JP2007047029A - Dust sensor and air cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust sensor capable of certainly and efficiently detecting dust by a simple constitution, and an air cleaner equipped with the dust sensor. <P>SOLUTION: The dust sensor 1 is mainly constituted of a housing 2, the surface case 3 for protecting the surface of the housing 2, the back lid 4 for protecting the back of the housing 2 and the element 5 which holds a light emitting part and a light detecting part to be housed in the housing 2. In this dust sensor 1, the size (inner peripheral edge Aa) of an air suction port 8 is formed so as to be made smaller than the size (outer peripheral edge Ab) of a dust detecting region SA. By this constitution, an air stream being a dust detecting target can be guided to the center part of the dust detecting region SA. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dust sensor for detecting dust (dust) such as cigarette smoke and dust, and an air cleaner provided with such a dust sensor.

  Air pollution is becoming a problem with the advancement of science and technology. For example, there is provided an air purifier that removes fine particles such as cigarette smoke and dust, dirt particles typified by fine powder, or house dust (in this application, dusts to be detected are collectively referred to as dust). Yes. In order to improve the operation efficiency of the air purifier, a photoelectric smoke detector (dust sensor) that detects a contamination state of air has been proposed (for example, see Patent Document 1).

  FIG. 9 is an explanatory diagram for explaining the relationship among the sizes of the airflow suction port, the airflow discharge port, and the dust detection region in the dust sensor according to the conventional example.

  The dust sensor 51 includes a housing 52, a front case 53 that protects the front side of the housing 52, a back cover 54 that protects the back side of the housing 52, a light emitting unit (not shown), and a light receiving unit (not shown). An element holder 55 that holds a not-shown element is the main component.

  A dust detection area SA is formed in the space of the housing 52. In addition, an airflow inlet 58 that introduces air (airflow) to be detected for dust and leads to the dust detection area SA is formed on the back side of the housing 52, and the airflow that releases the airflow after the dust detection is completed to the outside. A discharge port 59 is formed on the front side of the housing 52.

In the dust sensor 51, the size of the airflow inlet 58 (inner peripheral edge Aa) and the size of the airflow outlet 59 (inner peripheral edge Ac) are formed substantially the same as the size of the dust detection area SA (outer peripheral edge Ab). It is. With this configuration, a flow of airflow as a detection target is generated, so that dust in the airflow can be detected.
JP-A-8-62136

  However, in the conventional dust sensor 51, the dust detection area SA is configured to be approximately the same size as the airflow suction port 58 or smaller than the airflow suction port 58, so that the airflow introduced from the airflow suction port 58 is reduced. There is a problem that a part does not pass through the dust detection area SA, and a detection omission occurs without being a detection target, resulting in a decrease in detection efficiency.

  Furthermore, when detecting the size of the dust based on the level of detection at the light receiving portion, the light receiving sensitivity at the light receiving portion is different between the central portion and the peripheral portion of the dust detection area SA, so that accurate determination is difficult. was there. As a countermeasure against the distribution of light receiving sensitivity, it is conceivable to devise an optical system such as a lens, but there is a problem that the structure becomes complicated and expensive.

  The present invention has been made in view of such a situation, and irradiates the dust detection region with the irradiation light from the light emitting unit, and receives the reflected light from the dust in the airflow passing through the dust detection region by the light receiving unit. An object of the present invention is to provide a dust sensor that can detect dust reliably and efficiently with a simple configuration by making the inner periphery of the airflow suction port smaller than the outer periphery of the dust detection area in the dust sensor that detects dust. And

  Another object of the present invention is to provide an air purifier capable of efficiently and reliably purifying air by using an air purifier provided with a dust sensor according to the present invention.

  The dust sensor according to the present invention includes a dust detection region provided between the airflow inlet and the airflow outlet, a light emitting unit that irradiates the dust detection region with irradiation light, and reflection from the dust of the dust detection region. A dust sensor for detecting dust in the airflow passing through the dust detection region, wherein an inner peripheral edge of the airflow suction port is smaller than an outer peripheral edge of the dust detection region. .

