JP3326037B2 - Deterioration detection method for scattered light smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattered light for detecting the amount of smoke with high sensitivity by receiving scattered light obtained by irradiating a laser spot to smoke particles contained in air sucked by a fan from a security space. The present invention relates to a method for detecting deterioration of a smoke detector.

[0002]

2. Description of the Related Art Conventionally, in such a high-sensitivity scattered light type smoke detector, a sampling pipe is set up in a caution space such as a semiconductor-related clean room or a computer room, and air is sucked by a fan or a pump. The laser beam is focused, and the laser beam is focused. The pulsed scattered light of each smoke particle is captured by the light receiving unit, compared with a threshold value by a comparator, and converted into a pulse signal. The smoke amount is detected by counting the pulse signal.

[0003] The structure of the smoke detection section is such that a laser beam from a laser diode is condensed by a lens, a minute spot is applied to the smoke detection position, and a photodiode is arranged at a position shifted by a predetermined angle with respect to the optical axis of the laser light. Then, the light is condensed by a lens scattered by smoke particles and converted into a light reception signal. A test LED is arranged at a position facing the photodiode,
At the time of inspection, the test LED is turned on to check whether or not the photodiode output can be normally obtained.

[0004]

By the way, the laser diode used in such a highly sensitive scattered light type smoke detector has a deteriorated light emission capability during a long period of use, resulting in a reduced light emission amount. I do. However, at present, there is no method for judging the degree of deterioration of the laser diode itself.

[0005] Also, with respect to the photodiode for receiving light, the light receiving capability similarly decreases due to aging. In response to this, it is possible to determine the deterioration by lighting the test LED. However, the test LED also suffers from the deterioration of the light emitting ability, and it is difficult to determine the deterioration of only the photodiode. The present invention
In view of such a conventional problem, deterioration detection of a scattering type smoke detector that can detect the degree of deterioration of a laser diode, a test LED, and a photodiode as accurately as possible is possible. The aim is to provide a method.

[0006]

First, according to the present invention, a light receiving section is arranged at a position shifted by a predetermined angle with respect to an optical axis of a light emitting section with respect to a smoke detection space to receive light scattered by smoke particles. It is intended for a scattered light type smoke detection device provided with a test light emitting unit at an opposing position. As a method of detecting deterioration of such a scattered light type smoke detection device, the present invention drives the light emitting unit and the test light emitting unit at a predetermined current value at regular intervals, and based on the light reception output of the light receiving unit, Based on the characteristic value, the characteristic value of the test light emitting unit, the characteristic value when the light emitting unit and the test light emitting unit are simultaneously driven, a measurement process, and the previous and current characteristic values obtained in the measurement process.
A deterioration calculating step of calculating deterioration of the light emitting unit, the test light emitting unit, and the light receiving unit.

In the measurement process, the current values of the light emitting section and the test light emitting section are changed, and the characteristic value of the light emitting section, the characteristic value of the test light emitting section, Further, it is desirable to measure characteristic values when the light emitting unit and the test light emitting unit are simultaneously driven. The deterioration calculation process
For each of the characteristic value of the light emitting unit, the characteristic value of the test light emitting unit, and the characteristic value when the light emitting unit and the test light emitting unit are simultaneously driven, the degree of deterioration is obtained by dividing the current characteristic value by the previous characteristic value. K _L , L _E , and K _LE are obtained, and the deterioration α of the light emitting unit, the deterioration β of the test light emitting unit, and the deterioration γ of the light receiving unit are calculated as follows: α = K _LE / K _E β = K _LE / K _L γ = K _L・ Calculate as K _E / K _LE .

In the present invention, when detecting smoke particles with high sensitivity,
The light receiving unit is a laser diode, and the test light emitting unit is L
ED, and the light receiving unit is a photodiode,
The deterioration α and β of the light emitting ability of the laser diode and the LED and the deterioration γ of the light receiving ability of the photodiode are detected.

