JP7310859B2 - Photodetector and rangefinder - Google Patents

Description

The present invention relates to photodetectors and ranging devices.

In recent years, the development of a distance measuring device called LIDAR (Light Detection And Ranging) for self-driving automobiles is progressing. In this LIDAR, when traveling at a vehicle speed of about 100 [km/h] per hour, it is necessary to accurately measure the distance to an object up to about 300 [m] for safety. Of Flight) method is the mainstream. In the direct TOF method, a coherent laser beam is emitted in the direction to be detected, the laser beam that has collided with an object and is reflected is made incident on a light receiving part such as a photodiode via a lens, and the time from emission to detection is measured. It is a method to measure the distance to an object from the speed of light and the speed of light. A distance measuring device using the direct TOF method is generally configured to mechanically rotate 360[°] in a horizontal plane and stack a plurality of measurement systems in the vertical direction.

However, conventional distance measuring devices have the problem that sufficient resolution cannot be obtained in the vertical direction because the number of measuring systems stacked in the vertical direction is limited due to their sizes. There was a problem that miniaturization of equipment becomes difficult when a large number of are stacked. Furthermore, there was a problem that the durability of the mechanical 360° rotation mechanism had to be ensured, and that the structure had to be constructed in consideration of earthquake resistance.

As a technique to solve the problems of longitudinal resolution and mechanical durability, we have developed a deflection array that transfers image information from the imaging optics to the detector for the purpose of significantly increasing the signal-to-noise ratio of the detector. A pixel that is input immediately before and is operated within a two-dimensional array corresponding to each point in the field of view is determined, reflected light from the pixel that is operated on is directed to the photodiode, and light is reflected from the pixel that is operated off. A photosensitive member or photodiode array comprising a two-dimensional array of photosensitive pixels, characterized in that it directs light onto a light absorbing plate spaced from the photodiode, resulting from a two-dimensional light deflection array. A configuration is disclosed in which the two-dimensional array of detected light is directly detected by a two-dimensional photodiode array (for example, Patent Document 1).

However, the technique described in Patent Document 1 requires a structure having a plurality of transistors or the like arranged directly under each pixel for writing captured image information, and it takes time to write the operation information of each pixel. Therefore, there is a problem that high-speed operation is difficult. In addition, since the two-dimensional reflected light obtained from the light deflection array is directly incident on the two-dimensional photodiode array, there is a problem that a large-sized high-performance photodiode array is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photodetector and a distance measuring device that can suppress an increase in size and can detect light at high speed.

In order to solve the above-described problems and achieve the object, the present invention provides a photodetector for detecting incident light, comprising: a light guide section for guiding the incident light; and a light-receiving unit including a plurality of light-receiving elements for detecting the incident light deflected by the deflecting unit, wherein the deflecting unit includes a plurality of light-receiving elements that deflect the incident light. A plurality of optical deflection element groups each including an optical deflection element are divided into a plurality of division units in the vertical direction and the horizontal direction, and the optical deflection element groups are divided into a plurality of division units in the respective division units. The deflection elements are electrically connected in parallel to each other, and the plurality of optical deflection elements included in the optical deflection element group perform deflection operations simultaneously by passive matrix driving, and the plurality of the optical deflection element groups and the incident light deflected by a predetermined light deflecting element in the light deflecting element group performing the deflecting operation is received by a predetermined light receiving element among the plurality of light receiving elements. When the incident light is received by an element, the incident light deflected by an optical deflection element different from the predetermined optical deflection element in the optical deflection element group is received by a light receiving element different from the predetermined light receiving element among the plurality of light receiving elements. It is characterized by being received by an element.

According to the present invention, it is possible to suppress an increase in size and to detect light at high speed.

FIG. 1 is a diagram illustrating a typical photodetector. FIG. 2 is a diagram showing an example of the configuration of a general photodetector. FIG. 3 is a diagram showing an example of the configuration of a conventional photodetector. FIG. 4 is a diagram schematically showing a cross section of an optical deflection element of the DMD. FIG. 5 is a diagram illustrating an example of the configuration of a photodetector according to the first embodiment; 6A and 6B are a top view and a cross-sectional view of the optical deflection element of the photodetector according to the first embodiment. FIG. 7 is a diagram for explaining detection areas configured in space. FIG. 8 is a diagram showing an example of the configuration of a distance measuring device according to the second embodiment. FIG. 9 is a diagram for explaining the correspondence between the detection area, the optical deflection array, and the light receiving array. FIG. 10 is a flowchart showing an example of the flow of ranging operation of the ranging device according to the second embodiment. FIG. 11 is a diagram showing an example of a timing chart showing the operation of changing the laser intensity in the distance measuring device according to the modification.

Embodiments of a photodetector and a distance measuring device according to the present invention will be described in detail below with reference to the drawings. In addition, the present invention is not limited by the following embodiments, and the constituent elements in the following embodiments can be easily conceived by those skilled in the art, substantially the same, and so-called equivalent ranges. is included. Furthermore, various omissions, replacements, changes and combinations of components can be made without departing from the gist of the following embodiments.

[Regarding conventional photodetectors]
FIG. 1 is a diagram illustrating a typical photodetector. FIG. 2 is a diagram showing an example of the configuration of a general photodetector. A typical detector configuration will be described with reference to FIGS. 1 and 2. FIG.

In FIG. 1, a distance measuring device 101 is a general distance measuring device, and objects 102 to 105 indicate objects existing in space and subject to distance measurement. A distance measuring device 101 is a device for measuring distances to external objects such as objects 102 to 105 . Distance measuring device 101 simultaneously or sequentially measures distances to objects 102 to 105 located at different distances.

As shown in FIG. 2, the distance measuring device 101 includes, for example, a laser light source 201, a shaping lens 202, a polygon mirror 203, a lens 204, an imaging lens 205, and a light receiver 206.

