CN115206050B - Smoke alarm device - Google Patents
Smoke alarm device Download PDFInfo
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- CN115206050B CN115206050B CN202210829511.9A CN202210829511A CN115206050B CN 115206050 B CN115206050 B CN 115206050B CN 202210829511 A CN202210829511 A CN 202210829511A CN 115206050 B CN115206050 B CN 115206050B
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- analog
- smoke
- light
- control unit
- micro control
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Fire-Detection Mechanisms (AREA)
Abstract
The invention discloses a smoke alarm device which comprises an LED, a light transmission regulator, a photodiode and a smoke detection chip, wherein the smoke detection chip is used for adjusting the light intensity of the LED, adjusting the light transmittance of the light transmission regulator, detecting the current of the photodiode and logically controlling the whole device. In the smoke detection chip, a transimpedance amplifier, a band-pass filter, an integrator and an analog-to-digital converter jointly form an analog front end, and the optical loss in smoke is obtained according to the voltage level output by the conversion of the analog front end and is used as a smoke concentration determination value. When the device is in a strong illumination condition and the detection value of the analog-to-digital converter exceeds the upper limit of the threshold value, the micro control unit outputs a control signal to reduce the light transmittance of the light transmittance regulator; when the device is in a low illumination condition and the detection value of the analog-to-digital converter is lower than the lower threshold limit, the micro control unit outputs a control signal to increase the LED driving current, so that the influence of ambient light is eliminated.
Description
Technical Field
The invention relates to an alarm device, in particular to a smoke alarm device.
Background
With the rapid development of the internet of things technology, the security system is not an isolated monitoring system, but is an intelligent and networked intelligent system. Smoke detectors are widely used in the field of security and protection, and are also referred to as smoke-sensing fire detectors, smoke-sensing probes, and smoke-sensing sensors. The smoke detector is used as an important component of a security system, and has higher requirements on intelligence, reliability, accuracy and convenience.
For the existing photoelectric smoke detector, a light emitter and a light receiver are arranged inside the structure of the smoke detector. In a smokeless environment, there is a certain angular deviation between the emitter and the receiver, and the receiver will not receive the light source of the diffuser because the light is traveling straight. When a fire occurs, smoke particles enter the structure, the optical signals are scattered, and the receiver receives the optical signals sent by the scatterers and converts the optical signals into corresponding electrical signals. The electric signal is processed by an amplifier, an integrator and an algorithm, is compared with a preset value, and gives an alarm signal and drives a buzzer to alarm if the smoke alarm threshold value is exceeded.
However, the existing photoelectric smoke detector is limited by the detection mechanism, and has certain limitation in application, and the following problems are particularly existed:
1. the existing integrated smoke alarm device is easy to saturate under the influence of ambient light, so that smoke cannot be sensed and cannot be completely eliminated through the structure of the device;
2. the existing smoke concentration monitoring range is limited by the gain of a transconductance amplifier in a chip, and can not be adjusted in a wide range and a fine range;
3. the existing structure has larger volume due to the limitation of a detection mechanism.
Disclosure of Invention
The invention aims to: aiming at the prior art, a smoke alarm device is provided for eliminating the influence of ambient light.
The technical scheme is as follows: the smoke alarm device comprises an LED, a light transmission regulator, a photodiode and a smoke detection chip, wherein the smoke detection chip comprises an LED driver, a digital-to-analog converter, a transimpedance amplifier, a band-pass filter, an integrator, an analog-to-digital converter and a micro-control unit;
the light transmission regulator is arranged between the LED and the photodiode;
the signal input end of the LED driver is connected with the micro control unit, and the signal output end is connected with the LED;
the signal input end of the digital-to-analog converter is connected with the micro control unit, and the signal output end is connected with the light transmission regulator;
the photodiode, the transimpedance amplifier, the band-pass filter, the integrator and the analog-to-digital converter are sequentially connected, and the signal output end of the analog-to-digital converter is connected with the micro control unit;
the micro control unit obtains the light loss in the smoke according to the driving current output by the LED driver and the voltage output by the analog-to-digital converter, and the light loss is used as a smoke concentration judgment value;
when the smoke alarm device is in a strong illumination condition and the detection value of the analog-to-digital converter exceeds the upper limit of the threshold value, the micro control unit outputs a control signal to the digital-to-analog converter to reduce the light transmittance of the light transmittance regulator;
when the smoke alarm device is in a low-light condition and the detection value of the analog-to-digital converter is lower than the lower threshold value limit, the micro control unit outputs a control signal to increase the output current of the LED driver.
