JP3072337B2 - Optical wiring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optical wiring system for transmitting signals between points.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional optical wiring system. In the figure, 29 is a digital signal input terminal,
Reference numeral 30 denotes a differential light emitting element driving circuit, 31-1 and 31-2 light emitting elements, 32-1 and 32-2 optical transmission paths, and 33-1 and 32-1.
33-2 is a light receiving element, 34 is a light receiving element 33-1, 33-
An adder circuit for differentially adding the outputs of 2; 35, an amplifier;
36 is an identification circuit, 37 is a digital signal output terminal, 38 is a clock or control signal input terminal, 39 is a light emitting element drive circuit, 40 is a light emitting element, 41 is an optical transmission line, 42 is a light receiving element, 43 is an amplifier, and 44 is an amplifier. Clock or control signal.

A digital value (0, 1) input from a signal input terminal 29 is sent to a light emitting element driving circuit 30 of differential output. Two outputs of this drive circuit are connected to light emitting elements 31-1, 31-2, respectively. With such a configuration, when the digital value “1” is input from the signal input terminal 29, only the light emitting element 31-1 emits light, and when the digital value “0” is input, the light emitting element 31- Only 2 will emit light. The output signal lights of the two light emitting elements are respectively guided to optical transmission lines 32-1 and 32-2 such as optical fibers or spatial wirings, and are guided to light receiving elements 33-32.
1, 33-2.

In the adder circuit 34, the light receiving current of the light receiving element 33-1 generates a positive voltage, and the output current of the light receiving element 33-2 generates a negative voltage, and they are added to each other. Therefore, the output of the adder circuit 34 outputs a positive voltage if the input digital value is "1", and outputs a negative voltage if the input digital value is "0". The output of the adder circuit 34 is amplified by an amplifier 35, converted into a digital value by an identification circuit 36, and then output from an output terminal 37. In the optical wiring having the configuration as shown in FIG. 1 described below, bipolar code transmission can be equivalently realized, and the digital value “0” is input at the input of the amplifier 35.
And the potential difference at the time of "1" can be doubled as compared with the case of the unipolar code transmission, and the optimum threshold value always takes a constant value.
There is an advantage that transmission characteristic deterioration due to a change in the light receiving level is reduced. Also, in normal digital optical transmission, a clock signal for designating an identification timing is required when a received digital signal is identified.Furthermore, in wiring between digital circuits, a clock having the same phase as the signal is used. Need to be supplied to the digital circuit. FIG.
The transmission of these clock signals is conventionally performed by a clock recovery circuit that extracts the clock component from the received digital signal, or a separate clock signal transmission circuit separate from the digital signal transmission is used for clock transmission. This is done using the wiring of FIG.

[0005]

In the conventional optical wiring system described above, When a clock recovery circuit is used, a code conversion operation is required to make the transmission signal always have a clock component irrespective of the input digital signal, and there has been a problem that the entire transmission circuit becomes complicated. Further, as shown in FIG. 5, it is necessary to newly provide a light emitting element, a light receiving element, and an optical transmission line for clock transmission. In signal transmission between electronic circuits, a digital signal is controlled on a bit basis, that is, for example, when a packetized data signal is identified at the head position of a packet or when switching control is performed for each packet. However, even in such a case, it is necessary to arrange the control signals in a digital signal in a time series and then transmit them, or to provide a new wiring system for transmitting the control signals. Therefore, the present invention provides an optical wiring for performing wiring between digital electronic circuits by optical differential transmission,
By transmitting a clock signal or a control signal simultaneously with a digital signal, a clock signal or a control signal can be transmitted with a simple configuration without newly providing a light emitting element, a light receiving element, and an optical transmission line. I do.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an optical wiring in which wiring between digital electronic circuits is performed by light, in which two light emitting channels and two light receiving channels are provided, respectively, and an input digital signal The digital signal is modulated by switching the light-emitting channel to emit light according to the value, and a clock signal or a control signal is superimposed on the modulated signal for each light-emitting channel and transmitted. To demodulate a clock signal or a control signal, and obtain a difference to demodulate a digital signal. That is, the optical transmission circuit has two light emitting channels.
Binary digital input to the device
Two light emission channels depend on the value of the signal.
For modulating only one of the emission channels
And each of the signals modulated by the two emission channels
Means for superimposing a clock signal or a control signal on the
Each means provided in the optical transmission circuit has two
Light emitting channels for each of the current switches
The light-emitting elements that make up the
The clock signal between the light emitting element and the transistor
Or transistors for superimposing control signals
Are connected to each other, and the receiving circuit includes two light receiving chips.
Light receiving of two receiving channels
Means for outputting the sum of the signals,
Means for outputting the difference between the optical signals,
Each of the emission channel and the reception channel is connected
It is configured to be In addition, the optical receiving circuit
Two light receiving channels are two light receiving elements connected in series
And two light receiving elements connected in parallel.
And the optical transmission path is one of two emission channels
Output signal of one of two light receiving elements connected in series and
When coupled to one of two light receiving elements connected in parallel
The output signal of the other of the two emission channels is
The other of the two light receiving elements connected in series and
Is configured to be coupled to the other of the two light receiving elements
Things.

