JPS6022401Y2 - Electronic controller input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an input device for an electronic controller for inputting a signal to be controlled into the electronic controller.

Optical coupling devices have a light-emitting element on the input side and a light-receiving element on the output side housed in the same package, and since signals are transmitted optically, there is no disturbance in the electrical circuits on the input/output side, and the plant being controlled is It is used as an input device for an electronic controller as a control signal together with a limit switch attached to a motor.

FIG. 1 is a principle diagram showing an input device for an electronic controller using a conventional optical coupling device.

A contact point 1 of a limit switch provided on the controlled object is connected in series to a DC power source 2, an optical coupling element 3, and a resistor 4 that limits the current flowing through the optical coupling element.

The output side of this optocoupler 3 is connected to the base of a transistor 7, whose collector 8 is used as an output terminal.

Resistors 5 and 6 are resistance elements that constitute the transistor circuit 12.

With such a circuit configuration, when the contact 1 of the limit switch attached to the plant to be controlled is in a closed state, the output side of the optical coupling element 3 is in a conductive state.

Therefore, the base voltage of the transistor 7 decreases due to the voltage drop caused by the resistor 5, so the base voltage of the transistor 7 decreases, the transistor 7 becomes cut-off, and the voltage at the output terminal 8 increases and cannot be converted into a control voltage. , a control signal is sent to a predetermined circuit.

Conversely, if the contact 1 of the limit switch is in an open state as a control signal, the output side of the optocoupler 3 becomes a cut-off state, the transistor 7 becomes conductive, the voltage at the output terminal 8 decreases, and a control signal is generated. The signal is not sent to the specified circuit.

In this way, the input/output circuit of the electronic controller is electrically isolated by contact 1 of the limit switch that is the controlled object, and the control signal is extracted.If redundancy is required, the input side of the optical coupling element is By connecting optical coupling elements with the same characteristics in parallel,
In order to extract the output, the above-mentioned transistor circuits were arranged in parallel to form a redundant circuit.

However, in this redundant circuit, the current flowing through contact 1 of the limit switch increases, so in order to reduce this current, the voltage of the DC power supply must be increased and the capacity of resistor 4 must be increased. Furthermore, this causes a decrease in the reliability of the electronic controller.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned defects and provide an input device for an electronic controller that does not reduce redundancy and reliability of the electronic controller even if the optical coupling element fails in an open state.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 showing an embodiment of the present invention shows a contact 1 of a limit switch attached to a controlled object, a current limiting resistor 4, a first optical coupling element 3as, and a second optical coupling element 3b, which are connected in series. Power is supplied from power supply 2.

A first diode 9a having the polarity shown is connected in parallel to the input side of the first optical coupling element 3a, and a transistor ? a, resistance 5a
, 6a, and a first output terminal 8a, a first transistor circuit 12a is provided.

Similarly, a second diode 9b with polarity as shown is connected in parallel to the input side of the second optical coupling element 3b, and a transistor 7b and a resistor 5 are connected to the output side of the second optical coupling element 9b.
A second transistor circuit 12b is provided which includes a second output terminal 8b and a second output terminal 8b.

The exclusive OR circuit 10 has the first and second output terminals connected to the input side, and has the third output terminal 11 on the output side.

Next, the operation of the present invention will be explained below.

When the contact 1 of the limit switch to be controlled is in the open state, the outputs of the optical coupling elements 3a and 3b are in a non-conducting state as described above, so the transistors 7a and 7b are in a conducting state, and each output terminal 8a, 8b has an output voltage of zero.

Next, when the contact 1 of the limit switch is set to the closed state, a DC current is supplied to the input sides of the first and second optical coupling elements 3ay3b, and the eleventh and second optical coupling elements 3a and 3
The output side of b becomes conductive, and the first and second transistors ? a, 7b become non-conductive, and the first output terminal 8a
, an output voltage is generated at the second output terminal 8b, and a control signal is obtained.

In this way, when contact 1 of the limit switch is in a closed state and sends a normal signal to the output side, even if the input side of the optical coupling element 3a is in an open state and fails, the diode 9a remains connected. Therefore, a current flows through the optical coupling element 3b.

In other words, two sets of optical coupling elements will not fail due to an open circuit failure in one set of optical coupling elements.

Similarly, in the case of an open circuit failure of the optical coupling element 3b, the current flowing through the optical coupling element 3a flows to the diode 9b.

The exclusive OR circuit 10 detects when the output signals of the first and second transistor circuits 12a and 12b do not match, that is, when one set of optical coupling element circuits has failed, and outputs the third output. This is to display an alarm as a failure signal from the terminal.

It is preferable that two or more of the diodes 9a and 9b be connected in series so that the voltage drop is higher than the input side voltage drop of the optical coupling element 3at3b in order to cause current to flow through the optical coupling element 3at3b.

Further, this diode may be any other element, such as a Zener diode, as long as it is an element that allows current to flow rapidly at a voltage higher than the input voltage drop of the optical coupling elements 3a and 3b.

In the above embodiment, two sets of optical coupling element circuits have been described in detail, but if three sets are arranged in parallel in series and a majority logic (2 out of 3) is adopted using a large number of output signals, it will be very difficult. A highly reliable input device can be obtained, and even if four or more sets of optical coupling elements are used, similar effects can be obtained.

Furthermore, although the explanation has been made in the case where an optical coupling element is used in all cases, the same effect can be obtained with an element such as a relay whose input and output are electrically insulated.

As described above, the present invention connects a plurality of optical coupling elements in series, and each optical coupling element is provided with a nonlinear element in parallel. This has the advantage of being able to maintain a constant current flowing through the contacts of the switch, providing a highly reliable input device for an electronic controller with good redundancy.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of a conventional input device for an electronic controller, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 1... Limit switch contact, 2...
・DC power supply, 3...Optical coupling element, 4,5.6・
...Resistor, 7...Transistor, 8...
...output terminal, 3a...first optical coupling element, 3b...second optical coupling element, 5a, 5b...
...Resistance, 6a, 6b...Resistance, 7a...
...First transistor, 7b...Second transistor, 8a...First output terminal, 8b
...Second output terminal, 9a...First diode, 9b...Second diode, 12
a...First transistor circuit, 12b...
...Second transistor circuit.

Claims (1)

[Scope of utility model registration request] A plurality of series-connected optical coupling elements to which a current is supplied in response to a control signal, and a voltage that is connected in parallel to the input side of each of the optical coupling elements and that is higher than the input side operating voltage of the optical coupling element. 1. An input device for an electronic controller comprising a nonlinear element having a characteristic, and an exclusive OR circuit in which each output terminal of the optical coupling element is connected to an input side.