JPH1062657A - Optical bus and signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical bus and a signal processor in which the optical bus has been adopted that have high resistance against the environmental changes such as the temperature change and dust, and also the free detachment of the circuit substrates can be easily carried out in accordance with the expansibleness of a system. SOLUTION: An optical path and a signal processor are provided with a plurality of signal light incident parts 24a through which the incidence of signal light is carried out, a plurality of signal light outgoing parts 24b through which the outgoing of signal light is carried out, and optical bus bodies 20 each of which is formed in a sheet shape for propagating the signal light being incident from the signal light incident parts 24a toward the signal light outgoing parts 24b; and the signal light incident parts 24a and the signal light outgoing parts 24b are formed on both ends of the optical bus bodies 20, and also they are formed in the opposite positions intervening the optical bus bodies 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical bus for transmitting an optical signal and a signal processing device for performing signal processing including transmission and reception of data using the optical bus.

[0002]

2. Description of the Related Art With the development of very large scale integrated circuits (VLSI), circuit functions of circuit boards (daughter boards) used in data processing systems have been greatly increased. Since the number of signal connections to each circuit board increases as the circuit function increases, a data bus board (mother board) that connects each circuit board (doder board) with a bus structure requires a large number of connectors and connection lines. Parallel architectures have been adopted. Although the parallel bus has been improved by increasing the number of connection lines and miniaturization, the operation speed of the parallel bus has been improved.However, due to the signal delay caused by the capacitance between the connection lines and the resistance of the connection lines, the processing speed of the system becomes parallel. It may be limited by the operating speed of the bus. In addition, electromagnetic noise (E
MI: Electromagnetic Interf
issue) is also a significant constraint on improving the processing speed of the system.

In order to solve such a problem and improve the operation speed of the parallel bus, use of an in-system optical connection technique called optical interconnection has been studied. For an overview of optical interconnection technology, see "Tadaji Uchida, 9th Circuit Packaging Academic Conference, 15C01, p.
p. 201 to 202 ”and“ H. Tomimiuro et
al. , "Packaging Technology
for Optical Interconnect
s ", IEEE Tokyo No. 33, pp. 81
-86, 1994], Osamu Wada, Electronics 19
As described in "April 1993, pp. 52-55", various forms have been proposed depending on the configuration of the system.

[0004]

SUMMARY OF THE INVENTION Among the various types of optical interconnection technologies that have been proposed in the past,
Japanese Patent No. 41042 discloses an example in which an optical data transmission system using a high-speed, high-sensitivity light emitting / receiving device is applied to a data bus. A serial optical data bus for loop transmission between circuit boards has been proposed, in which light emitting / receiving devices on adjacent circuit boards incorporated in a system frame are spatially coupled by light. . In this method, a signal light sent from a certain circuit board is subjected to optical / electrical conversion on an adjacent circuit board, and further subjected to electrical / optical conversion on the circuit board again, and then transmitted to the next adjacent circuit board. Each circuit board is sequentially arranged in series, and is transmitted between all circuit boards incorporated in the system frame while repeating optical / electrical conversion and electric / optical conversion on each circuit board. For this reason, the signal transmission speed depends on the optical / electrical conversion speed and the electrical / optical conversion speed of the light receiving / light emitting device arranged on each circuit board, and at the same time is restricted. For data transmission between each circuit board, a light receiving / light emitting device arranged on each circuit board is used.
Since the optical coupling using free space is used, the light emitting / receiving devices arranged on the front and back sides of the adjacent circuit board are optically aligned and all the circuit boards are optically connected. Is required. Furthermore, since the optical fibers are coupled via a free space, interference (crosstalk) between adjacent optical data transmission lines occurs, and poor data transmission is expected. In addition, it is expected that data transmission failure will occur due to scattering of signal light due to an environment in the system frame, for example, dust or the like. Further, since the circuit boards are arranged in series, if any one of the boards is removed, the connection is interrupted there, and an extra circuit board is required to compensate for the disconnection. That is, there is a problem that the circuit board cannot be freely inserted and removed, and the number of the fixed boards is fixed.

