Multispectral multichannel laser smoke detector

Abstract

The utility model discloses a multispectral multichannel laser smoke detector which comprises a smoke chamber, at least two laser emission units and a photoelectric detection channel. The number of the photoelectric detection channels is at least two; the laser emitting unit comprises a laser emitter and a light trap; the laser emission units and the light traps are arranged in a one-to-one correspondence manner; the photoelectric detector channel comprises a photoelectric detector and an optical amplifier; the optical amplifier is arranged at the front end of the photoelectric detector; a shading plate is arranged in the smoke chamber; the wavelengths of lasers emitted by different laser emitting units are different; during measurement, the photoelectric detectors in different channels can respectively receive scattering signals with different wavelengths emitted by different laser emitting units, so that multiple groups of aerosol scattering signal data with different parameters are acquired, and smog can be more accurately judged.

Description

Technical Field

[0001] The utility model relates to the technical field of laser smoke detectors, in particular to a multi-spectrum multi-channel laser smoke detector. Background Art

[0002] At present, fire smoke sensors generally have problems such as low sensitivity, strong interference from water vapor, dust, and oil smoke, and difficulty in identifying special categories such as black smoke. Taking the most widely used smoke sensor with LED as the light source as an example, due to the shortcomings of LED light sources such as large divergence angle, low signal-to-noise ratio, serious internal multipath interference, and susceptibility to environmental interference, single-wavelength single-channel and multi-wavelength multi-channel are the conventional modes. The former is more widely used, and the latter is used in small quantities, but both have low detection sensitivity and are not suitable for early fire detection; they are not universal enough, such as difficulty in identifying special categories such as black smoke; they do not have intelligent identification capabilities, poor anti-interference capabilities, and are easily interfered by water vapor, dust, oil smoke, etc.; they have poor environmental adaptability and are prone to false alarms and false alarms after long-term accumulation of dust and oil. Utility Model Content

[0003] In view of the low sensitivity and anti-interference performance of the current laser smoke detectors, the utility model provides a multi-spectrum multi-channel laser smoke detector, which can achieve the effect of improving the sensitivity and anti-interference performance of the smoke detector.

[0004] In order to achieve the above object, the embodiment of the utility model adopts the following technical solution:

[0005] A multi-spectral multi-channel laser smoke detector comprises a smoke chamber, a laser emitting unit and a photoelectric detection channel, wherein the number of the laser emitting units is at least two; the number of the photoelectric detection channels is at least two; the laser emitting unit comprises a laser emitter and a light trap; the laser emitting unit and the light trap are arranged in a one-to-one correspondence; the photoelectric detector channel comprises a photoelectric detector and an optical amplifier; the optical amplifier is arranged at the front end of the photoelectric detector; a plurality of shading plates are arranged inside the smoke chamber; the laser wavelengths emitted by different laser emitting units are different; during measurement, the laser emitted by the laser emitting unit is received by the optical amplifier after being scattered by the aerosol in the smoke chamber, and then converted into an electrical signal by the photoelectric detector.

[0006] According to one aspect of the utility model, the angle between the photoelectric detector and the laser beam emitted by the laser emitting unit is 30° to 60° or 120° to 170°.

[0007] According to one aspect of the utility model, the shading plate is arranged between the photoelectric detection channels; the shading plate and the smoke chamber are integrally formed.

[0008] According to one aspect of the utility model, the optical amplifier is an oblique-section cylindrical structure.

[0009] According to one aspect of the utility model, a reflective mirror is arranged inside the optical amplifier.

[0010] According to one aspect of the utility model, a focusing lens is arranged between the photodetector and the light magnifier.

[0011] According to one aspect of the utility model, a temperature sensor and a carbon monoxide sensor are arranged in the smoke chamber.

[0012] According to one aspect of the utility model, a light shield is provided on the smoke chamber.

[0013] According to one aspect of the utility model, the detector includes a shell; a dust filter is arranged on the shell.

[0014] Advantages of the utility model:

[0015] The detector described in the present application is provided with multiple groups of laser emitting units and multiple groups of photoelectric detection channels in the smoke chamber, which can detect the laser scattering signals of aerosols at different wavelengths and different detection angles, so as to more accurately judge the type of aerosol according to the aerosol scattering macroscopic model, and has a stronger ability to accurately distinguish fire aerosols, stronger anti-interference ability and higher sensitivity; a light trap is arranged in the smoke chamber to absorb excess laser and avoid the accumulation of dust and oil on the inner wall of the smoke chamber to introduce additional stray light, which can be suitable for cooking fire scenes and has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a schematic diagram of the structure of a multi-spectrum multi-channel laser smoke detector described in the utility model. Figure 1 ;

[0018] Figure 2 This is a schematic diagram of the structure of a multi-spectrum multi-channel laser smoke detector described in the utility model. Figure 2 .

