booster

Abstract

To enable fire monitoring by all fire sensors even if a disconnection failure occurs in a loop transmission line connected in a loop shape to a receiver or a relay connected to the receiver.SOLUTION: An input / output switching type booster 16, in a fire alarm facility in which the input / output switching type booster is provided in a loop transmission line, is inserted and connected to a receiver 10 in the middle of the loop transmission line 12 connected in a loop shape, amplifies and outputs a signal inputted from one to the other, and switches an amplification direction by an operation test in which the receiver 10 transmits the signal from a terminal end side without transmitting the signal from a starting end side of the loop transmission line 12, and the operation test in which the receiver 10 transmits the signal from the starting end side of the loop transmission line 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a booster used in a fire alarm system that monitors fires by connecting a fire detector to a loop transmission line from a receiver. [Background technology]

[0002] In conventional fire alarm systems known as the R type, a terminal device such as a fire detector with a transmission function is connected to a transmission line drawn from a receiver, and when a fire is detected, for example, based on a fire interrupt from the fire detector, a search command is issued to identify the address of the fire detector that triggered the alarm, the address where the fire occurred is displayed, and fire data is collected and monitored from the identified fire detector.

[0003] In this way, knowing the address of the fire detector that detected the fire makes it possible to provide appropriate evacuation guidance and firefighting activities, making this a function that is essential especially for fire monitoring in large-scale facilities.

[0004] In addition, in order to ensure reliability against disconnection failures in the transmission line drawn from the fire receiver, a fire alarm system is known in which a fire detector is connected to a loop transmission line connected in a loop to the receiver to monitor fires.

[0005] FIG. 6 is an explanatory diagram of a conventional fire alarm system using a loop transmission line, where FIG. 6(A) shows a normal monitoring state and FIG. 6(B) shows a case where a disconnection fault has occurred.

[0006] 6(A), a transmission line 12 using a pair of signal lines is drawn from a transmission unit 22 provided in the receiver 10, and the transmission line 12 is arranged in a loop shape, that is, the transmission line 12 is drawn from the receiver 10 and then returns to the receiver 10. In the following explanation, the transmission line 12 connected in a loop shape to the receiver 10 is referred to as a loop transmission line 12.

[0007] A fire detector 18 equipped with a transmission function is connected between the signal lines of the loop transmission line 12, and a unique detector address is set to the fire detector 18. Fires are monitored by transmitting a downstream signal that changes the line voltage from the transmission unit 22 and an upstream signal that changes the line current from the fire detector 18.

[0008] A disconnection monitoring control unit 28 is provided at the end of the loop transmission line 12 drawn into the fire control receiver 10, and monitors for disconnection faults in the loop transmission line 12 based on the line voltage supplied from the transmission unit 22 to the loop transmission line 12. Also, switching circuit units 30a and 30b are provided at the end of the loop transmission line 12 to switch and connect the signal line at the end to the transmission unit 22, and in the normal monitoring state, the switching circuit units 30a and 30b are disconnected from the transmission unit 22.

[0009] As shown in Figure 6(B), if a break 31a occurs in the middle of the loop transmission line 12 during operation, the break monitoring control unit 28 detects a break fault due to the line voltage at the end of the loop transmission line 12 being cut off, and activates the switching circuit units 30a and 30b to connect the end side of the loop transmission line 12 to the transmission unit 22.

