JPH09261174A - Optical parallel transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively satisfy the safe standard of laser beams by transmitting the parallel data in parallel after encoding them into the data having approximately the same rate between '0' and '1' and then converting these data into electric signals. SOLUTION: An encoding circuit 1 encodes an input electric signal of 8 bits, for example, into an electric signal of 10 bits having the same number between '0' and '1'. The electric signals which are encoded by the circuit 1 are inputted to an electricity/light conversion circuit 2 and turned into 10 pieces of optical signals. Then these optical signals are inputted to a light/ electricity conversion circuit 3 of the receiver side via a tape fiber 6 consisting of a set of 10 pieces of optical fiber cables 5. The circuit 3 converts the received optical signals into the electric signals of 10 bits and then decodes them into the original signals of 8 bits in a procedure adverse to the encoding procedure of the circuit 2 via a decoding circuit 4 that is connected to the circuit 3. In such a transmitting way of optical signals, the laser beams radiated from the fiber 6 are limited to 5 pieces at most and less than conventional 8 pieces even if the fiber 6 is cut by mistake.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical parallel transmission system, and more particularly to an optical parallel transmission system using a laser diode (LD) as a light source.

[0002]

2. Description of the Related Art Conventionally, in such an optical parallel transmission system, a plurality of data are simultaneously transferred in parallel in parallel by using a light source such as a laser diode (LD). In such a case, for example, when the optical fiber cable is cut, there is a risk that the laser light may be irradiated to the human eyes. Therefore, some measures should be taken according to the laser light safety standard for the optical fiber cable structure, the connector, the LSI, and the like. Need to

However, in this type of conventional optical parallel transmission system, in order to minimize skew, which is variation in delay between signals, a plurality of optical fiber cables such as tape fibers are grouped together. Since it is common to transmit signals through a transmission cable having the structure described above, the danger when the transmission cable is cut tends to worsen from the viewpoint of laser light safety standards.

In order to avoid such a risk, a method of detecting the disconnection of the optical fiber cable and stopping the output of the laser light has been considered, but such a method is performed by the optical fiber cable. This can be realized only in the case of a configuration for performing parallel transmission, and at present, such a structure of the optical fiber cable of the optical parallel transmission system is not general.

[0005]

The above-mentioned conventional optical parallel transmission system has a problem that a considerable cost is required to realize a structure in which the optical fiber cable is not cut. In addition, a single transmission cable is not necessary, and since there are multiple connection points inside the housing, etc., it is necessary to realize a structure that does not easily come off even at this connection part. There is also the problem of becoming expensive.

Further, in the above-mentioned conventional optical parallel transmission system, for example, basically, a bidirectional optical fiber cable must be provided in order to determine that the optical fiber cable has been cut. There is a problem that it cannot be realized by the structure of the transmission type optical fiber cable.

It should be noted that, for example, Japanese Patent Application Laid-Open Nos. 4-90635 and 2-177626 propose an optical transmitter in which light emission of a laser diode is stopped when the plug side of an optical connector is pulled out. However, such an optical transmitter cannot effectively deal with the case where the optical cable itself is cut.

Therefore, the present invention has been made in view of the above problems, and by devising the optical signal output method, the structural design, the cable structure, the connection structure, etc. can be achieved while satisfying the laser light safety standard. An object of the present invention is to provide an optical parallel transmission system that can be simplified and realized at low cost.

[0009]

To achieve the above object, the present invention provides an optical parallel transmission system for converting a plurality of data into a plurality of optical signals and transferring them in parallel in a synchronous manner. Characterized by encoding the data so that the ratio of "0" and "1" is approximately the same, and then converting the encoded data into an optical signal and outputting the optical signal to an optical fiber cable. An optical parallel transmission system is provided.

Further, according to the present invention, in an optical parallel transmission system for converting a plurality of data into a plurality of optical signals and transferring them in parallel in a synchronous manner, a plurality of optical fiber cables for transmitting the plurality of optical signals are bundled with each other. And make the structure into one,
Among the plurality of optical fiber cables having the structure, ones having different optical signal transmission directions are included so that the ratios of the optical fiber cables having different optical signal transmission directions are substantially the same. An optical parallel transmission method is provided.

