Lidar system using light sources of different wavelengths

Abstract

The present invention relates to a laser radar system, which can include: a transceiver that generates light of mutually different wavelengths, and receives reflected light of mutually different wavelengths reflected from a target; a beam splitter that relatively divides the light of mutually different wavelengths of the transceiver into long-wave light and short-wave light; and a scanning mirror that irradiates the long-wave light and the short-wave light classified in the beam splitter to the outside, and that causes the reflected light of the long-wave light and the short-wave light to be incident to the transceiver through the beam splitter.

Description

Technical Field

[0001] This invention relates to lidar systems, and to lidar systems that utilize lasers with different wavelengths. Background Technology

[0002] Typically, LiDAR (Light Detection and Ranging) is a technology that detects the distance to an object by measuring the time-of-flight (ToF) of a laser beam emitted from a transmitter, reflected by an object, and returning to the receiver.

[0003] In particular, lidar sensor modules can be used in autonomous vehicles, autonomous drones, and other applications to detect nearby obstacles.

[0004] LiDAR systems typically use a single wavelength of light source to scan the surrounding environment and receive reflected light of that single wavelength to detect nearby obstacles.

[0005] However, when other lidar systems are located nearby and each uses the same wavelength to detect obstacles, there is a possibility of operational interference with the lidar system.

[0006] That is, noise is generated in 3D point cloud data, which is a collection of points in three-dimensional (3D) space, reducing the signal-to-noise ratio (SNR), which may reduce the overall measurement distance or cause errors in recognition and other functions due to noise.

[0007] Furthermore, lidar systems with a single wavelength light source and a single receiving system require additional delay units or multiple comparison units to compensate for walk errors in the received signal. Therefore, more complex circuitry is required, along with units for signal processing compensation.

[0008] Therefore, there is a need to provide a unit that can prevent mutual interference caused by the use of multiple lidar systems and a technical unit that can simplify the circuit.

[0009] For lidar systems using multiple wavelengths, Korean Patent No. 10-2136402 (granted on July 15, 2020, entitled "Multi-wavelength image lidar sensing device and signal processing method thereof") has been proposed.

[0010] However, the aforementioned authorized patents use multi-wavelength lidar sensors to detect the distance and shape information of objects, and can obtain information such as the object's color and reflectivity, but they have the disadvantage of being unable to solve all the problems of the aforementioned single-wavelength lidar systems. Summary of the Invention

[0011] (a) Technical problems to be solved

[0012] The technical problem to be solved by the present invention, considering the problems described above, is to provide a lidar system that can prevent interference with other nearby lidar systems.

[0013] Furthermore, another problem that the present invention aims to solve is to provide a lidar system that prevents interference from occurring and does not use additional circuitry for interference compensation.

[0014] Meanwhile, the present invention provides a lidar system that reduces the power consumption of the lidar receiving circuit and minimizes the impact of electromagnetic interference (EMI).

[0015] (II) Technical Solution

[0016] The lidar system of the present invention for solving the problems described above may include: a transceiver unit that generates light of different wavelengths and receives reflected light of different wavelengths reflected from a target; a beam splitter that divides the light of different wavelengths from the transceiver unit into long-wavelength light and short-wavelength light; and a scanning mirror that illuminates the long-wavelength light and short-wavelength light classified in the beam splitter to the outside, and the reflected light of the long-wavelength light and short-wavelength light is incident on the transceiver unit through the beam splitter.

[0017] In an embodiment of the present invention, the beam splitter may include a first surface for reflecting the long-wavelength light and a second surface, located opposite the first surface, for reflecting the short-wavelength light.

[0018] In an embodiment of the present invention, the optical axis spacing between the long-wavelength light and the short-wavelength light can be adjusted by adjusting the thickness of the gap between the first surface and the second surface.

[0019] In embodiments of the present invention, the optical axis spacing may be proportional to the thickness.

[0020] In an embodiment of the present invention, the vertical divergence angle of the long-wavelength light may be smaller than that of the short-wavelength light.

[0021] In an embodiment of the present invention, in the transceiver unit, by controlling the delay of the triggering time of the long-wavelength light and the short-wavelength light, a new output light waveform can be generated by combining the waveforms of the long-wavelength light and the short-wavelength light.

[0022] In an embodiment of the present invention, the transceiver unit includes a unit array that converts reflected light into electrical signals, wherein multiple units of the unit array can respectively receive both long-wavelength reflected light and short-wavelength reflected light.

