JPH0578086U - Multi-channel optical communication device - Google Patents

Abstract

(57) [Abstract] [Purpose] In addition to being able to perform remote measurement, ensure reliable electrical insulation and transmit measurement signals without being affected by electrical noise. A measuring signal from a plurality of transducers is input, the measuring pulse signal is switched and output through a multiplexer by a counter reference pulse generating means, and this measuring pulse signal is converted into a pulse amplitude modulation signal by an adder and a sample hold circuit. At the same time, a battery-driven transmission detection unit that frequency-converts and outputs this is provided. In addition, a reception measurement unit is provided which is linked to the transmission detection unit by an optical fiber. The reception measurement unit restores the input frequency conversion signal to a pulse amplitude modulation signal by the voltage converter and enables the measurement signal corresponding to the plurality of transducer signals to be output via the decommutator. The battery driving circuit of the transmission detection unit is provided with a switching element that is opened and closed by an optical signal supplied from the reception measurement unit via the optical fiber path and a capacitor connected in parallel with the transmission detection unit.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a multi-channel optical communication device, and more particularly to a multi-channel optical communication device suitable for remotely measuring by a plurality of sensors.

[0002]

[Prior Art]

 Conventionally, measurement signals from various transducers such as a load cell, a pressure sensor, and a position sensor are generally transmitted by a hard wire directly electrically connected to a recording device or a control device. That is, when measuring with a detection device such as position detection, pressure detection, force / torque detection, etc., the detected value is taken out as an electric signal and this is output to the recording device / control device via an amplifier, etc. A so-called electric wire is used for the transmission path. Then, the analog signal detected by the detection device is transmitted to the measurement device side, and if necessary, A / D converted and digitally processed in the recording device.

[0003]

[Problems to be solved by the device]

 However, it may not be possible to make a direct hard wire connection between the transducer and the measuring device. For example, if the transducer is operated under high voltage, electrical isolation is required for safety reasons, or electrical noise pickup is a problem.

The present invention pays attention to the above-mentioned conventional problems, and particularly in a system in which a high voltage exists, a measuring operator can perform remote measurement without approaching the high voltage region, and also provides electrical insulation. It is an object of the present invention to provide a multi-channel optical communication device that can be reliably realized and that can transmit a measurement signal without being affected by electrical noise.

[0005]

In order to achieve the above-mentioned object, a multi-channel optical communication device according to the present invention inputs measurement signals from a plurality of transducers, and a counter reference pulse generating means outputs the measurement signals via a multiplexer. A battery-powered transmission detection unit that switches and outputs the measurement pulse signal, converts this measurement pulse signal into a pulse amplitude modulation signal by an adder and a sample hold circuit, and frequency-converts this output signal, and this transmission detection unit. The frequency-converted signal input through this optical fiber is linked to the optical fiber, and the voltage-converted signal is restored to the pulse-amplitude-modulated signal by the voltage converter. It is equipped with a reception measurement unit capable of outputting, and is connected to the battery drive circuit of the transmission detection unit. It is provided with a reception measurement unit or we capacitors connected in parallel and the transmission detector switching element which is opened and closed by an optical signal supplied through the optical fiber path.

[0006]

[Action]

 According to the above configuration, the battery-driven transmission detection unit and the reception measurement unit are provided, and the former serves as a drive source for the transducer, and converts the detection signal from the transducer into a frequency-modulated optical signal. The latter converts the optical signal transmitted through the optical fiber back into the transducer signal. The transmission detection unit and the reception measurement unit are connected by an optical fiber and can be placed over a long distance. The interposition of this optical fiber enables remote measurement and also ensures the electrical insulation function.

Particularly, in the present invention, a plurality of transducers can be simultaneously used by performing a sampling process, and at the same time, it is possible to reduce the power consumption in the transmission measurement unit and reduce the number of transducers. Even when used, it is possible to transmit multiple measurement signals with a single optical fiber.

Further, the operation time of the transmission detector is about 25 hours using a standard 9 volt battery, but in the present invention, the switching element interposed in the battery circuit of the transmission detector is passed through the second optical fiber. Since it can be switched on and off by the optical signal sent from the reception and measurement unit, the battery life can be saved.

Further, the battery voltage at the transmission detection unit and the residual life of the battery can be confirmed by measuring the capacitor element of the transmission signal at the reception measurement unit side.

