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WO2020107250A1 - 一种激光接收电路及测距装置、移动平台 - Google Patents

一种激光接收电路及测距装置、移动平台 Download PDF

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Publication number
WO2020107250A1
WO2020107250A1 PCT/CN2018/117835 CN2018117835W WO2020107250A1 WO 2020107250 A1 WO2020107250 A1 WO 2020107250A1 CN 2018117835 W CN2018117835 W CN 2018117835W WO 2020107250 A1 WO2020107250 A1 WO 2020107250A1
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WIPO (PCT)
Prior art keywords
circuit
electrical signal
low
frequency
signal
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Application number
PCT/CN2018/117835
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English (en)
French (fr)
Inventor
马亮亮
洪小平
Original Assignee
深圳市大疆创新科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 深圳市大疆创新科技有限公司 filed Critical 深圳市大疆创新科技有限公司
Priority to CN201880016698.2A priority Critical patent/CN111492261B/zh
Priority to PCT/CN2018/117835 priority patent/WO2020107250A1/zh
Publication of WO2020107250A1 publication Critical patent/WO2020107250A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only

Definitions

  • the invention relates to the technical field of laser radar, in particular to a laser receiving circuit, a distance measuring device and a mobile platform.
  • Lidar is a radar system that emits laser beams to detect the target's position, speed and other characteristic quantities.
  • the light sensor of the lidar can convert the acquired light pulse signal into an electrical signal, and obtain the time information corresponding to the electrical signal based on the comparator, thereby obtaining the distance information between the lidar and the target.
  • the intensity of ambient light will have a significant impact on the performance of the ranging.
  • a large amount of optical noise will be generated under strong background light, and the deterioration of the signal-to-noise ratio will lead to a shorter measurement distance;
  • the measurement distance can be increased by lowering the trigger threshold (in the dark environment, the signal-to-noise ratio is improved). Under this strategy, the measurement of ambient light will be important.
  • a first aspect of the present invention provides a laser receiving circuit, including: a photoelectric conversion circuit and a separation circuit;
  • the photoelectric conversion circuit is used to receive an optical signal and convert the optical signal into an electrical signal, the optical signal includes an optical pulse signal reflected by an object and an ambient light signal;
  • the separation circuit is used to separate the electrical signal into a high-frequency electrical signal and a low-frequency electrical signal, the frequency of the high-frequency electrical signal is at least 10 times higher than the frequency of the low-frequency electrical signal,
  • the ambient light information acquisition circuit is configured to acquire information of the ambient light signal according to the low-frequency electrical signal.
  • the separation circuit includes two branches connected in parallel to each other, one of which is a high-frequency response circuit for responding only to the high-frequency electrical signal to filter out the low-frequency electrical signal;
  • the other branch is a low-frequency response circuit for responding only to the low-frequency electrical signal to filter out the high-frequency electrical signal, thereby separating the high-frequency electrical signal and the low-frequency electrical signal.
  • the high-frequency response circuit includes a high-speed amplifier and an AC coupler connected in series with each other;
  • the AC coupler performs AC coupling with the high-speed amplifier to filter the low-frequency electrical signal, and the high-speed amplifier is used to amplify the high-frequency electrical signal.
  • the AC coupler includes at least one capacitor, and/or the high-speed amplifier includes at least one high-speed transimpedance amplifier.
  • the low-frequency response circuit includes at least one low-speed transimpedance amplifier.
  • the low-frequency response circuit at least includes a current mirror for directly outputting or amplifying the low-frequency electrical signal by multiple times.
  • the low-frequency response circuit further includes a first amplification circuit and/or an electrical signal conversion circuit
  • the first amplifying circuit is used to amplify the electric signal output by the current mirror
  • the electrical signal conversion circuit includes at least one resistor for converting the current signal output by the current mirror into a voltage signal.
  • the current mirror includes at least one of a BJT device, a MOSFET device, and a JFET device.
  • the separation circuit further includes an amplifier connected in series between the photoelectric conversion circuit and the separation circuit to amplify the high-frequency electrical signal and the low-frequency electrical signal.
  • the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series to each other;
  • the low-frequency response circuit further includes a two-stage amplifying circuit to further amplify the low-frequency electrical signal responsive to the low-frequency response circuit.
  • the photoelectric conversion circuit includes a photosensitive sensor for receiving the laser pulse signal and converting the laser pulse signal into an electrical signal.
  • the ambient light information acquisition circuit prestores data on the correspondence between the light intensity under different ambient light intensities and the low-frequency electrical signal
  • the ambient light information acquisition circuit determines the light intensity of the ambient light based on the measured value of the low-frequency electrical signal and the corresponding relationship.
  • the light intensity under the different ambient light intensity has a linear relationship with the low-frequency voltage.
  • the frequency of the high-frequency electrical signal is at least 50 times higher than the frequency of the low-frequency electrical signal.
  • the invention also provides a distance measuring device, including:
  • Light emitting circuit used to emit laser pulse signal
  • the laser receiving circuit as described above is used for receiving an optical signal and converting the optical signal into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back by an object, and the electrical signal Separating into a high-frequency electrical signal and a low-frequency electrical signal, and acquiring information of the ambient light signal according to the low-frequency electrical signal;
  • a sampling circuit configured to sample the high-frequency electrical signal separated by the laser receiving circuit to obtain a sampling result
  • the arithmetic circuit is used for calculating the distance between the object and the distance measuring device according to the sampling result.
  • the sampling circuit further includes a comparison circuit, configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • a comparison circuit configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • the comparison circuit includes at least one comparator, a first input terminal of the comparator is used to receive the electrical signal input from the laser receiving circuit, and a second input terminal of the comparator is used to receive According to the preset threshold, the output terminal of the comparator is used to output the result of the comparison operation, where the result of the comparison operation includes time information corresponding to the electrical signal.
  • the comparison circuit further includes a time-to-digital converter, and the time-to-digital converter is electrically connected to the output terminal of the comparator, and is used to extract and compare with the result of the comparison operation output by the comparator Time information corresponding to electrical signals.
  • the invention also provides a mobile platform, including:
  • a platform body, the distance measuring device is installed on the platform body.
  • the mobile platform includes at least one of an unmanned aerial vehicle, a car, and a robot.
  • the present invention provides the above-mentioned laser receiving circuit, distance measuring device, and mobile platform.
  • the laser receiving circuit separates the electrical signal into a high-frequency electrical signal and a low-frequency electrical signal through a separation circuit.
  • the frequency of the high-frequency electrical signal is higher than At least 10 times the frequency of the low-frequency electrical signal, and at the same time obtain the information of the ambient light signal according to the low-frequency electrical signal through the ambient light information acquisition circuit, so as to dynamically adjust the trigger threshold for different ambient light, when the light is weak Significantly increase the measurement distance.
  • FIG. 1 is a schematic structural diagram of a laser receiving circuit provided by an embodiment of the present invention.
  • FIG. 2 is a schematic structural diagram of a laser receiving circuit provided by another embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a laser receiving circuit according to another embodiment of the present invention.
  • FIG. 4 is a schematic frame diagram of a distance measuring device according to an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of an embodiment of a distance measuring device provided by an embodiment of the present invention using a coaxial optical path.
  • the intensity of ambient light will have a significant impact on the performance of ranging, and the measurement of ambient light is becoming more and more important.
  • TOF mean-of-flight, time-of-flight
  • the signal-to-noise ratio directly affects the range, and an increase in the signal-to-noise ratio will increase the measurement distance.
  • an optical device working outdoors it is susceptible to the influence of external sunlight. Under strong light, the increase of optical noise will significantly reduce the signal-to-noise ratio of the receiving system, resulting in a lower range.
  • the trigger threshold In laser distance measurement, when there is ambient light The intensity of the noise is relatively large, and the trigger threshold is also high, while the signal and noise intensity are relatively small when there is no ambient light, and the trigger threshold is also low.
  • the noise of the analog circuit output will increase significantly in sunlight.
  • the trigger threshold In order to prevent false triggering in sunlight, the trigger threshold needs to be increased. However, increasing the trigger threshold will result in small signals that cannot be triggered in low light, and the effective optical signal will be leaked. In this case, the threshold voltage can be further lowered to increase the measurement distance and improve the weak environment Light time performance.
  • the existing laser ranging receiving circuit is greatly affected by ambient light, and the output noise of the circuit will increase significantly under strong background light.
  • the judgment threshold needs to be set relatively high, which will As a result, the measurement distance becomes shorter in low light.
  • multiple sets of sensors are generally used for environmental measurement.
  • a visual system such as a camera during the day can achieve effective environmental measurement, but the performance of the visual system will seriously deteriorate at night. At this time, it can form an effective complement with the laser ranging system.
  • the preset threshold can be adjusted to increase the range. At this time, the measurement of ambient light will be very important.
  • the present invention provides a laser receiving circuit to realize the measurement of the background light intensity, so that it can adapt to different judgment thresholds under different background light intensity.
  • the laser receiving circuit includes: a photoelectric conversion circuit and a separation Circuit.