Further, the light transmission regulator comprises a first polaroid, a second polaroid and a linear motor, wherein the first polaroid and the second polaroid are coaxially and parallelly arranged, the linear motor is electrically connected with the digital-to-analog converter, and the linear motor is used for changing the polarization angle difference between the first polaroid and the second polaroid by adjusting the angle of the second polaroid, so that the light transmittance of the light transmission regulator is adjusted.
Further, the micro control unit adjusts the output current by adjusting the pulse width of the output current of the LED driver.
Further, the micro control unit outputs a control signal to the digital-to-analog converter to adjust the light transmittance of the light transmittance adjuster, and the rotation angle of the second polaroid around the axial direction is adjusted in a stepping manner.
Further, when the smoke alarm device is in a low-light condition and the detection value of the analog-to-digital converter is lower than the lower threshold limit, the pulse width is adjusted in a stepping mode.
The beneficial effects are that: 1. when the device works under different illumination conditions, the smoke detection working state can be adjusted in a self-adaptive mode;
2. the intermediate process light transmittance regulator can attenuate the interference light source to the greatest extent, and can completely eliminate the influence of the ambient light on smoke alarm;
3. the light transmittance regulator can linearly regulate the light transmittance, and has a large regulating range and high regulating precision;
4. the LED light-emitting path and the photodiode receiving path are arranged on the same straight line, which is more beneficial to saving the volume of the device.
Drawings
FIG. 1 is a schematic diagram of the structure of the device;
FIG. 2 is a schematic diagram of a light transmission regulator;
FIG. 3 is a schematic view of polarizer adjustment in a light transmission adjuster.
Detailed Description
The invention is further explained below with reference to the drawings.
As shown in fig. 1, a smoke alarm apparatus includes an LED101, a light transmission regulator 102, a photodiode 103, and a smoke detection chip. The light transmission regulator 102 is disposed between the LED101 and the photodiode 103, and the three are spaced apart by a certain physical distance, and the light emitting path of the LED101 and the receiving path of the photodiode 103 are positioned on a straight line.
The smoke detection chip is used for light intensity adjustment of the LED101, light transmittance adjustment of the light transmittance adjuster 102, current detection of the photodiode 103 and logic control of the whole device. The smoke detection chip comprises an LED driver 105, a digital-to-analog converter 106, a transimpedance amplifier (TIA) 107, a band-pass filter (BPF) 108, an integrator 109, an analog-to-digital converter (ADC) 110, a micro-control unit 111, an Input Output (IO) 112 and a memory 113.
The signal input end of the LED driver 105 is connected with the micro control unit 111, and the signal output end is connected with the LED101; the signal input end of the digital-to-analog converter 106 is connected with the micro control unit 111, and the signal output end is connected with the light transmission regulator 102; the photodiode 103, the transimpedance amplifier 107, the band-pass filter 108, the integrator 109 and the analog-to-digital converter 110 are sequentially connected, and a signal output end of the analog-to-digital converter 110 is connected with the micro control unit 111. Wherein, the transimpedance amplifier 107, the band-pass filter 108, the integrator 109, and the analog-to-digital converter 110 together form an analog front end.
The LED driver 105 provides LED101 drive current. The digital-to-analog converter 106 outputs a linear control voltage to adjust the light transmittance of the light transmittance adjuster 102. The transimpedance amplifier 107 is used to convert the current induced by the photodiode 103 into a voltage. The bandpass filter 108 is used to filter out direct current and high frequency interference. The integrator 109 is used to accumulate the voltage pulse beam to obtain an analog voltage value proportional to the light intensity. The analog-to-digital converter 110 is used to convert the converted analog voltage to a logic value. The micro control unit 111, the input/output port 112 and the memory 113 jointly control the functions of the whole device, the micro control unit 111 is used for calling or storing data, and the input/output port 112 is a chip and external connection interface.
The LED101, the light transmission regulator 102, and the photodiode 103 are located in a darkroom, and smoke can enter the darkroom. As shown in fig. 2, in the present embodiment, the light transmission regulator 102 includes a first polarizer 201, a second polarizer 202, and a linear motor 203, where the first polarizer 201 and the second polarizer 202 are coaxially and parallel arranged, the first polarizer 201 is fixedly arranged, and a control end of the linear motor 203 is connected to a signal output end of the digital-to-analog converter 106. The linear motor 203 is used to change the polarization angle difference between the first polarizer 201 and the second polarizer 202 by adjusting the rotation angle of the second polarizer 202 around the axial direction, thereby adjusting the light transmittance of the light transmittance adjuster 102. As shown in fig. 3, the transmittance of the light transmission regulator 102 is maximum when the polarization angle difference θ of the two polarizers is 0 °, and the transmittance of the light transmission regulator 102 is minimum when θ is 90 °, that is, the light transmission regulator 102 performs the light transmission regulation by the polarization angle of the two polarizers, thereby controlling the light transmission.
