JP2019175083A - Smoke sensor and smoke detection system - Google Patents

Abstract

To provide a smoke sensor capable of suppressing reduction in accuracy of output from a light-receiving element, and a smoke detection system.SOLUTION: A smoke sensor comprises: a light-emitting element; a light-receiving element including a light-receiving axis which crosses a light-emitting axis of the light-emitting element; and a control unit which defines output of the light-receiving element in a state where a smoke concentration is zero, as a reference value and compensates the output of the light-receiving element by using a compensation value that is obtained on the basis of a rate of change in the output of the light-receiving element with respect to the reference value. Each time the smoke sensor is powered on, the control unit determines the compensation value of the light-receiving element.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a photoelectric smoke detector and a smoke detection system including a light emitting element and a light receiving element.

  2. Description of the Related Art Conventionally, a photoelectric smoke detector that detects smoke by emitting light from a light emitting element and receiving scattered light generated by smoke particles with a light receiving element is known. In the photoelectric smoke detector, the sensitivity of the light receiving element can change over time due to the fact that dirt adheres to the inside of the smoke detection chamber, the light emitting element and the light receiving element. Therefore, in order to suppress a decrease in smoke detection accuracy caused by a change in sensitivity of the light receiving element over time, a technique for performing compensation processing to compensate for the change in sensitivity of the light receiving element has been proposed (for example, see Patent Document 1).

JP2013-3760A

  In the smoke detector described in Patent Document 1, the sensitivity of the light receiving element is compensated by using a characteristic in which the sensitivity of the light receiving element is associated with the usage time of the light receiving element. In Patent Document 1, as the usage time becomes longer, the amount of dust and the like accumulated in the smoke detection chamber in which the light receiving element is accommodated increases, and accordingly, the scattered light in the smoke detection chamber increases and the light receiving intensity of the light receiving element increases. As a result, the sensitivity of the light receiving element is compensated according to the usage time.

  However, if the installation location of the smoke detector is changed due to a change in the layout of the room where the smoke detector is installed, the output of the light receiving element may change depending on the brightness of the installation location even if the smoke concentration is the same. There is. Also, if the installation environment of the smoke detector is changed while the output of the light receiving element is compensated, and the compensation amount is reset when the smoke detector is turned off, Despite the need for compensation, there is no compensation. If it does so, a fire will be monitored in the state which the sensitivity of the light receiving element fell.

  Also, if the smoke detector is cleaned and dust is removed with the sensitivity compensation amount of the light receiving element increased according to the usage time, the actual sensitivity of the light receiving element of the smoke detector will be The sensitivity returns to the state, that is, the state where dust or the like is not accumulated. However, since the sensitivity of the light receiving element is compensated, there is a possibility that the actual smoke density cannot be accurately detected. Also, if the sensitivity compensation amount was reset by turning off the smoke detector when the smoke detector was cleaned, if the cleaning was insufficient, compensation would be necessary. The sensitivity of the light receiving element is not compensated, and the smoke density cannot be detected accurately.

  The present invention has been made against the background of the above problems, and an object of the present invention is to provide a smoke detector and a smoke detection system capable of suppressing a decrease in accuracy of output of a light receiving element.

  A smoke detector according to the present invention uses a light emitting element, a light receiving element having a light receiving axis intersecting a light projecting axis of the light emitting element, and an output of the light receiving element in a state where the smoke density is zero as a reference value, and the reference A control unit that compensates for the output of the light receiving element using a compensation value obtained based on a change rate of the output of the light receiving element with respect to the value, and the control unit receives the light receiving each time the power is turned on. The compensation value of the element is determined.

  A smoke detection system according to the present invention includes a smoke detector and a receiver connected to the smoke detector, the smoke detector including a light emitting element and a projection of the light emitting element. A light-receiving element having a light-receiving axis that intersects the optical axis, and the receiver uses the output of the light-receiving element in a state where the smoke density is zero as a reference value, and the rate of change of the output of the light-receiving element with respect to the reference value A control unit that compensates the output of the light receiving element using the compensation value obtained based on the control unit, and the control unit determines the compensation value of the light receiving element each time the power is turned on. .

  According to the present invention, even when an external factor that changes the light receiving intensity of the light receiving element of the smoke detector changes, the output accuracy of the light receiving element can be maintained after the power is turned on.

It is a figure explaining the structure of the smoke detector which concerns on embodiment. It is a functional block diagram of the smoke detection system and smoke detector concerning an embodiment. It is a flowchart explaining the compensation process which concerns on embodiment.

