JP3119570B2 - Non-contact liquid detection method and detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a liquid such as a chemical solution or water accumulated on a floor, and more particularly to a detection method and a detection device for detecting a liquid in a non-contact manner.

[0002]

2. Description of the Related Art For example, in a clean room for manufacturing semiconductor devices, liquids such as chemicals and water leaked from equipment sometimes accumulate on floors that are hard to see by workers. There is a risk that various kinds of accidents may occur, such as leakage of electricity or slipping and falling of the worker. For this reason, a device for detecting such a liquid has conventionally been provided. For example, a sensor cable connected to a constant current source is laid on the floor of a clean room, and this sensor cable is connected to a current detector so that if liquid accumulates on the floor, the sensor cable There has been proposed an apparatus in which a liquid is detected by changing a detection value of a current detector by changing an original resistance value when a short circuit state occurs upon touch.

As a technique for detecting a liquid, Japanese Patent Laid-Open Publication No. 56-142658 discloses a technique in which a liquid is collected in a water collecting section, and one end of the liquid collecting section is connected to a light source. There is proposed an optical fiber in which a bent portion and an end portion of an optical fiber in which the optical fiber is connected to a photodetector are provided. In this technique, the light transmitted through the optical fiber is affected by the refractive index of the liquid stored in the water collecting section, and the liquid is detected by using the change in the detection value of the photodetector at the other end. Detection techniques have also been proposed. Therefore, when using this technology for detecting the liquid on the floor described above, a water collecting part is provided on a part of the floor,
It suffices to arrange an optical fiber facing this water collecting part.

[0004]

However, in the above-mentioned technique using the former sensor cable, when the liquid leaking onto the floor is an organic solvent or ultrapure water having extremely low conductivity, Since the degree to which the resistance value of the sensor cable is changed is extremely small, it is difficult to detect the liquid from the change in the resistance value, and the detection sensitivity is low, which is not practical. Also, the sensor cable may become dirty and the detection function may be impaired,
In addition, there is a risk of being damaged by stepping on the feet of workers, etc.
Maintenance becomes troublesome because it needs to be replaced periodically.

In the technology described in the above-mentioned publication, a water collecting portion needs to be provided on the floor surface. Therefore, even if the water collecting portion is provided in a part of a large area such as a clean room, the water collecting portion is provided. Since the leaked liquid does not always accumulate in the water collecting portion, it is difficult to perform reliable detection. In addition, since this technique is based on the premise that the optical fiber is directly in contact with the liquid, the optical fiber is likely to deteriorate depending on the type of chemical, and the optical fiber must be replaced frequently, which requires maintenance. Disadvantage in terms of performance.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-contact liquid detecting method and a detecting device which can detect a liquid with high reliability and facilitate maintenance.

[0007]

According to the present invention, there is provided a non-contact type liquid detecting apparatus comprising: a laser oscillator for projecting a laser beam toward a part of a surface for detecting the presence or absence of a liquid ;
The photodetector to be detected and the data of the received light intensity at the photodetector
Means for processing the liquid to determine the presence or absence of the liquid.
The means for judging the presence or absence of light is based on the intensity of the light received by the photodetector with respect to the intensity of the light reflected by the photodetector in the diffused state of the laser light reflected on the surface in a state where no liquid is present on a part of the surface
Non degrees is that detect a liquid is present on a part of the surface when extremely increased near zero becomes or extremely to lower high
This is a contact type liquid detection device.
The shaker is configured to scan a predetermined area on the floor surface with laser light.
The light detector is a direct reflection of the laser light on the floor.
Is disposed at a position where light is not received.

[0008]

[0009]

[0010]

[0011]

[Function] When there is no liquid at the place where the detection is performed,
Since the laser light is scattered at the time of reflection, by detecting the scattered light with a photodetector, it is possible to determine from the data of the received light intensity that no liquid exists. When a liquid exists, the laser light is reflected only in a specific direction, so the light detection hardly detects the reflected light, or almost all of the reflected light is detected. Becomes an extreme value, and it can be determined that liquid exists.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention. A laser oscillator 11 for partially emitting coherent laser light is provided on a floor such as a clean room, and the emitted laser light L is projected on a part of the floor 1. In this case, the location 2 where the laser beam L is projected is set to be a location for detecting whether or not the liquid is leaking or a location near the location. The laser oscillator 11 is provided at a low height along the floor 1 so as not to interfere with various devices (not shown) arranged on the floor 1.

