CN112817002A

CN112817002A - Distance detection system and image acquisition module comprising same

Info

Publication number: CN112817002A
Application number: CN202110124782.XA
Authority: CN
Inventors: 雷述宇
Original assignee: Ningbo Abax Sensing Electronic Technology Co Ltd
Current assignee: Ningbo Abax Sensing Electronic Technology Co Ltd
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2021-05-18

Abstract

The invention discloses a distance detection system and an image acquisition module including the same, comprising a driving part of a light source emitting end, a return light receiving end, and a processing module, wherein the driving part is used to configure the emitting light source to output emitting light to illuminate the field of view, The receiving end includes a photosensitive unit group that receives the light signal returned by the detected object in the field of view, and also includes more than two sub-function modules with different functions, and the sub-function modules share at least a transmission bus with a bidirectional data transmission function. By adopting a shared bus design in the chip of the design receiving end of this scheme, the interface module is divided into multiple interfaces located in the sub-function modules, so that the number of on-chip wiring is greatly reduced, which saves the difficulty of research and development and maximizes the To reduce the interference problem between wiring harnesses caused by complex wiring.

Description

Distance detection system and image acquisition module comprising same

Technical Field

The present disclosure relates to the field of detection technologies, and in particular, to a distance detection system and an image acquisition module including the same.

Background

As a method of measuring a distance from an object in a scene, a time of flight (TOF) technique is developed. Such TOF technology can be applied in various fields such as the automotive industry, human-machine interfaces, games, robotics, security, and the like. Generally, the TOF technology works by illuminating a scene with modulated light emitted from a light source and observing reflected light reflected by an object in the scene, the whole detection system includes a receiving end for transmitting the modulated and demodulated reflected light to a receiving end for receiving the reflected light reflected by the detected object in the field of view, and the detection system can obtain phase shift of the detected object by integrating the modulated and demodulated reflected light over a period of time and by using different phase delay receiving schemes, and obtain final distance information of the detected object by using the corresponding relationship between the phase shift and the distance, or can perform tens of thousands of detections in a direct manner, and the detection unit is excited by bias high voltage during the detection process, so that the diode is reversely applied with high voltage, and thus the detection unit is in an avalanche state and can realize single photon level sensitivity by single photon excitation, the statistical relation between the trigger probability and the time is obtained through ten thousands of detections, so that the flight time result can be directly obtained, and further the distance information can be directly obtained.

In order to ensure that the detection system has a wider field of view while obtaining higher detection efficiency in the detection process in the existing detection system, an array-type receiving module is adopted at present, thousands of pixel units are available in the array-type receiving module, each pixel unit can be a diode of a charge-coupled semiconductor CCD or a complementary metal oxide semiconductor CMOS type, and the like, and the array-type receiving module is not limited to be formed by only the two types of diodes, the space occupied by the whole detection system is smaller and smaller at present, the integration level of the system is higher and higher, more and more functional modules are required, however, in order to ensure the detection field range and the detection result accuracy, the array-type detector module needs to be ensured to have enough area, so that the rationalization layout of different modules in the detection system is necessary, various factors such as wiring density, influence among wiring harnesses, area occupation ratio of diode arrays of the detection modules and the like need to be considered in the overall layout design, if any factor is not considered, the influence of small detection visual angle, insufficient resolution and mutual interference among the wiring harnesses is likely to be generated, so that the detection result interference of the detection system is likely to be large, the detection result drift phenomenon is serious, even the detection result is invalid, the distance of the detected object cannot be accurately indicated, and the like.

In the above analysis, a scheme is designed that can adapt to the problems of the existing high-integration requirement, such as the resolution of the field of view and the angle of the field of view, and also can ensure that the detection result obtained by the detection system is accurate and has no drift, and the like.

Disclosure of Invention

The present application is directed to provide a distance detection system and an image acquisition module including the same, so as to solve the technical problem of inaccurate distance result obtained by the detection system, such as drift, caused by unreasonable layout of modules inside the system, and the like, resulting in a serious problem that the system completely loses distance detection function in use.

