JPS61262640A - Optical detection apparatus - Google Patents

Abstract

PURPOSE:To always maintain accurate detection operation without receiving the effect of dust, by providing shield plates each having a small hole in two receivers and passing only the light passing the central parts of the opening parts provided to the peripheral walls of said receivers among lights from a light emitter to a light receiver. CONSTITUTION:Receivers 30, 40 opened through peripheral wall opening parts 22a, 22b are arranged to both sides of an introducing body 20 introducing a fluid to be detected in opposed relationship. A light emitter 50 emitting light toward the opening part 22a is provided to the receiver 30 and a light receiver 60 receiving light from the light emitter 50 through the opening part 22b is provided to the receiver 40. Shield plates 32, 42 having opening parts 32a, 42a are respectively provided in the receivers 30, 40 and the light from the light emitter 50 is passed only through the central part of the opening part 22a and only light passing through the central part of the opening part 22b in the light from the opening part 22a is received by the light receiver 60. By this method, the light emitter and the light receiver are certainly blocked from dust to be protected from contamination and light receiving quantity is not reduced even if dust is adhered to the inner periphery of the each opening part, and accurate detection operation can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical detection device such as a transmitted light type or a scattered light type.

[Prior art]

Conventionally, this type of optical detection device has a pair of funnel-shaped members in each optical path tube provided on both sides of the flue, as disclosed in Japanese Patent Application Laid-open No. 49-117088, for example. The light emitted from the light emitter housed in one of the light pipes is made to enter the flue through the small-area opening ends of the pair of funnel-shaped members, and the light that has entered in this way is passed through the other light pipe. There is a device in which a light receiver housed inside receives light through each small-area opening end of another pair of funnel-shaped members.

[Problem that the invention seeks to solve]

However, in such a configuration, since the opening areas of each small-area opening end of each pair of funnel-shaped members are the same, the light emitter of the detected fluid such as dust introduced into the flue,
This may sufficiently block the light from reaching the light receiver, leading to contamination of the optical system, and if powder, etc. adheres to the inner circumferential surface of the small-area opening end of each funnel-shaped member on the flue side, it may cause damage to the light receiver. There is a problem in that the amount of light received is unnecessarily reduced.

Therefore, in order to cope with such a problem, the present invention aims to provide an optical detection device that always maintains proper detection operation without being affected by dust or the like.

[Means for solving problems]

In solving this problem, the structural features of the present invention are as follows:
an introduction cylinder for introducing the fluid to be detected; first and second tubes disposed symmetrically on both sides of the introduction cylinder and opening into the introduction cylinder through first and second peripheral wall openings, respectively;
a housing cylinder, a light-emitting body housed in the first housing cylinder and emitting light toward the first peripheral wall opening, and a light-emitting body passing through the second peripheral wall opening into the second housing cylinder and emitting light from the light-emitting body. an optical detection device that is housed in the first housing cylinder and includes a light receptor that is housed to receive light and detects a change in the amount of received light that occurs when the fluid to be detected is introduced into the introduction cylinder; a first shielding plate having a small hole formed to allow light from the light emitting body to pass through only a central portion of the opening of the first peripheral wall; and a second shielding plate having a small hole formed so that the light receiving body receives only the light that passes through the central part of the second peripheral wall frontage among the light from the frontage.

[Effect]

By configuring the present invention in this way, the light from the light emitting body is restricted by the small hole of the first shielding plate so that it passes only through the central portion of the opening of the first peripheral wall and enters the introduction cylinder. Also, among the incident light, only the light passing through the central portion of the second peripheral wall opening is regulated by the small hole of the second shielding plate so that it is received by the light receiving body. Based on the fact that the opening area of each of the peripheral wall openings is larger than the opening area of each small hole of the first and second shielding plates, the light emitting body and the light receiving body are reliably blocked from dust and the like and are protected from dirt. Not only can the original optical function be maintained, but since light only passes through the central portions of the first and second openings in the peripheral wall, dust and the like cannot adhere to the inner peripheral surfaces of the openings in the peripheral wall. However, as a result of this, the amount of light received by the light receiver does not decrease, and proper detection operation can always be ensured.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
In FIGS. 3 to 3, reference numeral S indicates an optical detection device according to the present invention, and this optical detection device S includes a radiator 10 of a vehicle and a bumper 11 of the vehicle located in front of the radiator 10 of the vehicle.
The horizontal plate 1 assembled to the chassis arm 12.12 between
3. It is placed and fixed approximately in the center of the top. The detection device S is of a transmitted light type and is composed of a cylindrical introducing body 20, a pair of cylindrical containers 30, 40, a light emitter 50, and a light receiver 60.