  • the photoelectric conversion circuit includes a photosensitive sensor. After receiving the optical pulse signal, the photoelectric conversion circuit converts the optical pulse signal into an electrical pulse signal.
  • the electrical pulse signal includes a voltage pulse signal or a current pulse signal, and is not limited to a certain one.
  • the photoelectric conversion circuit includes an APD (avalanche photodiode) or PIN.
  • the laser receiving circuit further includes a power management circuit for providing a reverse bias voltage to the avalanche photodiode, the avalanche photodiode is used to receive the optical pulse signal, and convert the optical pulse signal into an electrical signal, and The electrical signal is output to the separation circuit.
  • the separation circuit includes two branches connected in parallel with each other, one of which is a high-frequency response circuit,
  • the other branch is a low-frequency response circuit.
  • the frequency of the high-frequency electrical signal is at least 50 times higher than the frequency of the low-frequency electrical signal.
  • the frequency of the high-frequency electrical signal is at least 100 times higher than the frequency of the low-frequency electrical signal.
  • the high-frequency response circuit includes a high-speed amplifier and an AC coupler connected in series with each other; the AC coupler includes, for example, at least one capacitor, or other components that can filter out low-frequency electrical signals and electrical signals, and does not Limited to a certain kind.
  • the high-speed amplifier includes at least one high-speed transimpedance amplifier (TIA).
  • the TIA is used in a detection device that converts a weak optical signal into an electrical signal and amplifies the signal to a certain intensity and low noise in an optical communication system. Its working principle is : When the photosensitive surface of the photoelectric conversion circuit (such as PIN) is irradiated by the detection light, due to the reverse bias of the pn junction, the photo-generated carriers drift under the action of the electric field and generate a photocurrent in the external circuit; the photocurrent passes through the transimpedance amplifier Amplified output realizes the function of converting optical signals into electrical signals and then amplifying the electrical signals.
  • PIN photosensitive surface of the photoelectric conversion circuit
  • the TIA itself does not have the function of filtering high-frequency electrical signals and low-frequency electrical signals.
  • the filtering function is an AC coupler, which has the same amplification function for high-frequency electrical signals and low-frequency electrical signals, but An AC coupler is provided in the high-frequency response circuit. After the TIA and the AC coupler are AC-coupled, only the high-frequency electrical signal is responded to and amplified.
  • the low-frequency response circuit includes at least one low-speed transimpedance amplifier, wherein the low-speed transimpedance amplifier responds only to low-frequency electrical signals, which filters out high-frequency electrical signals to implement high-frequency electrical signals and low-frequency electrical signals Separation, and amplify low-frequency electrical signals.
  • the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series to each other, wherein the low-frequency filter is used to respond only to low-frequency electrical signals, which filters out high-frequency electrical Signal, but the low-frequency filter does not have an amplification function, so a second amplifying circuit is further connected after the low-pass filter, where the second amplifying circuit can use a conventional amplifier, because the low-frequency filter has been set, so only need It suffices to have an amplification function, and the choice is expanded.
  • a low-speed transimpedance amplifier can be provided after the low-frequency filter to achieve the amplification function.
  • the low-frequency response circuit includes a current mirror for directly outputting or amplifying the low-frequency electrical signal by several times.
  • the high-frequency response circuit has one embodiment, that is, it includes a high-speed amplifier and an AC coupler connected in series with each other, and the low-frequency response circuit has three embodiments, namely a low-speed transimpedance amplifier, a current mirror, and a low-frequency Pass filter and second amplifier circuit.
  • the laser receiving circuit of the present invention includes any combination of a high-frequency response circuit and three low-frequency response circuits. The following three specific embodiments of the laser receiving circuit can be obtained. Give a detailed explanation.
  • the high-frequency response circuit includes a high-speed transimpedance amplifier (TIA) and a capacitor C1.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit.
  • the power management circuit is used to provide an inversion for the avalanche photodiode. To bias.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are coupled to achieve the response of the high-frequency electrical signal while filtering out the low-frequency electrical signal.
  • the low-frequency response circuit is a low-frequency amplification circuit, wherein the low-frequency response circuit includes a low-pass filter and a second amplification circuit connected in series with each other, wherein the low-frequency filter is used to respond only to low-frequency electrical signals, which Filter out high-frequency electrical signals, but the low-frequency filter does not have an amplification function, so a second amplifier circuit is further connected after the low-pass filter, where the second amplifier circuit can use a conventional amplifier, because low-frequency filtering has been set Therefore, it only needs to have an amplifying function, and there is a choice to expand.
  • the shown photosensitive device PIN or APD is connected to the high-frequency response circuit and the low-frequency response circuit of the subsequent stage (where the low-frequency response circuit is connected to the ambient light information acquisition circuit) and outputs HS_TIA_out and DC_out signals.
  • the ambient light Due to the difference in bandwidth between the optical signal and the ambient light, the ambient light appears as a low-frequency DC signal.
  • the low-frequency response circuit separates the ambient light through a low-pass filter. After amplification, the intensity of the ambient light can be reversed by measuring the low-frequency voltage signal. weak.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit, and the power management circuit is used to give the avalanche photodiode Provide reverse bias.
  • TIA high-speed transimpedance amplifier
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are AC coupled, high-frequency received optical signals can be coupled into the high-speed transimpedance amplifier TIA through the capacitor C1, and the ambient light signal is filtered.
  • a high-speed transimpedance amplifier (TIA) circuit converts the current into a voltage, and the conversion gain of the TIA is Rf. In order to measure the narrow pulses emitted by the laser, the bandwidth of the TIA circuit is very high.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • a low-frequency response circuit is used to select a current mirror.
  • the current mirror is composed of Rin, T1 and T2, which provides DC bias for the APD.
  • the low-frequency received optical signal can enter the low-speed transimpedance amplifier TIA, and the high-frequency optical signal is filtered.
  • the low-frequency response circuit further includes a first amplifying circuit for further amplifying the signal output by the current mirror.
  • the current mirror shown can mirror the low-frequency electrical signal (ambient light signal) onto the first amplifying circuit, through the first amplifying circuit The signal output by the current mirror is further amplified.
  • the current mirror itself can amplify the electrical signal, the current mirror can output the same signal as the ambient light current, and can be amplified after a certain multiple of output, so the current mirror itself can also be set as an element with an amplification function .
  • the low-frequency response circuit selects a current mirror
  • the low-frequency response circuit further includes an electric signal conversion circuit for converting the current signal output by the current mirror into a voltage signal.
  • the electrical signal conversion circuit includes at least one resistor R1. As shown in FIG. 2, the mirror current output by the current mirror generates a voltage drop on R1, and measuring the voltage drop on R1 can inversely obtain the intensity of the background light.
  • FIG. 2 shows a current mirror designed with a BJT bipolar junction transistor (Bipolar Junction Transistor—BJT) device.
  • BJT Bipolar Junction Transistor
  • MOSFET Metal Organic semiconductor field effect transistor
  • JFET Junction Field -Effect Transistor
  • the APD shown in FIG. 2 is a positive high-voltage power supply, and in fact, a negative high-voltage power supply method can also be used, and the direction of the current mirror also needs to be reversed.
  • the high-frequency response circuit includes a high-speed transimpedance amplifier (TIA) and a capacitor C1.
  • the avalanche photodiode is connected to the input terminal of the high-frequency response circuit.
  • the power management circuit is used to provide avalanche photodiode. Provide reverse bias.
  • the high-speed transimpedance amplifier (TIA) and the capacitor C1 are AC coupled, high-frequency received optical signals can be coupled into the high-speed transimpedance amplifier TIA through the capacitor C1, and the ambient light signal is filtered.
  • a high-speed transimpedance amplifier (TIA) circuit converts the current into a voltage, and the conversion gain of the TIA is Rf. In order to measure the narrow pulses emitted by the laser, the bandwidth of the TIA circuit is very high.
  • the first input terminal of the high-speed transimpedance amplifier (TIA) is electrically connected to one end of the capacitor C1, the other end of the capacitor is electrically connected to the avalanche photodiode, and the second input end of the high-speed transimpedance amplifier (TIA) is
  • the reference circuit is electrically connected to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal can be electrically connected to the sampling circuit.
  • a low-frequency response circuit using one channel selects a low-speed transimpedance amplifier to respond to low-frequency electrical signals.
  • the low-speed transimpedance amplifier itself has the function of filtering high-frequency electrical signals, and only responds to low-frequency electrical signals.
  • the first input terminal of the low-speed transimpedance amplifier (TIA) is electrically connected to the avalanche photodiode
  • the second input terminal of the low-speed transimpedance amplifier (TIA) is electrically connected to the reference circuit, and is used for the high-speed transimpedance amplifier ( TIA) provides a reference voltage
  • the output of the low-speed transimpedance amplifier (TIA) can be electrically connected to the ambient light information acquisition circuit.
  • the separation circuit further includes an amplifier connected in series between the photoelectric conversion circuit and the separation circuit to amplify the high-frequency electrical signal and the low-frequency electrical signal.
