JP2007278858A - Fog particle sensor and fog sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fog particle sensor and a fog sensor that can perform detection, even if fog particle concentration is low, and perform detection at an early stage of fog rising. <P>SOLUTION: A shade housing 1 is provided therein with a light-emitting part 10 having a semiconductor laser 6 generating linear polarized light in a direction rectangular to a paper surface and having a lens 7 for turning incident light into parallel light; first and second light-receiving parts 20 and 30 disposed in a direction at 60 degrees from an incident light axis; an air suction part 4 for taking in sample air; and a suction fan 5 for supplying sample air to a detection area 2. The receiving part 20 comprises a lens 8 for light condensing, and a photodiode 9 for measuring the intensity I of scattered light. The receiving part 30 comprises a lens 13 for light condensing, a polarizing filter 11 for transmitting only the polarized light that is orthogonal to the incident light, and a photodiode 12 for measuring the intensity IS of scattered light transmitted by the polarizing filter 11. Based on the intensity I and the degree of polarization found from the IS, it is decided whether suspended particles are fog particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mist particle sensor and a mist sensor, and more particularly to a mist particle sensor that detects mist particles in the atmosphere and a mist sensor using the mist particle sensor.

  Conventionally, as means for detecting fog, for example, there is an infrared laser blocking type measuring instrument. In this measuring instrument, a light emitting unit and a light receiving unit are arranged to face each other, an infrared laser is irradiated from the light emitting unit to the light receiving unit, and the number of pulses blocked by fog is counted. And fog is detected by the count number (patent document 1). In addition, there is a device that includes a light emitting unit that emits infrared rays and a light receiving unit that receives infrared reflected light irregularly reflected by fog, counts the number of pulses of the received reflected light, and detects the fog based on the counted number (Patent Document 2).

However, the above-mentioned conventional apparatus has a drawback that it cannot be detected unless the concentration of fog particles is considerably high, and the apparatus is large and very expensive. There is a problem that a great deal of cost is required.
JP-A-7-325162 (Claim 1) JP 2003-121357 A (Claim 1)

  The present invention has been made in order to solve the above-described problems of the prior art, and the object of the present invention is to detect even when the concentration of fog particles is low, and at an early stage when fog occurs. It is providing the fog particle sensor and fog sensor which enable detection of fog generation from. Another object of the present invention is to provide a fog sensor and fog sensor that are small and inexpensive and can be installed at many points.

The fog particle sensor of the present invention is a fog particle sensor that determines whether or not each suspended particle contained in the atmosphere is a fog particle, and includes a light shielding housing having a detection area, and the light shielding housing. A sample air supply means for supplying sample air to the detection area, a light emitting unit for irradiating the detection area with linearly polarized light as incident light, and an intensity I of scattered light of linearly polarized light by suspended particles in the sample air a first light receiving portion, and a second light receiving unit for measuring the intensity I _S of the polarization direction of the scattered light perpendicular to the polarization direction of the incident light out of the scattered light, the first and second light receiving portions Based on the degree of polarization obtained from the intensity of the detected scattered light, it is determined whether or not the suspended particles are fog particles.

  In addition to the degree of polarization, it is possible to determine whether or not the suspended particles are fog particles based on the intensity I of the scattered light detected by the first light receiving unit in the previous period. is there.

Here, the degree of polarization is
(I−I _S ) / (I + I _S ),
(I-I _S ) / I and I _S / I
It can obtain | require by either of these.

When determining the degree of polarization from (I−I _S ) / (I + I _S ), it is preferable to determine that floating particles having a degree of polarization of 0.6 or more are fog particles.

  The mist sensor of the present invention is a mist sensor including any of the mist particle sensors described above, and whether or not suspended particles in the sample air continuously supplied to the sample air are mist particles. Are judged sequentially, and it is judged that fog is generated when the ratio of fog particles to all floating particles is 80% or more.

  Since the mist particle sensor and mist sensor of the present invention determine whether or not each suspended particle is a mist particle, it is possible to determine even if the mist particle concentration is low. Detection from an early stage is possible. Moreover, it is small and inexpensive and can be installed at many points.

  FIG. 1 shows the inside of a fog sensor according to an embodiment of the present invention. The fog sensor of this embodiment also functions as a fog particle sensor. As shown in the figure, the fog sensor of the present embodiment has a light shielding housing 1, and within the light shielding housing 1, a light emitting unit 10 that irradiates the detection area 2 with incident light and 60 degrees with respect to the incident optical axis. The first light receiving unit 20 disposed in the direction of the second light receiving unit 30, the second light receiving unit 30 also disposed in the direction of 60 degrees with respect to the incident optical axis, the air suction port 4 for taking sample air, and the sample A suction fan 5 for supplying air to the detection area 2 is provided.

