Particle counter

Abstract

The utility model discloses a particle counter, comprising a gas chamber, a light source configured to emit a light beam into the gas chamber, a lens configured to collimate the light beam to form a strip-shaped light spot, the strip-shaped light spot passing through the gas chamber, an extinction portion arranged opposite to the light source, and the extinction portion configured to eliminate stray light in the gas chamber, sampling gas flowing into the gas chamber through a gas inlet nozzle, and the sampling gas flowing into the gas chamber through the gas inlet nozzle. The gas outlet nozzle and the gas inlet nozzle are arranged oppositely, gas in the gas chamber is discharged through the gas outlet nozzle, the photoelectric detector is arranged right opposite to the photosensitive area, the concave reflector is arranged in the gas chamber, and the concave reflector and the photoelectric detector are arranged on the two opposite sides of the photosensitive area. The shading part is arranged between the photosensitive area and the photoelectric detector, and the shading part is configured to prevent scattered light and direct light outside the photosensitive area from reaching the photoelectric detector, so that noise signals are reduced, the signal-to-noise ratio is increased, and the particle counting accuracy is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection, in particular to a particle counter. Background Art

[0002] Particle counters are precision instruments that use light scattering to measure the size and count of suspended particles of varying diameters in the air. They are widely used in clean technology. Their counting accuracy is closely related to the signal-to-noise ratio. Therefore, continuous optimization of the optical path structure is necessary to improve the instrument's signal-to-noise ratio and enhance detection accuracy.

[0003] An existing dust particle counter has been found to frequently generate interference signals from smaller particles (0.3 micron) when measuring larger particles (e.g., 0.5 micron). Research has revealed that this is due to direct and scattered light from particles outside the photosensitive area reaching the photodetector, causing interference signals and reducing particle counting accuracy.

[0004] The above information disclosed in this background technology is only used to increase the understanding of the background technology of this application. Therefore, it may contain information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0005] In view of the problems pointed out in the background technology, the utility model provides a particle counter which optimizes the optical path and improves the accuracy of particle counting.

[0006] In order to achieve the above-mentioned purpose of the utility model, the utility model adopts the following technical solutions:

[0007] In some embodiments, a particle counter is provided, comprising:

[0008] air chamber;

[0009] a light source configured to emit a light beam into the gas chamber;

[0010] a lens configured to collimate the light beam to form a strip-shaped light spot, wherein the strip-shaped light spot passes through the gas chamber;

[0011] a light extinction portion, disposed opposite to the light source, and configured to eliminate stray light in the air chamber;

[0012] An air inlet nozzle, through which the sampled gas flows into the air chamber, and the sampled gas flow flowing into the air chamber intersects the strip-shaped light spot perpendicularly to form a photosensitive area;

[0013] An air outlet nozzle is arranged opposite to the air inlet nozzle, and the gas in the air chamber is discharged through the air outlet nozzle;

[0014] A photoelectric detector is arranged facing the photosensitive area;

[0015] a concave reflecting mirror disposed in the air chamber, wherein the concave reflecting mirror and the photodetector are disposed on opposite sides of the photosensitive area;

[0016] The light shielding portion is disposed between the photosensitive area and the photodetector, and is configured to block scattered light and direct light outside the photosensitive area from reaching the photodetector.

[0017] In some embodiments, the light shielding portion is further configured to block direct light within the photosensitive area from reaching the photodetector.

[0018] In some embodiments, the light shielding portion is a flat, long strip structure.

[0019] In some embodiments, the length of the light shielding portion is greater than the length of the photodetector.

[0020] In some embodiments, the light shielding portion is black.

[0021] In some embodiments, the light source is a laser diode.

[0022] In some embodiments, the lens is an aspheric collimating lens.

[0023] In some embodiments, a portion of the air inlet nozzle is located in the air chamber, and the portion of the air inlet nozzle located in the air chamber is a flat nozzle.

[0024] In some embodiments, the inner wall of the matte portion is a tapered structure.

[0025] Compared with the prior art, the advantages and positive effects of the present invention are:

[0026] The particle counter disclosed herein is provided with a light shielding portion between the photosensitive area and the photodetector, which is used to block scattered light and direct light outside the photosensitive area, thereby preventing scattered light and direct light outside the photosensitive area from reaching the photodetector, thereby reducing noise signals, improving the signal-to-noise ratio, and thereby improving particle counting accuracy.

