Fluid density gradient detecting device

Abstract

A fluid density gradient detecting device (1) comprises a first light-reflecting member (30), a first background member (20) provided with a first design pattern (20a), an imaging unit (10) that images the first design pattern (20a) through a first optical path (P1), and images the first design pattern (20a) through a second optical path (P2), and an information processing unit (100) that calculates the density gradient of a target area (90) of a fluid being observed, on the basis of a first image of the first design pattern (20a) imaged through the first optical path (P1), and a second image of the first design pattern (20a) imaged through the second optical path (P2), wherein the first optical path (P1) reaches from the first design pattern (20a) to the imaging unit (10) via the target area (90) and the first light-reflecting member (30), in this order, and the second optical path (P2) reaches from the first design pattern (20a) to the imaging unit (10) via the first light-reflecting member (30) and the target area (90), in this order.

Description

Fluid density gradient detection device

[0001] The present disclosure relates to a fluid density gradient detection device that detects the density gradient of a fluid.

[0002] Known techniques for visualizing density gradients in fluids include the Schlieren method and the background-oriented Schlieren method (BOS method). While the Schlieren method requires an optical system that generates parallel light and a knife edge that blocks the light beam, the BOS method makes it possible to visualize density gradients in fluids with a simple configuration that combines a background image and a camera.

[0003] Patent document 1 proposes a device based on the principle of the BOS method, which uses an imaging device to capture an image of the fluid being observed against a background of a periodic pattern, and outputs an image showing the density gradient of the fluid in the target area based on the captured image.

[0004] Japanese Patent Application Laid-Open No. 2022-184123

[0005] However, in the device of Patent Document 1, in order to improve sensitivity, it is necessary to increase the distance between the target area of ​​the fluid (i.e., the area where the airflow is generated) and the background pattern, which poses the problem of the device becoming large.

[0006] An object of the present disclosure is to provide a fluid density gradient detection device that can be made smaller.

[0007] The fluid density gradient detection device disclosed herein is a device for detecting the density gradient of a target area of ​​a fluid to be observed, and includes: a first background member having a first pattern pattern arranged in a position opposite a first light-reflecting member that reflects light; an imaging unit that images the first pattern pattern via the first light-reflecting member through a first light path that includes the target area, and images the first pattern pattern via the first light-reflecting member through a second light path that includes the target area; and an information processing unit that calculates the density gradient of the target area of ​​the fluid to be observed based on a first image of the first pattern pattern imaged through the first light path and a second image of the first pattern pattern imaged through the second light path, wherein the first light path extends from the first pattern pattern through the target area and the first light-reflecting member in that order to reach the imaging unit, and the second light path extends from the first pattern pattern through the first light-reflecting member and the target area in that order to reach the imaging unit.

[0008] According to the fluid density gradient detection device of the present disclosure, the device can be made smaller.

[0009] FIG. 1 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a first embodiment. FIG. 2 is a front view showing an example of a first pattern in the fluid density gradient detection device according to the first embodiment. FIG. 3 is a diagram showing an example of the hardware configuration of the information processing unit of FIG. 1. FIG. 4 is a diagram for explaining a method of calculating the position of a target area in the fluid density gradient detection device according to the first embodiment. FIG. 5 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a second embodiment. FIG. 6 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a third embodiment. FIG. 7 is a front view showing an example of a second pattern in the fluid density gradient detection device according to the third embodiment. FIG. 8 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a fourth embodiment. FIG. 9 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a fifth embodiment. FIG. 10 is a diagram showing an example of a first pattern in the fluid density gradient detection device according to the fifth embodiment. FIG. 11 is a diagram schematically showing the configuration of a fluid density gradient detection device according to a sixth embodiment. FIG. 12 is a front view showing an example of a first pattern in the fluid density gradient detection device according to the sixth embodiment.

[0010] A fluid density gradient detection device according to an embodiment will be described below with reference to the drawings. The fluid density gradient detection device is a device that detects the density gradient of a target area of ​​a fluid to be observed (e.g., a transparent gas or transparent liquid, or a liquid or solid that can transmit light of a wavelength that can be imaged by an imaging unit, etc.) and displays the movement of the fluid as an image. The fluid density gradient detection device is also called an airflow visualization device. The following embodiments are merely examples, and embodiments can be combined and modified as appropriate. In addition, in the drawings, components having the same or similar functions are assigned the same reference numerals.

