Electronic device and window glass equipped with electronic device

Abstract

This electronic device is an imaging device (100) provided so as to face a main surface (11B2), which is on the indoor side, of window glass (11) that separates the indoor side and the outdoor side of a space. The electronic device includes an opposing surface (111) facing the window glass (11). When the distance between the window glass (11) and the opposing surface (111) is g, the solar absorption rate of the opposing surface (111) is α, and the outer peripheral length of the opposing surface (111) is S, the following expressions (1)-(4) are satisfied. Expressions: (1) g ≥ 0; (2) g ≥ c1 × α + c2; (3) c1 = 0.0381S2 - 0.49S + 0.95; (4) c2 = -0.0032S2 - 0.41S - 6.1.

Description

Electronic devices and window glass with electronic devices

[0001] This disclosure relates to electronic devices and window glass with electronic devices.

[0002] As an example of an electronic device installed on or near a windowpane, a window camera is known (for example, Japanese Patent Publication No. 2021-111812). The window camera described in Japanese Patent Publication No. 2021-111812 is attached by adsorption or attachment to the interior glass of a window made of double-glazed glass, and captures images of the outside through the window.

[0003] However, when electronic devices are installed in or near window panes, the window panes may locally heat up due to the heat transferred or radiated from the electronic devices. When window panes heat up locally, there is a possibility that they may be damaged, such as by thermal cracking.

[0004] This disclosure, taking the above facts into consideration, aims to provide an electronic device that can suppress damage to window glass and a window glass equipped with an electronic device.

[0005] The electronic device relating to this disclosure is an electronic device provided so as to face the main surface on the interior side of a windowpane separating the interior from the exterior, and comprises a facing surface that faces the windowpane, and satisfies the following equations (1) to (4) when the distance between the windowpane and the facing surface is g, the solar absorptivity of the facing surface is α, and the outer circumference length of the facing surface is S. g ≥ 0 ... (1) g ≥ c1 × α + c2 ... (2) c1 = 0.038S ２ -0.49S+0.95...(3) c2=-0.0032S ２ -0.41S-6.1...(4)

[0006] As explained above, the electronic device and window glass with the electronic device relating to this disclosure have the excellent effect of suppressing damage to the window glass.

[0007] This is a perspective view showing an imaging device and the surrounding configuration of the imaging device according to an embodiment of the present disclosure. This is a perspective view showing an imaging device according to an embodiment of the present disclosure. This is a schematic front view showing an imaging device and the surrounding configuration of the imaging device according to an embodiment of the present disclosure. This is a cross-sectional view taken along the line 4-4 in Figure 3. This is a schematic front view showing an imaging device and the surrounding configuration of the imaging device according to a modified embodiment of the present disclosure. This is a graph showing the relationship between the distance between the window glass and the opposing surface, the solar absorptivity of the opposing surface, and the stress at the edge of the window glass. This is a graph showing the relationship between the distance between the window glass and the opposing surface, the solar absorptivity of the opposing surface, and the outer perimeter of the opposing surface, showing the case where the imaging device is a right-angled isosceles triangle. This is a graph showing the relationship between the distance between the window glass and the opposing surface, the solar absorptivity of the opposing surface, and the outer perimeter of the opposing surface, showing the case where the imaging device is a square. This is a graph showing the relationship between the distance between the window glass and the opposing surface, the solar absorptivity of the opposing surface, and the outer perimeter of the opposing surface. This is a table showing the relationship between the distance between the window glass and the opposing surface, the solar absorptivity of the opposing surface, the outer perimeter of the opposing surface, and the stress at the edge of the window glass. This figure illustrates one example of why reflections are included in the image captured by the comparative imaging device. This figure illustrates one example of why reflections are included in the image captured by the comparative imaging device. This figure illustrates one example of why the imaging device of the embodiment can reduce reflections. This figure illustrates one example of why the imaging device of the embodiment can reduce reflections. Figures 13AA to 13AF show examples of images obtained by fixed-point imaging with a camera, with the horizontal field of view θx set to 40 degrees, 50 degrees, 70 degrees, 80 degrees, 105 degrees, and 120 degrees. This figure shows an example of simulation results calculated by setting the reflection reduction rate Rx (%) with respect to distance Dx in 10-degree increments from 40 degrees to 100 degrees. This figure shows an example of calculation results when the horizontal field of view θx shown in Figure 13B is 40 degrees. This figure illustrates an example of the reflection reduction rate Rx with respect to distance Dx in the imaging device of the embodiment.

[0008] Embodiments of the electronic device and window glass with the electronic device relating to this disclosure will be described below with reference to Figures 1 to 14. In the following description and in each figure, the width direction (horizontal direction) of the window glass is defined as the X-axis direction, the height direction of the window glass is defined as the Y-axis direction, and the thickness direction of the window glass is defined as the Z-axis direction. For example, in the width direction of the window glass, the direction toward the mounting position of the imaging device to the window glass is defined as the +X-axis direction, and the opposite direction is defined as the -X-axis direction. For example, the direction from the bottom to the top of the window glass is defined as the +Y-axis direction, and the opposite direction is defined as the -Y-axis direction. For example, the indoor side of the window glass is defined as the +Z-axis direction, and the outdoor side of the window glass is defined as the -Z-axis direction. In the following description, the +Y-axis direction may be referred to as "up," and the -Y-axis direction may be referred to as "down." In the following description, "front view" means XY plane view. For example, the X-axis direction and the Z-axis direction are approximately parallel to the horizontal plane, and the Y-axis direction is approximately parallel to the direction perpendicular to the horizontal plane (in other words, the vertical direction).

[0009] In the following description, an imaging device will be used as an example of the electronic device relating to this disclosure. As shown in Figure 1, the imaging device (electronic device) according to this embodiment is attached, for example, to a window 10 provided in the wall 16 of a building 15.

[0010] <Window 10> Window 10 separates the interior and exterior of the building 15. Window 10 has a window pane 11 and a window frame 12. The window frame 12 is an example of a structure that is in contact with the window pane 11. The window pane 11 is generally housed in the window frame 12 via components such as a gasket and elastic sealant, but it may also be in direct contact with the window frame 12. The window pane 11 is a fixed window as an example, but it may also be a sliding window or the like.

[0011] An imaging device 100 is attached to the window 10. Specifically, the imaging device 100 is positioned opposite the main interior surface 11B2 of the window glass 11 provided in the window 10 of the building 15. As an example, the imaging device 100 is shaped like a roughly right-angled isosceles triangle when viewed from the front. The imaging device 100 is positioned at the upper end and one end in the width direction corner of the window 10.

[0012] Here, the window glass 11, the window frame 12, and the imaging device 100 constitute the window glass with imaging device (window glass with electronic device) 150 of the embodiment. However, the window glass with imaging device 150 may include the window glass 11 and the imaging device 100, but may not include the window frame 12.

[0013] The following describes the configuration in which the window glass 11 is installed in the building 15. However, the window glass 11 may also be installed in structures other than the building 15, or in vehicles such as automobiles. Examples of structures other than the building 15 include, for example, bridge piers, bridges, or civil engineering structures such as dams, as well as historical buildings or artistic buildings.

[0014] <Window Glass 11> Window glass 11 is a glass plate used in the windows of a building such as building 15. Window glass 11 may also be a glass facade located in the entrance of building 15. Window glass 11 is formed in a rectangular shape when viewed from the front, for example. Note that "rectangular" includes not only rectangles and squares, but also shapes where the corners of a rectangle or square are beveled. The shape of the window glass when viewed from the front is not limited to a rectangular shape, and may be other shapes such as a circle.

[0015] The window glass 11 separates the outside from the inside. The window glass 11 has an exterior main surface 11A1 and an interior main surface 11B2. The window glass 11 may be single-pane glass, laminated glass, or double-pane glass. The window glass 11 may also include glass coated with a heat-reflective film such as a Low-E (low emissivity) film, colored glass (also called heat-absorbing glass), or light-adjusting glass. The window glass 11 may also be glass that is neither colored nor surface-coated (hereinafter referred to as clear glass in this specification).

[0016] The heat-reflective film is preferably a metal film that is transparent to visible light. "Transparent" to visible light means that the luminous transmittance is at least 40%, preferably 60%, more preferably 70%, and even more preferably 80%.

[0017] The heat-reflective film performs the function of reflecting heat rays by comprising a conductive film. Furthermore, the heat-reflective film may also comprise layers other than the conductive film, insofar as it achieves the effects of this disclosure. Hereinafter, layers other than the conductive film in the heat-reflective film may be referred to as "other layers."

[0018] In this specification, "conductive film" refers to a film with an electrical resistivity of 100 [Ω·cm] or less at 20°C. The components of the conductive film are not particularly limited, but for example, metals such as silver, aluminum, and stainless steel, indium tin oxide (ITO), fluorine, and antimony doped tin oxide (SnO) have excellent heat reflectivity. ２ It is preferable that the main components are F, Sb), titanium nitride, niobium nitride, chromium nitride, zirconium nitride, and hafnium nitride (hereinafter also referred to as "conductive film component group A"). In this specification, "main component" means a content of 50 atomic percent or more of the total constituent components. That is, the conductive film of this embodiment contains at least one selected from the group consisting of conductive film component group A, and it is preferable that the total content of conductive film component group A in the conductive film of this embodiment is 50 atomic percent or more.

[0019] For a heat-reflective film to exhibit excellent heat-reflective properties, the conductive film preferably has at least one of silver and aluminum as its main component, more preferably has silver as its main component (i.e., contains 50% or more atoms), and even more preferably contains 95% or more atoms of silver.

[0020] Furthermore, the above-mentioned silver-based conductive film may contain one or more additive elements such as gold, palladium, copper, bismuth, neodymium, and platinum. By incorporating such additive elements into a silver-based conductive film, the diffusion of silver can be suppressed and moisture resistance can be improved. The additive elements are not limited to those exemplified above, and any element can be added as long as it achieves the effects of this disclosure.

[0021] In terms of durability, the heat-reflective film is preferable if it has a layer structure in which the conductive film is sandwiched between other layers such as a metal oxide layer or a metal nitride layer. Examples of metal oxide layers include layers of metal oxides mainly composed of aluminum oxide, zinc oxide, indium oxide, titanium oxide, niobium oxide, tin oxide, bismuth oxide, tantalum oxide, tungsten oxide, zirconium oxide, silicon oxide, etc. Of these, zinc oxide is preferred as the main component of the metal oxide layer because it has good compatibility with silver, which is a preferred component of the conductive film, and can improve the durability of the conductive film. Examples of metal nitride layers include silicon nitride (Si ３ N ４ Examples include layers of metal nitrides mainly composed of aluminum nitride (AlN), titanium nitride, etc.

[0022] Examples of materials for the window glass 11 include soda-lime silica glass, borosilicate glass, aluminosilicate glass, or alkali-free glass.

[0023] The thickness of the window glass 11 is 1.0 mm or more, and preferably 40 mm or less. If the thickness of the window glass 11 is 1.0 mm or more, the window 10 has sufficient strength to mount the imaging device 100. The thickness of the window glass is more preferably 3.0 mm or more, and even more preferably 9.0 mm or more. Furthermore, there is no particular upper limit to the thickness of the window glass 11, but it may be 40 mm or less, 20 mm or less, 15 mm or less, or 13 mm or less. Also, the thickness of the window glass 11 is not limited to the above values. The thickness of the window glass 11 may be set appropriately according to the specifications of the building 15.

[0024] Furthermore, the visible light reflectance of the window glass 11 as defined in JIS R 3106:2019 is, for example, 6% or more. Also, the visible light transmittance (TV) of the window glass 11 as defined in JIS R 3106:2019 is, for example, 30% to 96%. If the TV of the window glass 11 is 30% or more, the imaging device 100 will have sufficient image quality when it captures an image of the outside through the window glass 11. Also, if the TV of the window glass 11 is 96% or less, it will have excellent solar radiation shielding properties. The TV of the window glass 11 is preferably 50% or more, more preferably 70% or more, even more preferably 75% or more, and particularly preferably 80% or more. Also, the TV of the window glass 11 is preferably 95% or less, more preferably 92% or less, even more preferably 90% or less, and particularly preferably 85% or less.

