JP7603413B2 - Fire Receiver - Google Patents

Description

The present invention relates to a fire receiver that is connected to a sensor line to which fire detectors are connected, and issues a fire alarm for each sensor line.

In a fire alarm system connected to a P-type fire receiver that issues a fire alarm for each sensor line to which a fire detector is connected, the fire detector that detects a fire notifies the fire receiver of the occurrence of a fire by lowering its own impedance and increasing the current flowing through the sensor line. In such a fire alarm system, a technology has been proposed in which the fire detector changes its own impedance in a pulse-like manner to transmit its own address information to the fire receiver as a transmission signal (see, for example, Patent Document 1).

JP 2004-038647 A

In Patent Document 1, the fire receiver also uses a sensor line to send a transmission signal to the fire sensor, and the fire receiver and the fire sensor send and receive transmission signals in both directions.

As described in Patent Document 1, a terminator is connected to a sensor line to which a P-type fire receiver is connected in order to detect whether the sensor line is broken. There are two types of terminators: one with a capacitor and one with a terminating resistor. Here, a terminator with a capacitor is called a first terminator, and a terminator with a terminating resistor is called a second terminator. The method of detecting a break varies depending on whether a first terminator or a second terminator is used for the sensor line. In a sensor line to which a first terminator is connected, the capacitor of the first terminator is constantly charged, and the impedance between the sensor lines is periodically lowered to discharge the capacitor, and the fire receiver detects whether a break is present or not by the rate of decrease in the line voltage of the sensor line. In a sensor line to which a second terminator is connected, if no break occurs, a weak current flows through the sensor line in the path of the second terminator in addition to the consumption current of the fire detector, and if a break occurs, the weak current through the path of the second terminator stops flowing through the sensor line. A fire receiver connected to a detector line with a second terminator detects whether or not there is a break in the detector line by the current flowing through the detector line.

As mentioned above, existing fire alarm systems have a sensor line connected to a first terminator and a sensor line connected to a second terminator. The sensor line connected to the first or second terminator is installed when the building is constructed and is used for a long period of time thereafter, but the fire receiver may be renewed as the system ages. When renewing, the type of fire receiver to be used must be different depending on whether the first or second terminator is connected to the installed sensor line. This requires the manufacture of two types of fire receivers, which leads to increased manufacturing costs. Alternatively, it is possible to replace the first or second terminator connected to the end of the sensor line with one that matches the fire receiver's disconnection detection method, but the task of finding and replacing terminators for all of the multiple sensor lines installed in the building is a heavy burden.

The present invention was made in consideration of the above situation, and provides a fire receiver that can detect a disconnection regardless of whether the first or second terminator is connected to the detector line.

The fire receiver of the present invention is a fire receiver connected to a sensor line to which a fire sensor and a terminator are connected, and comprises: a power supply unit that applies a power supply voltage to the sensor line; a line monitoring unit that monitors the voltage of the sensor line and detects a fire signal from the fire sensor connected to the sensor line; a signal transmitting unit that transmits a transmission signal to the fire sensor by changing the line voltage of the sensor line; and, if the terminator includes a capacitor, a control unit that detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmitting unit changes the line voltage , and, if the terminator is a termination resistor, a control unit that detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmitting unit does not change the line voltage.

The fire receiver of the present invention can detect a disconnection regardless of whether the first or second terminator is connected to the detector line.

1 is an explanatory diagram of a fire alarm system 100 including a fire receiver 1 according to embodiment 1. 3A and 3B are diagrams illustrating a transmission signal according to the first embodiment. 5 is a timing chart illustrating a disconnection detection function when a first terminator 13A according to the first embodiment is connected. 10 is a timing chart illustrating a deterioration determination function of a capacitor of a first terminator according to the second embodiment.

The following describes an embodiment of the present invention with reference to the drawings. The present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention. The present invention also includes all possible combinations of the configurations shown in the following embodiment. The device shown in the drawings is an example of the device of the present invention, and the device of the present invention is not limited to the device shown in the drawings. In addition, in each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the entire specification.

