JPH10206677A - Optical bus and signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical bus which freely attaches or removes a circuit substrate without requiring fine optical positioning during attaching plural circuit substrate to the optical bus to construct a signal processor, has high light availability, and can speedily transmit a signal, and provide a processor which performs signal processing such as data transmitting/receiving using the optical bus. SOLUTION: A signal processor includes a signal light incident part 15 where a signal light 70 is incoming into an optical bus 10, signal light outgoing parts 16a-16d which outgoes income and propagated signal light, a light diffuser 18 which diffuses signal light 70 toward a light transmitting layer 12, and light path changing part 19 which changes a light path of at least a part of the diffused signal light such that the light goes in the more parallel direction of the sheet plane of the optical bus 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like optical bus for transmitting an optical signal, and a signal processing apparatus 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. As the number of signal connections to each circuit board increases as circuit functions increase, a data bus board (mother board) that connects each circuit board (daughter board) with a bus structure requires a large number of connectors and connection lines. Parallel architecture has been adopted. The operation speed of the parallel bus has been improved by increasing the parallelism by increasing the number of connection lines and miniaturization, but the processing speed of the system has been reduced due to the signal delay caused by the capacitance between the connection lines and the resistance of the connection lines. It may be limited by the operating speed of the bus. In addition, electromagnetic noise (E
MI: Electromagnetic Interf
issue also becomes a major 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
April 93, pp. 52-55 ", various forms of technology 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,
No. 41042 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 a light-emitting / light-receiving device is provided on both 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, signal light sent from a certain circuit board is subjected to optical / electrical conversion on an adjacent circuit board, and is further subjected to electrical / optical conversion on that circuit board. Each circuit board is sequentially arranged in series such as sending out light, and photoelectric conversion and electric / electrical conversion are performed on each circuit board.
The light is transmitted between all the circuit boards incorporated in the system frame while repeating the light conversion. 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. In addition, since data transmission between each circuit board uses optical coupling via a free space by a light receiving / light emitting device arranged on each circuit board, it is arranged on both front and back sides of an adjacent circuit board. It is necessary that the light emitting / receiving devices are optically aligned and all the circuit boards are optically coupled. Further, since the respective circuit boards are connected via a free space, interference (crosstalk) between adjacent optical data transmission lines occurs, and poor data transmission is expected. Also,
It is also anticipated that data transmission failure will occur due to the diffusion of the signal light due to the environment in the system frame, such as dust. Furthermore, since the circuit boards are arranged in series, if any one of the boards is removed, the connection will be interrupted there. Therefore, an extra circuit board is required to compensate for the disconnection. That is, there is a problem that the circuit board cannot be freely attached and detached, and the number of circuit boards is fixed. In addition, since each circuit board is coupled via free space, interference (crosstalk) between adjacent optical data transmission lines occurs, and data is diffused due to the diffusion of signal light due to the environment in the system frame, for example, dust. It is expected that transmission failures will occur.

In addition to these, as a data transmission technique between circuit boards, Japanese Patent Publication No. Hei 6-93051 discloses a technique in which a plate having two parallel surfaces and opposed to a light source is provided and arranged on the plate surface. A method of optically coupling between circuit boards via an optical path formed by a diffraction grating and a reflective element is disclosed. In this method, since the optical coupling is performed by the diffraction grating and the reflection element arranged on the plate surface, it is necessary to precisely optically align the circuit board and the diffraction grating and the reflection element arranged on the plate surface. In addition, since it is necessary to form a diffraction grating and a reflection element on the plate surface, there is a problem that a significant increase in cost is likely to occur. Further, light emitted from one point can be transmitted to only one fixed point, and there is a great restriction on arrangement that all circuit boards cannot be exhaustively connected like an electric bus. . Further, since the connection information between the circuit boards is determined by the diffraction grating and the reflective element arranged on the plate surface, the circuit boards cannot be freely attached and detached, and there is a problem that the degree of freedom of arrangement is small.
In addition, there are various problems such as interference (crosstalk) between adjacent optical transmission lines due to the displacement of the optical element, and data transmission failure is expected.

As means for solving these problems, a light diffusion section for diffusing incident signal light is provided in an optical transmission layer of a sheet-like optical bus, and the signal light diffused by the light diffusion section is dispersed in the optical transmission layer. An optical bus system that propagates light in all directions is conceivable. In this optical bus system, a plurality of circuit boards having a light receiving / emitting section can be securely optically coupled by a simple mounting method without requiring precise optical alignment. In addition, in this method, the number of circuit boards to be attached to the optical bus and the attachment position can be freely changed.
A highly scalable and highly flexible system can be constructed. Also, unlike the method of transmitting light through space,
Since light is transmitted through the light transmission layer, environmental problems due to airborne dust and the like are unlikely to occur. Furthermore, since the optical board does not need to be optically aligned when attached to the optical data bus, it has an advantage that it is resistant to temperature changes.

However, in the above-described method, the light diffusion unit provided in the light transmission layer diffuses the signal light in all directions.
There is a problem that a large amount of signal light escapes to the outside of the optical transmission layer, a small amount of signal light reaches the light receiving unit, and the light use efficiency is low. Therefore, it is necessary to use a high output light emitting element for the signal light output unit and a high sensitivity light receiving element for the signal light input unit, and it is difficult to reduce the power consumption and cost of the signal processing device. .

Also, the optical path length of the signal light propagating in the optical transmission layer and arriving at the light receiving portion varies depending on the angle of the signal light diffused by the light diffusing portion, and the time required for each signal light to reach the light receiving portion. Therefore, there is a problem that a delay occurs between the diffused signal lights and a transmission failure occurs when the signal light carries a high-frequency signal. Therefore, it is difficult to increase the speed of the signal processing device.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention allows a circuit board to be freely attached and detached without requiring precise optical alignment when configuring a signal processing device by attaching a plurality of circuit boards to an optical bus. An optical bus with high light utilization efficiency and high-speed signal transmission, and using the optical bus,
It is an object to provide a signal processing device that performs signal processing including transmission and reception of data.

