KR20200104745A - Apparatus for sensing particle - Google Patents

Abstract

A particle sensing apparatus according to an embodiment of the present invention comprises: a light emitting part which emits sensing light in a light traveling direction; and a first light receiving part and a second light receiving part respectively outputting a first particle sensing signal and a second particle sensing signal as the sensing light reflected on the particle is incident. The first light receiving part is disposed to be inclined by a first angle with respect to the light traveling direction, and the second light receiving part is disposed to be inclined by a second angle with respect to the light traveling direction. The present invention can provide a simple structure and a relatively low price.

Description

Particle sensing device{APPARATUS FOR SENSING PARTICLE}

The present invention relates to a particle sensing device.

A general optical particle sensing device senses light reflected by particles such as dust or suspended matter, and usually uses one light source and one light receiving element.

The optical particle sensing device of this type can measure particles in real time, but it is difficult to consider the particle size and it may be difficult to separate the particles according to the particle size.

As shown in FIG. 1, in the case of a general particle sensing device, one light-receiving element 10 is disposed perpendicular to the light propagation direction of light emitted from the light source 20, and such an arrangement decreases particle sensing efficiency. I can knock it down.

Since the general particle sensing device of FIG. 1 is difficult to sense particles according to the size, the general particle sensing device as shown in FIG. 2 includes a plurality of particle filters 30 to separate incoming particles by size, and separate the separated particles. You can sense it.

The general particle sensing device of FIG. 2 needs to be provided with a plurality of particle filters 30 and a plurality of particle sensing modules for each size, so the price may be excessively high.

US registered patent 6,794,671 (Registration date: September 21, 2004)

The particle sensing device according to an embodiment of the present invention is for measuring particles by size.

A particle sensing device and a particle sensing method according to an embodiment of the present invention are intended to provide a simple structure and a relatively low cost.

The subject of the present application is not limited to the subject mentioned above, and another subject not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a light emitting unit that emits sensing light in a light traveling direction; And a first light receiving unit and a second light receiving unit respectively outputting a first particle sensing signal and a second particle sensing signal as the sensing light reflected on the particle is incident, wherein the first light receiving unit is It is disposed to be inclined by an angle, and the second light receiving unit is disposed to be inclined by a second angle different from the first angle with respect to the light traveling direction.

The first angle may be less than 90 degrees, and the second angle may be greater than the first angle and less than 90 degrees.

The first light receiving part may be disposed on one side with respect to the light traveling direction, and the second light receiving part may be disposed on the other side opposite to the one side with respect to the light traveling direction.

The first light receiving part and the second light receiving part may be disposed at one side with respect to the light traveling direction.

The first light receiving part and the second light receiving part may be provided in one module body.

The first angle may be 25 degrees or more and 35 degrees or less, and the second angle may be 45 degrees or more and 55 degrees or less.

The size of the measurable particles may be 0.2 µm or more and 100 µm or less.

The wavelength of the sensing light may be 630 nm or more and 970 nm or less.

The particle sensing apparatus according to an exemplary embodiment of the present invention may further include an operation unit for deriving information on the size of the particles through the first particle sensing signal and the second particle sensing signal.

The particle sensing device according to an embodiment of the present invention further includes a body in which the light emitting unit, the first light receiving unit, and the second light receiving unit are installed, wherein the body has an inlet hole and an outlet hole, and the particle is included. The fluid may flow into the body through the inlet hole, the fluid flows out of the body through the outlet hole, and a fan configured to form a flow of the fluid may be further included.

The particle sensing device according to an embodiment of the present invention may measure particles by size through the first and second light receiving units disposed at different angles.

The particle sensing device according to an embodiment of the present invention can provide a simple structure and a relatively low cost because it can measure particles by size through the first and second light receiving units.

The effects of the present application are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 and 2 show a general particle sensing device.
3A, 3B, and 5 show a particle sensing device according to an embodiment of the present invention.
4 shows a conceptual diagram of Mie scattering.
6 is a graph showing the relationship between the wavelength and particle size of sensing light in which unscattered occurs.
7 shows a particle sensing device according to another embodiment of the present invention.
8 shows an example of a pattern of a first particle sensing signal and a second particle sensing signal of a first light receiving unit and a second light receiving unit.
9 is for explaining the graph of FIG. 8.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the accompanying drawings are only described in order to more easily disclose the contents of the present invention, and the scope of the present invention is not limited to the scope of the accompanying drawings. You will know.

In addition, terms used in the present application are used only to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance.

3A and 3B show a particle sensing device according to an embodiment of the present invention. As shown in FIGS. 3A and 3B, the particle sensing device according to the exemplary embodiment of the present invention includes a light emitting unit 110, a first light receiving unit 130, and a second light receiving unit 150.

