JPH05307051A - Abnormality monitoring device for sensor circuit - Google Patents

Abstract

PURPOSE:To preclude a system from risk of malfunction by sensing abnormality in an optical circuit such as severance at the time the power to the sensor circuit of a photo sensor is put on, and indicating the channel in which the abnormality has occurred in the event of abnormality occurrence during the system being in operation. CONSTITUTION:Magnetic field or electric field is sensed by a photo-sensor 1, and the obtained optical signal is converted into electric signal by a converter circuit 4, and the size of the DC component of this electric signal is fed to a abnormality indication part 10 at the time of abnormality occurrence. A setting circuit makes setting so that the size of the DC component of the electric signal given by the converter circuit 4 becomes constant. Signal from the setting circuit is fed to a computational processing part 7, and an output judging part 8 judges whether the result from computation is to be emitted as the output, and the output part 11 emits the output of a abnormality information output judging part 9 or the output judging part 8. Thus the output is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality monitoring device for detecting a magnetic field or an electric field using an optical sensor.

[0002]

2. Description of the Related Art Optical sensors utilizing the Faraday effect and the Pockels effect are excellent in environment resistance, noise resistance, and insulation and have been put to practical use in various fields. For example, in the case of an optical voltage sensor using the Pockels effect, the operation curve is represented by the equation (1). P = PO / 2 * (1 + sinπV / Vπ) = PO / 2 + PO / 2 * sinπV / Vπ (1) where PO is the incident power to the optical sensor, P is the output power from the optical sensor, and V is the applied power. The voltage, Vπ, is a half-wave voltage. As can be seen from the equation (1), when the output power of the light emitting diode (hereinafter referred to as LED) changes due to the influence of the temperature change and the incident power P0 to the optical sensor changes, the output power of the optical sensor changes. The DC component of the first item and the AC component of the second item of P change at the same rate. Therefore, when such an optical sensor is used, detection is performed using the modulation factor m represented by the equation (2) so as not to be affected by the incident power. m = AC component / DC component = sin πV / Vπ (2) Actually, an automatic power control circuit that feeds back to the current flowing through the LED so that the DC component of the output power from the optical sensor does not change on the detector side. A method (hereinafter referred to as an APC circuit), an automatic gain control circuit (hereinafter referred to as an AGC circuit) that feeds back to a gain, or a method of obtaining a ratio of an alternating current component to a direct current component by hardware or software is adopted.

[0003]

However, in the detection circuit using the optical sensor, it is necessary to keep the minimum received light power in order for the detection circuit to operate normally regardless of which of the above methods is used. .. Therefore, after installing the optical sensor and the detection circuit, it is always necessary to check the light receiving power of the detection circuit or the loss of the optical circuit for each channel. Also, after the APC circuit and AGC circuit, only the AC component is used for detection by AC coupling.
Even if the optical power decreases for some reason during system operation and becomes lower than the lower limit minimum received light power at which the detection circuit operates normally, the detection circuit continues to detect, and the system may malfunction. The present invention has been made in order to solve the above problems, by installing an optical sensor and a detection circuit,
When the power of the detection circuit is turned on, an abnormality due to a disconnection of the optical circuit is detected, the channel in which the abnormality has occurred can be detected, and if an abnormality occurs during system operation,
The purpose is to know the channel in which an abnormality has occurred and to prevent the system from malfunctioning.

[0004]

In order to solve the above-mentioned problems, the present invention provides a conversion circuit for converting an optical signal in which a magnetic field or an electric field is detected by an optical sensor into an electric signal, and a DC component of the electric signal from the conversion circuit. Setting circuit that sets the magnitude of the signal to be constant, an optical power detection unit that detects the magnitude of the DC component of the electrical signal from the conversion circuit and outputs it to the abnormality display unit in the event of an abnormality, and an electrical signal from the conversion circuit Error display section that displays the error information when the DC component of is less than or equal to the set value, the output determination section that determines whether the signal from the setting circuit is calculated by the calculation processing section and outputs the calculation result, and the optical power An output section for outputting either the output from the abnormality information output determining section or the output from the output determining section is provided by the output from the detecting section.

