Light-receiving element, distance measuring device, and mobile device

Abstract

The present application relates to a light receiving element, a distance measuring device, and a mobile device. A light receiving element according to the present disclosure includes an image sensor array configured to receive laser light reflected by a target on a pixel-by-pixel basis, wherein the image sensor array includes a central portion and a peripheral portion, and wherein a resolution of the central portion is higher than a resolution of the peripheral portion.

Description

[0001] This application is a divisional application of the Chinese national phase application, filed on May 8, 2018, with international application number PCT / JP2018 / 017737 and entitled "Range Measuring Device and Mobile Equipment". The Chinese national phase application entered the national phase on November 1, 2019, with application number 201880029231.1 and entitled "Range Measuring Device and Mobile Equipment". Technical Field

[0002] This disclosure relates to a ranging device and a mobile device. Background Technology

[0003] The time-of-flight (TOF) method, used to measure the time elapsed before a laser beam emitted towards a target is reflected back from the target, is one of the well-known measurement methods used in ranging devices (sometimes referred to as ranging devices) for measuring distances to a target. For example, the light-receiving element that receives the reflected light from the target can be a sensor, where unit pixels (hereinafter also simply "pixels") are arranged in a two-dimensional array. Two-dimensional array sensors typically have a configuration where the individual pixels are arranged at uniform spacing (see, for example, Non-Patent Documents 1 and 2).

[0004] Non-Patent Document 1 discloses a laser scanning TOF sensor, wherein a two-dimensional array sensor is used as a light receiving element for scanning laser beams in the system. Furthermore, Non-Patent Document 2 discloses a flash lidar system, referred to as a flash LiDAR (light detection and ranging) system, which uses a surface illumination light source to illuminate a measurement target with laser light and receives reflected light from the measurement target via a two-dimensional array sensor (e.g., a camera).

[0005] List of cited references

[0006] Non-patent literature

[0007] Non-Patent Literature 1: Christiano Niclass et al., "Design and characterization of a 256x64-pixels single-photon imager in CMOS for a MEMS based laser scanning time-of-flight sensor," Optics Letters, Vol. 11864, No. 20, May 21, 2012.

[0008] Non-Patent Literature 2: "A 32x32 pixel FLASH laser radar system incorporating InGaAs PIN and APD detectors" by Dries, John C., Brian Miles, and Roger Stettner in the 2004 issue of Defense & Security - International Society for Optics and Photonics. Summary of the Invention

[0009] The problem to be solved by the present invention

[0010] Meanwhile, a typical example of a ranging device that does not use a two-dimensional array sensor as a light-receiving element is a ranging device that uses a scanning mechanism such as a rotating mirror to scan a laser and a single-pixel light-receiving element to receive the reflected light returning from the target. In the case of such a ranging device, the scanning mechanism is mechanical and has a large number of driving components. Therefore, the scanning mechanism is large and expensive, and has problems with long-term reliability. From this point of view, ranging devices using two-dimensional array sensors as light-receiving elements have been developed and are expected to be a future technology.

[0011] However, especially in conventional ranging devices using a two-dimensional array sensor as the light receiving element, the pixels of the two-dimensional array sensor are arranged at a uniform spacing. Therefore, the angle of incidence of reflected light incident on each pixel of the light receiving element is narrower both away from the center and closer to the periphery of the light receiving element. Simultaneously, the amount of reflected light incident on each pixel of the light receiving element also decreases with the solid angle formed by each corresponding pixel, and the sensitivity at the periphery of the light receiving element decreases accordingly. Thus, the sensitivity difference between the center and periphery of the light receiving element becomes larger. As a result, the measurable distance is shorter and the measurable viewing angle is correspondingly narrower at locations closer to the periphery of the light receiving element.

[0012] Therefore, the purpose of this disclosure is to provide a ranging device with a wide field of view for measurable distances and a mobile device including the ranging device.

[0013] Solution to the problem

[0014] To achieve the above objectives, the ranging device according to this disclosure includes:

[0015] A laser irradiation unit is used to irradiate and measure a target using a laser; and

[0016] The laser receiving unit includes a light receiving element that receives laser light reflected from the measurement target pixel by pixel.

[0017] The spacing between unit pixels of the light-receiving element varies depending on its position within the light-receiving pixel region.

[0018] Furthermore, the mobile device according to this disclosure for achieving the above-mentioned objectives is equipped with a ranging device, which includes:

[0019] A laser irradiation unit is used to irradiate and measure a target using a laser; and

[0020] The laser receiving unit includes a light receiving element that receives laser light reflected from the measurement target pixel by pixel.

[0021] The spacing between unit pixels of the light-receiving element varies depending on its position within the light-receiving pixel region.

[0022] The fact that the pixel spacing of a light-receiving element varies with its position within the light-receiving pixel region means that the pixel spacing is not uniform across the entire light-receiving pixel region. For example, the pixel spacing varies between the central and peripheral portions of the light-receiving element, or more specifically, the pixel spacing is wider at locations farther from the central portion and closer to the peripheral portion of the light-receiving element to reduce the sensitivity difference between the central and peripheral portions of the light-receiving element.

[0023] According to one aspect of this disclosure, a light receiving element is disclosed, comprising: an image sensor array configured to receive laser light reflected by a target pixel by pixel, wherein the image sensor array includes a central portion and a peripheral portion, wherein the resolution of the central portion is higher than the resolution of the peripheral portion.

[0024] The unit pixel of the light receiving element is composed of any number of adjacent sub-pixels among a plurality of sub-pixels, which are arranged at a constant spacing. The number of sub-pixels constituting the unit pixel increases as it moves away from the center and closer to the periphery.

[0025] The size of a unit pixel increases as it moves away from the center and closer to the periphery.

[0026] The image sensor array is a two-dimensional array arranged in two dimensions in a first direction and a second direction intersecting the first direction.

[0027] The central part is the area of ​​interest, and the outer part is the area surrounding the area of ​​interest.

[0028] According to one aspect of this disclosure, a ranging device is disclosed, comprising: a laser irradiation unit configured to irradiate a measurement target with a laser; and a laser receiving unit including the aforementioned light receiving element.