Embodiment 1.
(Configuration of fire alarm system 100)
FIG. 1 is an explanatory diagram of a fire alarm system 100 including a fire receiver 1 according to the first embodiment. The fire alarm system 100 is installed in buildings such as hotels, apartment buildings, office buildings, and commercial facilities, and monitors fires and issues an alarm when a fire is detected. The fire alarm system 100 includes a fire receiver 1, a sensor circuit 10 consisting of a common line 11 and a line line 12 drawn from the fire receiver 1, and a fire sensor 20 connected to the sensor circuit 10. The fire sensor 20 notifies the fire receiver 1 of the detection of a fire by lowering the line voltage of the sensor circuit 10 and increasing the current flowing through the sensor circuit 10. The sensor circuit 10 serves both as a power line for supplying power to the fire sensor 20 and as a signal line for transmitting and receiving signals between the fire sensor 20 and the fire receiver 1.

A first terminator 13A or a second terminator 13B is connected to the end of the sensor line 10. The first terminator 13A is configured by connecting a resistor 133 and a capacitor 132 in series. The resistor 133 is for reducing the charge to the capacitor 132. The second terminator 13B is composed of a terminating resistor 131 and does not have a capacitor 132. As shown in FIG. 1, different types of terminators, the first terminator 13A and the second terminator 13B, can be connected to the fire receiver 1 of this embodiment. Note that, although this embodiment shows an example in which the different types of first terminator 13A and second terminator 13B are connected to the fire receiver 1, the fire receiver 1 of this embodiment can also be applied to a sensor line 10 to which only one of the terminators is connected.

Figure 1 shows an example in which two sensor lines 10 are connected to a fire receiver 1, but the number of sensor lines 10 is not limited to the example shown. Also, Figure 1 shows an example in which two fire sensors 20 are connected to one sensor line 10, but the number of fire sensors 20 is also not limited to the example shown.

(Configuration of fire detector 1)
The fire receiver 1 comprises a main control unit 2, a sub-control unit 3, a power supply unit 4, a receiving resistor 5, a line monitoring unit 6, and a signal transmission unit 7. The same number of sets each consisting of the sub-control unit 3, the power supply unit 4, the receiving resistor 5, the line monitoring unit 6, and the signal transmission unit 7 are provided as the number of sensor lines 10. The main control unit 2 and the sub-control unit 3 form the control unit of the fire receiver 1, with the main control unit 2 controlling the entire fire receiver 1 and the sub-control unit 3 controlling the sensor lines 10.

The main control unit 2 transmits and receives signals to and from the sub-control unit 3. The main control unit 2 outputs control signals to the sub-control unit 3 and controls the sub-control unit 3. The main control unit 2 is composed of dedicated hardware or a processor that executes programs stored in a memory (not shown).

The sub-controller 3 monitors one sensor line 10, receives output from the line monitor 6 connected to that sensor line 10, and controls the power supply unit 4 and signal transmitter 7 connected to that sensor line 10. The sub-controller 3 is composed of dedicated hardware or a processor that executes a program stored in a memory (not shown). Note that one sub-controller 3 may be configured to monitor multiple sensor lines 10, or the main controller 2 may also function as the sub-controller 3, and the main controller 2 may be configured to monitor multiple sensor lines 10.

The power supply unit 4 converts the AC voltage supplied from a commercial power source (not shown) into a DC voltage of, for example, 24 V, and supplies it to the common line 11 of the sensor circuit 10.

The receiving resistor 5 is connected in parallel with the line monitoring unit 6 and the line wire 12. A current flows through the receiving resistor 5, which is supplied from the power supply unit 4 to the common wire 11 and passes through the fire detector 20, the first terminator 13A or the second terminator 13B, and the line wire 12. When a current flows through the receiving resistor 5, a voltage is generated across the receiving resistor 5. This voltage is called the receiving voltage. In this way, the receiving resistor 5 converts the current into a receiving voltage, and the receiving voltage is input to the line monitoring unit 6.