[0025] <Imaging Device 100> The imaging device 100 is a device used by being attached to the interior side of the window glass 11 of the building 15. The imaging device 100 is a device that captures still images and videos of the outside through the window glass 11. For example, the imaging device 100 is connected to a processing device that performs image processing etc. via a cable 101. The imaging device 100 transmits image data to the processing device via the cable 101. The imaging device 100 also receives control signals from the processing device via the cable 101 to switch the imaging unit 140 on / off, etc., and receives power from the processing device (not shown). As shown in Figure 2, a connector 102 is connected to the end of the cable 101.

[0026] The processing unit is located, for example, inside a room in building 15. The processing unit may, as an example, be connected to an information processing unit such as a server outside the room via a wireless communication device or cable installed inside building 15. Alternatively, the processing unit may be connected to an information processing unit such as a PC (Personal Computer) or server installed inside building 15 via a cable or wireless communication device, and the PC or server may be connected to a higher-level server outside the room via a cable or wireless communication device.

[0027] As shown in Figure 1, the imaging device 100 includes a lens 130 facing the main surface 11B2 on the interior side of the window glass 11, and images an external subject through the lens 130 and the window glass 11. The subject is, for example, the scenery visible from the window glass 11 (everything visible from the window glass 11), and the scenery may be, for example, a road, sidewalk, passage or intersection, entrance to a building 15, ticket gate or entrance to a station, etc., and may also include people, vehicles, etc. Furthermore, the imaging device 100 may capture infrared images if infrared images can be acquired. The information captured by the imaging device 100 may be used for digital twin computing.

[0028] Such an imaging device 100 can be used for a variety of purposes and is not limited to any particular use. The imaging device 100 can capture images of subjects outside the window glass 11 of the building 15 and use the resulting images for a variety of purposes. Here, as an example, we will describe an application in which the imaging device 100 is used as a security surveillance camera. Since the imaging device 100 is positioned opposite the main surface 11B2 on the interior side of the window glass 11, it is difficult to see from the outside of the window glass 11 due to reflection. For this reason, its use as a surveillance camera is one example of a suitable application for the imaging device 100.

[0029] The height at which the imaging device 100 is attached to the windowpane 11 is preferably higher than the average human height, from the viewpoint of being able to get a good view of the area to be monitored. For example, the height at which the imaging device 100 is attached to the windowpane 11 is preferably 2m or more, and it may be attached to the windowpane 11 on the second floor or higher of a building 15, for example. If the height at which the imaging device 100 is attached to the windowpane 11 is 2m or more, it will be difficult for the person being monitored to see it.

[0030] Regarding the height of the position where the imaging device 100 is attached to the window glass 11, as an example, it may be set to a height at which an appropriate image can be captured in consideration of the range that can be imaged by the angle of view of the imaging device 100, the distance to the subject, etc. The upper limit of the height of the position where the imaging device 100 is attached to the window glass 11 is the height of the upper end of the window glass 11 that exists at the highest position among the window glasses 11 existing in the building 15. Note that the height of the imaging device 100 may be defined as the height from a reference plane parallel to the horizontal plane (for example, the ground, the floor surface, or a virtual plane). Also, the height of the imaging device 100 may be the height of the lens 130.

[0031] <Detailed Configuration of Imaging Device 100> As shown in FIGS. 1 and 2, the imaging device 100 includes a case 110, a lens 130, and an imaging unit 140. The imaging device 100 is attached to the window frame 12 of the window 10. Also, at least a part of the imaging device 100 is provided at a position within 10 cm from the edge of the window glass 11 in a front view.

[0032] <Case 110> The case 110 serves as the housing of the imaging device 100. The case 110 is shaped like a right-angled isosceles triangle in a front view. The case 110 extends in the Z-axis direction by a predetermined length. That is, the case 110 is a triangular prism-shaped housing that extends along the Z-axis direction.

[0033] The case 110 may be made of resin or metal, for example. As the resin material, a thermoplastic resin can be used, for example. As the thermoplastic resin, PC (polycarbonate) / ASA (Acrylate Styrene Acrylonitrile), ASA, or AES (Acrylonitrile Ethylene Styrene) etc. can be used. As the metal material, aluminum, iron, stainless steel, etc. can be used.

[0034] The case 110 has a facing surface 111 facing the main surface 11B2 on the indoor side of the window glass 11, a back surface 112 which is the surface on the opposite side to the facing surface 111, and side surfaces 113 connecting the facing surface 111 and the back surface 112. Further, the case 110 has a skirt (protruding portion) 114 protruding from the facing surface 111 in the direction of the window glass 11.

[0035] <Opposing surface 111> The opposing surface 111 is a surface parallel to the XY plane. The opposing surface 111 is a surface that partially or entirely faces the main surface 11B2 on the indoor side of the window glass 11. In the present embodiment, the opposing surface 111 is separated from the main surface 11B2 on the indoor side of the window glass 11.

[0036] As an example, the opposing surface 111 has a shape of a right-angled isosceles triangle when viewed from the front, and a concave portion 111A recessed in the Z-axis direction is provided at a substantially central portion. The surface of the concave portion 111A is recessed in a mortar shape and is annular when viewed from the front. Here, as an example, a form in which the opposing surface 111 has a shape of a right-angled isosceles triangle when viewed from the front will be described. However, the opposing surface 111 may have a shape of a right triangle in which the lengths of two sides other than the hypotenuse are different when viewed from the front, or may have a shape that is not a right triangle.

[0037] As an example, the concave portion 111A has an opening 111A1 at the central portion when viewed from the front. A lens 130 is provided in the opening 111A1 so as to be exposed from the opposing surface 111. As an example, the concave portion 111A has a depth such that the lens 130 does not protrude in the Z-axis direction more than the opposing surface 111 in the Z-axis direction.

[0038] Further, the concave portion 111A is formed in a tapered shape so that the opening diameter in the front view increases as it moves away from the opening 111A1 in order to prevent the wall surface of the concave portion 111A from falling within the range of the angle of view determined by the lens 130 and the imaging unit 140. Thereby, the wall portion of the concave portion 111A can be prevented from being reflected in the image captured by the imaging device 100. Further, the lens 130 can change its orientation with respect to the case 110. The concave portion 111A has a largely expanded tapered shape in order to prevent it from being reflected in the image even when the orientation of the lens 130 is changed so that the angle of the lens 130 with respect to the Z-axis becomes maximum.

[0039] The recess 111A may, for example, have a depth such that the lens 130 and holder 131 are flush with the opposing surface 111 in the Z-axis direction, or it may have a depth such that the lens 130 and holder 131 protrude further in the Z-axis direction than the opposing surface 111.

[0040] Furthermore, as shown in Figure 3, the opposing surface 111 is a right-angled isosceles triangle when viewed from the front. Therefore, the opposing surface 111 has two adjacent sides 115 and 116 that enclose a right-angle corner with the hypotenuse 117.

[0041] Furthermore, the opposing surface 111 is provided, for example, with a skirt 114 erected on its outer periphery when viewed from the front. The skirt 114 extends over almost the entire outer periphery. That is, the skirt 114 extends along the hypotenuse 117, adjacent sides 115 and 116. On the inside of the skirt 114 that is provided along the hypotenuse 117, a groove-forming wall 119 is erected to form a housing groove 118 between itself and the skirt 114. The cable 101 is housed in the housing groove 118.

[0042] The opposing surface 111 has a solar absorptance that conforms to JIS 3106:2019, which is set to a predetermined value. More specifically, the solar absorptance of the opposing surface 111 is preferably 85% or less, and more preferably 75% or less. The opposing surface 111 may have the material of the case 110 exposed, or the surface of the material of the case 110 may be coated with paint. If the opposing surface 111 is coated with paint, the opposing surface 111 contains the paint. Therefore, the solar absorptance of the opposing surface 111 can be adjusted by the paint. The paint may be, for example, black or dark-colored paint. A specific example of the paint is, for example, the paint described in Japanese Patent Application Publication No. 2000-129172. If the opposing surface 111 is divided into multiple parts with different solar absorptances, the solar absorptance of the opposing surface 111 is determined by weighted averaging using area fractions.

[0043] Furthermore, the area of ​​the opposing surface 111 in a front view is set to a predetermined value. Specifically, the area of ​​the opposing surface 111 in a front view is, for example, 1000 cm². ２ The following applies. Furthermore, the lower limit of the area of ​​the opposing surface 111 in a front view is not particularly limited, but 1 cm ２ That's all.

[0044] <Back surface 112> The back surface 112 is a surface located on the opposite side of the opposing surface 111, as shown in Figure 4 in particular. For example, it has the shape of a right-angled isosceles triangle, which is the same shape and size as the opposing surface 111. The back surface 112 is parallel to the XY plane. In a front view, the back surface 112 is positioned such that its hypotenuse and two adjacent sides overlap with the hypotenuse 117 and two adjacent sides 115 and 116 of the opposing surface 111, respectively.

[0045] <Side 113> As shown in Figures 1 and 2, side 113 is composed of three sides 113A, 113B, and 113C. Hereinafter, unless otherwise distinguished, the three sides 113A, 113B, and 113C will simply be referred to as side 113. Sides 113A, 113B, and 113C connect the opposing surface 111 of the case 110 to the rear surface 112.

[0046] Side surface 113C connects the hypotenuse 117 of the opposing surface 111 (see Figure 3) to the hypotenuse of the back surface 112. Side surface 113C is a surface that has a 45-degree angle with respect to the XZ plane and the YZ plane. Side surfaces 113A and 113B are connected to side surface 113C.

[0047] Furthermore, the sides 113A and 113B are provided so as to sandwich the right-angle corner of a right-angled isosceles triangle in a front view. Side 113A is a surface parallel to the XZ plane. Side 113B is a surface parallel to the YZ plane. Sides 113A and 113B are connected at a right angle. Sides 113A and 113B are provided so as to be in contact with the window frame 12. Magnets are provided on the inside (inside the case 110) of sides 113A and 113B. The imaging device 100 is fixed to the window frame 12 by magnetic attraction of these magnets to the window frame 12. If the window frame 12 is not made of magnetic metal, as an example, a sheet made of magnetic metal may be attached to the window frame 12, and the imaging device 100 may be fixed to the window frame 12 by magnetic attraction of the magnets to the magnetic metal sheet. The magnetic part is, for example, a permanent magnet with strong magnetic attraction, such as a neodymium magnet.

[0048] Here, as an example, we will describe a configuration in which the imaging device 100 includes a magnet and is magnetically attracted to a window frame 12 made of magnetic metal. However, the method of fixing the imaging device 100 to the window frame 12 is not limited to this. For example, the case 110 may be made of magnetic metal, a sheet-shaped magnet may be attached to the window frame 12, and the imaging device 100 may be fixed to the window frame 12 by magnetically attracting the case 110 to the sheet-shaped magnet attached to the window frame 12.

[0049] Alternatively, the imaging device 100 may be attached to the window frame 12 using an adhesive such as double-sided tape instead of a magnet. In this case, the adhesive such as double-sided tape should be applied to the part between the side surface 113A or 113B of the case 110 of the imaging device 100 and the window frame 12 that is not directly exposed to ultraviolet light. Even if the imaging device 100 is attached to the window frame 12 using an adhesive such as double-sided tape, if it is not directly exposed to ultraviolet light, deterioration due to ultraviolet light can be suppressed and the imaging device 100 can be stably fixed to the window frame 12.

[0050] Furthermore, while this description explains, as an example, how the imaging device 100 is fixed to the window frame 12, the fixing location of the imaging device 100 is not limited to the window frame 12. For example, the imaging device 100 may be fixed to a structure surrounding the window glass 11 other than the window frame 12, such as the ceiling or walls surrounding the window glass 11.

[0051] The imaging device 100 may also be suspended from the ceiling via a support or other component. Alternatively, the imaging device 100 may be attached to the main interior surface 11B2 of the window glass 11 with an adhesive or the like, or attached with double-sided tape.