  With this configuration, by narrowing and focusing the airflow as the detection target, it can be guided to the center of the dust detection area, so that detection omission can be prevented and accurate detection that is not affected by the difference in light receiving sensitivity is possible. Dust detection is possible.

  The dust sensor according to the present invention is characterized in that an inner peripheral edge of the airflow inlet is smaller than an inner peripheral edge of the airflow outlet.

  With this configuration, the airflow as the detection target can be narrowed down and the airflow as the dust detection target can be reliably guided to the dust detection region, so that accurate dust detection can be performed.

  In the dust sensor according to the present invention, the outer peripheral edge of the dust detection region is smaller than the inner peripheral edge of the air flow outlet.

  With this configuration, since the dust detection area can be narrowed down, the airflow can be accurately guided to prevent detection omission, and accurate dust detection can be performed.

  In the dust sensor according to the present invention, an outer peripheral edge of the dust detection region is larger than an inner peripheral edge of the air flow outlet.

  With this configuration, dust detection can be performed using the center of the dust detection area, so that the influence of the difference in light receiving sensitivity at the light receiving section relative to the center and the periphery of the dust detection area can be eliminated, so that accurate dust can be obtained. Detection is possible.

  In the dust sensor according to the present invention, the air flow inlet is configured by an element holder that holds the light emitting unit and the light receiving unit.

  With this configuration, the air flow inlet and the dust detection area can be easily and accurately aligned, which facilitates assembly, thereby reducing manufacturing costs and enabling accurate dust detection. .

  In the dust sensor according to the present invention, the air flow inlet is configured by a back cover of a housing containing an element holder for holding the light emitting part and the light receiving part.

  With this configuration, the air flow inlet and the dust detection area can be easily and accurately aligned, which facilitates assembly, thereby reducing manufacturing costs and enabling accurate dust detection. .

  In the dust sensor according to the present invention, the air flow inlet is narrower in the inside than the entrance.

  With this configuration, since the airflow suction port has a trumpet shape and the airflow can be narrowed and guided to the dust detection region, accurate dust detection can be performed.

  The air cleaner which concerns on this invention is equipped with the dust sensor which concerns on this invention, It is characterized by the above-mentioned.

  With this configuration, accurate dust detection is possible, so that an air cleaner capable of efficiently and reliably purifying air according to the amount of dust and the size of the dust is obtained.

  According to the dust sensor of the present invention, it is possible to accurately determine the type (large or small) of dust with a simple configuration by specifying the relative sizes of the airflow inlet, the dust detection area, and the airflow outlet. In addition, there is an effect that it can be detected efficiently.

  According to the air conditioner according to the present invention, there is an effect that it is possible to clean air efficiently and reliably according to the amount of dust and the size of the dust.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
FIG. 1 is an explanatory diagram showing the correlation among the sizes of the airflow inlet, the airflow outlet, and the dust detection area in the dust sensor according to the first embodiment of the present invention.

  The dust sensor 1 includes a housing 2, a front case 3 that protects the front side of the housing 2, a back cover 4 that protects the back side of the housing 2, a light emitting unit (not shown), and a light receiving unit (not shown). The element holder 5 included in the housing 2 is the main component. That is, the housing 2 includes the front case 3 and the back cover 4 and is configured to protect the element holder 5 from the outside.

  A dust detection area SA is formed in an appropriate space of the housing 2. In addition, air (airflow) that is subject to dust detection is introduced, and an airflow inlet 8 that guides to the dust detection area SA is formed on the back side (back cover 4) of the housing 2, and the airflow after the dust detection is completed. An air flow outlet 9 that discharges to the outside is formed on the front side (front case 3) of the housing 2.