  The light emitting unit 10 includes a semiconductor laser 6 that emits linearly polarized light in a direction perpendicular to the paper surface of FIG. 1 and a lens 7 that converts incident light from the semiconductor laser 6 into parallel light.

  The first light receiving unit 20 includes a lens 8 for collecting scattered light from suspended particles in the detection area 2 and a photodiode 9 for measuring the intensity I of the scattered light.

Further, the second light receiving unit 30 collects the scattered light from the suspended particles in the detection area 2 and a polarizing filter that transmits only the scattered light in the polarization direction orthogonal to the incident light out of the scattered light. 11 and a photodiode 12 for measuring the intensity I _{S of} scattered light transmitted through the polarizing filter 11.

  Sample air is supplied to the detection area 2 from the air suction port 4 at the lower part of the light shielding housing by the suction of the suction fan 5, and therefore the sample air always flows from the bottom to the top of the light shielding housing. The supply amount of the sample air is adjusted so that a plurality of suspended particles contained in the sample air are not sent to the detection area 2 at the same time.

  FIG. 2 shows the principle of the fog particle sensor of this embodiment. In the fog sensor of the present embodiment, incident light emitted from the semiconductor laser 6 of the light emitting unit 10 is polarized in the direction indicated by the arrow 18 and reaches the lens 7 along the optical axis 19. Incident light becomes parallel light by the lens 7 and enters the detection area 2 (FIG. 1). Sample air flows in the detection area 2, and the suspended air 21 is contained in the sample air. When the suspended particles 21 pass through the detection area 2, incident light is scattered. Unlike the incident light, the scattered light includes polarized light in all directions. Of this scattered light, the light directed toward the optical axis 29 is collected by the lens 8 and reaches the photodiode 9. A current proportional to the scattered light is output from the photodiode 9.

  On the other hand, of the scattered light scattered by the suspended particles 21, the light directed toward the optical axis 39 is collected by the lens 13 and reaches the polarizing filter 11. The polarizing filter 11 transmits only the light that is polarized in the direction indicated by the arrow 28 out of the scattered light, that is, the scattered light having a polarization component perpendicular to the polarization direction of the incident light. This transmitted light reaches the photodiode 12, and a current proportional to the polarization component perpendicular to the incident polarization direction of the scattered light is output from the photodiode 12.

FIG. 3 is a block diagram illustrating an example of a circuit that processes current from the photodiode 9 and the photodiode 12. The current output from the photodiode 9 and the current output from the photodiode 12 are respectively input to the current-voltage conversion circuits 18 and 14 and converted into voltages. Further, each converted voltage is input to the amplifier circuits 15 and 16, and a voltage representing the intensity I of the scattered light is output from the amplifier circuit 15, and this voltage is simultaneously input to the arithmetic circuit 17. Further, the amplifier circuit 16 outputs a voltage representing the intensity I _S of the polarization component orthogonal to the incident light in the scattered light, and this voltage is also input to the arithmetic circuit 17. Then, the arithmetic circuit 17 calculates the degree of polarization based on the output from the amplifier circuit 15 and the output from the amplifier circuit 16 according to the equation: polarization degree = (I−I _S ) / (I + I _S ). Then, based on this degree of polarization, or based on the degree of polarization and scattered light intensity I, it functions as a fog particle sensor by determining whether or not the suspended particles are fog particles, as will be described later. Moreover, if the sensor of this embodiment judges whether it is a fog particle about many floating particles, it will function as a fog sensor.

  FIG. 4 is a diagram illustrating the relationship between the scattered light intensity and the degree of polarization when measured on a clear day using the fog sensor of the embodiment according to FIGS. 1 to 3. The horizontal axis represents the intensity I of scattered light that reflects the size of the particles detected by the first light receiving unit, and the vertical axis represents the degree of polarization that reflects the surface state of the particles. The fine particles of fine particles are distributed in the region of 1 ≦ I ≦ 3 and in the region of −0.4 ≦ polarization degree ≦ 0.4, indicating that most of the suspended particles are dust. Yes.

