JPH10268147A - Optical bus board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical bus board capable of being reduced in size and giving high throughput. SOLUTION: This bus board has an optical signal distributor 7' made of an optical star coupler 27 having a waveguide 26 capable of distributing optical signals, guides 28 positioned and laid so as to enable the waveguide 26 and an optical fiber conductor 17 to be optically coupled at desired coupling efficiency, a substrate 29 for fixing the optical star coupler 27 and the guides 28, and a fixing mechanism 30 for fastening the optical fiber conductor 17. According to this construction, the conventional optical connector is eliminated, and a device can be formed to have a compact size, high density, light weight, high throughout or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical bus board constituting a data bus for transmitting data between a plurality of circuit boards.

[0002]

2. Description of the Related Art In order to realize a high-speed and large-capacity communication or information processing electronic device capable of responding to the demands of the future multimedia age, the inside of the device is connected together with the high performance of an LSI such as a processor. It is essential to increase the data bus throughput. Therefore, it has been studied and implemented to use an optical data bus capable of high speed and high throughput for transmitting data between a plurality of circuit boards by optical signals for signal connection in a communication system or an information processing system electronic device. (Eg, K. Itoh et al., “Data TransmissionPerform
ance of an Optical Backboard Bus ”Proc. 1995 Japan
IEMT Symposium, pp.268-271, 1995).

[0003] The optical data bus has no high-frequency loss, reflection due to branching, and the like, so that waveform distortion does not occur with respect to high-speed signals, and high-speed of several tens Gb / s or more can be achieved.
In addition, there is no load fluctuation on the input / output circuit of each circuit board due to the number and position of the circuit boards, which is a problem in the conventional data bus using electric signals, so that the scale can be increased.

FIG. 1 shows an outline of an optical data bus.
FIG. 1A is a perspective view, and FIG. 1B is a side view. Data transmission between the circuit boards 2 is performed by an optical bus board 3 connected to a plurality of circuit boards 2 via a back board 1 corresponding to a conventional electric bus. Each circuit board 2 is connected to the backboard 1 via an electrical connector 4 as in the conventional device, and the optical bus board 3 is connected to the backboard 1 by an electrical connector 5 constituting the optical bus board 3. Have been.

An optical bus board 3 for distributing a signal from one circuit board 2 to another circuit board 2 includes a plurality of electric / optical conversion circuits for converting electric signals received via the back board 1 into optical signals. 6, an optical signal distributor 7 for distributing an optical signal from an arbitrary electrical / optical conversion circuit 6 to each circuit board 2, and converting a plurality of optical signals from the optical signal distributor 7 into electrical signals. A plurality of optical-to-electrical conversion circuits 8 that output to the corresponding electrical connectors 5, between the electrical-to-optical conversion circuits 6 and the optical signal distributor 7, and between the optical signal distributor 7 and the optical-to-electrical conversion circuit 8 And an optical glass fiber 9 for connecting the optical fiber with an optical signal.

The optical signal distributor 7 has the same number of optical input ports 10 as the number m of circuit boards 2 required to transmit signals,
It has the same number n of optical output ports 11 as the number n of circuit boards 2 required to receive signals, and transmits the optical signals input to each of the m optical input ports 10 to the n optical output ports 11. It has the function of distributing with equal output.

The interconnection of signals such as data between circuit boards 2 having an arbitrary function is performed by transmitting an electric signal from a signal output terminal of the circuit board 2 via an electrical connector 5 to an optical bus board 3.
Is converted into an optical signal by an electric / optical conversion circuit 6 mounted on the surface of the optical signal distributor, transmitted to one input port 10 of an optical signal distributor 7 by an optical glass fiber 9, and divided into n by the optical signal distributor. transmitted to the n output ports 11 and
The electric signal is converted by the electric conversion circuit 8 into an electric signal.
Is transmitted to the signal input terminal of the circuit board 2 through the interface.

