JPH0626035Y2 - Anomaly detection device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an abnormality detection device capable of immediately detecting an abnormality due to a disconnection in an electronic device or the like, which can be distinguished from a power failure. is there.

[Conventional technology]

FIG. 2 is a circuit diagram of a gas leak alarm system shown as an example of electronic equipment. I is a gas leak alarm device, II is a monitoring unit, and L ₁ and L ₂ are signal lines. In gas leak alarm system I, T denotes a power transformer, the primary winding _{W P} to the commercial power supply _{E S}
Is applied to induce a specified voltage in the secondary winding W _S. S is a gas sensor, which detects that there is a gas leak and generates an output voltage. A ₁ and A ₂ are comparators, both of which are the reference voltage.
It has E _S1 and E _S2 (E _S2 > E _S1 ) and outputs when the output of the gas sensor S exceeds these values. PC _S and PC _R are a light emitting element and a light receiving element, and a photo coupler is formed by both. R _{1 to} R ₆ are resistors, D _{1 to} D ₃ are diodes, Z
D is a Zener diode, Q _{1 to} Q ₃ are transistors, and C
_{1 to} C ₃ are capacitors, and BZ is a buzzer. LED _G
Indicates a green light emitting diode, LED _R indicates a red light emitting diode, and T ₁ and T ₂ indicate output terminals of the gas leak alarm device I.

Next, the operation will be described.

When the commercial power supply E _S is applied to the primary winding W _P of the power transformer T, a specified voltage is induced in the secondary winding W _S , which is rectified by the diode D ₂ and smoothed by the capacitor C ₃ to generate a DC voltage. It becomes DC + and is supplied to each part. Since there is no output from the gas sensor S when there is no gas leak, the output of the comparator A ₁ is “H”, so the transistor Q ₁ is non-conductive, the transistor Q ₂ is conductive, and the light-emitting diode L
ED _G to display that there is no abnormality on. Comparator A
_Since the output of ₂ is also "H", the light emitting element PC _S does not light up, and the buzzer BZ does not ring. The light receiving element PC _R is also inoperative due to the light emitting element PC _S not lit, and the voltage applied to the transistor Q ₃ is low, so that the output terminals T ₁ , T ₂
The voltage appearing between them is, for example, 6 volts.

Next, when there is a small amount of gas leak and the output voltage from the gas sensor S exceeds the reference voltage E _S1 , the output of the comparator A ₁ becomes “L”, the transistor Q ₁ turns on, and the transistor Q ₂ turns off. Then, the light emitting diode LED _G is turned off and the light emitting diode LED _R is turned on.

Further, when there is a large amount of gas leakage and the output voltage of the gas sensor S exceeds the reference voltage E _S2 , the comparator A ₂ outputs “H”, so that the light emitting element PC _S is turned on and this light is received by the light receiving element P _S.
Enter the C _R, conducts the light-receiving element PC _R, transistor Q
The base voltage of ₃ rises. Therefore, the output terminals T ₁ , T
A voltage of, for example, 12 volts appears between the _two, and informs the monitoring unit II that there is a gas leak through the signal lines L ₁ and L ₂ .
Further, the buzzer BZ sounds at the same time as the light emission of the light emitting element PC _S , indicating that gas is leaking.

Further, at the time of power failure and when the signal lines L ₁ and L ₂ are broken, neither voltage of 6V or 12V appears on the monitoring line II,
OV appears. This allows the monitoring unit II to know that a power failure or disconnection has occurred.

[Problems to be solved by the invention]

In the circuit shown in FIG. 2, when a power failure occurs, the voltage appearing between the output terminals T ₁ and T ₂ as shown in FIG. The external output voltage E ₀ ) tends to be gradually attenuated because the charge of the capacitor C ₃ is discharged by the load inside and outside the circuit. In addition, E _{W in} FIG.
Is the trouble voltage range, and t ₀ is the time when the power failure occurred.