[0007]

Therefore, the digital signal transmitted between the digital electronic circuits is transmitted in a bipolar code format having excellent environmental resistance, and a clock signal or a control signal can be transmitted without providing a new wiring.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is a clock signal or control signal input terminal, 2 is a data signal input terminal, 3 is an inverter that digitally inverts from “1” to “0” or “0” to “1”, 4, 5 Is an addition circuit for adding two input signals in an analog manner, 6-1 and 6-2 are electro-optical conversion circuits including light emitting elements, and 7-1 and 7-2 are optical transmissions using optical waveguides or spatial wiring. Path, 8-1 and 8-2 are optical-electrical conversion circuits including light receiving elements, 9 is an addition circuit that adds two inputs in an analog manner, 10 is a circuit that outputs the difference between the two inputs,
11, a clock output terminal; and 12, a data signal output terminal.

A data signal input from a terminal 2 is branched into two, one of which passes through an inverter 3 and an addition circuit 4.
The other is superimposed on the clock signal or the control signal by the adding circuit 5 as it is, and the light-emitting channel 6-
1, 6-2 are output as optical signals. The optical transmission line guides these two optical signals to the light receiving channels 8-1 and 8-2. These two signals are received by the light receiving channels 8-1, 8-
The signals are converted into electric signals at 2, and sums and differences are obtained in analog manner in addition circuits 9 and 10, and output from output terminals 11 and 12.

FIG. 2 shows signals in each part of a device to which the optical wiring system of FIG. 1 is applied in a time series.
In the figure, reference numeral 13 denotes a clock signal or a control signal, 1
4 is a data signal, 15 is a data signal after passing through the inverter 3, 16 is a clock signal or a signal obtained by adding the control signal 13 and the data signal 15 and output from the light-emitting channel 6-2, and 17 is a clock signal or control signal. 13 is added to the data signal 15 and the signal is output from the light-emitting channel 6-1; 18 is a demodulated clock signal or control signal; and 19 is a demodulated data signal.

If the optical connection system as shown in FIG. 1 is used, the reproduced data signal 19 is transmitted by bipolar code as shown in FIG. 2, and the optimum threshold value for identifying the digital data signal can be kept constant. . The reproduced clock signal 18 is a pulse train including a DC component. By using the clock signal 18 and the optimum threshold “0” for bipolar code transmission shown in the drawing, it is possible to easily distinguish between “0” and “1” of the data signal. By the way, since the clock signal 18 is a signal which is always turned ON / OFF at a constant cycle, its average amplitude fluctuates only due to the fluctuation of the loss factor occurring in the wiring section. Therefore, the recovered clock signal 18
Can be used as a feedback output for gain control of the optical receiving circuit.

Further, the configuration shown in FIG. 1 has an advantage that the clock signal is always transmitted irrespective of the digital signal, so that a clock recovery circuit and a code conversion circuit are not required and the transmission / reception circuit can be simplified. When a control signal is superimposed instead of a clock signal, transmission is performed while the phase relationship between the control signal and the data signal is kept constant, so that bit-by-bit control can be easily realized.
As described above, in this embodiment, by using optical differential transmission, it is possible to transmit a clock signal or a control signal with a simple configuration without using a new wiring system.

FIG. 3 is a block diagram showing a second embodiment of the present invention. FIG. 3 shows an optical transmission circuit. In FIG. 3, reference numerals 20-1 and 20-2 denote transistors for current switching, 21-1 and 21-2 denote transistors for superimposing a clock signal or a control signal, and 22-. 1, 22-2 are light emitting elements, 23-1, 23-2 are output optical signals, and 24 is a reference voltage.

The current switch constituted by the transistors 20-1 and 20-2 is connected to a voltage of the reference voltage 24 set between the data signal composed of the binary digital signal sequence and the voltage amplitude representing the binary digital value. The transistor having the larger voltage value is turned on, and a current flows. Therefore, when the input data is "1", the transistor 20-1 is turned on, and the light emitting element 22-
Current flows through 1 and an optical signal is transmitted. On the other hand, when the digital value of the input data signal is "0", the transistor 20-2 is turned on, a current flows through the light emitting element 22-2, and an optical signal is transmitted. The transistor 21-
Reference numerals 1 and 21-2 denote elements for superimposing a clock signal or a control signal on a data signal, and change a current flowing through the light emitting elements 22-1 and 22-2 according to the amplitude of the clock signal or the control signal. Thus, in the configuration shown in FIG. 3, the function of the light emitting unit can be realized with a simple circuit configuration.