As shown in FIG. 2, a resin layer 16 on a surface of a substrate 15 having electric signal wirings 14 has an outer diameter as an electric / optical mixed substrate on which electric components such as the optical bus board and optical components are mixed. It has been proposed to use a fiber wiring board 15 in which an optical fiber core 17 of 0.25 mm is embedded. As a result, the area occupied by the fiber connection on the optical bus board 3 can be reduced to about 1.5% and the weight is significantly reduced as compared with the case where the conventional single-core optical fiber having a coating outer diameter of 2 mm is used. Is achieved.

[0009]

However, the optical coupling between the optical fiber core 17 and the optical components such as the optical signal distributor 7 in the optical bus board 3 to which the optical fiber wiring board 15 having such characteristics is applied. As shown in FIG. 3, this is performed through an optical connector 18 of a conventional SC type or an MJ type smaller than the SC type, which is manufactured for the purpose of connecting a single-core optical fiber cord or the like.

For this reason, a splice technique using a tool used for connection of an optical fiber cord or the like is applied to the optical fiber core 17 of the optical fiber wiring board 15 capable of achieving high density and light weight. And an optical connector plug 19 at one end.
The optical connector 18 is provided by a method of mechanically connecting the portion of the optical fiber 20 provided with a mark and a portion 21 of the embedded optical fiber core 17 rising from the substrate 15 with the fixing terminal 22 or the like, or a method of connecting by fusion. Plug 19 was connected.

However, according to this method, the optical fiber 2 with the plug 19 is required for positioning and fixing with a tool.
Both the zero and the rising portion 21 of the embedded optical fiber core 17 from the substrate 15 require an extra fiber length of about 30 cm, and the connection between the optical fiber core 17 and the optical component requires the rising of the embedded fiber. Although a length of about several cm is originally sufficient from the part to the plug, there is a problem that an extra optical fiber having a length of about 60 cm, which is several tens of times that of the length, is generated on the substrate 15. .

This not only hinders the high-density mounting of components, but also replaces the optical fiber 20 with the plug 19 with a tensile fiber such as Kevlar necessary for reinforcing and protecting the fiber core 17 as shown in FIG. It is necessary to form the optical fiber cord 25 covered with the reinforcing material 23 and the resin 24 by the above, and the area occupied by the optical fiber cord 25 increases, and the advantages of high density and light weight using the optical fiber wiring board 15 are obtained. There was a problem that was not utilized.

Further, since the optical waveguide constituting the optical star coupler having the function of distributing light in the optical signal distributor 7 is formed by photolithography, the light input from which the optical signal line from the circuit board 2 is concentrated is concentrated. Output port 9,
10 is 250 μm, which is almost the same as the outer diameter of the optical fiber core 17.
Also in the optical signal distributor 7 which can be formed in pitch in principle, the plug 19 of the optical connector 18 having an outer dimension of several cm is connected by using the optical fiber cord 25 similarly to the embedded optical fiber core 17. Therefore, the optical signal distributor 7 has been hindered from being reduced in size and increased in density.

Next, a description will be given of a problem with respect to increasing the throughput of the apparatus accompanying the development of the multimedia technology. When a higher throughput of the device is required, as a method of realizing it, a method of arranging a plurality of signal lines transmitted and received from one circuit board 2 and transmitting them in parallel, and a method of multiplexing signals in the circuit board 2 And one circuit board 2
There is a method of increasing the signal speed transmitted / received from the Internet.

When the parallel transmission is adopted, the optical bus board 3
In the method in which the conventional optical connector 18 is applied to the optical coupling between the optical fiber core 17 and the optical signal distributor 7 in the above-mentioned method, about 40 circuits arranged at a pitch of about 15 mm corresponding to one unit 12 of a communication system device assuming the data bus between the substrate 2, for example, to connect the optical fiber cord 25 having an outer diameter of 2 mm 4 in parallel, the optical signal distributor input port 9 of 7, the output port 10 are both about 500 mm ² optical fiber cord 2
In addition to requiring an occupied area of 5, the optical connector 18 with 160 optical fiber cords 25 is disposed at each of the input port 9 and the output port 10 of the optical signal distributor 7, and the optical bus board 3 itself There was a problem that it became difficult to manufacture.