Let the driving current provided by the LED driver 105 be I; the gain of the LED101 to convert current into effective light intensity is a 1 The method comprises the steps of carrying out a first treatment on the surface of the The transmittance of the light transmission regulator 102 is A 2 (θ) is a function of the angle θ between the polarizers; the gain of the photodiode 103 converting light intensity into current is a 3 The method comprises the steps of carrying out a first treatment on the surface of the Gain of the analog front end converting current to voltage A 4 The method comprises the steps of carrying out a first treatment on the surface of the Let the loss of light passing through the smoke be ζ, the voltage to be converted by the final adc110 be V, to obtain v=i (a 1 A 2 (θ)A 3 A 4 (1- ζ)). For the present device, parameter A 1 、A 2 、A 3 、A 4 To quantify the determined parameters, the values of I and V are calculated logically to obtain the light loss zeta in smoke, which is used as smoke concentration judging value to judge the indoor smoke concentration, and the device transmits the smoke concentration to the outsidePolice information.
The device can adaptively adjust the working state of the whole device according to the application environment. When the device is in a normal illumination condition, the micro-control unit 111 controls the LED driver 105 to generate a pulse current with a default intensity to drive the LED101, the light generated by the LED101 irradiates the photodiode 103 through the light transmission regulator 102, the LED101 has a certain attenuation in the process of penetrating smoke in a darkroom, the photodiode 103 converts the light into a current, the current is converted into a corresponding binary number value through the transimpedance amplifier 107, the band-pass filter 108, the integrator 109 and the analog-to-digital converter 110, the smoke concentration is obtained through the operation processing of the micro-control unit 111, and finally the interaction with the outside is performed through the input/output port 112.
When the device is in a strong illumination condition, the micro control unit 111 controls the LED driver 105 to generate a current with a default intensity to drive the LED101, the light generated by the LED101 irradiates the photodiode 103 through the light transmission regulator 102, the transimpedance amplifier 107 is saturated due to the strong converted current, the detection value of the analog-to-digital converter 110 exceeds the upper threshold, and the logic part controls the digital-to-analog converter 106 to regulate the light transmission regulator 102 to reduce the light transmittance, so that the voltage value converted by the analog front end enters the detection range. When the device is in a low-light condition, the micro control unit 111 will first control the LED driver 105 to generate a current with a default intensity to drive the LED101, the light generated by the LED101 irradiates the photodiode 103 through the light transmission regulator 102, the voltage accumulated by the integrator 109 is too low due to the fact that the converted current flows through the light transmission regulator, finally the detection value of the analog-to-digital converter 110 is lower than the threshold lower limit, the logic part controls the current pulse width output by the LED driver 105 to increase, and finally the voltage obtained by the integrator 109 is increased, so that the voltage value converted by the analog front end enters the detection range.
