JPH0435997Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention supplies optical pulses from an optical transmitter to an optical sensor via a star coupler, and receives sensor information to obtain various measurement results. This article relates to an optical multi-sensor device.

[Conventional technology]

Conventionally, Japanese Patent Laid-Open No. 105397/1983 has proposed a method for measuring physical quantities at remote locations using optical fibers.

As shown in FIG. 2, this is a configuration in which a light pulse transmitting/receiving circuit A and a light sensor circuit B are connected through a single optical fiber as a transmission path to obtain information from the light sensor.

The electrical signal generated by the pulse generator 21 is input to the optical transmitter 22 that converts it into an optical pulse, and the optical pulse generated by the optical transmitter 22 is transmitted to the optical directional coupler 2.
3 and is sent to the optical sensor circuit B via the transmission line 24, and the 1:n star coupler (multi-branch coupler) 2 branches the optical pulse to a plurality of optical sensors.
Enter 5. The optical pulses branched here pass through optical delay devices 261, 262, and 26n and enter optical sensors 271, 272, and 27n. The optical signal received in the optical sensor is transmitted to the reflecting plates 281, 282, 2.
8n, the signal returns to its original path and reaches the optical directional coupler 23 of the transmitting/receiving circuit A, where it is branched and enters the optical receiver 30, where it is processed by the signal processing device 31 and displayed on the display device 32. Ru.

[Problem to be solved by the present invention] However, in such a device, the intensity of the optical pulse is
The amount of light returning from the star coupler 25 to the transmission line 24 is the reciprocal of the number of branches n, and is further branched at the optical directional coupler 23, so the intensity of the optical pulse entering the optical receiver is equal to that generated at the optical transmitter 22. About 1/ of the time
It becomes 2n. For this reason, the difference from the signal due to reflection occurring at the joints of terminals, couplers, reflectors, etc. becomes small and difficult to distinguish, so-called S/
The N ratio becomes worse. In addition, in a reflective optical sensor, a signal due to reflection during sensor input/output is generated near the signal containing sensor information, resulting in noise.
Since the signal is close to the sensor information signal, it becomes difficult to separate the signal, resulting in a problem of poor S/N ratio.

The present invention aims to solve the above-mentioned problems and provide a multi-sensor device with high signal pulse intensity from the optical sensor and high precision.

[Means to solve the problem]

Therefore, in this invention, in order to distribute and supply optical pulses from a transmission optical path to multiple optical sensors, the input side and output side terminals are m (m is an integer of 3 or more): n
(n is an integer of 2 or more), connect the transmitter optical line to one terminal on the input side, connect the branch optical line to each terminal on the output side, and connect the remaining terminals on the input side. All of them are connected to a common receiving optical line and connected to an optical receiver.

Further, it is desirable that the optical sensor be of a transmission type, and that the input side terminal and output side terminal of each sensor be connected to separate branch optical lines.

[Effect]

In this way, since multiple input terminals of the star coupler are connected together to the receiving optical line, the intensity of the optical pulse sent to the optical receiver is (m-1)/
(m×n), so the signal level can be increased.

In addition, by configuring the optical sensor as a transmission type and connected to two branched optical lines, a time difference is created between the sensor information signal and the noise, making it easier to separate the noise and increasing the S/N ratio. Therefore, measurement accuracy is improved.

〔Example〕

This will be explained with reference to an embodiment shown in the drawings.

In FIG. 1, 1 is a pulse generator, 2 is an optical transmitter that converts electrical pulses into optical pulses and sends them out;
3 is a transmission optical line using optical fiber, 4 is a star coupler, 51, 52, 53...5n is a branch optical line made of optical fiber, 61, 62, 63...
...6n is an optical delay circuit, which is constructed by, for example, sequentially winding optical fibers of different lengths. 71, 72, 73...7n are reflective or transmissive optical sensors provided on the object to be measured 8;
For example, it detects voltage, current, temperature, or the status of protective devices in electrical equipment.

9 is an optical fiber receiving optical line, 10 is an optical receiver, 11 is an amplifier, 12 is a signal processing device,
13 is a display device.

