Optical ranging method and device

Abstract

The invention provides an optical ranging method and device. The method is applied to the optical distance measuring device, and the device comprises a module shell which is provided with a first opening; the light source and the photosensitive chip are located in the module shell; a first photosensitive area is arranged on the photosensitive chip; the method comprises the following steps: obtaining photon flight time detection data of a first photosensitive area; acquiring a first data parameter about the first reflected light and a superposition data parameter of the first reflected light and the second reflected light in the photon flight time detection data of the first photosensitive area; wherein the first reflected light is emitted by the light source and is reflected to the first photosensitive area by the inner wall of the module shell, and the second reflected light is emitted by the light source to the surface of a to-be-detected target outside the module shell, is reflected by the surface of the to-be-detected target, enters the module shell again through the first opening and is received by the first photosensitive area; and determining the distance of the to-be-measured target according to the first data parameter and the superposed data parameter.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of optical ranging, and in particular to an optical ranging method and device. BACKGROUND

[0002] A dToF (direct Time-of-Flight) system is usually used for high-precision distance measurement, which uses a SPAD (Single Photon Avalanche Diode) as a photoelectric sensor to receive a light signal and convert it into an electrical signal.

[0003] The dToF module emits photons to a target through a VCSEL (Vertical Cavity Surface Emitting Laser) at the emission end, and detects the photons reflected by the target through a SPAD at the receiving end. By counting the time difference between the photons detected at the receiving end and the photons emitted at the emission end, the distance of the target being measured can be determined. However, due to the limitations of the "optical dead zone distance" of the dToF module itself, targets within the optical dead zone distance cannot be measured or cannot be accurately measured, so the actual distance measurement application of the above dToF module still has certain limitations. SUMMARY

[0004] Therefore, the present disclosure provides an optical ranging method and device.

[0005] In one aspect, the present disclosure provides an optical ranging method applied to an optical ranging device, the optical ranging device comprising: a module housing having a first opening; a light source and a photosensitive chip located in the module housing; wherein the first opening is opposite to a light emitting surface of the light source; and a first photosensitive area is arranged on the photosensitive chip. The method comprises: obtaining photon time-of-flight detection data of the first photosensitive area; obtaining first data parameters of a first reflected light ray and superposition data parameters of the first reflected light ray and a second reflected light ray in the photon time-of-flight detection data of the first photosensitive area; wherein the first reflected light ray is a light ray emitted by the light source and reflected by an inner wall of the module housing to the first photosensitive area, the second reflected light ray is a light ray emitted by the light source to a target surface outside the module housing, reflected by the target surface, re-entering the module housing through the first opening, and received by the first photosensitive area; determining the distance of the target to be measured according to the first data parameters and the superposition data parameters.

[0006] In some embodiments, the photon flight time detection data of the first light sensing region comprises a first statistical histogram and a second statistical histogram, the horizontal coordinate of the first statistical histogram and the second statistical histogram is photon flight time, and the vertical coordinate is photon number; The first data parameter comprises a first centroid corresponding to the first reflected light in the first statistical histogram and a first centroid intensity; The superposition data parameter comprises a superposition centroid corresponding to the first reflected light and the second reflected light in the second statistical histogram and a superposition centroid intensity.

[0007] In some embodiments, the determining the distance of the target object according to the first data parameter and the superposition data parameter comprises: taking the first centroid intensity as the weight of the first centroid and taking the superposition centroid intensity as the weight of the superposition centroid; determining the distance of the target object according to the first centroid and the weight thereof, the superposition centroid and the weight thereof, and a weighted centroid algorithm of the histogram.

[0008] In some embodiments, the photon flight time detection data of the first light sensing region is acquired in time division to form the first statistical histogram and the second statistical histogram respectively; The photon flight time detection data corresponding to the first statistical histogram is acquired without setting the target object.

[0009] In some embodiments, the module shell further comprises a second opening, the light sensing chip further comprises a second light sensing region, and the second light sensing region is opposite to the second opening; the method further comprises: acquiring photon flight time detection data of the second light sensing region related to the target object; acquiring third data parameter of the photon flight time detection data of the second light sensing region about a third reflected light, the third reflected light being a light ray emitted from the light source to the target object outside the module shell, reflected by the surface of the target object, entering the module shell through the second opening and received by the second light sensing region; determining the distance of the target object according to the third data parameter.

[0010] In some embodiments, the photon flight time detection data of the second light sensing region comprises a third statistical histogram, and the method further comprises: determining a first distance of the target object at a first time according to the second statistical histogram; and / or determining a second distance of the target object at a second time according to the third statistical histogram; Wherein, the first distance is less than the optical dead zone distance of the optical ranging device, and the second distance is greater than or equal to the optical dead zone distance of the optical ranging device.

[0011] In some embodiments, the method further includes: Obtain the time difference between the first moment and the second moment; If the time difference between the first moment and the second moment is less than a time threshold, the dynamic distance of the target to be measured is determined based on the first distance and the second distance; wherein the dynamic distance is the instantaneous distance of the target to be measured output by the optical ranging device.

