Lighting fixtures

Abstract

The present invention provides a lighting fixture that can suppress the reflection of light emitted from a light source from appearing in the image captured by the photographic device, while also enabling miniaturization of the viewing window of the container. [Solution] The casing body 21 of the lighting fixture is provided with a single opening 25a that forms a light transmission area from the light source unit 3 and is within the field of view of the camera unit 4, and is also provided with a light-shielding means SD that covers the field of view of the camera unit 4. The light-shielding means SD comprises an inner louver 8 and an outer louver unit 9. The inner louver 8 is disposed in the space between the camera unit 4 and the transparent glass 26, and suppresses light irradiated from the light source unit 3 from being reflected by the transparent glass 26 and reaching within the field of view. The outer louver unit 9 is disposed in the space between the opening 25a and the tank-side glass 63, and suppresses light irradiated from the light source unit 3 from being reflected by the tank-side glass 63 and reaching within the field of view.

Description

Technical Field

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[0001] The present invention relates to lighting fixtures. In particular, the present invention relates to improvements in the internal structure of lighting fixtures.

Background Art

[0002] For example, as disclosed in Patent Document 1, in order to monitor the state of a storage substance (such as a solvent, etc.) in a tank, a light source for illuminating the inside of the tank and a camera for photographing the inside of the tank are required.

[0003] Patent Document 1 discloses connecting a first transparent rod and a second transparent rod to a tank individually, arranging a light source near the outer end face of one transparent rod and a camera near the outer end face of the other transparent rod respectively, and photographing the inside of the tank with the camera while illuminating the inside of the tank with the light source, thereby monitoring the state inside the tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A configuration in which the light source and the camera are placed separately (not housed in the same housing) as disclosed in Patent Document 1 is an effective means for avoiding the situation where the light from the light source is reflected by glass (such as glass attached to the viewing window of the tank, etc.) in the middle of its optical path and the reflected light is reflected into the image of the camera.

[0006] However, in this case, the tank would require two viewing windows: one for a light source unit with the light source built into the housing, and another for a camera unit with the camera built into the housing. Furthermore, if the tank were to have only one viewing window, the positions of the light source unit and the camera unit would need to be separated to suppress reflections of the light, requiring a large viewing window that spans both units, making it difficult to miniaturize the viewing window.

[0007] Thus, suppressing the reflection of light from the light source from appearing in the camera image and miniaturizing the tank's viewing window are conflicting goals, and until now, it had not been possible to achieve both.

[0008] The present invention has been made in view of the above, and its objective is to provide a lighting fixture that can suppress the reflection of light emitted from a light source from appearing in the image of the photographic means (camera in the above case) and that can also achieve miniaturization of the viewing window of the container (tank in the above case). [Means for solving the problem]

[0009] The present invention provides a solution for achieving the above objective, which is based on a lighting device that illuminates a space to be monitored when photographing the space to be monitored by a photographic means through a viewing window of the space to be monitored in a container having the space to be monitored. The lighting device comprises a lighting device casing, a light source housed inside the lighting device casing, and the photographic means, wherein the lighting device casing is provided with a single opening that forms a light transmission area from the light source and is within the field of view of the photographic means, and is equipped with a light shielding means that covers the field of view of the photographic means, thereby suppressing reflected light from a transmissive body placed on the optical path of the light emitted from the light source toward the space to be monitored from reaching within the field of view.

[0010] Due to this specific feature, even if light irradiated from the light source toward the monitored space inside the container is reflected by a transmissive material placed in its optical path, the field of view of the imaging means is covered by the light-shielding means, thus preventing the reflected light from reaching the field of view. Therefore, even with a single opening in the lighting fixture casing, the inclusion of the reflected light in the image captured by the imaging means is suppressed, allowing for effective monitoring of the monitored space.

[0011] Specifically, the transparent body includes a transparent glass mounted to cover the opening, and the light-shielding means includes a first light-shielding member disposed to cover the field of view range in the space between the imaging means and the transparent glass.

[0012] According to this, even if light irradiated from a light source toward the monitored space inside the container is reflected by the transparent glass, the field of view in the space between the imaging means and the transparent glass is covered by the first light-shielding means, thereby suppressing the reflected light from reaching the field of view. As a result, the reflected light reflected by the transparent glass is prevented from appearing in the image captured by the imaging means, enabling effective monitoring of the monitored space.

[0013] Furthermore, the transparent body includes a container-side glass installed to cover the viewing window, and the light-shielding means includes a second light-shielding member disposed to cover the field of view range in the space between the opening and the container-side glass.

[0014] According to this, even if light irradiated from a light source toward the monitored space inside the container is reflected by the container-side glass, the field of view in the space between the opening and the container-side glass is covered by the second light-shielding means, thereby suppressing the reflected light from reaching the field of view. As a result, the reflected light reflected by the container-side glass is prevented from appearing in the image captured by the imaging means, enabling effective monitoring of the monitored space.

[0015] Furthermore, the second light-shielding member comprises a casing-side light-shielding member attached to the lighting fixture casing and a container-side light-shielding member disposed on the container-side glass side, wherein the container-side light-shielding member is combined with the casing-side light-shielding member so as to be slidable relative to it along the direction in which the lighting fixture casing and the container face each other.

