JPS61228597A - Photoelectric type smoke sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a photoelectric system in which a light emitting unit and a light receiving unit are placed facing each other at a certain distance apart, and a fire is detected from the attenuation of light caused by smoke that has flowed in between the unit installations. Regarding smoke detectors, especially
The present invention relates to a photoelectric smoke detector that compensates for fluctuations in the received light signal due to dirt in the optical system.

(Prior Art) Conventionally, in photoelectric smoke detectors in which a light emitting unit and a light receiving unit are arranged separately, when used for a long time, dust accumulates on the windows of the light emitting unit and the light receiving unit, and the light receiving signal level decreases. If the signal level of the received light signal, which has decreased due to dust, falls below the threshold for determining fire, an erroneous fire signal will be output.

Therefore, cleaning work to remove dust was required at regular intervals.

However, since cleaning work to remove dust is difficult, a device has been devised that automatically compensates the received light signal according to the degree of dust adhesion.
A No. 25 rechargeable smoke detector is known.

In this photoelectric smoke detector, the gain of the operational amplifier that amplifies the light reception signal is varied in stages according to the degree of signal attenuation due to dust accumulation. By increasing the amplification gain by the same amount, it is possible to obtain a received light signal that is in the same state as when no dust is attached.

(Problems to be Solved by the Invention) However, dirt compensation by controlling the gain of an operational amplifier has the following problems.

The first problem is that as a method of varying the amplification gain, the impedance of the resistor network provided in the feedback circuit of the operational amplifier is changed by on/off control of multiple analog switches. This variation in on-resistance makes it impossible to accurately set the feedback impedance, making it difficult to perform linear gain control by switching.

The second problem is that in order to achieve linear gain control by switching, it is necessary to adjust the impedance by installing a large number of variable resistors, which makes the circuit complex and the adjustment work complicated. .

The third problem is that an up/down counter is required to control on/off of a plurality of analog switches, making the gain control circuit complicated.

On the other hand, the dirt compensation method using gain control compares the initial received light data and the current received light data at regular intervals.
Based on the difference, the gain of the operational amplifier is changed to cancel out the difference. However, when the smoke concentration gradually increases, such as in a fire, the signal drop is compensated for by controlling the amplification gain, and there is a risk that the fire may not be detected.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and it is possible to input received light data as it is without modifying it, and perform calculation processing based on the compensation coefficient at that time. An object of the present invention is to provide a photoelectric smoke detector that obtains compensated light reception data.

That is, in the present invention, the initial light reception data obtained when the power is first turned on is stored, and when dirt compensation is performed at predetermined intervals, compensation is performed according to the difference between the initial light reception data and the current light reception data. In order to calculate the compensated light reception data by correcting the ratio and multiplying this compensation v1 by the current light reception data,
In a photoelectric smoke detector, a light emitting unit and a light receiving unit are arranged facing each other at a predetermined distance apart, and the light receiving unit detects a fire by receiving attenuated light due to smoke of pulsed light emitted from the light emitting unit, A storage means stores light reception data at power-on as initial light reception data, and compares the light reception data at that time with the initial light reception data every predetermined dirt compensation cycle, and if a difference occurs between the two, the storage means stores the light reception data at the time of power-on as initial light reception data. a compensation ratio correcting means for correcting the compensation ratio according to the difference; and receiving light reception data obtained at each predetermined cycle shorter than the compensation cycle as is;
To provide a photoelectric smoke detector characterized by comprising a compensation calculation means for obtaining compensated light reception data by multiplication with a compensation ratio at that time, and a fire determination means for determining fire based on the compensated light reception data. It is something.

(Embodiment) FIG. 1 is an explanatory diagram showing an embodiment of the overall configuration of the present invention as a dimming type separation type photoelectric smoke detector.

In FIG. 1, a receiver 10 is installed in a central monitoring room or the like, and receives a fire detection signal from a photoelectric smoke detector and issues a fire alarm together with an indication of the area where the fire occurred. Also,
When a trouble occurs in a photoelectric smoke detector, an inspection alarm signal is received and an alarm is displayed to cause the photoelectric smoke detector to be inspected.

