JPH09180076A - Automatic fire alarm system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the work efficiency at the time of system construction by unnecessitating the installation of a transmitter response line by discriminating a fire alarm signal from a fire sensor and an emergency alarm signal from an emergency transmitter based on the outputs of plural voltage comparator circuits. SOLUTION: Plural voltage comparator circuits CP1-CP3 compare the voltage levels of respectively correspondent sensor lines with a reference level generated by a reference voltage output circuit ST and based on this compared result, the fire alarm signal from a fire sensor 3 and the emergency alarm signal from an emergency transmitter 4 are discriminated. Namely, even when plural sensor lines are connected to a fire receiver 1, only by connecting the respective fire sensor 3, emergency transmitter 4 and fire receiver 1 through two wire type sensor lines, the fire alarm signal and emergency alarm signal can be discriminated. Therefore, since it is not necessary to install any transmitter response line, the work efficiency at the time of system construction is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic fire alarm system, and more particularly to improvement of an automatic fire alarm system in which a fire detector and an emergency transmitter are connected to a common two-wire detector line. .

[0002]

2. Description of the Related Art Conventionally, an automatic fire alarm system of this type has a fire detector connected to a two-wire detector line of a fire receiver, and when the fire receiver receives a fire detection signal from the fire detector, Fire alarms are issued by sounding the district sound. On this detector line, in parallel with the fire detector,
If an emergency transmitter having an emergency button is connected, the operation of this emergency button can cause the fire receiver to perform the same processing as when the fire detector issued a warning.

However, when an emergency transmitter issues a warning,
Unlike when the fire detector issues a warning, it is necessary to cancel the storage function and immediately perform a fire alarm operation. For this reason, it was necessary to determine whether the fire receiver issued from the fire detector or the emergency transmitter, and it was necessary to provide a transmitter response line in addition to the detector line. . The inventors of the present application, in the patent application No. 190912 of 1995, disclose that a fire receiver uses a fire alarm signal from a fire detector,
We proposed an automatic fire alarm system that distinguishes an emergency alarm signal from an emergency transmitter by the voltage level.

This automatic fire alarm system will be described with reference to FIG. The system shown in FIG. 5 is an automatic system in which the fire detector 3 and the emergency transmitter 4 are connected in parallel via the detector line between the signal terminal L and the common terminal C of the fire receiver 1. It is a fire alarm system. The fire detector 3 is configured to include a fire sensor that becomes conductive when the fire detection unit 30 detects generation of smoke, heat, or the like, and when a fire is detected, the internal impedance of the fire detector is the resistance 3
1 and 33, the light emitting diode 32 is turned on and the voltage level of the sensor line is lowered.

The emergency transmitter 4 comprises a push button switch 40. When the push button switch is pressed in an emergency such as a fire, the sensor line is short-circuited in the emergency transmitter 4, and the impedance of the sensor line is equal to the line resistance R.
Only 0 is available. Therefore, the voltage level of the detector line becomes lower than that when the fire detector 3 is notified.
The detector alarm detection unit 10 of the fire receiver 1 is a circuit in which the light emitting diode LD1 is turned on when the voltage level of the detector line is lowered, and either the fire detector 3 or the emergency transmitter 4 issues an alarm signal. Is output, the light emitting diode LD1
Is turned on to inform the manager or the like.

Also, the transmitter response detection unit 1 of the fire receiver 1
Reference numeral 1 is a circuit in which the light emitting diode LD2 is turned on only when the emergency transmitter 4 outputs a warning signal based on the output result of the voltage comparison circuit CP. That is, the voltage dividing resistor R1,
The reference voltage level output by the reference voltage output circuit ST configured by R2 by dividing the power supply voltage and output is lower than when the fire detector 3 is issued and higher than when the emergency transmitter 4 is issued. Yes, the voltage comparison circuit CP outputs the comparison result of comparing the voltage level of the sensing line with the reference voltage level.