  FIG. 5 is a diagram showing the relationship between the scattered light intensity and the degree of polarization measured when the fog is generated using the same fog sensor as in FIG. 4, and the horizontal axis and the vertical axis are the same as those in FIG. A large amount of suspended particles at the time of fog generation are distributed in the region of 1 ≦ I ≦ 3 and 0.6 ≦ polarization degree ≦ 1. Further, it can be seen that since the humidity at the time of generation of fog is very high, dust particles as shown in FIG. 4 are hardly detected. If the fog sensor of the embodiment is used, it is possible to determine that suspended particles having a polarization degree of 0.6 or more are fog particles, as is apparent from FIGS. 4 and 5. Moreover, it can be judged from the comparison of FIG.4 and FIG.5 that the fog has generate | occur | produced when the ratio of the fog particle with respect to all the floating particles is 80% or more.

  In the above embodiment, the first light receiving unit 20 and the second light receiving unit 30 are both set at a direction of 60 degrees from the incident optical axis, but the optical axes of the two light receiving units are always the same from the incident optical axis. It is not necessary to install at an angle, and the installation direction may be any direction, but it is preferably between 0 and 90 degrees.

  The direction of the linearly polarized light of the incident light from the light emitting unit is not necessarily perpendicular to the paper surface. For example, when the linearly polarized light parallel to the paper surface is used as the incident light, the second light receiving unit The thirty polarizing filters 11 need to be set so as to transmit only a polarization component perpendicular to the incident polarization direction, that is, in a direction perpendicular to the paper surface.

  Moreover, in the said embodiment, although the semiconductor laser was used for the light source of the light emission part 10, it does not necessarily need to be a semiconductor laser and LED and a tungsten lamp can also be used. The semiconductor laser emits linearly polarized light, but the light from the LED or tungsten lamp is randomly polarized. Therefore, when using them, it is necessary to transmit only the linearly polarized light through the polarizing filter.

  If the mist particle sensor and the mist sensor according to the present invention are used, the mist particles can be detected with high accuracy from an early stage when the mist is generated, so that the mist particle sensor and the mist sensor can be used, for example, in the field of weather observation equipment.

It is a layout view of a fog particle sensor according to an embodiment of the present invention. It is a figure which shows the principle of the fog sensor of FIG. It is a block circuit diagram which shows an example of the processing method used for the fog sensor of FIG. It is a figure which shows the relationship between the scattered light intensity | strength at the time of measuring on a clear day using the fog sensor of FIG. It is a figure which shows the relationship between the scattered light intensity | strength at the time of measuring on the day of fog using the fog sensor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-shielding housing 2 Detection area 4 Air suction port 5 Suction fan 6 Semiconductor laser 7, 8, 13 Lens 9, 12 Photodiode 10 Light emission part 11 Polarization filter 13 Lens 18, 14 Current voltage conversion circuit 15, 16 Amplification circuit 17 Calculation circuit 19, 29, 39 Optical axis 20 First light receiving part 21 Floating particle 30 Second light receiving part

Claims (7)

A fog particle sensor that determines whether or not each suspended particle contained in the atmosphere is a fog particle,
A light shielding housing having a detection area;
Sample air supply means for supplying sample air to the detection area of the light shielding housing;
A light emitting unit that irradiates the detection area with linearly polarized light as incident light; and
A first light-receiving unit that measures the intensity I of linearly polarized scattered light from suspended particles in the sample air;
A second light receiving unit that measures the intensity I _S of the scattered light in the polarization direction orthogonal to the polarization direction of the incident light among the scattered light,
A fog particle sensor that determines whether or not suspended particles are fog particles based on the degree of polarization obtained from the intensity of scattered light detected by the first and second light receiving units.   2. The fog particle sensor according to claim 1, wherein a determination is made as to whether or not the suspended particles are fog particles based on the intensity I of scattered light detected by the first light receiving unit in addition to the degree of polarization. The fog particle sensor according to claim 1, wherein the degree of polarization is obtained by (I−I _S ) / (I + I _S ). The degree of polarization, (I-I _S) / fog particle sensor according to claim 1 or 2, wherein is obtained by I. The fog particle sensor according to claim 1, wherein the degree of polarization is obtained by I _S / I.   The fog particle sensor according to claim 3, wherein the suspended particles having a polarization degree of 0.6 or more are determined to be fog particles. It is a mist sensor provided with the mist particle sensor in any one of Claims 1 thru | or 6, Comprising: The judgment whether it is a mist particle about the floating particle | grains in the sample air continuously supplied to the said sample air. A mist sensor that sequentially performs and determines that mist is generated when the ratio of mist particles to all suspended particles is 80% or more.

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