[0023] In embodiments of the present invention, the upper part of the above-mentioned unit array may include a filter for allowing long-wavelength reflected light and short-wavelength reflected light to pass through.

[0024] In an embodiment of the present invention, the transceiver unit includes a unit array that converts reflected light into electrical signals. The units located at the center of the unit array can receive both long-wavelength reflected light and short-wavelength reflected light, while the other units besides the units located at the center can receive short-wavelength reflected light.

[0025] In an embodiment of the present invention, under steady-state conditions, the time domains of the aforementioned long-wavelength light and the aforementioned short-wavelength light above the threshold voltage are designated as the reference time domain of the detection signal. The aforementioned lidar system may further include a processor that uses the ratio of the detected time domain to the aforementioned reference time domain as the level of the received signal decreases or increases to compensate for wander error.

[0026] In an embodiment of the present invention, the receiving circuit of the transceiver unit may include: a receiving unit configured with the same number of channels as the multi-channel lidar sensor for detecting light; and a timing control unit that enables the plurality of receiving units respectively, with a difference in the enabling time of each receiving unit.

[0027] In an embodiment of the present invention, the number of receiving units is N, which is an integer greater than or equal to 4. Each receiving unit includes a photodiode for detecting light and an amplification unit for amplifying the detection signal of the photodiode. The timing control unit can output a receiving enable signal to the enable terminal of each amplification unit of the plurality of receiving units.

[0028] In an embodiment of the present invention, the number of receiving units is N, which is an integer greater than or equal to 4. Each receiving unit includes a photodiode for detecting light and an amplification unit for amplifying the detection signal of the photodiode. The timing control unit outputs a receiving enable signal synchronized with the transmitting enable signal for outputting laser light to the enable terminal of the first amplification unit. The enabling timing of the plurality of receiving units can be controlled by N-1 delay units that are respectively connected to the enable terminal pairs of the plurality of amplification units.

[0029] In an embodiment of the present invention, the N aforementioned receive enable signals may be delayed in stages from the first receive enable signal to the Nth receive enable signal at a set time.

[0030] In an embodiment of the present invention, the N aforementioned receive enable signals may include: a first time period during which the aforementioned amplification unit is sequentially enabled; and a third time period during which the aforementioned amplification unit is sequentially disabled.

[0031] In an embodiment of the present invention, the N aforementioned receive enable signals include a second time period in which all the aforementioned amplification units are kept in an enabled state. The second time period may be shorter than the enable time period of one receive enable signal.

[0032] In an embodiment of the present invention, the second time period can be from the rising edge of the Nth receive enable signal to the falling edge of the first receive enable signal.

[0033] In an embodiment of the present invention, the N aforementioned receive enable signals include a fourth time period from the third time period to the beginning of the first time period of the next frame, during which all the aforementioned amplification sections can be kept disabled.

[0034] (III) Beneficial Effects

[0035] This invention uses two beams of light with different wavelengths. By adjusting the distance between the optical axes of the two beams, each lidar system has a unique emission pattern, thereby preventing interference with other adjacent lidar systems.

[0036] Furthermore, the present invention leaves differences in pulse width, intensity, and delay time between two beams of light with different wavelengths, thereby achieving the effect of avoiding interference.

[0037] As described above, the present invention prevents interference by adjusting the distance between the optical axes of long-wavelength light and short-wavelength light, thus compensating for wandering errors even without the use of additional components.

[0038] Furthermore, the emission of the light source in a single measurement is divided into long-wavelength light and short-wavelength light with a specified delay time. Therefore, the standard peak time of a single emission is relatively low, which has a more favorable effect on eye safety.

[0039] Furthermore, the present invention has the effect of reducing power consumption and minimizing the impact of electromagnetic interference by changing the configuration of the receiving circuit of the transceiver unit. Attached Figure Description

[0040] Figure 1 This is a structural diagram of a lidar system according to a preferred embodiment of the present invention.

[0041] Figure 2 This is a side view schematic diagram of the long-wavelength and short-wavelength light emitted from the lidar system of the present invention.

[0042] Figure 3 for Figure 2 A top-down view.

[0043] Figure 4 This is a diagram showing the arrangement of the receiving unit array used in this invention.

[0044] Figure 5 This is a waveform diagram illustrating an example of trigger timing control for short-wavelength and long-wavelength light.

