Light receiving device for laser radar and dynamic adjustment method of light receiving device

Abstract

The invention provides a light receiving device for a laser radar and a method for dynamically adjusting the light receiving device, and the device comprises a photoelectric sensor which comprises a plurality of pixel units, each pixel unit comprises a single photon avalanche diode, and the pixel units are configured to detect the avalanche of a single photon and convert the avalanche into an output electric signal; a voltage source configured to provide a bias voltage to the photosensor; the adjusting unit is coupled between the voltage source and the photoelectric sensor and is configured to adjust the bias voltage of the photoelectric sensor according to the intensity of the ambient light so as to adjust the photon detection efficiency of the photoelectric sensor, and when the intensity of the ambient light is not greater than a second threshold value, the photon detection efficiency of the photoelectric sensor is increased; wherein the photon detection efficiency is represented by the ratio of the number of photons detected by the photoelectric sensor to the number of photons incident to the photoelectric sensor.

Description

Technical Field

[0001] The present invention relates to the field of laser detection, and particularly to an optical receiving device for a lidar and a method for dynamically adjusting the optical receiving device. Background Art

[0002] Lidar is currently widely used in the field of driverless. As a photoelectric sensor at the receiving end, compared with an avalanche photodiode (APD), a silicon photomultiplier (SiPM) has a manufacturing process compatible with the CMOS process, and its readout circuit is simpler and easier to integrate, making it an ideal sensor for the receiving end of lidar.

[0003] A silicon photomultiplier (SiPM) is an array composed of multiple pixel units. Each pixel unit is composed of a single-photon avalanche diode (SPAD) operating in Geiger mode and a quenching resistor in series therewith, where each single-photon avalanche photodiode (SPAD) is in series with a quenching resistor. When a photon is received by the single-photon avalanche diode, an electron-hole pair is formed. In the space charge region, the electron is accelerated to obtain sufficient kinetic energy, and secondary electron-hole pairs are formed through impact ionization, finally triggering a self-sustaining ionization cascade, making the silicon conductive and thus generating a current.

[0004] After the single-photon avalanche diode generates a current, the quenching resistor in series with the single-photon avalanche diode will obtain a relatively high voltage division, causing the voltage across the single-photon avalanche photodiode to drop below the breakdown voltage, thereby preventing the avalanche. Subsequently, the single-photon avalanche diode is recharged and restored to the state before breakdown, and then photon detection can be carried out again.

[0005] This working process determines that a single-photon avalanche diode will have a recovery time after detecting a photon. And the pixel unit composed of a single-photon avalanche diode (SPAD) and a quenching resistor in series also has such a characteristic.

[0006] This recovery time will cause most of the pixel units in the silicon photomultiplier to be continuously in the avalanche state and the charging and recovery process when the ambient light signal is strong, and thus cannot work normally, which will seriously affect the normal use of the lidar using it as the receiving end.

[0007] In the disclosed technologies, some special treatments are adopted to overcome the above defects. For example, the receiving field of view is reduced by adding a diaphragm. However, the use of the diaphragm will inhibit the ability of the lidar to measure short-range targets in the paraxial optical path, and will make optical installation and alignment more difficult during production; the small hole used as the diaphragm will inhibit the lidar from receiving the echo signal while suppressing the lidar from receiving ambient light, thereby reducing the long-range measurement ability of the lidar under weak ambient light conditions.

[0008] The content in the background technology section is only the technology known to the applicant and does not necessarily represent the prior art in this field. Summary of the Invention

[0009] To solve the problem that multiple pixel units of a silicon photomultiplier tube continuously avalanche under strong ambient light conditions and at the same time improve the ranging ability of a lidar under weak ambient light conditions, the present invention provides an optical receiving device for a lidar, including:

[0010] A silicon photomultiplier tube configured to receive photons and convert them into an output electrical signal;

[0011] A voltage source configured to provide a bias voltage to the silicon photomultiplier tube; and

[0012] An adjustment unit respectively coupled to the voltage source and the silicon photomultiplier tube and configured to adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of ambient light.

[0013] According to one aspect of the present invention, the adjustment unit adjusts the bias voltage of the silicon photomultiplier tube according to the intensity of ambient light, thereby adjusting the photon detection efficiency of the silicon photomultiplier tube.