The laser light source 201 is a light source that emits near-infrared laser light, for example. The shaping lens 202 is a lens that shapes the laser light emitted from the laser light source 201 into coherent laser light. The polygon mirror 203 is a member that reflects the laser beam shaped by the shaping lens 202 so as to scan in the horizontal direction (for example, the range of 120[°] to 360[°]) and directs it toward the lens 204 . A lens 204 is a lens that emits the laser beam reflected by the polygon mirror 203 to the outside of the distance measuring device 101 . In this way, the laser light emitted from the lens 204 is reflected by an object existing in the outside world and enters the distance measuring device 101 as reflected light.

The imaging lens 205 is a lens that forms an image on the light receiver 206 with reflected light from an object that has entered from the outside world. The light receiver 206 is a member that simultaneously or sequentially detects reflected light that has passed through the imaging lens 205 . The distance measuring device 101 measures the distance to each object from the reflected light detected by the light receiver 206, and acquires three-dimensional information in the horizontal, vertical and depth directions.

The distance measuring device 101 as described above is desired to detect a wide range of distance measurement data with high resolution and at the highest possible speed, and is also desired to be small and inexpensive. However, it has the problem of becoming a large-scale device.

FIG. 3 is a diagram showing an example of the configuration of a conventional photodetector. FIG. 4 is a diagram schematically showing a cross section of an optical deflection element of the DMD. Next, the configuration of a conventional photodetector described in, for example, US Patent Application Publication No. 2017/0357000 will be described with reference to FIGS. 3 and 4. FIG.

The photodetector 101a is a device that receives and detects reflected light from external objects such as the objects 111 and 112 . The reflected light may be reflected light emitted from some laser light source, as shown in FIG. As shown in FIG. 3, the photodetector 101a includes an imaging lens 211, a DMD (Digital Micromirror Device) 212, an imaging lens 213, and a light receiver 214.

The imaging lens 211 is a lens that forms an image on the DMD 212 of reflected light from an object that has entered from the outside world. The DMD 212 is an optical deflection array in which a large number of movable minute mirrors (optical deflection elements 212a shown in FIG. 4) are two-dimensionally arranged on an integrated circuit substrate. The imaging lens 213 is a lens that forms an image on the light receiver 214 of the light reflected by the ON operation of the optical deflection element 212 a in the DMD 212 . The light receiver 214 is a photodiode array that detects the light that is reflected by the ON-operated light deflection element 212 a in the DMD 212 and that has passed through the imaging lens 213 . In order to measure the distance of a distant object, it is desirable to use an avalanche photodiode, which is suitable for measuring a small number of photons, as the light receiver 214 rather than a normal photodiode.

The photodetector 101a acquires image information of an external object immediately before detection by the DMD 212, and among the optical deflection elements 212a of the DMD 212, the optical deflection element 212a to be turned on and the optical deflection element 212a to be turned off. to determine. At this time, it is necessary to store information on the ON/OFF operation of each optical deflection element 212a. Then, the DMD 212 of the photodetector 101 a turns ON only the optical deflection element 212 a determined to be turned ON, and reflects the reflected light from the imaging lens 211 toward the imaging lens 213 . As a result, the photodetector 101a can improve the signal-to-noise ratio.

Here, the configuration of the optical deflection element 212a of the DMD 212 will be described with reference to FIG. The optical deflection element 212a has a mirror configuration section 301 and an SRAM (Static Random Access Memory) 302, as shown in FIG.

The mirror component 301 is layered on the SRAM 302 and has a structure in which the angle of the mirror member is changed by torsion beams. The SRAM 302 is, as described above, a storage section including P-type transistors, N-type transistors, multi-layer wiring, etc., for storing information on the ON/OFF operation of the light deflection element 212a. The light deflection element 212 a having such a configuration moves the mirror member of the mirror configuration section 301 according to the ON/OFF information stored in the SRAM 302 .

In the photodetector 101a as described above, the image information of the object in the external world is acquired immediately before detection by the DMD 212, and the optical deflection element 212a to be turned on is specified based on the image information. However, it is not always clear how to specify, for example, in the above-mentioned US Patent Application Publication No. 201/0357000. Further, in the photodetector 101a, image information must be read each time the distance measurement operation is performed, but the operation for coping with an unpredictable case such as being unable to acquire the image information is not clear. In addition, the photodetector 101a requires a structure having a plurality of transistors and the like arranged directly under each pixel of the DMD 212 for writing captured image information. becomes high, and it takes time to write the operation information of each pixel, which makes high-speed operation difficult. In addition, since the optical deflection element 212a is of a torsion beam type and is movable, a restoring force and residual vibration of the beam are generated in the displacement in the reflection direction. I have a problem. Further, since the distance measurement operation is performed after specifying the optical deflection element 212a to be turned on, the distance measurement data is obtained at a timing slightly shifted from the specified timing. There is also a problem that it can be obtained. In addition, since the two-dimensional reflected light obtained from the DMD 212 as a light deflection array is directly incident on the light receiver 214 as a two-dimensional photodiode array, there is a problem that a large-sized high-performance photodiode array is required. be.

The configuration and operation that can solve the above problems will be described below.

[First Embodiment]
(Structure of photodetector)
FIG. 5 is a diagram illustrating an example of the configuration of a photodetector according to the first embodiment; 6A and 6B are a top view and a cross-sectional view of the optical deflection element of the photodetector according to the first embodiment. The configuration of the photodetector 1 according to this embodiment will be described with reference to FIGS. 5 and 6. FIG.

As shown in FIG. 5, the photodetector 1 includes a lens 16 (light guide section), a light deflection array 17 (deflection section), a light absorption plate 18, an imaging lens 19, and a light receiving array 20 (light receiving section). and a controller 21 (an example of a generation unit).

The lens 16 is a lens that guides reflected light (detection light, incident light) from an object that has entered from a detection area in the external world and forms an image on the light deflection array 17 .