[0016] According to this, even if there are variations in the distance between the container and the lighting fixture casing due to the shape of the container or the shape of the lighting fixture casing, the container-side light-shielding member slides relative to the casing-side light-shielding member, thereby absorbing these variations and ensuring a light-shielding state. This increases the versatility of the second light-shielding member.

[0017] Furthermore, a support portion for supporting the transparent glass is provided near the opening, and a filler is filled between the inner surface of the support portion and the outer surface of the transparent glass. The inner surface of the support portion is an inclined surface that narrows in diameter towards the inner side as it approaches the outside of the lighting fixture casing.

[0018] When high pressure is generated inside the lighting fixture casing, the pressure acting on the filler material is directed outwards from the casing. However, the reaction force to this pressure compresses the filler material in a direction where the inner surface of the support and the outer surface of the transparent glass face each other. In other words, this reaction force acts to increase the degree of adhesion between the filler material and the inner surface (inclined surface) of the support. This ensures a high level of explosion-proof performance between the support and the transparent glass.

[0019] The lighting fixture casing is a cast product, and the inner circumferential surface of the support portion that comes into contact with the filler is left as a cast surface without surface treatment.

[0020] According to this, since the surface roughness of the surface of the inner peripheral surface of the support portion that contacts the filler is large, the adhesion between this surface (casting surface) and the filler is maintained at a high level. Also by this, the explosion-proof performance between the support portion and the transmissive glass can be ensured highly.

Advantages of the Invention

[0021] In the present invention, a lighting fixture casing is provided with a single opening that forms a light transmission region from a light source and is within the angular range of the imaging means, and is provided with a light shielding means that covers the angular range of the imaging means. Thereby, even though the opening of the lighting fixture casing is single, it is possible to suppress the reflected light from being reflected in the image captured by the imaging means. As a result, it is possible to achieve both suppressing the reflected light of the light irradiated from the light source from being reflected in the image of the imaging means and miniaturizing the viewing window of the container.

Brief Description of the Drawings

[0022] [Figure 1] It is an external view of the lighting fixture according to the embodiment seen from obliquely above. [Figure 2] It is an external view of the lighting fixture according to the embodiment seen from obliquely below. [Figure 3] It is a front view showing a state where the lighting fixture according to the embodiment is attached to a tank. [Figure 4] It is a perspective view showing a state where the lighting fixture according to the embodiment is attached to a tank. [Figure 5] It is a cross-sectional view taken along the line V-V in FIG. 4, showing the periphery of the arrangement positions of the light source unit and the camera unit. [Figure 6] It is a cross-sectional view in a direction orthogonal to the cross-sectional direction of FIG. 5, showing the periphery of the arrangement position of the camera unit. [Figure 7] FIG. 7(a) is a cross-sectional view showing a support portion of a transmissive glass in the lighting fixture according to the embodiment, FIG. 7(b) is a cross-sectional view showing a support portion of a transmissive glass in the lighting fixture according to Comparative Example 1, and FIG. 7(c) is a cross-sectional view showing a support portion of a transmissive glass in the lighting fixture according to Comparative Example 2. [Figure 8] This is a perspective view showing the area around the placement of the camera unit inside the lighting fixture according to the embodiment. [Figure 9] This diagram shows the interior louvers; Figure 9(a) is a perspective view, Figure 9(b) is a plan view, and Figure 9(c) is a perspective view showing a portion of the louvers in cross-section. [Figure 10] This is a perspective view showing the exterior louver unit. [Figure 11] Figure 11(a) is a perspective view and Figure 11(b) is a plan view, showing the lower louvers of the outer louver unit. [Figure 12] This diagram shows the upper louver of the outer louver unit, with Figure 12(a) being a perspective view and Figure 12(b) being a plan view. [Figure 13] This is a diagram equivalent to Figure 5, showing a different tank from the one shown in Figure 5, with the lighting fixture installed. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment describes the case in which the present invention is applied to a pressure-resistant explosion-proof lighting fixture attached to a tank for storing and stirring a solvent. The tank is installed inside a factory building, for example, and multiple tanks are installed inside the building.

[0024] -Lighting fixture configuration- Figure 1 is an external view of the lighting fixture 1 according to this embodiment, viewed from diagonally above, and Figure 2 is an external view of the lighting fixture 1 according to this embodiment, viewed from diagonally below. As shown in these figures, the lighting fixture 1 according to this embodiment includes a lighting fixture casing 2, and various devices (control devices not shown, etc.), including a light source unit 3 and a camera unit 4 (see Figures 5 and 6), which will be described later, are housed inside this lighting fixture casing 2.

[0025] (Lighting fixture casing) The lighting fixture casing 2 comprises a casing body 21 and a lid member 23 supported on the upper part of the casing body 21 by a hinge member 22.

[0026] <Casing body> The casing body 21 is formed by integrally molding a substantially cylindrical body portion 24 and a bottom plate portion 25 located below the body portion 24 by casting (for example, die-casting aluminum).

