JP3056798B2 - Floating particle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting suspended particles such as smoke particles and dust.

[0002]

2. Description of the Related Art Conventionally, in a smoke detector, an air purifier, etc., a floating particle detecting device for detecting floating particles such as smoke particles and dust has been used. Various forms are considered for the detection of suspended particulates . As shown in FIG. 9 , light such as infrared rays is applied to the detection space by the light emitting element ED, and scattering generated when the suspended particulates are present in the detection space. It is often adopted that light is received by a light receiving element LD and floating particles are detected based on a change in a light receiving signal output from the light receiving element LD.

[0003] The light emitting element ED is driven, and the light receiving element LD is driven.
A circuit section for processing a light receiving signal output from the light emitting element ED and the light receiving element LD is mounted on a circuit board 4, and the circuit board 4 is housed in the case 1. That is, the detection space is formed in the case 1. On the circuit board 4, the components constituting the circuit section are arranged on the same surface as the light emitting element ED and the light receiving element LD, so that the circuit board 4 is provided with the partition wall 43, and through the partition wall 43, The side is a detection space, and the other side is a space for mounting components. In addition, the circulation port 6 for introducing the suspended particulates into the detection space is formed only on one surface of the case 1.

[0004]

In the above configuration, only a part of the circuit board 4 on one surface side is used as a detection space, and the detection space is small. The amount is small and the intensity of scattered light cannot be sufficiently obtained. That is, there is a problem that the sensitivity is low, and it cannot be detected that the concentration of the suspended fine particles is low. In addition, since the circulation port 6 is formed only on one surface of the case 1, it is necessary to wait for the suspended particulates to be naturally introduced, and it is determined whether or not the air introduced by the air purifier is clean. In such a case, there is a problem that the sensitivity cannot be increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to increase the detection space and detect the presence or absence of floating particles in an air flow path, thereby detecting floating particles with high sensitivity. It is an object of the present invention to provide an apparatus for detecting suspended particulates.

[0006]

[0007]

According to the first aspect of the present invention , a detection space is provided.
Light-emitting element that irradiates light to light, and light emitted from the light-emitting element
A light-receiving element that receives scattered light due to suspended fine particles,
Driving the light emitting element and receiving the light output from the light receiving element
For detecting suspended particles in the detection space based on optical signals
Circuit board with light-emitting element and light-receiving element
Board and circuit board are installed and suspended particulates are introduced
With a case in which a detection space to be detected is formed.
In the free particle detector, the components that make up the circuit
Optical element and light receiving element on opposite sides of circuit board
A pair is arranged, and a pair of
Are formed on the front and back sides of the circuit board.
Is formed a flow path through the sensing space between the two flow ports, to case <br/> scan has a body front and back sides of the circuit board is opened surrounds the periphery of the circuit board, the circuit portion of the circuit board Metal first blockades one opening of the body on the mounting surface side
And a second cover for closing the other opening of the body on the side of the circuit board on which the light emitting element and the light receiving element are arranged, and the body and the second cover cover the entire surface of the conductive layer. The contact portion between the body and the second cover is formed by melting and welding the insulating layers so that the conductive layers are electrically connected to each other. is there.

According to a second aspect , a light source for irradiating light to the detection space is provided.
Floating particles in the light emitted from the optical element and the light emitting element
Light-receiving element that receives scattered light due to
And based on the light receiving signal output from the light receiving element
The circuit for detecting airborne particles in the detection space is
The circuit board mounted with the
The detection space where the suspended particulates are introduced
Floating particulate detection device having a case formed inside
In the above, the light emitting element and the light receiving element
The elements are placed on the opposite sides of the circuit board and the case
Has a pair of circuit ports through which outside air flows in the case.
Formed on both sides of the board, inside the case
Is a flow path through the sensing space is formed, to case includes a body front and back sides of the circuit board is opened surrounds the periphery of the circuit board, the one opening of the body in side mounted with the circuit portion of the circuit board A first cover made of a metal to be closed and a second cover closing the other opening of the body on the surface of the circuit board on which the light emitting element and the light receiving element are arranged, wherein the body and the second cover are electrically conductive. The body, the first cover, and the second cover are formed of a material in which a filler of a material is filled into an insulating synthetic resin, and the body, the first cover, and the second cover are electrically connected to each other and electrically connected to a ground line of the circuit unit. It is being done.

