JP3237006B2 - Liquid detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for optically detecting the presence or absence of a liquid such as water or kerosene. For example, the detector is installed in a device such as an oil storage tank of a petroleum stove or a water heater. The present invention relates to a detector used for detecting the presence or absence of a liquid.

[0002]

2. Description of the Related Art FIG. 10 and FIG.
FIG. 10 shows an example of a conventional optical liquid detector disclosed in Japanese Patent Publication No. 20; FIG. 10 is a perspective view of the liquid detector, and FIG. 11 is a perspective view of the liquid detector crossing a prism portion. . As shown in FIGS. 10 and 11, this detector has a transparent column 1 having a rectangular cross-sectional shape. In the middle of the transparent column 1 in the longitudinal direction, it is aligned with the axis 0, 0 ′ of the transparent column 1. On the other hand, a liquid through-hole having parallel critical surfaces 2 and 3 at 45 ° is penetrated, and a light emitting element 5 is provided at one end of the transparent column 1.
At the other end, a bottomed hole 7 accommodating the light receiving element 6 respectively,
8 are formed integrally in the axial direction of the transparent column 1.

The above-described liquid detector supplies power to the light emitting element 5 to emit light. When the parallel critical surfaces 2 and 3 are in contact with air, the emitted light is reflected by the parallel critical surface 2 and is reflected by the light receiving element 6.
And no photocurrent flows through the light receiving element 6. When the liquid is filled in the liquid through hole 4 having the parallel critical surfaces 2 and 3, the light emitted from the light emitting element 5 enters the light receiving element 6 without being reflected or refracted by the parallel critical surfaces 2 and 3. Then, a photocurrent flows through the light receiving element 6.

Accordingly, by appropriately processing the photocurrent output from the light receiving element 6 in accordance with the presence or absence of light incident on the light receiving element 6, a detection signal as to whether or not the liquid through hole 4 is full of liquid can be obtained. Can be.

[0005]

The above-described liquid detector has the following problems. As shown in FIGS. 10 and 11, this liquid detector has a light emitting element 5 and a light receiving element 6 in holes 7, 8 provided at both ends of a transparent column 1 with their light emitting surface and light receiving surface facing each other. It has a structure inserted. The light-emitting element 5 is a so-called light-emitting lamp in which a light-emitting body is embedded in a shell-shaped or cylindrical package made of a transparent resin material. Similarly to the light emitting element 5, the light receiving element 6 has a structure in which a light receiving body is embedded in a package.

For this reason, the current supply terminal to the light emitting element 5 and the output terminal of the light receiving element 6 are shaped to project in the direction of the axis 0, 0 'of the transparent column 1. As a result, the dimension in the direction of the axis 0, 0 'becomes longer, and the degree of freedom when mounting the liquid container is small.

Further, since the light-emitting element 5 and the light-receiving element 6 are arranged to face each other at a distance from each other, complicated wiring is required when assembling into a device such as a stove or a water heater. The occupation ratio of the volume of the liquid detector to the volume is increased. Further, the light emitting element 5 and the light receiving element 6 are separate packages, and it is difficult to reduce the cost because a step of mounting the light emitting element 5 and the light receiving element 6 in the respective holes 7, 8 is required. Has become.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of a liquid detector. As a first invention, a light emitting element and a light receiving element arranged at a predetermined interval are provided. A reflecting member having a first reflecting surface in a light emitting optical path of the light emitting element and a second reflecting surface in a light receiving optical path of the light receiving element, and forming the first and second reflecting surfaces in a single plate-like body The light emitting element, the light receiving element, and the reflection member are provided in a package formed of a transparent material, and the package has a portion corresponding to the space between the first and second reflection surfaces. A concave portion having a wall surface which is greater than or equal to a critical angle with respect to the light emitted from the light emitting element, and when the object to be detected is in the concave portion, the light emitted from the light emitting element is first and second reflection surface portions. When the object is not detected, the light is emitted There is reflected by the wall surface of the recess, the light receiving element is proposed a liquid detectors, characterized by being configured so as not to light-receiving operation. The liquid detector configured as described above is small and suitable for mass production.

According to a second aspect of the present invention, both sides of a reflecting member formed of a plate-like body are bent to form first and second reflecting surfaces, and a light-transmitting portion is formed in a middle plane portion. A liquid detector characterized by this is proposed. The liquid detector configured as described above can reduce stray light and can obtain a high-quality detection signal.