On the other hand, in the method of multiplexing in the circuit board 2 for high throughput, the signal transmission speed is 10 Gb.
/ S or more, for example, at a low cost and a transmission rate of 1 to 2 Gb /
It is necessary to manufacture electric and optical elements using high-cost manufacturing techniques different from those for high-speed electrical and optical active elements and optically active elements. However, there is a problem that the optical bus having a configuration mounted on the backboard becomes inappropriate.

An object of the present invention is to provide an optical bus board which can be downsized and has a high throughput and can constitute an electronic device which can be scaled up with high speed, high function and high throughput.

[0018]

According to the present invention, in order to achieve the above object, a plurality of circuit boards each having a desired function are provided corresponding to each of the plurality of circuit boards and exchange electric signals with the circuit boards. An electrical connector, a plurality of electrical-optical conversion circuits for converting electrical signals from the electrical connectors into optical signals, an optical signal distributor for distributing optical signals from any electrical-optical conversion circuit, A plurality of optical-to-electrical conversion circuits for respectively converting the plurality of optical signals distributed from the signal distributor to electric signals and outputting the electric signals to corresponding electric connectors, and any one of the plurality of circuit boards An optical bus board for distributing signals from a plurality of other circuit boards to an optical bus between the electrical / optical conversion circuit and the optical signal distributor and between the optical signal distributor and the optical / electrical conversion circuit. Board surface resin The optical signal distributor is connected with an optical star coupler consisting of an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate, and a resin layer. It is characterized by comprising a guide for aligning the raised optical fiber core with the waveguide of the optical star coupler, and a fixing mechanism for fixing the optical fiber core.

According to the present invention, there is no need to use an optical connector as in the prior art for connecting the optical signal distributor to the optical fiber core embedded in the resin layer on the surface of the optical bus board, and an extra space is provided on the substrate. Since there is no danger of producing an optical fiber core, the apparatus can be reduced in size, density, weight, and the like, and the number of parts can be reduced, so that the cost can be reduced.

Further, a circuit board having an arbitrary function is connected in parallel with the optical bus board by a plurality of electric signal lines, and each electric signal line is connected to an input of a plurality of electric / optical conversion circuits. The output of the optical conversion circuit is connected in parallel to the input port corresponding to the circuit board on the transmitting side of a separate optical signal distributor by a plurality of optical fibers, and the output port corresponding to the circuit board on the receiving side of each optical signal distributor. Are connected to the inputs of a plurality of optical / electrical conversion circuits by a plurality of optical fibers, respectively, and the outputs of the respective optical / electrical conversion circuits are connected in parallel to a circuit board having an arbitrary function by a plurality of electric signal lines. For example, it is possible to increase the throughput while using a low-cost conventional electric element or optical active element.

Further, the optical signal distributor has a structure in which a plurality of optical star couplers each composed of an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate are laminated, and are arranged in parallel from the same circuit board. The connected signal lines are connected one-to-one to the input ports of the star coupler of each layer corresponding to the circuit board on the transmitting side, and the output of the star coupler of each layer corresponding to the circuit board on the receiving side. According to the parallel connection of the signal lines from the ports to the same circuit board, it is possible to reduce
The phase difference between optical signals from a plurality of electro-optical conversion circuits connected in parallel to one circuit board to the photoelectric conversion circuit is reduced by about 5
It can be suppressed to about ps.

[0022]

FIG. 5 shows a first embodiment of an optical bus board according to the present invention. FIG. 5 (a) is a side view of an optical signal distributor, and FIG. 5 (b) is an optical signal distributor. FIG. 2C is a plan view of the distributor, and FIG. 3C is a side view showing an optical coupling structure between the optical signal distributor and the embedded optical fiber core.

