JP3849762B2 - Optical unit for liquid detection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical unit for liquid detection, for example, an optical unit for liquid detection suitable for being attached to a liquid receiving container in order to detect liquid leakage in a semiconductor manufacturing facility.
[0002]
[Prior art]
For example, various processing liquids such as water, hydrochloric acid, highly flammable liquids, corrosive liquids are used in semiconductor manufacturing equipment, and a large number of pipes are provided as passages for these liquids. In these pipes, a valve device is interposed in the middle, or the pipes are connected by a joint. Corrosion-resistant liquid receiving containers such as stainless steel are placed below the connection between the pipe and the valve device and the connection between the pipes (seam). In the unlikely event that processing liquid leaks from the connection, I try to accept the fluid. The liquid receiving container is provided with a sensor for detecting liquid leakage almost directly below the connecting portion so as to detect liquid leakage promptly.
[0003]
10 is a perspective view of a conventional liquid detection optical unit attached to the liquid receiving container, FIG. 11 is a cross-sectional view taken along the arrow XI-XI in FIG. 10, and FIG. 12 is the arrow XII-XII in FIG. FIG. 10 to 12, the liquid detection optical unit (hereinafter simply referred to as “optical unit”) 20 is made of, for example, a fluororesin member in which the housing 21 and the fixing portion 22 have translucency and chemical resistance. For example, the fixing portion 22 is integrally formed, and is attached to a mounting bolt 41 fixed to the upper surface 40a of a stainless steel liquid receiving container 40 having corrosion resistance, and is detachably fixed by a fixing nut 42.
[0004]
As shown in FIGS. 11 and 12, in the housing 21, a light projecting optical system 27 comprising an optical fiber 24, a lens 25 and a light projecting prism 26, and a light receiving optical system comprising an optical fiber 28, a lens 29 and a light receiving prism 30 are provided. The system 31 is housed, and the lower surface 21c of the housing 21 is flat and is spaced apart in parallel with a slight gap between the upper surface 40a of the liquid receiving container 40 (hereinafter referred to as “liquid receiving surface 40a”). Opposite.
[0005]
The light introduced from the light emitting element (not shown) into the optical fiber 24 enters the projection prism 26 through the lens 25, is reflected downward by the projection prism 26, and a part thereof is indicated by a dotted line a. The light is reflected by the detection surfaces 21a and 21b of the housing 21 to reach the light receiving prism 30, and from the lens 29 to the light receiving element (not shown) through the optical fiber 28.
[0006]
As shown in FIG. 12, in the state where the optical unit 20 is set in the liquid receiving container 40, when there is no liquid leakage and no liquid leakage (liquid) is in contact with the detection surfaces 21a and 21b, the light projecting prism 26 A part of the emitted light is reflected by the detection surfaces 21a and 21b of the housing 21 as indicated by a dotted line a and reaches the light receiving prism 30 (hereinafter referred to as “reflected light a”), and a part thereof is indicated by a one-dot chain line b. As shown, the light is reflected by the liquid receiving surface 40a and reaches the light receiving prism 30 (hereinafter referred to as “reflected light b”), and is detected by the light receiving element from the lens 29 through the optical fiber 28.
[0007]
Further, when there is liquid leakage and the liquid leakage 1 drops in the vicinity of the opposite side of the fixed portion 22 of the housing 21 and comes into contact with the detection surface 21a, the light emitted from the light projection prism 26 is detected as indicated by the solid line c. Through the surface 21a, the liquid leaks (liquid) and only the reflected light b is detected. Further, when the leaked liquid 2 dropped on the upper surface of the fixing portion 22 near the housing 21 comes into contact with the detection surface 21b through the hole 22a penetrating the fixing portion 22, the light emitted from the light projecting prism 26 is detected on the detection surface. After being reflected by 21a, it passes through the detection surface 21b and reaches a liquid leak (liquid), and only the reflected light b is detected. In this manner, detection surfaces 21 a and 21 b that can contact the liquid are provided at the lower portion of the housing 21. In FIG. 12, hatching of the housing 21 is omitted for easy understanding of the light path.