Embodiment.
(Configuration of smoke detector)
FIG. 1 is a diagram for explaining the structure of a smoke detector according to an embodiment. The smoke detector 1 includes a casing 2 constituting an outer shell, a smoke detection space 3 formed inside the casing 2, a first light emitting element 4, a second light emitting element 5, and a light receiving element 6. . The smoke detector 1 emits light toward the smoke detection space 3 formed in the housing 2 and receives the scattered light generated by the smoke existing in the smoke detection space 3 to detect the smoke. It is a sensor.

  The first light emitting element 4 and the second light emitting element 5 are, for example, LEDs (Light Emitting Diodes), and emit light toward the smoke detection space 3. Both the first light emitting element 4 and the second light emitting element 5 emit red light (for example, wavelength 655 nm) in the visible light region toward the smoke detection space 3. In addition, the 1st light emitting element 4 and the 2nd light emitting element 5 are not limited to what emits red light with a wavelength of 655 nm, What is necessary is just to emit the light which has a peak wavelength within the range of wavelength 600nm -700nm. .

  The light receiving element 6 receives light and outputs a signal corresponding to the received light intensity. The light receiving element 6 is, for example, a photodiode. The light receiving element 6 is disposed at a position where the light emitted from the first light emitting element 4 and the second light emitting element 5 does not directly enter. That is, assuming that the optical axis of the first light emitting element 4 is the first light projecting axis 4A, the optical axis of the second light emitting element 5 is the second light projecting axis 5A, and the optical axis of the light receiving element 6 is the light receiving axis 6A. The optical axis 4A and the light receiving axis 6A intersect, and the second light projecting axis 5A and the light receiving axis 6A intersect. The light receiving element 6 receives scattered light generated by reflection of light emitted from the first light emitting element 4 and the second light emitting element 5 on smoke particles.

  The light receiving element 6 is in a position where the first angle θ1 of the light receiving axis 6A with respect to the first light projecting axis 4A of the first light emitting element 4 is an acute angle (for example, 60 °), and the second light projecting axis of the second light emitting element 5 is. The second angle θ2 of the light receiving shaft 6A with respect to 5A is at an obtuse angle (for example, 110 °). The first angle θ1 and the second angle θ2 are different. Therefore, when the first light emitting element 4 emits light, the light receiving element 6 receives the forward scattered light of smoke generated by the light of the first light emitting element 4. Further, when the second light emitting element 5 emits light, the light receiving element 6 receives the smoke backscattered light generated by the light of the second light emitting element 5. The first angle θ1 may be an acute angle, and more preferably a value in an angle range of 50 degrees to 70 degrees. The second angle θ2 may be an obtuse angle, and more preferably a value in the angle range of 100 degrees to 120 degrees.

  The light receiving element 6 outputs the received light intensity of the scattered light from the smoke generated by the light of the first light emitting element 4 as the first output signal S1, and the scattered light from the smoke generated by the light of the second light emitting element 5. Is received as the second output signal S2.

  FIG. 2 is a functional block diagram of the smoke detection system and the smoke detector according to the embodiment. The smoke detector 1 includes a first light emitting element 4, a second light emitting element 5, a light receiving element 6, a control unit 7, a storage unit 8, and a notification unit 9. The smoke detector 1 is connected to the fire receiver 20 via a transmission line, and the smoke detector 1 outputs a signal regarding the occurrence of a fire to the fire receiver 20. In the present embodiment, the smoke detector 1 and the fire receiver 20 constitute a smoke detection system.

  The control unit 7 controls the light emitting operation of the first light emitting element 4 and the second light emitting element 5. The control unit 7 determines whether or not a fire has occurred using the first output signal S1 and the second output signal S2 output from the light receiving element 6. Data used for determining whether or not a fire has occurred is stored in the storage unit 8. If it is determined that a fire has occurred, the control unit 7 controls the reporting unit 9 to transmit a signal indicating the occurrence of a fire to the fire receiver 20.

  Here, the control unit 7 is configured by dedicated hardware or an MPU (Micro Processing Unit) that executes a program stored in a memory. When the control unit 7 is dedicated hardware, the control unit 7 may be, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Applicable. Each function realized by the control unit 7 may be realized by individual hardware, or each function may be realized by one piece of hardware. When the control unit 7 is an MPU, each function executed by the control unit 7 is realized by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in a memory. The MPU implements each function of the control unit 7 by reading and executing a program stored in the memory. The memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM. The storage unit 8 is a nonvolatile or volatile semiconductor memory such as a RAM, ROM, flash memory, EPROM, or EEPROM.

