JP3635878B2 - Optical data bus, optical data bus complex, and signal processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical data bus responsible for transmission of an optical signal, and a signal processing apparatus that performs signal processing including transmission and reception of data using the optical data bus.
[0002]
[Prior art]
With the development of very large scale integrated circuits (VLSI), the circuit functions of circuit boards (daughter boards) used in data processing systems have increased significantly. As the circuit function increases, the number of signal connections to each circuit board increases. Therefore, a data bus board (motherboard) that connects each circuit board (daughter board) with a bus structure requires a large number of connection connectors and connection lines. A parallel architecture has been adopted. Although parallel buses have been improved by increasing the number of connection lines and paralleling them, parallel bus operation speeds have been improved. However, the system processing speed has been increased in parallel due to signal delays due to inter-connection wiring capacitance and connection wiring resistance. It may be limited by the operating speed of the bus. In addition, the problem of electromagnetic noise (EMI) due to the high density of parallel bus connection wirings is also a major limitation for improving the processing speed of the system.
[0003]
In order to solve such a problem and improve the operation speed of the parallel bus, it has been studied to use an in-system optical connection technique called optical interconnection. For an overview of optical interconnection technology, see “Junji Uchida, Circuit Implementation Conference 15C01, pp. 201-202 "and" H. Tomimura et al. "Packaging Technology for Optical Interconnects", IEEE Tokyo No. 33 pp. 81-86, 1994 ", various forms of technologies have been proposed depending on the contents of the system configuration. Of the conventionally proposed various forms of optical interconnection technologies, JP-A-2-41042 is disclosed. Discloses an example in which an optical data transmission method using a high-speed, high-sensitivity light-emitting / light-receiving device is applied to a data bus, in which light-emitting / light-receiving devices are arranged on both the front and back surfaces of each circuit board. 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, the signal light sent out from a certain circuit board is optical / electrically converted by the adjacent circuit board, and then this electric / optical conversion is then performed by the circuit board, and then to the adjacent circuit board. As the signal light is sent out, each circuit board is sequentially arranged in series and transmitted between all circuit boards incorporated in the system frame while repeating optical / electrical conversion and electrical / optical conversion on each circuit board. For this reason, the signal transmission speed depends on the light / electric conversion speed and the electric / light conversion speed of the light receiving / light emitting device arranged on each circuit board, and at the same time, is restricted. In addition, data transmission between circuit boards uses optical coupling with free space by light receiving / light emitting devices arranged on each circuit board, so it is arranged on both sides of adjacent circuit boards. The light emitting / receiving device is optically aligned and all circuit boards must be optically coupled. Furthermore, since each circuit board is coupled through a free space, interference (crosstalk) between adjacent optical data transmission paths occurs, and data transmission failure is expected. It is also expected that data transmission failure will occur due to scattering of signal light by the environment within the system frame, such as dust. Furthermore, since the circuit boards are arranged in series, if any of the boards is removed, the connection is interrupted there, so that an extra circuit board is required to make up for it. That is, there is a problem that the circuit boards cannot be freely attached and detached, and the number of circuit boards is fixed.
[0004]
In addition to these, as a data transmission technique between circuit boards using free space, Japanese Patent Application Laid-Open No. 61-196210 includes a plate having two parallel surfaces and facing a light source. A system is disclosed in which circuit boards are optically coupled to each other through an optical path using a free space, which is configured by a diffraction grating and a reflective element arranged in the above. In this system, there is a problem that light emitted from one point can be connected to only one fixed point and all circuit boards cannot be connected exhaustively like an electric bus. In addition, since a free space is used, a complicated optical system is required, and alignment is difficult, so that interference (crosstalk) between adjacent optical data transmission paths due to the displacement of the optical element occurs. Data transmission failure is expected. Furthermore, since the connection information between the circuit boards is determined by the diffraction grating and the reflecting element arranged on the plate surface, there are various problems that the circuit boards cannot be freely attached and detached and the expandability is low.
[0005]
As a means for solving these problems, an optical data bus using a transmission line as a common signal path by diffusing the signal light incident on the sheet-like transmission line over the entire transmission line using a diffuser is considered. It is done. If this method is used, a plurality of circuit boards having light receiving and emitting portions can be reliably optically coupled with simple attachment, and precise optical alignment is not required. In addition, the number of circuit boards and mounting positions can be freely changed, so that a highly flexible system with high expandability can be constructed. In addition, since the transmission path is used, it has the advantages of being resistant to dust and the like, and is resistant to temperature changes because it does not require optical alignment.