[0011] <<Embodiment 1>> Fig. 1 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 1 according to embodiment 1. Fig. 2 is a front view illustrating an example of a first pattern 20a in the fluid density gradient detection device 1. As shown in Fig. 1, the fluid density gradient detection device 1 has a first light reflecting member 30, a first background member 20, an imaging unit 10, and an information processing unit 100.

[0012] The first light reflecting member 30 has a light reflecting surface 30a that reflects light. The first light reflecting member 30 is, for example, a mirror.

[0013] The first background member 20 has a first pattern 20a disposed in a position facing the first light reflecting member 30. As shown in Fig. 2, the first pattern 20a includes a plurality of stripes arranged regularly (e.g., periodically). The extending direction of the stripes, the spacing between adjacent stripes, the width of each stripe, and the density or color of the stripes are set in advance.

[0014] The imaging unit 10 has an imaging surface 10a onto which light is incident. The imaging unit 10 is also referred to as an imaging device or a camera. In the first embodiment, the imaging unit 10 images the first pattern pattern 20a through a first optical path P1 including the target area 90 via the first light reflecting member 30, and also images the first pattern pattern 20a through a second optical path P2 including the target area 90 via the first light reflecting member 30. When imaging the target area 90 through the first optical path P1, the imaging unit 10 images the target area 90 before light is reflected by the light reflecting surface 30a. On the other hand, when imaging the target area 90 through the second optical path P2, the imaging unit 10 images the target area 90 after light is reflected by the light reflecting surface 30a. The target area 90 is a space where the first optical path P1 and the second optical path P2 overlap. In the first embodiment, the first optical path P1 travels from the first pattern pattern 20a, through the target area 90 and the first light reflecting member 30, in that order, to the imaging surface 10a of the imaging unit 10. The second optical path P2 travels from the first pattern pattern 20a, through the first light reflecting member 30 and the target area 90, in that order, to the imaging surface 10a of the imaging unit 10.

[0015] The information processing unit 100 is, for example, a computer. Using the principles of the BOS method, the information processing unit 100 calculates the density gradient of the target area 90 of the observed fluid based on a first image of the first pattern pattern 20a captured through the first optical path P1 and a second image of the first pattern pattern 20a captured through the second optical path P2. The information processing unit 100 can determine whether the calculated density gradient exceeds a preset threshold, present information indicating the position of the target area 90, and display an image of the target area 90 and the airflow around it (for example, on an image display device). The airflow visualization method is a well-known technique, and for example, the BOS (Background-Oriented Schlieren) method described in Non-Patent Document 1 can be used.

[0016] Thoth Children, "Gas Visualization Methods," URL: http: / / www.thothchildren.com / subject / 5c03421a41f88f267249f6a1

[0017] In order to observe the target area 90 through two optical paths (first and second optical paths P1 and P2 in FIG. 1), the first light reflecting member 30 and the pattern must be large enough relative to the observation target area.

[0018] The BOS method for visualizing density gradients in fluids has the advantage that the greater the distance between the location where the density gradient occurs and the pattern, the greater the sensitivity, making it possible to visualize even small density gradients.In conventional methods, in order to increase sensitivity, it was necessary to increase the distance between the imaging unit, which is placed on either side of the target area, and the pattern pattern, which increased the size of the entire device and made it impossible to use in small spaces.

[0019] In the fluid density gradient detection device 1 according to the first embodiment, the light emitted from the first pattern pattern 20a is reflected by the first light reflecting member 30, passes through the target area 90, and is incident on the imaging surface 10a of the imaging unit 10, thereby making it possible to reduce the size of the entire device. Even if the size is small, the distance on the optical path between the target area 90 and the first pattern pattern 20a can be increased, thereby improving sensitivity.

[0020] Fig. 3 is a diagram showing an example of the hardware configuration of the information processing unit 100 in Fig. 1. The information processing unit 100 has a processor 101 such as a CPU (Central Processing Unit), a memory 102 as a storage device such as a RAM (Random Access Memory), a storage device 103 as a non-volatile storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and an interface 104 to which the imaging unit 10 and a display device are connected. These components may be configured using dedicated processing circuits.

[0021] The processor 101 can execute the fluid density gradient detection method according to embodiment 1. The program for executing the fluid density gradient detection method is recorded on a recording medium such as an SD memory card (Secure Digital memory card) or a USB (Universal Serial Bus) memory card, or is provided by downloading via a network. The hardware configuration shown in FIG. 12 is an example, and various modifications to the hardware configuration are possible.

