Liquid leakage sensor

Abstract

To detect liquid leakage without contact with a liquid.SOLUTION: A determination circuit 104 determines that liquid leakage has occurred on a flat surface 151 when detecting a state in which an amount of light (an amount of received light) received by a second light receiving element 103 is larger than an amount of light (an amount of received light) received by a first light receiving element 102. When detection of a state continues for set time, the determination circuit 104 determines that the liquid leakage occurs on the flat surface 151.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid leakage sensor. [Background technology]

[0002] Conventional light refraction type liquid leakage sensors detect liquid leakage by the difference in the refractive index of the liquid causing a shift in the light path when the liquid comes into contact with the detection surface of the sensor (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-116138 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, the liquid comes into contact with the detection surface provided in the middle of the optical path. High-temperature liquids, corrosive liquids, etc. flow through the semiconductor device in which the liquid leakage sensor is used, and conventional liquid leakage sensors that detect by coming into contact with these liquids are required to be resistant to high temperatures and chemicals. For example, in the case of high-temperature liquids or corrosive liquids, it is not easy to detect leakage. Therefore, a liquid leakage sensor that does not come into contact with liquid is desired.

[0005] The present invention has been made to solve the above problems, and has an object to make it possible to detect liquid leakage without coming into contact with the liquid. [Means for solving the problem]

[0006] The liquid leakage sensor of the present invention comprises a light source that projects a beam of light onto a flat surface to be detected for liquid leakage, a first light receiving element that is positioned at a position where the light intensity of the light projected from the light source and reflected from a flat surface where no liquid leakage is occurring is highest and receives the light incident from the flat surface side, a second light receiving element that is positioned at a position farther from the light source than the first light receiving element in a direction parallel to the flat surface and receives the light incident from the flat surface side, and a determination circuit configured to determine that liquid leakage is occurring on the flat surface when it detects a state in which the amount of light received by the second light receiving element is greater than the amount of light received by the first light receiving element.

[0007] In one configuration example of the above liquid leakage sensor, the sensor is provided with a memory circuit configured to store a first threshold value greater than the difference between the amount of light reflected from a flat surface where no liquid leakage is occurring and received by a first light receiving element, and the amount of light reflected from a flat surface where no liquid leakage is occurring and received by a second light receiving element, and a second threshold value greater than the first threshold value.When the determination circuit detects a state in which the difference in light amount obtained by subtracting the amount of light received by the first light receiving element from the amount of light received by the second light receiving element is greater than the first threshold value and less than the second threshold value, the determination circuit determines that liquid leakage is occurring on the flat surface.

[0008] In one configuration example of the above liquid leakage sensor, the sensor is provided with a memory circuit configured to store a third threshold value greater than the difference between the amount of light reflected from a flat surface where no liquid leakage is occurring and received by the first light receiving element and the amount of light reflected from a flat surface where no liquid leakage is occurring and received by the second light receiving element, and a fourth threshold value greater than the sum of the amount of light reflected from a flat surface where no liquid leakage is occurring and the amount of light reflected from a flat surface where no liquid leakage is occurring and received by the first light receiving element and the amount of light reflected from a flat surface where no liquid leakage is occurring and received by the second light receiving element, and the determination circuit determines that liquid leakage is occurring on the flat surface when it detects a third state in which the difference between the amount of light received by the first light receiving element and the amount of light received by the second light receiving element is greater than the third threshold value and detects a fourth state in which the sum of the amount of light received by the first light receiving element and the amount of light received by the second light receiving element is greater than the fourth threshold value.

[0009] In one configuration example of the liquid leakage sensor described above, the determination circuit determines that liquid leakage has occurred on the flat surface when the detection of the state continues for a set time period. Effect of the Invention

[0010] As described above, according to the present invention, it is determined that liquid leakage has occurred on a flat surface based on the amount of light received by the first light receiving element and the amount of light received by the second light receiving element, so that liquid leakage can be detected without coming into contact with the liquid. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of a liquid leakage sensor according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a configuration diagram showing the configuration of a liquid leakage sensor according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a liquid leakage sensor according to an embodiment of the present invention will be described.

[0013] [Embodiment 1] First, a liquid leakage sensor according to a first embodiment of the present invention will be described with reference to Fig. 1. This liquid leakage sensor includes a light source 101, a first light receiving element 102, a second light receiving element 103, and a determination circuit 104.