The light-emitting unit 110 emits sensing light in a light traveling direction. In the embodiment of the present invention, the light emitting unit 110 may include a laser generator or an LED, but is not limited thereto.

Lasers and LEDs may have various advantages and disadvantages, and accordingly, according to design conditions, manufacturing conditions, and sales conditions of the particle sensing device according to an embodiment of the present invention, the light emitting unit 110 uses at least one of the laser and LED. Can include.

Since the laser has the same phase wavelength, the condensing efficiency of the laser using an optical element such as a lens may be better than that of an LED.

In addition, the output efficiency of LED is 10%, and the efficiency of output energy versus input energy may be lower than that of laser. In the case of laser, the output efficiency is over 50%, so high output can be obtained from low current input.

The wavelength bandwidth of the LED can be from 20 to 100 nm, and the wavelength bandwidth of the laser can be relatively narrow compared to the LED. Accordingly, when the light emitting unit 110 includes a laser, the optical system efficiency of the particle sensing device may be high.

The price of LED is cheaper and longer life than laser, so the production cost of particle sensing device can be lowered and operation life can be improved.

Meanwhile, the first light receiving unit 130 and the second light receiving unit 150 output a first particle sensing signal and a second particle sensing signal, respectively, as sensing light reflected on the particle is incident. In the exemplary embodiment of the present invention, the particles move along a fluid, and may be, for example, fine dust or ultrafine dust moving according to the flow of air, but the present invention is not limited thereto.

The first light receiving unit 130 and the second light receiving unit 150 may include, but are not limited to, a photo diode or a photo transistor that converts an optical signal into an electrical signal.

The first light receiving unit 130 is disposed to be inclined by a first angle a1 with respect to the light traveling direction, and the second light receiving unit 150 is disposed to be inclined by a second angle a2 with respect to the light traveling direction.

In this case, the first angle a1 and the second angle a2 are different from each other. For example, as shown in 3a, the first angle a1 may be less than 90 degrees, and the second angle a2 may be greater than the first angle a1 and less than 90 degrees. Alternatively, although not shown in FIGS. 3A and 3B, the first angle a1 may be an acute angle and the second angle a2 may be an obtuse angle. In addition, the first light receiving unit 130 and the second light receiving unit 150 may be disposed at different angles.

In FIG. 3A, the particle sensing device according to the embodiment of the present invention includes two light receiving units, but is not limited thereto, and three or more light receiving units disposed at different angles as shown in FIG. 3B may be provided as needed.

The particle sensing device according to an exemplary embodiment of the present invention may sense particles by size using a Mie scattering phenomenon. As shown in (A) of FIG. 4, when the particle is very small compared to the wavelength of the sensing light, Rayleigh scattering is performed so that the intensity of the sensing light reflected from the particle may be similar in all directions of the particle.

In contrast, as shown in FIGS. 4B and 4C, when the size of the particle is similar to the wavelength of the sensing light, the intensity of the sensing light reflected from the particle may vary according to the direction of the sensing light. That is, the intensity of the sensing light may increase as the direction of the sensing light reflected by the particles is the same as or similar to the light traveling direction.

In addition, although the size of the particle is similar to the wavelength of the sensing light, as the size of the particle increases, as shown in FIGS. 4B and 4C, the sensing light reflected by the particle may be concentrated in the light traveling direction.

In order to utilize such a non-scattering phenomenon, the particle sensing apparatus according to an embodiment of the present invention includes a plurality of light receiving units, that is, a first light receiving unit 130 and a second light receiving unit 150. In this case, the first light receiving unit 130 and the second light receiving unit 150 may be disposed to be inclined with respect to the light traveling direction at different angles.

By analyzing the first particle sensing signal and the second particle sensing signal respectively output from the first light receiving unit 130 and the second light receiving unit 150, the degree to which the sensing light reflected by the particles is concentrated in the light traveling direction can be derived. , Through this, the size of the particles and the amount of the particles can be measured.

Meanwhile, as shown in FIGS. 3A and 3B, the first light receiving unit 130 is disposed on one side with respect to the light traveling direction, and the second light receiving unit 150 is disposed on the other side opposite to one side with respect to the light traveling direction. I can.

Unlike this, as shown in FIG. 5, the first light receiving unit 130 and the second light receiving unit 150 may be disposed on one side with respect to the light traveling direction. In this case, the first light receiving unit 130 and the second light receiving unit 150 disposed on one side may be provided on the module body 170 to be modularized.

