JP3783991B2 - Smoke detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a smoke detection device that optically detects smoke particles floating in air sucked from a monitoring area using a laser beam to determine a fire.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an ultrasensitive smoke detection device has been used to detect a fire that occurs in a clean space represented by a clean room such as a computer room or a semiconductor manufacturing facility at an extremely early stage.
This ultra-sensitive smoke detection device sucks air from a pipe installed in a clean space, passes smoke particles contained in the sucked air through a smoke detection area irradiated with a laser diode, and detects smoke particles detected by a light receiving element. The number of received light pulse signals exceeding a predetermined threshold among the received light pulse signals due to the scattered light is counted per unit time, and 0.05 to 0.20% / m based on the counted number per unit time A weak smoke density in the range is detected.
[0003]
In this way, in the ultra-sensitive smoke sensing device that detects the smoke density by the pulse count of the light reception pulse signal, the number of scattered light counts per unit time changes due to the change in the flow rate of the sucked air, There is a problem that accurate smoke concentration cannot be detected. In order to solve this problem, the conventional apparatus measures the flow rate of air sucked by a flow meter, obtains a correction coefficient from the set flow rate and the detected flow rate, and corrects the count number per unit time.
[0004]
That is, when the actual detected flow rate Q increases with respect to the set flow rate Qr, the number of counts per unit time increases and the smoke density increases, so the correction coefficient K = Qr / Q is obtained, The correct smoke concentration can be detected by correcting the count value converted to the set flow rate Qr by multiplying the count value per unit time.
However, in order to correct the number of counts per unit time due to the change in the flow rate of the suction air, a flow meter is required, and the apparatus cost is considerably increased. There is also a problem that the smoke concentration cannot be accurately detected when a malfunction occurs in the flow meter.
[0005]
Therefore, the inventor of the present application does not need to measure the flow rate of the intake air, and can detect the smoke concentration based on the scattered light accurately even if the flow rate of the intake air changes. The integration unit per unit time, that is, the waveform area is obtained by integrating the received light pulse signal from the light receiving unit exceeding a certain threshold value, and the smoke density detection unit detects the smoke density based on the integration amount. (Japanese Patent Application No. 9-173968).
[0006]
[Problems to be solved by the invention]
However, in the smoke detection device that converts the smoke concentration to the smoke concentration based on the integrated value of the received pulse signal of scattered light per unit time, even if the smoke concentration is the same, the particle size of the smoke depends on the type of combustion product. Since there is a difference in distribution, there is a difference in the amount of integration per unit time. For example, in the case of smoke containing many smoke particles having a small particle diameter, the amount of scattered light of the smoke particles having a small particle diameter is weak and the integral amount of the received light pulse signal is small. On the other hand, in the case of smoke containing many smoke particles having a large particle diameter, the amount of scattered light of the smoke particles having a large particle diameter is strong, and the integral amount of the received light pulse signal is large.
[0007]
For this reason, a difference in the amount of integration per unit time due to a difference in the distribution of the smoke particle system may occur, and the detection accuracy of the smoke concentration may be lowered.
The present invention has been made in view of such problems, and even if there is a difference in the particle size distribution depending on the type of smoke, it is possible to accurately detect the smoke concentration based on the integrated amount without being affected by the difference. It is an object of the present invention to provide a smoke detection device.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the present invention is configured as follows. First, according to the present invention, a light projecting unit that irradiates a smoke detection region through which intake air passes laser light emitted from a laser diode, and a light receiving element that receives a scattered light pulse generated every time smoke particles pass through the smoke detection region. A light receiving unit that outputs a light reception pulse signal, an integration unit that integrates the light reception pulse signal from the light reception unit to obtain an integration amount per unit time, and a smoke density based on the integration amount per unit time of the integration unit. The present invention is directed to a smoke sensing device that includes a smoke concentration detection unit that detects smoke and optically detects smoke particles floating in the air sucked from a monitoring area to determine a fire.