[0022] 4 is a diagram illustrating a method for calculating the position of the target area 90 in the fluid density gradient detection device 1 according to embodiment 1. As shown in FIG. 4, even if the distance between the target area 90 and the first pattern pattern 20a is short, the occurrence of a density gradient of the fluid in the target area 90 causes image changes at two locations as viewed from the imaging unit 10. Therefore, based on the positional information of the two locations on the image of the imaging unit 10, the distance from the imaging unit 10 to the location where the density gradient occurs can be calculated using the principle of triangulation.

[0023] 4 , if the angle between the optical axis of the imaging unit 10 (i.e., the camera optical axis) and the first optical path P1 is α, the distance from the camera optical axis to the target area 90 is D, the distance between the light reflecting surface 30a of the first light reflecting member 30 and the first pattern pattern 20a is L, the distance between the target area 90 and the first pattern pattern 20a is Z, and the image of the target area 90 is 90', then the following equation holds: D = (2L - Z) × tan α. If the angle between the optical axis of the imaging unit 10 (i.e., the camera optical axis) and the second optical path P2 is β, then the following equation holds: D = Z × tan β. Therefore, the following holds true: (2L - Z) x tan α = Z x tan β 2L x tan α - Z x tan α = Z x tan β 2L x tan α = Z x (tan β + tan α) Z = 2L x tan α / (tan β + tan α).

[0024] As described above, the distance Z between the imaging unit 10 and the target area 90 can be calculated from the distance L and the angles α and β. In other words, the information processing unit 100 can calculate the position of the target area 90 based on the distance L between the first pattern pattern 20a and the first light reflecting member 30, the angle α which is the angle of incidence of the first optical path P1 with respect to the imaging surface 10a of the imaging unit 10, and the angle β which is the angle of incidence of the second optical path P2 with respect to the imaging surface 10a.

[0025] In this way, according to the first embodiment, the position of airflow generation can be calculated using a single imaging unit 10 (camera).

[0026] Second Embodiment FIG. 5 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 2 according to the second embodiment. The fluid density gradient detection device 2 differs from the fluid density gradient detection device 1 according to the first embodiment in that it does not have a first light reflecting member 30. In other words, the fluid density gradient detection device 2 according to the second embodiment uses the surface of another device (i.e., the first light reflecting surface 31a) or a mirror provided on another device as the first light reflecting member 31. The other device is not particularly limited and may be part of a facility or building. The other device is, for example, a device that uses gas (e.g., an air conditioner). Except for this point, the second embodiment is the same as the first embodiment.

[0027] Third Embodiment FIG. 6 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 3 according to a third embodiment. FIG. 7 is a diagram illustrating an example of a second pattern 32a in the fluid density gradient detection device 3. The fluid density gradient detection device 3 differs from the fluid density gradient detection device according to the first embodiment in that it further includes a second background member 32 that is disposed over the light reflecting surface 30a of the first light reflecting member 30 and has a second pattern pattern 32a including a plurality of periodically arranged regions with different light transmittances. The second pattern pattern 32a is a pattern of varying light transmittances. As shown in FIG. 7, the second pattern pattern 32a may have, for example, a plurality of stripes extending in a direction intersecting (e.g., perpendicular to) the first pattern pattern 20a. The second pattern pattern 32a is not limited to that shown in FIG. 7.

[0028] In embodiment 3, the first image acquired by the imaging unit 10 is obtained by imaging the first pattern pattern 20a and the second pattern pattern 32a through the first optical path P1, and the second image acquired by the imaging unit 10 is obtained by imaging the first pattern pattern 20a and the second pattern pattern 32a through the second optical path P2.

[0029] By forming the second background member 32 from a transmission filter, the position of the target area 90 can be calculated based on two types of pattern patterns. For example, if the first pattern pattern 20a and the second pattern pattern 32a are stripe patterns that are orthogonal to each other, a filter that extracts high-frequency components of the captured image along the extension direction of each stripe is applied, and an area where only one frequency component is reduced can be used to detect the density gradient in the second optical path P2, and an area where both frequency components are reduced can be used to detect the density gradient in the first optical path P1.

[0030] Furthermore, by making the first pattern pattern 20a and the second pattern pattern 32a different colors and using a color camera as the imaging unit 10, it is possible to apply a filter that decomposes the captured image into color components and extracts high-frequency components, thereby distinguishing between the first optical path P1 and the second optical path P2.

[0031] Except for the points mentioned above, the third embodiment is the same as the first embodiment. Furthermore, the third embodiment is applicable to the fourth to sixth embodiments described below.

