CN109870704A - TOF camera and its measurement method - Google Patents
TOF camera and its measurement method Download PDFInfo
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Abstract
It includes: transmitting module that the present invention, which provides a kind of TOF camera and its measurement method, TOF camera, for emitting optical signal to determinand；Receiving module, for acquiring the optical signal being reflected back by the determinand；Control module controls signal for sending to control the transmitting module and the receiving module, and for the optical signal and the optical signal being reflected back according to the transmitting, calculates the flight time of the optical signal；The receiving module includes at least one acquisition window, and the width of the acquisition window is different from the optical signal pulsewidth；The control signal includes at least one of dummy delay time signal, pulse width variations signal, acquisition window change width signal.The TOF camera and its measurement method, can expansion time flight measurement apart from while promote signal-to-noise ratio.
Description
Technical field
The present invention relates to optical field technology more particularly to a kind of TOF camera and its measurement methods.
Background technique
The full name of ToF is Time-of-Flight, i.e. the flight time, is to realize a kind of flight time by measuring light
The technology of accurate range determination.There are two types of modes for the measurement of TOF, and one is direct measurements (D-ToF), another is indirect
It measures (I-ToF).
D-ToF calculates measurement distance by the difference at two moment of record light emitting and light-receiving.This method
Principle is simple, but it is extremely difficult actually to reach ideal precision distance measurement, and emitted laser pulse is needed to have high energy
Amount, high duplication and short pulse duration etc. require, to the more demanding of hardware.When I-ToF emits a branch of by laser beam emitting device
Between on periodic modulation laser to body surface in sequence, return light then generated in timing one relative to incident light when
Between postpone, be embodied in phase delay, the size of phase delay and the flight time of light are directly proportional, and I-TOF passes through measurement
Phase delay carrys out light flight time measurement, further realizes range measurement.Commercial TOF depth camera mostly uses this at present
Technology.
However, I-TOF still faces some challenges, for example measurement distance is limited by the amplitude modulation period, and environment light is dry
The factors such as disturb and cause signal-to-noise ratio low etc., these challenges are still to further solve.
Summary of the invention
To solve the above problems, the present invention proposes a kind of TOF camera and its measurement method, it can be in expansion time flight measurement
Apart from while promote signal-to-noise ratio.
The present invention provides a kind of TOF camera, comprising: transmitting module, for emitting optical signal to determinand；Receiving module,
For acquiring the optical signal being reflected back by the determinand；Control module, for sending control signal to control the transmitting mould
Block and the receiving module, and for the optical signal and the optical signal being reflected back according to the transmitting, calculate institute
State the flight time of optical signal；The receiving module include at least one acquisition window, the width of the acquisition window with it is described
Optical signal pulsewidth is different；The control signal includes dummy delay time signal, pulse width variations signal, acquisition window change width
At least one of signal.
The present invention provides a kind of TOF camera measurement method, comprising the following steps: receives control signal, emits to determinand
Optical signal；Control signal is received, the optical signal being reflected back by the determinand is acquired；According to the optical signal of the transmitting and institute
The optical signal being reflected back is stated, the flight time of the optical signal is calculated；The optical signal being reflected back is by least one collecting window
Mouth acquisition, the width of the acquisition window are different from the optical signal pulsewidth；The control signal includes dummy delay time letter
Number, at least one of pulse width variations signal, acquisition window change width signal.
Beneficial effects of the present invention: by the way that signal will be controlled with dummy delay time signal, pulse width variations signal, collecting window
At least one of mouth width degree variable signal controls transmitting module or receiving module, so that reflected light signal can be collected
Window is acquired, according to acquisition window collected optical signal and then can measure and accurate surveying for flight time may be implemented
Amount；Another convenience, it is adjustable due to control signal so that TOF camera can carry out multiple spurs from measurement, while being able to ascend noise
Than.
Detailed description of the invention
Fig. 1 is a kind of TOF camera schematic illustration according to the embodiment of the present invention.