With such a structure, the fire receiver is notified by the fire detector or the emergency transmitter by only the two-wire type sensor line without providing the transmitter response line. It was possible to determine whether. Furthermore, the inventors of the present application also proposed another automatic fire alarm system in the above application. This automatic fire alarm system is shown in FIG. This automatic fire alarm system is a system in which the voltage comparison circuit CP and the reference voltage output circuit ST of the system shown in FIG. 5 are independent from the fire receiver 1 and configured as a transmitter connection adapter 2.

In this automatic fire alarm system, the fire receiver 1 and the transmitter connection adapter 2 are 2
Although it is connected by the three lines of the line type sensor line and the transmitter response line, the transmitter connection adapter 2 and the fire detector 3 are connected.
Also, the emergency transmitter 4 can be configured to be connected only by a two-wire type sensor line. Therefore, by adding the transmitter connection adapter 2 to the conventional fire receiver 1, the fire detector and the emergency transmitter 4 can be connected only by the 2-wire type detector line. It is possible to discriminate between the alarm signal from the fire detector 3 and the alarm signal from the emergency transmitter 4.

[0009]

However, all of the above automatic fire alarm systems correspond to only a single detector line. Therefore, if there are multiple detector lines, it is necessary to install the fire receiver 1 for each detector line, and this is not economical, so it is applied to a large-scale facility with multiple detector lines. I couldn't.

Conventionally, there has been a fire receiver in which a plurality of sensor lines are connected and the voltage level of each sensor line is monitored, but the transmitter connection adapter described above is used as an automatic receiver equipped with such a fire receiver. When applied to a fire alarm system, a transmitter connection adapter is required for each detector line, which is not economical. The present invention has been made in view of the above circumstances, and an automatic fire notification system for discriminating a fire alarm signal from a fire sensor and an emergency alarm signal from an emergency transmitter for a plurality of sensor lines. The purpose is to provide at low cost.

[0011]

In an automatic fire alarm system according to the present invention as set forth in claim 1, a fire detector and an emergency transmitter are connected to a fire receiver via a common two-wire detector line. The fire receiver is an automatic fire alarm system that distinguishes a fire alarm signal from a fire detector and an emergency alarm signal from an emergency transmitter by voltage level, and the fire receiver has two different wires. Signal terminals for connecting the respective sensor lines to each other, a plurality of voltage comparison circuits for comparing the voltage level of each of the signal terminals with a predetermined reference voltage level, and a reference for each of the voltage comparison circuits. And a single reference voltage output circuit for supplying a voltage level.

Here, the reference voltage level is a voltage level for distinguishing a fire alarm signal from the fire sensor and an emergency alarm signal from the emergency transmitter. In the automatic fire alarm system according to the present invention as set forth in claim 2, the fire detector and the emergency transmitter are connected to the fire receiver through a common two-wire type detector line, and the fire receiver is the fire detector. An automatic fire alarm system that discriminates a fire alarm signal from an emergency alarm signal and an emergency alarm signal from an emergency transmitter by voltage level, wherein the fire receiver connects different 2-wire sensor lines to each. A plurality of signal terminals, a signal extraction circuit for obtaining the minimum voltage level or the maximum voltage level of each of the sensor lines, and a single signal level comparison circuit that compares the voltage level output by the signal extraction circuit with a predetermined reference voltage level. It is configured to include a voltage comparison circuit and a reference voltage output circuit for supplying a reference voltage level to the voltage comparison circuit.

Here, the signal extraction circuit outputs the voltage level of the emergency notification signal if any of the sensor lines outputs the emergency notification signal based on the voltage level of each sensor line. It is a circuit to do. In the automatic fire alarm system according to the present invention as set forth in claim 3, the fire detector and the emergency transmitter are connected to the transmitter adapter via a common two-wire sensor line, and the transmitter adapter is
Connected to the fire receiver, the transmitter adapter discriminates the fire alarm signal from the fire detector from the emergency alarm signal from the emergency transmitter based on the voltage level, and the discrimination result is the fire alarm signal. An automatic fire alarm system for outputting to a receiver, wherein the transmitter adapter has a plurality of signal terminals for connecting different two-wire type sensor lines to each other and a predetermined voltage level of each signal terminal. It comprises a plurality of voltage comparison circuits for respectively comparing with the reference voltage level and a single reference voltage output circuit for supplying the reference voltage level to each of the above voltage comparison circuits.