From reception 1110, power supply signal line 161 inspection signal line 1
8 and common line 20 are drawn out, and these signal lines 16
．． 18. - Light receiving units 12a, . . . , 12n of a plurality of photoelectric smoke detectors are connected to 20.

In the photoelectric smoke detector of the present invention, each combination of the light receiving unit 12a and the light emitting unit 14a1 or the light receiving unit 12'n and the light emitting unit 14n constitutes one rechargeable smoke sensor.

For example, if one rechargeable smoke detector is made up of a light receiving unit 12a and a light emitting unit 14a, the light receiving unit 1
The light emitting unit 14a is disposed opposite to the light emitting unit 2a at a predetermined distance in the range of 5 to 100111, for example, a distance of 1511 Wt15. A pair of signal lines 22, 24 are drawn out from the light receiving unit 12a, and a pair of signal lines 22, 24 are drawn out from the light receiving unit 12a,
It is connected to the.

The connection of the signal lines 22 and 24 is the same for the light receiving unit 12n and the light emitting unit 14n.

Furthermore, each unit 12a that constitutes the rechargeable smoke detector,
-, 12n and the light emitting units 14a, -, 14n are each attached to a ceiling surface or the like by a mounting base 15.

FIG. 2 is a block diagram showing the device configuration of FIG. 1, including a light receiving unit 12a and a light emitting unit 14a.
The light receiving unit 12n and the light emitting unit 14n are arranged facing each other at a predetermined distance, and the light emitting unit 14a
, 14n are provided with a light emitting element 26, and are connected to the light receiving unit 128.1 via a signal line 22.24 which also serves as a power supply line.
The light emitting element 26 receives the light emission control signal given from 2n.
is driven to emit light, and the light from the light emitting element 26 is transmitted to the smoke detection area 30.
The light enters the light receiving element 28 provided in the light receiving units 12a, 12n through the light receiving unit 12a, 12n. Therefore, when installing the light receiving unit 12a and the light emitting unit 14a or the light receiving unit 121 and the light emitting unit 14n on a ceiling surface etc., the light emitting element 26
The optical axis is adjusted so that the light from the light enters the light receiving element 28 accurately. Further, the light emitted from the light emitting element 26, passing through the smoke detection area 30, and entering the light receiving element 28 is attenuated by the smoke present in the smoke detection area 30, and the light whose intensity is attenuated according to the smoke concentration. The light then enters the light receiving element 28.

Here, each of the light receiving units 128.12n has a built-in control section using a microcomputer, and the installation of the optical axis, etc. is performed using the light receiving data obtained when the power is first turned on after adjustment as the initial light receiving data. The wJIII for fire judgment is calculated based on the initial light reception data stored in the memory, and each time the light reception data is obtained, it is compared with 1liFj1 to determine a fire, and when it is determined that there is a fire, the power supply signal line 16 is
A fire signal is sent to the receiver 10 via the receiver 10. In addition, the initial light reception data stored in the memory of the microcomputer is used in the control process for dirt compensation, as will be explained later, and when the compensation limit is exceeded in the control process for dirt compensation, the inspection signal line is Received via *io
outputs an inspection alarm signal to indicate that dirt compensation has reached its limit.

Further, the inspection signal line 18 sends an alarm signal for inspection to the receiver 10 even if the initial light reception data stored in the memory when the power is first turned on is abnormal.

FIG. 3 is a block diagram showing the circuit configuration of the light receiving unit used in the photoelectric smoke detector of the present invention, which uses a microcomputer as the control section! be.

In FIG. 3, 32 is a constant voltage circuit, which receives power supply from the receiver and outputs a power supply voltage of, for example, 16V. A large capacity capacitor 34 is connected to the output of the constant voltage circuit 32.
is connected, and even if the power supply from the receiver is temporarily cut off due to a power outage, etc., the voltage charged in the capacitor 34 will supply power to the microcomputer as a control unit for a certain period of time, and the memory of the microcomputer will be saved. The memory of the initial light reception data DI is retained.