[0019] Legend: 1. Smoke chamber; 11. Sunshade; 2. Laser emission unit; 21. Laser emitter; 22. Light trap; 3. Photoelectric detection channel; 31. Photoelectric detector; 32. Optical amplifier; 33. Focusing lens. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] like Figure 1 , Figure 2 As shown, a multi-spectral multi-channel laser smoke detector includes a smoke chamber 1, a laser emitting unit 2 and a photoelectric detection channel 3, wherein the number of the laser emitting units 2 is at least two; the number of the photoelectric detection channels 3 is at least two; the laser emitting unit 2 includes a laser emitter 21 and a light trap 22; the laser emitting unit 2 and the light trap 22 are arranged in a one-to-one correspondence; the photoelectric detector 31 channel includes a photoelectric detector 31 and an optical amplifier 32; the optical amplifier 32 is arranged at the front end of the photoelectric detector 31; a light shielding plate 11 is arranged inside the smoke chamber 1; the laser wavelengths emitted by different laser emitting units 2 are different;

[0022] During measurement, the laser emitted by the laser emitting unit 2 is scattered by the aerosol in the smoke chamber 1, received by the optical amplifier 32, and then converted into an electrical signal by the photodetector 31; the photodetectors 31 of different channels can respectively receive scattered signals of different wavelengths emitted by different laser emitting units 2, thereby collecting multiple groups of aerosol scattering signal data with different parameters, and the type of aerosol can be analyzed and determined based on these data, so as to better distinguish fire aerosols from non-fire aerosols, thereby determining whether there is a fire;

[0023] Theoretically, according to the macroscopic mathematical model of aerosol scattering, the more types of laser emission wavelengths, the more observation channels, the higher the measurement accuracy, and the stronger the detector's ability to identify aerosols. However, due to the balance between cost and performance, the number of emission units and detection channels will not increase indefinitely. The specific number of channels is selected according to the usage scenario and accuracy requirements. The laser emission wavelength should cover the range from ultraviolet to short-wave infrared as much as possible. The number of photoelectric detection channels3 is usually more than two, including at least one forward scattering observation channel (the typical forward observation angle is 120°~170°) and one backscattering observation channel (the backscattering observation angle is 30°~60°);

[0024] like Figure 2As shown, a solution is provided in this embodiment, the number of laser emitting units 2 is two, and the number of photoelectric detection channels 3 is two; wherein one wavelength of the laser emitting unit 2 selects the blue-violet band (wavelength 0.4-0.5um), and the other emitting unit selects the near-infrared band (wavelength 0.8-0.95um); the two laser emitting units 2 are arranged oppositely and crosswise; the two photoelectric detection channels 3 are symmetrically distributed with the midline of the connecting line of the two laser emitting units 2 as the axis, so that any photoelectric detection channel 3 can be used as a forward scattering observation channel of one of the laser emitting units 2 and a backscattering observation channel of the other laser emitting unit 2 at the same time;

[0025] A light trap 22 is arranged opposite to each laser emitting unit 2 to absorb excess laser beams and prevent multiple strong reflections of the laser from affecting the aerosol scattering signal. The interior of the light trap 22 is a rough, low-reflectivity surface and is provided with a protrusion structure. The laser beam is completely absorbed after multiple irregular reflections inside the light trap 22, thereby preventing the laser beam from re-entering the smoke chamber 1 and interfering with the detection. In this way, even after long-term use, the accumulation of dust and oil on the inner wall of the smoke chamber 1 will not introduce additional stray light noise.

[0026] Several shading plates 11 are arranged in the smoke chamber 1 to divide the interior of the smoke chamber 1 into several relatively independent spaces, mainly to eliminate the external ambient light from entering the smoke chamber 1 and interfering with the detection channel as much as possible, to avoid the stray light of the laser in the smoke chamber 1 from entering the detection channel as much as possible, and to reduce the mutual interference between different detection channels; Figure 2 As shown, the shading plate 11 is connected to the edge of the smoke chamber 1 and is disconnected at the center of the smoke chamber 1, i.e., the intersection of the laser beams. This reduces the influence of stray light on the detection results without affecting the reception of aerosol scattering signals by each detection channel. In practical applications, the shading plate 11 can be integrally formed with the smoke chamber 1, which can effectively reduce costs.