[0027] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 is a cross-sectional view of a particle counter according to some embodiments;

[0030] Figure 2 is another cross-sectional view of a particle counter according to some embodiments;

[0031] Figure 3 is another cross-sectional view of a particle counter according to some embodiments;

[0032] Figure 4 is a partial structural diagram of a particle counter according to some embodiments;

[0033] Reference numerals:

[0034] 01. Light source; 02. Lens; 03. Air chamber; 04. Concave reflector; 05. Photodetector; 06. Extinction part; 07. Light shielding part; 08. Photosensitive area; 09. Air inlet nozzle; 10. Air outlet nozzle. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0038] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0039] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0040] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art will recognize the application of other processes and / or the use of other materials.

[0041] In some embodiments, the present disclosure provides a particle counter that uses the principle of light scattering to measure the size and number of suspended particles in the air.

[0042] Reference Figures 1 to 4 The particle counter includes an air chamber 03. The air chamber 03 is a closed cavity that provides a detection space. For example, the outer contour of the air chamber 03 is roughly rectangular, which is convenient for installing other components.

[0043] The particle counter includes a light source 01 . The light source 01 is disposed on a first side of a gas chamber 03 . The light source 01 is configured to emit a light beam into the gas chamber 03 .

[0044] The particle counter includes a lens 02 configured to collimate the light beam to form a strip-shaped light spot, which passes through the gas chamber 03.

[0045] The particle counter includes a light extinction unit 06 . Light extinction unit 06 is disposed on the second side of gas chamber 03 , opposite to light source 01 . The first side and the second side of gas chamber 03 are disposed opposite to each other. Light extinction unit 06 is configured to eliminate stray light within gas chamber 03 .

[0046] The particle counter includes an air inlet nozzle 09 . The air inlet nozzle 09 is disposed on the third side of the air chamber 03 . The sampling gas flows into the air chamber 03 through the air inlet nozzle 09 . The sampling gas flowing into the air chamber 03 intersects the strip-shaped light spot perpendicularly to form a photosensitive area 08 .

[0047] The particle counter includes an air outlet nozzle 10. The air outlet nozzle 10 is disposed on the fourth side of the air chamber 03. The third side and the fourth side of the air chamber 03 are disposed opposite each other. The air outlet nozzle 10 is disposed opposite the air inlet nozzle 09, and the gas in the air chamber 03 is discharged through the air outlet nozzle 10.

[0048] The particle counter includes a photodetector 05. This detector is located on the fifth side of the gas chamber 03, facing the photosensitive region 08. Its detection surface faces the photosensitive region 08. The photodetector 05 has a fast response, capable of receiving particle size signals and converting them into electrical signals, facilitating subsequent electrical signal processing to obtain a complete particle size signal.

[0049] The particle counter includes a concave reflector 04. Concave reflector 04 is disposed within gas chamber 03. Concave reflector 04 and photodetector 05 are disposed on opposite sides of photosensitive region 08. The reflective surface of concave reflector 04 faces photosensitive region 08, enabling efficient collection of scattered light signals.

[0050] The particle counter includes a light shield 07. The light shield 07 is disposed between the photosensitive region 08 and the photodetector 05. The light shield 07 is configured to block scattered light and direct light outside the photosensitive region 08 from reaching the photodetector 05, thereby reducing noise signals, improving the signal-to-noise ratio, and thereby improving particle counting accuracy.

[0051] The design principle of this disclosure is that scattered light from particles directly sprayed from the air inlet nozzle 09 onto the photosensitive area 08 is the desired detection target, while scattered light from particles scattered elsewhere within the air chamber 03 is not. If detected, these signals become interference signals, reducing particle counting accuracy. Therefore, direct and scattered light emitted by particles outside the photosensitive area 08 become interference signals, disrupting the count. Because these light rays are not reflected by the reflector, the signal is small. Weak signals correspond to small particles, which in turn add additional weak interference signals when counting small particles, thereby reducing the accuracy of small particle counts. For example, in actual experiments, it was found that when measuring large particles (e.g., 0.5 micron), interference signals from small particles (0.3 micron) often appeared. Research has revealed that this is because direct and scattered light from particles outside the photosensitive area 08 reaches the photodetector 05, causing interference signals and reducing particle counting accuracy.

[0052] Based on the above analysis, the present disclosure sets a light shielding portion 07 between the photosensitive area 08 and the photodetector 05, and uses the light shielding portion 07 to block the scattered light and direct light outside the photosensitive area 08, thereby preventing the scattered light and direct light outside the photosensitive area 08 from reaching the photodetector 05, thereby reducing noise signals, improving the signal-to-noise ratio, and thereby improving the accuracy of particle counting.

[0053] In some embodiments, the light shielding portion 07 is further configured to block direct light within the photosensitive region 08 from reaching the photodetector 05 .