Electric pulses generated from the pulse generator 1 at a time interval shorter than the time that light propagates from the optical transmitter 2 to the optical receiver 10 are converted into optical pulses by the optical transmitter 2 and sent to the optical transmission line 3. Sent out. This optical pulse enters from one input side terminal of the star coupler 4 and is branched into branch optical lines 51, 52, 53...5n, and optical delay circuits 61, 62, 63...
...6n (61 may have substantially no delay) to the optical sensors 71, 72, 73...7n.

Detection signals (sensor information) from the optical sensors 71, 72, 73...7n are returned to the star coupler 4 in the order of delay by the optical delay circuit, and are branched to input side terminals. Among the branched detection signals, the detection signals of the other terminals excluding the terminal connected to the transmission optical line 3 are collectively sent to the reception optical line 9, and converted into electric pulses by the optical receiver 10.
The signal is amplified by an amplifier 11 and processed by a signal processing device 12 .

Now, when there is an abnormality in the measured value of the optical sensor 72, a change has occurred in the second sensor information input to the optical receiver 10, and this is detected by the signal processing device 12 and displayed on the display device 13.

Here, connect the input side terminal of the star coupler to 3
If the number of output side terminals is four, the abnormal signal due to the optical intensity branched into four is branched to three input side terminals by a star coupler, and the output signals from two of these terminals are common. The light reaches the optical receiver 10 via the receiving optical line 9.

Therefore, the intensity of the optical pulse reaching the optical receiver 10 is approximately (3-1)/3×4=1/6,
Optical pulse intensity 1/2×4 when using conventional equipment
= greater than 1/8.

Note that an optical direction coupler may be provided on the transmitting optical line to branch the detection signal from the star coupler and connect it to a common receiving optical line together with other input side terminals, and each sensor They can be provided at separate and remote locations.

In addition, by using a transmission type sensor and installing it across two branched optical paths, the same detection signal (sensor information) can be obtained from both branched optical paths, and since a reflector is not required, the detection signal can be It is possible to eliminate nearby noise and improve the S/N ratio, and it is possible to omit a part of the optical line by inserting an optical direction coupler in the branched optical line.

[Effects of this invention]

As mentioned above, when transmitting multiple sensor information using optical fiber, there are m pieces on the input side (m is an integer of 3 or more) and n pieces on the output side (n is an integer of 2 or more).
A star coupler is provided with terminals, a transmitting optical line is connected to one terminal on the input side, a branch optical line is connected to the output side terminal, and the remaining terminals on the input side are connected to a common receiving optical line. Since it is connected to
The optical pulse intensity of the detection signal reaching the receiving optical line can be increased, the amplifier in the detection circuit may have a small dynamic range, and the S/N can be increased.
This has the effect of improving the ratio and ensuring reliable detection.
A highly accurate measuring device can be obtained.

Further, noise can be easily separated by using a transmission type optical sensor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional optical sensor device. 1 is a pulse generator, 2 is an optical transmitter, 3 is a transmission optical line, 4 is a star coupler, 5, 51, 52, 5
3...5n is a branch optical line, 6, 61, 62, 63
...6n is an optical delay circuit, 71, 72, 73, ...
7n is an optical sensor, 8 is an object to be measured, 9 is a receiving optical line, 10 is an optical receiver, 11 is an amplifier, 12 is a signal processing device, 13 is a display device, A is a transmitting/receiving circuit,
B is a light sensor circuit.

Claims (1)

[Claims for Utility Model Registration] 1. A transmission optical line made of an optical fiber that transmits optical pulses from an optical transmitter, and a branch optical line that supplies the optical pulses to a plurality of optical sensors through star couplers. and an optical multi-sensor device including a reception optical path for transmitting sensor information of each optical sensor from the star coupler to the optical receiver, wherein m star couplers are provided on the input side (m is an integer of 3 or more). and n terminals (n is an integer of 2 or more) on the output side, a transmission optical line is connected to one terminal on the input side, a branch optical line is connected to each terminal on the output side, and An optical multi-sensor device characterized in that the remaining terminals of the two are connected to a common receiving optical line. 2. The optical multi-sensor device according to claim 1, wherein the optical sensor is of a transmission type.