JPH0560640B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat sensor used in a disaster prevention system.

[Background Art] Conventionally, this type of heat sensor used in disaster prevention systems detects when the rate of increase in ambient temperature exceeds a preset value, or when the ambient temperature exceeds a preset detection temperature. It was designed to output a fire detection signal (for example, H level) when the fire occurred. However, in such conventional cases, the fire detection signal was a digital signal of 1, 0, so the fire alarm system receiver that centrally monitors the heat detector was installed at the disaster prevention center or office. However, there was a problem that the situation at the scene of the fire was not known and it was not possible to take appropriate measures.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to provide a heat detector that allows the receiver side of a self-fire alarm system to easily grasp the situation at the scene of a fire. Our goal is to provide the following.

[Disclosure of the Invention] (Structure) The present invention includes a first heat-sensitive element that has a quick response to ambient temperature, a second heat-sensitive element that has a slow response to ambient temperature, and a differential signal between the outputs of both heat-sensitive elements. The heat alarm system consists of an analog output circuit that amplifies and outputs the fire detection signal as a fire detection signal, and continuously sends a fire detection signal consisting of an analog signal corresponding to the rate of increase in ambient temperature to the receiver of the self-fire alarm system. The sensor is provided with an operation mode switching switch that replaces the second heat-sensitive element with a predetermined fixed resistor and switches the operation mode from temperature rise detection mode to ambient temperature detection mode in response to a control signal from the receiver side.

(Example) Fig. 1 shows the basic configuration of a heat sensor equipped with a temperature rise detection means of the present invention.
TH ₁ , a second thermal element TH ₂ consisting of a thermistor that responds slowly to the ambient temperature, and both thermal elements.
It consists of an operational amplifier OP that amplifies the differential signal of the TH ₁ and TH ₂ outputs and outputs it as a fire detection signal Vf from the output terminal To, and an analog output circuit AO consisting of bias setting resistors R ₁ to _{R 3} . Here, in the example, both heat-sensitive elements at a constant temperature
The resistance values of TH ₁ and TH ₂ are made equal. Also,
The DC power applied to the power input terminals TH ₁ and TH ₂ is applied via the constant voltage circuit VR to both ends of the series circuit of the resistors R ₁ and R ₂ and to the power supply terminal of the operational amplifier OP.

The operation of the embodiment will be described below. now,
When the ambient temperature is constant, that is, when there is no fire, the resistance values of both heat-sensitive elements TH ₁ and TH ₂
Since Rt ₁ and Rt ₂ are equal, the operational amplifier
The voltage amplification factor G (Rt ₂ /Rt ₁ ) of OP is 1, and the fire detection signal Vf is equal to the voltage V _A at point A.
Next, when the ambient temperature suddenly rises, the resistance value Rt 1 of the fast-responsive heat-sensitive element TH ₁ decreases, but the resistance value _{Rt 2 of} the slow-response heat-sensitive element TH ₂ hardly decreases, so the voltage amplification factor G becomes larger than 1, and the voltage level of the fire detection signal Vf (G×V _A ) increases in accordance with the rate of increase in ambient temperature. For example, the resistance values of heat-sensitive elements TH ₁ and TH ₂ when the ambient temperature is constant
When Rt ₁ and Rt ₂ are set to 20°C...1MΩ 40°C...500KΩ 60°C...250KΩ, and the voltage V _A at point A is set to 1V, the ambient temperature is constant (e.g.
20℃), the fire detection signal Vf (=V _A ) is
It has become 1V. Here, if the ambient temperature suddenly rises from 20℃ to 40℃, the thermal element TH ₁ will
However, since the heat sensitive element TH ₂ remains at 1MΩ, the fire detection signal Vf becomes 2V. Also,
Similarly, when the ambient temperature suddenly rises from 20°C to 60°C, the fire detection signal Vf becomes 4V. Furthermore, when the ambient temperature suddenly rises from 40°C to 60°C, the fire detection signal VF becomes 2V in the same way. That is, the fire detection signal Vf increases in proportion to the rate of increase in ambient temperature. Therefore, on the receiver side of the self-fire alarm system, it is possible to determine whether a fire has occurred based on the voltage level of the fire detection signal Vf, and also to determine whether the temperature rise associated with the fire is still occurring. It is possible to distinguish whether the fire has subsided or the temperature has decreased, and the fire can be dealt with appropriately.

