JP2011215685A - Smoke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smoke sensor wherein an error is reduced by allowing sensitivity to smoothly change before and after switching of an amplifier.SOLUTION: This smoke sensor includes: an LD unit 21; a photodiode 22; an amplifier circuit 24 amplifying an output signal of the photodiode 22; and an MPU 10 distinguishing fire occurrence based on an output of the amplifier circuit 24 and a smoke density obtained based thereon. The amplifier circuit 24 includes a plurality of stages of amplifiers connected in series, and outputs an output of each amplifier to a control circuit. The MPU 10 corrects the output of each amplifier based on a correction value obtained based on the output of the amplifier and the output of the amplifier adjacent to the preceding stage side thereof.

Description

  The present invention relates to smoke detectors, and more particularly to switching of multiple stages of amplifiers connected in series.

  Some conventional sensing devices change the smoke density detection range (dynamic range), for example, by switching the amplification level of the amplifier, and convert the output of the final stage of the amplifier to a fire signal or smoke density level. (See Patent Document 1).

Japanese Patent Publication No. 05-10718 (FIGS. 1 and 2)

  In the above conventional sensing device, the detection range (dynamic range) of smoke density is changed by switching the amplification degree of the amplifier, and the output of the final stage of the amplifier is converted into a fire signal or smoke density level. There is a problem in that the sensitivity changes stepwise before and after the switching of the amplification degree, resulting in an error.

  The present invention has been made to solve the above-described problems, and reduces the error by changing the sensitivity smoothly before and after the switching of a plurality of amplifiers connected in series. An object is to provide a smoke detector.

  A smoke detector according to the present invention includes a light emitting element disposed in a smoke detecting unit, a light receiving element that receives scattered light generated by smoke particles in which light emitted from the light emitting element is present in the smoke detecting unit, and In a smoke detector comprising an amplifier circuit for amplifying an output signal of a light receiving element and a control circuit for determining the occurrence of a fire based on the smoke density corresponding to the output of the amplifier circuit, the amplifier circuit is connected in series. A plurality of stages of amplifiers, and outputs the output of each amplifier to the control circuit, the control circuit including a smoke density corresponding to the output of the amplifier, a smoke density corresponding to the output of the amplifier, and a preceding stage side Is corrected based on a correction value obtained on the basis of the smoke density corresponding to the output of the amplifier adjacent to.

Further, in the smoke detector according to the present invention, the control circuit sets a switching upper limit value for the output of each amplifier, and the switching voltage value (switching voltage value <switching upper limit) for the output of each amplifier except for the first-stage amplifier. Value), and among the outputs of the amplifiers in a plurality of stages, the output of the amplifier on the rear stage within the range of the switching upper limit value is used to determine the occurrence of a fire, and the output of the amplifier is the switching voltage value , The correction value is obtained based on the smoke density corresponding to the output of the amplifier and the smoke density corresponding to the output of the amplifier on the preceding stage, and the smoke corresponding to the output of the amplifier on the preceding stage is obtained. The density is corrected based on the correction value.
In the smoke detector according to the present invention, when the output of the amplifier reaches the switching voltage value, the control circuit detects the smoke density corresponding to the output of the amplifier and the smoke of the output of the amplifier on the preceding stage. A correction value is obtained based on the difference from the density, and a negative or positive flag is set based on the magnitude of the two, and the correction value is set to the smoke density corresponding to the output of the amplifier on the preceding stage side. Correct by subtracting or adding based on

   In the smoke detector according to the present invention, the control circuit corresponds to the smoke density corresponding to the output of the amplifier, the smoke density corresponding to the output of the amplifier, and the output of the amplifier adjacent to the preceding stage. Even if the output of the amplifier is switched and used for fire discrimination, the sensitivity changes smoothly before and after switching the amplifier, and the error is corrected. It is reduced. For this reason, when the smoke density increases at a substantially constant rate of increase, the smoke density increases linearly and is output, making it possible to make an accurate fire judgment over a wide range of smoke densities. Yes.