[0009]

According to the method for detecting the deterioration of a scattered light type smoke detector according to the present invention, a device for detecting a smoke amount with high sensitivity by a scattered light type in which a laser diode, a photodiode and a test LED are arranged is provided. Measure the light receiving output of the photodiode as each characteristic value in each of the laser diode alone drive, the test LED alone drive, and the simultaneous drive of the laser diode and the test LED, based on the previous measurement result and this measurement result Deterioration of each element can be numerically detected, and by knowing which element has deteriorated to what extent, deterioration compensation processing and adjustment processing can be performed appropriately, and the stability and reliability of the device can be improved. Performance can be greatly improved.

[0010]

FIG. 1 shows an example of a scattered light type smoke detector to which the deterioration detection method of the present invention is applied. In FIG. 1, a laser diode (LD) 2 is provided as a light source in a smoke detection section 1, and a laser beam from the laser diode 2 is condensed by a lens 6 to form a small beam spot in a smoke detection space 5. are doing.

A photodiode (PD) 3 is provided at a position shifted by a predetermined light receiving angle θ with respect to the optical axis of the laser beam from the laser diode 2, and scattered light due to smoke particles existing in the smoke detection space 5. The light is condensed by the lens 7 and converted into an electric signal. An optical trap 25 is provided at a position facing the laser diode 2 so that unnecessary light does not enter the photodiode 3.

Further, a test LED 4 is provided at a position facing the photodiode 3 with the smoke detection area 5 interposed therebetween. The smoke detection unit 1 is provided with an MPU 8 for the process of detecting the amount of smoke by the scattered light method and the process of detecting the deterioration according to the present invention. In addition to the function of measuring the amount of smoke by the scattered light method, the MPU 8 is provided with a deterioration measurement processing unit 15 as a program control function for realizing the deterioration detection method of the present invention.

The laser diode 2 includes an LD drive circuit 10
The amount of light emission can be controlled by setting the supply current according to. The supply current to the laser diode 2 by the LD drive circuit 10 is the same as the supply current instruction value from the MPU 8.
The converter 9 converts the signal into an analog signal, and the LD drive circuit 1
It can be controlled by supplying 0. The test LED 4 is
The amount of light emission is controlled by controlling the supply current by the LED drive circuit 12. In this LED drive circuit 12 as well, the supply current is the current instruction data from the MPU 8 and the DA converter 1
It can be changed by converting by 1.

The light-receiving signal from the photodiode 3 is amplified by a light-receiving amplifier circuit 13, taken into the MPU 8 as digital data by an AD converter 14, and subjected to a normal smoke amount measurement process and further to a deterioration measurement processing unit 15. Used for the deterioration detection processing of the invention. Further, the detection result of the normal amount of smoke of the MPU 8 or the deterioration value measured by the deterioration measurement processing unit 15 is sent to an external unit such as a receiver and output and displayed.

Next, the principle of the deterioration detection method of the present invention executed by the deterioration measurement processing unit 15 provided in the MPU 8 of FIG. 1 will be described. The deterioration detection method of the present invention is based on a case where the laser diode 2 and the test LED 4 are driven by changing the supply current at predetermined intervals, and the laser diode 2 is driven independently based on the light receiving output of the photodiode 3. Light receiving output, test LED
The measurement process of measuring each of the received light output when the laser diode 4 is driven independently and the received light output when the laser diode 2 and the test LED 4 are simultaneously driven as characteristic values The previous and current characteristic values obtained in this measuring process , The deterioration calculation process of calculating the deterioration α, β, and γ of the laser diode 2, the test LED 4, and the photodiode 3.

FIG. 2 shows how the characteristic values are measured in the first measurement process. First, FIG. 2 (A)
The measurement results of the laser diode 2 are shown. The solid line is the characteristic obtained in the first measurement, and the broken line is the characteristic obtained in the next measurement after a certain period of time. That is, the laser diode 2
The supply current to the photodiode 3 is changed in three stages, for example, Ia1, Ia2, and Ia3.
Ja1, Ja2, and Ja3 giving the characteristics of the solid line as the D output are measured.