[0008]
When the light amounts of the reflected light a and b are La and Lb, the light receiving amount of the light receiving element is Lb when the optical unit 20 is in the set state and there is no liquid leakage (La + Lb), Lb when there is liquid leakage, and in the non-set state Sometimes La. The light receiving element outputs a signal corresponding to the amount of received light, and sets the threshold value Lh for determining the amount of received light to (La, Lb) <Lh <(La + Lb), so that the optical unit 20 is in the set state. When the amount of light received by the light receiving element is lower than the threshold value Lh (Lb <Lh), it can be detected that there has been leakage.
[0009]
[Problems to be solved by the invention]
As described above, the optical unit 20 includes the housing 21 having the detection surfaces 21a and 21b and the fixing portion 22 provided on one side of the housing 21, and the lower surface of the fixing portion 22 is the liquid receiving surface 40a. Due to the contact and fixation, the leakage 1 and leakage 2 on the side close to the detection surfaces 21a and 21b reach these detection surfaces 21a and 21b and are detected in a short time even with a small amount of leakage. . However, the leaked liquid 3 dropped on the side far from the detection surfaces 21a and 21b, that is, around the fixed portion 22, for example, on the side 22f side, is blocked by the fixed portion 22 and hardly reaches the detection surfaces 21a and 21b. A large amount of liquid leakage is required before reaching the detection surfaces 21a and 21b. As a result, there is a problem that it takes time to detect the liquid leakage, or it may not be detected in some cases.
[0010]
The present invention has been made in view of the above points, and provides a liquid detection optical unit that can reduce the amount of detection liquid until liquid detection and can shorten the time until detection. Objective.
[0011]
[Means for Solving the Problems]
The liquid detecting optical unit as claimed in claim 1 in order to achieve the object,
<A> A housing having a detection surface made of a translucent material that can be contacted with liquid ;
< b > An optical path passing through the detection surface is formed and supported by the housing, and the amount of light propagating through the optical path is changed according to a change in refractive index depending on whether or not the liquid is in contact with the detection surface. A projected optical system and a received optical system,
< c > A fixing portion that protrudes from one side of the housing, is fixed to a liquid receiving container that receives the liquid, and supports the detection surface against the inner wall surface of the liquid receiving container ;
< d > Projecting on the fixed surface side of the fixing portion with respect to the liquid receiving container, and forming a gap between the fixed surface side and the inner wall surface of the liquid receiving container when fixed to the liquid receiving container. A spacer;
< e > A liquid conduction hole provided at a base portion of the fixed portion with respect to the housing and guiding the liquid to the detection surface .
[0012]
Preferably, the liquid receiving container according to claim 2 has corrosion resistance and wettability with respect to the liquid, and the fixing portion is made of a material having no wettability with respect to the liquid, A capillary phenomenon with respect to the liquid is caused in a gap formed between the inner wall surface of the liquid receiving container. The gap formed between the inner wall surface of the liquid receiving vessel by the spacer as described in claim 3, and characterized by forming a narrow structure toward the vicinity of the detection plane from the periphery the fixing part To do.
[0013]
The optical unit for liquid detection is configured such that the detection surface for detecting the liquid in the housing and the liquid receiving surface face each other with a gap in a state where the fixing portion is fixed to the liquid receiving surface of the liquid receiving container, and the liquid conduction In other words, the periphery of the fixed portion and the detection surface are electrically connected by a gap formed between the fixed portion and the liquid receiving surface. Even if a small amount of the liquid dropped on the opposite side of the liquid receiving surface to the fixed portion of the housing, that is, the side close to the detection surface, reaches the detection surface and is detected in a short time. In addition, the liquid dripped around the fixed portion of the liquid receiving surface that is far from the detection surface reaches the detection surface through a gap between the fixed portion and the liquid receiving surface. As a result, even a small amount of liquid can reach the detection surface and can be detected in a short time.
[0014]
Since at least one of the opposing surfaces of the fixing portion and the liquid receiving surface has wettability with respect to the liquid, the detection surface can easily pass through the gap by capillary action even with a small amount of liquid around the fixing portion. To be detected (claim 2).
The gap between the opposing surfaces of the fixed portion and the liquid receiving surface constituting the liquid conduction structure becomes narrower from the periphery of the fixed portion toward the detection surface, so that the flow velocity of the liquid passing through the gap increases as the detection surface approaches. Therefore, the detection time is shortened even with a small amount of liquid (claim 3).
