Specific embodiment
In order to which technical problem to be solved of the embodiment of the present invention, technical solution and beneficial effect is more clearly understood,
The present invention is further described in detail below with reference to the accompanying drawings and embodiments.It should be appreciated that specific implementation described herein
Example is only used to explain the present invention, is not intended to limit the present invention.
It should be noted that it can be directly another when element is referred to as " being fixed on " or " being set to " another element
On one element or indirectly on another element.When an element is known as " being connected to " another element, it can
To be directly to another element or be indirectly connected on another element.In addition, connection can be for fixing
Effect is also possible to act on for circuit communication.
It is to be appreciated that term " length ", " width ", "upper", "lower", "front", "rear", "left", "right", "vertical",
The orientation or positional relationship of the instructions such as "horizontal", "top", "bottom" "inner", "outside" is that orientation based on the figure or position are closed
System is merely for convenience of the description embodiment of the present invention and simplifies description, rather than the device or element of indication or suggestion meaning must
There must be specific orientation, be constructed and operated in a specific orientation, therefore be not considered as limiting the invention.
In addition, term " first ", " second " are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance
Or implicitly indicate the quantity of indicated technical characteristic.Define " first " as a result, the feature of " second " can be expressed or
Implicitly include one or more this feature.In the description of the embodiment of the present invention, the meaning of " plurality " is two or two
More than, unless otherwise specifically defined.
The present invention provides a kind of time flight depth cameras, with stronger environment resistant light ability, it is possible to understand that
Being the problem of this programme is in addition to can solve ambient light interference, also can solve other problems, such as the problem etc. that power consumption is high.
Fig. 1 is time flight depth camera schematic diagram according to an embodiment of the invention.Time flight depth camera 10
Including emitting mould train 11, acquisition mould group 12 and processing circuit 13, wherein emitting mould train 11 provides transmitting light beam 30 to target empty
Between in illuminate the object 20 in space, at least partly transmitting light beam 30 through object 20 reflection after formed the reflected beams 40, reflection
At least partly collected mould group 12 of light beam 40 acquires, and processing circuit 13 connects with emitting mould train 11 and acquisition mould group 12 respectively
It connects, synchronized transmissions mould group 11 and the trigger signal for acquiring mould group 12 are issued with to calculate light beam by emitting mould train 11 and be collected mould
Time required for group 12 receives, i.e. flight time t between transmitting light beam 30 and the reflected beams 40, further, on object
The distance D of corresponding points can be calculated by following formula:
D=ct/2 (1)
Wherein, c is the light velocity.
Emitting mould train 11 includes light source 111, time optical modulator 112 and spatial light modulator 113.Light source 111 can be with
It is the light sources such as light emitting diode (LED), edge-emitting laser (EEL), vertical cavity surface emitting laser (VCSEL), is also possible to
The array of source of multiple light sources composition, the light beam that light source is emitted can be visible light, infrared light, ultraviolet light etc..
Time optical modulator 112 provides a time carrier signal to light source 111, is emitted accordingly with controlling light source 111
Carrier wave light beam.For example, in one embodiment, carrier signal is the pulse signal with certain frequency, and light source 111 is with the frequency
Emit pulsed light beam, can be used in direct time flight method (Direct TOF) measurement;In one embodiment, carrier signal
It is the square-wave signal or sinusoidal signal with certain wavelength, the amplitude of light source 111 is emitted accordingly by the carrier signal modulation
Square wave light beam or sine wave light beam, can be used for indirect flight Time Method (Indirect TOF) measurement in.It is understood that
It is that time optical modulator 112 can be independent control circuit and be also possible to processing circuit 13, for example processing circuit 13 passes through tune
The power of light source processed realizes the carrier modulation to light source amplitude.The frequency of carrier signal is set according to measurement distance, such as
1MHz~100MHz can be set into, measure distance at several meters to several hundred rice.
Spatial light modulator 113 receives the carrier wave light beam from light source 111, and carrier wave light beam is carried out spatial modulation, i.e.,
The distribution of carrier wave light beam in space is modulated to form the non-uniform non-floodlight carrier wave light beam of intensity distribution and launch outward.
Compared with traditional flood beam, since the intensity distribution of non-flood beam is uneven, in the identical situation of light source power, by force
Degree, which is distributed higher region, will have to the higher interference free performance of environment light;In addition, in the identical situation of projection field angle,
Due to the inhomogeneities of intensity distribution, base will reach identical environment light interference free performance, and floodlighting needs higher power consumption.
In some embodiments, the carrier wave light beam that spatial light modulator 113 is also used to receive expands, to expand
Field angle.
Processing circuit 13 can be independent special circuit, such as Special SOC chip, fpga chip, asic chip etc.,
Also it may include general processor, such as when the depth camera is integrated into such as mobile phone, TV, in computer intelligent terminal,
Processor in terminal can be used as at least part of the processing circuit 13.
