CN112703422B - Time-of-flight sensor and related systems and methods - Google Patents
Time-of-flight sensor and related systems and methods Download PDFInfo
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- CN112703422B CN112703422B CN202080003913.2A CN202080003913A CN112703422B CN 112703422 B CN112703422 B CN 112703422B CN 202080003913 A CN202080003913 A CN 202080003913A CN 112703422 B CN112703422 B CN 112703422B
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- 101100370021 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) TOF2 gene Proteins 0.000 description 5
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- 101100314162 Candida albicans (strain SC5314 / ATCC MYA-2876) YBL053 gene Proteins 0.000 description 4
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4808—Evaluating distance, position or velocity data
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/495—Counter-measures or counter-counter-measures using electronic or electro-optical means
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Abstract
The application discloses a time-of-flight sensor and related systems and methods. The time-of-flight sensor is used for controlling the light emitting module to continuously emit a plurality of light pulses, the light pulses are reflected by the target object to generate a plurality of reflected light pulses, and the time-of-flight sensor comprises: the control circuit generates a light emitting control signal to control the light emitting module to send the plurality of light pulses based on time-varying frequency, and also generates a sensing control signal to control the pixel array to sense the plurality of reflected light pulses based on the time-varying frequency; the pixel array generates a plurality of sensing outputs according to the sensed reflected light pulses; the time-digital conversion unit generates a plurality of conversion outputs according to the light-emitting control signal and the plurality of sensing outputs; and the processing circuit obtains a statistical result according to the plurality of conversion outputs, and obtains the flight time from the light-emitting module to the target object and back to the pixel array based on the statistical result.
Description
Technical Field
The present application relates to sensor technology, and more particularly, to a time-of-flight sensor and related systems and methods.
Background
The time-of-flight measurement technique includes a direct time-of-flight measurement technique that utilizes the emission of a light pulse to a target, and then measures the time interval between the time of receipt of a reflected light pulse reflected from the target and the time of emission of the light pulse, thereby obtaining the time-of-flight of the light, and then the measured time-of-flight is used to calculate depth information.
However, when a plurality of measurement devices using the direct time-of-flight measurement technique are simultaneously measuring on the same occasion (for example, a plurality of persons in a room are respectively using mobile phone terminals with the direct time-of-flight measurement function), reflected light pulses reflected from each other may be received, and signal interference between the devices may be caused. Therefore, how to reduce interference and improve accuracy has become one of the problems to be solved in the art.
Disclosure of Invention
An embodiment of the present application discloses a time-of-flight sensor for controlling a light emitting module to continuously emit a plurality of light pulses, the plurality of light pulses being reflected by a target to generate a plurality of reflected light pulses, the time-of-flight sensor comprising: the control circuit is coupled with the light emitting module, the pixel array and the time-digital conversion unit, generates a light emitting control signal to control the light emitting module to send the light pulses based on time-varying frequency, and also generates a sensing control signal to control the pixel array to sense the reflected light pulses based on the time-varying frequency; the pixel array generates a plurality of sensing outputs according to the sensed reflected light pulses; the time-digital conversion unit generates a plurality of conversion outputs according to the light-emitting control signal and the plurality of sensing outputs; and the processing circuit is used for obtaining a statistical result according to the plurality of conversion outputs and obtaining the flight time from the light-emitting module to the target object and then returning to the pixel array based on the statistical result.
Another embodiment of the present application discloses a time-of-flight sensing system comprising: the time-of-flight sensor described above; and the light-emitting module.
Another embodiment of the present application discloses a time-of-flight sensing method comprising: generating a light emission control signal to control the light emitting module to transmit the plurality of light pulses from the reference position based on the time-varying frequency, wherein the plurality of light pulses are reflected by the target object to generate a plurality of reflected light pulses; sensing the plurality of reflected light pulses at the reference location based on the time-varying frequency; generating a plurality of sensing outputs in dependence upon the plurality of reflected light pulses sensed; generating a plurality of conversion outputs according to the light emission control signal and the plurality of sensing outputs; obtaining a statistical result according to the plurality of conversion outputs; and obtaining the flight time from the reference position to the target object and back to the reference position based on the statistical result.
