Light detection device and sheet

Abstract

The present technology relates to a light detection device and a sheet that can prevent dirt from adhering to the light detection device while limiting the impact on light detection. An imaging device comprises an imaging unit and a signal processing circuit as a light detection element that detects incident light. The imaging device also comprises a lens that controls light incident on the light detection element, and a surface part formed on the light-incidence side from the light detection element. The surface part is formed from a plurality of projections regularly arranged on a flat plate that transmits light. The present technology can be applied to, for example, an imaging device which comprises a CMOS image sensor or other imaging element, a lens, and a surface part, and which captures an image of a subject.

Description

Photodetector and sheet

[0001] The present technology relates to a light detection device and a sheet, and more particularly to a light detection device and a sheet that can prevent adhesion of dirt to the light detection device while suppressing the influence on light detection.

[0002] With the spread of automation through AI (Artificial Intelligence) and the Internet of Things (IoT), the use of autonomous photodetection devices, which are photodetection devices without direct human involvement, is increasing. Examples of autonomous photodetection devices include security cameras, unmanned cameras such as cameras for cash registers and AI payment machines in parking lots, and sensors for unmanned transportation means (unmanned mobility) such as drones and self-driving cars.

[0003] On the other hand, if dirt adheres to a photodetector, it may become unable to detect, may cause false detection, or may reduce detection accuracy. Therefore, it is important to remove dirt from the photodetector. In photodetector systems that require direct human intervention, humans can recognize the dirt and remove it by cleaning or other methods.

[0004] However, since dirt adhering to a stand-alone photodetector cannot be recognized and removed by humans, the stand-alone photodetector must either have a function to detect and remove the dirt by itself, or undergo periodic maintenance such as cleaning.

[0005] As a method for removing dirt from a stand-alone photodetector, for example, a method for removing dirt from an in-vehicle camera using a cleaning liquid has been devised (see, for example, Patent Documents 1 and 2).

[0006] However, the above-mentioned method requires a great deal of cost to remove the dirt, such as the power consumption of the cleaning liquid spray mechanism, the effort required to fill the cleaning liquid, the installation of a cleaning liquid spray nozzle near the vehicle-mounted camera, and the installation of various parts that make up the spray mechanism.

[0007] JP 2022-547672 A JP 2022-131226 A

[0008] As described above, it is not easy to remove dirt from a stand-alone optical detection device. Furthermore, dirt that is difficult to remove by cleaning or maintenance work may adhere to the optical detection device in the sea, making it difficult to perform long-term or continuous detection using the optical detection device.

[0009] Therefore, there is a demand for a method for preventing the adhesion of dirt to a light detection device while suppressing the influence on light detection, but at present, such a demand has not been fully met.

[0010] The present technology has been made in view of such circumstances, and makes it possible to prevent adhesion of dirt to a light detection device while suppressing the influence on light detection.

[0011] A photodetector according to a first aspect of the present technology includes a photodetector element that detects incident light, a light control unit that controls the light incident on the photodetector element, and a surface portion that is formed on the light incident side of the photodetector element, and the surface portion is a photodetector configured by regularly arranging a plurality of protrusions on a flat plate that transmits the light.

[0012] In a first aspect of the present technology, a light detection element that detects incident light, a light control unit that controls the light that is incident on the light detection element, and a surface portion that is formed on the light incident side of the light detection element, the surface portion being configured by a flat plate that transmits the light and has a plurality of protrusions that are regularly arranged on the flat plate.

[0013] The sheet of the second aspect of the present technology is a sheet formed on the light incident side of the light detection element of a light detection device that includes a light detection element that detects incident light and a light control unit that controls the light incident on the light detection element, and is composed of a flat plate that transmits the light and has multiple protrusions regularly arranged on it.

[0014] In a second aspect of the present technology, a photodetection device includes a photodetection element that detects incident light and a light control unit that controls the light incident on the photodetection element, and is configured by forming a flat plate that transmits the light on the incident side of the photodetection element and has a plurality of protrusions regularly arranged on the flat plate.