[0010]

An optical bus according to the present invention that achieves the above object has an optical transmission layer having a relatively large refractive index,
Relatively small refractive index, comprising a clad layer sandwiching the optical transmission layer, a sheet-shaped optical bus responsible for the propagation of signal light, a signal light incident portion where the signal light is incident on the optical bus, A signal light emitting unit for emitting the incident and propagated signal light,
On the optical path of the signal light incident from the signal light incident portion, while including a light diffuser for diffusing the signal light incident from the signal light incident portion into the optical transmission layer, after being diffused by the light diffuser An optical path changing unit that changes an optical path of at least a part of the signal light so as to advance at an angle more parallel to a sheet surface of the optical bus is provided.

Here, the signal light incident portion is provided on the front surface of the optical bus, and the light diffuser is disposed on the optical path of the signal light incident from the signal light incident portion, the front surface or the back surface of the optical transmission layer. And the optical path changing portion is formed on the back or front surface of the optical transmission layer facing the light diffuser in the vicinity of the signal light incident portion. It is preferable to have an inclined surface which is depressed toward the opposite surface side.

Further, the optical path changing portion has an inclined surface formed on the back surface or the front surface of the optical transmission layer, the inclined surface gradually increasing as approaching the center of the signal light incident portion. It is also a preferred embodiment, when the length of the inclined surface from the center of the signal light incident portion in the sheet direction is L, the thickness of the light transmission layer is W, and the critical angle of the light transmission layer is θ, the sheet It is also preferable that the size of the inclined surface is increased so that the length L in the direction satisfies the formula L ≧ W × tan θ, and further, the surface of the inclined surface is
The light reflecting film may be formed directly on the surface of the inclined surface.

Further, the signal light incident portion is provided at an end face of the optical bus, and the light diffuser is provided at a position on the optical path of the signal light incident from the signal light incident portion, in contact with the end face of the optical transmission layer. In a preferred embodiment, the optical path changing unit is provided near the end face of the light transmission layer on the light diffuser side, and has a tapered surface that reduces the thickness of the light transmission layer toward the end face. One, the optical path changing portion is formed near the end face of the light transmission layer on the light diffuser side,
The tapered surface may have a shape in which the taper angle gradually increases toward the end face.

When the length in the sheet direction of the tapered surface from the end face on the side of the light diffuser is L, the thickness of the light transmission layer is W, and the critical angle of the light transmission layer is θ, the sheet direction is It is also preferable that the size of the tapered surface is increased so that the length L satisfies the formula L ≧ 1/2 (W × tan θ). Further, the surface of the tapered surface is in direct contact with air. And a light reflection film may be formed on the surface of the tapered surface.

According to another aspect of the present invention, there is provided a signal processing apparatus comprising: a base; a signal light emitting end for emitting signal light; and a circuit for generating a signal to be carried by the signal light emitted from the signal light emitting end. A plurality of circuit boards on which at least one of a signal light incident end for receiving signal light and a circuit for performing signal processing based on a signal carried by the signal light incident from the signal light incident end; A sheet-like optical bus having a relatively high refractive index and a cladding layer sandwiching the optical transmission layer, which has a relatively low refractive index, and is fixed to the optical bus. A signal light incident portion for inputting the signal light to the optical bus, and a signal light emitting portion for emitting the incident and propagated signal light. The signal light is incident on the optical path of the signal light incident from the signal light incident portion. The signal light incident from the light entrance is A light diffuser for diffusing the light into the layer is provided, and an optical path of at least a part of the signal light after the light is diffused by the light diffuser is more parallel to the sheet surface of the optical bus. An optical bus having an optical path changing unit that changes so as to advance, and the circuit board, wherein the signal light emitting end or the signal light incident end mounted on the circuit board is the signal light emitting unit and the signal light emitting unit. A plurality of substrate fixing portions for fixing on the base are provided so as to be coupled to the optical bus.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a first embodiment of the optical bus of the present invention, and FIG. 2 is a cross-sectional view of the optical bus of FIG. As shown in FIGS. 1 and 2,
The optical bus 10 includes an optical transmission layer 1 having a relatively large refractive index.
2 and a clad layer 13a, 13b having a relatively small refractive index sandwiching the optical transmission layer 12. A signal light incident portion 15 is provided on the optical bus 10, and a signal light 70 emitted from a laser diode 80 disposed above the optical bus 10 enters the optical bus 10 from here. The signal light 70 is located on the optical path of the signal light 70 incident from the signal light incident portion 15 and in contact with the back surface of the optical transmission layer 12.
A light diffuser 18 for diffusing light into the light transmission layer 12 is provided.

Further, on the front surface 12a of the optical transmission layer 12 near the signal light incident portion 15 near the signal light incident portion 15, the rear surface 10
An optical path changing portion 19 having an inclined surface 19a depressed toward the side b is provided. The inclined surface 19a is the light transmission layer 12
Of the signal light 70 after being diffused by the light diffuser 18 by the inclined surface 19a.
The optical path of at least a part of the signal light is changed so as to advance at an angle more parallel to the surface 10a (sheet surface) of the optical bus 10.

In this embodiment, the size of the optical path changing portion 19 is formed so that the radius is 2.8 mm and the angle α of the inclined surface 19a is 20 °. In this embodiment,
At the center of the depressed inclined surface 19a of the optical path changing part 19,
A plane 19b parallel to the back surface 10b of the optical bus 10 is formed so that the signal light 70 incident from the signal light incident portion 15 reaches the light diffuser 18 straight.

On each end face of the optical bus 10, there are signal light emitting portions 16a, 16b, 16c and 16d, and a photodiode 81 arranged at a position facing the signal light emitting portions 16a, 16b, 16c and 16d. The signal light 70 is emitted toward the. The optical transmission layer 12 includes the signal light 7
This layer is responsible for transmission of 0, and in this embodiment, polymethyl methacrylate having a high light transmittance and a thickness of 1 mm is used. Instead of polymethyl methacrylate, a plastic material having the same optical characteristics as polymethyl methacrylate, such as polystyrene or polycarbonate, can be used, or a quartz glass material can be used.