According to a third aspect of the present invention, the cross-sectional shape of the first reflecting surface of the reflecting member is a parabola whose focal point is the light emitting element, and the cross-sectional shape of the second reflecting surface is a parabola whose focal point is the light receiving element. A liquid detector characterized by the following is proposed. The liquid detector configured as described above can increase the use efficiency of the light emitted from the light emitting element, and can obtain a high quality detection signal.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the configuration of the liquid detector, and FIG. 2 is a sectional view taken along line AA in FIG. Figure 1,
As shown in FIG. 2, the lead terminals 11, 12, and 13 are arranged in parallel in the longitudinal direction thereof and in a horizontal line.

A light emitting element 14 is fixed to one end of the lead terminal 11 with a conductive adhesive so as to connect one electrode, and one end of the lead terminal 13 is On the other hand, the light receiving element 15 is fixed with a conductive adhesive so as to connect the electrodes. The other electrode of the light emitting element 14 and the other electrode of the light receiving element 15 are wired to one end of the lead terminal 12 by conductive lines 16 and 17, respectively.

Further, a reflecting member 18 made of a plate-like body having a first reflecting surface portion 19 provided on a light emitting optical path of the light emitting element 14 and a second reflecting surface portion 20 provided on a light receiving optical path of the light receiving element 15 is provided.
Is provided. The reflecting member 18 is plate-shaped, and both sides are bent at a right angle.
The first reflection surface portion 19 and the second reflection surface portion 20 are formed by being bent inward at an angle of 5 °. In this reflection member 18, only the surface portions of the first reflection surface portion 19 and the second reflection surface portion 20 may be mirror surfaces.
The entire surface of the reflecting member 18 on the side of the reflecting surfaces 19 and 20 may be a mirror surface.

These light emitting element 14, light receiving element 15, and lead
The lead terminals 11, 12, 13, the conductive wires 16, 17, and the reflection member 18 leave a part of the lead terminals 11, 12, 13 and are formed of a package made of a transparent material such as epoxy resin.
It is buried in the di 25. In this package 25, a V-shaped recess 21 formed by slopes 22, 23 is formed at a portion between the first reflection surface portion 19 and the second reflection surface portion 20 of the reflection member 18. Is provided.

FIG. 3 shows the light emitting element 14, the light receiving element 15,
It shows the arrangement of the lead terminals 11, 12, and 13.
The light emitting element 14 and the light receiving element 15 are arranged such that the light emitting direction and the light receiving direction are perpendicular to a plane 31 including the lead terminals 11 and 13 arranged in a plane parallel to the longitudinal direction. It is fixed to the lead terminals 11 and 13. The longitudinal direction of the lead terminals 11, 12, 13 is substantially perpendicular to the line 32 connecting the light emitting element 14 and the light receiving element 15.

The liquid detector constructed as described above has a leak detector.
And the light emitting element 14 emits light.
The emitted light is reflected by the reflecting member 18 as shown by a ray 24 in FIG.
Is reflected by the first reflection surface portion 19. in this case,
When the package 25 is in the air, it is reflected by the first slope 22 of the concave portion 21 of the package 25 like a light ray 26 and does not enter the light receiving element 15. Also, package 2
5 is in a liquid having a refractive index substantially equal to the refractive index of the package 25,
The light passes through the liquid without being reflected by the first slope 22, and further passes through the second slope 23 of the concave portion 21. Therefore,
The light is reflected by the second reflection surface portion 20 of the reflection member 18 and enters the light receiving element 15.

As described above, in the present liquid detector, when the liquid detector is in the liquid, the light emitted from the light emitting element 14 is incident on the light receiving element 15 and a photocurrent flows. Therefore, based on the presence or absence of light incident on the light receiving element 15, the light receiving element
By appropriately processing the photocurrent output from the liquid detector, it is possible to obtain a detection signal indicating whether or not the present liquid detector is in the liquid.

As described above, the present liquid detector applies the light emitted from the light emitting element 14 to the first and second reflecting surfaces 1 of the reflecting member 18.
By reflecting light at 9 and 20, the distance between the light emitting element 14 and the light receiving element 15 can be reduced, and the external dimensions can be made smaller than in the conventional example. Also, the light emitting element 14 and the light receiving element 15 are mounted so that the light emitting direction of the light emitting element 14 and the light receiving direction of the light receiving element 15 are perpendicular to the lead terminals 11 and 13 arranged in a plane. Thus, the light emitting element 14 and the light receiving element 15 can be mounted on the lead terminals 11 and 13 from the same direction, and the mounting process can be simplified, and the cost during mass production can be reduced.

