WO2023125449A1 - Air test structure, air filtration device and breathing machine - Google Patents

Abstract

An air test structure, an air filtration device and a breathing machine. The structure comprises an air flow channel (1) for air circulation, a laser light source (2), a fluorescence filter (3), a fluorescence receiver (4), and a signal conversion circuit (5), wherein the laser light source (2), the fluorescence filter (3) and the fluorescence receiver (4) are located in the air flow channel (1); the laser light source (2) excites biological particles in the air flow channel (1) to generate scattered light and fluorescent light; the fluorescence filter (3) reflects the scattered light and can be transmitted by the fluorescent light; the fluorescence receiver (4) converts the fluorescent light into a target current signal; and the signal conversion circuit (5) converts the target current signal into a target voltage signal, such that a signal processing system (8) collects the target voltage signal and then determines the number of biological particles according to a voltage value of the target voltage signal.

Description

An air detection structure, an air filter device and a ventilator

Cross References to Related Applications

This disclosure claims the priority of a patent application filed with the China Patent Office on December 31, 2021, with application number 202111678068.1 and titled "An Air Detection Structure, Air Filtration Device, and Air Filtration Equipment", the entire contents of which are incorporated by reference in this disclosure.

technical field

The invention relates to the technical field of air filtration, in particular to an air detection structure, an air filtration device and a ventilator.

Background technique

Currently, due to environmental changes, user groups pay more and more attention to the air quality in designated spaces, such as installing air filter devices indoors to filter the air. However, the replacement of air filter devices currently on the market is either based on whether the time has expired, or based on the evaluation of simple stress parameters, such as pressure, flow and other parameters to complete the replacement reminder.

Since the above method has no rigorous data basis, it often happens that the filter device has failed before the filter device is replaced, and the air quality cannot be guaranteed.

Contents of the invention

In view of the above problems, the present invention is proposed to provide an air detection structure, an air filter device and a ventilator that overcome the above problems or at least partially solve the above problems.

According to the first aspect of the present invention, the present invention provides an air detection structure, the structure includes an air channel for air circulation, a laser light source, a fluorescence filter, a fluorescence receiver and a signal conversion circuit, the laser light source , the fluorescent filter and the fluorescent receiver are located in the air flow channel, and the fluorescent filter and the laser light source are arranged oppositely on both sides of the air flow channel;

The fluorescence receiver converts the fluorescence passing through the fluorescence filter into a target current signal, and the signal conversion circuit converts the target current signal into a target voltage signal, so that the signal processing system collects the target voltage signal , determining the quantity of the biological particles according to the voltage value of the target voltage signal.

Optionally, the fluorescence receiver is a photomultiplier tube or an enhanced photodiode.

Optionally, the signal conversion circuit includes an operational amplifier, a compensation capacitor and a gain resistor; wherein,

The output end of the fluorescence receiver is used as the signal input end of the signal conversion circuit, and the cathode of the fluorescence receiver, one end of the compensation capacitor and one end of the gain resistor are respectively coupled to form a first node;

The anode of the fluorescent receiver and the non-inverting input end of the operational amplifier are both grounded, and the other end of the compensation capacitor, the other end of the gain resistor and the output end of the operational amplifier are simultaneously coupled, and The coupling forms a second node, wherein the second node serves as a signal output terminal of the signal conversion circuit, so that a signal processing system is coupled with the signal output terminal to collect the target voltage signal.

Optionally, the signal conversion circuit further includes a filter unit coupled to the cathode of the fluorescence receiver, and the filter unit includes a filter resistor and a filter capacitor;

The filter resistor is connected in parallel with the fluorescence receiver, and the filter capacitor is coupled between the cathode of the fluorescence receiver and the negative phase output terminal of the operational amplifier.

Optionally, the filter resistor is a metal film resistor.

Optionally, the filter capacitor is a ceramic capacitor.

Optionally, the laser light source excites the biological particles in the air channel to generate scattered light and fluorescence, the fluorescent filter reflects the scattered light, and the fluorescent filter can be detected by the fluorescent light. through.

