CN214122466U

CN214122466U - Collector, distance measurement system and electronic equipment

Info

Publication number: CN214122466U
Application number: CN202022441578.4U
Authority: CN
Inventors: 苏健; 何燃; 李国花; 朱亮; 闫敏
Original assignee: Shenzhen Oradar Technology Co Ltd
Current assignee: Shenzhen Oradar Technology Co Ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2021-09-03
Anticipated expiration: 2030-10-28

Abstract

The utility model discloses a collector, distance measurement system and electronic equipment, including the pixel unit that comprises at least one macropixel, every macropixel includes the different pixel of a plurality of opening factors to be used for gathering the facula that the target of different distances department reflected back in the visual field; wherein the pixels with large aperture factor are configured to acquire far-distance light spots and the pixels with small aperture factor are configured to acquire near-distance light spots. The utility model discloses a set up the different pixel of shedding factor, received signal light is very strong on the pixel of having avoided the low coverage facula, and the pixel takes place the saturation easily or produces the condition of piling up the effect, has balanced the reflected signal intensity of the measured object of collector received different distances, has reduced the range of change of signal luminous intensity, has improved the range finding degree of accuracy.

Description

Collector, distance measurement system and electronic equipment

Technical Field

The utility model relates to an optical ranging technical field especially relates to a collector, distance measurement system and electronic equipment.

Background

The distance measurement can be performed on the target by using the Time of Flight (ToF) principle to obtain a depth image containing the depth value of the target, and further, the functions of three-dimensional reconstruction, face recognition, man-machine interaction and the like can be realized based on the depth image. Related distance measurement systems have been widely used in the fields of consumer electronics, unmanned driving, AR/VR, and the like. Distance measurement systems based on the time-of-flight principle often include a light beam emitter, in which a light source emits a light beam to a target space to provide illumination, and a collector, through which the light beam reflected by the target is received. The collector comprises a pixel array, generally a pixel array based on a Single Photon Avalanche Diode (SPAD), when one photon in a reflected light beam is incident to the SPAD, an avalanche event output signal can be triggered to record the time of the photon reaching the pixel, and the time required by the light beam from emission to reception is calculated based on the avalanche event output signal.

According to the light path configuration between the emitter and the collector, the ToF measuring system can be divided into a coaxial mode and an off-axis mode; the coaxial system usually enables the emitter and the collector to share one scanning device, such as an MEMS galvanometer, so that large-field scanning is realized; off-axis systems often do not require a scanning device, but more receiving elements (such as a pixel array) are arranged at the collector end, so that the distance of a plurality of points in a large field of view can be measured at one time.

For off-axis ToF measurement systems, in order to receive reflected signals from objects at different distances from the object to be measured, pixels are generally arranged in a two-dimensional array, and signal light is received by switching on super-pixels within the range of spot movement. However, since the intensity of the reflected signals from different distances to the object to be measured is approximately inversely proportional to the square of the distance, the signal light received by the pixels of the near-distance light spot is so strong that the pixels are easily saturated or generate serious pile-up effect, which results in inaccurate distance measurement.

The above background disclosure is only provided to aid in understanding the concepts and technical solutions of the present invention, and it does not necessarily belong to the prior art of the present patent application, and it should not be used to assess the novelty and inventive step of the present application without explicit evidence that the above content has been disclosed at the filing date of the present patent application.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a collector, distance measurement system and electronic equipment to solve at least one kind of problem among the above-mentioned background art problem.

In order to achieve the above object, the embodiment of the present invention provides a technical solution that:

a collector comprises a pixel unit consisting of at least one macro-pixel, wherein each macro-pixel comprises a plurality of pixels with different aperture factors and is used for collecting light spots reflected by targets at different distances in a field of view; the opening factor is any value between 0 and 1; wherein the pixels with large aperture factor are configured to acquire far-distance light spots and the pixels with small aperture factor are configured to acquire near-distance light spots.

In some embodiments, the pixel is configured with a blocking sheet to limit the light entering area of the pixel through the blocking sheet, so as to reduce the photosensitive area of the pixel.

In some embodiments, the shielding sheet is a metallic or non-metallic light shielding medium or coating disposed on the pixels.

In some embodiments, each pixel corresponds to one of the masking pieces, and a plurality of the masking pieces are configured to have different aperture factors.

