JPH045238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a repeater for a gas leak detection system using a voltage output type gas leak detector.

[Background technology]

Figure 1 shows the circuit of a conventional gas leak indicator repeater. In the figure, _{1 1 and 1 2 are} gas leak detectors. It is used to detect gas, and is powered by a commercial power source.
Gas leak detection with voltage output type that generates an output consisting of a 12V voltage signal, generates an output consisting of a 6V voltage signal between the above output terminals when non-gas is detected, and sets the voltage between the output terminals to OV when the power is off. Configure the vessel. 2 ₁ is a first priority discrimination circuit, and this priority discrimination circuit 2 is equipped with signal input terminals G ₁ and G ₂ to which gas leak detectors 1 ₁ and 1 ₂ are connected, respectively, and a common connection terminal G _c , and each signal input Terminals G ₁ and G ₂ are diode D ₁ ,
_A series circuit of an output transistor Tr ₀ and an output resistor R ₀ is connected between this common connection point and the common connection terminal G _c . A series circuit consisting of resistors R _{1 ,} R ₂ and a Zener diode ZD 1 is connected in parallel to the series circuit of the transistor Tr ₀ and the output resistor R ₀ , and the cathode of the Zener diode ZD ₁ is connected to the base of the transistor Tr ₁ through the resistor R The transistor Tr ₁ is connected through the transistor Tr ₂ and is turned on when the Zener diode ZD ₁ is conductive. Here, the Zener voltage of the Zener diode ZD ₁ is expressed as each of the above diodes D ₁ ,
The Zener diode ZD ₁ is set to conduct when the voltage at the common connection point of D ₂ is 12V. Now, Zener diode ZD ₁ has two transistors.
A series circuit of Tr ₁ and Tr ₂ is connected. The bases of each transistor Tr ₁ and Tr ₂ are connected to corresponding signal input terminals G ₁ and G ₂ via resistors R ₃ and R ₄ , respectively. 2 ₂ is a second priority discrimination circuit, and this second priority discrimination circuit 2 ₂ has an output transistor for the output resistance R ₀ of the first priority discrimination circuit 2 ₁ .
Connect the series circuit of Tr ₀ ′ and output resistance R ₀ ′ in parallel,
Two series transistors Tr _{1 ′} , Tr ₂ ′ are connected in parallel to the Zener diode ZD ₁ ′ of the base bias circuit consisting of the resistors R ₁ ′, R ₂ ′ of the output transistor Tr 0 ′, and the Zener diode ZD ₁ ′. The base of Tr ₁ ′ is connected to the first priority discrimination circuit 2 ₁ through a resistor R ₃ ′.
Connect _the collector of _the transistor Tr ₀ for the output _of
It is connected to the emitter of the output transistor Tr ₀ ' via . Further, an expansion terminal _GI is provided at the anode of the diode D ₃ , and output terminals G ₀₁ and G ₀₂ for connecting the line 1 are provided at both ends of the output resistor R ₀ '. 3 is a trouble detection circuit, which uses a comparator CP1 to detect that the voltage across the output resistor _R0 of the first priority determination circuit ₂₁ has become 0V, turns on the transistor Tra, and issues an issue. It lights up a diode LED. Reference numeral 4 denotes a gas leak detection display circuit, which detects with a comparator CP2 that the voltage across the output resistor _R0 has reached 12V, turns on the transistor Trb, and lights the lamp L. In the diagram
_D4 is a loop prevention diode.

Now, gas leak indicator repeater A configured in this way
is used by connecting multiple units as shown in Fig. 2. In this case, as shown in Fig. 3, the output terminals G ₀₁ and G ₀₂ of the first stage gas leak indicator repeater A ₁ are connected.
are connected to the signal input terminals GI ₁ and GI ₂ of receiver B. And each gas leak indicator repeater A ₁ ~ An
Commonly connect the power terminal G _V of the receiver B and connect it to the power terminal G _V0 of the receiver B, and then connect each gas leak indicator repeater A ₁ to
Commonly connect the output terminal G ₀₂ on the ground side of An, and then connect the expansion connection terminal G _I of the previous stage to the other output terminal G ₀₁ in sequence, and connect the expansion connection terminal G _I to the own short-circuit terminal G in the final stage. Connect to _X to short diode D ₃ .