Optionally, the structure further includes a diffused light filter and a diffused receiver located in the air channel, and the diffused light filter and the laser light source are arranged opposite to each other on both sides of the air channel; wherein,

The laser light source excites the dust particles in the air channel to generate scattered light, and the scattered light filter can be transmitted by the scattered light;

The scattering receiver converts the scattered light passing through the scattered light filter into a scattered voltage signal, so that after the signal processing system collects the scattered voltage signal, it can determine the dust particle according to the voltage value of the scattered voltage signal quantity.

According to the second aspect of the present invention, the present invention provides an air filter device, which includes the air detection structure described in any one of the above.

According to the third aspect of the present invention, the present invention provides a ventilator, including the above-mentioned air filter device.

Compared with the prior art, the present invention includes an air channel for air circulation, a laser light source, a fluorescent filter, a fluorescent receiver and a signal conversion circuit, the laser light source, the fluorescent filter and the fluorescent receiver are located in the air channel, The fluorescence filter and the laser light source are arranged oppositely on both sides of the air flow channel. The laser light source can excite the biological particles in the air channel to generate scattered light and fluorescence, the fluorescent filter reflects the scattered light, and then the fluorescent filter can be transmitted by the fluorescent light. The fluorescence receiver converts the fluorescence passing through the fluorescence filter into a target current signal, and the signal conversion circuit converts the target current signal into a target voltage signal, so that after the signal processing system collects the target voltage signal, according to the voltage value of the target voltage signal Determine the number of bioparticles. As a result, the concentration and quantity of biological particles can be accurately measured, providing a scientific and rigorous basis for replacing filter devices, so that real-time monitoring of air quality can be carried out.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the specific embodiments of the present invention are enumerated below.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same components.

In the attached picture:

Fig. 1 is a structural schematic diagram of an air detection structure provided by an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a signal conversion circuit provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of another signal conversion circuit provided by an embodiment of the present invention;

Fig. 4 is a structural schematic diagram of another air detection structure provided by an embodiment of the present invention;

Fig. 5 is a schematic structural view of an air filter device provided by an embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a ventilator provided by an embodiment of the present invention.

Reference signs: 1. Air channel; 2. Laser light source; 3. Fluorescence filter; 4. Fluorescence receiver; 5. Signal conversion circuit; 501, operational amplifier; 502, compensation capacitor; 503, feedback gain resistor; 504. Filter resistor; 505. Filter capacitor; 6. Scattered light filter; 7. Scattering receiver; 8. Signal processing system; 9. Filter structure.

specific embodiment

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided for more thorough understanding of the present invention, and to fully convey the scope of the present invention to those skilled in the art.

Referring to Figures 1-4, an embodiment of the present invention provides an air detection structure, which may include an air channel 1 for air circulation, a laser light source 2, a fluorescence filter 3, a fluorescence receiver 4, and a signal conversion circuit 5. The laser light source 2 , the fluorescent filter 3 and the fluorescent receiver 4 are located in the air channel 1 , and the fluorescent filter 3 and the laser light source 2 are arranged opposite to each other on both sides of the air channel 1 . Wherein, the light source direction of the laser light source 2 faces the air channel 1 for irradiating the air flowing in the air channel 1 . The laser light source 2 excites the biological particles in the air channel 1 to generate scattered light and fluorescence. Specifically, when biological particles in the air pass through the area of the air channel 1 between the laser light source 2 and the fluorescent filter 3, the laser light source 2 is blocked to generate light pulses. The fluorescence filter 3 is used to separate scattered light and fluorescence. For example, the fluorescence filter 3 can reflect the scattered light, and the fluorescence filter 3 can be transmitted by the fluorescence. In one example, the fluorescent filter 3 may be a dichroic filter, and its reflectance to scattered light may be about 90%, and its transmittance to fluorescent light may be greater than 95%. Scattered light and fluorescence can be better separated.