  In the dust sensor 1 according to the present embodiment, the size (inner peripheral edge Aa) of the airflow suction port 8 is formed smaller than the size (outer peripheral edge Ab) of the dust detection area SA. This makes it possible to guide the airflow as a dust detection target to the center of the dust detection area SA, prevent detection of dust from being detected with respect to the introduced airflow, and the center of the dust detection area SA. The influence by the difference in the light receiving sensitivity at the light receiving unit with respect to the peripheral part can be eliminated. That is, the dust sensor 1 is a dust sensor that is accurate and has good detection efficiency.

  The size of the airflow inlet 8 (inner peripheral edge Aa) is smaller than the size of the airflow outlet 9 (inner peripheral edge Ac). This makes it possible to guide the airflow to surely pass through the dust detection area SA, prevent detection of dust from being detected with respect to the introduced airflow, and the center and peripheral parts of the dust detection area SA. It is possible to eliminate the influence due to the difference in the light receiving sensitivity at the light receiving unit.

  The size of the dust detection area SA (outer peripheral edge Ab) is smaller than the size of the airflow outlet 9 (inner peripheral edge Ac). As a result, the dust detection area SA can be narrowed down and the airflow can be reliably guided, so that accurate dust detection can be performed and detection efficiency can be improved.

<Embodiment 2>
FIG. 2 is an explanatory diagram showing the correlation among the sizes of the airflow inlet, the airflow outlet, and the dust detection area in the dust sensor according to the second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the size of the dust detection area SA (outer peripheral edge Ab) is larger than the size of the airflow outlet 9 (inner peripheral edge Ac). As a result, dust can be detected at the center of the dust detection area SA, and the influence of the difference in light receiving sensitivity at the light receiving section with respect to the center and the periphery of the dust detection area SA can be eliminated, and accurate dust detection can be performed. Is possible.

<Embodiment 3>
FIG. 3 is an explanatory diagram showing a case where the air flow inlet of the dust sensor according to the third embodiment of the present invention is configured by an element holder. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the air flow inlet 8 is configured by the element holder 5. By extending a part of the element holder 5 and forming an airflow suction port 8 that passes through the back cover 4 and communicates with the outside, the airflow suction port 8 is a part of the element holder 5 (the airflow constituted by the element holder 5). It is configured to communicate with the dust detection area SA via the introduction path).

  As a result, it is possible to easily and accurately align the airflow suction port 8 and the dust detection area SA. Therefore, since the dust sensor 1 can be assembled easily and accurately, the manufacturing cost can be reduced and the dust can be detected accurately.

<Embodiment 4>
FIG. 4 is an explanatory diagram showing a case where the air flow inlet of the dust sensor according to the fourth embodiment of the present invention is configured by a case back cover. The same parts as those in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the airflow suction port 8 is constituted by the case back cover 4. By opening an opening provided in a part of the back cover 4 to the inside and forming an air flow suction port 8 penetrating the element holder 5, the air flow suction port 8 is a part of the back cover 4 (the back cover 4 is configured by the back cover 4. It is configured to communicate with the dust detection area SA via an air flow introduction path).

  As a result, it is possible to easily and accurately align the airflow suction port 8 and the dust detection area SA. Therefore, the dust sensor 1 can be easily assembled, so that the manufacturing cost can be reduced and accurate dust detection can be performed.

<Embodiment 5>
FIG. 5 is an explanatory diagram showing a case where the airflow suction port of the dust sensor according to the fifth embodiment of the present invention is configured in a trumpet shape. The same parts as those in the first to fourth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the airflow suction port 8 is formed in a trumpet shape with a narrower interior than the entrance. As a result, it is possible to easily and accurately align the airflow inlet 8 and the dust detection area SA and to narrow the airflow and guide it to the center of the dust detection area SA. Therefore, accurate dust detection is possible. The present embodiment is a modification of the fourth embodiment, but can also be applied to the third embodiment.