The power supply voltage supplied from the power supply unit 4 is divided into [line impedance of the sensor circuit 10]:[receiving resistance], which is the impedance between the common line 11 and the line line 12. In other words, the power supply voltage is divided into a line voltage and a receiving voltage. Therefore, the receiving voltage is the value obtained by subtracting the line voltage from the power supply voltage. Here, the line impedance of the sensor circuit 10 is the composite impedance of the impedance of the fire sensor 20 connected to the sensor circuit 10 and the impedance of the first terminator 13A or the second terminator 13B.

The line monitoring unit 6 judges the state of the sensor line 10. Specifically, by monitoring the voltage of the sensor line 10, it judges whether the state is normal, a fire state, or a disconnection state, and outputs the judgment result. The line monitoring unit 6 has a fire threshold for judging whether or not there is a fire state, and a disconnection threshold for judging whether or not there is a disconnection state when the terminator is the second terminator, and judges the state of the sensor line 10 by comparing the received voltage input via the receiving resistor 5 with the fire threshold and the disconnection threshold. The disconnection threshold is a value smaller than the fire threshold. The line monitoring unit 6 performs a delay operation to confirm the judgment when the sensor line 10 continues in the same state for a predetermined delay time, so as not to be affected by momentary voltage changes in the sensor line 10 due to noise.

The signal transmission unit 7 is connected to the common line 11 and the line line 12, and transmits a transmission signal to the fire detector 20 by changing the line voltage of the detector line 10. The transmission operation of the transmission signal will be described later.

(Configuration of Fire Detector 20)
The fire detector 20 is a heat detector, a smoke detector, or a flame detector. When multiple fire detectors 20 are connected to one detector line 10, the fire detectors 20 are connected by a feeder wiring. When the end of the detector line 10 is a fire detector 20, the first terminator 13A or the second terminator 13B is connected to the fire detector 20 at the end. The fire detector 20 has a built-in contact 21 connected to the detector line 10. The contact of the fire detector 20 is normally open. Therefore, during normal times when the fire detector 20 does not detect a fire, only a weak current flows through the detector line 10. When the fire detector 20 detects a fire, it closes the contact 21 connected to the detector line 10, lowering the line voltage of the detector line 10 and allowing a current greater than normal to flow through the detector line 10. This current greater than normal becomes a fire signal and notifies the fire receiver 1 of the occurrence of a fire.

In this embodiment, only the contact 21 is shown for the fire detector 20, but the fire detector 20 is composed of a processor and the like. The fire detector 20 normally operates with a very small current consumption, so the contact 21 in the above description is in an open, high impedance state. On the other hand, when the fire detector 20 detects a fire, a large current flows, so the contact 21 in the above description is in a closed, low impedance state. Hereinafter, the operation of the fire detector 20 will be described as the operation of the contact 21.

(Fire alarm operation of fire receiver 1)
When the power is turned on, the fire receiver 1 supplies a power supply voltage to the sensor line 10 by the power supply unit 4. The power supply voltage is, for example, 24 V. The received voltage is input from the receiving resistor 5 to the line monitoring unit 6. The line monitoring unit 6 periodically compares the received voltage with a fire threshold to determine a fire state. When the fire detector 20 detects a fire and closes the contacts 21, and the line monitoring unit 6 detects a drop in the line voltage of the sensor line 10, a detection signal from the line monitoring unit 6 is input to the sub-controller 3. When the sub-controller 3 receives the detection signal, it notifies the main control unit 2, and the main control unit 2 performs an alarm operation when a fire is detected.

After the fire detector 20 detects a fire and the fire receiver 1 performs an alarm operation, when a recovery switch (not shown) provided on the fire receiver 1 is operated to input a recovery signal, the main control unit 2 disconnects the power supply unit 4 from the detector line 10 and cuts off the power supply to the fire detector 20. This causes the fire detector 20 to return to its normal state. By returning to its normal state, the contacts 21 of the fire detector 20 are opened.