The cladding layers 13a and 13b are formed of the light transmission layer 1
By totally reflecting light on the front surface 12a and the back surface 12b of the light transmission layer 12 which is the interface with the light transmission layer 2, and preventing dust and moisture from adhering to the front surface 12a or the back surface 12b of the light transmission layer 12, It is a layer having a function of suppressing the signal light in the transmission layer 12 from leaking out of the light transmission layer 12, and is made of a material having a light refractive index smaller than that of the material used for the light transmission layer 12. Since polymethyl methacrylate having a light refractive index of 1.49 is used for the light transmission layer 12 of this embodiment, the cladding layers 13a and 13b have a lower refractive index than that of polymethyl methacrylate.
A fluorine-containing polymer having a light refractive index of 1.40 is used. Therefore, in this embodiment, the critical angle between the optical transmission layer 12 and the cladding layer 13a is about 70 °, and the angle from the inside of the optical transmission layer 12 to the front surface 12a and the rear surface 12b of the optical transmission layer 12 is the critical angle θc Only the above signal light repeats total reflection and can propagate in the optical transmission layer 12. The material of the cladding layers 13a and 13b is not limited to the fluorine-containing polymer, and any material may be used as long as it has a lower refractive index than the material used for the light transmission layer 12. Can be.

The light diffuser 18 is a portion for diffusing light. In this embodiment, a reflection type diffusion sheet used for a liquid crystal backlight is attached to the back surface 2b of the light transmission layer 12. Note that any material that can diffuse light can be used instead of the diffusion sheet. Next, the operation of the optical bus 10 will be described.

When a signal light 70 carrying a signal is emitted from a laser diode 80 disposed above the signal light incident portion 15, the signal light 70 is transmitted from the signal light incident portion 15 to the optical bus 1.
0, and passes through the cladding layer 13a and the light transmission layer 12 to reach the light diffuser 18 formed on the back surface 12b of the light transmission layer 12. The signal light 70 that has reached the light diffuser 18 is reflected by the light diffuser 18 while being diffused toward the surface 12 a of the light transmission layer 12. In this embodiment, since the critical angle between the optical transmission layer 12 and the cladding layer 13a is 70 °, the diffusion angle θ between the normal direction of the surface 12a of the optical transmission layer 12 and the normal direction of the surface 12a is in the range of 90 ° to 70 °. The signal light 70a is totally reflected on the surface 12a of the optical transmission layer 12 and propagates in the optical transmission layer 12 as the signal light 70a '. When the optical path changing unit 19 does not exist, the signal light having an angle θ to be diffused of 70 ° or less is transmitted from the surface 12 a of the optical transmission layer 12 to the optical bus 1.
However, in this embodiment, the optical path changing unit 19
Is provided, the diffusion angle θ is 70 ° to 5 °.
The signal light 70b in the range of 0 ° is incident on the inclined surface 19a at an angle θ + α having a critical angle of 70 ° or more, and is totally reflected by the inclined surface 19a. The totally reflected signal light 70b 'is
The optical path is changed to a direction obtained by adding an angle twice the angle α between the light transmission layer 9a and the surface 12a of the light transmission layer 12 and the critical angle between the light transmission layer 12 and the cladding layer 13a becomes 70 ° or more. 12, the light is totally reflected and propagated.

In the present embodiment, the angle α between the inclined surface 19a and the surface 12a of the optical transmission layer 12 is set to 20 ° with respect to the critical angle of 70 °, so that the optical path changing unit 19 changes the signal light and the optical path to be changed. The range of the diffusion angle θ of the signal light that does not require an optical path change is 90 ° to 70 ° and 70 °
°, but it is not always necessary to make the angle ranges of these two continuous as described above.
In this case, the angle α of the inclined surface 19a may be set in accordance with the intensity distribution of the signal light diffused in accordance with the range of the angle θ where the intensity is larger.

The signal light 70a propagating in the optical transmission layer 12
70a ', ..., 70b, 70b', ... are a plurality of signal light emitting portions 16a, 16a,
Light beams 16b, 16c, and 16d are respectively emitted, and are received by photodiodes 81 arranged at positions facing the signal light emitting portions 16a, 16b, 16c, and 16d.

As described above, in the present embodiment, the light diffuser 1
Of the signal light that is diffused by the optical path changing unit 1, the signal light that escapes from the optical transmission layer 12 if the optical path changing unit 19 does not exist, and the diffusion angle θ is in the range of 50 ° to 70 ° is also
9, the optical path is changed to a direction in which total reflection is performed without reflection loss, and the signal light emitting portions 16a, 16b, 16c, 16 are changed.
d, and the light transmission efficiency can be improved.

In this embodiment, the signal light incident portion 15
Assuming that the length of the inclined surface 19a from the center in the sheet direction is L, the thickness of the optical transmission layer 12 is W, and the critical angle of the optical transmission layer 12 is θ, the length of the inclined surface 19a of the optical path changing unit 19 in the sheet direction is as follows. It is preferable that the length L is set so as to satisfy Expression (1). L ≧ W × tan θ (1) Since the inclined surface 19a is a concave side wall surface having a size of several mm, precision cutting technology and grinding technology used for manufacturing a curved surface such as an optical lens. It can be easily and inexpensively formed on the optical transmission layer 12 by using a polishing technique and the like. The cladding layers 13a and 13b can be formed by a coating method after forming the optical path changing portion 19 in the light transmission layer 12.

Next, a second embodiment of the optical bus of the present invention will be described. FIG. 3 is a partial sectional view of a second embodiment of the optical bus of the present invention. Since the optical bus 20 of the second embodiment shown in FIG. 3 has the same parts as the optical bus 10 of the first embodiment shown in FIGS. 1 and 2, different parts will be described below. I will explain mainly.