[0045] Figures 6 to 8 These are waveform diagrams used to illustrate the walk error compensation for received signals in this invention.

[0046] Figure 9 This is a circuit diagram of the receiving circuit of the transceiver unit of the present invention.

[0047] Figure 10 for Figure 9 Timing diagram of the timing control unit receiving the enable signal.

[0048] Figure 11 This is a circuit diagram of a receiving circuit according to another embodiment of the present invention.

[0049] Figure 12 This is a simulation result diagram of the receiving circuit.

[0050] Explanation of reference numerals in the attached figures

[0051] 10: Transceiver Unit; 20: Lens Unit

[0052] 30: Beam splitter; 40: Incident lens

[0053] 50: Scanning mirror Detailed Implementation

[0054] Hereinafter, the lidar system of the present invention utilizing light sources of different wavelengths will be described in detail with reference to the accompanying drawings.

[0055] The embodiments of the present invention are provided to illustrate the invention more fully to those skilled in the art. The embodiments described below can be modified into several other forms, and the scope of the invention is not limited to the embodiments described below. Rather, these embodiments are provided to make the invention more complete and to fully convey the spirit of the invention to those skilled in the art.

[0056] The terminology used in this specification is for describing specific embodiments and does not limit the invention. As used herein, unless otherwise expressly indicated in the context, the singular form may include the plural form. Furthermore, as used herein, "comprise" and / or "comprising" are used to indicate the presence of a particular mentioned shape, number, step, operation, component, factor, and / or combination thereof, and do not exclude the presence or addition of more than one other shape, number, step, operation, component, factor, and / or group. As used herein, the term "and / or" includes all combinations of more than one of the corresponding listed items.

[0057] In this specification, terms such as "first," "second," etc., are used to describe various components, areas, and / or parts, but it is obvious that these components, elements, areas, multiple layers, and / or multiple parts are not limited to these terms. These terms do not indicate a specific order, hierarchy, or superiority, but are only used to distinguish one component, area, or part from other components, areas, or parts. Therefore, the first component, area, or part detailed below may refer to a second component, area, or part without departing from the teachings of this invention.

[0058] Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings, which briefly illustrate embodiments of the invention. In the drawings, for example, deformations of the illustrated shapes can be predicted based on manufacturing techniques and / or tolerances. Therefore, embodiments of the invention should not be construed as limited to specific shapes in the areas shown in this specification; for example, they should include shape variations due to manufacturing processes.

[0059] Figure 1 This is a structural diagram of a lidar system according to a preferred embodiment of the present invention.

[0060] Reference Figure 1 The present invention may include: a transceiver 10 that outputs laser light having relatively short and long wavelengths; a beam splitter 30 that separates the long and short wavelengths from the light incident on the transceiver 10 through the lens 20; and a scanning mirror 50 that reflects the long and short wavelengths of light separated in the beam splitter 30 through the incident lens 40 and emits the light to the outside.

[0061] The structure and function of the lidar system of the present invention, constructed as described above, will be explained in more detail below.

[0062] First, the transceiver unit 10 includes at least one light source, which may be omitted in the following description, but it is assumed to include a light receiving element.

[0063] The light source of the aforementioned transceiver unit 10 can be a single light source or multiple light sources that output long wavelengths and short wavelengths. In this case, long wavelength and short wavelength are relative concepts, and the specific wavelength range belongs to the wavelength range of laser.

[0064] In other words, short wavelengths can be used as long as their wavelength is shorter than that of long wavelengths.

[0065] The light source can be an edge-emitting laser (EEL), a vertical-cavity surface-emitting laser (VCSEL), or a microlens array (MLA).

[0066] Assume that the lens section 20 includes at least one lens and filter required for emitting and receiving light.

[0067] The light emitted from the light source of the transceiver unit 10, including both long-wavelength and short-wavelength light, is incident on the beam splitter 30 through the lens unit 20 and reflected by the beam splitter 30.

[0068] At this time, the beam splitter 30 reflects the light output from the light source of the transceiver 10 at a 90-degree angle, so that the long-wavelength light and the short-wavelength light move horizontally along each optical axis and are reflected in such a way that the distance between the optical axes is specified as t'.

[0069] The beam splitter 30 includes: a first surface 31 for reflecting long wavelengths; and a second surface 32 located on the opposite side of the first surface 31.

[0070] The aforementioned interaxial distance t' is determined based on the thickness t of the beam splitter 30 corresponding to the interval between the first surface 31 and the second surface 32.