Therefore, even if the power supply from the receiver is temporarily cut off,
The initial light reception data Di is not erased.

The capacitor 34 also has the function of smoothing the output voltage from the constant voltage circuit 32.

36 is a control unit using a microcomputer;
For example, an 8-bit microcomputer is used.

A constant voltage circuit 38 supplies power to the control unit 36 using a microcomputer.
8 converts the output voltage of 16V from the constant voltage circuit 32 into a constant voltage of 5V and supplies it to the control section 36.

A power-on reset circuit 40 operates for a predetermined time when the power is turned on and outputs a reset signal until the microcomputer of the control section 36 is started. Note that the predetermined time is the time from when the control section 36 is powered on until a voltage at which it can operate normally is secured.

After receiving this reset signal, the master clock circuit 44
The control unit 36 performs light emission control and light reception control based on the output. The control unit 36 detects that the monitored voltage of the power supply voltage monitoring circuit 56 changes from below a predetermined voltage to above a predetermined voltage, determines that it is initial, and stores the initial light reception data obtained by the light emission control and light reception control in the memory 42. Of course, when storing the initial received light data in the memory 42, a data check is performed to see if the initial received light data is within a predetermined range, and if it is within the range, it is stored in the memory 42, and if it is outside the range. When this happens, an alarm signal for inspection is output to the receiver.

When the storage process of the initial light reception data, which is performed after the power-on reset circuit 40 outputs a reset signal when the power is turned on, is completed, the microcomputer of the control section 36 stops program control and returns to the standby state. The subsequent operations of the control section 36 are performed intermittently based on clock pulses from the master clock circuit 44. The master clock circuit 44 outputs clock pulses to the control section 36 at regular intervals ranging from 2 to 4 seconds, and the control section 36 that receives the clock pulses performs light emission control and light reception control, and the light reception obtained at this time. Compensated light reception data is obtained by inputting the data as is and performing dirt compensation calculation processing, and a fire is determined by comparing the compensated light reception data with a threshold value.

Reference numeral 46 denotes a light emission control circuit, which receives a light emission control signal output by the operation of the control unit 36 based on the master clock, outputs the control signal to the light emitting unit, and controls the light emitting element provided in the light emitting unit by utilizing the discharge of a capacitor. The sensor is pulse-driven to emit light to the light receiving unit to detect smoke.

48 is a light reception control circuit which, like the light emission control circuit 46, operates upon receiving a light reception control signal from the control section 36 which is operated in accordance with the clock pulse of the master clock circuit 44.

That is, the light reception control circuit 48 operates a constant voltage circuit 50 to supply a power supply voltage of 10V to the light reception circuit 52, and also operates a reference voltage generation circuit 54 that outputs a reference voltage, for example 2.5V, for A/D conversion. Furthermore, the power supply voltage monitoring circuit 56 that monitors the output voltage of the constant voltage circuit 32 is activated.

The light receiving circuit 52 includes the light receiving element 28. It has a built-in amplifier circuit and a peak hold circuit, and the light receiving element 28 receives the light emitted from the light emitting unit and converts it into an electrical signal.The amplifier circuit amplifies this received light signal to a specified level, and the peak hold circuit receives the light. Holds the peak level of the signal and outputs it. The light receiving signal output from the light receiving circuit 52 is A
The signal is supplied to the /D conversion circuit 58, converted into, for example, an 8-bit digital signal, and inputted to the control section 36 as received light data. The A/D conversion circuit 58 converts the light reception signal from the light reception circuit 52 into a digital signal based on the reference voltage of 2.5V from the reference voltage generation circuit 54. A sensitivity setting signal from a sensitivity setting circuit 60 is also input to the A/D conversion circuit 58, and the sensitivity setting circuit 60 is connected to the reference voltage generation circuit 54.
The threshold value for fire judgment in the control unit 36 is variably set by extracting the output voltage as different divided voltages by switching a rotary switch or the like. This sensitivity setting circuit 6o
The sensitivity setting signal from is also converted into a digital signal by the A/D conversion circuit 50 and provided to the control section 36. Further, the power supply voltage monitoring circuit 56 monitors the output voltage 16V of the constant voltage circuit 32 based on the signal from the light reception control circuit 48, and
Whether it is 6V or more or less is outputted to the control unit 36 via the A/D conversion circuit 58. If the power is turned on immediately, the constant voltage circuit 32 does not reach 16V immediately, but gradually increases, so the control unit 36 controls the power supply voltage monitoring circuit 56 to reach 16V.
It is determined that it is an initial by determining that the value has changed from less than or equal to V to more than or equal to V.

