WO2016197300A1

WO2016197300A1 - High-precision microminiaturized particle sensor

Info

Publication number: WO2016197300A1
Application number: PCT/CN2015/080969
Authority: WO
Inventors: 杜晨光; 戴震宇
Original assignee: 杜晨光
Priority date: 2015-06-08
Filing date: 2015-06-08
Publication date: 2016-12-15

Abstract

A high-precision microminiaturized particle sensor composed of a darkroom (1), a converging lens (2), a collecting lens (3), an infrared LED (4), an optical receiver (5), a diaphragm (6) and a circuit. The microminiaturized particle sensor can detect the density of particles in air with high precision, and the sensor, compared with traditional sensors, has the features of high precision, low costs, small volume, low power consumption, stability and reliability, acid and alkali corrosion resistance, anti-static performance and convenient use, and can be widely used for particle detection in various environments.

Description

A high precision miniature particle sensor

Technical field

The invention relates to a high precision miniaturized particle sensor.

Background technique

Atmospheric particulate matter is mainly derived from anthropogenic emissions, including the burning of three major fossil fuels, biomass, and direct emissions of road and building dust, industrial dust, and secondary particulate matter converted from gaseous pollutants discharged at one time. Atmospheric particulate matter can be suspended in the air for a long time, easy to carry toxic and harmful substances, and the transport distance is long, and the physiological structure of the human body determines the limited effect of filtering and blocking atmospheric particulate matter, so the atmospheric particulate matter has great influence on human health. .

Along with the rapid development of China's economy in recent years, people pay more and more attention to the quality of the surrounding living environment, especially the air quality, which promotes the rapid development of online monitoring technology for air quality. Light scattering method is the most commonly used method for on-line monitoring of air quality. Particle sensors developed by the principle of light scattering are common on the market. However, such sensors on the market have the following disadvantages: 1. The light emitted by the optical device passes through the sensor to measure the indoor wall. The multiple reflections form stray light, and the stray light enters the light receiver together with the light scattered by the particles, resulting in a low signal-to-noise ratio, large reading drift, and large deviation in measurement results. 2. Unreasonable system design, the light-emitting device is Working at a large current, resulting in a large power consumption; 3, the lens used for a long focal length, large diameter, resulting in a large overall sensor size; 4, the sensor circuit board is exposed outside, prone to moisture, corrosion, aging and other issues The sensor life is short and the performance is unstable. 5. The probe used by the sensor responds to visible light, so it is easily interfered by external light, resulting in inaccurate sensor reading.

Summary of the invention

In order to overcome the above drawbacks of the prior art, the present invention provides a highly accurate miniaturized particle sensor.

The technical solution adopted by the present invention to solve the above technical defects is as follows: a high-precision miniaturized particle sensor is composed of a dark room, a converging lens, a collecting lens, an infrared LED, a light receiver, an aperture, a circuit, and the particulate matter The sensor has a vent on at least one side for ambient air to enter the darkroom for measurement.

The converging lens, the collecting lens, the infrared LED, and the light receiver are all installed in a dark room, and the converging lens, the aperture, and the infrared LED form a transmitting system, and the aperture is located between the converging lens and the infrared LED, so that the infrared LED can be filtered out. The large angle of the exit light, so that the small angle of the exit light passes normally.

The collecting lens, the diaphragm and the light receiver constitute a detecting system, and the diaphragm is located between the collecting lens and the light receiver, so that the stray background light can be filtered out, and the signal light generated by the scattering can pass normally.

More preferably, the center of the pupil surrounds a space forming a cone, which makes the filtering effect best.

The launching system and the detecting system are respectively disposed on both sides of the vent hole.

The converging lens and the collecting lens all adopt short-focus, small-diameter lenses to realize miniaturization of the entire system.

The dark chamber is made of a material that absorbs light, which will help eliminate the interference of stray light and ensure the accuracy of the sensor reading.

The circuit includes a constant current drive module, an I-V conversion, an operational amplifier, and a connector. Under the control of the constant current driving module, the infrared LED emits stable infrared light, which is irradiated on the particles to generate scattered light. The scattered light is received by the light receiver and generates a current signal. The current signal is converted into a voltage signal through IV conversion, and then Operational amplification output.