(Smoke detection processing)
The control unit 7 calculates an output ratio R (= first output signal S1 / second output signal S2) between the first output signal S1 and the second output signal S2, and based on the calculated output ratio R, the first The output signal S1 is corrected. The corrected signal is referred to as a first output signal SC1. Then, the control unit 7 determines a fire using the corrected first output signal SC1. The storage unit 8 stores a threshold value for fire determination corresponding to, for example, a light attenuation rate of 10% / m by a CS meter (light attenuation rate meter). And the control part 7 determines with the fire having generate | occur | produced, when the value of 1st output signal SC1 after correction | amendment exceeds the threshold value for fire determination.

  Here, a process of obtaining the first output signal SC1 by correcting the first output signal S1 will be described. When a fire occurs, not only one type of smoke is generated, but various types of smoke, such as white smoke, gray smoke, and black smoke, are generated depending on the combusted matter. In addition, steam may be generated in the room where the smoke detector 1 is installed instead of smoke due to fire. The smoke detector 1 needs to detect and report a fire when any of these various types of smoke is generated, but should not be determined as a fire when steam is generated. And the output ratio R becomes a value according to whether it is the kind of smoke and steam. That is, it can be determined from the output ratio R whether the type of smoke and steam.

  The light receiving intensity of the light receiving element 6 when white smoke and gray smoke are in the smoke detecting space 3 is larger than the light receiving intensity of the light receiving element 6 when black smoke is in the smoke detecting space 3. In other words, when black smoke is in the smoke detection space 3, the light receiving intensity of the light receiving element 6 is relatively small. For this reason, if the same threshold value for fire determination is used for black smoke, white smoke, and gray smoke, it is difficult to determine that a fire has occurred in the case of black smoke. Further, when the steam is in the smoke detection space 3, it is necessary to determine that it is non-fire. From these, based on the output ratio R, that is, based on the type of smoke or the like, the first output signal S1 is corrected to obtain a corrected first output signal SC1, and the corrected first output signal The fire is judged using SC1.

  The storage unit 8 stores a correction table or a calculation formula in which the output ratio R serving as an index for determining whether or not the type of smoke and steam is associated with the correction coefficient Cf. The control unit 7 refers to the correction table or the calculation formula, acquires the correction coefficient Cf corresponding to the calculated output ratio R, corrects the first output signal S1 using the acquired correction coefficient Cf, and performs correction. A first output signal SC1 is generated. In order to obtain the corrected first output signal SC1 following the measurement value by the CS meter (dimming rate meter), the correction coefficient Cf for black smoke is based on the correction coefficient Cf for white smoke and gray smoke. Is also a large value. In the case of steam, since it is necessary to determine that there is no fire, the correction coefficient Cf in the case of steam is the value of the first output signal S1 before the correction is the value of the corrected first output signal SC1. The value is set to be smaller than that.

  The control unit 7 determines that a fire has occurred when the value of the corrected first output signal SC1 is greater than the threshold value. When it is determined that a fire has occurred, a fire signal is transmitted from the reporting unit 9 to the fire receiver 20.

  Instead of transmitting a fire signal from the alarm unit 9, the corrected smoke density may be transmitted as an analog value. In that case, the fire receiver 20 that has received the analog value from the reporting unit 9 determines the fire. Further, although the correction of the first output signal SC1 has been described here, the threshold value for fire determination may be corrected.

  The timing at which the control unit 7 acquires the output ratio R will be described. For example, the control unit 7 can obtain the output ratio R by always causing the first light emitting element 4 and the second light emitting element 5 to alternately emit light. In addition, the control unit 7 always causes the first light emitting element 4 to emit light, and monitors whether or not the amount of light received by the light receiving element 6 exceeds a set value set as a value smaller than a threshold for determining fire. This set value is stored in the storage unit 8. Then, the control unit 7 may acquire the output ratio R by causing the first light emitting element 4 and the second light emitting element 5 to emit light alternately when the amount of received light exceeds a set value.