[0029] According to one aspect of this disclosure, a mobile device including a ranging device is disclosed, the ranging device comprising: a laser irradiation unit configured to irradiate a measuring target with a laser; and a laser receiving unit including the aforementioned light receiving element.

[0030] Effects of the present invention

[0031] According to this disclosure, the sensitivity difference between the central and peripheral portions of a light-receiving element can be reduced. Therefore, a wide viewing angle can be achieved for measurable distances. It should be noted that the effects of this disclosure are not limited to those described herein and may include any effects described in this specification. Furthermore, the beneficial effects described in this specification are merely examples, and the beneficial effects of this disclosure are not limited to them and may include additional effects. Attached Figure Description

[0032] Figure 1 A schematic configuration diagram of a ranging device according to an embodiment of the present disclosure is provided.

[0033] Figure 2 A block diagram illustrating the basic configuration of a ranging device according to an embodiment of the present disclosure.

[0034] Figure 3A This is a plan view of the pixel array in the light receiving element according to Reference Example 1.

[0035] Figure 3B This is a schematic diagram illustrating the angle of incidence of reflected light incident on each pixel in the case of a pixel array in a light receiving element according to Reference Example 1.

[0036] Figure 4 A schematic configuration diagram of a laser beam scanning rangefinder according to Reference Example 2 is shown.

[0037] Figure 5 This is a plan view of the pixel array in the light receiving element according to Example 1.

[0038] Figure 6 This is a schematic diagram illustrating the angle of incidence of reflected light incident on each pixel in the case of a pixel array in a light-receiving element according to Example 1.

[0039] Figure 7A This is a plan view (part 1) of the pixel array in the light receiving element according to Example 2.

[0040] Figure 7B This is a plan view (part 2) of the pixel array in the light receiving element according to Example 2.

[0041] Figure 8 This is a plan view of the pixel array in the light receiving element according to Example 3.

[0042] Figure 9A An exploded perspective view is shown schematically of the stacked structure of the laser receiving unit according to Example 4.

[0043] Figure 9B A schematic side view illustrating the connection relationship between a unit pixel and a circuit section in a laser receiving unit with a stacked structure according to Example 4.

[0044] Figure 10 This is a plan view of the pixel array in the light receiving element according to Example 5.

[0045] Figure 11 This is a schematic configuration diagram of the optical receiving element according to Example 6.

[0046] Figure 12 A schematic plan view of a car as an example of a mobile device of the present disclosure equipped with a range measuring device. Detailed Implementation

[0047] The following detailed description, with reference to the accompanying drawings, illustrates a mode for implementing the technology according to this disclosure (hereinafter referred to as "Embodiments"). The technology according to this disclosure is not limited to the Embodiments, and the various numerical values ​​used in the Embodiments are merely examples. In the following description, identical components or components having the same function are indicated by the same reference numerals and will not be described again. It should be noted that the description will proceed in the following order.

[0048] 1. General description of the ranging device and mobile device disclosed herein

[0049] 2. The ranging device according to the embodiment

[0050] 2-1. Refer to Example 1 (Example of uniform pixel spacing)

[0051] 2-2. Refer to Example 2 (An example of a laser beam scanning method using a one-dimensional array sensor)

[0052] 2-3. Example 1 (Example of a two-dimensional array sensor)

[0053] 2-4. Example 2 (Example of pixel spacing varying pixel by pixel)

[0054] 2-5. Example 3 (Example of pixel spacing varying block by block)

[0055] 2-6. Example 4 (Example case of laser receiving units with a stacked structure)

[0056] 2-7. Example 5 (Example case where a unit pixel is formed by multiple sub-pixels)

[0057] 3. Modification

[0058] 3-1. Modification 1

[0059] 3-2. Revision 2

[0060] 4. Mobile devices according to this disclosure

[0061] 4-1. Specific Example (Example of a mobile device being a car)

[0062] 5. Implement the configuration of this disclosure.

[0063] <Overview of the ranging device and mobile device according to this disclosure>

[0064] In the ranging device and mobile device according to this disclosure, the spacing between unit pixels can be wider in positions away from the center of the light-receiving element and closer to the periphery of the light-receiving element. In this case, the spacing between unit pixels can vary pixel by pixel. Alternatively, when multiple adjacent unit pixels form a block, the spacing between unit pixels can vary block by block.

[0065] In the ranging device and mobile device according to this disclosure, including the preferred configuration described above, the light receiving element can be a two-dimensional array sensor in which unit pixels are arranged two-dimensionally in a first direction and a second direction intersecting the first direction. In this case, the spacing between the unit pixels of the light receiving element can vary in at least one of the first and second directions.

[0066] Furthermore, in the ranging device and mobile device according to this disclosure, including the preferred configuration described above, the size of a unit pixel of the light-receiving element can vary depending on its position within the light-receiving pixel region. Here, the size of a unit pixel refers to the size of the light-receiving surface of a unit pixel.

[0067] Furthermore, in the ranging device and mobile device according to this disclosure, including the preferred configuration described above, the laser receiving unit may have a circuit section for a corresponding pixel, which processes the signal of the corresponding unit pixel of the light receiving element. In this case, a stacked structure is preferably formed, in which the unit pixel is formed on a first substrate, the circuit section is formed on a second substrate, and the first and second substrates are stacked on top of each other. Furthermore, when a stacked structure is used, the spacing of the unit pixels formed on the first substrate can be different from the spacing of the circuit sections formed on the second substrate.

[0068] Furthermore, in the ranging device and mobile device according to this disclosure, including the preferred configuration described above, the light receiving element can be formed with a plurality of sub-pixels arranged at a constant spacing, and each unit pixel can be formed with an appropriate number of adjacent sub-pixels. In this case, the spacing between unit pixels is determined by the spacing between the sub-pixels and the number of sub-pixels constituting the unit pixel.

[0069] Furthermore, in the ranging device and mobile device according to this disclosure, the laser illumination unit can illuminate the measurement target while scanning the laser at equal angular intervals. In this case, the unit pixels are preferably arranged in an array with a spacing corresponding to the equal angular interval of the laser. Additionally, the light-receiving surface of the light-receiving element is preferably curved relative to the optical axis of the laser-receiving unit.