[0009]

According to the first aspect of the present invention, the components constituting the circuit section, the light emitting element and the light receiving element are arranged on opposite sides of the circuit board. Since there is no component, the detection space can be widened by forming the detection space on this one surface side. In the case, a pair of flow ports for flowing outside air is formed in the case on both the front and back sides of the circuit board, and a flow path passing through the detection space is formed between the two flow ports in the case. Therefore, floating particulates can be circulated between the two flow ports, and even if air is forcibly circulated, they can be arranged on the air flow path to detect the floating particulates. . As described above, the detection space is wide, and the detection space can be set on the air flow path,
It will be able to introduce a large amount of suspended particulates in the sensing space, Ru Nodea that can detect airborne particulates with high sensitivity. Further, a body surrounding the detection space and a second
The cover is made of conductive material and
Is connected to the light-receiving element,
Noise can be prevented from entering from outside,
Signal-to-noise of the circuit that processes the received light signal output from the child
The ratio can be high. That is, this
This also leads to higher sensitivity.

[0010]

According to the second aspect of the present invention, the circuit section is configured.
Components and light-emitting and light-receiving elements on a circuit board
On the opposite side of the circuit board.
There is no roadside part, so it is detected on this one side
It is necessary to make the detection space wide by forming a space
You can. The outside air flows into the case.
A pair of flow openings to be passed are formed on both sides of the circuit board.
In the case, there is a flow path between the two
As it is formed, suspended particulates are distributed between both distribution ports.
And force the air to flow
Even if it is in the air, place it on the air flow path to detect suspended particulates.
You can know. As described above, the detection space
And the detection space can be set on the air flow path.
As a result, a large amount of suspended particulates can be introduced into the detection space.
And can detect suspended particulates with high sensitivity.
You can. Furthermore, the whole to case formed of a conductive material, and has electrodes connected to the case to the ground line of the circuit unit, suspended particles adhere to the inner circumferential surface of the sensing space by the charging of the case This can prevent the occurrence of stray light and the occurrence of malfunctions over time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) First, the basic configuration of the present embodiment will be described with reference to FIGS.
In the following, the configuration which is the gist of the present embodiment will be described.
Will be described with reference to FIG. 6 and FIG. FIG.
As shown in FIG. 3, a light emitting element ED composed of a light emitting diode and a light receiving element LD composed of a photodiode are disposed in a rectangular parallelepiped case 1. The case 1 includes a rectangular frame-shaped body 10 made of a synthetic resin and having two opposing surfaces opened, a first metal cover 20 for closing both opening surfaces of the body 10, and a second synthetic resin second cover.
And the cover 30. In the body 10, a detection chamber 12 surrounded by a partition 11 is formed.
The first cover 20 and the second cover 30 are formed with flow ports 21 and 31, respectively, and the flow ports 21 and 31 are located on a straight line in a direction orthogonal to the opening surface. Detection room 1
A flow window 14 is opened at a portion corresponding to the flow port 21 on a surface of the partition 11 surrounding the second cover 20, the surface facing the first cover 20, and a rising wall 15 is formed at a periphery of the flow window 14. . A step 16 to be inserted into the distribution window 21 is formed at the tip of the rising wall 15. Therefore, the rising wall 15 functions as a spacer between the partition 11 and the first cover 20. The circuit board 4 is disposed in a space formed between the first cover 20 and the partition 11. On the circuit board 4,
A through hole 41 into which the rising wall 15 is inserted is drilled. A cylindrical spacer 4 is provided between the circuit board 4 and the first cover 20.
2, the first cover 20 is coupled to the body 10 by screwing the assembly screw 22 inserted through the first cover 20 to the body 10 through the spacer 42, and at the same time, the circuit board 4 It is fixed to. The light emitting element ED and the light receiving element LD are arranged on one surface of the circuit board 4 so as to face the detection chamber 12.

The second cover 30 has holders 32 and 33 for holding the light emitting element ED and the light receiving element LD, respectively. The holder 33 holding the light receiving element LD includes a plurality of light shielding plates 34 arranged in the optical axis direction, and prevents light from entering the light receiving element LD from an unnecessary direction.
A plurality of (four) locking claws 35 project from the surface facing the body 10 on the second cover 30, and the locking claws 35 are inserted inside the body 10 and formed on the side surfaces of the body 10. The distal end portion engages with the locking hole 17, and the second cover 30 is coupled to the body 10 by the locking claw 35 engaging with the locking hole 17.

