JP2819311B2 - Fire alarm system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fire alarm system.

[Related Art] A receiving unit including a receiver or a relay and a terminal including a relay or a fire detector are connected via a pair of power / signal lines, and the receiving unit and the terminal are connected to each other. There is a fire alarm system that employs a system in which two-way communication is performed, for example, a polling system. In this scheme,
A signal receiving circuit is provided in each of the receiving unit and the terminal.

A signal receiving circuit on the receiving side compares the voltage of the power / signal line with a predetermined determination level to determine whether the signal from the terminal is an L voltage signal or an H voltage signal. Similarly, the signal receiving circuit on the terminal side also compares the voltage of the power / signal line with a predetermined determination level to determine whether the signal from the receiving unit is an L voltage signal or an H voltage signal. doing. The discrimination level in the signal receiving circuit on the receiving side and the discrimination level in the receiving circuit on the terminal side are set to be the same.

By the way, the length of the line (power supply / signal line) differs for each building and each terminal, so that the line resistance differs for each building and each terminal, and the value of the voltage drop also differs according to the different resistance.

For this reason, when the receiver transmits an L voltage signal, for example, the voltage value of the L voltage signal is not so affected by the line resistance, but the terminal receives the L voltage signal from the receiver or the receiver receives the L voltage signal from the terminal. In this case, the voltage value of the L voltage signal is greatly affected by the line resistance. For this reason, depending on the line resistance, the voltage value of the L voltage signal when the receiver transmits the L voltage signal and the L value when the terminal receives the L voltage signal from the receiver or the receiver receives the L voltage signal from the terminal. It greatly fluctuates with the voltage value of the voltage signal. The same applies when transmitting and receiving the H voltage signal.

Therefore, in the conventional equipment, the discrimination level is set lower in anticipation of the large fluctuation.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional equipment, a receiving unit and a terminal are connected by a pair of lines, and power supply to the terminal and transmission and reception of a signal between the receiving unit and the terminal are performed by: Attempting to run on the same line causes the following problems.

First, in order for the receiver to send an L voltage signal to the terminal,
If the voltage supplied to the power / signal line falls below a predetermined value, it becomes impossible for the terminal to secure the minimum voltage necessary for operation of the fire detector and the like. For this reason, when the receiver sends the L voltage signal to the terminal, it is necessary to provide the terminal with a backup such as a large-capacity capacitor in order to operate the terminal normally, and the circuit configuration in the terminal is complicated and large. There is a problem of becoming.

When the receiver sends the H voltage signal to the terminal, the value of the voltage drop due to the line resistance increases depending on the current consumed on the terminal side. In this case, the terminal determines the H voltage signal from the receiver. There is a problem that becomes difficult.

The present invention simplifies and downsizes a circuit configuration in a terminal by eliminating the need to provide a backup such as a large-capacity capacitor in a terminal even if a line resistance exists, and reduces an H voltage from a terminal in a receiving unit. It is an object of the present invention to provide a fire alarm system in which a signal can be easily determined.

Means for Solving the Problems The present invention relates to a fire alarm system in which a receiving unit transmits and receives an H voltage signal and an L voltage signal to and from a terminal via a power / signal line. The discrimination level is set so as to be lower than the discrimination level of the signal reception circuit on the receiving side.

The present invention also provides a fire alarm system in which a receiving unit transmits and receives an H voltage signal and an L voltage signal to and from a terminal via a power / signal line.
A Zener diode and a switching element that is turned on when the terminal outputs the L voltage signal toward the receiving unit are connected in series between the two terminals.

[Operation] According to the present invention, the determination level of the terminal-side signal receiving circuit is set to be lower than the determination level of the receiving-side signal receiving circuit. By eliminating the need to provide a backup in the terminal, the circuit configuration in the terminal can be simplified and downsized, and the reception unit and the terminal can easily determine the H voltage signal from the other.