[0012] In some embodiments, determining the dynamic distance of the target under test based on the first distance and the second distance includes: Obtain a first weight related to the first distance and a second weight related to the second distance; wherein the first weight and the second weight are related to the optical dead zone distance of the optical ranging device; The dynamic distance is determined based on the first distance, the first weight, the second distance, and the second weight.

[0013] In some embodiments, the method further includes: Obtain a preset function, wherein the independent variables of the preset function include the first distance and the optical dead zone distance, and the value range of the preset function is 0 to 1; The preset function is used to smooth the value change curves of the first weight and / or the second weight during the process of determining the dynamic distance of the target to be measured.

[0014] On the other hand, embodiments of this disclosure also provide an optical ranging device, including: A module housing having a first opening; The light source and photosensitive chip are located inside the module housing; The first opening is opposite to the light-emitting surface of the light source; the photosensitive chip is provided with a first photosensitive area; The first photosensitive area is used to detect the first reflected light and the second reflected light emitted and reflected by the light source; wherein, the first reflected light is light emitted by the light source and reflected by the inner wall of the module housing to the first photosensitive area; the second reflected light is light emitted by the light source to the target surface outside the module housing, reflected by the target surface, re-entering the module housing through the first opening, and received by the first photosensitive area.

[0015] In some embodiments, the optical ranging device further includes a processor; The processor is configured to perform at least some of the steps in any of the methods described above.

[0016] In the technical solution provided in this embodiment, the optical ranging device is provided with a first photosensitive area that can detect the first reflected light inside the module housing. The first photosensitive area detects a superimposed layer of the first reflected light and a second reflected light reflected back from the first opening by the target object. The distance to the target object is determined based on the detected superimposed data parameters and the first data parameters corresponding to the first reflected light. In this way, the distance to the target object within the optical dead zone distance can be detected, overcoming the limitation of dToF modules in being unable to accurately measure the distance to the target object within the optical dead zone distance. Attached Figure Description

[0017] Figure 1A A schematic diagram illustrating the principle of ranging using a dToF module provided in this embodiment of the disclosure; Figure 1B A schematic diagram illustrating the principle of ranging using a dToF module provided in this embodiment of the present disclosure. Figure Two ; Figure 2 This is a schematic diagram of the structure of an optical ranging device provided in an embodiment of the present disclosure; Figure 3 A flowchart of an optical ranging method provided in this embodiment of the disclosure; Figure 4A The first statistical histogram involved in the optical ranging method provided in the embodiments of this disclosure; Figure 4B The second statistical histogram involved in the optical ranging method provided in the embodiments of this disclosure. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without one or more of these details. In other instances, to avoid confusion with this disclosure, certain technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0021] dToF uses a SPAD to receive optical signals and convert them into electrical signals. It calculates the distance to the target by statistically analyzing the time it takes for a photon to travel from emission to reflection and reception. Its detection principle is as follows: Figure 1A As shown, photons emitted by the laser emitter 111 of the transmitter 110 of the dToF module 100 reach the surface of the target 10 through the light exit port 112, and after reflection, reach the light inlet 122 of the receiver 120 and enter the photosensitive area 121 (i.e., SPAD) of the receiver 120. The dToF chip 130 calculates the photon flight time by the time the photon is detected by the photosensitive area 121 and the time the light pulse is emitted by the laser emitter 111, thereby determining the distance to the target 10 and realizing distance measurement.

[0022] The laser emitter 111 of the transmitter 110 of the dToF module 100, i.e., the VCSEL, has a field of view (FOL), and the SPAD of the receiver 120 has a field of view (FOV). Since the FOL and FOV are not coaxial, no matter how the structure of the dToF module 100 is designed, the system will always have an "optical dead zone" or "optical blind zone".

[0023] like Figure 1B As shown, when the target 10 is very close to the dToF module 100, the non-overlapping FOL and FOV of the system prevent the receiver 120 from receiving the reflected light emitted by the transmitter 110 and passed through the target 10, thus making the target 10 undetectable by the dToF module 100. This is because within a distance range very close to the dToF module 100, the non-overlapping FOL and FOV of the target 10 prevents reflected photons from entering the light inlet 122 of the receiver 120, or because the receiver 120 can only receive light reflected multiple times from the surfaces of the target 10 and the dToF module 100, resulting in incorrect optical path lengths and inaccurate ranging. Therefore, this distance range is called the "optical dead zone distance".

[0024] To accurately detect the distance to a target within the optical dead zone, embodiments of this disclosure provide an optical ranging method applicable to, for example... Figure 2The optical ranging device 200 shown includes: a module housing 210 having a first opening 211; a light source 220 and a photosensitive chip 230 located inside the module housing 210; wherein the first opening 211 is opposite to the light-emitting surface of the light source 220; and a first photosensitive area 231 is provided on the photosensitive chip 230.

[0025] The aforementioned light source 220 can be a laser emitter, such as a VCSEL, or other visible or non-visible light emitting elements. The photosensitive chip 230 can be a dToF chip, on which a logic processing unit for processing detection data is provided, or the photosensitive chip 230 can be connected to an external logic processing unit for processing detection data via wired or wireless means.