The optical deflection array 17 is an optical deflection array in which the optical deflection elements 17a shown in FIG. 6 are arranged two-dimensionally. The optical deflection array 17 forms a plurality of optical deflection element groups in which arbitrary optical deflection elements 17a of the plurality of optical deflection elements 17a are electrically connected to each other in parallel, and each optical deflection element constituting the optical deflection element group. As for 17a, optical deflection operations are simultaneously performed by passive matrix driving, and each optical deflection element group is caused to perform optical deflection operations simultaneously or sequentially as time elapses. The optical deflection element group is directly driven by an external signal (such as a signal from the controller 21) by passive matrix driving. As described above, when one of the optical deflection element groups of the optical deflection array 17 is turned on by passive matrix driving, the light reflected from the lens 16 and incident on the optical deflection elements 17a constituting the optical deflection element group is The light is reflected (deflected) by the optical deflection element 17 a as ON light directed toward the imaging lens 19 . Light reflected as ON light by each of the optical deflection elements 17a of the optical deflection device group that has been turned on is simultaneously detected by each light receiving element of the light receiving array 20. FIG. That is, when reflected light (incident light) reflected by a predetermined light deflecting element 17a in the light deflecting element group that is on is received by a predetermined light receiving element among the plurality of light receiving elements, the light deflection Reflected light (incident light) reflected by a light deflecting element 17a different from the light deflecting element 17a in the element group is received by a light receiving element different from the light receiving element among the plurality of light receiving elements. On the other hand, the reflected light from the lens 16 that has entered the optical deflection element 17a that constitutes the optical deflection element group that is in the OFF operation is reflected (deflected) by the optical deflection element 17a as OFF light that travels toward the light absorbing plate 18. be done. In such a configuration of the optical deflection array 17, by performing the optical deflection operation of the optical deflection element group simultaneously or sequentially with the passage of time, the same light receiving element in the light receiving array 20 can be used at different locations in the detection area. ON light based on the optical deflection operation of the corresponding optical deflection element 17a can be detected. In other words, the detection of a plurality of different locations on the same photosensitive element is performed sequentially, thereby improving the resolution of the detection area.

The light absorbing plate 18 is a member that absorbs light reflected as OFF light by the light deflection array 17 .

The imaging lens 19 is a lens that forms an image of the ON light reflected by the light deflection array 17 on the light receiving array 20 .

The light-receiving array 20 is a light-receiving array in which photodiodes serving as light-receiving elements for detecting (receiving) the ON light transmitted through the imaging lens 19 are two-dimensionally arranged. The light-receiving array 20 is composed of light-receiving elements that are sparse in number compared to the two-dimensionally arranged light deflecting elements 17 a in the light deflecting array 17 . Specifically, the light-receiving array 20 has a smaller number of light-receiving elements than the number of light deflecting elements 17a included in the light-deflecting array 17, and is divided into detection areas 500, which are areas detected by the photodetector 1 described later. It has the same number of light-receiving elements as the number of regions 501 formed. Details of the detection area 500 and the area 501 will be described later. With such a configuration of the light receiving array 20, the ON light reflected by the light deflection array 17 can be detected at the same time, and processing such as distance measurement can be performed at the same time. In addition, it is not limited to a photodiode, and may be composed of, for example, an avalanche photodiode (an example of a light receiving element). By using an avalanche photodiode, even a small number of photons can be accurately measured.

The controller 21 is a control device that controls the overall operation of the photodetector 1 . The controller 21, for example, executes the ON/OFF operation of the optical deflection element group by the optical deflection array 17, and measures the distance to the point of the object based on the ON light detection information detected by the light receiving array 20. , the distance information is used to perform processing such as generation of a 3D map (three-dimensional image).

Next, the details of the configuration of the optical deflection element 17a of the optical deflection array 17 will be described.

As shown in FIG. 6, the optical deflection element 17a includes a substrate 31, a wiring 32, an insulating film 33, a connection hole 34, electrodes 35a and 35b, a contact member 36, a fulcrum member 37, and a plate-shaped member. 38 , a post 39 and a hat-shaped member 40 . FIG. 6(b) is a cross-sectional view taken along the line A-A' in FIG. 6(a).

The substrate 31 is a plate-shaped member having a planar portion. As shown in FIG. 6A, the wirings 32 are a plurality of wirings formed of conductors arranged in parallel on the substrate 31 . As shown in FIG. 6B, the insulating film 33 is a film for insulating and protecting the wiring 32 arranged on the substrate 31 and planarizing it.

As shown in FIG. 6B, the connection hole 34 penetrates the insulating film 33 to electrically connect the electrode 35a and the arbitrary wiring 32, and electrically connect the electrode 35b and the arbitrary wiring 32. It is a member to be connected. The electrodes 35a and 35b are electrically connected to an arbitrary wiring 32 through the connection hole 34, thereby electrically connecting different optical deflection elements 17a. A group of optical deflection elements electrically connected in parallel is formed.

The electrodes 35 a and 35 b are electrodes arranged on the insulating film 33 so as to be symmetrical with respect to the fulcrum member 37 . As described above, the electrodes 35a and 35b are electrically connected to arbitrary wirings 32 through the connection holes 34, respectively.

As shown in FIG. 6B, the contact member 36 is a member arranged on the insulating film 33 on the side opposite to the electrodes 35a and 35b with respect to the fulcrum member 37, and when the plate-shaped member 38 is inclined, the contact member 36 It is a member to be contacted.

A plurality of fulcrum members 37 (two in the example of FIG. 6A) are arranged between the electrodes 35a and 35b on the planar portion of the substrate 31, and are arranged on the surface of the plate-shaped member 38 opposite to the reflecting surface. It is a member that comes into contact with the plate-shaped member 38 so as to move freely toward and away from it, and serves as a fulcrum for the tilting motion of the plate-shaped member 38 .

The plate-shaped member 38 is supported by the fulcrum member 37 so as to face the electrodes 35a and 35b so as to be freely contactable and detachable. It is a plate-shaped elastic member including a conductive region facing the electrodes 35a and 35b on at least a part of the surface in contact with the fulcrum member 37. As shown in FIG.

The pillars 39 are arranged on the planar portion of the substrate 31 and on the end side of the plate-shaped member 38 on the line connecting the fulcrums of the plurality of fulcrum members 37 in the direction of the line. It is a pillar-shaped portion that regulates the The cap-shaped member 40 is a cap-shaped member installed at the end of each of the columns 39 opposite to the substrate 31, and covers a part of the end of the plate-shaped member 38 in the above-described line direction to form a plate. It is a member that regulates the arrangement of the shape member 38 and prevents it from popping out. However, a gap is provided between the plate-shaped member 38 and the cap-shaped member 40 so that the plate-shaped member 38 can be freely tilted.