After receiving the fluorescence transmitted through the fluorescence filter 3, the fluorescence receiver 4 converts the fluorescence into a target current signal, wherein the target current information is a pulse signal. Preferably, since the fluorescence signal of biological particles is relatively weak, the target current signal can be converted into a larger target voltage signal by the signal conversion circuit 5, wherein the target voltage information is also a pulse signal. The target voltage signal can be collected by the target voltage acquisition unit in the signal processing system 8, so that after the signal processing system 8 collects the target voltage signal, the number of the biological particles can be determined according to the voltage value of the target voltage signal. For example, the pulse voltage signal can be counted or counted within a unit time. As a result, the concentration and quantity of biological particles can be accurately measured. At the same time, the voltage threshold can be set accordingly. When the concentration and quantity of biological particles exceed the voltage threshold, it is determined that the biological indicators in the air in the current air flow channel 1 are in a state of exceeding the standard, and an audible and visual alarm can be issued to remind the user to replace the filter in time. Air filter structure9. The present invention provides a scientific and rigorous basis for replacing the filter structure 9, so that the air quality can be monitored in real time.

An optional embodiment of the invention, the fluorescence receiver 4 is a photomultiplier tube or an enhanced photodiode, and the fluorescence receiver 4 can convert extremely weak light signals into electrical signals, thereby increasing the concentration of biological particles And the calculation accuracy of the quantity optimizes the performance of the product.

An optional embodiment of the invention, referring to FIG. 2 , the signal conversion circuit 5 includes an operational amplifier 501, a compensation capacitor 502 and a gain resistor 503. The cathode of the fluorescence receiver 4 is used as the signal input terminal of the signal conversion circuit 5, and the cathode of the fluorescence receiver 4, one end of the compensation capacitor 502 and one end of the gain resistor 503 are respectively coupled to form a first node A . The anode of the fluorescent receiver 4 and the non-inverting input end of the operational amplifier 501 are both grounded, and the other end of the compensation capacitor 502, the other end of the gain resistor 503, and the output end of the operational amplifier 501 Coupled at the same time, and the coupling forms the second node B, wherein the second node B is used as the signal output end of the signal conversion circuit 5, so that the signal processing system 8 is coupled with the signal output end to perform the described Acquisition of the target voltage signal.

Wherein, the calculation formula of the voltage V0 at the output terminal of the operational amplifier 501 is as follows:

V ₀ = I _PMT × R _F formula (1)

Wherein, I _PMT is the cathode current of the fluorescence receiver 4, R _F is the gain resistor 503, and the gain resistor 503 is used to amplify the pulse current generated by the fluorescence receiver 4, and its resistance value is the corresponding amplification factor. Wherein, from the perspective of signal amplification, the larger the gain resistor 503 is, the larger the voltage signal generated by the second node B is. From the perspective of signal bandwidth, the smaller the gain resistor 503 is, the higher the pulse frequency generated by the second node B is. Therefore, the resistance value of the gain resistor 503 is limited according to the response of the compensation capacitor 502 and the operational amplifier 501 . In order to convert the weak target current signal into a larger voltage signal, the maximum resistance value corresponding to the gain resistor 503 can be determined based on the response limit of the compensation capacitor 502 and the response limit of the operational amplifier 501, and this maximum resistance value can be used as the gain resistor 503 value. In an example, the calculation formula of the response frequency f _F of the gain resistor 503 is as follows:

The calculation formula of the response frequency f _-3dB of the operational amplifier 501 is as follows:

Wherein, C _PMT is the parasitic capacitance in the fluorescence receiver 4 , and its capacitance is determined according to the device characteristics of the fluorescence receiver 4 ; C _S is the sum of the compensation capacitor 502 and the input capacitance in the operational amplifier 501 . The resistance value of the gain resistor 503 is determined by formula (3). Wherein, the value of the compensation capacitor 502 can be ignored. For example, when the signal frequency is more than 300 KHz, f _-3dB can be selected as 400KHz. When the amplifier GBW is 210MHz and Cs is 20pF, the gain resistance R _F is 10.4MΩ. Wherein, the compensation capacitor 502, the parasitic capacitance in the fluorescence receiver 4 and the input capacitance in the operational amplifier 501 jointly adjust the phase of the target voltage signal, and together with the gain resistor 503 form a low-pass filter circuit, the obtained formula (3) The response frequency is the cutoff frequency of the low-pass filter. It can improve the signal-to-noise ratio, thereby optimizing the product performance of the air detection structure.