[0032] Fourth Embodiment Figure 8 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 4 according to a fourth embodiment. The fluid density gradient detection device 4 according to the fourth embodiment differs from the fluid density gradient detection device 1 according to the first embodiment in that it includes a second light reflecting member 40 arranged to face the first light reflecting member 30. The second light reflecting member 40 is, for example, a mirror that reflects light. The light reflecting surface 40a of the second light reflecting member 40 is arranged alongside the first pattern 20a.

[0033] In the fourth embodiment, the first optical path P1 travels from the first pattern pattern 20a through the first light reflecting member 30, the second light reflecting member 40, the target area 90, and the first light reflecting member 30 in this order, before reaching the imaging surface 10a of the imaging unit 10. The second optical path P2 travels from the first pattern pattern 20a through the first light reflecting member 30, the second light reflecting member 40, the first light reflecting member 30, and the target area 90 in this order, before reaching the imaging surface 10a of the imaging unit 10.

[0034] According to embodiment 4, the second light-reflecting member 40 is additionally arranged in a position directly opposite the first light-reflecting member 30, side-by-side with the imaging surface 10a of the imaging unit 10, so that the distance between the target area 90 and the first pattern pattern 20a can be made longer, thereby improving the accuracy of detecting the density gradient.

[0035] Except for the points mentioned above, the fourth embodiment is the same as the first embodiment. Furthermore, the fourth embodiment is applicable to the first and second embodiments and the fifth and sixth embodiments described below.

[0036] Fifth Embodiment FIG. 9 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 5 according to a fifth embodiment. FIG. 10 is a diagram illustrating an example of a first pattern pattern 21 in the fluid density gradient detection device 5 according to the fifth embodiment. In the fifth embodiment, the imaging unit 10 is a color camera with color separation capabilities. The fluid density gradient detection device 5 according to the fifth embodiment differs from the fluid density gradient detection device 1 according to the first embodiment in that the first pattern pattern 21 includes a first color region 21a and a second color region 21b. The first color and the second color are different colors. It is desirable that the first color and the second color be a combination of colors that can be easily separated as the output of the imaging unit 10. The first color and the second color are, for example, complementary colors.

[0037] In the fifth embodiment, the first optical path P1 travels from the first color region 21a of the first pattern pattern to the imaging surface 10a of the imaging unit 10, passing through the target area 90 and the first light reflecting member 30 in that order. The second optical path P2 travels from the second color region 21b of the first pattern pattern to the imaging surface 10a of the imaging unit 10, passing through the first light reflecting member 30 and the target area 90 in that order.

[0038] According to embodiment 5, the first pattern pattern 21 includes a first color area 21a and a second color area 21b, and the imaging unit 10 is a color camera, so that it is easy to distinguish between the first optical path P1 and the second optical path P2 based on the captured first image and second image.

[0039] Except for the points mentioned above, the fifth embodiment is the same as the first embodiment. Moreover, the fifth embodiment is applicable to the first to fourth embodiments.

[0040] Sixth Embodiment Figure 11 is a diagram schematically illustrating the configuration of a fluid density gradient detection device 6 according to the sixth embodiment. Figure 12 is a diagram illustrating an example of a first pattern pattern 22c in the fluid density gradient detection device 6 according to the sixth embodiment. In the sixth embodiment, the imaging unit 10 is a color camera with color separation capability. The fluid density gradient detection device 6 according to the sixth embodiment differs from the fluid density gradient detection device 1 according to the first embodiment in that the first light-reflecting member 33 includes a first light-reflecting surface 33a and a second light-reflecting surface 33b (e.g., multiple mirrors) and the first pattern pattern 22c includes a first color region 22a and a second color region 22b arranged so as to overlap the first color region 22a.

[0041] As shown in Fig. 12, the first pattern pattern 22c has a first color region 22a and a second color region 22b arranged so as to overlap the first color region 22a. The first color and the second color are different colors. It is desirable that the first color and the second color are a combination of colors that can be easily separated as the output of the imaging unit 10. The first color and the second color are, for example, complementary colors.

[0042] In the sixth embodiment, the first light reflecting surface 33a and the second light reflecting surface 33b face in different directions. In the example of Fig. 11, the second light reflecting surface 33b is inclined with respect to the first light reflecting surface 33a so as to direct light from the first pattern pattern 22c toward the imaging surface 10a of the imaging unit 10. The first light path P1 travels from the first pattern pattern 22c to the imaging unit 10 via the target area 90 and the first light reflecting surface 33a in this order. The second light path P2 travels from the first pattern pattern 22c to the imaging unit 10 via the second light reflecting surface 33b and the target area 90 in this order.