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a plan view showing a first embodiment of a liquid detection optical unit according to the present invention, FIG. 2 is a side view of the liquid detection optical unit shown in FIG. 1, and FIG. 3 is a liquid detection shown in FIG. FIG. 4 is a bottom view of the liquid detection optical unit shown in FIG.
[0016]
As shown in FIGS. 1 to 4, a liquid detection optical unit (hereinafter simply referred to as “optical unit”) 1 includes a housing 2 and a fixed portion 3 provided on one side of the housing 2. Housed therein are a light projecting optical system 27 and a light receiving optical system 31 similar to those of the conventional liquid detecting optical unit 20 shown in FIGS. The details of the light projecting optical system 27 and the light receiving optical system 31 are not described here. As shown in FIG. 4, detection surfaces 2 a and 2 b are provided at the lower portion of the housing 2 so that the liquid can come into contact with the detection unit composed of the light projecting optical system and the light receiving optical system.
[0017]
The fixing portion 3 is for fixing the housing 2 to the liquid receiving surface of the liquid receiving container, has a plate shape, the lower surface 3 a is flat, and is flush with the lower surface 2 c of the housing 2. A mounting hole 3c is formed in the approximate center of the upper surface 3b of the fixed portion 3, and a reinforcing metal collar 4 is inserted. On the lower surface 3a of the fixed portion 3, a spacer portion 3d is formed concentrically with the hole 3c so as to bulge into a disk shape.
[0018]
The spacer 3d forms a slight gap d (for example, about 0.5 mm) between the liquid receiving surface and the lower surface 2c of the housing 2 when the fixing portion 3 is fixed to the liquid receiving surface of the liquid receiving container. A gap 5 is formed between the flat lower surface 3a of the fixed portion 3 and the liquid receiving surface, and the periphery of the fixed portion 3, that is, the side portions 3f, the front and rear portions 3g, 3h, and the detection surfaces 2a, 2b are electrically connected. (FIG. 5).
[0019]
In addition, a liquid conduction hole 3e is formed at a position corresponding to the detection surface 2b at a base portion of the upper surface 3b of the fixed portion 3 with respect to the housing 2, and the liquid dropped on the upper surface 3b is applied to the detection surfaces 2b and 2a. It comes to lead. The housing 2 and the fixing portion 3 are made of a light-transmitting fluororesin member such as PFA or polypropylene having light-transmitting properties and chemical resistance.
[0020]
As shown in FIG. 5, the optical unit 1 is disposed at a predetermined position on the liquid receiving surface 40a of the stainless steel liquid receiving container 40 described above, and the fixing portion 3 is provided at the position via the collar 4 of the hole 3c. It is attached to the mounting bolt 41 and is fastened and fixed by a nut 42. In the state where the optical unit 1 is fixed to the liquid receiving surface 40a, the lower surface 2c of the housing 2 and the liquid receiving surface 40a are opposed to each other with the gap d by the spacer portion 3d, and the lower surface 3a of the fixing unit 3 And the liquid receiving surface 40a are opposed to each other with a gap d, and a gap 5 is formed as a liquid conduction structure that conducts the periphery of the fixed portion 3 and the detection surfaces 2a and 2b of the housing 2.
[0021]
Hereinafter, the liquid detection of the optical unit 1 will be described.
As shown in FIG. 5, the leaked liquid 1 dropped on the opposite side of the liquid receiving surface 40 a to the fixed portion 3 of the housing 2, that is, the side close to the detecting surface 2 a, flows through the liquid receiving surface 40 a and reaches the detecting surface 2 a, Furthermore, it detects by contacting the detection surface 2b through the clearance gap between the lower surface 2c. Further, the leaked liquid 2 dropped on the upper surface 3b of the fixed portion 3 flows through the upper surface 3b, reaches the detection surface 2b through the liquid conduction hole 3e, and further contacts the detection surface 2a through the lower surface 2c. Detected. Accordingly, these leaked liquids 1 and 2 reach the detection surfaces 2a and 2b even if a small amount can be contacted, and are detected in a short time.