[0070] <Distance measuring device according to an embodiment>

[0071] Figure 1 A schematic configuration diagram of a ranging device according to an embodiment of the present disclosure is provided. Figure 2 A block diagram illustrating the basic configuration of a ranging device according to an embodiment of the present disclosure.

[0072] The ranging device 1 according to an embodiment of the present disclosure employs the Time-of-Flight (TOF) method as a measurement method for measuring the distance to a target 10. The TOF method measures the time elapsed before a laser beam emitted towards the target 10 is reflected back by the target 10. To perform distance measurement using the TOF method, the ranging device 1 according to this embodiment includes a laser illumination unit 20, a laser receiving unit 30, and a control unit 40.

[0073] The laser illumination unit 20 includes a laser driver 21, a laser source 22, and a diffuser lens 23, and illuminates the measurement target 10 with laser light. The laser driver 21 drives the laser source 22 under the control of the control unit 40. The laser source 22 is formed, for example, by a semiconductor laser, and emits laser light when driven by the laser driver 21. The diffuser lens 23 scatters the laser light emitted from the laser source 22 and illuminates the surface of the measurement target 10 with laser light.

[0074] The laser receiving unit 30 includes a light-receiving lens 31, a light-receiving element 32, and a light-receiving circuit 33. Based on laser irradiation performed by the laser irradiation unit 20, the laser receiving unit 30 receives the reflected laser light from the target 10. The light-receiving lens 31 focuses the reflected laser light from the target 10 onto the light-receiving surface of the light-receiving element 32. The light-receiving element 32 receives the reflected laser light from the target 10 pixel by pixel through the light-receiving lens 31 and performs photoelectric conversion.

[0075] Under the control of the control unit 40, the light receiving circuit 33 receives the light receiving output from the light receiving element 32 to measure the time t elapsed before the laser emitted from the laser irradiation unit 20 toward the measurement target 10 is reflected by the measurement target 10 and returns. Here, L represents the distance to the measurement target 10, and c represents the speed of light. The distance L to the measurement target 10 can be determined according to the following formula:

[0076] L=(c×t) / 2

[0077] The control unit 40, for example, is formed by a central processing unit (CPU) and controls the laser irradiation unit 20 and the laser receiving unit 30. It should be noted that in the above example, the light receiving circuit 33 measures the time t elapsed before the laser emitted from the laser irradiation unit 20 toward the measurement target 10 is reflected by the measurement target 10 and returns. However, the measurement can be performed by the control unit 40.

[0078] The ranging device 1 with the above-described configuration of this embodiment is characterized in that the spacing between the unit pixels of the light receiving element 32 varies with its position within the light receiving pixel region. Here, "light receiving pixel region" refers to the region where unit pixels are provided to receive reflected laser light from the measurement target 10.

[0079] The light receiving element 32 can be either a two-dimensional array sensor (a so-called area sensor) that arranges unit pixels into a two-dimensional array, or a one-dimensional array sensor (a so-called line sensor) that linearly arranges unit pixels. By using a two-dimensional array sensor as the light receiving element 32, and by having the laser illumination unit 20 simultaneously measure each pixel through surface illumination, a distance image can be acquired as a dynamic image.

[0080] Meanwhile, the photoelectric conversion element per pixel can be a high-speed and high-sensitivity avalanche photodiode (APD), in which the photocurrent is multiplied by applying a reverse voltage to, for example, a single-photon avalanche diode (SPAD) that detects a single photon.

[0081] The fact that the pixel spacing of the light-receiving element 32 varies with its position within the light-receiving pixel region means that the pixel spacing is not uniform across the entire light-receiving pixel region. For example, the pixel spacing varies between the central and peripheral portions of the light-receiving element 32, or more specifically, the pixel spacing is wider at locations farther from the central portion and closer to the peripheral portion of the light-receiving element 32, in order to reduce the sensitivity difference between the central and peripheral portions of the light-receiving element 32. This arrangement allows for a wide viewing angle to be set for any measurable distance.

[0082] [Reference Example 1]

[0083] The pixel array in the light-receiving element of a conventional ranging device, which is uniform throughout the light-receiving pixel area according to the unit pixel spacing, will now be described as a reference example 1. Figure 3A This is a plan view of the pixel array in the light-receiving element according to Reference Example 1. Furthermore, Figure 3B This is a schematic diagram illustrating the angle of incidence of reflected light incident on each pixel in the case of a pixel array in a light receiving element according to Reference Example 1.

[0084] like Figure 3A As shown, in a two-dimensional array sensor in which multiple unit pixels 50 are arranged in a matrix in two dimensions, in the case of the pixel array in the light receiving element 32 according to Reference Example 1, the spacing (pixel spacing) of the unit pixels 50 is set to an equal interval p0 in the entire light receiving pixel area.

[0085] As described above, with uniform pixel spacing throughout the light-receiving pixel area, the incident angle of reflected light from the measuring target 10 into the light-receiving element 32 at each pixel 50 is narrower in the portion farther from the center of the light-receiving element 32 and closer to the periphery, such as from... Figure 3B This is self-evident. Meanwhile, when the reflective surface of the measurement target 10 is a flat surface, the optical path length of the reflected light from the measurement target 10 to each pixel 50 of the light receiving element 32 is greater in the portion farther from the center of the light receiving element 32 and closer to the periphery. Therefore, the amount of reflected light incident on each pixel 50 of the light receiving element 32 also decreases with the solid angle formed by each corresponding pixel 50, and the sensitivity at the periphery of the light receiving element 32 decreases accordingly.

[0086] As described above, the angular spacing of the reflected light incident on the light-receiving element 32 is governed by the pixel pitch of the light-receiving element 32, and therefore, there is a large sensitivity difference between the central and peripheral portions of the light-receiving element 32. Consequently, the measurable distance is shorter closer to the peripheral portion of the light-receiving element 32, and the measurable viewing angle is correspondingly narrower. Inevitably, the angular spacing of the reflected light incident on the light-receiving element 32 is governed by the pixel pitch of the light-receiving element 32, provided that the pixel pitch is uniform throughout the entire light-receiving pixel area. This applies regardless of whether the light-receiving element 32 is a two-dimensional array sensor or a one-dimensional array sensor.