Next, the principle or operation of the present invention will be described.

In the optical parallel transmission system in which a plurality of data are simultaneously transferred in parallel in a synchronous manner, what kind of data is output on the optical fiber cable, which is an optical transmission line, depends on the situation. For example, when a laser diode (LD) is used as a light source, the output of laser light is kept at a certain level in order to prevent human eye damage due to light leaking from an optical fiber cable in accordance with a safety standard assuming that laser light leaks. Need to be kept to.

Here, considering the case where the output signal is transferred in parallel by the eight optical fiber cables, the laser light is output without adding any special circuit as in the conventional case, and the output is caused for some reason during the output. When the operation is stopped and the laser beam continues to be output, and if the optical fiber cable is cut in this state, the worst 8 laser beams are emitted. If the output of 8 laser beams exceeds the safety standard (there is a very high possibility), the fiber optic cable should not be cut or the laser beam output should not exceed the standard. It is necessary to take either of these measures, but both measures are costly and technically difficult.

Therefore, according to the first optical parallel transmission system of the present invention, when a plurality of data are simultaneously transferred in parallel in a synchronous manner, a plurality of data are encoded by an encoding circuit and are simultaneously output. By making the ratio of “0” and “1” of the data almost the same (50% each) and converting the output signal to an optical signal and outputting it to a tape fiber or a bundle of a plurality of optical fiber cables, The intensity of laser light when the cable is cut is reduced to about half.

The encoding circuit for making the ratio of "0" and "1" of the parallel data approximately half and half is realized by a circuit configuration for converting an 8-bit signal into a 10-bit signal according to a predetermined conversion rule. can do. That is, 8
The binary pattern represented by the bit signal is 25
There are 6 types, but 1 represented by a 10-bit signal
Of the 024 patterns, there are 276 patterns in which "0" and "1" are half and half. Therefore, by associating the two according to a predetermined conversion rule, all of the 8-bit signals are converted into 10-bit signals. It can be expressed by a signal of a pattern in which “0” and “1” are half and half in the pattern. As a method for realizing such a conversion, for example, the well-known 8B10B conversion or 4B5B conversion can be adopted, but the principle is not limited to these conversion methods Various conversion methods can be adopted.

By such conversion, for example, in the case of an 8-bit signal, the signal is increased by 2 bits by encoding to 1
It is necessary to transfer a 0-bit signal, but only 5 bits of the 10-bit signal can be "1" at the same time, so the original 8-bit signal before encoding is "1" at the same time. The output of laser light is 37
It will be possible to reduce it by%, and a sufficient effect can be expected. It should be noted that such a conversion can be similarly applied when the signal before encoding is less than 8 bits.
Even when the number of signals before encoding is more than 8 bits, a similar effect can be expected by adding a signal for a predetermined number of bits or increasing the number of bits with 8 bits as one unit. be able to.

Further, according to the second optical parallel transmission system of the present invention, when the optical fiber cable is cut, the laser light emitted from the cut surface (optical fiber end surface) is halved on one side. When optical signals are transmitted in a bundled optical fiber cable in both directions, the number of optical signals transmitted in one direction is almost the same as the number of optical signals transmitted in the opposite direction (equal number , Or the difference between them is set to 1), so that the emission of the laser light is reduced to about half.

Thus, according to the optical parallel transmission system of the present invention, as will be described later, it is possible to satisfy the laser light safety standard by a method which is relatively inexpensive.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the first embodiment of the present invention uses a laser diode (LD) as a light source,
In an optical parallel transmission system that transmits more than four optical signals (e.g., 8) in parallel and outputs a plurality of data (e.g., 8 bits) synchronously, an input 8-bit electric signal is encoded. 1 is encoded into a 10-bit electric signal in which the ratio of “0” and “1” is approximately the same, and the encoded 1
The 0-bit electric signal is converted into 10 optical signals by the electric / optical conversion circuit 2, and the converted 10 optical signals are converted into 1
It is output to a 10-fiber tape fiber 6 having a structure in which 0 optical fiber cables 5 are bundled.