Fig. 2 is a kind of TOF camera structural schematic diagram according to the embodiment of the present invention.
Fig. 3 is a kind of TOF camera optical signal launch and acquisition method schematic diagram one according to the embodiment of the present invention.
Fig. 4 is a kind of TOF camera measurement method schematic diagram according to the embodiment of the present invention.
Fig. 5 is a kind of TOF camera optical signal launch and acquisition method schematic diagram two according to the embodiment of the present invention.
Fig. 6 is a kind of TOF camera optical signal launch and acquisition method schematic diagram three according to the embodiment of the present invention.
Fig. 7 is that a kind of TOF camera optical signal launch of single acquisition window according to an embodiment of the present invention shows with acquisition method
It is intended to.
Fig. 8 is a kind of optical signal curve synoptic diagram according to an embodiment of the present invention.
Fig. 9 is a kind of TOF camera optical signal launch according to an embodiment of the present invention and acquisition method schematic diagram four.
Figure 10 is a kind of TOF camera optical signal launch according to an embodiment of the present invention and acquisition method schematic diagram five.
Specific embodiment
The present invention is described in detail by specific embodiment with reference to the accompanying drawing, for a better understanding of this hair
It is bright, but following embodiments are not intended to limit the scope of the invention.In addition, it is necessary to illustrate, diagram provided in following embodiments
The basic conception that only the invention is illustrated in a schematic way, in attached drawing only display with related component in the present invention rather than according to reality
Component count, shape when implementation and size are drawn, when actual implementation each component shape, quantity and ratio can for it is a kind of with
The change of meaning, and its assembly layout form may also be increasingly complex.
Fig. 1 is a kind of TOF camera schematic illustration according to an embodiment of the present invention.TOF camera 101 includes transmitting module
103, receiving module 104 and control module 105.Control module 105 is connect with transmitting module 103, receiving module 104, for controlling
Transmitting module 103 processed emits optical signal 106 (such as pulsed laser signal) and arrives body 102 to be measured, and, for controlling and receiving module
104 receive optical signal 107 through reflection, and control module 105 will also be corresponding with reflected light signal progress based on transmitting optical signal
Calculation processing, for calculating the flight time of optical signals in space.
In some embodiments, the distance between transmitting module 103 and receiving module 104 109 is several millimeters or so, remote small
In distance 108 of the body 102 to be measured apart from TOF camera 101, therefore, pass through 105 pairs of transmitting optical signals 106 of control module and reflection
The time difference (phase difference) of optical signal 107 is calculated, and Δ t is denoted as, it is possible to further determine according to light propagation speed is constant
Reason, the distance 108 of body 102 to be measured can be acquired by formula (c Δ t/2).
Fig. 2 is a kind of TOF camera structural schematic diagram according to an embodiment of the present invention.The main building block of TOF camera 101
It is identical as Fig. 1, in addition, TOF camera 101 further includes drive circuit module, power module, shell etc., in figure and it is not entirely shown.
TOF camera 101 can be independent device, can be integrated in the electronic equipments such as mobile phone, tablet computer, computer.
Transmitting module 103 includes laser 201, laser driver 202, optical modulator 203.Laser driver 202 and swash
Light device 201 connects, luminous for driving laser 201, such as with certain pulsewidth emission pulse laser signal；Laser 201
The optically modulated device 203 of the light beam launched launches outward after modulating.
In some embodiments, laser 201 is the VCSEL laser of near infrared band, due in solar spectrum, closely
The ratio of infrared band is much lower compared to visible light, while the detector detection efficient of silicon substrate material can reach spy substantially
The requirement of survey can farthest reduce the interference of sunlight；In the present embodiment, its wavelength of the laser selected for
850nm or 940nm.Laser driver 202 is connect with laser 201, for driving laser 201 to launch high frequency modulated light
Beam includes laser drive circuit inside laser driver 202.