That is, the fire receiver, the fire detector, and the emergency transmitter are separated from the fire receiver in the automatic fire alarm system according to the first aspect of the present invention by making the voltage comparison circuit and the reference voltage generation circuit independent. It is something that is interposed between them. In the automatic fire alarm system according to the present invention as set forth in claim 4, the fire detector and the emergency transmitter are connected to the transmitter adapter via a common two-wire type detector line, and the transmitter adapter is Connected to the fire receiver, the transmitter adapter discriminates the fire alarm signal from the fire detector from the emergency alarm signal from the emergency transmitter based on the voltage level, and the discrimination result is the fire alarm signal. An automatic fire alarm system for outputting to a receiver, wherein the transmitter adapter has a plurality of signal terminals for connecting different two-wire type sensor lines to each other, and a minimum voltage level of each of the above sensor lines or A signal extraction circuit for obtaining the maximum voltage level, a single voltage comparison circuit for comparing the voltage level output by the signal extraction circuit with a predetermined reference voltage level, and a reference voltage relay for the voltage comparison circuit. Configured with a reference voltage output circuit for supplying Le.

That is, the signal extraction circuit, the voltage comparison circuit, and the reference voltage generation circuit are separated from the fire receiver in the automatic fire alarm system according to the present invention, and the fire receiver and the fire detector are provided. And an emergency transmitter.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of an automatic fire alarm system according to the present invention as set forth in claim 1. This automatic fire alarm system is configured by connecting a fire detector 3 and an emergency transmitter 4 in parallel to a detector line of a fire receiver 1. This fire receiver 1 has a plurality of signal terminals L1 to L
3, and different sensor lines are connected between each of these signal terminals and the common terminal C. In this figure, only the sensor lines connected to the signal terminal L1 are shown, and the sensor lines connected to the signal terminals L2 and L3 are omitted. Similar omissions are made in FIGS. 2 to 4 described later.

The fire detector 3 and the emergency transmitter 4 connected to the detector line are the same as those shown in FIG. That is, the fire detector 3 and the emergency transmitter 4 both reduce the voltage level of the detector line by the output of the alarm signal, and the voltage of the detector line when the emergency transmitter 4 outputs the emergency alarm signal. The level is lower than when the fire detector 3 outputs the fire alarm signal.

The fire receiver 1 has a plurality of sensor alarm detection units 101 to 103 corresponding to the respective sensor lines, a single transmitter response detection unit 11, and a plurality of voltages corresponding to the respective sensor lines. It is composed of comparison circuits CP1 to CP3 and a single reference voltage output circuit ST. Sensor alarm detection unit 101
Reference numerals 103 to 103 are circuits that light up the light emitting diode LD1 when the voltage levels of the corresponding signal terminals L1 to L3 decrease. Therefore, when either the fire detector 3 or the emergency transmitter 4 outputs a warning signal, the light emitting diode LD1 of the corresponding sensor warning detection unit 101 to 103 lights up to notify it.

The voltage comparison circuits CP1 to CP3 are comparators for comparing the voltage levels of the signal terminals L1 to L3 with the reference voltage level generated by the reference voltage output circuit ST, and the voltage level of the sensor line is the reference voltage level. Higher than that, the output terminal has a high impedance, while below the reference voltage level, the output terminal has a low voltage level. The output terminals of these voltage comparison circuits CP1 to CP3 are connected and connected to the transmitter response detection unit 11.

