JP2000249866A - Optical branching device, optical data bus, and signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the optical branching device which can prevent a defect in signal light transmission, projects signal light with nearly uniform intensity, and has high use efficiency for the light by equipping a light-transmissive medium propagating the signal light by the repetition of internal reflection, with plural projection parts which emit part of the signal light to the outside. SOLUTION: The optical branching device 10 is formed of a light-transmission medium which has a slanting surface 100 at one end and also has a uniform refractive index and is almost in a quadrangular prism shape. On the top surface 101, linear light projection parts 121 to 123 are formed which extend along the width of the optical branching device 10. The light projection parts 121 to 123 have projection opening parts formed of refracting surfaces 111 to 113 crossing the slanting surface 100 at right angles. The refracting surfaces are formed of one internal surface of a linear V groove. Light which is made incident vertically on the slanting surface 100 is totally reflected by the reverse surface 102. Part of the totally reflected light is projected from the refracting surface 111 of the light projection part 121 and the rest is totally reflected by the top surface 101 and propagated to the reverse surface 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical branching device, an optical data bus, and a signal processing device, and more particularly, to a light-transmitting medium that transmits an incident signal light, branches the light into a plurality of paths, and emits the light. And an optical data bus for inputting / outputting and transmitting signal light, and a signal processing device for performing signal processing including transmission / reception of data using the optical data 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 circuit function increases, the number of signal connections to each circuit board increases, so that a data bus board (motherboard) connecting each circuit board with a bus structure requires a large number of connectors and connection lines. A parallel architecture is employed. The operating speed of the parallel bus in the parallel architecture has been improved by promoting parallelization by increasing the number of connection lines and miniaturization.However, the signal delay caused by the capacitance between connection lines and the resistance of connection lines has led to an increase in the system speed. The processing speed may be limited by the operation speed of the parallel bus.

In addition, electromagnetic noise (EMI: Electromagnetic Interferen
The problem of ce) is also a great constraint on improving the processing speed of the system.

[0004] In order to solve the above problems and to 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 this optical interconnection technology, see Uchida, Academic Lecture Meeting on Circuit Packaging, 15CO01, pp. 201-2.
02 and H. Tomuro et al. IEEE Tokyo No.33 p. 81
86 (1994), various modes have been proposed depending on the configuration of the system.

Japanese Patent Application Laid-Open No. 2-41042 proposes an optical data transmission system using a light emitting / receiving device as an optical interconnection technique. In this optical data transmission system, light-emitting / light-receiving devices are arranged on both front and back surfaces of each circuit board, and the light-emitting / light-receiving devices on adjacent circuit boards incorporated in the system frame are spatially coupled with each other by light. A serial data bus for loop transmission between boards has been proposed.

In this method, a plurality of circuit boards are sequentially arranged in series, signal light transmitted from one predetermined circuit board is subjected to optical / electrical conversion on an adjacent circuit board, and then electrical / optical conversion is performed again. Signal light is transmitted to all circuit boards incorporated in the system frame while repeating optical / electrical conversion and electric / optical conversion on each circuit board arranged in series, such as transmitting signal light to the next adjacent circuit board. Is transmitted.

For this reason, the signal transmission speed is determined by the light / electricity conversion speed of the light receiving / light emitting device arranged on each circuit board,
And depends on the electrical / optical conversion speed and at the same time. In addition, since data transmission between the circuit boards uses optical coupling via a free space by a light receiving / light emitting device arranged on each circuit board, interference between adjacent optical data transmission paths is used. Crosstalk) may occur, and data transmission failure may occur. In addition, data transmission failure may occur due to scattering of signal light due to an environment between system frames, for example, dust or the like.

Japanese Patent Application Laid-Open No. S61-196210 proposes a method of optically coupling between circuit boards via an optical path constituted by a diffraction grating and a reflection element arranged on the surface of a plate. . In this method, light emitted from one point can be connected to only one fixed point.
It is not possible to exhaustively connect all circuit boards like an electric bus.

Further, the following techniques have been proposed for data transmission between circuit boards using an optical connection device having a branching element. JP-A-58-42333 discloses an example of data transmission between circuit boards using a plurality of half mirrors. However, when a plurality of half mirrors are used, the size of the apparatus is increased, and optical alignment with a light emitting / receiving device is required for each mirror. Also, the signal light transmitted through the half mirror has a light intensity that is approximately half of the light intensity of the incident light. There is a problem that a high light intensity cannot be obtained and signal light cannot be transmitted.

Japanese Patent Application Laid-Open No. Hei 4-134445 proposes a system in which signal light is incident from the side of a lens array in which a plurality of lenses are formed, and emitted from each lens. In this method, the closer the lens is to the light incident position, the larger the amount of emitted light becomes, so that the intensity of the emitted signal varies depending on the positional relationship between the incident position and the emitted position. Also,
Since the ratio of the light incident from the side surface passing through the opposing side surface is high, the utilization efficiency of the incident light amount is low.