[0022]
The liquid leakage 3 dropped around the fixing portion 3 of the liquid receiving surface 40a far from the detection surface 2b of the housing 2, for example, in the vicinity of the side portion 3f, flows through the liquid receiving surface 40a and the lower surface 3a of the fixing portion 3 and the liquid receiving surface. 40a, flows into both sides of the spacer portion 3d as shown by arrows in FIG. 4, reaches the lower surface 2c between the detection surfaces 2a and 2b of the housing 2, and collides substantially in the middle. It overflows on both sides, reaches the detection surfaces 2a and 2b, and comes into contact. Thereby, the liquid leakage 3 is detected.
[0023]
By the way, as described above, when the housing 2 and the fixing portion 3 are formed of a fluororesin member such as PFA, the liquid receiving container 40 is formed of stainless steel, and the leakage is water, However, the gap formed between the lower surface 2c of the housing 2 and the lower surface 3a of the fixing portion 3 and the liquid receiving surface 40a because stainless steel has wettability to water. In 5, it becomes movable by capillary action.
[0024]
Therefore, as described above, the leakage 3 that has flowed into the gap 5 between the lower surface 3a of the fixed portion 3 and the liquid receiving surface 40a rapidly moves as shown by the arrow in FIG. 2a and 2b are reached and contacted. As a result, even when the amount of the liquid leakage 3 is small, it can reach the detection surfaces 2a and 2b, and can be detected in a short time. Similarly to the liquid leak 3, the liquid leaks 1 and 2 are rapidly moved between the lower surface 2c of the housing 2 and the liquid receiving surface 40a by capillary action to come into contact with the detection surfaces 2a and 2b. Thus, if at least one surface of the liquid receiving surface 40a facing the lower surface 3a of the fixing portion 3 has wettability with respect to the liquid (leakage), the leakage (liquid) around the fixing portion 3 is reduced. Even a small amount can easily move (pass through) the gap 5 by capillary action and reach the detection surfaces 2a and 2b. In addition, it is preferable to set the space | interval d of the clearance gap 5 between the lower surface 3a of the fixing | fixed part 3 and the liquid receiving surface 40a to an optimal space | interval according to the viscosity of the liquid to detect.
[0025]
(Second Embodiment)
6 to 8 show a second embodiment of the optical unit according to the present invention, FIG. 6 is a side view of the liquid detection optical unit, and FIG. 7 is a front view of the liquid detection optical unit shown in FIG. FIG. 8 is a bottom view of the liquid detection optical unit shown in FIG. In addition, the same code | symbol is attached | subjected to the component same as the component of the optical unit for liquid detection in 1st Embodiment shown in FIG. 1 thru | or FIG. 4, and description is abbreviate | omitted.
[0026]
As shown in FIGS. 6 to 8, the lower surface 2c ′ of the housing 2 forms a tapered surface slightly inclined downward from the front and rear end portions toward the lower surface 2c ″ between the detection surfaces 2a and 2b. The lower surface 2c "between 2b is a plane. Further, the gap 7 (liquid conduction structure) formed between the lower surface 3a ′ of the fixed portion 3 and the liquid receiving surface 40a is such that the lower surface 3a ′ of the fixed portion 3 is located on the side far from the housing 2 of the fixed portion 3. The side surface 3f and the front and rear portions 3g, 3h form a tapered surface that is slightly inclined downward toward the lower surface 2c "of the housing 2, and is formed so as to be smoothly connected to the lower surface 2c". The gap 7 has the highest (wide) opening height from the liquid receiving surface 40a in the side portion 3f of the fixed portion 3, for example, about 1.5 mm. That is, the gap 7 is an inclined surface (tapered surface) whose height from the light receiving surface 40a becomes narrower from the periphery of the fixed portion 3 toward the vicinity of the detection surfaces 2a and 2b.
[0027]
As shown in FIG. 9, the leaked liquid 3 dropped on, for example, the vicinity of the side portion 3 f of the fixing portion 3 far from the detection surface 2 b of the housing 2 of the liquid receiving surface 40 a flows through the liquid receiving surface 40 a and flows into the fixing portion 3. It flows into the gap 7 between the lower surface 3a ′ and the liquid receiving surface 40a, flows on both sides of the spacer portion 3d as shown by arrows in FIG. 8, and reaches the lower surface 2c ″ between the detection surfaces 2a and 2b of the housing 2. In the middle of the collision, it overflows on both sides and reaches and comes into contact with the detection surfaces 2a and 2b, whereby the leakage 3 is detected.