[0071] The aforementioned inter-optical axis distance t' is proportional to the thickness t of the beam splitter 30.

[0072] For light including long wavelength and short wavelength with a length difference in relative wavelength, the long wavelength light is reflected from the first surface 31, which is the incident surface of the beam splitter 30, to the incident lens 40 side, and the short wavelength light is refracted by the first surface 31 and reflected by the second surface 32 to be incident on the incident lens 40.

[0073] At this point, the separated short-wavelength light and long-wavelength light are parallel to each other.

[0074] The separated long-wavelength and short-wavelength light are reflected by the scanning mirror 50 and emitted to the outside. In this invention, the long-wavelength light, which is beneficial to eye safety, can be used as the main beam, and the short-wavelength light can be used as the sub-beam.

[0075] The aforementioned scanning mirror 50 performs scanning by rotating to irradiate the set area with long-wavelength light and short-wavelength light, driven by a predetermined timing sequence.

[0076] The light emitted by the scanning mirror 50 is reflected by the surrounding objects. The reflected light is divided into long-wavelength light and short-wavelength light, which are received by the transceiver unit 10 in the opposite direction of the emission process.

[0077] Therefore, the position of an object can be detected.

[0078] The following is a more detailed explanation of the long-wavelength and short-wavelength light emitted by the scanning mirror 50.

[0079] Figure 2 This is a side view schematic diagram of the long-wavelength and short-wavelength light emitted from the lidar system 1 of the present invention. Figure 3 This is a top-down view.

[0080] Reference Figure 2 and Figure 3 Both long-wavelength and short-wavelength light can have the same basic driving state in their vertical divergence angle.

[0081] In the basic drive mode, receiving and transmitting have the same vertical viewing angle.

[0082] In addition to the basic driving force mentioned above, the detection distance can be increased by reducing the vertical divergence angle Tx_L of long-wavelength light and focusing it at the center viewpoint.

[0083] At this point, even if the vertical divergence angle Tx_L of the long-wavelength light is changed, the long-wavelength light is still beneficial to eye safety, and therefore, problems caused by light focusing do not occur.

[0084] Furthermore, although short-wavelength light is relatively less safe for the eyes, the sensor has excellent sensitivity, thus enabling scanning of a wide area over a short distance with a relatively wide vertical divergence angle Tx-S.

[0085] For this type of deformation-driven operation, the receiving vertical viewing angle Rx_V can increase with the increase of the vertical divergence angle Tx-S of the short-wavelength light. That is, the receiving vertical viewing angle Rx_V becomes the same angle as the vertical divergence angle Tx-S.

[0086] Furthermore, in the basic drive, the long-wavelength light and the short-wavelength light have the same divergence angle with the same field of view, pass parallel to each other through the beam splitter 30, and produce a difference of positive real number between the optical axes that is not 0.

[0087] Therefore, the horizontal viewing angle Rx_H is the angle between the horizontal divergence angle Tx_HS of long-wavelength light and the horizontal divergence angle Tx_HL of short-wavelength light and the optical axis.

[0088] In order to receive the reflected light of the present invention having the received vertical viewing angle Rx_V and the received horizontal viewing angle Rx_H as described above, a plurality of receiving unit arrays shall be provided in the transceiver unit 10.

[0089] Figure 4 This is a diagram showing the arrangement of the receiving unit array used in this invention.

[0090] like Figure 4 As shown, the multiple units constituting each receiving unit array can receive both long-wavelength reflected light and short-wavelength reflected light, and the resolution is determined according to the number of units.

[0091] Figure 4 This shows a row of cells arranged vertically. Figure 4Part (a) shows a cell in a basic driving state where the vertical divergence angle Tx_L of the long-wavelength light is the same as the vertical divergence angle Tx_S of the short-wavelength light, simultaneously receiving both long-wavelength and short-wavelength reflected light.

[0092] This is because the vertical divergence angle Tx_L of long-wavelength light and the vertical divergence angle Tx_S of short-wavelength light are the same as the receiving vertical viewing angle Rx_V.

[0093] Furthermore, in the deformation-driven state, the vertical divergence angle Tx_L of the long-wavelength light is narrower than the vertical divergence angle Tx_S of the short-wavelength light. At this time, as... Figure 4 In part (b), the central part of the unit array receives both long-wavelength and short-wavelength reflected light, while the side parts receive only short-wavelength reflected light.