[0015] 1 is a diagram showing a configuration example of an imaging device that is a first embodiment of a light detection device to which the present technology is applied. FIG. 2 is a top view showing a first configuration example of a surface portion. FIG. 3 is a side view showing a configuration example of the protrusion portion of FIG. 2. FIG. 4 is a diagram explaining the relationship between the contact angle of a droplet and hydrophilicity or water repellency. FIG. 5 is a side view showing a second configuration example of a surface portion. FIG. 6 is a top view showing a third configuration example of a surface portion. FIG. 7 is a top view and a side view showing a fourth configuration example of a surface portion. FIG. 8 is a top view and a side view showing a fifth configuration example of a surface portion. FIG. 9 is a top view showing an arrangement example of protrusion portions. FIG. 10 is a top view showing a sixth configuration example of a surface portion. FIG. 11 is a diagram showing a configuration example of an imaging device that is a second embodiment of a light detection device to which the present technology is applied. FIG. 12 is a diagram showing an example of the configuration of a mask. FIG. 13 is a block diagram showing an example of the schematic configuration of a vehicle control system. FIG. 14 is an explanatory diagram showing an example of the installation position of an imaging unit.

[0016] Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described. The description will be made in the following order: 1. First embodiment (image pickup device with lens) 2. Second embodiment (image pickup device without lens) 3. Application example to a moving body

[0017] In the drawings referred to in the following description, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Furthermore, the drawings may include parts whose dimensional relationships and ratios differ from each other.

[0018] Furthermore, the definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical idea of ​​the present disclosure. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read, and if it is rotated 180 degrees and observed, up and down are read inverted.

[0019] 1. First Embodiment Configuration Example of Imaging Apparatus FIG. 1 is a diagram showing a configuration example of an imaging apparatus that is a first embodiment of a photodetector to which the present technology is applied.

[0020] 1 is a camera including, in order from the light incident side, a surface portion 11, a lens 12, an imaging portion 13, and a signal processing circuit 14. The imaging device 10 captures an image of a subject 20 and generates a captured image.

[0021] Specifically, the surface portion 11 is formed on the boundary surface between the imaging device 10 and the outside world. The surface portion 11 is configured by regularly arranging a plurality of protrusions on a flat plate that transmits light from the subject 20. Examples of materials for the surface portion 11 include transparent resins such as PVC (polyvinyl chloride), PP (polypropylene), PC (polycarbonate), and PS (polystyrene), and siloxane-based inorganic coatings (glass coatings). The materials of the flat plate and the protrusions of the surface portion 11 may be the same or different.

[0022] The lens 12 is a light control unit that controls light incident on the imaging unit 13 from the subject 20 via the surface unit 11 .

[0023] The imaging unit 13 and signal processing circuit 14 constitute an imaging element (photodetection element) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor that detects light incident through the lens 12. Specifically, the imaging unit 13 receives the light incident through the lens 12 and generates an electrical signal corresponding to the amount of received light as optical information. The imaging unit 13 supplies the electrical signal to the signal processing circuit 14. The signal processing circuit 14 performs predetermined signal processing based on the electrical signal supplied from the imaging unit 13 to generate a captured image.

[0024] The surface portion 11 and the lens 12 may be integrated. That is, the surface portion 11 may be formed on the incident side surface of the lens 12. The surface portion 11 may be configured in the form of a sheet or the like separate from the lens 12, and may be attached to the incident side surface of the lens 12.

[0025] <First Structural Example of Surface Portion> FIG. 2 is a top view showing a first structural example of the surface portion 11 in FIG.

[0026] In the surface portion 11 shown in Fig. 2, a plurality of light-shielding protrusions 32 are arranged at equal intervals in a two-dimensional lattice (matrix) on a light-transmitting flat plate 31. In the example shown in Fig. 2, the shape of the protrusions 32 is a cone, and the diameter of the circle at the base of the protrusions 32 is 10 µm. The horizontal (row direction) and vertical (column) spacing of the protrusions 32 is 25 µm.

[0027] <First Structural Example of Protrusion> FIG. 3 is a side view showing a structural example of the protrusion 32 of FIG.

[0028] 2 is conical as described above, the shape of the side of the protrusion 32 is triangular as shown in Fig. 3. The generatrix of the protrusion 32 is approximately the same as the diameter of the circle at the bottom of the protrusion 32. The flat plate 31 is light-transmitting, but the protrusion 32 has light-blocking properties, for example, by having a black light-blocking film applied to its surface.