It should be noted that the present liquid detector detects the liquid so that an optical path is formed between the first slope 22 and the second slope 23 when the concave portion 21 of the package 25 is filled with the liquid. Photocurrent is output only when present. Therefore, when the liquid adheres to the slope 22 of the concave portion 21 in the form of water droplets, the photocurrent of the light receiving element 15 is not output, and the liquid detector has less malfunction.

Further, when the liquid detector itself fails, the following operation is performed. If the light emitting element 14 fails due to disconnection or the like, the light emitting element 14 does not emit light, so that no photocurrent is output from the light receiving element 15 regardless of whether the liquid detector is in air or liquid. Also, the light receiving element 1
In the failure of No. 5, no photocurrent is output from the light receiving element 15 irrespective of whether the liquid detector is in the air or in the liquid as described above.

Therefore, no photocurrent is output in any of the above cases. This is the same signal as when the liquid detector is in air during normal operation. That is, the device controlled by the detection signal of the liquid detector performs an operation of “no liquid” when the liquid detector fails. For example, in a device that uses the present liquid detector to detect water in a boiler provided in a water heater and controls the burner of the water heater to be in a combustion state only when water is present in the boiler, When there is no water in the boiler, or when the liquid detector is out of order, the burner is controlled to be turned off, and the device is highly safe.

FIG. 4 is a perspective view showing a modification of the reflection member 18. As shown in FIG. The reflection member 41 has a window 43 at the center of the middle plane portion 42.

FIG. 5 is a simplified diagram of a liquid detector using the reflection member 41. The light emitted from the light emitting element 14 is diffused light, and a part of the light reflected by the first reflection surface portion 44 of the reflection member 41 goes to the center of the plane portion 42 of the reflection member 41 like a light ray 46. This light passes through the window hole 4 in the plane portion 42.
If 3 is not provided, the light is reflected by the second reflection surface portion 45 of the reflection member 41 and enters the light receiving element 15 as a light ray 47 indicated by a two-dot chain line. The light indicated by the light ray 47 always enters the light receiving element 15 irrespective of whether the liquid detector is in the liquid or in the air, and the so-called S, which is the ratio between noise and signal components, is used.
This will make the N ratio worse. The reflection member 41 may form a cut groove instead of the window hole 43.

For this reason, the above-mentioned window hole 43 is provided in the reflection member 41 so as not to generate the reflected light indicated by the light ray 47. Therefore, the light indicated by the light beam 46
Is emitted to the outside through By providing the window hole 43 in the reflection member 41 as described above, the light indicated by the light ray 47 is eliminated and the SN ratio is improved.

FIG. 6 is a sectional view similar to FIG. 2 of a liquid detector showing another modification of the reflecting member 18. As shown in FIG. This reflecting member 50
In the figure, the cross-sectional shape of the first reflection surface portion 51 is a parabola having the light emitting element 14 as a focal point. Similarly, the cross-sectional shape of the second reflection surface portion 52 is a parabola whose focal point is the light receiving element 15.

When such a reflecting member 50 is provided, the light emitted from the light emitting element 14 is reflected by the first reflecting surface 51 and becomes a parallel light beam. When the package 25 is in the air, the parallel light is reflected by the slope 22 of the concave portion 21 and does not enter the light receiving element 15. When the package 25 is in the liquid, the parallel light becomes the slope 2 of the recess 21.
The light is not reflected at 2 and 23, but is reflected and condensed by the second reflection surface portion 52 as it is as a parallel light, and is incident on the light receiving element 15.

The light reflected by the first reflecting surface portion 51 of the reflecting member 50 and converted into parallel rays is reflected by the slope 22 of the concave portion 21 when the package 25 is in the air. The angles of incidence of the parallel rays on the slope 22 are all the same. Therefore, the angle of incidence of light on the interface between the media having two different refractive indices, that is, the slope 22,
The total reflection occurring at a critical angle or more occurs on the slope 22 in the entire area of the parallel rays. For this reason, when the reflecting member 50 is used, the light beam φ of the light emitted from the light emitting element 14 that is converted into a parallel light beam can be used for liquid detection, so that a liquid detector having a good SN ratio can be obtained.

FIGS. 7 and 8 show a modification of the V-shaped recess 21 formed in the package 25 shown in FIGS. FIG. 7 is a front view of a liquid detector provided with this package, and FIG. 8 is a cross-sectional view taken along line BB in FIG.
These drawings are modified versions of the package 25 of the liquid detector shown in FIGS. 1 and 2, and the other components are not changed. Omitted.

