JP2922423B2 - Heat detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sensor such as an on / off type heat sensor and an analog type heat sensor.

[0002]

2. Description of the Related Art In general, a heat detector uses a temperature detecting element as a sensor for heat generated from a fire, and monitors an electric signal from the temperature detecting element to detect the occurrence of a fire. FIG. 8 is a diagram showing a configuration example of such a heat detector. Referring to FIG. 8, this heat sensor includes a temperature detecting element 1 for detecting an environmental temperature, a signal detecting resistor 2 connected in series with the temperature detecting element 1, and a power supply voltage E on a line 3. join, in a case where the line 4 is kept at ground potential, monitoring the potential V _s of the midpoint 5 of the temperature detecting element 1 and the signal detecting resistor 2, the predetermined signal processing based on the potential V _s And a signal processing unit 6 for performing the processing.

Here, the temperature detecting element 1 has a resistance value R
_TH0 changes according to the environmental temperature T as in the following equation.

[0004]

R _TH0 = R _b0 · f (T)

In equation (1), _Rb0 is a constant resistance value independent of temperature T, and f (T) is a temperature function. For example, a thermistor (NTC)
A thermistor, a PTC thermistor, or a CTR thermistor). For example, when an NTC thermistor (negative characteristic thermistor) having a characteristic that the resistance value decreases as the temperature rises is used, the above temperature function f (T)
Is represented by the following equation.

[0006]

F (T) = exp (B / T)

In Equation 2, B is a constant (called B constant).

On the other hand, as the signal detecting resistor 2, a resistor _R0 whose resistance value _R0 hardly changes even if the temperature changes, is used. Therefore, the potential _{V s} of the middle point 5,
It becomes like the following formula.

[0009]

V _s = E · R ₀ / (R _TH0 + R ₀ ) = E · R ₀ / [R _b0 · exp (B / T) + R ₀ ]

[0010] As can be seen from Equation 3, when the NTC thermistor is used to the temperature sensing element 1, the potential V _s of the mid-point 5 increases as the ambient temperature T rises. Accordingly, the signal processing unit 6, by monitoring the potential V _s of the mid-point 5, it is possible to detect the heat generated from the fire.

The heat detector can be connected to, for example, a line extending from the receiver. The heat detector can be of two types, an on / off type and an analog type, depending on the mode of signal transmission to and reception from the receiver. Broadly classified into types. The on-off type heat sensor is connected between a pair of lines 102 from a receiver (P-type fire receiver) 101 as shown in FIG. It is configured to notify the receiver 101 of the occurrence of a fire by setting the impedance state. That is, when the heat detector is on-off type heat detector, the signal processing unit 6, for example, a comparator for comparing the potential V _s with a predetermined threshold value of the middle point 5, in accordance with the comparison result of the comparator And a switching circuit for switching the state of the pair of lines extending from the receiver. When the potential V _{s at the} midpoint 5 is equal to or lower than a predetermined threshold (fire alarm level), the pair of lines extending from the receiver is set to a high impedance. state and in the (off-state), the potential V _s of the midpoint 5 is higher than a predetermined threshold (level of fire alert), it is judged that a fire switch the pair of lines in a low impedance state (on-state) The receiver is notified of the fire.

As shown in FIG. 10, the analog type heat sensor is called by the address polling from the receiver 201 via the line 202, and at that time, sends out the signal information about the fire to the line 202. 201. That is, when the heat detector is an analog-type heat detector, the signal processing unit 6 monitors the potential V _s of the mid-point 5, when the address polling is made from the receiver, the potential of the midpoint 5 V _The analog signal corresponding to _s is processed into a form suitable for returning to the receiver (for example, converted into a digital signal by an A / D converter) and transmitted to the line 202.

In order to test whether the function of such a heat sensor (on / off type or analog type heat sensor) is normal, conventionally, as shown in FIG. 82 is connected in parallel with the temperature detecting element 1.

Here, the resistor 81 has a function as a pseudo fire resistor, and the resistance value _Rf of the resistor 81 is set to the resistance value of the temperature detecting element 1 at a predetermined temperature. .

In such a configuration, when performing a test, the switch 82 is closed. Thus, the potential V _s of the midpoint 5 is as follows.