[0026] The first photosensitive area 231 disposed on the photosensitive chip 230 can be a photon detection element containing a SPAD device, which can generate an electrical signal through photosensitive sensing and transmit it to the relevant circuit of the photosensitive chip 230 for signal processing.

[0027] Here, the photosensitive chip 230 and the light source 220 are disposed adjacent to each other on the same inner wall of the module housing 210. The first photosensitive area 231 can be located on the side of the photosensitive chip 230 closer to the light source 220. The first photosensitive area 231 is close to but not opposite to the first opening 211. For example, the first photosensitive area 231 can be located at a position opposite to the surface of the module housing 210. A portion of the light emitted from the light source 220 does not exit to the outside of the module housing 210 through the first opening 211, but is only reflected multiple times by the inner wall of the module housing 210 and the surface of the photosensitive chip 230 inside the module housing 210, and is finally received by the first photosensitive area 231 (this optical path can be called the "inner optical path", and this portion of light propagating along the "inner optical path" can be defined as the "first reflected ray"). Figure 2 (As shown by the solid arrow inside the middle module housing 210); another portion of the light emitted from the light source 220 passes through the first opening 211 and reaches the surface of the target 10 under test. When the target 10 under test is very close to the ranging device (the distance between the target 10 and the ranging device is less than the "optical dead zone distance" of the ranging device, such as...) Figure 2 The light from the target 10 (located in the dashed box) may be reflected by the surface of the target 10 and re-enter the module housing 210 through the first opening 211. It will then be reflected multiple times by the inner wall of the module housing 210 and the surface of the photosensitive chip 230, and finally received by the first photosensitive area 231 (this portion of light can be defined as "second reflected light"). Figure 2(As shown by the dashed arrow in the middle). Therefore, in this embodiment of the present disclosure, the first photosensitive area 231 is used to detect the two types of light (the first reflected light and the second reflected light) and collect detection data. By performing data analysis and calculation on the detection data, the distance of the target 10 to be measured, which is within the "optical dead zone distance" of the ranging device, can be determined.

[0028] like Figure 3 As shown, the method includes the following steps: Step S101: Acquire photon time-of-flight detection data of the first photosensitive area 231; The photon flight time detection data here can include the photon flight time of the photons received by the first photosensitive area 231 and the number of photons corresponding to the photon flight time. The photon flight time can be determined by recording the time of emission of the light pulse and the time of detection of the photon within that light pulse; the time difference between the two is the photon flight time. The number of photons corresponding to the photon flight time can be determined by counting the number of photons within a certain time interval (timebox) including the photon flight time.

[0029] If detection is performed without a target being set, the photon time-of-flight detection data obtained by the first photosensitive area 231 only includes the photon time-of-flight detection data of the first reflected ray. If detection is performed with a target 10 being set, and the target 10 is within the "optical dead zone distance" of the ranging device, the photon time-of-flight detection data packet obtained by the first photosensitive area 231 includes the photon time-of-flight data of the superposition of the first and second reflected rays.

[0030] Understandably, regardless of the circumstances under which the detection is performed, the data detected by the first photosensitive area 231 includes the photon flight time data of the first reflected light.

[0031] Step S102: Obtain the first data parameters of the first reflected ray and the superposition data parameters of the first reflected ray and the second reflected ray from the photon time-of-flight detection data of the first photosensitive area 231; The first reflected light is emitted from the light source 220 and reflected by the inner wall of the module housing 210 to the first photosensitive area, which is the light in the aforementioned inner optical path. The second reflected light is emitted from the light source 220 to the surface of the target 10 outside the module housing 210, reflected by the surface of the target 10, and re-enters the module housing 210 through the first opening 211 and is received by the first photosensitive area 231, which is the light that can be used to measure the distance to the target 10.

[0032] Since the photon time-of-flight detection data detected by the first photosensitive area 231 includes the first data parameters of the first reflected light ray from the internal optical path, and the first reflected light ray only propagates inside the optical ranging device, the first data parameters are only related to the optical structure of the optical ranging device itself, and are independent of the external environment of the optical ranging device 200 and the presence of a target. For example, the first data parameters are only affected by factors such as the relative position of the first photosensitive area 231 and the first opening 211, and the cavity height inside the module housing 210. Because the first data parameters are only related to the optical structure of the optical ranging device 200, the first data parameters determined by detecting the first reflected light ray through the first photosensitive area 231 are relatively stable when the optical structure of the optical ranging device 200 remains unchanged.

[0033] With the target 10 set up, the detected time-of-flight data is the superposition of the first reflected light and the second reflected light; therefore, it is referred to as the superimposed data parameter. The first data parameter can be obtained in advance through factory testing or obtained separately during each test.

[0034] Step S103: Determine the distance to the target to be measured based on the first data parameter and the superimposed data parameter.

