JPH0814501B2 - Optical power supply type signal processor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention supplies energy to a signal processing device side as light energy from a driving device side, and light energy is generated by a power generation means on the signal processing device side. Is converted into an electric signal to be used as a power source of the sensor and a power source of the signal transmission means, and the signal detection device side converts the sensor detection signal into an optical signal and transmits it to the driving device side, and the driving device side demodulates into an electric signal. The present invention relates to an optically-powered signal processing device that takes out as a sensor output.

(Prior Art) In an extremely severe noise environment such as electric power equipment, a method of converting the signal output to an optical signal and transmitting the signal is widely used in order to improve noise resistance of a signal processing device such as a sensor. There is.

In this case, the power supply line to the signal processing device also serves as a path for noise intrusion, so it is necessary to completely shield the electromagnetic wave. Therefore, the signal processing device is configured to be battery-operated to form an electrically closed system. It is effective to do. However, in this case, a maintenance load of battery replacement is required.

Therefore, a so-called optically-powered signal processing device that drives a signal processing device by transmitting light emitted from a semiconductor laser or the like to a signal processing device by an optical fiber as a system without using a battery and generating power by a solar cell at the radiating end thereof is used. There has been proposed a method of using light to insulate signals from power source energy.

However, in the optical power supply type signal processing device, the efficiency of optical / electrical conversion is low and the loss of the optical transmission system is large, so that the light source side must generate a large amount of energy which is several tens of times the energy consumed by the signal processing device side. There was a problem that had to be addressed.

FIG. 4 shows an example of such a conventional optical power feeding type signal processing device. Light emitted from the high output light source 1 of the driving device I is transmitted to the signal processing device II side via the optical fiber 2. It is converted into electric energy by the solar cell 3. Then, each device of the signal processing device II is driven by this electric energy, the input signal of the sensor 4 is processed by the conversion processing part 5, the processed signal is converted by the driving part 6 into an optical signal, and the driving device I up to. It is transmitted again through the optical fiber 7. In the drive unit I, when the signal from the optical fiber 7 is received, it is demodulated into an appropriate electric signal by the optical / electrical conversion unit 8 and is electrically taken out as a detection signal of the sensor 4.

(Problems to be Solved by the Invention) In such a conventional optical power feeding type signal processing device, a semiconductor laser is generally used as a high-power light source, but the life of the semiconductor laser is inversely proportional to the emission power of 2 to 4th power. It is known that, as the emission power is increased, the lifetime exponentially shortens, so it is desirable to drive with the minimum required emission power as much as possible. However, in the conventional optical power supply type signal processing device, the aging of the light emission amount of the light source,
The light source must be driven with excess light energy, including margins such as a decrease in conversion efficiency due to changes in the temperature of the solar cell and loss during maximum distance transmission, which shortens the life of the light source more than necessary. there were.

The present invention has been made in view of the above conventional problems, and can always maintain the electric energy received by the signal processing device to a minimum value regardless of the transmission distance, ambient temperature conditions, etc. It is an object of the present invention to provide an optical power supply type signal processing device capable of performing the above.

[Structure of the Invention] (Means for Solving the Problem) The present invention provides a sensor for measuring a physical quantity, a signal transmission means for converting a detection signal of the sensor into an optical signal and transmitting the optical signal through an optical fiber, and an optical fiber. A signal processing device provided with a power generation means for converting the light energy transmitted via the above into electric energy and supplying it to the sensor and the signal transmission means, a high output light source for emitting light energy to the optical fiber, and the signal. An optical power supply type signal processing device comprising: a drive device having a signal processing means for converting an optical signal transmitted from the processing device into an electric signal and demodulating a detection signal of the sensor. On the side, the power generation energy detection means for detecting the power generation energy of the power generation means, and the power generation energy detection signal by this power generation energy detection means are superimposed on the output of the signal transmission means. Signal separating means for separating the power generation energy detection signal superimposed by the signal superimposing means from the detection signal of the sensor, and the high output based on the separated power generation energy detection signal. A light emission amount control means is provided for controlling the light emission amount of the light source and adjusting the power generation energy of the power generation means to be substantially constant.

(Operation) In the optical power feeding type signal processing device of the present invention, the power generation energy converted by the power generation device is detected by the power generation energy detection device on the signal processing device side, and the power generation energy detection signal is superposed on the sensor detection signal by the signal superposition device. Then, it is transmitted to the drive unit side via the optical fiber.