The frequency-modulated signal from the transmission detector may be converted into an analog voltage by a high-speed phase lock loop type frequency / voltage converter in the reception measurement unit. This converter is not special, but does not have the speed limits of conventional frequency / voltage converters.

[0011]

【Example】

 Hereinafter, a specific embodiment of the multi-channel optical communication device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the overall configuration of a multi-channel optical communication device according to an embodiment, FIG. 2 is a block diagram showing the configuration of a transmission detection unit, and FIG. 3 is a block diagram showing the configuration of a reception measurement unit. It is a diagram.

The apparatus according to the embodiment includes a battery-driven transmission detection unit 12 having a plurality of transducers 10 ₁ , 10 ₂ , 10 ₃ ... 10 _n (n = 6 in the embodiment) and a remote location. A reception measuring unit 14 for receiving a signal transmitted from the transmission detecting unit 12 is provided, and an optical fiber cable 16 used for signal transmission is provided to connect the both.

First, as shown in FIG. 2, the transmission detector 10 is provided with a clock 18 for generating a square wave pulse of 400 Hz. The output pulse from this clock 18 sets the sampling rate and is used to control the timing of various digital elements. A one-shot multivibrator 20 is connected to the output side of such a clock 18, which generates an output pulse when the input square wave from the clock 18 changes from low level to high level. There is. These pulses are set to have a pulse width of about 150 microseconds. The output pulse generates two types of pulses, one of which changes positively and the other of which changes negatively.

A counter 22 is connected to the one-shot multivibrator 20, and a negative change pulse of the output pulse is inputted to the counter 22. The counter 22 receiving this counter continuously counts from 0 to 7. There is. In this case, the counter 22 produces a 3-bit output which matches the numbers 0 to 7. The counter 22 counts from 0 to 7 and is reset, and then the sequence is repeated.

Next, an 8-channel multiplexer 24 is connected to the output side of the counter 22 and controls it. The multiplexer 24 basically constitutes a single-pole 8-position switch. In this example, each of the eight output lines is installed one at a time so that they can be operated continuously. The 3-bit output from counter 22 determines which channel line is grounded. The input from the one-shot multivibrator 20 to the multiplexer 24 controls the length of time each channel is grounded. Since the pulse width is 150 microseconds, each channel is grounded for a time of 150 microseconds.

The eight output signals from the multiplexer 24 are the same eight channel drivers 26.₁, 26₂, 26₃…… 26_mIs to control. Each channel driver 26₁, 26₂, 26₃…… 26_mIs a low impedance source capable of supplying a few milliamps at 5 volts. The driver output has a potential of either ground or 5 volts depending on the control signal from the multiplexer 24. Driver 26₁, 26₂, 26₃…… 26_mWhen the input to is grounded by multiplexer 24, its driver output is 5 volts, otherwise it is a ground potential output. The multiplexer 24 has each driver 26  1, 26₂, 26₃…… 26_mSince the input to is grounded for 150 microseconds, the driver output also holds a 5 volt potential for 150 microseconds. The driver is continuously switched on and off by a multiplexer. Since the transmitter clock is operated at 400 hertz, each driver will have 50 on / off switching times (400/8). As such, each driver continues to be on for 150 microseconds every 20 milliseconds.

Each of the channel drivers 26 ₁ , 26 ₂ , 26 _3, ... 26 _m includes reference signal generators 28 ₁ , 28 ₂ constituting two kinds of signal sources driven by these and the transducer 10 described above. ₁ , 10 ₂ , 10 _3, ... 10 _n are connected.

The first two reference signal generators 28 ₁ and 28 ₂ are built in the transmission detection unit, generate signals of fixed amplitudes of the maximum and minimum values, and the reception measurement unit 14 I am trying to use it for the purpose of signal restoration. The remaining six transducers 10 ₁ , 10 ₂ , 10 ₃ ... 10 _n as signal generators are strain gauge bridges incorporated in load cells, pressure transducers and the like. The internal reference signal generators 28 ₁ and 28 ₂ that generate the two maximum and minimum values are electrically resistive bridges having the same fixed output as the strain gauge.

The input voltage to these bridges is derived from the 5 volt voltage channel driver output. The driver output is a 5 volt signal of only 150 microseconds output 50 times per second, resulting in a duty cycle of 0.75% for each bridge. This low duty cycle significantly reduces the power consumption of the strain gauge and is the first reason that the transmit detector 12 can be driven with a standard 9 volt battery for 20 to 25 hours.