[0035] Since the superimposed data parameters include the first data parameters, and the first data parameters can be measured independently, the data parameters corresponding to the second reflected ray can be calculated based on the first data parameters and the superimposed data parameters, thereby determining the distance to the target. For example, the reflection path lengths of the second reflected ray and the first reflected ray within the optical ranging device 200 can be considered approximately equal. Therefore, the difference between the light propagation path length of the second reflected ray and the light propagation path length of the first reflected ray can be approximated as the distance to the target. Thus, the distance to the target reflected by the difference between the superimposed data parameters and the first data parameters can be obtained.

[0036] In some embodiments, photon time-of-flight detection data can be represented in the form of a statistical histogram. The photon time-of-flight detection data of the first photosensitive area 231 includes, for example: Figure 4A The first statistical histogram shown, and as follows Figure 4B The second statistical histogram shown represents the photon flight time t on the horizontal axis and the number of photons n on the vertical axis. Specifically, the first statistical histogram reflects the data regarding the first reflected ray from the photon flight time detection data of the first photosensitive area 231, while the second statistical histogram reflects the superimposed data regarding the first and second reflected rays from the photon flight time detection data of the first photosensitive area 231.

[0037] In this embodiment of the disclosure, since photon flight events are independent random events, the distribution of photon flight time and photon quantity can be determined statistically, thereby analyzing and calculating the distance to the target 10. A statistical histogram can reflect the probability (or quantity) of different photon flight times: each rectangular bar in the histogram is a time box, the width of the time box represents a time interval, the height of the time box represents the number of photons falling within that time interval, and the position of the time box in the histogram represents the magnitude of the photon flight time falling within that time interval.

[0038] In some embodiments, time-of-flight detection data of the first photosensitive area 231 are acquired in a time-division manner to form a first statistical histogram and a second statistical histogram, respectively. The photon time-of-flight data corresponding to the first statistical histogram was acquired without a target being set. The photon time-of-flight data corresponding to the second statistical histogram was acquired when the target was within the optical dead zone of the optical ranging device.

[0039] Here, the first statistical histogram can be obtained by detecting the first reflected light from the inner optical path separately, for example, by calibration during the pre-shipment testing phase. The relevant data of this first statistical histogram can be stored in the storage space of the photosensitive chip 230 as an inherent parameter of the optical ranging device; it can also be obtained in real time during each test or each power-on initialization. For example, in the process of obtaining the first statistical histogram, the first opening 211 can be blocked, so that the first photosensitive area 231 can only receive light from the inner optical path, reducing the possibility of ambient light interference.

[0040] The aforementioned first data parameters include: the first centroid Ma and the first centroid intensity Pa corresponding to the first reflected ray in the first statistical histogram.

[0041] In this embodiment, the first centroid Ma can be understood as the data distribution center (or centroid) of the photon flight time data corresponding to the first reflected ray in the histogram. The first centroid intensity Pa can be understood as the probability (or quantity, i.e., the number of photon events) of the photon flight time corresponding to the distribution center (or centroid). It should be noted that the first centroid intensity Pa can also be the magnitude of the number of photon flight events (photon count) in the nearby timeboxes including the first centroid Ma.

[0042] The above-mentioned superimposed data parameters include: the superimposed centroid Mb and superimposed centroid intensity Pb ​​corresponding to the first and second reflected rays in the second statistical histogram.

[0043] Since the data detected by the first photosensitive area 231 includes both the first and second reflected rays when a target is set, the second statistical histogram reflects the result of the photon detection superposition of the first and second reflected rays. Therefore, the centroid of the second statistical histogram is called the superposition centroid, and its corresponding intensity is called the superposition centroid intensity.

[0044] exist Figure 4A In the first statistical histogram, the first centroid Ma basically conforms to a normal distribution. Therefore, the centroid of the statistical histogram basically coincides with the position of the statistical peak. That is, the first centroid Ma basically coincides with the position of the statistical peak. Accordingly, the intensity Pa of the first centroid Ma can be reflected by parameters such as the height (or intensity) of the statistical peak, the variance / standard deviation of the histogram, and the confidence interval near the statistical peak.

[0045] and Figure 4B In the second statistical histogram, there is not only the first statistical peak f1 formed by the inner optical path, but also the second statistical peak f2 formed under the influence of the second reflected light reflected by the target under test. This causes the position of the superimposed centroid Mb to deviate from any statistical peak, and the corresponding superimposed centroid intensity Pb ​​is also different from the intensity of any peak.

[0046] Therefore, in some embodiments, determining the distance to the target based on the first data parameter and the superimposed data parameter includes: The first centroid intensity Pa is used as the weight of the first centroid Ma, and the superimposed centroid intensity Pb ​​is used as the weight of the superimposed centroid Mb. The distance to the target is determined by a weighted centroid algorithm based on the first centroid Ma and its weight Pa, the superimposed centroid Mb and its weight Pb, and the histogram.