[0016]

V _s = E · R ₀ / [R _TH0 R _f / (R _TH0 + R _f ) + R ₀ ]

As described above, when the switch 82 is closed, the resistance 81 is connected in parallel with the resistance R _TH0 of the temperature detecting element 1.
(Fake fire resistance) _Rf is connected,
The potential V _s of the mid-point 5, can always be a voltage higher than a predetermined level (the level of fire alarm). Therefore,
If the function of the signal processing unit 6 is normal, the signal processing unit 6
In the case of the on / off type, a pair of lines are set to a low impedance state to notify the receiver of a pseudo fire occurrence, and in the case of the analog type, a pseudo fire occurrence signal (a signal corresponding to a fire) is output. It can be returned to the receiver.

In the receiver, when the switch 82 is closed, the impedance between the pair of lines becomes low,
Alternatively, when a fire occurrence signal is returned from the heat sensor, it is determined that the function of the heat sensor is normal, and
Conversely, if the switch 82 is closed and the pair of lines does not enter a low-impedance state, or if a fire signal is not returned from the heat sensor, the function of the heat sensor is abnormal ( (For example, failure).

[0019]

However, in the above-described conventional test method, only the function of the signal processing section 6 is mainly checked, and the most important function of the temperature detecting element 1 itself in the heat detector is checked. There was a drawback that it was not possible to check. For example, the temperature detection element 1
If the switch 82 is closed even if there is an abnormality in the characteristics of itself or the temperature detecting element 1 is out of order (for example, disconnection), the potential V _{s of the} middle point 5 is generated by the pseudo fire resistance 81.
Is always higher than the fire alarm level irrespective of the state of the temperature detecting element 1, so that there is a problem that it is not possible to confirm a characteristic abnormality or failure of the temperature detecting element 1.

Further, the resistance value _Rf of the resistor 81 is set to a constant value necessary for always determining that a fire has occurred irrespective of the environmental temperature at which the heat sensor is installed. during the test, the resistance value R ₁ of the temperature detecting element 1 by a change in environmental temperature changes, will also vary the potential V _s of the midpoint 5, was a drawback that it can not be performed stably test.

According to the present invention, there is provided a heat sensor having a simple test circuit capable of stably testing the entire function of a heat sensor including the function of a temperature detecting element without depending on a change in environmental temperature. It is intended to provide a sensor.

[0022]

In order to achieve the above object, according to the first aspect of the present invention, a heat detecting device for detecting a fire by using a temperature detecting element and monitoring an electric signal from the temperature detecting element. in sensors, the heat sensor is connected to the test circuit for testing the function of the thermal sensor, the said test circuit, the test element having a temperature sensing element foot URN comparable temperature characteristics The test element is disposed with respect to the temperature detection element such that when the function of the heat sensor is tested using the test circuit, the temperature characteristic of the temperature detection element is offset by the temperature characteristic of the test element. It is supposed to be. Thereby, the function of the entire heat sensor including the function of the temperature detecting element can be stably tested without being affected by the environmental temperature.

According to the second aspect of the present invention, when the function of the heat sensor is normal, a predetermined electric signal indicating a simulated fire occurrence state based on the temperature detection element and the test element. Is obtained. By checking whether or not this electric signal can be obtained, it is possible to accurately test whether the function of the heat sensor is normal or abnormal.

According to the third aspect of the present invention, a variable voltage can be applied to one terminal of the test element, and when the variable voltage is applied to one terminal of the test element, the test element and the temperature detection element are connected to each other. The function of the temperature detecting element of the heat sensor is tested from the electrical signal obtained based on the element. Thus, the function of the temperature detecting element of the heat sensor can be tested with high accuracy.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing one configuration example of the heat detector according to the present invention. Referring to FIG. 1, this heat sensor is the same as the heat sensor shown in FIG. 8, except that a switch 11 is provided between the signal detection resistor 2 and the line 4. The test element 12 is connected so as to be switchable. Basically, the switch 11 and the test element 12 constitute a test circuit for testing the heat detector shown in FIG. .

Here, as the test element 12, an element (for example, an NTC thermistor) having the same characteristics (temperature characteristics) as the temperature detection element 1 can be used. When an element having the same characteristic (temperature characteristic) as the temperature detection element 1 is used as the test element 12, the resistance value R _TH1 of the test element 12 changes as follows according to the environmental temperature T.