Now, if all gas leak detectors 1 ₁ and 1 ₂ are in normal condition, each gas leak indicator relay
In the first priority determination circuit ₂₁ of A ₁ to An, transistors Tr ₁ and Tr ₂ are turned on, and the output transistor Tr ₀ is turned on.
with a base current of 6V across the output resistor _R0 .
generates a voltage signal. In addition, in the final stage gas leakage display relay An, since the diode _D3 is short-circuited, _the transistors _Tr'1 ,
Tr' ₂ is turned on by a voltage of 6V across the output resistor R ₀ , turning on the output transistor Tr ₀ '. Therefore, a voltage of 6V is generated across the output resistor R ₀ '. This 6V voltage signal is sent to the preceding gas leak indicator relay An-1 via the output terminals G ₀₁ and G ₀₂ and line _{1, so the 6V voltage signal is sent to the preceding gas leak indicator relay An-1} .
- In the second priority discrimination circuit 2 ₂ of ₁ , the transistor Tr ₂ ' is turned on by this sent 6V voltage signal,
The base current flows through the transistors Tr ₁ ′ and Tr ₂ ′, which are turned on by the voltage across their own output resistance R ₀ , to turn on the output transistor Tr ₀ ′, and the output resistance
This generates a voltage of 6V across R ₀ '. In this way, voltage signals are sequentially sent to receiver B via each repeater An to _A1 , and receiver B
Then, if the voltage is 6V, it is determined that it is in the normal state.

In addition, if either gas leak detector 2 ₁ or 2 ₂ detects a gas leak, the output voltage will be 12V, so the first priority determination of the gas leak relay A to which the gas leak detector is connected is performed. In circuit 21, the Zener diode ZD ₁ conducts and the output transistor
The base current of Tr ₀ is passed through the Zener diode ZD ₁ to turn on the output transistor Tr ₀ ,
A voltage of 12V is generated across the output resistor _R0 .

Therefore, this voltage of 12V is detected by the gas leak detection circuit 4, and the lamp L is turned on to indicate the occurrence of a gas leak. At the same time, this 12V voltage makes the Zener diode _ZD1 ' of the second priority discrimination circuit ₂₂ conductive and turns on the output transistor _Tr0 ', regardless of the state of the subsequent gas leakage indicator repeater. ,
This turning on generates a voltage of 12V across the output resistor R ₀ '. This 12V voltage is applied to both ends of the output resistor R ₀ ′ via the diode D ₃ of the second priority discrimination circuit 2 ₂ in the previous stage and the output transistor Tr ₀ ′ through the line 1, and then to the next previous stage. It is sent. In this way, the 12V voltage signal is sequentially sent to the previous stage and received by receiver B.

Also, if the power to either gas leak detector 1 ₁ or 1 ₂ is turned off during normal operation, the corresponding first
Since either transistor Tr ₁ or Tr ₂ of the priority determination circuit 2 ₁ is turned off, the output transistor
The base current of Tr ₀ does not flow, so no voltage is generated across the output resistor R ₀ . This voltage of 0V is detected by the trouble detection circuit 3 and the issuing diode
The LED lights up. On the other hand, in the second priority determination circuit 2 ₂ , the transistor Tr ₁ ' is turned off, so even if the input voltage from the gas leak indicator relay A in the subsequent stage is
Even if the voltage is 6V and the transistor Tr ₂ ′ is turned on, no base current flows through the output transistor Tr 0 ′ and the output transistor Tr ₀ ′ is turned off. Therefore, the voltage across the output resistor R ₀ ' becomes 0V. As a result, the transistor of the second priority discrimination circuit ₂ of the gas leakage display repeater A in the previous stage
Tr ₂ ′ is turned off, the output transistor Tr ₀ ′ is turned off, and the voltage across the output resistor R ₀ ′ is set to 0V. In this way, a voltage signal of 0V is sent to receiver B.

In this way, the gas leak indicator repeater A of the circuit in Figure 1
gives top priority to the voltage signal 12V for gas leak detection,
Next, the voltage signal 0V when the power is turned off can be sent to receiver B with priority.