[0087] For example, for purposes such as autonomous driving, ranging devices can be installed and used in automobiles. In this case, the ranging device (ranging system) requires a 360-degree field of view (imaging field of view). Even if the 360-degree field of view (FoV) is divided and shared by four ranging devices, at least a 90-degree or at least a 100-degree field of view (FoV) is required to reduce blind spots or ensure reasonable overlap.

[0088] In a light-receiving element 32 of a two-dimensional array sensor with uniform pixel spacing throughout the light-receiving pixel area, for example, if the ranging field of view (FoV) is 100 degrees, the angular spacing is 0.24 degrees in the central portion of the light-receiving element 32, but 0.11 degrees in the peripheral portion. As a result, the sensitivity is almost halved, and the sensitivity difference between the central and peripheral portions of the light-receiving element 32 is almost doubled.

[0089] [Reference Example 2]

[0090] Next, a laser beam scanning ranging device, which is the optical receiving element 32 of Reference Example 2, is described. Figure 4 A schematic configuration diagram of a laser beam scanning rangefinder according to Reference Example 2 is shown.

[0091] A laser beam scanning ranging device, for example, uses a beam scanning unit 24 to scan a laser beam (laser) emitted from a laser source 22, and the reflected beam from the target being measured is reflected by a mirror 25 and guided to a light receiving element 32. The beam scanning unit 24 includes a scanning mechanism comprising a rotating mirror and a microelectromechanical system (MEMS), a beam splitter that separates the reflected beam from the target being measured and guides the beam to the mirror 25, etc. In the case of the laser beam scanning method according to Reference Example 2, the light receiving element 32 is formed from a single pixel.

[0092] In this laser beam scanning ranging device, laser beam scanning is typically performed at equally spaced angular intervals (equiangular spacing), allowing data to be acquired at equal intervals in both the central and peripheral portions of the field of view. However, as a mechanical structure, the scanning mechanism is large and expensive, and suffers from long-term reliability issues. Furthermore, the need for nonlinear control to match the laser beam scanning interval with the laser beam emission timing based on the pixel spacing makes control extremely complex. In particular, in mechanical scanning mechanisms using rotating or vibrating elements such as rotating mirrors or MEMS, controlling the scanning angular velocity is even more difficult, thus making it challenging to obtain ranging devices with wide field of view for measurable distances.

[0093] Considering the problems of Reference Examples 1 and 2 above, this embodiment is designed to obtain a wide viewing angle for measurable distances. Specifically, in this embodiment, the spacing of the unit pixels 50 in the pixel array of the light receiving element 32 varies with their position in the light receiving pixel region. The light receiving element 32 can be a two-dimensional array sensor or a one-dimensional array sensor. Specific examples of the pixel array in the light receiving element 32 will be described below.

[0094] Example 1

[0095] Example 1 is an example of a two-dimensional array sensor where the light receiving element 32 is a light receiving element 32. Figure 5 This is a plan view of the pixel array in the light-receiving element according to Example 1. It should be noted that... Figure 5 In this diagram, each 50-unit planar shape is represented as a square. However, this shape does not necessarily have to be a square; it can be some other shape, such as a rectangle or a hexagon (honeycomb structure).

[0096] like Figure 5As shown, the light-receiving element 32 according to Example 1 is a two-dimensional array sensor in which a plurality of unit pixels 50 are arranged in a matrix in two dimensions. Furthermore, the pixel array causes the spacing (pixel pitch) of the unit pixels 50 to vary with their position within the light-receiving pixel region. Specifically, in the pixel array of the light-receiving element 32 according to Example 1, the angular spacing of the reflected light incident on the light-receiving element 32 is governed by the pixel pitch in the light-receiving element 32; therefore, the pixel pitch is changed so that the angle of incidence of the reflected light relative to each pixel 50 becomes a constant angle.

[0097] For example, in the light-receiving pixel region of the pixel array in the light-receiving element 32 according to Example 1, the pixel spacing is set such that p1 < p2 < p3, ..., p n-1 <p n Established, where p1, p2, p3, ..., p n-1 and p n This refers to the pixel spacing in the direction from the center portion toward the outer portion. That is, in the light-receiving pixel area of ​​the light-receiving element 32 according to Example 1, the pixel spacing in the pixel array gradually becomes wider in the direction from the center portion toward the outer portion, so that the incident angle of the reflected light relative to each pixel 50 becomes a constant angle.

[0098] As described above, in the light-receiving pixel region of the pixel array in the light-receiving element 32 according to Example 1, the pixel pitch varies (changes) pixel by pixel, making the incident angle of reflected light relative to each pixel 50 of the light-receiving element 32 a constant angle. As a result, the sensitivity difference between the central and peripheral portions of the light-receiving element 32 can be reduced. Therefore, a wide viewing angle can be achieved for measurable distances.

[0099] It should be noted that in Example 1, in the light-receiving element 32 forming a two-dimensional array sensor, the pixel pitch varies in both the row direction (first direction) and the column direction (second direction). However, the pixel pitch does not necessarily have to vary in both directions, and can vary in at least the row direction or the column direction. Furthermore, in the case of a configuration that changes the pixel pitch in both the row and column directions, the pixel pitch in the row direction and the pixel pitch in the column direction do not necessarily have to be the same (same pitch).

[0100] Furthermore, in Example 1, all unit pixels 50 have the same unit pixel size (light-receiving surface size). However, the size can be varied depending on the position within the light-receiving pixel region. The effect of setting different sizes for unit pixels 50 based on their position within the light-receiving pixel region will be described later in Example 2.

[0101] Now for reference Figure 6Describe the angle of incidence of reflected light incident on each pixel 50 in the pixel array of the light receiving element 32 according to Example 1. Figure 6 This is a schematic diagram illustrating the angle of incidence of reflected light incident on each pixel 50 in the pixel array in the light receiving element 32 according to Example 1.

[0102] Here, the focal length of the lens optical system in the laser receiving unit 30 is represented by f, the angular spacing (angular resolution) of the reflected light incident on each pixel 50 is represented by Δθ, and the pixel spacing is represented by Δp. It should be noted that in Figure 5 In this context, Δ is omitted from the pixel spacing. Furthermore, in... Figure 5 and Figure 6 In the image, the number of pixels at the center of the light receiving element 32 is x1, and the number of pixels at the farthest point is x. n .