In one embodiment, optical modulator 203 includes diffusing globe, and the light beam for launching laser 201 carries out
Shaping is to form floodlighting, spatially to form preferable face illumination；In one embodiment, optical modulator 203 includes
Diffraction optical element, the light beam for launching laser 201 carry out diffraction to form spot beam, such as regularly arranged
Spot beam, compared with floodlighting, the calculated flight time signal-to-noise ratio of spot beam institute is higher.In one embodiment,
Optical modulator 203 further includes lens, and the light beam for launching laser 201 is reflected to realize and the function such as focus, collimate
Energy.
Receiving module 104 includes camera lens 204, optical filter 205 and imaging sensor 206；Wherein, in imaging sensor 206
Portion includes acquisition window 207 and acquisition window 208.Reflected light is by being imaged onto imaging sensor after camera lens 204 and optical filter 206
206, then by acquisition window 207 and acquisition window 208 reflected light is acquired, demodulates and obtain the time difference, so obtain to
Survey the distance value of object.
In some embodiments, camera lens 204 is made of one or more optical lenses, for collecting from object reflection
Reflected light signal is simultaneously imaged on imaging sensor 206；Optical filter 205 need to select the narrow-band-filter to match with optical source wavelength
Piece, for inhibiting the background noise of remaining wave band；Imaging sensor 206 is a kind of to fly the time (TOF) measurement dedicated for light
Imaging sensor, such as CMOS (complementary metal oxide semiconductor), APD (avalanche photodide), SPAD (single photon snow
Avalanche photo diode) etc. imaging sensors, the pixel of imaging sensor can be single-point, linear array or face battle array etc. forms.
Control module 105 is connect with transmitting module 103 and receiving module 104, for issuing control signal to each module
To implement corresponding control operation, and relevant calculation and processing etc. are carried out to the image received.
In some embodiments, the control function of control module 105 includes required when providing the transmitting laser of laser 201
Periodic modulation signal, acquisition window 207 and the acquisition signal of acquisition window 208 etc. in imaging sensor 206 are provided, also
The monitoring signals of auxiliary are provided, such as temperature sensing, overcurrent, overvoltage protection, fall off protection；Also include in control module 105
There are deposit and processing module, the collected initial data of acquisition window in imaging sensor 206 is saved and handled accordingly, is obtained
To the specific location of body to be measured.
Fig. 3 is a kind of TOF camera optical signal launch according to an embodiment of the present invention and acquisition method schematic diagram one.In Fig. 3
The acquisition signal for acquiring signal 303 and acquisition window B including emitting optical signal 301, reflected light signal 302, acquisition window A
304.Transmitting module is sent to body to be measured for optical signal 301 is emitted, and is back to and connects by the reflected light signal 302 that body to be measured is reflected back
Module is received, successively reflected light signal 302 is acquired by acquisition window A and acquisition window B, then by processor to acquisition
To signal calculation processing obtain Δ t, and then obtain the distance value of body to be measured.Acquisition window A and acquisition window B can be image
Acquisition window of the single pixel in different time sections on sensor, is also possible to adjacent pixel, for example, left and right it is adjacent, on
Under adjacent or the diagonal adjacent corresponding acquisition window A of two pixels and acquisition window B.
In some embodiments, the acquisition signal 303 of acquisition window A and the acquisition signal 304 of acquisition window B are two phases
Position is opposite, frequency and the identical signal of transmitting laser signal 301 (reflected light signal 302), for leading to the optical signal received
It crosses multiple integration method and is converted to electric signal and be acquired；When the acquisition signal (303/304) of acquisition window is high level, ability
The reflected light signal 302 from sample is received, thus for a certain moment, an only window can receive reflected light signal
302.It should be noted that since the amplitude M of reflected light signal 302 is limited by many factors such as environment light, body to be measured, amplitude
It is a unknown quantity；Therefore, the rising edge of the failing edge of acquisition window A and acquisition window B necessarily are in the arteries and veins of reflected light signal
In wide region, Δ t value can be just solved according to the relative intensity value of two acquisition windows.The non-phase of window claims failing edge in figure, just
Phase claims rising edge.
