltage regulation and protection, ensuring the stability of the constant current power adjustable module. During the charging phase, the diode conducts to charge the energy storage element. When the diode is turned off, the charging circuit is disconnected, enabling precise control of the charging energy of the energy storage element. During the energy release phase, the energy released by the energy storage element flows into the anode of the laser and out from the cathode. At this time, due to the unidirectional conductivity of the diode, the current flowing out from the cathode of the laser flows into the second terminal of the energy storage element to form an energy release circuit, ensuring the reliability of energy release during the energy release phase.
[0017] In one possible design, the laser includes a laser diode, the anode of which is grounded, and the cathode which is connected to the anode of the first diode and the second end of the energy storage element.
[0018] In one possible design, the second control circuit includes a second switch connected in series between the second terminal of the energy storage element and the ground terminal.
[0019] In one possible design, the constant voltage emission module further includes: an emission control switch, the source of which is connected to the anode of the laser, the drain of which is connected to the first end of the energy storage element, the controlled end of which is used to receive the emission control signal, and the cathode of the laser being connected to the second end of the energy storage element; wherein, when the energy storage element is charging, the emission control switch is turned off, and when the energy storage element releases energy, the emission control switch is turned on.
[0020] Secondly, embodiments of this application provide a lidar, including: a constant current transmitting circuit, a controller, and a laser receiving circuit as described in any optional manner of the first aspect; the controller is connected to a constant current power adjustable module and a constant voltage transmitting module; the laser receiving circuit is connected to the controller and is used to receive the echo light formed by the laser emitted by the constant current transmitting circuit being reflected by the target object.
[0021] In one possible design, the lidar also includes: a laser array, the laser array being composed of M... The array consists of N lasers, where M and N are the number of rows and columns of lasers in the array, respectively. M and N are both positive integers, and at least one of M and N is greater than or equal to 2.
[0022] Based on the above-mentioned optional methods, the lidar provided in this application embodiment can be a combination of one laser corresponding to one constant current power adjustable module, or a combination of a laser array composed of multiple lasers corresponding to one constant current power adjustable module, or a combination of a laser array composed of multiple lasers each corresponding to multiple constant current power adjustable modules. Based on different combinations, the lidar provided in this application can achieve different effects. Furthermore, since the constant current power adjustable module does not contain charging devices such as inductors, there are no differences between inductors, thus avoiding the problem of poor consistency in the overall emitted laser of the lidar. Even if the lidar provided in this application embodiment contains multiple constant current power adjustable modules and lasers, the heat generated by the overall circuit is relatively small, and the circuit loss is also low.
[0023] Based on the constant voltage transmitting circuit and lidar provided in the embodiments of this application, the constant voltage transmitting circuit can emit lasers of different powers based on the power supply voltage. Furthermore, it can ensure that the charging current flowing into the energy storage element during the charging phase is a constant current, thus ensuring the overall reliability of the constant voltage transmitting circuit and, consequently, the detection reliability of the lidar using this constant current transmitting circuit. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description 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.
[0025] Figure 1 This is a circuit diagram of a low-voltage transmitting circuit in related technologies; Figure 2 This is a circuit diagram of another constant voltage transmitting circuit in related technologies; Figure 3 This is a schematic diagram of the frame structure of a lidar provided in an embodiment of this application; Figure 4 This is a schematic diagram of the frame structure of another lidar provided in the embodiments of this application; Figure 5 This is a schematic diagram of the framework structure of a constant current transmitting circuit provided in an embodiment of this application; Figure 6 This is a schematic diagram of the framework structure of another constant current transmitting circuit provided in the embodiments of this application; Figure 7 This is a schematic diagram of the circuit structure of a constant current transmitting circuit provided in an embodiment of this application; Figure 8 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in the embodiments of this application; Figure 9 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in the embodiments of this application; Figure 10 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in an embodiment of this application; Figure 11 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in an embodiment of this application; Figure 12 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in an embodiment of this application; Figure 13 This is a schematic diagram of the circuit structure of another constant current transmitting circuit provided in an embodiment of this application.
[0026] Figure label: 1-Lidar; 11-Constant current transmitting circuit; 111-Constant current power adjustable module; 1111-Energy storage element; 1112-First control circuit; 1113-Second control circuit; 112-Constant voltage transmitting module; 1121-Laser; 12-Controller; 13-Laser receiving circuit; V1 - Low-voltage transmitting power supply; V2 - Constant-voltage transmitting power supply; V3 - Transmitting power supply; L - Inductor; Q1 - First switching element; Q2 - Second switching element; Q3 - First high-side switch; Q4 - Third low-side switch; Q5 - Second high-side switch; Q6 - First low-side switch; Q7 - Second low-side switch; Q8 - Transmitting control switch; D1 - Rectifier diode; D2 - Diode; D3 - Laser diode; C1 - Capacitor; C2 - Energy storage capacitor. Detailed Implementation
[0027] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.