An optical signal distributor, for example, 7 ′ includes an optical star coupler 27 having a waveguide 26 having a function of distributing an optical signal, an optical waveguide 26 and an optical fiber core 17.
And a light star coupler 27 which are positioned and arranged so that the optical coupling can be performed with a desired coupling efficiency.
It comprises a substrate 29 for fixing the optical fiber 17 and the guide 28, and a fixing mechanism 30 for fixing the optical fiber 17.

The optical coupling between the optical signal distributor 7 'and the optical fiber core 17 is performed by setting the end 31 of the optical fiber core 17 rising from the resin layer at a predetermined position along the guide 28 at a predetermined position. It is configured to be aligned without any adjustment by inserting it up to and fixed by the fixing mechanism 30.

When a glass capillary is used as the guide 28, for example, the dimensional accuracy of the inner diameter of the glass capillary is +
Since the thickness can be 0.001 mm, this structure enables optical connection with the optical waveguide 26 constituting the optical signal distributor 7 even with a single mode fiber having a core diameter of about 10 μm. The same applies to the outer dimensional accuracy of the glass capillary, and the optical waveguide 26 is formed by photolithography. The dimensional accuracy is 0.001 mm or less. When using a 50 μm multimode fiber,
By arranging the glass capillaries on a substrate having a V-groove or a flat substrate, an optical coupling portion having a structure capable of coupling the optical glass fiber core 17 and the optical waveguide 26 with sufficient efficiency can be easily formed.

Further, the length of the optical fiber core 21 rising from the resin layer 16 can be made the shortest necessary for connecting to the optical signal distributor 7 'along the capillary, which is simple and compact. It is possible to optically couple the optical fiber core 17 with the optical signal distributor 7 '.

As shown in FIG. 6, by inserting a lens 32 between the guide 28 and the waveguide 26, the coupling efficiency between the optical fiber core 17 and the optical waveguide 26 can be increased. is there.

In the present optical bus board, for example, 3 ',
Since the optical signal distributor 7 'is a passive component and there is no possibility of failure or the like, after optical coupling between the optical signal distributor 7' and the optical fiber core 17, it is not possible to remove and insert the optical fiber core 17. rare. Therefore, the function of the optical connector on the premise that an optical fiber required for an optical coupling structure between an active element such as an optical element that requires component replacement or the like at the time of a failure and the optical fiber is not required is necessary, and is essentially unnecessary. It is sufficient that positioning and fixing can be performed as in the present optical coupling structure.

Therefore, the dimensions and shape of the optical coupling portion are determined by the guide 28.
And the outer diameter of the guide 28 can be made substantially the same as the outer diameter of the optical fiber core 17, so that not only the optical coupling structure can be reduced in size, but also the number of parts can be reduced and the cost can be reduced. It is possible.

FIG. 7 shows a second embodiment of the present invention. FIG. 7A shows one circuit board 2 and an optical bus board 3 'of the present invention connected by a plurality of parallel signal lines. FIG. 2B is an enlarged view of a joint between a plurality of parallel optical glass fibers connected to one circuit board and an optical signal distributor.

As shown, one circuit board 2 having an arbitrary function and an optical bus board 3 'are connected to a plurality of signal lines 33.
The electric signals transmitted in parallel from the circuit board 2 are converted into optical signals by the electric / optical conversion circuit 6 for each electric signal line. The optical signal is supplied to the input port 10 corresponding to the circuit board 2 on the transmission side of the optical signal distributor 7 ′ for each fiber by a plurality of optical fiber cores 17.
And is distributed to each optical signal distributor 7 '. Circuit board 2 on the receiving side of each optical signal distributor 7 '
The optical signal from the output port 11 corresponding to is converted into an electrical signal by the optical / electrical conversion circuit 8 for each optical signal line, and a plurality of signals corresponding to the plurality of signals transmitted from the circuit board 2 on the transmission side are output. It is transmitted in parallel for each circuit board having an arbitrary function.