[0094] Furthermore, preferably, in addition to the lens, a bandpass filter that allows both long and short wavelengths to pass through is applied to the lens section 20.

[0095] like Figure 4 In the case of part (b), in the case of a specific unit that receives short wavelengths, a filter that allows only short-wavelength reflected light to pass through can be applied to the upper part of the unit that receives its short wavelengths to improve the signal-to-noise ratio.

[0096] As described above, by adjusting the thickness of the beam splitter 30, a different optical signal from that of other adjacent lidar systems can be used, thus preventing interference with other adjacent lidar systems.

[0097] Furthermore, interference between lidar systems with the same distance between their optical axes can be prevented by changing the trigger time of long-wavelength and short-wavelength light.

[0098] Figure 5 This is a waveform diagram illustrating an example of trigger timing control for short-wavelength and long-wavelength light.

[0099] Reference Figure 5 This allows for larger vertical divergence angles (Tx_S) for short-wavelength light and smaller vertical divergence angles (Tx_L) for long-wavelength light. As mentioned above, this takes into account eye safety characteristics.

[0100] For example, short-wavelength light can have a width of 10 ns and long-wavelength light can have a width of 5 ns. The desired waveform can be generated and output by delaying the output of the long-wavelength light. The delay of the trigger time can be performed in the transceiver unit 10.

[0101] Therefore, the present invention can generate various forms of output light waveforms by triggering timing control, which also affects the reflected light that is reflected by the target and received by the lidar system.

[0102] As mentioned above, various reflected light waveforms can be used to distinguish it from other lidar systems, thereby preventing interference.

[0103] Figures 6 to 8 The following are waveform diagrams used to illustrate the received signal wander error compensation of the present invention. Figure 6 As the baseline value, Figure 7 For compensation when signal strength decreases, Figure 8 An example of compensation for saturation of long-wavelength reflected light is shown.

[0104] Reference Figure 6 The receiving unit array of the transceiver unit 10 outputs a voltage signal based on the reception of reflected light, and can detect the received waveform L of long-wavelength reflected light and the received waveform S of short-wavelength reflected light.

[0105] This allows for the setting of a threshold voltage Vth as the minimum detection voltage by detecting all signals without detecting the target. In other words, only voltages above the threshold voltage Vth in the long-wavelength received waveform L and the short-wavelength received waveform S are used as detection signals.

[0106] The first edge is the detection signal for the long-wavelength received waveform L, and the second edge is the detection signal for the short-wavelength received waveform S.

[0107] The voltage range above the threshold voltage of the long-wavelength received waveform is A, the rising range Tr(L) can be represented by B, and the falling range Tf(L) can be represented by C.

[0108] The rising interval Tr(L) is the interval from the threshold voltage Vth to the peak point of the long-wavelength received waveform L, and the falling interval Tf(L) is the interval from the peak point to the threshold voltage Vth.

[0109] The total time (T) is the time from the junction of the threshold voltage and the rising interval Tr(L) of the long wavelength received waveform to the junction of the falling interval Tr(S) of the short wavelength received waveform and the threshold voltage. The transmission delay time (TxDelay time, DS) is the time from the peak point of the long wavelength received waveform L to the peak point of the short wavelength received waveform S.

[0110] The transmission delay time DS is the delay time of the transceiver unit 10 described above, and can be regarded as a system constant.

[0111] Similarly, in the second edge, the interval between the rising interval Tr(S) of the short-wavelength received waveform S and the junction of the threshold voltage Vth and the falling interval Tf(S) and the junction of the threshold voltage Vth becomes the time D of the detection signal.

[0112] E and F represent the time from the junction of the rising interval Tr(S) and the threshold voltage Vth to the peak point of the short-wavelength received waveform S, and the time from the peak point to the point where the falling interval Tf(S) meets the threshold voltage Vth, respectively.

[0113] In the above, A, B, C, D, E, F, and T, excluding DS, are all detection values.

[0114] Figure 7 Showing the detection value compared to Figure 6 Examples of states that have decreased. That is, compared to Figure 6 The components A', B', C', D', E', and F' that constitute the detection signal are all reduced.

[0115] At this point, if we assume that the ratio of A' / A, which represents the time of the long-wavelength detection signal, is α, and the ratio of D' / D, which represents the time of the short-wavelength detection signal, is β, then both α and β become values ​​less than 1.