In some embodiments, time flight depth camera 10 can also include the devices such as color camera, infrared camera, IMU
Function more abundant, such as the modeling of 3D texture, infrared face recognition, SLAM etc. may be implemented in part, the combination with these devices
Function.
Fig. 2 is emitting mould train schematic diagram according to an embodiment of the invention.Emitting mould train 11 includes light source 201, driving
Circuit 202, lens 203 and diffraction optical element (DOE) 204, light source 201 is under the Power x Time modulation of driving circuit 202
Emitting the light beam of pulse, square wave or sine wave modulation, light beam is incident on DOE204 after the collimation of lens 203 or focusing,
DOE204 carries out spatial modulation, i.e. diffraction to incident light beam.In one embodiment, DOE204 divides incident light beam
Beam, and launch multiple light beams 301,302 and 303, such as tens of thousands of light beams into object space, every light beam is in object 20
Surface formed a spot.In one embodiment, DOE204 (will be referred to by the diffraction formation rule arrangement to incident beam
The angular variation of each spot is uniformly distributed, regularly arranged to be incident on 3D body surface, and arrangement can be reconstructed) array of spots.?
In one embodiment, DOE204 will form speckle pattern by diffraction to incident beam, i.e., spot arrangement have it is certain with
Machine.
Light source 201 can be single source and be also possible to array of source.In one embodiment, light source 201 is by rule
The array of source of multiple light sources composition, for example be made of the VCSEL light source of semiconductor substrate and multiple arrangements on substrate
VCSEL array chip.The array beams that DOE204 emits light source 201 replicate, the non-flood beam launched outward by
The array beams of multiple duplications form, it is possible thereby to expand the quantity of field angle and light beam.
In some embodiments, the spatial light modulator in emitting mould train 11 also may include mask plate, wrap on mask plate
Containing the two-dimensional pattern that incident beam is modulated into non-flood beam, such as can be by incident beam through spatial modulation by mask plate
Form two-dimensional encoded pattern beam.
In some embodiments, the spatial light modulator in emitting mould train 11 also may include microlens array, lenticule
Array is arranged by multiple lenticule units, and in one embodiment, multiple lenticule units receive the light from light source 201
Array beams corresponding with the arrangement of lenticule unit are generated after beam to launch outward;In one embodiment, light source 201 also comprising with
Corresponding multiple sub-light sources are arranged in microlens array, each lenticule unit receives the light beam of corresponding sub-light source simultaneously
Array beams are launched outward after collimation or focusing.Array beams can be random alignment form and be also possible to regularly arranged form.
Fig. 3 is the emitting mould train schematic diagram of another embodiment according to the present invention.Emitting mould train 11 includes light source 303, drives
Dynamic circuit 304, optical beam scanner 305, can also include lens unit (not shown), and light source 303 issues light beam through light beam
Emit after 305 reflections of scanner/diffraction to object space.Driving circuit 304 carries out timing algorithm for power modulation to light source 201 to emit
The light beam of pulse, square wave or sine wave modulation, optical beam scanner 305 by along the rotation of uniaxial or multiaxis with by beam emissions to mesh
Mark space.Optical beam scanner includes MEMS (MEMS) scanner in one embodiment, due to high scanning
Frequency and lesser volume can make emitting mould train have lesser volume and higher performance.MEMS scanner can
To be scanned with the frequency of 1MHz~20MHz, therefore enough spaces and temporal resolution can be provided.Pass through driving circuit
304 and optical beam scanner 305 configuration, the light beam that can launch light source 303 carries out space and time-modulation to generate
Multiple patterns beam exit, such as regular speckle patterns, candy strip, the space pattern of Sine distribution etc..
In one embodiment, light source 303 is laser light source, its surface of MEMS scanner 305 includes balzed grating, thus
Striped can be generated in a predetermined direction, and more dense candy strip can produce by scanning in MEMS scanner 305, by
The resolution ratio of depth image can be improved in this.
In some embodiments, optical beam scanner 305 is also possible to liquid crystal light modulator, nano chips modulator etc..
Fig. 1 is returned to, acquisition mould group 12 includes array pixel cells 121, lens unit 122, and lens unit 122 receives and will
It is imaged on at least partly described array pixel cells 121 by at least partly non-floodlight carrier wave light beam that object is reflected back.Array
Pixel unit 121 can be charge coupled cell (CCD), complementary metal oxide semiconductor (CMOS), avalanche diode (AD),
The array pixel cells of the compositions such as single-photon avalanche diode (SPAD), array size represent the resolution ratio of the depth camera,
Such as 320x240 etc..Generally, what is connect with array pixel cells 121 further includes by signal amplifier, time to digital converter device
(TDC), the reading circuit (not shown) of one of devices such as analog-digital converter (ADC) or a variety of compositions.