A technique for transmitting data between circuit boards using a two-dimensional array device is disclosed in Japanese Patent Application Laid-Open No. 61-196210.
No. 6,086,045. The technique disclosed herein comprises a plate facing a light source having two parallel surfaces,
This is a method in which circuit boards are optically coupled via an optical path constituted by a diffraction grating and a reflection element arranged on the plate surface. In this method, light emitted from one point can be connected only to a fixed point, and all circuit boards cannot be exhaustively connected like an electric bus. Also,
Since a complicated optical system is required and it is difficult to perform positioning, etc., interference (crosstalk) between adjacent optical data transmission paths occurs due to the displacement of the optical element, and poor data transmission is expected. Since connection information between circuit boards is determined by a diffraction grating and a reflective element arranged on the plate surface, there are various problems such as the inability to freely insert and remove the circuit board and low expandability.

Another technique for transmitting data between circuit boards using a two-dimensional array device is disclosed in Japanese Patent Laid-Open No. 4-1344.
No. 15 discloses this. This publication discloses a lens array composed of a plurality of lenses having a negative curvature on a base made of a transparent material having a higher refractive index than air, and a light source for emitting light emitted from a light source from a side surface of the lens array. A data transmission system provided with an optical system is disclosed. This publication also discloses a method of forming a low-refractive-index region or a hologram in the substrate in place of a plurality of lenses having a negative curvature. In these methods, light incident from the side surface of the base is distributed to the upper surface of the base from a plurality of lenses having the above-mentioned negative curvature, a region having a low refractive index instead of the lens, or a portion formed with a hologram, and emitted. It is configured to: Therefore, it is conceivable that the intensity of the emitted signal varies depending on the positional relationship between the incident position of the light and a plurality of lenses, a region having a low refractive index instead of the plurality of lenses, and the emitting position on the substrate surface on which the hologram is formed. Further, it is considered that the ratio of light incident from the side surface of the base body to escape from the side surface opposite to the incident surface is high,
The efficiency of light used for signal propagation is low. Furthermore, since it is necessary to dispose a plurality of lenses having a negative curvature formed on the surface of the substrate, and a region where the refractive index is low or a hologram is substituted for the lens, the light input element of the circuit substrate is disposed. There are various problems that the degree of freedom is small and the expandability of the system is low.

In view of the above circumstances, the present invention provides an optical bus having high resistance to environmental changes such as temperature changes and dust, and capable of easily attaching and detaching a circuit board in accordance with expandability of a system, and an optical bus therefor. It is an object to provide a signal processing device employing a bus.

[0008]

According to the present invention, there is provided an optical bus according to the present invention, comprising: (1-1) a plurality of signal light input portions for injecting signal light, and a plurality of signal light in charge for emitting signal light. An emission section; and a sheet-shaped optical bus body for propagating the signal light incident from the signal light incidence section toward the signal light emission section. (1-2) The signal light incidence section and the signal A light emitting portion is formed on an end face of the optical bus main body, and the signal light incident portion and the signal light emitting portion are formed at positions facing each other with the optical bus main body interposed therebetween. .

Here, the optical bus main body includes a core layer for transmitting signal light, and a clad layer sandwiching the core layer and having a lower refractive index than that of the core layer. There may be. As described above, when the cladding layer is provided adjacent to the core layer, the signal light propagation efficiency can be increased. When a plurality of core layers are stacked, the provision of the clad layer can further reduce crosstalk between the plurality of signal light propagation layers.

Further, the optical bus body may have a plurality of core layers laminated with the clad layer interposed therebetween. As described above, by providing a plurality of core layers in the optical bus of the present invention, it is possible to transmit a parallel optical signal composed of a plurality of bits from one signal light input unit to another signal light output unit, Simultaneous transmission / reception with an optical signal from one signal light input unit to another signal light output unit independent of the optical signal from one signal light input unit to another signal light output unit Becomes

In the optical bus of the present invention, it is not always necessary to provide a plurality of core layers, but it is necessary to provide only one layer and distinguish one from another based on the wavelength of signal light and the like, thereby simultaneously transmitting and receiving a plurality of optical signals in one layer. May be performed. Further, it is preferable that the optical bus main body includes a light-shielding layer for preventing signal light from propagating between the core layers, between the plurality of core layers laminated with the clad layer interposed therebetween.