[0047] For example, a first difference can be obtained by subtracting the product of the superimposed centroid Mb and the superimposed centroid intensity Pb, and the product of the first centroid Ma and the first centroid intensity Pa. A second difference is obtained by subtracting the superimposed centroid intensity Pb ​​and the superimposed centroid intensity Pa. Then, the target centroid Mint is obtained based on the ratio of the first difference to the second difference, as shown in formula (1) below: (1) It should be noted that the formula for the weighted average algorithm of a histogram is usually: Weighted average = In this embodiment, the reason why equation (1) differs from the conventional weighted average formula is that the superimposed centroid intensity Pb ​​is essentially the superposition result of the photon detection data of the first reflected ray and the second reflected ray. It already includes the centroid intensity of the photon detection result of the first reflected ray in the inner optical path. Therefore, when solving for the target centroid Mint, the product of the first centroid Ma and its weight is no longer added to the product of the superimposed centroid Mb and its weight, but the product of the superimposed centroid Mb and its weight is subtracted from the product of the first centroid Ma and its weight.

[0048] In this way, by using the above testing and calculation process, the actual distance of the target 10 under test can be detected when it is within the optical dead zone distance, thereby breaking through the limitations of the dToF module and realizing a wider range of applications.

[0049] In some embodiments, such as Figure 2 As shown, the module housing 210 also includes a second opening 212, and the photosensitive chip 230 also includes a second photosensitive area 232, which is opposite to the second opening 212. In addition, a baffle 213 can be provided inside the module housing 210 to isolate the first photosensitive area 231 and the second photosensitive area 232, as well as to isolate the first opening 211 and the second opening 212, so that the light from the internal optical path will not be reflected to the second photosensitive area 232 inside the module housing 210.

[0050] The method also includes: Step S201: Obtain photon time-of-flight detection data related to the second photosensitive area 232 and the target 10 under test; Step S202: Obtain the third data parameter about the third reflected light from the photon time-of-flight detection data of the second photosensitive area 232. The third reflected light is the light emitted from the light source 220 to the target 10 outside the module housing 210, reflected by the surface of the target 10, enters the module housing 210 through the second opening 212, and is received by the second photosensitive area 232. Step S203: Determine the distance to the target 10 based on the third data parameter.

[0051] Here, the case where the distance to the target 10 is greater than or equal to the optical dead zone distance of the optical ranging device is provided (e.g.) Figure 2 The target 10, located within the solid-line frame, is used in the normal ranging process of the aforementioned optical ranging device. The second photosensitive area 232 is used to receive the light reflected back through the second opening 212, i.e., the third reflected light (also called the "external optical path light"), such as... Figure 2 (As shown by the long solid arrow reflecting off the target 10).

[0052] It should be noted that step S201 and the aforementioned step S101 are two independent methods for acquiring ranging data in the ranging method of this application. They can be applied to different ranging scenarios, and therefore can be implemented independently or in combination. When they are implemented independently, there is no order between them; when they are implemented in combination, they can be performed simultaneously.

[0053] Due to the high sensitivity of SPAD devices and the existence of quenching time, factors such as temperature and voltage have a particularly significant impact on ranging accuracy. To eliminate the influence of temperature and voltage on ranging accuracy, detection modules for the inner and outer optical paths can be set on the photosensitive chip 230. Since the effects of external factors such as temperature and voltage on the inner and outer optical paths are simultaneous and consistent, these common-mode interferences can be eliminated by subtracting the ranging results of the inner and outer optical paths (i.e., the ranging data corresponding to the first statistical histogram and the ranging data corresponding to the third statistical histogram).

[0054] In some embodiments, such as Figure 2 As shown, the inner optical path includes the optical path from which light emitted from the light source 220 is reflected in the module housing 210 and reaches the first photosensitive area 231. The outer optical path includes the optical path from which light emitted from the light source 220 passes through the first opening 211 to the target 10 under test, and then is reflected by the target 10 under test into the second opening 212 and reaches the second photosensitive area 232. Here, the second photosensitive area 232 can use the same photosensitive device as the first photosensitive area 231, such as a photosensitive device composed of one or more SPAD elements.

[0055] In this embodiment, subtracting the ranging results from the inner and outer optical paths can eliminate system transmission delay, thereby obtaining the system's ranging zero point. Furthermore, an opaque barrier 213 is used within the module to isolate the inner optical path photosensitive area (first photosensitive area 231) and the outer optical path photosensitive area (second photosensitive area 232) to prevent internal reflections from affecting the ranging of the outer optical path photosensitive area. Therefore, the first data parameter obtained by the first photosensitive area 231 from the inner optical path can also be used to correct or calibrate the third data parameter, resulting in a more accurate ranging result.

[0056] In some embodiments, the photon time-of-flight detection data of the second photosensitive area 232 includes a third statistical histogram, and the method further includes: Based on the second statistical histogram, the first distance of the target 10 at the first moment is determined; and / or Based on the third statistical histogram, the second distance of the target 10 at the second time point is determined; The first distance is less than the optical dead zone distance of the optical ranging device, and the second distance is greater than or equal to the optical dead zone distance of the optical ranging device.