[0027] The optical amplifier 32 is arranged in front of the photodetector 31 to enhance the amplification of the laser scattering signal and improve the signal-to-noise ratio; the optical amplifier 32 is a beveled cylindrical structure, and the beveled method can increase the opening to ensure that the laser scattering signal is received to the greatest extent. The interior of the cylindrical structure is a smooth mirror design, and the scattered light signal is enhanced and amplified after multiple reflections on the inner wall of the mirror, and then received by the photodetector 31.

[0028] A focusing lens 33 is arranged between the photodetector 31 and the optical amplifier. The laser scattering signal is collected to the maximum extent by the inner wall of the optical amplifier 32, and after multiple reflections on the inner wall, the laser scattering light within a certain angle is collected by the focusing lens 33 and converted into an electrical signal by the photodetector 31.

[0029] According to actual needs, gas sensors such as temperature sensors and carbon monoxide sensors can also be integrated in the smoke chamber 1 to achieve multifunctional composite detection of smoke detection, fire temperature detection and fire gas detection, thereby improving integration.

[0030] The smoke chamber 1 is provided with a light shield which adopts an optical maze design and can greatly reduce the influence of the external background light on the interior of the smoke chamber 1 while not affecting the entry of smoke and ensuring that the smoke stays in the smoke chamber 1 for a sufficiently long time.

[0031] The outer layer of the light shield is the outer shell of the detector; a dust filter is provided on the outer shell to ensure ventilation, dust prevention and insect prevention.

[0032] Advantages of the utility model:

[0033] The detector described in the present application is provided with multiple groups of laser emitting units and multiple groups of photoelectric detection channels in the smoke chamber, which can detect the laser scattering signals of aerosols at different wavelengths and different detection angles, so as to more accurately judge the type of aerosol according to the aerosol scattering macroscopic model, and has a stronger ability to accurately distinguish fire aerosols, stronger anti-interference ability and higher sensitivity; a light trap is arranged in the smoke chamber to absorb excess laser and avoid the accumulation of dust and oil on the inner wall of the smoke chamber to introduce additional stray light, which can be suitable for cooking fire scenes and has a wider range of applications.

[0034] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the protection scope of the claims.

Claims

1. A multi-spectral multi-channel laser smoke detector, comprising a smoke chamber (1), a laser emitting unit (2) and a photoelectric detection channel (3), characterized in that: The number of the laser emitting units (2) is at least two; the number of the photoelectric detection channels (3) is at least two; the laser emitting unit (2) comprises a laser emitter (21) and a light trap (22); the laser emitting unit (2) and the light trap (22) are arranged in a one-to-one correspondence; the photoelectric detection channel (3) comprises a photoelectric detector (31) and a light amplifier (32); the light amplifier (32) is arranged at the front end of the photoelectric detector (31); a plurality of light shielding plates (11) are arranged inside the smoke chamber (1); the laser wavelengths emitted by different laser emitting units (2) are different; during measurement, the laser emitted by the laser emitting unit (2) is scattered by the aerosol in the smoke chamber (1) and then received by the light amplifier (32), and then converted into an electrical signal by the photoelectric detector (31).

2. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: The angle between the photoelectric detector (31) and the laser beam emitted by the laser emitting unit (2) is 30° to 60° or 120° to 170°.

3. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: The shading plate (11) is arranged between the photoelectric detection channels (3); the shading plate (11) and the smoke chamber (1) are integrally formed.

4. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: The optical amplifier (32) is an obliquely sectioned cylindrical structure.

5. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: A reflective mirror is arranged inside the optical amplifier (32).

6. The multi-spectral multi-channel laser smoke detector according to claim 1, characterized in that: A focusing lens (33) is arranged between the photoelectric detector (31) and the light magnifying lens.

7. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: A temperature sensor and a carbon monoxide sensor are arranged in the smoke chamber (1).

8. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: The smoke chamber (1) is provided with a light shield.

9. The multi-spectrum multi-channel laser smoke detector according to claim 1, characterized in that: The detector comprises a shell; a dustproof filter is arranged on the shell.

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