Another embodiment of the application discloses a time-of-flight sensor comprising: the pixel array generates a plurality of sensing outputs according to a plurality of sensed reflected light pulses, wherein the plurality of reflected light pulses are formed by a light emitting module which sends a plurality of light pulses to a target object according to a light emitting control signal and based on time-varying frequency and is reflected by the target object; a time-to-digital conversion unit for generating a plurality of conversion outputs according to the light emission control signal and the plurality of sensing outputs; and the processing circuit is used for obtaining a statistical result according to the plurality of conversion outputs and obtaining the flight time from the light-emitting module to the target object and then returning to the pixel array based on the statistical result.
The disclosed time-of-flight sensors and related systems and methods may reduce mutual interference between time-of-flight sensors by emitting multiple pulses of light having a time-varying frequency.
Drawings
FIG. 1 is a functional block diagram of one embodiment of a time-of-flight sensing system of the present application.
FIG. 2 is a graph of waveforms of multiple light pulses emitted by two time-of-flight sensing systems having the same and fixed frequency when another time-of-flight sensing system is in the vicinity of the time-of-flight sensing systems.
FIG. 3 is a histogram statistic obtained by accumulating a plurality of converted outputs received by the time-of-flight sensing system in the context of FIG. 2.
Fig. 4 is a waveform diagram of a time-of-flight sensing system of the present application when another pulse of light of a fixed frequency is emitted in the vicinity of the time-of-flight sensing system.
FIG. 5 is a histogram statistic obtained by accumulating a plurality of converted outputs received by the time-of-flight sensing system of the present application in the context of FIG. 4.
Detailed Description
The following disclosure provides various embodiments or examples that can be used to implement various features of the present disclosure. Specific examples of components/elements and arrangements are described below to simplify the present disclosure. It is to be understood that these statements are to be considered in the light of the examples and not as limitations on the scope of the application. For example, in the following description, forming a first feature on or over a second feature may include certain embodiments in which the first and second features are in direct contact with each other; and may also include embodiments in which additional components/elements are formed between the first and second features such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. Such reuse is for brevity and clarity purposes and does not itself represent a relationship between the different embodiments and/or configurations discussed.
Moreover, spatially relative terms, such as "under," "below," "lower," "upper," and the like, may be used herein to facilitate a description of the relationship between one element or feature to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass a variety of different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be placed in other orientations (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein interpreted accordingly.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain standard deviations found in their respective testing measurements. As used herein, "identical" generally refers to actual values within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range. Alternatively, the term "same" means that the actual values fall within acceptable standard deviations of the average values, as determined by the consideration of those skilled in the art to which the present application pertains. It is to be understood that all ranges, amounts, values and percentages used herein (e.g., to describe amounts of materials, lengths of time, temperatures, operating conditions, ratios of amounts and the like) are modified by the term "same" unless otherwise specifically indicated. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present specification and attached claims are approximations that may vary depending upon the desired properties. At least these numerical parameters should be construed as the number of significant digits and by applying ordinary rounding techniques. Herein, a numerical range is expressed as from one end point to another end point or between two end points; unless otherwise indicated, all numerical ranges recited herein include endpoints.
When a plurality of measuring devices using the direct time-of-flight measuring technique measure at the same time on the same occasion, reflected light pulses reflected from each other may be received, thereby causing interference. Particularly, if the light pulses emitted by the measuring devices have the same period, each measuring device cannot distinguish the reflected light pulse reflected by the light pulse emitted by itself from the reflected light pulse reflected by the light pulse not emitted by itself. The present application avoids this problem by changing the frequency of the light pulses from fixed to non-fixed, as described in detail below.
FIG. 1 is a functional block diagram of one embodiment of a time-of-flight sensing system of the present application. The time of flight sensing system 100 can be used to measure the time of flight from the time of flight sensing system 100 to the target 114 and back to the time of flight sensing system 100 and estimate the distance between the target 114 and the time of flight sensing system 100 based thereon. It should be noted that the distance between the target object 114 and the time of flight sensing system 100 should be less than or equal to the maximum measured distance of the time of flight sensing system 100. In this embodiment, the time-of-flight sensing system 100 uses a direct time-of-flight metrology technique.