Fig. 4 is a kind of TOF camera measurement method schematic diagram according to the embodiment of the present invention.Firstly, as described in step 401:
By control module emissioning controling signal (such as duty ratio of setting acquisition window), so that the failing edge of acquisition window A and acquisition
The rising edge of window B is in the pulsewidth region of reflected light signal 302；Again by described in step 402: being counted by acquisition window A
The electric signal (charge accumulation amount) for calculating reflected light 302, is denoted as QA, such as the area in region 305 in figure；Again by described in step 403:
The electric signal (charge accumulation amount) that reflected light 302 is calculated by acquisition window B, is denoted as QB, such as the area in region 306 in figure；Most
Afterwards, as described in step 404: by reflected light 302 and the time difference of emergent light 301 is denoted as Δ t, pulsewidth is denoted as Th, by QAAnd QB
It calculates, obtains following result:
It should be noted that Q0For the electric signal of the environment light measured in no incident light, detection mode can pass through
Aforesaid way detection, can also detect, this is not restricted, such as after reflected light 302 has been received by other means
It is Q by the collected electric signal of acquisition window C (not shown) within the back segment time of cycle T0。
However, this method is feasible according to theory analysis, but there are some limitations, it is illustrated refering to Fig. 5.Due to this
The realization of scheme, a precondition are that the failing edge of window A and the rising edge of window B need to be in reflected light signal 302
In pulsewidth region, in some embodiments, in order to increase measurable distance, unlike embodiment illustrated in fig. 3, by collecting window
Mouthful width (time of integration) be set as different from the pulsewidth of optical signal, duty ratio difference in other words, generally acquisition window A
Width is greater than optical signal pulsewidth.Since acquisition window width is different from pulsewidth, this will lead to reflected light signal 302 and can be only in instead
Optical signal 501 is penetrated to the signal in 502 section of reflected light signal, that is, the time of reflected light signal 302 and transmitting optical signal 301
Difference has been limited in Δ t1~Δ t2Section in, limitation thus is caused to detecting distance, it is farther out or relatively close for detecting distance
Object, it is impossible to accurate detection.
Fig. 6 is a kind of TOF camera optical signal launch and acquisition method schematic diagram three according to the embodiment of the present invention.In Fig. 6
The acquisition signal for acquiring signal 603 and acquisition window B including emitting optical signal 601, reflected light signal 602, acquisition window A
604.In order to increase measurement distance, the width T of acquisition window A and acquisition window B in the present embodimentHIt is configured to be greater than optical signal
Pulsewidth Th.Transmitting module is sent to body to be measured for optical signal 601 is emitted, and reflected light signal 602 is back to receiving module.It can be with
Understand, when body to be measured is closer, reflection signal will entirely fall in acquisition window A the (feelings as shown in 605 in Fig. 6
Shape), when body to be measured distance farther out when, reflection signal will be entirely fallen in acquisition window B, both situations can not all be surveyed
Amount.
It is illustrated by taking the situation of Fig. 6 as an example, in order to solve this problem, in the present embodiment, control module is to transmitting
Module sends control signal, for example setting dummy delay time t makes transmitting module postpone transmitting light letter relative to receiving module
Number, the transmitting optical signal and reflected light signal after delay transmitting are as shown in dotted line 606 and 607 in Fig. 6, as dummy delay time t
When being suitably worth for some, the pulsewidth section of reflected light signal 607 will include the failing edge and acquisition window of acquisition window A simultaneously
The rising edge (refer specifically to reflected light signal can be collected window A and acquisition window B is received) of B, passes through collecting window
Mouth A and acquisition window B is successively acquired reflected light signal 607, finally obtains Δ t to collected signal calculation processing,
And then obtain testing distance value.