In some embodiments, the shielding sheet is provided with an opening through which the signal light reflected by the target object to be measured is incident on the corresponding pixel.

In some embodiments, the shape of the opening of the shielding sheet may be square, rectangular, circular, polygonal, or other irregular shapes.

In some embodiments, the number of openings of the shutter may be one or more.

In some embodiments, the pixels are configured to have adjustable photosensitive area size, and the size of the photosensitive area of each pixel is adjusted to make the size of the photosensitive area of each pixel different, so that the pixels have different aperture factors.

The embodiment of the utility model provides another technical scheme does:

a distance measuring system comprises a collector, a transmitter and a processing circuit respectively connected with the transmitter and the collector in any embodiment scheme; wherein the content of the first and second substances,

the emitter is used for emitting pulse beams to a target area, and at least part of the pulse beams form reflected pulse beams after being reflected by the target area;

the collector receives photons in the reflected pulse light beam to form a photon signal;

and the processing circuit synchronizes the trigger signals of the emitter and the collector, processes the photon signals and calculates the distance information of the target to be measured based on the flight time of the reflected pulse beams.

The embodiment of the utility model provides a further technical scheme does:

an electronic device, comprising: the shell, the screen and the distance measuring system of the previous embodiment; the emitter and the collector of the distance measuring system are arranged on the same surface of the electronic device and used for emitting light beams to a target object, receiving the light beams reflected by the target object and forming electric signals.

The utility model discloses technical scheme's beneficial effect is:

compared with the prior art, the utility model discloses a set up the different pixel of aperture factor for the pixel aperture factor that the long distance facula shines is big, and the pixel aperture factor that the low coverage facula shines is little, and received signal light is very strong on having avoided the pixel of low coverage facula, and the pixel takes place the saturation easily or produces the condition of piling up the effect, has balanced the reflected signal intensity of the measured object of the different distances that the collector received, has reduced the variation range of signal light intensity, has improved the range finding degree of accuracy.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

Fig. 1 is a schematic diagram of a distance measuring system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a collector according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of arrangement of a light shielding sheet and a pixel array of a collector according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of another arrangement of the pixel array of the collector according to an embodiment of the present invention.

Fig. 5 is a schematic view of another arrangement of the pixel array of the collector according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of an electronic device according to another embodiment of the present invention.

Detailed Description

In order to make the technical problem, technical scheme and beneficial effect that the embodiment of the present invention will solve more clearly understand, the following combines the drawings and embodiment, and goes forward the further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. The connection may be for fixation or for circuit connection.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the embodiments of the present invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.

Fig. 1 is a schematic diagram of a distance measuring system according to an embodiment of the present invention, where the distance measuring system 10 includes a transmitter 11, a collector 12, and a processing circuit 13 connected to the transmitter 11 and the collector 12, respectively. Wherein the emitter 11 is configured to emit a light beam 30 toward the target area 20, the light beam 30 being emitted into the target area space to illuminate the target object in the space; at least a portion of the transmitted beam 30 is reflected by the target area 20 to form a reflected beam 40, and at least a portion of the reflected beam 40 is received by the collector 12; the processing circuit 13 is connected to the emitter 11 and the collector 12, and synchronizes the trigger signals of the emitter 11 and the collector 12 to calculate the time required for the light beam to be received from emitting to reflecting, i.e. the flight time t between the emitted light beam 30 and the reflected light beam 40, and further, the distance D of the corresponding point on the target object can be calculated by the following formula:

D＝c·t/2 (1)

where c is the speed of light.

The transmitter 11 includes a light source 111, a transmitting optical element 112, a driver 113, and the like. The light source 111 may be a Light Emitting Diode (LED), a Laser Diode (LD), an Edge Emitting Laser (EEL), a Vertical Cavity Surface Emitting Laser (VCSEL), or the like, or may be a one-dimensional or two-dimensional light source array composed of a plurality of light sources. Preferably, the light source array is a VCSEL array light source chip formed by generating a plurality of VCSEL light sources on a single semiconductor substrate, and the arrangement of the light sources in the light source array may be regular or irregular. The light beam emitted by the light source 111 may be visible light, infrared light, ultraviolet light, or the like. The light source 111 emits a light beam outward under the control of the driver 113.