62 is a fire signal output circuit, which performs a switching operation in response to an output when a fire is determined by the control unit 36, and outputs a fire signal between the power signal line 16 drawn out from the receiver 10 and the common line 20. It sends out a fire signal by passing an electric current through it. Further, 64 is a check signal output circuit, and when the control unit 36 determines that there is an abnormality in the light receiving unit, the receiver 1
Inspection signal line 18 drawn from 0. An inspection signal is sent by passing an inspection current between the common wire 20 and the common wire 20. Here, the fire signal current by the fire signal output circuit 62 and the inspection signal current by the inspection signal output circuit 64 are, for example, 3 at maximum.
It is assumed to be 0 milliampere. On the other hand, in a state where no fire signal or inspection signal is output, the average monitoring current is suppressed to about 250 microamperes.

FIG. 4 is a flowchart showing the control processing of the light receiving unit by the microcomputer of the control section 36 of FIG.

First, when the power is turned on, the power-on reset circuit 40 outputs a reset signal for a predetermined time, and after the reset signal ends,
When the first output signal from the master clock circuit 44 is input, the microcomputer of the control section 36 starts operating. The microcomputer that has started operating first performs light emission and light reception control in block 66. Through this light emission and light reception control, a light reception signal is obtained by the light reception circuit 52 of the light reception unit.
Input the converted light reception data [)n. In the next determination block 70, it is checked whether or not it is initialized.
), the process proceeds to decision block 72, where it is checked whether the first obtained light reception data Qn is within a predetermined range. When the first light reception data On is outside this range, the process proceeds to block 74 and a signal for an inspection alarm is output to the receiver. In other words, if the received light data [)n obtained immediately after the power is turned on is out of a predetermined range, for example, the optical axis between the light receiving unit and the light emitting unit is shifted, and the received light signal level becomes extremely low. This is the case. Therefore, an inspection alarm is issued to readjust the optical axis. Further, if the received light data Dn exceeds a predetermined range, it is possible that the gain adjustment of the amplifier etc. provided in the light receiving circuit 52 is not appropriate. In this case as well, an inspection warning for readjustment is issued.

On the other hand, when the received light data [)n is within the predetermined range, the process proceeds to block 76, where the received light data [)n is stored in the memory 42 of the microcomputer as the initial received light data Di. In this way, even if the power supply from the receiver is completely stopped, the initial light reception data Di stored in the memory 42 is stored and retained for a predetermined period of time due to the charge of the internal capacitor 34, and even if the power supply is completely stopped, etc. will not be deleted.

When the storage of the initial light reception data D1 is completed, the process proceeds to block 78, dirt compensation processing, and this dirt compensation processing is performed in the fifth step.
This will be explained in more detail by the block diagram of FIG. 6 and the flowchart of FIG.

In the dirt compensation processing of block 78, the received light data [)n is multiplied by a compensation ratio N that compensates for the attenuation of light due to dirt on the windows of the light receiving unit and the light emitting unit. Find and ru.