If the number of signals output from the encoding circuit 1 is an even number, half of the output signals are set to "0" and the remaining half are set to "1", while the encoding circuit 1 is set. If the number of signals output from is an odd number, the number of signals of "0" is one more than that of "1", or the number of signals of "1" is one more than that of "0". Good.
It is most desirable that the number of "0" s and "1" s differ by at most one, but it is also possible to adopt a configuration in which the number of "0s" and "1s" differ by two depending on the number of bits transmitted. Is.

Then, 10 encoded in this way
The optical signal of the book is transferred to the receiving side via the optical fiber cable 5, converted into an electric signal by the optical / electrical converting circuit 3 on the receiving side, and then the decoding circuit 4 corresponding to the encoding circuit 1
To decode it to the original 8-bit electric signal.

Next, referring to FIG. 3, the second embodiment of the present invention uses a laser diode (LD) as a light source, and more than four laser diodes as in the first embodiment of the present invention. In an optical parallel transmission system for transmitting optical signals (for example, 4 lines) in parallel and outputting a plurality of data (for example, 4 bits) in synchronization, more than four optical fiber cables 5 for transmitting optical signals are provided. When the optical signals are bidirectionally transmitted by such at least two tape fibers 12, 12 ', the tape fibers 12, 12' are bundled together to form a structure like the tape fiber 12.
2 by the optical connectors 13, 13 'connected to the ends of
The optical fiber cables 5, 5'in one tape fiber 12, 12 'are replaced, and some of the optical fiber cables 5, 5'in the tape fiber 12, 12' have different optical signal transmission directions. The number of optical signals in the opposite direction is set to be the same as or more than that of the optical signal in one direction.

The second embodiment of the present invention as described above is combined with the above-described first embodiment of the present invention to input to the optical fiber cables 5, 5'in the tape fibers 12, 12 '. The encoded 4-bit electric signal is converted into 5 by the encoding circuits 8 and 8'where the ratio of "0" and "1" is approximately the same.
It is encoded into a bit electric signal, and the encoded 5-bit electric signal is converted into five optical signals by the electric / optical conversion circuits 9 and 9 ', and then the tape fibers 12 and 1
The optical fiber cables 5, 5'in the two tape fibers 12, 12 'may be replaced by the optical connectors 13, 13' connected to the ends of the 2 '.

[0025]

EXAMPLES Next, the above-described embodiment of the present invention will be described more specifically with reference to Examples.

[0026]

First Embodiment First, a first embodiment of the optical parallel transmission system of the present invention will be described. 1 is a block diagram showing a configuration of an optical parallel transmission system according to a first exemplary embodiment of the present invention.

Referring to FIG. 1, the optical parallel transmission system according to the first embodiment of the present invention includes a coding circuit 1 for coding an 8-bit electric signal and outputting a 10-bit electric signal.
1 bit of a 10-bit electric signal output from the encoding circuit 1
An electrical / optical conversion circuit 2 for converting 0 optical signals, an optical / electrical conversion circuit 3 for converting 10 optical signals into 10-bit electrical signals, and an 8-bit electrical / decoding circuit for decoding 10-bit electrical signals. A decoding circuit 4 for outputting an electric signal, 10 optical fiber cables 5 for transmitting an optical signal, and a 10-core tape fiber 6 having a structure in which 10 optical fiber cables are bundled are provided.

The encoding circuit 1 encodes the input 8-bit electric signal into a 10-bit electric signal having the same number of "0" and "1". In addition, according to the above-mentioned principle, if 10-bit output is set for 8-bit input, the ratio of “0” and “1” of output data to all input data should be half. Various encodings are possible.

An electric signal of 10 bits, which is encoded by the encoding circuit 1 and is composed of "0" and "1", is input to the electrical / optical conversion circuit 2 and converted into 10 optical signals. The converted 10 optical signals are input to the optical / electrical conversion circuit 3 on the receiving side via the tape fiber 6 which is a set of 10 optical fiber cables 5.

The optical / electrical conversion circuit 3 on the receiving side converts 10 optical signals into 10-bit electric signals, and then the decoding circuit 4 connected thereto reverses the encoding procedure in the encoding circuit 2. The procedure is to decode the original 8-bit electrical signal.