Further, according to the present invention, a Zener diode and a switching element that is turned on when the terminal outputs an L voltage signal to a receiving unit are connected in series between two terminals on the terminal side of the power / signal line. Therefore, even if a plurality of terminals output the L voltage signal at the same time, two terminals on the terminal side of the power / signal line
The voltage between the two terminals does not become lower than the Zener voltage, and by setting the Zener voltage of the Zener diode to a required voltage or more in advance, the L voltage signal can be reliably sent to the receiver.

Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In FIG. 1, the receiving unit RE and the terminal T are connected by a pair of power / signal lines L1 and L2. Note that the terminal T
Terminals such as repeaters or fire detectors, and one receiver
A plurality of terminals T are connected to RE. The receiving unit RE is a receiving unit of a fire receiver or a repeater.

The receiving unit RE includes a microcomputer MPU1, constant voltage circuits AVR11 and AVR12, a constant current circuit CC, and an H signal transmission circuit HC.
And transistors Tr11, Tr12, Tr13, Tr14, Tr15, Tr1
6, Tr17, Tr18, a comparator CM1, and a Zener diode ZD11.

The constant voltage circuit AVR11 supplies a constant voltage of, for example, 26V,
The constant voltage circuit AVR12 supplies, for example, a voltage of 18V.

The constant current circuit CC is a circuit in which the transistor Tr11 is turned on when the terminal T returns a signal to the receiving unit RE, and the current from the constant voltage circuit AVR11 flows at a constant value toward the terminal T. This is a circuit for limiting the current to the terminal T when returning. The constant current circuit CC allows a constant current to flow to the terminal T, thereby restricting a voltage drop due to line resistance of the power / signal lines L1 and L2 when returning a signal from the terminal T.
When the transistor Tr22 is turned on, the zener diode ZD22 and the transistor Tr22 are protected.

The H signal transmission circuit HC supplies power to the terminal T,
This is a circuit that also serves as a voltage signal transmission circuit.
Only when 12 is on, the output voltage (H voltage signal) of the constant voltage circuit AVR11 is supplied to the terminal T.

The transistors Tr13 and Tr17 are switching circuits that are turned on when transmitting the H voltage signal, and turned on when the signal from the terminal T is returned.

The transistors Tr14 and Tr18 are switching circuits that are turned on when the receiving unit RE sends out an L voltage signal to the terminal. When the transistors Tr14 and Tr18 turn on, the output voltage (L voltage signal) of the constant voltage circuit AVR12 is output to the terminal T. Is to be supplied to

The comparator CM1 is a comparator necessary for receiving a return signal from the terminal T. The comparator CM1 compares the voltage V1 at the terminal t11 with the Zener voltage (reference voltage) of the Zener diode ZD11 to return the signal from the terminal T. This is to determine whether the signal is an H voltage signal or an L voltage signal.

The comparator CM1 and the Zener diode ZD11 compare the signal of the power / signal line connected to the receiving unit with the first determination level, and determine whether the signal of the power / signal line is the H voltage signal or the L voltage signal. It is an example of a receiver-side signal receiving circuit that determines whether or not there is a signal. Note that the first determination level is the Zener voltage of the Zener diode ZD11 in the above embodiment.

On the other hand, the terminal T has a constant voltage circuit AVR21, a microcomputer MPU2, transistors Tr21 and Tr22, and Zener diodes ZD21 and ZD22.

The microcomputer MPU2 is an example of means for executing the flowchart shown in FIG.

The constant voltage circuit AVR21 is connected via a power / signal line L1, L2,
This is a constant voltage circuit that converts the 26V and 18V voltages supplied from the constant voltage circuits AVR11 and AVR12 of the receiving unit RE into necessary voltages (for example, 12V) to the terminal T side and supplies them.

The circuit including the Zener diode ZD21 and the transistor Tr21 forms a comparison circuit CM2 that determines whether the signal transmitted from the receiving unit RE is an H voltage signal or an L voltage signal. That is, if the voltage V2 of the terminal t21 is equal to or higher than the Zener voltage of the Zener diode ZD21, the transistor Tr21
Is turned on, and by detecting this ON state, it can be determined that the signal from the receiving unit RE is the H voltage signal.

The transistor Tr22 is a switching transistor for the terminal T to return the L voltage signal to the receiver RE. When the transistor Tr22 is turned on, the Zener diode ZD22
Are output to terminals t21 and t22 (power signal lines L1 and L2) as L voltage signals.