[0010] Therefore, the signal from the transmission unit 22 is transmitted from the end of the loop transmission line 12 to the location where the break 31a occurred via the switching circuit units 30a and 30b, making it possible to send and receive signals between the location where the break 31a occurred and the fire detector 18 connected between the end of the loop transmission line 12.Even if a break occurs, the fire monitoring function of the fire detector 18 connected to the loop transmission line 12 will not be lost, and high reliability is achieved. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-004033 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-114632 [Patent Document 3] Japanese Patent Application Publication No. 1-297931 [Patent Document 4] Microfilm of Utility Model Application No. 156218-1984 [Patent Document 5] Japanese Patent Application Publication No. 2-28798 Summary of the Invention [Problem to be solved by the invention]

[0012] When fires are monitored using a fire detector connected to a loop transmission line from a receiver, the transmission line is pulled out into the alert zone and then returned to the receiver. This means that the loop transmission line is roughly twice as long as a normal transmission line pulled out from the receiver to the alert zone, and the line resistance at the end of the loop transmission line also increases. For example, if the transmission line resistance required to receive downstream and upstream signals between the transmitter and fire detector is 30 ohms, the loop transmission line will have a 60 ohm end, making it impossible to send and receive signals to and from fire detectors connected in a transmission line range exceeding 30 ohms. For this reason, it is possible to install a booster along the loop transmission line.

[0013] Figure 7 is an explanatory diagram showing a conventional fire alarm system in which a booster is installed on a loop transmission line. Figure 7(A) shows the normal monitoring state, and Figure 7(B) shows the case where a wire breakage fault has occurred.

[0014] 7(A), the booster 100 is inserted and connected, for example, at a return position that is halfway along the loop transmission line 12. Here, the section between the start of the loop transmission line 14 drawn out from the receiver 10 and the booster 100 is referred to as the start-side transmission line 12a, and the section between the booster 100 and the end of the loop transmission line 12 returned to the receiver 10 is referred to as the end-side transmission line 12b.

[0015] The booster 100 amplifies the downstream signal input from the start-end transmission line 12a using the voltage boost circuit unit 102 and outputs it to the termination-end transmission line 12b, and also amplifies the upstream signal input from the termination-end transmission line 12b using the current boost circuit unit 104 and outputs it to the start-end transmission line 12a.Even if the line length of the loop transmission line 12 increases, a decrease in the signal level between the fire detector 18 connected to the termination side of the loop transmission line 12 is prevented, and signal transmission and reception with the transmission unit 22 can be reliably performed.

[0016] However, even if a booster 100 is provided in the loop transmission line 12, as shown in Figure 7(B), if, for example, a break 31b occurs in the start-side transmission line 12a of the loop transmission line 12 and the end side of the loop transmission line 12 is connected to the transmission section 22 by the operation of the switching circuits 30a and 30b by the break monitoring control section 28, the booster 100 amplifies the downstream signal and the upstream signal in only one direction using the voltage boost circuit section 102 and the current boost circuit section 104, so the downstream signal transmitted from the end side of the loop transmission line 12 via the switching circuits 30a and 30b cannot pass through the booster 100, and the upstream signal from the fire detector 18 between the booster 100 and the point where the break 31b occurred cannot pass through the booster 100 either, resulting in the problem of losing the fire monitoring function of the fire detector 18 connected between the booster 100 and the point where the break 31b occurred.

[0017] The present invention aims to provide a booster for use in fire alarm equipment that enables fire monitoring by all fire detectors even if a disconnection occurs in a loop transmission line connected in a loop to a receiver or a repeater connected to the receiver. [Means for solving the problem]

[0018] (Amplification based on operational test and output (Booster that switches the direction of the signal) The present invention is a booster used in a fire alarm system in which a fire detector is connected to a loop transmission line that is connected in a loop to a receiver or a repeater connected to the receiver, The booster is A unique address is set. Inserted and connected in the middle of the loop transmission line 、 Input from one side Downstream from the receiver to the fire detector Amplify the signal and output to the other end At the same time , The upstream signal from the fire detector to the receiver is amplified and output to one side, From the receiver Through a loop transmission line sent Instructs switching of the signal amplification direction directed at itself Based on signal operation tests, A downstream signal input from the other side is amplified and output to one side, and an upstream signal input from one side is amplified and output to the other side. amplification and output do Upbound signal and downstream signals Switching the direction of operation The method is characterized by carrying out the following. [Brief explanation of the drawings]