The optical signal distributor 7 'has a structure in which a star coupler 27 composed of an optical waveguide 26 is laminated, and a signal line 33 connected in parallel from the same circuit board 2 corresponds to the circuit board 2 on the transmission side. The star couplers 27 of each layer are connected to the input port 10 of the star coupler 27 of each layer in a one-to-one correspondence, and correspond to the circuit board 2 on the receiving side.
Are connected in parallel to the same circuit board 2.

According to this configuration, it is possible to increase the throughput of the optical bus board 3 'and the circuit board 2 while using the same electric active element, light emitting element, and light receiving element as in the prior art.
The optical fiber core 17 embedded in the optical bus board 3 'is laid out by CAD, including the portion rising from the substrate, and the length of the optical fiber is 1 m.
m, the optical signal distributor 7
Since the waveguide 26 is formed by photolithography, the length can be controlled with an accuracy of 1 μm or less.
It is possible to suppress the phase difference between the optical signals from the plurality of electrical-optical conversion circuits 6 connected in parallel to one circuit board 2 to the optical-electrical conversion circuit 8 to about 5 ps.

Further, the thickness of the optical waveguide 26 in the optical signal distributor 7 'may be substantially the same as the core diameter of the optical glass fiber core 17, so that the thickness of the optical signal distributor 7' per layer Is limited by the outer dimensions of the guide 28. For example, when a glass capillary is used as the guide 28, since the outer dimension is 0.25 mm,
The minimum thickness of the optical signal distributor 7 'per layer is 0.25 m
m, for example, even if four layers are stacked, the optical signal distributor 7 ′
Has a small component height of 1 mm, and high-density mounting is possible.

[0035]

As described above, according to the present invention,
A plurality of electrical connectors respectively provided for a plurality of circuit boards having an arbitrary function and exchanging electrical signals with the circuit boards; and a plurality of electrical connectors respectively converting electrical signals from the electrical connectors into optical signals. And an optical-to-optical conversion circuit, an optical signal distributor that distributes optical signals from an arbitrary electrical-to-optical conversion circuit, and a plurality of optical signals that are distributed from the optical signal distributor are converted into electrical signals, respectively. A plurality of optical-electrical conversion circuits that output to the electrical connector to be provided, in an optical bus board that distributes a signal from any one of the plurality of circuit boards to a plurality of any other circuit boards, Connect the optical-to-optical converter and the optical-signal distributor and the optical-signal distributor and the optical-to-electrical converter with an optical fiber core embedded in the resin layer on the surface of the optical bus board. The distributor An optical star coupler comprising an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate, and a guide for aligning an optical fiber core rising from the resin layer with the optical star coupler waveguide. The optical bus board for interconnecting signals such as data between a plurality of circuit boards having arbitrary functions by reducing the size, density and weight of the optical bus , It is possible to increase the scale.

According to the present invention, a circuit board having an arbitrary function is connected in parallel with an optical bus board by a plurality of electric signal lines, and each electric signal line is connected to an input of a plurality of electric / optical conversion circuits. The output of each electrical / optical conversion circuit is connected in parallel to the input port corresponding to the circuit board on the receiving side of a separate light transmitting signal distributor by a plurality of optical fibers, and the receiving side of each optical signal distributor is connected. An output port corresponding to the circuit board is connected to an input of a plurality of optical / electrical conversion circuits by a plurality of optical fibers, respectively, and an output of each optical / electrical conversion circuit is connected to a circuit board having an arbitrary function by a plurality of electric signal lines. By connecting them in parallel, an optical bus board that interconnects signals such as data between multiple circuit boards with arbitrary functions can achieve high throughput while using low-cost conventional electric elements and optical active elements Do Theft is possible.