[0027]

R _TH1 = R _b1 · f (T)

In Equation 5, R _b1 is a constant resistance value independent of temperature T. Further, f (T) is the same temperature function as the temperature function f (T) in the equation (Equation 1) for giving the temperature change of the resistance value R _TH0 of the temperature detection element 1, and
Is given by Equation 2 if is an NTC thermistor. That is, the fact that the test element 12 and the temperature detection element 1 have the same temperature characteristics means that when an NTC thermistor is used for these elements, the B constant is the same in Equation 2.

Next, the operation of the heat sensor of FIG. 1 will be described.
This during normal operation of the heat detector, in FIG. 1, switch 11 is connected to the S ₁ side. Therefore, in this case, the heat sensor has exactly the same circuit as the heat sensor shown in FIG. 8 and operates exactly the same as the heat sensor shown in FIG.

[0030] When performing a test of the functionality of the sensor switches the switch 11 to S ₂ side. Thus, the potential V _s of the midpoint 5 is as follows.

[0031]

Vs = E · R _TH1 / (R _TH0 + R _TH1 ) = E · R _b1 · f (T) / (R _b0 · f (T) + R _b1 · f (T)) = E · R _b1 / ( _Rb0 + _Rb1 ) = _Vs0

[0032] As can be seen from Equation 6, when the test element 12 and the temperature detecting element 1 is of the same temperature characteristics, the potential of the midpoint 5 V when the changeover switch 11 to S ₂ side
_s does not depend on the environmental temperature T (the temperature function is canceled out), and has a constant value _Vs0 . Therefore, the test element 12 is set so that this value _Vs0 becomes a value corresponding to the fire alarm level.
By setting the resistance value _Rb1 of the sensor in advance, the function of this sensor can be tested.

[0033] That is, when the switch 11 is switched to the _{S 2} side, the potential _{V s} of the midpoint 5 has a level _{V s0} always fire alert without being influenced by the ambient temperature. Therefore, if the function of the signal processing unit 6 is normal, the signal processing unit 6 puts the pair of lines in a low impedance state to notify the receiver of a pseudo-fire occurrence in the case of an on / off type, In the case of the type, a pseudo fire occurrence signal (a signal corresponding to a fire) can be returned to the receiver.

[0034] At the receiver, when the switch 11 is switched to the S ₂ side, between a pair of lines it is or a low impedance state, or if the fire occurrence signal from the heat sensor is returned, the heat sensitive function vessels (i.e., the function of the signal processing section 6) is determined to be normal, and if the contrary, when the switch 11 is switched to the S ₂ side, between a pair of lines is a low impedance When there is no fire signal or when a fire occurrence signal is not returned from the heat sensor, it can be determined that the function of the heat sensor (that is, the function of the signal processing unit 6) is abnormal (for example, failure).

By the way, in the heat sensor of FIG. 1, the function test of the heat sensor can be performed more reliably and accurately than in the past by using a test circuit having a simple configuration of the switch 11 and the test element 12. Can be.

That is, the sensor (test circuit) of FIG.
As described above, when the test element 12 and the temperature detecting element 1 are of the same characteristics, (constant value corresponding to the fire level) potential V _s of the midpoint 5 is a constant value which is independent of the ambient temperature T V since the _s0, environmental temperature T is changed, the potential V _s of the midpoint 5 is always constant without variation, the functional test of the detector can be performed stably.

In the sensor (test circuit) shown in FIG. 1, the characteristics of the temperature detecting element 1 are abnormal,
There when faulty (e.g. breakage), at the time of the test, the potential V _s of the mid-point 5, since the variation from the constant value V _s0, by detecting the variation, perform functional tests of the temperature detecting element 1 itself be able to. More specifically, for example, it provided a potential variation detecting means for detecting whether the potential V _s of the midpoint 5 exceeds a predetermined error range from a constant value V _s0 (not shown) to the signal processing unit 6, during the test it, when the potential V _s of the midpoint 5 exceeds a predetermined error range from a constant value V _s0, either the temperature detecting element 1 is characteristic abnormality, or the temperature sensing element 1 is faulty May be sent to the receiver. Furthermore, if the potential V _s of the midpoint 5 is increased, the means for determining whether the decrease provided, when the potential V _s is increased, it is determined that the sensitivity of the temperature detection element 1 (R _b0 or B) is reduced , when the potential V _s is decreased, it may also be configured to determine the sensitivity of the temperature detection element 1 (R _b0 or B) increases.

As described above, the heat detector (test circuit) of FIG.
Thus, the function of the entire heat sensor including the function of the temperature detecting element 1 can be stably tested.