[0028] Where the following description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended embodiments.
[0029] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0031] Currently, lidar technology is becoming increasingly mature, leading to its widespread application in various fields such as ranging, surveying, traffic management, and atmospheric monitoring. A lidar system typically consists of a laser emitter and a laser detector. The laser emitter emits laser light to target objects within the detection area, while the laser detector receives the echo light reflected from the target objects within that area. Lidar can then perform detection based on the distance and velocity of the target object reflected from the echo light. To enable the laser emitter to emit laser light, it is usually necessary to provide it with a driving current of the required intensity to ensure that it can emit laser light based on that driving current.
[0032] In related technologies, low-voltage or constant-voltage power supplies are typically used to provide the driving voltage for the laser. For an example, please refer to [link to relevant documentation]. Figure 1 This refers to the circuit that provides drive current to a laser and the drive regulation circuit that controls energy in related technologies. This drive circuit typically consists of an inductor (such as...). Figure 1 As shown in L), the first switching element (such as L) Figure 1 Q1), rectifier diode (as shown) Figure 1 As shown in D1) and capacitors (such as Figure 1 As shown in Figure C1), one end of the inductor L is connected to a low-voltage transmitting power supply (such as...). Figure 1 As shown in Figure V1, the other end of inductor L is connected to the drain of the first switching element Q1, and the source of the first switching element Q1 is connected to one end of rectifier diode D1. The controlled terminal of the first switching element Q1 is used to receive the transmission control signal. The other end of rectifier diode D1 is connected to the first plate of capacitor C1 and the input terminal of the laser transmitter, and the second plate of capacitor C1 is grounded. When the first switching element Q1 is turned on, the current provided by the low-voltage transmission power supply V1 charges inductor L; when the first switching element Q1 is turned off, the current in inductor L charges capacitor C1 through rectifier diode D1; when capacitor C1 is fully charged, it discharges to the input terminal of the laser transmitter. It is worth noting that the discharge of capacitor C1 provides the driving current for the laser transmitter, enabling the laser transmitter to emit laser light based on the driving current. This drive regulation circuit is a boost circuit. During the conversion from low voltage to high voltage, the inductor L experiences some losses during the actual boost process, resulting in energy loss in the laser emitter. Furthermore, the lidar may connect to other peripheral circuits, and due to the inductor L, large cables are required for high current transmission, leading to cable losses. Additionally, the inductor L and the first switching element Q1 occupy a large area, generating significant heat during operation, increasing space requirements and heat dissipation costs, which is detrimental to integrated design.
[0033] Here, it is understandable that when a lidar has multiple drive adjustment circuits to drive multiple laser groups, the lidar becomes too large. Furthermore, due to the differences in inductance L between them, the power of the emitted lasers from the multiple lasers will be affected, resulting in poor uniformity of the emitted lasers and unsatisfactory actual detection results.
[0034] For example, please refer to Figure 2 , Figure 2 This is a drive circuit that provides the driving voltage to the laser from a constant voltage emission power supply. This drive circuit consists of a second switching element (such as...). Figure 2 The second switching element Q2 is configured such that its drain is connected to a constant voltage transmitting power supply (e.g., Q2). Figure 2 As shown in Figure V2, the source of the second switching element Q2 is connected to the input terminal of the laser emitter. The controlled terminal of the second switching element Q2 is used to receive the transmission control signal. The transmission control signal controls the on / off state and conduction time of the second switching element Q2, thereby controlling the emission state and power of the laser. However, when charging with a constant voltage power supply V2, the charging current is infinitely large, which may exceed the current threshold required for laser emission, causing the laser to emit light erroneously. To avoid this problem, current-limiting resistors are usually used to limit the charging current. This increases the power consumption of the drive circuit, reduces the charging efficiency, and increases the size of the drive circuit. Furthermore, in lidar technologies using a constant voltage power supply V2, it is usually necessary to release energy from a high voltage and convert energy to a low voltage. However, the laser emitter contains many parasitic capacitances and inductances, which slows down the process of releasing energy from the high voltage and charging energy from the low voltage, thus affecting the frequency of the laser emitted by the lidar.