Notably, the time-of-flight sensing system 100 may be implemented as a variety of different types of time-of-flight ranging systems, such as a time-of-flight based optical ranging system, a time-of-flight based acoustic ranging system, a time-of-flight based radar ranging system, or other types of time-of-flight ranging systems. For brevity, the time-of-flight ranging scheme of the present application is described below in terms of an embodiment in which time-of-flight sensing system 100 is implemented as an optical ranging system.
The time-of-flight sensing system 100 can include, but is not limited to, a lighting module 112 and a time-of-flight sensor 102. The light emitting module 112 may include, but is not limited to, a driving circuit and a light emitting unit (not shown in fig. 1). The driving circuit is used for driving the light-emitting unit to enable the light-emitting unit to emit light pulses. The light emitting unit may be, but is not limited to, a semiconductor laser (also may be referred to as a laser diode), a light emitting diode, or other light emitting unit that may generate light pulses.
The time-of-flight sensor 102 includes a control circuit 104, a pixel array 106, a time-to-digital conversion unit 108, and a processing circuit 110. The control circuit 104 is coupled to the light emitting module 112, the pixel array 106 and the time-to-digital conversion unit 108, specifically, the control circuit 104 generates a light emission control signal Se to control the light emitting module 112 to continuously emit a plurality of light pulses LT (including LT1, LT 2) based on the time-varying frequency Fv, that is, the light emission control signal Se to control the light emitting module 112 to emit a plurality of light pulses LT at a plurality of transmission time points based on the time-varying frequency Fv, and the plurality of light pulses LT are reflected by the object 114 to generate a plurality of reflected light pulses LR (including LR1, LR 2). The control circuit 104 also generates a sensing control signal Ss to control the pixel array 106 to sense the plurality of reflected light pulses LR based on the time-varying frequency Fv, i.e. the control circuit 104 generates the sensing control signal Ss to control the pixel array 106 to sense the plurality of reflected light pulses LR in a plurality of sensing time periods based on the time-varying frequency Fv.
The pixel array 106 generates a plurality of sense outputs Spxo (including Spxo, spxo,) in accordance with the sensed plurality of reflected light pulses LR. The time-to-digital conversion unit 108 generates a plurality of converted outputs Stdc (including Stdc, stdc, and..2) according to the light emission control signal Se and the plurality of sensing outputs Spxo. The processing circuit 10 is configured to obtain statistics according to the plurality of conversion outputs Stdc, in this embodiment, the processing circuit 10 counts the data distribution of the plurality of conversion outputs Stdc, specifically, the processing circuit 10 groups the same values in the plurality of conversion outputs Stdc into a group, obtains a histogram (histogram) statistics, or a quality profile, and obtains a time of flight Sr from the light emitting module 112 to the target object 114 and back to the pixel array 106 based on the histogram statistics.
First, fig. 2 and 3 illustrate the problem to be solved by the present application by using a time-of-flight sensing system emitting light pulses at a constant frequency as a comparative example. FIG. 2 is a timing diagram of a plurality of light pulses emitted by two time of flight sensing systems having the same and fixed frequency when another time of flight sensing system TOF2 is in the vicinity of the time of flight sensing system TOF 1. Wherein the time of flight sensing system TOF1 emits a plurality of light pulses LT (comprising LT1, LT2,) having a fixed frequency F, i.e. a fixed time interval between the plurality of light pulses LT1, LT2, & gt, the time interval between T1 and T4, the time interval between T4 and T7 and the time interval between T7 and T10 are all the same as in fig. 2. The reflected light pulses LR (including LR1, LR2, etc.) after the light pulses LT are reflected back to the time of flight sensing system TOF1 by the target also have a fixed frequency F, and the time intervals between T2 and T5, between T5 and T8, and between T8 and T11 are the same as shown in fig. 2. Furthermore, the plurality of light pulses emitted by the further time of flight sensing system TOF2 also has a frequency F, which is the same as the plurality of light pulses LT, so that the plurality of reflected light pulses LR ' (comprising LR1', LR2',.) reflected from the object also has a frequency F, the time interval between T3 and T6, the time interval between T6 and T9, and the time interval between T9 and T12 are all the same as fig. 2.