In the above description, an element having the same characteristics as the temperature detecting element 1 is used as the test element 12. However, the same element as the temperature detecting element 1 can be used as the test element 12. In this case, if the resistance value R ₀ of the signal detection resistor 2 is set to the same value as the resistance value of the temperature detection element 1 at the temperature of the fire alarm, the fire alarm level becomes E / 2, and the actual fire alarm level becomes E / 2. when a fire occurs, the potential _{V s} of the midpoint 5 (the ie fire alert level (E / 2) or higher) is 1/2 or more of the voltage between lines 3 and 4 (power supply voltage) E. Further, at the time of the test, since it is exactly the same element is used as the temperature detecting element 1 into the test device 12, 1/2 of the voltage E between the potential V _s of the midpoint 5 lines 3, 4 (E / 2
), The fire alarm level is reached, and based on this, the function of the sensor can be tested.

In the above description, the middle point 5
Static changes in potential _{V s} (one terminal 12 of the test element 12
Connect a line 4, by using the constant voltage applied to one terminal 12a of the test element changes in the potential V _s of a state in which the ( "0" V)), abnormalities in the characteristics of the temperature detecting element 1 Alternatively, although a failure is detected, a test can be performed under a configuration as shown in FIG. 2 in order to more accurately detect a change (abnormality) in the characteristic of the temperature detecting element. That is, in the heat sensor of FIG.
Used only to open and close between Further, one terminal 12a of the test element 12 is connected to the variable voltage generator 41.
It can be connected to. As the variable voltage generator 41, for example, a first mode for generating a constant voltage value (for example, “0” V) and a variable voltage V as shown in FIG.
_x (in the example of FIG. 3, a saw-tooth-shaped variable voltage), and a mode in which the first and second modes can be switched by, for example, a manual operation can be used.

In the configuration example shown in FIG. 2, during normal operation of the heat detector, the switch 11 is closed and the variable voltage generator 4 is turned off.
1, one terminal 12a of the test element 12 is kept open. In this case, the heat sensor has exactly the same circuit as the heat sensor shown in FIG. 8 and operates exactly the same as the heat sensor shown in FIG.

When testing the function of the signal processing section 6 of the heat sensor, the switch 11 is opened and the variable voltage generator 41 is set to the first mode. This allows
The heat detector is a heat detector shown in FIG. 1, the switch 11 becomes the same state as switching to S ₂ side, in the same manner as described above, it is possible to test the function of the signal processing unit 6.

When the function of the temperature detecting element 1 of the sensor is tested, the switch 11 is opened and the variable voltage generator 41 is set to the second mode. In this case, from the variable voltage generator 41, for example, the variable voltage V _x is generated as shown in FIG. 3, this is to join the one terminal 12a of the test element 12, the potential of the midpoint 5 V
_s is as follows.

[0044]

[Equation 7] _{V s = (E-V x} ) R TH1 / (R TH0 + R TH1) + V x = E · R b1 / (R b0 + R b1) + V x · R b0 / (R b0 + R b1)

[0045] Note that as the number 7 is clear, even when applying a variable voltage V _x, the potential V _s of the midpoint 5 is a one that does not depend on the environmental temperature T (i.e., temperature function is canceled )

[0046] FIGS. 4 (a) to (e), the potential V _s of the midpoint 5 upon application of a sawtooth variable voltage V _x as shown in Figure 3 is shown. If the function (for example, sensitivity) of the temperature detecting element 1 is normal, the potential V
_s is as shown in FIG. In contrast, when the function of the temperature detecting element 1 (e.g., sensitivity) is abnormally or failure, the potential V _s of the mid-point 5, FIG. 4
(B), (c), (d) or (e). FIG. 4B shows the case where the sensitivity of the temperature detecting element 1 is decreased (the resistance _Rb0 or the B constant is smaller than the normal value), and FIG. 4C shows that the sensitivity of the temperature detecting element 1 is increased. When the resistance value _Rb0 or the B constant is larger than the normal value, FIG. 4D shows the case where the temperature detection element 1 is disconnected (the resistance value _Rb0 is infinite). )
The case where the temperature detecting element 1 is short-circuited (resistance value _{R b0} "0") to which shows the potential _{V s.}

[0047] In this case, the signal processing unit 6, for example, as shown in FIG. 5, the sawtooth voltage V _s of the midpoint 5 is compared with a predetermined threshold value V _T, sawtooth voltage V _s is the predetermined threshold value V _T a counter 51 for counting the time until the, the sensitivity change detection unit 52 for detecting a sensitivity change of the temperature detecting element 1 according to the count value CNT of the counter 51, when the sawtooth voltage V _s becomes E a first determination unit 53 determines that the temperature detecting element 1 is short circuited, the second determination unit 54 determines that the temperature detecting element 1 is disconnected when the sawtooth voltage V _s is V _x
And having the following. here,
Counter 51 is adapted to operate in synchronism with the sawtooth variable voltage V _x, when the sawtooth variable voltage V _x becomes "0" V, and is reset.