In the second embodiment, the light diffuser 28 is disposed at a position in contact with the surface 22a of the light transmission layer 22 on the optical path of the signal light 70 incident from the signal light incident part 25, and Is transmitted through the optical transmission layer 22 and diffused into the optical transmission layer 22, and is formed by attaching a transmission type diffusion sheet used for a liquid crystal backlight to the surface 22 a of the optical transmission layer 22. You.

Further, the optical path changing unit 29 includes the signal light incident unit 2
The structure has an inclined surface 29a which is formed on the back surface 22b of the optical transmission layer 22 in the vicinity of 5 and is depressed toward the surface 20a side of the optical bus 20 toward the center of the signal light incident portion 25. The light transmission layer 22 has a thickness of 1 m as in the first embodiment.
m of polymethyl methacrylate and the cladding layer 23 are also formed by using a fluorine-containing polymer similarly to the first embodiment, and the critical angle between the light transmission layer 22 and the cladding layer 23 is also the same as that of the first embodiment. Similarly, it is about 70 °.

Next, the operation of the optical bus of this embodiment will be described. When the signal light 70 is emitted from a laser diode (not shown) disposed above the signal light incident portion 25, the signal light 70 is transmitted through the signal light incident portion 25 to the optical transmission layer 2.
The light enters the light diffuser 28 formed on the second surface 22a.
The incident signal light 70 passes through the light diffuser 28 and diffuses into the light transmission layer 22. The optical path of the signal light 70 transmitted and diffused through the light diffuser 28 and incident on the optical transmission layer 22 is changed by the optical path changing unit 29. Optical path changing unit 29
Is formed to have a radius of 2.8 mm in this embodiment. The inclined surface 29a is formed in a shape in which the angle α formed with the back surface 22b of the optical transmission layer 22 gradually increases in the range of 20 ° to 60 ° as approaching the center side of the signal light incident portion 25.

In this embodiment, since the critical angle between the light transmission layer 22 and the cladding layer 23 is 70 °, the angle θ between the light transmission layer 22 and the normal to the back surface 22b of the light transmission layer 22 is 90 °.
The signal light 70a diffused in the range of ° to 70 ° is totally reflected on the back surface 22b of the optical transmission layer 22 and propagates in the optical transmission layer 22 as the signal light 70a '. The diffusion angle θ is 70
In the case where the optical path changing unit 29 does not exist, the signal light having a temperature equal to or less exits from the rear surface 22b of the optical transmission layer 22 to the outside of the optical bus 20. However, since the present embodiment includes the optical path changing unit 29, The signal light 70b whose diffusion angle θ is in the range of 70 ° to 30 ° is incident on the inclined surface 29a at an angle θ + α equal to or greater than the critical angle 70 °, and is totally reflected by the inclined surface 29a. The signal light 70b 'totally reflected is changed in the optical path in a direction in which an angle twice the angle α formed between the inclined surface 29a and the back surface 22b of the optical transmission layer 22 is added, and the optical transmission layer 22 and the cladding layer 2
Since the critical angle between the three becomes equal to or more than 70 °, the light propagates by totally reflecting inside the optical transmission layer 22.

The signal light 70a propagating in the optical transmission layer 22
70a ',..., 70b, 70b',... Are respectively emitted from a plurality of signal light emitting portions (not shown) formed around the optical bus 20, and face each signal light emitting portion. The light is received by a photodiode (not shown) arranged at the position. As described above, in the present embodiment, of the signal light diffused by the light diffuser 28, if the optical path changing unit 29 does not exist, the signal light escapes from the optical transmission layer 22, and the diffusion angle θ is 70 ° to 30 °. The signal light in the range can also be changed in optical path by the optical path changing unit 29 in a direction in which total reflection is performed without reflection loss and propagated to the signal light emitting unit, so that light transmission efficiency can be improved.

Next, a third embodiment of the optical bus of the present invention will be described. FIG. 4 is a partial sectional view of a third embodiment of the optical bus of the present invention. The optical bus 30 of the third embodiment shown in FIG. 4 has many parts that are the same as those of the optical bus 20 of the second embodiment shown in FIG. 3, and therefore, in the following description, only different parts will be described. .

In the third embodiment, the structure of the optical bus 30 on the back surface 32b side of the optical transmission layer 32 is different from that of the second embodiment. That is, the inclined surface 39a of the optical path changing portion 39 formed on the back surface 32b side of the optical transmission layer 32 has a rear surface of the optical transmission layer 32 within a range of 20 ° to 45 ° as approaching the center side of the signal light incident portion 35. 32b is formed in such a shape that the angle α with the second surface 32b gradually increases.
There is no cladding layer in the portion a, and the surface of the inclined surface 39a is in direct contact with air. Since the refractive index of air is 1, the critical angle of the inclined surface 39a is about 42 °. As in the second embodiment, the light transmission layer 32 is made of polymethyl methacrylate, and the cladding layer 33 is also made of a fluorine-containing polymer, similarly to the second embodiment. The critical angle θc between them is also about 70 ° as in the second embodiment.

As described above, also in this embodiment, the light transmission layer 3
Since the critical angle between the optical transmission layer 32 and the cladding layer 33 is 70 °, the signal light 70 diffused in the range of 90 ° to 70 ° with respect to the normal θ of the back surface 32b of the optical transmission layer 32.
a is a signal light 70 which is totally reflected by the back surface 32 b of the optical transmission layer 32 and
The light propagates through the light transmission layer 32 as a '. The signal light 70b in the range where the diffusing angle θ is 70 ° or less hits the inclined surface 39a at an angle θ + α at which the critical angle becomes 42 ° or more, and is totally reflected. Next, the optical path of the signal light 70b is changed to a direction obtained by adding an angle twice as large as the angle α of the inclined surface 39a, and becomes larger than the critical angle between the optical transmission layer 32 and the cladding layer 33. Is totally reflected and propagated.