(Compensation processing)
As described above, the fire determination is performed using the first output signal S1 and the second output signal S2 output from the light receiving element 6, but the first output signal S1 and the second output signal S2 of the first output signal S2 with the passage of time. A decrease in accuracy may occur. For example, when dust or the like adheres to the smoke detection space 3 and white contamination occurs, the amount of reflected light in the smoke detection space 3 increases, and the light receiving intensity of the light receiving element 6 increases as a whole. Further, when dust or the like adheres to the smoke detection space 3 and black contamination occurs, the amount of reflected light in the smoke detection space 3 decreases, and the light receiving intensity of the light receiving element 6 decreases as a whole. Further, when contamination occurs due to dust or the like adhering to the surfaces of the first light emitting element 4, the second light emitting element 5, and the light receiving element 6, the amount of light transmitted through the surfaces of these elements decreases, and the light receiving element 6. The received light intensity is reduced. Thus, even if the actual smoke density is the same, the light receiving intensity of the light receiving element 6 can change due to external factors. Further, the light receiving intensity of the light receiving element 6 can also change due to the temporal deterioration of the first light emitting element 4, the second light emitting element 5, and the light receiving element 6. Such a change in the light receiving intensity of the light receiving element 6 leads to a decrease in the accuracy of smoke detection. Therefore, in the present embodiment, a compensation process is performed, which is a process that compensates for such a change in the received light intensity of the light receiving element 6 due to time or an external factor. In the compensation processing of the present embodiment, the signal output from the light receiving element 6 is compensated to obtain the first output signal S1 and the second output signal S2. That is, the compensated values of the output of the light receiving element 6 are the first output signal S1 and the second output signal S2. For the sake of explanation, the values before compensation of the output of the light receiving element 6 are referred to as a first output signal S01 and a second output signal S02.

  The compensation process of the output of the light receiving element 6 is performed by the control unit 7 in the present embodiment. In the compensation process, the control unit 7 compares the output of the light receiving element 6 when the smoke density is zero with the reference value SS, and compensates the output of the received light intensity based on the rate of change of the output with respect to the reference value SS. Is obtained. The reference value SS is an output of the light receiving element 6 when the smoke density is zero in an initial state, that is, a state where dust or the like is not accumulated (for example, at the time of factory shipment). In the present embodiment, there are a first reference value SS1 corresponding to the first light emitting element 4 and a second reference value SS2 corresponding to the second light emitting element 5. Further, there are a first compensation value Cp1 used for compensation of the output of the first light emitting element 4, and a second compensation value Cp2 used for compensation of the output of the second light emitting element 5. The absolute value of the compensation value Cp increases as the rate of change of the first output signal S01 with respect to the first reference value SS1 increases.

  FIG. 3 is a flowchart illustrating compensation processing according to the embodiment. FIG. 3 exemplifies compensation processing for the output of the light receiving element 6 when the first light emitting element 4 emits light. As a premise, the first reference value SS1 and the second reference value SS2 are stored in the storage unit 8. In addition, a table or a calculation formula indicating the relationship between the change rate of the output of the light receiving element 6 with respect to the first reference value SS1 and the first compensation value Cp1 is stored in the storage unit 8. In addition, a table or a calculation formula indicating the relationship between the change rate of the output of the light receiving element 6 with respect to the second reference value SS2 and the second compensation value Cp2 is stored in the storage unit 8.

  The control unit 7 executes compensation processing when the smoke detector 1 is powered on. Furthermore, in the present embodiment, the control unit 7 executes compensation processing periodically, for example, every 24 hours.

  When starting the compensation process, the controller 7 causes the first light emitting element 4 to emit light (S10). Next, the control unit 7 acquires the first output signal S01 before compensation output from the light receiving element 6 (S11). Subsequently, the control unit 7 determines a compensation timing that is a timing at which the compensation processing is performed (S12). If it is time to turn on the power, the process proceeds to step S13, and if it is time to periodically perform the compensation process, the process proceeds to step S14. In step S <b> 13, the control unit 7 acquires the first maximum value stored in the storage unit 8. In step S <b> 14, the control unit 7 acquires the second maximum value stored in the storage unit 8.

  Here, the first maximum value and the second maximum value are both the maximum value of the first compensation value Cp1. The first maximum value and the second maximum value are different values, and the first maximum value is larger than the second maximum value. That is, the maximum value of the first compensation value Cp1 in the compensation process performed when the power is turned on is larger than the maximum value of the first compensation value Cp1 in the compensation process performed periodically.

  Next, the control unit 7 determines the first compensation value Cp1 within the range of the maximum value of the first compensation value Cp1 acquired in Step S13 or Step S14 (S15). Since the first maximum value is larger than the second maximum value, the first compensation value Cp1 used in the compensation process performed when the power is turned on can be larger than the first compensation value Cp1 in the periodic compensation process. .