[0014] According to one aspect of the present invention, the adjustment unit includes:

[0015] A first resistor unit connected in series between the voltage source and the silicon photomultiplier tube and configured to adjust the voltage of the silicon photomultiplier tube according to the intensity of ambient light;

[0016] A first capacitor unit connected in parallel with the silicon photomultiplier tube and configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light.

[0017] According to one aspect of the present invention, the adjustment unit includes:

[0018] A current detection unit coupled to the voltage source and configured to detect the current passing through the silicon photomultiplier tube;

[0019] A control unit coupled to the current detection unit and configured to output a control signal according to the current;

[0020] A voltage adjustment unit coupled between the control unit and the silicon photomultiplier tube and configured to dynamically adjust the bias voltage on the silicon photomultiplier tube according to the control signal.

[0021] According to one aspect of the present invention, the current detection unit includes:

[0022] A second resistor unit configured such that one end thereof is coupled to the voltage source and the other end thereof is coupled to the input end of the voltage adjustment unit;

[0023] An operational amplifier configured to be coupled to the second resistor unit at both ends.

[0024] According to one aspect of the present invention, the optical receiving device further includes a first capacitor unit, which is connected in parallel with the silicon photomultiplier tube and configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light.

[0025] According to one aspect of the present invention, the silicon photomultiplier tube is configured to receive ambient light and convert it into an output electrical signal.

[0026] According to one aspect of the present invention, the adjustment unit is configured to:

[0027] When the intensity of the ambient light is not less than the first threshold, reduce the photon detection efficiency of the silicon photomultiplier tube;

[0028] When the intensity of the ambient light is not greater than the second threshold, increase the photon detection efficiency of the silicon photomultiplier tube.

[0029] According to one aspect of the present invention, the first threshold and the second threshold are configured to be determined according to the standard normal distribution of the ambient light intensity.

[0030] According to one aspect of the present invention, the voltage adjustment unit includes any one of a metal-oxide-semiconductor field-effect transistor (MOSFET) and a bipolar junction transistor (BJT) with an adjustable resistance value.

[0031] According to one aspect of the present invention, the voltage adjustment unit includes a low dropout linear regulator (LDO), and the low dropout linear regulator (LDO) is used to control the voltage output to the silicon photomultiplier tube.

[0032] The present invention also provides a method for dynamically adjusting the optical receiving device as described above, including:

[0033] Receiving photons through the silicon photomultiplier tube and converting them into an output electrical signal;

[0034] According to the intensity of the ambient light, adjusting the photon detection efficiency of the silicon photomultiplier tube through the adjustment unit.

[0035] According to one aspect of the present invention, the method further includes:

[0036] According to the intensity of the ambient light, adjusting the bias voltage of the silicon photomultiplier tube through the adjustment unit, thereby adjusting the photon detection efficiency of the silicon photomultiplier tube.

[0037] According to one aspect of the present invention, the optical receiving device further includes: a first resistor unit connected in series between the voltage source and the silicon photomultiplier tube, and a first capacitor unit connected in parallel with the silicon photomultiplier tube. The method further includes:

[0038] Adjust the voltage on the silicon photomultiplier tube according to the intensity of ambient light through the first resistor unit;

[0039] Keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light through the first capacitor unit.

[0040] According to one aspect of the present invention, the optical receiving device further includes: a current detection unit coupled to the voltage source; a control unit coupled to the current detection unit; and a voltage adjustment unit coupled between the control unit and the silicon photomultiplier tube. The method further includes:

[0041] Detect the current passing through the silicon photomultiplier tube through the current detection unit;

[0042] Output a control signal according to the current through the control unit;

[0043] Dynamically adjust the bias voltage on the silicon photomultiplier tube according to the control signal through the voltage adjustment unit.

[0044] According to one aspect of the present invention, the optical receiving device further includes: a first capacitor unit connected in parallel with the silicon photomultiplier tube, configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light. The method further includes:

[0045] When the intensity of the ambient light is not less than the first threshold, reduce the photon detection efficiency of the silicon photomultiplier tube;

[0046] When the intensity of the ambient light is not greater than the second threshold, increase the photon detection efficiency of the silicon photomultiplier tube.

[0047] According to one aspect of the present invention, the first threshold and the second threshold can be determined according to the standard normal distribution of the ambient light intensity.