[0048] In such a configuration, when the potential V _s of the midpoint 5 is as shown in FIG. 4 (a), the signal processing section 6
So by count CNT of the counter 51 is approximately the same as the normal value CNT _0, it is determined that the function of the temperature detecting element 1 is normal. In contrast, when the potential V _s of the midpoint 5 is as shown in FIG. 4 (b), the signal processing section 6
So by count CNT of the counter 51 is very small compared with the normal value CNT _0, determines the sensitivity of the temperature detection element 1 is reduced, also, the potential V _s of the mid-point 5 in FIG. 4
If becomes such as shown in (c), the signal processing unit 6, by a very large compared with the count value CNT is normal value CNT ₀ of the counter 51, determines the sensitivity of the temperature detection element 1 is raised can do. That is, a change in sensitivity of the temperature detecting element 1 can be detected with high accuracy.

[0049] Also, when the potential _{V s} of the midpoint 5 is as shown in FIG. 4 (d), the signal processing unit 6, the potential _{V s}
By There is V _x, it can detect that the temperature detecting element 1 is disconnected. The potential _{V s} of the mid-point 5 in FIG. 4
If the things (e), the in the signal processing unit 6, by the potential V _s is E, can be detected that the temperature detecting element 1 is shorted.

[0050] Thus, in the configuration example of FIG. 2, by applying a variable voltage V _x from the variable voltage generator 41 to the test element 12, the heat detector entire study, including the temperature detecting element 1 It can be performed with high accuracy. In the above example, although using a counter 51, instead of using the counter 51, such as to measure the voltage of V _s direct various modifications are possible.

In the examples shown in FIGS. 1 and 2, it has been described that the basic configuration of the heat sensor is as shown in FIG. 8, but the present invention is applied to a heat sensor having the configuration shown in FIG. There is no limitation, and any type of heat sensor may be used as long as a temperature sensor is used as a sensor for the heat generated from a fire and has a function of monitoring the electric signal from the temperature sensor and detecting the occurrence of a fire. Applicable to sensors. In connection with this, when the function of the heat sensor is tested using the test circuit, the temperature of the temperature detecting element 1 is offset by the temperature characteristic of the test element. What is necessary is that the test element is arranged for the detection element 1, and is not limited to the circuit configuration shown in FIGS. 1 and 2, and various modifications are possible.

More specifically, the present invention can be applied to a heat sensor as shown in FIG. Referring to FIG. 6, the heat detector includes a temperature detecting element 1 between a line 3 to which a power supply voltage E is applied and a line 4 held at a ground potential, a signal detecting resistor 2, a reference resistor 21, , And a reference resistor 22 are connected, and the potentials V _sa and V _{sb at} the midpoints 5 a and 5 b of the bridge circuit are applied to the signal processing unit 25, and the potential V at the midpoint 5 a is applied to the signal processing unit 25.
Based on the potential V _sb of _sa, the midpoint 5b and performs a predetermined signal processing. When the present invention is applied to the heat sensor as shown in FIG. 6, the configuration of the heat sensor including the test circuit can be as shown in FIG. 7, for example. That is, in the heat detector shown in FIG.
1 and a line 3, a switch 23 is provided, and the test element 2 is switchably connected to the reference resistor 21 by the switch 23.
4 are connected, and basically, such a switch 23 and the test element 24 form a test circuit.

Here, as the test element 24, an element having the same characteristics (temperature characteristics) as the temperature detection element 1 (for example, an NTC thermistor) can be used. When an element having the same characteristic (temperature characteristic) as the temperature detecting element 1 is used as the test element 24, the resistance value R _TH2 of the test element 24 changes as follows according to the environmental temperature T.

