JPH07220184A - Fire sensor - Google Patents

Abstract

PURPOSE:To exactly detect physical quantity corresponding to a fire phenomenon even when the environmental temperature of the fire sensor is different by compensating the output voltage of a smoke sensor by multiplying a voltage compensation coefficient to the output voltage of the smoke sensor at monitoring time. CONSTITUTION:A ROM 20 stores the output voltage of a surrounding temperature detection part 70 for the smoke sensor or the like at manufacture time such as sensitivity setting time, the surrounding temperature of the smoke sensor at manufacture time, voltage vs. temperature table and temperature vs. compensation coefficient table, and voltage difference is calculated between the output voltage of the surrounding temperature detection part 70 at manufacture time and the output voltage of the smoke sensor at monitoring time. Then, the output voltage of the smoke sensor is compensated by converting the voltage difference to surrounding temperature difference based on the voltage vs. temperature table, converting a temperature, for which a surrounding temperature at manufacture time is added to this surrounding temperature difference, to the voltage compensation coefficient baesd on the temperature vs. compensation coefficient table and multiplying the calculated voltage compensation coefficient to the output voltage of the smoke sensor at monitoring time or the like. Therefore, even when the characteristics of electric components are dispersed, smoke concentration can be exactly detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature compensation of a fire detector in which a physical quantity detecting element such as a smoke sensor detects a physical quantity corresponding to a fire phenomenon.

[0002]

2. Description of the Related Art In a conventional fire detector, for example, a smoke fire detector, a light emitting element and a light receiving element are provided in a smoke chamber, light emitted from the light emitting element is diffusely reflected by smoke, and the diffusely reflected light is received. The element receives, the amplifier amplifies the output level of the light receiving element, and the smoke density is determined based on the level of the amplified signal.

[0003]

The temperature of the fire detector differs depending on the environment in which the fire detector is installed, and the ambient temperature of the fire detector also differs depending on the installation place. That is, in the vicinity of the roof of the building, the temperature becomes extremely high due to solar heat, and the temperature of the basement and the like made of non-insulated concrete becomes extremely low, and the temperature conditions greatly differ between them. Furthermore, the environmental temperature of the fire detector is greatly affected by the climate associated with the latitude of the installation location and the presence or absence of air conditioning such as heating and cooling.

On the other hand, the sensitivity of the fire detector is adjusted at the time of manufacture under substantially constant temperature conditions. Here, when the sensitivity of the fire detector fluctuates due to temperature, there is a problem that the sensitivity fluctuates depending on the installation location even after the sensitivity is properly adjusted during the adjustment.

For example, when an LED is used as the light emitting element and a photodiode is used as the light receiving element, L
The light emission amount of the ED has a temperature characteristic of −0.6% / ° C., and the output level of the photodiode has a temperature characteristic of + 0.2% / ° C. Therefore, the total temperature characteristic of the LED and the photodiode is -0.6% / ° C + 0.2% / ° C =-
0.4% / ° C. For this reason, even if the actual smoke density is the same, if the temperature inside the smoke fire detector changes when the smoke density is detected, the output voltage of the light receiving element will be -0.4% / ° C.
fluctuate. That is, when the temperature inside the smoke fire detector changes by 50 ° C., the output level of the light receiving element changes by 20%.

Further, like the light emitting element and the light receiving element, an amplifier circuit composed of semiconductor elements also has a temperature characteristic, and if the temperature inside the fire detector changes, the output level is changed by the temperature characteristic of these semiconductor elements. fluctuate.

Therefore, the output level is affected by the combined temperature characteristics of the constituent parts of the fire detector, and the fluctuation characteristics are not monotonic with respect to the temperature, but the temperature compensating elements such as thermistors that have been conventionally used. However, the compensation method using does not allow sufficient temperature compensation.

The above-mentioned problems occur not only in photoelectric smoke fire detectors but also in other smoke fire detectors. Further, a temperature sensor using a thermistor, a pyroelectric sensor for detecting a flame, The same applies to a fire detector using an odor sensor using a semiconductor element.

