CN114089353A - Detection system and detection method - Google Patents

Abstract

The application provides a detection system, characterized in that includes: a light source configured to output emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit further obtains final target information according to the return light signal in the second time period, and the working unit can obtain the final target information in the second time period by obtaining the first delay time, so that the effect of detecting the target distance more accurately is achieved.

Description

Detection system and detection method

Technical Field

The present application relates to the field of detection technologies, and in particular, to a detection system and a detection method.

Background

In recent years, with the progress of semiconductor technology, miniaturization of a ranging module for measuring a distance to an object has progressed. Therefore, for example, it has been realized to install a ranging module in a mobile terminal such as a so-called smart phone which is a small information processing apparatus having a communication function with the advancement of technology, and in the distance or depth information detection process, a method frequently used is Time of flight ranging (TOF) whose principle is to obtain a target distance by continuously transmitting a light pulse to a target and then receiving light returned from the object with a sensor, by detecting the flight (round trip) Time of the light pulse, and a technique of directly measuring the light flight Time in the TOF technique is called DTOF (direct-TOF); a measurement technique of periodically modulating the emitted light signal, measuring a phase delay of the reflected light signal with respect to the emitted light signal, and calculating a time of flight from the phase delay is called an ITOF (index-TOF) technique. According to the difference of modulation and demodulation types, the method can be divided into a Continuous Wave (CW) modulation and demodulation mode and a Pulse Modulated (PM) modulation and demodulation mode, Direct Time of flight (DTOF) is used as one of TOF, and the DTOF technology directly obtains a target distance by calculating the transmitting and receiving Time of an optical Pulse.

The detection principle of DTOF is to apply an operating voltage greater than a certain threshold voltage to a detector pixel unit (a single photon avalanche diode is currently used, and SPAD is not limited herein), so that the diode is in an avalanche mode, so that the detector pixel unit will have a particularly high sensitivity, for SPAD diode, even can be triggered by a single photon, and can output the target distance of the detected object by obtaining the statistical result of multiple triggers, however, in the practical application process, the detection system is generally disposed in a housing, part of laser light after the laser light emits the light source will be reflected in the detector array by a lens or a lens, a device panel, at least one surface of the housing accommodating the detection system, and the like, so that part of the detector pixel unit in the detector array will be reflected, and especially, more impurities exist on the lens or the lens as the use time becomes longer, therefore, more emitted light is reflected back to the detector array, and the emitted light received by the detector array is different through a lens or a lens and the like due to the phenomena, namely, the receiving array needs to be adjusted and corrected, and the receiving module is ensured to continuously obtain a more accurate detection result.

Disclosure of Invention

An object of the present application is to provide a receiving module for overcoming the defects in the prior art, so as to solve the technical problem that the existing detecting unit cannot cope with the wavelength variation of the laser emitting light source to obtain the optimal signal-to-noise ratio to ensure the accurate and efficient detection of the object distance.

In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

in a first aspect, an embodiment of the present application provides a detection system, including: a light source configured to output emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit also obtains final target information according to the return light signals in the second time period.

Optionally, the array type receiver is an array type receiver composed of SPAD pixel units.

Optionally, only a part of the SPAD pixel cells are working cells in all detection periods.

Optionally, the number of SPAD pixel units operating in the first period of time is less than the number of operating SPAD pixel units acquiring field-of-view return light information in the second period of time.

Optionally, at least some of the receiving units in the receiving module are in a linear mode of SPAD during the first delay time period, and at least some of the receiving units are in an avalanche mode of SPAD during the second time period.

Optionally, the dielectric layer includes at least one of the following: a lens or mirror, a device panel, at least one face of a housing containing the detection system, and the like.

Optionally, the receiving unit of at least part of the receiving module, which obtains the return light signal reflected by the dielectric layer in the first time period, is determined in at least one of the following manners:

presetting functions or table relations, etc., self-adapting, starting up presetting, etc.

In a second aspect, the present embodiments provide a detection method using the detection system of the first aspect, which is characterized by including a light source, the light source outputting emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit also obtains final target information according to the return light signals in the second time period.

Optionally, the array type receiver is an array type receiver composed of SPAD pixel units.

Optionally, only a part of the SPAD pixel cells are working cells in all detection periods.

Optionally, the number of SPAD pixel units operating in the first period of time is less than the number of operating SPAD pixel units acquiring field-of-view return light information in the second period of time.