[0035] To address this, this application provides a constant current emitting circuit and a lidar. The constant current emitting circuit can provide a constant current to the energy storage element without adding additional components, thereby avoiding the problem of excessive charging current causing the laser to emit light erroneously, and ensuring the reliability and accuracy of the laser emitted by the laser.
[0036] The constant current transmitting circuit and lidar provided in this application are described below with reference to the accompanying drawings.
[0037] Please see Figure 3This application provides a lidar 1, which may include a constant current emitting circuit 11, a controller 12, and a laser receiving circuit 13. The controller 12 is connected to the constant current emitting circuit 11 and the laser receiving circuit 13. The controller 12 is used to control the constant current emitting circuit 11 to emit light and to control the laser receiving circuit 13 to receive the echo light formed by the laser emitted by the constant current emitting circuit 11 being reflected by the target object, thereby determining the distance and speed of the target object and completing the detection of the target object.
[0038] In one example, please refer to Figure 4 The constant current transmitting circuit 11 may include a constant current power adjustable module 111 and a constant voltage transmitting module 112. The input terminal of the constant current power adjustable module 111 is connected to the transmitting power supply (e.g., Figure 4 The constant current power adjustable module 111 can also adjust the power of the laser emitted by the constant voltage emission module 112 based on the power supply voltage. Thus, the constant current emission circuit 11 provided in this application embodiment can emit lasers of different powers based on the power supply voltage, so that the lidar 1 can detect target objects at different distances over a wider range, thus expanding the detection range of the constant current emission circuit 11.
[0039] For example, please refer to Figure 5 The constant current power adjustable module 111 may include an energy storage element 1111, which provides a constant current to the energy storage element 1111. The constant voltage emission module 112 may include a laser 1121. The constant current power adjustable module 111 includes at least two stages: a charging stage and a releasing stage of the energy storage element 1111. The charging stage of the energy storage element 1111 includes charging it with a power supply voltage. The releasing stage of the energy storage element 1111 includes releasing the electrical energy stored in the energy storage element 1111 to drive the laser 1121 to emit laser light, thereby completing the stimulated emission step. To avoid excessive charging current during the charging process, which could cause the laser 1121 to emit light erroneously, the current flowing into the energy storage element 1111 when the power supply voltage charges the energy storage element 1111 is a constant current. This ensures a stable charging current, preventing excessive charging current from causing the laser 1121 to emit light erroneously and guaranteeing the reliability and accuracy of the laser emitted by the laser 1121. Furthermore, the constant current power adjustable module 111 can adjust the amount of energy stored in the energy storage element 1111. This means that by adjusting the amount of energy stored in the energy storage element 1111, the laser 1121 can emit lasers of different power. Thus, the constant current emission circuit 11 provided in this embodiment can emit lasers of different power based on a constant high voltage, thereby achieving the effect of detecting target objects at different distances over a wider range.
[0040] It is worth noting that the power supply voltage provided by the transmitting power supply V3 connected to the constant current power adjustable module 111 in this embodiment can be a constant voltage or a variable voltage. This application only needs to make the charging current in the charging stage a constant current through the constant current power adjustable module 111. This application does not impose any specific restrictions on this.
[0041] During the charging process, the energy storage element 1111 generates strong reverse current fluctuations across its terminals. Since it is connected in parallel with the laser 1121 in the constant current emission module 112, there is a possibility of reverse current flowing towards the laser 1121, potentially damaging it due to a large current surge. To ensure a constant charging current during the charging phase and to precisely regulate and control the energy stored in the energy storage element 1111 to guarantee the reliability of laser emission from the laser 1121, in one example, the constant current power adjustable module 111 further includes: a first control circuit 1112 and a second control circuit 1113. One end of the first control circuit 1112 is connected to the transmitting power supply V3, and the other end is connected to the energy storage element 1111. One end of the second control circuit 1113 is connected to the second end of the energy storage element 1111, and the other end is grounded. By controlling the conduction state and conduction time of the first control circuit 1112 and the second control circuit 1113, the charging state of the transmitting power supply V3 to the energy storage element 1111 and the amount of energy stored in the energy storage element 1111 can be controlled. Furthermore, the first control circuit 1112 ensures that the current flowing through it and into the energy storage element 1111 is constant. Thus, the constant current power adjustable module 111 provided in this embodiment not only ensures a constant charging current during the charging phase, preventing damage to the energy storage element, but also adjusts the amount of energy stored in the energy storage element 1111, thereby ensuring the reliability and accuracy of the laser emitted by the laser 1121, and consequently ensuring the detection reliability and accuracy of the lidar 1 using this constant current transmitting circuit 11.