The present invention can accurately detect a physical quantity corresponding to a fire phenomenon even if the environmental temperature of the fire detector is different and the characteristics of the electric parts used in the fire detector vary. The object is to provide a fire detector that can be used.

[0010]

According to the present invention, an output voltage of an ambient temperature detecting portion such as a smoke sensor at the time of manufacturing when sensitivity is set, an ambient temperature of a smoke sensor at the time of manufacturing, and a voltage vs. temperature table are provided. , A temperature-compensation coefficient table is stored in the memory, and the voltage difference between the output voltage of the ambient temperature detection unit during manufacturing and the output voltage of the smoke sensor during monitoring is calculated,
Based on the voltage vs. temperature table, the above voltage difference is converted to the ambient temperature difference, and the temperature obtained by adding the ambient temperature during manufacturing to this ambient temperature difference is converted into the voltage compensation coefficient based on the temperature vs. compensation coefficient table. By multiplying the output voltage of the smoke sensor at the time of monitoring by the obtained voltage compensation coefficient,
The output voltage of the smoke sensor is compensated.

[0011]

According to the present invention, the voltage difference between the output voltage of the ambient temperature detecting portion of the smoke sensor during manufacturing and the output voltage during monitoring is calculated, and the calculated voltage difference is calculated based on the voltage vs. temperature table. Converted to a difference, the current temperature obtained by adding the ambient temperature at the time of manufacturing to this ambient temperature difference, based on the temperature vs. voltage compensation coefficient table, converted to a voltage compensation coefficient, to the output voltage of the smoke sensor at the time of monitoring, Since the smoke sensor output voltage is compensated by multiplying the obtained voltage compensation coefficient, etc., even if the environmental temperature of the fire detector is different, the electric power used for the ambient temperature detection part in the fire detector Even if the characteristics of the parts vary, the smoke density can be accurately detected.

[0012]

1 is a block diagram showing a smoke fire detector 1 according to an embodiment of the present invention.

In this embodiment, a microcomputer (microcomputer) 10 controls the entire smoke fire detector 1, and a ROM 20 stores a program of a flow chart shown in FIG. 2 and a table described later. The RAM 21 is a work area and corresponds to the voltage V _X corresponding to the temperature measured by the ambient temperature detection unit 70 and the concentration held by the sample hold circuit 42 holding the signal output value of the amplifier circuit 40. The voltage SLV and the smoke density data SLV _C after temperature compensation are stored.

The EEPROM 22 stores the self-address of the smoke fire detector 1, the ambient temperature T _S when the sensitivity of the smoke fire detector 1 is set, and the output voltage V of the ambient temperature detector 70 when the sensitivity is set. It stores _S and.

The light emitting circuit 30 supplies a current pulse for light emission to the light emitting element 31 when receiving a light emission control pulse from the microcomputer 10, and the amplifier circuit 40 sets the output level of the light receiving element 41 to a predetermined gain. It is to be amplified by. The sensitivity of the fire detector 1 is set by adjusting the amplification factor of the amplifier circuit 40.

The transmission / reception circuit 50 is a transmission circuit for transmitting a signal such as a fire signal or a physical quantity signal of smoke from the microcomputer 10 to a receiver (not shown) and a reception circuit for transmitting a signal such as a polling signal from the receiver to the microcomputer 10. And have. The confirmation lamp 51 is lit when the smoke fire detector 1 detects a fire, and the constant voltage circuit 60
Is a circuit that supplies a constant voltage to the microcomputer 10.

The ambient temperature detector 70 detects the ambient temperature of the smoke fire detector 1, and actually detects the temperature inside the smoke fire detector 1 and is provided inside the smoke fire detector 1. The diodes D1 and D2 and the diodes D1 and
It is composed of a resistor R1 connected in series with D2.
That is, one end of the resistor R1 is connected to the power supply _Vcc, and the resistor R1
The other end of 1 is connected to the anode terminal of the diode D1,
The cathode terminal of the diode D1 is connected to the anode terminal of the diode D2, the cathode terminal of the diode D2 is grounded, and the connection terminal between the other end of the resistor R1 and the anode terminal of the diode D1 is the output terminal of the ambient temperature detection unit 70. .