(Signal transmission operation by fire detector 1)
FIG. 2 is a diagram for explaining a transmission signal according to the first embodiment. FIG. 2 shows a waveform of the line voltage of the sensor line 10. The signal transmission unit 7 of the fire receiver 1 changes the line voltage of the sensor line 10 between a high level and a low level. In FIG. 2, the high level is indicated by H, and the low level is indicated by L. Normally, the line voltage is maintained at a high level. The signal transmission unit 7 changes the line voltage to a low level in a pulsed manner to form a waveform as shown in FIG. 2, and transmits this waveform to the fire sensor 20 as a transmission signal. The transmission signal transmitted by the fire receiver 1 is, for example, a request signal that requests the fire sensor 20 to transmit an address or a status. The high level line voltage is, for example, 24 V, and the low level line voltage is, for example, 8.2 V.

The low-level line voltage transmitted by the signal transmission unit 7 only needs to be equal to or lower than the voltage at which the line monitoring unit 6 judges a fire to be present when compared with the fire threshold. The signal transmission unit 7 can also simulate a fire state for testing purposes. Specifically, the low-level line voltage of the signal transmission unit 7 is set to the same value as the line voltage when the fire detector 20 closes the contacts 21. In this way, the same received voltage as when the fire detector 20 detects a fire is input to the line monitoring unit 6, and the operation of the fire receiver 1 when a fire occurs can be tested. Thus, according to this embodiment, the signal transmission unit 7 can be used for both transmitting a transmission signal and for fire testing. Therefore, there is no need to provide a separate circuit, and the manufacturing cost of the fire receiver 1 can be reduced.

(Fire detector 1 detects broken wire)
Next, the operation of the fire receiver 1 of this embodiment to detect the presence or absence of a disconnection in the sensor line 10 will be described. In the fire receiver 1, whether the first terminator 13A or the second terminator 13B is connected to each of the sensor lines 10 is set in advance by the user. The sub-controller 3 may store the type of terminator of the corresponding sensor line 10, or the main controller 2 may store the types of terminators of all the sensor lines 10. Alternatively, the type of terminator may be set for each circuit board to which the sensor line 10 is connected.

The fire receiver 1 of this embodiment is characterized in that it uses the signal transmission unit 7 described above to detect whether or not the sensor line 10 is disconnected. This is explained in detail below.

Figure 3 is a timing chart explaining the disconnection detection function when the first terminator 13A according to embodiment 1 is connected. As shown in Figure 3, the signal transmission unit 7 of the fire receiver 1 sets the line voltage of the sensor line 10 to a low level in period T1, and sets the line voltage of the sensor line 10 to a high level in period T2. The low level period T1 and the high level period T2 are alternately repeated.

3(a) shows the received voltage detected by the line monitoring unit 6 when no break occurs in the sensor line 10 to which the first terminator 13A is connected. Here, the received voltage is the value obtained by subtracting the line voltage from the power supply voltage, so that the waveform is upside down compared to the line voltage. When the line voltage is changed to a low level by the signal transmitting unit 7, a large current flows through the receiving resistor 5, and the received voltage input to the line monitoring unit 6 rises with a predetermined time constant. Since the capacitor 132 provided in the first terminator 13A is charged, even if the line voltage changes sharply from a high level to a low level, the line voltage gradually drops due to the discharge from the capacitor 132, so the received voltage also rises gradually. Then, when the line voltage is changed to a high level by the signal transmitting unit 7, the capacitor 132 of the first terminator 13A is charged, and the received voltage of the line monitoring unit 6 drops and returns to a normal state. The length of the period T1 during which the line voltage is at a low level is set to a period during which the capacitor 132 is not completely discharged. In this way, the line voltage can be prevented from reaching, for example, 8.2 V, and the received voltage can be prevented from exceeding the fire threshold.

When there is no break in the sensor line 10 to which the first terminator 13A is connected, the signal transmission unit 7 alternately switches the line voltage between high and low levels, resulting in the received voltage waveform shown in Figure 3(a). The line monitoring unit 6 does not receive a received voltage higher than the fire threshold. In this state, the sub-control unit 3 determines that there is no break in the sensor line 10.