In such a case, if both the plurality of reflected light pulses LR and the plurality of reflected light pulses LR ' (including LR1', LR2',.) are received by the time of flight sensing system TOF1, the pixel array of the time of flight sensing system TOF1 generates a plurality of sensing outputs Spxo (including Spxo1, spxo1', spxo2, spxo2', spxo3, spxo3', spxo, spxo4'. That is, so to speak with respect to fig. 2, for light pulse LT1, the time-of-flight sensing system receives two sensing outputs Spxo and Spxo' respectively; for light pulse LT2, the time-of-flight sensing system receives two sensing outputs Spxo and Spxo', respectively; for light pulse LT3, the time-of-flight sensing system receives two sensing outputs Spxo and Spxo', respectively; for light pulse LT4, the time-of-flight sensing system receives two sensing outputs Spxo 'and Spxo', respectively. It should be noted that the time of flight sensing system TOF2 is illustrated in fig. 2 as being farther away from the target object (i.e. LR' is later than LR return time).
The time-to-digital conversion unit of the time-of-flight sensing system then obtains a plurality of converted outputs Stdc (including Stdc1, stdc1', stdc2, stdc2', stdc3, stdc3', stdc, stdc4',. Specifically, the time-to-digital conversion unit of the time-of-flight sensing system can know the emission time points of the light pulses LT according to the emission control signal Se, and can generate according to the sensing outputs Spxo: the transition output Stdc represents the time interval (a value of 13 time units) from the emission of the light pulse LT1 to the reception of the sensing output Spxo 1; the transition output Stdc 'represents the time interval (24 time units in value) from the emission of the light pulse LT1 to the receipt of the sensing output Spxo'; the transition output Stdc represents the time interval (a value of 13 time units) between the emission of the light pulse LT2 to the receipt of the sensing output Spxo 2; the transition output Stdc 'represents the time interval (value 24 time units) from the emission of the light pulse LT2 to the reception of the sensing output Spxo'; the transition output Stdc represents the time interval (a value of 13 time units) from the emission of the light pulse LT3 to the reception of the sensing output Spxo 3; the transition output Stdc 'represents the time interval (24 time units in value) from the emission of the light pulse LT3 to the receipt of the sensing output Spxo'; the transition output Stdc4 represents the time interval (a value of 13 time units) between the emission of the light pulse LT4 to the receipt of the sensing output Spxo 4; the transition output Stdc 'represents the time interval (24 time units in value) from the emission of the light pulse LT4 to the receipt of the sensing output Spxo'.
The processing circuitry of the time of flight sensing system then generates the histogram statistics of fig. 3 based on a plurality of converted outputs Stdc (including Stdc1, stdc ', stdc2, stdc2', stdc3, stdc3', stdc, stdc',..4.) for a total of 36 converted outputs (1 to 36 time units), wherein it can be seen that the cumulative amount of converted outputs of 13 time units and 24 time units is typically 80 times, thus making it impossible for the processing circuitry of the time of flight sensing system to tell which of 13 time units and 24 time units should be reflected back to the time of flight sensing system as time of flight from the time of flight sensing system to the target.
It should be noted that the values at the other individual converted outputs have only relatively very small accumulated amounts, except for 13 time units and 24 time units, and that the values at these converted outputs may be due to other sources of interference (e.g., reflections from dust, or random errors from hardware, such as pixel array 106, etc.), but such random errors do not result in particularly noticeable accumulated amounts. The reason why the conversion output of the relatively maximum cumulative amount cannot be judged from the histogram statistics of fig. 3 is that it is disturbed by the other time of flight sensing system TOF2, more precisely, caused by the frequency synchronization of the plurality of light pulses emitted by the other time of flight sensing system TOF2 and the plurality of light pulses emitted by the time of flight sensing system TOF 1.