Since each bridge is switched or sampled 50 times per second, this sampling rate limits the maximum frequency response of the communication system. Theoretically, the maximum sine curve frequency that can be reproduced from sample data is less than half the sampling rate. In this case, the maximum frequency response is below 25 hertz. For practical reasons, the practical maximum frequency is around 20 Hertz. Sampling techniques significantly reduce power consumption, but at the same time limit frequency response. The sampling rate in this embodiment is one example, and it is possible to increase the sampling rate and increase the practical maximum frequency depending on the application.

The outputs of the above eight bridges, that is, the reference signal generators 28 ₁ , 28 ₂ and the transducers 10 ₁ , 10 ₂ , 10 ₃ ... 10 _n are input to the summing amplifier 30. This adds the bridge outputs and amplifies the summed signal by a factor of 100. Since the output voltage of the bridge is 0 volt except when the bridge is on, only the output of the bridge that is on is amplified. The salient output waveform from the amplifier is shown at the output of summing amplifier 30 in FIG. Each pulse matches the output from a particular channel and its pulse amplitude is indicative of the output voltage of a particular bridge. The duration of each pulse is 150 microseconds and the pulse interval is 2.5 milliseconds.

The output side of the summing amplifier 30 is connected to the sample hold circuit 32. The purpose of the sample and hold circuit 32 is to maintain or hold its pulse level until the next pulse arrives from the amplifier 30. The reason for doing this is to keep the voltage level of the single channel as long as possible, so that the voltage / frequency converter 34 is operated at a specific frequency as long as possible.

The sample hold circuit 32 is controlled by the pulse from the one-shot multivibrator 20. When the control signal is high level, the output of the sample and hold circuit 32 follows the input signal from the amplifier 30. When the control signal is low level, the output of the sample hold circuit 32 is stored or held at the final value when the control signal shifts to low level. The control signal is the channel driver 26  1, 26₂, 26₃…… 26_mHigh level only when is on. The output of the sample-hold circuit 32 becomes a pulse amplitude modulation (PAM) signal, and the six transducers 10₁10,₂10,₃...... 10_n(Channel driver 26₃~ 26₈ ) And a reference signal generator 28 for generating two maximum / minimum pulse levels₁, 28₂(Channel driver 26₁, 26₂) Contains the signal from.

The pulse amplitude modulation signal from the sample hold circuit 32 is used as an input signal to the voltage / frequency converter (VFC) 34. A voltage to frequency converter (V FC) 34 produces time-fixed pulses, the frequency of these pulses being controlled by the PAM signal from the sample-hold circuit. VFC output frequency range is 7. 5 to 22.5 kHz. The maximum pulse level from channel driver 26 ₁ produces a VFC output of 7.5 kHz and the minimum pulse level from channel driver 26 ₂ produces an output of 22.5 kHz. The transmission detector 12 thus constitutes the time division multiplexing PAM / FM system.

An LED 36 for inputting a continuous pulse from the VFC is provided so that an optical pulse is generated every time the VFC generates an electric pulse. The optical pulse from the LE D36 is supplied to the optical fiber cable 16 used for transmission to the reception measurement unit 14.

Next, the configuration of the reception measurement unit 14 will be described with reference to FIG. The reception / measurement unit 14 includes a photodiode 38, and receives the frequency-converted optical signal input from the transmission detection unit 12 via the optical fiber cable 14 to generate a minute current. A pulse amplifier 40 is connected to the photodiode 38, which converts the input current pulse into a voltage pulse and amplifies it. Since the optical pulse does not have the clear digital pulse waveform required for the subsequent circuit, the amplified pulse is converted into a good-quality digital signal pulse by the built-in pulse shaper circuit. The output of the amplifier 40 and the shaper processed is the same as the output of the VFC 34 in the transmission detector 12.

Next, the frequency-modulated pulse train that has passed through the amplifier 40 and the shaper processing is then output to the frequency / voltage converter (FVC) 42, where it is restored to the basic PAM voltage waveform. The PAM signal at this point in the reception measurement unit 14 is the same as the PAM signal as the output of the sample hold circuit 32 in the transmission detection unit 12. The FVC42 is a digital phase-locked loop (PLL) that immediately changes the step at the input frequency. The VFC 34 in the transmission detector 12 instantaneously changes the step with the input voltage. However, in the FVC 42 in the reception measurement unit 14, a step change in the input frequency causes a slight response delay.