[0006]
[Problems to be solved by the invention]
However, in the optical data bus, since light is diffused in all directions, most of the light is emitted to places other than the edge on the emission side. Therefore, the light intensity at the light receiving portion becomes very weak, and there is a problem that speeding up and low power consumption cannot be achieved.
[0007]
In view of the above circumstances, an object of the present invention is to provide an optical data bus that has high transmission efficiency of signal light and has little variation in the amount of emitted light at the edge on the side from which the signal light is emitted.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a method of diffusing signal light using a cylindrical lens array in which a plurality of cylindrical surfaces are arranged in the longitudinal direction of the edge at the edge on the side where the signal light is incident can be considered. . By diffusing signal light using a cylindrical lens that has a sufficiently short focal length compared to the transmission distance, it is possible to have a certain degree of spread at the edge on the exit side, and the resulting spread angle θ is the cylindrical lens array Is determined by the ratio between the pitch p of the lens and the focal length f of the cylindrical lens (see FIG. 8).
[0009]
For example, when a cylindrical lens array having a refractive index of 1.5, a radius of 0.5 mm, and a pitch of 0.7 mm is used, the divergence angle is in principle ± 16.4 degrees.
In order to satisfy the so-called broadcast property that the signal light reaches the entire edge on the emission side, the width D of the edge on the emission side is set to D <p · L / f with respect to the transmission distance L of the optical transmission. However, since it is desirable that more substrates can be simultaneously connected to the data bus, it is desirable that the width D of the output side edge can be set wider. Accordingly, a wider spread angle is required.
[0010]
Therefore, the optical data bus of the present invention that achieves the above object is
A signal light incident part that is responsible for the incidence of signal light along one edge, and a signal light emission part that is responsible for the emission of signal light along the edge opposite to the one edge; A sheet-like optical data bus that propagates the signal light incident from the light incident part and emits the signal light from the signal light emission part,
A cylindrical lens array composed of a plurality of first cylindrical surfaces in which the signal light incident portion is arranged in the longitudinal direction of the edge formed on the one edge;
A plurality of second cylindrical surfaces arranged opposite to the one edge and extending along the one edge and arranged in the longitudinal direction of the one edge, and cooperating with the cylindrical lens array; And a cylindrical lens array member for diffusing the signal light into the optical data bus.
[0011]
The optical data bus complex of the present invention is
A signal light incident part that is responsible for the incidence of signal light along one edge, and a signal light emission part that is responsible for the emission of signal light along the edge opposite to the one edge; A sheet-like optical data bus that propagates the signal light incident from the light incident part and emits the signal light from the signal light output part, and the signal light incident part is formed in the longitudinal direction of the one edge formed on the one edge. A cylindrical lens array comprising a plurality of first cylindrical surfaces arranged in a row, and arranged in the longitudinal direction of the one edge that is disposed opposite to one edge and extends along the one edge. An optical data bus having a plurality of second cylindrical surfaces and a cylindrical lens array member that diffuses signal light into the optical data bus in cooperation with the cylindrical lens array is lower than the refractive index of the optical data bus Clad with refractive index The is characterized in that formed by stacking a plurality of sheets is sandwiched among each other.
[0012]
The signal processing apparatus of the present invention
Substrate,
A signal light emitting end that emits signal light, a circuit that generates a signal to be carried by the signal light emitted from the signal light emitting end, and a signal light incident from the signal light incident end and the signal light incident end from which the signal light enters A plurality of circuit boards on which at least one of a circuit for performing signal processing based on a signal carried is mounted;
A signal light incident part that is responsible for the incidence of signal light along one edge, and a signal light emission part that is responsible for the emission of signal light along the edge opposite to the one edge; A sheet-like optical data bus that propagates the signal light incident from the light incident part and emits the signal light from the signal light output part, and the signal light incident part is formed in the longitudinal direction of the one edge formed on the one edge. A cylindrical lens array comprising a plurality of first cylindrical surfaces arranged in a row, and arranged in the longitudinal direction of one of the edges arranged opposite the one edge and extending along the one edge. An optical data bus having a plurality of second cylindrical surfaces and a cylindrical lens array member that diffuses signal light into the optical data bus in cooperation with the cylindrical lens array, and the circuit board are mounted on the circuit board. Signal light emission To the signal light input end, characterized in that a plurality of substrate fixing portion for fixing on a substrate in a state that is coupled to the optical data bus in the signal light input unit to the signal light emission part.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a plan view showing a first embodiment of an optical data bus according to the present invention.