As described above, unlike the optical deflection element 212a shown in FIG. 4, the optical deflection element 17a does not have a portion corresponding to the SRAM 302 including transistors and the like, and has only a configuration corresponding to the mirror configuration portion 301. It's becoming Therefore, the optical deflection array 17 having the optical deflection elements 17a can be manufactured with a large reduction in manufacturing man-hours compared to the conventional DMD 212, and can be easily manufactured with a high yield.

Also, with the configuration of the light deflection element 17a as described above, the cold light deflection operation is performed in the direction of the arrow shown in FIG. 6(a). Specifically, the inclination angle of the plate-shaped member 38 is determined by contact with the fulcrum member 37, the contact member 36, and the cap-shaped member 40, and the inclination direction is determined by the voltage applied to the electrodes 35a and 35b. That is, the plate-shaped member 38 performs tilting operation so as to reflect the detection light as ON light, or changes the detection light as OFF light, as shown in FIG. Perform tilting motion so as to reflect as In this way, the optical deflection element 17a does not have the restoring force of the torsion beam unlike the optical deflection element 212a of the DMD 212 described above, so that the optical deflection operation can be performed at high speed.

(About detection area)
FIG. 7 is a diagram for explaining detection areas configured in space. A detection area of the external world detected by the photodetector 1 according to the present embodiment will be described with reference to FIG.

A detection area 500 shown in FIG. 7A is a two-dimensional representation of a detection area in space in the external world where the photodetector 1 can detect light for convenience. Therefore, although the reflection position of the light on the object in the depth direction of the detection area 500 differs depending on the distance of the object included in the detection area 500, for the sake of convenience, it will be described as being detected in the two-dimensional detection area 500. . Further, the detection area 500 is divided into a plurality of areas 501 as shown in FIG. For example, if the detection area 500 is divided into 800 areas 501, 20 in the vertical direction and 40 in the horizontal direction, the light receiving array 20 also has 20×40=800 light receiving elements. including.

FIG. 7B shows an enlarged view of the two lower right areas 501 in the detection area 500 . Detection points 502 included in each region 501 correspond to corresponding positions in the region 501 , and these detection points 502 correspond to respective optical deflection elements included in the same optical deflection element group in the optical deflection array 17 . It corresponds to element 17a. That is, the light deflection elements 17a that reflect the light incident on the photodetector 1 from the detection points 502 of the regions 501 are included in the same light deflection element group. Similarly, the detection points 503 included in each area 501 correspond to the corresponding positions in the area 501, and these detection points 503 are directed to another identical optical deflection element group in the optical deflection array 17. It corresponds to each included optical deflection element 17a. Therefore, if the area 501 is composed of 60×60=3600 detection points, the optical deflection array 17 is composed of 3600 optical deflection element groups. Therefore, the light deflection elements 17a included in the light deflection element group corresponding to the detection point 502 simultaneously perform the light deflection operation, so that the light corresponding to each detection point 502 is simultaneously deflected by each light receiving element of the light receiving array 20. will be detected. By sequentially driving different optical deflection element groups (for example, the optical deflection element group corresponding to the detection point 503), each detection point corresponding to the optical deflection element 17a included in the optical deflection element group is detected. Light is simultaneously detected at the photodetector array 20 .

With the above configuration, the number of divisions of the detection area 500, that is, the resolution of the light detected by the photodetector 1, is determined by the number of areas 501 constituting the detection area 500 (that is, the number of light receiving elements of the light receiving array 20). number) and the number of optical deflection element groups forming the optical deflection array 17 (that is, the number of detection points forming the region 501), which is 800×3600=2880000. That is, using a simple configuration of the light receiving array 20 that is sparse than the number of divisions of the detection area 500 (that is, the number of optical deflection elements 17a in the optical deflection array 17), each optical deflection element 17a constituting the optical deflection element group The optical deflection operation is performed simultaneously by passive matrix driving, and the optical deflection operation of each optical deflection element group is performed simultaneously or sequentially with the passage of time, thereby greatly improving the resolution. It is possible to provide a photodetector 1 with a

As described above, in the photodetector 1 according to the present embodiment, the lens 16 guides incident light, the optical deflection array 17 deflects the incident light guided by the lens 16, and the light receiving array 20 , a plurality of light receiving elements for detecting the incident light deflected by the light deflection array 17, the light deflection array 17 has a plurality of light deflection element groups including a plurality of light deflection elements 17a for deflecting the incident light, and the light The deflection element group is configured by electrically connecting a plurality of optical deflection elements 17a in parallel with each other. The optical deflecting element groups 17a and 17b perform deflection operations simultaneously or sequentially over time. When light is received by a predetermined light receiving element among the light receiving elements, the incident light deflected by the light deflecting element 17a different from the light deflecting element 17a in the light deflecting element group is directed to the light receiving element among the plurality of light receiving elements. is received by a light-receiving element different from the There is no need to stack multiple detectors in the vertical direction as in conventional measurement systems, and there is no need to store image information, so there is no need to input the image information. It is possible to suppress and detect light at high speed. Further, since a structure having a plurality of transistors or the like arranged directly under each pixel like the DMD 212 for writing image information is unnecessary, the structure can be made simple. Moreover, since a scanning system is not required, there is an advantage that it is hard to break. In addition, passive matrix driving eliminates the need for an external signal for driving each pixel, which simplifies the configuration of the controller. In addition, since a plurality of optical deflection elements 17a are connected in parallel and optical deflection operations are performed simultaneously, the number of pads for voltage application can be reduced.