However, when a large number of gas leak indicator repeaters A ₁ to An are used as shown in Fig. 2, the voltage drop (approximately 0.6 V) of the diode D ₃ in the second priority discrimination circuit ₂ 2
can no longer be ignored, and even if a 12V gas leak detection voltage signal is generated when multiple repeaters are connected, the voltage input to receiver B will be reduced to the normal signal voltage of 6V due to the voltage drop mentioned above. As the situation approaches, receiver B has the disadvantage that it cannot distinguish between normal conditions and gas leak detection.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks.
The purpose is to provide a repeater for a gas leak detection system that can send a signal of the correct voltage to a receiver even if a large number of repeaters are connected, and that allows the receiver to correctly discriminate signals. It is in.

[Disclosure of the invention]

FIG. 4 shows an embodiment circuit of repeater A of the present invention. 2 is a priority discrimination circuit, and this priority discrimination circuit 2 has three pairs of signal input terminals G ₁₀ , G ₁₁ , G ₂₀ , G ₂₁ , G ₃₀ ,
G ₃₁ , diode bridges DB ₁ , DB ₂ , and DB ₃ are connected between each pair of signal input terminals, and the output terminals of each diode bridge DB ₁ , DB ₂ , and DB ₃ are commonly connected. It is connected to the common connection terminal _Gc , which also serves as the ground side output terminal. In addition, each output terminal is connected to a corresponding transistor Tr ₁ to
It is connected to the base of Tr ₃ via resistors R ₅ , R ₆ , and R ₇ . Each signal input terminal G ₁₀ , G ₁₁ ~ _{G 30} , G ₃₁ is commonly connected via a diode D ₅ ~ D ₁₀ , respectively, and between this common connection point and common connection terminal G _c A series circuit consisting of a transistor Tr ₀ , an output resistor R ₀ , and a diode D ₁₁ is connected. This series circuit includes resistors R ₁ , R ₂ and a Zener diode.
Connect the series circuit with ZD ₁ and Zener diode
The cathode of ZD ₁ is connected to the base of an output transistor Tr ₀ via a resistor R ₂ . In addition, the Zener diode ZD ₁ is connected to the transistor Tr ₁ ~
A Tr ₃ series circuit is connected.

Therefore, the priority determination circuit 2 has each signal input terminal G ₁₀ ,
Gas leak detector 1 connected to G ₁₁ ~ G ₃₀ , G _{31 1} ~
Under normal conditions, when the AC output voltage of Tr 1 to _{Tr 3} is, for example, 6V, all transistors Tr ₁ to Tr ₃ are turned on, and the base current of the output transistor Tr ₀ flows to turn it on, and the output resistor R ₀ and the diode are turned on. Generate a voltage of 6V across _D11 . Also, any of the gas leak detectors 1 ₁ to 1 ₃ are powered off and the voltage is 0V.
When generating an output voltage of transistor Tr ₁
~The corresponding one in Tr ₃ is turned off, cutting off the base current of the output transistor Tr ₀ , turning off the transistor Tr ₀ , and turning off the output resistor R ₀ and diode D ₁₁
Let the voltage across both ends be 0V. Furthermore, when any of the gas leak detectors ₁₁ to ₁₃ detects a gas leak and generates a voltage of 12V, a Zener diode is set to conduct when this 12V voltage is applied.
_ZD1 becomes conductive, causing the base current of the output transistor Tr0 to flow, turning on _the output transistor _Tr0 , regardless of the states of the transistors _Tr1 to _Tr3 . Therefore the output resistance R ₀ and the diode D ₁₁
This generates a voltage of 12V across the terminal. In this way, the priority determining circuit 2 operates in the same manner as the first priority determining circuit 2 of the circuit shown in FIG.