[0028]
The gap 7 around the fixed portion 3 has the same pressure as the gap 5 (FIG. 5) when the lower surface 3a ′ is flat, but more because the opening area of the side portion 3f and the front and rear portions 3g and 3h is wide. Liquid is supplied to the gap 7, and the distance d between the lower surface 2c "and the liquid receiving surface 40a is the same in the vicinity of the detection surfaces 2a and 2b as compared with the flat surface, but the liquid supply amount is large, so the movement of the liquid The speed is increased, and the time until detection is further shortened in combination with the capillary phenomenon.
[0029]
【The invention's effect】
As described above, according to the present invention, the liquid can move toward the detection surface of the housing through the gap without being blocked by the fixing portion that fixes the housing to the liquid receiving container. However, the time until detection can be shortened (claim 1). In addition, the liquid can move by capillarity through the gap toward the detection surface without being blocked by the fixed portion, and the time until detection can be further shortened.
[0030]
In addition, the pressure around the fixed part is the same as that in the flat case, but the opening area is large and the fluid flows easily. However, since the liquid supply amount is large, the moving speed of the liquid is increased, and the time until detection can be further shortened.
[Brief description of the drawings]
FIG. 1 is a plan view of a first embodiment of an optical unit for liquid detection according to the present invention.
FIG. 2 is a side view of the optical unit for liquid detection shown in FIG.
FIG. 3 is a front view of the optical unit for liquid detection shown in FIG.
4 is a bottom view of the liquid detection optical unit shown in FIG. 1; FIG.
FIG. 5 is a cross-sectional view taken along the arrow line VV in a state where the liquid detection optical unit shown in FIG. 4 is attached to the liquid receiving container.
FIG. 6 is a side view showing a second embodiment of the optical unit for liquid detection according to the present invention.
7 is a front view of the liquid detection optical unit shown in FIG. 6. FIG.
8 is a bottom view of the liquid detection optical unit shown in FIG. 6. FIG.
9 is a cross-sectional view taken along arrows IX-IX in a state in which the liquid detection optical unit shown in FIG. 8 is attached to a liquid receiving container.
FIG. 10 is a perspective view showing an example of a conventional liquid detection optical unit attached to a liquid receiving container.
11 is a sectional view taken along arrows XI-XI of the liquid detection optical unit shown in FIG.
12 is a cross-sectional view of the liquid detection optical unit shown in FIG. 10 along the arrow XII-XII.
[Explanation of symbols]
1 Optical unit for liquid detection (optical unit)
2 Housing 2a, 2b Detection surface 3 Fixed portion 3a Lower surface (plane)
3a 'bottom surface (inclined surface)
3d Spacers 5 and 7 Gap (Liquid conduction structure)
27 Light projection optical system 31 Light reception optical system 40 Liquid receiving container 40a Liquid receiving surface (liquid receiving container upper surface)
41 Mounting bolt 42 Fixing nut

Claims (3)

A housing having a detection surface made of a translucent material that can be contacted with liquid;
An optical path through the detection surface is formed and supported by the housing, and a projection light amount is provided so that the amount of light transmitted through the optical path changes according to a change in refractive index depending on the presence or absence of liquid contact with the detection surface. A light optical system and a light receiving optical system;
A fixing portion that protrudes from one side of the housing, is fixed to a liquid receiving container that receives the liquid, and supports the detection surface against the inner wall surface of the liquid receiving container ;
A spacer that protrudes on the fixed surface side of the fixing portion with respect to the liquid receiving container and forms a gap between the fixed surface side and the inner wall surface of the liquid receiving container when fixed to the liquid receiving container;
An optical unit for liquid detection, comprising: a liquid conduction hole provided at a base portion of the fixed portion with respect to the housing to guide the liquid to the detection surface . The liquid receiving container has corrosion resistance and wettability with respect to the liquid,
The said fixing | fixed part consists of a material which does not wet to the said liquid, and produces the capillary phenomenon with respect to the said liquid in the clearance gap formed between the inner wall surfaces of the said liquid receiving container. Liquid detection optical unit. Gap formed between the inner wall surface of the liquid receiving vessel by the spacer, the liquid detecting optical unit according to claim 1 which forms a narrow structure toward the vicinity of the detection plane from the periphery the fixing unit.

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