[0048] A preferred embodiment of the present invention provides an optical receiving device with a dynamic adjustment circuit and a method for dynamically adjusting the optical receiving device. The dynamic adjustment circuit can adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of ambient light, so as to reduce the photon detection efficiency and the number of pixel units with continuous avalanche under strong ambient light conditions; and increase the photon detection efficiency under weak ambient light conditions, thereby improving the ranging ability of the lidar. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the accompanying drawings:

[0050] Figure 1 The structure of a silicon photomultiplier is schematically shown;

[0051] Figure 2 A light receiving device according to a preferred embodiment of the present invention is schematically shown;

[0052] Figure 3 A light receiving device according to a preferred embodiment of the present invention is schematically shown;

[0053] Figure 4 A light receiving device according to a preferred embodiment of the present invention is schematically shown;

[0054] Figure 5 A light receiving device according to a preferred embodiment of the present invention is schematically shown;

[0055] Figure 6 A flowchart of a method for dynamically adjusting a light receiving device according to a preferred embodiment of the present invention is shown;

[0056] Figure 7 A flowchart of a method for dynamically adjusting a light receiving device according to a preferred embodiment of the present invention based on a dual threshold is shown. Detailed implementation manners

[0057] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the accompanying drawings and the description are considered to be exemplary in nature rather than restrictive.

[0058] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0059] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral connection: it may be a mechanical connection, an electrical connection or may communicate with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0061] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0062] The embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0063] The internal structure of the silicon photomultiplier (SiPM) 11 is as Figure 1 shown. The most basic unit of the silicon photomultiplier 11 is a pixel unit (shown by the dotted box in the figure) composed of a single-photon avalanche diode (SPAD) 111 operating in Geiger mode and a series quenching resistor 112. Multiple pixel units are arranged in a two-dimensional direction to form the silicon photomultiplier 11. The photon detection efficiency of the silicon photomultiplier 11 refers to the ratio of the number of photons detected by the silicon photomultiplier 11 to the number of incident photons, that is, the efficiency of the silicon photomultiplier 11 in converting an optical signal into an electrical signal (for example: when 100 photons are incident on the silicon photomultiplier 11, and the silicon photomultiplier 11 detects 90 photons and converts them into electrical signals, then the photon detection efficiency of the silicon photomultiplier 11 is 90%). The higher the photon detection efficiency, the stronger the sensitivity of the silicon photomultiplier to photons; the weaker the photon detection efficiency, the weaker the sensitivity of the silicon photomultiplier to photons.

[0064] The working process of the silicon photomultiplier 11 is as follows: when a single photon is incident on a pixel unit, if the photon is detected by the pixel unit, it will cause an avalanche in the single-photon avalanche diode 111 in the pixel unit, and the junction capacitance of the single-photon avalanche diode 111 ( Figure 1(not shown) The accumulated charge flows from the anode to the cathode, the bias voltage across the single-photon avalanche diode 111 drops, the avalanche stops, the voltage change ΔV across the single-photon avalanche diode 111 is output through the fast output capacitor 113, and then the quenching resistor 112 charges the junction capacitance of the single-photon avalanche diode 112 to restore it to the Geiger mode. Only when the single-photon avalanche diode 111 is restored to the Geiger mode can it continue to respond to the next photon. The time for the quenching resistor 112 to charge the junction capacitance of the single-photon avalanche diode 111 is the recovery time of the single-photon avalanche diode 111.

[0065] When multiple photons are incident on different pixel units, multiple single-photon avalanche diodes 111 will undergo avalanches. In this way, multiple fast output capacitors 113 connected to the multiple avalanche photodiodes 111 will output the voltage changes of each single-photon avalanche diode 111. The voltage changes output by the multiple single-photon avalanche diodes 111 are accumulated and the total voltage change ΔV is output. The more the number of single-photon avalanche diodes 111 that undergo avalanches, the greater the accumulated total voltage change ΔV output; the more the number of single-photon avalanche diodes 111 that undergo avalanches, the more the charge quantity for charging the junction capacitance in the single-photon avalanche diode 111 through the quenching resistor, that is, the greater the generated charging current.

[0066] Since the silicon photomultiplier can detect single photons, when the continuous ambient light is strong, most of the pixel units in the silicon photomultiplier detect the ambient light signal and are continuously in the avalanche and charge recovery process. Such a characteristic causes the silicon photomultiplier to be unable to perform subsequent detections. The present invention provides a silicon photomultiplier with a dynamic adjustment circuit. The dynamic adjustment circuit can adjust the photon detection efficiency of the silicon photomultiplier according to the intensity of the ambient light, so as to reduce the photon detection efficiency and reduce the number of pixel units with continuous avalanches under strong ambient light conditions; under weak ambient light conditions, improve the photon detection efficiency to improve the ranging ability of the lidar.

