Laser emitting circuit

Abstract

The present application provides a laser emitting circuit. The laser emitting circuit comprises: n laser emitting channels and first circuits, and the n laser emitting channels are connected to a common cathode, n being a positive integer greater than 1. In a single laser emitting channel, an anode of a laser is connected to a first power supply by means of a gating circuit, a cathode of the laser is connected to the common cathode, and the gating circuit is used for controlling the connection or disconnection between the laser and the first power supply. One end of each first circuit is connected to a second power supply, and the other end is connected to a first node between the corresponding gating circuit and the corresponding laser. The first circuits are unidirectional conduction circuits, and a conduction direction of each first circuit is a direction in which current flows from the second power supply to the corresponding first node. An output voltage of the second power supply is less than a turn-on voltage of each laser. Embodiments of the present application can be applied to intelligent vehicles or new energy vehicles, can reduce circuit costs, and can reduce the reverse voltage applied to a laser, thereby preventing the laser from being damaged due to the reverse voltage.

Description

Laser emitting circuit Technical Field

[0001] This application relates to the field of detection technology, and more specifically, to a laser emitting circuit. Background Technology

[0002] With the development of laser technology, lidar has been widely used in fields such as intelligent vehicles and surveying. Some lidar systems may include multiple lasers, and each laser can be driven by a laser emitting circuit to emit a laser beam.

[0003] If each laser is controlled independently using a high-side drive method, the number of drive switches that need to withstand high current in the laser emitting circuit will increase with the number of lasers, greatly affecting the cost of the lidar and hindering the miniaturization of the entire lidar system. By adopting a common-cathode low-side drive scheme, the number of high-current drive devices required in the laser emitting circuit can be greatly reduced, thus significantly lowering the cost of the laser emitting circuit.

[0004] However, the common cathode low-side drive scheme increases the reverse voltage on the laser, making the laser more susceptible to damage due to the reverse voltage. Summary of the Invention

[0005] This application provides a laser emitting circuit that reduces circuit cost while lowering the reverse voltage experienced by the laser, thus preventing damage to the laser due to reverse voltage.

[0006] In a first aspect, a laser emitting circuit is provided. The laser emitting circuit includes: n laser emitting channels and a first circuit; the n laser emitting channels are connected to a common cathode, where n is a positive integer greater than 1. Each of the n laser emitting channels includes a laser and a gating circuit. In a single laser emitting channel, the anode of the laser is connected to a first power supply via the gating circuit, and the cathode of the laser is connected to the common cathode. The gating circuit is used to control the connection or disconnection of the laser and the first power supply. One end of the first circuit is connected to a second power supply, and the other end of the first circuit is connected to a first node between the gating circuit and the laser; the first circuit is a unidirectional conducting circuit, and the conduction direction of the first circuit is the direction in which current flows from the second power supply to the first node; the output voltage of the second power supply is less than the turn-on voltage of the laser.

[0007] In this application, by setting a first circuit with unidirectional conduction function, the anode of the laser can be connected to a second power supply. When the corresponding selection circuit of the laser is in the open state, the electromotive force at the anode of the laser will rise to near the output voltage of the second power supply. On the one hand, when the electromotive force at the cathode of the laser (i.e., the electromotive force on the common cathode) increases due to the opening of the drive switch, the reverse voltage experienced by the laser will decrease accordingly because the anode of the laser can be connected to the second power supply. On the other hand, since the output voltage of the second power supply is less than the turn-on voltage of the laser, even if the first circuit is turned on, the laser will not emit light under the influence of the second power supply. In this way, the reverse voltage experienced by the laser can be reduced, and the laser's light emission process can be avoided.

[0008] In some possible implementations, the laser emitting circuit may further include a second circuit; the second circuit may be connected to a common cathode and a third power supply, and may be used to limit the current flow from the common cathode to the third power supply when the electromotive force of the common cathode is in a steady state; the output voltage of the third power supply may be greater than a first threshold and less than a second threshold. The first threshold may be the steady-state electromotive force of the common cathode when the second circuit is in an off state, at least one selector switch is in a conducting state, and the drive switch is in an off state; the second threshold may be the peak electromotive force of the common cathode when the second circuit is in an off state; the drive switch may be used to connect the common cathode and ground.

[0009] In this application, since the second circuit connects the common cathode and the third power supply, even if an induced electromotive force (EMF) in the circuit causes the EMF of the common cathode to be too high, when the induced EMF of the common cathode exceeds the third power supply, current can flow from the common cathode to the third power supply, thereby reducing the EMF of the common cathode and thus lowering the reverse voltage experienced by the laser. Furthermore, the second circuit can limit the current flow from the common cathode to the third power supply when the EMF of the common cathode is in a steady state. Therefore, including this second circuit in the laser emitting circuit will not affect the normal light emission process of the laser. In this way, the reverse voltage experienced by the laser can be further reduced, and the laser's light emission process can be avoided.

[0010] In some possible implementations, the difference between the output voltage of the third power supply and the first threshold can be less than or equal to the third threshold.

[0011] When current flows through the second circuit to the third power supply, the greater the difference between the output voltage of the third power supply and the peak electromotive force (i.e., the smaller the difference between the peak and steady-state electromotive force), the faster the common cathode will depressurize. In this application, the difference between the output voltage of the third power supply and the first threshold is set within the third threshold. On the one hand, this helps to maintain the reverse voltage on the laser at a low level; on the other hand, it also ensures the depressurization speed of the common cathode.

[0012] In some possible implementations, the third threshold can be less than or equal to 2 volts.

[0013] In some possible implementations, the second circuit may include a diode. The diode can be in the direction of current flow from the common cathode to the third power source, and the diode's parasitic capacitance can be less than or equal to a fourth threshold.

[0014] In this application, by incorporating a diode in the second circuit, the second circuit becomes a unidirectional conducting circuit where current flows from the common cathode to the third power supply. Since the electromotive force (EMF) of the common cathode typically only increases rapidly when the state of the driving switch changes, when the EMF of the common cathode exceeds that of the third power supply, the second circuit can depressurize the common cathode, causing its EMF to drop rapidly, thereby reducing the reverse voltage experienced by the laser. Furthermore, because the output voltage of the third power supply is greater than the steady-state EMF of the common cathode when the second circuit is open, the diode in the second circuit will not conduct when the EMF of the common cathode is in a steady state, thus avoiding interference with the normal light emission process of the laser.

[0015] In some possible implementations, the fourth threshold can be less than or equal to 5 picofarads.

[0016] In this application, when the parasitic capacitance of the diode is less than or equal to 5 picofarads, the second circuit can have better high-frequency response performance and the second circuit can have a higher discharge speed to the common cathode.

[0017] In some possible implementations, the second circuit may include a capacitor.

[0018] In this application, by setting a capacitor in the second circuit, on the one hand, when the electromotive force of the common cathode is in a steady state, the capacitor in the second circuit can achieve isolation between the common cathode and the third power supply, so that the second circuit can avoid affecting the normal light emission process of the laser; on the other hand, since the electromotive force of the common cathode often rises rapidly only when the state of the driving switch changes, the capacitor in the second circuit can realize the transfer of electrical energy between the common cathode and the third power supply at this time, thereby reducing the electromotive force of the common cathode and thus reducing the reverse voltage on the laser.

[0019] In some possible implementations, the length of the second circuit can be less than or equal to 10 millimeters.

[0020] When current flows from the second circuit to the third power source, the shorter the length of the second circuit, the faster the pressure relief rate of the common cathode will be. In this application, the length of the second circuit is set to within 10 millimeters, which ensures the pressure relief rate of the common cathode.

[0021] In some possible implementations, the laser emitting circuit may also include a drive switch and a control circuit for the drive switch. The drive switch may be connected to a common cathode and ground; the control circuit for the drive switch may include a pull-down control circuit, which may be provided with a first impedance.

[0022] Since there is a correlation between the current in the control circuit of the drive switch and the current in the main loop of the drive switch, this application reduces the rate of change of the current in the pull-down control circuit by setting an impedance, thereby reducing the rate of change of the current in the main loop. Furthermore, since the induced electromotive force generated in the circuit when the state of the drive switch changes is positively correlated with the rate of change of the current, setting an impedance in the pull-down control circuit reduces the induced electromotive force in the circuit, thereby reducing the electromotive force of the common cathode and thus reducing the reverse voltage of the laser.

[0023] In some possible implementations, the first impedance can be a resistor.

[0024] In some possible implementations, the difference between the output voltage of the second power supply and the turn-on voltage can be less than or equal to the fifth threshold.

[0025] In a single laser emission channel, when the gating circuit within that channel is open, the electromotive force at the anode of the laser in that channel will be near the output voltage of the second power supply. Consequently, the smaller the difference between the output voltage of the second power supply and the turn-on voltage of the laser, the better the effect on improving the reverse voltage experienced by the laser. In this application, setting the difference between the output voltage of the second power supply and the turn-on voltage of the laser within a fifth threshold is beneficial for maintaining the reverse voltage experienced by the laser at a low level.

[0026] In some possible implementations, the fifth threshold can be less than or equal to 1 volt.

[0027] In some possible implementations, a single laser emission channel may also include an energy storage circuit with a capacitor, one end of which may be connected to ground, and the other end of which may be connected to a second node between the laser and the gating circuit.