[0042] For example, during the charging phase of the energy storage element 1111, both the first control circuit 1112 and the second control circuit 1113 are turned on. The current corresponding to the power supply voltage provided by the transmitting power supply V3 flows sequentially through the first control circuit 1112, the energy storage element 1111, and the second control circuit 1113 to ground, forming a charging loop. At this time, the first control circuit 1112 can ensure that the current flowing through the first control circuit 1112 and into the energy storage element 1111 is a constant current, ensuring the stability of the current connected to the energy storage element 1111. This avoids the problem of the laser 1121, which is connected in parallel with the energy storage element 1111, being damaged by a large current surge. At the same time, it also avoids the problem of the charging current being infinitely large when charging the energy storage element 1111, causing the charging current to exceed the current threshold required for the laser 1121 to emit light, thus causing the laser 1121 to emit light erroneously, affecting the detection accuracy of the lidar 1 and making the detection unreliable.
[0043] Thus, the charging current during the charging phase can be kept constant by the first control circuit 1112, thereby ensuring the reliability of the laser emitted by the laser 1121. Furthermore, this application eliminates the need for an additional boost circuit (e.g., a boost inductor) to charge the energy storage element 1111, resulting in a simple structure, low energy loss due to the absence of a boost process, and reduced heat generation, thus saving on heat dissipation costs. Simultaneously, it enables the constant current emission circuit 11 to emit lasers at a higher frequency, thereby allowing the lidar 1 to achieve high-frequency laser emission.
[0044] Furthermore, the constant current power adjustable module 111 provided in this application embodiment can adjust the charging state and the amount of energy stored in the energy storage element 1111 by controlling the conduction state and conduction time of the first control circuit 1112 and the second control circuit 1113 when a power supply voltage is applied. Since the other end of the second control circuit 1113 is grounded, i.e., the reference level is always 0V, there is always a stable voltage difference on the second control circuit 1113, and there is no voltage charging process of the bootstrap capacitor, resulting in a fast response speed. Moreover, when the second control circuit 1113 is turned off, the charging circuit formed by the first control circuit 1112, the energy storage element 1111, and the second control circuit 1113 will be turned off immediately. Therefore, the charging state and the amount of energy stored in the energy storage element 1111 can be precisely controlled, thereby ensuring the reliability of laser emission.
[0045] It is worth noting that the conduction state and conduction time of the first control circuit 1112 and the second control circuit 1113 are controlled and set by the controller 12. Furthermore, when the energy storage element 1111 releases energy, the second control circuit 1113 is turned off, rapidly cutting off the ground conduction loop of the energy storage element 1111, thereby ensuring the accuracy of energy release by the energy storage element 1111, and consequently ensuring the accuracy of laser emission from the constant voltage emission module 112.
[0046] Optional, please refer to Figure 7 The first control circuit 1112 can be a first high-side switch (such as...) Figure 7 As shown in Q3), below, energy storage element 1111 is used as the energy storage capacitor (as shown in Q3). Figure 7 As shown in Figure C2), the drain of the first high-side switch Q3 is connected to the transmitting power supply V3, and the source of the first high-side switch Q3 is connected to the first terminal of the energy storage capacitor C2. The controlled terminal (i.e., the gate) of the first high-side switch Q3 is connected to a power control signal. Here, it can be understood that the power control signal is provided by the controller 12, and the adjustment frequency of the power control signal can be adjusted according to different needs, thereby regulating the conduction state and conduction time of the first high-side switch Q3. During the charging phase, the first high-side switch Q3 can ensure that the charging current flowing to the energy storage capacitor C2 is a constant current. The following is an exemplary description of the first high-side switch Q3 provided in this application, based on whether the power supply voltage provided by the transmitting power supply V3 is a constant voltage or a non-constant voltage.
[0047] The first type: The power supply voltage provided by the transmitting power source V3 is a constant voltage.
[0048] Initially, the voltage of the energy storage capacitor C2 is 0V or a low voltage, resulting in a large voltage difference between C2 and the transmitting power supply V3. After the charging phase begins, the large voltage difference between C2 and V3 causes the first high-side switch Q3 to rapidly increase its current from zero, entering the saturation region. This means the current flowing through Q3 and to C2 is constant, ensuring the reliability of the laser 1121 during the charging phase. The linear conduction time of Q3 is then adjusted via a power control signal, enabling precise control of the energy stored in C2 and thus linear control of the laser power emitted by the laser 1121. After the charging phase, the energy release phase begins, at which point C2 releases energy, causing the laser 1121 to emit laser light at the corresponding power. Thus, by adjusting the conduction state and conduction time of the first high-side switch Q1, the laser 1121 can emit lasers of different powers, enabling the lidar 1 to detect target objects at different distances over a wider range, thereby expanding the detection range of the constant current emission circuit 11.