Further, according to the smoke detector according to the present invention, the switching upper limit value is set for the output of each amplifier, and the switching voltage value (switching voltage value <switching upper limit value) is set for the output of each amplifier except for the first stage amplifier. And the output of the amplifier on the rear stage within the range of the switching upper limit value among the outputs of the amplifiers of a plurality of stages is used for determining the occurrence of a fire, and when the output of the amplifier reaches the switching voltage value Then, a correction value is obtained based on the smoke density corresponding to the output of the amplifier and the smoke density corresponding to the output of the amplifier on the preceding stage, and the smoke density corresponding to the output of the amplifier on the preceding stage is calculated. Since the correction is made based on the correction value, the sensitivity changes smoothly before and after the switching of a plurality of amplifiers connected in series.
Further, according to the smoke detector according to the present invention, when the output of the amplifier reaches the switching voltage value, the smoke density corresponding to the output of the amplifier and the smoke density of the output of the amplifier on the upstream side thereof are compared. A correction value is obtained based on the difference, and a negative or positive flag is set based on the magnitude of both, and the correction value is set based on the flag to the smoke density corresponding to the output of the amplifier on the front side. Since correction is performed by subtraction or addition, correction processing can be easily performed.

It is a functional block diagram of the smoke detector which concerns on one embodiment of this invention. FIG. 2 is a circuit diagram of a photodiode, a current-voltage converter, and an amplifier circuit in FIG. 1. 4 is a flowchart (part 1) illustrating an amplifier selection process in the smoke detector of FIG. 1; FIG. 3 is a flowchart (part 2) illustrating an amplifier selection process in the smoke detector of FIG. 1. 6 is a flowchart (part 3) illustrating an amplifier selection process in the smoke detector of FIG. 1; It is the characteristic view which showed the relationship between the output of a photodiode (sensor), the output of an amplifier, and smoke density.

FIG. 1 is a block diagram showing a configuration of a smoke detector according to an embodiment of the present invention.
The smoke detector 1 is configured such that a duct (not shown) for drawing air from a detection area is connected to a smoke detector, and functions as a control circuit of the present invention as shown in FIG. A microprocessor (MPU) 10 is provided. The microprocessor 10 is connected to a smoke detection unit 20, an environment monitoring / fan control unit 30, a status display / sound unit 40, and the like.

  The smoke detection unit 20 includes an LD unit 21 including a laser diode, a photodiode (PD) 22, a current-voltage conversion unit 23, and an amplification circuit 24. Details of the smoke detector 20 will be described in detail later with reference to FIG. The laser diode corresponds to the light emitting element of the present invention, and the photodiode 22 corresponds to the light receiving element of the present invention.

  The environment monitoring / fan control unit 30 includes a fan voltage control / rotational speed monitoring unit 31, an airflow monitoring unit 32, a voltage monitoring unit 33, a voltage monitoring unit 34, and a temperature detection unit 35. The fan voltage control / rotational speed monitoring unit 31 is arranged in a duct (not shown) and controls the fan 71 that takes in air from the space to be monitored, and controls the drive voltage based on the output of the microprocessor 10. At the same time, the rotational speed is taken in and output to the microprocessor 10. The airflow monitoring unit 32 includes, for example, a flow sensor, detects the flow rate of the duct, and outputs it to the microprocessor 10. The voltage monitoring unit 33 monitors the power supply voltage (for example, 24 V) and outputs it to the microprocessor 10. The voltage monitoring unit 34 monitors the internal voltage applied to the microprocessor 10 and outputs it to the microprocessor 10. The temperature detector 35 detects the temperature of the environment where the smoke detector 1 is installed and outputs it to the microprocessor 10. The microprocessor 10 takes in the output from the environment monitoring / fan control unit 30 and controls the fan 71 via the fan voltage control / rotation number monitoring unit 31 and performs various arithmetic processes.

  The state display / acoustic unit 40 includes a display unit 41 and an acoustic unit 42. The display unit 41 includes, for example, a normal, alarm (alarm levels 1 to 3), a confirmation lamp for displaying filter replacement, a 10-segment (bar graph) LED indicating smoke concentration, and a 7-segment LED indicating a failure error code. For example, the sound unit 42 notifies about alarms (two types), failure, filter replacement, and the like.