  • the amplifier circuit uses a high-speed transimpedance amplifier (TIA), the first input terminal of the high-speed transimpedance amplifier is electrically connected to the avalanche photodiode, and the second high-speed transimpedance amplifier (TIA)
  • the input terminal is electrically connected to a reference circuit, and is used to provide a reference voltage for a high-speed transimpedance amplifier (TIA) whose output terminal is electrically connected to a high-frequency response circuit and a low-frequency response circuit, respectively.
  • TOF ranging needs to read the current signal output by the photosensitive device, convert the current into a voltage through a high-speed transimpedance amplifier (TIA) circuit, and the conversion gain of the TIA is Rf.
  • TIA transimpedance amplifier
  • the bandwidth of the TIA circuit is very high. At this time, it has the same conversion capability for the received optical signal and the ambient optical signal.
  • the low-frequency response circuit further includes a two-stage amplification circuit to perform secondary amplification on the low-frequency electrical signal that the low-frequency response circuit responds to.
  • the ambient light information acquisition circuit prestores data of the correspondence between the light intensity under different ambient light intensities and the low-frequency electrical signal; the ambient light information acquisition circuit is based on the measured low-frequency electrical signal The value and the correspondence determine the light intensity of the ambient light.
  • the output photocurrent is proportional to the input light intensity
  • the conversion of the photocurrent by the laser receiving circuit is also proportional to the input light intensity.
  • k can be obtained by calculation, as long as the photoelectric conversion multiple of the photosensor and the magnification of the circuit are known, the light intensity can be obtained.
  • the voltage signal can be calibrated to the ambient light intensity through calibration. For example, before the machine leaves the factory, the laser receiving circuit is irradiated with ambient light of known light intensity.
  • the circuit will output a voltage, and the output voltage is linear with the input light intensity. Therefore, it is possible to measure the voltage of multiple different ambient lights, calculate the linear factor and record it in the machine. When used, multiply the measured voltage by the linear factor to infer the intensity of the ambient light. The measurement of the ambient light is realized through the above method, and then the preset threshold is adjusted when the ambient light is weak.
  • an embodiment of the present invention further provides a distance measuring device, including a light emitting circuit for emitting a laser pulse signal; the above-mentioned laser receiving circuit for receiving an optical signal and converting the optical signal Converted into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back from the object, and the electrical signal is separated into a high-frequency electrical signal and a low-frequency electrical signal, and obtained according to the low-frequency electrical signal Information of the ambient light signal; a sampling circuit for sampling the high-frequency electrical signal separated by the laser receiving circuit to obtain a sampling result; an operation circuit for calculating the object and The distance between the distance measuring devices.
  • a distance measuring device including a light emitting circuit for emitting a laser pulse signal; the above-mentioned laser receiving circuit for receiving an optical signal and converting the optical signal Converted into an electrical signal, wherein the optical signal includes an optical pulse signal and an ambient light signal reflected back from the object, and the electrical signal is separated into a high-frequency electrical signal and a low-
  • the number of the light emitting devices is at least 2.
  • the sampling circuit further includes a comparison circuit, configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • a comparison circuit configured to perform a comparison operation between the electrical signal input from the laser receiving circuit and a preset threshold to extract time information corresponding to the electrical signal.
  • the comparison circuit includes at least one comparator, a first input terminal of the comparator is used to receive the electrical signal input from the laser receiving circuit, and a second input terminal of the comparator is used to receive According to the preset threshold, the output terminal of the comparator is used to output the result of the comparison operation, where the result of the comparison operation includes time information corresponding to the electrical signal.
  • the comparison circuit further includes a time-to-digital converter (Time-to-Digital Converter, TDC).
  • TDC Time-to-Digital Converter
  • the time-to-digital converter is electrically connected to the output terminal of the comparator, and is used to extract and compare with the result of the comparison operation output by the comparator. Time information corresponding to electrical signals.
  • the preset threshold can be adjusted according to the intensity of the measured ambient light, so that when the ambient light is weak, a normal optical signal can trigger the preset threshold, thereby increasing the measurement distance.
  • the preset threshold can be adjusted in the following ways:
  • the first implementation of adjusting the preset threshold adjusts the voltage of the comparison circuit to adjust the preset threshold of the comparison circuit.
  • the distance measuring device includes a digital-to-analog converter.
  • the digital-to-analog converter can be connected to the input terminal of the comparison circuit, and the preset threshold of the comparison circuit can be adjusted by controlling the output voltage of the digital-to-analog converter.
  • the second implementation of adjusting the preset threshold may be: the distance measuring device may further include a comparison threshold adjustment circuit.
  • the comparison threshold adjustment circuit includes multiple resistors, and one end of the multiple resistors is connected to the comparator At the input end, multiple voltage signals are input to the other end of the multiple resistors to provide a preset threshold value to the input end of the comparator through the multiple resistors.
  • the second input to the comparison circuit is adjusted. The preset threshold at the input.
  • an embodiment of the present invention further provides a mobile platform, the mobile platform includes any of the foregoing distance measuring devices and a platform body, and the distance measuring device is installed on the platform body. Further, the mobile platform includes at least one of a manned aircraft, an unmanned aerial vehicle, a car, a robot, and a remote control car.
  • the light emitting devices provided by the various embodiments of the present invention may be applied to a distance measuring device, and the distance measuring device may be an electronic device such as a laser radar or a laser distance measuring device.
  • the distance measuring device is used to sense external environment information, for example, distance information, azimuth information, reflection intensity information, speed information, etc. of the environmental target.
  • the distance measuring device can detect the distance between the detecting object and the distance measuring device by measuring the time of light propagation between the distance measuring device and the detection object, that is, Time-of-Flight (TOF).
  • TOF Time-of-Flight
  • the distance measuring device may also detect the distance between the detected object and the distance measuring device through other techniques, such as a distance measuring method based on phase shift measurement, or a distance measuring method based on frequency shift measurement. There are no restrictions.
  • the distance measuring device 100 may include a transmitting circuit 110, a receiving circuit 120, a sampling circuit 130, and an arithmetic circuit 140.
  • the transmission circuit 110 may transmit a sequence of light pulses (for example, a sequence of laser pulses).
  • the receiving circuit 120 can receive the optical pulse sequence reflected by the detected object, and photoelectrically convert the optical pulse sequence to obtain an electrical signal, which can be output to the sampling circuit 130 after processing the electrical signal.
  • the sampling circuit 130 may sample the electrical signal to obtain the sampling result.
  • the arithmetic circuit 140 may determine the distance between the distance measuring device 100 and the detected object based on the sampling result of the sampling circuit 130.
  • the distance measuring apparatus 100 may further include a control circuit 150, which may control other circuits, for example, may control the working time of each circuit and/or set parameters for each circuit.
  • a control circuit 150 may control other circuits, for example, may control the working time of each circuit and/or set parameters for each circuit.
  • the distance measuring device shown in FIG. 4 includes a transmitting circuit, a receiving circuit, a sampling circuit, and an arithmetic circuit
  • the embodiments of the present application are not limited thereto, and the transmitting circuit, the receiving circuit, the sampling circuit, and the arithmetic
  • the number of any of the circuits may be at least two.
  • the distance measuring apparatus 100 may further include a scanning module 160 for changing the propagation direction of the laser pulse sequence emitted by the transmitting circuit.
  • the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, and the arithmetic circuit 140, or the module including the transmitting circuit 110, the receiving circuit 120, the sampling circuit 130, the arithmetic circuit 140, and the control circuit 150 may be referred to as measurement
  • the distance measuring module 150 may be independent of other modules, for example, the scanning module 160.
  • a coaxial optical path may be used in the distance measuring device, that is, the light beam emitted by the distance measuring device and the reflected light beam share at least part of the optical path in the distance measuring device.
  • the distance measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance measuring device and the reflected light beam are respectively transmitted along different optical paths in the distance measuring device.
  • FIG. 5 shows a schematic diagram of an embodiment of the distance measuring device of the present invention using a coaxial optical path.
  • the distance measuring device 200 includes a distance measuring module 201.
  • the distance measuring module 210 includes a transmitter 203 (which may include the above-mentioned transmitting circuit), a collimating element 204, and a detector 205 (which may include the above-mentioned receiving circuit, sampling circuit, and arithmetic circuit) Optical path changing element 206.
  • the ranging module 210 is used to emit a light beam, and receive back light, and convert the back light into an electrical signal.
  • the transmitter 203 may be used to transmit a light pulse sequence.
  • the transmitter 203 may emit a sequence of laser pulses.
  • the laser beam emitted by the transmitter 203 is a narrow-bandwidth beam with a wavelength outside the visible light range.
  • the collimating element 204 is disposed on the exit optical path of the emitter, and is used to collimate the light beam emitted from the emitter 203, and collimate the light beam emitted from the emitter 203 into parallel light to the scanning module.
  • the collimating element is also used to converge at least a part of the return light reflected by the detection object.
  • the collimating element 204 may be a collimating lens or other element capable of collimating the light beam.