3 in the figure is a trouble detection circuit, and this trouble detection circuit 3 resists the voltage of the first constant voltage circuit 5.
When the reference voltage divided by R ₈ , Zener diode ZD ₂ , and resistor R ₉ and the voltage across the series circuit of the output resistor R ₀ and diode D ₁₁ become 0V, the output is generated from the comparator CP1 etc. When the output of comparator CP1 becomes “H”, that is, when 0V is detected, the light emitting diode
The LED lights up to indicate when a problem has occurred. 4 is a gas leak detection circuit, and this gas leak detection circuit 4 is composed of a comparator CP2 and the like that generates a detection output when the voltage across a series circuit of an output resistor R ₀ and a diode D ₁₁ reaches 12V.
The reference voltage of the comparator CP2 is set by the series circuit of the Zener diode _ZD2 and the resistor _R9 . The constant voltage circuit 5 is for obtaining a constant voltage output of 12V, and is designed to generate a voltage having the same value as the signal voltage when gas leakage is detected. ZD ₃ is a Zener diode for setting the reference voltage, and Tr ₁₁ is a control transistor.

Now, the output voltage of this constant voltage circuit 5 is further increased by a second constant voltage circuit 6 consisting of a Zener diode _ZD4 .
The voltage is stepped down to the same voltage as the normal signal voltage of 6V, and the 12V output is sent to the correction circuit 7, which will be described later.
is connected to the output terminal _G0 via the transistor _Tr4 . The correction circuit 7 includes a transistor Tr ₅ that is turned on by a current that flows when the Zener diode ZD ₅ becomes conductive when the voltage applied to the output of the comparator CP2 or the additional connection terminal _GI reaches a value close to about 12V, and the transistor Tr ₄ When transistor Tr ₅ is on, it turns on transistor Tr ₄ , and when transistor Tr 5 is off, it turns on transistor Tr ₄ .
Tr ₄ is turned off to apply or cut off the voltage of 12V to the output terminal _GI via the transistor Tr ₄ . D ₁₃ and D ₁₄ are diodes for preventing wraparound. Now, 8 in the figure is a discrimination circuit,
This discrimination _circuit 8 turns on the transistor Tr 6 when the voltage applied to the extension connection terminal G _I is 6 V or more, turns on another transistor Tr ₇ via this transistor Tr ₆ , and connects this transistor Tr ₇ and the diode D. controls the application of a voltage of 6V from the second constant voltage circuit 6 to the output terminal Go through ₁₂ ;
Further, a transistor Tr ₈ is provided which is turned on by the output of the comparator CP1, and the emitter of the transistor Tr ₇ is grounded by this transistor Tr ₈ .
By preventing the voltage of 6V from being applied to the output terminal Go, the output terminal G _p can be set to 0V. In the figure, R ₀ ' is an output resistance connected between the output terminal G _p and the common connection terminal G _c .
In the figure, reference numeral 9 denotes a gas leak indicator circuit. In this gas leak indicator circuit 9, when there is an output from the comparator CP2, a transistor Tr ₉ is turned on, and this turns on a transistor Tr ₁₀ , which turns on the lamps L ₁ and L _2. It lights up. In this case, after the transistor Tr ₉ is turned on, a power supply voltage of 24V, which has increased from 12V, is applied from the receiver B side to the power supply terminal G _V , and the Zener diode ZD ₆ connected in series to the collector of the transistor Tr ₉ becomes conductive. , transistor Tr ₁₀ is turned on. In the figure _, G _X is a shorting terminal, and this shorting terminal _G

Therefore, when a system is configured by connecting the repeaters of the present invention as shown in FIG.
If the input is 6V, the 6V output of the constant voltage circuit 6 is sent to the previous stage repeater through the discrimination circuit 8, and if the input is 12V, the 12V output of the constant voltage circuit 5 is sent to the relay.
The output is sent to the previous-stage repeater from the output terminal G _p via the correction circuit 7, and is sequentially transmitted to the receiver B. Further, when the input is 0V, the transistors Tr ₆ and Tr ₇ of the discrimination circuit 8 are turned off, and the 6V output of the constant voltage circuit 6 is cut off, making the output 0V. Of course, if any of the gas leak detectors 1 ₁ to 1 ₃ connected to the relay device detects a gas leak,
The signal voltage of 12V is discriminated and outputted by the priority discrimination circuit 2, and a voltage of 12V is generated at the output terminal _Gp by the functions of the gas leak detection circuit 4, the correction circuit 7, and the constant voltage circuit 5. In addition, if the power of any of the gas leak detectors ₁₁ to ₁₃ is turned off, the priority discrimination circuit 2 discriminates, and the trouble detection circuit 3 and discrimination circuit 7 function to determine whether the output terminal _Gp is The 6V voltage applied from the voltage circuit 6 is cut off to 0V and transmitted to the previous stage repeater.