Note that the output voltage of the constant voltage circuit AVR12 and the Zener voltages of the Zener diodes ZD11, ZD21, ZD22 are determined in consideration of the voltage drop due to the line resistance of the power / signal lines L1, L2. For example, if the output voltage (L voltage signal) of constant voltage circuit AVR12 is 18V, L
The zener voltage of the zener diode ZD21 for determining the voltage signal is 20 V, the zener voltage of the zener diode ZD22 for transmitting the L voltage signal from the terminal T is 18 V, and the zener diode for determining the L voltage signal voltage from the terminal.
Set the zener voltage of ZD11 to 22V.

The Zener diode ZD21 and the transistor Tr21 determine whether the signal on the power / signal line is an H voltage signal by comparing the signal on the power / signal line connected to the terminal with the second determination level by the Zener diode. It is an example of a terminal-side signal receiving circuit that determines whether the signal is a voltage signal.
Note that, in the above embodiment, the second determination level is
This is the Zener voltage of the Zener diode ZD21.

Further, the first determination level is set higher than the second determination level. That is, the determination level (first determination level) of the receiving-side receiving circuit is set higher than the determination level (second determination level) of the terminal-side receiving circuit.

If the terminal T is a repeater, a fire detector, a waterproof device, a waterproof smoke exhaust device, and the like (not shown) are connected to the repeater.

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

FIG. 2 is a flowchart showing the operation of the receiving unit RE.

First, various initial settings are made (S1).
If it is necessary to turn on Tr12 and Tr13 and send a signal to the terminal T (S2, S3), the bit information to be sent is read. If the level of the bit to be sent is L (S4, S5), the transistor The transistor Tr14 is turned on, the transistors Tr12 and Tr13 are turned off (S6), and after a predetermined time has elapsed (S7), the transistor Tr is turned off.
12, Turn on Tr13 and turn off transistor Tr14 (S
8). If the level of the bit to be transmitted is H (S4, S4
5) Turn off the transistor Tr14 and set the transistors Tr12 and T
Leave r13 on. Then, after transmitting all the bits (S9), if there is no need for reception (S10), the process returns to S3.

On the other hand, if reception is necessary, the transistor Tr11 is turned on and the transistor Tr12 is turned off. After a lapse of a predetermined time (S11, S12), the output of the comparator CM1 is read (S13), and if it is at the L level (S14). , The corresponding bit is set to L (S15),
When the reception of the predetermined bit is completed, the reception signal is decoded, and the transistors Tr12 and Tr13 are turned on and the transistor Tr11 is turned off (S16, S17, S19). If the level read in S14 is H, the corresponding bit is set to H (S18).

FIG. 3 is a flowchart showing the operation of the terminal T in the above embodiment.

First, initial setting is performed (S21), a start signal is received, and after a predetermined time has elapsed (S22, S23), the output of the comparator CM2 composed of the Zener diode ZD21 and the transistor 21 is read (S24). If the level is L (S25), the corresponding bit is set to L (S2
6) If the level is H, the corresponding bit is set to H (S27).

Then, the reception of the predetermined bit is completed (S28), and if there is no call to the terminal T from the receiver RE (S29), the process returns to S22.

On the other hand, if there is a call from the receiver RE in S29, the command is decoded, and if it is necessary to return the command (S30, S31), the bit information to be transmitted is read (S32). If there is any (S33), the transistor Tr22 is turned on, and after a lapse of a predetermined time (S34, S35), the transistor Tr22 is turned on.
Is turned off (S36), and if all bits are transmitted (S37), S2
Return to 2. If transmission of all bits has not been completed (S37),
Return to S32.

As described above, the discrimination level of the signal receiving circuit on the receiving unit RE side (the Zener voltage of the Zener ZD11) and the discrimination level of the signal receiving circuit on the terminal T side (the Zener voltage of the Zener ZD21) are made different. By setting the Zener voltage of the Zener ZD11 higher than the Zener voltage, even if there is some line resistance, the power / signal line L
1. The effect of the voltage drop due to the line resistance of L2 can be eliminated, and therefore, a backup of a large capacity capacitor etc.
Therefore, the circuit configuration in the terminal can be simplified and downsized, and the reception unit RE can easily determine the H voltage signal from the terminal. Therefore, even if the line length changes,
This can be adequately dealt with.