  • the optical path changing element 206 is used to combine the transmitting optical path and the receiving optical path in the distance measuring device before the collimating element 104, so that the transmitting optical path and the receiving optical path can share the same collimating element, so that the optical path More compact.
  • the transmitter 103 and the detector 105 may respectively use respective collimating elements, and the optical path changing element 206 is disposed on the optical path behind the collimating element.
  • the light path changing element can use a small-area mirror to convert The transmitting optical path and the receiving optical path are combined.
  • the light path changing element may also use a reflector with a through hole, where the through hole is used to transmit the outgoing light of the emitter 203, and the reflector is used to reflect the return light to the detector 205. This can reduce the blocking of the return light by the support of the small mirror in the case of using the small mirror.
  • the optical path changing element is offset from the optical axis of the collimating element 204. In some other implementations, the optical path changing element may also be located on the optical axis of the collimating element 204.
  • the distance measuring device 200 further includes a scanning module 202.
  • the scanning module 202 is placed on the exit optical path of the distance measuring module 201, and the scanning module 102 is used to change the transmission direction of the collimated light beam 219 emitted through the collimating element 204 and project it to the external environment, and project the return light to the collimating element 204 .
  • the returned light is converged on the detector 105 via the collimating element 104.
  • the scanning module 202 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the light beam.
  • the scanning module 202 includes a lens, a mirror, a prism, a galvanometer, a grating, a liquid crystal, an optical phased array (Optical Phased Array), or any combination of the above optical elements.
  • at least part of the optical element is moving, for example, the at least part of the optical element is driven to move by a driving module, and the moving optical element can reflect, refract, or diffract the light beam to different directions at different times.
  • multiple optical elements of the scanning module 202 may rotate or vibrate about a common axis 209, and each rotating or vibrating optical element is used to continuously change the direction of propagation of the incident beam.
  • the multiple optical elements of the scanning module 202 may rotate at different rotation speeds, or vibrate at different speeds.
  • at least part of the optical elements of the scanning module 202 can rotate at substantially the same rotational speed.
  • the multiple optical elements of the scanning module may also rotate around different axes.
  • the multiple optical elements of the scanning module may also rotate in the same direction, or rotate in different directions; or vibrate in the same direction, or vibrate in different directions, which is not limited herein.
  • the scanning module 202 includes a first optical element 214 and a driver 216 connected to the first optical element 214.
  • the driver 216 is used to drive the first optical element 214 to rotate about a rotation axis 209 to change the first optical element 214 The direction of the collimated light beam 219.
  • the first optical element 214 projects the collimated light beam 219 to different directions.
  • the angle between the direction of the collimated light beam 219 changed by the first optical element and the rotation axis 109 changes as the first optical element 214 rotates.
  • the first optical element 214 includes a pair of opposed non-parallel surfaces through which the collimated light beam 219 passes.
  • the first optical element 214 includes a prism whose thickness varies along at least one radial direction.
  • the first optical element 114 includes a wedge-angle prism that aligns the straight beam 119 for refraction.
  • the scanning module 202 further includes a second optical element 215 that rotates about a rotation axis 209.
  • the rotation speed of the second optical element 215 is different from the rotation speed of the first optical element 214.
  • the second optical element 215 is used to change the direction of the light beam projected by the first optical element 214.
  • the second optical element 115 is connected to another driver 217, and the driver 117 drives the second optical element 215 to rotate.
  • the first optical element 214 and the second optical element 215 may be driven by the same or different drivers, so that the first optical element 214 and the second optical element 215 have different rotation speeds and/or rotations, thereby projecting the collimated light beam 219 to the outside space Different directions can scan a larger spatial range.
  • the controller 218 controls the drivers 216 and 217 to drive the first optical element 214 and the second optical element 215, respectively.
  • the rotation speeds of the first optical element 214 and the second optical element 215 can be determined according to the area and pattern expected to be scanned in practical applications.
  • Drives 216 and 217 may include motors or other drives.
  • the second optical element 115 includes a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the second optical element 115 includes a prism whose thickness varies along at least one radial direction. In one embodiment, the second optical element 115 includes a wedge angle prism.
  • the scanning module 102 further includes a third optical element (not shown) and a driver for driving the third optical element to move.
  • the third optical element includes a pair of opposed non-parallel surfaces through which the light beam passes.
  • the third optical element includes a prism whose thickness varies along at least one radial direction.
  • the third optical element includes a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or turns.
  • each optical element in the scanning module 202 can project light into different directions, such as directions 211 and 213, so as to scan the space around the distance measuring device 200.
  • the detector 205 is placed on the same side of the collimating element 204 as the emitter 203.
  • the detector 205 is used to convert at least part of the returned light passing through the collimating element 204 into an electrical signal.
  • each optical element is coated with an antireflection coating.
  • the thickness of the AR coating is equal to or close to the wavelength of the light beam emitted by the emitter 103, which can increase the intensity of the transmitted light beam.
  • a filter layer is coated on the surface of an element on the beam propagation path in the distance measuring device, or a filter is provided on the beam propagation path to transmit at least the wavelength band of the beam emitted by the transmitter, Reflect other bands to reduce the noise caused by ambient light to the receiver.
  • the transmitter 203 may include a laser diode through which laser pulses in the order of nanoseconds are emitted.
  • the laser pulse receiving time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this way, the distance measuring device 200 can calculate the TOF using the pulse reception time information and the pulse emission time information, thereby determining the distance between the detection object 201 and the distance measuring device 200.
  • the distance and orientation detected by the distance measuring device 200 can be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like.
  • the distance measuring device of the embodiment of the present invention can be applied to a mobile platform, and the distance measuring device can be installed on the platform body of the mobile platform.
  • a mobile platform with a distance-measuring device can measure the external environment, for example, measuring the distance between the mobile platform and obstacles for obstacle avoidance and other purposes, and performing two-dimensional or three-dimensional mapping of the external environment.
  • the mobile platform includes at least one of an unmanned aerial vehicle, a car, a remote control car, a robot, and a camera.
  • the platform body When the distance measuring device is applied to an unmanned aerial vehicle, the platform body is the fuselage of the unmanned aerial vehicle.
  • the platform body When the distance measuring device is applied to an automobile, the platform body is the body of the automobile.
  • the car may be a self-driving car or a semi-automatic car, and no restriction is made here.
  • the platform body When the distance measuring device is applied to a remote control car, the platform body is the body of the remote control car.
  • the platform body When the distance measuring device is applied to a robot, the platform body is a robot.
  • the platform body When the distance measuring device is applied to a camera, the platform body is the camera itself.
  • the present invention provides a laser emission solution that meets human eye safety regulations by providing the above-mentioned light emitting device, ranging device, and mobile platform.
  • the circuit in the above device can ensure that the laser radiation value does not exceed the safety Standard value, so as to ensure the safety of the laser device.