The transmitter response detecting section 11 is a circuit that turns on the light emitting diode LD2 when the voltage level of the connected signal line is a low voltage level. That is, when any of the voltage comparison circuits CP1 to CP3 outputs a low voltage level, the light emitting diode LD2 is turned on, and in other cases, it is turned off. Therefore, if the emergency button of any of the emergency transmitters 4 is pressed and the voltage level of the sensor line to which the emergency transmitter 4 is connected falls below the reference voltage level, the corresponding voltage comparison circuits CP1 to CP3 are activated. A low level signal is output and the light emitting diode LD2 is turned on.
On the other hand, when all the emergency transmitters 4 do not output the alarm signal, the output terminals of all the voltage comparison circuits CP1 to CP3 have high impedance, and the light emitting diode LD1 does not light.

The sensor alarm detection units 101 to 103 and the transmitter response detection unit 11 are composed of the light emitting diodes LD1 and L.
It is needless to say that instead of lighting D2, a circuit that blinks may be used, and the same applies to the following embodiments. By configuring the fire receiver 1 in this way, even if there are multiple detector lines connecting the fire detector 3 and the emergency transmitter 4, a transmitter response line is provided in addition to the detector line. It is possible to distinguish between the fire alarm signal of the fire detector and the emergency alarm signal of the emergency transmitter.

FIG. 2 shows an example of the configuration of the automatic fire alarm system according to the second aspect of the present invention. This automatic fire alarm system is configured by connecting the fire detector 3 and the emergency transmitter 4 in parallel to the detector line of the fire receiver 1 as in the system shown in FIG. 1. Signal terminals L1 to L3, and different sensor lines are connected between each of these signal terminals and the common terminal C.

The fire receiver 1 includes a plurality of sensor alarm signal detection units 101 to 103 corresponding to each sensor line, a single transmitter response detection unit 11, and a single voltage comparison circuit CP.
And a reference voltage output circuit ST and a signal extraction circuit SD. Sensor alarm signal detection unit 101-103
Is a circuit that lights up the light emitting diode LD1 when the voltage levels of the corresponding signal terminals L1 to L3 decrease. Therefore, if either the fire sensor 3 or the emergency transmitter 4 outputs a warning signal, the corresponding sensor warning detection unit 101-
The light emitting diode 103 lights up to inform it.

The signal extraction circuit SD includes diodes D1 to D
3 is a circuit in which the signal lines from the respective signal terminals L1 to L3 are connected through the circuit 3, and the maximum voltage or the minimum voltage of all the signal terminals L1 to L3 can be obtained depending on the mounting direction of the diodes. The illustrated signal extraction circuit is a circuit for obtaining the minimum value, and one of the emergency transmitters 4 is
If the alarm signal is output, the voltage level input to the voltage comparison circuit CP becomes the voltage level of the emergency alarm signal.

The voltage comparison circuit CP is a comparator for comparing this minimum value with the reference voltage level output by the reference voltage output circuit ST, and outputs it if the minimum value of the voltage level of the sensor line is higher than the reference voltage level. While the terminal goes high, the output terminal goes low if it is lower than the reference voltage level. The transmitter response detection unit 11 determines the light emitting diode LD2 based on the output of the voltage comparison circuit CP.
Is a circuit for turning on or off. That is, when the voltage comparison circuit CP outputs a low level signal, the light emitting diode LD2 is turned on to indicate that the emergency alert signal is sent from the emergency transmitters, while all the emergency transmitters 4 are activated. Since the warning signal is not output, the light emitting diode LD2 is turned off if the voltage comparison circuit CP outputs a high level signal.

By configuring the fire receiver 1 as described above, only by providing the single voltage comparison circuit CP, the fire alarm signal of the fire detector 3 and the emergency transmitter 4 are provided for all the detector lines. Can be distinguished from the emergency alert signal of. FIG. 3 shows a structural example of the automatic fire alarm system according to the present invention as set forth in claim 3. This automatic fire alarm system is configured by connecting a fire detector 3 and an emergency transmitter 4 to a fire receiver 1 via a transmitter connection adapter 2. This transmitter connection adapter 2 is different from the fire receiver 1
The line detector line and the transmitter response line are connected by three lines, while the fire detector 3 and the emergency transmitter 4 are connected via only the two line detector line. Also, as in FIG. 1, the fire detector 3 and the emergency transmitter 4 are connected in parallel to the detector line.