[0028] Secondly, a laser emitting circuit is provided. This laser emitting circuit includes: n laser emitting channels and a second circuit; the n laser emitting channels are connected to a common cathode, where n is a positive integer greater than 1. Each of the n laser emitting channels includes a laser and a gating circuit. In a single laser emitting channel, the anode of the laser is connected to a first power supply via the gating circuit, and the cathode of the laser is connected to the common cathode. The gating circuit is used to control the connection or disconnection of the laser and the first power supply. The second circuit connects the common cathode and a third power supply. The second circuit is used to limit the current flow from the common cathode to the third power supply when the electromotive force of the common cathode is in a steady state; the output voltage of the third power supply can be greater than a first threshold and less than a second threshold. The first threshold can be the steady-state electromotive force of the common cathode when the second circuit is in an off state, at least one gating switch is in a conducting state, and a drive switch is in an off state; the second threshold can be the peak electromotive force of the common cathode when the second circuit is in an off state; the drive switch can be used to connect the common cathode and ground.

[0029] In some possible implementations, the difference between the output voltage of the third power supply and the first threshold can be less than or equal to the third threshold.

[0030] In some possible implementations, the third threshold can be less than or equal to 2 volts.

[0031] In some possible implementations, the second circuit may include a diode. The diode can be in the direction of current flow from the common cathode to the third power source, and the diode's parasitic capacitance can be less than or equal to a fourth threshold.

[0032] In some possible implementations, the fourth threshold can be less than or equal to 5 picofarads.

[0033] In some possible implementations, the second circuit may include a capacitor.

[0034] In some possible implementations, the length of the second circuit can be less than or equal to 10 millimeters.

[0035] Thirdly, a laser emitting circuit is provided. This laser emitting circuit includes: n laser emitting channels, a drive switch, and a control circuit for the drive switch; the n laser emitting channels are connected to a common cathode, where n is a positive integer greater than 1; the drive switch is connected to the common cathode and a ground wire. Each of the n laser emitting channels includes a laser and a gating circuit. In a single laser emitting channel, the anode of the laser is connected to a first power supply via the gating circuit, and the cathode of the laser is connected to the common cathode. The gating circuit is used to control the connection or disconnection of the laser and the first power supply. The control circuit for the drive switch may include a pull-down control circuit, which may be provided with a first impedance.

[0036] For example, the control circuit of the drive switch can be used to control the drive switch to be turned on or off; one end of the pull-down control circuit can be connected to the control terminal of the drive switch, and the other end can be connected to the ground wire.

[0037] In some possible implementations, the control circuit for driving the switch may also include a pull-up control circuit, one end of which can be connected to the control terminal of the drive switch, and the other end of which can be connected to a fourth power supply.

[0038] In some possible implementations, the first impedance can be a resistor.

[0039] Fourthly, a detection device is provided, which may include the laser emitting circuitry of any one of the first to third aspects and their possible implementations. For example, the detection device may be a lidar.

[0040] Fifthly, an intelligent driving device is provided, which may include the laser emitting circuit of any one of the first to third aspects and their possible implementations, or may include the detection device of the fourth aspect and any possible implementations. For example, the intelligent driving device may be a vehicle. Attached Figure Description

[0041] Figure 1 is a schematic diagram of the laser emitting circuit 100 provided in an embodiment of this application;

[0042] Figure 2 is a schematic diagram of the laser emitting circuit 200 provided in an embodiment of this application;

[0043] Figure 3 is a schematic diagram showing the change of potential difference across some components in the laser emitting circuit 200 provided in the embodiment of this application;

[0044] Figure 4 is a schematic diagram of the laser emitting circuit 300 provided in an embodiment of this application;

[0045] Figure 5 is a schematic diagram of the laser emitting circuit 400 provided in an embodiment of this application;

[0046] Figure 6 is a schematic diagram of the change in electromotive force in the laser emitting circuit 400 provided in the embodiment of this application;

[0047] Figure 7 is a schematic diagram showing the change of potential difference across some components in the laser emitting circuit 400 provided in the embodiment of this application;

[0048] Figure 8 is a schematic diagram of the laser emitting circuit 500 provided in an embodiment of this application;

[0049] Figure 9 is a schematic diagram of the laser emitting circuit 600 provided in an embodiment of this application;

[0050] Figure 10 is a schematic diagram of the change in electromotive force in the laser emitting circuit 600 provided in the embodiment of this application;

[0051] Figure 11 is a schematic diagram showing the change of potential difference across some components in the laser emitting circuit 600 provided in the embodiment of this application;

[0052] Figure 12 is a schematic diagram of a control circuit for driving a switch provided in an embodiment of this application;

[0053] Figure 13 is a schematic diagram of the laser emitting circuit 700 provided in an embodiment of this application;

[0054] Figure 14 is a schematic diagram of the laser emitting circuit 800 provided in an embodiment of this application;

[0055] Figure 15 is a schematic diagram of the change in electromotive force in the laser emitting circuit 800 provided in the embodiment of this application;

[0056] Figure 16 is a schematic diagram showing the change of potential difference across some components in the laser emitting circuit 800 provided in the embodiment of this application;

[0057] Figure 17 is a schematic diagram of the laser emitting circuit 1000 provided in an embodiment of this application;

[0058] Figure 18 is a schematic diagram of the change in electromotive force in the laser emitting circuit 1000 provided in the embodiment of this application;

[0059] Figure 19 is a schematic diagram showing the change of potential difference across some components in the laser emitting circuit 1000 provided in the embodiment of this application;

[0060] Figure 20 is a schematic diagram of the laser emitting circuit 1200 provided in an embodiment of this application. Detailed Implementation

[0061] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0062] Lidar is a sensor that combines laser technology with photoelectric conversion technology. Its basic working principle is: the transmitter emits detection light into the detection area, and the receiver receives the return light (or echo) returned from the detection area. The relevant information of the target in the detection area is obtained through the return light.

[0063] For example, the transmitter can use one or more of the following lasers as the light source: vertical cavity surface emitting laser (VCSEL), photonic crystal surface emitting semiconductor laser (PCSEL), edge emitting laser (EEL), laser diode (LD), distributed feedback laser diode (DFB-LD), grating coupled sampling reflection laser diode (GCSR-LD), or micro opto-electro-mechanical system laser diode (MOEMS-LD), etc.

[0064] In one possible implementation, the emitting end may include a laser emitting chip, which includes one of the aforementioned multiple light sources. In another possibility, the emitting end may include a single VCSEL chip. In yet another possibility, the emitting end may include a laser emitting chip composed of multiple VCSEL chips spliced ​​together. On the one hand, by splicing multiple VCSEL chips, the emission power of the detection device can be increased, the blind zone of the detection device can be reduced, and the detection performance can be improved. On the other hand, with the same emitting area, splicing multiple VCSEL chips results in less stress than directly using a single VCSEL chip of approximately the same size. Furthermore, splicing multiple chips also has higher heat dissipation efficiency and can reduce crosstalk.

[0065] For some lidar systems, the transmitting end can include multiple lasers, such as mechanical multi-line lidar and solid-state lidar. The transmitting end can also include corresponding driving circuits for these multiple lasers. In some possible implementations, the multiple lasers included in the transmitting end can be arranged in an array, such as a one-dimensional array or a two-dimensional array.

[0066] In some lidar systems, multiple lasers at the transmitting end need to be controlled independently, such as one-dimensional addressable flash lidar, two-dimensional addressable flash lidar, and semi-solid-state lidar. If a high-side drive method is used to independently control each laser, the number of drive switches in the laser transmitting circuit that need to withstand high current increases with the number of lasers, significantly impacting the lidar's cost and hindering its miniaturization. By adopting a common-cathode low-side drive scheme, the number of high-current driving devices required in the circuit can be greatly reduced, significantly lowering the circuit cost.

[0067] High-side drive means that the load drive switch is located on the power supply side of the load; that is, the drive switch is located between the load and the power supply, rather than between the load and electrical ground. Low-side drive means that the load drive switch is located on the ground side of the load; that is, the drive switch is located between the load and electrical ground, rather than between the load and the power supply.

[0068] The following example uses laser diodes as the light source at the transmitter, and illustrates the two driving methods described above with reference to Figures 1 and 2. Figures 1 and 2 respectively demonstrate the use of high-side driving and low-side driving methods to drive multiple laser diodes (e.g., laser diodes LD1 to LD2). n (where n is a positive integer). In addition, in Figures 1 and 2, it is assumed that the driving switch of the laser is a metal-oxide-semiconductor field-effect transistor (MOSFET). Hereinafter, MOSFET can be simply referred to as MOS, MOS transistor, or MOS transistor switch.

[0069] For example, Figures 1 and 2 are schematic diagrams of two laser emitting circuits provided in this application.

[0070] Referring to Figure 1, in the laser emitting circuit 100 (hereinafter referred to as circuit 100), a single laser can have an independent drive switch; for example, MOS1 to MOS2. n Can be used with laser diodes LD1 to LD n One-to-one correspondence. For MOS1 to MOS n For any MOSFET switch in the circuit, when the MOSFET switch is in the closed state, the laser diode connected to it will be connected to the power supply Vcc. Taking laser diode LD1 as an example, its driving switch (i.e., MOS1) can be set on the anode side of laser diode LD1, or between laser diode LD1 and power supply Vcc; when MOS1 is in the closed state, laser diode LD1 will be connected to capacitor C0 and power supply Vcc, and the laser diode will be able to emit light.

