JP2543106Y2 - Alarm signal input circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a signal input of an alarm device which receives signals from two sensor circuits, activates an alarm device based on the signals detected by the respective sensor circuits, and generates an abnormal alarm or the like. Circuit.

[0002]

2. Description of the Related Art Conventionally, there has been known a signal input circuit of an alarm device in which temperature is detected by two systems and an alarm device is activated upon receiving this detection signal. For example, when detecting the temperature of the engine room of a large bus, etc., detection points are provided at two places of a main engine and a sub engine, and sensors are arranged at these points, and signals from these two systems of sensors are received. The alarm is activated when an abnormality occurs.

FIG. 2 shows an example of a signal input circuit of an alarm device used in this case. That is, the signal input circuit 20 includes two input circuits 21 and 22 having the same circuit configuration. The input circuit 21 has two comparators 1 and 2 formed of ICs.
The reference voltages V ₁₁ and V ₁₃ are connected to the minus input terminals of
Are applied. These reference voltages V ₁₁ and V ₁₃ are:
Resistance R obtained by dividing the power supply voltage V by a resistor R ₁₀ and R ₁₁ each
₁₁ and the voltage of a voltage of the resistor R ₁₃ obtained by dividing the power supply voltage V by a resistor R ₁₂ and R _13.

An input terminal e of an input circuit 21 is connected to the plus input terminals of these comparators 1 and 2 via a resistor R ₁₄ , and a power supply is connected to the input terminal e via a resistor R _15. Voltage V is applied.

The input terminal f of the input circuit 21 is grounded, and a sensor circuit A in which a resistor Rs ₁ and a thermal switch S ₁ are connected in parallel between the input terminal f and the input terminal e. Are connected. The output terminals of the two comparators 1 and 2 are connected to alarm devices including an inverter circuit 23, an amplifier circuit 24, and alarm indicators 25 and 26, respectively.

A sensor circuit A is connected between input terminals e and f of the input circuit 21, and an alarm device is connected to output terminals of the comparators 1 and 2 to apply a power supply voltage V to the input circuit 21. At this time, the voltage Vi applied divided by the resistor Rs ₁ of the power supply voltage V in the resistor R ₁₅ and the sensor circuit A to the positive input terminal of the comparator 1 and 2. Reference voltage V ₁₁ of comparator 1
Is set in advance so that V ₁₁ > Vi according to the values of the resistors R ₁₀ and R _11, and the reference voltage V ₁₃
Is set in advance so that V ₁₃ <Vi according to the values of the resistors R ₁₂ and R ₁₃ . The output of the comparator 1 in this state is V
_L and low, the output of the comparator 2 is higher and V _H.

When the sensor circuit A is disconnected, the voltage Vi rises, the output of the comparator 1 changes from _VL to _VH , and the alarm indicator lamp 25 lights up via the inverter circuit 23 to give an alarm. At this time, the output state of the comparator 2 remains at V _{H and} no change appears.

[0008] On the other hand, when the heat-sensitive switch S ₁ in the sensor circuit A becomes abnormal situation that ON by heat, the output of the comparator 2 a voltage Vi descends changes from V _H to V _L, the amplification circuit 24 The warning indicator lamp 26 is lit via this to give an alarm. At this time, the output state of the comparator 1 remains at _{VL and} no change appears. That is, when the sensor circuit A is broken warning indicator 25 will alarm lights, the heat-sensitive switch S ₁ is turned ON warning indicator 26 in the sensor circuit A is adapted to alarm lights.

The signal input circuit 20 is adapted to correspond to the two sensor circuits A and B.
It is composed of two input circuits 21 and 22. Input circuit 2
2 has the same configuration as the input circuit 21 described above, has input terminals g and h for connecting a sensor circuit B formed by connecting a resistor Rs ₂ and a thermal switch S ₂ in parallel, and includes a comparator (not shown). ) Output terminals are connected to an inverter circuit 27 and an amplifier circuit 28, respectively, and these circuits 27 and 28 are connected to alarm indicators 29 and 30, respectively. The signal input circuit 20 is configured as described above, receives signals of two systems of the sensor circuits A and B disposed at two detection points, and receives a disconnection in each of the sensor circuits A and B and a thermal switch. and oN of S _1, S ₂ is adapted to alarm separately.

Further, as shown in FIG.
In some cases, the outputs of the comparators 1 and 22 are temporarily input to the inverter 23 via the OR circuit 40. This is to reduce the number of alarms by sharing an alarm due to disconnection in the sensor circuits A and B.

[0011]

However, in each case, two input circuits for performing the same operation are required, so that four expensive comparators composed of ICs are required, resulting in an increase in cost. Was.

An object of the present invention is to provide a signal input circuit of an alarm device which has a simple circuit configuration and is low in manufacturing cost.

[0013]

According to the present invention, two systems of a sensor circuit in which a resistor and a thermal switch are connected in parallel are connected,
A signal input circuit of an alarm device for activating an alarm device when the sensor circuit is disconnected or a thermal switch is turned on, wherein input terminals a, b, c, and d for connecting the sensor circuits A and B are provided. And one input terminal d is grounded,
The other two input terminals b and c are formed to be conductive with each other, are pulled up by a resistor, and are connected to the base of the transistor Q whose power is applied to the collector,
Further, the other input terminal a is pulled up by a resistor, and is connected to the other input terminals of the two comparators 1 and 2 each having one input terminal to which a different reference voltage is applied. The sensor circuit A is connected between the input terminal b or c, the sensor circuit B is connected between the input terminal b or c and the input terminal d, and the outputs of the comparators 1 and 2 and the collector output of the transistor Q are connected. It is characterized in that each of the alarms is activated.