[0029] Therefore, of the light incident on the surface portion 11, for example, light incident on an area 31a on the light incident side surface of the flat plate 31 where the protrusions 32 are not formed passes through the flat plate 31 and is incident on the imaging unit 13 via the lens 12. On the other hand, light incident on the protrusions 32 is absorbed by the protrusions 32 and is not refracted or reflected by the protrusions 32. Therefore, the light incident on the protrusions 32 does not enter the imaging unit 13 via the lens 12 and does not adversely affect the captured image.

[0030] Alternatively, the black light-shielding film may be applied only to the bottom surface of the protrusion 32 .

[0031] <Explanation of Relationship Between Contact Angle and Hydrophilicity or Water Repellency> FIG. 4 is a diagram illustrating the relationship between the contact angle of a droplet attached to a solid surface and hydrophilicity or water repellency.

[0032] As shown in Figure 4, at the intersection of the flat surface of a solid surface 52 on which a droplet 51, such as a water droplet, is attached and the contour curve of the droplet 51, the smaller the contact angle θ, which is the angle formed by the flat surface of the solid surface 52 and the contour of the droplet 51, the higher the hydrophilicity and the lower the water repellency. The larger the contact angle θ, the lower the hydrophilicity and the higher the water repellency. Hydrophilicity is the property of being wetted by droplets, and water repellency is the property of repelling droplets. Generally, a contact angle θ of 100 degrees or more is called water repellency, and a contact angle θ of 150 degrees or more is called super water repellency.

[0033] Here, when the surface tension of the droplet 51 is such that the droplet 51 completely adheres to the solid surface 52, if the solid surface 52 is rough, the projections that make up the rough surface amplify the surface tension of the droplet 51. In other words, the projections increase the contact angle θ. Therefore, when the solid surface 52 is rough, the contact angle θ ｒ can be expressed by the following approximate formula (1) using an effective contact area ratio r (r≧1). The effective contact area ratio r is the ratio of the surface area of ​​the solid surface 52 when the solid surface 52 is a rough surface to the floor area, which is the surface area of ​​the solid surface 52 when the solid surface 52 is a flat surface. In other words, the effective contact area ratio r represents the roughness of the solid surface 52.

[0034]

[0035] In equation (1), θ １ represents the contact angle of the droplet 51 when the solid surface 52 is flat. This approximation formula (1) is called the Wenzel formula. According to formula (1), the contact angle θ ｒ The larger the effective contact area ratio r, the larger the value of r. Therefore, maximizing water repellency means maximizing the effective contact area ratio r.

[0036] Therefore, in order to maximize the water repellency of the surface portion 11, it is sufficient to maximize the effective contact area ratio r of the surface portion 11. Effective contact area ratio r of the surface portion 11 Ｓ is expressed by the following equation (2).

[0037]

[0038] In equation (2), a is the radius of the base of the protrusion 32, b (b>a) is the length of the generatrix of the protrusion 32, and c (2a<c) is the horizontal and vertical spacing (pitch) of the protrusions 32, i.e., the horizontal and vertical spacing between the centers of each protrusion 32.

[0039] As shown in equation (2), the effective contact area ratio r Ｓ is the surface area c of the flat plate 31 on which one protrusion 32 is arranged. ２ its surface area c ２ and the sum of the side surface area πab of one protrusion 32 to obtain the area of ​​the bottom surface πa ２is the ratio of the area subtracted.

[0040] According to equation (2), the effective contact area ratio r Ｓ is expressed as a quadratic expression of a, a linear expression of b, and a quadratic expression of the reciprocal of c. According to equation (2), the longer the length b of the generatrix of the protrusion 32 is, and the closer the width 2a of the protrusion 32 is to the interval c, the smaller the effective contact area ratio r Ｓ Therefore, by making the angle of the apex of the cone of the protrusions 32 more acute and by making the spacing c of the protrusions 32 closer to the width 2a of the protrusions 32, the water repellency of the surface portion 11 can be improved. As a result, liquid droplets such as water droplets adhering to the surface portion 11 flow down from the surface portion 11 while retaining the dirt adhering to the surface portion 11.