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Abstract

一种激光接收电路及测距装置（100）、移动平台，激光接收电路包括：光电转换电路和分离电路；其中，光电转换电路，用于接收光信号，以及将光信号转成电信号，光信号包括经物体反射回的光脉冲信号和环境光信号；分离电路，用于将电信号分离成高频电信号和低频电信号，高频电信号的频率高于低频电信号的频率的至少10倍，环境光信息获取电路，用于根据低频电信号获取环境光信号的信息。激光接收电路及测距装置（100）、移动平台可以获取环境光信号的信息，以实现动态调整不同环境光时的触发阈值，在弱光时显著增加测量距离。

Description

一种激光接收电路及测距装置、移动平台 技术领域
本发明涉及激光雷达技术领域，尤其涉及一种激光接收电路及测距装置、移动平台。
背景技术
激光雷达是以发射激光束探测目标的位置、速度等特征量的雷达系统。激光雷达的光敏传感器可以将获取到的光脉冲信号转变为电信号，基于比较器获取该电信号对应的时间信息，从而得到激光雷达与目标物之间的距离信息。
然而，在激光测距领域，环境光的强度会对测距的性能产生显著影响，在强背景光下会产生大量的光噪声，恶化信噪比导致测量距离变近；而在弱光环境时可以通过降低触发的阈值来提高测量距离(在黑暗环境下信噪比提高)，在这种策略下环境光的测量将会很重要。
因此，需要提供一种装置以实现环境光的测量。
发明内容
本发明第一方面提供了一种激光接收电路，包括：光电转换电路和分离电路；
其中，所述光电转换电路，用于接收光信号，以及将所述光信号转成电信号，所述光信号包括经物体反射回的光脉冲信号和环境光信号；
所述分离电路，用于将所述电信号分离成高频电信号和低频电信号，所述高频电信号的频率高于所述低频电信号的频率的至少10倍，
环境光信息获取电路，用于根据所述低频电信号获取所述环境光信号的信息。
可选地，所述分离电路包括彼此并联连接设置两个支路，其中一个支路为高频响应电路，用于仅对所述高频电信号响应，以滤除所述低频电信号；
另外一个支路为低频响应电路，用于仅对所述低频电信号响应，以滤除所述高频电信号，进而分离所述高频电信号和低频电信号。
可选地，所述高频响应电路包括彼此串联连接的高速放大器和交流耦合器；
所述交流耦合器与所述高速放大器进行交流耦合，用于过滤所述低频电信号，所述高速放大器用于对所述高频电信号放大。
可选地，所述交流耦合器包括至少一电容，和/或所述高速放大器包括至少一个高速跨阻放大器。
可选地，所述低频响应电路包括至少一个低速跨阻放大器。
可选地，所述低频响应电路至少包括一电流镜，用于将所述低频电信号直接输出或放大数倍后输出。
可选地，所述低频响应电路还包括一第一放大电路和/或电信号转换电路；
其中，所述第一放大电路用于对所述电流镜输出的电信号放大；
所述电信号转换电路包括至少一电阻，用于将所述电流镜输出的电流信号转换为电压信号。
可选地，所述电流镜包括BJT器件、MOSFET器件和JFET器件中的至少一种。
可选地，所述分离电路还包括放大器，所述放大器串联于所述光电转换电路与所述分离电路之间，以对所述高频电信号和所述低频电信号进行放大。
可选地，所述低频响应电路包括彼此串联连接的低通滤波器和第二放大电路；
或所述低频响应电路还包括一二级放大电路，以对所述低频响应电路响应的所述低频电信号进一步放大。
可选地，所述光电转换电路包括光敏传感器，用于接收所述激光脉冲信号，以及将所述激光脉冲信号转换为电信号。
可选地，所述环境光信息获取电路内预存有在不同环境光强度下的光强度与所述低频电信号的对应关系的数据；
所述环境光信息获取电路基于所述测得的所述低频电信号的值和所述对应关系确定所述环境光的光强度。
可选地，所述不同环境光强度下的光强度与低频电压呈线性关系。
可选地，所述高频电信号的频率高于所述低频电信号的频率的至少50倍。
本发明还提供了一种测距装置，包括：
光发射电路，用于出射激光脉冲信号；
如上述的激光接收电路，用于接收光信号，以及将所述光信号转成电信号，其中，所述光信号包括经物体反射回的光脉冲信号和环境光信号，并将所述电信号分离成高频电信号和低频电信号，以及根据所述低频电信号获取所述环境光信号的信息；
采样电路，用于对所述激光接收电路分离后的所述高频电信号进行采样，获得采样结果；
运算电路，用于根据所述采样结果计算所述物体与所述测距装置之间的距离。
可选地，所述采样电路还包括比较电路，用于将从所述激光接收电路输入的电信号与预设阈值进行比较运算，提取与所述电信号对应的时间信息。
可选地，所述比较电路包括至少一个比较器，所述比较器的第一输入端用于接收所述从激光接收电路输入的电信号，所述比较器的第二输入端用于接收所述预设阈值，所述比较器的输出端用于输出比较运算的结果，其中，所述比较运算的结果中包含与所述电信号对应的时间信息。
可选地，所述比较电路还包括时间数字转换器，所述时间数字转换器与所述比较器的输出端电连接，用于根据所述比较器输出的比较运算的结果，提取与所述电信号对应的时间信息。
本发明还提供了一种移动平台，包括：
上述的测距装置；和
平台本体，所述测距装置安装在所述平台本体上。
可选地，所述移动平台包括无人飞行器、汽车和机器人中的至少一种。
本发明通过提供上述激光接收电路、测距装置以及移动平台，所述激光接收电路通过分离电路将所述电信号分离成高频电信号和低频电信号，所述高频电信号的频率高于所述低频电信号的频率的至少10倍，同时通过环境光信息获取电路根据所述低频电信号获取所述环境光信号的信息，以实现动态调整不同环境光时的触发阈值，在弱光时显著增加测量距离。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明一实施例提供的激光接收电路的结构示意图；
图2为本发明另一实施例提供的激光接收电路的结构示意图；
图3为本发明再一实施例提供的激光接收电路的结构示意图；
图4是本发明实施例提供的一种测距装置的示意性框架图；
图5是本发明实施例提供的测距装置采用同轴光路的一种实施例的示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
在激光测距领域，环境光的强度会对测距的性能产生显著影响，环境光的测量越来越重要。在TOF(me-of-flight，飞行时间)应用中信噪比会直接影响量程，信噪比的提高将会提高测量距离。而作为光学设备在室外工作时易受到外部阳光的影响，在强光下因为光噪声的增加，会显著降低接收系统的信噪比，从而导致量程降低。
在激光测距时，在有环境光时
Figure PCTCN2018117835-appb-000001
噪声的强度都比较大，其触发阈值也较高，而在没有环境光时的信号和噪声强度都比较小，其触发阈值也较低。在阳光下模拟电路输出的噪声会显著提高，为了在阳光下不会发生误触发，需要将触发阈值提高。但是将触发阈值提高之后会导致在弱光时小信号无法被触发，则会将有效的光信号漏掉，在这种情况下可以将阈值电压进一步调低，从而增加测量距离，提高在弱环境光时的性能。
现有的激光测距接收电路受环境光影响较大，在强背景光下电路的输出噪声会显著增大，为了在强光噪声时不触发噪点，需要将判断阈值设置的比较高，这会导致在弱光时测量距离变近。
此外，在车载的环境测量系统里，一般会使用多套传感器进行环境测量，在白天时使用摄像头之类的视觉系统可以实现有效的环境测量，但在黑夜时视觉系统的性能将会严重下降，此时可以跟激光测距系统形成有效互补。
在强背景光时光噪声无法被避免，但在弱背景光时可以通过调整预设阈值来提高量程。此时环境光线的测量就会非常重要。
为了解决上述问题，本发明提供了一种激光接收电路，以实现背景光强的测量，从而可以实现在不同背景光强下适应不同的判断阈值，所述激光接收电路包括：光电转换电路和分离电路。
其中，所述光电转换电路包括光敏传感器。光电转换电路在接收光脉冲信号之后，将所述光脉冲信号转化为电脉冲信号，所述电脉冲信号包括电压脉冲信号或电流脉冲信号，并不局限于某一种。
可选地，所述光电转换电路包括APD(雪崩光电二极管)或PIN。
其中，所述激光接收电路还包括电源管理电路，用于给雪崩光电二极管提供反向偏压，所述雪崩光电二极管用于接收光脉冲信号，以及将所述光脉冲信号转换为电信号，并将所述电信号输出给分离电路。
其中，所述分离电路包括彼此并联连接设置两个支路，其中一个支路为高频响应电路，
另外一个支路为低频响应电路。
可选地，高频电信号的频率高于所述低频电信号的频率的至少50倍。可选地，高频电信号的频率高于所述低频电信号的频率的至少100倍。
可选地，所述高频响应电路包括彼此串联连接的高速放大器和交流耦合器；所述交流耦合器例如包括至少一电容，或其他可以实现将低频电信号电信号过滤掉的元件，并不局限于某一种。
可选地，高速放大器包括至少一个高速跨阻放大器(TIA)，TIA用于光通信系统中将微弱的光信号转换成电信号并将信号进行一定强度低噪声放大的 探测器件，其工作原理是：光电转换电路(例如PIN)的光敏面受探测光照射时，由于p-n结处于反向偏置，光生载流子在电场的作用下产生漂移，在外电路产生光电流；光电流通过跨阻放大器放大输出，实现了光信号转换成电信号进而将电信号初步放大的功能。