<Embodiment 6>
FIG. 6 is a perspective plan view showing the relationship between the layout of the light emitting unit and the light receiving unit and the dust detection area in the dust sensor according to the sixth embodiment of the present invention. The same parts as those in the first to fifth embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the light emitting unit 6 is formed on one wall surface of the housing 2, and the light receiving unit 7 is formed on the other wall surface facing the light emitting unit 6. The light emitting unit 6 includes a light emitting element 6a, and the light receiving unit 7 includes a light receiving element 7a. The light emitting element 6a is, for example, a semiconductor light emitting diode (LED), and the light receiving element 7a is, for example, a semiconductor phototransistor. In the light emitting unit 6 and the light receiving unit 7, the detection accuracy is improved by condensing the irradiation light and the reflected light using a suitable lens (optimizing by narrowing the light beam diameter).

  During operation, the irradiation light Le is emitted from the light emitting unit 6 (light emitting element 6a) toward the dust detection area SA. The irradiation light Le is scattered and reflected by the dust DD contained in the air current in the dust detection area SA, and enters the light receiving unit 7 (light receiving element 7a) as reflected light Lr corresponding to the amount of dust DD. Therefore, the area where the optical axis of the irradiation light Le and the optical axis of the reflected light Lr intersect becomes the dust detection area SA. The light receiving unit 7 can detect the dust DD as an electric signal by receiving the reflected light Lr and performing photoelectric conversion. That is, the state of dust DD can be detected as an electric signal.

  The air flow inlet 8 (not shown in FIG. 6) and the air outlet 9 (not shown in FIG. 6) are configured to correspond to the dust detection area SA so as to face each other on the front side and the back side of the drawing. is there.

<Embodiment 7>
FIG. 7 is a circuit block diagram showing a configuration of circuit blocks of a detection unit and a control unit of a dust sensor according to Embodiment 7 of the present invention.

  The dust sensor 1 includes a detection unit 10 and a control unit 20. The detection unit 10 includes a light emitting unit 6 and a light receiving unit 7. The light emitting unit 6 includes a light emitting element 6a and a drive circuit 6b that drives the light emitting element 6a, and emits irradiation light Le according to LED driving pulse input supplied from the signal processing unit 21 of the control unit 20.

  The light receiving unit 7 includes a light receiving element 7a and amplification circuits 7b, 7c, and 7d, amplifies the reflected light Lr as appropriate, and outputs the amplified light to the analog / digital converter 22 of the signal processing unit 21. Since the signal detected by the light receiving element 7a is extremely small, the signal is amplified to a level that can be processed by the analog-digital converter 22 using a plurality of amplifier circuits (7a, 7b, 7c).

  The signal processing unit 21 is configured by a microcomputer, and performs dust detection by appropriately converting a detection output as an analog signal into a digital signal by an analog / digital converter 22 and performing necessary signal processing. The amount of dust and the size (type) of dust can be detected by detecting dust. The controller 20 is connected to an appropriate power source 23 to supply power necessary for circuit operation.

  In addition, since the signal processing unit 21 performs signal processing with a digital signal, it can also be used as a control unit of a computer-controlled air purifier (see Embodiment 8).

  8A and 8B are waveform diagrams for explaining the state of signal processing in the control unit of the dust sensor according to the seventh embodiment of the present invention. FIG. 8A shows the state of LED driving pulse input, and FIG. The detection output state corresponding to dust is shown.

  The LED driving pulse input is repeated at a cycle Ts, and power is supplied to the light emitting element 6a during the cycle Tp. That is, the irradiation light Le is emitted from the light emitting element 6a during the period Tp (light emission period). Corresponding to the light emission of the light emitting element 6a, the reflected light Lr is detected by the light receiving element 7a and detected as a detection output. If the detection output is an analog signal and the dust (amount and size) is less than the detection limit (threshold Th), the detection output becomes a waveform having a peak value less than the threshold Th, such as Vpa, and the detection limit. If the threshold value exceeds (threshold Th), the detection output becomes a waveform having a peak value equal to or higher than the threshold Th such as Vpb, and dust can be detected. That is, the peak value is proportional to the amount of dust, and increases as the size of the dust increases. The detection accuracy can be further improved by providing a plurality of levels of the threshold Th.