[0049] It is worth noting that as the energy storage capacitor C2 is continuously charged during the charging phase, the voltage difference between the energy storage capacitor C2 and the transmitting power supply V3 gradually decreases. When the voltage difference is reduced to a certain value, it may cause the first high-side switch Q3 to be in the variable resistance region. At this time, the current flowing through the first high-side switch Q3 and into the energy storage capacitor C2 is not a constant current. To avoid inconsistent charging current in this situation, which could affect the reliability of laser emission from laser 1121, this application sets the power supply voltage of the transmitting power supply V3 to be higher than or equal to the target voltage of the energy storage capacitor C2. Initially, the current will rapidly rise to the saturation region (constant current). As it approaches the target voltage, the first high-side switch Q3 enters the variable resistance region, and the current rapidly decreases, causing the energy storage capacitor C2 to approach the target voltage. Sufficient charging time is then allowed, ensuring that each path reaches a voltage close to the target voltage. Thus, during the charging phase, before the voltage of the energy storage capacitor C2 reaches the target voltage, the voltage difference between the energy storage capacitor C2 and the transmitting power supply V3 remains greater than a certain value, keeping the first high-side switch Q3 in the saturation region. This means that the current flowing through the first high-side switch Q3 and to the energy storage capacitor C2 is constant, thereby ensuring the reliability of laser 1121 during the charging phase.
[0050] The second type: The power supply voltage provided by the transmitting power source V3 is not constant.
[0051] Initially, the voltage of the energy storage capacitor C2 is 0V or a low voltage. At this time, the voltage difference between the energy storage capacitor C2 and the transmitting power supply V3 is relatively large. After the charging phase begins, due to the large voltage difference between the energy storage capacitor C2 and the transmitting power supply V3, the first high-side switch Q3 is in the saturation region. That is, the current flowing through the first high-side switch Q3 and into the energy storage capacitor C2 is a constant current, ensuring the reliability of the laser 1121 during the charging phase. As the energy storage capacitor C2 is continuously charged during the charging phase, its voltage increases. At this time, the power supply voltage provided by the transmitting power supply V3 can be increased, ensuring that the voltage difference between the energy storage capacitor C2 and the increased power supply voltage remains relatively large. This keeps the first high-side switch Q3 in the saturation region, meaning that the current flowing through the first high-side switch Q3 and into the energy storage capacitor C2 is constant. Consequently, the charging current of the energy storage capacitor C2 remains less than the current threshold required for the laser 1121 to emit light, avoiding the problem of the laser 1121 emitting light erroneously. This ensures the accuracy and reliability of the laser emitted by the constant voltage transmitting module 112, and consequently, the detection accuracy and reliability of the lidar 1.
[0052] In summary, this application can ensure the reliability of the laser 1121 by limiting the operation of the first high-side switch Q1 to the saturation region, so that the charging current flowing through the first high-side switch Q1 into the energy storage capacitor C2 is a constant current. Moreover, no additional devices are needed to limit the charging current, resulting in a simple structure.
[0053] In one example, see Figure 8 The first control circuit 1112 may also include a third low-side switch (such as...). Figure 8 As shown in Q4), the source of the third low-side switch Q4 is grounded, and the drain of the third low-side switch Q4 is connected to the source of the first high-side switch Q3. The controlled terminal of the third low-side switch Q4 is used to connect to the power control signal. At this time, by adjusting the adjustment frequency of the power control signal, the conduction state and conduction time of the first high-side switch Q3 and the third low-side switch Q4 can be adjusted, thereby achieving precise control over the charging state of the energy storage capacitor C2 and the amount of energy stored in the energy storage capacitor C2, thus ensuring the reliability of the emitted laser.
[0054] It is worth noting that after the energy release phase of the energy storage element 1111 ends, there is usually some energy remaining in the energy storage capacitor C2. At this time, when the first low-side switch Q6 is in the on state, the remaining energy in the energy storage capacitor C2 may be released through the first low-side switch Q6 in the on state, that is, there is energy backflow. Thus, there is a certain energy loss, which means that more energy is needed to charge the energy storage capacitor C2 next time, thereby prolonging the charging phase of the energy storage element 1111, which is inconsistent with the preset charging time. This may lead to instability in the energy release phase of the energy storage element 1111, which in turn reduces the reliability of laser emission.