Realize that the key of the present embodiment method is that suitable dummy delay time t, which how is arranged, makes reflected light signal
607 pulsewidth section is by the rising edge of failing edge and acquisition window B simultaneously comprising acquisition window A, due to the distance of body to be measured
It is unknown, or for dynamic scene, the distance of body to be measured is constantly changing, therefore dummy delay time t is in different surveys
Also constantly changing in the amount frame period.In one embodiment, the mode taken multiple measurements within the single frame period solves this
The different dummy delay time is arranged when measurement every time, until finding suitable dummy delay time t in one problem.
It should be noted that the T in Fig. 6 refers to that single pulse transmitting and received period, frame period refer generally to often obtain
The required time of depth image (distance value) frame is taken, the frame period generally comprises one or more impulse ejection and connects
Receive cycle T.For the present embodiment, the frame period include at least multiple pulses emit with receive the period and.
In one embodiment, the value of dummy delay time t is the width value T by acquisition windowHWith transmitting optical signal 601
The pwm value T of (reflected light signal 602)hRatio determine；Remember TH/Th=L, when Δ t is (k-1) Th~k ThIt is any in section
When value, t is set as t=TH- k T, k=1,2 ... ... L needs to carry out at least K times measurement, be usually no more than 2L measurement.
When just reflected light signal drops into acquisition window failing edge and rising edge, void at this time is set as like delay time
T, by the signal value of the secondary measurement, the calculation formula of flight time is as follows:
In one embodiment, acquisition window can only be set as single window, for example only include acquisition window A.Fig. 7 is
The TOF camera optical signal launch and acquisition method schematic diagram of list acquisition window according to an embodiment of the invention.Acquisition window
Relationship between width and transmitting signal pulsewidth is set to: TH=3Th, carry out in the single frame period 4 measurements (T1, T2, T3,
T4), control module applies the dummy delay time of t1 (t1=0), t2, t3, t4 to transmitting module when measuring every time, wherein ti
=(i-1) Th, i=1,2,3,4；Acquisition window A collects 4 optical signals: Q1, Q2, Q3 and Q4 altogether.From embodiment illustrated in fig. 7
As can be seen that only in the 3rd measurement, reflected light signal can drop into the failing edge of acquisition window A.4 optical signals of acquisition
Curve graph is as shown in Figure 8.It is assumed that complete reflected light signal intensity is Q, the part light letter in acquisition window A failing edge is dropped into
Number intensity is Q ', and background light signal intensity is Q0, then has following relationship:
Q1=Q2=Q+Q0
Q3=Q '+Q0 (3)
Q4=Q0
By above-mentioned relation, in conjunction with formula (1), the flight time of optical signal can be calculated by following formula:
Wherein, Q and Q ' can be by a variety of calculations, for example, Q=Q1-Q4, alternatively, Q=Q2-Q4, alternatively, Q=Q1+
Q2-2Q4；Q '=Q3-Q4.It is understood that using Q=Q1+Q2-2Q4 this calculation substantially to repeatedly measure into
It has gone averagely, signal-to-noise ratio can be effectively reduced.When pendulous frequency is more, Q and Q ' can be by the way that averagely (intermediate value be average or adds
Weight average) mode calculated to reduce signal-to-noise ratio.
In Fig. 7 and embodiment illustrated in fig. 8, the delay time repeatedly measured is with THIt is set for step-length, it in this way can be true
It protects only a single point and falls in decline phase of curve, i.e., only single measurement can allow reflection signal to drop into the failing edge of acquisition window.
In some embodiments, it is also possible to by reducing step-length, so that the curve decline phase includes more than one point, it finally equally can be with
Signal-to-noise ratio is promoted by the modes such as average.