The introduction body 20 is fixed on the horizontal plate 13 along the longitudinal direction of the vehicle with its introduction port 21 facing the bumper 11, and the introduction port 21 of the introduction body 20 is inclined downward. On the other hand, the base 22 of the introduction body 20 is parallel to the horizontal plate 13. The housing body 30 has its central axis aligned with the introduction body 2.
The distal opening 3 is perpendicular to the central axis of the base 22 of 0.
1, the container 40 is coaxially fixed to an opening 22a provided in the peripheral wall of the base 22 by screws 31a to 31a, while the container 40 is positioned symmetrically with respect to the container 30 with respect to the base 22. , is fixed at its tip opening 41 to an opening 22b provided in the peripheral wall of the base 22 by screws 41a to 41a. In such a case, the respective central axes of both numerical volumes 30 and 40 coincide with each other.

The light emitting device 50 is fixed to the bottom of the container 30 by an annular member 50a with its light emitting surface 51 facing the tip opening 31 of the container 30, and the light emitting axis of the light emitter 50 is located at the center of the container 30. coincides with the axis. Thus, the light emitter 50 extends from the light emitting surface 51 to the center hole 3 of the partition plate 32 along its light emitting axis.
Light is emitted through 2a. In such a case, the center of the center hole 32a of the partition plate 32 coincides with the light emitting axis, and the light emitting device 50
emits light from its built-in light emitting diode along its light emitting axis. Further, the partition plate 32 is interposed between the light emitter 50 and the opening 22a of the base 22 in the container 30 so as to be perpendicular to its central axis, and the inner diameter of the center hole 32a of the partition plate 32 is φa (see Figure 4) and bulkhead plate 3
2, the distance L1 between the right side surface and the tip of the light emitting surface 51 of the light emitter 50 is determined as follows.

That is, as shown in FIG. If the distance between the right side surface shown in FIG. 4 and the tip of the light emitting surface 51 of the light emitter 50 is taken as L2, and the allowable deposition thickness δ is taken as shown in FIG. 4, φa and L
l is determined, for example, based on the characteristic line St shown in FIG. 5, so that δ>δO. However, the characteristic curve S1 is
This was experimentally determined as δ-0.5mm+, φbx5m, and L2-22ms. In this case, the diameter of the light beam on the right side of the opening 22a of the base 22 in FIG. 4 has a value corresponding to 10% of the peak light intensity value.

The light receiver 60 is fixed to the bottom of the container 40 by an annular member 60a with its light-receiving surface 61 facing the tip opening 41 of the container 40, and the light-receiving axis of the light receiver 60 is aligned with the center of the container 40. coincides with the axis. Thus, when the light receiver 60 receives light from the light emitter 50 along the light receiving axis on the light receiving surface 61 through each center hole 42a of the partition plate 42, it generates a light receiving signal corresponding to the amount of the received light. In such a case, the light receiver 60 receives light using its built-in phototransistor.

Further, the partition plate 42 is interposed between the light receiver 60 and the opening 22b of the base 22 in the container 40 so as to be perpendicular to the central axis thereof, and the inner diameter of the center hole 42a of the partition plate 42 is φa (corresponds to the inner diameter φa of the center hole 32a of the partition plate 32)
and the opening side end surface of the container 40 of the partition plate 42 and the light receiver 60
The distance L1 from the tip of the light-receiving surface 61 is determined, for example, based on the characteristic straight line S2 shown in FIG. 7, so that δ>δ0.

However, the characteristic line S2 is δ-0.5mm as described above.
.