In fig. 4 and 5, the time-of-flight sensing system 100 of the present application is used to emit light pulses LT of time-varying frequency as compared to the comparative embodiment of fig. 4 and 5. Fig. 4 is a waveform diagram of a time-of-flight sensing system of the present application when another pulse of light of a fixed frequency is emitted in the vicinity of the time-of-flight sensing system 100. Wherein the time-of-flight sensing system 100 emits a plurality of light pulses LT (including LT1, LT2,) having a time-varying frequency Fv that varies in a pseudo-random manner over time such that a plurality of time intervals separating the plurality of light pulses LT are not exactly the same as one another, i.e., the plurality of light pulses LT1, LT2, & gt have a non-fixed time interval therebetween. For fig. 4, the time interval between T1 and T4, the time interval between T4 and T7, and the time interval between T7 and T10 are all different. The reflected light pulses LR (including LR1, LR2, etc.) after the light pulses LT are reflected back to the time of flight sensing system 100 by the target also have a non-fixed frequency Fv, and the time interval between T2 and T5, the time interval between T5 and T8, and the time interval between T8 and T11 are different from each other as shown in fig. 4. Furthermore, the plurality of light pulses emitted by the further time-of-flight sensing system has a fixed frequency F, so that the plurality of reflected light pulses LR ' (including LR1', LR2',.) reflected from the target 114 also has a fixed frequency F, the time interval between T3 and T6, the time interval between T6 and T9, and the time interval between T9 and T12 are all the same as in fig. 4.
In such a case, if both the plurality of reflected light pulses LR and the plurality of reflected light pulses LR '(including LR1', LR2',.) are received by the time-of-flight sensing system 100, the pixel array 106 of the time-of-flight sensing system 100 generates a plurality of sensing outputs Spxo (including Spxo1, spxo1', spxo2, spxo2', spxo3, spxo3', spxo, spxo ',.) as a function of the sensed plurality of reflected light pulses LR and LR'. That is, so that for light pulse LT1, time-of-flight sensing system 100 receives two sensing outputs Spxo and Spxo' respectively for fig. 4; for light pulse LT2, time-of-flight sensing system 100 receives two sensing outputs Spxo and Spxo', respectively; for light pulse LT3, time-of-flight sensing system 100 receives two sensing outputs Spxo and Spxo', respectively; for light pulse LT4, time-of-flight sensing system 100 receives two sensing outputs Spxo 'and Spxo', respectively.
The time-to-digital conversion unit 108 of the time-of-flight sensing system 100 then obtains a plurality of converted outputs Stdc (including Stdc1, stdc1', stdc2, stdc2', stdc3, stdc3', stdc, stdc4',. Specifically, the time-to-digital conversion unit 108 of the time-of-flight sensing system 100 can know the emission time points of the light pulses LT according to the emission control signal Se, and can generate according to the sensing outputs Spxo: the transition output Stdc represents the time interval (a value of 13 time units) from the emission of the light pulse LT1 to the reception of the sensing output Spxo 1; the transition output Stdc 'represents the time interval (24 time units in value) from the emission of the light pulse LT1 to the receipt of the sensing output Spxo'; the transition output Stdc represents the time interval (a value of 13 time units) between the emission of the light pulse LT2 to the receipt of the sensing output Spxo 2; the transition output Stdc 'represents the time interval (value is 20 time units) between the emission of the light pulse LT2 to the reception of the sensing output Spxo'; the transition output Stdc represents the time interval (a value of 13 time units) from the emission of the light pulse LT3 to the reception of the sensing output Spxo 3; the transition output Stdc 'represents the time interval (28 time units in value) from the emission of the light pulse LT3 to the receipt of the sensing output Spxo'; the transition output Stdc4 represents the time interval (a value of 13 time units) between the emission of the light pulse LT4 to the receipt of the sensing output Spxo 4; the transition output Stdc 'represents the time interval (18 time units in value) from the emission of the light pulse LT4 to the receipt of the sensing output Spxo'.