Two terminals on the T side are connected to the terminals of the power / signal lines L1 and L2.
Between t21 and t22, the Zener diode ZD22 and the transistor Tr22 that is turned on when the terminal T outputs the L voltage signal toward the receiving unit RE are connected in series, so that a plurality of terminals simultaneously output the L voltage signal. Even if the voltage is output, the voltage between the two terminals on the terminal side of the power / signal line does not become lower than the zener voltage ZD22, and by setting the zener voltage of the zener diode ZD22 to a required voltage or more in advance, The L voltage signal can be reliably sent to the receiver RE.
In this case, the constant current circuit CC may be omitted, but if the constant current circuit CC is used, useless current flowing through the power / signal line can be reduced.

In the terminal T, a fixed resistor may be used instead of the Zener diode ZD22 for signal generation. However, in this case, the signal voltage is unnecessarily reduced due to a voltage drop due to the fixed resistor + line resistance. And
In some cases, the receiver RE cannot detect that the terminal T is transmitting the L voltage signal. However, in the above embodiment, there is no such concern.

Further, in the above embodiment, the signal of the power supply / signal line connected to the terminal side is compared with the discrimination level by the Zener diode ZD21. The voltage from the voltage circuit AVR21 may be used as the determination level. In this case, it is necessary to divide the voltage V2.

In the above embodiment, the receiver is described as a receiver and the repeater is a terminal. However, the same description can be applied to a case where the repeater is a receiver and a fire detector or the like is a terminal.

[Effect of the Invention] According to the present invention, even if there is some line resistance,
Eliminating the need to provide the terminal with a backup such as a large-capacitance capacitor has the effect of simplifying and miniaturizing the circuit configuration in the terminal, and making it easy for the receiver to determine the H voltage signal from the terminal.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the receiving unit RE in the above embodiment. FIG. 3 is a flowchart showing the operation of the terminal T in the above embodiment. RE: receiving unit, T: terminal, AVR11, AVR12, AVR21: constant voltage circuit, CC: constant current circuit, HC: H voltage signal transmission circuit, ZD11, ZD12, ZD22 ... Zener diode.

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

Claims (4)

(57) [Claims] 1. A fire alarm system in which a receiving unit transmits and receives an H voltage signal and an L voltage signal to and from a terminal via a power / signal line, wherein the receiving unit supplies power to the power / signal line. By comparing the signal of the power supply / signal line connected to the receiving section with a first determination level to determine whether the signal from the terminal is an H voltage signal or an L voltage signal. A signal receiving circuit on the receiving unit side;
A terminal-side signal receiving circuit that determines whether the signal from the receiving unit is an H voltage signal or an L voltage signal by comparing the signal from the receiving unit with the determination level. The power supply connected to the receiving side A fire alarm system wherein the first discrimination level for comparing the signal of the signal line is set higher than the second discrimination level for comparing the signal of the power and signal line connected to the terminal. . 2. The method according to claim 1, wherein the line resistance between the receiving unit and the terminal is determined according to a value of a line resistance.
A fire alarm system wherein a value of a difference between the first determination level and the second determination level is set. 3. The terminal-side signal receiving circuit according to claim 1, wherein the terminal-side signal receiving circuit includes: a transistor;
And a Zener diode that provides a discrimination level.
A fire alarm system wherein the Zener diode is connected in series with a base of the transistor. 4. A fire alarm system in which a receiving unit transmits and receives an H voltage signal and an L voltage signal to and from a terminal via a power / signal line. A Zener diode and a switching element that is turned on when the terminal outputs the L voltage signal toward the receiving unit are connected in series between the terminals, and the receiving unit is connected to the power / signal line. A fire alarm system comprising: a power supply for supplying power; and means for limiting a current to the terminal when the terminal returns a signal to the receiving unit.