The ambient temperature detector 70 detects the ambient temperature of the smoke fire detector 1 by utilizing the temperature characteristic of the voltage across the diodes D1 and D2.
The diodes D1 and D2 are preferably provided near the light emitting element 31 and the light receiving element 41.

The ROM 20 also has a voltage-temperature table used when converting voltage data into temperature data,
A temperature-to-voltage compensation coefficient table used when converting temperature data into a voltage compensation coefficient, and an analog conversion table that converts smoke density data of digital data into an analog amount to be transmitted to a receiver such as a fire receiver (not shown). It is something to remember. Actually, the voltage-temperature table is a table used when converting the voltage difference into the temperature difference, and the temperature-voltage compensation coefficient table is a table used when deriving the voltage compensation coefficient K from the temperature difference. The voltage compensation coefficient K is a coefficient for correcting the output voltage (smoke concentration data) SLV of the sample hold circuit 42 according to the ambient temperature of the smoke fire detector 1.

Next, the operation of the above embodiment will be described.

FIG. 2 shows the microcomputer 1 in the above embodiment.
7 is a flowchart showing an operation performed by 0.

First, the initial value is set (S1), and when a predetermined time, for example, 3 seconds has elapsed (S2), the voltage V _X corresponding to the temperature at the time of monitoring, which is measured by the ambient temperature detecting unit 70.
(The voltage converted into digital data by the A / D converter of the microcomputer 10) is taken in, the output voltage V _S of the ambient temperature detector 70 at the time of sensitivity setting is read from the EEPROM 22 (S3), and the temperature corresponding voltage V at the time of monitoring is read. _The voltage difference ΔV is obtained by subtracting the voltage V _S corresponding to the ambient temperature when the sensitivity is set from _X
The microcomputer 10 executes a calculation for obtaining (S
4) Based on the voltage-temperature table stored in the ROM 20, the voltage difference ΔV is converted into the ambient temperature difference ΔT (S5).

Further, the temperature T _S at the time of sensitivity setting is read from the EEPROM 22 (S6), and the temperature T _S at the time of sensitivity setting is read.
By adding the ambient temperature difference ΔT to the ambient temperature difference ΔT, the microcomputer 10 calculates the ambient temperature (that is, the present temperature) T _{X in} which the error due to the temperature characteristics of the diodes D1 and D2 is eliminated (S7), The voltage compensation coefficient K is obtained from the current temperature T _X based on the temperature-voltage compensation coefficient table stored in the ROM 20 (S8).

Then, the microcomputer 10 takes in the voltage SLV corresponding to the smoke density held by the sample hold circuit 42 (S9), and the obtained voltage compensation coefficient K is added to the voltage SLV corresponding to the smoke density at the time of monitoring. Multiply by to obtain smoke density data SLV _C after temperature compensation (S
10) Then, the smoke density data SLV _C after the temperature compensation is converted into the analog value SLV _a based on the analog conversion table and stored in the RAM 21 (S11), and the process returns to step S2.

When returning to step S2, if there is a call from the receiver within a predetermined time (S12), the analog value SLV by the smoke density data SLV _C after temperature compensation is obtained.
_A is sent to the receiver (S13).

That is, in the above embodiment, first, the voltage based on the temperature at the time of monitoring is detected, and the voltage at the time of sensitivity setting is subtracted from this voltage, so that the difference between the voltage at the time of monitoring and the voltage at the time of sensitivity setting is calculated. The temperature difference is obtained, a temperature compensation coefficient corresponding to the temperature obtained by adding the temperature at the time of setting the sensitivity to the temperature difference is obtained, and the smoke concentration data is multiplied by the obtained temperature compensation coefficient to correct the smoke concentration data. Here, when obtaining the temperature at the time of monitoring, in the above embodiment, the temperature difference between the temperature at the time of monitoring and the temperature at the time of sensitivity setting is obtained, and the temperature at the time of sensitivity setting is added to this temperature difference to obtain the temperature at the time of monitoring. It seems that the temperature is being calculated, and it seems to be a useless step, but there is an important significance in obtaining the temperature difference between the temperature at the time of monitoring and the temperature at the time of setting sensitivity.