[0055] To avoid energy backflow in the energy storage capacitor C2 after the energy release phase of the energy storage element 1111, which could potentially reduce the reliability of the emitted laser, please refer to [link to relevant documentation]. Figure 8 The high-side control circuit 1112 may also include a second high-side switch (such as...). Figure 8 As shown in Q5), the source of the second high-side switch Q5 is connected to the source of the first high-side switch Q3, and the drain of the second high-side switch Q5 is connected to the first terminal of the energy storage capacitor C2. The controlled terminal of the second high-side switch Q5 is connected to the power control signal. In this way, the added second high-side switch Q5 and the first high-side switch Q3 can form a pair of switches. The second high-side switch Q5 and the first high-side switch Q3 realize capacitor bootstrapping, thereby isolating the energy backflow problem of the energy storage capacitor C2, avoiding the energy loss problem, and thus ensuring the adjustment reliability of the constant voltage power adjustable module 111, that is, ensuring the reliability of the constant voltage emission circuit 11 emitting laser.
[0056] Optional, please refer to Figure 9The first control circuit 1112 can be a first switch (such as...) Figure 9 As shown in K1, the first switch K1 is connected in series between the transmitting power supply V3 and the first terminal of the energy storage capacitor C2. By controlling the on-state and on-time of the first switch K1, the charging state of the energy storage element 1111 and the amount of energy stored in the energy storage element 1111 can be precisely controlled, thereby ensuring the reliability of the emitted laser. At this time, a current-limiting element (e.g., a current-limiting resistor) can be set to limit the charging current, but this application does not make specific limitations on this.
[0057] The specific structure of the first control circuit 1112 provided in this application embodiment can be set based on different lidars 1. For example, if the lidar 1 does not need to achieve ultra-low power consumption, but is developing towards miniaturization, the first control circuit 1112 can only be set with a single switch, so that the structure is simple and meets the miniaturization development. In this regard, this application does not impose specific limitations.
[0058] It should be emphasized again that the second control circuit 1113 provided in this application embodiment can quickly control the on / off state of the ground conduction loop of the energy storage capacitor C2 during charging, thereby precisely controlling the charging energy of the energy storage capacitor C2 to ensure the accuracy of energy release, that is, to precisely control the power of the emitted laser, and thus ensure the accuracy of laser emission from the constant voltage emission module 112. For example, during the charging phase, when the second control circuit 1113 is turned off, the charging loop is disconnected to achieve precise control of the charging energy of the energy storage capacitor C2; during the energy release phase, the second control circuit 1113 is turned on, allowing the energy released by the energy storage capacitor C2 to flow to the laser 1121 to achieve narrow-pulse laser emission. It is worth noting that the specific circuit form of the second control circuit 1113 can be varied.
[0059] In one example, see Figure 10 The second control circuit 1113 may include a first low-side switch (such as...) Figure 10 As shown in Q6) and the second low-side switch (such as Figure 10As shown in Q7, the drain of the first low-side switch Q6 is connected to the second terminal of the energy storage capacitor C2. The controlled terminal of the first low-side switch Q6 is connected to the energy storage control signal. The drain of the second low-side switch Q7 is grounded, and the source of the second low-side switch Q7 is connected to the source of the first low-side switch Q6. The controlled terminal of the second low-side switch Q7 is also connected to the energy storage control signal. Here, it can be understood that the energy storage control signal is provided by the controller 12. The adjustment frequency of the energy storage control signal can be adjusted according to different needs, thereby adjusting the conduction state and conduction time of the first low-side switch Q6 and the second low-side switch Q7. Through the first low-side switch Q6 and the second low-side switch Q7, the conduction loop of the energy storage capacitor C2 to ground can be quickly turned on and off when the energy storage capacitor C2 releases energy, thereby precisely controlling the charging energy of the energy storage capacitor C2.
[0060] In one example, see Figure 11 The second control circuit 1113 may also include a diode (such as...). Figure 11 As shown in Figure D2), the anode of diode D2 is connected to the second terminal of energy storage capacitor C2, and the cathode of diode D2 is grounded to play a role in voltage stabilization and protection, ensuring the stability of the constant current power adjustable module 111. In this example, one end of the laser 1121 is grounded, and the other end of the laser 1121 is connected between the second terminal of the energy storage capacitor C2 and the anode of the diode D2. Taking the laser 1121 as a laser diode (LD) as an example, the anode of the laser diode is grounded, and the cathode of the laser diode is connected between the second terminal of the energy storage capacitor C2 and the anode of the diode D2. At this time, during the charging stage, the diode D2 is turned on to charge the energy storage capacitor C2. When the diode D2 is turned off, the charging circuit is broken, so as to achieve precise control of the charging energy of the energy storage capacitor C2. During the energy release stage, the energy released by the energy storage capacitor C2 flows into the anode of the laser diode and flows out from the cathode of the laser diode. At this time, since the characteristic of the diode D2 is unidirectional conduction, the current flowing out from the cathode of the laser diode will flow into the second terminal of the energy storage capacitor C2 to form an energy release circuit, ensuring the reliability of energy release during the energy release stage.