[0067] According to a preferred embodiment of the present invention, as Figure 2 shown, the present invention provides an optical receiving device 10 for a lidar, including: a silicon photomultiplier 11, a voltage source 12, and an adjustment unit 13. The silicon photomultiplier 11 is configured to receive photons and convert them into an output electrical signal (total voltage change ΔV). This output electrical signal can be an output voltage, used as a detection signal to calculate the distance and / or reflectivity of the target object. The voltage source 12 is configured to provide a bias voltage to the silicon photomultiplier 11, and the photon detection efficiency of the silicon photomultiplier 11 can be adjusted by adjusting this bias voltage. The adjustment unit 13 is respectively coupled to the voltage source 12 and the silicon photomultiplier 11, and is configured to adjust the photon detection efficiency of the silicon photomultiplier 11 according to the intensity of the ambient light.

[0068] According to a preferred embodiment of the present invention, the photon detection efficiency of the silicon photomultiplier tube 11 is determined by the bias voltage across the silicon photomultiplier tube 11. When the bias voltage across the silicon photomultiplier tube 11 is larger, the photon detection efficiency is higher; when the bias voltage across the silicon photomultiplier tube 11 is smaller, the photon detection efficiency is lower. The adjustment unit 13 can actively or passively adjust the bias voltage across the silicon photomultiplier tube 11 according to the intensity of the ambient light, thereby adjusting the photon detection efficiency of the silicon photomultiplier tube 11. The intensity of the ambient light is obtained based on the detection result of the silicon photomultiplier tube 11. The change in the intensity of the ambient light causes the number of pixel units in the silicon photomultiplier tube 11 to undergo avalanche, resulting in a corresponding change in the current generated by the silicon photomultiplier tube 11. Thus, the bias voltage across the silicon photomultiplier tube 11 can be dynamically adjusted according to the change in the current passing through the silicon photomultiplier tube 11.

[0069] According to a preferred embodiment of the present invention, as Figure 3 shown, the adjustment unit 13 of the light receiving device 10 includes: a first resistor unit 131 and a first capacitor unit 132. The first resistor unit 131 is connected in series between the voltage source 12 and the silicon photomultiplier tube 11, and adjusts the bias voltage of the silicon photomultiplier tube 11 according to the intensity of the ambient light. When the ambient light increases, the first resistor unit 131 causes the bias voltage of the silicon photomultiplier tube 11 to decrease; when the ambient light decreases, the first resistor unit 131 causes the bias voltage of the silicon photomultiplier tube 11 to increase. The first capacitor unit 132 is connected in parallel with the silicon photomultiplier tube 11 and is configured to keep the bias voltage across the silicon photomultiplier tube 11 stable when receiving signal light.

[0070] Specifically, a first resistor unit 131 is connected in series between the silicon photomultiplier tube 11 and the voltage source 12. Under strong ambient light conditions, the more the number of incident photons, the more the number of pixel units undergoing avalanche, the larger the current passing through the silicon photomultiplier tube 11, the increase in the current passing through the first resistor unit 131, thereby causing the voltage across the first resistor unit 131 to rise, the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 to decrease, the photon detection efficiency to decrease, and the number of pixel units undergoing avalanche to decrease. Under weak ambient light conditions, the fewer the number of incident photons, the fewer the number of pixel units undergoing avalanche, the smaller the current passing through the silicon photomultiplier tube 11, the decrease in the current passing through the first resistor unit 131, thereby causing the voltage across the first resistor unit 131 to drop, the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 to increase, the photon detection efficiency to increase, and the number of pixel units undergoing avalanche to increase.

[0071] The first capacitor unit 132 can ensure that the bias voltage across the device changes little when the silicon photomultiplier tube 11 receives a laser pulse within a short time. When the silicon photomultiplier tube 11 detects the signal light, since the duration of the signal light is very short (for example, the pulse width is 3 ns), the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 will drop rapidly, resulting in the first capacitor unit 132 releasing relatively little charge. Since the amount of charge stored in the first capacitor unit 132 is much larger than the released charge, the total charge amount of the first capacitor unit 132 remains basically unchanged. Therefore, the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 is basically stable. When the silicon photomultiplier tube 11 detects continuous ambient light, since the duration of the ambient light is very long, it causes the first capacitor unit 132 to continuously release charge, thereby causing the voltage across the first capacitor unit 132 to continuously drop, resulting in the bias voltage across the silicon photomultiplier tube 11 to continuously drop. When the voltage across the first capacitor unit 132 reaches the difference between the voltage of the voltage source 12 and the voltage across the first resistor unit 131, the first capacitor unit 132 stops releasing charge.