In the photodetector 1 according to this embodiment, in the optical deflection element 17a, the substrate 31 has a planar portion, the plate-shaped member 38 has a deflection surface for deflecting incident light, and the fulcrum member 37 is protruding from the planar portion and serves as a fulcrum of the tilting motion of the plate-shaped member 38 so as to be able to come into contact with and separate from the surface of the plate-shaped member 38 opposite to the deflection surface. By regulating the arrangement of the member 38 and providing a gap between the plate-shaped member 38 and the plate-shaped member 38, the plate-shaped member 38 can be freely tilted. The plate-shaped member 38 includes conductive regions facing the plurality of electrodes 35a and 35b on the surface of the plate-shaped member 38 opposite to the reflecting surface. As a result, unlike the optical deflection element 212a of the DMD 212 described above, the torsion beam does not have a restoring force, so that the optical deflection operation can be performed at high speed.

Further, in the photodetector 1 according to the present embodiment, the number of light receiving elements included in the light receiving array 20 is smaller than the number of light deflecting elements 17a included in the light deflecting array 17 . Thereby, the resolution of the light detected by the photodetector 1 is equal to the product of the number of light deflection element groups included in the light deflection array 17 and the number of light receiving elements included in the light receiving array 20 . As a result, the number of detection points per unit time can be increased, detection can be performed over a wide range, and the resolution of light detected by the photodetector 1 can be improved.

[Second embodiment]
A distance measuring device according to the second embodiment will be described, centering on the differences from the photodetector 1 according to the first embodiment. In the first embodiment, the description has focused on the configuration as the photodetector 1 responsible for the light detection operation, instead of the configuration using a clear light source. In this embodiment, a specific configuration of a distance measuring device that has a light source that emits laser light and measures the distance to an object by using the reflected light of the laser light emitted from the light source that is reflected by the object. explain.

(Configuration of distance measuring device)
FIG. 8 is a diagram showing an example of the configuration of a distance measuring device according to the second embodiment. The configuration of the distance measuring device 1a according to this embodiment will be described with reference to FIG.

As shown in FIG. 8, the distance measuring device 1a includes a laser light source 11 (an example of a light source), a shaping lens 12, a prism lens 13, a lens 16 (light guide section), and an optical deflection array 17 (deflection section). , a light absorbing plate 18, a light absorbing plate 18, an imaging lens 19, a light receiving array 20 (light receiving unit), and a controller 21 (an example of a generating unit).

The laser light source 11 is a light source that emits, for example, near-infrared pulsed laser light. Note that, instead of the laser light source 11 that emits laser light, a light source that emits light such as an LED (Light Emitting Diode) may be used.

The shaping lens 12 is a lens that shapes the laser light emitted from the laser light source 11 into coherent laser light.

The prism lens 13 is an optical system member that refracts the laser light shaped by the shaping lens 12 and directs it to the light deflection array 17 . Also, the prism lens 13 transmits reflected light (detection light) that has returned from the detection area and is reflected by the light deflection array 17 and directs it toward the imaging lens 19 .

The lens 16 magnifies the laser light refracted by the prism lens 13 and reflected by the light deflection array 17 in the vertical and horizontal directions so that the laser light is directed to the detection area 500 in the external space where the rangefinder 1a measures the range. It is a lens that radiates light. Also, the lens 16 is a lens that guides reflected light (detection light, incident light) from an object that has entered from the detection area 500 and forms an image on the light deflection array 17 .

A detection area 500 shown in FIG. 8 is similar to the detection area 500 shown in FIG. 7A, and is represented two-dimensionally for convenience. Therefore, although the reflection position of the light on the object in the depth direction of the detection area 500 differs depending on the distance of the object included in the detection area 500, for the sake of convenience, it will be described as being detected in the two-dimensional detection area 500. . For example, the detection area 500 is divided into 800 areas 501, 20 vertically and 40 horizontally, and the light receiving array 20, which will be described later, includes 20×40=800 light receiving elements. correspond respectively to Assuming that the area 501 is composed of, for example, 60×60=3600 detection points as shown in FIG. has 2,880,000 pixels, 1200 in the vertical direction and 2400 in the horizontal direction. One pixel of each of these corresponds to one of the optical deflection elements 17 a that constitute the optical deflection array 17 . In this case, the laser light (radiation light) expanded and emitted from the lens 16 is reflected by the object included in each area 501, and the reflected light is returned along the same optical axis as the original laser light. The reflected light (detection light) is guided to the lens 16 and enters the light deflection element 17 a in the light deflection array 17 .

The optical deflection array 17 is an optical deflection array in which the optical deflection elements 17a shown in FIG. 6 are two-dimensionally arranged. The optical deflection array 17 forms a plurality of optical deflection element groups in which arbitrary optical deflection elements 17a of the plurality of optical deflection elements 17a are electrically connected to each other in parallel, and each optical deflection element constituting the optical deflection element group. As for 17a, optical deflection operations are simultaneously performed by passive matrix driving, and each optical deflection element group is caused to perform optical deflection operations simultaneously or sequentially as time elapses. The optical deflection element group is directly driven by an external signal (such as a signal from the controller 21) by passive matrix driving. In this way, by the ON operation by passive matrix driving of any one of the optical deflection element groups of the optical deflection array 17, the laser light from the laser light source 11 incident on the optical deflection elements 17a constituting the optical deflection element group is turned ON. Reflected (deflected) light is emitted to the detection area 500 through the lens 16, reflected from the object included in the detection area 500, and guided by the lens 16. The reflected light is reflected by the light deflection element 17a. , and passes through the prism lens 13 toward the imaging lens 19 . Light reflected by each of the light deflecting elements 17a of the light deflecting device group that has been turned on passes through the prism lens 13 and the imaging lens 19, and is simultaneously detected by each light receiving element of the light receiving array 20. Become. That is, when reflected light (incident light) reflected by a predetermined light deflecting element 17a in the light deflecting element group that is on is received by a predetermined light receiving element among the plurality of light receiving elements, the light deflection Reflected light (incident light) reflected by a light deflecting element 17a different from the light deflecting element 17a in the element group is received by a light receiving element different from the light receiving element among the plurality of light receiving elements. On the other hand, the laser beam incident on the optical deflection element 17a constituting the optical deflection element group in OFF operation is reflected (deflected) as OFF light directed toward the light absorption plate 18 . In such a configuration of the optical deflection array 17, by performing the optical deflection operation of the optical deflection element group simultaneously or sequentially with the passage of time, the same light receiving element in the light receiving array 20 can be used at different locations in the detection area. ON light based on the optical deflection operation of the corresponding optical deflection element 17a can be detected. In other words, the detection of a plurality of different locations on the same photosensitive element is performed sequentially, thereby improving the resolution of the detection area. The configuration of the optical deflection element 17a is the same as that of the first embodiment described above.