[0014]

With the above arrangement, the sensor circuit A is connected between the input terminals a and b of the signal input circuit of the alarm device, and the sensor circuit B is connected between the input terminals c and d. Then, the reference voltage of the comparator 1 is set higher than the voltage applied to the other input terminal, and the reference voltage of the comparator 2 is set lower than the voltage applied to the other input terminal. The output terminals of the comparators 1 and 2 are connected to the alarm circuit, the collector output of the transistor Q is also input to the alarm circuit, and the sensor circuits A and B are arranged at the detection points.

In this state, when the temperature at the detection point changes and the sensor circuit A is disconnected, the input voltage of the input terminals of the comparators 1 and 2 increases. Then, the input voltage of the comparator 1 becomes higher than the reference voltage, the output changes from _VL to _VH , and the alarm is activated to give an alarm. At this time, the output state of the comparator 2 remains at V _{H and} no change appears. Also, the sensor circuit B
Is the same when the wire is disconnected.

On the other hand, when the temperature at the detection point changes and the thermal switch of the sensor circuit A is turned on, the input voltages of the input terminals of the comparators 1 and 2 decrease. Then, the input voltage of the comparator 2 becomes lower than the reference voltage, the output changes from V _H to V _L, alarm device to alert operating. At this time, the output state of the comparator 1 remains at _{VL and} no change appears.

Further, when the thermal switch of the sensor circuit B is turned on, the base voltage of the transistor Q drops, the transistor Q turns off, and the collector voltage rises. For this reason, the alarm connected to the collector is activated to give an alarm.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same parts as those described in the description of the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a signal input circuit 10 of an alarm device according to an embodiment of the present invention. As shown in the figure, the signal input circuit 10 is one of the input circuits 21 and 22 of the signal input circuit 20 described in the section of the prior art.
1 is used as it is, and a circuit configuration using a transistor Q instead of the input circuit 22 is provided.

That is, the signal input circuit 10 has four input terminals a, b, c, and d, the input terminal d is grounded, and the other two input terminals b and c are formed to be conductive. and a resistor R ₉ is connected to a power source V is pulled up. Further, the input terminals b, c is connected to the base of the transistor Q via the resistor R _7, the emitter of the transistor Q is grounded, the collector resistor R ₈
Be connected to a power supply V, the output of the collector are inputted alarm devices constituting an inverter circuit U ₃ an alarm indicator lamp 30 by.

Although the conventional input circuit 21 uses the conventional input circuit 21 as it is, the voltage applied to the plus input terminals of the comparators 1 and 2 during normal operation differs from the conventional one. Reference voltage V ₄ , V to each minus input terminal
_Since there is a difference in the value of ₅ mag, the value of each resistor is different. The operation is not different from the conventional case.

As shown in the figure, sensor circuits A and B are connected to this signal input circuit 10, and a power supply voltage V is applied. In this state, if one or one of the sensor circuits A and B is disconnected, the alarm indicator light 25 is lit to give an alarm, and one or one of the thermal switches S _{1 and} S ₂ is turned on.
Then, the warning indicator light 26 is turned on to give a warning. In this case, the heat-sensitive switch S ₂ is ON sensor circuit B Then, the collector voltage rises transistor Q is in OFF, the alarm indicator 30 via the inverter circuit U ₃ is turned. Therefore, it is possible to determine which of the thermal switches S _{1 and} S ₂ has been turned ON. In an actual circuit, a holding circuit and a flashing (flashing) circuit are inserted after the signal input circuit 10.

[0023]

[Effect of the invention] As described above, according to the invention,
As compared with the signal input circuit of the conventional alarm device, an expensive comparator composed of an IC can be saved, so that the cost of parts is reduced and the number of parts is also reduced. Therefore, the processing cost is reduced and the reliability of the product can be improved.

[Brief description of the drawings]

FIG. 1 is an embodiment of a signal input circuit of an alarm device of the present invention.

FIG. 2 is a signal input circuit of a conventional alarm device.

FIG. 3 is a signal input circuit of another conventional alarm device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Comparator 2 Comparator 10, 20 Signal input circuit of alarm device A Sensor circuit B Sensor circuit Q Transistor

Claims (1)

(57) [Scope of request for utility model registration] 1. A signal input circuit of an alarm device in which a sensor circuit in which a resistor and a thermal switch are connected in parallel is connected, and when the sensor circuit is disconnected or the thermal switch is turned on, an alarm device is activated. And input terminals a, for connecting the sensor circuits A, B,
b, c, and d, one input terminal d is grounded, and the other two input terminals b and c are formed to be conductive with each other, are pulled up by a resistor, and are supplied with power to the collector. The other input terminal a is connected to the base of the transistor Q, and the other input terminal a is connected to the other input terminal of the two comparators 1 and 2 in which different reference voltages are respectively applied to one input terminal while being pulled up by a resistor. The sensor circuit A is connected between the input terminal a and the input terminal b or c, and the sensor circuit B is connected between the input terminal b or c and the input terminal d. A signal input circuit for an alarm device, wherein the alarm device is activated by the output and the collector output of the transistor Q.