[0009]
For such a smoke sensing device, the present invention sets a plurality of threshold values for the received light pulse signal received by the light receiving unit, and determines a threshold value corresponding to the peak value of the received light pulse signal, and a threshold value determining unit When the determination threshold value is less than or equal to a predetermined value, there is provided a peak value correction unit that corrects the peak value of the received light pulse signal corresponding to the determination threshold value to a larger peak value and integrates the peak value.
[0010]
According to the inventor's consideration, the distribution of the peak values obtained from the received pulse signal of the scattered light of the smoke particles for smoke containing a large amount of smoke particles having a large particle size and smoke containing many smoke particles having a small particle size. When both are measured, the distribution of the regions with small peak values is concentrated in both cases. Therefore, the present invention corrects the peak value of the scattering pulse signal of the smoke particles concentrated in the region where the peak value is small, thereby suppressing the error of the integral amount due to the difference in the smoke particle diameter distribution, and the type of smoke. It makes it possible to detect smoke density more accurately.
[0011]
In an actual apparatus configuration, the received light pulse signal is converted into digital data and processed. For this reason, the threshold determination unit inputs the conversion data from the A / D converter that samples the light reception pulse signal and converts it into n-bit light reception data having a predetermined peak value resolution ΔV per bit. It is determined whether or not the conversion data of the converter is light reception data having bit 1 in any of the predetermined lower m bits.
[0012]
In this case, when the threshold value determination unit determines the light reception data having bit 1 in any of the lower m bits, the peak value correction unit corrects the light reception data to predetermined k bits larger than the lower m bits.
For example, the threshold value determination unit determines whether the conversion data converted by the A / D converter is light reception data having bit 1 in any of the lower 2 bits, and the peak value correction unit determines which of the lower 2 bits in the threshold value determination unit. When the received light data having the bit 1 is determined, the 5 bits are corrected to the received light data with all 1 bits.
[0013]
That is, the peak value correcting unit corrects each received light data to 5-bit received light data “11111” when the threshold determining unit determines the 2-bit received light data “01” or “10”.
As another example, the threshold value determination unit determines whether the converted data converted by the A / D converter is light reception data having bit 1 in any of the lower 2 bits, and the peak value correction unit is the threshold value determination unit. When light reception data having bit 1 in any one of the lower 2 bits is determined, 4 bits are corrected to light reception data with all 1 bits. That is, the peak value correcting unit corrects each received light data to 4-bit received light data “1111” when the threshold determining unit determines the 2-bit received light data “01” or “10”.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall configuration diagram of the smoke sensing device of the present invention. In FIG. 1, a smoke detection device 1 is installed in a clean room such as a computer room or a semiconductor manufacturing facility to detect smoke due to a fire at an extremely early stage, and is installed in a monitoring area in the smoke detection device 1. The detection pipe 2 is connected. The detection pipe 2 is, for example, a T-shaped pipe and includes a plurality of suction holes 3.
[0015]
A detection pipe 2 is connected to an inlet of the smoke detection unit 4 provided in the smoke detection device 1, and an outlet side is opened in a chamber provided with a suction device 7. In the monitoring state, the suction device 7 sucks air at a predetermined flow rate set in advance by driving the motor. For this reason, the air sucked from the suction hole 3 of the detection pipe 2 installed in the warning area passes through the smoke detector 4. It is discharged from the suction device 7 through.
[0016]
The suction flow rate of the suction air by the suction device 7 is determined to be a predetermined value by design, but the actual flow rate varies with the set flow rate due to fluctuations in the rotation of the motor and so on. The passage speed of the smoke particles contained in the air passing through the smoke part 4 also varies.
The smoke detector 4 is provided with a laser diode (LD) 5 and a photodiode (PD) 6 as a light receiving element. As the photodiode 6, for example, a PIN photodiode is used.