In addition to the above, the microprocessor 10 is connected to a transmission / input / output unit 50, various switches 61, nonvolatile memories 62 and 63, a real-time clock 64, a DIP switch (DIPSW) 65, and the like.
The transmission / input / output unit 50 includes a transmission / reception unit (RS422) 51, an analog output unit 52, and a no-voltage contact 53. The output of the transmission / reception unit 51 is transmitted to a transmission (NIU) board of a receiver (not shown), the output of the analog output unit 52 is output to a recorder such as a logger of the receiver, and the no-voltage contact 53 is a receiver. Connected to the display. The transmission / input / output unit 50 is configured as described above, and the output of the smoke detector 1 is transmitted to a receiver or the like.
The various switches 61 include, for example, switches corresponding to recovery, shut-off, sound stop, simulated fire, and simulated failure. When these switches are operated, the microprocessor 10 corresponds to the operated switches. Perform arithmetic processing.
In the nonvolatile memory 62, for example, sensitivity and the like are set at the factory at the time of shipment. For example, density changes and events are recorded in the nonvolatile memory 63. The real time clock 64 generates a clock for operating the microprocessor 10 and the like. The dip switch 65 is for setting the address of the smoke detector 1, for example, and is set at the factory at the time of shipment.

  The configuration of the smoke detector 1 according to the present embodiment is as described above. Next, the smoke detection unit 20 that is a characteristic part of the present embodiment will be described in detail with reference to FIG.

FIG. 2 is a circuit diagram of the photodiode 22, the current-voltage converter 23, and the amplifier circuit 24 of the smoke detector.
As shown in FIG. 2, the smoke detection unit 20 includes a photodiode 22, a current-voltage conversion unit 23, and an amplifier circuit 24. A resistor R1 is connected in parallel to the photodiode 22, and receives light from the LD unit 21. The current-voltage conversion unit 23 includes resistors R2 and R3, a capacitor C1, and an amplifier (op-amp) AMP1, and converts the current from the photodiode 22 into a voltage. The amplifier circuit 24 includes a plurality of stages of amplifiers (three stages in the illustrated example) connected in series. The first stage amplifier includes resistors R2 to R4, capacitors C1 and C2, and an amplifier (op-amp) AMP1. It is composed of A part of the first-stage amplifier constitutes a current-voltage converter 23. The second stage amplifier includes resistors R5 to R7, capacitors C3 and C4, and an amplifier (op-amp) AMP2. The third-stage amplifier includes resistors R8 and R9, a capacitor C5, and an amplifier (op-amp) AMP3.

  In FIG. 2, the output of the first stage amplifier is expressed as AMP1out, the output of the second stage amplifier is expressed as AMP2out, the output of the third stage amplifier is expressed as AMP3out, and the output AMP1out of the first stage amplifier is expressed as second. The second stage amplifier output AMP2out is amplified by the third stage amplifier and output as AMP3out. These AMP1out, AMP2out, and AMP3out are input to the microprocessor 10, and the microprocessor 10 obtains the smoke density based on the input, and the fire discrimination means functionally incorporated in the microprocessor 10 determines the smoke density. If it is equal to or greater than a predetermined threshold, it is determined that a fire has occurred. A process in which the microprocessor 10 obtains the smoke density will be described with reference to FIGS.

  3 to 5 are flowcharts showing processing when the microprocessor 10 obtains the smoke density. FIG. 3 shows processing when the AMP3 output value (AMP3out) is applied as smoke density data. FIG. 4 shows AMP2. FIG. 5 shows a process when the output value (AMP2out) is applied as smoke density data, and FIG. 5 shows a process when the AMP1 output value (AMP1out) is applied as smoke density data. FIG. 6 is a characteristic diagram showing the relationship between the output (AMP1out to AMP3out) of the amplifier circuit and the smoke density.

In FIG. 3, the microprocessor 10 indicates that the relationship between the AMP3 output value and the AMP3 switching upper limit value (which is a threshold value for applying the AMP3 output value or the AMP2 output value)
AMP3 output value ≧ AMP3 switching upper limit value,
(S11), and if the condition is not satisfied (NO), the AMP3 output value is converted into smoke density. (S12) This conversion is performed based on the characteristics of FIG. 6, for example.
The relationship between the AMP3 output value and the AMP2 switching voltage value (which is an output value near the switching from the AMP3 output value to the AMP2 output value) is AMP3 output value ≧ AMP2 switching voltage value,
Is determined (S13).
For example, the AMP2 switching voltage value is set to about 70 to 90% of the AMP3 switching upper limit value. If the condition is not satisfied (NO), the AMP2 linearity adjustment value is cleared (S14), and the AMP1 linearity adjustment value is cleared (S15). These AMP2 linearity adjustment value and AMP1 linearity adjustment value will be described later.
Then, the smoke density (AMP3 smoke density) converted based on the AMP3 output value is set as the smoke density at that time (S16).