In order to distinguish each independent signal in the PAM signal, it is necessary to detect the first channel pulse. This is done in the tuning demodulator 44. The maximum and minimum pulses in the PAM signal are associated with the channel drivers 10 ₁ and 10 ₂ and the tuned demodulator 44 detects the change between these two pulse levels. The tuned demodulator 44 produces one pulse each time the pulse changes from a maximum value to a minimum value. The signal level of the PAM signal is controlled by the transmission detector 12, and the signal amplitude from the channels 3 to 8 becomes smaller than the amplitude of the channels 1 and 2. The tuning pulse frequency is 50 Hz, which matches the sampling rate in the transmission detector 12.

The pulse from the tuning demodulator 44 is input to the second phase lock loop (second PLL) 46. This PLL is not used as an FVC, but it only generates a clock signal or pulse signal that is eight times the frequency of the tuning pulse. This clock frequency is 400 Hz, which is the same as the clock frequency in the transmission detector 12. Both tuning and clock frequencies are derived from the received PAM signal.

A decommutator 46 for inputting three types of signals is also provided. The three types of signals are a PAM signal, a tuning signal and a clock signal. In the decommutator 46, the PAM voltage level is extracted at the time specified by the clock pulse. Also, each independent channel signal is controlled by a tuning pulse and sent to the correct output point. This results in eight output voltages that match the eight PAM signal levels.

[0032] To obtain an output voltage in succession for each channel, the sample-and-hold circuit 4 8 _1, 48 _2, 48 ₃ ...... 48 ₈ are provided, which are connected to the eight de commutation data output pin .. Each sample and hold circuit 48 ₁ , 48 ₂ , 48 ₃ ... 48 ₈ maintains a constant output voltage until the decommutator 46 generates a new voltage level for the corresponding channel. Since the sampling rate in the transmission detector 12 is 50 Hz, the output voltage in each of the sample and hold circuits 48 ₁ , 48 ₂ , 48 ₃ ... 48 ₈ is updated 50 times per second.

In addition to such a configuration, the multi-channel optical communication device of the embodiment includes an on / off control means for the transmission detector 12. This on / off control means is provided with a phototransistor 52 interposed in a battery driving circuit 50 as shown in the transmission detecting section 12 portion of FIG. 4, and connects the phototransistor 52 to the reception measuring section 14 and the transmission detecting section 12. It is assumed that it is operated by the optical signal supplied from the second optical fiber cable 54. The phototransistor 52 is connected in series with the battery 56 and operates as a simple switch. When the optical signal supplied from the reception measurement unit 14 is switched off, the phototransistor 52 becomes an open circuit, and the transmission detection unit 12 is switched off. Therefore, the transmission detection unit 12 is switched on / off by the reception measurement unit 14, and therefore, the life of the battery 56 of the transmission detection unit 12 is the maximum when the transmission detection unit 12 is in the non-driving state. can do. When the phototransistor 52 receives light, a current flows, and a voltage drop of about 0.2 volt occurs.

In addition, the device is provided with a battery check circuit of the transmission detector 12. This is because the battery voltage of the transmission detection unit 12 is indirectly measured by the reception measurement unit 14, and as shown in FIG. 4, it is connected in parallel with the transmission detection unit 12 in the battery drive circuit 50. The capacitor 58 is provided. The capacitor 58 has a capacity of about 400 microfarads and stabilizes the direct current supplied to the transmission detector 12. Since the capacitor 58 has a relatively large capacity, it should supply a voltage for operating and driving the transmission detection units 12 connected in parallel for a short time after the phototransistor 52 is switched off. You can The transmission detection unit 12 is normally driven by a battery voltage between 9 V and approximately 6.8 V, and below this voltage the drive of the transmission detection unit 12 is stopped and the reception measurement unit 14 cannot receive any signal. ..

In order to determine the approximate battery voltage, the time from the time when the phototransistor 52 is turned off in the reception measurement unit 14 to the time when the signal of the transmission detection unit 12 disappears in the reception measurement unit 14 is received. The measuring unit 14 measures. When using a new battery, this measurement time is about 60 milliseconds (when the capacitor capacity is 470 microfarads). Battery voltage drops, 7. This time interval decreases until it reaches a battery voltage of 0 Volts (taking into account the 0.2 Volt voltage drop across the phototransistor 52), and eventually the time interval becomes 0. By utilizing this, the battery voltage and its life can be determined without providing an additional circuit in the transmission detector 12.