[0021] [Figure 1] An explanatory diagram showing the outline of a fire alarm system with an input / output switching booster installed on a loop transmission line [Figure 2] Block diagram showing an embodiment of an input / output switching booster [Figure 3] Block diagram showing the operation of the input / output switching booster when a disconnection fault occurs in the start-end transmission line [Figure 4] Block diagram showing the operation of the input / output switching booster in normal monitoring mode and when a disconnection fault occurs in the termination transmission line. [Figure 5] A block diagram showing another embodiment of an input / output switching type booster. [Figure 6] An explanatory diagram showing a conventional fire alarm system equipped with a loop transmission line. [Figure 7] An explanatory diagram showing a conventional fire alarm system with a booster installed on a loop transmission line. DETAILED DESCRIPTION OF THE INVENTION

[0022] [Fire alarm system] (Fire alarm system overview) Figure 1 is an explanatory diagram showing an overview of a fire alarm system in which an input / output switching booster is installed in a loop transmission line. As shown in Figure 1, an R-type receiver 10 is installed in a caretaker's room on the first floor of a building where the fire alarm system is installed, and a loop transmission line 12 using a pair of signal lines 14a and 14b is drawn from the receiver 10 to the alert area.

[0023] A plurality of fire detectors 18 each having a transmission function and each having a unique address are connected to the loop transmission line 12. An input / output switching type booster 16 is inserted and connected at an intermediate position of the loop transmission line 12.

[0024] Here, the maximum number of addresses that can be set for a terminal including a fire detector 18 connected to the loop transmission path 12 is, for example, 255, and since the input / output switching type booster 16 also has a transmission function, a maximum of 254 fire detectors 18 can be connected to the loop transmission path 12.

[0025] (Receiver functional configuration) The receiver 10 includes a reception control unit 20, a transmission unit 22, an operation unit 23, a display unit 24, an alarm unit 25, a signal transfer unit 26, a disconnection monitoring control unit 28, and switching circuit units 30a and 30b.

[0026] The reception control unit 20 is a computer circuit or the like equipped with a CPU, memory, various input / output ports, etc. The transmission unit 22 transmits and receives signals to and from the fire detector 18 connected to the loop transmission line 12 in accordance with a predetermined communication protocol.

[0027] The downstream signal from the transmission unit 22 to the fire detector 18 is transmitted in voltage mode. This voltage mode signal is transmitted as a voltage pulse that changes the line voltage of the loop transmission line 12 between, for example, 18 volts and 30 volts.

[0028] On the other hand, the upstream signal from the fire detector 18 to the receiver 10 is transmitted in current mode. In this current mode, a signal current is passed through the loop transmission line 12 at the timing of bit 1 of the transmission data, and the upstream signal is transmitted to the receiver as a so-called current pulse train.

[0029] Monitoring control by the reception control unit 20 of the receiver 10 is as follows. During normal monitoring, the reception control unit 20 periodically instructs the transmission unit 22 to transmit a broadcast batch AD conversion signal containing a batch AD conversion command. Upon receiving this batch AD conversion signal, the fire detector 18 detects and stores the smoke density or temperature as sensor data. Next, the reception control unit 20 transmits a call signal containing a polling command that sequentially specifies the terminal addresses.

[0030] When the fire detector 18 receives a call signal with an address that matches its own address, it transmits a response signal including the sensor data it is holding at that time to the receiver 10. When the fire detector 18 detects a fire, it transmits a fire interrupt signal to the receiver 10. When the reception control unit 20 receives the fire interrupt signal via the transmission unit 22, it transmits a group search command signal to identify the group that includes the fire detector 18 that has detected the fire, and then transmits an intra-group search command signal to identify the address of the fire detector 18 that has detected the fire, and displays the fire occurrence address while collecting and monitoring fire data from the identified fire detector.