As described above, arrangement positions of the first light receiving unit 130 and the second light receiving unit 150 may be changed according to design conditions or manufacturing conditions. In addition, when the first light receiving unit 130 and the second light receiving unit 150 are modularized, the manufacturing process can be simplified by assembling the light receiving module rather than assembling each of the first light receiving unit 130 and the second light receiving unit 150.

Meanwhile, the first angle a1 may be 25 degrees or more and 35 degrees or less. When the first angle a1 is less than 25 degrees, the sensing light in the light traveling direction, not the sensing light reflected by the particles, may enter the first light receiving unit 130. In addition, when the first angle a1 is greater than 35 degrees, interference between the first light receiving unit 130 and the second light receiving unit 150 may occur.

In addition, the second angle a2 may be 45 degrees or more and 55 degrees or less. When the second angle a2 is less than 45 degrees, interference may occur between the second light receiving unit 150 and the first light receiving unit 130. When the second angle a2 is greater than 55 degrees, sensing light that is excessively distant from the light traveling direction is incident on the second light receiving unit 150 and thus the accuracy of particle size determination may be degraded.

Meanwhile, the size of the measurable particles may be 0.2 µm or more and 100 µm or less, and the wavelength of the sensing light may be 630 nm or more and 970 nm or less. 6 is a graph showing the relationship between the wavelength and particle size of sensing light in which unscattered occurs.

As shown in FIG. 6, in order for the particle sensing device according to the embodiment of the present invention to use the non-scattering of particles, the size of the particle to be sensed and the wavelength of the sensing light must be appropriately matched. In an exemplary embodiment of the present invention, when the light emitting unit 110 emits a laser of 630 nm or more and 970 nm or less, the size of the measurable particle may be 0.2 µm or more and 100 µm or less.

On the other hand, Figure 7 shows a particle sensing device according to an embodiment of the present invention. As shown in FIG. 7, the light emitting part 110, the first light receiving part 130, and the second light receiving part 150 may be provided in the body 190. A flow path through which a fluid including particles can flow may be formed inside the body 190. In this case, the fluid introduced through the inlet hole 210 may flow out through the outlet hole 230 after passing through the flow path.

When the fluid passes through the flow path, the sensing light output from the light-emitting unit 110 is scattered by the particles to reach the first light-receiving part 130 and the second light-receiving part 150, and accordingly, the first light-receiving part 130 and The second light receiving unit 150 may output a first particle sensing signal and a second particle sensing signal, respectively.

A lens 250 for focusing or collimating the sensing light of the light emitting unit 110 may be formed in the light traveling direction, and a lens 250 is also formed near the first light receiving unit 130 and the second light receiving unit 150 Can be. The lens 250 can perform a normal operation even if the output of the light emitting unit 110 is lowered by focusing or collimating the sensing light.

The trap 270 may prevent reflection and scattering of the sensing light when the sensing light travels straight. In the absence of particles, the sensing light travels straight to reach the trap 270, and the sensing light reflected from the wall surface other than the particles may also be prevented from re-reflection and scattering of the sensing light by the trap 270.

The operation unit 290 may derive information on the size of a particle through the first particle sensing signal and the second particle sensing signal. To this end, the operation unit 290 may perform digital processing on the first particle sensing signal and the second particle sensing signal. The operation unit 290 may derive information on the size of particles through the first particle sensing signal and the second particle sensing signal on which digital processing has been performed.

Although not shown in the drawing, digital processing of the first particle sensing signal and the second particle sensing signal may be performed through a separate digital processing unit other than the operation unit 290.

In the embodiment of the present invention, the calculating unit 290 may derive information on the size of the particles through the intensity ratio of the first particle sensing signal and the second particle sensing signal.

[Equation 1]

R = D1s / D2s

In Equation 1, D1s may be the intensity of the first particle sensing signal, and D2s may be the intensity of the second particle sensing signal. According to the operation of the operation unit 290, R may be less than or greater than 1.0 according to the result of Equation 1. If R is less than 1.0, small-sized particles may be sensed, and if R is greater than 1.0, large-sized particles may be sensed.

[Equation 2]

R*α = weight factor = f (α = compensation constant)

The weighting factor is for deriving the size of the particle through the intensity of the first particle sensing signal or the second particle sensing signal. Since the first particle sensing signal is more sensitive to the size of the particle than the second particle sensing signal, in an embodiment of the present invention, the size of the particle may be derived by multiplying the intensity D1s of the first particle sensing signal by a weighting factor f. Of course, in some cases, the particle size may be derived through the second particle sensing signal and the weighting factor.

The weighting factor may derive a weighting factor by multiplying the R value by a compensation constant, and a weighting factor according to the size of the first particle sensing signal or the second particle sensing signal may be set through an experiment.