[0017]
Detection of airborne particles (aerosol) including smoke particles present in the sucked air passing through the smoke detector 4 is performed by detecting scattered light by irradiation of laser light from the laser diode 5 with the photodiode 6. A light reception pulse signal corresponding to the above is output to the signal processing unit 8 to perform signal processing for smoke density detection. In the signal processing unit 8 of the present invention, the smoke density is detected based on the integral value of the received light pulse signal obtained per unit time as signal processing for detecting the smoke density based on the received light pulse signal. .
[0018]
FIG. 2 is an explanatory diagram of a scattered light type smoke particle detection structure provided in the smoke detector 4 of FIG. In FIG. 2, the laser diode 5 performs so-called single deflection oscillation in which the electrolysis direction of the emitted laser light is determined in a predetermined direction, and includes a laser diode chip 5a therein. The laser light emitted from the laser diode 5 spreads as a diffusion wave toward the light projecting optical axis 11.
[0019]
Following the laser diode 5, an imaging lens 9 is installed, and a light source image of the laser diode 5, that is, a light source image of the emission surface of the laser diode chip 5a (near field) is passed through the imaging position 10 through which the inhaled air stream 13 passes. Pattern) is formed to form a minute spot area of about 1 μm.
For the imaging position 10 of the light source image of the laser diode 5 by the imaging lens 9, a light receiving optical axis 12 is set on the light projecting optical axis 11 in a direction orthogonal to, for example, θ = 90 °, and the photodiode 6 is installed. The arrangement direction of the photodiode 6 is parallel to the direction of the electric field E indicated by an arrow in an elliptical pattern (far field pattern) 14 indicating the light intensity distribution in the optical axis cross-sectional direction of the laser light diffused past the imaging position 10, for example. Arranged in the direction.
[0020]
By disposing the photodiode 6 in a direction parallel to the direction of the electric field E in this way, it is possible to receive the scattered light from the smoke particles passing through the minute spot at the imaging position 10 with the highest efficiency.
FIG. 3 is a block diagram of the signal processing unit of FIG. The signal processing unit 8 is provided with a control unit 15. The laser diode 5 is connected to the control unit 15 through the light projecting circuit unit 16, and the output of the photodiode 6 is input-connected through the light receiving circuit unit 17. ing. Further, a suction device 7 having a motor is connected. The control unit 15 is provided with a smoke density detection unit 18.
[0021]
FIG. 4 is a circuit block of the smoke density detection unit 18 provided in the control unit 15 of FIG. 3 and is shown together with the light receiving circuit unit 17. This smoke concentration detection unit 18 detects the smoke concentration based on the integrated value of the received light pulse signal of scattered light obtained per unit time T, and the smoke particle depending on the type of smoke flowing into the smoke detection unit. Light emission adjustment is performed so as to reduce the influence of distribution.
[0022]
The light receiving circuit unit 17 is provided with a light receiving circuit 20 and an amplifier circuit 21. The light reception pulse signal a from the amplification circuit 21 provided in the light reception circuit unit 17 is input to the A / D converter 22 provided on the smoke density detection unit 18 side, and is sampled by the sampling clock b of a predetermined frequency. It is converted into digital received light data c. An MPU 23 is provided following the A / D converter 22, and the functions of the threshold determination unit 24, the peak value correction unit 25, the integration unit 26, the smoke density conversion unit 27, and the timer unit 28 are realized by program control of the MPU 23. .
[0023]
The threshold value determination unit 24 sets a plurality of threshold values for the light reception data c from the A / D converter 22 and determines a threshold value corresponding to the peak value of the light reception data. When the determination threshold of the threshold determination unit 24 is equal to or less than a predetermined value, the peak value correction unit 25 corrects the peak value of the received light data corresponding to the determination threshold to a larger peak value and supplies the corrected peak value to the integration unit 26. The integration unit 26 performs integration processing of the light reception data corrected by the peak value correction unit 25 over a certain time T determined by the reset signal e from the timer unit 28, specifically, cumulative addition of the light reception data, and the integration data is obtained. Output to the smoke density conversion unit 27.
