CN113514380A - High-precision smoke detection method and device - Google Patents
High-precision smoke detection method and device Download PDFInfo
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- CN113514380A CN113514380A CN202110760559.4A CN202110760559A CN113514380A CN 113514380 A CN113514380 A CN 113514380A CN 202110760559 A CN202110760559 A CN 202110760559A CN 113514380 A CN113514380 A CN 113514380A
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Abstract
The invention belongs to the technical field of photoelectric smoke detectors, and discloses a high-precision smoke detection method and device, wherein the device comprises a photoelectric smoke detector, the photoelectric smoke detector comprises a transmitting control circuit, a transmitting tube, a photosensitive receiving tube, a small signal amplifying circuit and an MCU (microprogrammed control Unit), and the MCU comprises an ADC (analog to digital converter); the method comprises the steps of putting the photoelectric smoke detector into a standard smoke concentration; the ADC acquires an output value of the small-signal amplification circuit, and the MCU adjusts the amplification gain of the small-signal amplification circuit to enable the output value of the small-signal amplification circuit to approach a preset alarm threshold value; completing the calibration of the photoelectric smoke detector, and recording an alarm threshold value and a gain adjustment value of a small signal amplifying circuit by the MCU; the photoelectric smoke detector is arranged in a workplace, and the gain value of the small signal amplifying circuit is set according to the parameters to detect smoke. The invention has the beneficial effects that: the gain difference of the amplifying circuit caused by the difference of components and assembly errors can be eliminated, and the detection precision of the photoelectric smoke detector is improved.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of photoelectric smoke detectors, in particular to a high-precision smoke detection method and device.
[ background of the invention ]
Currently, there are two main types of smoke detectors, an ion type smoke detector and a photoelectric type smoke detector. The ionic smoke detector has radioactivity, so that the application market is gradually reduced. The photoelectric smoke detector has the advantages of no radioactive pollution, small influence caused by wind current and environmental humidity change, low cost, high reliability and the like, so the trend that the photoelectric smoke detector replaces an ion smoke detector is more and more obvious. The photoelectric smoke detector needs to be calibrated (in a standard smoke box, a value corresponding to the ADC and collected under the standard smoke concentration is used as an alarm threshold value) so as to ensure that the photoelectric smoke detector alarms when the preset standard smoke concentration is reached.
In the existing calibration process, due to individual differences of components, such as different radiation intensities of transmitting tubes, different offset voltages of operational amplifiers, errors of resistance and capacitance and the like, the outputs of small signal amplifying circuits in standard smoke concentration are different, and the final result is that alarm thresholds are different, some are large and some are small. In order to ensure that all manufactured detector alarm thresholds fall within the output range of the circuit, the set value of the alarm threshold is often far lower than the output range of the circuit. The gain of the small-signal amplifying circuit is not fully utilized, and the detection precision of the detector is low due to the combination of the ADC (analog-to-digital conversion module) resolution of the MCU (microprocessor). Meanwhile, the alarm threshold is set to be low, so that when the ADC is interfered, the alarm threshold is easily reached by slight disturbance, and false alarm is generated.
Referring to fig. 1, a calibration process of a conventional photoelectric smoke detector is shown in the figure, which is caused by individual differences of components, such as different radiation intensities of emitting tubes, different offset voltages of operational amplifiers, and errors of resistance and capacitance, so that the detection accuracy of the photoelectric smoke detector is low. For example: in the standard smoke box, the standard smoke concentration is 0.120dB/m, and the full range of the ADC of the MCU is 3.3V. When the ADC is 10 bits, 1LBS ═ 0.003V, i.e., the ADC minimum resolvable voltage is 0.003V. At present, when two A, B photoelectric smoke detectors are provided, the output of the amplifying circuit of the small signal amplifying circuit is 0.5V when the air is cleaned; when the smoke concentration is standard, the output of the amplifying circuit of the small signal amplifying circuit of the machine A is 3.0V, and the output of the amplifying circuit of the small signal amplifying circuit of the machine B is 2.0V.
Setting: y is the standard smoke concentration;
v _ air is an output value of the small-signal amplifying circuit in the air cleaning process;
v _ click is an output value of the small signal amplifying circuit when the smoke concentration is standard;
1LBS is the minimum voltage that the ADC can resolve;
delta is the detector accuracy, i.e. the minimum smoke change value can be detected.
Then δ ═ y/((V _ look-V _ air)/1LBS)
A, detector precision: δ is 0.120dB/m/((3.0-0.5)/0.003) is 0.000144dB/m
B, detector precision: δ is y/((V _ looks-V _ air)/1LBS) is 0.120dB/m/((2.0-0.5)/0.003) is 0.000240 dB/m.