[0116] Using this reduction ratio, one can refer to the signal strength reduction. Figure 6 The waveform described is used to compensate for horizontal wander error. Preferably, the calculation is based on a longer wavelength with a fast rise time.

[0117] Figure 8 Showing with Figure 7 Conversely, in cases where the peak point becomes difficult to detect due to the increased waveform of the received signal, the ratio α of the lengths of the A' interval of the long-wavelength received waveform L in the saturated state is still calculated using the A interval of the long-wavelength received waveform L as the reference.

[0118] α can be a real number greater than 1, and the increase ratio of α at this time can be calculated.

[0119] Furthermore, using the D interval of the short-wavelength received waveform S as a reference, the ratio β of the lengths of the D' interval of the short-wavelength received waveform S in the saturated state can be obtained. In this case, β is a real number greater than 1, which can be used to obtain E', F', etc.

[0120] In the saturation state, compensation is preferably performed using β. This is because the peak height is relatively low, and therefore, the correction value is obtained using the short-wavelength received waveform S that maintains linearity.

[0121] Furthermore, preferably, the transmission delay time DS is set such that the crossover point in the attached figure is below the threshold voltage Vth.

[0122] As described above, the present invention is characterized by the ability to compensate for errors in the received waveform using two output beams of different wavelengths, even without the use of additional compensation circuitry, thereby simplifying the circuitry.

[0123] Although this compensation process is not shown in the accompanying drawings, it can be performed in a processor that interprets the received signal used for compensation.

[0124] Figure 9 This is a circuit diagram of the receiving circuit of the multi-channel lidar used in this invention. Figure 10 for Figure 9 Timing diagram of the timing control unit receiving the enable signal.

[0125] Refer to each Figure 9 and Figure 10 The present invention includes: N receiving units 110-1 to 110-n, each forming a channel for receiving laser light reflected by an object; and a timing control unit 120 for controlling the enabling state of each of the receiving units 110-1 to 110-n.

[0126] The receiving units 110-1 to 110-n described above can each have the same structure. For example, they may include: a photodiode PD for receiving laser light reflected by an object; an amplification unit TIA for amplifying the output of the photodiode PD by enabling control through the receiving enable signal RXE of the timing control unit 120; and an analog-to-digital converter ADC for converting the output of the amplification unit TIA into a digital signal.

[0127] The number of channels in the lidar receiving circuit is determined based on the numbers of receiving units 110-1 to 110-n.

[0128] The timing control unit 120 provides different timing receive enable signals RXE#1 to RXE#N to the enable terminal EN of the amplifier TIA provided in the receiver 110-1 to 110-n for forming each multi-channel receiver, and may include multiple switching circuits.

[0129] like Figure 10 As shown, the multiple receive enable signals RXE#1 to RXE#N provided from the timing control unit 120 have high potential intervals of the same length (same period) and are input to the enable terminal EN of the amplification section TIA of each receiver 110-1 to 110-n with a time delay that is the same as the delay time set sequentially.

[0130] The present invention utilizes the received enable signal to control the enable state of the amplifier TIA. The amplifier TIA is enabled in the high potential range of the received enable signal RXE#1 to RXE#N, and disabled and does not operate in the low potential range (disable range).

[0131] In the above, N or n is a positive integer. Considering a multi-channel LiDAR, which has at least 4 channels, N or n is an integer of 4 or more.

[0132] Therefore, the present invention ensures that the amplification section TIA does not consume power in the disabled region, thereby reducing power consumption. Furthermore, since the power supply is not turned on and off simultaneously, the occurrence of electromagnetic interference can be minimized.

[0133] The receiving enable signals RXE#1 to RXE#N of the timing control unit 120 can be divided into four timing intervals for explanation.

[0134] Refer again Figure 10 Within a specified time, a transmit enable signal TXE is output, and simultaneously, a first receive enable signal RXE#1 is input to the enable terminal of the amplification section TIA of the first receiving section 110-1 to amplify the light receiving signal of the photodiode PD, and then convert it into a digital signal in the analog-to-digital converter ADC for output.

[0135] After that, after the set time, a second receive enable signal RXE#2 is input to the enable terminal of the amplifier section TIA of the second receiver 110-2, thereby enabling the receiver 110-2, which is the second channel, to operate.

[0136] The process described above is repeated sequentially. Finally, the Nth receive enable signal RXE#N is input to the amplification section TIA of the Nth receiver 110-n, and light can be detected by the receiver 110-n, which is the Nth channel.