[0031] The disconnection monitoring control unit 28 detects and monitors the signal voltage obtained at the end of the loop transmission line 12. When a disconnection occurs in the loop transmission line 12, the signal voltage is cut off and becomes undetectable, thereby detecting the disconnection. By turning on switching circuit units 30a, 30b, which use relay contacts and switch elements, the transmission unit 22 is connected to the end of the loop transmission line 12, and signals are sent and received in parallel to the transmission line between both ends of the loop transmission line 12 and the disconnection location, thereby recovering from the disconnection fault.

[0032] In the normal monitoring state, the input / output switching booster 16 voltage-amplifies the downstream signal (voltage pulse signal) input from the start-side transmission line 12a and outputs it to the termination-side transmission line 12b, and current-amplifies the upstream signal (current pulse signal) input from the termination-side transmission line 12b and outputs it to the start-side transmission line 12a. When a disconnection fault occurs in the start-side transmission line 12a, the input / output switching booster 16 is configured to switch inputs and outputs so that, on the condition that the end of the loop transmission line 12 is connected to the transmission unit 22 by the operation of the switching circuit units 30a, 30b by the disconnection monitoring control unit 28, the downstream signal (voltage pulse signal) input from the termination-side transmission line 12b is voltage-amplified and output to the start-side transmission line 12a, and current-amplified the upstream signal (current pulse signal) input from the start-side transmission line 12a and output it to the termination-side transmission line 12b.

[0033] The input / output switching booster 16 operates on power supplied from a commercial power source, and further includes an emergency battery that is powered under normal circumstances and functions as an operating power source in the event of a power outage.

[0034] The input / output switching booster 16 operates on power supplied from a commercial power source and is provided with an indicator lamp that displays status information such as the power supply state and the signal amplification direction.

[0035] The input / output switching booster 16 has a unique address, and when it recognizes a signal sent from the receiver to itself, it responds to the signal by returning status information, switching the signal amplification direction, or performing other actions in response to the signal.

[0036] The input / output switching booster 16 includes a circuit for short circuit protection.

[0037] [Input / output switching booster] Fig. 2 is a block diagram showing an embodiment of an input / output switching type booster. As shown in Fig. 2, the input / output switching type booster 16 is composed of a downstream signal boost circuit unit (voltage boost circuit unit) 32, an upstream signal boost circuit unit (current boost circuit unit) 46, a booster control unit 34, a transmission unit 36, a first voltage detection unit 38, a second voltage detection unit 40, downstream signal input / output switching circuit units 42 and 44, and upstream signal input / output switching circuit units 48 and 50. The downstream signal boost circuit unit 32 functions as a voltage boost circuit unit, and the upstream signal boost circuit unit 46 functions as a current boost circuit unit.

[0038] The downstream signal boost circuit section 32 is a circuit section that amplifies the voltage of the input downstream signal, that is, a voltage pulse signal, in one direction and outputs the amplified signal, and includes a voltage amplifier and a waveform shaping circuit.

[0039] The upstream signal boost circuit section 46 is a circuit section that amplifies the current of the input upstream signal, that is, a current pulse signal, in one direction and outputs the amplified signal, and includes a current amplifier and a waveform shaping circuit.

[0040] The downstream signal input / output switching circuit units 42, 44 are configured with switching elements such as switching relay contacts or FETs. The downstream signal input / output switching circuit unit 42 is provided on the input side of the downstream signal boost circuit unit 32, with the positive side of the start-side transmission line 12a connected to its switching terminal a, the positive side of the end-side transmission line 12b connected to its switching terminal b, and the common terminal c connected to the input of the downstream signal boost circuit unit 32.

[0041] The downstream signal input / output switching circuit unit 44 is provided on the output side of the downstream signal boost circuit unit 32, with the positive side of the termination side transmission line 12b connected to the switching terminal a, the positive side of the start side transmission line 12a connected to the switching terminal b, and the common terminal c connected to the output of the downstream signal boost circuit unit 32.