[0071] In the scheme shown in Figure 1, the light emission process of each laser can be independently controlled by controlling the closing and opening of each drive switch; since the drive switch is located between the laser and the power supply, this method can also be called the high-side independent drive method.

[0072] Referring to Figure 2, in the laser emitting circuit 200 (hereinafter referred to as circuit 200), multiple lasers can share the same drive switch; for example, laser diodes LD1 to LD2. n The cathode of each laser can be connected to a common cathode, and the drive switch (e.g., MOS0) can be connected to the common cathode and ground. Furthermore, to achieve independent control of each laser, a corresponding selector switch (e.g., switches S1 to S2) can be installed on the anode side of each laser. n The selector switch can be connected to Vcc at one end and to the anode of the corresponding laser diode at the other end. Taking laser diode LD1 as an example, by closing switch S1, the anode of laser diode LD1 can be connected to the power supply Vcc, and the power supply Vcc can charge capacitor C1; when MOS0 is closed, laser diode LD1 will be connected to ground, and the laser diode will be able to emit light. When only laser diode LD1 needs to emit light, switches S2 to S... n Set to the off state; in this case, even if MOS0 is closed, only the laser diode LD1 will emit light.

[0073] In the scheme shown in Figure 2, the light emission process of each laser can be individually controlled by the combination of the gating switch and the driving switch. Since the gating switch is set at the anode of the laser and the driving switch is set at the cathode of the laser, this method can also be called the high-side gating-low-side driving method.

[0074] Referring to Figure 2, the circuit 200 may also include a control circuit 210 (hereinafter referred to as control circuit 210 or circuit 210) for driving the switch. The control circuit 210 may be connected to the control terminal of MOS0 to control MOS0 to be turned on or off.

[0075] In the high-side gating-low-side driving method, when the laser emits light, the current flowing through the driving switch will be much greater than the current flowing through the gating switch of the laser. The former may be tens or even hundreds of times greater than the latter.

[0076] Compared to the high-side independent driving method, the high-side gating-low-side driving method reduces the number of switches that need to withstand high current in the circuit by sharing the driving switch; in particular, it can greatly reduce the cost of the circuit when there are a large number of lasers.

[0077] However, using a high-side gating and low-side driving method increases the reverse voltage on the laser, making the laser more susceptible to breakdown due to the reverse voltage.

[0078] In the circuit 200 shown in Figure 2, the electromotive force at the anode of the laser diode LD1 is denoted as V. 10 The electromotive force at the cathode of laser diode LD1 is denoted as V. 20 , laser diode LD n The electromotive force at the positive end is denoted as V. 30 Accordingly, V 10 -V 20 This can represent the potential difference across the laser diode LD1, V 30 -V 20 This can represent a laser diode (LD). n The potential difference between the two ends. Moreover, since circuit 200 uses a common cathode connection for each laser, the electromotive force at the cathode of laser diode LD1 can also be the electromotive force of the common cathode.

[0079] The following assumes that the power supply Vcc is 30 volts (V). Taking the light emission process of laser diode LD1 as an example, the formation of reverse voltage is illustrated in Figure 3.

[0080] Assume that in the test scenario shown in Figure 3, only channel 1, where laser diode LD1 is located, needs to emit light. In this scenario, switch S1 can be set to the closed state, and switches S2 to S... n Set to the off state. Before the laser diode LD1 needs to emit light, the drive switch (i.e., MOS0) can be set to the off state. When the laser diode LD1 needs to emit light, MOS0 can be controlled to close; correspondingly, the power supply Vcc, capacitor C1, laser diode LD1, and ground will form a loop, allowing the laser diode LD1 to emit light. After the emission is complete, MOS0 can be controlled to open.

[0081] Before MOS0 closes, since switch S1 is closed, the power supply Vcc will charge capacitor C1, and the voltage on capacitor C1 can reach the voltage of the power supply Vcc (i.e., 30V). Since one end of capacitor C1 is grounded and the other end is connected to the anode of laser diode LD1, the electromotive force at the anode of laser diode LD1 (i.e., V...) 10 It can approach 30V. Due to the switch S2 to S... n When in the open state, capacitors C2 to C n The voltage on it will be 0; with the laser diode LD n For example, the electromotive force (i.e., V) at the anode of this laser diode 30At this point, it will be 0. Additionally, since the laser diode LD1 and MOS0 are connected in series and MOS0 is grounded, when switch S1 is closed, the electromotive force V... 10 It will be divided by the laser diode LD1 and the MOS0 which is in the off state.

[0082] For example, referring to Figure 3, before MOS0 is closed, the voltage division of laser diode LD1 (i.e., V) 10 -V 20 The voltage is approximately 7V, and the voltage drop across MOS0 is approximately 23V. Since MOS0 is connected to the common cathode and ground, the electromotive force (EMF) of the common cathode (i.e., V) is approximately 7V. 20 The voltage is approximately 23V; correspondingly, the laser diode LD... n The potential difference between the two ends (i.e., V) 30 -V 20 The voltage is approximately -23V, which is the voltage of the laser diode LD. n It will be subjected to a reverse voltage of approximately 23V.

[0083] When MOS0 is closed, its internal resistance decreases rapidly, the potential difference across MOS0 drops rapidly to 0V, and the electromotive force (EMF) of the common cathode drops to 0V. When MOS0 is closed, due to the emission of light from laser diode LD1, the energy stored in capacitor C1 will be consumed, and the EMF at the anode of laser diode LD1 will experience a certain voltage drop compared to before MOS0 is closed. This may cause the EMF at the anode of the laser diode to be lower than the voltage of the power supply Vcc during the emission process.

[0084] For example, referring to Figure 3, when MOS0 is in the closed state, the potential difference (i.e., V) across the laser diode LD1 is... 10 -V 20 The voltage will rise to around 22V, and the laser diode LD will... n The potential difference between the two ends will fluctuate around 0V.

[0085] When it is necessary to stop the laser diode LD1 from emitting light, MOS0 can be controlled to switch from the closed state to the open state. When MOS0 is opened, its internal resistance will increase rapidly, and the potential difference across it will increase rapidly. Due to the unavoidable parasitic inductance in the circuit, the potential difference across MOS0 will be higher than before MOS0 was closed. Correspondingly, the electromotive force of the common cathode will be higher than before MOS0 was closed, and the laser diode LD1 will... n It will be subjected to a larger reverse voltage.

[0086] For example, referring to Figure 3, when MOS0 is turned off, the potential difference (i.e., V) across the laser diode LD1 is... 10 -V 20The voltage will rapidly change from approximately 22V to around -20V; that is, when MOS0 is disconnected, the electromotive force of the common cathode will rise rapidly, causing the laser diode LD1 to experience a reverse voltage of approximately 20V. Similarly, the laser diode LD... n The potential difference between the two ends (i.e., V) 30 -V 20 The voltage will rapidly change from around 0V to around -46V, which is the voltage of the laser diode (LD). n It will be subjected to a reverse voltage of approximately 46V. This reverse voltage will eventually be discharged through leakage current, restoring the static equilibrium state (also known as steady state) until the laser diode LD1 emits light again. In steady state, the electromotive force fluctuations at various locations in the laser circuit are small or even unchanged; in this example, after MOS0 returns to the off state, the electromotive force in the circuit will gradually return to steady state, where the potential difference V is... 10 -V 20 Approximately 7V, potential difference V 30 -V 20 It is approximately -23V.

[0087] In a high-side gating-low-side driving scheme, during the emission of light by the selected laser (e.g., laser diode LD1), the unselected laser (e.g., laser diode LD1) emits light... n The laser will be subjected to a large reverse voltage for a long time. On the one hand, an excessive reverse voltage may cause the laser to break down. On the other hand, being subjected to a large reverse voltage for a long time may cause the laser's performance to degrade and reduce its lifespan.

[0088] Therefore, this application provides a laser emitting circuit that can effectively reduce the reverse voltage on the laser and effectively prevent the laser from being damaged due to reverse breakdown.

[0089] For example, FIG4 is a schematic diagram of a laser emitting circuit 300 provided in an embodiment of the present application.

[0090] The laser emitting circuit 300 (hereinafter referred to as circuit 300) may include n laser emitting channels. These n laser emitting channels can be connected to a common cathode, and a drive switch can connect the common cathode to ground. For example, referring to Figure 4, in the laser emitting circuit 300, channels 1 to n can be connected to a common cathode, which can be connected to ground via a drive switch. Furthermore, different channels can use the same type of laser, or they can use different types of lasers.

[0091] A single laser emission channel among n laser emission channels may include a laser and a gating circuit. In a single laser emission channel, the anode of the laser can be connected to a first power supply through the gating circuit, and the cathode of the laser can be connected to a common cathode. The gating circuit can be used to control the connection or disconnection between the laser and the first power supply. For example, referring to Figure 4, taking channel 1 as an example, channel 1 may include laser 1 and gating circuit 1. The cathode of laser 1 can be connected to the common cathode, and gating circuit 1 can connect the anode of laser 1 to the first power supply. Again, taking channel 1 in Figure 4 as an example, when gating circuit 1 is in the on state, laser 1 is connected to the first power supply; when gating circuit 1 is in the off state, laser 1 is disconnected from the first power supply. The on / off state of gating circuit 1 can be achieved by a switch in gating circuit 1; by controlling the on / off state of this gating switch, the connection or disconnection between laser 1 and the first power supply can be controlled.