[0057] In this embodiment, when the target is a static target: when the target is within the optical dead zone of the optical ranging device, a first distance of the target can be determined based on a second statistical histogram; when the target is outside the optical dead zone of the optical ranging device, a second distance of the target can be determined based on a third statistical histogram. When the target is a dynamic target: when the target is within the optical dead zone of the optical ranging device at a first moment, a first distance of the target can be determined based on a second statistical histogram; when the target is outside the optical dead zone of the optical ranging device at a second moment, a second distance of the target can be determined based on a third statistical histogram. If the target moves rapidly back and forth near the optical dead zone of the optical ranging device, the real-time distance of the target can be determined by combining the first distance and the second distance.

[0058] Considering the changing position of the target 10, different detection data can be switched during the detection process to determine the actual distance of the target 10 at different times. When the target 10 is within the optical dead zone, its first distance can be determined according to the second statistical histogram, which is implemented by calculating the first distance using the data detected by the first photosensitive area 231 in the above embodiment. When the target 10 moves beyond the optical dead zone distance, its second distance can be determined according to the third statistical histogram, which is implemented by referring to the process of steps S201 to S203 above.

[0059] In addition, a special case is considered: the target 10 moves back and forth rapidly near the critical position of the optical dead zone distance. Due to the influence of some signal transmission delay, the ranging result output by the optical ranging device may change abruptly, making it difficult to determine its accurate position.

[0060] Therefore, in some embodiments, the method may further include the following steps: Step S204: Obtain the time difference between the first moment and the second moment; Step S205: If the time difference between the first moment and the second moment is less than the time threshold, then determine the dynamic distance of the target 10 to be measured based on the first distance and the second distance; wherein the dynamic distance is the instantaneous distance of the target 10 to be measured output by the optical ranging device 200.

[0061] If the time difference between the first and second moments is large, it indicates that the target 10 may be in a slowly moving position or has undergone a position change. Conversely, if the time difference is less than a time threshold, it indicates that the target 10 may be in a rapidly moving state or located at the critical position of the optical dead zone. Therefore, the dynamic distance can be calculated based on the first and second distances measured at the first and second moments, respectively. This dynamic distance can be used to describe the position of the target 10 with a high probability, serving as the ranging result of the optical ranging device. In other words, the impact of position jumps can be reduced by calculating the above two sets of data, allowing for the most accurate measurement of the actual distance to the target 10.

[0062] In some embodiments, determining the dynamic distance of the target to be measured based on a first distance and a second distance includes: Obtain a first weight related to a first distance and a second weight related to a second distance; wherein the first weight and the second weight are related to the optical dead zone distance of the optical ranging device; The dynamic distance is determined based on the first distance, the first weight, the second distance, and the second weight.

[0063] Since the first distance and the second distance are detected by different photosensitive areas, there is a certain difference between them. Therefore, the dynamic distance can be determined by weighted averaging.

[0064] First, the weights of the first distance and the second distance need to be determined based on the optical dead zone distance, i.e., the first weight and the second weight mentioned above, and then a weighted average calculation is performed.

[0065] The aforementioned first and second weights can be determined based on the characteristics of the optical ranging device itself and the relative position of the target and the optical ranging device. For example, the first and second weights can be determined based on the absolute differences between the first distance, the second distance, and the optical dead zone distance of the optical ranging device. If the absolute difference between the measured first distance and the optical dead zone distance is less than the absolute difference between the second distance and the optical dead zone distance, it indicates that the first distance may be closer to the actual distance. In this case, the first weight of the first distance is larger, and the second weight of the second distance is smaller. Conversely, if the absolute difference between the measured first distance and the optical dead zone distance is greater than the absolute difference between the second distance and the optical dead zone distance, it indicates that the second distance may be closer to the actual distance. In this case, the first weight of the first distance is smaller, and the second weight of the second distance is larger. Therefore, the weights can be determined based on the optical dead zone distance and the measured first or second distance.

[0066] In some embodiments, the method further includes: Obtain the preset function. The independent variables of the preset function include the first distance and the optical dead zone distance. The value range of the preset function is 0 to 1. The preset function is used to smooth the value change curves of the first weight and / or the second weight during the process of determining the dynamic distance of the target to be measured.

[0067] Here, the preset function refers to a function relating to the first weight or the second weight mentioned above. For example, the sum of the first weight and the second weight is 1; therefore, both the first weight and the second weight are greater than or equal to 0 and less than or equal to 1. Thus, the range of the preset function is 0 to 1. For example, if the first weight is P, then the second weight is 1-P; or if the second weight is P, then the first weight is 1-P. The preset function is denoted by f, which is P=f(Mint,Mthd). Where Mint is the first distance, and Mthd is the optical dead zone distance.

[0068] In some other embodiments, the independent variables of the preset function may also include the second distance and the optical dead zone distance. Since the sum of the first weight and the second weight is 1, if the independent variables of the preset function are the second distance and the optical dead zone distance, it is only necessary to adjust the dependent variable of the preset function to the second weight.

[0069] In this embodiment of the disclosure, the method for calculating the target distance using the first distance, the first weight, the second distance, and the second weight can refer to the following formula (2) or formula (3): (2) (3) in, For dynamic distance, The first distance, This is the second distance.