[0042] The downstream signal input / output switching circuit units 42, 44 have a first switching position on the side of switching terminal a and a second switching position on the side of switching terminal b. Therefore, when the downstream signal input / output switching circuit units 42, 44 are in the first switching position where they are the illustrated switching terminal a, the start-side transmission line 12a is input-connected to the downstream signal boost circuit unit 32 and the output of the downstream signal boost circuit unit 32 is connected to the termination-side transmission line 12b, and when they are in the second switching position where they are the switching terminal b, the termination-side transmission line 12b is input-connected to the downstream signal boost circuit unit 32 and the output of the downstream signal boost circuit unit 32 is connected to the start-side transmission line 12a.

[0043] The upstream signal input / output switching circuit units 48, 50 are configured with switching elements such as switching relay contacts or FETs. The upstream signal input / output switching circuit unit 48 is provided on the input side of the upstream signal boost circuit unit 46, with the positive side of the termination side transmission line 12b connected to the switching terminal a, the positive side of the start side transmission line 12a connected to the switching terminal b, and the common terminal c connected to the input of the upstream signal boost circuit unit 46.

[0044] The upstream signal input / output switching circuit unit 50 is provided on the output side of the upstream signal boost circuit unit 46, with the positive side of the starting transmission line 12a connected to the switching terminal a, the positive side of the terminating transmission line 12b connected to the switching terminal b, and the common terminal c connected to the output of the upstream signal boost circuit unit 46.

[0045] The upstream signal input / output switching circuits 48, 50 have a first switching position at switching terminal a and a second switching position at switching terminal b. Therefore, when the upstream signal input / output switching circuits 48, 50 are in the first switching position at switching terminal a as shown in the figure, the termination-side transmission line 12b is input-connected to the upstream signal boost circuit 46 and the output of the upstream signal boost circuit 46 is connected to the start-side transmission line 12a, and when they are in the second switching position at switching terminal b, the start-side transmission line 12a is input-connected to the upstream signal boost circuit 46 and the output of the upstream signal boost circuit 46 is connected to the termination-side transmission line 12b.

[0046] The first voltage detector 38 detects the line voltage of the start-end transmission line 12a and outputs it to the booster controller 34. The second voltage detector 40 detects the line voltage of the end-end transmission line 12b and outputs it to the booster controller 34.

[0047] The booster control unit 34 is composed of a computer circuit equipped with a CPU, memory, and various input / output ports, and performs input / output switching control by executing a program using the CPU. When a predetermined line voltage is detected by the first voltage detection unit 38 and the second voltage detection unit 40 (when the loop transmission line 12 is normal or the termination-side transmission line 12b is disconnected), the booster control unit 34 switches the downstream signal input / output switching circuit units 42, 44 and the upstream signal input / output switching circuit units 48, 50 to the first switching position on the illustrated switching terminal a side, and causes the downstream signal input from the start-side transmission line 12a to be voltage-amplified by the downstream signal boost circuit unit 32 and output toward the termination-side transmission line 12b, and also causes the upstream signal input from the termination-side transmission line 12b to be current-amplified by the upstream signal boost circuit unit 46 and output toward the start-side transmission line 12a.

[0048] Furthermore, when the first voltage detection unit 38 does not detect a predetermined line voltage due to a break in the start-end transmission line 12a, and when the second voltage detection unit 40 detects a predetermined line voltage due to the disconnection of the start-end side transmission line 12a and the disconnection monitoring control unit 28 connecting the end of the loop transmission line 12 to the transmission unit 22 through the operation of the switching circuit units 30a, 30b, the input / output switching control by the booster control unit 34 switches the downlink signal circuit units 42, 44 and the uplink signal input / output switching circuit units 48, 50 to the second switching position on the switching terminal b side, voltage-amplifies the downlink signal input from the end-end side transmission line 12b and outputs it toward the start-end side transmission line 12a, and current-amplifies the uplink signal input from the start-end side transmission line 12a and outputs it toward the end-side transmission line 12b.