The transmitter connection adapter 2 is composed of a plurality of voltage comparison circuits CP1 to CP3 corresponding to each sensor line and a reference voltage output circuit ST, and the voltage comparison circuit CP.
The output terminals of 1 to CP3 are connected and output to the transmitter response terminal of the fire receiver 1. The fire receiver 1 includes a plurality of signal terminals L1 to L3, a transmitter response terminal A and a common terminal C, and a plurality of sensor alarm signal detection units 101 to 103 corresponding to each sensor line, and a single detector. Transmitter response detection unit 11
It is composed of

The sensor alarm signal detection units 101-103 are
Signal terminals L1 to L3 and transmitter connection adapter 2 respectively
Through the fire detector 3 and the emergency transmitter 4 are connected to the detector line. Also, the transmitter response detection unit 1
1 is a transmitter connection adapter 2 via a transmitter response terminal A
It is connected to the internal voltage comparison circuits CP1 to CP3. That is,
In this automatic fire alarm system, the voltage comparison circuits CP1 to CP3 and the reference voltage output circuit ST are taken out from the fire receiver 1 shown in FIG. 1 and configured as a transmitter connection adapter 2 independent from the fire receiver 1. Is.

Therefore, when either the fire detector 3 or the emergency transmitter 4 outputs a warning signal, the light emitting diode LD1 of the corresponding sensor warning detection unit 101-103 lights up to notify it. Further, if the emergency button of any of the emergency transmitters 4 is pressed and the voltage level of the sensor line to which the emergency transmitter 4 is connected falls below the reference voltage level, the corresponding in the transmitter connection adapter 2 is responded. The voltage comparison circuits CP1 to CP3 output low level signals and output a transmitter response signal to the fire receiver 1. Then, based on this signal, the light emitting diode LD2 of the transmitter response detection unit 11 is turned on.

The automatic fire alarm system having such a transmitter connection unit 2 is connected to the fire detector 3 and the emergency transmitter 4 in addition to the detector lines even when there are a plurality of detector lines. Without providing a transmitter response line,
The alarm signal of the fire detector 3 and the alarm signal of the emergency transmitter 4 can be discriminated. In addition, the fire receiver 1, which is used by directly connecting the sensor line and the transmitter response line,
Just by adding such a transmitter connection adapter 2, the fire detector 3 and the emergency transmitter 4 are simply connected by a detector line, and even if there is no sensitive transmitter response line, the fire detector 3 fires. The alarm signal and the emergency alarm signal of the emergency transmitter 4 can be discriminated.

FIG. 4 shows an example of the configuration of the automatic fire alarm system according to the fourth aspect of the present invention. This automatic fire alarm system includes a fire receiver 1 and a transmitter connection adapter 2
And a plurality of detector lines to which the fire detector and the emergency transmitter 4 are connected are connected in the same manner as the automatic fire alarm system shown in FIG. The fire receiver 1, the fire detector 3, and the emergency transmitter 4 are the same as those shown in FIG.

The transmitter connection adapter 2 includes a signal extraction circuit S
D, a single voltage comparison circuit CP, and a reference voltage output circuit S
And T. The signal extraction circuit SD is a circuit for connecting the signal lines from the respective signal terminals through the diodes D1 to D3 to obtain the minimum value of the voltage level of each sensor line, and is the same as the circuit shown in FIG. Is. That is, this automatic fire alarm system is the fire receiver 1 shown in FIG.
The signal extraction circuit SD, the voltage comparison circuit CP, and the reference voltage output circuit ST are taken out from the above, and configured as a transmitter connection adapter 2 independent of the fire receiver 1.

