JPS6036029B2 - condition detection device - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a state detection device for detecting the state of an electrical device. The present invention makes it possible to detect disconnection and short-circuit accidents in electrical devices, facilitates failure detection in electrical devices, and improves reliability of control devices. FIG. 1 is a diagram showing the input/output characteristics of the potential detection circuits 81 and 82 used in the present invention, where 11 is the characteristic curve of the potential detection circuit 81, 12 is the characteristic curve of the potential detection circuit 82, and V is the potential detection circuit. 82, V2 represents the potential detection level of the potential detection circuit 81, and V3 represents the power supply potential. FIG. 2 shows an embodiment of the invention. In FIG. 2, 20 is an input terminal for a drive signal, 21 is a resistor, 22 is a drive transistor serving as a switch means, and 23
is a power supply terminal, 24 is a resistor, 25 is a failure signal generation circuit, 2
6, 27 are NOT circuits, 28, 29 are AND circuits, 30
, 31 are output terminals, and 32 is an electrical device. The operation of the apparatus shown in FIG. 2 will be explained below. In FIG. 2, a drive signal for driving an electrical device 32 is applied to input terminal 20. In FIG. When the drive signal is "L", the drive transistor 22 becomes conductive and the electric device 32 is driven. At this time, the potential at the connection point 33 between the drive transistor 22 and the electric device 32 becomes approximately the power supply potential. If the drive signal is "H", the drive transistor 22 becomes non-conductive and the electric device 32 is not driven. At this time, the potential of the connection point 33 becomes approximately the ground potential. Input terminal 5 of state detection circuit 3 is connected to connection point 33 through resistor 24 . Resistor 7 and resistor 24 are selected to have approximately the same value, and the resistance values of these resistors 7 and 24 are extremely large compared to the resistance value of electrical device 32, and the resistance value of electrical device 32 is equal to the resistance of resistors 7 and 24. It can be ignored compared to the value. First, in the case where the electrical device 32 is not malfunctioning and the electrical device 32 is not driven, the connection point 3
3 is at the ground potential, so a potential approximately half of the power supply potential is applied to the input terminal 5. Since this is the state in region [D] of the characteristic diagram in FIG. 1, the output terminal 61 of the potential detection circuit 81 becomes "H" and the output terminal 62 of the potential detection circuit 82 becomes "L". In this state, if the electrical device 32 is disconnected, the path of the current flowing through the resistors 7, 24 and the electrical device 32 is immediately cut off, so that the power supply potential is applied to the input terminal 5. This is the first
Since it is the area [m] of the characteristic diagram, the potential detection circuit 81,
The output terminals 61 and 62 of 82 become "L". If the electrical device 32 is disconnected in this way, the signal at the output terminal 61 becomes "H".
becomes “L”. Next, when the electrical device 32 is being driven and the electrical device 32 is not malfunctioning, the potential of the connection point 33 is approximately the power supply potential, so the input terminal 5
A power supply potential is applied to. Since this state is in region [m] of the characteristic diagram in FIG. 1, the signals at the output terminals 61 and 62 of the potential detection circuits 81 and 82 become "L". If the electrical device 32 is short-circuited, the voltage drop between the emitter and collector of the drive transistor 22 will increase, and the connection point 33 will be at ground potential. Therefore, a potential equal to the power supply potential divided by about half is applied to the input terminal 5 by the resistor 7 and the resistor 24. This is the area of the characteristic diagram in Figure 1.

Since the state is [0], the potential detection circuit 81
The signal at the output terminal 61 of
The signal at the output terminal 62 of No. 2 becomes "L". In this way, the state in which the signal at the output terminal 61 changes from "L" to "H" can be detected as a short-circuit failure in the electrical device 32. The output terminal 61 of the potential detection circuit 81 is connected to the failure signal generation circuit 25. The failure signal generation circuit 25 separates the signal from the potential detection circuit 81 and generates a disconnection signal and a short circuit signal depending on whether or not the electric device 32 is being driven. That is, A.N.
The drive signal of the D circuit 28 is “H”, and the electric device 32
is not driven, when the electric device 32 is disconnected and the signal at the output terminal 61 of the potential detection circuit 81 becomes "L", the signal at the output terminal 30 becomes "H", indicating a disconnection fault. Generates a disconnection signal. Furthermore, when the drive signal is "L" and the electrical device 32 is being driven, the AND circuit 29 detects when the electrical device 32 is short-circuited and the signal at the output terminal 61 of the potential detection circuit 81 becomes "H". , the signal at the output terminal 31 becomes "H", generating a short circuit signal indicating a short circuit fault. In this way, the fault signal generation circuit 25 separates the signal from the state detection circuit 3, and
Generates open circuit and short circuit signals. The above-described potential detection circuits having two different potential detection levels can be configured by Schmitt circuits each having different potential detection levels, comparators each having a reference voltage set to a different value, or the like. Furthermore, as shown in Figures 3 and 4, MOS FE
T(Mene1 Oxide Semiconductor rF
The circuit can be simplified by using the threshold voltage of the ET. Potential detection circuits using these MOSFETs are suitable for circuit integration.
In Fig. 3, 32 and 34 are P-channel MOSFEs.
T33 and 35 indicate N-channel MOS FETs. The mutual conductance of each MOSFET 32, 33, 34, 35 is ta m32, ta m33, ta m34, ta m
35, there is the following relationship between each. Tam32
>> Tam33 Tam34 <<Ta m35 Here, the N-channel MOSFET 33 works as a load resistance for the P-channel MOSFET 32, and is replaced with a resistor. Also, the P-channel MOSFET 34 is the N-channel MOSFET 34.