Further, the optical signal distributor has a structure in which a plurality of optical star couplers composed of an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate are laminated, and the optical signal distributor is arranged in parallel from the same circuit board. Is connected to the input port of the star coupler of each layer corresponding to the circuit board on the transmitting side in a one-to-one correspondence, and the star coupler of each layer corresponding to the circuit board of the receiving side is determined. By connecting the signal lines from the output ports in parallel to the same circuit board, the optical bus board for interconnecting signals such as data between a plurality of circuit boards having arbitrary functions has been reduced in size and density, In addition, it is possible to suppress the phase difference between the optical signals from the plurality of electro-optical conversion circuits connected in parallel to one circuit board to the photoelectric conversion circuit to about 5 ps. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an optical data bus.

FIG. 2 is a configuration diagram showing an outline of an optical fiber wiring board;

FIG. 3 is a configuration diagram showing an optical coupling structure between an optical fiber core and an optical signal distributor using a conventional optical connector in an optical bus board.

FIG. 4 is a sectional view of an optical fiber cord.

FIG. 5 is a configuration diagram showing a first embodiment of the optical bus board of the present invention.

FIG. 6 is a configuration diagram showing an outline of an optical signal distributor having a lens.

FIG. 7 is a configuration diagram showing a second embodiment of the optical bus board of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Back board, 2 ... Circuit board, 3 '... Optical bus board, 4, 5 ... Electric connector, 6 ... Electric-optical conversion circuit,
7 ': optical signal distributor, 8: optical-electrical conversion circuit, 9: optical glass fiber, 10: optical input port, 11: optical output port, 14: electrical signal line, 15: optical fiber wiring board, 1
6 resin, 17 optical fiber core, 26 waveguide, 27 optical star coupler, 28 guide, 29 substrate, 30 fixing mechanism, 31 end of optical fiber core, 3
2 ... lens, 33 ... signal line.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuro Crescent 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A plurality of electrical connectors which are provided corresponding to a plurality of circuit boards having an arbitrary function and exchange electrical signals with the circuit boards, respectively. A plurality of electrical / optical conversion circuits for converting signals, an optical signal distributor for distributing optical signals from an arbitrary electrical / optical conversion circuit, and a plurality of optical signals distributed from the optical signal distributor, respectively. And a plurality of optical-to-electrical conversion circuits that output the signals to corresponding electrical connectors, and distributes signals from any one of the plurality of circuit boards to any of a plurality of other circuit boards. In an optical bus board, an optical fiber core embedded in a resin layer on the surface of the optical bus board connects between the electrical / optical conversion circuit and the optical signal distributor and between the optical signal distributor and the optical / electrical conversion circuit. Along with An optical star coupler consisting of an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate, and an optical fiber core rising from a resin layer are used as a signal distributor. An optical bus board comprising a guide for positioning and a fixing mechanism for fixing an optical fiber. 2. A circuit board having an arbitrary function is connected in parallel with an optical bus board by a plurality of electric signal lines, and each electric signal line is connected to an input of a plurality of electric / optical conversion circuits. The output of the optical conversion circuit is connected in parallel to the input port corresponding to the circuit board on the transmitting side of a separate optical signal distributor by a plurality of optical fibers, and the output port corresponding to the circuit board on the receiving side of each optical signal distributor. Are connected to the inputs of a plurality of optical-to-electrical conversion circuits by a plurality of optical fibers, respectively, and the outputs of the optical-to-electrical conversion circuits are connected in parallel to a circuit board having any function by a plurality of electric signal lines. The optical bus board according to claim 1, wherein 3. The optical signal distributor has a structure in which a plurality of optical star couplers composed of an organic optical waveguide formed on a resin film or an inorganic optical waveguide formed on an inorganic flat plate are laminated, and are arranged in parallel from the same circuit board. The connected signal lines are connected one-to-one to the input ports of the star coupler of each layer corresponding to the circuit board on the transmitting side, and the output of the star coupler of each layer corresponding to the circuit board on the receiving side. 3. The optical bus board according to claim 2, wherein signal lines from the ports are connected in parallel to the same circuit board.