Japanese Patent Application Laid-Open No. 63-1223 discloses an optical bus system using an optical fiber capable of transmitting substantially uniform signal light by sequentially increasing the branching ratio from the incident end. In addition, a method of forming a coupler applicable to such a method is described in IEEE Photonics Technology Lette.
rs, vol. 8, No. 12, December (1996). The method of forming a coupler described here branches light by a V-groove formed in an optical fiber, and it is considered that the output light amount can be adjusted by adjusting the size of the V-groove. But it is very difficult to make
There is a problem that the utilization efficiency of input light is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can prevent transmission failure of signal light, transmit incident light to an emission position, and signal light intensity emitted from the emission position. Optical branching device that is substantially uniform and has high light use efficiency, an optical data bus using the plurality of optical branching devices, and a signal processing device including the optical data bus and performing signal processing including data transmission and reception The purpose is to provide.

[0013]

In order to achieve the above object, an optical branching device according to the present invention is formed of a light-transmitting medium that propagates a signal light by repeating internal reflection, and further comprises a signal light. A plurality of emission portions provided with a plurality of emission openings that are provided with an incidence portion into which the light is incident, and a reflection portion that internally reflects the signal light, and emit a part of the incident signal light to the outside. is there.

According to the present invention, the signal light incident from the incident portion is propagated while being repeatedly reflected inside the optical branching device formed of the translucent medium. The reflecting portion for internally reflecting the signal light is provided with a plurality of emission portions for emitting a part of the incident signal light to the outside, so that the propagated light is branched by the emission portion and emitted to the outside. Is done. Further, since each of the emission sections is provided with a plurality of emission apertures, even when the light intensity distribution of the irradiation area of the incident signal light is not uniform, the emission area of each of the emission sections is not changed. Light of different portions is split and output. For this reason,
The average light intensity emitted from each emission part can be made substantially constant.

In the optical branching device according to the present invention, the position of at least a part of the emission opening of each emission part is made different with respect to the irradiation area of the incident light, so that each emission part has a different irradiation area. Can be split and output.

In order to reduce the variation in the intensity of the outgoing light, the number of outgoing openings is preferably three or more. .., Nn, where N1, N2, N3,..., Nn are the number of output apertures with respect to the output section close to the input section. Can be determined to satisfy. Also, the exit aperture is a refracting surface,
It can be composed of a prism or a reflecting surface.

In the optical branching device of the present invention, the angle of light incident on the optical branching device and the light propagating through the optical branching device are formed by forming a relay lens that reflects the incident light toward the emission portion. Since the propagation angle due to the shift and the spread of the propagation light can be corrected, the propagation of the propagation light to the emission unit can be performed more efficiently.

By arranging a plurality of the above optical branching devices in parallel, an optical data bus can be configured.

The optical data bus constructed as described above is used, and the optical data bus is provided with an electronic circuit for generating an electric signal and a signal light emitting body for converting the electric signal into signal light and emitting the signal light. At least one of a light projecting means, a signal light incident body for receiving the signal light and converting the incident signal light into an electric signal, and a light receiving means having an electronic circuit for processing the converted electric signal is mounted. By optically coupling with at least one of the light emitting means and the light receiving means of the plurality of circuit boards, the signal processing device of the present invention can be configured.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the first embodiment, the present invention is applied to a three-branch optical branching device. First,
The principle of the first embodiment will be described with reference to FIG. The light branching device 10 is formed of a substantially quadrangular prism-shaped light-transmitting medium having a uniform refractive index and having an inclined surface 100 inclined at an angle of 45 degrees with the back surface 102 at one end.

As the material of the translucent medium, a plastic material such as polymethyl methacrylate, polycarbonate, and amorphous polyolefin, or an inorganic glass can be used.

On the surface 101 of the optical branching device 10, three linear emitting portions 121, 122 and 123 are formed, each extending in the width direction of the optical branching device 10. Emitting part 12
Each of the apertures 1, 122, and 123 has an exit aperture formed of refraction surfaces 111, 112, and 113 perpendicular to the inclined surface 100 so as not to satisfy the condition of total reflection for incident light. ing. The refracting surface is formed by grinding one side of the translucent medium to form a linear V-shaped groove. When the translucent medium is made of a plastic material, the refracting surface can be manufactured by a method such as injection molding.

According to the optical branching device 10, the inclined surface 10
The light incident perpendicular to 0 is the back surface 1 of the transmitted light medium.
02 is incident at an angle of incidence equal to or greater than the critical angle, and is totally reflected by the back surface 102. Part of the totally reflected light is emitted from the refraction surface 111 of the emission unit 121 that does not satisfy the total reflection condition, and the remaining light is totally reflected by the front surface 101 of the transmission optical medium and
02. The propagated light is totally reflected again on the back surface 102, a part of the light is emitted from the refraction surface 112 of the emission part 122, and the remaining light is totally reflected on the front surface 101 and propagates toward the back surface 102. Then, the light is totally reflected again on the back surface 102 and is emitted from the refraction surface 113 of the emission unit 123.

Therefore, according to the optical branching device of the present embodiment, incident light can be branched into three.