<Eighth embodiment>
The air purifier (not shown) according to the present embodiment includes the dust sensor 1 described in the first to seventh embodiments. By providing the dust sensor 1 described in the first to seventh embodiments, accurate and efficient dust detection can be performed. Therefore, the dust sensor 1 can be accurately set according to the amount of dust and the size (type) of dust. And it becomes possible to control an air cleaner efficiently, and it becomes an air cleaner in which efficient and reliable air purification is possible.

  In addition, the air cleaner which concerns on this Embodiment can include air conditioning equipment, such as an air conditioner. In that case, the control part 20 (refer Embodiment 7) of the dust sensor 1 can be made common with the control part (not shown) of an air cleaner.

It is explanatory drawing which shows the correlation of the magnitude | size of the airflow inlet in the dust sensor which concerns on Embodiment 1 of this invention, an airflow outlet, and a dust detection area | region. It is explanatory drawing which shows the correlation of the magnitude | size of the airflow inlet in the dust sensor which concerns on Embodiment 2 of this invention, an airflow outlet, and a dust detection area | region. It is explanatory drawing which shows the case where the airflow suction inlet of the dust sensor which concerns on Embodiment 3 of this invention is comprised by the element holder. It is explanatory drawing which shows the case where the airflow suction inlet of the dust sensor which concerns on Embodiment 4 of this invention is comprised by the back cover of the housing | casing. It is explanatory drawing which shows the case where the airflow inlet of the dust sensor which concerns on Embodiment 5 of this invention is comprised in a trumpet shape. It is a perspective top view which shows the relationship between the layout of the light emission part in the dust sensor which concerns on Embodiment 6 of this invention, a light-receiving part, and a dust detection area | region. It is a circuit block diagram which shows the structure of the circuit block of the detection part of the dust sensor which concerns on Embodiment 7 of this invention, and a control part. It is a wave form diagram explaining the state of the signal processing in the control part of the dust sensor which concerns on Embodiment 7 of this invention, (A) shows the state of the pulse input for LED drive, (B) respond | corresponds to dust. Indicates the state of the detection output output. It is explanatory drawing explaining the relationship of the magnitude | size of the airflow inlet in the dust sensor which concerns on a prior art example, an airflow outlet, and a dust detection area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dust sensor 2 Case 3 Front case 4 Back cover 5 Element holder 6 Light emitting part 6a Light emitting element 7 Light receiving part 7a Light receiving element 8 Air current inlet 9 Air current outlet 10 Detection part 20 Control part Aa Inner edge (size of air current inlet Sa)
Ab outer periphery (size of dust detection area)
Ac Inner edge (size of airflow outlet)
DD Dust Le Irradiated light Lr Reflected light SA Dust detection area

Claims (8)

A dust detection area provided between the airflow inlet and the airflow outlet, a light emitting unit that emits irradiation light to the dust detection area, and a light receiving unit that receives reflected light from dust in the dust detection area A dust sensor for detecting dust in the airflow passing through the dust detection region,
The dust sensor according to claim 1, wherein an inner peripheral edge of the air flow inlet is smaller than an outer peripheral edge of the dust detection region.   The dust sensor according to claim 1, wherein an inner peripheral edge of the airflow suction port is smaller than an inner peripheral edge of the airflow discharge port.   The dust sensor according to claim 2, wherein an outer peripheral edge of the dust detection region is smaller than an inner peripheral edge of the air flow outlet.   The dust sensor according to claim 2, wherein an outer peripheral edge of the dust detection region is larger than an inner peripheral edge of the air flow outlet.   5. The dust sensor according to claim 1, wherein the air flow inlet is configured by an element holder that holds the light emitting unit and the light receiving unit.   The said air flow inlet is comprised by the back cover of the housing | casing which contains the element holder holding the said light emission part and the said light-receiving part, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Dust sensor.   The dust sensor according to claim 5 or 6, wherein the air flow inlet has an inside narrower than the inlet.   An air cleaner comprising the dust sensor according to any one of claims 1 to 7.

Images