[0092] The laser emitting circuit 300 may further include a first circuit, one end of which may be connected to a second power supply, and the other end of which may be connected to a node between the gating circuit and the laser (for ease of distinction, referred to as the first node). The first circuit may be a unidirectional conducting circuit, and its conduction direction may be the direction in which current flows from the second power supply to the first node; the output voltage of the second power supply may be less than the turn-on voltage of the laser.

[0093] For example, the first circuit can include components with unidirectional conductivity, such as diodes, transistors, and field-effect transistors. By including these unidirectional conductive components, the first circuit can achieve unidirectional conduction. As another example, assuming the turn-on voltage of lasers 1 to n is 10V, the output voltage of the second power supply can be 8V, 9V, or 9.2V. As yet another example, assuming the turn-on voltage of laser 1 is 10V, and the turn-on voltage of lasers 2 to n is 11V, in this case, when the output voltage of the second power supply is less than the minimum turn-on voltage among lasers 1 to n (i.e., 10V), even if the selection circuits 1 to n are all in the off state, lasers 1 to n will not emit laser light under the influence of the second power supply.

[0094] For example, referring to FIG4, one end of the unidirectional conduction circuit 1 can be connected to a node between the gating circuit 1 and the laser 1, and the other end can be connected to a second power supply; similarly, one end of the unidirectional conduction circuit 2 can be connected to a second power supply, and the other end can be connected to a node between the gating circuit 2 and the laser 2; and so on. In this example, unidirectional conduction circuits 1 to n can correspond to the first circuit described above.

[0095] Since one end of each of the unidirectional conducting circuits 1 to n is connected to the second power source, in some implementations, multiple circuits in the unidirectional conducting circuits 1 to n can share a single section of circuit. For example, referring to Figure 4, the unidirectional conducting circuits 1 to n can share a single section of circuit at the end closest to the second power source to reduce the total length of the circuit.

[0096] In practical implementation, the first power supply, the second power supply, and the third and fourth power supplies (described later) can be implemented using the same power supply or different power supplies. For example, the first power supply and the second power supply can be two different power supplies. Alternatively, the first power supply and the second power supply can correspond to different output terminals of the same power supply; this power supply can output different voltages at these two output terminals. Another example is that a power supply can be connected to a transformer circuit, which can have multiple output terminals to output different voltages; the aforementioned first power supply and second power supply can correspond to different output terminals of this transformer circuit.

[0097] In this embodiment, by providing a first circuit with unidirectional conduction, the anode of the laser can be connected to a second power supply. When the corresponding selection circuit of the laser is open, the electromotive force (EMF) at the anode of the laser will rise to near the output voltage of the second power supply. On one hand, when the EMF at the cathode of the laser (i.e., the EMF on the common cathode) increases due to the opening of the drive switch, the reverse voltage experienced by the laser will decrease accordingly because the anode of the laser can be connected to the second power supply. On the other hand, since the output voltage of the second power supply is less than the turn-on voltage of the laser, the laser will not emit light under the influence of the second power supply even if the first circuit is on. In this way, the reverse voltage experienced by the laser can be reduced, and the laser's light emission process can be avoided.

[0098] In some possible implementations, a single laser emission channel may also include an energy storage circuit; the energy storage circuit may be equipped with a capacitor to store electrical energy. One end of the energy storage circuit may be grounded, and the other end may be connected to a node between the gating circuit and the laser (for ease of distinction, denoted as the second node). For example, referring to Figure 4, taking channel 1 as an example, channel 1 may also include an energy storage circuit 1, one end of which may be grounded, and the other end of which may be connected to a node between the laser 1 and the gating circuit 1.

[0099] In some possible implementations, the difference between the output voltage of the second power supply and the turn-on voltage of the laser can be less than a certain threshold (for ease of distinction, denoted as the fifth threshold). For example, this fifth threshold can be 0.8V. Or, for another example, it can be 1V. Or, in a specific implementation, this fifth threshold can be set according to the specific circumstances of the laser emitting circuit.

[0100] In a single laser emission channel, when the gating circuit within that channel is open, the electromotive force at the anode of the laser in that channel will be near the output voltage of the second power supply. Consequently, the smaller the difference between the output voltage of the second power supply and the turn-on voltage of the laser, the better the improvement effect on the reverse voltage experienced by the laser. In this embodiment, setting the difference between the output voltage of the second power supply and the turn-on voltage of the laser within a fifth threshold is beneficial for maintaining the reverse voltage experienced by the laser at a low level.

[0101] The laser emitting circuit 300 has been illustrated above with reference to Figure 4. The implementation of the first circuit and the selection circuit will be illustrated below with reference to Figure 5. In Figure 5, it is assumed that the first circuit achieves unidirectional conduction through a diode. The laser emitting circuit 400 shown in Figure 5 can be understood as an extension or variation of the laser emitting circuit 300.

[0102] For example, Figure 5 is a schematic diagram of a laser emitting circuit provided in an embodiment of this application.

[0103] Referring to Figure 5, the laser emitting circuit 400 (hereinafter referred to as circuit 400) may include laser diodes LD1 to LD2. n Similar to circuit 200 shown in Figure 2, circuit 400 can employ a high-side gating and low-side driving configuration for the multiple laser diodes. Furthermore, based on circuit 200, circuit 400 can include unidirectional conduction circuits 1 to n. For example, one end of unidirectional conduction circuit 1 can be connected to a node between the gating switch S1 and the laser diode LD1, and the other end can be connected to the power supply V0; this unidirectional conduction circuit 1 can include a diode D1, the anode of which can be connected to the power supply V0. Similarly, one end of unidirectional conduction circuit n can be connected to the gating switch S1. n With laser diode LD n One of the nodes can be connected to the power supply V0.

[0104] In circuit 400, the output voltage of power supply V0 can be less than that of laser diodes LD1 to LD2. n The turn-on voltage. That is, for any channel, if the channel is not selected (i.e., the selector switch in that channel is in the open state), even if the drive switch is closed, the laser diode in that channel will not emit light under the influence of the power supply V0. For example, assume the laser diode LD... n The threshold voltage is 10V, and the output voltage of power supply V0 is 9V; at switch S n Even when MOS0 is in the on state, the laser diode LD is in the off state. n It will not emit light under the influence of power supply V0.

[0105] In Figure 5, power supply Vcc can correspond to the first power supply in Figure 4, and power supply V0 can correspond to the second power supply in Figure 4.

[0106] For example, circuit 400 can be an improvement on circuit 200 (denoted as improvement 1); in improvement 1, unidirectional conduction circuits 1 to n are added.

[0107] For ease of distinction, in the embodiments of this application, the electromotive force V is... ab The prefix "a" in the subscript indicates the location of the electromotive force (EMF) in the circuit, and the suffix "b" indicates the improvement scheme adopted by the circuit. Specifically, "a" of 1 indicates that the EMF is at the anode of laser diode LD1; "a" of 2 indicates that the EMF is at the cathode of laser diode LD1; and "a" of 3 indicates that the EMF is at the cathode of laser diode LD1. n The electromotive force (EMF) at the anode terminal. A value of 0 for "b" indicates that the circuit did not employ the improvement scheme (i.e., circuit 200); a value of 1 for "b" indicates that the circuit employed improvement scheme 1 (i.e., circuit 400); a value of 2 for "b" indicates that the circuit employed improvement scheme 2 (described later); a value of 3 for "b" indicates that the circuit employed improvement scheme 3 (described later); and a value of 4 for "b" indicates that the circuit employed improvement scheme 4 (described later). For example, the EMF V... 10 This can be represented by the electromotive force (EMF) at the anode of the laser diode LD1 in circuit 200; the EMF V 11 This can represent the electromotive force (EMF) at the anode of the laser diode LD1 in circuit 400. The representation of EMF is explained uniformly here and will not be discussed separately later.

[0108] The following description, using Figures 6 and 7 as examples, illustrates the changes in electromotive force (EMF) in the circuit before and after implementing improvement scheme 1, taking the light emission process of laser diode LD1 as an example. Figures 6 and 7 correspond to the same test scenario. Figure 6 shows the changes in EMF at various locations in the circuit, while Figure 7 shows the changes in the potential difference across some components.

[0109] In the test scenarios shown in Figures 6 and 7, similar to the test scenario in Figure 3, it is still assumed that the power supply Vcc is 30V. Additionally, due to the addition of unidirectional conduction circuits 1 to n in Improvement Scheme 1, this test scenario also assumes that the power supply V0 is 9V, and the laser diodes LD1 to LD2 are... n The turn-on voltage is 10V.