[0014] The light source 101 projects a beam of light onto a plane 151 that is the object of liquid leakage detection. The light source 101 projects the beam of light perpendicular to the plane 151. The light emitted from the light source 101 is converted into a beam of light by, for example, a first optical system 111 and projected onto the plane 151. The plane 151 is, for example, a floor surface that is the object of liquid leakage detection.

[0015] The first light receiving element 102 is disposed at a position where the light intensity of the light projected from the light source 101 and reflected from the flat surface 151 where no liquid leakage occurs is the highest, and receives the light incident from the flat surface 151 side. The second light receiving element 103 is disposed at a position farther away from the light source 101 than the first light receiving element 102 in a direction parallel to the flat surface 151, and receives the light incident from the flat surface 151 side. The light reflected from the flat surface 151 is received by the first light receiving element 102 and the second light receiving element 103, for example, via a predetermined second optical system 112. The first light receiving element 102 and the second light receiving element 103 can be composed of, for example, a photodiode. For example, the installation position of the first light receiving element 102 can be determined so that the amount of light received by the first light receiving element 102 is maximized in a state where no liquid leakage occurs.

[0016] When the determination circuit 104 detects a state in which the amount of light (received light amount) received by the second light receiving element 103 is greater than the amount of light (received light amount) received by the first light receiving element 102, it determines that liquid leakage has occurred on the flat surface 151. If the determination circuit 104 continues to detect the state for a set period of time, it can determine that liquid leakage has occurred on the flat surface 151. However, it can also immediately determine that liquid leakage has occurred when the above-mentioned state is detected. Since the surface of the leaked liquid may be wavy, if the above-mentioned state is detected even for an instant, it is determined that liquid leakage has occurred.

[0017] The light reflected by the plane 151 where no liquid leakage occurs is mainly incident on the first light receiving element 102. In contrast, when liquid leakage occurs, the reflective surface is positioned higher than the plane 151, and the reflected light incident on the first light receiving element 102 decreases and the reflected light incident on the second light receiving element 103 increases. As a result, the amount of light received by the first light receiving element 102 is less than the amount of light received by the second light receiving element 103, and the determination circuit 104 can determine that liquid leakage has occurred.

[0018] According to the first embodiment, the liquid leakage sensor can be disposed at a position away from the plane (floor surface) on which liquid leakage is to be detected, so that liquid leakage can be detected without coming into contact with the liquid.

[0019] [Embodiment 2] Next, a liquid leakage sensor according to a second embodiment of the present invention will be described with reference to Fig. 2. This liquid leakage sensor includes a light source 101, a first light receiving element 102, and a second light receiving element 103. These elements are configured similarly to those in the first embodiment. In the second embodiment, a memory circuit 105 is further included.

[0020] The memory circuit 105 stores a first threshold value that is greater than the difference between the amount of light reflected from the plane 151 where no liquid leakage occurs and received by the first light receiving element 102, and the amount of light reflected from the plane 151 where no liquid leakage occurs and received by the second light receiving element 103, and a second threshold value that is greater than the first threshold value.

[0021] When the judgment circuit 104a detects a state in which the differential light amount obtained by subtracting the amount of light received by the first light receiving element 102 from the amount of light received by the second light receiving element 103 is greater than a first threshold value and smaller than a second threshold value, it judges that a liquid leak is occurring on the plane 151.

[0022] By making such a judgment, liquid leakage can be accurately judged even when the beam light projected by the light source 101 onto the plane 151 is tilted from the perpendicular to the plane 151 or when the leaked liquid absorbs the light.

[0023] In addition, the memory circuit 105 can be configured to store a third threshold value having a value greater than the difference between the amount of light reflected from the plane 151 where no liquid leakage is occurring and received by the first light receiving element 102, and the amount of light reflected from the plane 151 where no liquid leakage is occurring and received by the second light receiving element 103, and a fourth threshold value having a value greater than the sum of the amount of light reflected from the plane 151 where no liquid leakage is occurring and received by the first light receiving element 102, and the amount of light reflected from the plane 151 where no liquid leakage is occurring and received by the second light receiving element 103.