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

the embodiment of the application provides a distance detection system in a first aspect, which comprises a driving part of a light source emitting end, a return light receiving end and a processing module, wherein the driving part is used for configuring the emitting light source to output emitted light to illuminate a field of view, the receiving end comprises a photosensitive unit group for receiving return light signals of an object to be detected in the field of view, and more than two sub-functional modules with different functions are further included, and the sub-functional modules at least share a transmission bus with a data bidirectional transmission function.

Optionally, the sub-functional modules further share a clock signal transmission line.

Optionally, each of the more than two sub-function modules includes a data sub-interface unit, and the sub-function modules are all connected to the transmission bus through the data sub-interface unit.

Optionally, the driving part comprises more than two driving sub-function modules with different functions, and the driving sub-function modules at least share a transmission bus with a data bidirectional transmission function.

Optionally, the driving sub-functional modules further share a clock signal transmission line.

Optionally, each of the more than two driver sub-function modules includes a data driver sub-interface unit, and the sub-function modules are all connected to the transmission bus through the data driver sub-interface unit.

Optionally, a transmission bus shared by the receiving terminal function modules and having a data bidirectional transmission function is directly or indirectly connected with a transmission bus shared by the driving module part driving sub-function modules.

Optionally, the driving part includes more than two sub-driving parts, and the more than two sub-driving parts and the receiving end use the same address code segment.

Optionally, the sub-function modules further share a sub-chip selection signal transmission line.

In a second aspect, the invention provides an image acquisition module using the distance detection system of the first aspect, further comprising a two-dimensional image acquisition module and a visible light driving module for illuminating a field of view, wherein the visible light driving module comprises at least two visible photon driving parts, and the at least two visible photon driving parts and the two-dimensional image acquisition module use the same address code segment.

The beneficial effect of this application is:

the distance detection system comprises a driving part of a light source transmitting end, a return light receiving end and a processing module, wherein the driving part is used for configuring the light source to output emitted light to illuminate a view field, the receiving end comprises a photosensitive unit group for receiving return light signals of detected objects in the view field, and more than two sub-function modules with different functions, the sub-function modules at least share a transmission bus with a data bidirectional transmission function, through the scheme of the invention, the return light receiving end internally comprises the sub-function modules with different functions, the number of module connecting lines in a chip is greatly reduced through sharing a read-write bidirectional data line between the sub-function modules, the complex wiring scene between the sub-function and an interface part in the process of connecting the sub-function and the interface part through a unified interface is avoided, and in order to ensure that the wiring does not interfere with each other, the wiring density is required to be ensured not to be too large, so that the requirement on wiring connection is particularly high on the whole, the scheme can quickly and accurately complete in-chip wiring, can realize the effect of no interference between module signals under a compact scale, and can realize the effects of expansion of functional modules and the like only by software improvement on a time sequence.

Drawings

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

FIG. 1 is a schematic diagram of a detection system provided in the prior art;

fig. 2 is a schematic diagram of an arrangement of functional modules at a receiving end provided in the prior art;

fig. 3 is a schematic layout diagram of a driving sub-functional module of a driving part provided in the prior art;

fig. 4 is a schematic diagram of an image acquisition module according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram illustrating a basic working principle of a receiving module and a driving module according to an embodiment of the present disclosure;

fig. 6 is a schematic diagram of a shared transmission line and a clock signal line in a receiving end chip according to an embodiment of the present disclosure;

fig. 7 is a schematic layout diagram of a receiving module and a driving portion according to an embodiment of the present disclosure;

fig. 8 is a schematic layout diagram of another receiving module and driving unit according to an embodiment of the present application.