[0103] The pixel pitch p1 of pixel x1 located at the center of light receiving element 32 is expressed as:

[0104] p1={tan(Δθ)-tan(0)}×f

[0105] The i-th pixel x i From the center pixel spacing p i Represented as:

[0106] p i ={tan(i×Δθ)-tan((i-1)×Δθ)}×f

[0107] The pixel pitch varies in the light-receiving pixel region to satisfy the above relationship. However, it is not necessary to form the pitch entirely based on the relationship expression, and the intended purpose can be achieved as long as the pixel array makes the pixel pitch at least wider in the portion (center) away from the center of the light-receiving element 32 and closer to the outer portion (farthest end).

[0108] Now, the pixel spacing settings in the pixel array of the light-receiving element 32 according to Example 1 will be specifically described with a digital example. For example, the necessary ranging field of view (FoV) is 100 degrees, the angular spacing Δθ is 0.2 degrees, and the focal length f of the lens optical system is 17 mm. In this case, the pixel spacing p1 of the pixel x1 located at the center is expressed as:

[0109] p1 = (tan0.2 - tan0) × 17mm

[0110] ≈59μm. Furthermore, when n=250, the pixel pitch p of the furthest pixel xn is... n Represented as:

[0111] p n= (tan50 - tan49.8) × 17mm

[0112] ≈143μm

[0113] Example 2

[0114] Example 2 is an example of a pixel-by-pixel variation in the pixel pitch of the light-receiving element 32 forming a one-dimensional array sensor. Figure 7A This is a plan view (part 1) of the pixel array in the light receiving element 32 according to Example 2. Figure 7B This is a plan view (part 2) of the pixel array in the light-receiving element 32 according to Example 2. It should be noted that... Figure 7A and 7B In this diagram, each 50-unit planar shape is represented as a rectangle. However, this shape does not necessarily have to be a rectangle; it can be some other shape, such as a square or a hexagon.

[0115] For example, Figure 7A The pixel array shown is an example of a one-dimensional array sensor in which the unit pixels 50 of the light-receiving element 32 are arranged in two rows along the row direction. For example, Figure 7B The pixel array shown is an example of a one-dimensional array sensor in which the unit pixels 50 of the light receiving element 32 are arranged in two columns along the column direction.

[0116] In the pixel array of the light-receiving element 32 according to Example 2, the pixel spacing is changed, so that when forming a pixel array... Figure 7A and 7B In the light-receiving element 32 of the one-dimensional array sensor shown, the incident angle of the reflected light relative to the corresponding unit pixel 50 becomes a constant angle. For example, in the light-receiving pixel region, the pixel spacing is set such that p1 < p2 < p3, ..., p n-1 <p n Established, where p1, p2, p3, ..., p n-1 and p n This represents the pixel spacing in the direction from the center outwards.

[0117] As described above, in the light-receiving pixel region of the pixel array in the light-receiving element 32 according to Example 2, the pixel pitch varies (changes) pixel by pixel, making the incident angle of reflected light relative to each pixel 50 of the light-receiving element 32 a constant angle. As a result, the sensitivity difference between the central and peripheral portions of the light-receiving element 32 can be reduced. Therefore, a wide viewing angle can be achieved for measurable distances.

[0118] Furthermore, in the pixel array of the light-receiving element 32 according to Example 2, the size (light-receiving surface size) of a unit pixel 50 in the light-receiving element 32 varies with its position in the light-receiving pixel region. For example, in the formation of... Figure 7A In the case of the light-receiving element 32 of the one-dimensional array sensor shown, each pixel has the same size x in the column direction of the unit pixel 50, and the size in the row direction is set such that y1 <y2<y3、...、y n-1 <y n Established, where y1, y2, y3, ..., y n-1 and y n It indicates the dimension from the center part to the outer part in the row direction.

[0119] For example, in the formation of Figure 7B In the case of the light-receiving element 32 of the one-dimensional array sensor shown, each pixel has the same size x in the row direction of the unit pixel 50, and the size in the row direction is set such that y1 <y2<y3、...、y n-1 <y n Established, where y1, y2, y3, ..., y n-1 and y n This indicates the dimension from the center portion outwards along the column direction. That is, in... Figure 7A and Figure 7B In any of the cases shown, the size of the unit pixel 50 is set to become larger at positions further from the center of the light-receiving pixel area and closer to the periphery.

[0120] As described above, the optical path length of reflected light from the measurement target to each pixel 50 of the light receiving element 32 becomes longer in the portion farther from the center of the light receiving element 32 and closer to the periphery. Therefore, the amount of reflected light incident on each pixel 50 decreases with the solid angle formed by each corresponding pixel 50, and the sensitivity at the periphery of the light receiving element 32 decreases accordingly. Consequently, the sensitivity difference between the center and periphery of the light receiving element 32 becomes larger. As a result, the measurable distance is shorter closer to the periphery of the light receiving element 32, and the measurable viewing angle is correspondingly narrower.

[0121] On the other hand, in the pixel array of the light-receiving element 32 according to Example 2, the size of the unit pixel 50 is set to become larger in the central portion away from the light-receiving pixel area and closer to the periphery. With this arrangement, the optical path length of the reflected light from the measurement target to each pixel 50 of the light-receiving element 32 can compensate for the reduction in light quantity caused by the increased optical path length in the positions further away from the central portion and closer to the periphery of the light-receiving element 32. Therefore, the sensitivity difference between the central and peripheral portions of the light-receiving element 32 can be reduced.

[0122] When setting the size of unit pixel 50 to become larger at locations farther from the center and closer to the periphery, it is preferable to set the size of each pixel according to the degree of change in the length of the reflected light path, which is longer at locations farther from the center of the light receiving element 32 and closer to the periphery.

[0123] Example 3

[0124] Example 3 is an example of a block-by-block variation in the pixel pitch of the light-receiving element 32 forming a one-dimensional array sensor. Figure 8 This is a plan view of the pixel array in the light-receiving element 32 according to Example 3. It should be noted that... Figure 8 In this diagram, each 50-unit planar shape is represented as a rectangle. However, this shape does not necessarily have to be a rectangle; it can be some other shape, such as a square or a hexagon.

