JPH0361818A - Photo power dispatching type signal processor - Google Patents

Abstract

PURPOSE:To prevent excessive photo power transmission for preventing a short life of an output light source by providing a power generating energy detecting means and a signal overlapping means on a signal processor side and a signal separating means and a light emission amount controlling means on a driving side. CONSTITUTION:A driving device 1 controls a laser light source 11 so that sum of output of a light amount controlling photo diode 13 and output of a signal processing unit 17 is constant, while the laser is modulated by pulse signals and an amplifier circuit 14 controls a peak value. A light signal is sent to a processing circuit II with an optical fiber 30. A conversion processing unit 26 is driven via a photo diode 21 and a transformer 22. With input photo power compared with reference voltage, if the input is smaller, output of a comparator is overlapped with output of the conversion processing unit. When a modulation circuit 27 senses drop in photo power, a sensor outputs and sends frequency signals (b) of double pulses to the driving device I. A separating demodulation circuit 16 separates output (a) of the voltage comparator 24 from the sensor signal (b) and the signal processing unit 17 increases/decreases the signals to a control amplifier according to existence or not of the signal so that the signal is suppressed to be the minimum photo power required for detection of a sensor 25 thereby lengthening laser life.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention supplies energy as optical energy from the drive device side to the signal processing device side, and generates optical energy by power generation means on the signal processing device side. is converted into an electrical signal and used as a power source for the sensor and a power source for the signal transmission means.The sensor detection signal is also converted from the signal processing device side into an optical signal and transmitted to the drive device side, where it is demodulated into an electrical signal. The present invention relates to a light-fed signal processing device that extracts the sensor output as a sensor output.

(Prior technology) In extremely noisy environments such as power equipment, a method of converting the signal output into an optical signal and transmitting it is widely used to improve the noise resistance of signal processing devices such as sensors. There is.

In this case, the power supply line to the signal processing device is also a route for noise to enter, so it is necessary to provide complete electromagnetic shielding, and for this purpose, the signal processing device is battery-powered and an electrically closed system is configured. It is effective to do so. However, in this case, the maintenance burden of battery replacement is required.

Therefore, as a method that does not use batteries, the light emitted by a semiconductor laser or the like is transmitted to the signal processing device using an optical fiber, and at the radiation end, a solar cell generates electricity to drive the signal processing device. A method has been proposed in which signals are isolated from power supply energy using light using a type signal processing device.

However, in optically powered signal processing equipment, the efficiency of optical/electrical conversion is low and the loss in the optical transmission system is large, so the light source side must generate energy several tens of times greater than the energy consumed by the signal processing equipment side. Is this an inevitable problem?
Ta.

FIG. 4 shows an example of such a conventional optically powered signal processing device, in which light emitted from a high-output light source 1 of a driving device I is transmitted to a signal processing device n side via an optical fiber 2.
It is converted into electrical energy by the solar cell 3. and,
Each device of the signal processing device (■) is driven by this electric energy, and the input signal of the sensor 4 is processed by the conversion processing section 5.The processed signal is converted into an optical signal by the driving section 6, and the optical signal is transmitted again to the driving device WI. Transmission through fiber 7.

The drive device I receives signals from the optical fiber 7.
Second, the optical/electrical converter 8 demodulates the signal I7 into an appropriate electrical signal, which is then electrically extracted as a detection signal for the sensor 4.

(Problems to be Solved by the Invention) In such conventional optically powered signal processing devices, a semiconductor laser is generally used as the high-output light source ε, but the lifespan of the semiconductor laser is approximately 2 to 4 times the power of the emitted light. It is known that the life span is exponentially shortened as the light emitting power is increased, so it is desirable to drive with the minimum necessary light emitting power as much as possible. However, in conventional optically powered signal processing devices, excessive light energy is used to operate the light source, including margins such as age-related changes in the amount of light emitted by the light source, reductions in conversion efficiency due to temperature changes in the solar cells, and losses during maximum distance transmission. There was a problem in that the life of the light source was shortened more than necessary because the light source had to be driven.

This invention was made in view of these conventional problems, and it is possible to always maintain the electrical energy received by the signal processing device at a minimum value regardless of the transmission distance, ambient temperature conditions, etc., thereby extending the life of the light source. An object of the present invention is to provide an optically-fed signal processing device that can perform the following steps.