The signal processing apparatus of the present invention employing the above-described optical bus includes: (2-1) a substrate (2-2) a signal light emitting end for emitting signal light and a signal emitted from the signal light emitting end. At least one of an electronic circuit that generates a signal to be carried by light, and an electronic circuit that performs signal processing based on the signal carried by the signal light incident end where the signal light is incident and the signal light incident from the signal light incident end. (2-3) A plurality of signal light incident portions, which are fixed to the above-mentioned base and are responsible for signal light incidence, a plurality of signal light emitting portions responsible for emitting signal light, and a signal An optical bus main body formed in a sheet shape for propagating the signal light incident from the light incident portion toward the signal light emitting portion, wherein the signal light incident portion and the signal light emitting portion are connected to the optical bus main body. Signal light incident And an optical bus having a signal light emitting portion formed at a position facing the optical bus main body. (2-4) A signal light emitting end and a signal light incident end mounted on the circuit board. Are provided with a plurality of substrate fixing portions that are fixed on the base in a state where the substrate is coupled to the optical bus at the signal light incidence portion and the signal light emission portion, respectively.

According to the signal processing device of the present invention, as described above, the optical bus of the present invention is employed, and high-speed communication using an optical signal is possible. Here, in the processing signal device of the present invention, the substrate fixing unit includes a substrate connector that performs input and output of an electric signal to and from an electronic circuit mounted on a circuit board fixed to the substrate fixing unit. It is preferred that it is. When the board fixing portion is provided with a board connector, the board connector has both an optical coupling between the signal light emitting end or the signal light incident end mounted on the circuit board and the optical bus, and an input / output of an electric signal. Can be carried. The circuit board can be fixed to the board fixing portion, and at the same time, the signal light emitting end or the signal light incident end mounted on the circuit board can be connected to the optical bus. No special alignment is required. This will be described more specifically in an embodiment described later.

In the signal processing apparatus of the present invention, the signal light emitting end or the signal light incident end mounted on the circuit board is disposed at the position of the signal light emitting end or the signal light incident end. Each may be a light emitting element that emits signal light, or a light receiving element that receives signal light, or the signal light emitting end or the signal light incident end may be formed by an optical waveguide that propagates signal light, respectively. It may be a signal light emitting end or a signal light incident end.

[0015]

Embodiments of the present invention will be described below. FIG. 1 is a diagram illustrating a signal processing according to the present invention including a sheet-like optical data bus, which is an embodiment of the optical bus of the present invention, and a plurality of circuit boards optically connected to each other by the sheet-like optical data bus. It is a schematic structure figure of one embodiment of a device.

A support substrate 1 which is an example of the substrate according to the present invention
The optical data bus 12 in a sheet shape is fixed on the reference numeral 0. The sheet-shaped optical data bus 12 includes a sheet-shaped optical data bus main body 20 in which core layers 21 and clad layers 22 are alternately stacked, a signal light incident portion 24a, and a signal light emitting portion 24.
b. , 30 are fixed on the supporting substrate 10, and each circuit board connector 30,.
, 40 are detachably mounted.