As shown in FIG. 2, a partition 18 is formed in the detection chamber 12 between the light emitting element ED and the light receiving element LD, and a notch 19 is formed in the partition 18 at a position corresponding to the flow window 14. ing. The partition 18 prevents direct light from the light emitting element ED from being incident on the light receiving element LD. The light emitting element ED and the light receiving element LD are arranged in the upper part of FIG.
2 are inclined so as to gradually reduce the distance from the bottom to the top in FIG. Therefore, the detection chamber 12
The light from the light emitting element ED is reflected obliquely downward and leftward in FIG. 2 by the partition wall 11, so that it is possible to prevent the light from being directly reflected toward the flow passage 14. Further, the light reflected by the partition 11 of the detection chamber 12 is reflected by the inner peripheral surface of the case 1 and the partition 18, and the amount of light is attenuated each time the light is reflected. A part of the partition wall 11 of the detection Intellectual chamber 12 constitute a light trap.

With the above-described structure, the two outlets 2
A flow path that passes through the detection chamber 12 can be formed between the light-emitting element ED and the light-receiving element L.
It is possible to detect the particles suspended in the sensing space is overlapping portion of the light receiving region of D. Also the case
By forming the above-mentioned optical trap in 1,
Prevents light from being reflected into the detection space in case 1
The light emitted from the light emitting element
Light entering the photodetector due to stray light generated by reflection on the peripheral surface
Reduces light emission and detects floating particulates with high sensitivity and stability
can do. By the way, as shown in FIG. 4, the light emitting element ED includes an oscillation circuit 51 and a driving circuit 52.
It is driven so as to be turned on intermittently at a substantially constant cycle.

On the other hand, the light receiving signal of the current output corresponding to the light receiving amount of the light receiving element LD is converted into the light receiving amount through a very high input impedance (about 100 MΩ) current-voltage conversion circuit 61 constituted by using an operational amplifier circuit. It is converted to the corresponding voltage output. Thereafter, the received light signal converted into the voltage output passes through the band-pass filter 62 (50 Hz to 10 kHz), and is further clipped by the peak cut circuit 63 composed of a diode connected in anti-parallel to remove a noise component. You.

After the noise component is removed from the received light signal in this manner, the received light signal is sampled and held by the sample-and-hold circuit 64.
To the light emitting element ED based on the output of the oscillation circuit 51.
Light reception signal is taken in synchronization with the lighting timing of
The voltage value of the light receiving signal is held until the next light receiving signal is input. By the way, in this basic configuration, a digital output unit that outputs a binary signal corresponding to whether the concentration of the suspended particles in the detection space is equal to or more than a predetermined value or less than a predetermined value, and a continuous amount corresponding to the concentration of the suspended particles. And an analog output unit for outputting the same.

The digital output section comprises a comparator 65 for comparing the output of the sample-and-hold circuit 64 with a reference voltage. When the concentration of floating particulates is less than a predetermined value, the output becomes L level, and when the concentration is higher than the predetermined value, the output becomes H level. It is set to be. On the other hand, the analog output section outputs the output of the sample and hold circuit 64 and the reference voltage generation circuit 66.
And a differential amplifier circuit 67 for performing correction by taking a difference from the output reference voltage. The output of the differential amplifier circuit 67 is amplified by the DC amplifier circuit 68, so that a continuous output corresponding to the received light signal is obtained. It is configured so that it can be obtained. The reference voltage generation circuit 66 includes a first reference voltage generation unit 66a that divides a power supply voltage, and a second reference voltage generation unit that outputs a second reference voltage based on the first reference voltage output from the first reference voltage generation unit 66a. And a reference voltage generator 66b. The differential amplifier 67 receives the second reference voltage, and the DC amplifier 68 receives the first reference voltage. Each of the above circuits is supplied with power from a power supply circuit 55 for converting a DC input to a constant voltage.

Here, the components other than the light emitting element ED and the light receiving element LD among the components constituting the circuit section are surface-mounted using chip components as much as possible. Also, the light emitting element ED and the light receiving element LD and other components are:
It is arranged on the opposite surface of the circuit board 4 on both sides. That is, most parts of the circuit portion are arranged on the surface of the circuit board 4 facing the first cover 20. If you do this,
A light emitting element E is provided on the surface of the circuit board 4 on the detection chamber 12 side.
Since D and other components of the light receiving element LD are hardly mounted, a large space can be used as the detection chamber 12, and the amount of outside air introduced into the detection chamber 12 is increased to operate with high sensitivity. It becomes possible.