On the other hand, if the laser diode 3 deteriorates to a certain extent after a certain period of time, the PD output obtained in the second measurement shows Ja1 ', Ja2 as shown by the broken line.
', Ja3'. FIG. 2B shows the LED supply currents Ib1 and Ib for the test LED 4 in the same manner.
The characteristics for two times changed in three steps of 2, Ib3, the solid line is the previous characteristic, and the broken line is the current characteristic. Also in this case, the PD obtained by the previous lighting of the test LED 4 was used.
The outputs Nb1, Nb2, and Nb3 are reduced to Nb1 ', Nb2', and Nb3 ', which give the characteristics indicated by broken lines, depending on the degree of deterioration after a certain period.

FIG. 2C shows the characteristics of the PD output by the photodiode 3 when both the laser diode 2 and the test LED 4 are simultaneously driven. Similarly, the solid line is the previous characteristic, and the broken line is the current characteristic. Becomes At this time, the supply currents Ia and Ib to the laser diode 2 and the test LED 4 are the three-stage LED supply currents Ia1 to Ia3 and the LED supply currents Ib1 to Ib used in FIGS.
Use b3.

In the case of the simultaneous driving shown in FIG. 2C, the PD output by the simultaneous driving is Mab1, Mab2 in the previous time of the solid line.
, Mab3, and according to the deterioration after a certain period of time, the current measurement results show Mab1 ', Mab2', Mab3 as indicated by broken lines.
´. Next, a description will be given of a deterioration detection process performed based on the previous and current characteristic measurement results shown in FIG.

First, in each of FIGS. 2A, 2B and 2C, the degree of deterioration K _L of the laser diode 2 alone driving and the test are shown from the difference between the previous characteristic indicated by the solid line and the current characteristic indicated by the broken line. Degree of Degree K _E of Single Drive of Test LED 4, and Laser Diode 2 and Test LED
The degree of deterioration K _LE in the simultaneous driving of No. 4 is calculated by the following equation.

[0021]

(Equation 1)

The meaning of the equations (1) to (3) is shown in FIG.
The average value of the measured values of the three PD outputs obtained by changing the supply current shown in (A) to (C) in three stages was obtained for the previous time and this time, and the current average value was divided by the previous average value. Things. Thus, by calculating the degree of deterioration using the average value of the measured values obtained by changing the supply current in three stages, the degree of deterioration with little variation can be obtained.

Of course, the number of measurements used to calculate the degree of deterioration is not limited to three, but may be a plurality of times. If the measurement result is stable, it is not an average value but a specific value in the first measurement process. Only one measurement of the supply current may be used. Here, the degradation of the light emitting ability of the laser diode 2 is α,
Assuming that the deterioration of the light emitting ability of the test LED 4 is β and the deterioration of the light receiving ability of the photodiode 3 is γ, the above (1)
The following relationship is established between the degrees of deterioration K _L , K _E, and K _LE based on the actually measured values of Expressions (3) to (3).

[0024]

(Equation 2)

Therefore, based on the relations of the equations (4) to (6), the deterioration α of the light emitting ability of the laser diode and the test L
The degradation β of the light emitting ability of the ED 4 and the degradation γ of the light receiving ability of the photodiode 3 are calculated by the following equations.

[0026]

(Equation 3)

FIG. 3 is a flowchart showing the operation of the MPU 8 shown in FIG.
This is the overall processing of the measurement processing by the deterioration measurement processing unit 15 provided in the above. First, in step S1, the output of the laser diode 2, the test LED 4, and the output of the photodiode 3 by driving the laser diode 2 and the test LED 4 are measured, for example, according to the characteristics shown by solid lines in FIGS. Obtain three measurements.

Subsequently, in step S2, the progress of a predetermined period of time, for example, one month, half year, or one year, in which deterioration is expected, is monitored. When the predetermined period has passed, the process proceeds to step S3, and the same as step S1 is performed. The PD output is measured to obtain a measured value according to the characteristics indicated by broken lines in FIGS. 2 (A) to 2 (C), for example. Subsequently, in step S4, the degrees of deterioration K _L , K _E , and K _LE according to the above equations (1) to (3).
Is calculated, and in step S5, the respective deterioration α, β, γ are calculated according to the equations (7) to (9).

Then, in step S6, the calculated deteriorations α, β, γ are evaluated and output is displayed. The evaluation of the calculated deterioration may be performed artificially, or, for example, a threshold value of the deterioration to be determined to be abnormal may be determined, and a warning of a maintenance request may be displayed when the threshold value falls below the threshold value. Hereinafter, similarly, the processing of steps S2 to S6 is repeated at regular intervals.