8 shows an example of a pattern of a first particle sensing signal and a second particle sensing signal of the first light receiving unit 130 and the second light receiving unit 150. 8 shows waveforms of the first particle sensing signal and the second particle sensing signal for each particle size, in which the first light receiving unit 130 and the second light receiving unit 150 are disposed at an angle of 30 degrees and 50 degrees with respect to the light traveling direction, respectively. This is the waveform in the state. Also, as in the conventional method, the waveform of the particle sensing signal when the light receiving unit is disposed at 90 degrees with respect to the light traveling direction is also shown.

Each graph represents the waveforms of the first particle sensing signal and the second particle sensing signal in a Cartesian coordinate system, and the small graph at the bottom left of each graph is the waveform of the first particle sensing signal and the second particle sensing signal in the polar coordinate system. Represents.

The X-axis of the large graph is an angle display, and the angle at this time indicates the angle between the incident direction and the scattered direction when the sensing light incident toward the particle is scattered around the particle as shown in FIG. 9. In addition, the Y-axis of the large graph represents the intensity of particle sensing signals. That is, the graph of FIG. 8 represents the intensity of the particle sensing signals according to the scattered angle, and it can be seen that the pattern of the intensity scattered for each angle is different according to the size of the scattered particles.

Meanwhile, the operation unit 290 may perform a particle counting function. That is, the number of particles may be derived by counting a case in which the intensity of at least one of the first particle sensing signal and the second particle sensing signal is greater than the reference value.

Meanwhile, as shown in FIG. 7, the particle sensing device according to another exemplary embodiment of the present invention may further include a fan 310 for forming a fluid flow. To this end, a pipe provided with a fan 310 may communicate with the outlet hole 230 or the inlet hole 210. The fan 310 can maintain a constant amount of fluid inflow, and the fan 310 provided in the pipe can be attached or detached according to the customer's intention.

As described above, the embodiments according to the present invention have been looked at, and the fact that the present invention can be embodied in other specific forms without departing from its spirit or scope other than the above-described embodiments is understood by those of ordinary skill in the art. It is self-evident to Therefore, the above-described embodiments are to be regarded as illustrative rather than restrictive, and accordingly, the present invention is not limited to the above description and may be modified within the scope of the appended claims and their equivalents.

Light-emitting unit 110
The first light receiving unit 130
The second light receiving unit 150
Module body 170
Body(190)
Inlet hole (210)
Outflow hole (230)
Lens(250)
Trap(270)
Operation unit 290
Fan (310)

Claims (10)

A light emitting unit that emits sensing light in a light traveling direction; And
And a first light receiving unit and a second light receiving unit respectively outputting a first particle sensing signal and a second particle sensing signal as the sensing light reflected on the particle is incident,
The first light receiving part is disposed to be inclined by a first angle with respect to the light traveling direction,
The particle sensing device, wherein the second light receiving unit is disposed to be inclined by a second angle different from the first angle with respect to the light traveling direction.
The method of claim 1,
Particle sensing device, characterized in that the first angle is less than 90 degrees, the second angle is greater than the first angle and less than 90 degrees.
The method of claim 1,
The first light receiving part is disposed on one side with respect to the light traveling direction,
Particle sensing device, characterized in that the second light receiving unit is disposed on the other side opposite to the one side with respect to the light traveling direction.
The method of claim 1,
Particle sensing device, characterized in that the first light receiving unit and the second light receiving unit are disposed at one side with respect to the light traveling direction.
The method of claim 4,
Particle sensing device, characterized in that the first light receiving unit and the second light receiving unit are provided in one module body.
The method of claim 1,
The first angle is 25 degrees or more and 35 degrees or less,
Particle sensing device, characterized in that the second angle is 45 degrees or more and 55 degrees or less.
The method of claim 1,
Particle sensing device, characterized in that the size of the measurable particles is 0.2 µm or more and 100 µm or less.
The method according to claim 6 or 7,
Particle sensing device, characterized in that the wavelength of the sensing light is 630 nm or more and 970 nm or less.
The method according to any one of claims 1 to 7,
Particle sensing device, characterized in that it further comprises an operation unit for deriving information on the size of the particles through the first particle sensing signal and the second particle sensing signal.
The method of claim 1,
The light emitting unit, the first light receiving unit and the second light receiving unit further comprises a body installed,
An inlet hole and an outlet hole are formed in the body,
The fluid containing the particles flows into the body through the inlet hole, and the fluid flows out of the body through the outlet hole,
Particle sensing device, characterized in that it further comprises a fan for forming the flow of the fluid.

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