On the other hand, at another position on the floor 1 different from the laser oscillator 11, a photodetector 12 capable of receiving a laser beam and detecting the intensity of the received laser beam (amount of received light) is provided. I do. The photodetector 12 is located at a position not directly facing the laser beam L emitted from the laser oscillator 11, in this case, on the same side as the laser oscillator 11 with respect to a part 2 of the floor 1 on which the laser beam L is projected. Located on one side. The light detector 12 has a wide light receiving angle to some extent, and is arranged so as to include the part 2 of the floor within the light receiving angle. The photodetector 12 is connected to a processing determination unit 14 for processing data obtained by receiving light to determine the presence of a liquid.

According to such a configuration, as shown in FIG. 2A, when a liquid such as a chemical liquid does not leak to the floor 1,
The laser light L emitted from the laser oscillator 11 is reflected on the floor 1 when projected on a part of the floor at a specific angle. At this time, most of the reflected light is reflected in accordance with the law of reflection, but since the surface of the floor 1 is formed as a rough surface when viewed microscopically, a part of the coherent laser light L is At 1, the light is reflected in a diffused state and is directed in all directions as scattered light S. Therefore, in the photodetector 12 arranged on one side of the laser oscillator 11, the scattered light S
Is received, and data of the received light intensity of a certain value is output.

On the other hand, as shown in FIG. 2 (b), when the liquid 3 is leaking to the floor 1, the laser light L emitted from the laser oscillator 11 is applied to the surface of the liquid 3 or its edge at a specific angle. When projected, since the surface of the liquid 3 is smooth,
The laser light L is totally reflected by the liquid 3 and is reflected only in a specific direction. Therefore, in the photodetector 12, the light L ′ reflected on the floor surface, that is, the surface of the liquid 3 is reflected.
Is extremely low, and as a result, the data of the received light intensity is close to zero.

Alternatively, depending on the projection position of the laser beam L onto the liquid 3, the laser beam L may be reflected toward the photodetector 12. In this case, almost all of the reflected light L 'is detected by the photodetector. 12 to be detected,
The received light intensity data has an extremely high value.

As shown in FIG. 2C, when an object 4 other than a liquid is present on the floor surface, when the laser beam L is projected on the object 4, as in the case of the floor surface, Object 4
The laser light L is reflected as scattered light S by the rough surface. Therefore, in the photodetector 12, the scattered light S
By receiving a part of, as in the case of FIG.
Data of the received light intensity of a certain value is output.

Therefore, in this detecting device, when the liquid 3 leaks to the floor 1, the data of the light receiving intensity at the photodetector 12 becomes extremely low or extremely high. Then, it is possible to detect the leakage of the liquid by confirming the change in the value of the data. For this reason, it is possible to detect the leakage of the liquid without contacting the floor surface, and it is possible to detect the leakage of the liquid with high accuracy without each part of the detection device being contaminated or damaged by the liquid. It is possible and extremely advantageous in terms of maintenance.

FIG. 3 is a diagram showing a schematic configuration of a reference example of the present invention. This embodiment is also configured as a detection device for detecting leakage of liquid on the floor surface, and includes a laser oscillator and a photodetector as in the first embodiment.
However, in this reference example, the photodetectors 12 and 13 having the same configuration are used.
Are provided, and one of the first photodetectors 12 is disposed on one side of the laser oscillator 11 as in the first embodiment, but the other one of the second photodetectors 13 is provided. Is disposed at a position directly opposite to the laser oscillator 11 with a part 2 of the floor 1 on which the laser light is projected. Each of the light detectors 12 and 13 is connected to a processing determination unit 14.

Therefore, in this configuration, as shown in FIG. 4A, when there is no liquid on the floor 1, most of the laser light L projected from the laser oscillator 11 is reflected by the floor 1, The light is received by the second photodetector 13. A part of the laser light L is reflected in a scattered state because the floor surface 1 is rough as in the first embodiment, and a part of the scattered light S is received by the first photodetector 12. You. Therefore, the data of the received light intensity of the first photodetector 12 becomes a certain value as in the first embodiment, while the second photodetector 1
The light receiving intensity data of No. 3 has a relatively high value.