[0052] <Skirt 114> As shown in Figures 2 to 4, the skirt 114 is a frame that is approximately a right-angled isosceles triangle in front view. The skirt 114 is provided on the outer circumference of the opposing surface 111. The skirt 114 protrudes from the opposing surface 111 toward the main surface 11B2 on the interior side of the window glass 11. The tip of the skirt 114 is in contact with the main surface 11B2 on the interior side of the window glass 11. The skirt 114 is formed from a plate-like member. The skirt 114 may be formed integrally with the case 110. The thickness of the skirt 114 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. If the thickness of the skirt 114 is 10 mm or less, it is less prone to thermal cracking. The thickness of the skirt 114 is preferably 0.5 mm or more, and may be 1 mm or more. If the thickness of the skirt 114 is 0.5 mm or more, it becomes easier to fix the imaging device 100 to the window glass 11, and also easier to manufacture the skirt 114.

[0053] In this embodiment, the tip of the skirt 114 is in contact with the main surface 11B2 on the interior side of the window glass 11. As a result, the space between the opposing surface 111 of the imaging device 100 and the main surface 11B2 on the interior side of the window glass 11 is a closed space. The closed space is defined by the opposing surface 111 of the imaging device 100, the main surface 11B2 on the interior side of the window glass 11, and the inner circumferential surface of the skirt 114.

[0054] <Lens 130> The lens 130 is held in a holder 131 that is configured to allow the orientation of the lens 130 to be changed. The lens 130 and the holder 131 are provided in the opening 111A1 of the recess 111A on the opposing surface 111 of the case 110.

[0055] <Imaging Unit 140> As shown in Figure 1, the imaging unit 140 is arranged to be aligned with the lens 130 along the Z-axis direction. The imaging unit 140 is a camera body capable of capturing digital images of both video and still images, and as an example, includes an image sensor using a CMOS (Complementary Metal Oxide Semiconductor) or CCD (Charge Coupled Device) as the image sensor. The camera body is the part of the camera excluding the lens 130. In other words, the imaging unit 140 and the lens 130 constitute a digital camera.

[0056] The imaging unit 140 captures an image of a subject outside the window glass 11 through the lens 130. The imaging unit 140 may or may not have a telephoto function. If the imaging unit 140 does not have a telephoto function, the imaging unit 140 can be made inexpensively, and the imaging device 100 can be manufactured at a low cost. The imaging unit 140 is connected to the processing device via the cable 101.

[0057] <How to attach the imaging device 100 to the window frame 12> Next, we will explain how to attach the imaging device 100 to the window frame 12, mainly using Figure 1. As shown in Figure 1, the window frame 12 has a horizontal frame portion 12X that extends in the X-axis direction and a vertical frame portion 12Y that extends in the Y-axis direction. In this embodiment, the horizontal frame portion 12X and the vertical frame portion 12Y are connected at the corner of the window frame portion 12. At the corner, the angle between the horizontal frame portion 12X and the vertical frame portion 12Y is 90 degrees.

[0058] For example, the imaging device 100 is positioned at the upper corner of the window frame 12. This is because the upper corner of the window frame 12 is less visible and less conspicuous to a large number of people from the outside. Also, a certain height is preferable for mounting the imaging device 100, as it allows for imaging of a wider area. However, the position where the imaging device 100 can be mounted is not limited to the upper corner of the window frame 12.

[0059] The imaging device 100 is fixed to the upper corner of the window frame 12 by bringing the sides 113A and 113B (see Figure 2) of the case 110 into contact with the upper corner of the window frame 12 and magnetically attracting the magnet part to the window frame 12.

[0060] The case 110 of the imaging device 100 has sides 113A and 113B that form a 90-degree angle, allowing sides 113A and 113B to contact the inner corners of the frame portions 12X and 12Y of the window frame 12. Therefore, by simply pressing sides 113A and 113B of the imaging device 100 against the inner corners of the frame portions 12X and 12Y of the window frame 12, the two magnetic portions 120 on sides 113A and 113B are magnetically attracted to the frame portions 12X and 12Y. In this way, the imaging device 100 can be easily attached to the window frame 12.

[0061] Furthermore, the imaging device 100 is a right triangle when viewed from the front and fits perfectly into the inner corners of the frame portions 12X and 12Y of the window frame 12. As a result, the imaging device 100 appears to be fused with the window frame 12, resulting in a good aesthetic design.

[0062] <Details of the Opposing Surface 111 and Skirt 114> The opposing surface 111 and skirt 114 of the imaging device 100 will be described in more detail. As shown in Figures 1 and 4, the imaging device 100 has a gap between the opposing surface 111 of the case 110 and the main surface 11B2 on the interior side of the window glass 11. When the distance between the opposing surface 111 and the main surface 11B2 on the interior side of the window glass 11 is g (more specifically, the distance in the Z-axis direction), the solar absorptivity of the opposing surface 111 is α, and the outer circumference length of the opposing surface 111 is S, the imaging device 100 satisfies the following equations (1) to (4): g ≥ 0 ... (1) g ≥ c1 × α + c2 ... (2) c1 = 0.038S ２-0.49S + 0.95...(3) c2 = -0.0032S ２ -0.41S - 6.1...(4)

[0063] As shown in formulas (1) to (4), the distance g between the facing surface 111 of the imaging device 100 and the window glass 11 may be determined based on the solar radiation absorption rate α of the facing surface 111 and the outer peripheral length S of the facing surface 111. In other words, the solar radiation absorption rate α of the facing surface 111 may be determined based on the distance g between the facing surface 111 of the imaging device 100 and the window glass 11 and the outer peripheral length S of the facing surface 111. In other words, the outer peripheral length S of the facing surface 111 may be determined based on the distance g between the facing surface 111 of the imaging device 100 and the window glass 11 and the solar radiation absorption rate α of the facing surface 111.

[0064] As shown in FIG. 4, in the imaging device 100 according to the present embodiment, the tip of the skirt 114 protruding from the facing surface 111 is in contact with the main surface 11B2 on the indoor side of the window glass 11. Therefore, the protruding length of the skirt 114 (the shortest distance from the tip of the skirt 114 to the facing surface 111) h coincides with the distance g by which the facing surface 111 and the main surface 11 on the indoor side of the window glass 11 are separated. In other words, g = h. Therefore, the imaging device 100 satisfies the following formulas (5) to (9). h > 0...(5) h ≥ c1 × α + c2...(6) c1 = 0.038S ２ -0.49S + 0.95...(7) c2 = -0.0032S ２ -0.41S - 6.1...(8) h = g...(9)

[0065] ​

[0066] Next, the derivation method for equations (1) to (9) above will be explained. The maximum stress σ generated at the edge of the window glass when an imaging device is installed at the corner of the window glass was calculated using the finite element method (FEM). The conditions refer to the thermal cracking calculation of the Flat Glass Association. Specifically, the window glass is double-glazed (more specifically, double-glazed with two transparent glass plates, each plate 6 mm thick, and a distance of 12 mm between them). The dimensions of the window glass are a width (length in the X-axis direction) of 1000 mm and a height (length in the Y-axis direction) of 1000 mm. The sash fitting is a standard fitting (conforms to JASS17). Furthermore, assuming installation in winter on a window glass 11 with the main interior surface 11B2 facing south vertically, the solar radiation is 825 [W / m ２ It is stated that the construction site for window glass 11 is assumed to be in southern Kanto, Hokuriku, Tokai, Kinki, Chugoku, Shikoku, or Kyushu, and the ambient temperature is assumed to be 5.0 [°C] outdoors and 20.0 [°C] indoors. The heat transfer coefficient is 8 W / m on the indoor side. ２ The temperature is K, and the outdoor temperature is 15.1 W / m². ２ It is designated as K. For the season, direction, and construction site, the most stringent conditions were selected from several calculations.

[0067] According to the thermal cracking risk assessment established by the Flat Glass Association, the stress σ generated at the edge of the window glass (hereinafter sometimes referred to as the "edge portion") is calculated using the following formula (10): σ = k0・k1・k2・k3・f・(tg-ts)・・・(10)

[0068] Here, tg is the temperature of the center of the glass, and ts is the window frame temperature. Also, k0 is the basic stress coefficient, k1 is the shadow coefficient, k2 is the curtain coefficient, k3 is the area coefficient, and f is the edge temperature coefficient.

[0069] Note that the FEM calculations do not consider the effects of the shadow coefficient (k1) and curtain coefficient (k2). Therefore, the final stress value is obtained by multiplying the calculated value by k1 and k2. Here, the shadow coefficient k1 is set to 1.7 (considered to be the most severe condition, parallel shadow or sharp shadow), and the curtain coefficient k2 is set to 1.

[0070] Using FEM, the stress generated at the edge of the window glass was calculated from equation (10) above. Specifically, the maximum stress generated at the edge of the window glass when the imaging device was installed at the corner of the window glass was calculated. The imaging device at this time was a right-angled isosceles triangle in front view, with a perimeter length of 46 cm on the opposing surface and a thickness of 50 mm. A skirt portion was installed without interruption along the entire perimeter of the opposing surface, and the tip of this skirt portion abutted against the window glass, forming a closed space between the opposing surface 111 of the imaging device and the main surface on the interior side of the window glass. Therefore, there was no airflow between the opposing surface of the imaging device and the main surface on the interior side of the window glass. Under these conditions, the behavior of the stress generated at the edge of the window glass was investigated by changing the solar absorptivity of the opposing surface of the imaging device from 10% to 95%. The results are shown in Figure 6.

[0071] Figure 6 shows the distance g (mm) between the opposing surface of the imaging device and the main interior surface of the window glass on the horizontal axis, and the stress generated at the edge of the window glass on the vertical axis. The values ​​from 10% to 95% shown at the bottom represent the solar absorptivity. The points in the graph of Figure 6 represent calculated values ​​using FEM, and the line represents an approximation of the calculated value. As shown in Figure 6, the generated stress σ increases as the solar absorptivity increases. Furthermore, when the solar absorptivity is 30% or higher, it can be observed that the generated stress decreases as the separation distance g increases. In addition, for all solar absorptivity values, the improvement effect saturates in the range where the separation distance g is greater than 12 mm. Therefore, the separation distance g may be 12 mm or less.

[0072] From the graph in Figure 6, it can be seen that to suppress thermal cracking of window glass, it is effective to lower the solar radiation absorptance of the opposing surface and to increase the distance g between the opposing surface of the imaging device and the main interior surface of the window glass. This study assumes conditions in which there is no airflow into the gap.

[0073] Thus, while installing an imaging device near a windowpane increases the temperature of the windowpane and raises the risk of thermal breakage, the temperature of the windowpane can be reduced by lowering the solar absorptivity of the surface opposite the imaging device, or by increasing the distance g between the surface opposite the imaging device and the main interior surface of the windowpane, thereby suppressing thermal breakage of the windowpane.

[0074] Next, we investigated the relationship between the distance g between the opposing surface and the window glass, the solar absorptivity of the opposing surface, and the outer perimeter length of the opposing surface when an imaging device having a right-angled isosceles triangular opposing surface is mounted near the window glass. The results of the investigation are shown in Figure 7. In Figure 7, the vertical axis shows the distance g between the opposing surface and the window glass, and the horizontal axis shows the solar absorptivity of the opposing surface.

[0075] Generally, the upper limit of allowable stress to suppress thermal cracking in window glass is considered to be 17.7 MPa. This upper limit of allowable stress is the stress applied to transparent glass, heat-absorbing glass, and glass coated with a heat-reflective film, with a thickness of 3 mm to 12 mm, as calculated by the Japan Flat Glass Association. This value applies not only to single-pane glass but also to laminated glass and double-pane glass.

[0076] Figure 7 plots the solar absorptivity of the opposing surface and the lower limit of the distance between the opposing surface and the window glass, within the range where the stress acting on the edge of the window glass does not exceed the upper limit allowable stress of 17.7 MPa, when the outer perimeter length of the opposing surface is varied from 34 cm to 76 cm. Therefore, when the distance g between the opposing surface and the window glass is greater than the line representing each outer perimeter length, the stress acting on the edge of the window glass will be 17.7 MPa or less, and the risk of thermal cracking of the window glass can be reduced. Specifically, for example, if the outer perimeter length of the opposing surface is 48 cm and the solar absorptivity of the opposing surface is 60%, the risk of thermal cracking of the window glass can be reduced if the distance g between the opposing surface and the window glass is 4 mm or more. On the other hand, if the distance g between the opposing surface and the window glass is less than 4 mm, the risk of thermal cracking of the window glass cannot be reduced.