In this embodiment, of the signal light diffused by the light diffuser 38, all the signal light that escapes from the back surface 32b of the light transmission layer 32 to the outside of the optical bus 30 if the inclined surface 39a does not exist is converted into an optical path. The light path can be changed in the direction in which total reflection without reflection loss is performed by the changing unit 39 and propagated to the signal light emitting unit (not shown), so that light use efficiency can be improved.

FIG. 5 is a graph showing the optical transmission efficiency of the optical bus of the present invention in comparison with the conventional method by calculation simulation. The simulation was performed on the assumption that the diffusion pattern of the signal light in the light diffuser was perfect diffusion. As shown in FIG. 5, the simulation result of the conventional optical bus A without the optical path changing part shows that when the critical angle between the optical transmission layer and the cladding layer is 40 °, the optical transmission efficiency is about 0.6, The optical transmission efficiency when the angle is 70 ° is about 0.1. On the other hand, an optical bus B provided with an optical path changing unit having a fixed angle inclined surface (corresponding to the first embodiment)
According to the simulation result, when the critical angle is 40 °,
The light transmission efficiency is about 0.92, and the light transmission efficiency when the critical angle is 70 ° is about 0.25.

Further, an optical bus C having an optical path changing portion having an angle-variable type inclined surface formed so that the angle α of the inclined surface gradually increases as approaching the center of the light diffuser.
According to the simulation results (corresponding to the second and third embodiments), the optical transmission efficiency is 1.0 when the critical angle is 60 ° or less, and the optical transmission efficiency when the critical angle is 70 ° increases to about 0.75. I have. In the optical bus C, by setting the critical angle to 60 ° or less, all signal light can be totally reflected and transmitted in the optical transmission layer.

Next, a fourth embodiment of the optical bus of the present invention will be described. FIG. 6 is a partial sectional view of a fourth embodiment of the optical bus of the present invention. The optical bus 40 of the fourth embodiment shown in FIG. 6 has many of the same parts as the optical bus 20 of the second embodiment shown in FIG. 3, and therefore, in the following description, only different parts will be described. .

In the fourth embodiment, the structure of the optical bus 40 on the back surface 42b side of the optical transmission layer 42 is different from that of the second embodiment. That is, the inclined surface 49 a of the optical path changing portion 49 formed on the back surface 42 b side of the optical transmission layer 42 is
The value of the angle α is formed so as to gradually increase in the range of 20 ° to 35 ° as approaching the center of 8.
Further, on the surface of the inclined surface 49a, a metal light reflection film 44 formed by an aluminum evaporation method or the like is provided. The light reflecting film 44 has a function of a mirror reflecting surface for the signal light 70.

In this embodiment, of the signal light 70 diffused by the light diffuser 48, the diffusion angle θ is from 90 ° to 70 °.
The signal light 70 in the range of the angle?
2b at an angle θ. Since the angle θ is equal to or greater than the critical angle 70 ° between the optical transmission layer 42 and the cladding layer 43, the light is totally reflected and propagates in the optical transmission layer 42. The signal light 70 in the range where the angle of diffusion θ is 70 ° or less first strikes the inclined surface 49 a and is reflected by the light reflecting film 44. Since the angle α of the inclined surface 49a increases as approaching the center of the light diffuser 48, the optical path is changed in a direction in which a larger angle is added to the signal light having a smaller angle θ,
Since the angle becomes equal to or larger than the critical angle between the light transmission layer 42 and the cladding layer 43, the light is totally reflected and propagated in the light transmission layer 42.

In the above embodiment, of the signal light 70 diffused by the light diffuser 48, the signal light which escapes from the light transmission layer 42 to the outside unless the optical path changing section 49 having the light reflection film 44 exists. The optical transmission layer 42 is also
Can propagate within. Therefore, the optical transmission efficiency of the optical bus can be improved. Further, in the case of the optical path changing portion 49 provided with the light reflecting film 44, the inclination angle of the inclined surface 49a can be made smaller than that of the case of only the total reflection surface composed of the light transmission layer and the cladding layer. Is increased, and the inclined surface 49a can be easily formed.

Next, a fifth embodiment of the optical bus of the present invention will be described. FIG. 7 is a schematic configuration diagram of a fifth embodiment of the optical bus of the present invention, and FIG.
It is sectional drawing seen in the A 'direction. As shown in FIGS. 7 and 8, one end surface 54 of a sheet-like optical bus 50 including an optical transmission layer 52 and a cladding layer 53 sandwiching the optical transmission layer 52.
a has a signal light incident portion 55, and the other end surfaces 54b, 54c, 54d of the optical bus 50 have signal light emitting portions 56b, 56c, 56d, respectively. A light diffuser 58 for diffusing the signal light 70 incident from the signal light incident part 55 toward the inside of the optical transmission layer 52 is provided on the optical path of the signal light 70 incident from the signal light incident part 55. The light diffuser 58 is
The incident signal light 70 is diffused and the incident signal light 70 is transmitted through the optical transmission layer 52. In the vicinity of the end surface 54a on the signal light incident side, tapered surfaces 59a and 59b having a shape in which the taper angle gradually increases toward the end surface 54a.
Is formed. Tapered surface 5
9a and 59b are a front surface 52a and a back surface 5 of the light transmission layer 52.
2b has an inclination of 15 ° (angle α). As in the first embodiment, polymethyl methacrylate and fluorine-containing polymer are used for the light transmission layer 52 and the cladding layer 53, respectively. The critical angle between the light transmission layer 52 and the cladding layer 53 is the same as in the first embodiment. About 70 °, and the end face 54a of the tapered faces 59a, 59b.
Has a length L of about 1.4 mm.