[0027] The body portion 24 is provided with wiring openings 24a, 24a for drawing power lines and signal lines to the light source unit 3 and the camera unit (shooting means) 4. The body portion 24 also has bracket mounting seats 24b, 24b, ... arranged at multiple locations (for example, 4 locations) around the circumferential direction for attaching the lighting fixture 1 to the tank (container in this invention) T via mounting brackets 51 (see Figures 3 and 4), which will be described later. Figure 3 is a front view showing the lighting fixture 1 attached to the tank T. Figure 4 is a perspective view showing the lighting fixture 1 attached to the tank T. As shown in Figures 3 and 4, an L-shaped mounting bracket 51 is bolted to each bracket mounting seat 24b, and the mounting bracket 51 is connected to a tank-side bracket 52 extending from the tank T side by bolts B2, thereby attaching the lighting fixture 1 to the tank T.

[0028] Here, we will describe the mounting structure of the lighting fixture 1 to the tank T. In Figure 3, the tank body T1 (the tank body in which the solvent is stored) of the tank T is shown by a dashed line, and the mounting unit 6, which covers the viewing window (an opening provided at the top of the tank body T1) and serves as the mounting part for the lighting fixture 1, is shown by a solid line.

[0029] The mounting unit 6 comprises an annular lower ring member 61, an annular upper ring member 62, a flattened cylindrical tank-side glass (transparent body) 63 with a diameter larger than the opening diameter of the inner openings of these ring members 61 and 62, and the tank-side bracket 52. In other words, the tank-side glass 63 is sandwiched between the lower ring member 61 and the upper ring member 62 via a sealing material, and bolts B1 are inserted through each of the eight bolt insertion holes provided in each of these ring members 61 and 62, and the bolts B1 are screwed into female screw holes provided on the outer circumference of the viewing window of the tank body T1, thereby mounting the mounting unit 6 to cover the viewing window. Furthermore, on the upper surface of the upper ring member 62, the tank-side bracket 52 is superimposed on four bolt insertion holes located every other of the eight bolt insertion holes, and the bolts B1 are inserted through the bolt insertion holes provided in the tank-side bracket 52, thereby supporting the tank-side bracket 52 on the upper surface of the upper ring member 62. The lighting fixture 1 is then attached to the tank T by connecting the tank-side bracket 52 and the mounting bracket 51 with bolts B2. In this state of attachment of the lighting fixture 1 to the tank T, the opening 25a of the bottom plate portion 25 (see Figures 2 and 5), which will be described later, and the viewing window of the tank T face each other with the tank-side glass 63 in between.

[0030] As shown in Figures 1 and 2, the upper edge of the body portion 24 is provided with a flange 24c that extends outward by a predetermined distance. Bolt fastening portions 24d are provided at multiple equally angled locations on the circumferential direction of the flange 24c, where the body portion 24 is partially thickened below the flange 24c. These bolt fastening portions 24d are for bolting the cover member 23, and have bottomed female screw holes (not shown in the figures) that extend in the direction along the centerline of the body portion 24 (vertical direction). In this embodiment, eight bolt fastening portions 24d, 24d, ... are provided in the circumferential direction, and eight female screw holes are also formed, but this number is not limited to these.

[0031] As shown in Figure 2, the bottom plate portion 25 has a circular opening 25a in the center. This opening 25a serves two purposes: to allow illumination light from the light source unit 3 to pass through, and to enable the camera unit 4 to photograph the inside of the tank T. This opening 25a is covered by a transparent glass 26 (see Figure 5) disposed inside the casing body 21. As a result, the illumination light from the light source unit 3 passes through this transparent glass (transmitter) 26, the opening 25a, the tank-side glass 63, and the viewing window to illuminate the inside of the tank T. At the same time, these transparent glass 26, the opening 25a, the tank-side glass 63, and the viewing window form the field of view of the camera provided in the camera unit 4, thus enabling photography inside the tank T.

[0032] <Lid component> The lid member 23 is for closing the upper opening of the casing body 21 and, as described above, is rotatably supported on the upper part of the casing body 21 by a hinge member 22. The outer peripheral edge of the lid member 23 is provided with a flange 23a that extends outward by a predetermined distance. Bolt insertion holes (not shown in the figure) are formed in this flange 23a at equal angular intervals along its circumferential direction, corresponding to the flange 24c provided on the upper end edge of the body portion 24. In this embodiment, eight bolt insertion holes are formed, but this number is not limited to this.

[0033] When the upper opening of the casing body 21 is closed with the cover member 23, a sealing material such as a gasket (not shown) is interposed between the flanges 24c and 23a, the flanges 24c and 23a are overlapped, and the bolt B3 is inserted through the bolt insertion hole formed in the cover member 23 and the female screw hole formed in the bolt fastening portion 24d (for example, the bolt B3 is inserted from the top), and the bolt B3 is screwed into the female screw hole. As a result, the flange 24c of the casing body 21 and the flange 23a of the cover member 23 are in close contact, ensuring the explosion-proof performance of the lighting fixture 1.

[0034] Furthermore, as another configuration to ensure this explosion-proof performance, in this embodiment, high explosion-proof performance is also ensured between the opening 25a provided in the bottom plate portion 25 and the transparent glass 26. This will be explained in detail below.