The light absorbing plate 18 is a member that absorbs light reflected as OFF light by the light deflection array 17 .

The imaging lens 19 is a lens that forms an image on the light receiving array 20 of the ON light reflected by the light deflection array 17 and transmitted through the prism lens 13 .

The light-receiving array 20 is a light-receiving array in which photodiodes serving as light-receiving elements for detecting (receiving) the ON light transmitted through the imaging lens 19 are two-dimensionally arranged. The light-receiving array 20 is composed of light-receiving elements that are sparse in number compared to the two-dimensionally arranged light deflecting elements 17 a in the light deflecting array 17 . Specifically, the light-receiving array 20 has a smaller number of light-receiving elements than the number of light deflecting elements 17a included in the light-deflecting array 17, and is divided into detection areas 500, which are areas detected by the distance measuring device 1a, which will be described later. It is composed of the same number of light receiving elements as the number of the regions 501 formed, for example, 800 light receiving elements, 20 in the vertical direction and 40 in the horizontal direction. With such a configuration of the light receiving array 20, the detection light reflected by the light deflection array 17 can be detected at the same time, and processing such as distance measurement can be performed at the same time. It should be noted that the light receiving element is not limited to a photodiode, and may be composed of an avalanche photodiode, a CCD (Charge-Coupled Device), or the like (an example of a light receiving element).

The controller 21 is a control device that controls the overall operation of the distance measuring device 1a. The controller 21 performs, for example, laser light emission operation by the laser light source 11, on/off operation of the light deflection element group by the light deflection array 17, and object detection information detected by the light receiving array 20. Measurement processing of the distance to a point, generation processing of a 3D map (three-dimensional image), and the like are executed.

When the lens 16, the light deflection array 17, the light absorbing plate 18, the image forming lens 19, the light receiving array 20, and the controller 21 are extracted from the distance measuring device 1a, incident light from the outside is sequentially detected. It can be regarded as an example of a photodetector, and the distance measuring device 1a itself can also be regarded as an example of a photodetector including the component.

(Relationship between detection area, light deflection array, and light receiving array)
FIG. 9 is a diagram for explaining the correspondence between the detection area, the optical deflection array, and the light receiving array. The correspondence between the detection area 500, the light deflection array 17 and the light receiving array 20 will be described with reference to FIG.

The detection area 500 shown in FIG. 9A is divided into 800 areas 501, 20 in the vertical direction and 40 in the horizontal direction, as described above. Assuming that the area 501 is composed of, for example, 60×60=3600 detection points as shown in FIG. has 2,880,000 pixels, 1200 in the vertical direction and 2400 in the horizontal direction.

Further, as shown in FIG. 9B, the optical deflection array 17 has, for example, a vertical length of 24 [mm] and a horizontal length of 48 [mm]. It is composed of a total of 2,880,000 optical deflection elements 17a, 1,200 in the vertical direction and 2,400 in the horizontal direction. That is, one pixel of each detection area 500 corresponds to one of the optical deflector elements 17 a that constitute the optical deflector array 17 . A group unit of the optical deflection elements 17 a in the optical deflection array 17 corresponding to the area 501 of the detection area 500 is defined as a division unit 170 . That is, the division unit 170 includes 60×60=3600 optical deflection elements 17a. Then, an optical deflection element group is formed in which the optical deflection elements 17a at corresponding positions in each divided unit 170 are electrically connected in parallel. That is, the optical deflection element group is formed by 800 optical deflection elements 17a electrically connected to each other. Also, since the division unit 170 includes 3600 optical deflection elements 17a, there are 3600 optical deflection element groups. Therefore, the 800 optical deflection elements 17a constituting the optical deflection element group perform optical deflection operations simultaneously by passive matrix driving, and the 3600 optical deflection element groups perform optical deflection operations simultaneously or sequentially as time elapses. I do. Here, focusing on one divisional unit 170, one of the 3600 optical deflection elements 17a included in the divisional unit 170 is an optical deflection element electrically connected in parallel in each of the other divisional units 170. 17a, the remaining 3599 pieces in the division unit 170 are turned off.

Further, as shown in FIG. 9C, the light receiving array 20 has, for example, a vertical length of 400 [μm] and a horizontal length of 800 [μm]. It is composed of a total of 800 light receiving elements 20a, 20 in the direction and 40 in the horizontal direction. That is, the light receiving array 20 is composed of the same number of light receiving elements 20 a as the number of divided areas 501 in the detection area 500 and the number of division units 170 in the light deflection array 17 . That is, the area 501 of the detection area 500, the division unit 170 of the light deflection array 17, and the light receiving element 20a of the light receiving array 20 are in a corresponding relationship.

With such a configuration of the detection region 500, the light deflection array 17, and the light receiving array 20, the laser light reflected by the reflection surface of the light deflection element 17a of the light deflection element group that has been turned on passes through the lens 16 as an ON light. The laser beams are simultaneously radiated toward the corresponding 800 detection points in the detection area 500 and reflected by the reflecting surfaces of the optical deflection elements 17a of the optical deflection element group that has turned off, and are directed toward the light absorption plate 18 as OFF light. Absorbed. When an object is present at one of 800 detection points in the detection area 500, the laser beam emitted from the distance measuring device 1a is reflected by the object, and part of the laser beam is converted into reflected light (detection light). (the optical axis of the laser beam). As a result, the influence of extraneous light such as sunlight can be suppressed, and noise can be reduced. The reflected light (detection light) that has returned passes through the lens 16, is reflected by the reflecting surface of each light deflection element 17a of the light deflection element group that is in the ON state, passes through the prism lens 13, and forms an image. The light is detected (received) by the light receiving array 20 via the lens 19 . As described above, the detection area 500 is a wide area of the outside world, but is condensed by the lens 16 and becomes 24 [mm] in the vertical direction and 48 [mm] in the horizontal direction in the light deflection array 17. The light is condensed by the image lens 19 and becomes 400 [μm] in the vertical direction and 800 [μm] in the horizontal direction at the light receiving array 20 .