[0024]
The smoke density conversion unit 27 converts the integration data obtained from the integration unit 26 into a smoke density every unit time T. A conversion table for converting this integrated data into smoke concentration should be prepared as a theoretical value by determining parameters such as the particle size of the smoke particles, the passing speed of the smoke detector, and the peak value of the received pulse signal for the smoke particles. Can do.
Next, the principle of correction of received light data in the present invention by the threshold value determination unit 24 and the peak value correction unit 25 provided in the MPU 23 of FIG. 4 will be described.
[0025]
FIG. 5 shows that the smoke obtained by burning the incense stick A and the cotton lantern B is sucked and passed through the smoke detecting unit 4 of the smoke sensing device 1 of FIG. It is the measurement result of the content rate which shows the distribution of the crest value contained in 1000 smoke particles by inputting the light reception pulse signal a obtained from the provided amplification circuit 21 into the crest analysis device.
In FIG. 5, the crest value is divided into 64 steps of i = 1 to 64 as crest value number i, and the content rate is measured. In other words, the minimum peak value for i = 1 is 64 mV, increasing by 32 mV for each step, and the maximum peak value for i = 64 is 2048 mV. This peak value is actually determined by the conversion characteristic from an analog signal to a digital signal by the A / D converter 22 provided in FIG.
[0026]
That is, if the peak value resolution ΔV per bit of the A / D converter 22 is ΔV = 32 mV, the peak value of the analog signal is converted into digital data indicated by the peak value number i. In this case, since the peak value number i is i = 1 to 64, the bit data subjected to A / D conversion is 8-bit data “00000001” to “01111111” in which i = 1 to 64 is expressed in binary.
[0027]
The peak value of the peak value number i = 1, which is less than the peak value of 64 mV, becomes digital data “00000000”, and thus the noise component of the received light pulse signal is cut, and the received light pulse signal of 64 mV or higher is handled as the effective peak value. .
Here, since the smoke of the incense stick A has a relatively low combustion temperature, many smoke particles having a large particle diameter are included. For example, the content rate of 2048 mV at which the peak value is maximum is 6.9%. On the other hand, since the cotton lantern B has a relatively high combustion temperature, it contains many smoke particles having a small particle diameter. For example, the content rate of 2048 mV at which the peak value is maximum is 1.7%, and the content rate of smoke particles having a large particle diameter is about 1/5 compared to the incense stick A.
[0028]
On the other hand, for the incense stick A and the cotton lantern B, when the peak value is 64 mV, the incense stick A containing many smoke particles with a large particle diameter is 36.5%, and the cotton lantern core containing many smoke particles with a small particle diameter. B is 47.0%. When the wave height is 96 mV at i = 2, the incense stick A is 11.5%, the cotton lantern B is 13.9%, and when i = 3 is 128 mV, the incense stick A is 7.2% and the cotton wick B is also 7. Nearly the same as 2%.
[0029]
FIG. 6 shows the distribution of peak values in the incense stick A and cotton wick B in FIG. 5 for 64 mV to 544 mV where i = 1 to 16. FIG. 7 shows this relationship more clearly.
FIG. 7 (A) shows the crest value distribution of the combustion product A containing many smoke particles having a large particle size, while FIG. 7 (B) shows the wave for the smoke of the combustion product B containing many smoke particles having a small particle size. High value distribution. 7 (A) and 7 (B) show the respective tendencies with emphasis on the actual measurement results of FIG. For this reason, in the smoke containing many smoke particles having a large particle diameter in FIG. 7 (A), the slope of the decrease in the content rate with respect to the increase in the crest value is small, and the content rate is distributed over a wide range of crest values. ing.
[0030]
On the other hand, in the smoke containing many smoke particles having a small particle diameter in FIG. 7B, the distribution of the crest values is a narrow range concentrated in the lower side. When the integrated value per unit time of the received light pulse signal is detected with different types of smoke having the peak value distribution as shown in FIGS. 5A and 5B having the same concentration, smoke particles having a large particle diameter are detected. The integrated value of smoke in FIG. 7A having a large distribution is large, and the integrated value of smoke in FIG. 7B having a small particle size is small. Therefore, in the present invention, correction is performed so that the integral value due to the crest value of smoke having a small particle diameter in FIG. 7B approaches the integral value due to smoke having a large particle diameter in FIG.