[0035] Figure 7(a) is a cross-sectional view showing the support portion of the transparent glass 26 (the support portion at the outer peripheral edge of the transparent glass 26). As shown in Figure 7(a), the peripheral portion of the opening 25a in the bottom plate portion 25 is composed of an outer horizontal portion 25b extending horizontally from the lower end of the body portion 24 toward the inner circumference, an inclined portion (support portion in this invention) 25c extending diagonally downward toward the inner circumference from the inner side of the outer horizontal portion 25b, and an inner horizontal portion 25d extending horizontally from the lower end of the inclined portion 25c toward the inner circumference. The opening 25a is formed by the inner peripheral edge of this inner horizontal portion 25d. Furthermore, the inner peripheral surface 25e of this inner horizontal portion 25d is an inclined surface that slopes toward the outer circumference as it goes downward.

[0036] Furthermore, the upper surface 25f of the outer horizontal section 25b (the surface facing the inside of the casing body 21) and the upper surface 25g of the inner horizontal section 25d (the surface located on the inside side of the casing body 21) are machined surfaces (machined surfaces where the cast surface has been polished), whereas the inclined surface 25h of the inclined section 25c (the surface located on the inside side of the casing body 21) is an unmachined surface. In other words, the inclined surface 25h of this inclined section 25c is a surface that remains as the cast surface (a surface with a large surface roughness).

[0037] Furthermore, as a support structure for the transparent glass 26 around the opening 25a, the outer diameter of the transparent glass 26 is set to be larger than the inner diameter of the opening 25a and smaller than the inner diameter of the outer horizontal portion 25b, and the transparent glass 26 is positioned so that its outer peripheral surface 26a and the inclined surface 25h of the inclined portion 25c face each other. More specifically, annular support rings 27a and 27b are in contact with the upper and lower sides of the outer peripheral portion of the transparent glass 26, and the transparent glass 26 is sandwiched and supported between these support rings 27a and 27b. In addition, a disc-shaped plate material 28 is placed above the upper support ring 27a, and this plate material 28 is attached to the upper surface 25f of the outer horizontal portion 25b by bolts B4. The lower support ring 27b is placed on the upper surface 25g of the inner horizontal portion 25d. As a result, the unit, which consists of the transparent glass 26, the upper support ring 27a, and the lower support ring 27b, is supported by being sandwiched between the plate material 28 and the upper surface 25g of the inner horizontal portion 25d.

[0038] Furthermore, a filler 7 is filled between the outer circumferential surface 26a of the transparent glass 26 and the inclined surface 25h of the inclined portion 25c, and between the outer circumferential surfaces of each support ring 27a, 27b and the inclined surface 25h of the inclined portion 25c. The filler 7 consists of a filler body portion 71 filled between the outer circumferential surface 26a of the transparent glass 26 and the inclined surface 25h of the inclined portion 25c, an upper filler portion 72 above the filler body portion 71 filled between the outer circumferential surface of the upper support ring 27a and the inclined surface 25h of the inclined portion 25c, and a lower filler portion 73 below the filler body portion 71 filled between the outer circumferential surface of the lower support ring 27b and the inclined surface 25h of the inclined portion 25c. As mentioned above, the inclined surface 25h of the inclined portion 25c is a surface with a large surface roughness that remains as the cast surface, so a high degree of adhesion between this inclined surface 25h and the filler 7 is maintained. Furthermore, the outer surface of the filler body portion 71 is inclined downwards toward the center, following the inclined surface 25h of the inclined portion 25c. Therefore, when high pressure is generated inside the casing body 21, the pressure acting on the upper surface of the filler body portion 71 is vertically downward, but the reaction force of this pressure acts in a direction that compresses the lower region of the filler body portion 71 horizontally, thereby increasing the degree of adhesion between the filler body portion 71 and the inclined surface 25h of the inclined portion 25c. This ensures explosion-proof performance between the opening 25a provided in the bottom plate portion 25 and the transparent glass 26.

[0039] Below, we compare the structure described above (explosion-proof structure) with the configurations of several comparative examples.

[0040] Figure 7(b) is a cross-sectional view showing the support portion of the translucent glass 26 in the lighting fixture according to Comparative Example 1. In this configuration, the upper surface 25f of the outer horizontal portion 25b and the upper surface 25g of the inner horizontal portion 25d are connected by a vertical plane A, without the presence of an inclined portion 25c (without providing an inclined surface 25h). In this case, when high pressure is generated inside the casing body 21, no force is generated that compresses the lower region of the filler body portion 71 in the horizontal direction (as described above using Figure 7(a)), nor is there any force that increases the degree of adhesion between the filler body portion 71 and the vertical plane A. Therefore, there is a possibility that the explosion-proof performance of the lighting fixture may not be sufficiently obtained.

[0041] In this embodiment, as described above, by providing an inclined surface 25h on the inclined portion 25c, a force is generated that acts to compress the lower region of the filler body portion 71 in the horizontal direction, thereby increasing the degree of adhesion between the filler body portion 71 and the inclined surface 25h of the inclined portion 25c, and thus ensuring the explosion-proof performance of the lighting fixture 1.

[0042] Furthermore, generally, the explosion-proof structure around the periphery of the transparent glass 26 specifies the fixing distance between the casing body 21 and the transparent glass 26. In other words, it is specified that the contact distance (contact distance in the cross-sectional view) of the filler 7 interposed between the transparent glass 26 and the components constituting the casing body 21 at the outer edge of the transparent glass 26 must be at least a predetermined distance. In this embodiment, the thickness dimension of the transparent glass 26 is made to be equal to or longer than this predetermined distance, and the filler 7 is made to contact the entire outer peripheral surface 26a of the transparent glass 26, thereby satisfying this requirement without allowing the filler 7 to wrap around to the upper or lower sides of the transparent glass 26.