A power supply line and electric wires 11 for transmitting electric signals are provided on the support substrate 10, and the electric wires 11 are connected to the board connectors 30,.
, And 30 are electrically connected to the electronic circuits 41 on the circuit boards 40,..., 40 mounted on the board connectors 30,. Also, each circuit board 40,.
, 40 are provided with opposing light emitting and receiving elements 42,..., 42, each of which is a pair of a light emitting element and a light receiving element. The light receiving elements 42,..., 42 are optically coupled to the optical data bus 12. The signal light incident part 24a and the signal light emitting part 24b of the optical data bus 12 are arranged on the end face 20a of the optical data bus main body 20 at a position facing each other with the respective core layers 21 of the optical data bus main body 20 interposed therebetween. The signal light emitted from the light emitting element in a certain light emitting / receiving element 42 enters the core layer 21 of the optical data bus main body 20 from the signal light incident portion 24a of the optical data bus 12, propagates through the core layer 21, The light is transmitted to the signal light emitting portion 24b located at a position facing the signal light incident portion 24a, and is received by a light receiving element in the light emitting and receiving element 42 optically coupled to the signal light emitting portion 24b.

In the optical bus of the present invention, as described above, the signal light incident portion and the signal light emitting portion are formed on the end face of the optical bus main body, and the signal light incident portion and the signal light emitting portion form the optical bus main body. The signal light incident from the signal light incident portion formed on the end face of the optical bus main body is formed at the position opposed to the optical bus main body. Therefore, an optical bus having high signal light propagation efficiency is formed.

FIG. 2 is a partially enlarged view of the support substrate and the optical data bus main body of the signal processing device shown in FIG. However,
In FIG. 2, the number of layers of the optical data bus main body 20 is generalized, and the optical data bus main body 20 is further illustrated by adding a light shielding layer 23. The optical data bus main body 20 is fixed on the support substrate 10, and includes a core layer 21, a cladding layer 22 formed so as to sandwich the core layer 21 from above and below, and a light shielding layer sandwiched between the cladding layers 22. 23 have a structure in which a large number of layers are stacked as shown in the figure.

The core layer 21 is a layer for transmitting signal light. In this embodiment, the layer has high light transmittance and has a thickness of 0.5 mm per layer of polymethyl methacrylate (PMMA).
Is used. The cladding layer 22 is formed of the core layer 2
A material having a refractive index lower than the refractive index of the core layer 21 is selected as a layer having a function of suppressing light in the layer 1 from leaking in the thickness direction of the layer. Here, PM is applied to the core layer 21.
Since MA is employed, a fluorine-containing polymer material is suitably employed for the cladding layer 22. Further, in the present embodiment, in order to prevent the signal light from entering the adjacent core layer 21 beyond the cladding layer 21, the light shielding layer 23 for absorbing light is provided so as to be sandwiched between the cladding layers 21. I have. In the present embodiment, the thickness of the two cladding layers 22 sandwiching the light shielding layer 23 is 0.5 mm, which is the same as the thickness of the core layer 21.
By preparing and stacking these sheet materials and then pressing them together, an optical bus having the laminated structure shown in the figure is formed.

FIG. 3 is a partially enlarged view of a circuit board of the signal processing device shown in FIG. On the other hand, VL
An electronic circuit 41 (see FIG. 1) such as an SI chip is mounted, and a cutout portion 44 formed in a part of the circuit board 40 is provided.
As shown in FIG. 2, a plurality of light emitting and receiving elements 42 arranged at the same pitch as the pitch between the core layers 21 in the thickness direction of the optical data bus main body 20 are provided on the mutually opposing lateral end faces 44a and 44b. Are arranged. Each of these light emitting / receiving elements 42 is provided with a laser diode 42a and a photodiode 42b. An electric signal input / output terminal 43 is arranged at a lower end of the circuit board 40.

In the present embodiment, just by correctly mounting the circuit board 40 to the board connector 30 in this manner, the electrical connection with the electrical wiring 11 on the support board 10 and the connection with the optical data bus 12 are established. Optical coupling is completed. FIG. 4 is a sectional view of the signal processing device shown in FIG. The laser diode 42a of the light emitting / receiving element 42 on the circuit board 40 emits pulsed light carrying a signal, and passes through the signal light incident portion 24a of the optical data bus 12 to the core layer 21 of the optical data bus main body 20. Incident. The light incident on the core layer 21 propagates through the core layer 21 and reaches the signal light emitting portion 24b located at a position facing the signal light incident portion 24a, and is detected by the photodiode 42b of the light emitting and receiving element 42 on the circuit board 40. You.