[0031]
FIG. 8 shows that the smoke density conversion part output of the incense stick A, which is smoke with a large particle diameter in FIG. 5, is set to 100, and the wave height value of the cotton lantern B, which is smoke with a small particle diameter, is corrected to make the wave height value higher. It is a correction result at the time. First, the correction example 1 is a case where the peak value of the cotton wick B is not corrected, and the cotton wick B is 58.5 with respect to 100 of the incense stick A, and a large error is generated although the smoke density is the same.
[0032]
Therefore, as in correction example 2, the i = 2 pulse height value of 96 mV or less of the cotton lantern B is corrected to i = 256 wave height value of 256 mV. When this 8-bit light reception data is viewed, the 96 mV light reception data of i = 2 is “00000010”, and there are “00000001” of i = 1 as a value less than this. The received light data “00000111” is corrected. When such correction of the correction example 2 is performed, the smoke density conversion unit output can increase the cotton wick B to 74.5 with respect to 100 of the incense stick A, and the difference between the two is reduced.
[0033]
Further, in the third correction example, the peak value of 96 mV or less is corrected to 512 mV where i = 15. This correction means that the 64 mV received light data “00000001” or the 96 mV received light data “00000010” is corrected to 512 mV received light data “00001111” where i = 15. In the third correction example, the cotton wick B can be corrected to 86.8 with respect to 100 of the incense stick A, and the difference can be further reduced.
[0034]
Correction example 4 is a case where the peak value of 96 mV or less for cotton wick B is corrected to light reception data “00011111” with a peak value of 1024 mV at i = 31. In this correction example 4, the cotton wick B can be corrected to 99.4 with respect to 100 of the incense stick A, and can be substantially matched.
As is apparent from the correction example of FIG. 8, the correction that corrects 96 mV or less in the correction example 4 to 1024 mV is the most optimal correction. For this reason, in the MPU 23 of FIG. 4, for example, the correction condition of the correction example 4 of FIG. 8 is adopted. Specifically, the A / D converter 22 is set so as to have a resolution corresponding to the crest value interval of 32 mV in FIG. 5 per bit, whereby the A / D converter 22 receives the received light pulse signal a from the amplifier circuit 21. The peak value (mV) is converted into received light data c in which the peak value number i in FIG.
[0035]
The threshold determination unit 24 determines whether or not the peak value is 96 mV or less in FIG. 5, more specifically, whether the lower 2 bits of the 8-bit light reception data c from the A / D converter 22 is “01” or “10”. is doing. When the threshold value determination unit 24 determines that the lower 2 bits of the 8-bit light reception data c are either “01” or “10”, the peak value correction unit 25 performs the peak value corresponding to the peak value 1024 mV in FIG. The number i is corrected to light reception data “00011111” expressed in binary. The other received light data c is output to the integrating unit 26 without being corrected.
[0036]
FIG. 9 is a timing chart of the peak value correction process by the MPU 23 of FIG. FIG. 9A shows a light reception pulse signal a output from the amplifier circuit 21. For this light reception pulse signal a, the peak value numbers i = 1, 2, 3, 4, 5,. Threshold values TH1, TH2, TH3, TH4, TH5,... Having peak values corresponding to are apparently set. FIG. 9B shows a sampling clock for the A / D converter 22. The A / D converter 22 samples the received light pulse signal a in FIG. 9A at the timing of the sampling clock b, and FIG. To A / D converter output c.
[0037]
The A / D converter output c in FIG. 9C shows the peak value of the received light pulse signal a extracted with the sampling clock b as it is, but the width of the thresholds TH1 to TH5 actually corresponds to the resolution of 1 bit. Thus, it is actually normalized to the level of each threshold.