The optical data bus 100 includes a cylindrical lens array 110 in which the first cylindrical lenses 111 are arranged and a cylindrical lens array member 120 in which the second cylindrical lenses 121 are arranged. It plays the role of the signal light incident part referred to in the present invention. In addition, the optical data bus 100 includes an optical transmission unit 130 responsible for signal light propagation and a signal light emission unit 140 responsible for signal light emission.
[0014]
The optical data bus 100 is manufactured by the following manufacturing method, for example.
In this embodiment, the sheet-like light transmission unit 130 having a thickness of 0.5 mm and the cylindrical lens array 111 are made of PMMA (polymethyl methacrylate) having a high light transmittance. The optical transmission unit 130 and the cylindrical lens array 110 are prepared in advance, and the mold is heated to a temperature at which PMMA is sufficiently melted, and PMMA in a molten state that is sufficiently heated is poured into the mold, It is produced by taking out after cooling.
[0015]
The first cylindrical surface 111 does not need to be formed on the entire edge of the optical data bus, and may be formed at a position corresponding to the signal light. In addition, the cylindrical lens array 111 may be integrally combined with the optical transmission unit 130 after being manufactured by a mold independent of the optical transmission unit 130.
The material of the cylindrical lens array member 120 is also the same PMMA as that of the optical transmission unit 130 and the cylindrical lens array 110. Like the optical transmission unit 130 and the cylindrical lens array 110, a previously prepared mold is heated, and PMMA is poured into the mold. It is produced by taking out after cooling. Similar to the first cylindrical lens 111, the second cylindrical lens 121 is not necessarily formed on the entire cylindrical lens array member 120, and may be formed at a position corresponding to the signal light.
[0016]
Further, the cylindrical lens array member 120 may be movable for adjusting the distance between the first cylindrical lens 111 and the second cylindrical lens 121.
In the present embodiment, the first and second cylindrical lenses 111 and 121 are arranged at a pitch of several hundred μm, and this pitch is smaller than the beam diameter of the signal light in which the laser light from the semiconductor laser is roughly collimated by the lens. It has become.
[0017]
The signal light 200 incident on the signal light incident portion of the optical data bus 100 manufactured as described above is first refracted by the second cylindrical lens 121, further refracted by the first cylindrical lens 111, and once focused. After that it is diffused. The diffused signal light 210 is propagated through the optical transmission unit 130 to the signal light emitting unit 140.
[0018]
The spread of the signal light 210 diffused at the signal light incident part is determined by the ratio between the combined focal length f ′ of the first and second cylindrical lenses 111 and 121 and the pitch p. Assuming that the transmission distance of optical transmission is L and the width of the signal light emitting part is D, each parameter is set so as to satisfy the relationship of f ′ <p · L / D. it can.
[0019]
In addition, since the first and second cylindrical lenses 111 and 121 are arranged so as not to diffuse the signal light in the thickness direction of the optical transmission unit 130, the optical transmission unit originally included in the signal light 200 If the spread in the thickness direction of 130 is less than or equal to the total reflection condition of the light transmission unit 130, all the signal light 210 is propagated to the signal light emitting unit 140.
[0020]
FIG. 2 is a conceptual diagram showing a state of refraction of signal light by the first and second cylindrical lenses.
The signal light incident on the second cylindrical lens 121 is first refracted by the second cylindrical lens 121 and is once focused at a position that has a focal length f ₁ from the main surface of the second cylindrical lens 121. Thereafter, the light enters the first cylindrical lens 111 while diffusing, and the spread angle at this time is the angle θ ₁ shown in FIG. 2 is incident on the first cylindrical lens 111 and refracted by the first cylindrical lens 111, thereby expanding the divergence angle and corresponding to the combined focal length f ′ of the first and second cylindrical lenses 111 and 121. The angle θ ′ shown in FIG.