The signal light 70 emitted from the laser diode 80 disposed at a position facing the signal light incident portion 55
Is incident on the light diffuser 58 formed on the end face 54a via the signal light incident portion 55, the signal light 70 is
8, the light is transmitted while diffusing toward the light transmission layer 52, and diffuses in all directions in the light transmission layer 52. The signal light 70a whose angle β formed between the direction of diffusion and the normal direction of the end face 54a is in the range of 0 ° to 20 ° is the surface 52a of the optical transmission layer 52 first.
And collide against the back surface 52b at an angle of 90 ° -β,
Since the angle 90 ° −β is equal to or greater than the critical angle 70 ° between the light transmission layer 52 and the cladding layer 53, the light transmission layer 52
The light transmission layer 5 is totally reflected by the front surface 52a and the rear surface 52b of the
Propagation in 2

The signal light 70b whose diffusion angle β is in the range of 20 ° to 35 ° escapes from the front surface 52a and the back surface 52b of the optical transmission layer 52 to the outside of the optical bus 50 when the optical path changing portion 59 does not exist. In this embodiment, since the optical path changing unit 59 is provided, the signal light 70b first enters the tapered surfaces 59a and 59b of the optical path changing unit 59 at an angle of 90 ° -β + α having a critical angle of 70 ° or more. And tapered surface 5
The light is totally reflected at 9a and 59b. Totally reflected signal light 70b '
Is changed in the optical path in a direction obtained by subtracting twice the angle α between the tapered surfaces 59a and 59b.
Since the angle becomes equal to or larger than the critical angle between the three, the light is totally reflected and propagated in the light transmission layer 52.

In this way, the signal light propagating in the optical transmission layer 52 is emitted from the signal light emitting portions 56b, 56c, 56d formed on the end faces 54b, 54c, 54d of the optical bus 50, respectively, and the signal light emitting portion 56b , 56c, 56d are received by a photodiode 81 disposed at a position facing the same. As described above, in each of the above embodiments,
In the signal light incident on the optical bus, the signal light which escapes from the optical transmission layer to the outside unless the light diffuser and the optical path changing unit is present is transmitted by the optical path changing unit in a direction where total reflection without reflection loss is performed. Since the light path can be changed and propagated to the signal light emitting section, the light transmission efficiency can be improved.

Next, a description will be given of a sixth embodiment of the optical bus according to the present invention. FIG. 9 is a partial sectional view of a sixth embodiment of the optical bus of the present invention. The optical bus 60 according to the sixth embodiment shown in FIG. 9 includes the same parts as the optical bus 50 according to the fifth embodiment shown in FIGS. 7 and 8, and therefore, different parts will be described below. I will explain mainly.

In the sixth embodiment, the end face 6 of the optical bus 60
The structure on the 4a side is different from that of the fifth embodiment. That is, the tapered surfaces 69a and 69b of the optical path changing portion 69 formed near the end surface 64a of the optical bus 60 are different from the tapered surface of the fifth embodiment in the angle of 15 ° instead of the tapered surface of 15 °. It is formed as a tapered surface having a two-stage structure with a 5 ° portion. The light transmission layer 62 and the cladding layer 63 are made of polymethyl methacrylate and a fluorine-containing polymer each having a thickness of 1.3 mm thicker than the fifth embodiment, and a critical angle between the light transmission layer 62 and the cladding layer 63 is used. Is about 70 ° as in the fifth embodiment. In this embodiment, since a portion having an angle of 5 ° is added, the length of the tapered surfaces 69a and 69b is set so as to satisfy Expression (2), unlike Expression (1) described above. That is, assuming that the length of the tapered surfaces 69a and 69b from the end surface 64a is L, the thickness of the optical transmission layer 62 is W, and the critical angle of the optical transmission layer 62 is θ, the length L of the tapered surfaces 69a and 69b is L ≧ 1/2 (W × tan θ) (2) It is preferable that L is set to satisfy the following condition. In the present embodiment, L is set to 2.8 mm.

The signal light 70 emitted from a laser diode (not shown) disposed at a position facing the signal light incident portion 65 on the end surface 64a of the optical bus 60 is transmitted through the signal light incident portion 65 to the end surface 64a. When the signal light 70 is incident on the light diffuser 68 formed in the optical transmission layer 62, the signal light 70 is transmitted while being diffused toward the light transmission layer 62 by the light diffuser 68 and diffused in all directions in the light transmission layer 62. The signal light 70a in which the angle β formed by the direction of diffusion and the normal direction of the end face 64a is in the range of 0 ° to 10 °
First, the front surface 62a and the back surface 62b of the optical transmission layer 62
At an angle of 90 ° -β, and the angle of 90 °-
β is the critical angle 70 between the optical transmission layer 62 and the cladding layer 63
Since the angle is greater than or equal to °, the light is totally reflected on the front surface 62a and the back surface 62b of the optical transmission layer 62, and propagates in the optical transmission layer 62 while maintaining the angle of 90 ° -β.

The signal light 70b whose diffusion angle β is in the range of 10 ° to 20 ° is firstly applied to the taper surfaces 69a, 69b of the optical path changing portion 69 at an angle of 5 ° at an angle of 90 ° which is more than the critical angle of 70 °. -Β and totally reflected by the tapered surfaces 69a and 69b. The totally reflected signal light 70 b ′ is
The optical path is changed to a direction obtained by subtracting an angle of 10 ° which is twice the angle of 5 ° between the optical transmission layer 62 and the cladding layer 63.
The angle is an angle in the range of 0 ° to 10 ° which is more parallel to the sheet direction of the optical bus 60 and propagates through the light transmission layer 62 by total internal reflection.

The signal light 70c having a diffusion angle β in the range of 20 ° to 35 ° is applied to the tapered surface 6c as in the fifth embodiment.
The direction in which the optical path is changed to a direction obtained by subtracting an angle of 30 ° which is twice the angle of 15 ° of 9a and 69b and the optical path of the signal light 70c ′ is changed depends on the critical angle 70 between the optical transmission layer 62 and the cladding layer 63. The angle is an angle in the range of 0 ° to 10 ° which is more parallel to the sheet direction of the optical bus 60 and propagates through the light transmission layer 62 by total internal reflection.