[0041] However, if the protrusions 32 are too small compared to the droplets, the droplets will not be able to fully adhere to the surfaces of the protrusions 32 due to the surface tension of the droplets, and the surface area in contact with the droplets will not increase. Therefore, the minimum size of the protrusions 32 is set to be larger than the minimum size of the droplets. For example, the minimum size of a water droplet determined by surface tension under atmospheric pressure is approximately 1.3 μm. Therefore, the minimum size of the protrusions 32 is set to 0.1 to 1 μm under atmospheric pressure.

[0042] On the other hand, if the protrusions 32 are too large compared to the water droplets, the protrusions 32 do not function as a rough surface for the water droplets, but function as a flat surface. Therefore, the maximum size of the protrusions 32 is set to a level at which the protrusions 32 function as a rough surface for the water droplets.

[0043] As a result, the protrusions 32 are formed so that, for example, the height and width of the protrusions 32, more specifically, the sizes of the generatrix b and the diameter 2a of the base are approximately the same (for example, one is less than 10 times the other), and are several μm to several tens of μm under atmospheric pressure. When the height and width of the protrusions 32 are approximately the same, the protrusions 32 are easy to manufacture.

[0044] As described above, in order to improve water repellency, it is better for the spacing between the protrusions 32 to be small; however, because the protrusions 32 block light, if the spacing between the protrusions 32 is too small, sufficient light for imaging will not be incident on the imaging unit 13. The amount of light sufficient for imaging varies depending on the performance of the imaging element. Therefore, the spacing between the protrusions 32 is set based on the performance of the imaging element and the bottom area of ​​the protrusions 32, etc., so as to enable sufficient light for imaging to be incident on the imaging unit 13. As described above, there is a trade-off between the rectilinear light transmittance and water repellency of the surface portion 11.

[0045] <Second Structural Example of Surface Portion> FIG. 5 is a side view showing a second structural example of the surface portion 11. As shown in FIG.

[0046] In the surface portion 11 in Figure 5, parts corresponding to the surface portion 11 in Figure 3 are assigned the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on the parts that differ from the surface portion 11 in Figure 3. The surface portion 11 in Figure 5 differs from the surface portion 11 in Figure 3 in that the protrusions 32 are not coated with a black light-shielding film, and a black light-shielding portion 71 is formed in an area on the lens 12 side (lower side in Figure 5) that corresponds to an area 70 where the protrusions 32 are formed on the light incident side surface of the flat plate 31. Other than that, it is configured in the same way as the surface portion 11 in Figure 3.

[0047] 5 , the area 31a of the flat plate 31 where the protrusions 32 are not formed is light-transmitting, and the light-shielding area 71 corresponding to the area 70 where the protrusions 32 are formed is light-shielding. The size of the area of ​​the light-shielding area 71 is slightly larger than the bottom surface of the protrusions 32. The light-shielding area 71 absorbs light incident on the protrusions 32 and prevents it from passing through or being reflected by the light-shielding area 71. As a result, the light incident on the protrusions 32 does not enter the imaging unit 13 via the lens 12.

[0048] In addition, if the shape of the protrusion 32 is a cone or a triangular pyramid or the like that has a refractive index or reflection characteristics that prevent light passing through the protrusion 32 from entering the imaging unit 13 via the lens 12, it is not necessary to apply a light-shielding film to the protrusion 32 or to provide a light-shielding portion 71 on the flat plate 31.

[0049] The light-shielding portion 71 may be formed in a region on the light incident side of the flat plate 31 corresponding to the region 70. Instead of forming the light-shielding portion 71, a light-shielding film may be applied to a region on the surface of the flat plate 31 on the lens 12 side corresponding to the region 70.

[0050] <Third Structural Example of Surface Portion> FIG. 6 is a top view (bird's-eye view) showing a third structural example of the surface portion 11. As shown in FIG.

[0051] In FIG. 6, in order to simplify the drawing, only a part of the surface portion 11 is shown.

[0052] In the surface portion 11 of Fig. 6, parts corresponding to those in the surface portion 11 of Fig. 3 are given the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the surface portion 11 of Fig. 3. The surface portion 11 of Fig. 6 differs from the surface portion 11 of Fig. 3 in that it has a regular triangular pyramid-shaped protrusion 81 instead of the conical protrusion 32, but is otherwise configured in the same way as the surface portion 11 of Fig. 3.