[0024] In this case, when the judgment circuit 104a detects a third state in which the difference in light amount between the amount of light received by the first light receiving element 102 and the amount of light received by the second light receiving element 103 is greater than a third threshold, and detects a fourth state in which the total amount of light received by the first light receiving element 102 and the amount of light received by the second light receiving element 103 is greater than a fourth threshold, it determines that liquid leakage has occurred on the plane 151.

[0025] By making such a determination, even if the reflectance of the flat surface 151 is low and the amount of light (light intensity) of the reflected light from the flat surface 151 is small, the liquid leakage can be accurately determined.

[0026] Even in these cases, the determination circuit 104a can determine that liquid leakage has occurred on the plane 151 if the detection of the state continues for a set period of time. However, it can also immediately determine that liquid leakage has occurred when the above-mentioned state is detected. Since the surface of the leaked liquid may be wavy, it can also be determined that liquid leakage has occurred if the above-mentioned state is detected even for an instant.

[0027] In addition, the above-mentioned judgment circuit can be a computer device equipped with a CPU (Central Processing Unit), a main memory device, an external memory device, a network connection device, etc., and the above-mentioned functions can be realized by the CPU operating (executing the program) according to a program expanded in the main memory device.

[0028] The above-mentioned memory circuit and judgment circuit can also be configured by a programmable logic device (PLD: Programmable Logic Device) such as an FPGA (field-programmable gate array). Each of the memory circuit and judgment circuit can be written into the FPGA by connecting a predetermined writing device. Furthermore, each of the above-mentioned circuits written into the FPGA can be confirmed by the writing device connected to the FPGA.

[0029] As described above, according to the present invention, it is determined that liquid leakage has occurred on a flat surface based on the amount of light received by the first light receiving element and the amount of light received by the second light receiving element, making it possible to detect liquid leakage without coming into contact with the liquid.

[0030] It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0031] 101...light source, 102...first light receiving element, 103...second light receiving element, 104...determination circuit, 111...first optical system, 112...second optical system, 151...plane.

Claims

1. A light source that projects a beam of light onto a plane that is a target for detecting liquid leakage; a first light receiving element that is disposed at a position where the light intensity of light projected from the light source and reflected from the flat surface where no liquid leakage occurs is the highest, and that receives light incident from the flat surface side; a second light receiving element that is disposed at a position farther from the light source than the first light receiving element in a direction parallel to the plane, and receives light incident from the plane side; a determination circuit configured to determine that a liquid leak has occurred on the flat surface when a state in which the amount of light received by the second light receiving element is greater than the amount of light received by the first light receiving element is detected; A liquid leakage sensor comprising:

2. 2. The liquid leakage sensor according to claim 1, a memory circuit configured to store a first threshold value having a value larger than a difference between an amount of light reflected from the flat surface where no liquid leakage occurs and received by the first light receiving element and an amount of light reflected from the flat surface where no liquid leakage occurs and received by the second light receiving element, and a second threshold value larger than the first threshold value; The determination circuit determines that a liquid leak has occurred on the flat surface when it detects a state in which a difference in light amount obtained by subtracting the amount of light received by the first light receiving element from the amount of light received by the second light receiving element is greater than the first threshold value and the difference in light amount is smaller than the second threshold value. Liquid leakage sensor.

3. 2. The liquid leakage sensor according to claim 1, a third threshold value having a value larger than the difference between the amount of light reflected from the flat surface where no liquid leakage occurs and received by the first light receiving element and the amount of light reflected from the flat surface where no liquid leakage occurs and received by the second light receiving element; and a fourth threshold value having a value larger than the sum of the amount of light reflected from the flat surface where no liquid leakage occurs and received by the first light receiving element and the amount of light reflected from the flat surface where no liquid leakage occurs and received by the second light receiving element; a memory circuit configured to store The determination circuit detects a third state in which a difference in light amount between the amount of light received by the first light receiving element and the amount of light received by the second light receiving element is greater than the third threshold, and determines that liquid leakage has occurred on the flat surface when it detects a fourth state in which a total light amount of the amount of light received by the first light receiving element and the amount of light received by the second light receiving element is greater than the fourth threshold. Liquid leakage sensor.

4. The liquid leakage sensor according to any one of claims 1 to 3, The determination circuit is a liquid leakage sensor that determines that a liquid leak is occurring on the flat surface when the detection of the state continues for a set time period.

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