[0110] Before MOS0 is closed, for channel 1, in the circuit employing improved scheme 1 (i.e., circuit 400), the potential difference (i.e., V) across the laser diode LD1 is... 11 -V 21 The voltage is approximately 7V, and the potential difference across MOS0 is approximately 23V; this is similar to the case without the improved solution, as shown in Figure 7. For unselected channels (e.g., channel n), in the circuit using improved solution 1, the laser diode LD... n The anode of the laser diode LD will be able to be connected to the power supply V0 via a unidirectional conduction circuit n; compared to the case without the improved solution, the laser diode LD n The electromotive force at the anode will be approximately 0V (refer to V in Figure 6). 30 Increase to around 9V (refer to V in Figure 6) 31 Accordingly, after adopting improvement scheme 1, the laser diode LD n The potential difference between the two ends will be around -23V, which was the value before the improvement (see V in Figure 7). 30 -V 20 The voltage changes to approximately -14V (refer to V in Figure 7). 31 -V 21 Laser diode (LD) n The voltage drop due to the reverse voltage is approximately 9V, which is close to the voltage of the power supply V0.

[0111] When MOS0 is closed, in the circuit using improved scheme 1, the voltage across MOS0 will rapidly drop to 0, and the voltage across the laser diode LD1 (refer to V in Figure 7) will decrease. 11 -V 21 The voltage will rise to around 22V, similar to the situation without the improvement measure (see V in Figure 7). 10 -V 20 Furthermore, in the circuit employing improved solution 1, due to the laser diode LD... n The power supply terminal can be connected through diode D n Connected to power supply V0, laser diode LD n The electromotive force at the anode will remain around 9V (see V in Figure 6). 31 Furthermore, compared to the case where no improvement measures were adopted (see V in Figure 6), 30 Laser diode LD n The fluctuation of the electromotive force at the anode will be smaller.

[0112] When MOS0 is disconnected, in the circuit using improved scheme 1, the electromotive force at the anode of laser diode LD1 will oscillate continuously until it returns to its equilibrium state, that is, returns to about 30V (refer to V in Figure 6). 11Similar to the case where no improvement measures were adopted. Laser diode (LD) n The electromotive force at the anode will oscillate at around 9V and then remain at around 9V (refer to V in Figure 6). 11 Accordingly, after adopting improvement scheme 1, the laser diode LD n The potential difference between the two ends will be reduced from approximately -46V before the improvement (see V in Figure 7). 30 -V 20 The voltage rises to around -37V (refer to V in Figure 7). 31 -V 21 That is, laser diode (LD). n The reverse voltage across the terminals will drop from approximately 46V to approximately 37V, with the magnitude of the voltage drop being similar to that of the power supply V0.

[0113] In the test scenarios shown in Figures 6 and 7 above, it is assumed that the output voltage of power supply V0 is 9V. If the output voltage of power supply V0 is reduced from 9V to 6V, when MOS0 is disconnected, the laser diode LD... n The reverse voltage across the terminals will be around 40V; under these conditions, the laser diode LD... n Although the reverse voltage is lower than the unimproved 46V, it will still be higher than the scheme shown in Figure 7 (around 37V). In other words, the closer the output voltage of the power supply V0 is to the laser diode LD... n The higher the turn-on voltage, the better it will have an effect on reducing the reverse voltage experienced by the laser diode.

[0114] The above, with reference to Figures 4 to 7, introduces a scheme for reducing the reverse voltage of a laser. The following, with reference to Figures 8 to 11, introduces another scheme for reducing the reverse voltage of a laser. These different schemes for reducing the reverse voltage of a laser can be implemented independently or in combination; this application does not limit this approach.

[0115] For example, Figure 8 is a schematic diagram of another laser emitting circuit provided in an embodiment of this application.

[0116] The laser emitting circuit 500 (hereinafter referred to as circuit 500) may include a drive switch and n laser emitting channels. Similar to circuit 300, in laser emitting circuit 500, the n laser emitting channels can be connected to a common cathode, and the drive switch can connect the common cathode and ground. Moreover, in a single laser emitting channel, the anode of the laser can be connected to a first power supply through a gating circuit, and the cathode of the laser can be connected to a common cathode. The gating circuit can be used to control the connection or disconnection between the laser and the first power supply.

[0117] The laser emitting circuit 500 may further include a second circuit, one end of which can be connected to a common cathode, and the other end of which can be connected to a third power supply. The second circuit can be used to limit the current flow from the common cathode to the third power supply when the electromotive force of the common cathode is in a steady state.

[0118] The output voltage of the third power supply can be greater than a first threshold and less than a second threshold. The first threshold can be the steady-state electromotive force of the common cathode when the second circuit is in the off state; the second threshold can be the peak electromotive force of the common cathode when the second circuit is in the off state.

[0119] For example, the electromotive force (EMF) at a certain location in a circuit being in a steady state (or static) can include: the EMF at that location having small fluctuations (e.g., less than a certain threshold) or even no fluctuations when the state of the circuit does not change. Accordingly, the EMF at that location in a steady state can be called the steady-state EMF (or static) at that location.

[0120] For the common cathode, the electromotive force (EMF) cannot be in a steady state when the laser is emitting light. The common cathode can be in a steady state when the drive switch is off and at least one gating circuit is on. That is, the first threshold can be the steady-state EMF of the common cathode when the second circuit is off, the drive switch is off, and at least one gating circuit is on.

[0121] For example, taking Figure 3 as an example, before closing MOS0, the laser diode LD1 and LD n The electromotive force at both ends is almost constant; correspondingly, the laser diode LD1 and LD2... n The potential difference between the two ends (i.e., the potential difference V) 10 -V 20 and potential difference V 30 -V 20 There is almost no fluctuation; in this case, the electromotive force V at the anode of the laser diode LD1 can be considered to be... 10 The electromotive force V at the cathode of laser diode LD1 20 (i.e., the electromotive force of the common cathode) and the laser diode LD n The extreme electromotive force V of the positive electrode 30 Both are in a stable state. For example, in Figure 3, after MOS0 is disconnected, laser diodes LD1 and LD... n The electromotive force at both ends will slowly recover to a steady state.

[0122] For example, assuming the second circuit is in the off state, the steady-state electromotive force of the common cathode is 23V, and the peak electromotive force of the common cathode is 46V; that is, assuming the first threshold is 23V and the second threshold is 46V. In this case, the output voltage of the third power supply can be set between 23V and 46V, for example, 24V or 30V.

[0123] In this embodiment, since the second circuit can limit the current from the common cathode to the third power supply when the electromotive force of the common cathode is in a steady state, the arrangement of the second circuit will not interfere with the normal light emission process of the laser. In addition, since the second circuit connects the common cathode and the third power supply, when the electromotive force of the common cathode exceeds the third power supply due to the parasitic inductance of the circuit, the current can flow from the common cathode to the third power supply, thereby reducing the electromotive force of the common cathode and thus reducing the reverse voltage on the laser.

[0124] Furthermore, assuming the first threshold is 23V and the second threshold is 46V, if the output voltage of the third power supply is 30V, the voltage of the common cathode must be at least 30V for the second circuit to discharge pressure from the common cathode; if the output voltage of the third power supply is 24V, the second circuit can discharge pressure from the common cathode if the voltage of the common cathode exceeds 24V.

[0125] In some possible implementations, the difference between the output voltage of the third power supply and the first threshold can be less than or equal to a certain threshold (for ease of distinction, denoted as the third threshold). For example, the third threshold could be 1V. Or, for example, the third threshold could be 2V. Or, in a specific implementation, the third threshold can be set according to the specific requirements of the laser emitting circuit.

[0126] When current flows through the second circuit to the third power supply, the greater the difference between the output voltage of the third power supply and the peak electromotive force (i.e., the smaller the difference between the peak and steady-state electromotive force), the faster the common cathode will depressurize. In this embodiment, the difference between the output voltage of the third power supply and the first threshold is set within the third threshold. On the one hand, this helps to maintain the reverse voltage on the laser at a low level; on the other hand, it also ensures the depressurization speed of the common cathode.

[0127] In some possible implementations, the length of the second circuit can be less than or equal to 10 millimeters. For example, the length of the second circuit can be 8 millimeters or 5 millimeters.

[0128] When current flows from the second circuit to the third power source, the shorter the length of the second circuit, the faster the pressure relief rate of the common cathode will be. In this embodiment, the length of the second circuit is set within 10 millimeters to ensure the pressure relief rate of the common cathode.

[0129] In some embodiments, a capacitor may be included in the second circuit. When the electromotive force of the common cathode is in a steady state, the capacitor will be able to block the current flow; when the electromotive force of the common cathode fluctuates at a low frequency, the capacitor will be able to block the low-frequency current between the common cathode and the third power source. For example, the capacitance value of the capacitor may be 500 pF or 1000 pF.

[0130] In some embodiments, the second circuit may include a unidirectional conductive element. The conduction direction of this unidirectional conductive element can be the direction in which current flows from the common cathode to the third power source. For example, the second circuit may include a diode, the anode of which can be connected to the common cathode, and the cathode of which can be connected to the third power source. Further, the parasitic capacitance of the diode may be less than a certain threshold (for ease of distinction, denoted as the fourth threshold). For example, the fourth threshold may be 3pF. As another example, when the parasitic capacitance of the diode is less than or equal to 5pF, the second circuit can have better high-frequency response performance; if the electromotive force of the common cathode exceeds the output voltage of the third power source, the second circuit can quickly discharge voltage to the common cathode.

[0131] In other embodiments, the second circuit may include capacitors and unidirectional conductive elements.