The apparatus A for detecting suspended particulates configured as described above is used, for example, in an air purifier as shown in FIG. The air purifier B includes a fan 72 in a housing 71.
, And is configured to send out the air introduced from the front surface of the housing 71 from an air outlet 76 provided on the upper surface of the housing 71. A front cover 73 is detachably mounted on the front surface of the housing 71, and a pair of filters 75a, 7 held by a filter holder 74 is provided between the housing 71 and the front cover 73.
5b is provided. The filter 75a is provided to prevent large dust from entering the inside, and the filter 75b is provided to remove floating particulates and odor. Here, the floating particle detecting device A is disposed in the housing 71 so that a part of the air that has passed through the filter 75a is introduced into the floating particle detecting device A. Further, the suspended particulate detection device A is disposed on a flow path to the fan 72 so that air is forcibly circulated when the fan 72 operates. According to such a configuration, after the operation of the fan 72, when the concentration of the suspended particulates detected by the suspended particulate detection device A becomes equal to or lower than the predetermined value, the fan 72 is regarded as being air-cleaned. Control such as automatic stop is enabled.

In [0021] a roller, because the light receiving signal output from the light receiving element LD is weak, the electromagnetic waves such as foreign, a problem that the signal-to-noise ratio is lowered. Therefore, in the present embodiment, the electromagnetic shielding is performed by forming the body 10 and the second cover 30 using a conductive material.

That is, the body 10 and the second cover 30 are formed of a conductive synthetic resin in which a filler such as a short metal fiber or a short carbon fiber is mixed in a base synthetic resin such as ABS or polystyrene. Fig. 6 (a)
As shown in the figure, the conductive synthetic resin is formed such that the entire surface of the conductive layer 2 having conductivity has an insulating layer 3 made of a synthetic resin as a base.
The structure is covered with.

By the way, the use of the body 10 and the second cover 30 as an electromagnetic shield, it is necessary to the conductive layer 2 between the body 10 and the second cover 30 to the same potential, as the basic structure, This requirement cannot be satisfied only by engaging the locking claw 35 with the locking hole 17. That is, as shown in FIG.
Cannot electrically connect the conductive layer 2. Therefore, in this embodiment, as shown in FIG. 7, a ridge 13 having a triangular cross section is provided on the surface of the body 10 facing the second cover 30, and the ridge 13 is formed by ultrasonic welding. By melting the ridge 13, the insulating layer 3 is broken, and the conductive layer 2 is electrically connected as shown in FIG. 6 (a). In this way, the body 10
And the second cover 30 can be joined without any gap.

On the other hand, since the first cover 20 and the body 10 are joined by the assembling screws 22, if the body 10 is tapped and the metal assembling screws 22 are used, the first cover 20 and the And can be electrically connected. With the above configuration, the body 10, the first cover 20, and the second cover 30 can be electrically connected to each other to function as an electromagnetic shield, and the signal-to-noise ratio can be improved. is there. Here, by electrically connecting the first cover 20 and a ground line provided on the circuit board 4, charging of the case 1 can be prevented. It is possible to suppress the aging of the stray light due to the adhesion to the surface, and to prevent a malfunction for a long period of time .

[0025] (Example 2) In Example 1, but using the conductive synthetic resin in case 1,
In this embodiment, as shown in FIG. 8, a conductive film 5 is formed at a key position to provide an electromagnetic shielding effect and an antistatic effect. The conductive film 5 is formed by applying a conductive paint or plating a metal such as nickel or copper, and the same effect as when a conductive synthetic resin is used can be expected. The other configuration is the same as that of the first embodiment, and the description is omitted.

[0026]

[Effect of the Invention] As described above, according to the first aspect, since the place on the opposite side to each other and the components constituting the circuit portion and the light emitting element and a light receiving element on a circuit board, the circuit board Since there is no component of the circuit section on one surface side, the detection space can be widened by forming the detection space on this one surface side. In addition, a pair of flow ports through which outside air flows in the case are formed on the front and back sides of the circuit board, and the case is detected between the two flow ports in the case.
Since a flow path passing through the intellectual space is formed , floating particles can be circulated between both flow ports, and even if air is forced to flow, it is arranged on the air flow path and floats Fine particles can be detected. As described above, the detection space is wide, and the detection space can be set on the air flow path. As a result, a large amount of floating particles can be introduced into the detection space, and the floating particles can be detected with high sensitivity. The effect is that it can be done .
In addition, the body surrounding the detection space and the second cover
Formed of electrically conductive material and electrically connected to each other
Noise, such as electromagnetic waves, is external to the photodetector.
Light from the light-receiving element.
The signal-to-noise ratio of the circuit that processes the received light signal
You can do it. That is, by this
Also has the advantage of leading to higher sensitivity.