[0077] Next, we examined the relationship between the distance g between the opposing surface and the window glass, the solar absorptivity of the opposing surface, and the outer perimeter of the opposing surface when an imaging device with a square-shaped opposing surface (see Figure 5) is mounted near the window glass. The examination method is the same as that used for an imaging device with a right-angled isosceles triangular opposing surface, so a detailed explanation of the examination method is omitted. The examination results are shown in Figure 8. In Figure 8, as in Figure 7, the vertical axis shows the distance g between the opposing surface and the window glass, and the horizontal axis shows the solar absorptivity of the opposing surface.

[0078] Figure 8 plots the solar absorptivity of the opposing surface and the lower limit of the distance between the opposing surface and the window glass, within the range where the stress acting on the edge of the window glass does not exceed the upper limit allowable stress of 17.7 MPa, when the outer circumference of the opposing surface is varied from 40 cm to 69 cm. Similar to Figure 7, in Figure 8, when the distance g between the opposing surface and the window glass is greater than the line indicating each outer circumference, the stress acting on the edge of the window glass will be 17.7 MPa or less, and the risk of thermal cracking of the window glass can be reduced.

[0079] As shown in Figures 7 and 8, the risk of thermal breakage of the window glass increases as the perimeter length of the opposing surface increases. To suppress thermal breakage of the window glass, it is necessary to reduce the solar absorptivity of the opposing surface. When it is not possible to reduce the solar absorptivity of the opposing surface for optical or design reasons, this graph shows that the risk of thermal breakage of the window glass can be reduced by increasing the distance between the opposing surface and the window glass. Furthermore, as shown in Figures 7 and 8, it can be seen that the behavior differs somewhat depending on the shape of the opposing surface. The risk of thermal breakage of the window glass is higher when the opposing surface is square. Therefore, when the opposing surface is square, it is necessary to lower the solar absorptivity of the opposing surface to reduce the risk of thermal breakage of the window glass compared to when the opposing surface is a right-angled isosceles triangle.

[0080] Figure 9 is a combined graph of Figures 7 and 8. In Figure 9, the slope and intercept of each line are plotted. Note that some of the lines shown in Figures 7 and 8 are not strictly straight lines, but such lines can be approximated as straight lines. For this reason, the lines that are not straight lines in Figures 7 and 8 are approximated as straight lines, and their slopes and intercepts are plotted accordingly. From Figure 9, it can be seen that the slope and intercept of each line are approximated by the outer perimeter of the opposing surface, rather than the shape of the opposing surface.

[0081] Next, we derive a function that approximates the plotted slopes (see the solid line in Figure 9). This function is given by the following equation (11): y = 0.038x ２ -0.49x+0.95...(11)

[0082] Next, we derive a function that approximates the plotted intercepts (see the dashed line in Figure 9). This function is given by the following equation (12): y = -0.0032x ２ -0.41x-6.1...(12)

[0083] The lower limit of the distance g (mm) between the opposing surface and the window glass, g0, can be expressed as shown in the following formula (13): g0 = c1 × α + c2 ... (13)

[0084] Furthermore, the c1 (slope) and c2 (intercept) in equation (13) above are determined by the outer circumference S (cm) of the opposing surface, regardless of the shape of the opposing surface, as shown in equations (14) and (15) below: c1 = 0.038S ２ -0.49S+0.95...(14) c2=-0.0032S ２ -0.41S-6.1...(15)

[0085] From the above, equations (1) to (9) are derived.

[0086] This embodiment provides the following effects. In this embodiment, the distance g between the window glass 11 and the opposing surface 111, the solar radiation absorptance α of the opposing surface 111, and the outer circumference S of the opposing surface 111 are in a predetermined relationship. Specifically, the relationship is such that it satisfies the above equations (1) to (4). This makes it possible to suppress localized temperature rise of the window glass 11 caused by the imaging device 100. Therefore, damage to the window glass 11, such as thermal cracking, can be suppressed.

[0087] The effect of suppressing damage due to thermal cracking of the window glass 11 will be explained in detail using Figure 10. As shown in Figure 10, when the shape of the opposing surface is a right-angled isosceles triangle, the outer circumference S of the opposing surface is 39 cm, and the solar absorptivity α of the opposing surface is 75%, then g0 is approximately 2.9 (see equations (13), (3), and (4) above). g0 is the lower limit of the separation distance g (mm) between the opposing surface and the window glass. Therefore, if the separation distance g (mm) between the opposing surface and the window glass is made larger than g0, damage (thermal cracking) to the window glass can be suppressed (see equation (2)). As shown in Figure 10, when g is set to 4.0 mm, which is larger than g0, the stress generated at the edge of the window glass becomes 17.1 MPa. This means that the stress acting on the edge of the window glass is lower than the upper limit allowable stress of 17.7 MPa. Therefore, the judgment is OK, and it can be determined that the effect of suppressing damage to the window glass 11 has been obtained. On the other hand, if g is set to 1.0 mm, which is smaller than g0, the stress generated at the edge of the window glass becomes 18.1 MPa. This means that the stress acting on the edge of the window glass is higher than the upper limit allowable stress of 17.7 MPa. Therefore, the judgment is NG, and it can be determined that the damage suppression effect of the window glass 11 has not been obtained. Thus, it can be understood that the damage suppression effect of the window glass 11 is obtained when the above equations (1) to (4) are satisfied.

[0088] Similarly, when the outer perimeter length S is 48 cm and the solar absorptance α is 60%, it can be understood that the effect of suppressing damage to the window glass 11 can be obtained if conditions (1) to (4) are satisfied. Also, when the shape of the opposing surface is square, it can be understood that the effect of suppressing damage to the window glass 11 can be obtained if conditions (1) to (4) are satisfied.

[0089] Furthermore, in this embodiment, the skirt 114 protrudes from the opposing surface 111. Therefore, when attempting to bring the opposing surface 111 closer to the main surface 11B2 on the interior side of the window glass 11, the skirt 114 and the window glass 11 interfere with each other. As a result, the distance between the opposing surface 111 and the window glass 11 is unlikely to become shorter than the length by which the skirt 114 protrudes from the opposing surface 111 (hereinafter referred to as the "protrusion length"). Thus, it is possible to prevent the distance between the window glass 11 and the opposing surface 111 from becoming shorter than the desired distance.

[0090] Furthermore, the protruding length of the skirt 114 is set to be greater than or equal to a predetermined value derived from the solar radiation absorptivity α of the opposing surface 111 and the outer circumference length S of the opposing surface 111. The predetermined value derived from the solar radiation absorptivity α of the opposing surface 111 and the outer circumference length S of the opposing surface 111 is set to the distance between the opposing surface 111 and the window glass 11 that can suppress localized heating of the window glass 11 caused by the imaging device 100. For this reason, the length of the skirt 114 is longer than the distance (length) that suppresses localized heating of the window glass 11. Therefore, damage to the window glass 11, such as thermal cracking, can be suppressed.

[0091] Furthermore, when imaging the outside of the window glass 11 from the inside at night, the reflected image caused by the reflection of the inside image off the window glass 11 is projected onto the outside image, overlapping with the outside image and making it difficult to see the outside image. On the other hand, in this embodiment, the skirt 114 is provided over the entire circumferential area of ​​the outer periphery of the opposing surface 111. As a result, when the skirt 114 and the window glass 11 come into contact, the space formed between the opposing surface 111 and the window glass 11 becomes a closed space. Therefore, the projection of the reflected image caused by the reflection of the inside image off the window glass 11 can be suppressed.

[0092] Furthermore, in this embodiment, the thickness of the skirt 114 is set to 10 mm or less. This makes it possible to reduce the weight of the imaging device 100.

[0093] Furthermore, in this embodiment, the area of ​​the opposing surface 111 is 1000 cm². ２ The following is stated. This makes it possible to suppress damage to the window glass 11, such as thermal cracking.

[0094] Furthermore, in this embodiment, the imaging device 100 is installed within 10 cm of the edge of the window glass 11 when viewed from a direction perpendicular to the main surface 11B2 on the interior side of the window glass 11. This helps to suppress damage to the window glass 11, such as thermal cracking.

[0095] Furthermore, in this embodiment, the solar radiation absorption rate of the opposing surface 111 is set to 85% or less. This helps to suppress damage to the window glass 11, such as thermal cracking.

[0096] In the above calculation using FEM, the window glass 11 is assumed to be double-glazed glass. Double-glazed glass is a type of glass commonly used along with single-pane glass, etc., but the applicant considered double-glazed glass to be more susceptible to thermal cracking than other types of glass. In particular, the above analysis used a type of double-glazed glass that is especially susceptible to thermal cracking as the window glass. Specifically, a double-glazed glass in which both glass plates are transparent was used. When an electronic device is placed in contact with double-glazed glass, for example, a double-glazed glass composed of transparent glass is more susceptible to thermal cracking than a double-glazed glass in which one of the two glass plates has a heat-reflective film or includes heat-absorbing glass. The reason for this susceptibility to thermal cracking is described below.

[0097] Thermal breakage of window glass occurs due to the temperature difference between the glass surface heated by solar radiation and the glass edges surrounded by the window frame (the heat capacity of the building structure also plays a significant role). Generally, this temperature difference is larger in winter than in summer, and the risk of thermal breakage is generally higher in winter. Double-glazed glass tends to reach higher temperatures than single-pane glass. This is because the interior side of double-glazed glass tends to reach higher temperatures due to the insulating effect of the air layer. Thus, double-glazed glass tends to reach higher temperatures and has a higher risk of thermal breakage. In such cases, it is generally the interior side of the glass that breaks. If no object (for example, the imaging device 100 according to this embodiment) is installed near the window glass, using double-glazed glass that includes glass with a heat-reflective film or heat-absorbing glass that is colored will further increase the temperature of the window glass, generally increasing the risk of thermal breakage. On the other hand, as in this embodiment, when an object (an electronic device such as the imaging device 100) is placed near the window glass, using glass with a heat-reflective film or heat-absorbing glass reduces solar radiation, thus generally inhibiting the heating of the object. This tendency is particularly pronounced when an object with a high solar radiation absorption rate, such as the imaging device 100, is placed opposite the window glass 11, as in this embodiment. Therefore, in this embodiment, double-glazed glass with two transparent glass panes without such films is less effective than double-glazed glass containing glass with a heat-reflective film or heat-absorbing glass, as it results in a greater amount of solar radiation incident on the imaging device 100 and a greater heating, thus increasing the risk of thermal cracking of the window glass.

[0098] For the reasons stated above, the window glass used in the above calculation is assumed to be double-glazed glass made of transparent glass, which is particularly susceptible to thermal breakage. Furthermore, from the calculation results above, it can be understood that, according to this embodiment, damage can be sufficiently suppressed even with double-glazed glass made of transparent glass, which is susceptible to thermal breakage.

[0099] <Reducing reflections using the window frame 12> Next, we will explain how to reduce reflections using the window frame 12. The imaging device 100 preferably uses the window frame 12 to reduce reflections so that it can capture images of the outside even when the indoor lights are on at night. This will be explained using Figures 11A, 11B, 12A, and 12B. Also, although this explanation describes a configuration in which the imaging device 100 is not equipped with a skirt 114, the same applies to the imaging device 100 equipped with a skirt 114.

[0100] Figures 11A and 11B are not embodiments, but diagrams illustrating an example of why reflections are included in the image captured by the comparative imaging device 50. The comparative imaging device 50 has the same camera configuration as the imaging device 100 of the embodiment shown in Figure 2. The comparative imaging device 50 will be described as including a lens 130 and an imaging unit 140, similar to the imaging device 100 of the embodiment.

[0101] Figure 11A shows an example of an XZ cross-section of a portion of a window pane 11 made of double-glazed glass, viewed from the +Y direction. Figure 11A also shows a simplified image capture device 50. Let C be the optical axis of the lens 130, and θx be the horizontal field of view of the image capture device 50. The position in the Y direction of the XZ cross-section shown in Figure 11A is the position passing through the optical axis C of the lens 130. For simplicity, the image capture device 50 is assumed to be rectangular in XZ plane view and symmetrical with respect to the optical axis C of the lens 130.

[0102] Here, using Figure 11A, we will first explain the configuration of the window glass 11, which is made of double-glazed glass that is less likely to reduce reflections compared to single-pane glass, and then explain why the reflection of the reflected image from the window glass 11 is captured by the imaging device 50.