It was determined experimentally that φb=6m and L2=22m. However, the above dimensions are for the partition wall plate 42 and the opening 22.
b, the light receiver 60 is the partition plate 32, the opening 22a1 is the light emitter 5
Considering that they respectively correspond to 0, they are substantially the same. Further, the center of the center hole 42a of the partition plate 42 coincides with the light receiving axis.

Furthermore, as can be understood by comparing both characteristic curves 31 and 32 with each other, the slope θs1 of the characteristic curve S1 is equal to the slope θs1 of the characteristic curve S1.
is smaller than the slope θs2 of 2. This means that the spread of the luminous flux from the light emitter 50 is smaller than the spread of the light flux received by the light receiver 60.

Therefore, if it is desired to make φa and Ll the same in both corner wall plates 32 and 42, φa and Ll determined by the characteristic curve S3 (see FIG. 5) are adopted.

As a result, the allowable deposition thickness δ can be made thicker, and the shapes of the light-emitting side and the light-receiving side can be made the same, thereby reducing costs.

In addition, in the detection device S configured as described above, when the various dimensions A-E and θa to θC of the introducer 20 are taken as shown in FIG.
C is determined in consideration of the following points.

1. While the particle size of dust is about 0.02 to 30 μl, the particle size of foreign particles such as raindrops other than dust is 0.15 μl.
Since the particle size is approximately 3 fl, the difference in particle size is large, and the mass of the dust is extremely small compared to that of the foreign matter.

Therefore, when the radiator fan of the radiator 10 is activated when the vehicle is running or when the vehicle is stopped, the direction of the airflow flowing parallel to the horizontal plate 13 from the front to the rear of the vehicle is determined by the inlet port of the inlet body 20. If it is bent upward at 21, the traveling direction of each piece of dust is carried by the airflow and it is easy to bend upward, while the foreign object is easy to go straight because of its inertial mass. Moreover, this kind of thing is also influenced by the flow velocity range of the airflow.

2. If the opening height A of the introduction port 21 (i.e., the opening area of the introduction port 21) is appropriate, the upper edge length B of the introduction port 21 is relatively long. It is effective for

In this embodiment configured as described above, when the detection device S is activated, the light emitted from the light emitter 50 is transmitted along the light emitting axis to the center hole 32a of the partition plate 32, and both openings 22a, 22.
b and the center hole 42a of the partition plate 42, the light is received by the light receiver 60 along its light receiving axis, and is generated as a light receiving signal. When the vehicle is running in this condition, if the dust fluid flows from the front to the rear along with the airflow, the dust fluid will flow along with the airflow because the mass of each part of the dust in this dust fluid is small as described above. After flowing into the introduction port 21 of the introduction body 20, it is smoothly bent upward with the airflow without fluid resistance along the inner wall of the introduction port 21, and further bent by the inner wall of the base 22, and then progress smoothly towards the end. Therefore, the amount of light received by the light receiver 60 decreases in accordance with the dust concentration of the dust fluid, and the value of the light reception signal from the light receiver 60 decreases accordingly.

In such a case, even if foreign matter such as particles constituting mud, water, snow, or water spray enters the introduction body 20 along with the dust fluid, the mass of the foreign matter will not exceed that of the dust as described above. Due to its inertial mass, the foreign object separates from the airflow that curves upward as described above and travels straight, colliding with the lower part of the inner wall of the inlet 21 and then colliding with the lower part of the inner wall of the inlet 21. It descends along the section and is reliably prevented from penetrating into the base 22. Therefore, only the dust fluid from which foreign matter has been removed flows smoothly into the base 22 of the introducing body 20 along with the airflow, and as a result, the above-mentioned foreign matter has the same effect on reducing the amount of light received by the light receiver 60. Therefore, the value of the light reception signal of the light receiver 60 can be obtained with high accuracy in accordance with only the dust concentration.

Further, in the above-described operation, the opening 2 of the base 22
Even if dust is deposited on 2a or 22b, the various dimensions φa and Ll are set so that δ>δ0.