Detailed Description

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

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

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

Fig. 1 is a schematic block diagram of a detection system according to an embodiment of the present disclosure. As shown in fig. 1, the detecting device includes: the light emitting module 110, the processing module 120, and the light receiving module 130 are described by taking ITOF ranging as an example, the light emitting module 110 includes, but is not limited to, a semiconductor laser, a solid-state laser, and may also include other types of lasers, when a semiconductor laser is used as a light source, a Vertical-cavity surface-emitting laser (VCSEL) or an edge-emitting semiconductor laser (EEL) may be used, which is only exemplary and not particularly limited herein, in the system of fig. 1, the driving portion 15 may drive the light source 11 to emit required emitted light in different modes, and a driving signal of the driving portion may be derived from the processing module 12 of the system. The light source 11 emits sine wave, square wave, triangular wave, etc., and in the ranging application, most of the laser light with a certain wavelength, such as 950nm infrared laser light (preferably near infrared laser light), the emitted light is projected into the field of view, the detected object 14 existing in the field of view can reflect the projected laser light to form the return light, the return light enters the detection system and is received by the receiving end 13, the receiving end can include a photoelectric conversion portion, such as an array type sensor composed of CMOS, CCD, etc., and can also include a plurality of lenses to form more than one image plane, that is, the receiving module includes more than one image plane, the photoelectric conversion portion of the receiving module is located at one of the image planes, and can receive and obtain 0 °, 90 °, 180 °, and 270 ° delayed received signals by the four-phase scheme, and the method of calculating the sine wave by using the four-phase distance scheme is exemplified here, the amplitude of the received signal is measured at four equidistant points (e.g. intervals of 90 ° or 1/4 λ):

the ratio of the difference between a1 and A3 to the difference between a2 and a4 is equal to the tangent of the phase angle. ArcTan is in fact a bivariate arctangent function, which can be mapped to the appropriate quadrant, defined as 0 ° or 180 ° when a2 ═ a4 and a1> A3 or A3> a1, respectively.

The distance to the target is determined by the following formula:

the distance measurement is carried out by determining the frequency of the emitted laser, where c is the speed of light,

is the phase angle (measured in radians) and f is the modulation frequency. The scheme can achieve the effect of detecting the distance of the detected object in the field of view, the scheme is called as a four-phase delay scheme to obtain a detection result, the receiving end 13 generates different information through photoelectric conversion, in some cases, a 0-degree and 180-degree two-phase scheme is used for obtaining the information of the detected object, three-phase schemes of 0 degrees, 120 degrees and 240 degrees are disclosed in documents to obtain target information, even a five-phase delay scheme is disclosed in documents.

The DTOF distance measurement principle is also relatively simple and clear, the light source 11 emits pulsed laser light with a certain pulse width, for example, in the order of a few nanoseconds, which is reflected by the detection target back to the array-type receiving end 13 in the avalanche state SPAD, which can be made into an avalanche photodiode when the avalanche photodiode SPAD operates in the known Geiger mode in the case where its breakdown voltage is exceeded, so as to detect the photocurrent in which a single incident photon can trigger an infinite amplification. SPAD imaging sensors are semiconductor photosensitive devices consisting of an array of SPAD regions fabricated on a silicon substrate. The SPAD region produces an output pulse when struck by a photon. The SPAD region has a pn junction that is reverse biased above the breakdown voltage so that a single photogenerated carrier can trigger an avalanche multiplication process, photon signals received by the image sensor can be processed using a matched circuit detection to count output pulses from the SPAD region within a time window, wherein tens of thousands of laser pulses can be emitted for a high confidence result, the detection unit obtains a statistical result, such that a more accurate distance can be obtained by processing the statistical result.

Fig. 2 is a schematic diagram of a receiving end in the prior art, which may include a photodiode array 230 for acquiring return light, sub-function modules with different functions are arranged around the array, and the different sub-function modules are indicated by

reference numbers

2201 and 2205, in the prior art, in order to ensure the uniformity of interfaces, a uniform interface module 210 is arranged around a diode array unit, the interface module includes sub-interfaces corresponding to the sub-function modules with different functions, in order to ensure that the different sub-function modules can accurately operate, read/write data lines need to be arranged, clock signal lines also need to be connected in order to ensure the normal distribution of timing, chip select signal lines also need to be arranged in part of protocols, and the sub-function modules may include but are not limited to the following modules, such as a PLL module, a power-on reset control module port, a BIAS module TOP BIAS module, and an MIPI TX transmission interface, a TDC time-to-digital conversion module, a LOGIC circuit module of LOGIC, a LVDS configuration monitoring module, etc., where the MIPI module includes 4LANE and a clock signal, and the MIPI module can operate on any one of LANE, and certainly can operate in a mode exceeding 2LANE, and its states include lp (low power) mode and hs (high speed) mode, and the signal frequencies in the two modes will not be the same, and can implement the functions of mirror signal function, flip function, truncation bit, etc., and its states are not limited, and the specific arrangement position of each sub-function module is not limited, but in the prior art, although the sub-interface unit (which may be SPI slave, but is not limited thereto) is configured in the unified interface module 210, it seems that the area of each sub-function module is small, however, the actual wiring will be very complex, and in order to ensure the wiring density, the saving of the actual occupied area is very limited, the wiring of each sub-function module consumes great time and energy, the wiring accuracy is also higher, and once a small ring section has a problem, the whole module cannot be normally used.