[0125] For example, the pixel array in the light-receiving element 32 of Example 3 is an example of a one-dimensional array sensor, where the unit pixels 50 are arranged in two rows in the row direction. In such a one-dimensional array sensor, for example, an appropriate number of adjacent unit pixels 50, such as three unit pixels 50, form a block. Specifically, blocks 1, 2, 3, ... and m are formed in the direction from the central portion toward the peripheral portion, each block consisting of three unit pixels 50. In each block, the spacing (size in the row direction) between the three unit pixels 50 is the same.

[0126] Furthermore, in the pixel array of the light receiving element 32 according to Example 3, the pixel spacing is set such that p1 < p2, ..., p n-1 <p n It is valid, where p1 represents the pixel spacing in block 1, p2 represents the pixel spacing in block 2, and p m This represents the pixel spacing within block m. In other words, within the light-receiving pixel region, the pixel array causes the pixel spacing to widen block by block from the center outwards. In this case, the pixel size is larger further away from the center and closer to the periphery.

[0127] As described above, in the light-receiving pixel region of the pixel array in the light-receiving element 32 according to Example 3, the pixel spacing varies (changes) block by block, making the incident angle of reflected light relative to each pixel 50 of the light-receiving element 32 a constant angle. As a result, the sensitivity difference between the central and peripheral portions of the light-receiving element 32 can be reduced. Therefore, a wide viewing angle can be achieved for measurable distances.

[0128] It should be noted that the example described is a one-dimensional array sensor with unit pixels 50 arranged in two rows in the row direction. However, for example, a one-dimensional array sensor with unit pixels 50 arranged in two columns in the column direction can achieve similar functions and effects as described above, provided that the one-dimensional array sensor has a similar basic configuration as described above.

[0129] Example 4

[0130] Example 4 shows an example of a laser receiving unit 30 of the ranging device 1 according to this embodiment having a stacked structure. Figure 9A An exploded perspective view of a laser receiving unit 30 with a stacked structure according to Example 4. Figure 9B The connection relationship between the unit pixel and the circuit section in the laser receiving unit with a stacked structure according to Example 4 is shown.

[0131] like Figure 7A As shown, the laser receiving unit 30 of the ranging device 1 according to this embodiment has a stacked structure, wherein a light receiving element 32 is formed on a first substrate 61, a light receiving circuit 33 is formed on a second substrate 62, and the first substrate 61 and the second substrate 62 are stacked on top of each other. More specifically, a unit pixel 50 of the light receiving element 32 is formed on the first substrate 61. The light receiving circuit 33 includes a circuit section 331 for processing the signal of the corresponding unit pixel 50 of the light receiving element 32 for the corresponding pixel, and each circuit section 331 of the light receiving circuit 33 has an almost identical circuit size and is formed on the second substrate 62.

[0132] Here, in the case where unit pixels 50 are arranged two-dimensionally at equal intervals over the entire light-receiving pixel area on the first substrate 61 (see...), Figure 3A The individual circuit sections 331 of the light receiving circuit 33 are also arranged in a two-dimensional manner at equal intervals on the second substrate 62 stacked on the first substrate 61, according to the corresponding unit pixel 50. With the help of this stacked structure of the laser receiving unit 30, the signals of the corresponding unit pixels 50 irradiated by the surface irradiation performed by the laser irradiation unit 20 can be read by the individual circuit sections 331 of the light receiving circuit 33 at the same time, and then processed.

[0133] In the stacking structure according to Example 4, for example, in the case where the pixel pitch and pixel size of the unit pixel 50 are changed pixel by pixel as in Example 2 (see...) Figure 7A and 7B ), so that each circuit section 331 of the optical receiving circuit 33 has substantially the same circuit size, and as Figure 9B As shown, the spacing of the circuit section 331 is changed only by connecting the wiring 332. This is a structure that can be formed because the laser receiving unit 30 has a stacked structure.

[0134] That is, in the stacked structure according to Example 4, due to the stacked structure, the spacing of the unit pixels 50 formed on the first substrate 61 and the spacing 331 of the circuit portions formed on the second substrate 62 can be different from each other only through the connection of the wiring 332. As a result, even if the pixel spacing of the unit pixels 50 changes, the uniform circuit size of each circuit portion 331 of the light receiving circuit 33 can be maintained. Furthermore, each circuit portion 331 of the light receiving circuit 33 can be disposed on the second substrate 62 without being affected by the spacing of the unit pixels 50.

[0135] Example 5

[0136] Example 5 is an example case in which each unit pixel 50 in the light receiving element 32 formed by a one-dimensional array sensor is formed by multiple sub-pixels. Figure 10 This is a plan view of the pixel array in the light-receiving element 32 according to Example 5. It should be noted that... Figure 10 In this context, a planar shape of 50 pixels per unit is represented as a rectangle. However, this shape does not necessarily have to be a rectangle; it can be some other shape, such as a square or a hexagon.

[0137] For example, in the example of a one-dimensional array sensor, the pixel array in the light-receiving element 32 of Example 5 is used, wherein a plurality of sub-pixels 51 forming a unit pixel 50 are arranged in a row in the row direction (along the row direction) at a specific spacing p0. In this one-dimensional array sensor, each unit pixel 50 is formed with an appropriate number of sub-pixels 51 that are adjacent to each other among the plurality of sub-pixels 51. In this case, the appropriate number of sub-pixels 51 serve as a unit pixel 50, which is electrically connected in parallel with each other in the circuit section 331.

[0138] exist Figure 10In the example shown, in the light-receiving element 32 forming a one-dimensional array sensor, the number of sub-pixels 51 constituting a unit pixel 50 changes from 2 to 3 to 4 in the direction from the center portion toward the periphery,... Specifically, the unit pixel 501 at the center of the sensor is formed by two sub-pixels 51, the second unit pixel 502 at the center of the sensor is formed by three sub-pixels 51, and the third unit pixel 503 at the center of the sensor is formed by four sub-pixels 51, and so on.