An optional embodiment of the invention, referring to FIG. 3 , the signal conversion circuit 5 further includes a filter unit coupled to the cathode of the fluorescence receiver 4, the filter unit includes a filter resistor 504 and a filter capacitor 505, the filter The capacitor 505 is connected in series with the fluorescent receiver 4 , and the filter resistor 504 is connected in parallel with the fluorescent receiver 4 . Specifically, the filter resistor 504 is used to provide a static operating point for the fluorescence receiver 4. When weak background light is received by the fluorescence receiver 4, the DC voltage of the first node A will slowly rise, and the filter resistor 504 can slowly The increased DC voltage discharge ensures that the fluorescent receiver 4 has a stable static operating point. The filter capacitor 505 plays a role of isolating direct current, so that only pulse current signals generated by biological particles can pass through, which improves the signal-to-noise ratio. Therefore, the filter unit can eliminate the background noise, thereby making the pulse signal of the light pulse converted into the current pulse more obvious. It is beneficial to further improve the calculation accuracy of the concentration and quantity of biological particles.

The filter resistor 504 and the filter capacitor 505 constitute a high-pass filter circuit for the target current signal, and the corresponding lower limit frequency fx is calculated as follows:

Wherein, the R1 is a filter resistor 504, and the Cl is a filter capacitor 505. In a specific application scenario, the selection of the resistance value of the filter resistor 504 needs to be limited. When the resistance value of the filter resistor 504 is too large, even if the target current is very weak, the voltage across the filter resistor 504, the voltage across the filter capacitor 505, and The input voltage of the operational amplifier 501 will be too large, thus causing damage to the above-mentioned components. For example, the resistance value of the filter resistor 504 may be 1 MΩ. The capacitance of the filter capacitor 505 can be 10uF, and the corresponding lower limit frequency fx can be obtained as 0.016Hz according to formula (4).

In one example, the filter resistor 504 may be a metal film resistor, wherein the metal film resistor has a wide operating frequency range, is suitable for high-frequency circuits, and has a stable voltage and a small temperature coefficient, which can improve the target current signal Accuracy of collection. Thereby optimizing the product performance of the detection structure. In another example, the filter capacitor 505 is a ceramic capacitor, and the ceramic capacitor has a relatively wide temperature coefficient of capacitance, thereby ensuring the accuracy of target current signal acquisition on the basis of eliminating background noise.

An optional embodiment of the invention, the signal conversion circuit 5 may also include a voltage adjustment unit, the voltage adjustment unit includes a first adjustment resistor 506, a second adjustment resistor 507, a third adjustment resistor 508, a fourth adjustment resistor 509 and the fifth adjusting resistor 510, wherein the third adjusting resistor 508 and the fourth adjusting resistor 509 are adjustable resistors. One end of the first adjusting resistor 506 is connected to a positive power supply, one end of the second adjusting resistor 507 is connected to a negative power supply, the other end of the first adjusting resistor 506, the other end of the second adjusting resistor 507, and the third adjusting resistor One end of 508 and one end of the fourth adjusting resistor 509 are simultaneously coupled to form a third node C, and the adjusting end of the third adjusting resistor 508, the adjusting end of the fourth adjusting resistor 509 and a section of the fifth adjusting resistor 510 are simultaneously ANDed The non-inverting input terminal of the amplifier 501 is coupled to form a fourth node D. The other end of the third adjusting resistor 508 , the other end of the fourth adjusting resistor 509 and the other end of the fifth adjusting resistor 510 are all grounded. The operational amplifier 501 can be powered by positive and negative dual power supplies, and its linearity range is larger than that of the power supply. Wherein, the voltage adjustment unit provides a reference level for the operational amplifier 501 . The DC bias operating point of the operational amplifier 501 can be adjusted by adjusting the resistance values of the third adjusting resistor 508 and the fourth adjusting resistor 509 . In this way, the pulsed DC signal corresponding to the fluorescence can be collected more easily.

The voltage regulating unit may also include a regulating capacitor 511, one end of the regulating capacitor 511 is coupled to the fourth node D, and the other end is grounded, which can filter out noise on the positive power supply +VCC and the negative power supply -VCC to prevent power supply noise pollution Operational amplifier 501. In the present invention, a capacitor with the same effect as the adjustment capacitor 511 can also be added at other positions, and the corresponding coupling position is not limited, and can be selected according to specific conditions to create a clean circuit environment for the operational amplifier 501 .