The processing circuit 110 of the time-of-flight sensing system 100 then generates the histogram statistics of fig. 5 according to the plurality of conversion outputs Stdc (including Stdc1, stdc1', stdc2, stdc2', stdc3, stdc3', stdc, stdc', and.+ -.) for a total of 36 conversion output values (1 to 36 time units). Since the emission time of the light pulse LT of the embodiment is no longer synchronized with the receiving time of the plurality of sensing outputs Spxo in comparison with fig. 2, in the histogram statistics of fig. 5, there is no relatively high accumulation at the value of 24 time units of the converted output, and only the highest accumulation at the value of 13 time units of the converted output is 80 times, so the processing circuit 110 of the time-of-flight sensing system 100 takes the highest number of 13 time units of the value as the time-of-flight from the light emitting module 112 to the target object 114 and back to the pixel array 106.
Embodiments of the present application may break up the non-random interference (i.e., synchronous interference) that would otherwise be caused by the other time-of-flight sensing system into pseudo-random interference by emitting light pulses of a time-varying frequency Fv, i.e., the frequency of the light pulses of the other time-of-flight sensing system is prevented from being exactly synchronized to the frequency Fv of the light pulses of the time-of-flight sensing system 100. Thus, on the histogram statistics of fig. 5, there is only a single salient accumulation, and the corresponding converted output value represents the true time of flight. Even if another time-of-flight sensing system uses the time-varying frequency technique as in the present application, the situation of fig. 2 and 3 is not created because the time-varying frequencies Fv of the light pulses emitted simultaneously by both time-of-flight sensing systems will vary in a pseudo-random manner, almost completely synchronization is not possible.
The above-described practice of pseudo-randomly generating the time-varying frequency Fv may be accomplished by, for example, in some embodiments, pseudo-randomly switching between a plurality of predetermined frequencies, e.g., pseudo-randomly varying between 6 predetermined frequencies, to obtain the time-varying frequency Fv.
In certain embodiments, it may also be employed to switch between multiple frequencies in a predetermined manner, and the multiple frequencies are generated in a pseudo-random manner, such as by changing the time-varying frequency Fv in a pseudo-random manner every fixed period.
In some embodiments, the two embodiments described above may be combined.
The foregoing description briefly sets forth features of certain embodiments of the application so that those skilled in the art may more fully understand the several aspects of the application. Those skilled in the art should appreciate that they can readily use the present application as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments described herein. It will be understood by those skilled in the art that such equivalent embodiments are within the spirit and scope of the present application and that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the present application.
Claims (18)
1. A time-of-flight sensor for controlling a light emitting module to continuously emit a plurality of light pulses, the plurality of light pulses being reflected by a target to produce a plurality of reflected light pulses, the time-of-flight sensor comprising:
The control circuit is coupled with the light emitting module, the pixel array and the time digital conversion unit, generates a light emitting control signal to control the light emitting module to send the light pulses at non-fixed time intervals based on time-varying frequency, and also generates a sensing control signal to control the pixel array to sense the reflected light pulses based on the time-varying frequency;
the pixel array generates a plurality of sensing outputs according to the sensed reflected light pulses; the time-digital conversion unit generates a plurality of conversion outputs according to the light-emitting control signal and the plurality of sensing outputs; and
And the processing circuit is used for obtaining a statistical result according to the plurality of conversion outputs and obtaining the flight time from the light-emitting module to the target object and then returning to the pixel array based on the statistical result.
2. The time-of-flight sensor of claim 1, wherein the statistics comprise histogram statistics.
3. The time-of-flight sensor of claim 1, wherein the time-varying frequency varies in a pseudo-random manner over time such that a plurality of time intervals separating the plurality of light pulses are not exactly the same as one another.
4. A time-of-flight sensor as claimed in claim 3, wherein the time-varying frequency is switched between a plurality of predetermined frequencies in a pseudo-random manner such that a plurality of time intervals separating the plurality of light pulses are not exactly the same as each other.
5. A time-of-flight sensor as claimed in claim 3, wherein the time-varying frequency is switched in a predetermined manner between a plurality of frequencies, the plurality of frequencies being generated in a pseudo-random manner such that a plurality of time intervals separating the plurality of light pulses are not exactly the same as one another.
6. The time-of-flight sensor of claim 1, wherein the control circuit generates the light emission control signal to control the light emitting module to transmit the plurality of light pulses at a plurality of transmit time points based on the time-varying frequency, and the control circuit generates the sense control signal to control the pixel array to sense the plurality of reflected light pulses at a plurality of sense time periods based on the time-varying frequency.