Therefore, when either the fire detector 3 or the emergency transmitter 4 outputs a warning signal, the light emitting diode LD1 of the corresponding sensor warning detection unit 101-103 lights up to notify it. When the emergency button of any of the emergency transmitters 4 is pressed and the voltage level of the sensor line to which the emergency transmitter 4 is connected falls below the reference voltage level, the signal extraction circuit SD causes this emergency The voltage level of the report signal is input to the voltage comparison circuit. Therefore, the voltage comparison circuit CP outputs a low level signal, and the fire receiver 1
A transmitter response signal is output to. Based on this signal, the light emitting diode LD2 of the transmitter response detection unit 11 is turned on.

By configuring the fire receiver 1 and the transmitter adapter 2 as described above, even if there are a plurality of detector lines, the connection between the fire detector 3 and the emergency transmitter 4 is connected to the detector line. It is possible to discriminate between the fire alarm signal of the fire detector and the emergency alarm signal of the emergency transmitter without providing the transmitter response line. Further, with the transmitter connection adapter 2 having such a configuration, only by providing the single voltage comparison circuit CP, the alarm signal of the fire detector 3 and the emergency transmitter 4 of all the detector lines are provided. It can be distinguished from the alarm signal.

[0035]

In the automatic fire alarm system according to the present invention as set forth in claim 1, the plurality of voltage comparison circuits have the voltage level of the corresponding sensor line and the reference voltage level generated by the reference voltage output circuit. And the fire alarm signal from the fire detector and the emergency alarm signal from the emergency transmitter are discriminated based on the comparison result.

That is, even when a plurality of detector lines are connected to the fire receiver, each fire detector and the emergency transmitter are connected to the fire receiver by a two-wire type detector line. The fire alarm signal and the emergency alarm signal can be distinguished from each other. Therefore, since it is not necessary to install a transmitter response line, it is possible to improve work efficiency during system construction, that is, to reduce construction work.

In the automatic fire alarm system according to the second aspect of the present invention, the signal extraction circuit obtains the minimum voltage or the maximum voltage of a plurality of sensor lines, and the voltage comparison circuit compares this voltage and the reference voltage level. By comparing, the fire alarm signal from the fire sensor and the emergency alarm signal from the emergency transmitter are discriminated for all the sensor lines. That is, it is possible to determine the alarm signals of a plurality of sensor lines only by providing a single voltage comparison circuit.

Therefore, it is possible to provide at low cost an automatic fire alarm system that does not require a transmitter response line and can discriminate between a fire alarm signal and an emergency alarm signal. In the automatic fire alarm system according to the present invention as set forth in claim 3, the transmitter connection adapter includes a voltage comparison circuit and a reference voltage generation circuit to discriminate between the fire alarm signal and the emergency alarm signal, and the determination result. To the fire receiver.

Therefore, the fire detector and the emergency transmitter are connected by the detector line only by adding the transmitter connection adapter to the fire receiver which is used by directly connecting the detector line and the transmitter response line. It is possible to distinguish between the fire alarm signal and the emergency alarm signal even if there is no transmitter response line. In the automatic fire alarm system according to the present invention as set forth in claim 4, the transmitter connection adapter includes a signal extraction circuit, and a single voltage comparison circuit determines whether or not there is an emergency alarm signal for all sensor lines. Then, the discrimination result is output to the fire receiver.

Therefore, the transmitter connection adapter can be provided at low cost, the transmitter response line is unnecessary, and the automatic fire alarm system capable of discriminating between the fire alarm signal and the emergency alarm signal is inexpensive. Can be provided to.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an automatic fire alarm system according to the present invention as set forth in claim 1.

FIG. 2 is a diagram showing a configuration example of an automatic fire alarm system according to the present invention as defined in claim 2;

FIG. 3 is a diagram showing a configuration example of an automatic fire alarm system according to the present invention as set forth in claim 3.

FIG. 4 is a diagram showing a configuration example of an automatic fire alarm system according to the present invention as defined in claim 4;

FIG. 5 is a diagram showing a configuration example of an automatic fire alarm system described in the related art.