In embodiment shown in Fig. 6~8, it is exemplary applied by control module to transmitting module when providing close-in measurement it is empty
Quasi- delay time, the i.e. mode of delay pulse clock solve the situation that closer object is unable to measure.For telemeasurement
For, the dummy delay time can be emitted to postpone to acquire clock, to make acquisition window past to receiving module by control module
After postpone, until find the pulsewidth section of reflected light signal and meanwhile include acquisition window A failing edge and/or acquisition window B
Rising edge.Such as in one embodiment, for the situation of single acquisition window, collecting window is allowed by setting certain step-length
Mouth postpones backward, the curve of same available similar Fig. 8 after repeatedly measuring, the difference is that the curve in the present embodiment will be by scheming
Decline curve in 8 becomes ascending curve.It is understood that curve is to rise or decline to depend on the dummy delay time
Setting, for example for embodiment illustrated in fig. 7, the dummy delay time can also be configured to gradually reduce with certain step-length, i.e.,
It is changed stepwise from t4 to t1, such obtained curve is ascending curve.
On the one hand single acquisition window reduces the hardware requirement of imaging sensor compared with more acquisition windows, on the other hand
The identical function of more acquisition windows may be implemented in conjunction with dummy delay signal, so that cost be greatly reduced.
In above-mentioned each embodiment, the measurement of flight time can be effectively carried out by way of repeatedly measuring, simultaneously
Improve measurement distance and signal-to-noise ratio.But bring adverse effect is since the increase of time in single frames leads to depth information simultaneously
The frame per second of acquisition reduces, and is unfavorable for carrying out high-acruracy survey to the body to be measured of high-speed motion.In order to solve this problem, at one
In embodiment, delay time setting no longer as the gradual setting in the illustrated embodiment of Fig. 6~8 (gradually with certain step-length
Increased or decrease), but by random or with certain search strategy (such as gradient descent method, iterative method, dichotomy etc.)
Be configured, the set-up mode that theoretically more can quickly receive reflected light signal is better, can so reduce pendulous frequency from
And promote frame per second.
Fig. 9 is a kind of TOF camera optical signal launch according to an embodiment of the present invention and acquisition method schematic diagram four, here together
Sample is illustrated by taking single acquisition window as an example.Unlike the embodiments above, control module is to transmitting module in the present embodiment
The control signal of transmission includes pulse width variations signal, so that the pulsewidth of light emission signal changes in multiple measurement.Such as
Shown in Fig. 9, the relationship between acquisition window width and transmitting signal pulsewidth is set to: TH=3Th, the interior progress 3 of single frame period
Secondary measurement (T1, T2, T3), control module applies the dummy delay of t1 (t1=0), t2, t3 to transmitting module when measuring every time
Time, wherein ti=(i-1) Th, i=1,2,3；Control module can also apply pulse width variations to transmitting module when in addition measuring every time
Signal, the pulsewidth measured in the present embodiment for the first time is identical as the pulsewidth of third time measurement, Th1=Th3, and measure for the second time
Pulsewidth is twice of T of the pulsewidth of measurement for the first timeh2=2Th1, acquisition window A collects 3 optical signals: Q1, Q2 and Q3 altogether.By
In increasing pulsewidth, embodiment illustrated in fig. 7 is compared, the present embodiment is only achieved that in second of measurement and falls into transmitting optical signal
The failing edge of acquisition window, reduces pendulous frequency.It is assumed that second of complete reflected light signal intensity when measuring is Q, fall into
It is Q ' to the part optical signals intensity in acquisition window A failing edge, background light signal intensity is Q0, then measurement and for the first time
It is strong when the complete reflected light signal intensity and background light signal intensity for corresponding to pulsewidth when measuring three times are measured with second
There are proportional relations for degree, there is following relationship:
Q1=mQ+Q0
Q2=Q '+Q0 (5)
Q3=nQ+Q0
In above formula, m=n=1/2, it is to be understood that the ratio between specific numerical value and pulsewidth is related, surveys for the first time
Measuring the pulsewidth measured with third can not also be identical.Q then can be calculated by modes such as direct or average computations by formula (4)
With Q ', finally bring into formula (3) to calculate the flight time.
