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

Abstract

The present invention provides a light receiving device for laser radar and a method for dynamically adjusting the light receiving device, comprising: a silicon photomultiplier tube, configured to receive photons and convert them into output electrical signals; a voltage source, configured to provide a bias voltage to the silicon photomultiplier tube; and an adjustment unit, respectively coupled to the voltage source and the silicon photomultiplier tube, configured to adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of ambient light. The light receiving device provided by the present invention comprises a dynamic adjustment circuit, which can adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of ambient light, thereby reducing the photon detection efficiency under strong ambient light conditions; and improving the photon detection efficiency under weak ambient light conditions, thereby improving the distance measurement capability of the laser radar.

Description

Technical Field

[0001] The present invention relates to the field of laser detection, and in particular to a light receiving device for laser radar and a method for dynamically adjusting the light receiving device. Background Art

[0002] LiDAR is currently widely used in the field of unmanned driving. Silicon photomultiplier (SiPM) is used as the photoelectric sensor at the receiving end. Compared with avalanche diode (APD), its manufacturing process is compatible with CMOS process, and its reading circuit is simpler and easy to integrate. It is an ideal sensor for the receiving end of LiDAR.

[0003] Silicon photomultiplier (SiPM) is an array composed of multiple pixel units, which are composed of single photon avalanche diodes (SPADs) working in Geiger mode and quenching resistors in series, where each single photon avalanche photodiode (SPAD) is connected in series with a quenching resistor. When a photon is received by a 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 collision ionization, which eventually triggers a self-perpetuating ionization cascade, making the silicon conductive and generating current.

[0004] After the single-photon avalanche diode generates current, the quenching resistor connected in series with the single-photon avalanche diode will obtain a higher voltage divider, which will reduce the voltage across the single-photon avalanche photodiode to below the breakdown voltage, thereby preventing the avalanche. The single-photon avalanche diode will then be recharged and restored to its state before the breakdown, and photon detection can then be performed again.

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

[0006] The recovery time will cause most of the pixel units in the silicon photomultiplier tube to remain in an avalanche state and the charging recovery process when the ambient light signal is strong, and cannot work normally, which will seriously affect the normal use of the laser radar that uses it as the receiving end.

[0007] In the disclosed technology, the above defects are overcome by some special processing, for example, by adding an aperture to reduce the receiving field of view. However, the use of the aperture will inhibit the ability of the laser radar to measure close-range targets in the paraxial optical path, and will make optical installation and alignment more difficult in production; the small hole used as the aperture will inhibit the laser radar from receiving ambient light and also inhibit the laser radar from receiving echo signals, thereby reducing the laser radar's distance measurement ability under weak ambient light conditions.

[0008] The contents of the background technology section are merely the technologies known to the public and do not necessarily represent the existing technologies in the field. Summary of the invention

[0009] In order to solve the problem of continuous avalanche of multiple pixel units of silicon photomultiplier tubes under strong ambient light conditions, and to improve the distance measurement capability of laser radar under weak ambient light conditions, the present invention provides a light receiving device for laser radar, comprising:

[0010] a silicon photomultiplier tube configured to receive photons and convert them into output electrical signals;

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

[0012] The adjustment unit is coupled to the voltage source and the silicon photomultiplier tube respectively, and is 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 the 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 comprises:

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

[0016] The first capacitor unit is connected in parallel with the silicon photomultiplier tube and is 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 comprises:

[0018] a current detection unit, coupled to the voltage source and configured to detect a 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] The voltage regulating unit is coupled between the control unit and the silicon photomultiplier tube and is 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 comprises:

[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 regulating unit;

[0023] The operational amplifier is configured to have two ends coupled to the second resistance unit.

[0024] According to one aspect of the present invention, the optical receiving device further comprises 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.