Fig. 4 is array pixel cells schematic diagram according to an embodiment of the invention.Array pixel cells 40 include multiple
Pixel unit 401 is converted into electric signal by reading for receiving the light beam being reflected back by object, and by light energy or photon numbers
Circuit 50 exports.In this embodiment it is assumed that the speckle pattern being made of multiple spots 60 being reflected back by object, by right
Spot can be configured to suitable size to be imaged on array pixel cells by the setting of lens, emitting mould train etc..Such as this
In embodiment, the size of spot about occupies 4 pixel regions.It is understood that the size of spot also can be set into it is single
The pixel region of pixel, two pixels or other quantity, such array pixel cells 40 are divided into more according to incident light beam
A sub- pixel unit region.
In this embodiment it is assumed that individually stigmatic image is on the sub-pixel unit that tetra- pixels of A, B, C, D form, speckle
For spot amplitude in pattern by sine wave or square-wave frequency modulation, the period of modulation is T.A, tetra- pixels of B, C, D are configured to single
Activated on the different time in cycle time, for example, respectively 0~T/2, T/2~T, T/4~3T/4, in 3T/4~5T/4 time
It is activated to acquire light beam, respectively obtains optical signal value I1, I2, I3 and I4.Due to it is corresponding in four pixels be same
Spot, when spot is sufficiently small, the corresponding object of spot may be considered a point, that is, think the depth value phase in four pixels
Together, it is based on this, processing circuit can be according to four-stepped switching policy, and the distance value of spot is (when including flight in tetra- pixels of A, B, C, D
Between) will be calculated by following formula:
D=CTatan2 (I1-I3, I4-I2)/(4 π) (2)
It is understood that the size of spot can carry out designing adjustment accordingly for multistep phase shift.
In some embodiments, spot is configured to the size of 2 pixel units, such as at ellipticity.Spot amplitude quilt
Impulse modulation, pulse period T, one in 2 pixel units is activated with emitting mould train impulsive synchronization, and in 0~T/2
Interior reception light beam, another receives light beam in T/2~T time, generates electric signal I1, I2 respectively.Then 2 pixels are corresponding
The depth value (include flight time) of target object can be calculated by following formula:
In some embodiments, spot is configured to the size of the above pixel unit of at least three.Spot amplitude is by pulse tune
It makes, pulse period T, at least three in multiple pixel units acquires background light signal I0 within 0~T/3 time respectively, in T/
3~2T/3 acquires optical signal I1, acquires optical signal I2 in 2T/3~T.Or 0~T/3 time interior acquisition optical signal I1, T/3~
2T/3 acquires optical signal I2, and 2T/3~T acquires background light signal I0, can calculate the distance value of target object accordingly
The above is only how being carried out apart from calculating using speckle pattern to better illustrate, and that enumerates several possible adjusts
System and be applied equally to apart from depth calculation mode, other possible modulation systems and distance calculation formula it is proposed that it is non-
Flood light pattern.
In order to increase the resolution ratio of depth image, in some embodiments, the distance between adjacent spots be should not be too large, excellent
Selection of land, the distance between adjacent spots along a direction are configured to be no more than 1 times of spot itself size in the direction, such as
Spot lateral dimension is M, adjacent spots transversely between be divided into N, then N < M, preferably, N is configured to the 50% of M.
This scheme by the way that the multiple pixels fallen into same blob are carried out with timing control and approximate calculation depth value,
For the calculating of traditional single pixel, computational efficiency is increased dramatically.And for flood light pattern, due to single
The range of spot is smaller, and the multiple pixels dropped into single spot can be identified that (flood light pattern can not be positioned at phase
Consistent multiple pixels), calculated depth value confidence level is higher.
It is understood that be illustrated so that spot is formed by non-floodlight carrier wave light beam as an example in the embodiment above
, above scheme is equally applicable to other non-floodlight carrier wave light beams, such as striped, two-dimensional encoded pattern etc..
Fig. 5 is the flight time calculation method step schematic diagram according to the application one embodiment.The flight time calculates
Method is to be executed according to above-mentioned time flight depth camera by forms such as processing circuit, software, software and hardware combinings.In 511 steps
In, non-floodlight carrier wave light beam, emitting mould train such as Fig. 2, Fig. 3 and above-mentioned each embodiment institute are launched outward using emitting mould train
Show, the non-floodlight carrier wave light beam emitted includes the carrier light of the non-floodlight forms such as speckle, regular spot, two-dimensional encoded, striped
Beam;In 512 steps, at least partly described non-floodlight carrier wave light beam being reflected back by object, transmitting are acquired using acquisition mould group
Mould group launches the object after light beam in illumination target space, and is reflected by object, and what is be reflected back is at least partly described non-general
Light carrier light beam is received by collected mould group, acquires mould group as shown in Fig. 4 and the various embodiments described above;In step 513, calculate
Flight time between the non-floodlight carrier wave beam emissions and reflection passes through the side such as phase, high-speed shutter by processing circuit
Formula record and calculate the non-floodlight carrier wave light beam of transmitting and the light beam that is reflected back between flight time, specific calculation
It is detailed in the description of front, such as 2 phases, 3 phases and 4 phase calculation modes.
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.