[0021]
When the graph is drawn with the horizontal axis as the distance d between the principal surface of the second cylindrical lens 121 and the apex of the first cylindrical lens 111 and the divergence angle θ ′ as the vertical axis, a graph rising right as shown in FIG. Become. However, the pitch p of the first and second cylindrical lenses 111 and 121 is 0.7 mm. When the distance d is greater than about 0.8 mm, the spread angle can be made larger than when a single-row cylindrical lens is used, and when the distance d is 2 mm, a maximum spread angle of about 35 degrees can be obtained. . If the interval is larger than 2 mm, the signal light diffused by the second cylindrical lens 121 is incident on the plurality of first cylindrical lenses 111, so that the spread angle cannot exceed the maximum value.
[0022]
By using the sheet-like optical data bus as described above, incident signal light can be efficiently diffused and transmitted. That is, the incident light can be efficiently transmitted to the signal light emitting unit by diffusing the incident light using the cylindrical lens, and the spread angle can be sufficiently widened by diffusing the signal light by the two cylindrical lenses. Can do. Further, the variation of the signal light is reduced in the signal light emitting part.
[0023]
FIG. 4 is a schematic configuration diagram showing a second embodiment of the optical data bus of the present invention.
In this optical data bus 300, a cylindrical lens 311 is arranged near the center of the signal light incident part 310 in a direction perpendicular to the incident direction of the signal light, and the side surface of the optical data bus 300 of the signal light incident part 310 is arranged. In the vicinity of 320, the cylindrical lens 312 is arranged so that the position of the cylindrical lens 312 shifts toward the traveling direction side of the signal light as it approaches the side surface 320. With this configuration, the signal light incident unit 310 refracts the signal light incident from a position close to one side surface of the optical data bus 300 in a direction away from the side surface. Therefore, the signal light 400 incident near the center of the signal light incident part 310 and the signal light 410 incident near the side surface of the optical data bus 300 of the signal light incident part 310 are equally distributed over the entire signal light emitting part 330. Will be diffused.
[0024]
Note that setting the width and the like of the signal light emitting unit 330 so as to satisfy the broadcast property is the same as in the first embodiment.
FIG. 5 is a schematic perspective view showing an embodiment of the optical data bus complex of the present invention. The optical data bus complex 500 includes a plurality of optical data buses 100 shown in FIG. 1, a plurality of cladding layers 600 that reflect signal light diffused in the thickness direction of the optical data buses 100, and reflection by the cladding layers 600. The optical data bus 100, the cladding layer 600, the optical absorption layer 700, the cladding layer 600, and the optical data bus 100 are arranged in order. It is laminated repeatedly. Since the optical data bus complex 500 has such a configuration, it can transmit and receive a parallel optical signal composed of a plurality of bits.
[0025]
FIG. 6 is a schematic perspective view showing an embodiment of the signal processing apparatus of the present invention.
The signal processing device 800 includes a mother board 810 which is an example of a base according to the present invention, an optical data bus complex 500 shown in FIG. 5 mounted on the mother board 810, and a plurality of circuit boards 820. On the circuit board 820, a light emitting element 821 which is an example of the signal light emitting end according to the present invention, a light receiving element 822 which is an example of the signal light incident end according to the present invention, a VLSI which performs signal processing and the like Circuit 823 is arranged. The circuit board 820 is detachable with respect to the mother board 810. When the circuit board 820 is fixed to the mother board 810, the light emitting element 821 and the light receiving element 822 are connected to the signal light incident part of the optical data bus and the board fixing part (not shown). It is fixed so as to face the signal light emitting part. Use of the optical data bus complex 500 shown in FIG. 5 facilitates alignment when the circuit board 820 is fixed on the mother board 810.
[0026]
According to the signal processing apparatus configured as described above, loss of signal light during transmission / reception can be reduced, and signal light can be transmitted / received simultaneously between a plurality of substrates, so that high speed and low power consumption are achieved. The signal processing apparatus can be realized. In addition, since the light utilization efficiency is extremely high, it is possible to cope with higher speed even with the conventional signal light.
[0027]
【The invention's effect】
As described above, according to the optical data bus of the present invention, it is possible to realize an optical data bus that has high signal light transmission efficiency and little variation in the amount of emitted light at the edge on the signal light emitting side. .
According to the optical data bus complex of the present invention, parallel optical signals composed of a plurality of bits can be transmitted and received.
[0028]
According to the signal processing apparatus of the present invention, a high-speed and low power consumption signal processing apparatus can be realized.