Optionally, at least some of the receiving units in the receiving module are in a linear mode of SPAD during the first delay time period, and at least some of the receiving units are in an avalanche mode of SPAD during the second time period.

Optionally, the receiving unit of at least part of the receiving module, which obtains the return light signal reflected by the dielectric layer in the first time period, is determined in at least one of the following manners:

presetting functions or table relations, etc., self-adapting, starting up presetting, etc.

The beneficial effect of this application is: provided is a reception module, characterized by including: a light source configured to output emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit further obtains final target information according to the return light signals in the second time period; therefore, the working unit can obtain the final target information in the second time period by obtaining the first delay time, and further the effect of more accurately detecting the target distance is realized, the pixel units of part of detectors of the DTOF detection system work partially, so that on one hand, the possibility of dividing the non-working pixel units and the working pixel units exists, on the other hand, the idle time period can be distributed in the working pixel units to obtain the first delay time, so that more accurate correction results can be obtained for the working pixel units, and more accurate detection results can be obtained.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic diagram illustrating an operating principle of a detection system according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram illustrating an influence of a dielectric layer on a detection result according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a reference unit according to an embodiment of the present application;

fig. 4 is a schematic diagram of another embodiment of the present application, in which at least a part of a working unit is selected as a reference unit;

fig. 5 is a schematic diagram of a detection method of a detection system according to an embodiment of the present application;

fig. 6 is a schematic diagram of a system detection method for selecting at least a part of working units as reference units according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

Fig. 1 is a schematic diagram of a detection system according to an embodiment of the present disclosure. As shown in fig. 1, which illustrates a basic principle of acquiring an object by a detection system, a processing unit 120 controls a light source 110 to emit a transmission light, where the light source may be an LED or a laser source, where the light source is generally selected to be a laser source with a near-infrared wavelength in order to take into account safety of human eyes, etc., the laser source may be a VSCEL array type laser source, which is not limited herein, at least a part of the light source 110 emits a detection light, and certainly includes a scene where all of the transmission light and a part of the transmission light are emitted, which is not limited herein, in order to achieve energy concentration and high efficiency of system operation, a part of output units are generally used to output the transmission light, and a receiving module 130 includes a SPAD single photon avalanche diode detection unit, which can achieve accurate detection under weak energy.

In an actual detection process, a light source emits pulse laser with a certain pulse width, for example, in a nanosecond level, final target distance information is obtained from a statistical result by emitting the pulse laser ten thousand times, the pulse laser is reflected back to an array type receiving module in an avalanche state SPAD through a detection target 140, a detection unit in the avalanche state can receive a returned signal, and the processing unit 120 can output a distance between a detection system and the detection target.

Fig. 2 is a schematic diagram illustrating the influence of the medium layer on the detection result provided by the embodiment of the present application, the light source 210 emits laser light, the medium layer 250 is located between the emitted light and the detected object, which may be a lens or a mirror, a device panel, at least one surface of a housing in which the detection system is disposed, and the like, the light source 210 emits the emitted light, the medium layer 250 reflects a portion of the laser light, and as the usage time increases, more impurities will be present on the medium layer 250, and thus more emitted light will be reflected, at least a portion of the detector module 230 is triggered by the laser light reflected back through the medium layer 250, and a large amount of calculation will be added for the whole statistics after more pixel units are triggered to generate avalanche, and in addition, the laser light reflected by the medium layer 250 will interfere with the detection of the detection object 240, so that the effective information of the detection object 240 is interfered, the final detection target information is also affected, which causes inaccuracy of the whole detection result, and the influence on the dielectric layer 250 needs to be corrected in real time along with the increase of time, so that the detection system can be adaptively adjusted and ensured to be always in a state of efficient operation, the reflection information of the dielectric layer 250 can be continuously updated by using at least part of the SPAD pixel units of the receiving module, and then the detection result of the reflection information of the dielectric layer 250 can be adjusted in real time, thereby realizing the real-time adjustment on the first delay time, ensuring that the detection system can be adaptively operated in various states, and further adjusting at least part of the units of the receiving module 250 from the linear mode to the geiger mode in a second time period after the first delay time period, therefore, the return light reflected by the detection target 240 is obtained only in the second time period of the return light signal reflected by the detection target 240 in the field of view, so that the most accurate detection result of the detection system can be ensured, and the influence of the medium layer 250 on the detection result of the detection system is avoided.