[0053] In the example of Fig. 6A, the horizontal and vertical spacing between the protrusions 81 is the length of one side of the equilateral triangle at the base of the protrusions 81. In the example of Fig. 6B, the length of one side of the equilateral triangle at the base of the protrusions 81 is one-third of that in the example of Fig. 6A, and the horizontal and vertical spacing between the protrusions 81 is twice the length of one side of the equilateral triangle at the base of the protrusions 81.

[0054] In the surface portion 11 of Fig. 6A, the ratio of the area of ​​the region 31a where the protrusions 81 of the flat plate 31 of Fig. 6A are not formed to the entire area of ​​the light incident side of the flat plate 31 is smaller than the ratio in the surface portion 11 of Fig. 6B. Therefore, the surface portion 11 of Fig. 6A has a lower rectilinear light transmittance than the surface portion 11 of Fig. 6B. However, the spacing between the protrusions 81 in the surface portion 11 of Fig. 6A is closer to the width of the protrusions 81, i.e., the diameter of the inscribed circle of the bottom surface of the protrusions 81, compared to the surface portion 11 of Fig. 6B, and therefore the water repellency is high.

[0055] In contrast, the surface portion 11 in Fig. 6B has a higher rectilinear light transmittance but lower water repellency than the surface portion 11 in Fig. 6A. However, the water repellency can be improved by increasing the height of the protrusions 81 in Fig. 6B.

[0056] <Fourth structural example of surface portion> Fig. 7 is a top view and a side view showing a fourth structural example of the surface portion 11. Specifically, Fig. 7A and Fig. 7B are a top view and a side view, respectively, showing the fourth structural example of the surface portion 11.

[0057] In the surface portion 11 of Figure 7, parts corresponding to those in the surface portion 11 of Figure 3 are given the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the surface portion 11 of Figure 3. The surface portion 11 of Figure 7 differs from the surface portion 11 of Figure 3 in that three protrusions 91 are formed on the side surface of the protrusion 32, but is otherwise configured in the same way as the surface portion 11 of Figure 3.

[0058] As shown in Figures 7A and 7B, the three protrusions 91 formed on the side surface of the protrusion 32 are all conical in shape and of the same size. That is, the overall shape of the protrusions 32 and 91 on the surface portion 11 is a fractal shape. The size of the protrusion 91 is smaller than the size of the protrusion 32, and in the example of Figure 7, it is half the size of the protrusion 32. The generatrix and the diameter of the circle on the base of the protrusion 91 are approximately the same. In the example of Figure 7, the vertices of the three protrusions 91 are located at equal intervals on the same concentric circle on the same plane perpendicular to the perpendicular line from the vertex of the protrusion 32.

[0059] As described above, by forming protrusions 91 smaller than protrusions 32 on the side surfaces of protrusions 32, even droplets that are too small for protrusions 32 become droplets of an appropriate size for protrusions 91, and protrusions 91 can function as a rough surface for droplets. As a result, the water repellency of surface portion 11 against droplets of different sizes is improved. Furthermore, by forming protrusions 91, the effective contact area ratio of surface portion 11 increases compared to surface portion 11 in FIG. 3 , thereby improving the water repellency itself.

[0060] <Fifth structural example of surface portion> Fig. 8 is a top view and a side view showing a fifth structural example of the surface portion 11. Specifically, Fig. 8A and Fig. 8B are a top view and a side view, respectively, showing the fifth structural example of the surface portion 11.

[0061] In the surface portion 11 of Figure 8, parts corresponding to those in the surface portion 11 of Figure 6 are given the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the surface portion 11 of Figure 6. The surface portion 11 of Figure 8 differs from the surface portion 11 of Figure 6 in that three protrusions 111 are formed on the side surface of the protrusion 81, but is otherwise configured in the same way as the surface portion 11 of Figure 6.

[0062] As shown in Figures 8A and 8B, the three protrusions 111 formed on the side surface of the protrusion 81 are all shaped like regular triangular pyramids of the same size. That is, the overall shape of the protrusions 81 and 111 on the surface portion 11 is a fractal shape. The size of the protrusions 111 is smaller than the size of the protrusion 81, and in the example of Figure 8, it is half the size of the protrusion 81. Each of the three protrusions 111 is formed on each of the three side surfaces of the triangle of the protrusion 81 so that their positions in the height direction perpendicular to the flat plate 31 are the same.