The A / D converter output c in FIG. 9C, that is, the received light data is input to the threshold value determination unit 24 in FIG. 4, and the threshold value determination unit 24 determines the peak value below the threshold value TH2 corresponding to 96 mV, and the peak value correction unit. 25, for example, in FIG. 9D, the threshold value TH7 corresponding to 256 mV in the correction example 2 in FIG. 8 is corrected. Of course, correction example 4 is corrected to 1024 mV corresponding to threshold value TH31, but correction example 2 is targeted because it cannot be expressed in FIG. 9D.
[0038]
The peak value correction output d of FIG. 9 (D) subjected to the peak value correction in this way is integrated by the integration unit 26 over a predetermined time T determined by the reset signal e, that is, the peak value of each correction output is cumulatively added, The integrated value is output to the density conversion unit 27 and converted to the corresponding density.
FIG. 10 shows the tendency of the integrated value S before and after the correction with respect to the smoke density when the peak value correction is performed by the MPU 23 of FIG.
[0039]
In FIG. 10, characteristic A1 is a combustion product containing smoke particles having a large particle size before correction, and B1 is a combustion product containing smoke particles having a small particle size, and there is a large difference between them when there is no correction.
In such a case, for example, the peak values as in correction examples 2 to 4 in FIG. 8 are set so as to bring the combustion product B1 containing smoke particles having a small particle size closer to the characteristics of the combustion product A1 containing smoke particles having a large particle size. When the correction is performed, the characteristic B1 of the combustion product including smoke particles having a small particle size approaches the characteristic A1 of the combustion product including smoke particles having a large particle size, as in B2. In this case, even if the characteristic A1 includes smoke particles having a large particle diameter, the correction of the crest value is performed for the portion having a small crest value, and the characteristic A1 of the combusted matter also changes as in A2 due to the correction.
[0040]
However, in the case of a combustion product containing smoke particles having a large smoke particle diameter, the distribution of the peak value in the portion where the peak value correction is performed is small, and therefore the change in the characteristic A2 from the characteristic A1 to the correction of the peak value. As a result, the corrected characteristics B2 and A2 can be brought close as a whole.
In addition, although said embodiment took the example of a correction | amendment based on distribution of the content rate of the crest value for the incense stick of FIG. 5 and the smoke of a cotton lantern as an example, it is in distribution of particle diameter other than this. Obtain the same correction result by obtaining the same relationship between the combustibles with large differences and performing the peak value correction to correct the higher peak value for the small peak part of the smoke with small particle size. Can do.
[0041]
In the above embodiment, the case where the received light pulse signal is converted into received light data by the A / D converter and the peak value correction and integration processing is performed is taken as an example, but the same can be realized by analog signal processing. it can.
In the above embodiment, as shown in FIG. 2, the laser beam from the laser diode 5 is focused to the imaging position 10 by the imaging lens to create an optical image of a minute beam spot. The air stream of smoke particles sucked from the outside is allowed to pass through, but the collimating lens is used in place of the imaging lens 9 to convert the laser light from the laser diode 5 into parallel light, and the parallel light has a predetermined configuration. The present invention can also be applied to a smoke sensing device having a parallel optical system in which a photodiode 6 as a light receiving element is disposed at an angle θ.
[0042]
Furthermore, the present invention includes appropriate modifications within a range that does not impair the object and advantages thereof, and is not limited by the numerical values of the above-described embodiments.