[Structure of the Invention] (Means for Solving the Problem) The present invention includes a sensor that measures a physical quantity, a signal transmission means that converts a detection signal of the sensor into an optical signal and transmits it via an optical fiber, and an optical fiber. a signal processing device equipped with a power generation means for converting optical energy transmitted through the optical fiber into electrical energy and supplying the electrical energy to the sensor and the signal transmission means; a high-output light source that emits optical energy to the optical fiber; A light-fed signal processing device comprising a drive device ε equipped with a signal processing means for converting an optical signal transmitted from a processing device into an electric signal and demodulating a detection signal of the sensor, the signal processing device A power generation energy detection means for detecting the power generation energy of the power generation means and a signal superimposition means for superimposing the power generation energy detection signal from the power generation energy detection means on the output of the signal transmission means are provided on the drive device side, and the signal superposition means is provided on the drive device side. a signal separating means for separating the generated energy detection signal superimposed by the superimposing means from the detection signal of the sensor; and a signal separating means for controlling the amount of light emitted from the high output light source based on the separated generated energy detection signal, so that the generated energy of the power generating means is This device is provided with a light emission amount control means that adjusts the amount of light emission to be approximately constant.

(Function) In the optically powered signal processing device of the present invention, the generated energy converted by the power generation means is detected by the generated energy detection means on the signal processing device side, and this generated energy detection signal is superimposed on the sensor detection signal by the signal superimposition means. The signal is then transmitted to the drive device via an optical fiber.

On the drive device side, the signal separation means separates the two signals and provides the generated energy signal to the light emission amount control means, which performs feedback control of the light emission amount of the high output light source so that the generated energy is approximately constant.

In this way, a noise-resistant physical quantity measurement system is constructed by optical power supply, and the light source life is extended by always controlling the amount of light emitted by the high-output light source to the minimum necessary level.

(Example) Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.

FIG. 1 shows an embodiment of the invention. The optically-fed signal processing device is roughly composed of a driving device I, a signal processing device (2), and optical fibers 30 and 31 connecting the two.

The drive device (2) includes a semiconductor laser 11 as a light source, a control drive circuit 12 for the semiconductor laser 11, a photodiode 13 for automatic light amount control of the semiconductor laser 11, a charging current amplification circuit 14, and a signal processing device (2). Photodiode 1 receives incoming optical signals and converts them into electrical signals
5, and a separation/demodulation circuit 16 that separates the electrical signal output from the photodiode 15 into two signal components a and b.
and a signal processing section 17 that converts the electrical signal component into an appropriate signal.

On the other hand, the signal processing device (2) includes a photodiode 21 for converting optical energy sent from the driving device I into electrical energy, a transformer 22 for boosting the output voltage of the photodiode 12, and a transformer 22 for boosting the output voltage of the photodiode 12. a rectifier circuit 23 that converts the signal into a DC signal, a voltage comparator 24 that compares the DC output voltage of the rectifier circuit 23 with a reference voltage with a certain hysteresis, and a detection signal of a sensor 25 for physical quantities such as temperature and pressure. a conversion processing unit 26 that converts the output signal of the voltage comparator 24 and the conversion processing unit 2
6, and a light source 28 driven by the output of the modulation circuit 27.

Next, the operation of the optically fed signal processing device having the above configuration will be explained.

The optically powered signal processing device has two basic functions, one of which is to amplify the output signal of the sensor 25 in the conversion processing section 26, convert it into a frequency signal, etc. in the modulation circuit 27, and optically transmit it. The function is to demodulate this signal using the separation/demodulation circuit 16 and extract it as an appropriate electrical signal. Another function is to control the emission power of the semiconductor laser 11 on the driving device I side by using the output signal of the voltage comparator 24 with hysteresis in order to keep the output voltage of the rectifier circuit 23 of the signal processing device (2) constant and provide it to the sensor 25. It's about controlling.

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 1 as a high-power light source in drive device ■
1 has a configuration in which its forward current is controlled so that the sum of the output of the photodiode 13 and the output from the signal processing section 17 for automatic light amount control becomes constant. Therefore, by changing the output of the signal processing section 17, the amount of light emitted by the semiconductor laser 11 can be changed. In addition, the semiconductor laser 11 has a power of several to several tens of KH.
The amplifier circuit 14 performs peak value control using a peak hold circuit or average value control using an integrating circuit.

In this way, the frequency-modulated optical signal from the semiconductor laser 11 is transmitted via the optical fiber 30 to the photodiode 21 on the signal processing device (2) side.

In the signal processing device (■), since the transmitted optical power is modulated by pulses, the optical/electrical conversion signal output by the photodiode 21 becomes an alternating current, and the transformer 22
The output is boosted and used to drive the conversion processing section 26.