[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, reducing the photon detection efficiency of the silicon photomultiplier tube;

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

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

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

[0031] According to one aspect of the present invention, the voltage regulating unit comprises: 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, comprising:

[0033] The silicon photomultiplier tube receives photons and converts them into output electrical signals;

[0034] The photon detection efficiency of the silicon photomultiplier tube is adjusted by the adjustment unit according to the intensity of the ambient light.

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

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

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

[0038] By means of the first resistor unit, the voltage on the silicon photomultiplier tube is adjusted according to the intensity of the ambient light;

[0039] The bias voltage on the silicon photomultiplier tube is kept stable by the first capacitor unit when receiving signal light.

[0040] According to one aspect of the present invention, the light receiving device further comprises: a current detection unit coupled to the voltage source; a control unit coupled to the current detection unit; and a voltage regulating unit coupled between the control unit and the silicon photomultiplier tube, wherein the method further comprises:

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

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

[0043] The bias voltage on the silicon photomultiplier tube is dynamically adjusted according to the control signal by 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 and configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light, and the method further includes:

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

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

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

[0048] A preferred embodiment of the present invention provides a light receiving device with a dynamic adjustment circuit, and a method for dynamically adjusting the light 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, thereby reducing the photon detection efficiency and reducing the number of pixel units with continuous avalanche under strong ambient light conditions; and improving the photon detection efficiency under weak ambient light conditions, thereby improving the ranging capability of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings are used to provide a further understanding of the present invention and constitute 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 of the present invention. In the accompanying drawings:

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

[0051] Figure 2 Schematically shows a light receiving device according to a preferred embodiment of the present invention;

[0052] Figure 3 Schematically shows a light receiving device according to a preferred embodiment of the present invention;

[0053] Figure 4 Schematically shows a light receiving device according to a preferred embodiment of the present invention;

[0054] Figure 5 Schematically shows a light receiving device according to a preferred embodiment of the present invention;

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

[0056] Figure 7 A flow chart of a method for dynamically adjusting an optical receiving device based on dual thresholds according to a preferred embodiment of the present invention is shown. DETAILED DESCRIPTION

[0057] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0058] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are 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, and therefore cannot be understood as limiting 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 indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0059] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, 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 limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0061] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of 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 are described below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

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

[0064] The working process of the silicon photomultiplier tube 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 the single photon avalanche diode 111 in the pixel unit to avalanche, and the junction capacitance ( Figure 1 The accumulated charge (not shown) flows from the anode to the cathode, the bias voltage across the single-photon avalanche diode 111 drops, the avalanche stops, and the voltage change ΔV across the single-photon avalanche diode 111 is output through the fast output capacitor 113. Then, the junction capacitance of the single-photon avalanche diode 112 is charged through the quenching resistor 112 to restore it to the Geiger mode. Only when the single-photon avalanche diode 111 returns to the Geiger mode can it continue to respond to the next photon, and 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 cause avalanche. In this way, multiple fast output capacitors 113 connected to multiple avalanche photodiodes 111 will output the voltage change of each single-photon avalanche diode 111. The voltage changes output by multiple single-photon avalanche diodes 111 are accumulated and a total voltage change ΔV is output. The more single-photon avalanche diodes 111 that avalanche, the greater the total voltage change ΔV accumulated and outputted. The more single-photon avalanche diodes 111 that avalanche, the greater the amount of charge charged to the junction capacitance in the single-photon avalanche diode 111 through the quenching resistor, that is, the greater the charging current generated.

[0066] Since silicon photomultiplier tubes can detect single photons, when the ambient light is continuously strong, most of the pixel units in the silicon photomultiplier tubes detect the ambient light signal and continue to be in the process of avalanche and charging recovery. Such characteristics make the silicon photomultiplier tube unable to perform subsequent detection. The present invention provides a silicon photomultiplier tube with a dynamic adjustment circuit, and the dynamic adjustment circuit can adjust the photon detection efficiency of the silicon photomultiplier tube according to the intensity of the ambient light, thereby reducing the photon detection efficiency and reducing the number of pixel units that continue to avalanche under strong ambient light conditions; and improving the photon detection efficiency under weak ambient light conditions, so as to improve the distance measurement capability of the laser radar.