On the side of the driving device, the signal separation means separates the two signals and gives a power generation energy signal to the light emission amount control means, where feedback control of the light emission amount of the high output light source is performed so that the power generation energy becomes substantially constant.

In this way, a physical quantity measuring system that is resistant to noise is configured by optical power feeding, and the light source life is extended by controlling the amount of light emitted from the high-output light source to the minimum necessary.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The optical power feed type signal processing device is roughly divided into a drive device I, a signal processing device II, and optical fibers 30 and 31 connecting the two.

The drive unit I includes a semiconductor laser 11 as a light source, a control drive circuit 12 for the semiconductor laser 11, and the semiconductor laser 11
A photodiode 13 for automatic light amount control, a photocurrent amplifier circuit 14, a photodiode 15 for receiving an optical signal sent from the signal processing device II and converting it into an electrical signal, and as an output of the photodiode 15. A separation / demodulation circuit 16 for separating an electric signal into two signal components a and b, and a signal processing unit 17 for converting the electric signal component into an appropriate signal are provided.

On the other hand, the signal processing device II has a photodiode 21 for converting the light energy sent from the driving device I into electric energy, a transformer 22 for boosting the output voltage of the photodiode 12, and a transformer 22 for boosting the output voltage. Circuit 23 for converting the generated signal to DC, a voltage comparator 24 for comparing the DC output voltage of the rectifier circuit 23 with a reference voltage with a certain hysteresis, and a sensor for physical quantity such as temperature and pressure.
A conversion processing unit 26 for converting the detection signal of 25, a modulation circuit 27 for superimposing the output signal of the voltage comparator 24 and the output signal of the conversion processing unit 26, and a light source driven by the output of the modulation circuit 27. 28 and.

Next, the operation of the optical power feeding type signal processing device having the above configuration will be described.

The optical power supply type signal processing device has two basic functions,
One of them is that the output signal of the sensor 25 is amplified by the conversion processing unit 26, converted into, for example, a frequency signal in the modulation circuit 27 and transmitted optically, and this is demodulated by the separation demodulation circuit 16 and taken out as an appropriate electric signal. That is the function. Another function is that the semiconductor laser 11 on the drive unit I side is controlled by the output signal of the voltage comparator 24 having hysteresis to keep the output voltage of the rectifier circuit 23 of the signal processing unit II constant and supply it to the sensor 25.
Is to control the light emission power of.

And since the feature of this embodiment lies in the latter function,
The operation of controlling the emission power of the semiconductor laser 11 to be constant will be described below.

Semiconductor laser as high-power light source in drive unit I
The forward current 11 is controlled so that the added value of the output of the photodiode 13 for automatic light amount control and the output from the signal processing unit 17 becomes constant. Therefore, the amount of light emitted from the semiconductor laser 11 can be changed by changing the output of the signal processing unit 17. The semiconductor laser 11 is modulated with a pulse signal of several K to several tens KHz, and the amplification circuit 14 in the above control performs peak value control by a peak hold circuit or average value control by an integration circuit.

Thus, the frequency-modulated optical signal from the semiconductor laser 11 is transmitted to the photodiode 21 on the signal processing device II side via the optical fiber 30.

In the signal processing device II, since the transmitted optical power is modulated by the pulse, the photo / electric conversion signal output by the photodiode 21 becomes an alternating current, and the output is boosted by the transformer 22 and the output of the conversion processing unit 26 is increased. It will be used for driving.

Here, when the input light power is insufficient, the boosted voltage is smaller than the reference voltage, and the output of the voltage comparator 24 in the modulation circuit 27 is superimposed on the output of the conversion processing unit 26. On the contrary, when the input light power is excessive, the obtained voltage is equal to or higher than the reference voltage, and the output of the voltage comparator 24 is not superimposed on the output of the conversion processing unit 26.

As a method of superimposing the signal in the modulation circuit 27, the signal of the sensor 25 is subjected to voltage-frequency conversion by the conversion processing unit 26 into a frequency signal, and when there is an output of the voltage comparator 24, each pulse of this frequency signal is There is a method of changing from a single pulse to a double pulse. According to this method, when the obtained optical power is sufficiently high, the sensor output becomes a single-pulse frequency signal, and when the optical power decreases, the sensor output becomes a double-pulse frequency signal.

The output signal of the modulation circuit 27 is converted into an optical pulse signal by the light source 28 and transmitted to the driving device I side via the optical fiber 31.