Fig. 3 is a schematic diagram of a driving module in the prior art, driving sub-function modules with different functions in each driving

part

3201 and 3205 are arranged at different positions of the driving part, an interface part 310 is arranged in an independent area to integrate connection interfaces of each driving sub-function module, each driving sub-function module includes different functions, because the driving module itself does not include a detection array of diodes, which does not need to consider the marginalized layout of the on-chip function modules, and can alleviate the problem of excessive wiring harness density caused by a large number of wires due to a large number of sub-function modules to a certain extent, however, for a driver driving module, the number of sub-function modules inside the driver driving module may reach tens of levels of 20, even 30, and so when the interfaces are uniformly arranged in an independent area, the area occupied by each sub-function module alone can be prevented from being slightly larger, however, since the number of sub-functional modules is large, the number of required wires is also large, the complexity of the wires is also very high, and once the wires are not reasonable or the wires have problems, the whole driving part will fail, which is similar to a part of sub-functional modules on the receiving end, but the driving part has its unique sub-functional module, which is not limited herein.

Fig. 4 is a schematic diagram of a system module with different functions provided by the present invention, wherein 41-44 represent different modules of the system module, for example, a camera module capable of obtaining different two-bit images, a plurality of cameras with different resolutions, such as two-shot, three-shot, four-shot, etc., a visible light such as a flash driving module and a TOF ranging module, and a laser light source driving module of the TOF ranging module, where the TOF distance detecting system of the present invention can be combined with a two-dimensional image sensor to form an image obtaining module, and is not limited herein.

Fig. 5 is a schematic diagram of an operating principle of an image acquisition module combined by multiple modules according to the present invention, where more than two receiving ends are illustrated, one of the receiving ends is a receiving end of a TOF range finding system, and the receiving end is in communication connection with at least two driving portions, where the receiving end and the at least two driving portions share the same code segment, for example, a signal includes a signal segment of 2+5+8+ …, where the information represented by the signal segment 2bit may be shared by the receiving end and the at least two driving portions, and the information 00 illustrated in fig. 5 represents the data information of the receiving end, and 01, 10, and 11 respectively correspond to different driving portions of the at least two driving portions, so that the case of the at least two driving portions is illustrated, and different emission modes may be required for different scenes are mainly considered, for example, the light source emitted in DTOF ranging can be set as four different sets of emitted light, and the high-resolution range detection result is obtained by synthesizing the return light information corresponding to the four different sets of emitted light, at this time, at least two driving portions are optimally selected, in other scenarios, for example, it is necessary to perform zonal emission to solve the problems of multipath or conflict between detection range and resolution, and at least two driving portions are also necessary, of course, it is necessary to have no less than two driving portions for the emission power of the light source, of course, only one driving portion and the receiving end may actually share the same address code segment, and the 5-bit information in the example may include the address signal of the sub-function module in the corresponding module, and 2-bit information may include the address signal of the sub-function module in⁵32 can discern 32 different sub-function module at most through the code segment of 5 bits, so design also can satisfy the requirement to different sub-function module quantity in the different modules, 8 bits can be corresponding to the different operating instruction execution in every submodule piece, this also leaves sufficient design space for the designer, can realize for example the MIPI sub-function module of aforesaid beforeThe functions of mirroring, turning over, bit truncation, and the like of the number, and the functions of selecting and using a clock signal of a 4LANE and/or MIPI self-function block, and the like, also not limited to the listed functions, certainly, the foremost end of the signals may also include 1-bit read/write identification subcode information, whether the section of communication data information is to be read or written information can be easily distinguished through setting of the bit value, a specific data bit may also be included after the code segment, and the communication signal segment may be composed of a plurality of 8-bit sub-segments, and the communication signal segment of the module in fig. 5 is not limited to be realized in this format, and may also be composed of other sub-code segments with different functions and composed of other bits. Further, the receiving end in fig. 5 may further include a two-dimensional image sensor corresponding to natural light, or may also be a receiving end with more than two double shots, three shots, four shots, and the like, and of course, the visible light receiving end and/or the receiving end of the distance detection system corresponding to the infrared laser may also be connected to only one driving portion, even two or more two-dimensional image receiving ends may be shared in a special scene, and this is also only exemplary and is not limited specifically.