其中，所述TIA本身并没有对高频电信号和低频电信号进行过滤的功能，起到过滤功能的是交流耦合器，其对高频电信号和低频电信号具有相同的放大功能，但是由于在高频响应电路中通过设置交流耦合器，所述TIA与交流耦合器交流耦合之后，仅对高频电信号进行响应并放大。
可选地，所述低频响应电路包括至少一个低速跨阻放大器，其中，所述低速跨阻放大器仅对低频电信号响应，其过滤掉高频电信号，以实现高频电信号和低频电信号的分离，并且对低频电信号进行放大。
或者，作为另外一种实施方式，所述低频响应电路包括彼此串联连接的低通滤波器和第二放大电路，其中，所述低频滤波器用于仅对低频电信号响应，其过滤掉高频电信号，但是低频滤波器不具备放大功能，因此在低通滤波器后进一步连接一第二放大电路，其中，所述第二放大电路可以选用常规的放大器，由于已经设置低频滤波器，因此只需要具有放大功能即可，选择余地扩大，当然在所述低频滤波器之后再设置一低速跨阻放大器也可以实现放大功能。
或者，作为再一种实施方式，所述低频响应电路包括一电流镜，用于将所述低频电信号直接输出或放大数倍后输出。
如上所述，其中所述高频响应电路具有一种实施方式，即包括彼此串联连接的高速放大器和交流耦合器，低频响应电路具有三种实施方式，分别为低速跨阻放大器、电流镜以及低通滤波器和第二放大电路。其中，本发明的所述激光接收电路包括高频响应电路和三种低频响应电路中的任意一个组合，可以得到以下三种激光接收电路的具体实施方式，下面结合附图对每一种实施方式进行详细的说明。
第一种：如图1所示，高频响应电路包括高速跨阻放大器(TIA)和电容C1，雪崩光电二极管与高频响应电路的输入端连接，电源管理电路用于给雪崩光电二极管提供反向偏压。
其中，高速跨阻放大器(TIA)第一输入端与电容C1的一端电连接，所述电容的另一端与所述雪崩光电二极管电连接，所述高速跨阻放大器(TIA)第二输入端与参考电路电连接，与用于为高速跨阻放大器(TIA)提供参考电压，所述高速跨阻放大器(TIA)的输出端可以与采样电路电连接。
其中，所述高速跨阻放大器(TIA)和电容C1耦合，以实现高频电信号的响应，同时将低频电信号滤除。其中，所述低频响应电路为一低频放大电路，其中所述低频响应电路包括彼此串联连接的低通滤波器和第二放大电路，其中，所述低频滤波器用于仅对低频电信号响应，其过滤掉高频电信号，但是低频滤波器不具备放大功能，因此在低通滤波器后进一步连接一第二放大电路，其中，所述第二放大电路可以选用常规的放大器，由于已经设置低频滤波器，因此只需要具有放大功能即可，选择余地扩大，当然在所述低频滤波器之后再设置一低速跨阻放大器也可以。
所示光敏器件PIN或APD经过高速TIA后分两路接入后级的高频响应电路和低频响应电路(其中低频响应电路与环境光信息获取电路连接)并输出HS_TIA_out和DC_out信号。
由于光信号和环境光带宽的不同，环境光表现为低频的直流信号，在低频响应电路通过低通滤波器将环境光分离出来，经过放大后可以通过低频电压信号的测量反推环境光的强弱。
第二种，如图2所示，其中，高频响应电路包括高速跨阻放大器(TIA)和电容C1，雪崩光电二极管与高频响应电路的输入端连接，电源管理电路用于给雪崩光电二极管提供反向偏压。
其中，所述高速跨阻放大器(TIA)和电容C1交流耦合，高频的接收光信号可以通过电容C1耦合进入高速跨阻放大器TIA，环境光信号则被过滤。在该高频响应电路中通过高速跨阻放大器(TIA)电路将电流转换为电压，TIA的转换增益为Rf。为了测量激光器发出的窄脉冲，TIA电路的带宽很高。
其中，高速跨阻放大器(TIA)第一输入端与电容C1的一端电连接，所述电容的另一端与所述雪崩光电二极管电连接，所述高速跨阻放大器(TIA)第二输入端与参考电路电连接，与用于为高速跨阻放大器(TIA)提供参考电 压，所述高速跨阻放大器(TIA)的输出端可以与采样电路电连接。
另外使用一路的低频响应电路选用电流镜，电流镜由Rin，T1和T2组成，为APD提供直流偏执，低频的接收光信号可以进入低速跨阻放大器TIA，高频的光信号则被过滤。
所述低频响应电路还包括一第一放大电路，用于对所述电流镜输出的信号进一步放大。
其中，在该低频响应电路中，对信号放大的方式包括至少以下两种：第一，所示电流镜可以将低频电信号(环境光信号)镜像到第一放大电路上，通过第一放大电路对所述电流镜输出的信号进一步放大。第二，所述电流镜本身可以对电信号进行放大，所述电流镜可以输出与环境光电流相同的信号，可以放大一定的倍数后输出，因此电流镜本身也可以设置为具有放大功能的元件。
当所述低频响应电路选用电流镜时，所述低频响应电路中还进一步包括电信号转换电路，用于将所述电流镜输出的电流信号转换为电压信号。
所述电信号转换电路包括至少一电阻R1，如图2所示，电流镜输出的镜像电流在R1上产生压降，测量R1上的压降即可反推得到背景光的强度。
其中，附图2中给出了以BJT双极结型晶体管(Bipolar Junction Transistor—BJT)器件设计的电流镜，在本发明的实施例中好可以用MOSFET、JFET结型场效应晶体管(Junction Field-Effect Transistor，JFET)等实现电流镜。
可选地，图2中给出的APD为正高压供电，实际上也可以采用负高压供电方式，此时电流镜的方向也要取反。
第三种，如图3所示，其中，高频响应电路包括高速跨阻放大器(TIA)和电容C1，雪崩光电二极管与高频响应电路的输入端连接，电源管理电路用于给雪崩光电二极管提供反向偏压。
其中，所述高速跨阻放大器(TIA)和电容C1交流耦合，高频的接收光信号可以通过电容C1耦合进入高速跨阻放大器TIA，环境光信号则被过滤。在该高频响应电路中通过高速跨阻放大器(TIA)电路将电流转换为电压，TIA的转换增益为Rf。为了测量激光器发出的窄脉冲，TIA电路的带宽很高。
其中，高速跨阻放大器(TIA)第一输入端与电容C1的一端电连接，所述电容的另一端与所述雪崩光电二极管电连接，所述高速跨阻放大器(TIA)第二输入端与参考电路电连接，与用于为高速跨阻放大器(TIA)提供参考电压，所述高速跨阻放大器(TIA)的输出端可以与采样电路电连接。
另外使用一路的低频响应电路选用选用低速跨阻放大器，用于对低频电信号响应。所述低速跨阻放大器自身具有对高频电信号过滤的功能，仅对低频电信号响应。
其中，低速跨阻放大器(TIA)第一输入端与所述雪崩光电二极管电连接，所述低速跨阻放大器(TIA)第二输入端与参考电路电连接，与用于为高速跨阻放大器(TIA)提供参考电压，所述低速跨阻放大器(TIA)的输出端可以与环境光信息获取电路电连接。
需要说明的是上述三种实施方式仅仅为示例性的，其他类型的高频响应电路和低频响应电路只要能够实现上述功能均可以应用于本发明。
进一步，所述分离电路还包括放大器，所述放大器串联于所述光电转换电路与所述分离电路之间，以对所述高频电信号和所述低频电信号进行放大。
如图1所示，所述放大电路选用高速跨阻放大器(TIA)，所述高速跨阻放大器的第一输入端与所述雪崩光电二极管电连接，所述高速跨阻放大器(TIA)第二输入端与参考电路电连接，与用于为高速跨阻放大器(TIA)提供参考电压，所述高速跨阻放大器(TIA)的输出端分别于高频响应电路和低频响应电路电连接。
其中，TOF测距需要读取光敏器件输出的电流信号，通过高速跨阻放大器(TIA)电路将电流转换为电压，TIA的转换增益为Rf。为了测量激光器发出的窄脉冲，TIA电路的带宽很高，此时对接收光信号和环境光信号有相同的转换能力。
由于环境光线产生的光电流较弱，所述低频响应电路还包括一二级放大电路，以对所述低频响应电路响应的所述低频电信号进行二次放大。
进一步，环境光信息获取电路内预存有在不同环境光强度下的光强度与所述低频电信号的对应关系的数据；所述环境光信息获取电路基于所述测得的所 述低频电信号的值和所述对应关系确定所述环境光的光强度。
具体地，在使用线性的光敏传感器PIN或APD时，其输出的光电流大小与输入光强成正比，激光接收电路对光电流的转换也成正比，即输出电压的幅值为输入光强的k倍。此处的k可以通过计算获得，只要已知光敏传感器对光电转换倍数和电路的放大倍数，即可得到光强度。一般光敏器件光电转换倍数存在较大的个体差异，理论计算将会存在较大的误差，可以通过标定将电压信号标定到环境光强。例如在机器出厂前，对激光接收电路照射已知光强的环境光，此时电路将会输出电压，输出电压与输入光强是线性的。因此可以测量多个不同环境光时的电压，计算线性因子并记录在机器内部。在使用时将测量得到的电压乘以该线性因子即可反推出环境光的强弱。通过上述方法实现对环境光的测量，进而在环境光较弱时，对预设阈值进行调整。
在另一个实施例中，本发明实施例还提供了一种测距装置，包括光发射电路，用于出射激光脉冲信号；上述的激光接收电路，用于接收光信号，以及将所述光信号转成电信号，其中，所述光信号包括经物体反射回的光脉冲信号和环境光信号，并将所述电信号分离成高频电信号和低频电信号，以及根据所述低频电信号获取所述环境光信号的信息；采样电路，用于对所述激光接收电路分离后的所述高频电信号进行采样，获得采样结果；运算电路，用于根据所述采样结果计算所述物体与所述测距装置之间的距离。