[0049] [Operation when loop line is broken] (Disconnection of the transmission line at the starting end) FIG. 3 is a block diagram showing the operation of an input / output switching booster when a disconnection fault occurs in the start-end transmission line, and the booster control unit 34, transmission unit 36, first voltage detection unit 38, and second voltage detection unit 40 shown in FIG. 2 are omitted.

[0050] In a normal monitoring state where there is no break in the loop transmission line 12, as shown in FIG. 2, the downstream signal input / output switching circuit units 42, 44 and the upstream signal input / output switching circuit units 48, 50 are switched to the first switching position which is the side of the switching terminal a shown in the figure, and the downstream signal input from the start-side transmission line 12a is voltage-amplified by the downstream signal boost circuit unit 32 and output toward the termination-side transmission line 12b, and the upstream signal input from the termination-side transmission line 12b is current-amplified by the upstream signal boost circuit unit 46 and output toward the start-side transmission line 12a.

[0051] In this state, if a break 52 occurs in the start-end transmission line 12a as shown in Fig. 3, the break monitoring control unit 28 of the receiver 10 shown in Fig. 1 detects that the line voltage at the end of the loop transmission line 12 has been cut off due to the break 52, turns on the switching circuits 30a and 30b, and connects the transmission unit 22 to the end of the loop transmission line 12. As a result, the downstream signal output from the transmission unit 22 is transmitted from both the start and end of the loop transmission line 12 to the location where the break 52 has occurred in Fig. 3.

[0052] At this time, the first voltage detection unit 38 of the input / output switching booster 16 no longer detects the specified line voltage due to the break 52, and the second voltage detection unit 40 detects the specified line voltage because the end of the loop transmission line 12 is connected to the transmission unit 22. As a result, as shown in Figure 3, the booster control unit 34 switches the downstream signal input / output switching circuit units 42, 44 and the upstream signal input / output switching circuit units 48, 50 to the second switching position which is the side of switching terminal b, and the downstream signal input from the termination side transmission line 12b is voltage-amplified by the downstream signal boost circuit unit 32 and output toward the start side transmission line 12a where the break 52 has occurred, and also current-amplified the upstream signal input from the start side transmission line 12a where the break 52 has occurred by the upstream signal boost circuit unit 46 and output toward the termination side transmission line 12b.

[0053] Therefore, even if a break 52 occurs in the transmission line 12a at the start end of the loop transmission line 12, downstream and upstream signals can be sent and received between all fire detectors 18 connected to the loop transmission line 12 and the transmission section 22 of the receiver 10, and the fire monitoring function of the fire detectors 18 will not be lost.

[0054] The break 52 is a break in the signal cable used in the loop transmission line 12, and although it is shown in Figure 3 as break 52 in the positive signal line, the above effect can also be achieved in the case where breaks occur in both the positive and negative signal lines, which generally occur.

[0055] (Disconnection of the transmission line on the termination side) FIG. 4 is a block diagram showing the operation of the input / output switching booster in the normal monitoring state and when a disconnection fault occurs in the termination side transmission line, and the booster control unit 34, transmission unit 36, first voltage detection unit 38, and second voltage detection unit 40 shown in FIG. 2 are omitted.

[0056] As shown in Fig. 4, if a break 54 occurs in the termination side transmission line 12b in a normal monitoring state in which the downstream signal input / output switching circuit units 42, 44 and the upstream signal input / output switching circuit units 48, 50 are switched to the first switching position corresponding to the switching terminal a, the break monitoring control unit 28 of the receiver 10 shown in Fig. 1 detects that the line voltage at the termination of the loop transmission line 12 has been cut off due to the break 54, turns on the switching circuit units 30a, 30b, and connects the transmission unit 22 to the termination of the loop transmission line 12. As a result, the downstream signal output from the transmission unit 22 is transmitted from both the start and end of the loop transmission line 12 to the location where the break 54 occurred in Fig. 3.