It is understood that control module has sent dummy delay signal to transmitting module simultaneously in embodiment illustrated in fig. 9
And pulse width variations signal, in some embodiments, it is also possible to send pulse width variations signal only to realize the survey to the flight time
Amount.Being continuously increased or reduce, the down or up edge until reflected light signal to be fallen into acquisition window to pulsewidth can be passed through
The flight time can be calculated.The set-up mode of pulse width variations is similar with the set-up mode of dummy delay signal, can be gradually
It, can also be by random or with certain search strategy (such as gradient descent method, iterative method, two into formula (cumulative or decrescence)
Point-score etc.) it is configured, the set-up mode that theoretically more can quickly receive reflected light signal is better, can so reduce measurement
Number is to promote frame per second.
Figure 10 is a kind of TOF camera optical signal launch according to an embodiment of the present invention and acquisition method schematic diagram five.Here
Equally it is illustrated by taking single acquisition window as an example.The control signal that control module is sent to receiving module in the present embodiment includes adopting
Collect window width variable signal, so that acquisition window width changes in multiple measurement, for example passes through control pixel
Time for exposure changes the width of acquisition window.As shown in Figure 10,3 measurements (T1, T2, T3) have been carried out in the single frame period,
Control module sends control signal to receiving module when measurement every time, so that acquisition window width gradually increases, respectively TH1、
TH2、TH3, it is assumed that the pulsewidth for emitting optical signal is constant, and acquisition window A collects 3 optical signals: Q1, Q2 and Q3, it is assumed that second altogether
Complete reflected light signal intensity is Q when secondary measurement, and the part optical signals intensity dropped into acquisition window A failing edge is Q ',
Background light signal intensity is Q0, then has following relationship:
Q1=Q0
Q2=Q '+Q0 (6)
Q3=Q+Q0
Q and Q ' then can be calculated by modes such as direct or average computations by formula (5), the flight time of optical signal can
To be calculated by following formula:
It is understood that control module has sent acquisition window width to receiving module and becomes in embodiment illustrated in fig. 10
Change signal.Can by the continuous variation to acquisition window width, until reflected light signal is fallen into acquisition window decline or
Rising edge can calculate the flight time.The set-up mode of pulse width variations and dummy delay signal, pulse width variations signal are set
It is similar to set mode, can be gradual (cumulative or decrescence), it can also be by being randomly provided or with certain search strategy (ratio
Such as gradient descent method, iterative method, dichotomy) it is configured, it theoretically more can quickly receive the setting side of reflected light signal
Formula is better, can so reduce pendulous frequency to promote frame per second.
In some embodiments, control module can send control signal to transmitting module and receiving module simultaneously, than
Dummy delay signal and acquisition window change width signal such as are sent simultaneously, or sends pulse width variations signal simultaneously and adopts
Collect window width variable signal, or sends dummy delay signal, pulse width variations signal and acquisition window change width simultaneously
Signal.In short, can be by suitably controlling signal so that reflected light signal falls into the down or up edge of acquisition window i.e.
The flight time can be calculated.
In embodiment shown in Fig. 6~10, change by being taken multiple measurements in picture frame period, and in each measurement
At least one of dummy delay time, pulsewidth and acquisition window width realize the measurement of flight time, similarly, one
In a little embodiments, at least one of virtual delay time, pulsewidth, acquisition window width can be preset, so that it may control
The measurement range of the TOF camera, to realize the measurement of single TOF camera apart from controllable effect, i.e., using single TOF
Camera carry out multiple spurs from measurement；The significant increase application range of TOF camera.Such as, it is assumed that the pulsewidth of transmitting optical signal 601
Value Th=5ns, the width value T of acquisition windowH=20ns, i.e. TH=4ThWhen, it is arranged to t0=15ns when being virtually delayed, it is corresponding
Flight time measurement range delta t be 0~5ns；As the t0=10ns, corresponding flight time measurement range delta t of being virtually delayed
For 5~10ns；As the t0=5ns that is virtually delayed, it is 10~15ns that corresponding flight time measurement range, which is Δ t,.