For example, in the light deflection element group that has been turned on, the laser light reflected by the reflecting surface of the light deflection element 17a corresponding to the detection point 1002 shown in FIG. The light is incident on a point on the object at the detection point 1001 shown in FIG. 9(a). Then, part of the laser light reflected at the point on the object returns as reflected light (detection light) along the emission direction of the laser light (optical axis of the laser light). The returned reflected light (detection light) passes through the lens 16 and is reflected by the reflecting surface of each light deflection element 17 a corresponding to the detection point 1002 of the light deflection element group that is in the ON state. , and is detected (received) by the light-receiving element 20a including the detection point 1003 shown in FIG.

Therefore, while one optical deflection element group out of the 3600 optical deflection element groups is ON-operated, distance measurement is performed, and the remaining 3599 optical deflection element groups are also ON-operated in order, and Since the optical deflection element 17a is also required to perform distance measurement, a high-speed optical deflection operation is desired, but as described in detail with reference to FIG. . Although the amount of reflected light that returns along the radiation direction varies depending on the reflectance and unevenness of the object, the speed of light is constant because it is determined by the state of the field, and it returns along the radiation direction. The distance is calculated by the direct TOF method from the time to the point, and the role of the distance measuring device 1a is fulfilled. That is, each of the light receiving elements 20a of the light receiving array 20 is assigned to 800 areas 501, and distance measurement is performed at 800 points at the same time. Distance measurement is possible with a resolution of 10,000 pixels, and the resolution can be greatly improved.

Note that the resolution of the detection area 500, the size of the light deflection array 17, and the size of the light receiving array 20 are shown by way of example, and are not limited to the configurations described above, and may be changed according to design. is possible. That is, in the configuration shown in FIG. 9, the pixel pitch of the light deflection array 17 is 20 [μm], and the pixel pitch of the light receiving array 20 is also 20 [μm]. can be changed to the size of

(Flow of range finding operation of range finder)
FIG. 10 is a flowchart showing an example of the flow of ranging operation of the ranging device according to the second embodiment. The flow of the ranging operation of the ranging device 1a according to this embodiment will be described with reference to FIG.

<Step S11>
The laser light source 11 emits pulsed laser light such as infrared light under the control of the controller 21 . Laser light emitted from a laser light source 11 is shaped into coherent laser light by a shaping lens 12 . The laser beam shaped by the shaping lens 12 is refracted by the prism lens 13 and directed toward the light deflection array 17 . Then, the process proceeds to step S12.

<Step S12>
The laser light refracted by the prism lens 13 is incident on the light deflection array 17 . Then, the process proceeds to step S13.

<Step S13>
The optical deflection array 17 turns on a specific optical deflection element group by passive matrix driving according to the control by the controller 21, and deflects the incident laser light by the optical deflection element 17a included in the optical deflection element group. let it happen The laser light reflected (deflected) by the light deflection element 17a travels toward the lens 16 as ON light. Then, the process proceeds to step S14.

<Step S14>
The lens 16 expands the laser light reflected by the light deflection array 17 in the vertical and horizontal directions and radiates it to the detection area 500 in the external space where the rangefinder 1a measures the range. Then, step S15. Move to

<Step S15>
Laser light (radiation light) magnified and emitted from the lens 16 is reflected by objects included in each region 501 of the detection region 500 . Then, the process proceeds to step S16.

<Step S16>
Of the reflected light reflected by the object, the reflected light (detection light) that has returned along the same optical axis as the original laser light is guided to the lens 16, and is guided to each of the light deflection element groups that are on. The light is incident (imaged) on the optical deflection element 17a. Here, the extraneous light mixed in from different directions is not guided to the light receiving array 20 due to the difference in the optical axis, so detection with high sensitivity is possible. Then, the process proceeds to step S17.

<Step S17>
Reflected light (detection light) incident on each light deflecting element 17a in the light deflecting element group that is on is transmitted through the prism lens 13, is imaged on the light receiving array 20 by the imaging lens 19, and is imaged on the light receiving array 20. 20 is detected (received). Then, the process proceeds to step S18.

<Step S18>
In the controller 21, the laser light is emitted from the laser light source 11, reflected by each light deflection element 17a of the light deflection element group that is on, and detected as detection light by each of the corresponding light receiving elements 20a of the light receiving array 20. The distance to the point on the object corresponding to each of the optical deflection elements 17a is measured from the time and the speed of light. Then, the process proceeds to step S19.

<Step S19>
If distance measurement for all areas of the detection area 500, that is, distance measurement by all optical deflection element groups of the optical deflection array 17 is completed (step S19: Yes), the process proceeds to step S20, and if not completed (step S19: No), the process returns to step S13 in order to switch the ON operation to another optical deflection element group for which distance measurement has not yet been performed.

<Step S20>
The controller 21 generates a 3D map (three-dimensional image) using distance information to a point of an object based on detection information of the detected light detected by each light receiving element 20a of the light receiving array 20. FIG.

Through the flow of steps S1 to S20 described above, the distance measuring operation by the distance measuring device 1a is executed. That is, the configuration as a transmitter including the laser light source 11, the shaping lens 12, the prism lens 13, the light deflection array 17, the light absorption plate 18 and the lens 16, the lens 16, the light deflection array 17, the prism lens 13 and the imaging lens 19 , and the configuration as a receiver (photodetector) including the light receiving array 20, while synchronizing, range finding operation can be performed for all points in the external measurement space.