Figure 3 (b) shows the received voltage detected by the line monitoring unit 6 when a break occurs in the sensor line 10 to which the first terminator 13A is connected. When the signal transmission unit 7 changes the line voltage to a low level, a large amount of current flows through the receiving resistor 5, and the received voltage input to the line monitoring unit 6 rises sharply. When the signal transmission unit 7 changes the line voltage to a high level, the received voltage of the line monitoring unit 6 drops and returns to a normal state. If a break occurs in the sensor line 10 to which the first terminator 13A is connected, when the signal transmission unit 7 changes the line voltage to a low level, the line monitoring unit 6 detects the steep voltage rise shown in Figure 3 (b). By comparing the received voltage at this time with the fire threshold, the line monitoring unit 6 outputs a signal indicating a break to the sub-controller 3.

In this embodiment, the sub-controller 3 determines whether or not there is a disconnection by comparing the received voltage with the fire threshold, but the fire threshold and the threshold for determining a disconnection may be separate. The threshold for determining a disconnection can be set appropriately according to the capacity of the capacitor 132 of the second terminator, the low level period T1 and the high level period T2 output by the signal transmitter 7.

Next, detection of a disconnection in the sensor line 10 to which the second terminator 13B is connected will be described. When the second terminator 13B without the capacitor 132 is connected to the sensor line 10, if no disconnection occurs, a weak current flows through the sensor line 10 via the termination resistor 131 of the second terminator 13B. The line monitoring unit 6 detects the received voltage corresponding to this weak current, and if a weak current is flowing, it determines that no disconnection has occurred. If a disconnection occurs in the sensor line 10, no current flows through the termination resistor 131 of the second terminator 13B, and the line monitoring unit 6 cannot detect the received voltage corresponding to the weak current. The line monitoring unit 6 detects that a disconnection has occurred in the sensor line 10 by comparing the received voltage with the disconnection threshold, and outputs a signal indicating the disconnection to the sub-control unit 3.

As described above, in the fire receiver 1 of this embodiment, when the first terminator 13A is connected to the sensor line 10, the presence or absence of a disconnection is detected based on the received voltage detected by the line monitoring unit 6 when the signal transmitting unit 7, which transmits a transmission signal to the fire sensor 20, changes the line voltage. Also, when the second terminator 13B is connected to the sensor line 10, the presence or absence of a disconnection in the sensor line 10 is detected based on the received voltage detected by the line monitoring unit 6. Therefore, a disconnection can be detected whether the first terminator 13A including the capacitor 132 is connected to the sensor line 10 or whether the second terminator 13B including the termination resistor 131 is connected to the sensor line 10.

In addition, in this embodiment, the signal transmission unit 7 is used to detect a disconnection when the first terminator 13A is connected. Therefore, it is possible to detect the presence or absence of a disconnection in the sensor line 10 to which the first terminator 13A is connected without providing a dedicated circuit for disconnection detection. Therefore, it is possible to suppress an increase in the manufacturing cost of the fire receiver 1.

(Modification)
In the first embodiment, it has been described that which of the first terminator 13A and the second terminator 13B is connected is set in advance by the user for each sensor line 10. As a modified example, a terminator discrimination function that determines which of the first terminator 13A and the second terminator 13B is connected using the signal transmission unit 7 will be described with reference to FIG.

It is assumed that it is unknown whether the first terminator 13A or the second terminator 13B is connected to each sensor line 10. As shown in FIG. 3, when the signal transmission unit 7 determines the terminator, it changes the line voltage of the sensor line 10 from high to low. When the first terminator 13A is connected, the received voltage input to the line monitoring unit 6 rises gradually as shown in FIG. 3(a) due to the discharge from the capacitor 132. On the other hand, when the second terminator 13B is connected, since there is no capacitor 132, the received voltage input to the line monitoring unit 6 rises sharply as shown in FIG. 3(b).

In this way, when the signal transmission unit 7 reduces the line voltage, the received voltage input to the line monitoring unit 6 can detect whether the first terminator 13A or the second terminator 13B is connected to the sensor line 10. Therefore, even if many years have passed since the installation of the sensor line 10 and the user does not know whether the first terminator 13A or the second terminator 13B is connected to the sensor line 10, it is possible to detect a break in the line regardless of the type of terminator.

Embodiment 2.
In this embodiment, a function for determining deterioration of the capacitor 132 of the first terminator 13A will be described. This embodiment is added to the configuration described in embodiment 1. The structure of the fire control panel 1 of this embodiment is the same as that described in FIG.