[0072] Therefore, the combination of the first capacitor unit 132 and the first resistor unit 131 can adjust the bias voltage of the silicon photomultiplier tube 11 in the presence of ambient light, thereby adjusting the photon detection efficiency; in the case of signal light incident, the bias voltage of the silicon photomultiplier tube 11 is stabilized, thereby ensuring that the signal light is detected. It is easy for those skilled in the art to understand that the first resistor unit and the first capacitor unit can be resistor devices and capacitor devices, or other devices that implement the functions of the first resistor unit and the first capacitor unit.

[0073] According to a preferred embodiment of the present invention, as Figure 4 shown, the adjustment unit 13 of the light receiving device 10 includes: a current detection unit 137, a control unit 134, and a voltage adjustment unit 135. The current detection unit 137 is coupled to the voltage source 12 and is configured to detect the current passing through the silicon photomultiplier tube 11. The control unit 134 is coupled to the current detection unit 137 and is configured to output a control signal according to the detected current. The voltage adjustment unit 135 is coupled between the control unit 134 and the silicon photomultiplier tube 11 and is configured to dynamically adjust the bias voltage on the silicon photomultiplier tube 11 according to the control signal.

[0074] A voltage regulating unit 135 is connected in series between the silicon photomultiplier tube 11 and the voltage source 12. The voltage regulating unit 135 can be a metal-oxide-semiconductor field-effect transistor (MOSFET) with an adjustable resistance value, a bipolar junction transistor (BJT), or a voltage regulator device such as a low-dropout linear regulator (LDO). The current detection unit 137 detects the current passing through the silicon photomultiplier tube 11, and the control unit 134 controls the voltage regulating unit 135 based on the current detected by the current detection unit 137, so as to dynamically adjust the bias voltage between the anode and cathode of the silicon photomultiplier tube 11. Under strong ambient light conditions, the more incident photons there are, the more pixel units that undergo avalanche, resulting in an increase in the current of the silicon photomultiplier tube 11. The voltage regulating unit 135 adjusts the bias voltage between the anode and cathode of the silicon photomultiplier tube 11, causing the bias voltage to decrease, the photon detection efficiency to decrease, and the number of pixel units that undergo avalanche to decrease. Under weak ambient light conditions, the fewer incident photons there are, the fewer pixel units that undergo avalanche, the current of the silicon photomultiplier tube 11 decreases, and the voltage regulating unit 135 adjusts the bias voltage between the anode and cathode of the silicon photomultiplier tube 11, causing the bias voltage to increase, the photon detection efficiency to increase, and the number of pixel units that undergo avalanche to increase.

[0075] According to a preferred embodiment of the present invention, the control unit 134 is configured to: when the intensity of the ambient light is not less than the first threshold, control the voltage regulating unit 135 to adjust the bias voltage to reduce the photon detection efficiency of the silicon photomultiplier tube 11; when the intensity of the ambient light is not greater than the second threshold, control the voltage regulating unit 135 to adjust the bias voltage to increase the photon detection efficiency of the silicon photomultiplier tube 11. The first threshold and the second threshold can be determined according to the standard normal distribution of the ambient light intensity historical data. For example, according to the standard normal distribution of the ambient light intensity, the first threshold and the second threshold are determined at 2 standard deviations from the average value of the ambient light intensity. The first threshold is the light intensity value at 2 positive standard deviations from the average value of the ambient light intensity; and the second threshold is the light intensity value at 2 negative standard deviations from the average value of the ambient light intensity. At the same time, when the signal light is incident, the voltage regulating unit 135 also plays a role in stabilizing the bias voltage. It is easy for those skilled in the art to understand that the object compared by the control unit 134 can be the intensity of the ambient light and the first threshold / second threshold, or the current flowing through the silicon photomultiplier tube 11 and the first current threshold / second current threshold, where the intensity of the ambient light corresponds to the current, the first threshold corresponds to the first current threshold, and the second threshold corresponds to the second current threshold. After the detection circuit design is completed, through simulation or experiment, the first current threshold corresponding to the ambient light being the first threshold and the second current threshold corresponding to the ambient light being the second threshold can be determined, so as to be used in the control logic of the control unit 134.