[0054]

R _TH2 = R _b2 · f (T)

In Equation 8, _Rb2 is a constant resistance value independent of temperature T. Further, f (T) is the same temperature function as the temperature function f (T) in the equation (Equation 1) for giving the temperature change of the resistance value R _TH0 of the temperature detecting element 1.
Is given by Equation 2 if is an NTC thermistor.

The heat detector having the structure as shown in FIG.
The test operation can be performed in the same procedure as the heat sensor shown in FIG. That is, in the normal operation of the heat detector, in FIG. 7, the switch 23 is connected to the S ₃ side. In this case, in this heat sensor, the midpoint 5a
Potential _{V sa} of is expressed by the following equation.

[0057]

V _sa = E · R ₀ / (R _TH0 + R ₀ )

The potential _{Vsb at the} middle point 5b is expressed by the following equation.

[0059]

V _sb = E · R ₂ / (R ₂ + R ₁ )

Note that in _equations 9 and 10, R _TH0 ,
R ₀ , R ₁ , and R ₂ are resistance values of the temperature detection element 1, the signal detection resistance 2, the reference resistance 21, and the reference resistance 22, respectively. When the heat sensor is of an on / off type, the signal processing unit 25 outputs, for example, the potential V _{sa of the} middle point 5a.
And a comparator that compares the potential _{Vsb of the} middle point 5b with
A switching circuit that switches the state of a pair of lines extending from the receiver in accordance with the comparison result of the comparator. The switching circuit detects the environmental temperature T and the resistance value R _TH0 of the temperature detecting element 1 that is large. When the potential V _{sa at} the middle point 5a on the side of the reference resistor is lower than the potential V _{sb at} the middle point 5b of the reference resistor, the pair of lines extending from the receiver are in a high impedance state (OFF state), and the environmental temperature T
_Rises , the resistance value R _TH0 of the temperature detecting element 1 decreases, and the potential V _{sa at} the middle point 5a on the detection side becomes the middle point 5b of the reference resistance.
When the potential becomes higher than the potential _Vsb , the pair of lines is switched to low impedance to notify the receiver of the fire. When this heat sensor is of an analog type, the signal processing unit 25 outputs, for example, the potential V at the midpoint 5a.
The potential V _sb at the midpoint 5b is subtracted from _sa, and an analog signal corresponding to the subtraction result is processed into a form suitable for returning to the receiver (for example, converted into a digital signal by an A / D converter). ), The signal is transmitted to the line. When the potential V _{sa at the} midpoint 5a is higher than the potential V _{sb at the} midpoint 5b, a positive signal can be returned to the receiver as a fire occurrence signal.

[0061] When performing a test of the functionality of the sensor switches the switch 23 to S ₄ side. As a result, the potential _{Vsb at the} middle point 5b is expressed by the following equation.

[0062]

V _sb = E · R ₂ / (R ₂ + R _TH2 )

Here, the constant resistance value R _b2 of the test element 24
For a constant resistance value R _b0 of the temperature detecting element 1 and resistance values R ₁ and R _{2 of the} reference resistances 21 and 22, the following equation (Equation 12) is obtained.
It is assumed that a device that satisfies the above condition is used (set).

[0064]

R ₀ : (R ₂ + α) = R _b0 : R _b2

Here, α is an appropriate positive resistance value irrespective of the environmental temperature T. When a test element 24 having a constant resistance value _Rb2 that satisfies the condition of Expression 12 is used,
The relationship between the potential V _sa at the middle point 5a and the potential V _{sb at the} middle point 5b is as follows.

[0066]

V _sa = E · R ₀ / (R _TH0 + R ₀ ) = E / (1 + R _b0 · f (T) / R ₀ ) = E / (1 + R _b2 · f (T) / (R ₂ + α) ) = E · R ₂ / (R ₂ + R _TH2 / (1 + α / R ₂ ))> V _sb

[0067] The number 13 relationship, so satisfied regardless of the environmental temperature T, when the switch 23 is switched to the _{S 4} side than the potential _{V sb} potential _{V sa} midpoint 5b midpoint 5a Always higher.

Accordingly, if the function of the signal processing unit 25 is normal, the signal processing unit 25 sets the pair of lines to a low impedance state and informs the receiver of the occurrence of a simulated fire in the case of the ON / OFF type. In the case of the analog type, a pseudo fire occurrence signal (a signal corresponding to a fire) is returned to the receiver.