[0063] As described above, by forming the protrusions 111 smaller than the protrusions 81 on the side surfaces of the protrusions 81, even droplets that are too small for the protrusions 81 become an appropriate size for the protrusions 111, and the protrusions 111 can function as a rough surface for droplets. As a result, water repellency against droplets of different sizes is improved. Furthermore, by forming the protrusions 111, the effective contact area ratio of the surface 11 increases compared to the surface 11 in FIG. 6 , thereby improving the water repellency itself.

[0064] <Example of Arrangement of Protrusions> FIG. 9 is a top view showing an example of arrangement of the protrusions 81 of FIG. 8 on the surface portion 11. As shown in FIG.

[0065] 9, in order to simplify the drawing, only an area of ​​the surface portion 11 where 2×2 protrusions 81 are arranged is shown. This also applies to FIG. 10, which will be described later.

[0066] The spacing between the protrusions 81 is set so that the protrusions 111 arranged on the side of one protrusion 81 do not come into contact with the protrusions 111 arranged on the side of a neighboring protrusion 81. In the example of Fig. 9, the spacing between the protrusions 81 in the horizontal and vertical directions is twice the length of one side of the equilateral triangle at the base of the protrusion 81.

[0067] As shown in Figures 7 to 9, even when protrusions 91 (111) are formed on the side surfaces of protrusions 32 (81), the rectilinear light transmittance of the surface portion 11 depends greatly on the size of the bottom surfaces of the protrusions 32 (81) and the horizontal and vertical spacing of the protrusions 32 (81).

[0068] The number of divisions into the size of the protrusions 32 (81) is not limited to 2. The size of the protrusions 32 (81) is divided, for example, so that the minimum size is a size that can function as a rough surface for anticipated droplets. Therefore, if the maximum size of the protrusion is an extremely elongated cube, the number of divisions into the size of the protrusion increases.

[0069] <Sixth Structural Example of Surface Portion> FIG. 10 is a top view showing a sixth structural example of the surface portion 11. As shown in FIG.

[0070] In the surface portion 11 of Fig. 10, parts corresponding to those in the surface portion 11 of Fig. 9 are given the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the surface portion 11 of Fig. 9. The surface portion 11 of Fig. 10 differs from the surface portion 11 of Fig. 9 in that a protrusion 131 is newly formed, but is otherwise configured in the same way as the surface portion 11 of Fig. 9.

[0071] As shown in Figure 10, the protrusions 131 are regular triangular pyramids of the same size as the protrusions 111. In the example of Figure 10, for every 2 x 2 protrusions 81, a protrusion 131 is arranged in the center of the 2 x 2 protrusions 81. Note that the protrusions 131 may be arranged in any manner as long as they are arranged between the protrusions 81. By forming protrusions 131 identical to the protrusions 111, the number of protrusions 111 and 131 of sizes suitable for small droplets increases. Therefore, the water repellency of the surface portion 11 can be further improved.

[0072] As described above, the imaging device 10 includes a surface unit 11, a lens 12, an imaging unit 13, and a signal processing circuit 14. The surface unit 11 is configured by a light-transmitting flat plate 31 on which a plurality of protrusions 32 (81) are regularly arranged. Therefore, the area 31a of the surface unit 11 where the protrusions 32 (81) are not formed can have light transmittance and improved water repellency. As a result, the imaging device 10 can be prevented from becoming dirty while minimizing the impact on imaging. This allows the imaging device 10 to be installed even in locations or under conditions where removing dirt is difficult. Since it is not necessary to detect and remove dirt from the imaging device 10 or to perform signal processing to enable high-quality images to be generated even when dirt is present, the imaging device 10 can be simplified to ensure reliability.

[0073] On the other hand, if an imaging device performs signal processing that enables it to generate high-quality images even when dirt is attached, the signal processing becomes more complex and the processing load increases.If a water-repellent material is applied to the lens of an imaging device using a spray or the like to prevent dirt from adhering to the lens, the material significantly changes the light incident on the lens, making it difficult for the imaging element to receive the light normally.