In the above embodiment, when obtaining the temperature difference between the temperature at the time of monitoring and the temperature at the time of setting sensitivity, the voltage corresponding to the temperature at the time of sensitivity setting is subtracted from the voltage corresponding to the temperature at the time of monitoring. At this stage, the variation in the voltage of each diode is canceled. That is, there is almost no individual difference in the temperature characteristics of the diode (voltage change due to temperature change), and the diode used when obtaining the voltage corresponding to the temperature during monitoring and the voltage corresponding to the temperature during sensitivity setting are obtained. Since the diode used at the same time is the same, and the difference between the two voltages obtained by the same diode is obtained, the obtained voltage difference has an error due to the characteristics of the diode (error due to variations in the forward voltage of the diode). It will not be included. Therefore, the temperature difference from the set temperature can be accurately obtained.

The temperature characteristic of the voltage across the diode D1 is −
It is said that it is 2 mV / ° C, but there is variation in the forward voltage of the diode D1.
Some are 5V. Therefore, when a diode having a forward voltage of 0.45V and a diode having a forward voltage of 0.55V are used, the difference between them is 0.1V. In this case, a diode having a forward voltage of 0.45V is used. With a fire detector,
There is a temperature measurement error of 50 ° C. with a fire detector using a diode with a forward voltage of 0.55V. But,
In the above embodiment, no error occurs due to variations in the forward voltage of the diode.

Further, in the above embodiment, the temperature compensation coefficient corresponding to the present temperature is obtained, and the smoke concentration data is corrected by multiplying the obtained temperature compensation coefficient by the smoke concentration data. The property is removed. As the smoke density data to be multiplied by the temperature compensation coefficient, a converted analog value may be adopted instead of the voltage taken in by the microcomputer.

In the above embodiment, the resistor R1 is the power source V
_The diodes D1 and D2 are connected to the _cc side, and the diodes D1 and D2 are connected to the ground side. However, if the voltage of the power supply V _cc does not change depending on the temperature, the resistor R1 is connected to the ground side, contrary to the above, and the diode D1 is connected. , D2 may be connected to the power supply _Vcc side.

FIG. 3 is a block diagram showing a smoke fire detector 2 which is another embodiment of the present invention.

The smoke fire detector 2 shown in FIG. 3 is basically the same as the smoke fire detector 1 shown in FIG. 1, except that an ambient temperature detector 71 is provided instead of the ambient temperature detector 70. It is a thing.

The ambient temperature detecting section 71 detects the temperature inside the smoke fire detector 2, and includes a transistor TR provided near the light emitting element 31 and the light receiving element 41 and a resistor connected to the transistor TR. It consists of and.
That is, the transistor TR is a PNP type transistor, the resistors R2 and R3 are an emitter resistor and a collector resistor, respectively, and the resistors R4 and R5 apply the divided voltage to the base of the transistor TR. . Note that the ambient temperature detecting unit 71 uses the transistor TR.
The ambient temperature is detected by utilizing the temperature characteristic of the voltage between the base and the emitter. The temperature characteristic of the voltage between the base and the emitter of this transistor is similar to the temperature characteristic of the diode used in FIG. 1, and the same method as described above is used.

The base voltage of the transistor TR is the resistance R
4 and R5 maintain a substantially constant value, and when the base-emitter voltage of the transistor TR changes due to temperature, the change value occurs as a change in the forward voltage of the resistor R2. The resistor R2 has an emitter current Ie.
However, assuming that the collector current Ic is flowing through the resistor R3 and the current amplification factor of the transistor TR is sufficiently large, the relation of Ic = Ie is approximately obtained.