[0067] According to a preferred embodiment of the present invention, Figure 2 As shown, the present invention provides a light receiving device 10 for a laser radar, comprising: a silicon photomultiplier tube 11, a voltage source 12 and an adjustment unit 13. The silicon photomultiplier tube 11 is configured to receive photons and convert them into an output electrical signal (total voltage change ΔV), which 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 tube 11, and the photon detection efficiency of the silicon photomultiplier tube 11 can be adjusted by adjusting the bias voltage. The adjustment unit 13 is coupled to the voltage source 12 and the silicon photomultiplier tube 11, respectively, and is configured to adjust the photon detection efficiency of the silicon photomultiplier tube 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 at both ends of the silicon photomultiplier tube 11. When the bias voltage at both ends of the silicon photomultiplier tube 11 is larger, the photon detection efficiency is higher; when the bias voltage at both ends of 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 at both ends of 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 according to the detection result of the silicon photomultiplier tube 11. The change in the intensity of the ambient light changes the number of pixel units in the silicon photomultiplier tube 11 that undergo avalanches, resulting in a corresponding change in the current generated by the silicon photomultiplier tube 11. Therefore, 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.

[0069] According to a preferred embodiment of the present invention, Figure 3 As 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 reduces the bias voltage of the silicon photomultiplier tube 11, and when the ambient light decreases, the first resistor unit 131 increases the bias voltage of the silicon photomultiplier tube 11. 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.

[0070] Specifically, the 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 incident photons there are, the more pixel units that avalanche occurs, the greater the current passing through the silicon photomultiplier tube 11, and the more current passing through the first resistor unit 131, so that the voltage across the first resistor unit 131 rises, the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 decreases, the photon detection efficiency decreases, and the number of pixel units that avalanche occurs decreases. Under weak ambient light conditions, the fewer incident photons there are, the fewer pixel units that avalanche occurs, the smaller the current passing through the silicon photomultiplier tube 11, and the current passing through the first resistor unit 131 decreases, so that the voltage across the first resistor unit 131 decreases, the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 increases, the photon detection efficiency increases, and the number of pixel units that avalanche occurs increases.

[0071] The first capacitor unit 132 can ensure that the bias voltage at both ends of the device does not change much when the silicon photomultiplier tube 11 receives a laser pulse in a short time. When the silicon photomultiplier tube 11 detects signal light, since the duration of the signal light is very short (for example, the pulse width is 3ns), the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 will drop quickly, causing the first capacitor unit 132 to release relatively little charge. Since the amount of charge stored in the first capacitor unit 132 is much larger than the amount of charge released, the total amount of charge of the first capacitor unit 132 remains basically unchanged, so the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 is basically stable; and when the silicon photomultiplier tube 11 detects continuous ambient light, since the duration of the ambient light is very long, the first capacitor unit 132 continues to release charge, so that the voltage across the first capacitor unit 132 continues to drop, causing the bias voltage across the silicon photomultiplier tube 11 to continue to 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 presence of incident signal light, stabilize the bias voltage of the silicon photomultiplier tube 11 to ensure 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 can be other devices that realize the functions of the first resistor unit and the first capacitor unit.

[0073] According to a preferred embodiment of the present invention, Figure 4 As shown, the adjustment unit 13 of the optical 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 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 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 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 may be a metal-oxide semiconductor field effect transistor (MOSFET) with adjustable resistance value, a bipolar junction transistor (BJT), or a voltage control 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 from the current detection unit 137, thereby dynamically adjusting the bias voltage between the anode and the cathode of the silicon photomultiplier tube 11. Under strong ambient light conditions, the more incident photons there are, the more pixel units that avalanche occurs, 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 the cathode of the silicon photomultiplier tube 11 to reduce the bias voltage, reduce the photon detection efficiency, and reduce the number of pixel units that avalanche occurs. Under weak ambient light conditions, the fewer the number of incident photons, the fewer the number of pixel units that undergo avalanche, the current of the silicon photomultiplier tube 11 decreases, and the voltage adjustment unit 135 adjusts the bias voltage between the anode and cathode of the silicon photomultiplier tube 11 to increase the bias voltage, increase the photon detection efficiency, and increase the number of pixel units that undergo avalanche.