[0069] In the receiver, when the switch 23 is switched to the S ₄ side, between a pair of lines it is or a low impedance state, or if the fire occurrence signal from the heat sensor is returned, the heat sensitive function vessels (i.e., the function of the signal processing section 25) is determined to be normal, and if the contrary, when the switch 23 is switched to the S ₄ side, between a pair of lines is a low impedance Or not
Alternatively, when a fire occurrence signal is not returned from the heat sensor, the function of the heat sensor (that is, the signal processing unit 25
Can be determined to be abnormal (for example, a failure).

By the way, in the heat sensor of FIG. 7, as in the heat sensor of FIG. 1, a functional test of the heat sensor is performed by a simple test circuit including the switch 23 and the test element 24 as compared with the conventional heat sensor. Can be performed more reliably and accurately.

That is, the heat detector (test circuit) shown in FIG.
As described above, when the test element 24 and the temperature detection element 1 have the same characteristics, the difference between the potential V _sa of the middle point 5a and the potential V _{sb of the} middle point 5b does not depend on the environmental temperature T. Since the constant value _Vs1 is obtained, even if the environmental temperature T changes,
The potential V _sa at the middle point 5a is always higher than the potential V _{sb at the} middle point 5b by a constant value V _s1 , so that the function test of the sensor can be stably performed.

In the sensor (test circuit) shown in FIG. 7, the characteristics of the temperature detecting element 1 are abnormal,
There when faulty (e.g. breakage), at the time of the test, the potential V _sa varies the midpoint 5a, therefore, since V _s1 varies, by detecting the variation of V _s1, the temperature detecting element 1 itself Functional tests can be performed. More specifically, for example, the difference between the potential V _sa and the potential V _sb (potential difference)
Is a signal processing unit 2 that is provided with a potential difference fluctuation detecting means (not shown) for detecting whether or not exceeds a predetermined error range from the constant value _Vs1.
5, when the potential difference exceeds a predetermined error range from the fixed value _Vs1 during the test, it is notified that the temperature detecting element 1 has abnormal characteristics or that the temperature detecting element 1 is faulty. Signal to the receiver. Further, a means for determining whether the potential difference has increased or decreased is provided. When the potential difference increases, it is determined that the sensitivity ( _Rb0 or B) of the temperature detecting element 1 has decreased. It may be configured to determine that the sensitivity ( _Rb0 or B) of the detection element 1 has increased.

As described above, the heat detector (test circuit) shown in FIG.
Also, the function of the entire heat detector including the function of the temperature detecting element 1 can be stably tested.

In the above configuration example, the test elements 12 and
24, an element having the same temperature characteristic as the temperature detecting element 1 or an element exactly the same as the temperature detecting element 1 is used, but it is difficult to obtain a test element having the same temperature characteristic as the temperature detecting element 1. considering that there is, when almost the same test device is used as the temperature sensing element 1 during the test, so that the potential V _s or the potential difference V _s1 of the midpoint 5 is a level sufficient to carry out the test , For example, test element 1
2, 24, the constant resistance values R _b1 and R _b2 are R
It is also possible to use a _b0 and greater than _{R 2.} As described above, by taking a margin such as making the values of R _b1 and R _b2 larger than those of R _b0 and R ₂ , the test element 1
The characteristics of the 2, 24 is not less different from the characteristics of the temperature sensing element 1, the potential V _s or the potential difference V midpoint 5 during test
_s1 can always be at a large level. That is, it is possible to reliably increase the level to the fire alert level or higher.

In the heat detector, the temperature detecting element 1
In general, in order to accurately detect the environmental temperature T, for example, in a form exposed to the outside of the housing surface of the sensor, or
Although it is installed in a form similar to that, the test elements 12, 24
Is preferably installed inside the heat detector (without being exposed to the outside) in order to reduce its own failure. As a result, the degree of failure of the test elements 12 and 24 can be significantly reduced as compared with the temperature detection element 1, and a functional test of the sensor including the temperature detection element 1 can be performed reliably and stably. Note that the test elements 12, 24 may be pre-installed in the heat sensor, or may be removably attached to the heat sensor as needed.
In a case where the test elements 12 and 24 are configured to be detachably attached to the heat sensor, replacement of the test elements 12 and 24 becomes easy.