Figure 2 shows the basic configuration of another heat sensor. A stabilized DC power supply is applied to the series circuit of TH ₁ and TH ₂ , and the voltage at the connection point (point B) is amplified and output. Analog output circuit at buffer BF
This is what formed the AO.

The operation of the embodiment will be described below. now,
When the ambient temperature suddenly increases, although the resistance value Rt 1 of the heat-sensitive element TH ₁ immediately decreases, the resistance value Rt ₁ of the heat-sensitive element TH ₂ decreases immediately.
Since the resistance value Rt ₂ hardly decreases, the voltage at point C
Vc becomes higher, and this voltage Vc is output as the fire detection signal Vf. In this case, a voltage follower circuit is formed by the buffer BF, making it possible to lower the output impedance.

FIG. 3 shows one embodiment of the present invention.
In a heat sensor similar to the one shown in the figure, the second heat-sensitive element TH ₁ is replaced with a predetermined fixed resistor R ₄ and the differential mode is switched from temperature rise detection mode to ambient temperature detection mode using a control signal from the receiver side. It is equipped with a mode change switch SW. Note that the switch SW is switched by a control signal input to the switching control terminal Tc.

Now, when the switch SW is switched to the A side, the same process as in the first embodiment is performed, in which the fire detection signal Vf corresponding to the rate of increase in ambient temperature is output via the output terminal To. When a heat detection operation is performed and the switch SW is switched to the low side, a fire detection signal Vf at a voltage level (=R ₄ /Rt ₁ ) corresponding to the rise in ambient temperature is output via the output terminal To. It is becoming more and more common. Therefore, the operation mode can be switched between the temperature rise detection mode and the ambient temperature detection mode by the control signal input to the switching control terminal Tc, and the receiver side of the self-fire alarm system can detect the rising temperature at the scene. It is now possible to perform monitoring according to the situation by appropriately selecting an operation mode according to the situation.

Furthermore, in the heat sensor shown in Fig. 2, the heat-sensitive element is
Needless to say, if TH ₁ is replaced with a fixed resistor, it becomes ambient temperature detection mode.

[Effects of the Invention] The present invention is configured as described above, and is based on a differential signal between the output of the first heat-sensitive element, which responds quickly to the ambient temperature, and the output of the second heat-sensitive element, which responds slowly to the ambient temperature. There is a temperature rise detection mode that determines the initial stage of a fire (small temperature rise rate) or the spread of a fire (large temperature rise rate), and a temperature rise detection mode that determines the initial stage of a fire (small temperature rise rate) or the spread of a fire (large temperature rise rate). Ambient temperature detection mode, which detects the temperature and determines the fire situation, can be selected from the receiver side according to the situation at the site, and receives control of disaster prevention shutters, etc. according to the situation at the site and the fire situation. This has the effect of allowing the machine to perform the process more appropriately.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a basic example of a heat sensor according to the present invention, FIG. 2 is a circuit diagram of another basic example, and FIG. 3 is a circuit diagram of an embodiment of the present invention. TH ₁ and TH ₂ are heat sensitive elements, and AO is an analog output circuit.

Claims (1)

[Claims] 1 A first heat-sensitive element that responds quickly to ambient temperature, a second heat-sensitive element that responds slowly to ambient temperature, and an analog that amplifies the differential signal of the output of both heat-sensitive elements and outputs it as a fire detection signal. In a heat sensor that continuously sends a fire detection signal consisting of an analog signal corresponding to the rate of increase in ambient temperature to the receiver of the self-fire alarm system, the control signal from the receiver side A heat sensor comprising an operation mode switching switch that replaces the second heat-sensitive element with a predetermined fixed resistor and switches the operation mode from a temperature rise detection mode to an ambient temperature detection mode.