[0137] As described above, the period from the rising edge of the first receive enable signal RXE#1 to the rising edge of the Nth receive enable signal RXE#N is defined as the first time period T1. The first time period T1 is the interval in which each receiving unit 110-1 to 110-n is enabled by the timing control unit 120 with a time difference.

[0138] That is, it can be understood that multiple channels of the multi-channel lidar receiving circuit are turned on sequentially, thus minimizing the generation of electromagnetic interference.

[0139] Then, the second time period T2 is actually shorter than the high-potential interval of a receive enable signal. At this time, it is the receive signal waiting time used to calculate the distance to the object detected by the lidar sensor.

[0140] The second time period T2 begins with the rising edge of the Nth receive enable signal RXE#N and ends with the falling edge of the first receive enable signal RXE#1.

[0141] Next, the third time period T3, from the falling edge of the first receive enable signal RXE#1 to the falling edge of the Nth receive enable signal RXE#N, is the interval during which the N receiving units 110-1 to 110-n constituting each channel are turned off with time differences.

[0142] At this time, electromagnetic interference can also be minimized by preventing rapid power conversion.

[0143] After all receivers 110-1 to 110-n are turned off, a fourth time period T4 is maintained to keep receivers 110-1 to 110-n in a turned-off state until the transmit enable signal TXE is output in the next frame.

[0144] During the fourth time period T4, all receiving units 110-1 to 110-n are in a turned-off state, thus reducing power consumption.

[0145] Therefore, the present invention can reduce power consumption and prevent overheating in multi-channel lidar receiving circuits, and can minimize the occurrence of electromagnetic interference through sequential enable control.

[0146] Figure 11 The circuit diagram of the receiving section of the transceiver unit 10 of a multi-channel lidar according to another embodiment of the present invention is shown.

[0147] Reference Figure 11 For those referenced in the above text Figure 9 In the configuration described, the timing control unit 120 outputs a receive enable signal RXE#1 based on the transmit enable signal.

[0148] Delay units 130-1 to 130-n-1 are connected in series between the enable terminals EN of the multiple amplifier units TIA in each receiver unit 110-1 to 110-n.

[0149] That is, the first delay section 130-1 is used to connect the enable terminal of the amplification section TIA of the first receiving section 110-1 with the enable terminal of the amplification section TIA of the second receiving section 110-2.

[0150] Furthermore, the second delay section 130-2 is used to connect the enable terminal of the amplification section TIA of the second receiving section 110-2 with the enable terminal of the amplification section TIA of the third receiving section 110-3.

[0151] By connecting the multiple delay units as described above, the (N-1)th delay unit 130-n-1 connects the enable terminal of the amplification unit TIA of the (N-1)th receiving unit 110-n-1 with the enable terminal of the amplification unit TIA of the Nth receiving unit 110-n.

[0152] As previously referred to Figure 10 As explained, the delay time of each signal in these multiple delay sections 130-1 to 130-n-1 can be considered to be the same as the delay time of each of the receive enable signals RXE#1 to RXE#N.

[0153] Therefore, by using multiple delay units 130-1 to 130-n-1, the timing control unit 120 can output only the first receive enable signal RXE#1, or it can generate receive enable signals RXE#2 to RXE#N that are delayed after the first receive enable signal RXE#1 and input them to the enable terminals of each amplifier unit TIA.

[0154] Figure 11 The embodiments shown are also consistent with Figure 10 The timing diagram operates in the same way as the previous example, with a first time period T1, a second time period T2, a third time period T3, and a fourth time period T4. Therefore, the only difference compared to the previous example is the circuit configuration, but the same function and effect are shown.

[0155] Figure 12 The simulation results are for the multi-channel lidar receiving circuit of the present invention.

[0156] Reference Figure 12 In this invention, the amplification section TIA of each channel receiving section 110-1 to 110-n is enabled by sequential control of the receiving enable signal. In the past, as a control for turning the power on and off, a power failure (glitch) phenomenon caused by rapid current changes occurred.

[0157] However, in this invention, the current change is controlled relatively slowly, thereby mitigating power supply failures. Since failures are known to be the cause of power supply electromagnetic interference, this invention reduces power supply electromagnetic interference.

[0158] As can be seen from the curve of the total current change, both the present invention and the existing circuits convert from 64mA to 400mA. In the past, rapid current changes were performed. In contrast, the present invention shows that, relatively speaking, a gentle slope and change are formed over time.