[0132] In other embodiments, the second circuit may also include other electrical components, such as resistors, switching elements, etc.

[0133] The laser emitting circuit 500 has been illustrated above with reference to Figure 8. The implementation of the second circuit will be illustrated below with reference to Figure 9. The laser emitting circuit 600 shown in Figure 9 can be understood as an extension or variation of the laser emitting circuit 500.

[0134] For example, Figure 9 is a schematic diagram of a laser emitting circuit provided in an embodiment of this application.

[0135] Referring to Figure 9, the laser emitting circuit 600 (hereinafter referred to as circuit 600) may include laser diodes LD1 to LD2. n Similar to circuit 200 shown in Figure 2, circuit 600 can use a high-side gating and low-side driving method to configure the multiple laser diodes. Additionally, based on circuit 200, circuit 600 can include circuit 610. One end of circuit 610 can be connected to power supply V00, and the other end of circuit 610 can be connected to a common cathode.

[0136] In one design, circuit 610 may include a diode D0, and the conduction direction of diode D0 may be the direction in which current flows from the common cathode to the power supply V00, as shown in Figure 9.

[0137] In the circuit shown in Figure 9, the output voltage of power supply V00 can be greater than the steady-state electromotive force (EMF) of the common cathode when circuit 610 is in the off state, switch S1 is in the on state, and MOS0 is in the off state; the output voltage of power supply V00 can be less than the peak EMF of the common cathode when circuit 610 is in the off state. For example, a switch can be provided in circuit 610 to control the on and off states of circuit 610; this switch can be set to the off state to detect the peak EMF of the common cathode when circuit 610 is in the off state. Alternatively, by removing diode D0 from circuit 610, circuit 610 can be made to be in the off state, thereby enabling the detection of the peak EMF of the common cathode when circuit 610 is in the off state.

[0138] In Figure 9, power supply Vcc can correspond to the first power supply in Figure 8, and power supply V00 can correspond to the third power supply in Figure 8. For example, suppose the peak electromotive force of the common cathode is 46V when circuit 610 is in the off state, and suppose the steady-state electromotive force of the common cathode is 23V when circuit 610 is in the off state, switch S1 is in the on state, and MOS0 is in the off state; in this case, the voltage of power supply V00 can be between 23V and 46V, such as 24V, 26V, or 30V.

[0139] For example, circuit 600 can be an improvement on circuit 200 (denoted as improvement 2); in improvement 2, circuit 610 is added.

[0140] The following description, using Figures 10 and 11 as examples, illustrates the changes in electromotive force (EMF) in the circuit before and after implementing improvement scheme 2. Figures 10 and 11 correspond to the same test scenario. Figure 10 shows the changes in EMF at various locations in the circuit, while Figure 11 shows the changes in the potential difference across some components.

[0141] In the test scenarios shown in Figures 10 and 11, the same as in Figure 3, it is still assumed that the power supply Vcc is 30V; in addition, since the improvement scheme 2 adds circuit 610, it is also assumed that the power supply V00 is 24V in this test scenario.

[0142] Before MOS0 is closed, in the circuit employing improved scheme 2 (i.e., circuit 600), the electromotive force (i.e., V) at the anode of laser diode LD1 is... 12 The electromotive force (V) at the cathode of laser diode LD1 22 ) and laser diode LD n The electromotive force at the anode (i.e., V) 32 Similar to the case without the improvement scheme, as shown in Figure 10; that is, the electromotive force V 32 With V30 Similar, electromotive force V 22 With V 20 Similar, electromotive force V 12 With V 10 Similar. In the circuit using improved scheme 2, the potential difference (i.e., V) across the laser diode LD1 is similar. 12 -V 22 Laser diode LD n The potential difference between the two ends (i.e., V) 32 -V 22 The changes are similar to those in the case where no improvement measures were adopted, as shown in Figure 11.

[0143] At this stage, the electromotive force of the common cathode is in a steady state, which is (see V in Figure 10). 20 and V 22 The voltage is approximately 23V. Since the voltage of the power supply V00 (i.e., 24V) is higher than the electromotive force of the common cathode, the diode D0 will not conduct at this time, and the current will not flow from the common cathode to the power supply V00.

[0144] When MOS0 is closed, in the circuit using improved scheme 2, the voltage across MOS0 will rapidly drop to 0, and the voltage across the laser diode LD1 (refer to V in Figure 11) will decrease. 12 -V 22 The voltage will rise to around 22V, similar to the situation without the improvement measure (see V in Figure 11). 10 -V 20 Referring to Figure 10, when MOS0 is in the closed state, in the circuit employing improved scheme 2 (i.e., circuit 600), the electromotive force at the anode of laser diode LD1, the electromotive force at the cathode of laser diode LD1, and the electromotive force at the cathode of laser diode LD1 are... n The electromotive force at the anode is similar to that in the case without the improvement scheme. At this stage, the electromotive force of the common cathode is still less than that of the power supply V00, the diode D0 is still not conducting, and the current still does not flow from the common cathode to the power supply V00.

[0145] When MOS0 is disconnected, the potential difference across MOS0 (refer to V in Figure 11) is as follows: for the circuit using Improved Solution 2 and the circuit without Improved Solution 2. 30 -V 20 V 32 -V 22 The voltage will drop rapidly from around 0V to around -46V, and the electromotive force of the common cathode (see V in Figure 10) will decrease accordingly. 20 V 22 The voltage will rapidly increase to over 40V. For circuits without the improvement scheme, the electromotive force of the common cathode (see V in Figure 10) will be... 20It will be difficult to discharge quickly, laser diode LD n The reverse voltage received (see V in Figures 11 and 3) 30 -V 20 The current will be slowly discharged as a leakage current. For the circuit using Improvement Scheme 2, the electromotive force at the common cathode (see V in Figure 10) will be... 22 When the electromotive force exceeds the power supply V00 (i.e., 24V), diode D0 will conduct, causing the electromotive force of the common cathode to rapidly decrease to around 24V; correspondingly, the laser diode LD... n The potential difference between the two ends will change from about -46V before the improvement to about -24V, that is, the reverse voltage on the laser diode will decrease from about 46V to about 24V.

[0146] In the test scenarios shown in Figures 10 and 11 above, assume the output voltage of power supply V00 is 24V. If the voltage of power supply V00 is increased from 24V to 30V, when MOS0 is disconnected, the electromotive force (EMF) of the common cathode will rapidly increase to over 40V. Subsequently, after diode D0 turns on, the EMF of the common cathode will rapidly decrease to around 30V. Correspondingly, the laser diode LD... n The reverse voltage at this point (around 30V) is lower than the previous 46V, but still higher than the scheme shown in Figure 11 (around 24V). In other words, the closer the output voltage of the power supply V00 is to the steady-state electromotive force of the common cathode, the better it is for reducing the LD voltage of the laser diode. n The more reverse voltage applied, the better the effect.

[0147] In another design approach, diode D0 in circuit 610 can be replaced with a capacitor. In the test scenarios of Figures 10 and 11, before MOS0 is closed, if circuit 610 is in the open state, the steady-state electromotive force (EMF) of the common cathode will be approximately 23V. If circuit 610 is not closed, under the influence of power supply V00, the steady-state EMF of the common cathode may increase, for example, to approximately 24V. When MOS0 is opened, the EMF of the common cathode will rapidly increase and exceed power supply V00. The changing current on the common cathode will flow through circuit 610 to power supply V00, causing the EMF on the common cathode to decrease to approximately 24V.

[0148] The above, in conjunction with Figures 8 to 11, introduces a scheme to reduce the reverse voltage of a laser. In practice, this scheme can be implemented alone, or it can be combined with other schemes to reduce reverse voltage.

[0149] The control circuit 210 for driving the switch was not described in detail in the above description of the circuits shown in Figures 2, 5 and 9. The circuit 210 will be described in illustrative form below with reference to Figure 12.

[0150] For example, FIG12 is a schematic diagram of a control circuit for driving a switch provided in an embodiment of this application. The control circuit 210 can be used to control the closing and opening of the drive switch.

[0151] Referring to Figure 12, the control circuit 210 may include a pull-up control circuit and a pull-down control circuit. One end of the pull-up control circuit can be connected to the power supply Vdd, and the other end can be connected to the control terminal of MOS0; one end of the pull-down control circuit can be connected to the ground wire, and the other end can be connected to the control terminal of MOS0. When the pull-up control circuit is in the on state and the pull-down control circuit is in the off state, the control terminal of MOS0 will be connected to the power supply Vdd; when the pull-up control circuit is in the off state and the pull-down control circuit is in the on state, the control terminal of MOS0 will be connected to the ground wire. In the control circuit 210, by setting the state of the pull-up control circuit and the pull-down control circuit, the on and off states of the drive switch MOS0 can be controlled.

[0152] For example, the control circuit 210 can be applied to circuits 200, 400 and 600. The control circuit 210 can control the opening and closing of MOS0, thereby obtaining the change of electromotive force in the circuits shown in Figures 3, 6, 7, 10 and 11.

[0153] The control circuit 210 for driving switches used in circuits 200, 400, and 600 has been described above with reference to Figure 12. The following, with reference to Figures 13 to 16, introduces another scheme to reduce the reverse voltage of the laser.