[0005]

Therefore, for the abnormality before the system operation, the optical sensor and the detection circuit are installed so that the abnormality display section of the detection circuit and the channel in which the abnormality has occurred can be recognized when the power is turned on. Further, when an abnormality occurs during system operation, only the abnormality information is transmitted without transmitting the detection information to the detection data processing terminal.

[0006]

EXAMPLE The present invention will be described below with reference to the example shown in FIG. 1 is an optical sensor, 2 is a light transmitting means, 3 is a light source for outputting light to the optical sensor, 4 is a conversion circuit for converting an optical signal from the optical sensor into an electric signal, and 5 is a DC component of the output from the conversion circuit. AGC circuit that sets the gain so as to be constant,
Reference numeral 6 is an optical power detection unit for inputting a signal from the opto-electric conversion unit and detecting whether or not the signal is equal to or more than a set value. Reference numeral 7 is for inputting the signal of the AGC circuit and arithmetically processing the signal. A processing unit, 8 is an output determination unit that determines whether to output a signal from the arithmetic processing unit, 9 is an abnormality information output determination unit that determines whether to output abnormality information, and 10 is a channel in which an abnormality has occurred. An abnormality display section 11 for displaying the signal is an output section for inputting a signal from the output determination section and a signal from the abnormality information output determination section, and outputting the signal to a monitoring device (not shown). Next, the operation will be described. The optical signal from the optical sensor is converted into an electric signal by the conversion circuit 4,
When the DC component of the electric signal is equal to or less than the set value, the optical power detection unit 6 issues a command to the abnormality display unit 10 to turn on the LED to display the channel in which the abnormality has occurred, and the output determination unit 8 and the abnormality information output. The abnormality information output determination unit 9 outputs an abnormality information to the output unit 11 while issuing a command to the determination unit 9 so that the detection information is not output. The output unit 11 outputs abnormality information to the outside according to a predetermined format. Although the example using the AGC circuit has been described in the present embodiment, it can be applied to the case where an APC circuit or another method is used, and an example in which two photosensors are installed in parallel is shown. May be installed.

[0007]

As described above, according to the present invention,
When installing the optical sensor and detection circuit before configuring the entire system, it is possible to immediately check the presence or absence of an abnormality and the channel in which an abnormality has occurred, so it is necessary to check the optical power or loss for all channels as in the past. Therefore, the operation of the detection circuit can be easily confirmed. In particular, it is useful in the case of a large-scale system in which a large number of optical sensors and detection circuits are installed. If an abnormality occurs during operation, the detection signal is not output to the outside, so that the malfunction of the entire system due to the false detection can be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an abnormality monitoring device showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical sensor 2 Optical transmission means 3 Light source 4 Conversion circuit 5 AGC circuit 6 Optical power detection section 7 Arithmetic processing section 8 Output determination section 9 Abnormality information output determination section 10 Abnormality display section 11 Output section

Claims (1)

[Claims] 1. A detection circuit for detecting a magnetic field or an electric field using an optical sensor, a conversion circuit for converting an optical signal of which the magnetic sensor detects the magnetic field or the electric field into an electric signal, and a DC component of the electric signal from the conversion circuit. A setting circuit that sets the magnitude to be constant, an optical power detection unit that detects the magnitude of the DC component of the electrical signal from the conversion circuit and outputs it to the abnormality display unit in the event of an abnormality, and an electrical signal from the conversion circuit. An abnormality display section that displays abnormality information when the DC component is less than or equal to a set value, an output determination section that determines whether the signal from the setting circuit is calculated by the calculation processing section and outputs the calculation result, and an optical power detection An abnormality monitoring device for a detection circuit, comprising: an output unit that outputs either the output from the abnormality information output determination unit or the output from the output determination unit according to the output from the unit.