Here, from the laser diode 42a on the end face of the circuit board 40, signal light representing an address and signal light representing data enter the same core layer 21 in time series. Specify the data receiving side with the first address signal light,
Only the designated circuit board 40 receives the next data signal light. Such transmission and reception of the signal light are performed in parallel in each of the laminated core layers 21. Here, the transmission / reception timing of the signal light via each core layer 21 is synchronized with the clock signal light given to a certain layer of the plurality of core layers 21, so that the signal light passes through each core layer 21. The signal light transmitted and received is uniformly defined as a parallel signal. Further, in the present embodiment, the data bus width is set to 32 bits, and each layer of the stacked core layers 21 is configured to correspond to each 1 bit. Therefore, presentation of an address and transmission / reception of data are performed via the 32 core layers 21. In the case where the bus width is further increased, for example, when the data bus width is 64 bits, the core layer 21 may have 64 layers. However, a configuration in which two or more bits correspond to one layer of the laminated core layers 21 and a configuration in which two or more layers of the laminated core layers 21 correspond to one bit are also possible. .

In the above embodiment, polymethyl methacrylate (PMMA) is used as the core layer 21.
Alternatively, a plastic material having similar optical properties, such as polystyrene (PS) and polycarbonate (PC), can be used. As the core layer 21,
Even when polystyrene (PS) or polycarbonate (PC) is used, the cladding layer 22 can be made of a fluorine-containing polymer.

In the above embodiment, the sheet thickness of each of the core layer and the cladding layer including the light shielding layer is 0.5 mm.
However, as long as the optical characteristics are not impaired, there is no problem if the thickness is larger or smaller. By forming each layer thin, an optical data bus having an extremely wide bus width is formed in a small space, and therefore, a data transmission rate can be dramatically improved.

Further, in the above embodiment, the core layer 21,
Although a plastic material was used as the cladding layer 22,
It is also possible to use a quartz glass material instead of a plastic material. When a quartz glass material is used, P ₂ O ₅ , Al ₂ O ₃ , B ₂
It is preferable to produce a sheet having a specific refractive index control by using O ₃ or the like, and use a combination having a large difference in refractive index.

Further, in the above embodiment, after each single-layer sheet such as the core layer 21 and the cladding layer 22 is prepared in advance, the laminated structure is formed by pressure bonding or the like. It is also possible to continuously form a desired laminated structure in a vacuum film forming apparatus such as a vapor deposition method and a plasma polymerization method,
Further, a desired laminated structure can be formed by a spin coating method or a roll coating method using a material obtained by dissolving these constituent substances in a solvent.

Further, the optical data bus body 20 according to the present embodiment may have a structure in which a light scatterer is arranged at the signal light incident portion of each core layer, and the core layer corresponding to the emission window of the laser diode 42a. The signal light incident portion may be provided with a scattering optical element, for example, a light dispersing lens. Furthermore, in this embodiment, the light emitting / receiving element 42 (laser diode 42a and photodiode 42b) on the circuit board 40 is directly optically coupled to the optical data bus 20, but an optical waveguide is provided on the circuit board 40. It is also possible to form such a structure that a light emitting element or a light receiving element is directly provided at the other end of the optical waveguide.

FIG. 5 is a schematic configuration diagram of another embodiment of the signal processing device of the present invention. In the signal processing device shown in FIG. 5, a plurality of board connectors 30 are provided on the support board 10, and a plurality of circuit boards 40 are fixed to the support board 10 by the plurality of board connectors 30. A U-shaped optical data bus 12 ′ is arranged adjacent to the plurality of circuit boards 40. As shown in FIG. 5, the U-shaped optical data bus 12 'has a structure in which core layers 21 and clad layers 22 are alternately stacked. By forming the optical data bus 12 ′ in such a U-shaped structure, each pair of light emitting and receiving elements 42 provided on the side end surface 40 a of each circuit board 40 can be connected by an optical transmission line.