Here, when the human power optical power is insufficient, the boosted voltage is smaller than the reference voltage, and the output of the voltage comparator 24 is superimposed on the output of the conversion processing section 26 in the modulation circuit 27. Conversely, When the input light) is excessive, the obtained voltage is higher than the reference voltage and the output of the voltage comparator 24 is
It is not superimposed on the output of 6.

The signal superimposition method in this modulation circuit 27 and 1
, If the signal of the sensor 25 is converted into a voltage-frequency signal by the conversion processing unit 26 and there is a frequency signal 17, the output of the voltage comparator 24, A, There is a pulse (rubbing method). According to this method, when the obtained light power is sufficiently large (J is the sensor output is a single pulse frequency signal, and as the optical power decreases, the sensor output is doubled). This will be a 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 (2) via the optical fiber 31.

On the drive device I side, the signal is transmitted via the optical fiber 31.
r) < Zl The optical signal is input to the separation and demodulation circuit 16,
Here, the output signal a of the voltage comparator 24 is separated from the sensor output signal 41, and the presence or absence of that signal is determined by the signal processing section 17, and the output of the control amplifier circuit 12^2 is increased or decreased.

The overall control flow is shown in timing chart 1 in FIG.

First, as shown in FIG. 2(b) lj, there is an output from the voltage comparator 24, which is superimposed on the sensor output signal and given from the signal processing device ■ side to the drive unit WI side, and it is determined that the optical power is low. Ru. Therefore, the signal processing unit 17 gradually increases the forward current of the semiconductor laser 11 as shown in FIG. As shown in figure (a), rise 1. To go.

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 and is no longer superimposed on the sensor output.
decreases the forward current of the semiconductor laser 11-.

Part 1. When the optical power decreases and the voltage comparator 24 starts outputting again, the semiconductor 1 nose 1.1
Increases power.

In this way, the amount of light emitted by the semiconductor laser 11 is controlled to increase or decrease as shown in FIG. By transmitting the minimum optical power necessary for the sensor 25 to detect the physical quantity, the semiconductor laser 1-
This prevents the lifespan from being shortened due to excessive light emission caused by 1.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, as shown in FIG. Optical power supply and sensor signal transmission can be performed in both directions with just one wire.

[Effects of the Invention] As described above, according to the present invention, there is a generated energy detecting means for detecting the generated energy of the power generating means on the signal processing device side, and a generated energy detection signal by the generated energy detecting means is outputted from the signal transmitting means. A signal superimposing means is provided for superimposing the generated energy detection signal on the signal superimposing means, and a signal separating means for separating the generated energy detection signal from the signal superimposing means from the sensor detection signal is provided on the drive device side, A light emission control means is provided to control the light emission amount of the high-output light source so that the generated energy of the power generation means is almost constant, so that the optical power is given from the drive device side to the signal processing device side through the optical fiber. It is possible to suppress ε to the minimum required for physical quantity measurement processing by sensors, and the lifespan of high-output light sources is not shortened due to the transmission of excessive optical power as in the past, and the high-output light sources are It can extend the lifespan.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention, FIG. 2 is a timing chart explaining the operation of the above embodiment, and FIG. 3 is a perspective view of an optical fiber used in another embodiment of the invention. FIG. 4 is a circuit block diagram of a conventional example. ■...Driver 11...Semiconductor laser 13...Photodiode 14...Charge current amplification circuit 15...Photodiode 16...Separation and demodulation circuit 21□...Photodiode 22... Transformer 24...Voltage comparator 26...Conversion processing unit 28...Light source 31...Optical fiber ■...Signal processing device 12...Control drive circuit 17...Signal processing unit 3... - Rectifier circuit 5...Sensor 7...Modulation circuit O...Optical fiber

Claims (1)

[Claims] A sensor that measures a physical quantity, a signal transmission means that converts a detection signal of the sensor into an optical signal and transmits it via an optical fiber, and converts the optical energy transmitted via the optical fiber into electrical energy. a signal processing device equipped with a power generation means for converting the optical signal into an optical signal and supplying it to the sensor and the signal transmission means; a high-output light source that emits optical energy to the optical fiber; A light-fed signal processing device comprising: a drive device equipped with a signal processing means for converting into a signal and demodulating a detection signal of the sensor; and a signal superimposing means for superimposing a generated energy detection signal from the generated energy detecting means on the output of the signal transmission means, and the driving device side receives the generated energy detection signal superimposed by the signal superimposing means. signal separating means for separating the signal from the detection signal of the sensor; and a light emitting device for controlling the amount of light emitted from the high output light source based on the separated generated energy detection signal so that the generated energy of the power generating means is approximately constant. An optical power supply type signal processing device comprising a quantity control means.