[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 adjustment 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 adjustment 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, such as 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, wherein the first threshold is the light intensity value of 2 positive standard deviations from the average value of the ambient light intensity; and the second threshold is the light intensity value of 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 adjustment unit 135 also plays a role in stabilizing the bias voltage. It is easy for a person 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 value / the second threshold value, or the current current flowing through the silicon photomultiplier tube 11 and the first current threshold value / the second current threshold value, wherein the intensity of the ambient light corresponds to the current current, the first threshold value corresponds to the first current threshold value, and the second threshold value corresponds to the second current threshold value. After the detection circuit design is completed, the first current threshold value corresponding to the first threshold value when the ambient light is the first threshold value, and the second current threshold value corresponding to the second threshold value when the ambient light is the second threshold value can be determined through simulation or experiment, so as to be used for the control logic of the control unit 134.

[0076] Preferably, the voltage regulating unit 135 may be implemented by a transient enhanced LDO circuit, and is used to control the voltage output to the silicon photomultiplier tube.

[0077] According to a preferred embodiment of the present invention, Figure 4 As shown, the current detection unit 137 includes a second resistance unit 136, which is configured to have one end coupled to the voltage source 12 and the other end coupled to the input end of the voltage adjustment unit 135; an operational amplifier 133, which is configured to have both ends coupled to the second resistance unit 136.

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

[0079] The current detection unit 137 is coupled to the voltage source 12 and 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 to have one end coupled to the voltage source 12 and the other end coupled to the input end of the voltage adjustment unit 135; and an operational amplifier 133, configured to have both ends coupled to the second resistor unit 136. The control unit 134 is coupled to the current detection unit 137 and configured to output a control signal according to the current. The voltage adjustment unit 135 is coupled between the control unit 134 and the silicon photomultiplier tube 11 and 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 configured to keep the bias voltage on the silicon photomultiplier tube 11 stable when receiving signal light.

[0080] Figure 5The embodiment can realize the switching between active regulation mode and passive regulation mode. In the active mode, the switch 138 is disconnected, and the second resistance unit 136 and the voltage regulation unit 135 are connected in series between the silicon photomultiplier tube 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 adjustable resistance value. The current detection unit 137 detects the current passing through the silicon photomultiplier tube 11, and the control unit 134 dynamically adjusts the voltage regulation unit 135 based on the current detected from the current detection unit 137, thereby dynamically adjusting the bias voltage between the anode and the cathode of the silicon photomultiplier tube 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 regulating unit 135 remains unchanged (for example, in a constant resistance state), the switch 138 is closed, and the second resistance unit 136 is connected in series between the voltage source 12 and the silicon photomultiplier tube 11, and the bias voltage of the silicon photomultiplier tube 11 is adjusted according to the intensity of the ambient light. 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. It is easy for those skilled in the art to understand that the second resistance unit and the first capacitor unit can be a second resistor and a first capacitor, or other devices that realize the functions of a second resistor and a first capacitor. The ambient light can be received by the silicon photomultiplier tube and converted into an output electrical signal, and the output electrical signal can represent the intensity of the ambient light.

[0081] This dual-mode circuit can choose between active mode and passive mode. The active mode has a larger dynamic adjustment range, faster response speed, higher adjustment accuracy, and can achieve temperature compensation. It is suitable for application scenarios such as detecting a larger ambient light range, higher precision adjustment, and a larger operating temperature range. The passive mode is relatively power-saving, suitable for application scenarios that do not require control, and is easier to use.