More preferably, the photoreceiver is a phototransistor, which can have higher photoelectric conversion efficiency and cooperate with the detection system, so that the infrared LED works at a lower power, thereby achieving low power consumption of the entire module, and finally making the present The particle sensor of the invention has an operating current of less than 1 mA.

More preferably, the surface of the detecting head of the light receiver is a material capable of filtering visible light, which can effectively filter out interference of visible light and further enhance the accuracy of the sensor reading.

The surface of the dark room is covered with a shielding shell, and the circuit comprises a filter capacitor. The filter capacitor and the shielding shell can fully filter external interference, ensure the authenticity of the signal, and improve the signal to noise ratio.

The bottom surface of the darkroom has a straight mouth, the circuit is fixed in the installation space formed by the straight mouth of the bottom surface of the darkroom, and the circuit board is fixed on the bottom surface of the darkroom by a potting process, so that the circuit can be permanently fixed on the bottom surface of the darkroom. The space formed by the mouth, and the entire particle sensor will not have the bare board, enhance the physical properties of the sensor such as acid and alkali corrosion resistance, shock resistance, electrical insulation, etc., and also increase the overall aesthetic effect of the particle sensor.

With the above technical solution, the advantages of the present invention are:

1. High accuracy and high precision can effectively detect the content of particulate matter in the ambient air;

2, small size, easy to install and use;

3, low power consumption, working current can be reduced from the current 20mA of the particle sensor on the market to less than 1mA, can be used for portable products powered by micro batteries;

4, the appearance of the product has no exposed circuit, the overall effect is more beautiful;

5, moisture-proof, shock-proof, acid and alkali corrosion resistance, good insulation;

6. It is not sensitive to visible light, is not susceptible to natural light, and has strong anti-interference ability.

DRAWINGS

1 and 2 are schematic views of the overall structure of the present invention.

Figure 3 is a schematic diagram of the circuit of the present invention.

Main part label description:

1 darkroom 2 converging lens

3 collection lens 4 infrared LED

5 light receiver 6 light

7 vent 8 straight

9 circuit board

detailed description

For a more complete and clear disclosure of the present invention, the technical means and the technical effects of the present invention will be described in detail below.

A high-precision miniaturized particle sensor comprises: a darkroom 1, a converging lens 2, a collecting lens 3, an infrared LED 4, a light receiver 5, an aperture 6, and a circuit. The particulate sensor has a vent 7 on at least one side for ambient air to enter the darkroom 1 for measurement.

The concentrating lens 2, the collecting lens 3, the infrared LED 4, and the light receiver 5 are all installed in the darkroom 1. The converging lens 2, the aperture 6, and the infrared LED 4 constitute a transmitting system, and the aperture 6 is located at the converging lens 2 and the infrared LED 4. In this way, the large-angle outgoing light of the infrared LED 4 can be filtered out, so that the small-angle outgoing light passes normally. The collecting lens 3, the diaphragm 6, and the light receiver 5 constitute a detecting system, and the diaphragm 6 is located between the collecting lens 3 and the light receiver 5, so that the stray background light can be filtered out, and the signal light generated by the scattering can pass normally.

More preferably, the center of the diaphragm 6 surrounds a space forming a cone, which makes the above filtering effect best.

The transmitting system and the detecting system are respectively disposed on both sides of the vent hole 7.

Both the condenser lens 2 and the collecting lens 3 adopt short-focus, small-diameter lenses, so that the main physical structure of the dark room 1 and the aperture 6 can be greatly reduced, thereby achieving miniaturization of the entire system.

The darkroom 1 uses a material that absorbs light, which will help eliminate the interference of stray light and ensure the accuracy of the sensor readings.

The circuit comprises a constant current driving module, an I-V conversion, an operational amplifier and a connector. The infrared LED 4 emits stable infrared light under the control of the constant current driving module, and illuminates the particles to generate scattered light, and the scattered light is received by the light receiver 5 The current signal is received and generated, and the current signal is converted into a voltage signal by I-V conversion, and then amplified by an operation.