The working process of the device is specifically as follows:
s1: powering up the device, and starting to establish a smoke detection alarm process;
s2: the logic control section controls the whole device initialization including resetting the memory 113 area, restoring the LED driver 105 current pulse width to a default value, and adjusting the light transmittance adjuster 102 to the highest light transmittance, that is, θ=0°;
s3: MCU111 controls the LED101 driver to start working;
s4: the LED101 is electrified and emits light source, the current is converted into effective light source, and a certain loss exists, and the obtained effective light intensity is set as IA 1 ；
S5: the light source passes through the smoke from the LED101 to the light transmission regulator 102 and then to the photodiode 103, and has a certain loss, namely zeta, when passing through the smoke, the light transmission of the light transmission regulator 102 is related to the polarizer theta, and finally the light intensity reaching the photodiode 103 is I A 1 A 2 (θ)(1-ζ)；
S6: photodiode 103 converts light intensity to a current gain of A 3 The current pulse obtained from the photodiode 103 is subjected to transconductance amplification by the TIA107, bandpass filtering by the BPF108, integration of the voltage pulse by the integrator 109, and the gain through the analog front end is set to a 4 The current I generated from the LED driver 105 is finally outputted to-be-converted voltage v=i (a via the integrator 109 1 A 2 (θ)A 3 A 4 (1-ζ))；
S7: the ADC110 converts the voltage V into a binary digital value D, and the D is transmitted to the MCU111 for processing;
s8: assuming that the threshold range of the ADC110 is (a, B), determining whether a < D < B is satisfied, if not, executing S9, and if so, executing S10;
s9: if D > B, the MCU111 controls the DAC106 to adjust the light transmission regulator 102, so that the second polarizer 202 in the light transmission regulator 102 rotates by a certain angle Δθ, the polarization angles of the first polarizer 201 and the second polarizer 202 increase by Δθ on the last angle, and then S3 is executed; if D < a, the MCU111 controls the current pulse outputted from the LED driver 105 to increase the current pulse width by Δt, and then performs S3;
s10: MCU111 calculates smoke concentration Z according to current I, voltage V obtained by conversion and current set parameter, and compares with normal smoke concentration range (0, Y);
s11: if the smoke concentration Z < Y, executing S2 after the system is delayed; if smoke concentration Z > Y, the system alarms to the outside smoke through IO button 112, ending this.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (5)
1. The smoke alarm device is characterized by comprising an LED (101), a light transmission regulator (102), a photodiode (103) and a smoke detection chip, wherein the smoke detection chip comprises an LED driver (105), a digital-to-analog converter (106), a transimpedance amplifier (107), a band-pass filter (108), an integrator (109), an analog-to-digital converter (110) and a micro control unit (111);
a light transmission regulator (102) is provided between the LED (101) and the photodiode (103);
the signal input end of the LED driver (105) is connected with the micro control unit (111), and the signal output end is connected with the LED (101);
the signal input end of the digital-to-analog converter (106) is connected with the micro control unit (111), and the signal output end is connected with the light transmission regulator (102);
the photodiode (103), the transimpedance amplifier (107), the band-pass filter (108), the integrator (109) and the analog-to-digital converter (110) are sequentially connected, and the signal output end of the analog-to-digital converter (110) is connected with the micro control unit (111);
the micro control unit (111) obtains the light loss in the smoke according to the driving current output by the LED driver (105) and the voltage output by the analog-to-digital converter (110), and the light loss is used as a smoke concentration determination value;
when the smoke alarm device is in a strong illumination condition and the detection value of the analog-to-digital converter (110) exceeds the upper threshold limit, the micro control unit (111) outputs a control signal to the digital-to-analog converter (106) to reduce the light transmittance of the light transmittance regulator (102);
when the smoke alarm device is in a low light condition, which causes the detection value of the analog-to-digital converter (110) to be lower than the lower threshold value, the micro control unit (111) outputs a control signal to increase the output current of the LED driver (105).
2. The smoke alarm device according to claim 1, wherein the light transmission regulator (102) comprises a first polarizer (201), a second polarizer (202) and a linear motor (203), the first polarizer (201) and the second polarizer (202) are coaxially arranged in parallel, the linear motor (203) is electrically connected to the digital-to-analog converter (106), and the linear motor (203) is configured to change the polarization angle difference between the first polarizer (201) and the second polarizer (202) by adjusting the angle of the second polarizer (202), so as to adjust the light transmission of the light transmission regulator (102).
3. The smoke alarm device according to claim 1, wherein said micro control unit (111) adjusts the output current magnitude by adjusting the pulse width of the output current of said LED driver (105).
4. The smoke alarm device according to claim 2, wherein said micro control unit (111) outputs a control signal to said digital-to-analog converter (106) to adjust the light transmittance of said light transmittance adjuster (102) by stepwise adjustment of the rotation angle of said second polarizing plate (202) around the axial direction.
5. A smoke alarm device according to claim 3, characterized in that the pulse width is stepwise adjusted when the smoke alarm device is in a low light condition resulting in a detection value of the analog to digital converter (110) below a lower threshold limit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210829511.9A CN115206050B (en) | 2022-07-15 | 2022-07-15 | Smoke alarm device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210829511.9A CN115206050B (en) | 2022-07-15 | 2022-07-15 | Smoke alarm device |
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| CN115206050A CN115206050A (en) | 2022-10-18 |
| CN115206050B true CN115206050B (en) | 2023-08-01 |
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| CN202210829511.9A Active CN115206050B (en) | 2022-07-15 | 2022-07-15 | Smoke alarm device |
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| CN2624305Y (en) * | 2003-03-28 | 2004-07-07 | 陈海明 | Laser smoke sensing detector |
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