[0076] Preferably, the voltage regulating unit 135 can be implemented by a transient-enhanced LDO circuit for controlling the voltage output to the silicon photomultiplier tube.

[0077] According to a preferred embodiment of the present invention, as Figure 4 shown, the current detection unit 137 includes a second resistor unit 136 configured such that one end thereof is coupled to the voltage source 12 and the other end thereof is coupled to the input terminal of the voltage regulating unit 135; and an operational amplifier 133 configured such that both ends thereof are coupled to the second resistor unit 136.

[0078] According to a preferred embodiment of the present invention, as Figure 5 shown, the adjustment unit 13 of the optical receiving device 10 includes a current detection unit 137, a control unit 134, a voltage regulating unit 135, and a first capacitor unit 132.

[0079] The current detection unit 137 is coupled to the voltage source 12 and is configured to detect the current passing through the silicon photomultiplier tube 11, wherein the current detection unit 137 includes a second resistor unit 136 configured such that one end thereof is coupled to the voltage source 12 and the other end thereof is coupled to the input terminal of the voltage regulating unit 135; and an operational amplifier 133 configured such that both ends thereof are coupled to the second resistor unit 136. The control unit 134 is coupled to the current detection unit 137 and is configured to output a control signal according to the current. The voltage regulating unit 135 is coupled between the control unit 134 and the silicon photomultiplier tube 11 and is configured to dynamically adjust the bias voltage on the silicon photomultiplier tube 11 according to the control signal. The first capacitor unit 132 is connected in parallel with the silicon photomultiplier tube 11 and is configured to keep the bias voltage on the silicon photomultiplier tube 11 stable when receiving signal light.

[0080] Figure 5Embodiments can achieve the switching between the active adjustment mode and the passive adjustment mode. In the active mode, switch 138 is disconnected, and a second resistor unit 136 and a voltage regulation unit 135 are connected in series between the silicon photomultiplier 11 and the voltage source 12. The voltage regulation unit 135 can be a metal-oxide-semiconductor field-effect transistor (MOSFET) or a bipolar junction transistor (BJT) with an adjustable resistance value. The current detection unit 137 detects the current passing through the silicon photomultiplier 11, and the control unit 134 dynamically adjusts the voltage regulation unit 135 based on the current detected by the current detection unit 137, thereby dynamically adjusting the bias voltage between the anode and cathode of the silicon photomultiplier 11. At the same time, when the signal light is incident, the voltage regulation unit 135 also plays a role in stabilizing the bias voltage. In the passive mode, the control unit 134 is turned off, and the voltage regulation unit 135 is kept unchanged (for example, in the state of a constant resistor), switch 138 is closed, and the second resistor unit 136 is connected in series between the voltage source 12 and the silicon photomultiplier 11 to adjust the bias voltage of the silicon photomultiplier 11 according to the intensity of the ambient light. The first capacitor unit 132 is connected in parallel with the silicon photomultiplier 11 and is configured to keep the bias voltage on the silicon photomultiplier 11 stable when receiving the signal light. It is easy for those skilled in the art to understand that the second resistor unit and the first capacitor unit can be a second resistor and a first capacitor, or other devices that implement the functions of the second resistor and the first capacitor. The ambient light can be received by the silicon photomultiplier and converted into an output electrical signal, and the output electrical signal can characterize the intensity of the ambient light.

[0081] This dual-mode circuit can select between the active mode and the passive mode. The active mode has a larger dynamic adjustment range, a fast response speed, a high adjustment accuracy, and can achieve temperature compensation, and is suitable for application scenarios such as detecting a larger range of ambient light, higher-precision adjustment, and a larger operating temperature range; the passive mode is relatively power-saving and is suitable for application scenarios without control, and the application is more convenient.

[0082] According to a preferred embodiment of the present invention, as Figure 6 shown, the present invention also provides a method 20 for dynamically adjusting the optical receiving device 10 as described above, including:

[0083] In step S201, photons are received by the silicon photomultiplier 11 and converted into an output electrical signal, and the output electrical signal can be an output voltage, which is used as a detection signal to calculate the distance and / or reflectivity of the target object.

[0084] In step S202, according to the intensity of the ambient light, the photon detection efficiency of the silicon photomultiplier 11 is adjusted by the adjustment unit 13.