In an optional embodiment of the invention, in addition to biological particles, the air generally also includes dust particles. The structure also includes a diffused light filter 6 and a diffused receiver 7 located in the air channel 1, and the diffused light filter 6 and the laser light source 2 are oppositely arranged on both sides of the air channel 1 . Wherein, the light source direction of the laser light source 2 faces the air channel 1 for irradiating the air flowing in the air channel 1 . The laser light source 2 excites the dust particles in the air channel 1 to generate scattered light. Specifically, when dust particles in the air pass through the area of the air channel 1 between the laser light source 2 and the scattered light filter 6, the laser light source 2 is blocked to generate scattered light, wherein the scattered light is in the form of light pulses. The scattered light filter 6 can be transmitted by the scattered light. The scattering receiver 7 converts the scattered light passing through the scattered light filter 6 into a scattered voltage signal, so that after the signal processing system 8 collects the scattered voltage signal, it determines the voltage value according to the voltage value of the scattered voltage signal. number of dust particles.

For example, the scattered voltage signals can be counted or counted within a unit time. As a result, the concentration and number of dust particles can be accurately metered. At the same time, the voltage threshold can be set accordingly. When the concentration and quantity of dust particles exceed the voltage threshold, it is determined that the dust index in the air in the current air flow channel 1 is in a state of exceeding the standard, and an audible and visual alarm can be issued to remind the user to replace the filter in time. Air filter structure9.

The invention can accurately measure the concentration and quantity of biological particles and dust particles in the air, provide scientific and rigorous basis for replacing the filter structure 9, and thus can monitor the air quality in real time.

Referring to FIG. 5 , the present invention provides an air filter device, which includes the air detection structure and filter structure 9 described in any one of the above.

The present invention provides an air filtering device, which includes the above-mentioned air filtering device. Wherein, the air filter equipment may include fresh air equipment, ventilator and other equipment. Referring to FIG. 6 , a schematic structural view of a ventilator is shown. Wherein, the ventilator includes a breathing device, and the breathing device includes an air inlet and an air outlet. In one example, the filter device can also be installed at the gas outlet of the user's exhaled air, and the filter device can be used to prevent biological particles such as bacteria exhaled by the user from contaminating the breathing device. When the filtration device fails or the filtration efficiency decreases, biological particles are immersed in the breathing device, breeding and spreading the pollution. Respiratory hazard when next used or by other users. Therefore, when the biological particles pass through the filter device and exceed the threshold, the user is reminded to replace it in time to ensure the safety of every breath.

In another example, the filter device may be installed at the air inlet for evaluating the filtration efficiency of the filter device at the air inlet. When the filtration efficiency of the filter device meets the filtration requirements, there are almost no or few biological particles and/or dust particles passing through the filter device in the input air. At this time, there is no light pulse signal for scattered light and fluorescence, which is manifested as a circuit in the electrical signal. background noise. When the filtration efficiency of the filter device decreases, the number of biological particles and/or dust particles passing through the filter device in the input air begins to increase, and the scattered light or fluorescent pulse signal increases, and the signal processing system 8 calculates that it exceeds the set threshold, indicating that the filter device is invalid. It is no longer possible to provide service and needs to be replaced in time.

In summary, the present invention includes an air channel 1 for air circulation, a laser light source 2, a fluorescent filter 3, a fluorescent receiver 4 and a signal conversion circuit 5, a laser light source 2, a fluorescent filter 3 and a fluorescent receiver 4 is located in the air channel 1, and the fluorescent filter 3 and the laser light source 2 are oppositely arranged on both sides of the air channel 1. The laser light source 2 can excite the biological particles in the air channel 1 to generate scattered light and fluorescence, the fluorescent filter 3 reflects the scattered light, and then the fluorescent filter 3 can be transmitted by the fluorescent light. The fluorescence receiver 4 converts the fluorescence passing through the fluorescence filter 3 into a target current signal, and the signal conversion circuit 5 converts the target current signal into a target voltage signal, so that after the signal processing system 8 collects the target voltage signal, according to the target voltage The voltage value of the signal determines the number of biological particles. As a result, the concentration and quantity of biological particles can be accurately measured, providing a scientific and rigorous basis for replacing filter devices, so that real-time monitoring of air quality can be carried out.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

It is easy for those skilled in the art to think that: any combination of the above-mentioned embodiments is feasible, so any combination of the above-mentioned embodiments is an embodiment of the present invention, but due to space limitations, this description will be limited here Not detailed one by one.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure the understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, in order to streamline the present disclosure and to facilitate an understanding of one or more of the various inventive aspects, various features of the invention are sometimes grouped together in a single embodiment, figure, or its description.