If the base-emitter voltage changes by Δv depending on the temperature, the forward voltage of the resistor R2 also changes by Δv, and as a result, the change ΔIe of the emitter current becomes Δv / R2. The change of ΔIe is equivalently caused as a change ΔIc of the collector current, and the forward voltage of the resistor R3 detected by the A / D converter of the microcomputer 10 is Δ.
Only v × R3 / R2 will change. Where R3>
When configured to be R2, the variation value Δv of the base-emitter voltage is A / A as a value amplified by R3 / R2.
It is detected by the D conversion unit, which improves the accuracy in detecting the temperature change.

An NPN transistor may be used instead of the PNP transistor used in FIG. 3, and at this time, the same effect as described above is produced. In this case, the resistors R2 and R4 are connected to the emitter and the base, the other ends of the resistors R2 and R4 are connected to the ground, the resistors R3 and R5 are connected to the collector and the base, and the other ends of the resistors R3 and R5 are connected. It may be connected to the power source _Vcc .

Between the resistor R1 in FIG. 1 and the power supply V _CC ,
A switch (not shown) is provided between the resistors R4 and R2 in FIG. 3 and the power supply V _CC, and only when the temperature is detected,
The microcomputer 10 may turn on the switch, whereby the current consumption of the temperature detection units 70 and 71 can be reduced. That is, the temperature detecting means receives power supply through the control means for controlling power supply,
Only when the temperature is detected, the control means supplies the power to the temperature detection means.

In the above embodiment, the smoke fire detector 1,
When the internal temperature of 2 changes, the output level of the light receiving element 31 is corrected and converted into an analog value, but the output level of the light receiving element 31 should be compared with a predetermined reference level, for example, a fire determination reference level. When the smoke density is detected by, the above reference level may be corrected according to the temperature change inside the smoke fire detectors 1, 2.

In each of the above embodiments, the case where the detected physical quantity signal of smoke is sent to the receiver has been described.
Similarly, in the case where the smoke fire detector discriminates the fire by itself and sends out the fire signal, the output voltage SLV of the sample hold circuit 42 is similarly based on the temperature corresponding voltage V _X output from each of the ambient temperature detecting units 70 and 71. Alternatively, the fire discrimination reference level may be corrected.

The temperature compensation coefficient stored in the EEPROM 22 should be stored as an appropriate value for each fire detector so that it will be a value that is inconsistent with the temperature fluctuation characteristics shown by the fire detector when temperature compensation is not performed. You can When the temperature fluctuation characteristics of each fire detector are uniform, the same effect as above can be obtained by storing the temperature compensation coefficient common to each fire detector in the ROM.

Further, although the above embodiment is the smoke fire detector, at least one of physical quantity detecting elements such as a temperature sensor, a pyroelectric sensor (infrared sensor), and an odor sensor can detect a physical quantity corresponding to a fire phenomenon other than smoke. You may make it apply the said Example to the fire detector to detect. Although the above embodiment converts the output value of the fire detection circuit into an analog value and outputs the analog value, the above embodiment may be applied to a fire detector that directly sends the output value of the fire detection circuit. The above embodiment may be applied to a fire detector that determines a fire based on the output value of the fire detection circuit and sends out a fire signal.

Further, in the above embodiment, the output voltage of the sample hold circuit 42 is used as the smoke density data, but the output level of the physical quantity detecting element related to the fire such as the current and the light quantity other than the voltage is used as the smoke density data. You may.

In the above embodiment, the output level of the physical quantity detecting element is measured at a predetermined time other than the sensitivity setting in the manufacturing of the fire detector, other than the sensitivity setting, and at the time of installing the fire detector. However, the temperature at this time is also measured at the same time, and these output levels and temperatures are recorded in the EEPROM 22.
It may be stored in. That is, the EEPROM 22 may store the predetermined-time output level that is the output level of the physical quantity detection element at the predetermined time and the predetermined-time ambient temperature that is the ambient temperature of the physical quantity detection element at the predetermined time. Further, the ROM 20 stores an output level vs. temperature table which is data corresponding to the output level of the physical quantity detection element and a temperature vs. voltage compensation coefficient table which is data corresponding to level compensation coefficient for compensating the output level.
It may be stored in.