It functions as a load resistance for the OSFET 35 and can be replaced with a resistor. Detection level V, . V
2 are N-channel MOSFET 35 and P
It is determined by the threshold voltage of the channel MOSFET. Therefore, the detection level V,,V2 is
It can be freely selected by changing the threshold voltages of SFETs 32 and 35. In FIG. 4, 36 is a P-channel MOSFET, and 37 and 38 are N-channel MOSFETs.
36, ta m37, and ta m38, the following relationship exists. The N-channel MOSFET 37 serves as a load resistor and can be replaced with a resistor that satisfies the above formula. In FIG. 4, the detection levels V, , V2 of the characteristic diagram in FIG.
are determined by the threshold voltages of N-channel MOSFET 38 and P-channel MOSFET 36, respectively. As described above, the status of an electrical device can be detected, but if this invention is used in a control system that controls a plurality of electrical devices using a plurality of switches, it is possible to easily indicate the failure of the electrical device. Furthermore, by flipping a switch, you can easily discover which electrical device is malfunctioning. FIG. 5 is a diagram illustrating a configuration in which a failure of an electrical device can be easily discovered by switching a switch in a control device capable of indicating a failure of an electrical device. In FIG. 5, la to ln are switches, 3a to 3n and 3a' to 3n' are state detection circuits that are exactly the same as the state detection circuit 3 in FIG. 2, and 9a to gn, 21a to 21n, and 24a to 24M are resistors. 23 is a power terminal, 25a to 25
2, 30a to 30n and 31a to 31n are terminals that generate the same output signals as the output terminals 30 and 31 in FIG. 2, respectively; 36, 37; 38 is an OR circuit, 38 is a disconnection indicator lamp, 39 is a short circuit indicator lamp, and 4 river drive signal generation circuits. The device shown in FIG. 5 will be briefly explained. The state detection circuits 3a to 3n detect the states of the switches la to ln. The drive signal generation circuit 40 includes the state detection circuits 3a to 3n.
According to the states of switches la to ln detected by
Electrical devices 32a corresponding to switches la to ln, respectively
~32n to generate a drive signal to each electrical device 32a.
~32n is driven. The state detection circuits 3a' to 3n' are
A failure in each of the electrical devices 32a to 32n is detected in the same manner as in the case of FIG. Furthermore, each failure signal generation circuit 25a to 2
5n identifies the signals of each state detection circuit 31a to 31n,
Generates open circuit and short circuit signals. Each output terminal 30a
30n is connected to the input terminal of the OR circuit 36, and when one or more electrical devices are disconnected, the disconnection indicator lamp 38 is lit. Further, each of the output terminals 31a to 31n is connected to an input terminal of an OR circuit 37, and when one or more electrical devices are short-circuited, a short-circuit indicator lamp is lit. The disconnection signal is generated only when the electrical devices 32a to 32n are not driven, that is, when the corresponding switches la to ln are open.
If the disconnection indicator lamp 38 lights up, switch la~
If ln is sequentially opened and opened, if the disconnection indicator lamp 38 blinks in response to the closing and opening operations of the switch, it is determined that the electrical device corresponding to this switch is disconnected. Further, the short circuit signal is generated only when each of the electrical devices 32a to 32n is driven, that is, when the corresponding switch la to ln is closed, so if the short circuit indicator lamp 39 is lit, the switch la to ln If the switches are sequentially opened and closed, if the short-circuit indicator lamp blinks in response to the opening and closing operations of the switch, it is possible to determine whether the electrical device corresponding to the switch is short-circuited. In this way, all the failure signal generation circuits 25a to 25a~
There is no need to display the output signals of 25n individually, and a small number of indicator lights can be used to indicate a fault, and the switch can be opened,
Faults in electrical equipment can be easily detected by switching the closing state. Even when a disconnection fault and a short circuit fault are indicated by a single indicator lamp, the faulty electrical device can be identified in the same way by repeatedly opening and closing the switch. By doing the above, it is possible to realize an extremely simple failure display device. As described above, according to the present invention, it is possible to detect a disconnection or short circuit failure in an electrical device using a potential detection circuit having a potential detection level, a plurality of resistors, and a failure signal generation circuit. Therefore, failures in the electrical device can be easily discovered, and this can greatly contribute to improving the reliability of the control device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the characteristics of the potential detection circuit of this invention device;
FIG. 2 is an electric circuit diagram showing one embodiment of the device of the invention, FIGS. 3 and 4 are diagrams showing other examples of the state detection circuit of the device of the invention, and FIG. 5 is an electric circuit diagram of another example of the device of the invention. FIG. 2 is an electrical circuit diagram showing an example. In the figure, 3 is a state detection circuit, 4 is a power source, 81 and 82 are potential detection circuits, 32 is an electrical device, and 25 is a failure signal generation circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. An electrical device, a switch means for driving the electrical device, a group of resistors connected to a connection point between the electrical device and the switch means and set so that the divided voltage changes depending on the state of the electrical device, and a detection device. The detection level of this potential detection circuit is set so that when compared with the potential of the connection point mentioned above, the magnitude relationship is reversed between when the electrical device is normal and when it is abnormal due to disconnection or short circuit. A state detection circuit detects the voltage divided by the resistor group by the potential detection circuit to detect the state of the electrical device, and an output signal of the state detection circuit is separated to generate a disconnection signal and a short circuit signal. A state detection device comprising: a fault signal generation circuit that generates a signal, compares it with a drive signal for driving the electrical device, and generates a disconnection or short circuit fault signal for the electrical device.