As described above, according to the present embodiment, of the signal light incident on the optical bus, the signal light that escapes from the optical transmission layer to the outside unless the light diffuser and the optical path changing unit are present is removed. The light can be propagated in the optical transmission layer by the change unit, and the optical transmission efficiency of the optical bus can be improved. Further, the light can be propagated at an angle more parallel to the sheet direction of the optical bus, and the delay between signal lights can be further reduced. Thus, high-speed signal transmission can be performed.

In the fifth and sixth embodiments, similarly to the second, third and fourth embodiments, the optical path changing parts 59 and 69 are provided by the optical transmission layer 5.
The taper surfaces 59a, 59b, 69a, 69b formed near the end surfaces 54a, 64a and having a taper angle gradually increasing toward the end surfaces 54a, 64a.
The taper 59a, 59b, 69a, without forming a cladding layer on the surface of the tapered surface.
The optical path changing portions 59 and 69 may be formed so that the surface of the 69b surface directly contacts the air. Further, the tapered surface 59
It is also effective to form a light reflection film on the surfaces of a, 59b, 69a, and 69b.

Next, a signal processing apparatus of the present invention including the above-described optical bus and a plurality of circuit boards optically connected by the optical bus will be described. FIG. 10 is a schematic configuration diagram of an embodiment of the signal processing device of the present invention. As shown in FIG. 10, the signal processing device 90 includes a support substrate 91, which is an example of a base according to the present invention, an optical transmission layer 92 fixed to the support substrate 91, and a cladding layer sandwiching the optical transmission layer 92. 93, a sheet-like optical bus 94 for transmitting signal light, a plurality of circuit boards 97, and a plurality of board fixing portions 99 for fixing the circuit boards 97 on the support board 91 are provided. As the optical bus 94, a stack of a plurality of optical data buses of the present invention described above with reference to FIG. 1 is used. The signal processing device 90 is configured by mechanical and mechanical coupling.

The plurality of substrate fixing portions 99 provided on the support substrate 91 are arranged such that the signal light input / output end 98 mounted on the circuit board 97 is connected to the optical bus 94 at the signal light input / output portion 95. The circuit board 97 is fixed on the support board 91. The mechanism for fixing the circuit board 97 by the board fixing section 99 is detachable. The signal light input / output end 98 on the circuit board 97 side in this embodiment corresponds to one or both of the signal light input end and the signal light output end according to the present invention. The signal light input / output unit 95 on the side corresponds to one or both of the signal light input unit and the signal light output unit according to the present invention.

A power supply line and electric wiring 91 a for transmitting an electric signal are provided on the supporting substrate 91, and the electric wiring 91 a is fixed to each substrate via a plurality of substrate fixing portions 99. It is electrically connected to a circuit 96 on a circuit board 97 mounted on the unit 99. Each circuit board 97 has a plurality of signal light input / output ends 98 each composed of a pair of a light emitting element that emits signal light and a light receiving element that receives signal light, and signal light emitted from the signal light input / output end 98. At least one of a circuit 96 that generates a signal to be carried and a circuit 96 that performs signal processing based on the signal carried by the signal light incident from the signal light input / output end 98 are mounted.

When the circuit board 97 is mounted on the board fixing section 99, each signal light input / output end 98 is arranged at a position facing each light transmission layer 92 of the signal light input / output section 95 of the optical bus 94. The signal light emitted from the light emitting element in the signal light input / output terminal 98 enters the optical transmission layer 92 of the optical bus 94, is diffused in the optical transmission layer 92, and is dispersed in the other circuit board 9.
7 is transmitted to the signal light input / output unit 95 at a position opposite to the signal light input / output terminal 98, and is received by the light receiving element in the signal light input / output terminal 98 optically coupled to the signal light input / output unit 95. Is done.

In this manner, a plurality of circuit boards 97 are optically coupled by a plurality of optical buses 94 to constitute a signal processing device. By using the optical bus of the present invention provided with a unit, a plurality of circuit boards can be detachably mounted, a power consumption is low, and a signal processing device capable of high-speed signal processing can be configured. .

[0059]

As described above, according to the optical bus of the present invention, on the optical path of the signal light incident from the signal light incident portion,
A light diffuser that diffuses the incident signal light into the optical transmission layer is provided, and an optical path changing unit that changes the optical path of the signal light after being diffused by the light diffuser is provided. Since the signal light that escapes can be changed in the optical path in a direction in which total reflection occurs without reflection loss and propagated in the optical transmission layer, an optical bus with high light transmission efficiency can be obtained.

Further, according to the optical bus of the present invention, since the light diffuser is provided on the optical path of the signal light incident from the signal light incident portion, a plurality of circuit boards are attached to the optical bus and the signal processing device is provided. It is possible to obtain an optical bus to which a circuit board can be freely attached and detached without requiring precise optical alignment when constructing the optical bus. Further, according to the signal processing device of the present invention, efficient signal processing is performed by using the above-described optical bus having high light transmission efficiency and optically coupling this optical bus to a circuit board having a light receiving / emitting unit. be able to. Also,
The number of circuit boards optically coupled to the optical bus and the mounting position can be freely set, and a low-power consumption and high-speed signal processing device that does not require precise optical alignment can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an optical bus of the present invention.

FIG. 2 is a cross-sectional view of the optical bus of FIG.

FIG. 3 is a partial sectional view of a second embodiment of the optical bus of the present invention.

FIG. 4 is a partial sectional view of a third embodiment of the optical bus of the present invention.

FIG. 5 is a graph showing the optical transmission efficiency of the optical bus according to the present invention in comparison with the conventional method by calculation simulation.

FIG. 6 is a partial cross-sectional view of a fourth embodiment of the optical bus of the present invention.

FIG. 7 is a schematic configuration diagram of a fifth embodiment of the optical bus of the present invention.

FIG. 8 is a cross-sectional view of the optical bus of FIG.

FIG. 9 is a partial sectional view of a sixth embodiment of the optical bus of the present invention.

FIG. 10 is a schematic configuration diagram of an embodiment of a signal processing device of the present invention.