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

[0083] In step S201 , photons are received by the silicon photomultiplier tube 11 and converted into output electrical signals. The output electrical signals may be output voltages, which are used as detection signals to calculate the distance and / or reflectivity of the target object.

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

[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 at both ends of the silicon photomultiplier tube 11. When the bias voltage at both ends of the silicon photomultiplier tube 11 is larger, the photon detection efficiency is higher; when the bias voltage at both ends of 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. The change in the intensity of the ambient light changes the number of pixel units in the silicon photomultiplier tube 11 that undergo avalanches, causing the current generated by the silicon photomultiplier tube 11 to change accordingly, thereby dynamically adjusting the bias voltage on the silicon photomultiplier tube 11 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, a first capacitor unit 132 connected in parallel with the silicon photomultiplier tube 11, and the method 20 further includes:

[0088] The voltage on the silicon photomultiplier tube 11 is adjusted according to the intensity of the ambient light through the first resistor unit 131 .

[0089] The first capacitor unit 132 is used to keep the bias voltage on the silicon photomultiplier tube 11 stable when receiving 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; when signal light is incident, the bias voltage of the silicon photomultiplier tube 11 is stabilized to ensure 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; and a voltage regulating unit 135 coupled between the control unit 134 and the silicon photomultiplier tube 11. The method 20 further includes:

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

[0093] Outputting a control signal according to the detected current through the control unit 134;

[0094] The bias voltage on the silicon photomultiplier tube 11 is dynamically adjusted according to the control signal through the voltage adjustment unit 135 .

[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, configured to keep the bias voltage on the silicon photomultiplier tube 11 stable when receiving signal light, such as Figure 7 As shown, step S202 of method 20 specifically includes:

[0096] In step S1: detecting ambient light, the detection result may be obtained through a silicon photomultiplier tube.

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

[0098] When the intensity of the ambient light is greater than the first threshold, it is judged as strong ambient light, and the process proceeds to steps S31-S33: determining that strong ambient light is detected, reducing the bias voltage across the silicon photomultiplier tube, 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, the process proceeds to step S4: determining whether the intensity of the ambient light is less than the second threshold.

[0100] When the intensity of the ambient light is less than the second threshold, it is determined to be weak ambient light, and the process proceeds to steps S51-S53: determining that weak ambient light is detected, increasing the bias voltage at both ends of the silicon photomultiplier tube, thereby improving the photon detection efficiency of the silicon photomultiplier tube.

[0101] A preferred embodiment of the present invention provides a light receiving device with a dynamic adjustment circuit, and a method for dynamically adjusting the light 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, thereby reducing the photon detection efficiency under strong ambient light conditions and reducing the number of pixel units with continuous avalanche; and improving the photon detection efficiency under weak ambient light conditions to enhance the ranging capability of the laser radar.

[0102] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A light receiving device for laser radar, comprising: A silicon photomultiplier tube, comprising a plurality of pixel units, wherein the pixel units include single-photon avalanche diodes, and each pixel unit is configured to detect a single photon to generate avalanche and convert it into an output electrical signal; a voltage source configured to provide a bias voltage to the silicon photomultiplier tube; and An adjustment unit is coupled between the voltage source and the silicon photomultiplier tube, and is configured to adjust 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. When the intensity of the ambient light is not less than a first threshold, the photon detection efficiency of the silicon photomultiplier tube is reduced to reduce the number of pixel units that undergo avalanche, wherein the photon detection efficiency is characterized by the ratio of the number of photons detected by the silicon photomultiplier tube to the number of photons incident on the silicon photomultiplier tube.

2. The optical receiving device according to claim 1, wherein the adjusting unit comprises: A first resistor unit is connected in series between the voltage source and the silicon photomultiplier tube, and adjusts the voltage of the silicon photomultiplier tube according to the intensity of ambient light; The first capacitor unit is connected in parallel with the silicon photomultiplier tube and is configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light.