Therefore: the detection precision of the machine A is higher, the alarm threshold value of the machine A is 3.0V, the alarm threshold value of the machine B is 2.0V, the anti-interference capability of the machine A is stronger, and false alarm is not easy to generate.
Because the current situations such as component difference, assembly error and the like exist objectively, if the detection precision of the detector is improved in the aspects of reducing the component difference and the assembly error, the cost is high, and the method is not suitable for batch production. Therefore, it is necessary to provide a method and an apparatus for high-precision smoke detection, which can eliminate the gain difference of the amplifying circuit caused by the difference of components and assembly errors, improve the detection precision of the photoelectric smoke detector, enhance the consistency of products, do not need to specially select components, and are suitable for batch production.
[ summary of the invention ]
The invention discloses a high-precision smoke detection method and device, which can effectively solve the technical problems related to the background technology.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the utility model provides a high accuracy smog detecting device, includes photoelectric smoke detector, photoelectric smoke detector includes emission control circuit, transmitting tube, photosensitive receiving tube, small signal amplification circuit and MCU, MCU includes the ADC, MCU passes through emission control circuit control transmitting tube transmission infrared light signal, photosensitive receiving tube receives infrared light signal, and when smog, photosensitive receiving tube produces the photocurrent, and the photocurrent flows through passing after small signal amplification circuit enlargies the ADC, MCU basis small signal amplification circuit's output value with MCU's the difference of predetermineeing alarm threshold value is right small signal amplification circuit carries out gain adjustment.
As a preferred improvement of the present invention: the photoelectric smoke detector also comprises an alarm device, and the alarm device is connected with the MCU.
A method of high accuracy smoke detection, the method comprising the steps of:
s1, the MCU checks the calibration flag bit of the photoelectric smoke detector, judges whether the flag bit is 1, if not, executes step 2; if yes, go to step S8;
s2, lighting an uncalibrated indicator lamp;
s3, placing the photoelectric smoke detector into a standard smoke box, wherein smoke with standard concentration is arranged in the standard smoke box;
s4, detecting whether a start calibration signal is received, if so, executing a step S5; if not, go to step S2;
s5, the ADC of the MCU collects the output value of the small signal amplifying circuit, whether the output value is equal to a preset alarm threshold value or not is judged, and if yes, the step S6 is executed; if not, go to step S7;
s6, completing the calibration of the photoelectric smoke detector, recording an alarm threshold value and a gain adjustment value of a small signal amplifying circuit by the MCU, writing the alarm threshold value and the gain adjustment value into a memory, calibrating the flag bit of the photoelectric smoke detector to be 1, and executing the step S1;
s7, the MCU adjusts the gain value of the small signal amplifying circuit and executes the step S5;
s8, installing the photoelectric smoke detector in a workplace, reading in a gain parameter and an alarm threshold value by the MCU, and setting a gain value of the small-signal amplifying circuit according to the gain parameter;
s9, acquiring the AD value of the small signal amplification circuit through the MCU;
s10, judging whether the AD value is larger than the alarm threshold value, if so, executing a step S11; if not, go to step S9;
and S11, outputting an alarm.
As a preferred improvement of the present invention: the preset alarm threshold is set at a position close to the full scale of the ADC sampling.
The invention has the following beneficial effects:
when the photoelectric smoke detector is calibrated in standard smoke concentration, the gain value of the small signal amplifying circuit is automatically adjusted, so that the output value of the small signal amplifying circuit reaches a preset value (preset alarm threshold value) and corresponds to the preset alarm threshold value according to the standard smoke concentration. The gain difference of the small-signal amplifying circuit caused by the difference of components and assembly errors is eliminated in the calibration process, the detection precision of the photoelectric smoke detector is improved, the consistency of products is enhanced, components do not need to be specially selected, and the small-signal amplifying circuit is suitable for batch production.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:
FIG. 1 is a flow chart of a calibration of a conventional photoelectric smoke detector;
FIG. 2 is a block diagram of the circuit of the present invention;
FIG. 3 is a block diagram illustrating the process of the present invention.
[ detailed description ] embodiments
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 2, the present invention provides a high-precision smoke detection device, including a photoelectric smoke detector, where the photoelectric smoke detector includes a transmission control circuit, a transmitting tube, a photosensitive receiving tube, a small signal amplification circuit, and an MCU, where the MCU includes an ADC, the MCU controls the transmitting tube to transmit an infrared light signal through the transmission control circuit, the photosensitive receiving tube receives the infrared light signal, when smoke exists, the photosensitive receiving tube generates a photocurrent, which is amplified by the small signal amplification circuit and then transmitted to the ADC, and the MCU performs gain adjustment on the small signal amplification circuit according to a difference between an output value of the small signal amplification circuit and a preset alarm threshold of the MCU.