FIG. 4 is a block diagram showing a third embodiment of the present invention. FIG. 4 shows a configuration of an optical receiving circuit. In FIG. 4, reference numerals 25-1 and 25-2 denote light receiving elements for receiving data signals, and reference numerals 26-1 and 26-2 denote light receiving elements for receiving a clock signal or a control signal. , 27 and 28 are amplifiers.

An optical signal 23-1 in which a clock signal or a control signal is superimposed on a data signal is received by light receiving elements 25-1 and 25-2.
6-1. The optical signal 23-2 in which the clock signal or the control signal is superimposed on the inverted data signal is
Coupled to light receiving elements 25-2 and 26-2. Light receiving element 2
5-1 and 25-2 are connected in series, and the output obtained from the midpoint is output via the amplifier 27. on the other hand,
The light receiving elements 26-1 and 26-2 are connected in parallel.
The sum of the light receiving currents of the two light receiving elements is amplified by the amplifier 28 and output. With this configuration, a bipolar-coded digital signal is obtained from the output of the amplifier 27, and a clock signal or a control signal is obtained from the output of the amplifier 28. Therefore, according to the configuration shown in FIG. 4, the sum or difference of the two light receiving signals can be output only by connecting the connection of the two light receiving elements in series or in parallel. It is possible to do.

[0017]

As described above, the present invention uses a transmission device having two systems, one system for transmitting a digital value "1" and the other system for transmitting a digital value "0". By using clock signals or control signals superimposed on both systems and transmitting them independently, both bipolar code transmission and clock or control signal transmission can be realized with a simple configuration without using new wiring in optical transmission. can do. By applying this bipolar code transmission, the allowable signal-to-noise ratio in digital transmission can be increased. In addition, there is an advantage that the threshold value for reproducing the digital signal can be kept constant without depending on the intensity of the received light signal, so that the apparatus can be simply configured. Also, by transmitting the data signal and the clock signal or control signal simultaneously,
As compared with the case where these signals are transmitted in time series, a clock recovery circuit, a code conversion circuit, and the like are not required, and the circuit configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus to which an optical wiring system according to the present invention is applied.

FIG. 2 is a waveform chart showing a signal form in each section of the device.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a block diagram of a device to which a conventional optical wiring system is applied.

[Explanation of symbols]

1 clock signal (or control signal)
Input terminal 2 Data signal input terminal 3 Inverter 4,5,9 Addition circuit 6-1, 6-2 Electric-optical conversion circuit 7-1,7-2 Optical transmission line 8-1,8-2 Optical-electric conversion circuit Reference Signs List 10 Circuit for outputting two input differences 11 Clock output terminal 12 Data signal output terminal 13, 18 Clock signal (or control signal) 14, 15, 19 Data signal 16, 17, 23-1, 23-2 Optical signal 20- 1,20-2,21-1,1-2-2 Transistors 22-1,22-2 Light emitting element 24 Reference voltage 25-1,25-2,26-1,26-2 Light receiving element 27,28 Amplifier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 10/00 H04L 25/02

Claims (2)

(57) [Claims] 1. An optical wiring system including an optical transmission circuit, an optical transmission line, and an optical reception circuit for transmitting a binary digital signal, wherein the optical transmission circuit is configured by two light-emitting channels and input to a device. Means for modulating only one of the two light-emitting channels according to the value of the binary digital signal; and a clock signal or a control signal for each of the signals modulated by the two light-emitting channels. And a means for superimposing , and each of the means provided in the optical transmission circuit is provided in each of the current switches including two transistors.
The light emitting elements constituting the light emitting channel are connected in a forward direction
Between the light emitting element and the transistor.
A clock for superimposing a clock signal or control signal
Njisuta is configured to be connected respectively, said receiving circuit is constituted by two light-receiving channel, and means for outputting the sum of light receiving signals of the two receiving channels, the difference of light reception signals of the two light-receiving channel and means for outputting said optical transmission line optical wiring system, characterized in that configured so that the coupling each of the two light emitting channel and receiver channel. 2. The light receiving circuit according to claim 1, wherein two light receiving channels of the light receiving circuit are connected in series.
Two light receiving elements and two light receiving elements connected in parallel
Therefore, each of the optical transmission lines is configured so that one of the two light emission channels is provided.
Output signal of one of the two light receiving elements connected in series is
And one of the two light receiving elements connected in parallel
And the other of the two emission channels
One of the two light receiving elements connected in series
And the other of the two light receiving elements connected in parallel
An optical wiring system characterized by being configured so as to be structured as follows.