A specific configuration of this battery check circuit will be described with reference to FIG. The battery check circuit 60 uses the usable voltage as a judgment criterion as an index of the remaining battery life. To apply this circuit, an alkaline battery or the like whose battery voltage decreases by discharging can be used as a battery power source. Batteries that maintain a constant voltage during their useful life cannot be measured by this circuit configuration.

The battery check circuit 60 indirectly measures the battery voltage, and the basic concept can be understood from the graph shown in FIG. That is, the capacitor 58 connected in parallel to the transmission detection unit 12 in the battery drive circuit 50 assists in stably supplying DC power to the transmission detection unit 12. The energy stored in the capacitor 58 causes the transmission detector 12 to continue operating for a while after the phototransistor 52 interposed in the drive circuit 50 is switched off. As shown in the graph of FIG. 5, even if the phototransistor 52 is turned off at time t ₀ , the transmission detection unit 12 is reduced to the cutoff voltage of the transmission detection unit 12 by the discharge of the capacitor 58, which is about 6.8 volts. The operation is continued until it is reached. With this voltage, the transmission detector 12 stops the generation of the optical signal. The discharge time Δt depends on the initial voltage from the capacitor. With a new battery, the discharge time will be maximum, and it will be about 60 milliseconds depending on the capacity of the capacitor. As the battery nears its end of life and its output voltage drops to approximately 7 volts, the discharge time is zero. Therefore, the life of the battery 56 can be determined by measuring the discharge time Δt.

The discharge time Δt is measured by the circuit configuration of the reception measuring unit 14 side shown in FIG. The phototransistor 52 on the transmission detector 12 side is turned off by turning off the semiconductor laser 62 including the LED 36 of the reception measurement unit 14. The semiconductor laser 62 outputs an optical signal to the phototransistor 52. The battery check circuit 60 detects the disappearance of the measurement signal from the transmission measurement unit 12 from the time when the battery check button 64 provided on the power source side of the semiconductor laser 62 is pressed, and the time when the reception measurement unit 12 detects it. The elapsed time until is mainly measured.

Therefore, the battery check circuit 60 includes a retrigger type one-shot multivibrator 66 that takes in the output signal of the pulse amplifier 40 that is a signal input unit from the transmission measurement unit 12. The output from the re-trigger one-shot multivibrator 66 maintains a high level while receiving the optical pulse signal from the transmission measurement unit 12. Since the output time of this one-shot multivibrator 66 is only a little longer than the maximum trigger time interval due to the input optical pulse signal, the output of the oneshot multivibrator 66 will drop immediately after the disappearance of the input pulse signal. ..

An exclusive OR circuit (xor) 68 is provided on the output side of the one-shot multivibrator 66, and at the same time, the signal from the battery check button 64 is also inputted. By inputting both signals to the exclusive OR circuit (xor) 68, the output of the exclusive OR circuit 68 becomes high level during the Δt time which is the measurement target.

The time interval ΔT can be displayed by various methods. How shown in FIG. 4, it is assumed that turns on the four light-emitting diodes 70 _1-7 0 ₄ corresponding to the simple approximate battery voltage. When all four light emitting diodes are lit when the battery check button 64 is pressed, it indicates that the battery 56 has the maximum voltage, and when one light emitting diode is lit, the battery 56 has a long life. I try to show that it is near the end of my life.

This is realized by providing _four one-shot multi-vibrators 72 _{1 to} 72 ₄ which are simultaneously activated when the battery check button 64 is pressed. Oscillation time of one-shot multivibrator 72 _{1-72 4} that is changed to be stepwise increased between 60 milliseconds approximately 10 milliseconds. These one-shot multivibrator 72 _{1-72 4} each correspond to the light emitting diodes 70 ₁ to 70 ₄ are connected so as to start them, 4-channel latch circuit 74 is provided in the middle, A pulse signal corresponding to the measurement time Δt output from the exclusive OR circuit 68 is input to the circuit 74 as a timing signal pulse. This four pulse signals from the one-shot multivibrator over data 72 ₁ to 72 _4, the timing signal pulses from the exclusive-OR circuit 68, passes through the four channels latch circuit 74, the corresponding light-emitting diodes 70 ₁ 70 ₄ to light the. When the timing the pulse width is longer than the pulse width from one-shot multivibrator 72 _{1-72 4} is operated on-emitting diodes 70 ₁ to 70 ₄ are jointly in one-shot multivibrator 72 _{1-72 4} It When the timing pulse is longer than all four of the one-shot multivibrator 72 _{1-72 4} pulses, four light emitting diodes 70 ₁ to 70 ₄ is turned all. If the timing pulse is only longer than the shortest one-shot pulse, then only one light emitting diode 70 ₁ is illuminated. This makes it possible to easily determine the battery life on the receiving and measuring unit 14 side.