In one embodiment, the light source 111 emits a pulse light beam outwards under the control of the driver 113 at a certain frequency (pulse period), which can be used in Direct time of flight (Direct TOF) measurement, and the frequency is set according to the measurement distance, such as 1MHz-100MHz, which is several meters to several hundred meters. It will be appreciated that the light beam emitted by the light source 111 may also be controlled by a part of the processing circuitry 13 or a sub-circuit present independently of the processing circuitry 13. In one embodiment, the light source 111 emits an amplitude modulated continuous wave light beam, such as a sinusoidal or square wave continuous wave light beam, out under control of processing circuitry, which may be used in Indirect time of flight (infrared TOF) measurements.

The emission optical element 112 receives the light beam emitted from the light source 111 and projects the light beam to a target region after shaping. In one embodiment, the transmitting optical element 112 receives the pulsed light beam from the light source 111 and optically modulates, such as diffracting, refracting, reflecting, etc., the pulsed light beam, and then transmits the modulated light beam, such as a focused light beam, a flood light beam, a structured light beam, etc., into space. The emitting optical element 112 may be in the form of one or more of a lens, a liquid crystal element, a diffractive optical element, a microlens array, a Metasurface (Metasurface) optical element, a mask, a mirror, a MEMS galvanometer, and the like.

Collector 12 includes pixel unit 121, filter unit 122, and receiving optical element 123; the receiving optical element 123 is configured to receive at least a portion of the light beam reflected by the target and guide the light beam to the pixel unit 121, and the filtering unit 122 is configured to filter out background light or stray light. The pixel unit 121 includes a two-dimensional pixel array composed of a plurality of pixels; in one embodiment, the pixel cells 121 are an array of pixels comprised of single photon avalanche photodiodes (SPADs) that can respond to incident single photons and output signals indicative of the arrival times of the received photons in response at each SPAD, with the collection of the weak optical signals and the calculation of the time of flight implemented using, for example, time-correlated single photon counting (TCSPC).

In general, a readout circuit including one or more of a signal amplifier, a time-to-digital converter (TDC), a digital-to-analog converter (ADC), and the like connected to the pixel unit 121 is also included. These circuits can be integrated with the pixels as part of the collector or as part of the processing circuit 13, and are hereinafter collectively referred to as part of the processing circuit 13.

The processing circuit 13 synchronizes the trigger signals of the emitter 11 and the collector 12, processes the photon signals of the pixel collected light beams, and calculates the distance information of the target to be measured based on the flight time of the reflected light beams. In one embodiment, the SPAD outputs a photon signal in response to an incident single photon, and the processing circuitry 13 receives the photon signal and performs signal processing to obtain the time of flight of the beam. In particular, the processing circuit 13 counts the number of collected photons to form successive time bins, which are joined together to form a statistical histogram to reproduce the time series of the reflected beam, and identifies the time of flight of the reflected beam from emission to reflection back to reception using peak matching and filtering detection. It will be appreciated that the processing circuit 13 may be a stand-alone dedicated circuit, such as a dedicated SOC chip, FPGA chip, ASIC chip, etc., or may comprise a general purpose processing circuit.

In some embodiments, the distance measurement system 10 further includes a memory for storing a pulse code program with which to control the excitation time, emission frequency, etc. of the light beam emitted by the light source 111.

In some embodiments, the distance measurement system 10 may further include a color camera, an infrared camera, an IMU, etc., and a combination thereof may implement more rich functions, such as 3D texture modeling, infrared face recognition, SLAM, etc.

Referring to fig. 2, fig. 2 is a schematic structural diagram of collector 12 according to an embodiment of the present invention. Collector 12 includes pixel unit 200; the pixel unit 200 comprises at least one macro-pixel 201, wherein each macro-pixel 201 comprises a plurality of pixels 202 with different aperture factors, and the pixels 202 are used for collecting light spots reflected by targets at different distances in a field of view; wherein, the long-distance light spot (the light spot reflected by the long-distance target) is incident on the pixel with large aperture factor, and the short-distance light spot (the light spot reflected by the short-distance target) is incident on the pixel with small aperture factor. Specifically, the pixels 202 with different aperture factors may be arranged regularly or irregularly, and are not limited in this embodiment of the invention. In one embodiment, as shown in fig. 4, the reflected light spot is incident on a combined pixel 204 (for example, 4 pixels constitute one combined pixel), and the aperture factor of each pixel in the combined pixel may be configured to be the same or different.