[0139] In this arrangement, the spacing of unit pixels 50 is determined by the spacing p0 of sub-pixels 51 and the number of sub-pixels 51 constituting unit pixel 50. In the example above, the spacing (size in the row direction) p1 of unit pixels 501 is p0×2, the spacing p2 of unit pixels 502 is p0×3, the spacing p3 of unit pixels 503 is p0×3, and the spacing of other unit pixels is similar. In this way, the spacing of unit pixels is determined by the spacing p0 of sub-pixels 51 and the number of sub-pixels 51.

[0140] In the pixel array of the light-receiving element 32 according to Example 5, the size of the unit pixel 503 (the size of the light-receiving surface) and the spacing of the unit pixels 503 can be varied according to the spacing p0 of the sub-pixels 51 and the number of sub-pixels 51 constituting the unit pixel 50. Furthermore, in the light-receiving pixel region, the number of sub-pixels 51 constituting the unit pixel 50 is set such that the spacing and size of the unit pixels 50 become larger further away from the center and closer to the periphery. In this way, the sensitivity difference between the center and periphery of the light-receiving element 32 can be reduced, and therefore, a wide viewing angle can be obtained for a measurable distance.

[0141] It should be noted that the example described is a one-dimensional array sensor in which unit pixels 50 are arranged in a row in the row direction. However, for example, a one-dimensional array sensor in which unit pixels 50 are arranged in a column direction can achieve similar functions and effects as described above, provided that the one-dimensional array sensor has a similar basic configuration as described above.

[0142] <Edit>

[0143] Although the technology according to this disclosure has been described so far based on preferred examples, the technology according to this disclosure is not limited to those examples. The configuration and structure of the ranging device described in the above embodiments are merely examples and can be modified as appropriate.

[0144] [Modification 1]

[0145] For example, in each of the above examples, a ranging device having a laser source 22 as a surface light source has been described as an example. However, the technology according to this disclosure can also be applied to laser beam scanning ranging devices formed by MEMS, mirrors, optical phased arrays (OPA), etc. (see...) Figure 4 In the case of a laser beam scanning ranging device, laser beam scanning is performed at equal angular intervals (equally spaced angular intervals), therefore, the spacing array of unit pixels 50 preferably corresponds to equal angular intervals.

[0146] [Modification 2]

[0147] In addition, such as Figure 11 As shown, in a ranging device that simultaneously illuminates a target with a laser scanning laser at equal angular intervals, the light-receiving surface of the light-receiving element 32 can be bent relative to the optical axis O of the laser receiving unit 30, such that the spacing of the unit pixels 50 corresponds to the angular spacing of the laser. Using this arrangement, the variation in the spacing of the unit pixels 50 can be reduced. For example, the light-receiving surface of the light-receiving element 32 can be bent by bending the chip (substrate) of the light-receiving element 32.

[0148] <Mobile devices according to this disclosure>

[0149] The ranging device according to this disclosure can be installed and used in any kind of mobile device (such as automobiles, electric vehicles, hybrid vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, boats, robots, construction machinery or agricultural machinery (tractors)).

[0150] [Specific Example]

[0151] This article describes cars as a specific example of mobile devices. Figure 12 A schematic plan view of a car as an example of a mobile device of the present disclosure equipped with a range measuring device.

[0152] like Figure 12 As shown, for purposes such as autonomous driving, the vehicle 100 is equipped with ranging devices 1A, 1B, 1C, and 1B at a total of four locations, namely two front locations and two rear locations of the vehicle body 101. It should be noted that the locations and number of ranging devices 1 shown herein are merely examples, and this disclosure is not limited to these examples. In cases where the purpose is autonomous driving, a 360-degree field of view (imaging field of view) FoV is required; therefore, ranging devices 1A, 1B, 1C, and 1B divide and share the 360-degree field of view FoV.

[0153] Then, the distance measuring device 1A located at the front left side measures the distance to a vehicle traveling in front and to the left thereof, and measures the distance to an obstacle or the like existing in front and to the left thereof. The distance measuring device 1B located at the front right side measures the distance to a vehicle traveling in front and to the right thereof, and measures the distance to an obstacle or the like existing in front and to the right thereof.

[0154] The distance measuring device 1C located at the rear left side measures the distance to a vehicle traveling behind and to the left thereof, and measures the distance to an obstacle or the like existing behind and to the left thereof. The distance measuring device 1D located at the rear right side measures the distance to a vehicle traveling behind and to the right thereof, and measures the distance to an obstacle or the like existing behind and to the right thereof.

[0155] The distance measuring device 1 according to the present disclosure can be used as the distance measuring devices 1A, 1B, 1C and 1D. As described above, in the distance measuring device 1 according to the present disclosure, the pitch per unit pixel of the light receiving element varies depending on the position in the light receiving pixel region. As a result, the sensitivity difference between the central portion and the peripheral portion of the light receiving element can be reduced. Therefore, a wide field of view can be achieved for the measurable distance. Accordingly, since the distance measuring device 1 of the present disclosure is used as the distance measuring devices 1A, 1B, 1C and 1D in a vehicle 100 for automatic driving or the like, the distance to a nearby traveling vehicle and the distance to a nearby located obstacle or the like can be measured more accurately. This contributes to the construction of a safer automatic driving system and the like.

[0156] <Configuration for Implementing the Present Disclosure>

[0157] It should be noted that the present disclosure can also be implemented with the configuration described below.

[0158] <<A. Distance Measuring Device>>

[0159] [A-1] A distance measuring device, comprising:

[0160] a laser irradiation unit configured to irradiate a measurement target with laser; and

[0161] a laser receiving unit comprising a light receiving element that receives laser reflected by the measurement target pixel by pixel,

[0162] wherein a pitch per unit pixel of the light receiving element varies with a position in a light receiving pixel region.

[0163] [A-2] The distance measuring device according to [A-1],

[0164] wherein the pitch per unit pixel is wider at a position farther from a central portion of the light receiving element and closer to a peripheral portion thereof.

[0165]

A-3

A-1

A-2

[0166] The spacing between the unit pixels varies pixel by pixel.

[0167] [A-4] The ranging device according to [A-1] or [A-2],

[0168] When multiple adjacent unit pixels form a block, the spacing between the unit pixels changes block by block.

[0169]

A-5

A-2

A-4

[0170] Wherein, when the light receiving element is a two-dimensional array sensor in which the unit pixels are arranged in two dimensions in a first direction and a second direction intersecting the first direction,

[0171] The spacing between unit pixels of the light receiving element varies in at least one of the first and second directions.