[0074] The shape of the protrusions 32 (81, 91, 111, 131) can be any shape, such as a cone, a regular triangular pyramid, a polygonal prism, or a polygonal pyramid other than a regular triangular pyramid. When the protrusions 32 (81, 91, 111, 131) are square prisms, the surface portion 11 can be easily manufactured. The protrusions 91 (111) may be disposed on the flat plate 31 near the protrusions 32 (81) rather than being formed on the side surfaces of the protrusions 32 (81). In this case, the surface portion 11 can be easily manufactured.

[0075] The shape, size, and spacing of the protrusions 32 (81, 91, 111, 131) are set according to the performance of the downstream imaging unit 13 and signal processing circuit 14. For example, the shape, size, and spacing of the protrusions 32 (81, 91, 111, 131) are set so that the surface unit 11 has a rectilinear light transmittance according to the performance of the imaging unit 13 and signal processing circuit 14, and so that water repellency is maximized. If the signal processing circuit 14 can compensate for the reduction in rectilinear light transmittance or insufficient light amount caused by the protrusions 32 (81, 131), the surface unit 11 may have a smaller rectilinear light transmittance, and water repellency can be further improved.

[0076] If the signal processing circuit 14 can perform processing that takes into account the influence of light that has passed through the protrusions 32 (81, 91, 111, 131), the light-shielding film (light-shielding portion 71) does not need to be formed regardless of the shape, size, and spacing of the protrusions 32 (81, 91, 111, 131). The spacing between the protrusions 32 (81) does not have to be completely equal, as long as it is approximately equal.

[0077] 2. Second Embodiment Configuration Example of Imaging Apparatus FIG. 11 is a diagram showing a configuration example of an imaging apparatus that is a second embodiment of a photodetector to which the present technology is applied.

[0078] In the imaging device 210 in Fig. 11, parts corresponding to those in the imaging device 10 in Fig. 1 are assigned the same reference numerals. Therefore, the description of those parts will be omitted as appropriate, and the description will focus on parts that differ from the imaging device 10. The imaging device 210 is a lensless camera, and differs from the imaging device 10 in that it includes a surface portion 211 and a mask 212 instead of the surface portion 11 and the lens 12, but is otherwise configured similarly to the imaging device 10.

[0079] Surface portion 211 differs from surface portion 11 in that protrusions are formed at positions other than those corresponding to the multiple micropores formed in mask 212, but is otherwise configured in the same manner as surface portion 11.

[0080] The mask 212 is a light control unit that controls light incident from the subject 20 to the imaging unit 13 through the surface portion 211. Specifically, the mask 212 has a plurality of microscopic holes (random holes) that penetrate the mask 212 non-periodically. The mask 212 functions as a coded aperture, and emits light that has entered from the subject 20 through the surface portion 211 to the imaging unit 13 without being collected through the microscopic holes. Therefore, the captured image generated by the signal processing circuit 14 of the imaging device 10 is a non-imaged image. Therefore, an imaged image is restored from this captured image by a downstream image processing device (not shown).

[0081] Note that the surface portion 211 and the mask 212 may be integrated. That is, the surface portion 211 may be formed on the incident side surface of the mask 212. The surface portion 211 may be configured in the form of a sheet or the like separate from the mask 212, and may be attached to the incident side surface of the mask 212.

[0082] <Example of Mask Structure> FIG. 12 is a diagram showing an example of the structure of the mask 212 in FIG.

[0083] 12 , a plurality of microscopic holes 231 are formed non-periodically in the mask 212. Light incident on the mask 212 is emitted to the imaging unit 13 through the microscopic holes 231. Therefore, no protrusions are formed in the areas of the flat plate of the surface unit 211 that correspond to the microscopic holes 231. In other words, protrusions are formed in areas of the flat plate of the surface unit 211 that correspond to the light-shielded areas other than the microscopic holes 231 of the mask 212. This makes it possible to prevent the protrusions from adversely affecting the light that is incident on the imaging unit 13 through the microscopic holes 231.