[0103] <Structure of window glass 11 made of double-glazed glass> Window glass 11 made of double-glazed glass has a glass plate 11A, a glass plate 11B, and a heat-reflective film 11C. Glass plate 11A is an example of a first glass plate on the exterior side, and glass plate 11B is an example of a second glass plate on the interior side.

[0104] Glass plate 11A has an outer main surface 11A1 and an inner main surface 11A2. Glass plate 11B has an outer main surface 11B1 and an inner main surface 11B2. Main surface 11A1 is an example of a first main surface, and main surface 11A2 is an example of a second main surface. Main surface 11B1 is an example of a third main surface, and main surface 11B2 is an example of a fourth main surface.

[0105] Main surface 11A1 is located on the exterior side of main surface 11A2, and main surface 11A2 is located on the interior side of main surface 11A1. The exterior side of main surface 11A1 means that it is located on the exterior side of main surface 11A2, and the interior side of main surface 11A2 means that it is located on the interior side of main surface 11A1. The same applies to main surfaces 11B1 and 11B2.

[0106] The glass plates 11A and 11B maintain a constant distance in the Z direction by placing spacers (not shown) between them. The glass plates 11A and 11B have a constant thickness and are parallel to the XY plane. The heat-reflective film 11C is formed on the main surface 11A2 as an example. In Figures 11A, 11B, 12A, and 12B, the thickness of the heat-reflective film 11C in the Z direction is exaggerated relative to the thickness of the glass plates 11A and 11B in the Z direction. Here, as an example, a configuration in which the heat-reflective film 11C is provided on the main surface 11A2 on the indoor side of the outdoor glass plate 11A is described, but the heat-reflective film 11C may also be provided on the main surface 11B1 on the outdoor side of the indoor glass plate 11B. The material of the spacer is, for example, metal or resin. The metal used for the spacer is, for example, aluminum or stainless steel.

[0107] <Reasons why double-glazed glass is less effective at reducing reflected images than single-pane glass> In window glass 11 made of double-glazed glass, the distance between the main surfaces 11A1 and 11A2 of the glass plate 11A located on the exterior side and the lens 130 is longer by the thickness of the spacer and the thickness of the glass plate 11, making it easier for reflected images to be captured. Furthermore, in double-glazed glass, a highly reflective heat-reflective film 11C is provided on the interior main surface 11A2 of the exterior glass plate 11A, or on the exterior main surface 11B1 of the interior glass plate 11B, which further emphasizes the reflected image. For these reasons, it is more difficult to reduce reflected images with double-glazed glass than with single-pane glass.

[0108] <Reasons why the reflected image is captured by the imaging device 50> Unless otherwise specified below, the following explanation will describe the case where the imaging device 50 captures the outside through the window glass 11 from the inside when the lights are on at night. Nighttime is, for example, the time from sunset to sunrise. When the lights are turned on at night, the outside is dark, while the inside is bright.

[0109] When the reflectance of the heat-reflective film 11C is higher than that of the glass plates 11A and 11B, the reflection of the image produced when viewing the window glass 11 from the inside is more visible to the human eye when the reflection of the image produced by the heat-reflective film 11C is greater than the reflection of the reflection of the image produced by the glass plates 11A and 11B. For this reason, the reflection of the image produced by the heat-reflective film 11C is dominant in the image captured by the imaging device 50, rather than the reflection of the reflection of the reflection of the reflection of the reflection of the reflection of the reflection of the reflection of the reflection of the heat-reflective film 11C.

[0110] Figure 11A shows the optical path of light arriving from the +Z direction side to the -Z direction side of the imaging device 50 and reflected back to the +Z direction side by the heat reflective film 11C with a thick arrow. Also in Figure 11A, the horizontal field of view θx is divided into region (1) and region (2). Region (1) is the region on the indoor side where light directed toward the window glass 11 does not reach the heat reflective film 11C. Region (2) is the region on the indoor side where light directed toward the window glass 11 does reach the heat reflective film 11C.

[0111] In Figure 11A, the range of the horizontal field of view θx and the boundaries of regions (1) and (2) are shown by four dashed lines. The four dashed lines are folded back toward the lens 130 on the surface of the heat-reflective film 11C on the +Z side, in order to indicate the boundaries of the regions through which light traveling from the +Z side of the imaging device 50 toward the -Z side and reflected toward the +Z side by the heat-reflective film 11C passes.

[0112] Furthermore, Figure 11B is used here to make the range and regions (1) and (2) of the horizontal field of view θx easier to see. In Figure 11A, the incident light that arrives at the heat reflective film 11C on the indoor side is reflected back to the -Z direction side of the heat reflective film 11C in Figure 11B, and is shown as light arriving at the window glass 11 from the -Z direction side. For this reason, in Figure 11B, the four dashed lines representing the range and regions (1) and (2) of the horizontal field of view θx are shown as straight lines, and the optical path of the reflected light, indicated by the thick arrow, is shown linearly as the optical path of light that arrives at the window glass 11 from the -Z direction side, passes through the heat reflective film 11C, and reaches the lens 130.

[0113] Figure 11B also shows the imager mirror image 50R, which is a mirror image of the imager 50 with respect to the heat-reflective film 11C, and the lens mirror image 130R, which is a mirror image of the lens 130. The imager mirror image 50R and the lens mirror image 130R have shapes that are symmetrical with respect to the heat-reflective film 11C, when the heat-reflective film 11C is considered as a plane, with respect to the imager 50 and the lens 130.

[0114] Note that the XYZ coordinates shown in Figure 11B are for the actual window glass 11 and the imaging device 50, and do not include the imaging device mirror image 50R, the lens mirror image 130R, or the optical path.

[0115] The central region (1) of the horizontal field of view θx is the region that is in the shadow of the imaging device 50 and does not experience light reflection from the heat-reflective film 11C. Region (1) is the region located between two dashed lines passing through the center of the lens 130 and the two corners of the housing of the imaging device 50 on the window glass 11 side. The optical path of light within region (1) will be explained below using Figures 11A and 11B.

[0116] In Figure 11A, light (arrow 1A) passing through region (1) on the indoor side toward the heat-reflective film 11C is blocked by the imaging device 50 and does not reach the heat-reflective film 11C, and is not reflected by the heat-reflective film 11C. Therefore, the light within region (1) does not enter the lens 130 and is not imaged by the imaging unit 140. This can be explained in Figure 11B as follows. In Figure 11B, light (arrow 1A) passing through region (1) toward the heat-reflective film 11C is blocked by the imaging device mirror image 50R and does not reach the heat-reflective film 11C. Therefore, the light (arrow 1A) within region (1) does not enter the lens 130 and is not imaged by the imaging unit 140.

[0117] Region (2) of the horizontal field of view θx is the region where light reflection occurs by the heat-reflective film 11C without being cast in the shadow of the imaging device 50. Region (2) consists of two regions located on both sides of region (1) (the -X direction side and the +X direction side). Region (2) consists of two regions obtained by excluding the central region (1) from the region included in the horizontal field of view θx in the XZ plane view. The optical path of light within region (2) will be explained as follows using Figures 11A and 11B.

[0118] In Figure 11A, light (arrow 2A) traveling through region (2) on the indoor side toward the heat-reflective film 11C is not blocked by the imaging device 50, and therefore reaches the heat-reflective film 11C and is reflected. The light reflected by the heat-reflective film 11C is captured by the imaging unit 140 after passing through the lens 130. In contrast, in Figure 11B, light (arrow 2A) traveling through region (2) toward the heat-reflective film 11C is not blocked by the imaging device mirror image 50R, and therefore reaches the heat-reflective film 11C and is reflected. In Figure 11B, the light reflected by the heat-reflective film 11C is represented as light that passes through the heat-reflective film 11C and travels in a straight line. The light reflected by the heat-reflective film 11C is captured by the imaging unit 140 after passing through the lens 130. Therefore, the image captured by the imaging device 50 includes the reflection of the light (arrow 2A) that passed through region (2).

[0119] <Reasons why the imaging device 100 can reduce reflections> Figures 12A and 12B illustrate an example of why the imaging device 100 of this embodiment can reduce reflections. First, we will explain using Figure 12A.

[0120] Figure 12A, similar to Figure 11B, shows an example of an XZ cross-section of a portion of a window pane 11 made of double-glazed glass, viewed from the +Y direction. The Y-direction position of the XZ cross-section shown in Figure 12A is the position passing through the optical axis C of the lens 130. Figure 12A also shows a simplified representation of the imaging device 100. The optical axis of the lens 130 is C. For the sake of simplicity, the imaging device 100 is assumed to be rectangular in XZ plane view and symmetrical with respect to the optical axis C of the lens 130. The horizontal field of view of the imaging device 100 is denoted as θx.

[0121] Figure 12A, like Figure 11B, shows the imager mirror image 100R and the lens mirror image 130R, which are mirror images of the imaging device 100 and the lens 130. Also in Figure 12A, the window frame 12 and the window frame mirror image 12R, which is a mirror image of the window frame 12. The window frame 12 shown in Figure 12A is more specifically the frame portion 12Y that extends in the Y-axis direction on the +X-axis side of the window glass 11, so it is denoted by the reference numeral 12Y in parentheses, but unless otherwise specified, it will be described as the window frame 12.

[0122] The imager image 100R, the lens image 130R, and the window frame image 12R have shapes that are symmetrical with respect to the heat reflective film 11C, when the heat reflective film 11C is considered as a plane, with respect to the imager 100, the lens 130, and the window frame 12, respectively.

[0123] Note that the XYZ coordinates shown in Figure 12A are the coordinates for the actual window glass 11 and the imaging device 100, and unless otherwise specified, the imaging device mirror image 100R, the lens mirror image 130R, the window frame mirror image 12R, and the optical path are not used.

[0124] In Figure 12A, the horizontal field of view θx is divided into three regions: region (1), two regions (2), and one region (3), as shown by the five dashed lines.

[0125] The central region (1) of the horizontal field of view θx is the same as region (1) shown in Figure 11B. Light that passes through region (1) on the indoor side and heads toward the heat-reflective film 11C is blocked by the imaging device 100 and is not reflected by the heat-reflective film 11C, so it does not enter the lens 130 and is not imaged by the imaging unit 140.

[0126] Region (3) is the outer part of region (2) on the +X side shown in Figure 11B at the horizontal angle of view θx, and is the region where light is blocked by the window frame mirror image 12R. Region (3) is the region between two dashed lines: the dashed line connecting the +X side end of the horizontal angle of view θx to the center of the lens 130, and the dashed line connecting the corner on the -X side of the window frame mirror image 12R on the -Z side to the center of the lens 130.

[0127] Light that passes through region (3) on the indoor side and heads toward the heat-reflective film 11C is blocked by the window frame mirror image 12R and is not reflected by the heat-reflective film 11C. Therefore, it does not enter the lens 130 and is not imaged by the imaging unit 140. As a result, the imaging device 100 can eliminate the reflection of reflected images caused by light passing through the outer part of the region (2) on the +X side shown in Figure 11B in the horizontal field of view θx.

[0128] Furthermore, since the region (2) on the -X side is the same as the region (2) on the -X side shown in Figure 11B, the image captured by the imaging device 100 includes reflections of light (arrow 2A) that has passed through the region (2) on the -X side.

[0129] In Figure 12A, region (2) exists between region (1) and region (3), but it is significantly narrower compared to region (2) on the +X side shown in Figure 11B. The imaging device 100 can reduce the reflection of reflective images caused by light incident from the window frame 12 side of the optical axis C of the lens 130 being reflected by the heat reflective film 11C by utilizing the window frame 12. On the +X side of the optical axis C of the lens 130, the window frame 12 is used as a lens hood.

[0130] Furthermore, Figure 12B shows the imaging device 100 in contact with the main surface 11B2 on the interior side of the window glass 11. By bringing the imaging device 100 closer to the window glass 11 than in Figure 12A, the region (2) between regions (1) and (3) can be made narrower or eliminated compared to the region (2) on the +X direction side shown in Figure 12A. If the imaging device 100 is installed as shown in Figure 12B, the reflection of reflected images caused by reflected light from light incident from the window frame 12 side of the optical axis C can be eliminated, and the reflection of reflected images caused by reflection by the heat reflective film 11C can be reduced compared to the imaging device 100 shown in Figure 12A.