[0043] In the sixth embodiment, the first light reflecting member 33 has the first light reflecting surface 33a and the second light reflecting surface 33b (e.g., multiple mirrors) arranged at an angle, thereby making it possible to reduce the size of the device in the height direction in FIG. 11 and to miniaturize the entire device.

[0044] Except for the points mentioned above, the sixth embodiment is the same as the first embodiment. Moreover, the sixth embodiment is applicable to the first to fifth embodiments.

[0045] The fluid density gradient detection devices 1 to 6 according to the first to sixth embodiments can be used, for example, as devices for detecting gas leaks from gas-using equipment or gas piping. Examples of gas-using equipment include air conditioners that use refrigerant gas and equipment and facilities that use fuel gas.

[0046] 1 to 6 Fluid density gradient detection device, 10 Imaging unit, 10a Imaging surface, 20, 21, 22 First background member, 20a, 22c First pattern pattern, 21a, 22a First pattern pattern (first color area), 21b, 22b First pattern pattern (second color area), 30, 31, 33 First light-reflecting member, 30a Light-reflecting surface, 32 Second background member, 32a Second pattern pattern, 33a First light-reflecting surface, 33b Second light-reflecting surface, 40 Second light-reflecting member, 90 Target area, 100 Information processing unit, P1 First light path, P2 Second light path.

Claims

1. A fluid density gradient detection device for detecting the density gradient of a target area of ​​an observed fluid, comprising: a first background member having a first pattern pattern arranged in a position facing a first light reflecting member that reflects light; an imaging unit that images the first pattern pattern through a first light path that includes the target area via the first light reflecting member, and images the first pattern pattern through a second light path that includes the target area via the first light reflecting member; and an information processing unit that calculates the density gradient of the target area of ​​the observed fluid based on a first image of the first pattern pattern imaged through the first light path and a second image of the first pattern pattern imaged through the second light path, wherein the first light path passes from the first pattern pattern through the target area and the first light reflecting member in that order to reach the imaging unit; and the second light path passes from the first pattern pattern through the first light reflecting member and the target area in that order to reach the imaging unit.

2. The fluid density gradient detection device according to claim 1, further comprising the first light reflecting member.

3. A fluid density gradient detection device as described in claim 2, further comprising a second background member arranged over the light reflecting surface of the first light reflecting member and having a second pattern including a plurality of periodically arranged regions having different light transmittances, wherein the first image is obtained by imaging the first pattern pattern and the second pattern pattern through the first light path, and the second image is obtained by imaging the first pattern pattern and the second pattern pattern through the second light path.

4. A fluid density gradient detection device as described in claim 1 or 2, characterized in that it has a second light reflecting member arranged opposite the first light reflecting member, and the first light path reaches the imaging unit by passing from the first pattern pattern through the first light reflecting member, the second light reflecting member, the target area, and the first light reflecting member in that order, and the second light path reaches the imaging unit by passing from the first pattern pattern through the first light reflecting member, the second light reflecting member, the first light reflecting member, and the target area in that order.

5. A fluid density gradient detection device as described in claim 1 or 2, characterized in that the imaging unit is a color camera with color separation capability, the first pattern pattern includes a first color area and a second color area, the first optical path reaches the imaging unit from the first color area of ​​the first pattern pattern, passing through the target area and the first light reflecting member in this order, and the second optical path reaches the imaging unit from the second color area of ​​the first pattern pattern, passing through the first light reflecting member and the target area in this order.

6. The fluid density gradient detection device according to claim 5, characterized in that the first color and the second color are different colors.

7. The fluid density gradient detection device of claim 2, characterized in that the imaging unit is a color camera with color separation capability, the first light reflecting member includes a first light reflecting surface and a second light reflecting surface facing in a different direction from the first light reflecting surface, the first pattern pattern includes a first color area and a second color area arranged to overlap the first color area, the first optical path passes from the first pattern pattern through the target area and the first light reflecting surface in this order to reach the imaging unit, and the second optical path passes from the first pattern pattern through the second light reflecting surface and the target area in this order to reach the imaging unit.

8. A fluid density gradient detection device as described in any one of claims 1 to 7, characterized in that the information processing unit calculates the position of the target area based on the distance between the first pattern and the first light reflecting member, the angle of incidence of the first light path with respect to the imaging surface of the imaging unit, and the angle of incidence of the second light path with respect to the imaging surface.

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