As described above, in the distance measuring device 1a according to the present embodiment, the laser light source 11 emits, for example, a laser beam, and each optical deflection element 17a in the optical deflection element group that is performing the deflection operation (ON operation) is The laser light from the laser light source 11 is deflected toward the lens 16, and the lens 16 magnifies the laser light from the laser light source 11 deflected by each light deflection element 17a in the light deflection element group performing the deflection operation. of the laser light reflected by the object and returned along the optical axis of the laser light is guided as incident light to each of the optical deflection elements 17a corresponding to the laser light. shine. As a result, there is no need to vertically stack a plurality of detectors serving as measurement systems as in the prior art, and there is no need to store image information. It is possible to suppress an increase in size and to detect light at high speed. In addition, the same effects as those of the photodetector 1 according to the first embodiment are obtained.

(Modification)
A distance measuring device 1a as an example of a photodetector according to a modification will be described, focusing on the points that are different from the distance measuring device 1a according to the present embodiment described above.

FIG. 11 is a diagram showing an example of a timing chart showing the operation of changing the laser intensity in the distance measuring device according to the modification. With reference to FIG. 11, the operation of changing the laser intensity for suppressing erroneous detection with other laser beams incident from the outside in the distance measuring device 1a according to this modified example will be described.

For example, when the distance measurement time for one point is 4 [μsec], assuming that the tilting operation of the optical deflection element 17a requires 1.5 [μsec], the remaining detection time is 2.5 [μsec]. It turns out that. For example, 2 [μsec] is sufficient for distance measurement up to 300 [m] ahead. There is a need to. In particular, when the distance measuring device 1a is mounted on a vehicle that automatically drives, for example, it is required to be able to suppress erroneous detection due to mixing with laser light from a distance measuring device mounted on another vehicle.

Therefore, the range finder 1a according to the present modification converts the laser light into nanosecond-level pulses and changes at least one of the intensity and the phase in the middle of the output, thereby radiating from the range finder 1a itself. erroneous detection is suppressed by discriminating whether it is a laser beam that has been emitted or another laser beam. For example, as shown by the pulse-shaped waveform indicated by the dotted line in FIG. A laser beam with varying laser intensity is emitted. As a result, the reflected light from the object with respect to such a laser beam also has a similar intensity ratio. When detecting light with a different intensity ratio, it can be determined that it is a different laser beam, so accurate distance measurement is possible.

Reference Signs List 1 photodetector 1a distance measuring device 11 laser light source 12 shaping lens 13 prism lens 16 lens 17 light deflection array 17a light deflection element 18 light absorption plate 19 imaging lens 20 light receiving array 20a light receiving element 21 controller 31 substrate 32 wiring 33 insulating film 34 Connection hole 35a, 35b Electrode 36 Contact member 37 Support member 38 Plate-shaped member 39 Column 40 Cap-shaped member 101 Rangefinder 101a Photodetector 102 to 105, 111, 112 Object 170 Division unit 201 Laser light source 202 Shaping lens 203 Polygon model Mirror 204 Lens 205 Imaging lens 206 Light receiver 211 Imaging lens 212 DMD
212a optical deflection element 213 imaging lens 214 light receiver 301 mirror structure 302 SRAM
500 detection area 501 area 502, 503 detection points 1001 to 1003 detection points

U.S. Patent Application Publication No. 2017/0357000

Claims (9)

A photodetector for detecting incident light,
a light guide section that guides the incident light;
a deflection section that deflects the incident light guided by the light guide section;
a light receiving section including a plurality of light receiving elements for detecting the incident light deflected by the deflection section;
with
The deflection unit has a plurality of optical deflection element groups including a plurality of optical deflection elements that deflect the incident light, and is divided into a plurality of division units in the vertical direction and the horizontal direction,
The optical deflection element group is configured by electrically connecting the optical deflection elements at corresponding positions in each of the divided units in parallel,
the plurality of optical deflection elements included in the optical deflection element group perform deflection operations simultaneously by passive matrix driving;
each of the plurality of optical deflection element groups sequentially performs the deflection operation with the lapse of time;
When the incident light deflected by a predetermined light deflecting element in the light deflecting element group performing the deflection operation is received by a predetermined light receiving element among the plurality of light receiving elements, in the light deflecting element group A photodetector in which the incident light deflected by an optical deflection element different from the predetermined optical deflection element is received by a light receiving element different from the predetermined light receiving element among the plurality of light receiving elements. The optical deflection element is
a substrate having a planar portion;
a plate-shaped member having a deflection surface that deflects the incident light;
a fulcrum member projecting from the planar portion and serving as a fulcrum of tilting motion of the plate-shaped member so as to freely come into contact with and separate from a surface of the plate-shaped member opposite to the deflection surface;
a shade-shaped member that regulates the arrangement of the plate-shaped member and allows the plate-shaped member to freely tilt by providing a gap between the plate-shaped member and the plate-shaped member;
a plurality of electrodes arranged symmetrically with respect to the fulcrum member on the planar portion;
with
2. The photodetector according to claim 1, wherein said plate-shaped member includes a conductive region facing said plurality of electrodes on said opposite surface. 3. The photodetector according to claim 2, wherein the deflection surface is a reflective surface. The photodetector according to any one of claims 1 to 3, wherein the number of said light receiving elements included in said light receiving section is smaller than the number of said light deflecting elements included in said deflecting section. 5. The photodetector according to claim 4, wherein the resolution of light detected by said photodetector is equal to the product of the number of said light deflecting element groups possessed by said deflecting section and the number of said light receiving elements possessed by said light receiving section. . 6. The photodetector according to claim 1, wherein the light receiving element is an avalanche photodiode. a light source emitting light;
a photodetector according to any one of claims 1 to 6;
with
each of the optical deflection elements in the optical deflection element group performing the deflection operation deflects light from the light source toward the light guide section;
The light guide section magnifies the light from the light source deflected by each of the light deflection elements in the light deflection element group performing the deflection operation, radiates the light to the outside, and reflects the light from an object. A distance measuring device that guides the reflected light returned along the optical axis of the light to each of the optical deflection elements corresponding to the light as the incident light. 8. The distance measuring apparatus according to claim 7, wherein said light source emits said light in a pulsed form, and changes at least one of intensity and phase during output. 9. The generating unit according to claim 7 or 8, further comprising a generating unit that generates a three-dimensional image based on a distance obtained from the time from when the light is emitted from the light source to when the light is detected by the light receiving unit. rangefinder.

Images