The microcomputer 10 and ROM
20 is a level difference calculation means for calculating the level difference between the output level at the time of monitoring, which is the output level of the physical quantity detection element at the time of monitoring the fire detector, and the output level at the predetermined time, based on the output level vs. temperature table. First converting means for converting the level difference into an ambient temperature difference, and a monitoring ambient temperature obtained by adding an ambient temperature at a predetermined time to the ambient temperature difference obtained by the first converting means, based on a temperature-voltage compensation coefficient table,
Second conversion means for converting to a level compensation coefficient, output level compensation means for compensating the output level of the physical quantity detection element by multiplying the output level of the physical quantity detection element at the time of monitoring by the level compensation coefficient obtained by the second conversion means Is an example of.

[0045]

According to the present invention, even if the environmental temperature of the fire detector is different and the characteristics of the electric parts used in the fire detector vary, the physical quantity corresponding to the fire phenomenon can be accurately determined. The effect that it can be detected is exhibited.

[Brief description of drawings]

FIG. 1 is a block diagram showing a smoke fire detector 1 which is an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation executed by a microcomputer 10 in the above embodiment.

FIG. 3 is a block diagram showing a smoke fire detector 2 according to another embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Smoke fire detector, 10 ... Microcomputer, 20 ... ROM, 21 ... RAM, 22 ... EEPROM, 30 ... Light emitting circuit, 31 ... Light emitting element, 40 ... Amplifying circuit, 41 ... Light receiving element, 70, 71 ... Surroundings Temperature detection unit, V _X ... voltage corresponding to the temperature measured by the ambient temperature detection unit 70, SLV ... voltage corresponding to the concentration held by the sample hold circuit 42, V _S ... ambient temperature detection unit 70 at the time of sensitivity setting Output voltage, ΔV ... voltage difference (V _X −V _S ), ΔT ... ambient temperature difference, T _S ... ambient temperature when setting sensitivity, T _X ... current temperature (T _S + ΔT), K ... as a level compensation coefficient Voltage compensation coefficient, SLV _C ... smoke density data after compensation.

Claims (3)

[Claims] 1. A fire detector in which a physical quantity detecting element detects a physical quantity corresponding to a fire phenomenon, and a predetermined time output level which is an output level of an ambient temperature detecting section at a predetermined time, and a physical quantity detecting element at the predetermined time. A predetermined time ambient temperature that is the ambient temperature, an output level vs. temperature table that is the corresponding data of the output level of the ambient temperature detection unit and the temperature, and a level compensation coefficient that compensates the temperature and the output level of the physical quantity detection element. Storage means for storing a temperature-compensation coefficient table which is corresponding data; and a level difference between a monitoring output level which is an output level of the ambient temperature detecting part and a predetermined time output level when the fire detector is monitored. Level difference calculation means for calculating; first conversion means for converting the level difference into an ambient temperature difference based on the output level vs. temperature table; Second conversion means for converting the monitored ambient temperature obtained by adding the ambient temperature difference at the predetermined time to the ambient temperature difference obtained by the first conversion means to a level compensation coefficient based on the temperature versus compensation coefficient table; Output level compensating means for compensating the output level of the physical quantity detecting element by using the level compensating coefficient obtained by the second converting means for the output level of the physical quantity detecting element during the monitoring. Characteristic fire detector. 2. The fire detector according to claim 1, wherein the physical quantity detection element is at least one of a smoke sensor that detects smoke density, a temperature sensor, a pyroelectric sensor, and an odor sensor. 3. The fire detector according to claim 1, wherein the ambient temperature detecting unit uses a temperature characteristic of a voltage across a diode or a temperature characteristic of a base-emitter voltage of a transistor.