[0043] Figure 7(c) is a cross-sectional view showing the support portion of the translucent glass 26 in the lighting fixture according to Comparative Example 2. The translucent glass 26 is made thinner, and the filler 7 is wrapped around the upper and lower sides of the translucent glass 26 to satisfy the above requirements. In this case, in the parts where the filler 7 is wrapped around, the translucent glass 26 is covered with the filler 7, and in these parts, the function of transmitting illumination light from the light source unit 3 and the function of enabling the camera unit 4 to take pictures inside the tank T cannot be performed. As a result, it becomes necessary to increase the diameter of the translucent glass 26 and the diameter of the viewing window of the tank T.

[0044] In this embodiment, by ensuring that the thickness dimension of the transparent glass 26 is equal to or longer than the predetermined distance, it is not necessary to allow the filler 7 to wrap around the upper or lower side of the transparent glass 26, thereby enabling a reduction in the diameter of the transparent glass 26 and the viewing window of the tank T.

[0045] <Hinge component> As shown in Figures 1 and 2, the hinge member 22 comprises a hinge shaft 22a and a hinge fitting 22c having a guide hole 22b that guides and holds the hinge shaft 22a. The guide hole 22b of the hinge fitting 22c is an elongated hole that extends in the vertical direction, and when the fastening of the lid member 23 to the casing body 21 is released, the lid member 23 can be moved vertically relative to the casing body 21 within the range of the guide hole 22b of the hinge fitting 22c.

[0046] (Light source unit) Next, the light source unit 3 will be described. Figure 5 is a cross-sectional view along the VV line in Figure 4, showing the area around the installation location of the light source unit 3 and the camera unit 4. Figure 6 is a cross-sectional view in a direction perpendicular to the cross-sectional direction of Figure 5, showing the area around the installation location of the camera unit 4.

[0047] As shown in Figure 5, the light source unit 3 is located near the bottom plate portion 25 (near the opening 25a) of the casing body 21 and consists of a number of LED chips (light sources in this invention) 31a mounted on the lower surface of an LED substrate 31. Specifically, the LED substrate 31 is attached to the lower surface of a support bracket 32 ​​that is screwed to the outer horizontal portion 25b of the bottom plate portion 25, and light is emitted downward from the LED chips 31a mounted on this LED substrate 31.

[0048] Furthermore, a substantially circular opening 28a is formed in the plate material 28 in the portion located below the LED substrate 31, and a lens 33 is disposed inside this opening 28a for distributing the illumination light emitted from the LED chip 31a towards the inside of the tank T.

[0049] (Camera unit) Next, the camera unit 4 will be described. As shown in Figures 5 and 6, the camera unit 4 is located near the bottom plate portion 25 (near the opening 25a) of the casing body 21, and houses a camera (image sensor) (not shown) inside a roughly rectangular parallelepiped casing 41, with the field of view facing downwards. Examples of this camera include CCD (Charge-Coupled Device) and CMOS (Complementary metal-oxide-semiconductor). In addition, a roughly circular opening 28b is formed in the plate material 28 in the portion located below the camera unit 4. This opening 28b is used as a space for arranging the inner louvers 8 that constitute the light-shielding means SD, which will be described later.

[0050] The images of the inside of tank T acquired by this camera unit 4 are displayed on the monitor screen of a monitoring device installed in a control facility (not shown), allowing a supervisor to monitor the state of the solvent inside tank T by visually inspecting the monitor screen.

[0051] (shading means) A key feature of this embodiment is the inclusion of a light-shielding means SD that covers the field of view of the camera in the camera unit 4, thereby suppressing reflected light from the light source unit 3 towards the tank T, reflected by the transmissive glass 26 and the tank-side glass 63, from reaching the field of view. The configuration of this light-shielding means SD will be described below.

[0052] Figure 8 is a perspective view showing the area around the installation location of the camera unit 4 inside the lighting fixture 1.

[0053] As shown in Figures 5, 6, and 8, the light-shielding means SD is composed of an inner louver (first light-shielding member) 8 and an outer louver unit (second light-shielding member) 9.

[0054] The inner louver 8 is positioned as a component to suppress light emitted from the light source unit 3 from being reflected by the translucent glass 26 and reaching the aforementioned viewing angle range. On the other hand, the outer louver unit 9 is positioned as a component to suppress light emitted from the light source unit 3 from being reflected by the tank-side glass 63 and reaching the aforementioned viewing angle range. The inner louver 8 and the outer louver unit 9 will be described below. <Inner Louver> Figure 9 shows the inner louver 8, where Figure 9(a) is a perspective view, Figure 9(b) is a plan view, and Figure 9(c) is a perspective view showing a part of the louver in cross-section. As shown in these figures, the inner louver 8 comprises a base plate 81 and a light-shielding portion 82.

[0055] As shown in Figures 5 and 6, the base plate 81 is a plate-shaped member having a predetermined thickness that is placed on the upper surface of the transparent glass 26. As shown in Figure 9, the base plate 81 has a roughly rectangular shape in plan view, with one of its four sides 81a being roughly arc-shaped.