[0027]

According to the configuration of claim 2 , the circuit section is configured.
Components and light-emitting and light-receiving elements on a circuit board
On the opposite side of the circuit board.
There is no roadside part, so it is detected on this one side
It is necessary to make the detection space wide by forming a space
You can. The outside air flows into the case.
A pair of flow openings to be passed are formed on both sides of the circuit board.
In the case, there is a flow path between the two
As it is formed, suspended particulates are distributed between both distribution ports.
And force the air to flow
Even if it is in the air, place it on the air flow path to detect suspended particulates.
You can know. As described above, the detection space
And the detection space can be set on the air flow path.
As a result, a large amount of suspended particulates can be introduced into the detection space.
And can detect suspended particulates with high sensitivity.
It has the effect of being able to cut. Furthermore, since the entire case is formed of a conductive material and the case is electrically connected to the ground line of the circuit section, it is possible to prevent floating particles from adhering to the inner peripheral surface of the detection space due to charging of the case. This can prevent the stray light from increasing over time and prevent malfunction from occurring.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a basic configuration of a first embodiment.

FIG. 2 is a front view showing a basic configuration of the first embodiment with a second cover removed.

FIG. 3 is a longitudinal sectional view illustrating a basic configuration of the first embodiment.

FIG. 4 is a block diagram illustrating a basic configuration of the first embodiment.

FIG. 5 is an exploded perspective view showing a usage form of the basic configuration of the first embodiment.

6A is a cross-sectional view of a main part of Example 1 , and FIG. 6B is a cross-sectional view of a main part of a comparative example.

FIG. 7 is a cross-sectional view of a main part of Embodiment 1 before processing.

FIG. 8 is a longitudinal sectional view of the second embodiment.

FIG. 9 is an exploded perspective view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 case 2 conductive layer 3 insulating layer 4 circuit board 10 body 20 first cover 21 communication port 30 second cover 31 communication port 41 through hole ED light emitting element LD light receiving element

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-213853 (JP, A) JP-A-1-259496 (JP, A) JP-A-54-29078 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) G01N 21/00-21/61

Claims (2)

(57) [Claims] 1. A light-emitting element for irradiating light to a detection space, a light-receiving element for receiving scattered light due to suspended fine particles in light emitted from the light-emitting element, and a light-receiving element for driving the light-emitting element and outputting from the light-receiving element. A circuit board mounted with a light-emitting element and a light-receiving element for detecting a floating particle in the detection space based on a signal, and a detection space into which the circuit board is mounted and the floating particle is introduced are formed inside. In the apparatus for detecting suspended particulates provided with a case, the components constituting the circuit section, the light emitting element and the light receiving element are arranged on opposite sides of the circuit board, and the case has a pair of flow ports through which outside air flows in the case. passing There are formed on the front and back sides of the circuit board, is in the case the sensing space between both flow port
Flow path is formed, and the case surrounds the periphery of the circuit board.
Both the body with the circuit board open on both sides and the circuit board
One opening of the body on the side of the board where the circuit is mounted
A first metal cover for closing the circuit board;
The other side of the body on the side where the light emitting element and light receiving element are arranged
And a second cover for closing the opening of the body.
And the second cover is made of synthetic resin over the entire surface of the conductive layer.
Body made of a material covered with an insulating layer consisting of
A contact portion between the second cover and the second cover is electrically connected to each other.
A floating particle detecting device characterized by melting and welding an insulating layer so as to be continued . 2. A light emitting device for irradiating light to a detection space, and a light emitting device.
Light scattered by suspended particles among light emitted from optical elements
A light receiving element for receiving light and a light emitting element are driven and received.
Based on the received light signal output from the optical element
Light emitting element and light receiving element
When the circuit board mounted with the
In both cases, a detection space into which suspended particulates are introduced is formed inside.
In a suspended particle detection device with a
The parts that make up the road, the light emitting element and the light receiving element
Placed on opposite sides of the board, inside the case
A pair of outlets that allow the outside air to flow through the front and back sides of the circuit board
The inside of the case passes through the detection space between the two
That flow path is formed, to case a metal for closing the body front and rear sides are open in the circuit board surrounds the periphery of the circuit board, the one opening of the body in side mounted with the circuit portion of the circuit board And a second cover for closing the other opening of the body on the surface of the circuit board on which the light emitting element and the light receiving element are arranged, and the body and the second cover are made of a conductive material filler. Has insulating properties
Is formed by the filling material in a synthetic resin that, the body and the
The first cover and the second cover are electrically connected to each other.
Rutotomoni, suspended particulates detecting device you characterized by comprising <br/> is electrically connected to the ground line of the circuit portion.