Fig. 3 is a schematic diagram of a reference cell configuration provided in an embodiment of the present application, where an edge pixel in an SPAD array is greatly affected by receiving background light, and a pixel generally disposed at an edge position of a detector array is a non-working pixel, and is also used as a reference pixel to eliminate noise interference of the array, but generally, the edge pixel is closer to a laser source, and therefore, the probability of being triggered is higher, and the working pixel cell in the detector array used in the present invention is not all cells in the array, which can ensure that at least some cells in the detector array can share a processing circuit such as a TDC, and thus the detector as a whole can be realized, and in order to further improve the detection efficiency and resolution of the array, multi-subframe detection can be performed, for example, the working time of a black pixel cell in the detection array in fig. 3 is not consistent with that of a gray pixel cell, therefore, the final detection result can be formed by splicing the detection results twice or more than twice, so as to realize the full-coverage and high-resolution detection of the field of view, the edge pixel is set as the reference unit Re, so that the receiving module can be arranged to obtain the first delay time in any time period without influencing other working pixel units, on the other hand, the receiving module and the edge pixel are combined to realize the adaptability of the system to the complex field of view multi-target condition and ensure the detection efficiency of the detection system, the first delay time is more accurately obtained when only part of the receiving module is in the working state, because the results of a plurality of subframes are required to be superposed, on the one hand, the number of the working units of each subframe is less, so that the probability of the working units being influenced by the dielectric layer 250 is larger, on the other hand, the superposition in the results of each subframe is influenced, further affecting the validity of the overall detection result, which in severe cases may cause the overall detection system to fail in this mode of operation and not be used for distance acquisition, the above problem can be solved by the arrangement of fig. 3, wherein at least part of the receiving units are in the SPAD linear mode during the first delay period, and in the SPAD avalanche mode during the second period, and when this is achieved a certain voltage can be applied to the system during the linear mode, but this voltage is lower than the threshold voltage, for example, at a level of 1V or 2V lower than the threshold voltage, and during the second period in which avalanche is required the voltage is raised above the avalanche threshold voltage, for example, 3V or some other fixed value higher than the avalanche voltage, which can ensure a fast response of the detection unit without directly applying a high voltage such that the detector pixel unit requires a long response time, thereby affecting the detection efficiency and the detection accuracy.

Fig. 4 is another schematic diagram of selecting at least a part of reference cells in working cells according to an embodiment of the present application, which is similar to the setting principle and the working principle of the reference cells in fig. 3 and will not be described in detail herein, but the difference between them is that at least a part of cells in at least one of working pixel groups GB1, GB2, GB3, GB4, GB5, etc. are selected as reference cells, because the probability that these working pixels receive return light reflected by a dielectric layer is also relatively large according to the light emitting rule of a light source, so that the first delay time period can be obtained more accurately, the result obtained by the reference cells can be set according to different values according to different working cell configurations using an average algorithm or a maximum value, etc., and is not limited herein, and can be selected from gray working pixel groups, and the optimal number of the reference cells needs to be smaller than the number of pixel cells in actual working, therefore, the detection efficiency of the whole system can be ensured, the processing method of obtaining the first delay time by the reference pixel is the same as the method of obtaining the detection target by the working unit, so that the working reliability of the whole system is ensured, and the selected reference unit can be determined according to at least one of the following rules: the method includes the steps of presetting functions or table relations and the like, self-adapting, starting up presetting and the like, thus ensuring the working reliability of the whole system and also ensuring the simplicity and convenience of implementation.

Fig. 5 is a schematic diagram of a detection method of a detection system according to an embodiment of the present application, which mainly includes the following steps: the invention relates to a method for outputting emitted light by a light source S101, which is a problem encountered in the application of an SPAD single photon detection system, in particular to a risk that the detection of the system cannot be realized under a detection mechanism due to the problem related to a detection method with only part of detection units as working units.

S102 at least part of receiving units of the receiving module receive return light signals of the emitted light reflected back by the dielectric layer and acquire first delay signals, wherein the receiving units can be fixed units such as edge units in the module, or variable reference units, such as pixel units selected from working pixel units in a self-adaptive mode, a startup preset mode and the like according to preset functions or table relations and the like, and specific working time is acquired by methods such as adaptation, startup correction and dynamic correction in non-working time periods, so that real-time tracking of influences on the dielectric layer in the system is realized.