[0056] The light-shielding portion 82 is positioned in the center of the base plate 81. This light-shielding portion 82 has a base portion 82a that is octagonal in plan view and has a predetermined height, and a projection portion 82b that protrudes upward in a frustoconical shape from the upper surface of the base portion 82a. Inside the projection portion 82b, the base portion 82a, and the base plate 81, an inner field of view space S1 is formed, which is a frustoconical space that widens in diameter as it extends downward. The upper part of this inner field of view space S1 is open to the upper surface of the top of the projection portion 82b. The shape of this open hole 82c is circular, with approximately the same diameter as the camera lens of the camera unit 4. As shown in Figure 8, the camera unit 4 is mounted on the top of the projection portion 82b such that the camera lens faces the hole 82c.

[0057] The inclination angle of the inner wall surface of the inner viewing space S1, which is provided inside the inner louver 8, is set to be equal to or greater than the viewing angle of the camera in the camera unit 4, so that the inner wall surface constituting the inner viewing space S1 (the protrusion 82b, the base 82a, and the inner wall surface of the base plate 81) does not appear in the image acquired by the camera. More specifically, in this embodiment, the viewing angle of the camera in the cross-section shown in Figure 6 (shown by a dashed line in the figure) is greater than the viewing angle of the camera in the cross-section shown in Figure 5 (shown by a dashed line in the figure), and since the inner viewing space S1 is a frustoconical space, the inclination angle of the inner wall surface of this inner viewing space S1 is set to be equal to or greater than the viewing angle of the camera in the cross-section shown in Figure 6.

[0058] Furthermore, the inner wall surfaces (the protruding portion 82b, the base portion 82a, and the inner wall surfaces of the base plate 81) that constitute this inner viewing space S1 are coated with a matte black paint in order to suppress light reflection from these inner wall surfaces.

[0059] <Exterior Louver Unit> Figure 10 is a perspective view showing the outer louver unit 9. As shown in Figure 10, the outer louver unit 9 is composed of a lower louver (container-side light-shielding member) 91 and an upper louver 92 (casing-side light-shielding member).

[0060] Figure 11 shows the lower louver 91, where Figure 11(a) is a perspective view and Figure 11(b) is a plan view. Figure 12 shows the upper louver 92, where Figure 12(a) is a perspective view and Figure 12(b) is a plan view.

[0061] In the following explanation, the left-right direction in Figure 5 (the horizontal direction in which the light source unit 3 and camera unit 4 are aligned) will be referred to as the X direction, with the left direction in the figure being called the X1 direction and the right direction being called the X2 direction. Similarly, the left-right direction in Figure 6 (the horizontal direction perpendicular to the horizontal direction in which the light source unit 3 and camera unit 4 are aligned) will be referred to as the Y direction, with the left direction in the figure being called the Y1 direction and the right direction being called the Y2 direction. These directions are indicated by arrows in Figures 5, 6, and 10-12.

[0062] As shown in Figure 11, the lower louver 91 includes a first inclined section 91a and a second inclined section 91b located on both sides in the X direction and inclining inward as they extend upward, having a predetermined height, and a third inclined section 91c and a fourth inclined section 91d located on both sides in the Y direction and inclining inward as they extend upward, having a predetermined height. The lower ends of each inclined section 91a to 91d are located on the same plane, and these lower ends rest on the upper surface of the tank-side glass 63 (see Figures 5 and 6). On the other hand, the upper end of the first inclined section 91a is located at a position a predetermined dimension higher than the upper end of the second inclined section 91b. In other words, the upper end portions of the third inclined section 91c and the fourth inclined section 91d each include a reference height portion 91e, 91e located closer to the second inclined section 91b and set to a lower height dimension, and an upward extension portion 91f, 91f located closer to the first inclined section 91a and set to a higher height dimension (higher than the reference height portions 91e, 91e). Furthermore, at the upper end of the central portion in the Y direction of both the first inclined portion 91a and the second inclined portion 91b, a guide member 91h is provided, which has a rectangular groove 91g that extends outward in the X direction and opens toward the inner space of the lower louver 91.

[0063] As shown in Figure 12, the upper louver 92 includes first inclined sections 92a and second inclined sections 92b located on both sides in the X direction and inclined inward as they extend upward, having a predetermined height, and third inclined sections 92c and fourth inclined sections 92d located on both sides in the Y direction and inclined inward as they extend upward, having a predetermined height. The inclination angles of these inclined sections 92a to 92d are approximately the same as the inclination angles of the inclined sections 91a to 91d of the lower louver 91. Furthermore, the inclination angles of these inclined sections 92a to 92d and 91a to 91d are approximately the same as the inclination angles of the inner wall surface of the inner viewing space S1 in the inner louver 8. The lower ends of each inclined section 92a to 92d are located on the same plane, and the upper ends of each inclined section 92a to 92d are also located on the same plane.

[0064] The first inclined portion 92a and the second inclined portion 92b of the upper louver 92 are each provided with fin portions 92e, 92e that can be inserted into the grooves 91g, 91g of the guide members 91h, 91h provided on the lower louver 91. In other words, as shown in Figure 10, the lower louver 91 and the upper louver 92 are combined such that relative movement (sliding) in the vertical direction is possible, but relative movement in the horizontal direction is not possible, when the upper louver 92 is inserted into the inner space of the lower louver 91 from below, and each fin portion 92e, 92e of the upper louver 92 is inserted into the grooves 91g, 91g of the guide members 91h, 91h of the lower louver 91.