FIG. 1 is a plan view showing a first embodiment of an optical data bus of the present invention.
FIG. 2 is a conceptual diagram showing a state of refraction of signal light by first and second cylindrical lenses.
FIG. 3 is a graph showing the relationship between the interval between the cylindrical lenses and the divergence angle.
FIG. 4 is a schematic configuration diagram showing a second embodiment of the optical data bus of the present invention.
FIG. 5 is a schematic perspective view showing an embodiment of the optical data bus complex of the present invention. FIG. 6 is a schematic perspective view showing an embodiment of a signal processing apparatus of the present invention.
FIG. 7 is a plan view of an optical data bus having one cylindrical lens array.
FIG. 8 is a conceptual diagram showing a state in which signal light is refracted by one cylindrical lens.
[Explanation of symbols]
100, 300 Optical data bus 110 Cylindrical lens array 111 First cylindrical lens 120 Cylindrical lens array member 121 Second cylindrical lens 130 Light transmission section 140, 330 Signal light emitting section 310 Signal light incident section 311 Cylindrical lens 500 Optical data bus Composite 600 Clad layer 700 Light absorption layer 800 Signal processing device 810 Motherboard 820 Circuit board 821 Light emitting element 822 Light receiving element

Claims (5)

A signal light incident part responsible for the incidence of signal light along one edge, and a signal light emission part responsible for the emission of signal light along the edge opposite to the one edge, A sheet-like optical data bus that propagates the signal light incident from the signal light incident part and emits the signal light from the signal light emission part,
A cylindrical lens array composed of a plurality of first cylindrical surfaces in which the signal light incident portion is arranged in the longitudinal direction of the edge formed on the one edge;
A plurality of second cylindrical surfaces arranged opposite to the one edge and extending along the one edge and arranged in the longitudinal direction of the one edge, and cooperating with the cylindrical lens array And a cylindrical lens array member for diffusing the signal light into the optical data bus. 2. The optical data bus according to claim 1, wherein the cylindrical lens array member is movable for adjusting a distance between the first cylindrical surface and the second cylindrical surface. 2. The optical data bus according to claim 1, wherein the signal light incident part refracts the signal light incident from a position close to one side surface of the optical data bus in a direction away from the side surface. A signal light incident part that is responsible for the incidence of signal light along one edge, and a signal light emission part that is responsible for the emission of signal light along the edge opposite to the one edge, A sheet-like optical data bus that propagates signal light incident from a signal light incident part and emits the signal light from the signal light emission part, wherein the signal light incident part is formed on the one edge. A cylindrical lens array composed of a plurality of first cylindrical surfaces arranged in the longitudinal direction of the first lens, and a length of the one edge that is disposed to face the one edge and extend along the one edge. An optical data bus having a plurality of second cylindrical surfaces arranged in a direction and having a cylindrical lens array member that diffuses the signal light into the optical data bus in cooperation with the cylindrical lens array, Lower than the refractive index of the bus Optical data bus complex that a cladding layer having a rate characterized by formed by laminating a plurality of sheets is sandwiched among each other. Substrate,
A signal light emitting end for emitting signal light, a circuit for generating a signal to be carried on the signal light emitted from the signal light emitting end, a signal light incident end for receiving signal light, and a signal incident from the signal light incident end A plurality of circuit boards on which at least one of a circuit for performing signal processing based on a signal carried by light is mounted;
A signal light incident part responsible for the incidence of signal light along one edge, and a signal light emission part responsible for the emission of signal light along the edge opposite to the one edge, A sheet-like optical data bus that propagates signal light incident from a signal light incident part and emits the signal light from the signal light output part, wherein the signal light incident part is formed on the one edge. A cylindrical lens array composed of a plurality of first cylindrical surfaces arranged in the longitudinal direction, and the longitudinal length of the one edge that is disposed opposite to the one edge and extends along the one edge. An optical data bus having a plurality of second cylindrical surfaces arranged in a direction and having a cylindrical lens array member that diffuses the signal light into the optical data bus in cooperation with the cylindrical lens array, and the circuit board On the circuit board And a plurality of substrate fixing portions for fixing the signal light emitting end or signal light incident end on the base body in a state where the signal light emitting portion or signal light incident end is coupled to the optical data bus in the signal light incident portion or signal light emitting portion. A characteristic signal processing apparatus.

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