[0131] Thus, in order to reduce the reflection of reflected images caused by reflection by the heat-reflective film 11C using a structure in contact with the window glass 11, such as the window frame 12, the position of the imaging device 100 relative to the window frame 12 (structure) and the window glass 11 can be set as follows, for example, using the horizontal field of view θx, distance Dx, and distance Dz.

[0132] <Horizontal field of view θx, distance Dx, distance Dz> The imaging device 100 defines the horizontal field of view θx, the distance Dx in the X direction between the lens 130 and the window frame 12, and the distance Dz between the lens 130 and the heat-reflective film 11C, as shown in Figure 12A, in order to reduce the reflection of reflected images due to the reflection of light by the heat-reflective film 11C. Here, the horizontal field of view θx and distance Dx are defined in relation to the frame portion 12Y of the window frame 12, but in relation to the frame portion 12X of the window frame 12, it is sufficient to define the vertical field of view θy of the lens 130 and the distance Dy in the Y direction between the lens 130 and the frame portion 12X. Distance Dz is common. The horizontal field of view θx and vertical field of view θy are examples of the field of view of the imaging device 100.

[0133] <Horizontal field of view θx> The imaging device 100 has, for example, a horizontal field of view θx of 40 degrees or more, more preferably 70 degrees or more and 100 degrees or less. Since the imaging device 100 is intended to be used, for example, as a security surveillance camera, a certain degree of field of view is required.

[0134] To explain the horizontal field of view θx, we will use Figures 13AA to 13AF. Figures 13AA to 13AF show examples of images obtained by fixed-point imaging with a camera when the horizontal field of view θx is set to 40 degrees, 50 degrees, 70 degrees, 80 degrees, 105 degrees, and 120 degrees.

[0135] As shown in Figures 13AA to 13AF, in the image with a horizontal field of view θx of 40 degrees (Figure 13AA, upper left), the building is visible on the left side, but not entirely. The building is, for example, a 10-story building. In the image with a horizontal field of view θx of 50 degrees (Figure 13AB, upper center), the entire building is visible on the left side, but the image area is not very wide. In the image with a horizontal field of view θx of 70 degrees (Figure 13AC, upper right), the entire building and its perimeter are included. In the image with a horizontal field of view θx of 80 degrees (Figure 13AD, lower left), the entire building and its perimeter are included, and the image covers an even wider area than in the 70-degree case. In the image with a horizontal field of view θx of 105 degrees (Figure 13AE, lower center), the entire building and its perimeter are included, but the image is distorted. In the image with a horizontal field of view θx of 120 degrees (Figure 13AF, lower right), the image distortion is even stronger than in the 105-degree case.

[0136] When imaging was performed with the horizontal field of view θx set to a value less than 40 degrees and a value greater than 120 degrees, it was found that, for example, a horizontal field of view θx of around 30 degrees resulted in too narrow a field of view, and anything less than 40 degrees was difficult to use as a camera. For these reasons, it is preferable that the horizontal field of view θx be 40 degrees or greater.

[0137] Furthermore, as can be seen from the six images shown in Figures 13AA to 13AF, it is more preferable that the horizontal field of view θx be 70 degrees or more, or 100 degrees or less. This is because a horizontal field of view θx of 70 degrees or more allows imaging of a 10-story building and a wide area surrounding it, while an angle of view of 100 degrees or less results in almost no distortion of the image.

[0138] Based on the above, the horizontal field of view θx is preferably 40 degrees or more, and more preferably 70 degrees or more or 100 degrees or less. The same applies to the vertical field of view θy.

[0139] <Dx in the X direction between lens 130 and window frame 12> The distance Dx in the X direction between lens 130 and window frame 12 is the distance in the X direction between the center of lens 130 and the wall portion of window frame 12 on the -X direction side, as shown in Figure 12A. Here, the X direction is the direction parallel to the main surface 11B2 of the window glass 11.

[0140] The distance Dx is preferably 0 mm or more and 180 mm or less. The reason for this will be explained using Figures 13B and 13C. Figure 13B is a diagram showing an example of simulation results calculated by setting the reflection reduction rate Rx (%) with respect to the distance Dx in 10-degree increments from 40 degrees to 100 degrees horizontally. Figure 13C is a diagram showing an example of calculation results when the horizontal field of view θx shown in Figure 13B is 40 degrees.

[0141] Here, the reflection reduction rate Rx (%) is the value obtained by dividing the length X3 by the length Xt (X3 / Xt), using the length Xt in the X direction of the portion of the surface of the heat-reflective film 11C on the +Z direction side that is included in the horizontal field of view θx (see Figure 12A) and the length X3 in the X direction of the portion of the surface of the heat-reflective film 11C on the +Z direction side that is included in region (3) (see Figure 12A). The reflection reduction rate Rx (%) represents the ratio to which reflected light is reduced in the portion of the surface of the heat-reflective film 11C on the +Z direction side that is included in the horizontal field of view θx.

[0142] The calculation was performed with the distance Dz set to 1 mm. Furthermore, assuming that the main surface 11A1 on the exterior side of the window glass 11 and the outer surface of the window frame 12 parallel to the XY plane in the -Z direction coincide in the Z direction, the calculation was performed with the length of the window frame 12 in the Z direction set to 500 mm. Generally, in buildings such as office buildings, there is a window frame 12 that has a sufficient length in the Z direction toward the interior side from the main surface 11A1 on the exterior side of the window glass 11. Also, even if the length of the window frame 12 itself in the Z direction is shorter than 500 mm, it is assumed that there is a structure such as an interior wall that extends continuously in the +Z direction from the window frame 12. Therefore, the calculation was performed with the length of the window frame 12 in the Z direction set to 500 mm.

[0143] As shown in Figure 13B, the reflection reduction rate R reached a nearly equal peak value at a distance Dx of approximately 5 mm for all horizontal angles of view θx. Furthermore, it showed a tendency to decrease nearly linearly as the distance Dx increased for all horizontal angles of view θx. Among the seven horizontal angles of view θx from 40 to 100 degrees, the reflection reduction rate R was lowest at the narrowest angle of view of 40 degrees, and tended to increase as the horizontal angle of view θx increased. This is thought to be because, as the horizontal angle of view θx increases, the area occupied by the window frame 12 within the horizontal angle of view θx increases, resulting in more light being blocked by the window frame 12 and a reduction in the reflection of reflected images based on reflected light.

[0144] Furthermore, the reflection reduction rate R for the narrowest horizontal field of view θx, 40 degrees, was 1% at a distance Dx of 180 mm, but became 0% when the distance exceeded 180 mm and reached 190 mm.

[0145] From the above, it was found that in order to reduce the reflection of reflected images caused by reflection by the heat-reflective film 11C using a structure in contact with the window glass 11, such as the window frame 12, one example is to set the position of the imaging device 100 relative to the window frame 12 (structure) and the window glass 11 such that the horizontal field of view θx is 40 degrees or more and the distance Dx is 0 mm or more and 180 mm or less. The reflection reduction rate Rx (%) is preferably greater than 0% and 50% or less. If Rx is greater than 0% and 50% or less, it is easier to capture images of the outside even when the indoor lights are on at night without using a lens hood. Rx is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. Also, Rx may be 45% or less, 40% or less, or 35% or less.

[0146] Furthermore, the reflection reduction rate Rx (%), which represents the ratio by which reflected light is reduced in the portion of the surface of the heat-reflective film 11C on the +Z direction side that is included in the horizontal field of view θx, has been explained here. However, since there is a frame portion 12X of the window frame 12 on the +Y direction side of the imaging device 100, the reflection reduction rate Ry (%) can be similarly calculated for the vertical field of view θy. The reflection reduction rate Ry (%) represents the ratio by which the reflection of the reflected image based on reflected light is reduced by the frame portion 12X in the portion of the surface of the heat-reflective film 11C on the +Z direction side that is included in the vertical field of view θy. The degree to which the imaging device 100 can reduce the reflection of the reflected image using the window frame 12 is the sum of the reflection reduction rates Rx and Ry minus the value of the overlapping portion of the reflection reduction rates Rx and Ry. It is preferable that the reflection reduction rate Ry (%) is greater than 0% and 50% or less. If Ry is greater than 0% and less than or equal to 50%, it is easier to capture images of the outside even when the indoor lights are on at night without using a lens hood. Ry is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. In addition, Ry may be 45% or less, 40% or less, or 35% or less.

[0147] <Distance Dz between lens 130 and heat-reflective film 11C> The distance Dz between lens 130 and heat-reflective film 11C is the distance in the Z direction between the apex of lens 130, which is composed of a convex lens protruding in the -Z direction, and the surface (reflective surface) of heat-reflective film 11C on the +Z direction side. If the window glass 11 is double-glazed, the distance Dz will vary depending on the thickness of the spacer between glass plates 11A and 11B.

[0148] The lens 130 is provided in the opening of the recess 131 of the holder 131 of the case 110. Preferably, the vertex of the lens 130 on the -Z direction side is recessed in the +Z direction compared to the first surface 111 of the case 110, but the vertex of the lens 130 on the -Z direction side and the first surface 111 may be flush. Also, in Figures 12A and 12B, the heat-reflective film 11C is provided on the main surface 11A2 on the indoor side of the outdoor side glass plate 11A, but it may also be provided on the main surface 11B1 on the outdoor side of the indoor side glass plate 11B.

[0149] Furthermore, if the imaging device 100 is positioned away from the window glass 11 in the +Z direction, the distance in the Z direction between the window glass 11 and the lens 130 increases. This widens region (2) between regions (1) and (3) shown in Figure 12A (the angle of region (2) in the XZ plane view increases), and the reflection of reflected images based on reflected light from light incident from the window frame 12 side of the optical axis C increases. From this viewpoint, simulations have shown that it is preferable for the distance Dz to be 100 mm or less.

[0150] Based on the above, when the reflectance of the heat-reflective film 11C is higher than the reflectance of the window glass 11, it is preferable that the distance Dz between the lens 130 and the heat-reflective film 11C be 0 mm or more and 100 mm or less. This is to effectively reduce reflections caused by the heat-reflective film 11C.

[0151] Furthermore, even if the window glass 11 is double-glazed and has a heat-reflective film 11C, if the reflectivity of the heat-reflective film 11C is lower than the reflectivity of the window glass 11, reflections from the window glass 11 will be dominant. In this case, by treating the distance in the Z direction between the focal point of the lens 130 and the outer main surface 11A1 of the outer glass plate 11A of the double-glazed window glass 11 as the aforementioned distance Dz, and setting the distance Dz between the focal point of the lens 130 and the outer main surface 11A1 of the outer glass plate 11A of the double-glazed window glass 11, reflections from the window glass 11 can be effectively reduced.

[0152] In this explanation, we have used Figures 11A to 12B to describe the case where the window glass 11 is double-glazed, but as mentioned above, the window glass 11 may also be single-pane glass. If the window glass 11 is single-pane glass and a heat-reflective film is provided on the exterior main surface 11A1 (see Figure 1B) or the interior main surface 11B2 (see Figure 1B), and the reflectance of the heat-reflective film is higher than the reflectance of the window glass 11, then the distance Dz is the distance in the Z direction between the focal point of the lens 130 and the heat-reflective film, as in the case of double-glazed window glass 11.

[0153] Furthermore, if the window glass 11 is single-pane glass and does not have a heat-reflective coating 11C, reflections from the window glass 11 will occur. For this reason, if the window glass 11 is single-pane glass and does not have a heat-reflective coating 11C, the distance in the Z direction between the focal point of the lens 130 and the outer main surface 11A1 (see Figure 1B) of the window glass 11, which is made of single-pane glass, is treated as the above-mentioned distance Dz, and by setting the distance Dz between the focal point of the lens 130 and the outer main surface 11A1 of the window glass 11, which is made of single-pane glass, reflections from the window glass 11 can be effectively reduced.

[0154] Furthermore, even if the window glass 11 is single-pane glass and has a heat-reflective coating 11C, if the reflectivity of the heat-reflective coating 11C is lower than the reflectivity of the window glass 11, reflections from the window glass 11 will be dominant. In this case, by treating the distance in the Z direction between the focal point of the lens 130 and the outer main surface 11A1 (see Figure 1B) of the window glass 11, which is made of single-pane glass, as the aforementioned distance Dz, and setting the distance Dz between the focal point of the lens 130 and the outer main surface 11A1 of the window glass 11, which is made of single-pane glass, reflections from the window glass 11 can be effectively reduced.