It should be noted that the battery check circuit 60 as described above is changeable, and therefore the light emitting diode may be turned on only when the battery check button 64 is pressed.

With such a configuration, the measurement data from the plurality of transducers can be remotely detected, and this is transmitted to the measurement section side by the optical fiber cable. Insulation is ensured and electrical noise can be prevented from entering. In particular, the battery 56 is used as the power supply of the transmission detection unit 12, but since it has a low power consumption circuit, it can be used for a long time, and the power on / off operation on the detection side and the voltage of the battery 56 can be performed remotely. A check function can be added. Therefore, there is an effect that remote measurement can be performed especially for a system in which a high voltage exists, and it can be applied to an inspection device for distribution lines, a force sensor of a manipulator, and the like.

[0045]

[Effect of the device]

 As described above, according to the present invention, the measurement signal from a plurality of transducers is input, and the measurement pulse signal is switched and output through the multiplexer by the counter reference pulse generating means and the measurement pulse signal is added. And a sample-hold circuit converts the pulse-amplitude-modulated signal into a frequency-converted signal and outputs the frequency-converted signal to a battery-powered transmission detection unit, which is linked to this transmission detection unit via an optical fiber. And a reception measurement unit capable of outputting a measurement signal corresponding to the plurality of transducer signals via a decommutator by restoring the frequency conversion signal input as a pulse amplitude modulation signal by a voltage converter, An optical signal supplied to the battery drive circuit of the transmission detector via the optical fiber path from the reception measurement unit. Since a switching element that can be opened and closed more and a capacitor connected in parallel with the transmission detector are provided, it is possible for a measurement operator in a system with high voltage to perform remote measurement without approaching the high voltage region, and to provide electrical insulation. The result is that the measurement signal can be transmitted without being affected by electrical noise.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a multi-channel optical communication device according to an embodiment.

FIG. 2 is a circuit configuration diagram of a transmission detector of the device.

FIG. 3 is a circuit configuration diagram of a reception measurement unit of the device.

FIG. 4 is a configuration diagram of a battery drive circuit and a check circuit of a transmission detection unit.

FIG. 5 is an explanatory diagram of a battery check operation.

[Explanation of symbols]

10 ₁ , 10 ₂ , 10 ₃ ...... 10 _n Transducer 12 Transmission detection unit 14 Reception measurement unit 16 Optical fiber cable 18 Clock 20 One-shot multivibrator 22 Counter 24 Multiplexer 26 ₁ , 26 ₂ , 26 ₃ ... 26 _m Channel driver 28 ₁ , 28 ₂ Reference signal generator 30 Summing amplifier 32 Sample and hold circuit 34 Voltage / frequency converter (VFC) 36 LED 38 Photodiode 40 Pulse amplifier 42 Frequency / voltage converter (FVC) 44 Tuning demodulator 46 Decommutator 48 ₁ , 48 _2, 48 ₃ ...... 48 ₈ sample and hold circuit 50 battery circuit 52 phototransistor 54 second optical fiber cable 56 battery 58 capacitor 60 battery check circuit 62 semiconductor laser 64 Batterichi Kkubotan 66 re-triggered one-shot multivibrator 68 exclusive OR circuits 70 ₁ to 70 ₄ emitting diodes 72 ₁ to 72 ₄ one-shot multivibrator 74 4-channel latch circuit

Claims (1)

[Scope of utility model registration request] 1. A measurement signal from a plurality of transducers is input, the measurement pulse signal is switched and output through a multiplexer by a counter reference pulse generating means, and the measurement pulse signal is added to a pulse amplitude modulation signal by an adder and a sample hold circuit. A battery-powered transmission detector that converts the frequency to
The transmission detector is linked by an optical fiber, and the frequency-converted signal input via this optical fiber is restored to a pulse-amplitude modulated signal by a voltage converter, which corresponds to the plurality of transducer signals via a decommutator. A reception measuring unit capable of outputting a measurement signal, and a battery driving circuit of the transmission detecting unit, a switching element opened and closed by an optical signal supplied from the reception measuring unit through an optical fiber path, and a transmission detecting unit. A multi-channel optical communication device comprising a capacitor connected in parallel with the device.