FIG. 6 is a diagram showing another configuration example of the automatic fire alarm system described in the related art.

[Explanation of symbols]

 1 ... Fire receiver 2 ... Transmitter connection adapter 3 ... Fire detector 4 ... Emergency transmitter L1-L3 ... Signal terminals CP, CP1-CP3 ... Voltage comparison circuit ST. ..Reference voltage output circuit SD ... Signal extraction circuit

Claims (4)

[Claims] 1. A fire detector and an emergency transmitter are connected to a fire receiver through a common two-wire detector line, and the fire receiver sends a fire alarm signal from the fire detector and an emergency call. In an automatic fire alarm system that discriminates an emergency alarm signal from a machine based on the voltage level, the fire receiver has a plurality of signal terminals for connecting different two-wire sensor lines to each other, and each of the above signals. A plurality of voltage comparison circuits for respectively comparing the voltage level of the terminal with a predetermined reference voltage level, and a single reference voltage output circuit for supplying the reference voltage level to each of the above voltage comparison circuits are provided. An automatic fire alarm system characterized by discriminating between a fire alarm signal from a fire detector and an emergency alarm signal from an emergency transmitter based on the output of a voltage comparison circuit. 2. A fire detector and an emergency transmitter are connected to a fire receiver through a common two-wire detector line, and the fire receiver sends a fire alarm signal from the fire detector and an emergency call. In an automatic fire alarm system that discriminates an emergency alert signal from a firearm based on the voltage level, the fire receiver has a plurality of signal terminals for connecting different two-wire sensor lines to each other, and each of the above-mentioned sensing terminals. Signal extraction circuit for obtaining the minimum voltage level or the maximum voltage level of the power supply line, a single voltage comparison circuit for comparing the voltage level output by the signal extraction circuit with a predetermined reference voltage level, and the reference voltage for the voltage comparison circuit. A reference voltage output circuit for supplying a level is provided, and the fire alarm signal from the fire detector and the emergency alarm signal from the emergency transmitter can be distinguished based on the output of the voltage comparison circuit. Automatic fire alarm system according to claim. 3. A fire detector and an emergency transmitter are connected to a transmitter adapter through a common two-wire detector line, and the transmitter adapter is connected to the fire receiver. In the automatic fire alarm system in which the transmitter adapter discriminates the fire alarm signal from the fire detector and the emergency alarm signal from the emergency transmitter according to the voltage level, and outputs the determination result to the fire receiver. The transmitter adapter has a plurality of signal terminals for connecting different two-wire sensor lines to each other, and a plurality of voltage comparison circuits for comparing the voltage level of each of the signal terminals with a predetermined reference voltage level. And a single reference voltage output circuit for supplying a reference voltage level to each of the above voltage comparison circuits, and a fire alarm from a fire detector is output based on the output of each of the above voltage comparison circuits. An automatic fire alarm system characterized by distinguishing between a signal and an emergency alarm signal from an emergency transmitter. 4. A fire detector and an emergency transmitter are connected to a transmitter adapter through a common two-wire type detector line, and the transmitter adapter is connected to the fire receiver. In the automatic fire alarm system in which the transmitter adapter discriminates the fire alarm signal from the fire detector and the emergency alarm signal from the emergency transmitter according to the voltage level, and outputs the determination result to the fire receiver. The transmitter adapter has a plurality of signal terminals for connecting different two-wire sensor lines to each other, a signal extraction circuit for obtaining a minimum voltage level or a maximum voltage level of each sensor line, and the signal A single voltage comparison circuit for comparing the voltage level output by the extraction circuit with a predetermined reference voltage level, and a reference voltage output circuit for supplying the reference voltage level to the voltage comparison circuit are provided. An automatic fire alarm system comprising: a fire alarm signal from a fire detector and an emergency alarm signal from an emergency transmitter based on the output of the voltage comparison circuit.