[0155] In a window pane 11 made of single-pane glass without a heat-reflective coating 11C, light arriving from the indoor side is reflected back to the indoor side at the indoor main surface 11B2 (see Figure 1B) and the outdoor main surface 11A1 (see Figure 1B). The reflection at the outdoor main surface 11A1 occurs when light transmitted through the indoor main surface 11B2 is reflected by the inner surface of the window pane 11 on the outdoor main surface 11A1. Since the window pane 11 has a visible light reflectance of approximately 4% at both the main surface 11B2 and the main surface 11A1, it has a total visible light reflectance of approximately 8%.

[0156] Thus, even when the window glass 11 is single-pane glass and does not have a heat-reflective coating 11C, the reflection of the reflective image can be reduced by setting the position of the imaging device 100 so that the horizontal field of view θx, distance Dx, and distance Dx satisfy the above-described conditions, similar to the case described above when the window glass 11 is double-pane glass and has a heat-reflective coating 11C.

[0157] <Reflection Reduction Rate Rx (%) with respect to Distance Dx> Figure 14 is a diagram illustrating an example of the reflection reduction rate Rx (%) with respect to distance Dx in the imaging device 100 of the embodiment.

[0158] Figure 14, similar to Figure 12A, shows an example of an XZ cross-section of a portion of a window pane 11 made of double-glazed glass, viewed from the +Y direction. The Y-direction position of the XZ cross-section shown in Figure 14 is the position passing through the optical axis C of the lens 130. Figure 14 also shows a simplified image capture device 100. The optical axis of the lens 130 is C. For the sake of simplicity, the image capture device 100 is assumed to be rectangular in XZ plane view and symmetrical with respect to the optical axis C of the lens 130. Note that the horizontal field of view θx of the image capture device 100 is larger than the horizontal field of view θx in Figure 12A.

[0159] Figure 14, like Figure 12A, shows the imager mirror image 100R and the lens mirror image 130R, which are mirror images of the imaging device 100 and the lens 130. Also in Figure 14, the window frame 12 and the window frame mirror image 12R, which is a mirror image of the window frame 12. The window frame 12 shown in Figure 14 is more specifically the frame portion 12Y that extends in the Y-axis direction on the +X-axis side of the window glass 11, so it is denoted by the reference numeral 12Y in parentheses, but unless otherwise specified, it will be described as the window frame 12.

[0160] Furthermore, in Figure 14, in addition to the window frame 12, an exterior window frame 12A is provided. The window frame 12A protrudes outward (towards the -Z direction) from the exterior main surface 11A of the glass plate 11A. The width of the window frame 12A in the X direction is, for example, equal to the width of the window frame 12 in the X direction. The length of the window frame 12A in the Z direction is shorter than the length of the window frame 12 in the Z direction, and the -Z direction end of the window frame 12A is located towards the +Z direction from the -Z direction end of the window frame mirror image 12R. Therefore, the position of the -Z direction end of the window frame mirror image 12R is equal to the position of the -Z direction end of the window frame mirror image 12R shown in Figure 12A.

[0161] The imager image 100R, the lens image 130R, and the window frame image 12R have shapes that are symmetrical with respect to the heat reflective film 11C, when the heat reflective film 11C is considered as a plane, with respect to the imager 100, the lens 130, and the window frame 12, respectively.

[0162] Note that the XYZ coordinates shown in Figure 14 are the coordinates for the actual window glass 11 and the imaging device 100, and unless otherwise specified, the imaging device mirror image 100R, lens mirror image 130R, window frame mirror image 12R, and optical path are not used.

[0163] Figure 14 mainly shows the portion on the +X side of the optical axis C, omitting a portion of the portion on the -X side of the optical axis C. In Figure 14, in addition to regions (1) to (3), regions (4) and (5) are shown on the +X side of the optical axis C. In Figure 14, regions (1) to (5) are all within the range of the horizontal field of view θx. Regions (1) and (2) are the same as regions (1) and (2) shown in Figure 12A.

[0164] In Figure 14, region (3) is the part outside the horizontal field of view θx of region (2) on the +X side shown in Figure 14, and is the region where light is blocked by the window frame mirror image 12R but not by the window frame 12A as a real image. Region (3) is the region between two dashed lines: a dashed line connecting the corner on the -X side of the window frame mirror image 12R on the -Z side and the center of the lens 130, and a dashed line connecting the corner on the -X side of the window frame 12A on the -Z side and the center of the lens 130.

[0165] Region (4) is the part outside of region (3) in the horizontal field of view θx, and is the region between two dashed lines: one connecting the corner on the -Z side of the window frame 12A on the -X side and the center of the lens 130, and the other connecting the +X side edge of the surface on the +Z side of the heat reflective film 11C and the center of the lens 130. Region (4) is the region where light is blocked by the window frame 12A as a real image.

[0166] Region (5) is the part outside of region (4) in the horizontal field of view θx, and is the region between two dashed lines: the dashed line connecting the +X side edge of the +Z side surface of the heat reflective film 11C to the center of the lens 130, and the dashed line connecting the +X side edge of the horizontal field of view θx to the center of the lens 130.

[0167] Light 3A that passes through region (3) on the indoor side and heads toward the heat-reflective film 11C is blocked by the window frame mirror image 12R and is not reflected by the heat-reflective film 11C. Therefore, it does not enter the lens 130 and is not imaged by the imaging unit 140. As a result, the reflection of light 3A passing through region (3) shown in Figure 14 can be eliminated.

[0168] Furthermore, the light rays 4A and 5A passing through regions (4) and (5), like the light 3A in region (3), are not reflected by the heat-reflective film 11C and do not enter the lens 130. However, since a window frame 12A exists as a real image in regions (4) and (5), the light rays 4A and 5A do not contribute to reducing the reflection of the reflected image.

[0169] Even when a window frame 12A is present, the imaging device 100 can reduce the reflection of reflective images caused by light incident from the window frame 12 side of the optical axis C of the lens 130 being reflected by the heat-reflective film 11C by utilizing the window frame 12. On the +X side of the optical axis C of the lens 130, the window frame 12 is used as a lens hood.

[0170] In order to reduce the reflection of reflected images due to the reflection of light by the heat-reflective film 11C, the imaging device 100 defines the horizontal field of view θx, the distance in the X direction Dx between the lens 130 and the window frame 12, and the distance Dz between the lens 130 and the heat-reflective film 11C, as shown in Figure 14, as well as the distances d, e, f, and g shown in Figure 14.

[0171] Distance d is the distance in the Z direction between the +Z end of the window frame 12 and the heat reflective film 11C, and is equal to the distance in the Z direction between the -Z end of the window frame mirror image 12R and the heat reflective film 11C. Distance e is the distance between the heat reflective film 11C and the -Z end of the window frame 12A. Distance f is the length between the lens 130 and the -Z end of the window frame 12A, where f = Dz + e. Distance g is the length between the lens 130 and the -Z end of the window frame mirror image 12R, where g = Dz + d.

[0172] Here, the horizontal field of view θx, distance Dx, distance d, distance e, distance f, and distance g in the XZ plane view are defined in relation to the frame portion 12Y of the window frame 12. However, in relation to the frame portion 12X of the window frame 12, it is sufficient to define the vertical field of view θy of the lens 130, the distance Dy in the Y direction between the lens 130 and the frame portion 12X, and the distances d, e, f, and g in the XZ plane view. Distance Dz is common to all. The horizontal field of view θx and the vertical field of view θy are examples of the field of view of the imaging device 100.

[0173] In Figure 14, the optical axis C of the lens 130 is parallel to the length direction in the Z direction. However, to explain a more general situation, let θc be the angle that the optical axis C makes with the Z direction. θc is defined as an angle that tilts towards the +X direction when viewed from the +Y direction, in a clockwise direction from the -Z direction, and a negative angle when tilting towards the -X direction when counterclockwise from the -Z direction.

[0174] Whether the -X-direction end of the window frame 12A is captured on the -Z-direction side when viewed from lens 130 depends on whether f × tan(θx / 2 + θc) > Dx. If f × tan(θx / 2 + θc) is greater than Dx, the window frame 12A is captured when viewed from lens 130. If f × tan(θx / 2 + θc) is less than or equal to Dx, the window frame 12A is not captured when viewed from lens 130. When the window frame 12A is not captured when viewed from lens 130, it means that the window frame 12A is not within the horizontal field of view θx. When the window frame 12A is captured when viewed from lens 130, it means that the window frame 12A is within the horizontal field of view θx.

[0175] <When the window frame 12A is reflected when viewed from lens 130> When the window frame 12A is reflected when viewed from lens 130, the length X12 on the reflective surface of the heat-reflective film 11C is expressed by the following equation (16), using the ratio of length Dz to distance f. Note that length X12 is the sum of the length on the reflective surface of the heat-reflective film 11C of the portion of region (1) on the reflective surface of the heat-reflective film 11C that is on the +X direction side of the straight line passing through the center of lens 130 and parallel to the normal of the window glass 11, and the length of region (2) on the reflective surface of the heat-reflective film 11C on the +X direction side. X12 = Dx × Dz / g = Dx × Dz / (Dz + d) ... (16)

[0176] When the window frame 12A is reflected as seen from the lens 130, the length X4 in the X direction of region (4) on the reflective surface of the heat-reflective film 11C can be expressed by the following equation (17), using the ratio of distance f to distance e: X4 = Dx × e / f = Dx × e / (Dz + e) ​​... (17)

[0177] When the window frame 12A is reflected as seen from the lens 130, the length X5 in the X direction of the region (5) on the reflective surface of the heat-reflective film 11C is expressed by the following equation (18): X5 = Dz × tan(θx / 2 + θc) - Dx ... (18)

[0178] Here, if Xt is the length in the X direction included in the horizontal field of view θx on the reflective surface of the heat-reflective film 11C, then the length Xt is expressed by the following equation (19): Xt = Dz × {tan(θx / 2 - θc) + tan(θx / 2 + θc)} ... (19)

[0179] When the window frame 12A is reflected when viewed from the lens 130, the length X3 in the X direction of region (3) on the reflective surface of the heat-reflective film 11C is obtained by subtracting lengths X12, X4, and X5 from the length Dz × tan(θx / 2 + θc), and is expressed by the following equation (20). The length Dz × tan(θx / 2 + θc) is the length obtained by considering the angle θc that the optical axis C of the lens 130 makes with the Z direction for half the length Xt, Xt / 2. X3=Dz×tan(θx / 2+θc)-X12-X4-X5=Dz×tan(θx / 2+θc)-Dx×Dz / (Dz+d)-Dx× e / (Dz+e)-(Dz×tan(θx / 2+θc)-Dx)=Dz×Dx×{1 / (Dz+e)-1 / (Dz+d)}...(20)

[0180] From the above, the reflection reduction rate Rx (%) with respect to distance Dx when the window frame 12A is reflected when viewed from the lens 130 can be expressed by the following equation (21) using lengths X3 and Xt: Rx = X3 / Xt × 100 = [Dz × Dx × {1 / (Dz+e) - 1 / (Dz+d)}] / [Dz × {tan(θx / 2 - θc) + tan(θx / 2 + θc)}] × 100 = Dx × {1 / (Dz+e) - 1 / (Dz+d)} / {tan(θx / 2 - θc) + tan(θx / 2 + θc)} × 100 (%) ... (21)

[0181] Here, the horizontal field of view θx, distance Dx, distance d, distance e, distance f, and distance g in the XZ plane view are defined in relation to the frame portion 12Y of the window frame 12. However, in relation to the frame portion 12X of the window frame 12, it is sufficient to define the vertical field of view θy of the lens 130, the distance Dy in the Y direction between the lens 130 and the frame portion 12X, and the distances d, e, f, and g in the XZ plane view.

[0182] The reflection reduction rate Rx (%) with respect to distance Dx, expressed by formula (21), is preferably greater than 0% and 50% or less. If Rx is greater than 0% and 50% or less, it is easier to capture images of the outside even when indoor lights are on at night without using a lens hood. Rx is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. In addition, Rx may be 45% or less, 40% or less, or 35% or less.