Incidentally, in order to reduce the crosstalk between the core layers 21, the cladding layer 22 between the core layers 21 may be formed as two layers, and the light shielding layer 23 may be formed therebetween. Further, in the above embodiment, the example in which the optical data bus is formed in a flat plate shape or a U-shape has been described, but the shape of the optical data bus and the shape of the entire signal processing device are limited to these specific shapes. is not.

[0031]

As described above, according to the optical bus of the present invention, the signal light enters the optical bus and propagates in the optical bus, so that the optical bus is resistant to environmental changes such as temperature change and dust. It is expensive and does not generate electromagnetic noise due to the optical bus unlike the electric signal transmission bus.

According to the signal processing device of the present invention, the output signal light from one circuit board is simultaneously transmitted to all the other circuit boards via the optical bus, so that the signal transmission between the circuit boards is performed. Is completed only by performing light / electric conversion and electric / light conversion once. In addition, the circuit board can be freely attached and detached to expand the system. In this case, there is no need to use a special short-circuit connector or the like in an empty slot, and a highly expandable system can be configured. it can.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical bus according to an embodiment of the present invention, which includes a sheet optical data bus and a plurality of circuit boards optically connected to each other by the sheet optical data bus. It is a schematic structure figure of one embodiment of a device.

FIG. 2 is a partially enlarged view of a support substrate and an optical data bus main body of the signal processing device shown in FIG.

FIG. 3 is a partially enlarged view of a circuit board of the signal processing device shown in FIG.

FIG. 4 is a cross-sectional view of the signal processing device shown in FIG.

FIG. 5 is a schematic configuration diagram of another embodiment of the signal processing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Support board 11 Electrical wiring 12 Optical data bus 20 Optical data bus main body 21 Core layer 22 Cladding layer 23 Light shielding layer 24a Signal light incidence part 24b Signal light emission part 30 Board connector 40 Circuit board 40a Side end face 41 Electronic circuit 42 Throw Light receiving element 42a Laser diode 42b Photodiode 43 Electric signal input / output terminal 44 Notch 44a, 44b Lateral end face

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location H04L 12/40 (72) Inventor Masao Funada 430 Nakaicho Sakai, Ashigara-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Takashi Ozawa 430, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. A plurality of signal light input sections for receiving signal light, a plurality of signal light output sections for outputting signal light, and a signal light incident from the signal light input section directed to the signal light output section. An optical bus main body formed in a sheet shape, and the signal light incident portion and the signal light emitting portion are formed on an end face of the optical bus main body, and the signal light incident portion and the signal An optical bus, wherein a light emitting portion is formed at a position facing the optical bus main body. 2. The optical bus body according to claim 1, further comprising: a core layer for transmitting signal light, and a cladding layer sandwiching the core layer and having a lower refractive index than the core layer. The optical bus according to claim 1, wherein: 3. The optical bus according to claim 2, wherein the optical bus main body has a plurality of core layers laminated with the clad layer interposed therebetween. 4. A base, a signal light emitting end for emitting signal light, an electronic circuit for generating a signal to be carried by the signal light emitted from the signal light emitting end, a signal light incident end for receiving the signal light, and A plurality of circuit boards on which at least one of an electronic circuit that performs signal processing based on a signal carried by the signal light incident from the signal light incident end is mounted; A plurality of signal light incident portions, a plurality of signal light emitting portions responsible for emitting the signal light, and a sheet-shaped light for propagating the signal light incident from the signal light incident portion toward the signal light emitting portion A bus main body, wherein the signal light incident portion and the signal light emitting portion are formed on an end surface of the optical bus main body, and the signal light incident portion and the signal light emitting portion sandwich the optical bus main body. Light bar formed at the position facing And placing the circuit board on the base with the signal light emitting end and the signal light incident end mounted on the circuit board being coupled to the optical bus at the signal light incident section and the signal light emitting section, respectively. A signal processing device, comprising: a plurality of substrate fixing portions for fixing the substrate.