In block 80, a fire is determined by comparing the compensated received light data [)a obtained in the dirt compensation process 78 with a threshold value calculated based on the initial received light data Di. Specifically, multiple compensated light reception data obtained at each fixed detection period based on the master clock are obtained as light reception data for fire judgment using the moving average method, and when this light reception data is below a predetermined threshold, It is determined that a fire has occurred when this continues for a certain period of time. As a result of the fire determination processing in block 80, when it is determined that there is a fire in determination block 82, the process proceeds to block 84, where a fire signal is output to the receiver. If it is not determined that there is a fire, the fire signal output processing in block 84 is not performed, and the process directly proceeds to block 86 to stop the control, return the microcomputer to the standby state, and receive the next clock pulse.

FIG. 5 is a block diagram showing the functions of the microcomputer that executes the tI11m process shown in FIG. Compensation counter 92. It is composed of a compensation calculation means 94 and a fire judgment means 96.

That is, the initial light reception data storage means 88 stores the light reception data [)m as the initial light reception data Di only when the power supply voltage monitoring circuit 56 determines that the voltage has exceeded a predetermined voltage upon power-on. Of course, when storing the initial light reception data, the condition is that the light reception data is within a predetermined range. Compensation ratio correction means 90. The functions of the compensation counter 92 and the compensation calculation means 94 will be further clarified by the dirt compensation process shown in the flowchart of FIG. In addition, the compensation calculation means 94 uses light reception data obtained by light emission and light reception control based on the master clock [
)n, performs dirt compensation, calculates and outputs compensation data Oa,
It is given to the fire judgment means 96.

FIG. 6 is a flowchart showing dirt compensation processing performed in the light receiving unit in the photoelectric smoke detector of the present invention, and is controlled by a program of a microcomputer constituting the control section or by the compensation ratio correction means shown in FIG. 90
．． The function block for dirt compensation processing is executed by a compensation counter 92 and a compensation calculation means 94.

Therefore, to explain the dirt compensation processing shown in FIG. 6, first, in block 100, a compensation counter is incremented. This compensation counter can be implemented as a program counter. The compensation counter counts the master clock that is output at a certain period, for example within a range of 2 to 4 seconds.
A full count is reached in a counting time of minutes, producing a counter output for performing the dirt compensation process. That is, the count value of the compensation counter is monitored by the determination block 102, and when the counting time of the counter reaches 50 minutes, which is the compensation period, compensation processing starting from block 104 is started.

The principle of dirt compensation processing performed in the processing after block 104 is as follows.

The current light reception data obtained by light emission and light reception control based on the instant Otsuk pulse is Dnq, and the compensation ratio at this time is N.
Then, the compensated light reception data [)a is Da −Dn
It is determined by XN - (1).

The compensation ratio N in this equation (1) is N-1/(1-
/100) -...(2) is defined. Here, K is a compensation coefficient, which becomes -0 in the initial state, and -1, 2, 3, etc. when the received light data decreases due to dirt.
increases sequentially with each compensation cycle, and as the received light data increases, the values also increase with each compensation cycle -1, -2, -3, -...
It takes a value that decreases sequentially. That is, if the initial light reception data D1 and the current light reception data [)n do not match, the compensation ratio N is corrected by increasing or decreasing the compensation coefficient K by ±1 every compensation period.

Therefore, to specifically explain the stain compensation processing after block 104, first, in block 104, a compensation counter is cleared. Next, in block 106, the previous compensation ratio Nn-
1 and the current light reception data [)n, the above (1) and (2)
Compensated light reception data Da is calculated from the formula.

Once the compensated light reception data Da has been calculated in block 106, the process proceeds to decision block 108, where it is checked whether the compensated light reception data □a is equal to the initial light reception data D1. At this time, if there is no dirt, it becomes [)a-Di, but if there is dirt, the compensated light reception data Da becomes smaller, and the process proceeds to the next judgment block 110 to check the magnitude relationship between the compensation light reception data Da and the initial light reception data Qi. Discern. If the compensated light reception data [)a is larger than the initial light reception data Di in the comparison judgment of this judgment block 110, the process proceeds to block 112 to reduce the compensation ratio N. In other words, when Qa > Qi, the previous compensation ratio Nrow 1 used to calculate the compensated received light data Qa in block 106 is too large, so that the compensated received light data ()a, which is larger than the initial received light data Qi, is Therefore, in block 112, a new modified correction coefficient )(n is calculated as Kn - Kn-1-1''' (3).