[0065] Furthermore, the third inclined portion 92c and the fourth inclined portion 92d of the upper louver 92 are each provided with support portions 92f, 92f that protrude outward along the Y direction. These support portions 92f are provided with insertion holes 92g that are elongated in shape. As shown in Figures 2 and 6, roughly rectangular support brackets 29, 29 are bolted to the lower surface of the inner horizontal portion 25d of the casing body 21, and these support brackets 29, 29 are inserted into the insertion holes 92g, 92g in the support portions 92f, 92f of the upper louver 92, thereby supporting the upper louver 92 on the bottom plate portion 25 of the casing body 21.

[0066] As shown in Figures 5, 6, and 8, when the lower louver 91 and the upper louver 92 are combined and the upper louver 92 is supported by the bottom plate portion 25 of the casing body 21, an outer viewing space S2 is formed, which is a truncated square pyramidal space that extends from the inside of the lower louver 91 to the inside of the upper louver 92 and widens towards the bottom. The inclination angle of the inner wall surface of this outer viewing space S2 is set to be equal to or greater than the viewing angle of the camera in the camera unit 4, similar to the inner viewing space S1 described above, so that the inner wall surface constituting the outer viewing space S2 (the inner wall surface of the lower louver 91 and the inner wall surface of the upper louver 92) does not appear in the image acquired by the camera. More specifically, as mentioned above, the camera's field of view angle in the cross-section shown in Figure 6 (shown by a dashed line in the figure) is larger than the camera's field of view angle in the cross-section shown in Figure 5 (shown by a dashed line in the figure). Therefore, the inclination angle of the inner wall surface of this outer field of view space S2 is set to be equal to or greater than the camera's field of view angle in the cross-section shown in Figure 6. This outer field of view space S2 constitutes a space continuous with the inner field of view space S1 mentioned above. Specifically, in the cross-sections shown in Figures 5 and 6, the inner wall surface of the inner field of view space S1 and the inner wall surface of the outer field of view space S2 are located on approximately the same straight line.

[0067] Furthermore, the inner wall surfaces constituting this outer viewing space S2 (the inner wall surface of the lower louver 91 and the inner wall surface of the upper louver 92) are painted with a matte black finish to suppress light reflection, similar to the inner wall surfaces constituting the inner viewing space S1 described above.

[0068] -Monitoring operations inside the tank- Next, we will explain the monitoring operation inside tank T using the lighting fixture 1 configured as described above. This monitoring operation inside tank T monitors the stirring state of the solvent inside tank T, the amount of solvent, and other related matters.

[0069] During the monitoring operation inside the tank T, each LED chip 31a of the light source unit 3 is lit, and the illumination light from each LED chip 31a is directed downwards. This illumination light passes through the translucent glass 26, the opening 25a, the tank-side glass 63, and the viewing window, illuminating the inside of the tank T.

[0070] Furthermore, the camera in camera unit 4 photographs the inside of tank T by passing through the transparent glass 26, the opening 25a, the tank-side glass 63, and the viewing window, and transmits the image data to a monitoring device installed in the management facility. As a result, the image of the inside of tank T is displayed on the monitor screen of the monitoring device, and the monitor can monitor the condition of the solvent inside tank T by visually checking the monitor screen.

[0071] In this embodiment, the inner louver 8 prevents light emitted from the light source unit 3 from being reflected by the translucent glass 26 and reaching the field of view, and the outer louver unit 9 prevents light emitted from the light source unit 3 from being reflected by the tank-side glass 63 and reaching the field of view. In other words, by covering the field of view of the camera in the camera unit 4 with the light-shielding means SD, the reflected light from the translucent glass 26 and the tank-side glass 63 of the light emitted from the light source unit 3 into the tank T from reaching the field of view is suppressed, and the image of the inside of the tank T displayed on the monitor screen of the monitoring device has reduced reflection of the reflected light. This improves the accuracy of monitoring the state of the solvent inside the tank T.

[0072] -Effects of the embodiment- As described above, in this embodiment, the lighting fixture casing 2 is provided with a single opening 25a that forms the light transmission area from the light source unit 3 and is within the field of view of the camera unit 4, and is also equipped with a light-shielding means SD that covers the field of view of the camera unit 4. As a result, even though the opening 25a of the lighting fixture casing 2 is a single opening, the reflection of light that appears in the image captured by the camera unit 4 is suppressed, and the monitoring of the monitored space can be performed well. As a result, it is possible to suppress the reflection of light from the light source unit 3 from appearing in the image of the camera unit 4 and to miniaturize the viewing window of the tank T.

[0073] Furthermore, in this embodiment, the lower louver 91 and the upper louver 92 constituting the outer louver unit 9 are made capable of relative movement (sliding) in the vertical direction. As a result, even if there is variation in the distance between the tank T and the lighting fixture casing 2 due to the shape of the tank T or the shape of the lighting fixture casing 2, the lower louver 91 slides relative to the upper louver 92, absorbing the variation and ensuring a light-shielding state.