[0154] For example, Figure 13 is a schematic diagram of another laser emitting circuit provided in an embodiment of this application.

[0155] The laser emitting circuit 700 (hereinafter referred to as circuit 700) may include a drive switch and n laser emitting channels. Similar to circuit 300, in laser emitting circuit 700, the n laser emitting channels can be connected to a common cathode, and the drive switch can connect the common cathode and ground. Moreover, in a single laser emitting channel, the anode of the laser can be connected to a first power supply through a gating circuit, and the cathode of the laser can be connected to a common cathode. The gating circuit can be used to control the connection or disconnection between the laser and the first power supply.

[0156] The laser emitting circuit 700 may further include a control circuit 710 (referred to as circuit 710) for driving a switch. Circuit 710 may include a pull-down control circuit 711, which may have a first impedance. The pull-down control circuit 711 may be connected to the control terminal of the drive switch and the ground wire.

[0157] In one example, this first impedance can be achieved using an inductor.

[0158] In another example, this first impedance can be achieved using a resistor. For example, the resistance value could be 10 or 15 ohms.

[0159] For example, circuit 710 may further include pull-up control circuit 712, which can be connected to the control terminal of the drive switch and the fourth power supply. Pull-down control circuit 711 and / or pull-up control circuit 712 may be equipped with switches to control the on / off state of the circuit containing the switch. For example, pull-down control circuit 711 may be equipped with a pull-down control switch, which, when closed, connects the control terminal of the drive switch to ground. As another example, pull-up control circuit 712 may be equipped with a pull-up control switch, which, when closed, connects the control terminal of the drive switch to the fourth power supply.

[0160] Referring to Figure 14, and assuming the first impedance is a resistor, the following example illustrates how the first impedance can be implemented.

[0161] For example, FIG14 is a schematic diagram of a laser emitting circuit provided in an embodiment of this application. The laser emitting circuit 800 shown in FIG14 can be understood as an extension or modification of the laser emitting circuit 700.

[0162] Referring to Figure 14, the laser emitting circuit 800 (hereinafter referred to as circuit 800) may include laser diodes LD1 to LD2. n Similar to circuit 200 shown in Figure 2, circuit 800 can use a high-side gating and low-side driving method to configure the multiple laser diodes. Unlike circuit 200, circuit 800 does not use control circuit 210 to control the opening and closing of MOS0; instead, control circuit 810 controls the opening and closing of MOS0. Compared to circuit 210, control circuit 810 includes a resistor R1 in the pull-down control circuit of MOS0.

[0163] In Figure 14, power supply Vcc can correspond to the first power supply in Figure 13, and power supply Vdd can correspond to the fourth power supply in Figure 13.

[0164] For example, circuit 800 can be an improvement of circuit 200 (denoted as improvement 3); in improvement 3, a resistor R1 is added to the pull-down control circuit of MOS0.

[0165] The following description, using Figures 15 and 16 as examples, illustrates the changes in electromotive force (EMF) in the circuit before and after implementing improvement scheme 3. Figures 15 and 16 correspond to the same test scenario. Figure 15 shows the changes in EMF at various locations in the circuit, while Figure 16 shows the changes in the potential difference across some components.

[0166] In the test scenarios shown in Figures 15 and 16, the same as in Figure 3, it is still assumed that the power supply Vcc is 30V.

[0167] Before disconnecting MOS0, in the circuit employing improved scheme 3 (i.e., circuit 800), the electromotive force (i.e., V) at the anode of laser diode LD1 is... 13 The electromotive force (V) at the cathode of laser diode LD1 23 ) and laser diode LD n The electromotive force at the anode (i.e., V) 33 Similar to the case without the improved solution, as shown in Figure 15; in the circuit using improved solution 3, the potential difference (i.e., V) across the laser diode LD1 is... 13 -V 23 Laser diode LD n The potential difference between the two ends (i.e., V) 33 -V 23 The changes are similar to those in the case where no improvement measures were adopted, as shown in Figure 16.

[0168] Because parasitic inductance is unavoidable in the circuit, the change in current in the circuit when MOS0 is turned off will generate a corresponding induced electromotive force (EMF), causing the EMF of the common cathode to be potentially higher than before MOS0 is turned on. When MOS0 is turned off, for the circuit using Improvement Scheme 3, the presence of resistor R1 in the pull-down control circuit of MOS0 reduces the rate of change of current in the pull-down control circuit, and correspondingly reduces the rate of change of current in the main loop (e.g., the current flowing from the common cathode to MOS0). Since the induced EMF generated by the parasitic inductance is related to the rate of change of current, reducing the rate of change of current in the main loop can reduce the induced EMF generated by the parasitic inductance. Referring to Figure 15, for the circuit using Improvement Scheme 3, the EMF of the common cathode will be approximately 46V before the improvement (refer to V). 20 Reduce to around 30V (refer to V) 23 Accordingly, referring to Figure 16, the laser diode LD n The voltage across the terminals will be around -46V, which was the previous value (refer to V). 30 -V 20 The voltage changes to approximately -30V (refer to V). 33 -V23 Laser diode LD n The reverse voltage it receives drops to around 30V.

[0169] The above, with reference to Figures 4 to 16, introduces several methods to reduce the reverse voltage of a laser. In practical implementation, these methods can be implemented individually or in combination. The following, with reference to Figures 17 to 20, provides illustrative examples of different combinations of methods.

[0170] For example, FIG17 is a schematic diagram of a laser emitting circuit provided in an embodiment of the present application. The circuit 1000 shown in FIG17 can be understood as a combination of laser emitting circuits 400, 600 and 800.

[0171] For example, circuit 1000 can be an improvement on circuit 200 (denoted as improvement 4). In improvement 4, unidirectional conduction circuits 1 to n and circuit 610 are added; in addition, control circuit 810 is used to control the closing and opening of MOS0.

[0172] The following description, using Figures 18 and 19 as examples, illustrates the changes in electromotive force (EMF) in the circuit before and after implementing improvement scheme 4. Figures 18 and 19 correspond to the same test scenario. Figure 18 shows the changes in EMF at various locations in the circuit, while Figure 19 shows the changes in the potential difference across some components.

[0173] In the test scenarios of Figures 18 and 19, the same test conditions as in the other test scenarios mentioned above were used; for example, it was assumed that the power supply Vcc was 30V and the output voltage of the power supply V0 was 9V.

[0174] Before MOS0 is closed, for channel 1, in the circuit employing improved scheme 4 (i.e., circuit 1000), the electromotive force (i.e., V) at the anode of laser diode LD1 is... 14 The electromotive force (V) at the cathode of laser diode LD1 24 ) and the potential difference (i.e., V) across the laser diode LD1. 14 -V 24 Similar to the case without the improvement scheme, as shown in Figures 18 and 19. For unselected channels (e.g., channel n), in the circuit using improvement scheme 4, the laser diode LD... n The electromotive force at the anode will increase from approximately 0V before the improvement (see V in Figure 18). 30 Increase to around 9V (refer to V in Figure 18) 34 Laser diode LD n The voltage across the terminals will be reduced from approximately -23V (as shown in Figure 19).30 -V 20 The voltage has been improved to around -14V (see V in Figure 19). 34 -V 24 Laser diode LD n The voltage drop due to the reverse voltage is approximately 9V. During this stage, the electromotive force of the common cathode is less than the power supply V00, and diode D0 is not conducting.

[0175] When MOS0 is closed, in both the circuit using improved scheme 4 and the circuit without improved scheme, the potential difference across MOS0 will rapidly decrease to 0, and the voltage at the anode of laser diode LD1 will decrease slightly (refer to V in Figure 18). 10 V 14 The voltage at its cathode will rapidly drop to around 0V (refer to V in Figure 18). 20 V 24 Correspondingly, the potential difference across the laser diode LD1 (refer to V in Figure 19) 10 -V 20 V 14 -V 24 The voltage will rise rapidly to around 22V. In the circuit using improved solution 4, due to the laser diode LD... n The anode of the laser diode LD can be connected to the power supply V0 through a unidirectional conduction circuit n. n Electromotive force at the anode (see V in Figure 18) 34 The voltage will remain around 9V. During this stage, the electromotive force of the common cathode is still less than the power supply V00, and the diode D0 is not conducting.

[0176] When MOS0 is turned off, in both the circuit using Improved Solution 4 and the circuit without Improved Solution 4, the internal resistance of MOS0 will increase rapidly, and the potential difference across it will increase rapidly. In the circuit using Improved Solution 4, on the one hand, due to the presence of resistor R1, the peak value of the electromotive force of the common cathode will increase from approximately 46V before improvement (see V in Figure 18). 20 The voltage drops to around 30V (refer to V in Figure 18). 24 Furthermore, when the electromotive force of the common cathode exceeds the power supply V00, diode D0 will conduct, causing the electromotive force of the common cathode to rapidly decrease to around 24V. On the other hand, due to the laser diode LD... n The anode of the laser diode LD can be connected to the power supply V0 through a unidirectional conduction circuit n. n The electromotive force at the anode will remain around 9V (see V in Figure 18). 34 Accordingly, referring to Figure 19, when MOS0 is disconnected, the laser diode LD... nThe reverse voltage received will be significantly reduced compared to before the improvement.