What the present invention reached, which have the beneficial effect that, provides a kind of novel I-TOF detection technique, at the same to receiving module with
And transmitting module applies control signal with expansion time flight measurement distance and promotes signal-to-noise ratio.
The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be said that
Specific implementation of the invention is only limited to these instructions.For those skilled in the art to which the present invention belongs, it is not taking off
Under the premise of from present inventive concept, several equivalent substitute or obvious modifications can also be made, and performance or use is identical, all answered
When being considered as belonging to protection scope of the present invention.
Claims (10)
1. a kind of TOF camera characterized by comprising
Transmitting module, for emitting optical signal to determinand；
Receiving module, for acquiring the optical signal being reflected back by the determinand；
Control module for sending control signal to control the transmitting module and the receiving module, and is used for basis
The optical signal of the transmitting and the optical signal being reflected back, calculate the flight time of the optical signal；
The receiving module includes at least one acquisition window, and the width of the acquisition window is different from the optical signal pulsewidth；
The control signal includes dummy delay time signal, pulse width variations signal, at least one in acquisition window change width signal
Kind.
2. TOF camera as described in claim 1, which is characterized in that the control module be used for the transmitting module and
The receiving module sends control signal and the optical signal being reflected back is made to drop into the upper of at least one acquisition window
Rise along and/or failing edge, and the winged of the optical signal is calculated according to the collected optical signal of at least one described acquisition window institute
The row time.
3. TOF camera as claimed in claim 2, which is characterized in that
The dummy delay time signal emits the light for controlling the transmitting module with the dummy delay time delay
Signal, or the control receiving module acquire the optical signal with the dummy delay time delay；
The pulse width variations signal is used to control the light emitted when the transmitting module repeatedly measures within a frame period
The pulsewidth of signal changes；
Described in the acquisition window change width signal is used to control when the receiving module repeatedly measures within a frame period
The width of acquisition window changes.
4. TOF camera as claimed in claim 3, which is characterized in that the dummy delay time is according to the acquisition window
Width and the optical signal pulsewidth ratio determine.
5. TOF camera as claimed in claim 3, which is characterized in that the virtual delay time signal, pulse width variations letter
Number, the set-up mode of the acquisition window variable signal include one of set-up modes such as progressive, random, search strategy.
6. a kind of TOF camera measurement method, which comprises the following steps:
Control signal is received, emits optical signal to determinand；
Control signal is received, the optical signal being reflected back by the determinand is acquired；
According to the optical signal of the transmitting and the optical signal being reflected back, the flight time of the optical signal is calculated；
The optical signal being reflected back is acquired by least one acquisition window, the width of the acquisition window and the optical signal arteries and veins
It is wide different；
The control signal include dummy delay time signal, pulse width variations signal, in acquisition window change width signal extremely
Few one kind.
7. TOF camera measurement method as claimed in claim 6, which is characterized in that the control signal makes described be reflected back
Optical signal drop into the rising edge and/or failing edge of at least one acquisition window, and according at least one described acquisition
Window collected optical signal calculate flight time of the optical signal.
8. TOF camera measurement method as claimed in claim 7, which is characterized in that
The dummy delay time signal is used to emit with the dummy delay time delay optical signal, or with described virtual
Delay time delay acquires the optical signal；
The pulsewidth of the optical signal emitted when the pulse width variations signal for repeatedly measuring within a frame period becomes
Change；
The width hair of the acquisition window when acquisition window change width signal for repeatedly measuring within a frame period
Changing.
9. TOF camera measurement method as claimed in claim 8, which is characterized in that the dummy delay time adopts according to
The width and the optical signal pulsewidth ratio for collecting window determine.
10. TOF camera measurement method as claimed in claim 8, which is characterized in that the virtual delay time signal, described
Pulse width variations signal, the acquisition window variable signal set-up mode include in the set-up modes such as progressive, random, search strategy
One kind.
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