On the other hand, when it is determined in the determination block 110 that [)a > [)i, the process proceeds to block 114, where Kn −Kn−
A new compensation coefficient Kn corrected by 1+1.-(4) is calculated.

The correction of the compensation coefficient in block 114 is performed because the previous compensation ratio Nn-1 used to calculate the compensated light reception data [)a in block 106 is too small.
<Qi, and dirt compensation is insufficient. Therefore, by increasing the compensation coefficient Kn-1 by +1 using the above formula (4), a new compensation coefficient )(n is calculated, and the value of the compensation ratio N given by the above formula (2) with the increase in n) will also increase.

The amount of change in the compensation coefficient due to one correction in blocks 112 and 114 is ±1, and therefore the change in the compensation ratio is also suppressed to a minute value.

In block 112 or 114, a new compensation coefficient) (Once n has been calculated, proceed to the next block 116, and use the corrected compensation coefficient) (n again to calculate the compensated light reception date: 9Da.
is calculated according to equations (1) and (2) above.

That is, when correcting Qa<[)i to )(n-Kn-1+'l), the compensation ratio N also increases, and compensated light reception data Da that is even closer to the initial light reception data Di is calculated.Also, [)a >[)i When the correction is made to)(n −)(n-1-1), the compensation ratio N also decreases, and similarly compensated light reception data closer to the initial light reception data Di is calculated.

Subsequently, in decision block 118 it is checked whether the new compensation factor 1 (n) modified in block 112 or 114 is within predetermined limits.

As an example, the range in which the compensation coefficient Kn changes is limited to the following range: +50>Kn>-20-(5). Therefore, the compensation coefficient for each compensation cycle)
(If the correction of n reaches Kn-50 or Kn-20, it is judged that it is no longer possible to compensate for contamination by signal processing because it is out of the range of equation (5), and the process proceeds to block 120 for inspection. A signal for warning is outputted to the receiver to prompt cleaning of dirt adhering to the windows of the light emitting unit and the light receiving unit.

The dirt compensation shown in the flowchart of FIG. 6 will be explained using specific numerical values as follows.

First, the initial light reception data DiffiDi-100 is the light reception data Dn obtained in the current compensation cycle.
95, and the previous compensation coefficient Kn-1 is )(n-1-Q
Suppose it was.

Since the compensation data [)a calculated in block 106 is the compensation coefficient Kn-1=O, from the above (1) and (2), Q
a-[)n-95.

Since the compensated light reception data [)a is smaller than the initial light reception data D1, the process proceeds to block 114. In block 114, the compensation coefficient is modified as Kn - Kn-1+ 1 =O+ 1-1.

Next, in block 116, the corrected compensation coefficient Kn=1 is used to calculate the compensated received light data [)a as Da-95x(1/(1
-1/100)) -95,95.

If the current received light data Dn-95 is similarly obtained in the next compensation cycle, the compensation coefficient is set to Kn-2 in block 114.
Da −95X ((1
-2/100)) -〇〇. 9 is calculated.

Similarly, the compensation coefficient Kn for each compensation period is )(n-3,
The number increases by 4, 5, and so on.

That is, in order to bring the current received light data Dn-95 closer to the initial received light data Di, the compensation coefficient is
n-0, 1, 2, 3, 4, 5, and therefore the compensation ratio given by the above equation (2)' is 1. tN=1.00,
It increases as 1.01, 1.02, 1°03.1.04.1.05. Therefore, even if it does not change from the current received light data Dn-95, the compensated received light data [)a is Da-95,00,
95,95,96,94,97,94,98,96,1
Increases to 00,00. In this way, in the fifth compensation cycle, the compensated light reception data matches the initial light reception data, and Qa
As long as the relationship -[)i is maintained, dirt compensation is performed using the compensation ratio N-1,05 determined by the compensation coefficient Kn-5.