As shown in FIGS. 7 and 8, the package 61 has a concave portion having a first reflecting surface portion 63 inclined so as to have a wall surface having a critical angle or more with respect to the light emitted from the light emitting element 14. 62 are formed. In these figures, ray 6
The light emitted from the light emitting element 14 indicated by 4 is reflected by the first reflecting surface 19 of the reflecting member 18, and when the package 61 is in the air, it is reflected by the first wall 63 of the concave portion 62, Thus, the light is radiated to the outside of the package 61. When the package 61 is in the liquid, the light passes through the first wall surface 63 of the concave portion 62, passes through the second wall surface 66, is reflected by the second reflection surface portion 20 of the reflection member 18, and receives light. The light enters the element 15.

When the package 61 is in the air, the liquid detector using the package 61 has a light emitting element 14.
Is reflected by the first wall surface 63 of the concave portion 62 and immediately radiated to the outside of the package 61, so that it becomes a liquid detector which outputs a detection signal having a good SN ratio without generating stray light.

The reflecting member 18 shown in FIG. 2 is not limited to the shape shown in FIG. 9 but has two bent portions for forming the first reflecting surface portion 19 and the second reflecting surface portion 20 (FIG. 9A). 9) may be used, or the shape shown in FIG. 9B in which the bent part is an arc may be used.

Although the embodiment of the present invention has been described above, in practicing the present invention, when an infrared light-emitting element, an ultraviolet light-emitting element, or the like is used as the light-emitting element 14, the light-emitting wavelength may be reduced. Packages 25 and 6 made of transparent material
Form one. Further, in the above description, the air is not limited to the actual air, but may be a gas such as nitrogen, or may be a medium having a refractive index smaller than the refractive index of the liquid to be detected.

[Brief description of the drawings]

FIG. 1 is a simplified front view of a liquid detector of the present invention.

FIG. 2 is a sectional view of the liquid detector taken along line AA in FIG. 1;

FIG. 3 is a layout diagram of a lead terminal, a light emitting element, and a light receiving element of the liquid detector.

FIG. 4 is a perspective view showing a modification of the reflection member provided in the liquid detector.

FIG. 5 is a simplified diagram of a liquid detector including the reflecting member shown in FIG.

FIG. 6 is a cross-sectional view of a liquid detector similar to FIG. 2 showing another modified example of the reflection member.

FIG. 7 is a front view of a liquid detector in which a package is modified.

8 is a cross-sectional view of the liquid detector taken along line BB in FIG. 7;

FIGS. 9A and 9B are views showing a reflecting member in which the shape of a bent portion is changed.

FIG. 10 is a perspective view showing a configuration of a liquid detector shown as a conventional example.

FIG. 11 is a perspective view traversing the liquid detector of the conventional example.

[Explanation of symbols]

 11, 12, 13 Lead terminal 14 Light emitting element 15 Light receiving element 16, 17 Conductive wire 18, 42, 50 Reflecting member 19, 44, 51 First reflecting surface section 20, 45, 52 of reflecting member Second of reflecting member 22 First slope 23 Second slope 24, 26, 46, 47, 64, 65 Light rays 25, 61 Package 43 Window 63 First wall 66 Second wall

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-219853 (JP, A) JP-A-6-102080 (JP, A) JP-A-6-58793 (JP, A) JP-A-7- 225146 (JP, A) JP-A-6-300610 (JP, A) JP-A-3-28426 (JP, U) JP-B-5-14209 (JP, B2) Patent 2666332 (JP, B2) Patent 2722048 (JP , B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01F 23/28

Claims (3)

(57) [Claims] 1. A light-emitting element and a light-receiving element disposed at a predetermined interval, a first reflection surface portion in a light-emitting optical path of the light-emitting element, and a second reflection surface portion in a light-receiving optical path of the light-receiving element. ,
A light-emitting element, a light-receiving element and a light-reflective member are provided in a package formed of a transparent material. When a concave portion having a wall surface having a critical angle or more with respect to the emission light of the light emitting element is formed in a portion corresponding to the portion between the first and second reflection surface portions, and the object to be detected is in the concave portion. The light emitted from the light emitting element is reflected by the first and second reflection surface portions and is incident on the light receiving element. When the object to be detected is not present, the emitted light is reflected by the wall surface of the concave portion, and the light receiving element is A liquid detector characterized in that it does not perform a light receiving operation. 2. A reflection member formed of a plate-like body is bent at both sides to form first and second reflection surfaces at both sides.
2. The liquid detector according to claim 1, wherein a light transmitting portion is formed in a middle plane portion. 3. A sectional shape of a first reflecting surface portion of the reflecting member is a parabola whose focus is on the light emitting element, and a cross sectional shape of a second reflecting surface portion is a parabola whose focus is on the light receiving element. The liquid detector according to claim 1, wherein