进一步地，所述光发射装置的数量为至少2个。
可选地，所述采样电路还包括比较电路，用于将从所述激光接收电路输入的电信号与预设阈值进行比较运算，提取与所述电信号对应的时间信息。
可选地，所述比较电路包括至少一个比较器，所述比较器的第一输入端用于接收所述从激光接收电路输入的电信号，所述比较器的第二输入端用于接收所述预设阈值，所述比较器的输出端用于输出比较运算的结果，其中，所述比较运算的结果中包含与所述电信号对应的时间信息。
可选地，比较电路还包括时间数字转换器(Time-to-Digital Converter，TDC)，时间数字转换器与比较器的输出端电连接，用于根据比较器输出的比较运算的 结果，提取与电信号对应的时间信息。
在所述测距装置中可以根据测定环境光的强弱对预设阈值进行调整，以使在环境光较弱的情况下，正常的光信号可以触发预设阈值，进而增加测量距离。在本发明的一实施例中，可以通过以下方式调整预设阈值：
本发明一实施例中，调整预设阈值的第一种实现方式调整比较电路的电压来调整比较电路的预设阈值。例如，所述测距装置包括数模转换器，可以通过数模转换器与比较电路输入端连接，并通过控制数模转换器的输出电压的大小来调整比较电路的预设阈值。
本发明一实施例中，调整预设阈值的第二种实现方式可以是：测距装置还可以包括比较阈值调整电路，比较阈值调整电路包括多个电阻，多个电阻的一端连接至比较器的输入端，多个电压信号输入到多个电阻的另一端，用于通过多个电阻向比较器的输入端提供预设阈值，通过调整多个电阻的组成结构，调整输入到比较电路的第二输入端的预设阈值。
在另一个实施例中，本发明实施例还提供了一种移动平台，所述移动平台包括上述的任一测距装置以及平台本体，所述测距装置安装在所述平台本体。进一步地，所述移动平台包括载人飞行器、无人飞行器、汽车、机器人和遥控车中的至少一种。
本发明各个实施例提供的光发射装置可以应用于测距装置，该测距装置可以是激光雷达、激光测距设备等电子设备。在一种实施方式中，测距装置用于感测外部环境信息，例如，环境目标的距离信息、方位信息、反射强度信息、速度信息等。一种实现方式中，测距装置可以通过测量测距装置和探测物之间光传播的时间，即光飞行时间(Time-of-Flight，TOF)，来探测探测物到测距装置的距离。或者，测距装置也可以通过其他技术来探测探测物到测距装置的距离，例如基于相位移动(phase shift)测量的测距方法，或者基于频率移动(frequency shift)测量的测距方法，在此不做限制。
为了便于理解，以下将结合图4所示的测距装置100对测距的工作流程进行举例描述。
如图4所示，测距装置100可以包括发射电路110、接收电路120、采样 电路130和运算电路140。
发射电路110可以发射光脉冲序列(例如激光脉冲序列)。接收电路120可以接收经过被探测物反射的光脉冲序列，并对该光脉冲序列进行光电转换，以得到电信号，再对电信号进行处理之后可以输出给采样电路130。采样电路130可以对电信号进行采样，以获取采样结果。运算电路140可以基于采样电路130的采样结果，以确定测距装置100与被探测物之间的距离。
可选地，该测距装置100还可以包括控制电路150，该控制电路150可以实现对其他电路的控制，例如，可以控制各个电路的工作时间和/或对各个电路进行参数设置等。
应理解，虽然图4示出的测距装置中包括一个发射电路、一个接收电路、一个采样电路和一个运算电路，但是本申请实施例并不限于此，发射电路、接收电路、采样电路、运算电路中的任一种电路的数量也可以是至少两个。
一些实现方式中，除了图4所示的电路，测距装置100还可以包括扫描模块160，用于将发射电路出射的激光脉冲序列改变传播方向出射。
其中，可以将包括发射电路110、接收电路120、采样电路130和运算电路140的模块，或者，包括发射电路110、接收电路120、采样电路130、运算电路140和控制电路150的模块称为测距模块，该测距模块150可以独立于其他模块，例如，扫描模块160。
测距装置中可以采用同轴光路，也即测距装置出射的光束和经反射回来的光束在测距装置内共用至少部分光路。或者，测距装置也可以采用异轴光路，也即测距装置出射的光束和经反射回来的光束在测距装置内分别沿不同的光路传输。图5示出了本发明的测距装置采用同轴光路的一种实施例的示意图。
测距装置200包括测距模块201，测距模块210包括发射器203(可以包括上述的发射电路)、准直元件204、探测器205(可以包括上述的接收电路、采样电路和运算电路)和光路改变元件206。测距模块210用于发射光束，且接收回光，将回光转换为电信号。其中，发射器203可以用于发射光脉冲序列。在一个实施例中，发射器203可以发射激光脉冲序列。可选的，发射器203发射出的激光束为波长在可见光范围之外的窄带宽光束。准直元件204设置于 发射器的出射光路上，用于准直从发射器203发出的光束，将发射器203发出的光束准直为平行光出射至扫描模块。准直元件还用于会聚经探测物反射的回光的至少一部分。该准直元件204可以是准直透镜或者是其他能够准直光束的元件。
在图2所示实施例中，通过光路改变元件206来将测距装置内的发射光路和接收光路在准直元件104之前合并，使得发射光路和接收光路可以共用同一个准直元件，使得光路更加紧凑。在其他的一些实现方式中，也可以是发射器103和探测器105分别使用各自的准直元件，将光路改变元件206设置在准直元件之后的光路上。
在图2所示实施例中，由于发射器103出射的光束的光束孔径较小，测距装置所接收到的回光的光束孔径较大，所以光路改变元件可以采用小面积的反射镜来将发射光路和接收光路合并。在其他的一些实现方式中，光路改变元件也可以采用带通孔的反射镜，其中该通孔用于透射发射器203的出射光，反射镜用于将回光反射至探测器205。这样可以减小采用小反射镜的情况中小反射镜的支架会对回光的遮挡。
在图2所示实施例中，光路改变元件偏离了准直元件204的光轴。在其他的一些实现方式中，光路改变元件也可以位于准直元件204的光轴上。
测距装置200还包括扫描模块202。扫描模块202放置于测距模块201的出射光路上，扫描模块102用于改变经准直元件204出射的准直光束219的传输方向并投射至外界环境，并将回光投射至准直元件204。回光经准直元件104汇聚到探测器105上。
在一个实施例中，扫描模块202可以包括至少一个光学元件，用于改变光束的传播路径，其中，该光学元件可以通过对光束进行反射、折射、衍射等等方式来改变光束传播路径。例如，扫描模块202包括透镜、反射镜、棱镜、振镜、光栅、液晶、光学相控阵(Optical Phased Array)或上述光学元件的任意组合。一个示例中，至少部分光学元件是运动的，例如通过驱动模块来驱动该至少部分光学元件进行运动，该运动的光学元件可以在不同时刻将光束反射、折射或衍射至不同的方向。在一些实施例中，扫描模块202的多个光学元件可 以绕共同的轴209旋转或振动，每个旋转或振动的光学元件用于不断改变入射光束的传播方向。在一个实施例中，扫描模块202的多个光学元件可以以不同的转速旋转，或以不同的速度振动。在另一个实施例中，扫描模块202的至少部分光学元件可以以基本相同的转速旋转。在一些实施例中，扫描模块的多个光学元件也可以是绕不同的轴旋转。在一些实施例中，扫描模块的多个光学元件也可以是以相同的方向旋转，或以不同的方向旋转；或者沿相同的方向振动，或者沿不同的方向振动，在此不作限制。
在一个实施例中，扫描模块202包括第一光学元件214和与第一光学元件214连接的驱动器216，驱动器216用于驱动第一光学元件214绕转动轴209转动，使第一光学元件214改变准直光束219的方向。第一光学元件214将准直光束219投射至不同的方向。在一个实施例中，准直光束219经第一光学元件改变后的方向与转动轴109的夹角随着第一光学元件214的转动而变化。在一个实施例中，第一光学元件214包括相对的非平行的一对表面，准直光束219穿过该对表面。在一个实施例中，第一光学元件214包括厚度沿至少一个径向变化的棱镜。在一个实施例中，第一光学元件114包括楔角棱镜，对准直光束119进行折射。
在一个实施例中，扫描模块202还包括第二光学元件215，第二光学元件215绕转动轴209转动，第二光学元件215的转动速度与第一光学元件214的转动速度不同。第二光学元件215用于改变第一光学元件214投射的光束的方向。在一个实施例中，第二光学元件115与另一驱动器217连接，驱动器117驱动第二光学元件215转动。第一光学元件214和第二光学元件215可以由相同或不同的驱动器驱动，使第一光学元件214和第二光学元件215的转速和/或转向不同，从而将准直光束219投射至外界空间不同的方向，可以扫描较大的空间范围。在一个实施例中，控制器218控制驱动器216和217，分别驱动第一光学元件214和第二光学元件215。第一光学元件214和第二光学元件215的转速可以根据实际应用中预期扫描的区域和样式确定。驱动器216和217可以包括电机或其他驱动器。
在一个实施例中，第二光学元件115包括相对的非平行的一对表面，光束 穿过该对表面。在一个实施例中，第二光学元件115包括厚度沿至少一个径向变化的棱镜。在一个实施例中，第二光学元件115包括楔角棱镜。