[0084] As described above, the imaging device 210 includes the surface portion 211, the mask 212, the imaging unit 13, and the signal processing circuit 14. The surface portion 211 is configured by arranging a plurality of protrusions on a light-transmitting flat plate in areas other than the areas corresponding to the micropores 231 of the mask 212. Therefore, the surface portion 211 can have improved water repellency while maintaining rectilinear light transmittance in the areas corresponding to the micropores 231. As a result, it is possible to prevent the adhesion of dirt to the imaging device 210 while suppressing the influence on imaging.

[0085] The protrusions on the surface portion 211 may be arranged regularly.

[0086] The present technology can also be applied to a light detection device that includes a light detection element that detects a phenomenon using light, other than an imaging device that includes an imaging element.

[0087] 3. Application Examples to Mobile Bodies The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0088] FIG. 13 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0089] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 13, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown in the figure are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053 as functional components of the integrated control unit 12050.

[0090] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0091] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0092] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0093] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0094] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0095] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0096] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0097] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0098] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 13, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0099] FIG. 14 is a diagram showing an example of the installation position of the imaging unit 12031.

[0100] In FIG. 14, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0101] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0102] 14 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0103] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0104] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation.

[0105] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0106] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0107] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 12031, the outside vehicle information detection unit 12030, and other components of the above-described configuration. Specifically, for example, the imaging device 10 (210) can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to prevent dirt from adhering to the imaging unit 12031 while suppressing the impact on imaging. As a result, a captured image that is easier to see can be obtained, thereby reducing driver fatigue.

[0108] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0109] For example, it is possible to adopt a configuration in which all or part of the above-described embodiments are combined.

[0110] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0111] The present technology can have the following configurations. (1) A photodetector including: a photodetector element that detects incident light; a light control unit that controls the light incident on the photodetector element; and a surface unit formed on the light incident side of the photodetector element, wherein the surface unit is configured by a flat plate that transmits the light and on which a plurality of protrusions are regularly arranged. (2) The photodetector according to (1), wherein the protrusions are configured to have light-blocking properties. (3) The photodetector according to (1), wherein a region of the flat plate on which the plurality of protrusions are formed has light-blocking properties, and a region on which the plurality of protrusions are not formed has light-transmitting properties. (4) The photodetector according to any of (1) to (3), wherein the plurality of protrusions are arranged at predetermined intervals. (5) The photodetector according to any of (1) to (4), wherein other protrusions different in size from the protrusions are arranged on a surface of the protrusions. (6) The light detection device according to any one of (1) to (5), configured so that other protrusions different in size from the protrusions are arranged between the protrusions. (7) A sheet for a light detection device including a light detection element that detects incident light and a light control unit that controls the light incident on the light detection element, the sheet being formed on the light incident side of the light detection element and configured by regularly arranging a plurality of protrusions on a flat plate that transmits the light.

[0112] REFERENCE SIGNS LIST 10 imaging device, 11 surface portion, 12 lens, 13 imaging portion, 14 signal processing circuit, 31 flat plate, 31a region, 32 protrusion portion, 70 region, 81, 91, 111, 131 protrusion portion, 210 imaging device, 211 surface portion, 212 mask

Claims

1. A photodetection device comprising a photodetection element that detects incident light, a light control unit that controls the light incident on the photodetection element, and a surface portion formed on the light incident side of the photodetection element with respect to the light, wherein the surface portion is configured by regularly arranging a plurality of protrusions on a flat plate that transmits the light.

2. The photodetection device according to claim 1, wherein the protrusions are configured to have a light-shielding property.

3. The photodetection device according to claim 1, wherein a region of the flat plate where the plurality of protrusions are formed has a light-shielding property, and a region where the plurality of protrusions are not formed has a light-transmitting property.

4. The photodetection device according to claim 1, wherein the plurality of protrusions are configured to be arranged at a predetermined interval.

5. The photodetection device according to claim 1, wherein other protrusions having a size different from that of the protrusions are arranged on the surface of the protrusions.

6. The photodetection device according to claim 1, wherein other protrusions having a size different from that of the protrusions are arranged between the protrusions.

7. A sheet for a photodetection device comprising a photodetection element that detects incident light and a light control unit that controls the light incident on the photodetection element, the sheet being formed on the light incident side of the photodetection element with respect to the light and configured by regularly arranging a plurality of protrusions on a flat plate that transmits the light.

Images