Specifically, the photoelectric smoke detector utilizes the scattering principle of smoke particles to light, the transmitting tube and the photosensitive receiving tube are arranged in the labyrinth, when no smoke particles exist in the labyrinth, ambient light outside the shell of the photoelectric smoke detector is blocked by the labyrinth and basically cannot enter the labyrinth, the photosensitive receiving tube can only receive background light formed by infrared light beams in a sensitive space through multiple reflections, and therefore no photocurrent is generated, and the circuit is in a normal monitoring working state. When smoke particles enter a sensitive space surrounded by the labyrinth, the smoke particles absorb incident light and emit light to the surrounding with the same wavelength, and after part of scattered light is received by the photosensitive receiving tube, the impedance of the light receiving element is changed to form photocurrent. And the photocurrent is amplified by the small signal amplifying circuit and then is sent to the ADC of the MCU. When the photocurrent is high to a certain degree and the value output by the small signal amplifying circuit reaches the MCU preset value (alarm threshold value), an alarm is generated.
Preferably, the photoelectric smoke detector further comprises an alarm device, and the alarm device is connected with the MCU.
Referring to fig. 3, the present invention provides a method for detecting smoke with high accuracy, which comprises the following steps:
s1, the MCU checks the calibration flag bit of the photoelectric smoke detector, judges whether the flag bit is 1, if not, executes step 2; if yes, go to step S8;
s2, lighting an uncalibrated indicator lamp;
s3, placing the photoelectric smoke detector into a standard smoke box, wherein smoke with standard concentration is arranged in the standard smoke box;
s4, detecting whether a start calibration signal is received, if so, executing a step S5; if not, go to step S2;
s5, the ADC of the MCU collects the output value of the small signal amplifying circuit, whether the output value is equal to a preset alarm threshold value or not is judged, and if yes, the step S6 is executed; if not, go to step S7;
s6, completing the calibration of the photoelectric smoke detector, recording an alarm threshold value and a gain adjustment value of a small signal amplifying circuit by the MCU, writing the alarm threshold value and the gain adjustment value into a memory, calibrating the flag bit of the photoelectric smoke detector to be 1, and executing the step S1;
s7, the MCU adjusts the gain value of the small signal amplifying circuit and executes the step S5;
s8, installing the photoelectric smoke detector in a workplace, reading in a gain parameter and an alarm threshold value by the MCU, and setting a gain value of the small-signal amplifying circuit according to the gain parameter;
s9, acquiring the AD value of the small signal amplification circuit through the MCU;
s10, judging whether the AD value is larger than the alarm threshold value, if so, executing a step S11; if not, go to step S9;
and S11, outputting an alarm.
Specifically, the photoelectric smoke detector is placed in the standard smoke concentration, the ADC collects the output value of the small-signal amplification circuit, and the MCU adjusts the amplification gain of the small-signal amplification circuit to enable the output value of the small-signal amplification circuit to be close to the preset alarm threshold value. And completing the calibration of the photoelectric smoke detector, and recording an alarm threshold value and a gain adjustment value of the small-signal amplifying circuit by the MCU. The photoelectric smoke detector is arranged in a workplace, and the gain value of the small signal amplifying circuit is set according to the parameters to detect smoke. When the invention is calibrated in standard smoke concentration, the gain of the small signal amplifying circuit is automatically adjusted, so that the circuit output reaches a preset value (preset alarm threshold). The standard smoke concentration is used for correspondingly presetting an alarm threshold value, and the gain difference of the amplifying circuit caused by the difference of components and assembly errors is eliminated in the calibration process. The detection precision of the photoelectric smoke detector is improved, the product consistency is enhanced, components do not need to be specially selected, and the photoelectric smoke detector is suitable for batch production.
Further, the preset alarm threshold is set at a position close to a full scale of the ADC sampling, for example, the full scale of the ADC sampling is 3.3V, and the MCU adjusts the gain of the small-signal amplifying circuit to output the small-signal amplifying circuit to about 3.0V.
The working principle is as follows: when the photoelectric smoke detector is calibrated in standard smoke concentration, the gain value of the small signal amplifying circuit is automatically adjusted, so that the output value of the small signal amplifying circuit reaches a preset value (preset alarm threshold value) and corresponds to the preset alarm threshold value according to the standard smoke concentration. The gain difference of the amplifying circuit caused by the difference of components and assembly errors is eliminated in the calibration process, so that the detection precision of the photoelectric smoke detector is improved, and the consistency of products is enhanced.