More preferably, the photoreceiver 5 selects a phototransistor, has a high photoelectric conversion efficiency, and cooperates with the detection system, so that the infrared LED 4 operates at a lower power, thereby achieving low power consumption of the entire module, and finally making the present The particle sensor of the invention has an operating current of less than 1 mA.

The surface of the darkroom 1 is covered with a shielding shell. The circuit includes a filter capacitor. The filter capacitor and the shielding shell can fully filter out external interference, ensure the authenticity of the signal, and improve the signal-to-noise ratio.

The bottom of the darkroom 1 has a straight mouth 8 , and the circuit is fixed in the installation space formed by the straight mouth 8 of the darkroom, and the circuit board 9 is fixed on the bottom surface of the darkroom by a potting process, so that the circuit can be permanently fixed to the bottom of the darkroom 8 In the space formed, and the entire sensor will not be exposed by the circuit board 9, which enhances the physical properties of the sensor such as acid and alkali corrosion resistance, shock resistance, electrical insulation, etc., and also increases the overall aesthetic effect of the sensor.

The surface of the probe of the light receiver 5 is a material capable of filtering out visible light, which can effectively filter out the interference of visible light and further enhance the accuracy of the sensor reading.

The invention utilizes the principle of optical detection, and the infrared LED 4 of the transmitting system emits infrared light, which is filtered by the aperture 6 in the emission system and focused by the converging lens 2, and the infrared light mainly concentrates on the ambient air at the vent hole 7 and is exposed to the environment. The scattering of particles in the air, the convergence of the scattered light by the collecting lens 3, the filtering of the stray light by the pupil 6 , the scattered light reaches the detecting head of the light receiver 5, and is converted into a weak electrical signal; the electrical signal passes through the subsequent circuit The amplification and filtering process obtains a voltage signal related to the particulate matter in the ambient air.

The above is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention, All should be included in the scope of this patent.

Claims

A high-precision miniaturized particle sensor, comprising: a darkroom, a converging lens, a collecting lens, an infrared LED, a light receiver, a diaphragm, a circuit, wherein the particulate sensor has a vent hole on at least one side thereof The collecting lens, the collecting lens, the infrared LED and the light receiver are all installed in the dark room, the collecting lens, the diaphragm and the infrared LED are combined to form a transmitting system, the collecting lens, the diaphragm, the light receiver are composed of the detecting system, the transmitting system and the detecting system. They are respectively arranged on both sides of the vent hole.
A high-precision miniaturized particle sensor according to claim 1, wherein the aperture of the transmitting system is located between the converging lens and the infrared LED, and filters out the large-angle outgoing light of the infrared LED, and is small. The angle exiting light passes normally, and the diaphragm of the detecting system is located between the collecting lens and the light receiver to filter out stray background light, and the signal light generated by the scattering passes normally.
A high-precision miniaturized particle sensor according to claim 1, wherein said converging lens and collecting lens each use a short focal length and a small aperture lens to achieve miniaturization of the entire system.
A high-precision miniaturized particle sensor according to claim 1, wherein said dark chamber is made of a material having high light absorbability.
A high-precision miniaturized particle sensor according to claim 1, wherein said circuit comprises a constant current driving module, an IV conversion, an operational amplifier and a connector, and the infrared LED is controlled by a constant current driving module. A stable infrared light is emitted, and the scattered light is generated on the particulate matter, and the scattered light is received by the optical receiver and generates a current signal, which is converted into a voltage signal by IV conversion, and then output and amplified.
A high-precision miniaturized particle sensor according to claim 1, wherein said dark chamber surface is covered with a shielding shell, said circuit comprising a filter capacitor, said filter capacitor and shield shell being Fully filter out external interference, ensure signal authenticity, and improve signal-to-noise ratio.
A high-precision miniaturized particle sensor according to claim 1, wherein said bottom surface of said darkroom has a straight mouth, said circuit is fixed in an installation space formed by a straight mouth on the bottom surface of the darkroom, and is potted by a potting. The process secures the board to the underside of the darkroom.
A high-precision miniaturized particle sensor according to claim 1 or 2, wherein said pupil center surrounds a space forming a taper.
A high-precision miniaturized particle sensor according to claim 1 or 2, wherein said photoreceiver is a photodetector, more preferably a phototransistor, and the surface of the probe is capable of filtering visible light. s material.