[0054] One function of light shield 07 is to block scattered light and direct light outside photosensitive region 08 from reaching photodetector 05. Another function of light shield 07 is to block direct light within photosensitive region 08 from reaching photodetector 05. This reduces the amount of scattered light within photosensitive region 08 that reaches photodetector 05, reducing noise, improving the signal-to-noise ratio, and ultimately enhancing particle counting accuracy.

[0055] In some embodiments, the shading portion 07 is a flat, long strip structure, which improves the shading effect and facilitates installation in the air chamber 03 with limited space.

[0056] In some embodiments, the length of the light shielding portion 07 is greater than that of the photodetector 05 , which can effectively block direct light signals from particles in the photosensitive area 08 and the non-photosensitive area 08 , reduce noise signals, and improve the signal-to-noise ratio.

[0057] In some embodiments, the shading portion 07 is black to improve the shading effect.

[0058] In some embodiments, the light source 01 is a laser diode, which is low in cost.

[0059] In some embodiments, the lens 02 is an aspheric collimating lens 02 .

[0060] In some embodiments, a portion of the air inlet nozzle 09 is located in the air chamber 03 , and the portion of the air inlet nozzle 09 located in the air chamber 03 is a flat nozzle.

[0061] In some embodiments, the inner wall of the matte portion 06 is a tapered structure, and the inner wall of the matte portion 06 is smooth, which reduces diffuse reflection and improves the matte effect.

[0062] In some embodiments, the particle counter operates as follows:

[0063] Light source 01, such as a laser diode, reflects an elliptical light spot. By using an aspheric collimating lens 02 and adjusting its position, the laser beam can be collimated and shaped into a stripe-shaped light spot. The energy of the stripe-shaped light spot is focused into a thin line in the photosensitive area 08, resulting in a light spot with high energy density.

[0064] When particles of different sizes pass through the light spot, they will generate relatively stray Mie scattered light and produce more interference signals;

[0065] By providing a light shielding portion 07 between the photosensitive region 08 and the photodetector 05, the scattered light and direct light outside the photosensitive region 08 are effectively blocked from reaching the photodetector 05, and the direct light within the photosensitive region 08 is blocked from reaching the photodetector 05, thereby improving the signal-to-noise ratio. Figure 4 In the figure, the four dotted arrows represent the reflected light within the photosensitive area 08, and the two solid arrows represent the direct light within the photosensitive area 08;

[0066] The concave reflector 04 collects the stray light and transmits it to the photodetector 05, generating different current signals. By converting them into voltage signals, the circuit performs signal amplification processing to obtain information such as particle size and particle number.

[0067] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0068] The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited to them. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this utility model should be included in the scope of protection of the present utility model. Therefore, the scope of protection of the present utility model should be based on the scope of protection of the claims.

Claims

1. A particle counter, characterized in that include: air chamber; a light source configured to emit a light beam into the gas chamber; a lens configured to collimate the light beam to form a strip-shaped light spot, wherein the strip-shaped light spot passes through the gas chamber; a light extinction portion, disposed opposite to the light source, and configured to eliminate stray light in the air chamber; An air inlet nozzle, through which the sampled gas flows into the air chamber, and the sampled gas flow flowing into the air chamber intersects the strip-shaped light spot perpendicularly to form a photosensitive area; An air outlet nozzle is arranged opposite to the air inlet nozzle, and the gas in the air chamber is discharged through the air outlet nozzle; A photoelectric detector is arranged facing the photosensitive area; a concave reflecting mirror disposed in the air chamber, wherein the concave reflecting mirror and the photodetector are disposed on opposite sides of the photosensitive area; The light shielding portion is disposed between the photosensitive area and the photodetector, and is configured to block scattered light and direct light outside the photosensitive area from reaching the photodetector.

2. The particle counter according to claim 1, characterized in that The light shielding portion is further configured to block direct light within the photosensitive area from reaching the photodetector.

3. The particle counter according to claim 1 or 2, characterized in that The light shielding portion is a flat long strip structure.

4. The particle counter according to claim 3, characterized in that The length of the light shielding portion is greater than the length of the photodetector.

5. The particle counter according to claim 3, characterized in that The light shielding portion is black.

6. The particle counter according to claim 1 or 2, characterized in that The light source is a laser diode.

7. The particle counter according to claim 1 or 2, characterized in that The lens is an aspheric collimating lens.

8. The particle counter according to claim 1 or 2, characterized in that A portion of the air inlet nozzle is located in the air chamber, and the portion of the air inlet nozzle located in the air chamber is a flat nozzle.

9. The particle counter according to claim 1 or 2, characterized in that The inner wall of the matte portion is a tapered structure.

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