[0043]
【The invention's effect】
As described above, according to the present invention, even if there is a difference in the particle size distribution depending on the type of smoke, a region having a small peak value of the light reception pulse signal of smoke having a small particle size is converted to a higher peak value. By performing the correction, it is possible to suppress the error in the integral amount due to the difference in the smoke particle diameter distribution, and thereby to detect the smoke density more accurately regardless of the type of smoke.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of the overall configuration of a smoke sensing device according to the present invention. FIG. 2 is an explanatory diagram of a scattered light type smoke particle detection structure according to the present invention. FIG. 3 is a block diagram of the signal processing device of FIG. 3 is a circuit block diagram of the smoke concentration detection processing unit in FIG. 3. FIG. 5 is an explanatory diagram of the measurement result of the peak value distribution of the smoke obtained by burning the incense stick and the cotton lantern. FIG. 6 is a graph plotting FIG. FIG. 7 is a graph schematically showing the tendency of the distribution of peak values when the particle size is large and small. FIG. 9 is a timing chart of the output of the smoke density conversion unit when the incense stick is 100. FIG. 10 is a timing chart of the peak value correction processing in FIG. 4. FIG. Characteristic diagram showing the relationship of integral values Description of the code]
1: Smoke detection device 2: Detection pipe 3: Suction hole 4: Smoke detection part 5: Laser diode 5a: Laser diode chip 6: Photodiode (light receiving element)
7: Suction device 8: Signal processing unit 9: Imaging lens 10: Imaging position (smoke detection area)
11: light emitting optical axis 12, 19: light receiving optical axis 15: control unit 16: light projecting circuit unit 17: light receiving circuit unit 18: smoke density detecting unit 20: light receiving circuit 21: amplifier circuit 22: A / D converter 23: MPU
24: Threshold determination unit 25: Peak value correction unit 26: Integration unit 27: Smoke density conversion circuit 28: Timer circuit

Claims (6)

A light projecting unit that irradiates a smoke detection region through which intake air passes laser light emitted from a laser diode, and a light receiving pulse that receives a scattered light pulse generated each time smoke particles pass through the smoke detection region by a light receiving element. A light receiving unit that outputs a signal; an integration unit that integrates a light reception pulse signal from the light receiving unit to obtain an integral amount per unit time; and a smoke density that is detected based on the integral amount per unit time of the integration unit In a smoke sensing device that comprises a smoke concentration detector and optically detects smoke particles floating in the air aspirated from a monitored area to judge a fire,
A plurality of threshold values for the received light pulse signal received by the light receiving unit, and a threshold value determination unit for determining a threshold value corresponding to the peak value of the received light pulse signal;
When the determination threshold of the threshold determination unit is equal to or less than a predetermined value, the peak value correction unit that corrects the peak value of the received light pulse signal corresponding to the determination threshold to a larger peak value and integrates the peak value by the integration unit;
A smoke sensing device characterized by comprising: The smoke sensing device according to claim 1,
The threshold determination unit inputs conversion data from an A / D converter that samples the light reception pulse signal and converts it into n-bit light reception data having a predetermined peak value resolution ΔV per bit, and the A / D converter Whether or not the n-bit converted data is received light data having bit 1 in any of the predetermined lower m bits,
The crest value correcting unit corrects the received light data having a predetermined k bits larger than the lower m bits when the threshold value determining unit determines received light data having bit 1 in any of the lower m bits. A smoke detector. The smoke sensing device according to claim 2, wherein
The threshold determination unit determines whether or not the received light data has bit 1 in any of the lower 2 bits of the n-bit converted data converted by the A / D converter,
The peak value correction unit corrects the received light data having bit 1 in any one of the lower 2 bits to 5-bit light reception data, which is all 1 bits, when the threshold value determination unit determines the light detection data. apparatus. 4. The smoke detection device according to claim 3, wherein when the threshold value determination unit determines 2-bit light reception data “01” or “10”, the peak value correction unit receives each light reception data as 5-bit light reception. A smoke sensing device, wherein the data is corrected to data “11111”. The smoke sensing device according to claim 2, wherein
The threshold determination unit determines whether the n-bit conversion data converted by the A / D converter is light reception data having bit 1 in any of the lower 2 bits,
The peak value correcting unit corrects the received light data having 4 bits in all of the lower 2 bits to 4 bits of received light data when the threshold value determining unit determines one of the lower 2 bits. Sensing device. 6. The smoke detection device according to claim 5, wherein when the threshold value determination unit determines 2-bit light reception data “01” or “10”, the peak value correction unit receives each light reception data as 4-bit light reception. A smoke sensing device, wherein the data is corrected to data “1111”.

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