Since L2 is determined as described above, the light emitting device 50 is narrowed by the center hole 32a of the partition plate 32 and passes through it.
The luminous flux (see symbol m in FIG. 4) from the aperture 22a
The light beam passes straight through the center of the aperture 22a and enters the base 22 without being blocked by the dust accumulated on the aperture 22b. It passes through the center hole 42a of the partition plate 42 and enters the light receiver 60 without being obstructed by the dust accumulated on the partition plate 22b.
Based on the necessary and sufficient amount of luminous flux from the light emitter 50 determined by the inner diameter φa of the center hole 32a of No. 2, proper detection can always be performed without being affected by the accumulated dust. In such a case, each container 3 consisting of each opening 22a, 22b
Even if the dust flow penetrates into the 0.40, each bulkhead plate 32.42
The inner diameter φa of the center holes 32a and 42a corresponds to each opening 22a.

22b is smaller than the inner diameter φb of the light emitting device 50.
The receiver 60 is protected from dirt.

Incidentally, in this example, when the various dimensions of the introduction body 20 were determined as follows, it was possible to reliably separate the dust fluid from the foreign matter, and as a result, good experimental results were obtained. However, the vehicle speed of the vehicle was set to 0 to 1100 Km/h (corresponding to the airflow velocity of 0 to 60 Km/h at the mounting portion of the detection device S).

θa=40°~50°, θb#45°θcI-15'5°, B#40mmC#40m
m, D=5mm Eζ12mm Also, L1#14fl, φa=2m, L2#22m
.

When φb#5m weight, J I 5-Do 207-
When we conducted an experiment based on the standards of Fl and JI 5-DO207-C1, we found that the light attenuation due to dirt after the experiment was 1.4% for JIS-DO207-Fl compared to the amount of light before the experiment, and JIS-00207 -01 gave a good result of 2.3%.

In the above embodiments, an example in which the device of the present invention is applied to a vehicle has been described, but the present invention is not limited to this, and the device of the present invention may be installed in a general building as a fire detection device.

Further, in the embodiment described above, an example was explained in which one partition wall plate 32.42 was provided in each container 30. 30. A plurality of partition plates 32 (
Alternatively, the inner diameter of the center hole of 42) may be made thicker as it is farther from the light emitter 50 (or light receiver 60).

Further, in the above embodiments, an example in which the present invention is applied to a transmitted light type detection device has been described, but instead of this, the present invention may be applied and implemented to a scattered light type detection device.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view showing an embodiment of the detection device according to the present invention, FIG. 2 is a diagram showing how the detection device in FIG. 1 is attached to a vehicle, and FIG. 4 is a partially enlarged sectional view of the above embodiment; FIG. 5 is a characteristic line diagram showing the relationship between the inner diameter φa and the distance L1 on the light emitting side; and FIG. 6 is a diagram showing the opening at the base of the introduction body. The light intensity distribution diagram in and FIG.
FIG. 3 is a characteristic line diagram showing the relationship. Explanation of symbols S...detection device, 20...introducer, 22a. 22b...opening, 30.40...container, 32.
42... Partition plate, 32a, 42a... Center hole, 50
... emitter, 60... light receiver.

Claims (1)

[Claims] an introduction cylinder for introducing the fluid to be detected; first and second tubes disposed symmetrically on both sides of the introduction cylinder and opening into the introduction cylinder through first and second peripheral wall openings, respectively;
a housing cylinder, a light-emitting body housed in the first housing cylinder and emitting light toward the first peripheral wall opening, and a light-emitting body passing through the second peripheral wall opening into the second housing cylinder and emitting light from the light-emitting body. an optical detection device that is housed in the first housing cylinder and includes a light receptor that is housed to receive light and detects a change in the amount of received light that occurs when the fluid to be detected is introduced into the introduction cylinder; a first shielding plate having a small hole formed to allow light from the light emitting body to pass through only a central portion of the first peripheral wall opening; and a first shielding plate housed in the second housing cylinder and having the first peripheral wall. A second shielding plate having a small hole formed so that the light receiving body receives only the light that passes through the central portion of the second peripheral wall opening out of the light from the opening. Optical detection device.