FIG. 4 shows details of the PD output measurement processing shown in steps S1 and S3 in FIG. First, in step S1, the supply current of the laser diode 2 is set to an initial value, light emission driving of the laser diode 2 is performed in step S2, and the light receiving output of the photodiode 3 is measured in step S3. Subsequently, in step S4, it is checked whether or not the predetermined number of measurements has been completed. If not, in step S5, the supply current to the laser diode 2 is updated to the next value, and the processing from step S2 is performed. repeat.

When the measurement process by the light emission drive of the laser diode 2 is completed, an initial value of the supply current to the test LED 4 is set in a step S6, and the test LED 4 is driven to emit light in a step S7. The output of the diode 3 is measured. Then, step S9
Then, it is checked whether or not the predetermined number of measurements determined for the test LED 4 has been completed. If the measurement has not been completed, in step S10, the current supplied to the test LED 4 is updated to the next value. Is repeated.

When the measurement by driving the test LED 4 is completed, the supply current for simultaneous driving is set for each of the laser diode 2 and the test LED 4 in step S11, and the drive current is simultaneously driven in step S12. The LD output of the photodiode 3 is measured at step S14, and the laser diode 2 and the test LED 4 are measured at step S15 until the predetermined number of measurements is completed at step S14.
The supply current is updated to the next value, and the processing is repeated.

FIG. 5 shows a high-sensitivity smoke detector to which the deterioration detection method of the present invention is applied. In FIG. 5, the high-sensitivity smoke detection device 16 includes a smoke detection unit 1, a circuit unit 18, a flow measurement unit 19,
It has a fan unit 20, and a warning space 2
1, a sampling pipe 22 is provided, and the air in the caution space 21 is sucked into the smoke detection section 1 by suction by the fan section 20.
The configuration of the smoke detector 1 is the same as that of FIG. In the circuit section 18,
The hardware including the MPU 8 as shown in FIG. 1 is implemented.

The smoke detection processing by the circuit section 18 includes a noise reduction processing and a signal amplification by a filter for a pulse-like signal due to scattering from smoke particles obtained by the photodiode 3 provided in the smoke detection section 1. After that, the S / N is improved, the signal is converted into a digital signal by the AD converter 14, and a signal pulse is taken in over a certain gate time and counted, thereby converting into a smoke density.

Further, since the circuit section 18 is provided with a processing function for realizing the deterioration detection method of the present invention, for example, at the time of initializing diagnosis processing when the power of the high-sensitivity detecting device 16 is turned on, the first processing is performed. The measurement process is performed, and thereafter, the measurement process is performed every elapse of a predetermined period, and the deterioration of the laser diode, test LED, and photodiode provided in the smoke detection unit 1 is performed every time after the second time. Using the result of the calculation of γ, necessary measures are taken by displaying on the device itself or displaying a message to the host device.

The flow rate measuring section 1 provided following the smoke detecting section 1
As 9, the flow rate of the sample air sucked by the fan unit 20 is measured using, for example, a platinum film thermistor. The measurement result of the flow velocity measuring section 19 is given to the circuit section 18 and, for example, when the count value of smoke particles due to the flow rate fluctuation is corrected, or when the flow rate falls below a certain value, the sampling pipe 22 or the suction fan An alarm display is made on the assumption that the unit 20 has some abnormality.

In the above-described embodiment, the application to a high-sensitivity smoke detection device which receives the scattered light of smoke particles by narrowing the beam spot of the laser diode to the position where the sample air passes is described as an example. LED instead of 2
The same can be applied to a normal scattered light type smoke detector using the above. When the present invention is applied to the scattered light type smoke detector, the function may be provided in the detector itself, or provided in the receiver to exchange necessary information by polling from the receiver to reduce deterioration. You may make it detect.