On the drive unit I side, the optical signal transmitted through the optical fiber 31 is input to the separation / demodulation circuit 16, where the output signal a of the voltage comparator 24 is separated from the sensor output signal b,
The presence or absence of the signal is determined by the signal processing unit 17, and the output to the control amplification circuit 12 is increased or decreased.

The overall control flow is shown in the timing chart of FIG.

First, as shown in FIG. 7B, there is an output from the voltage comparator 24, which is superimposed on the sensor output signal and given from the signal processing device II side to the driving device I side, and it is determined that the optical power is low. It Therefore, the signal processing unit 17 is a semiconductor laser.
The forward current of 11 is gradually increased as shown in FIG. 7C, and the output voltage of the rectifier circuit 23 is also increased as shown in FIG. I will do it.

However, when the rectified output reaches the upper limit of the hysteresis of the voltage comparator 24, the output of the voltage comparator 24 disappears,
Since it is no longer superimposed on the sensor output, the signal processor 17 reduces the forward current of the semiconductor laser 11. And
When the optical power decreases and the voltage comparator 24 starts to output again, the power of the semiconductor laser 11 is increased.

In this way, the emission amount of the semiconductor laser 11 is controlled to increase or decrease as shown in FIG. 2 (c) so that the output voltage of the rectifier circuit 23 on the signal processing device II side falls within a predetermined upper and lower limit range. By transmitting the minimum optical power required for detecting the physical quantity of the sensor 25, the life of the semiconductor laser 11 is prevented from being shortened due to excessive light emission.

The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 3, by using directional couplers 33, 34 instead of the optical fibers 30, 31, the optical fiber 35 can be used.
It becomes possible to bidirectionally perform optical power feeding and sensor signal transmission with only one of the above.

[Effects of the Invention] As described above, according to the present invention, the power generation energy detection means for detecting the power generation energy of the power generation means on the signal processing device side, and the power generation energy detection signal by the power generation energy detection means are output to the signal transmission means. And a signal separating means for separating the power generation energy detection signal superimposed by the signal superimposing means from the detection signal of the sensor on the drive device side, and a high output light source of the high output light source based on the separated power generation energy detection signal. Since the light emission amount control means for controlling the light emission amount and adjusting the power generation energy of the power generation means to be substantially constant is provided, the optical power given from the driving device side to the signal processing device side through the optical fiber is measured by the physical quantity by the sensor. It can be minimized to the minimum required for measurement processing, and the shortevity of high output light sources by transmitting excess optical power as in the past The life of the high-power light source can be extended without causing life.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the above embodiment, and FIG. 3 is a perspective view of an optical fiber used in another embodiment of the present invention. FIG. 4 is a circuit block diagram of a conventional example. I ... Drive device, II ... Signal processing device 11 ... Semiconductor laser, 12 ... Control drive circuit 13 ... Photodiode 14 ... Photocurrent amplifier circuit 15 ... Photodiode 16 ... Separation demodulation circuit, 17 ... … Signal processing unit 21 …… Photodiode 22 …… Transformer, 23 …… Rectifier circuit 24 …… Voltage comparator, 25 …… Sensor 26 …… Conversion processing unit, 27 …… Modulation circuit 28 …… Light source, 30 …… Optical fiber 31 ... Optical fiber

Claims (1)

[Claims] 1. A sensor for measuring a physical quantity, a signal transmitting means for converting a detection signal of the sensor into an optical signal and transmitting the optical signal through an optical fiber, and optical energy transmitted through the optical fiber into electric energy. A signal processing device including a power generation unit that converts and supplies the sensor and the signal transmission unit, a high-output light source that emits optical energy to the optical fiber, and an optical signal transmitted from the signal processing unit as an electrical signal. In the optical power feed type signal processing device, which is provided with a drive device having a signal processing means for converting into a signal and demodulating a detection signal of the sensor, the power generation energy of the power generation means is detected on the signal processing device side. The power generation energy detecting means and the signal superimposing means for superimposing the power generation energy detection signal by the power generation energy detecting means on the output of the signal transmitting means are provided, and the drive is provided. A signal separating means for separating the power generation energy detection signal superimposed by the signal superimposing means from the detection signal of the sensor on the installation side, and controlling the light emission amount of the high output light source based on the separated power generation energy detection signal, An optical power feed type signal processing device comprising a light emission amount control means for adjusting the power generation energy of the power generation means to be substantially constant.