S103, at least part of receiving units of the receiving module obtain return light information in a field of view in a second time period after the first delay time period, wherein the receiving units may or may not include the units of S102, but preferably are more than the receiving units in S102 in number, so that the detection system is ensured to process less data, and the purpose of efficient operation of the system is ensured.

S104, the processing unit obtains final target information according to the return light signals in the second time period, after the return light delay information of the medium layer is removed, the processing unit obtains return light information reflected by the detection target in the view field, the processing module can construct a more accurate histogram by utilizing the information and combining the timestamp of the TDC module, so that accurate information of the detected object in the final view field is obtained, and the method is certainly suitable for complex scenes with different multiple targets and far and near states.

Fig. 6 is a schematic diagram of a system detection method for selecting at least a part of the working units as reference units according to an embodiment of the present application, in which a part of the process is similar to that of fig. 5 and will not be described in detail,

s201, at least part of the working units are selected as reference units, and selection rules can be determined by using methods such as preset functions or table relations, self-adaption, startup presetting and the like, so that the reference units are dynamically determined.

S202 the reference unit receives a return light signal which is reflected and returned by the transmitting light through the dielectric layer and acquires a first delay signal, and the reference unit acquires the working time period of the reference unit for acquiring the first delay time according to methods such as self-adaption, power-on correction and dynamic correction in the non-working time of the receiving module, so that the whole system has higher autonomy.

S203, the reference unit is restored to be the working unit, the receiving units of at least part of the receiving modules obtain the return light information in the field of view in a second time period after the first delay time period, and after the reference unit of the non-working time period finishes the acquisition of the first delay time period, the whole detector receiving module array obtains the final field of view information by using a method of multi-subframe synthesis of part of the units according to the previous working rule, which is similar to the method for constructing a histogram and finally obtaining the target distance information in the process of constructing the histogram in the figure 5.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (13)

1. A detection system, comprising: a light source configured to output emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit also obtains final target information according to the return light signals in the second time period.

2. A detection system according to claim 1 wherein the array-type receiver is an array-type receiver of SPAD pixel cells.

3. The detection system of claim 2, wherein only a portion of the SPAD pixel cells are active cells during all detection periods.

4. A detection system according to claim 3, wherein the number of SPAD pixel elements operating in the first time period is less than the number of operating SPAD pixel elements acquiring field-of-view return light information in the second time period.

5. The detection system of claim 2, wherein at least some of the receiving units in the receiving module are in a linear mode of SPAD during the first delay period and in an avalanche mode of SPAD during the second period.

6. The detection system of claim 1, wherein the dielectric layer comprises at least one of:

a lens or mirror, a device panel, at least one face of a housing containing the detection system, and the like.

7. The detection system of claim 1, wherein the receiving unit of the at least a portion of the receiving module that obtains the return optical signal reflected by the dielectric layer during the first time period is determined by at least one of:

presetting functions or table relations, etc., self-adapting, starting up presetting, etc.

8. A detection method using the detection system of claim 1, comprising: a light source that outputs emitted light; an array type receiving module that receives return light of the emitted light through a field of view; a dielectric layer located on the light source propagation path; the receiving unit of the at least part of receiving module receives return light information which is emitted by the light source in a first time period and reflected by the medium layer; the processing unit can acquire a first delay signal according to at least part of the return information acquired by the receiving unit; at least part of receiving units of the receiving module obtain return light signals output to a field of view by the light source in a second time period after the first time delay time period; the processing unit also obtains final target information according to the return light signals in the second time period.

9. A method of detection according to claim 8 wherein the array-type receiver is an array-type receiver of SPAD pixel cells.

10. The detection method of claim 9, wherein only a portion of the SPAD pixel cells are active cells during all detection periods.

11. The detection method according to claim 10, wherein the number of SPAD pixel elements operating in the first time period is smaller than the number of operating SPAD pixel elements that acquire field-of-view return light information in the second time period.

12. The detection method of claim 9, wherein at least some of the receiving units in the receiving module are in a linear mode of SPAD during the first delay time period and in an avalanche mode of SPAD during the second time period.

13. The detection method of claim 8, wherein the receiving units of at least a portion of the receiving modules that obtain the return optical signals reflected by the dielectric layer during the first time period are determined by at least one of:

presetting functions or table relations, etc., self-adapting, starting up presetting, etc.

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