  Next, the control unit 7 compensates the first output signal S01 using the compensation value determined in step S15, and obtains the first output signal S1 (S16).

  Although FIG. 3 illustrates the case where the first output signal S01 of the light receiving element 6 is compensated when the first light emitting element 4 is caused to emit light, the same processing is executed when the second light emitting element 5 is caused to emit light. Is done. In that case, the first light emitting element, the first compensation value, the first output signal S01, and the first output signal S1 in FIG. 3 are respectively converted into the second light emitting element, the second compensation value, the second output signal S02, and the first output signal S02. What is necessary is just to read as 2 output signal S2.

  As described above, according to the present embodiment, every time the power is turned on, the output of the light receiving element 6 is compensated. For this reason, even if external factors such as the installation environment of the smoke detector 1 or the fouling state of the smoke detector 1 change while the power of the smoke detector 1 is shut off, after the power is turned on The accuracy of the output of the light receiving element 6 is restored. For this reason, the accuracy of the output of the light receiving element 6 can be maintained.

  Further, according to the present embodiment, the output of the light receiving element 6 is periodically compensated separately from when the power is turned on. For this reason, even when the smoke detector 1 is contaminated or deteriorated with the passage of time, it is possible to suppress a decrease in the accuracy of the output of the light receiving element 6.

  In the present embodiment, the first maximum value of the compensation value used for the compensation process when the power is turned on is larger than the second maximum value of the compensation value used for the periodic compensation process. . While the deterioration of the output accuracy of the light receiving element 6 over time gradually progresses, the change in the external factor of the smoke detector 1 when the power is turned on after the power is turned off can be relatively large. For this reason, by setting the first maximum value of the compensation value used when the power is turned on to a relatively large value, the output of the light receiving element 6 can be set to a more accurate value. Further, by setting the second maximum value of the compensation value in the periodic compensation process to a relatively small value, when the output of the light receiving element 6 fluctuates due to temporary disturbance, excessive compensation is performed. It can suppress that it is performed.

  The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made. For example, the case where there are two first light emitting elements 4 and second light emitting elements 5 and one light receiving element 6 is illustrated, but the first light emitting element 4 and the second light emitting element 5 are, for example, white light or the like. The light emitting element may have a predetermined wavelength range. In this case, the light receiving element may be configured to receive scattered light having different wavelengths by an optical filter or the like.

  Moreover, although the said embodiment demonstrated that the control part 7 of the smoke detector 1 performed a compensation process, the fire receiver 20 may perform a compensation process. In this case, the smoke detector 1 sends the output from the light receiving element 6 to the fire receiver 20 via the transmission line, and the fire receiver 20 compensates for the obtained output of the light receiving element 6 and performs compensation. Use the output to determine whether a fire has occurred.

  DESCRIPTION OF SYMBOLS 1 Smoke detector, 2 housing | casing, 3 smoke detection space, 4 1st light emitting element, 4A 1st light projection axis, 5 2nd light emitting element, 5A 2nd light projection axis, 6 light receiving element, 6A light receiving axis, 7 control Part, 8 storage part, 9 reporting part, 20 fire receiver.

Claims (4)

A light emitting element;
A light receiving element having a light receiving axis intersecting a light projecting axis of the light emitting element;
A control unit that compensates the output of the light receiving element using a compensation value obtained based on the change rate of the output of the light receiving element with respect to the reference value, with the output of the light receiving element in a state where the smoke density is zero And
The control unit determines the compensation value of the light receiving element every time power is turned on. The control unit periodically determines the compensation value of the light receiving element separately from when the power is turned on,
The smoke detector according to claim 1, wherein the first maximum value of the compensation value determined when the power is turned on is larger than the second maximum value of the compensation value determined periodically. The light emitting device includes a first light emitting device and a second light emitting device,
The angle of the light projecting axis of the first light emitting element with respect to the light receiving axis of the light receiving element is different from the angle of the light projecting axis of the second light emitting element with respect to the light receiving axis of the light receiving element. 2. The smoke detector according to 2. A smoke detection system comprising a smoke detector and a receiver connected to the smoke detector,
The smoke detector is
A light emitting element;
A light receiving element having a light receiving axis that intersects a light projecting axis of the light emitting element,
The receiver
A control unit that compensates the output of the light receiving element using a compensation value obtained based on the change rate of the output of the light receiving element with respect to the reference value, with the output of the light receiving element in a state where the smoke density is zero With
The control unit determines the compensation value of the light receiving element every time power is turned on.

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