[0070] The preset function is used to smooth the curve of the value change of the first weight or the second weight. Therefore, in order to make the continuity and transition of the weight change better, a continuous monotonic function with a threshold value between [0, 1] can be used to simulate the change of the P value. For example, the sigmoid function can be used to characterize the change process of P, so as to smooth the ranging results of the inner and outer optical paths to the target more smoothly and avoid the result jump. The sigmoid function formula is shown in the following formula (4): P=sig[k( )]= (4) Where P is the second weight and k is the transition smoothness. A larger k value makes the transition faster, and vice versa. The value of k can be set according to factors such as the optical structure of the module, the abrupt change value that the system can tolerate, and the moving speed of the target under test.

[0071] Combining formulas (3) and (4) above, we can obtain the following formula (5) to calculate the dynamic distance of the target: (5) In this way, when measuring the distance to a moving target, the internal and external optical paths can be flexibly switched to measure the distance to the target, and the jump in the distance measurement result caused by the change of the internal and external optical path distance measurement method can be avoided, thus improving the stability of the distance measurement result.

[0072] It should be noted that the embodiments disclosed herein are only illustrated by using the sigmoid function as the preset function (smoothing function). In other embodiments, the preset function (smoothing function) may also be other continuous functions with a value range of [0,1], such as trigonometric functions, linear functions, etc.

[0073] Through the above embodiments of this disclosure, the optical ranging device is provided with a first photosensitive area 231 that can detect the first reflected light inside the module housing 210. The first photosensitive area 231 detects a superimposed layer of the first reflected light and a second reflected light reflected back from the first opening 211 by the target object. The distance to the target object is determined based on the detected superimposed data parameters and the first data parameters corresponding to the first reflected light. In this way, the distance to the target object within the optical dead zone distance can be detected, overcoming the limitation of dToF modules in being unable to accurately measure the distance to the target object within the optical dead zone distance.

[0074] Furthermore, the optical ranging device can also be equipped with a second photosensitive area 232 to detect the distance to the target located outside the optical dead zone. This increases the detection range of the optical ranging device. Moreover, considering the high sensitivity of SPAD devices and the existence of quenching time, factors such as temperature and voltage have a particularly significant impact on ranging accuracy. To eliminate the influence of temperature and voltage on ranging accuracy, the first photosensitive area 231 and the second photosensitive area 232 can be used as detection modules for the inner and outer optical paths, respectively. Since the effects of external factors such as temperature and voltage on the inner and outer optical paths are simultaneous and consistent, subtracting the ranging results from the two optical paths can eliminate these common-mode interferences, thereby improving the accuracy of the outer optical path detection.

[0075] Furthermore, since the first photosensitive area 231 of this embodiment can be used to realize the distance of the target to be measured located within the optical dead zone distance, the solution of this embodiment can also realize the distance detection of the target to be measured in a moving state.

[0076] Furthermore, when the target to be measured moves rapidly or moves at a critical position, the solution provided in this embodiment of the present disclosure also optimizes the calculation method of the output dynamic distance, making the output results more accurate and smooth.

[0077] In summary, the solutions provided by the embodiments of this disclosure optimize the ranging performance of the optical ranging device from multiple perspectives and improve the practicality of the optical ranging device.

[0078] Based on the same inventive concept, this disclosure also provides an optical ranging device 200, such as... Figure 2 As shown, the optical ranging device 200 includes: Module housing 210, module housing 210 having a first opening 211; The light source 220 and the photosensitive chip 230 are located inside the module housing 210; The first opening 211 is opposite to the light-emitting surface of the light source 220; the photosensitive chip 230 is provided with a first photosensitive area 231; The first photosensitive area 231 is used to detect the first reflected light and the second reflected light emitted from the light source 220 and reflected by it. The first reflected light is the light emitted from the light source 220 and reflected by the inner wall of the module housing 210 to the first photosensitive area 231. The second reflected light is the light emitted from the light source 220 to the surface of the target 10 outside the module housing 210, reflected by the surface of the target 10, and then re-entering the module housing 210 through the first opening 211 and being received by the first photosensitive area 231.

[0079] In addition, the optical ranging device 200 module housing 210 also includes a second opening 212, and the photosensitive chip 230 also includes a second photosensitive area 232, which is opposite to the second opening 212.

[0080] The structure and working principle of the optical ranging device can be referred to the optical ranging device 200 involved in any of the above embodiments, and will not be repeated here.

[0081] In some embodiments, the optical ranging device 200 further includes a processor; The processor is configured to perform at least some of the steps in any of the methods described above.

[0082] It is understood that the photosensitive chip 230 may have data processing capabilities to perform the steps in any of the above methods, but its data processing capabilities may not be sufficient to perform complex data processing, such as data processing for transition situations in the above embodiments. Therefore, an external processor can also be used to perform data processing to complete at least some of the steps of the above methods.

[0083] In another embodiment, the optical ranging device 200 described above can also be an electronic device containing a processor, such as a mobile phone or a smart terminal. The processor inside can also be used to execute all the data processing related steps in any of the above methods, while the photosensitive chip 230 can only perform signal transmission related processing.