[0057] At this time, the first voltage detector 38 of the input / output switching booster 16 detects a predetermined line voltage without being affected by the disconnection 54 of the termination side transmission line 12b, and the second voltage detector 40 Since the booster is outputting a signal in the downstream direction and a voltage is applied, the open end has simply changed from the switching circuit section 30a to the broken point, and a specified line voltage is detected, which is the same as a normal state where there is no break in the loop transmission line 12.As a result, the booster control section 34 maintains the first switching position, which is the side of switching terminal a of the downstream signal input / output switching circuit sections 42, 44 and the upstream signal input / output switching circuit sections 48, 50.

[0058] That is, recovery from a break 54 in the termination side transmission line 12b can be achieved simply by controlling the receiver 10 to connect the transmission unit 22 to the termination of the loop transmission line 12 by turning on the switching circuit units 30a and 30b using the break monitoring control unit 28.

[0059] [Another embodiment of the input / output switching type booster] Fig. 5 is a block diagram showing another embodiment of an input / output switching type booster. As shown in Fig. 5, the input / output switching type booster 16 of this embodiment is characterized by including a first downstream signal boost circuit 32a that voltage-amplifies a downstream signal input from a start-side transmission line 12a in one direction and outputs the amplified signal to a termination-side transmission line 12b, a second downstream signal boost circuit 32b that voltage-amplifies a downstream signal input from the termination-side transmission line 12b in the reverse direction and outputs the amplified signal to the start-side transmission line 12a, a first upstream signal boost circuit 46a that current-amplifies an upstream signal input from the termination-side transmission line 12b in one direction and outputs the amplified signal to the start-side transmission line 12a, and a second upstream signal boost circuit 46b that current-amplifies a upstream signal input from the start-side transmission line 12a in the reverse direction and outputs the amplified signal to the termination-side transmission line 12b.

[0060] Downstream signal input / output switching circuit sections 42, 44 are provided for the first downstream signal boost circuit section 32a and the second downstream signal boost circuit section 32b, and upstream signal input / output switching circuit sections 48, 50 are provided for the first upstream signal boost circuit section 46a and the second upstream signal boost circuit section 46b.

[0061] If there is no break in the loop transmission line 12 or if a break has occurred in the termination side transmission line 12b, the booster control unit 34 switches the downstream signal input / output switching circuit units 42, 44 and the upstream signal input / output switching circuit units 48, 50 to the first switching position which is the side of switching terminal a based on the detection of a predetermined line voltage by the first voltage detection unit 38 and the second voltage detection unit 40, inserts and connects the first downstream signal boost circuit unit 32a into the loop transmission line 12 to voltage-amplify the downstream signal input from the start side transmission line 12a and output it to the termination side transmission line 12b, and also inserts and connects the first upstream signal boost circuit unit 46a into the loop transmission line 12 to current-amplify the upstream signal input from the termination side transmission line 12b and output it to the start side transmission line 12a.

[0062] On the other hand, if a break occurs in the start-end transmission line 12a, the first voltage detection unit 38 no longer detects the specified line voltage, and the second voltage detection unit 40 detects the specified line voltage. Based on this, the booster control unit 34 switches the downlink signal input / output switching circuit units 42, 44 and the uplink signal input / output switching circuit units 48, 50 to the second switching position which is the side of switching terminal b, inserts and connects the second downlink signal boost circuit unit 32b to the loop transmission line 12, voltage-amplifies the downlink signal input from the termination-end transmission line 12b and outputs it to the start-end transmission line 12a, and also inserts and connects the second uplink signal boost circuit unit 46b to the loop transmission line 12, current-amplifies the uplink signal input from the start-end transmission line 12a and outputs it to the termination-end transmission line 12b.

[0063] Other configurations and functions are the same as those in the embodiment shown in FIG. 2, so the same reference numerals are used and the description thereof is omitted.