The comparison between the present invention and the conventional method is as follows:
1. according to the traditional method, the gain of the small-signal amplification circuit is fixed and unchanged; according to the invention, the gain of the small-signal amplifying circuit is adjustable.
2. In the traditional method, the MCU only collects the ADC data; according to the invention, the MCU collects the ADC data and has the function of adjusting the gain of the small-signal amplifying circuit.
3. According to the traditional method, when the photoelectric smoke detector is calibrated, only ADC data is collected, and the whole process is open-loop; according to the invention, when the photoelectric smoke detector is calibrated, the MCU collects the ADC data and forms a closed loop with the gain adjustment of the small signal amplifying circuit.
4. In the traditional method, in order to ensure the consistency of products, components need to be specially selected; according to the invention, a closed-loop mode is adopted, the gain difference of the small-signal amplifying circuit is eliminated, and components do not need to be specially selected.
5. According to the traditional method, the gain of the small-signal amplifying circuit is fixed, the output difference of the small-signal amplifying circuit is large due to the difference of components, and in order to ensure that the alarm threshold value falls within the output range of the small-signal amplifying circuit, the circuit gain value of the small-signal amplifying circuit is artificially reduced, so that the accuracy of the photoelectric smoke detector is lowered; according to the invention, a closed-loop mode is adopted, the gain difference of the small-signal amplifying circuit is eliminated, the designed preset alarm threshold value corresponds to the standard smoke concentration, the gain of the small-signal amplifying circuit can be utilized to the maximum extent, and the precision of the photoelectric smoke detector is improved.
While embodiments of the invention have been disclosed above, it is not limited to the applications set forth in the specification and the embodiments, which are fully applicable to various fields of endeavor for which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (4)
1. A high accuracy smoke detector, its characterized in that: including photoelectric smoke detector, photoelectric smoke detector includes transmission control circuit, transmitting tube, photosensitive receiving tube, small signal amplification circuit and MCU, MCU includes the ADC, MCU passes through transmission control circuit control the transmitting tube transmits infrared light signal, photosensitive receiving tube receives infrared light signal, and when smog, photosensitive receiving tube produces the photocurrent, and the photocurrent flows through transmit after small signal amplification circuit enlargies the ADC, MCU basis small signal amplification circuit's output value with MCU's the difference of predetermineeing alarm threshold value is right small signal amplification circuit carries out the gain control.
2. A high accuracy smoke detector apparatus according to claim 1 and further comprising: the photoelectric smoke detector also comprises an alarm device, and the alarm device is connected with the MCU.
3. A method of detecting a high accuracy smoke detector apparatus according to claim 1 or claim 2 and including the steps of:
s1, the MCU checks the calibration flag bit of the photoelectric smoke detector, judges whether the flag bit is 1, if not, executes step 2; if yes, go to step S8;
s2, lighting an uncalibrated indicator lamp;
s3, placing the photoelectric smoke detector into a standard smoke box, wherein smoke with standard concentration is arranged in the standard smoke box;
s4, detecting whether a start calibration signal is received, if so, executing a step S5; if not, go to step S2;
s5, the ADC of the MCU collects the output value of the small signal amplifying circuit, whether the output value is equal to a preset alarm threshold value or not is judged, and if yes, the step S6 is executed; if not, go to step S7;
s6, completing the calibration of the photoelectric smoke detector, recording an alarm threshold value and a gain adjustment value of a small signal amplifying circuit by the MCU, writing the alarm threshold value and the gain adjustment value into a memory, calibrating the flag bit of the photoelectric smoke detector to be 1, and executing the step S1;
s7, the MCU adjusts the gain value of the small signal amplifying circuit and executes the step S5;
s8, installing the photoelectric smoke detector in a workplace, reading in a gain parameter and an alarm threshold value by the MCU, and setting a gain value of the small-signal amplifying circuit according to the gain parameter;
s9, acquiring the AD value of the small signal amplification circuit through the MCU;
s10, judging whether the AD value is larger than the alarm threshold value, if so, executing a step S11; if not, go to step S9;
and S11, outputting an alarm.
4. A method of high accuracy smoke detection according to claim 3 and further comprising: the preset alarm threshold is set at a position close to the full scale of the ADC sampling.
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| CN202110760559.4A CN113514380A (en) | 2021-07-06 | 2021-07-06 | High-precision smoke detection method and device |
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-
2021
- 2021-07-06 CN CN202110760559.4A patent/CN113514380A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1281200A (en) * | 2000-03-13 | 2001-01-24 | 窦征 | Photoelectric smoke sensor and its sensitivity regulation method |
| CN101169362A (en) * | 2006-10-26 | 2008-04-30 | 上海贝岭股份有限公司 | Indoor fog detected and controlled integrated circuit |
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