[0177] For example, FIG20 is a schematic diagram of a laser emitting circuit provided in an embodiment of the present application. The circuit 1200 shown in FIG20 can be understood as a combination of laser emitting circuits 400, 600 and 800.

[0178] Referring to Figure 20, circuit 1200 may include channels 1-a to na, and channels 1-b to nb, for a total of 2*n channels. Channels 1-a to na may each be equipped with a laser diode (LD). 1-a To LD n-a Channels 1-b to nb can each be equipped with a laser diode (LD). 1-b To LD n-b Laser diode LD 1-a To LD n-a The cathode can be connected to the common cathode a to drive the MOS switch. 0-a The common cathode a can be connected to the ground wire; similarly, the laser diode LD 1-b To LD n-b The cathode can be connected to the common cathode b to drive the MOS switch. 0- b It can connect the common cathode b to the ground wire.

[0179] For channels 1-a and 1-b, when the selector switch S1 is in the ON state, the laser diode LD... 1-a and LD 1-b It can be connected to the power supply Vcc. When the selector switch S1 is in the open state, the laser diode LD... 1-a and LD 1-b The connection to the power supply Vcc will be broken. Similarly, the strobe switch S... n Can control laser diode LD n-a and LD n-b The connection and disconnection between the power supply Vcc and the power source.

[0180] When the selector switch S1 is closed, if the closed MOS 0-a And disconnect the MOS 0-b Laser diode LD 1-a It will emit light, and the laser diode LD 1-b It will not emit light; if the MOS is disconnected... 0-a And close the MOS 0-b Laser diode LD 1-a It will not emit light, while the laser diode LD 1-b It will light up. This is achieved by controlling switches S1 to S2. n MOS 0-aand MOS 0-b It can control the emission of a single laser diode.

[0181] Similar to circuit 1000, in circuit 1200, the laser diode LD 1-a and LD 1-b The anode of the diode can be connected to the power supply V0 through the unidirectional conduction circuit containing diode D1; similarly, the laser diode LD n-a and LD n-b The anode can pass through diode D n The unidirectional conduction circuit is connected to the power supply V0.

[0182] Additionally, in circuit 1200, the common cathode a can be connected via diode D. 0-a The unidirectional conduction circuit is connected to power supply V00, and the common cathode b can be connected to diode D. 0-b The unidirectional conduction circuit it belongs to is connected to power supply V00. MOS 0-a A resistor R can be set in the pull-down control circuit. 1-a MOS 0-b A resistor R can be set in the pull-down control circuit. 1-b .

[0183] In one example, circuit 1200 can be understood as a combination of two circuits 1000. In specific implementations, three or even more circuits 1000 can be combined with each other as needed.

[0184] The laser emitting circuit provided in the embodiments of this application has been described above with reference to Figures 1 to 20.

[0185] This application also provides a detection device, which may include any of the laser emitting circuits shown in Figures 4 to 20. For example, the detection device may be a lidar.

[0186] In one design approach, a one-dimensional addressable flash lidar can employ the laser emitting circuit shown in Figure 17.

[0187] In another design approach, the two-dimensional addressing flash lidar can use the laser emitting circuit shown in Figure 20.

[0188] This application also provides an intelligent driving device, which may include any of the laser emitting circuits shown in Figures 4 to 20, or may include the detection device described above. For example, the intelligent driving device may be a vehicle.

[0189] The vehicles involved in this application embodiment can be vehicles in a broad sense, including transportation vehicles (such as commercial vehicles, passenger cars, motorcycles, flying cars, trains, etc.), industrial vehicles (such as forklifts, trailers, tractors, etc.), engineering vehicles (such as excavators, bulldozers, cranes, etc.), agricultural equipment (such as lawnmowers, harvesters, etc.), amusement equipment, toy vehicles, etc. This application embodiment does not specifically limit the type of vehicle. For example, the vehicles in this application can be hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), or new energy vehicles (NEV), etc.

[0190] The terminology used in the embodiments of this application is for the purpose of describing specific embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of this application, “at least one” and “one or more” refer to one, two, or more than two. The term “and / or” is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can indicate: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0191] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0192] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0193] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0194] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0195] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0196] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0197] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

A laser emitting circuit, characterized in that, The laser emitting circuit includes: n laser emitting channels and a first circuit; The n laser emission channels are connected to a common cathode, where n is a positive integer greater than 1; Each of the n laser emission channels includes a laser and a gating circuit; In the single laser emission channel, the anode of the laser is connected to the first power supply through the gating circuit, and the cathode of the laser is connected to the common cathode. The gating circuit is used to control the connection or disconnection of the laser and the first power supply. One end of the first circuit is connected to the second power supply, and the other end of the first circuit is connected to the first node between the gating circuit and the laser. The first circuit is a unidirectional conducting circuit, and the conduction direction of the first circuit is the direction in which the current flows from the second power supply to the first node. The output voltage of the second power supply is less than the turn-on voltage of the laser. The laser emitting circuit according to claim 1 is characterized in that, The laser emitting circuit also includes a second circuit. The second circuit connects the common cathode and the third power source, and the second circuit is used to limit the current from the common cathode to the third power source when the electromotive force of the common cathode is in a steady state; The output voltage of the third power supply is greater than the first threshold and less than the second threshold; Wherein, the first threshold is the steady-state electromotive force of the common cathode when the second circuit is in the off state and at least one of the gating circuits is in the on state and the drive switch is in the off state, the second threshold is the peak electromotive force of the common cathode when the second circuit is in the off state, and the drive switch is used to connect the common cathode and the ground wire. The laser emitting circuit according to claim 2 is characterized in that, The difference between the output voltage of the third power source and the first threshold is less than or equal to the third threshold. The laser emitting circuit according to claim 3 is characterized in that, The third threshold is less than or equal to 2 volts. The laser emitting circuit according to any one of claims 2 to 4 is characterized in that, The second circuit is equipped with a diode, the conduction direction of which is the direction in which the current flows from the common cathode to the third power source, and the parasitic capacitance of the diode is less than or equal to a fourth threshold. The laser emitting circuit according to claim 5 is characterized in that, The fourth threshold is less than or equal to 5 picofarads. The laser emitting circuit according to any one of claims 2 to 6 is characterized in that, The second circuit includes a capacitor. The laser emitting circuit according to any one of claims 2 to 7 is characterized in that, The length of the second circuit is less than or equal to 10 millimeters. The laser emitting circuit according to any one of claims 1 to 8 is characterized in that, The laser emitting circuit also includes a control circuit for the drive switch, the control circuit for the drive switch includes a pull-down control circuit, and the pull-down control circuit is provided with a first impedance. The laser emitting circuit according to claim 9 is characterized in that, The first impedance is a resistor. The laser emitting circuit according to any one of claims 1 to 10 is characterized in that, The difference between the output voltage of the second power supply and the turn-on voltage is less than or equal to the fifth threshold. The laser emitting circuit according to claim 11 is characterized in that, The fifth threshold is less than or equal to 1 volt. The laser emitting circuit according to any one of claims 1 to 12 is characterized in that, The single laser emission channel also includes an energy storage circuit with a capacitor. One end of the energy storage circuit is connected to the ground wire, and the other end of the energy storage circuit is connected to a second node between the laser and the gating circuit. A laser emitting circuit, characterized in that, The laser emitting circuit includes: n laser emitting channels and a second circuit; The n laser emission channels are connected to a common cathode, where n is a positive integer greater than 1; Each of the n laser emission channels includes a laser and a gating circuit; In the single laser emission channel, the anode of the laser is connected to a first power supply via a gating circuit, and the cathode of the laser is connected to the common cathode. The gating circuit is used to control the connection or disconnection of the laser and the first power supply. The second circuit connects the common cathode and the third power source, and the second circuit is used to limit the current from the common cathode to the third power source when the electromotive force of the common cathode is in a stable state; The output voltage of the third power supply is greater than the first threshold and less than the second threshold; Wherein, the first threshold is the steady-state electromotive force of the common cathode when the second circuit is in the off state and at least one of the gating circuits is in the on state and the drive switch is in the off state, the second threshold is the peak electromotive force of the common cathode when the second circuit is in the off state, and the drive switch is used to connect the common cathode and the ground wire. The laser emitting circuit according to claim 14 is characterized in that, The difference between the output voltage of the third power source and the first threshold is less than or equal to the third threshold. The laser emitting circuit according to claim 15 is characterized in that, The third threshold is less than or equal to 2 volts. The laser emitting circuit according to any one of claims 14 to 16 is characterized in that, The second circuit is equipped with a diode, the conduction direction of which is the direction in which the current flows from the common cathode to the third power source, and the parasitic capacitance of the diode is less than or equal to a fourth threshold. The laser emitting circuit according to claim 17 is characterized in that, The fourth threshold is less than or equal to 5 picofarads. The laser emitting circuit according to any one of claims 14 to 18 is characterized in that, The second circuit includes a capacitor. The laser emitting circuit according to any one of claims 14 to 19 is characterized in that, The length of the second circuit is less than or equal to 10 millimeters. A lidar, characterized in that Includes a laser emitting circuit as described in any one of claims 1 to 20. A vehicle characterized by comprising: It includes a laser emitting circuit as described in any one of claims 1 to 20, or it includes a lidar as described in claim 21.

Images