[0064] In this way, by providing the first downstream signal boost circuit 32a and the second downstream signal boost circuit 32b and the first upstream signal boost circuit 46a and the second upstream signal boost circuit 46b dedicated to the transmission direction of the loop transmission line 12, it is possible to individually set an amplification factor suited to the electrical characteristics of the output side transmission line and achieve optimal signal amplification and transmission, even if the input / output switching type booster 16 is not provided at the midpoint of the loop transmission line 12 and the electrical characteristics, including the resistance, of the start-side transmission line 12a and the end-side transmission line 12b are different. The amplification factor setting means may be a known variable resistor.

[0065] [Modifications of the present invention] The above embodiment takes an example of a wire breakage fault, but even if the system intentionally breaks the wire, such as the operation of a short circuit isolator that cuts off a shorted portion of a circuit, the booster will operate as if it is a wire breakage.

[0066] In the above embodiment, a loop wiring is drawn out from the receiver, but the sensor and booster may be connected to a loop wiring drawn out from a repeater connected to the receiver.

[0067] In the above embodiment, both the upstream and downstream signals can be amplified simultaneously, but the amplification direction of the signal can be switched in the event of a wire breakage. For example, in the case of a fire alarm system in which both voltage and current signals are downstream signals, the downstream signal is amplified under normal circumstances, and the amplification direction is changed in the event of a wire breakage.

[0068] In addition to the above embodiment, the input / output switching booster 16 may be configured to insulate the input and output. For example, the amplifier unit may be insulated from the input terminal and first voltage detection unit 38 using a photocoupler or the like, and the output terminal and second voltage detection unit 40 may be insulated from the amplifier unit using a photocoupler or the like. By isolating the input / output terminals, it is possible to prevent a collision between the signal output of the booster and the signal output of the receiver, which occurs when only the GND line is broken.

[0069] In addition to the above embodiment, the fire alarm system may have an automatic test function. For example, the output of the transmitter 22 is stopped only at the start end, and the switching circuits 30a and 30b are turned on to confirm that the signal amplification direction of the input / output switching booster 16 is reversed. Alternatively, the receiver may send a signal to the input / output switching booster 16 to switch the amplification direction.

[0070] The above embodiment takes as an example a fire alarm system in which an R-type fire detector is connected via a loop transmission line from an R-type receiver, but it can also be applied to a fire alarm system in which an addressable fire detector with a transmission function is connected and an address is set on a loop-type detector line drawn from a P-type receiver.

[0071] The present invention also includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the numerical values ​​shown in the above embodiments. [Explanation of symbols]

[0072] 10: Receiver 12: Loop transmission line 12a: Starting end transmission line 12b: Termination side transmission line 14a, 14b: Signal line 16: Input / output switching booster 18: Fire detector 20: Reception control section 22,36: Transmission section 28: Disconnection monitoring control unit 30a, 30b: switching circuit section 32: Downstream signal boost circuit section 32a: First downstream signal boost circuit section 32b: Second downstream signal boost circuit section 34: Booster control unit 38: First voltage detection unit 40: Second voltage detection unit 42, 44: Downstream signal input / output switching circuit section 46: Upstream signal boost circuit 46a: First upstream signal boost circuit section 46b: Second upstream signal boost circuit section 48, 50: Upstream signal input / output switching circuit section

Claims

[Claim 1] A booster used in a fire alarm system that connects a fire detector to a loop transmission line that is loop-connected to a receiver or a repeater connected to the receiver, The booster comprises: A unique address is set and inserted into the loop transmission line, a downstream signal input from one side to the receiver for the fire detector is amplified and output to the other side, and an upstream signal input from the other side to the receiver for the fire detector is amplified and output to the one side, A booster characterized by switching the direction of the uplink signal and the downlink signal to be amplified and output, based on an operational test using a signal sent from the receiver via the loop transmission path to instruct the booster to switch the signal amplification direction, so that the downlink signal input from the other side is amplified and output to the one side, and the uplink signal input from the one side is amplified and output to the other side.

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