In one embodiment, the collector further comprises a readout circuit 300, the readout circuit 300 comprising a TDC circuit and a histogram processing circuit for processing the photon signals and outputting a histogram containing photon time-of-flight information.

Referring to fig. 3, in one embodiment, pixels having different aperture factors are implemented by providing a masking sheet 203. Specifically, collector 12 includes a pixel array and a plurality of shielding sheets 203; the pixel array is a two-dimensional pixel array formed by a plurality of pixels and used for sensing signal light reflected by a detected target object; the plurality of shielding sheets 203 are configured to have different aperture factors to limit the light entrance area of the pixel by shielding the pixel, reduce the light sensing area of the pixel, and limit the amount of light entering. As shown in fig. 3, the shielding sheet 203 is provided with an opening 2031, and the signal light reflected by the target object to be measured can be incident on the pixel 202 through the opening 2031; in the figure, white represents the opening of the shielding sheet, and one shielding sheet corresponds to one pixel. In the embodiment of the utility model, the opening of the shielding piece can not be adjusted; of course, in other embodiments, the opening of the shielding plate may be set to be adjustable, and the number of the shielding plates is less than or equal to the number of the pixels.

In some embodiments, the number of masking sheets and the number of pixels may be the same or different; such as: during long-distance measurement, most pixels do not need to be shielded, so the number of the shielding pieces can be different from the number of the pixels, and the number of the shielding pieces is less than the number of the pixels. It will be appreciated that in some embodiments, one masking strip may correspond to multiple pixels.

In some embodiments, the shielding sheet is various types of metal or nonmetal shielding media or coatings disposed on the pixels. The shape of the opening of the shielding sheet can be square, rectangle, circle, polygon or other irregular shapes. The number of the openings of the shielding sheet may be one or more, and the position of the opening is not limited to the central position, and correspondingly, the non-shielded portion of the pixel is not limited to the central position of the pixel.

In some embodiments, the pixels are designed to have adjustable photosensitive area size, and each pixel has a different aperture factor by adjusting the size of the photosensitive area of each pixel so that the size of the photosensitive area of each pixel is different. The aperture factor of the pixel can be any value between 0 and 1, when the aperture factor is 0, the area of a photosensitive area of the pixel is zero, the light incoming quantity is zero, and the pixel cannot acquire light spots; when the aperture factor is 1, the area of the photosensitive area of the pixel is not reduced and is the area of the photosensitive area of the pixel under the initial normal condition, and the area of the photosensitive area of the pixel is the largest and the light incoming quantity is the largest at this time, so that the pixel is allowed to acquire more optical signals. Pixels with different aperture factors may constitute the pixel array in any combination as long as the pixel array can adapt to the variation of signal light intensity with position.

It should be noted that, in the embodiment of the present invention, the pixel is realized to have different opening factors by adopting the shielding sheet or by designing the pixel, and in some other embodiments, the pixel can also be made to have different opening factors by other methods.

As shown in fig. 4 to 5, the pixels with different aperture factors may be any combination of positions as long as the combination can adapt to the change of the intensity of the signal light with the position, and the arrangement of the pixels may be regular or irregular. Fig. 4 is a regular arrangement manner, and the aperture factors of the pixels in the combined pixels are the same, the aperture factors of the pixels gradually decrease from left to right, and the pixels with different aperture factors sequentially collect light spots of long distance, medium distance and short distance. And FIG. 5 is an irregular form, and the aperture factors of the pixels in the pixels are different, and the aperture factor is an arbitrary value between 0 and 1.

In one embodiment, when emitter 11 emits a spot beam toward a subject, the spot beam is reflected by the subject, and the pixel elements in collector 12 direct the spot beam to corresponding pixels, wherein the imaging spot configured as a single spot beam is incident on a corresponding "combined pixel" of multiple pixels. A single blob corresponds to a single combined pixel 204 consisting of 4 pixels as shown in fig. 4. The size of the combined pixel 204 may be set according to practical situations, and includes at least one pixel. For off-axis scanning, due to the existence of parallax, the displacement of the light spot incident on the pixel when the measured object is far and near different times, generally, the light spot is shifted along the baseline direction, so that all the resultant pixels included in the shift of the light spot caused by the influence of parallax are combined into a macro-pixel by a pre-calibration method, and during ranging, all the pixels in the macro-pixel are turned on, so that the resultant pixels corresponding to the spots reflected by the object at different distances in the measuring range all fall into the macro-pixel area. And the number of the macro-pixels determines the number of sampling points of the collector for completing one frame measurement.