[0074] Figure 13 is a diagram equivalent to Figure 5, showing the lighting fixture 1 attached to a tank T different from the one shown in Figure 5. In Figure 13, the gap between the bottom plate portion 25 of the casing body 21 and the upper ring member 62 of the mounting unit 6 is narrower than in Figure 5. In this case, the lower louver 91 moves relatively upward on the outside of the upper louver 92 to compensate for the narrower gap. This upward movement of the lower louver 91 is guided by the fact that each fin portion 92e, 92e of the upper louver 92 is inserted into the grooves 91g, 91g of each guide member 91h, 91h of the lower louver 91. Even in this case, the lower end of the lower louver 91 rests on the upper surface of the tank-side glass 63, covering the field of view of the camera in the camera unit 4. In addition, the state shown in Figure 13 is the state in which the lower louver 91 is moved to its highest position, and the lower end of the upper louver 92 is also resting on the upper surface of the tank-side glass 63.

[0075] In this way, even if there is variation in the distance between the tank T and the lighting fixture casing 2, the lower louver 91 slides relative to the upper louver 92, absorbing the variation and ensuring a light-shielding state. This increases the versatility of the outer louver unit 9.

[0076] -Other Embodiments- Furthermore, the present invention is not limited to the embodiments described above, and all modifications and applications are possible within the scope of the claims and equivalents thereof.

[0077] For example, the above embodiment described an application of the present invention as a pressure-resistant explosion-proof lighting fixture attached to a tank T for storing and agitating a solvent. The present invention is not limited to this, and may also be applied to monitoring a space other than the tank T, or as a lighting fixture other than a pressure-resistant explosion-proof lighting fixture.

[0078] Furthermore, although the inner louver 8 was configured as a single component in the above embodiment, it may also be configured as a combination of multiple components, as in the outer louver unit 9. Also, although the outer louver unit 9 was configured as a combination of multiple components (lower louver 91 and upper louver 92) in the above embodiment, it may also be configured as a single component, as in the inner louver 8.

[0079] Furthermore, in order to reduce the size of the viewing window of the tank T, it is preferable to reduce the diameter of the opening 25a of the lighting fixture casing 2. In this case, it is necessary to bring the light source unit 3 and the camera unit 4 closer together. However, to prevent heat from the light source unit 3 from adversely affecting the camera unit 4, it is necessary to keep the distance between the two units greater than a predetermined distance. Taking these factors into consideration, the distance between the light source unit 3 and the camera unit 4 and the inner diameter of the opening 25a are appropriately set by experiment or simulation. [Industrial applicability]

[0080] This invention is applicable as a pressure-resistant explosion-proof lighting fixture with a built-in camera. [Explanation of symbols]

[0081] 1 Lighting fixtures 2. Lighting fixture casing 25a opening 25c Inclined part (support part) 25h slope 26. Transparent glass (transparent material) 3 Light source units 31a LED chip (light source) 4. Camera unit (shooting means) 63 Tank-side glass (transparent material) 7. Filler 8. Inner louvers (first light-shielding member) 9. Outer louver unit (second light-shielding member) 91 Lower louvers (container-side light-shielding member) 92 Upper louvers (casing-side light-shielding member) T Tank (container) SD shading means

Claims

1. In a lighting device that illuminates the space to be monitored with light when photographing the space to be monitored from a viewing window of a container having the space to be monitored using a photographic means, The system comprises a lighting fixture casing, a light source housed inside the lighting fixture casing, and the imaging means. The lighting fixture casing is provided with a single opening that forms the area through which light from the light source is transmitted and which is within the field of view of the imaging means. A lighting fixture characterized by comprising a light-shielding means that covers the field of view of the aforementioned shooting means, thereby suppressing reflected light from a transparent body placed on the optical path of light irradiated from the light source toward the monitored space from reaching the field of view.

2. In the lighting fixture according to claim 1, The permeable body includes a transparent glass that is installed to cover the opening, The lighting fixture is characterized in that the light-shielding means includes a first light-shielding member disposed to cover the field of view range in the space between the photographing means and the transparent glass.

3. In the lighting fixture according to claim 2, The permeable body includes a container-side glass that is installed to cover the viewing window. The lighting fixture is characterized in that the light-shielding means includes a second light-shielding member disposed to cover the field of view range in the space between the opening and the container-side glass.

4. In the lighting fixture described in claim 3, The lighting fixture is characterized in that the second light-shielding member comprises a casing-side light-shielding member attached to the lighting fixture casing and a container-side light-shielding member disposed on the container-side glass side, wherein the container-side light-shielding member is combined with the casing-side light-shielding member so as to be slidable relative to it along the direction in which the lighting fixture casing and the container face each other.

5. In the lighting fixture according to claim 2, A support portion for supporting the transparent glass is provided near the opening. A filler is filled between the inner surface of the support portion and the outer surface of the transparent glass. The lighting fixture is characterized in that the inner circumferential surface of the support portion is an inclined surface that decreases in diameter towards the inner circumferential side as it approaches the outside of the lighting fixture casing.

6. In the lighting fixture according to claim 5, The aforementioned lighting fixture casing is a cast product. A lighting fixture characterized in that the inner circumferential surface of the support portion that comes into contact with the filler is left as a cast surface without surface treatment.

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