3. The optical receiving device according to claim 1, wherein the adjusting unit comprises: a current detection unit, coupled to the voltage source and configured to detect a current passing through the silicon photomultiplier tube; a control unit, coupled to the current detection unit and configured to output a control signal according to the current; The voltage regulating unit is coupled between the control unit and the silicon photomultiplier tube and is configured to dynamically adjust the bias voltage on the silicon photomultiplier tube according to the control signal.

4. The light receiving device according to claim 3, wherein the current detection unit comprises: 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 regulating unit; The operational amplifier is configured to have two ends coupled to the second resistance unit. 5 . The optical receiving device according to claim 4 , further comprising a first capacitor unit connected in parallel with the silicon photomultiplier tube and configured to keep a bias voltage on the silicon photomultiplier tube stable when receiving signal light. 6 . The light receiving device according to claim 1 , wherein the silicon photomultiplier tube is configured to receive ambient light and convert it into an output electrical signal.

7. The optical receiving device according to any one of claims 1 to 5, wherein the adjustment unit is configured as: When the intensity of the ambient light is not greater than a second threshold, the photon detection efficiency of the silicon photomultiplier tube is increased. 8 . The light receiving device of claim 7 , wherein the first threshold value and the second threshold value are configured to be determined according to a standard normal distribution of ambient light intensity.

9. The optical receiving device according to any one of claims 3 to 5, wherein the voltage adjustment unit comprises: Any of a metal-oxide semiconductor field effect transistor and a bipolar junction transistor whose resistance value can be adjusted.

10. The optical receiving device according to any one of claims 3 to 5, wherein the voltage adjustment unit comprises: A low-dropout linear regulator is used to control the voltage output to the silicon photomultiplier tube.

11. A method for dynamically adjusting the optical receiving device according to any one of claims 1 to 10, comprising: Detecting a single photon avalanche through a pixel unit including a single photon avalanche diode in the silicon photomultiplier tube and converting it into an output electrical signal; According to the intensity of the ambient light, the bias voltage of the silicon photomultiplier tube is adjusted by the adjustment unit, thereby adjusting the photon detection efficiency of the silicon photomultiplier tube. When the intensity of the ambient light is not less than the first threshold, the photon detection efficiency of the silicon photomultiplier tube is reduced to reduce the number of pixel units that undergo avalanche. The photon detection efficiency is characterized by the ratio of the number of photons detected by the silicon photomultiplier tube to the number of photons incident on the silicon photomultiplier tube.

12. The method according to claim 11, wherein the light receiving device further comprises: A first resistance unit is connected in series between the voltage source and the silicon photomultiplier tube, and a first capacitance unit is connected in parallel with the silicon photomultiplier tube. The method further includes: By means of the first resistor unit, the voltage on the silicon photomultiplier tube is adjusted according to the intensity of the ambient light; The bias voltage on the silicon photomultiplier tube is kept stable by the first capacitor unit when receiving signal light.

13. The method according to claim 11, wherein the light receiving device further comprises: a current detection unit, coupled to the voltage source; a control unit, coupled to the current detection unit; A voltage regulating unit is coupled between the control unit and the silicon photomultiplier tube, wherein the method further comprises: Detecting the current passing through the silicon photomultiplier tube by the current detection unit; Outputting a control signal according to the current through the control unit; The bias voltage on the silicon photomultiplier tube is dynamically adjusted according to the control signal by the voltage adjustment unit.

14. The method according to any one of claims 11 to 13, wherein the light receiving device further comprises: A first capacitor unit is connected in parallel with the silicon photomultiplier tube and is configured to keep the bias voltage on the silicon photomultiplier tube stable when receiving signal light. The method further includes: When the intensity of the ambient light is not greater than a second threshold, the photon detection efficiency of the silicon photomultiplier tube is increased.

15. The method of claim 14, wherein the first threshold and the second threshold are determined according to a standard normal distribution of ambient light intensity.

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