[0159] This invention is not limited to the above embodiments. Various modifications and variations can be made without departing from the technical spirit of this invention, which will be obvious to those skilled in the art.

Claims

1. A lidar system, characterized in that, include: The transceiver unit generates light of different wavelengths and receives reflected light of different wavelengths from the target. The beam splitter separates light of different wavelengths from the transceiver into long-wavelength light and short-wavelength light. as well as A scanning mirror illuminates long-wavelength and short-wavelength light that has been sorted in the beam splitter, and the reflected light from the long-wavelength and short-wavelength light is then incident on the transceiver unit via the beam splitter. The beam splitter includes: The first surface is used to reflect the long-wavelength light; as well as The second surface, located opposite the first surface, is used to reflect the short-wavelength light. The optical axis spacing between the long-wavelength light and the short-wavelength light is adjusted by adjusting the thickness of the gap between the first and second surfaces.

2. The lidar system according to claim 1, characterized in that, The optical axis spacing is proportional to the thickness.

3. The lidar system according to claim 1, characterized in that, The vertical divergence angle of the long-wavelength light is smaller than that of the short-wavelength light.

4. The lidar system according to claim 1 or 3, characterized in that, In the transceiver unit, Controlling the delay in the triggering time of the long-wavelength light and the short-wavelength light, A new output light waveform is generated by combining the waveforms of the long-wavelength light and the short-wavelength light.

5. The lidar system according to claim 4, characterized in that, The transceiver unit includes a unit array that converts reflected light into electrical signals. The multiple units of the unit array are each capable of receiving both long-wavelength reflected light and short-wavelength reflected light.

6. The lidar system according to claim 5, characterized in that, The upper part of the unit array includes filters for allowing long-wavelength and short-wavelength reflected light to pass through.

7. The lidar system according to claim 4, characterized in that, The transceiver unit includes a unit array that converts reflected light into electrical signals. The central units of the array are capable of receiving both long-wavelength and short-wavelength reflected light, while the other units besides the central units are capable of receiving short-wavelength reflected light.

8. The lidar system according to claim 4, characterized in that, Under steady-state conditions, the time domain of the long-wavelength light and the short-wavelength light above the threshold voltage is designated as the reference time domain of the detection signal. The lidar system also includes a processor that compensates for walk errors by using the ratio of the detected time domain to the reference time domain as the level of the received signal decreases or increases.

9. The lidar system according to claim 1, characterized in that, The receiving circuit of the transceiver unit includes: The receiving unit, configured with the same number of channels as the multi-channel lidar sensor, is used for detecting light; and The timing control unit enables multiple receiving units separately, and maintains a difference in the enable time for each receiving unit for control purposes.

10. The lidar system according to claim 9, characterized in that, The receiving units are N units, which are integers of 4 or more. The receiving unit includes: Photodiodes are used to detect light; and The amplification section is used to amplify the detection signal of the photodiode. The timing control unit outputs a receive enable signal to the enable terminal of each amplification section of the plurality of receivers.

11. The lidar system according to claim 9, characterized in that, The receiving units are N units, which are integers of 4 or more. The receiving unit includes: Photodiodes are used to detect light; and The amplification section is used to amplify the detection signal of the photodiode. The timing control unit outputs a receive enable signal synchronized with the transmit enable signal used for outputting laser light to the enable terminal of the first amplifier unit. The enabling timing of the plurality of receiving units is controlled by N-1 delay units that are respectively connected to the enable terminal pairs of the plurality of amplification units.

12. The lidar system according to claim 10 or 11, characterized in that, The N receive enable signals are each delayed in stages from the first receive enable signal to the Nth receive enable signal at a set time.

13. The lidar system according to claim 12, characterized in that, The N receive enable signals include: In the first time period, the amplification section is sequentially enabled; and During the third time period, the magnification section is disabled sequentially.

14. The lidar system according to claim 13, characterized in that, The N receive enable signals include a second time period in which all the amplifiers remain enabled. The second time period is shorter than the enable time period of a receive enable signal.

15. The lidar system according to claim 14, characterized in that, The second time period is from the rising edge of the Nth receive enable signal to the falling edge of the first receive enable signal.

16. The lidar system according to claim 13, characterized in that, The N receive enable signals include a fourth time period from the third time period to the beginning of the first time period of the next frame. During the fourth time period, all the aforementioned amplification features are kept disabled.

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