Referring to fig. 2, the readout circuit includes a TDC circuit and a histogram processing circuit for processing the photon signals to draw a histogram reflecting the waveform of the pulses emitted by the light source in the emitter; further, the flight time can also be calculated according to the histogram, and the result is finally output. The readout circuit may be composed of a single TDC circuit and a histogram processing circuit, or may be an array readout circuit composed of a plurality of TDC circuits and histogram processing circuits.

Referring to fig. 6, fig. 6 shows an electronic device according to another embodiment of the present invention, which may be a desktop device, a desktop-mounted device, a portable device, a wearable device, an in-vehicle device, a robot, or the like. In particular, the device may be a laptop or an electronic device to allow gesture recognition or biometric recognition. In other examples, the device may be a head-mounted device for identifying objects or hazards in the user's surroundings for safety, e.g., a virtual reality system that obstructs the user's vision of the environment, objects or hazards in the surroundings may be detected to provide the user with warnings about nearby objects or obstacles. In other examples, which may be a mixed reality system that mixes virtual information and images with the user's surroundings, objects or people in the user's environment may be detected to integrate virtual information with the physical environment and objects. In other examples, the device may be applied to the field of unmanned driving and the like. Referring to fig. 6, taking a mobile phone 400 as an example for explanation, the electronic device includes a housing 41, a screen 42, and the distance measuring system of the foregoing embodiment; the emitter and the collector of the distance measuring system are arranged on the same surface of the electronic equipment and used for emitting light beams to the target object, receiving the light beams reflected by the target object and forming electric signals.

It is to be understood that the foregoing is a more detailed description of the invention, and specific/preferred embodiments thereof are described, and it is not intended that the invention be limited to the specific embodiments disclosed. For those skilled in the art to which the invention pertains, a plurality of alternatives or modifications can be made to the described embodiments without departing from the concept of the invention, and these alternatives or modifications should be considered as belonging to the protection scope of the invention. In the description herein, references to the description of the term "one embodiment," "some embodiments," "preferred embodiments," "an example," "a specific example," or "some examples" or the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention.

In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. One of ordinary skill in the art will readily appreciate that the above-disclosed, presently existing or later to be developed, processes, machines, manufacture, compositions of matter, means, methods, or steps, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. A collector is characterized in that: the device comprises a pixel unit consisting of at least one macro-pixel, wherein each macro-pixel comprises a plurality of pixels with different aperture factors and is used for collecting light spots reflected by targets at different distances in a field of view; the opening factor is any value between 0 and 1; wherein the pixels with large aperture factor are configured to acquire far-distance light spots and the pixels with small aperture factor are configured to acquire near-distance light spots.

2. The collector of claim 1, wherein: the pixel is provided with a shielding piece so as to limit the light entering area of the pixel through the shielding piece and reduce the photosensitive area of the pixel.

3. The collector of claim 2, wherein: the shielding sheet is a metal or nonmetal shading medium or coating arranged on the pixels.

4. The collector of claim 2, wherein: each pixel corresponds to one of the shielding sheets, and the shielding sheets are configured to have different aperture factors.

5. The collector of claim 4, wherein: the shielding piece is provided with an opening, and signal light reflected by a detected target object is incident on the corresponding pixel through the opening.

6. The collector of claim 5, wherein: the shape of the opening of the shielding sheet can be square, rectangle, circle, polygon or other irregular shapes.

7. The collector of claim 5, wherein: the number of the openings of the shielding piece can be one or more.

8. The collector of claim 1, wherein: the pixels are set to be adjustable in photosensitive area size, and the photosensitive area size of each pixel is made to be different by adjusting the photosensitive area size of each pixel, so that the pixels have different aperture factors.

9. A distance measuring system characterized by: the device comprises a transmitter, a collector of any one of claims 1-8 and a processing circuit connected with the transmitter and the collector respectively; wherein the content of the first and second substances,

10. An electronic device, comprising: a housing, a screen, and the distance measuring system of claim 9; the emitter and the collector of the distance measuring system are arranged on the same surface of the electronic device and used for emitting light beams to a target object, receiving the light beams reflected by the target object and forming electric signals.