[0085] According to a preferred embodiment of the present invention, the adjustment method 20 further includes:

[0086] According to the intensity of the ambient light, the bias voltage of the silicon photomultiplier tube 11 is adjusted by the adjustment unit 13 to adjust the photon detection efficiency of the silicon photomultiplier tube 11. The photon detection efficiency of the silicon photomultiplier tube 11 is determined by the bias voltage across the silicon photomultiplier tube 11. When the bias voltage across the silicon photomultiplier tube 11 is larger, the photon detection efficiency is higher; when the bias voltage across the silicon photomultiplier tube 11 is smaller, the photon detection efficiency is lower. The adjustment unit 13 actively or passively adjusts the bias voltage on the silicon photomultiplier tube 11 according to the intensity of the ambient light, thereby adjusting the photon detection efficiency of the silicon photomultiplier tube 11. Wherein, the change in the intensity of the ambient light causes the number of avalanches in the pixel units in the silicon photomultiplier tube 11 to change, resulting in a corresponding change in the current generated by the silicon photomultiplier tube 11. Thus, the bias voltage on the silicon photomultiplier tube 11 can be dynamically adjusted according to the change in the current passing through the silicon photomultiplier tube 11.

[0087] According to a preferred embodiment of the present invention, the optical receiving device 10 further includes: a first resistor unit 131, connected in series between the voltage source 12 and the silicon photomultiplier tube 11, and a first capacitor unit 132, connected in parallel with the silicon photomultiplier tube 11. The method 20 further includes:

[0088] Adjust the voltage on the silicon photomultiplier tube 11 by the first resistor unit 131 according to the strength of the ambient light.

[0089] Keep the bias voltage on the silicon photomultiplier tube 11 stable by the first capacitor unit 132 when receiving the signal light.

[0090] The combination of the first capacitor unit 132 and the first resistor unit 131 can adjust the bias voltage of the silicon photomultiplier tube 11 in the presence of ambient light, thereby adjusting the photon detection efficiency; in the presence of signal light incident, stabilize the bias voltage of the silicon photomultiplier tube 11, thereby ensuring that the signal light is detected.

[0091] According to a preferred embodiment of the present invention, the optical receiving device 10 further includes: a current detection unit 137, coupled to the voltage source 12; a control unit 134, coupled to the current detection unit 137; a voltage adjustment unit 135, coupled between the control unit 134 and the silicon photomultiplier tube 11. The method 20 further includes:

[0092] Detect the current passing through the silicon photomultiplier tube 11 by the current detection unit 137;

[0093] Output a control signal by the control unit 134 according to the detected current;

[0094] Dynamically adjust the bias voltage on the silicon photomultiplier tube 11 by the voltage adjustment unit 135 according to the control signal.

[0095] According to a preferred embodiment of the present invention, the optical receiving device 10 further includes: a first capacitor unit 132, connected in parallel with the silicon photomultiplier tube 11 and configured to keep the bias voltage on the silicon photomultiplier tube 11 stable when receiving signal light, as Figure 7 shown, step S202 of method 20 specifically includes:

[0096] In step S1: Detect ambient light, which can be based on the detection result of the silicon photomultiplier tube.

[0097] In step S2: Determine whether the intensity of the ambient light is greater than a first threshold. Wherein:

[0098] When the intensity of the ambient light is greater than the first threshold, it is determined as strong ambient light, and steps S31 - S33 are entered: It is recognized that strong ambient light is detected, and the bias voltage across the silicon photomultiplier tube is reduced, thereby reducing the photon detection efficiency of the silicon photomultiplier tube.

[0099] When the intensity of the ambient light is less than or equal to the first threshold, step S4 is entered: Determine whether the intensity of the ambient light is less than a second threshold. Wherein:

[0100] When the intensity of the ambient light is less than the second threshold, it is determined as weak ambient light, and steps S51 - S53 are entered: It is recognized that weak ambient light is detected, and the bias voltage across the silicon photomultiplier tube is increased, thereby increasing the photon detection efficiency of the silicon photomultiplier tube.

[0101] A preferred embodiment of the present invention provides an optical receiving device with a dynamic adjustment circuit, and a method for dynamically adjusting the optical receiving device. The dynamic adjustment circuit can adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of the ambient light, so as to reduce the photon detection efficiency and the number of pixel units with continuous avalanche under strong ambient light conditions; under weak ambient light conditions, increase the photon detection efficiency to improve the ranging ability of the lidar.