Further, when all the gas leak detectors 1 ₁ to 1 ₃ are in the normal state, the transistors Tr ₆ of the discrimination circuit 8,
Tr ₇ is turned on by the 6V voltage from the relay after disconnection, and the output voltage of 6V from the constant voltage circuit 6 is transferred to the output terminal G _p
It is applied to Of course, the 6V of the final stage repeater
The voltage input is the output resistance of priority discrimination 2 of the relay
It is obtained from the voltage across R ₀ and the diode D ₁₁ , and the 6V voltage signal can be transmitted from the final stage to the previous stages in sequence as described above.

〔Effect of the invention〕

The present invention includes the first and second constant voltage circuits, the discrimination circuit, the correction circuit, the trouble detection circuit, the gas leak detection circuit, and the priority discrimination circuit configured as described above. If the output voltage signal of the device or the input signal voltage from the subsequent repeater is at the third voltage level at the time of gas flow detection, it can be output with the highest priority, and the output voltage signal is
If it is 0V, the output can be set to 0V, so the receiver can discriminate when trouble occurs due to power off.Moreover, the output signal voltage is output from the built-in constant voltage circuit, so it is possible to set the output to 0V. This eliminates the possibility that signal voltage discrimination cannot be performed correctly at the receiver due to the voltage drop of the bypass prevention diode, and therefore there is no limit to the number of repeaters connected, resulting in the effect that the system can be expanded freely.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional example, Fig. 2 is a schematic configuration diagram of a system using the same repeater as above, Fig. 3 is a connection example diagram of the same as above, and Fig. 4 is a circuit diagram of an embodiment of the present invention. Yes, Tr ₀ is an output transistor, D ₄ to _{D 10} are diodes, G ₁₀ , G ₁₁ to G ₃₀ , G ₃₁ are signal input terminals, ZD ₁ is a Zener diode, _GI is an expansion connection terminal, G _p is Output terminal, G _c is common connection terminal, Tr ₁ ,
Tr ₂ and Tr ₃ are transistors, 1 ₁ to 1 ₃ are gas leak detectors, 2 is a priority discrimination circuit, 3 is a trouble detection circuit, 4 is a gas leak detection circuit, 5 is a first constant voltage circuit, and 6 is a first constant voltage circuit. 2 is a constant voltage circuit, 7 is a correction circuit, and 8 is a discrimination circuit.

Claims (1)

[Claims] 1 Detects gas such as city gas and generates an output at a first voltage level between a pair of output terminals, and when non-detection generates an output at a second voltage level lower than the first voltage level between the output terminals It is equipped with a plurality of pairs of signal input terminals to which a gas leak detector is connected, and the output voltage between the output terminals is OV when the power is turned off.One of the signal input terminals is commonly connected through a diode, and the other is connected to the gas leak detector. Direct common connection, connect a series circuit of an output transistor and an output resistor between both common connection points, and make sure that the voltage of either signal input terminal is at the third voltage level or that the voltage of all signal input terminals is at the third voltage level. A priority discrimination circuit includes a voltage detection means that turns on an output transistor when the voltage is at a second voltage level, and a gas leak detection circuit that generates an output when the voltage across the output resistor is at a third voltage level. A circuit, a trouble detection circuit that generates an output when the voltage across the output resistor is OV, a first constant voltage circuit that generates a constant voltage at a third voltage level, and the output of a subsequent repeater are connected. a correction circuit that turns on when the voltage of the expansion connection terminal is at a third voltage level or when the detection output of the gas leakage detection circuit is input to generate the output voltage of the first constant voltage circuit to the output terminal; a constant voltage generating circuit that generates a constant voltage at a voltage level of , and a switch that is turned on when the voltage at the expansion connection terminal is at a second voltage level to generate the output voltage of the second constant voltage circuit at the output terminal. 1. A repeater for a gas leak detection system, characterized in that the repeater comprises a discriminating circuit which is turned on in response to a detection output of the trouble detection circuit, and has a discriminating circuit comprising the switch means and another switch means which turns off the switch means.