On the other hand, in the case of the disconnection of the signal lines L ₁ and L ₂ , as shown in FIG. 4, when the disconnection occurs at time t ₀ , the external output voltage E ₀ immediately becomes OV.

As described above, there are two cases in which the power is turned off, that is, a case of power failure and a case of disconnection. However, the two cannot be distinguished as they are. Therefore, conventionally, the AC10 as shown in Table 1 below is used.
The combination of 0V monitoring and external output status distinguishes power failures and troubles. However, such AC100V
There is a problem in that pulling AC100V of another system into the device to monitor the power supply requires a lot of trouble such as wiring.
In other words, when considering a shutoff valve controller, the shutoff valve controller is currently designed to operate only at the external output power source and at a position different from that of the alarm device.
Pulling in 100V is costly because wiring work is difficult. Furthermore, this AC100V must have a structure that the user cannot freely remove.

This method is very important when the shutoff valve controller or the like connected to the external output is operated only when trouble occurs and not when there is a power failure. That is, when the shutoff valve is closed due to a power outage, it is closed at each home at the same time, so that there is a problem that maintenance shops such as gas shops are frequently dispatched.

The present invention has been made in order to solve the above problems, and an object thereof is to provide an abnormality detection device capable of distinguishing between a power failure and a disconnection with a simple circuit configuration.

[Means for solving problems]

The abnormality detecting device according to the present invention comprises a diode and a first resistor connected in series between terminals to which a voltage to be monitored is applied, and further a second and a third resistor connected in series. The first resistor is connected in parallel, the second resistor is connected to both input terminals of the comparator, the third resistor is connected to the capacitor, and the comparator outputs a disconnection output. When output, keep this disconnection output until power is restored,
A latch circuit for storing is provided.

[Action]

In this invention, the magnitude of the current gradually decreases during a power failure with respect to the direction of the current flowing through the second resistor during a normal time, but since the direction is the same, the output of the comparator is the same during the normal time and during a power failure. Will be the same. Further, when the wire is disconnected, the current flowing through the second resistor is supplied from the capacitor, which is the opposite of the case of the normal time and the time of power failure, and the output of the comparator is inverted.

〔Example〕

FIG. 1 shows an embodiment of the abnormality detecting device of the present invention. D ₁₁ and D ₁₂ are diodes, and R _{11 to} R ₁₃ are first to third.
Resistors, C ₁₁ , C ₁₂ are capacitors, COM1 to COM
3 is a comparator, ES ₁₂ and ES ₁₃ are reference voltages, T ₁₁ and T ₁₂ are input terminals, T ₁₀ is an output terminal, and LT is a latch circuit.
Note that C ₁₂ and D ₁₂ are provided as backup power supplies for the comparators COM1 to COM3. In addition, (A), (B),
(C) represents the output state.

Next, the operation will be described.

In a normal state without power failure or disconnection, a voltage of 6 V is applied between the input terminals T ₁₁ and T ₁₂ , so that currents I ₁₁ , I ₁₂ , and I ₁₃ flow through the diode D ₁₁ . At this time, a voltage of V ₁₂ = R ₁₂ · I ₁₂ is generated across the second resistor R ₁₂ ,
The capacitor C ₁₁ is R ₁₃ · I generated in the third resistor R _13.
It is charged by the current I ₁₂ by ₁₂ voltage. Voltage relationship of the input terminal of the comparator COM1 by the current I ₁₂ has a non-inverting input terminal V _NI, the inverting input terminal relationship V _{NI> V I} is established as _{V I,} the output terminal T of the order comparator COM1 _Ten
Becomes "H" and is latched by the latch circuit LT. Therefore, the output (C) becomes "H". Further, the output (B) of the comparator COM3 becomes "L", and it can be understood from the combination thereof that it is in the normal state. If gas leaks, an output voltage of 12 V appears at the output terminal T _{1 of} FIG. 2 and is applied to the input terminal T _{11 of} FIG. 1, so that the output (C) is “H”, the output ( Both A) and (B) are "L".