[0102] Finally, it should be noted that: The above are only preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An optical receiving device for lidar, comprising: A photoelectric sensor including a plurality of pixel units, each pixel unit including a single-photon avalanche diode, and the pixel units being configured to detect the avalanche of single photons and convert them into output electrical signals; A voltage source configured to provide a bias voltage to the photoelectric sensor; And An adjustment unit coupled between the voltage source and the photoelectric sensor and configured to adjust the bias voltage of the photoelectric sensor according to the intensity of ambient light, thereby adjusting the photon detection efficiency of the photoelectric sensor. When the intensity of the ambient light is not greater than a second threshold, the photon detection efficiency of the photoelectric sensor is increased, wherein the photon detection efficiency is characterized by the ratio of the number of photons detected by the photoelectric sensor to the number of photons incident on the photoelectric sensor.

2. The optical receiving device according to claim 1, wherein the adjustment unit includes: A first resistor unit connected in series between the voltage source and the photoelectric sensor and configured to adjust the voltage of the photoelectric sensor according to the intensity of ambient light; A first capacitor unit connected in parallel with the photoelectric sensor and configured to keep the bias voltage on the photoelectric sensor stable when receiving signal light.

3. The optical receiving device according to claim 1, wherein the adjustment unit includes: A current detection unit coupled to the voltage source and configured to detect the current passing through the photoelectric sensor; A control unit coupled to the current detection unit and configured to output a control signal according to the current; A voltage adjustment unit coupled between the control unit and the photoelectric sensor and configured to dynamically adjust the bias voltage on the photoelectric sensor according to the control signal.

4. The optical receiving device according to claim 3, wherein the current detection unit includes: A second resistor unit configured such that one end thereof is coupled to the voltage source and the other end is coupled to the input end of the voltage adjustment unit; An operational amplifier configured to be coupled to both ends of the second resistor unit.

5. The optical receiving device according to claim 4, further including a first capacitor unit connected in parallel with the photoelectric sensor and configured to keep the bias voltage on the photoelectric sensor stable when receiving signal light.

6. The optical receiving device according to any one of claims 1-5, wherein the adjustment unit is configured to: When the intensity of the ambient light is not less than a first threshold, reduce the photon detection efficiency of the photoelectric sensor.

7. The optical receiving device according to any one of claims 3 to 5, wherein the voltage regulating unit comprises: Any one of a metal-oxide-semiconductor field-effect transistor with adjustable resistance value, a bipolar junction transistor, and a low-dropout linear regulator.

8. A method for dynamically adjusting the optical receiving device according to any one of claims 1-7, comprising: Detecting the avalanche of single photons by the pixel units including single-photon avalanche diodes in the photoelectric sensor and converting them into output electrical signals; According to the intensity of the ambient light, the bias voltage of the photoelectric sensor is adjusted by the adjustment unit, so as to adjust the photon detection efficiency of the photoelectric sensor. When the intensity of the ambient light is not greater than a second threshold, the photon detection efficiency of the photoelectric sensor is increased, so that the number of pixel units where avalanche occurs increases, wherein the photon detection efficiency is characterized by the ratio of the number of photons detected by the photoelectric sensor to the number of photons incident on the photoelectric sensor.

9. The method according to claim 8, wherein the optical receiving device further comprises: A first resistance unit, connected in series between the voltage source and the photoelectric sensor, and a first capacitance unit, connected in parallel with the photoelectric sensor. The method further includes: Adjusting the voltage on the photoelectric sensor according to the strength of the ambient light through the first resistance unit; Making the bias voltage on the photoelectric sensor stable when receiving signal light through the first capacitance unit.

10. The method according to claim 8, wherein the optical receiving device further comprises: A current detection unit, coupled to the voltage source; A control unit, coupled to the current detection unit; A voltage adjustment unit, coupled between the control unit and the photoelectric sensor. The method further includes: Detecting the current passing through the photoelectric sensor through the current detection unit; Outputting a control signal according to the current through the control unit; Dynamically adjusting the bias voltage on the photoelectric sensor according to the control signal through the voltage adjustment unit.

11. The method according to any one of claims 8-10, wherein the optical receiving device further comprises: A first capacitance unit, connected in parallel with the photoelectric sensor, configured to make the bias voltage on the photoelectric sensor stable when receiving signal light. The method further includes: When the intensity of the ambient light is not less than a first threshold, reducing the photon detection efficiency of the silicon photomultiplier.

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