[0061] Optional, such as Figure 12 As shown, the second control circuit 1113 may include a second switch (such as...) Figure 12 As shown in Figure K2, the second switch K2 is connected in series between the second terminal of the energy storage capacitor C2 and the ground terminal. The second switch K2 allows for rapid switching on and off of the ground conduction loop of the energy storage capacitor C2 when it releases energy, thereby enabling precise control of the charging energy of the energy storage capacitor C2.
[0062] It is worth noting that the second control circuit 1113 may also include other switching elements, and this application does not impose specific limitations on this.
[0063] Thus, the constant current power adjustable module 111 provided in this embodiment of the application is equipped with an energy storage element 1111, a first control circuit 1112, and a second control circuit 1113. By controlling the conduction state and conduction time of the first control circuit 1112 and the second control circuit 1113, the constant current emitting circuit 11 can enable the laser 1121 to emit lasers of different powers based on the power supply voltage. The first control circuit 1112 can ensure that the charging current flowing into the energy storage element 1111 is a constant current, thereby ensuring the stability of the current connected to the energy storage element 1111. This avoids the problem of the laser 1121, which is connected in parallel with the energy storage element 1111, being damaged by a large current surge or the laser 1121 emitting light erroneously, thus ensuring the reliability of the laser emitted by the constant current emitting circuit 11. Furthermore, the second control circuit 1113 has a fast switching response speed, ensuring the overall reliability of the constant current emitting circuit 11, making it suitable for different lidars 1 and detection scenarios. The constant current transmitting circuit 11 in this application does not require additional charging components and boost circuits, and has a simple overall structure. Furthermore, the constant current transmitting circuit 11 does not have a boost process, resulting in low energy loss.
[0064] Here, it can be understood that the lidar 1 provided in this application embodiment can be a combination of one laser 1121 corresponding to one constant current power adjustable module 111, or a combination of a laser array composed of multiple lasers 1121 corresponding to one constant current power adjustable module 111, or a combination of multiple laser arrays composed of multiple lasers 1121 respectively corresponding to multiple constant current power adjustable modules 111. It is worth noting that the laser array can be composed of M... The array consists of N lasers 1121, where M and N are the number of rows and columns of lasers 1121 included in the array, respectively. M and N are both positive integers, and at least one of M and N is greater than or equal to 2. The specific number can be set based on actual needs, and this application does not impose specific restrictions on this.
[0065] For example, when the lidar 1 is a combination of a laser array consisting of multiple lasers 1121 and a constant current power adjustable module 111, more lasers 1121 can be arranged in the lidar 1. The constant current power adjustable module 111 controls the stimulated light state of the lasers 1121 and the power of the emitted laser, so that the uniformity of the emitted laser of the lidar 1 is high.
[0066] For example, when the lidar 1 is a combination of multiple constant current power adjustable modules 111 corresponding to a laser array composed of multiple lasers 1121, each row, column, or block of lasers 1121 in the laser array can be controlled by an independent constant current power adjustable module 111. This results in higher precision in controlling the laser emitted by the lidar 1. Furthermore, based on different needs, the emission power of lasers 1121 in different areas of the laser array can be made different to achieve different detection effects, improving the overall applicability of the lidar 1. Meanwhile, the constant current power adjustable module 111 provided in this application does not contain charging devices such as inductors. Therefore, there are no differences between inductors, thus avoiding the problem of poor consistency in the overall emitted laser. Moreover, even though the lidar 1 provided in this embodiment has multiple constant current power adjustable modules 111, the heat generated by the overall circuit is relatively small, and the circuit loss is also low.
[0067] In one example, see Figure 13 The constant voltage transmitter module 112 may also include a transmitter control switch (such as...). Figure 13 As shown in Q8), the source of the emission control switch Q8 is connected to the laser 1121, with the laser 1121 serving as a laser diode (e.g., Q8). Figure 13 Taking D3 as an example, the source of the transmit control switch Q8 is connected to the anode of the laser diode D4, the drain of the transmit control switch Q8 is connected to the first terminal of the energy storage element 1111, the controlled terminal of the transmit control switch Q8 is used to receive the transmit control signal, and the cathode of the laser diode D4 is connected to the second terminal of the energy storage element 1111. Here, it can be understood that the transmit control signal is provided by the controller 12, and the frequency of the transmit control signal can be adjusted according to different needs, thereby adjusting the conduction state and conduction time of the transmit control switch Q8.