In the above determination (S13), if the condition is satisfied (YES), the AMP2 output value is converted into smoke density (S16), and the relationship between the AMP3 smoke density and the AMP2 smoke density is
It is determined whether or not AMP3 smoke density ≧ AMP2 smoke density (S17). If the condition is not satisfied (NO),
AMP2 smoke density-AMP3 smoke density (deviation calculation)
(S18), the deviation is set to the AMP2 linearity adjustment value (S19),
The plus direction adjustment flag is set (S20), and the process proceeds to the above process (S16).

In the above determination (S17), if the condition is satisfied (YES),
AMP3 smoke concentration-AMP2 smoke concentration (deviation calculation)
(S21), the deviation is set to the AMP2 linearity adjustment value (S22),
The minus direction adjustment flag is set (S23), and the process proceeds to the above process (S16).
Here, the AMP2 linearity adjustment value, the positive direction adjustment flag, and the negative direction adjustment flag are for adjusting the level of the AMP3 smoke density and the level of the AMP2 smoke density, and correct the AMP2 smoke density in FIG. 4 described later. Used when. For example, as shown in FIG. 6, in the range of 0.000% / m to 0.200% / m, the AMP3 output value (AMP3out) is applied to detection of smoke density.

In FIG. 3, the microprocessor 10 determines that the relationship between the AMP3 output value and the AMP3 switching upper limit value satisfies the condition that the AMP3 output value ≧ the AMP3 switching upper limit value (S11, YES),
In FIG. 4, the relationship between the AMP2 output value and the AMP2 switching upper limit value (which is a threshold value for applying the AMP2 output value or the AMP1 output value) is
AMP2 output value ≧ AMP2 switching upper limit value,
Is determined (S31). If the condition is not satisfied (NO), the AMP2 output value is converted into smoke density (S32). This conversion process is also performed based on the characteristics shown in FIG. And
The AMP2 smoke density soil AMP2 linearity adjustment value is corrected (S33), and the corrected AMP2 smoke density is set as the smoke density at that time. In the above correction calculation, the AMP2 linearity adjustment value (S19, S22), the positive direction adjustment flag, and the negative direction adjustment flag are already set (S20, S23), and the set flag is Addition or subtraction is performed based on this.
Next, the relationship between the AMP2 output value and the AMP1 switching voltage value (which is an output value in the vicinity of switching from the AMP2 output value to the AMP1 output value) is AMP2 output value ≧ AMP1 switching voltage value,
It is determined whether or not (S34). For example, the AMP1 switching voltage value is set to about 70 to 90% of the AMP2 switching upper limit value. When this condition is not satisfied, the process proceeds to the above process (S16), and the AMP2 smoke density corrected as described above is set as the smoke density at that time.

In the above determination (S34), if the condition is satisfied (YES), the AMP1 output value is converted into smoke density (S35), and the relationship between the AMP2 smoke density and the AMP1 smoke density is
It is determined whether or not AMP2 smoke density ≧ AMP1 smoke density (S36), and if the condition is not satisfied (NO),
AMP1 smoke density-AMP2 smoke density (calculation of deviation)
(S37), the deviation is set to the AMP1 linearity adjustment value (S38),
The positive direction adjustment flag is set (S39), and the process proceeds to the above process (S16).
In the above determination (S36), if the condition is satisfied (YES),
AMP2 smoke density-AMP1 smoke density (deviation calculation)
(S40), the deviation is set to the AMP1 linearity adjustment value (S41), the minus direction adjustment flag is set (S42), and the process proceeds to the above process (S16).
Here, the AMP1 linearity adjustment value, the positive direction adjustment flag, and the negative direction adjustment flag are for adjusting the level of the AMP3 smoke density and the level of the AMP2 smoke density, and correct the AMP1 smoke density in FIG. 5 described later. Used when. For example, as shown in FIG. 6, in the range of 0.200% / m to 20.000% / m, the AMP2 output value (AMP2out) is applied to detection of smoke density.