一个实施例中，扫描模块102还包括第三光学元件(图未示)和用于驱动第三光学元件运动的驱动器。可选地，该第三光学元件包括相对的非平行的一对表面，光束穿过该对表面。在一个实施例中，第三光学元件包括厚度沿至少一个径向变化的棱镜。在一个实施例中，第三光学元件包括楔角棱镜。第一、第二和第三光学元件中的至少两个光学元件以不同的转速和/或转向转动。
扫描模块202中的各光学元件旋转可以将光投射至不同的方向，例如方向211和213，如此对测距装置200周围的空间进行扫描。当扫描模块202投射出的光211打到探测物201时，一部分光被探测物201沿与投射的光211相反的方向反射至测距装置200。探测物201反射的回光212经过扫描模块202后入射至准直元件204。
探测器205与发射器203放置于准直元件204的同一侧，探测器205用于将穿过准直元件204的至少部分回光转换为电信号。
一个实施例中，各光学元件上镀有增透膜。可选的，增透膜的厚度与发射器103发射出的光束的波长相等或接近，能够增加透射光束的强度。
一个实施例中，测距装置中位于光束传播路径上的一个元件表面上镀有滤光层，或者在光束传播路径上设置有滤光器，用于至少透射发射器所出射的光束所在波段，反射其他波段，以减少环境光给接收器带来的噪音。
在一些实施例中，发射器203可以包括激光二极管，通过激光二极管发射纳秒级别的激光脉冲。进一步地，可以确定激光脉冲接收时间，例如，通过探测电信号脉冲的上升沿时间和/或下降沿时间确定激光脉冲接收时间。如此，测距装置200可以利用脉冲接收时间信息和脉冲发出时间信息计算TOF，从而确定探测物201到测距装置200的距离。
测距装置200探测到的距离和方位可以用于遥感、避障、测绘、建模、导航等。在一种实施方式中，本发明实施方式的测距装置可应用于移动平台，测距装置可安装在移动平台的平台本体。具有测距装置的移动平台可对外部环境进行测量，例如，测量移动平台与障碍物的距离用于避障等用途，和对外部环 境进行二维或三维的测绘。在某些实施方式中，移动平台包括无人飞行器、汽车、遥控车、机器人、相机中的至少一种。当测距装置应用于无人飞行器时，平台本体为无人飞行器的机身。当测距装置应用于汽车时，平台本体为汽车的车身。该汽车可以是自动驾驶汽车或者半自动驾驶汽车，在此不做限制。当测距装置应用于遥控车时，平台本体为遥控车的车身。当测距装置应用于机器人时，平台本体为机器人。当测距装置应用于相机时，平台本体为相机本身。
本发明通过提供上述光发射装置、测距装置以及移动平台，以提供一种符合人眼安全规定的激光发射方案，当系统发生单一故障时，上述装置中的电路可以保证激光辐射值不超过安规值，从而保证激光装置的使用安全。
本发明实施例中所使用的技术术语仅用于说明特定实施例而并不旨在限定本发明。在本文中，单数形式“一”、“该”及“所述”用于同时包括复数形式，除非上下文中明确另行说明。进一步地，在说明书中所使用的用于“包括”和/或“包含”是指存在所述特征、整体、步骤、操作、元件和/或构件，但是并不排除存在或增加一个或多个其它特征、整体、步骤、操作、元件和/或构件。
在所附权利要求中对应结构、材料、动作以及所有装置或者步骤以及功能元件的等同形式(如果存在的话)旨在包括结合其他明确要求的元件用于执行该功能的任何结构、材料或动作。本发明的描述出于实施例和描述的目的被给出，但并不旨在是穷举的或者将被发明限制在所公开的形式。在不偏离本发明的范围和精神的情况下，多种修改和变形对于本领域的一般技术人员而言是显而易见的。本发明中所描述的实施例能够更好地揭示本发明的原理与实际应用，并使本领域的一般技术人员可了解本发明。
本发明中所描述的流程图仅仅为一个实施例，在不偏离本发明的精神的情况下对此图示或者本发明中的步骤可以有多种修改变化。比如，可以不同次序的执行这些步骤，或者可以增加、删除或者修改某些步骤。本领域的一般技术人员可以理解实现上述实施例的全部或部分流程，并依本发明权利要求所作的等同变化，仍属于发明所涵盖的范围。

Claims (20)

  1. 一种激光接收电路，其特征在于，包括：光电转换电路和分离电路；
    其中，所述光电转换电路，用于接收光信号，以及将所述光信号转成电信号，所述光信号包括经物体反射回的光脉冲信号和环境光信号；
    所述分离电路，用于将所述电信号分离成高频电信号和低频电信号，所述高频电信号的频率高于所述低频电信号的频率的至少10倍，
    环境光信息获取电路，用于根据所述低频电信号获取所述环境光信号的信息。
  2. 根据权利要求1所述的激光接收电路，其特征在于，所述分离电路包括彼此并联连接设置两个支路，其中一个支路为高频响应电路，用于仅对所述高频电信号响应，以滤除所述低频电信号；
    另外一个支路为低频响应电路，用于仅对所述低频电信号响应，以滤除所述高频电信号，进而分离所述高频电信号和低频电信号。
  3. 根据权利要求2所述的激光接收电路，其特征在于，所述高频响应电路包括彼此串联连接的高速放大器和交流耦合器；
    所述交流耦合器与所述高速放大器进行交流耦合，用于过滤所述低频电信号，所述高速放大器用于对所述高频电信号放大。
  4. 根据权利要求3所述的激光接收电路，其特征在于，所述交流耦合器包括至少一电容，和/或所述高速放大器包括至少一个高速跨阻放大器。
  5. 根据权利要求2所述的激光接收电路，其特征在于，所述低频响应电路包括至少一个低速跨阻放大器。
  6. 根据权利要求2所述的激光接收电路，其特征在于，所述低频响应电路至少包括一电流镜，用于将所述低频电信号直接输出或放大数倍后输出。
  7. 根据权利要求6所述的激光接收电路，其特征在于，所述低频响应电路还包括一第一放大电路和/或电信号转换电路；
    其中，所述第一放大电路用于对所述电流镜输出的电信号放大；
    所述电信号转换电路包括至少一电阻，用于将所述电流镜输出的电流信号 转换为电压信号。
  8. 根据权利要求7所述的激光接收电路，其特征在于，所述电流镜包括BJT器件、MOSFET器件和JFET器件中的至少一种。
  9. 根据权利要求2至8之一所述的激光接收电路，其特征在于，所述分离电路还包括放大器，所述放大器串联于所述光电转换电路与所述分离电路之间，以对所述高频电信号和所述低频电信号进行放大。
  10. 根据权利要求9所述的激光接收电路，其特征在于，所述低频响应电路包括彼此串联连接的低通滤波器和第二放大电路；
    或所述低频响应电路还包括一二级放大电路，以对所述低频响应电路响应的所述低频电信号进一步放大。
  11. 根据权利要求1所述的激光接收电路，其特征在于，所述光电转换电路包括光敏传感器，用于接收所述激光脉冲信号，以及将所述激光脉冲信号转换为电信号。
  12. 根据权利要求1所述的激光接收电路，其特征在于，所述环境光信息获取电路内预存有在不同环境光强度下的光强度与所述低频电信号的对应关系的数据；
    所述环境光信息获取电路基于所述测得的所述低频电信号的值和所述对应关系确定所述环境光的光强度。
  13. 根据权利要求12所述的环境光测量装置，其特征在于，所述不同环境光强度下的光强度与低频电压呈线性关系。
  14. 根据权利要求1所述的环境光测量装置，其特征在于，所述高频电信号的频率高于所述低频电信号的频率的至少50倍。
  15. 一种测距装置，其特征在于，包括：
    光发射电路，用于出射激光脉冲信号；
    如权利要求1至14任一项所述的激光接收电路，用于接收光信号，以及将所述光信号转成电信号，其中，所述光信号包括经物体反射回的光脉冲信号和环境光信号，并将所述电信号分离成高频电信号和低频电信号，以及根据所述低频电信号获取所述环境光信号的信息；
    采样电路，用于对所述激光接收电路分离后的所述高频电信号进行采样，获得采样结果；
    运算电路，用于根据所述采样结果计算所述物体与所述测距装置之间的距离。
  16. 根据权利要求15所述的测距装置，其特征在于，所述采样电路还包括比较电路，用于将从所述激光接收电路输入的电信号与预设阈值进行比较运算，提取与所述电信号对应的时间信息。
  17. 根据权利要求15所述的测距装置，其特征在于，所述比较电路包括至少一个比较器，所述比较器的第一输入端用于接收所述从激光接收电路输入的电信号，所述比较器的第二输入端用于接收所述预设阈值，所述比较器的输出端用于输出比较运算的结果，其中，所述比较运算的结果中包含与所述电信号对应的时间信息。
  18. 根据权利要求17所述的测距装置，其特征在于，所述比较电路还包括时间数字转换器，所述时间数字转换器与所述比较器的输出端电连接，用于根据所述比较器输出的比较运算的结果，提取与所述电信号对应的时间信息。
  19. 一种移动平台，其特征在于，包括：
    权利要求15至18任一项所述的测距装置；和
    平台本体，所述测距装置安装在所述平台本体上。
  20. 根据权利要求19所述的移动平台，其特征在于，所述移动平台包括无人飞行器、汽车和机器人中的至少一种。
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