[Explanation of symbols]

10, 20, 30, 40, 50, 60 Optical buses 10a, 12a, 20a, 22a, 52a Surfaces 10b, 12b, 22b, 32b, 42b, 52b
Back surface 12, 22, 32, 42, 52, 62 Optical transmission layer 13a, 13b, 23, 33, 43, 53, 63 Cladding layer 15, 25, 35, 55, 65 Signal light incident portions 16a, 16b, 16c, 16d Signal light emitting portions 18, 28, 38, 48, 68 Light diffusers 19, 29, 39, 49, 59, 69 Optical path changing portions 19a, 29a, 39a, 49a Inclined surface 19b Parallel surface 44 Light reflecting film 54a, 54b, 54c, 54d End surfaces 56b, 56c, 56d Signal light emitting portions 59a, 59b Tapered surface 62a Front surface 62b Back surface 64a, 64b End surface 69a, 69b Tapered surface 70, 70a, 70a ', ..., 70b, 70b',
... Signal light 80 Laser diode 81 Photodiode 90 Signal processing device 91 Support substrate 91a Electrical wiring 92 Optical transmission layer 93 Cladding layer 94 Optical bus 95 Signal light input / output unit 96 Circuit 97 Circuit board 98 Signal light input / output terminal 99 Board fixing part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanori Hirota 430 Nakai-cho, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Tsutomu Hamada 430 Sakai, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Masao Funada 430 Nakaicho, Nakai-machi, Ashigara-gun, Kanagawa Prefecture Inside Fuji Xerox Fuji Xerox Co., Ltd. (72) Inventor Takashi Ozawa 430 Nakai-cho, Nakai-cho, Ashigara-gun, Kanagawa Prefecture Green Tech Nakai Inside Fuji Xerox Co., Ltd.

Claims (12)

[Claims] 1. A sheet-like optical bus having a relatively high refractive index and a relatively low refractive index, and a cladding layer sandwiching the optical transmission layer, for transmitting signal light. A signal light incident portion for inputting the signal light to the optical bus; and a signal light emitting portion for emitting the incident and propagated signal light, wherein the light of the signal light incident from the signal light incident portion is provided. A light diffuser for diffusing the signal light incident from the signal light incident portion toward the inside of the optical transmission layer on the road, and at least a part of the signal light after being diffused by the light diffuser; An optical path changing section for changing the optical path of the optical bus so as to advance at an angle more parallel to the sheet surface of the optical bus. 2. The optical signal processing apparatus according to claim 1, wherein the signal light incident portion is provided on a front surface of the optical bus, and the light diffuser is provided on a front surface or a rear surface of the optical transmission layer on an optical path of the signal light incident from the signal light incident portion. Along with the optical path changing portion, the optical path changing portion is formed on the back surface or the front surface of the optical transmission layer facing the light diffuser in the vicinity of the signal light incident portion. 2. The optical bus according to claim 1, wherein the optical bus has an inclined surface depressed toward the facing surface. 3. The optical path changing portion has an inclined surface formed on the rear surface or the front surface of the optical transmission layer, the inclination angle of which gradually increases as approaching the center side of the signal light incident portion. The optical bus according to claim 2, wherein: 4. When the length of the inclined surface from the center of the signal light incident portion in the sheet direction is L, the thickness of the optical transmission layer is W, and the critical angle of the optical transmission layer is θ, the sheet direction is Length L
3. The optical bus according to claim 2, wherein the size of the inclined surface is increased such that the following equation is satisfied: L ≧ W × tan θ. 5. The optical bus according to claim 2, wherein the surface of the inclined surface is in direct contact with air. 6. The optical bus according to claim 2, wherein a light reflecting film is formed on a surface of said inclined surface. 7. A position having the signal light incident portion on an end surface of the optical bus, wherein the light diffuser is in contact with an end surface of the optical transmission layer on an optical path of signal light incident from the signal light incident portion. Wherein the optical path changing portion is formed near the end face of the light transmission layer on the light diffuser side, and has a tapered surface that reduces the thickness of the light transmission layer toward the end face. The optical bus according to claim 1, wherein: 8. The optical path changing section has a tapered surface formed near the end face of the light transmission layer on the light diffuser side, the taper angle gradually increasing as approaching the end face side. The optical bus according to claim 7, wherein: 9. The length of the tapered surface in the sheet direction from the end surface on the light diffuser side is L, the thickness of the light transmission layer is W,
When the critical angle of the optical transmission layer is θ, the size of the tapered surface is increased so that the length L in the sheet direction satisfies the following equation: L ≧ 1/2 (W × tan θ). Item 7. An optical bus according to item 7. 10. The optical bus according to claim 7, wherein a surface of said tapered surface is in direct contact with air. 11. The optical bus according to claim 7, wherein a light reflecting film is formed on a surface of said tapered surface. 12. A base, a signal light emitting end for emitting signal light, a circuit for generating a signal carried by the signal light emitted from the signal light emitting end, a signal light incident end for receiving the signal light, and the signal A plurality of circuit boards on which at least one of a signal processing circuit based on a signal carried by the signal light incident from the light incident end is mounted; and a light having a relatively large refractive index fixed to the base. A sheet-like optical bus for transmitting signal light, comprising a transmission layer and a cladding layer sandwiching the optical transmission layer having a relatively low refractive index, wherein the signal light is incident on the optical bus. A signal light incident portion, and a signal light emitting portion for emitting the incident and propagated signal light, and the signal light incident from the signal light incident portion on the optical path of the signal light incident from the signal light incident portion. A light diffuser for diffusing the light into the light transmission layer; And an optical path changing unit that changes an optical path of at least a part of the signal light of the signal light after being diffused by the light diffuser so as to travel at an angle more parallel to a sheet surface of the optical bus. The optical bus provided, and the circuit board, in a state where the signal light emitting end or the signal light incident end mounted on the circuit board is coupled to the optical bus at the signal light incident portion and the signal light emitting portion, A signal processing device comprising: a plurality of substrate fixing portions that are fixed on the base.