7. The time-of-flight sensor of claim 1, wherein the plurality of converted outputs correspond to a plurality of times of flight for the plurality of pulses of light emitted from the light emitting module to the target, reflected back into the plurality of reflected pulses of light.
8. The time-of-flight sensor of claim 1, wherein the plurality of converted outputs have N values in total, N being less than the number of the plurality of converted outputs, the processing circuit counting the N values and their corresponding numbers among the plurality of converted outputs and taking a highest number of the N values as a time-of-flight from the light emitting module to the target and back to the pixel array.
9. A time-of-flight sensing system, comprising:
a time-of-flight sensor as claimed in any one of claims 1 to 8; and
The light emitting module.
10. A time-of-flight sensing method, comprising:
Generating a light emission control signal to control the light emitting module to transmit a plurality of light pulses at non-fixed time intervals from a reference position based on a time-varying frequency, the plurality of light pulses being reflected by a target object to generate a plurality of reflected light pulses;
Sensing the plurality of reflected light pulses at the reference location based on the time-varying frequency;
generating a plurality of sensing outputs in dependence upon the plurality of reflected light pulses sensed;
generating a plurality of conversion outputs according to the light emission control signal and the plurality of sensing outputs;
Obtaining a statistical result according to the plurality of conversion outputs; and
And obtaining the flight time from the reference position to the target object and returning to the reference position based on the statistical result.
11. A time-of-flight sensing method as claimed in claim 10, wherein the statistics comprise histogram statistics.
12. A time-of-flight sensing method as claimed in claim 10, wherein the time-varying frequency varies in a pseudo-random manner over time such that a plurality of time intervals separating the plurality of light pulses are not exactly the same as one another.
13. A time-of-flight sensing method as claimed in claim 12, wherein the time-varying frequency is switched between a plurality of predetermined frequencies in a pseudo-random manner such that a plurality of time intervals separating the plurality of light pulses are not identical to each other.
14. A time-of-flight sensing method as claimed in claim 12, wherein the time-varying frequency is switched in a predetermined manner between a plurality of frequencies, the plurality of frequencies being generated in a pseudo-random manner such that a plurality of time intervals separating the plurality of light pulses are not exactly the same as one another.
15. The time-of-flight sensing method of claim 10, wherein generating the emission control signal to control the light emitting module to transmit the plurality of light pulses based on the time-varying frequency comprises:
Generating a light emission control signal to control the light emitting module to transmit the plurality of light pulses at a plurality of transmission time points based on a time-varying frequency; and
The step of sensing the plurality of reflected light pulses based on the time-varying frequency comprises:
the plurality of reflected light pulses are sensed over a plurality of sensing periods based on the time-varying frequency.
16. The time-of-flight sensing method of claim 10, wherein the plurality of converted outputs correspond to a plurality of times of flight of the plurality of light pulses emitted from the light emitting module to the target, reflected back to the pixel array as the plurality of reflected light pulses.
17. The time-of-flight sensing method of claim 10, wherein the plurality of transformed outputs have a total of N values, N being less than the number of the plurality of transformed outputs, and the step of deriving the statistical result from the plurality of transformed outputs comprises:
Counting the N numerical values and the corresponding quantity thereof in the conversion outputs; and
The step of obtaining the time of flight from the reference position to the target object and back to the reference position based on the statistics comprises the following steps:
And taking the highest number of the N numbers as the flight time from the light emitting module to the target object and then returning to the pixel array.
18. A time-of-flight sensor, comprising:
the pixel array generates a plurality of sensing outputs according to a plurality of reflected light pulses sensed based on time-varying frequency, wherein the plurality of reflected light pulses are formed by a light emitting module sending a plurality of light pulses to a target object at non-fixed time intervals based on a light emitting control signal and based on the time-varying frequency and being reflected by the target object;
A time-to-digital conversion unit for generating a plurality of conversion outputs according to the light emission control signal and the plurality of sensing outputs; and
And the processing circuit is used for obtaining a statistical result according to the plurality of conversion outputs and obtaining the flight time from the light-emitting module to the target object and then returning to the pixel array based on the statistical result.
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