In FIG. 4, when the condition that the relationship between the AMP2 output value and the AMP2 switching upper limit value is such that the AMP2 output value ≧ the AMP2 switching upper limit value is satisfied (S31, YES),
In FIG. 5, the relationship between the AMP1 output value and the AMP1 switching upper limit value (which is a threshold for applying the AMP1 output value or the smoke density upper limit value) is
AMP1 output value ≧ AMP1 switching upper limit value,
Is determined (S51). If the condition is not satisfied (NO), the AMP1 output value is converted into smoke density (S52). And
AMP1 smoke density soil AMP1 linearity adjustment value correction calculation is performed (S53), the process proceeds to the above process (S16), and the corrected AMP1 smoke density is set as the smoke density at that time. In the above correction calculation, either the AMP1 linearity adjustment value (S38, S41), the plus direction adjustment flag, or the minus direction adjustment flag has already been set (S39, S42). Addition or subtraction is performed based on this.
For example, as shown in FIG. 6, the AMP1 output value (AMP1out) is in the range of 2.000% / m to 20.000% / m for detection of smoke density.
In the determination (S51), if the condition is satisfied (YES), 20.000 (% / m) is set as the smoke density at that time in order to fix the smoke density upper limit (S54). ), The process proceeds to the above process (S16).

  As described above, according to the present embodiment, the outputs AMP1out, AMP2out, and AMP3out of the amplifier to be applied according to the output of the photodiode 22 are properly used, and within the range of the switching upper limit value among the outputs of a plurality of stages. The output of an amplifier on the rear stage side is used to determine the occurrence of a fire. When the amplifier output reaches the switching voltage value, a correction value (linearity) An adjustment value) is obtained, and the output of the multiplier on the front side is corrected based on the correction value. For this reason, when the smoke density increases at a substantially constant rate of increase, the smoke density increases linearly and is output, so that the smoke density can be detected over a wide range and an accurate fire Judgment is possible.

  In addition, in the correction calculation, the microprocessor 10 obtains a correction value based on the difference between the output of the amplifier and the output of the amplifier on the preceding stage, and a negative or positive flag based on the magnitude of the two. (Minus direction adjustment flag, plus direction adjustment flag) is set, and the above correction value is subtracted or added to the output of the amplifier on the front stage side based on the flag to correct the correction process. It can be carried out.

  The correction operation of the present invention is not limited to the above example. The relative ratio of the outputs of adjacent amplifiers is obtained, and the relative ratio is used as a correction value, and the output value of the amplifier is multiplied or divided. May be.

  10 microprocessor, 20 smoke detection unit, 21 LD unit, 22 photodiode, 23 current voltage conversion unit, 24 amplifier circuit, 30 environment monitoring / fan control unit, 31 fan voltage control / rotation number monitoring unit, 32 airflow monitoring unit, 33 voltage monitoring unit, 34 voltage monitoring unit, 35 temperature detection unit, 40 status display / acoustic unit, 41 display unit, 42 acoustic unit, 50 transmission / input / output unit, 51 transmission / reception unit, 52 analog output unit, 53 no-voltage contact , 61 Various switches, 62 Non-volatile memory, 63 Non-volatile memory, 64 Real time clock, 65 Dip switch.

Claims (3)

A light emitting device disposed in the smoke detector;
A light receiving element that receives scattered light generated by smoke particles present in the smoke detector, and the light emitted from the light emitting element;
An amplifier circuit for amplifying the output signal of the light receiving element;
A control circuit for determining the occurrence of a fire based on the smoke density corresponding to the output of the amplifier circuit;
In the smoke detector with
The amplifier circuit includes a plurality of amplifiers connected in series, and outputs the output of each amplifier to the control circuit,
The control circuit includes:
The smoke density corresponding to the output of the amplifier is corrected based on the correction value obtained based on the smoke density corresponding to the output of the amplifier and the smoke density corresponding to the output of the amplifier adjacent to the preceding stage. A smoke detector. The control circuit includes:
A switching upper limit value is set for the output of each amplifier, and a switching voltage value (switching voltage value <switching upper limit value) is set for the output of each amplifier except for the first-stage amplifier. The output of the latter-stage amplifier within the range of the switching upper limit value is used to determine the occurrence of a fire, and when the output of the amplifier reaches the switching voltage value, the smoke concentration corresponding to the output of the amplifier, and A correction value is obtained on the basis of the smoke density corresponding to the output of the amplifier on the upstream side, and the smoke density corresponding to the output of the amplifier on the front stage is corrected based on the correction value. Item 2. The smoke detector according to item 1.   When the output of the amplifier reaches the switching voltage value, the control circuit obtains a correction value based on the difference between the smoke density corresponding to the output of the amplifier and the smoke density of the output of the preceding amplifier. In addition, a negative or positive flag is set based on the magnitude of both, and the smoke value corresponding to the output of the amplifier on the preceding stage side is corrected by subtracting or adding the correction value based on the flag. The smoke detector according to claim 2.

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