[0038]

As described above, according to the present invention, the light receiving output of the photodiode is measured by independently driving the laser diode, independently driving the test LED, and simultaneously driving the laser diode and the test LED. The deterioration of each element can be numerically detected from the previous and current measurement results, and the degree of deterioration of each element can be grasped quantitatively. Compensation processing for compensating for the decrease in the amount of light, forcible processing for maintaining the appropriate amount of emitted light and received light, and the ability to accurately and appropriately judge the abnormality of the element, greatly improving the stability and reliability of the device. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a device configuration to which the present invention is applied.

FIG. 2 is an explanatory diagram of a measurement example of a characteristic value according to the present invention.

FIG. 3 is a flowchart showing overall processing of deterioration detection according to the present invention by the MPU of FIG. 1;

FIG. 4 shows the LD drive, LED drive, LD and LE of FIG.
Flowchart of measurement process of PD output by simultaneous driving of D

FIG. 5 is an explanatory diagram of a high-sensitivity smoke detection device to which the present invention is applied.

[Explanation of symbols]

 1: Smoke detection section 2: Laser diode (LD) 3: Photodiode (PD) 4: Test LED 5: Smoke detection area 6, 7: Lens 8: MPU 9, 11, DA converter (DAC) 10: LD drive Circuit 12: LED drive circuit 13: Light-receiving amplifier circuit 14: AD converter (ADC) 15: Deterioration measurement processing unit 16: High-sensitivity smoke detector 18: Circuit unit 19: Flow rate measurement unit 20: Fan unit 21: Warning space 22: Sampling tube 25: Optical trap

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kohei Miyao 2-10-43 Kami-Osaki, Shinagawa-ku, Tokyo Inside Houtiki Co., Ltd. (72) Inventor Ichiro Endo 2- 10-43, Kami-Osaki, Shinagawa-ku, Tokyo (56) References JP-A-2-18697 (JP, A) JP-A-55-78397 (JP, A) JP-A-2-18695 (JP, A) JP-A-1-213794 ( JP, A) JP 49-35035 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08B 17/107

Claims (4)

(57) [Claims] 1. A light-emitting unit is disposed at a position deviated by a predetermined angle from an optical axis of a light-emitting unit with respect to a smoke detection space to receive light scattered by smoke particles, and a test light-emitting unit is disposed at a position facing the light-receiving element. In the method for detecting deterioration of the scattered light type smoke detection device provided with, the light emitting unit and the test light emitting unit are driven at a predetermined current value at regular intervals, and the light emission is performed based on the light receiving output of the light receiving unit. Measuring the characteristic value of the unit, the characteristic value of the test light emitting unit, and the characteristic value when simultaneously driving the light emitting unit and the test light emitting unit; and the previous and the current time obtained in the measuring process. A deterioration calculating step of calculating deterioration of the light emitting unit, the test light emitting unit, and the light receiving unit based on the characteristic value. 2. The method for detecting deterioration of a scattered light type smoke detector according to claim 1, wherein the measuring step includes changing a current value of the light emitting unit and the test light emitting unit, and detecting a light output of the light receiving unit. The characteristic value of the light emitting unit, the characteristic value of the test light emitting unit, and the characteristic value when the light emitting unit and the test light emitting unit are simultaneously driven are measured as an average value of the scattered light smoke. A method for detecting deterioration of a detection device. 3. The deterioration detecting method for a scattered light type smoke detector according to claim 1, wherein the deterioration calculating step includes the step of calculating the characteristic value of the light emitting section, the characteristic value of the test light emitting section, and the light emitting section. and for each of the characteristic values when simultaneously driving the test light emitting portion, the degree K _L deterioration by dividing the current characteristic value in the previous characteristic values, L _E, determine the K _LE, deterioration of the light emitting portion alpha, test The scattered light smoke is characterized in that the deterioration β of the light emitting part and the deterioration γ of the light receiving part are calculated as α = K _LE / K _E β = K _LE / K _L γ = K _L · K _E / K _LE A method for detecting deterioration of a detection device. 4. A method for detecting deterioration of a scattered light type smoke detector according to claim 1, wherein said light receiving section is a laser diode, said test light emitting section is an LED, and
A method for detecting deterioration of a scattered light type smoke detector, wherein the light receiving unit is a photodiode, and detects deterioration α, β of light emitting ability of the laser diode and the LED and deterioration γ of light receiving ability of the photodiode.