Conversely, when the current received light data Dn exceeds the initial received light data, the compensation coefficient Kn is determined by block 112 as Kn =O, -1. -2. -3°... decreases with each compensation cycle, so the compensation ratio N is N-1,00,0,9
The angle decreases as 9, 0, 98, 0, 97°, etc., and the compensated light reception data (a) becomes closer to the initial light reception data Di.

In the calculation of the compensation process in actual program processing, for example, if the data is 8 bits, the calculation process is executed as 56Da-256 (Dn x1/(1-Kn/100)).

In addition, in the flowchart of FIG. 6, the repair coefficient Kn is increased or decreased by 1 (n-±1) every compensation cycle, but if the change in the compensation ratio N is a minute value, the compensation coefficient can be increased or decreased by ±2. ．±
3. You may change it as follows. The value of change in this compensation coefficient can be arbitrarily determined within a range that does not exceed the change in received light data in a fire.

Furthermore, although the present invention has been described as a dimming type separate photoelectric smoke detector, an integrated photoelectric smoke detector in which the light emitting unit and the light receiving unit of the present invention are integrally provided in one chamber may also be used. can also be applied as is.

(Effects of the Invention) As explained above, according to the present invention, the received light data is input as is without modification, without using hardware dirt compensation such as variable amplification gain, and the compensation coefficient at that time is Since the compensated received light data is obtained through calculation processing based on the calculation process, it is possible to accurately compensate for the contamination of the received light data according to the degree of contamination of the optical system, allowing highly reliable fire monitoring to continue over a long period of time. be able to.

In addition, since the compensation rate is adjusted to a small predetermined value at a time, even if the smoke concentration gradually increases as in the case of a smoke fire, the compensation rate will not change as the smoke concentration increases. It is possible to reliably prevent corrections and to reliably detect fires caused by burning without being affected by dirt compensation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the device configuration of the present invention,
22 is a block diagram showing the device configuration of the present invention, FIG. 3 is a block diagram showing an embodiment of the receiving unit of the present invention, FIG. 4 is a general flowchart showing program control processing of the light receiving unit, and FIG. FIG. 5 is a block diagram showing a dirt compensation processing circuit according to the present invention, and FIG. 6 is a flowchart showing dirt compensation processing executed by program control of the light receiving unit of the present invention. 10: Receivers 12a to 12n: Light receiving units 14a to 14n: Light emitting unit 16: Power supply signal line 18: Inspection signal line 20: Common line 22.24: Signal line 26: Light emitting element 28: Light receiving element 30: Smoke detection area 32.38.50: Constant voltage circuit 34: Capacitor 36: Control unit 40: Power-on reset circuit 42: Memory 44: Master clock circuit 46: Light emission control circuit 48: Light reception control circuit 52: Light reception circuit 54: Reference voltage generation circuit 56: Power supply voltage monitoring circuit 58: A/D conversion circuit 60: Sensitivity setting circuit 62: Fire signal output circuit 64: Inspection signal output circuit 8th: Initial light reception data storage means 90: Compensation coefficient correction means 92: Compensation counter 94 : Compensation calculation means 96 2 Fire judgment means

Claims (1)

[Claims] A photoelectric smoke device in which a light-emitting unit and a light-receiving unit are arranged facing each other at a predetermined distance apart, and the light-receiving unit receives attenuated light due to smoke of pulsed light emitted from the light-emitting unit to detect fire. In the sensor, a storage means stores light reception data at the time of power-on as initial light reception data, and a storage means that compares the light reception data at that time with the initial light reception data at every predetermined dirt compensation cycle, and records a difference between the two. Compensation ratio correction means for correcting the compensation ratio according to the difference when a difference occurs; and a compensation ratio correction means that inputs the received light data obtained at each predetermined cycle shorter than the compensation cycle as it is and multiplies it by the compensation ratio at that time to calculate the compensated light reception. A photoelectric smoke detector characterized by comprising a compensation calculation means for calculating data, and a fire determination means for determining a fire based on the compensated light reception data.