Fig. 6 shows a design scheme of a receiving-side on-chip shared bus provided by the present invention, in which

sub-function modules

6201 and 6206 with different functions are disposed around the array active region 630 formed by diodes, an interface module formed by sub-interfaces in the prior art is eliminated, each sub-function module is disposed with a separate sub-interface unit, and a bus in the receiving-side on-chip may include a shared two-wire scheme in an IIC manner, i.e., share a data signal line and a clock signal line with a bidirectional data transmission function, or certainly include an SPI manner in which a three-wire scheme is shared, i.e., share a data signal line, a clock signal line and a chip select signal line with a bidirectional data transmission function, where the method is not limited to the two buses, and each function module in more than two sub-function modules included in the receiving side includes a data sub-interface unit, all the sub-function modules are connected to the transmission bus through the sub-interface units, so that only the bus needs to be arranged in the receiving end, and all the sub-function modules are connected to the bus in the simplest way, thereby meeting the requirements of on-chip wiring density and maximum reduction of wiring errors.

Fig. 7 is a schematic view of a scheme structure in which on-chip buses are adopted for both the receiving end and the driver driving portion provided by the present invention, fig. 7 is a scheme in which buses are shared in an SPI layout, where the left side may be a schematic view of the receiving end and the right side is a schematic view of the driving portion, and the buses of the receiving end and the driving portion are connected in a direct manner, but may also be connected in an indirect manner in actual use, for example, in a wireless manner, etc., the same receiving end and the driving portion system use the same chip selection signal, and the driving portion has two PADs for distinguishing different driving portions of the same bus; different receiving end driving part systems are distinguished through different chip selection signals, but the different receiving end driving part systems share a clock and a bidirectional data signal.

The functional modules in fig. 8 and fig. 7 may be similar, but the two-line communication of the IIC is used as a shared bus to implement the on-chip bus scheme of the receiver and the driver, and the details of the rest are not repeated.

It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

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

Claims

1. The distance detection system is characterized by comprising a driving part of a light source emitting end, a return light receiving end and a processing module, wherein the driving part is used for configuring the emitting light source to output emitting light to illuminate a visual field, the receiving end comprises a photosensitive unit group for receiving return light signals of detected objects in the visual field, and more than two sub-functional modules with different functions share at least a transmission bus with a data bidirectional transmission function.

2. The distance detection system of claim 1 wherein said sub-functional modules further share a clock signal transmission line.

3. The distance detection system of claim 1 wherein each of said more than two sub-functional modules comprises a data sub-interface unit through which said sub-functional modules are connected to said transmission bus.

4. The distance detecting system according to claim 1, wherein the driving section includes more than two driving sub-function modules having different functions, the driving sub-function modules sharing at least a transmission bus having a data bidirectional transmission function.

5. The distance detection system of claim 4 wherein said driver sub-function modules further share a clock signal transmission line.

6. The distance detection system of claim 4 wherein each of said more than two driver sub-function modules comprises a data driver sub-interface unit through which said sub-function modules are connected to said transmission bus.

7. The distance detecting system according to claim 4, wherein a transmission bus shared by the reception terminal function modules and having a data bidirectional transmission function is directly or indirectly connected to a transmission bus shared by the drive mode section drive sub-function modules.

8. The distance detection system of claim 1, wherein the driving part comprises more than two sub-driving parts, and the more than two sub-driving parts and the receiving end use the same address code segment.

9. The distance detection system of claim 1 wherein said sub-functional modules further share a sub-chip select signal transmission line.

10. An image acquisition module comprising the detection system of claim 8, further comprising a two-dimensional image acquisition module and a visible light driver module illuminating a field of view, said visible light driver module comprising no less than two visible photon drivers, said no less than two visible photon drivers and said two-dimensional image acquisition module using the same address code segment.