[0084] The methods disclosed in the several method embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new method embodiments.

[0085] The features disclosed in the several device embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new device embodiments.

[0086] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure.

Claims

1. An optical ranging method, characterized in that, An optical ranging device is used in an optical ranging device, the optical ranging device comprising: a module housing having a first opening; a light source and a photosensitive chip located within the module housing; wherein the first opening is opposite to the light-emitting surface of the light source; and a first photosensitive area is provided on the photosensitive chip; The method includes: Acquire photon time-of-flight detection data of the first photosensitive area; Acquire the first data parameters of the first reflected light and the superposition data parameters of the first reflected light and the second reflected light from the photon time-of-flight detection data of the first photosensitive area; wherein, the first reflected light is the light emitted from the light source and reflected by the inner wall of the module housing to the first photosensitive area, and the second reflected light is the light emitted from the light source to the surface of the target to be tested outside the module housing, reflected by the surface of the target to be tested, and then re-entering the module housing through the first opening and being received by the first photosensitive area; The distance to the target to be measured is determined based on the first data parameters and the superimposed data parameters.

2. The method according to claim 1, characterized in that, The photon flight time detection data of the first photosensitive area includes a first statistical histogram and a second statistical histogram. The horizontal axis of the first statistical histogram and the second statistical histogram is the photon flight time, and the vertical axis is the number of photons. The first data parameters include: the first centroid and the intensity of the first centroid corresponding to the first reflected ray in the first statistical histogram; The superimposed data parameters include: the superimposed centroid and superimposed centroid intensity of the first reflected ray and the second reflected ray in the second statistical histogram.

3. The method according to claim 2, characterized in that, Determining the distance to the target based on the first data parameters and the superimposed data parameters includes: The first centroid strength is used as the weight of the first centroid, and the superimposed centroid strength is used as the weight of the superimposed centroid; The distance to the target to be measured is determined based on the first centroid and its weight, the superimposed centroid and its weight, and the weighted centroid algorithm of the histogram.

4. The method according to claim 2, characterized in that, Time-of-flight detection data of the first photosensitive area are acquired in a time-division manner to form the first statistical histogram and the second statistical histogram, respectively; The photon time-of-flight detection data corresponding to the first statistical histogram was acquired without setting a target to be measured.

5. The method according to any one of claims 2 to 4, characterized in that, The module housing further includes a second opening, and the photosensitive chip further includes a second photosensitive area, the second photosensitive area being opposite to the second opening; the method further includes: Acquire photon time-of-flight detection data related to the target in the second photosensitive area; The third data parameter about the third reflected light is obtained from the photon time-of-flight detection data of the second photosensitive area. The third reflected light is the light emitted from the light source to the target outside the module housing, reflected by the surface of the target, enters the module housing through the second opening, and is received by the second photosensitive area. The distance to the target to be measured is determined based on the third data parameter.

6. The method according to claim 5, characterized in that, The photon time-of-flight detection data of the second photosensitive area includes a third statistical histogram, and the method further includes: Based on the second statistical histogram, determine the first distance of the target at the first moment; and / or Based on the third statistical histogram, determine the second distance of the target at the second time point; Wherein, the first distance is less than the optical dead zone distance of the optical ranging device, and the second distance is greater than or equal to the optical dead zone distance of the optical ranging device.

7. The method according to claim 6, characterized in that, The method further includes: Obtain the time difference between the first moment and the second moment; If the time difference between the first moment and the second moment is less than a time threshold, the dynamic distance of the target to be measured is determined based on the first distance and the second distance; wherein the dynamic distance is the instantaneous distance of the target to be measured output by the optical ranging device.

8. The method according to claim 6, characterized in that, Determining the dynamic distance of the target to be measured based on the first distance and the second distance includes: Obtain a first weight related to the first distance and a second weight related to the second distance; wherein the first weight and the second weight are related to the optical dead zone distance of the optical ranging device; The dynamic distance is determined based on the first distance, the first weight, the second distance, and the second weight.

9. The method according to claim 8, characterized in that, The method further includes: Obtain a preset function, wherein the independent variables of the preset function include the first distance and the optical dead zone distance, and the value range of the preset function is 0 to 1; The preset function is used to smooth the value change curves of the first weight and / or the second weight during the process of determining the dynamic distance of the target to be measured.

10. An optical ranging device, characterized in that, include: A module housing having a first opening; The light source and photosensitive chip are located inside the module housing; The first opening is opposite to the light-emitting surface of the light source; the photosensitive chip is provided with a first photosensitive area; The first photosensitive area is used to detect the first reflected light and the second reflected light emitted and reflected by the light source; wherein, the first reflected light is light emitted by the light source and reflected by the inner wall of the module housing to the first photosensitive area; the second reflected light is light emitted by the light source to the target surface outside the module housing, reflected by the target surface, re-entering the module housing through the first opening, and received by the first photosensitive area.

11. The optical ranging device according to claim 10, characterized in that, The optical ranging device also includes a processor; The processor is configured to perform at least some of the steps in the method as described in any one of claims 1 to 9.

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