Furthermore, those skilled in the art will understand that although some embodiments described herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention. and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

Claims (10)

1. An air detection structure, characterized in that the structure includes an air channel (1) for air circulation, a laser light source (2), a fluorescence filter (3), a fluorescence receiver (4) and a signal conversion circuit ( 5), the laser light source (2), the fluorescence filter (3) and the fluorescence receiver (4) are located in the air channel (1), the fluorescence filter (3) and the laser light source (2 ) are relatively arranged on both sides of the air flow channel (1);

   The fluorescence receiver (4) converts the fluorescence passing through the fluorescence filter (3) into a target current signal, and the signal conversion circuit (5) converts the target current signal into a target voltage signal, so that After the signal processing system (8) collects the target voltage signal, it determines the quantity of the biological particles according to the voltage value of the target voltage signal.
2. The air detection structure according to claim 1, characterized in that the fluorescence receiver (4) is a photomultiplier tube or an enhanced photodiode.
3. The air detection structure according to claim 1 or 2, characterized in that, the signal conversion circuit (5) includes an operational amplifier (501), a compensation capacitor (502) and a gain resistor (503); wherein,

   The cathode of the fluorescence receiver (4) is used as the signal input end of the signal conversion circuit (5), the cathode of the fluorescence receiver (4), one end of the compensation capacitor (502) and the gain resistor (503) One ends of are respectively coupled to form a first node;

   The anode of the fluorescent receiver (4) and the non-inverting input end of the operational amplifier (501) are both grounded, and the other end of the compensation capacitor (502), the other end of the gain resistor (503) and The output terminals of the operational amplifier (501) are coupled simultaneously to form a second node, wherein the second node serves as the signal output terminal of the signal conversion circuit (5), so that the signal processing system (8 ) is coupled to the signal output terminal to collect the target voltage signal.
4. The air detection structure according to claim 1, 2 or 3, characterized in that, the signal conversion circuit (5) further comprises a filter unit coupled to the cathode of the fluorescence receiver (4), the filter unit Including a filter resistor (504) and a filter capacitor (505);

   The filter resistor (504) is connected in parallel with the fluorescent receiver (4), and the filter capacitor (505) is coupled between the cathode of the fluorescent receiver (4) and the negative phase output terminal of the operational amplifier (501) between.
5. The air detection structure according to claim 4, characterized in that the filter resistor (504) is a metal film resistor.
6. The air detection structure according to claim 4 or 5, characterized in that the filter capacitor (505) is a ceramic capacitor.
7. The air detection structure according to claim 1, characterized in that, the laser light source (2) excites the biological particles in the air channel (1) to generate scattered light and fluorescence, and the fluorescence filter (3) The scattered light is reflected, and the fluorescence filter (3) can be transmitted by the fluorescence.
8. The air detection structure according to any one of claims 1-7, characterized in that, the structure also includes a scattered light filter (6) and a scattered light receiver (7) located in the air channel (1) ), the scattered light filter (6) and the laser light source (2) are relatively arranged on both sides of the air flow channel (1); wherein,

   The laser light source (2) excites the dust particles in the air channel (1) to generate scattered light, and the scattered light filter (6) can be transmitted by the scattered light;

   The scattering receiver (7) converts the scattered light passing through the scattered light filter (6) into a scattering voltage signal, so that after the signal processing system (8) collects the scattering voltage signal, according to the scattering voltage The voltage value of the signal determines the number of said dust particles.
9. An air filter device, characterized in that the device comprises the air detection structure according to any one of claims 1-8.
10. A ventilator, characterized in that it comprises the air filter device described in claim 9.

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