In the above embodiment, the switch 1
1 and 23 may be configured so that they can be directly operated by an operator. For example, when a test command is received from a receiver, automatic switching is performed in response to the test command. It may be configured.
Alternatively, for example, as shown in Japanese Utility Model Publication No. 58-21020, the switches 11 and 23 are configured as reed switches that operate by an external magnetic force, and permanent magnets and the like are provided on the switches (reed switches) 11 and 23. It is also possible to operate the switches 11 and 23 by approaching (by bringing the magnets closer).

In the configuration of FIG. 2, the switch 11 is
In addition to the above-described operation example, open / close control can be further performed in conjunction with the test voltage generator 41. Specifically, for example, it is possible to automatically open the switch 11 when the variable voltage generator 41 is connected to the heat detector.

In the example shown in FIG. 1 or FIG. 7, the voltage applied to one terminal of the test element 12 or 24 at the time of the test is set to the ground potential “0” V or the power supply potential E. When the function is normal, based on the temperature detection element 1 and the test element 12 or 24,
It is also possible to apply a constant voltage other than "0" V or E to one terminal of the test elements 12 and 24 as long as a predetermined electric signal representing a pseudo fire occurrence state can be obtained. .

[0079]

As described above, according to the first aspect of the present invention, a test circuit for testing the function of the heat sensor is connected to the heat sensor, and the test circuit is connected to the test circuit. , the test element having a comparable temperature characteristics is provided pot temperature detecting element foot, the test element, when the function of the heat detector is tested using the test circuit, the temperature detected by the temperature characteristics of the test device Since it is arranged for the temperature detection element so as to offset the temperature characteristics of the element, the function of the entire heat sensor including the function of the temperature detection element must be stably tested without being affected by the environmental temperature. Can be.

According to the second aspect of the present invention, when the function of the heat detector is normal, the predetermined electric power indicating a pseudo fire occurrence state is determined based on the temperature detecting element and the test element. Since it is configured to obtain a signal,
It is possible to accurately test whether the function of the heat sensor is normal or abnormal.

According to the third aspect of the present invention, a variable voltage can be applied to one terminal of the test element,
Since the function of the temperature detection element of the heat sensor is configured to be tested from an electric signal obtained based on the temperature detection element and the test element when a variable voltage is applied to one terminal of the test element. In addition, the function of the temperature detecting element of the heat sensor can be accurately tested.

[Brief description of the drawings]

FIG. 1 is a diagram showing one configuration example of a heat detector according to the present invention.

FIG. 2 is a diagram showing another configuration example of the heat detector according to the present invention.

3 is a diagram showing an example of a variable voltage V _x output from the variable voltage generator.

Variable voltage V _x as shown in FIG. 4 FIG. 3 is a diagram showing the potential V _s of a predetermined portion when applied to the test element.

FIG. 5 is a diagram illustrating an example of a signal processing unit.

FIG. 6 is a diagram illustrating a configuration example of a heat detector.

FIG. 7 is a diagram showing another configuration example of the heat detector according to the present invention.

FIG. 8 is a diagram illustrating a configuration example of a heat detector.

FIG. 9 is a diagram for explaining an on / off type heat sensor.

FIG. 10 is a diagram for explaining an analog heat sensor.

FIG. 11 is a diagram showing a configuration example of a conventional heat detector having a test function.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temperature detection element 2 Signal detection resistor 3, 4 wire 5 Midpoint 6, 25 Signal processing unit 11, 23 Switch 12, 24 Test element 21, 22 Reference resistance 41 Variable voltage generator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01K 7/24 G08B 17/00 G08B 17/06

Claims (3)

(57) [Claims] 1. A heat sensor for detecting a fire by using a temperature detection element and monitoring an electric signal from the temperature detection element, wherein the heat sensor includes a function for testing the function of the heat sensor. test circuit is connected, the said test circuit, the test element is provided with the temperature detecting element foot URN comparable temperature characteristics, the test element, the function of the heat detector using the test circuit tests When, to offset the temperature characteristics of the temperature detection element by the temperature characteristics of the test element,
A heat sensor, wherein the heat sensor is arranged for the temperature detecting element. 2. The heat sensor according to claim 1, wherein, when the function of the heat sensor is normal, a predetermined fire condition is determined based on the temperature detection element and the test element. A heat sensor configured to obtain a measured electric signal. 3. The heat sensor according to claim 1, wherein a variable voltage can be applied to one terminal of the test element, and a temperature is detected when the variable voltage is applied to one terminal of the test element. A heat sensor characterized in that the function of a temperature detecting element of the heat sensor is tested from an electric signal obtained based on the element and the test element.