Next, the case of power failure will be described. In the case of a power failure, the external output voltage E ₀ drops with a gentle slope as shown in FIG. 3, so the directions of the currents I ₁₁ , I ₁₂ , and I ₁₃ are the same, and their magnitudes only gradually decrease. is there. Therefore, the output terminal T ₁₀ of the comparator COM1 remains “H” and is latched by the latch circuit LT. Therefore, the output (C) becomes "H", and the output (A),
(B) also becomes "H". You can see that there is a power outage.

Next, the case of disconnection will be described. When a disconnection occurs,
A change in the external output voltage E ₀ as shown in FIG. 4 is input. In FIG. 1, the currents I ₁₁ , I ₁₂ , and I ₁₃ cease to flow, and the charges stored in the capacitor C ₁₁ are
It flows as a current I ₁₀ through the first resistors R ₁₂ and R ₁₁ . Since the direction of this current is opposite to the current I ₁₂ flowing through the second resistor R ₁₂ at the normal time, the relationship of V _NI <V _I is established, and the output terminal T ₁₀ of the comparator COM1 becomes “L”. . The output (C) is "L" and the outputs (A) and (B) are "H".
Becomes Therefore, it can be distinguished from the power-off in the case of a power failure. Then, a power failure, the comparator COM1~COM3 by a backup power source by the diode D ₁₂ and the capacitor C ₁₂ in any case disconnection is operated. The correspondence between outputs (A), (B), and (C) and each state is shown below.
It looks like the table.

It should be noted that the above embodiment is a case where the present invention is applied to a gas leak alarm system, but it goes without saying that it can be applied to various other electronic and electric devices. Also, the comparator C
Connect a relay drive circuit to the output terminal T _{10 of} OM1,
It is also possible to display the disconnection and power failure by the relay contact.

[Effects of the Invention] As described above, the present invention connects the diode and the first resistor in series between the terminals to which the voltage to be monitored is applied, and further connects the second and third resistors in series. Connected in parallel with the first resistor, both ends of the second resistor are connected to both input terminals of the comparator, respectively, and a capacitor is connected to both ends of the third resistor, Further, when the voltage applied between the terminals becomes 0 volt and a current flows in the opposite direction from the capacitor to the first resistor, and the comparator outputs a disconnection output, this disconnection output is supplied to the power supply. Since a latch circuit that holds and stores data until recovery is provided, the direction of the current flowing through the second resistor will be opposite in the case of a power failure and in the case of a wire break, and the output of the comparator will be inverted, resulting in a power failure or wire breakage. It can be easily detected.
Moreover, there is a practical effect that the circuit configuration is extremely simple and can be easily applied to existing devices.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a gas leak alarm system which is an example of an application target of the present invention, and FIG. 3 is a change of external output voltage at the time of power failure. Similarly, FIG. 4 is a diagram showing a change in the external output voltage at the time of disconnection. In the figure, T ₁₁ and T ₁₂ are input terminals, T ₁₀ is an output terminal, and L ₁ and L ₂
Is a signal line, D ₁₁ and D ₁₂ are diodes, and R _{11 to} R ₁₃ are first
~ Third resistor, C ₁₁ and C ₁₂ are capacitors, COM 1 ~
COM3 is a comparator.

Claims (1)

[Scope of utility model registration request] 1. A diode and a first resistor are connected in series between terminals to which a voltage to be monitored is applied, and further a second and a third resistor are connected in series, and the first resistor is used. Connected in parallel with each other, both ends of the second resistor are connected to both input terminals of the comparator, respectively, and a capacitor is connected to both ends of the third resistor, and further applied between the terminals. When the comparator outputs a disconnection output due to the current flowing in the opposite direction from the capacitor to 0 V due to the disconnection, the disconnection output is maintained until the power is restored. An anomaly detection device comprising a latch circuit for holding and storing.