[0183] When the window frame 12A is reflected when viewed from the lens 130, the reflection reduction rate Ry (%) with respect to distance Dy can be expressed by the following equation (22), using lengths X3 and Xt: Ry = X3 / Xt × 100 = [Dz × Dy × {1 / (Dz+e) - 1 / (Dz+d)}] / [Dz × {tan(θy / 2 - θc) + tan(θy / 2 + θc)}] × 100 = Dy × {1 / (Dz+e) - 1 / (Dz+d)} / {tan(θy / 2 - θc) + tan(θy / 2 + θc)} × 100 (%) ... (22)

[0184] The reflection reduction rate Ry (%) with respect to distance Dy, expressed by formula (22), is preferably greater than 0% and 50% or less. If Ry is greater than 0% and 50% or less, it is easier to capture images of the outside even when indoor lights are on at night without using a lens hood. Ry is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. Ry may also be 45% or less, 40% or less, or 35% or less.

[0185] <When the window frame 12A is not reflected when viewed from lens 130> When the window frame 12A is not reflected when viewed from lens 130, it is the case that regions (4) and (5) do not exist in Figure 14. Regions (4) and (5) do not exist, for example, when the horizontal field of view θx is narrow and the window frame 12A is not reflected, or when the window frame 12A does not exist as shown in Figure 12A.

[0186] In this case, within the XZ plane, we can remove the terms for lengths X4 and X5 from equation (20), so length X3 is expressed by the following equation (23): X3 = Dz × tan(θx / 2 + θc) - X12 = Dz × tan(θx / 2 + θc) - Dx × Dz / (Dz + d) ... (23)

[0187] From the above, the reflection reduction rate Rx (%) with respect to distance Dx when the window frame 12A is not reflected when viewed from lens 130 can be expressed by the following equation (24) using the lengths X3 and Xt in equation (23): Rx = X3 / Xt × 100 = Dz × tan(θx / 2 + θc) - Dx × Dz / (Dz + d) / [Dz × {tan(θx / 2 - θc) + tan(θx / 2 + θc)}] × 100 = {tan(θx / 2 + θc) - Dx / (Dz + d)} / {tan(θx / 2 - θc) + tan(θx / 2 + θc)} × 100 (%) ... (24)

[0188] Furthermore, in relation to the frame portion 12X of the window frame 12, the reflection reduction rate Ry (%) relative to the distance D when the window frame 12A is reflected when viewed from the lens 130 can be determined using the vertical field of view θy of the lens 130, the distance Dy in the Y direction between the lens 130 and the frame portion 12X, and the distances d, e, f, and g in the XZ plane view.

[0189] The reflection reduction rate Rx (%) with respect to distance Dx, expressed by formula (24), is preferably greater than 0% and 50% or less. If Rx is greater than 0% and 50% or less, it is easier to capture images of the outside even when indoor lights are on at night without using a lens hood. Rx is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. In addition, Rx may be 45% or less, 40% or less, or 35% or less.

[0190] The reduction rate Ry (%) can be expressed by the following equation (25), using lengths X3 and Xt: Ry = X3 / Xt × 100 = Dz × tan(θy / 2 + θc) - Dy × Dz / (Dz + d) / [Dz × {tan(θy / 2 - θc) + tan(θy / 2 + θc)}] × 100 = {tan(θy / 2 + θc) - Dy / (Dz + d)} / {tan(θy / 2 - θc) + tan(θy / 2 + θc)} × 100 (%) ... (25)

[0191] The reflection reduction rate Ry (%) with respect to distance Dy, expressed by formula (10), is preferably greater than 0% and 50% or less. If Ry is greater than 0% and 50% or less, it is easier to capture images of the outside even when indoor lights are on at night without using a lens hood. Ry is more preferably 10% or more, even more preferably 20% or more, and particularly preferably 30% or more. Ry may also be 45% or less, 40% or less, or 35% or less.

[0192] Although the electronic device and the window glass with the electronic device according to the embodiment have been described above, the design of this disclosure can be modified as appropriate without departing from the gist of it.

[0193] For example, in the above embodiment, an example was described in which an imaging device 100 is used as an electronic device attached to the window, but this disclosure is not limited thereto. The electronic device can be anything that can be attached to the window 10, and may be, for example, a sensor, an antenna, a speaker, etc.

[0194] Furthermore, although the imaging device 100 was configured to be detachable from the window 10 in the above embodiment, this disclosure is not limited thereto. The imaging device 100 may be fixed to the window 10 in a manner that prevents it from being detachable.

[0195] Furthermore, although the above embodiment describes an example in which the imaging device 100 is provided with a skirt 114, this disclosure is not limited thereto. For example, the imaging device 100 does not need to be provided with a skirt 114.

[0196] Furthermore, although the above embodiment describes an example in which the skirt 114 is provided over the entire outer periphery of the opposing surface 111, this disclosure is not limited thereto. For example, the skirt 114 may be provided only in a portion of the outer periphery of the opposing surface 111.

[0197] Furthermore, although the above embodiment describes an example in which the tip of the skirt 114 abuts against the main surface 11B2 on the interior side of the window glass 11, the present disclosure is not limited thereto. For example, the tip of the skirt 114 may be spaced apart from the main surface 11B2 on the interior side of the window glass 11. In this case, the relationship between the protruding length h of the skirt and the distance g between the opposing surface 111 and the main surface 11 on the interior side of the window glass 11 is h < g.

[0198] Furthermore, although the above embodiment describes an example in which the outer circumference S of the imaging device 100 is uniform at any position in the Z-axis direction, the present disclosure is not limited thereto. The outer circumference of the imaging device 100 may vary depending on the position in the Z-axis direction. For example, the outer circumference of the imaging device 100 may increase as it approaches the window glass 11, or increase as it moves away from the window glass 11. In the case where the outer circumference of the imaging device 100 varies depending on the position in the Z-axis direction, the outer circumference S substituted into the above equations (1) to (9) may be the outer circumference S of the surface located closest to the window glass 11.

[0199] Furthermore, although the above embodiment describes an example in which the opposing surface 111 of the imaging device 100 and the main surface 11B2 on the interior side of the window glass 11 are spaced apart, the present disclosure is not limited to this. If the above equations (1) to (9) are satisfied, the distance g between the opposing surface 111 and the main surface 11B2 on the interior side may be 0. In other words, the opposing surface 111 and the main surface 11B2 on the interior side may be in contact. In this case, the imaging device 100 will not be provided with a skirt 114.

[0200] Furthermore, although the above embodiment described opposing surfaces 111 and 211 which are right-angled isosceles triangles and squares in a front view, the shape of the opposing surfaces is not limited to these. As long as the above formulas (1) to (9) are satisfied, the shape of the opposing surfaces may be other shapes. For example, the shape of the opposing surfaces may be a triangle other than a right-angled isosceles triangle in a front view, or a quadrilateral other than a square. It may also be circular, or a polygon other than a triangle or quadrilateral.

[0201] The following additional information is disclosed regarding the above-described embodiments.

[0202] (Note 1) An electronic device provided so as to face the main surface on the interior side of a windowpane separating the interior from the exterior, the device having a facing surface that faces the windowpane, and satisfying the following equations (1) to (4) when the distance between the windowpane and the facing surface is g, the solar absorptivity of the facing surface is α, and the outer circumference length of the facing surface is S. g ≥ 0 ... (1) g ≥ c1 × α + c2 ... (2) c1 = 0.038S ２ -0.49S+0.95...(3) c2=-0.0032S ２ -0.41S - 6.1 ... (4) (Note 2) The electronic device described in Note 1, which is provided on the outer circumference of the opposing surface and has a protruding portion that protrudes from the outer circumference, and satisfies the following equations (5) to (9) when the length of the protruding portion that protrudes from the opposing surface is h. h > 0 ... (5) h ≥ c1 × α + c2 ... (6) c1 = 0.038S ２ -0.49S+0.95...(7) c2=-0.0032S ２-0.41S - 6.1 ... (8) h ≤ g ... (9) (Note 3) An electronic device provided so as to face the main surface on the interior side of a windowpane separating the interior from the exterior, comprising: a facing surface facing the windowpane; and a protruding portion provided on the outer periphery of the facing surface and protruding from the outer periphery, wherein when the length of the protruding portion protruding from the facing surface is h, the solar absorptivity of the facing surface is α, and the outer periphery length of the facing surface is S, the electronic device satisfies the following equations (10) to (13): h > 0 ... (10) h ≥ c1 × α + c2 ... (11) c1 = 0.038S ２ -0.49S+0.95...(12) c2=-0.0032S ２ -0.41S-6.1...(13) (Note 4) The electronic device according to Note 2 or Note 3, wherein the projection is provided over the entire circumferential area of ​​the outer periphery of the opposing surface. (Note 5) The electronic device according to any one of Notes 2 to 4, wherein the projection is plate-shaped and has a plate thickness of 10 mm or less. (Note 6) The area of ​​the opposing surface is 1000 cm² ２ The following electronic devices are specified in any one of the appendices 1 to 5: (Appendix 7) The electronic device is installed within 10 cm from the edge of the window glass when viewed from a direction perpendicular to the main surface of the window glass, as specified in any one of the appendices 1 to 6: (Appendix 8) The solar absorptivity of the opposing surface is 85% or less, as specified in any one of the appendices 1 to 7: (Appendix 9) The opposing surface is a right-angled triangle, as specified in any one of the appendices 1 to 8: (Appendix 10) The opposing surface is a square, as specified in any one of the appendices 1 to 8: (Appendix 11) The window glass with an electronic device, comprising the electronic device specified in any one of the appendices 1 to 10 and the window glass.

[0203] Furthermore, the disclosure of Japanese Patent Application No. 2025-015149, filed on 31 January 2025, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually described as being incorporated by reference.

[0204] 11 Window glass 11B2 Main surface on the interior side 100 Imaging device (electronic device) 111 Opposing surface 114 Skirt (protruding part)

Claims

1. An electronic device provided so as to face the main surface on the interior side of a windowpane separating the interior from the exterior, the device having a facing surface that faces the windowpane, and satisfying the following equations (1) to (4) when the distance between the windowpane and the facing surface is g, the solar absorptivity of the facing surface is α, and the outer circumference length of the facing surface is S: g ≥ 0 ... (1) g ≥ c1 × α + c2 ... (2) c1 = 0.038S ２ -0.49S+0.95...(3) c2=-0.0032S ２ -0.41S-6.1...(4) 2. The electronic device according to claim 1, comprising a projection provided on the outer periphery of the opposing surface and projecting from the outer periphery, wherein when the length of the projection protruding from the opposing surface is h, the following equations (5) to (9) are satisfied: h > 0 ... (5) h ≥ c1 × α + c2 ... (6) c1 = 0.038S ２ -0.49S+0.95...(7) c2=-0.0032S ２ -0.41S-6.1...(8) h≦g...(9) 3. An electronic device provided so as to face the main surface on the interior side of a windowpane separating the interior from the exterior, comprising: an opposing surface facing the windowpane; and a protruding portion provided on the outer periphery of the opposing surface and protruding from the outer periphery, wherein the length of the protruding portion from the opposing surface is h, the solar absorptivity of the opposing surface is α, and the outer periphery length of the opposing surface is S, the electronic device satisfies the following equations (10) to (13): h > 0 ... (10) h ≥ c1 × α + c2 ... (11) c1 = 0.038S ２ -0.49S+0.95...(12) c2=-0.0032S ２ -0.41S-6.1...(13) 4. The electronic device according to claim 2, wherein the protrusion is provided over the entire circumferential area of ​​the outer periphery of the opposing surface.

5. The electronic device according to claim 2, wherein the protruding portion is plate-shaped and has a plate thickness of 10 mm or less.

6. The area of ​​the opposing surfaces is 1000 cm². ２ The electronic device according to claim 1, as follows:

7. The electronic device according to claim 1, which is installed within 10 cm from the edge of the window glass when viewed from a direction perpendicular to the main surface of the window glass.

8. The electronic device according to claim 1, wherein the solar radiation absorptance of the opposing surface is 85% or less.

9. The electronic device according to claim 1, wherein the opposing surfaces are in the shape of a right triangle.

10. The electronic device according to claim 1, wherein the opposing surfaces are square in shape.

11. A window glass with an electronic device, comprising the electronic device according to any one of claims 1 to 10, and the window glass.

Images