[0068] During the charging phase of the energy storage element 1111, the transmission control switch Q8 is turned off. During the energy release phase of the energy storage element 1111, the transmission control switch Q8 is turned on, and the driving current released by the energy storage element 1111 flows through the transmission control switch Q8 and the laser 1121 to ground, forming an energy release circuit to drive the laser 1121 to emit light. In this way, by controlling the on and off state of the transmission control switch Q8, the reliability of the laser 1121 in different modes can be ensured, thereby ensuring the accuracy and reliability of the laser emitted by the constant voltage transmission module 112, and thus ensuring the detection accuracy and reliability of the lidar 1 using the constant voltage transmission module 112.
[0069] Optionally, the laser 1121 can also be disposed between the energy storage element 1111 and the ground terminal. For example, the cathode of the laser 1121 is connected to the second end of the energy storage element 1111, and the anode of the laser 1121 is grounded. The specific placement of the laser 1121 can be selected according to actual needs, and this application does not impose specific restrictions on this.
[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0071] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A constant current transmitting circuit, characterized in that, The constant current transmitting circuit includes: A constant current power adjustable module includes an energy storage element. The input terminal of the constant current power adjustable module is connected to a transmitting power supply with an output power voltage to charge the energy storage element. The constant current power adjustable module provides a constant current to the energy storage element and adjusts the amount of energy stored in the energy storage element. A constant voltage emission module includes a laser connected to an energy storage element. The laser is used to emit laser light when the energy storage element releases energy, and different energies stored in the energy storage element correspond to different laser emission powers. The constant current power adjustable module also includes: The first control circuit has one end connected to the transmitting power supply and the other end connected to the energy storage element; The second control circuit has one end connected to the second end of the energy storage element and the other end grounded. When the energy storage element is charged, both the first control circuit and the second control circuit are turned on and the on time is controllable, so as to charge the energy storage element through the transmitting power supply and control the amount of energy stored in the energy storage element. The current flowing through the first control circuit and into the energy storage element is a constant current. When the energy storage element releases energy, at least the first control circuit is turned off.
2. The constant current transmitting circuit according to claim 1, characterized in that, The first control circuit includes: The first high-side switch has a drain connected to the transmitting power supply, a source connected to the first end of the energy storage element, and a controlled end connected to the power control signal.
3. The constant current transmitting circuit according to claim 1, characterized in that, The first control circuit includes: The first switch is connected in series between the transmitting power source and the first terminal of the energy storage element.
4. The constant current transmitting circuit according to any one of claims 1-3, characterized in that, The second control circuit includes: The first low-side switch has its drain connected to the second terminal of the energy storage element, and the controlled terminal is used to receive the energy storage control signal. The second low-side switch has its drain grounded and its source connected to the source of the first low-side switch. The controlled terminal is used to receive the energy storage control signal.
5. The constant current transmitting circuit according to any one of claims 1-3, characterized in that, The second control circuit includes: The diode has its anode connected to the second terminal of the energy storage element, and its cathode grounded.
6. The constant current transmitting circuit according to claim 5, characterized in that, The laser includes: The laser diode has its anode grounded and its cathode connected to both the anode of the first diode and the second terminal of the energy storage element.
7. The constant current transmitting circuit according to any one of claims 1-3, characterized in that, The second control circuit includes: The second switch is connected in series between the second end of the energy storage element and the grounding end.
8. The constant current transmitting circuit according to any one of claims 1-3 or 4, characterized in that, The constant voltage transmission module also includes: The emission control switch has its source connected to the anode of the laser, its drain connected to the first end of the energy storage element, and its controlled end used to receive the emission control signal. The cathode of the laser is connected to the second end of the energy storage element. Specifically, when the energy storage element is charging, the transmission control switch is turned off, and when the energy storage element releases energy, the transmission control switch is turned on.
9. A lidar, characterized in that, include: At least one constant current transmitting circuit as described in any one of claims 1-8; The controller is connected to the constant current power adjustable module and the constant voltage transmission module; A laser receiving circuit, connected to the controller, is used to receive the echo light formed by the laser emitted by the constant current emitting circuit being reflected by the target object.
10. The lidar according to claim 9, characterized in that, The lidar also includes: Laser array, consisting of M The array consists of N lasers, where M and N are the number of rows and columns of the lasers in the array, respectively. M and N are both positive integers, and at least one of M and N is greater than or equal to 2.