By transmitting the optical signal in this way, even if the tape fiber 6 is cut for some reason, the laser light emitted from the end face of the cut tape fiber 6 is 10 optical fiber cables. Only half of the five laser beams are emitted, and even if accidentally emitted to the human eye, only a maximum of five laser beams are emitted. Therefore, the maximum number of laser beams emitted using the conventional method is 8 You can get well below the book.

FIG. 2 is a sectional view of the tape fiber 6 shown in FIG. As shown in FIG. 2, in the tape fiber 6, ten optical fiber cables 5 are arranged in a line at equal intervals. The laser light is actually carried by the core 7 at the center of the optical fiber cable 5.

As described above, there are 10 optical fiber cables 5 on the end face of the tape fiber 6, but since there are at least two directions in which the laser light travels, it is possible to change the combination of the tape fiber 6 by changing the combination. Irradiation of laser light from the end face can be reduced. This point will be described in detail in a second embodiment described later.

Further, in the optical parallel transmission system according to this embodiment, assuming that the number of signals “0” and “1” after encoding and before decoding is the same, for example, an optical / electrical conversion circuit. By providing a check circuit in 3, it is possible to detect a 1-bit error. With such a check circuit, it is possible to effectively determine the failure of one of the optical fiber cable 5 and the electrical / optical conversion circuit 2, and to determine the abnormality without adding a parity bit. become.

In this embodiment, the case where the number of the optical fiber cables 5 into which the optical signal is inputted after the conversion by the encoding circuit 1 and the electric / optical conversion circuit 2 is an even number has been described. Similarly, when the number is odd, the same effect can be obtained by encoding so that either "0" or "1" is one less than the other.

In this embodiment, the tape fiber which is a typical transmission cable has been described as an example, but the present invention is not limited to the tape fiber, and the same effect can be obtained by a structure in which ordinary optical fiber cables are bundled. Can be obtained.

[0037]

Second Embodiment Next, a second embodiment of the optical parallel transmission system of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the optical parallel transmission system according to the second exemplary embodiment of the present invention.

Referring to FIG. 3, the optical parallel transmission system according to the second embodiment of the present invention can be applied to the case of transmitting 4-bit data bidirectionally, for example. In the optical parallel transmission system according to the present embodiment, from encoding to electrical / optical conversion,
The flow of a series of processes up to optical / electrical conversion and decoding is the same as in the case of the first embodiment described above.

Since the optical signal is transmitted in two directions, the optical fiber cable 5 connected to the sending side can be seen when the cross section of one side where the tape fibers 12 and 12 'are present.
Although the laser beam is emitted from the optical fiber cable, the optical fiber cable 5 connected to the receiving side does not emit the laser beam. This phenomenon is the same as in the case of the first embodiment described above, and there is no irradiation of laser light from the other cross section of the tape fibers 6 and 12, but here the irradiation of laser light is considered considering the worst case. It is supposed to be.

Referring to FIG. 3, in the optical parallel transmission system according to the second embodiment of the present invention, the optical fibers connected to the ends of the tape fibers 12, 12 'are considered in consideration of the directivity of the optical signal. Two tape fibers 1 having a structure in which five optical cable fibers 5 and 5'are bundled by the connectors 13 and 13 '.
The optical signals are rearranged between 2 and 12 'to minimize the irradiation of laser light.

That is, the data transmitted in one direction is 4
Because of the bit width, the encoding circuits 8 and 8'convert the data into 5 bits, and the ratio of "0" and "1" is 2: 3.
Alternatively, the data converted in such a manner is reconnected by the optical connector 13 so that the data converted in such a manner becomes approximately 1: 1 in the two directions of the sending direction and the receiving direction, and the laser light is transmitted. Minimize irradiation.