On the other hand, as shown in FIG. 4B, in a state where the liquid 3 is leaking to a part of the floor 1, the laser beam L is applied only at a specific angle because the surface of the liquid 3 is smooth. Is reflected. Therefore, the data of the received light intensity of the first photodetector 12 is extremely low or extremely high as in the first embodiment. Similarly, the second photodetector 13 has extremely high or very low data of the received light intensity depending on the angle of reflection on the surface of the liquid 3. And in this case, the first photodetector 12 and the second photodetector 13
The received light intensity data does not increase or decrease at the same time, but values in opposite directions. Or,
Both values are low.

Further, as shown in FIG. 4 (c), when an object 4 other than a liquid is present on the floor 1, when the laser beam L is projected on the object 4, Similarly,
The laser light L is reflected as scattered light S by the rough surface of the object 4. Therefore, in the first photodetector 12,
By receiving a part of the scattered light S, data of the received light intensity having a certain value is output as in the case of FIG. On the other hand, since the second photodetector 13 cannot receive at least the directly reflected laser light, the data of the received light intensity is extremely low.

Therefore, it is possible to detect the leakage of the liquid on the floor surface by monitoring the light receiving intensities of the first photodetector 12 and the second photodetector 13 and considering a combination of these data. Alternatively, the presence of an object can be detected. In particular, in this reference example, the presence or absence of the liquid is accurately detected by taking into account the received light intensity data of the second photodetector 13 even when the reflection angle of the laser light is variously changed depending on the state of the liquid. It becomes possible. In addition, by using the second photodetector 13, it is possible to detect the case where no liquid or object is present on the floor surface and the case where an object is present. More effective detection can be performed than in the difficult first embodiment.

Here, in each of the above embodiments, one laser oscillator and one or two photodetectors are used. However, by increasing the number of laser oscillators and photodetectors, more accurate detection is possible. It can be carried out. In particular, if laser light is emitted in different plane directions using two or more laser oscillators, it is possible to detect liquid leakage over a wide range of the floor surface. Further, by using three or more photodetectors, it is possible to detect the liquid leakage state more finely.

Alternatively, instead of providing a plurality of laser oscillators, a floor surface can be scanned by one laser oscillator, and data of the received light intensity at the photodetector is obtained in synchronization with the scanning, thereby obtaining the floor surface. It is also possible to detect a wide area of the surface without fail. In this case, the photodetector may be configured to scan the light receiving range in synchronization with the laser oscillator.

The means for processing the data of the received light intensity obtained by the photodetector to detect leakage of the liquid can be easily realized by data processing using a personal computer.

Further, in the above embodiment, the present invention is applied to the case of detecting a liquid leaking to the floor, but a detecting device for detecting whether or not the liquid exists in various liquid containers. Needless to say, the present invention can be similarly applied.

[0028]

The present invention described above, according to the present invention includes a scattering of the laser light when the liquid material is not present, the received light intensity in the light detector at a reflection in a specific direction of the laser light when the presence of liquid it is possible to detect the presence or absence of liquid on the basis of Rukoto be different. This makes it possible to detect the presence or absence of the liquid without contacting the liquid, prevent the detector from being contaminated or deteriorated by the liquid, enable reliable detection, and facilitate maintenance. It has the effect of becoming.

Further, the non-contact type liquid detecting device of the present invention
While maintaining the non-contact state it is possible to detect the presence or absence of liquid to the liquid body.

Furthermore, the non-contact type liquid detecting device of the present invention
Indicates that the surface is a floor surface and the laser oscillator
A scannable configured surface, it is possible to detect the presence or absence of the liquid over a large area.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an inspection method in the first embodiment.

FIG. 3 is a diagram showing a schematic configuration of a reference example of the present invention.

FIG. 4 is a diagram for explaining an inspection method in a reference example.

Claims (1)

(57) [Claims] 1. A laser oscillator for projecting a laser beam toward a part on a surface for detecting the presence or absence of a liquid, a photodetector for detecting a reflected light of the laser beam, and a light receiving intensity of the photodetector. Means for processing data to determine the presence or absence of a liquid, wherein the means for determining the presence or absence of the liquid is such that the laser light reflected on the surface in a state where the liquid does not exist on a part of the surface Liquid is present in a part of the surface when the detected light intensity is extremely low and close to zero or extremely high with respect to the received light intensity of the reflected light in the diffused state in the photodetector. a non-contact type liquid detection device that detect and, the surface is a floor surface, the laser oscillator,
The laser beam can scan a predetermined area of the floor surface.
And the photodetector is configured to directly detect the laser light on the floor surface.
It is located at a position where it does not receive tangential reflection light.
Non-contact type liquid detection device that.