Figure 4 is a timing chart explaining the deterioration determination function of the capacitor 132 of the first terminator 13A in the second embodiment. The transmission signal shown in Figure 4 is the same as that shown in Figure 3, and shows a waveform that is generated by changing the line voltage by the signal transmitter 7. Figure 4 (a) shows the received voltage in a state where there is no deterioration in the capacitor 132 of the first terminator 13A, and Figure 4 (a1) shows the received voltage in a state where there is deterioration in the capacitor 132 of the first terminator 13A.

When the capacitor 132 deteriorates, as shown in FIG. 4(a1), the value of the received voltage when the signal transmission unit 7 transmits the transmission signal increases over time. Specifically, when the signal transmission unit 7 sets the line voltage to a low level, which is the first voltage, during period T1, the received voltage input to the line monitoring unit 6 increases over time. Also, when the signal transmission unit 7 sets the line voltage to a high level during period T2, the received voltage input to the line monitoring unit 6 increases over time. The time required to charge the capacitor 132 also increases. In this embodiment, the sub-control unit 3 determines the deterioration state of the capacitor 132 of the first terminator 13A by comparing the first detection value, which is the received voltage input to the line monitoring unit 6 when the signal transmission unit 7 sets the line voltage to a low level, with a reference value. Alternatively, the sub-controller 3 determines the deterioration state of the capacitor 132 of the first terminator 13A by comparing the received voltage input to the line monitoring unit 6 when the signal transmitting unit 7 switches the line voltage from low level to high level with a reference value. The reference value is stored in advance in the sub-controller 3. When determining the deterioration of the capacitor 132, the pulse width of the transmission signal, i.e., the length of the periods T1 and T2, may be made shorter than when a normal transmission signal is transmitted. In this way, the change in the received voltage due to the deterioration of the capacitor 132 becomes noticeable, making it easier to determine the deterioration of the capacitor 132.

As described above, according to this embodiment, when the first terminator 13A including the capacitor 132 is connected to the sensor line 10, the voltage detected by the line monitoring unit 6 when the signal transmission unit 7 changes the line voltage is compared with a reference value. Then, the deterioration state of the capacitor 132 is determined based on the comparison result. Therefore, when it is determined that the capacitor 132 is deteriorated, the user is notified, thereby making it possible to avoid continued use of the deteriorated first terminator 13A. Furthermore, according to this embodiment, there is no need to provide a dedicated circuit component for determining deterioration of the capacitor 132 of the first terminator 13A, so that an increase in the manufacturing cost of the fire receiver 1 can be suppressed.

1 Fire receiver, 2 Main control unit, 3 Sub-control unit, 4 Power supply unit, 5 Receiving resistor, 6 Line monitoring unit, 7 Signal transmission unit, 10 Sensor line, 11 Common line, 12 Line line, 13A First terminator, 13B Second terminator, 20 Fire detector, 21 Contact, 100 Fire alarm system, 131 Termination resistor, 132 Capacitor, 133 Resistor.

Claims (2)

A fire receiver connected to a detector line to which a fire detector and a terminator are connected,
A power supply unit that applies a power supply voltage to the sensor line;
a line monitoring unit that monitors a voltage of the detector line and detects a fire signal from the fire detector connected to the detector line;
a signal transmitting unit that transmits a transmission signal to the fire detector by changing a line voltage of the detector line;
When the terminator includes a capacitor, detecting the presence or absence of a disconnection of the sensor line based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmission unit changes the line voltage,
A fire receiver comprising: a control unit that, when the terminator is a termination resistor, detects whether or not the sensor line is disconnected based on the line voltage of the sensor line detected by the line monitoring unit when the signal transmitting unit is not changing the line voltage. When the terminator includes a capacitor,
the control unit determines a deterioration state of the capacitor by comparing a first detection value, which is a voltage of the sensor line detected by the line monitoring unit when the signal transmission unit sets the line voltage to a first voltage, with a reference value ;
If it is determined that the capacitor is deteriorated, a notification is given.
2. The fire receiver according to claim 1.

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