Specifically, as shown in FIG. 3, two out of five outputs of the upper electro-optical conversion circuit 9 which is a transmission circuit to the right are transmitted to the left in the lower stage. Two of the five upper optical fiber cables 5 left after taking them to the circuit and taking them to the lower transmission circuit are the electrical / optical circuits that are the lower left transmission circuit. By connecting the output part of the conversion circuit 9'and the input part of the optical / electrical conversion circuit 10 ', even when the tape fiber 12 is cut,
When viewed from the cross section, only the maximum three laser light outputs are visible. Furthermore, since the three circuits are coded by the coding circuits 8 and 8 ', it is possible to suppress the irradiation of the laser beam for two lines at the maximum.

Similarly, two of the five outputs from the lower electro-optical conversion circuit 9'which is a transmission circuit to the left are brought to the transmission circuit to the right in the upper stage, and Two of the five lower optical fiber cables 5'that were left over to the transmission circuit were used as the output section of the electrical / optical conversion circuit 9, which is the upper right transmission circuit. It is connected to the input part of the optical / electrical conversion circuit 10.

In this embodiment, the number of parallel data is as small as 4, so that the sufficient effect is not obtained. However, by increasing the data width, the further effect can be obtained.

[0045]

As described above, according to the present invention,
When the parallel data is transferred, the data is once encoded into data in which the ratio of “0” and “1” is approximately the same, and then the electrical signal is converted into an optical signal and transmitted in parallel,
For example, with 8-bit parallel data, the data width increases by about 25% due to encoding, but from the viewpoint of laser light safety standards, the maximum laser light intensity emitted when the optical fiber cable is cut is about It can be reduced by 37%, and the cost for satisfying the safety standard of laser light can be reduced.

Further, according to the present invention, by encoding the parallel data, it is possible to easily discriminate the data error due to the defect phenomenon of the optical fiber cable without adding the parity bit etc., and improve the maintainability. You can

Further, according to the present invention, the output of the laser light can be further reduced by considering the directivity of the optical signal, and the safety standard of the laser light can be obtained without strengthening the structure of the cable or the connector. Can be satisfied.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical parallel transmission system according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view of the tape fiber shown in FIG.

FIG. 3 is a block diagram showing a configuration of an optical parallel transmission system according to a second exemplary embodiment of the present invention.

[Explanation of symbols]

 1 Encoding circuit (8 bits → 10 bits) 2 Electrical / optical conversion circuit (10 bits) 3 Optical / electrical conversion circuit (10 bits) 4 Decoding circuit (10 bits → 8 bits) 5 Optical fiber cable 6 Tape fiber ( 10 cores 7 cores 8, 8'encoding circuit (4 bits → 5 bits) 9, 9'electric / optical conversion circuit (5 bits) 10, 10 'optical / electrical conversion circuit (5 bits) 11, 11' decoding Circuit (5 bits → 4 bits) 12, 12 'Tape fiber (5 cores) 13, 13' Optical connector

Claims (6)

[Claims] 1. An optical parallel transmission system for converting a plurality of data into a plurality of optical signals and synchronously transferring them in parallel, wherein the plurality of data are encoded so that the ratio of "0" and "1" is the same. An optical parallel transmission system characterized in that the encoded data is converted into an optical signal and output to an optical fiber cable after being converted into a data of a certain degree. 2. The optical parallel transmission system according to claim 1, wherein the plurality of data are encoded by being associated with a larger number of data than the plurality of data by a predetermined number. 3. The method according to claim 1, wherein when the number of encoded data is an even number, "0" and "1" of the encoded data are the same number. Optical parallel transmission system described. 4. When the number of encoded data is an odd number, the difference between the numbers of “0” and “1” of the encoded data is 1. Item 1 or 2
Optical parallel transmission system described. 5. An optical parallel transmission system for converting a plurality of data into a plurality of optical signals and synchronously transferring them in parallel, wherein a plurality of optical fiber cables for transmitting the plurality of optical signals are bundled together. The optical fiber cables having different structures are included in the plurality of optical fiber cables having the structure so that the ratios of the optical fiber cables having different optical signal transmission directions are similar to each other. An optical parallel transmission method characterized in that 6. The plurality of pieces of data are encoded so that the ratio of “0” and “1” of the data output to the optical fiber cable in which the transmission direction of the optical signal is the same is approximately the same. The optical parallel transmission system according to claim 5, wherein