[0172]

A-6

A-1

A-5

[0173] The size of a unit pixel of the light receiving element varies with its position in the light receiving pixel region.

[0174]

A-7

A-1

A-6

[0175] The laser receiving unit includes a circuit section for a corresponding pixel, which processes the signal of the corresponding unit pixel of the light receiving element.

[0176] The unit pixel is formed on the first substrate, and

[0177] The circuit portion is formed on a second substrate stacked on a first substrate.

[0178] [A-8] The ranging device according to [A-7]

[0179] The spacing between unit pixels formed on the first substrate is different from the spacing between circuit portions formed on the second substrate.

[0180] [A-9] The ranging device according to [A-1]

[0181] The light-receiving element is formed by a plurality of sub-pixels arranged at a constant spacing.

[0182] A unit pixel is formed by an appropriate number of sub-pixels that are adjacent to each other in a plurality of sub-pixels, and

[0183] The pitch of said unit pixels is determined by the pitch of sub-pixels and the number of sub-pixels constituting said unit pixels.

[0184] [A-10] The distance measuring device according to [A-1],

[0185] wherein said laser irradiation unit irradiates said measurement target while scanning laser at equal angular intervals, and

[0186] said unit pixels are arranged in an array at a pitch corresponding to the equal angular interval of laser.

[0187] [A-11] The distance measuring device according to [A-10],

[0188] wherein said light receiving element has a light receiving surface.

[0189] <<B. Mobile Device>>

[0190] [B-1] A mobile device equipped with a distance measuring device, said distance measuring device comprising:

[0191] a laser irradiation unit configured to irradiate a measurement target with laser; and

[0192] a laser receiving unit comprising a light receiving element that receives, pixel by pixel, laser reflected by said measurement target,

[0193] wherein the pitch of unit pixels of said light receiving element varies depending on the position in the light receiving pixel area.

[0194] [B-2] The mobile device according to [B-1],

[0195] wherein the pitch of said unit pixels becomes wider at positions farther from the central portion of said light receiving element and closer to the peripheral portion.

[0196] [B-3] The mobile device according to [B-1] or [B-2],

[0197] wherein the pitch of said unit pixels varies pixel by pixel.

[0198] [B-4] The mobile device according to [B-1] or [B-2],

[0199] wherein when a plurality of adjacent unit pixels form a block, the pitch of said unit pixels varies block by block.

[0200] [B-5] The mobile device according to any one of [B-2] to [B-4],

[0201] Wherein, when the light receiving element is a two-dimensional array sensor in which the unit pixels are arranged in two dimensions in a first direction and a second direction intersecting the first direction,

[0202] The spacing between unit pixels of the light receiving element varies in at least one of the first and second directions.

[0203] [B-6] The mobile device according to any one of [B-1] to [B-5]

[0204] The size of a unit pixel of the light receiving element varies with its position in the light receiving pixel region.

[0205] [B-7] The mobile device according to any one of [B-1] through [B-6],

[0206] The laser receiving unit includes a circuit section for a corresponding pixel, which processes the signal of the corresponding unit pixel of the light receiving element.

[0207] The unit pixel is formed on the first substrate, and

[0208] The circuit portion is formed on a second substrate stacked on a first substrate.

[0209] [B-8] The mobile device according to [B-7],

[0210] The spacing between unit pixels formed on the first substrate is different from the spacing between circuit portions formed on the second substrate.

[0211] [B-9] The mobile device according to [B-1],

[0212] The light-receiving element is formed by a plurality of sub-pixels arranged at a constant spacing.

[0213] A unit pixel is formed by an appropriate number of sub-pixels that are adjacent to each other in a plurality of sub-pixels, and

[0214] The spacing of a unit pixel is determined by the spacing of its sub-pixels and the number of sub-pixels that make up the unit pixel.

[0215] [B-10] The mobile device according to [B-1],

[0216] The laser irradiation unit irradiates the measurement target while scanning with lasers at equal angular intervals, and

[0217] The unit pixels are arranged in a spacing array corresponding to the equiangular spacing of the laser.

[0218] [B-11] The mobile device according to [B-10],

[0219] The light receiving element has a light receiving surface that is bent relative to the optical axis of the laser receiving unit.

[0220] List of reference numerals

[0221] 1 Distance measuring device

[0222] 10 Measurement Target

[0223] 20 laser irradiation units

[0224] 21 Laser Driver

[0225] 22 laser sources

[0226] 23 Diffuse Lens

[0227] 24-beam scanning unit

[0228] 25 Reflectors

[0229] 30 laser receiving units

[0230] 31. Light receiving lens

[0231] 32 Optical receiving element

[0232] 33 Optical Receiver Circuit

[0233] 40 Control Unit

[0234] 50 units of pixels

[0235] 51 subpixels

[0236] 61 First substrate

[0237] 62 Second substrate.

Claims

1. A light receiving element, comprising: An image sensor array is configured to receive laser light reflected from a target pixel by pixel. The image sensor array includes a central portion and a peripheral portion, wherein the resolution of the central portion is higher than that of the peripheral portion.

2. The optical receiving element according to claim 1, wherein, in, Each unit pixel of the light-receiving element is composed of any number of adjacent sub-pixels arranged at a constant spacing. The number of sub-pixels constituting the unit pixel increases as it moves away from the center portion and closer to the outer portion.

3. The optical receiving element according to claim 2, wherein, in, The size of the unit pixel increases as it moves away from the center and closer to the periphery.

4. The optical receiving element according to claim 1, wherein, in, The image sensor array is a two-dimensional array arranged in a first direction and a second direction intersecting the first direction.

5. The optical receiving element according to any one of claims 1 to 4, wherein, The central portion is the region of interest, and the outer portion is the region surrounding the region of interest.

6. A ranging device, comprising: The laser irradiation unit is configured to irradiate the measurement target with a laser. A laser receiving unit, comprising the optical receiving element according to claim 1.

7. A mobile device including a ranging device, the ranging device comprising: The laser irradiation unit is configured to irradiate the measurement target with a laser. as well as A laser receiving unit, comprising the optical receiving element according to claim 1.

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