As a light source of the light incident on the optical branching device, for example, a laser diode (hereinafter, LD530) that oscillates a laser beam having a wavelength of 680 nm can be used. As shown in FIG. 2, the field pattern of the LD 530 has a Gaussian distribution light emission intensity. Light with different intensities at different positions of the field pattern is emitted from each of the emission openings, so that the amount of emitted light varies.

For this reason, in the first embodiment, FIG.
As shown in FIGS. 4A and 4B and FIG. 4, a plurality of emission apertures are provided in each emission section to make the amount of emitted light uniform. Hereinafter, the optical branching device according to the first embodiment will be described. In FIGS. 3 and 4, parts corresponding to those in FIG.

Surface 10 of optical branching device 10 of the present embodiment
In FIG. 1, three emission portions 121, 122, and 123 each formed of three linear V-shaped grooves arranged at equal intervals are formed. Therefore, in the emission part 121, the V-groove forms an emission opening composed of three refraction surfaces 111 having the same area at equal intervals (interval twice as large as the width of the V-groove). Similarly, the three refracting surfaces 11 of the same area are also provided at intervals of twice the width of the V-groove in each of the emission portions 122 and 123.
An emission opening composed of 2, 113 is formed.

Further, as shown in FIG. 4, the width of the light emitting portion composed of three refracting surfaces is formed smaller than the major diameter of the irradiation area of the incident light (the field pattern of the LD 530 is shown in the figure). 121 is an inclined surface side end (left end)
Are provided so as to coincide with the left end of the irradiation area, and the emission section 122 is provided such that the left end is located at a position away from the left end of the emission section 121 by a distance corresponding to the width of the V-groove. Is provided at a position away from the left end of the emission section 122 by a distance corresponding to the width of the V-groove, and the end (right end) on the vertical surface side of the emission section 123 coincides with the right end of the irradiation area.
Thus, the emission units are provided such that all the refraction surfaces of the emission units, that is, the positions of the emission openings are different from each other with respect to the irradiation area of the incident light.

The emitting portion may be provided over the entire width direction of the surface 101 of the translucent medium as shown in FIG. 3B, or as shown in FIG. It may be provided at the center in the width direction of the surface 101 of the translucent medium.

According to the present embodiment, the light incident from the inclined surface 100 is emitted from the emission section 1 similarly to the first embodiment.
21, 122, 123 each refractive surface 111, 112,
The light is divided from 113 and emitted. To explain further with reference to FIG. 4, a portion corresponding to A of the irradiation area to be propagated is divided and emitted from each of the three refraction surfaces 111 of the emission unit 121, and is applied to the remaining B and C of the irradiation area. The corresponding portion is propagated while being totally reflected on the front surface 101 and the back surface 102 of the translucent medium.

Then, B of the irradiation area of the propagated light
Are the three refraction surfaces 112 of the emission unit 122.
And the portion corresponding to C in the irradiation area is emitted from each of the three refraction surfaces 113 of the emission section 123.

In the present embodiment, even when the light intensity distribution in the irradiation area is not uniform, the light from the different parts of the irradiation area is divided and output from each of the light emitting sections. The average light intensity obtained can be made substantially constant.

In the above embodiment, a three-branch optical branching device having three emission parts has been described. However, two, four or more emission parts can be provided. In the above description, the case where the refraction surface is used as the exit aperture is described, but an exit aperture such as a reflection surface or a prism may be provided instead of the refraction surface.

FIG. 5 is a graph comparing the relative output intensities of the light at the respective light-emitting portions when the number of light-emitting portions in the three-branch light branching device is 2, 3, and 4. The emission position 1 is the emission unit 121, and the emission position 2 is the emission unit 122
And the emission position 3 indicates the emission unit 123.
FIG. 6 is a graph showing a comparison of the relative output intensities of the light at the respective light-emitting portions when the number of light-emitting portions in the five-branch optical branching device having five light-emitting portions is 2, 3, and 4. FIG. 7 is a graph showing the relationship between the number of divisions in the three-branch and five-branch optical branching devices and the variation in the intensity of light emitted from each emission part. As understood from FIGS. 5 and 6, when the number of divisions of the emission section is set to 3 or more, the relative emission intensity becomes substantially constant, and as understood from FIG.
By setting the number of divisions of the light emitting portion to three or more, the variation in light intensity can be reduced, and the variation in the amount of emitted light is reduced to 10% or less when the number of divisions is three or more. Therefore, it is preferable that the number of divisions of each emission part is three or more and the number of emission openings is three or more.

In the first embodiment, FIG.
As shown in (A) and (B), the refraction surface is divided by 1 per division.
The light emitting portions 122 and 123 may be deformed so as to be increased one by one. Reference numerals 112A and 113A indicate increased refraction surfaces. In this modified example, the left end of each emission unit matches the left end of the irradiation area, and the position of a part of the refraction surface of each emission unit matches the irradiation area of the incident light. Further, in this aspect, even when the propagation light spreads due to the smoothness of the translucent medium, the light can be emitted from each emission unit.

FIG. 9A shows a second embodiment of the present invention. This embodiment is different from the first embodiment in that the number of refraction surfaces on each light exit surface is one by one. By increasing, the width of the emission part is made wider than the width of the irradiation area.

In the first embodiment described above, the left end of the emission section on the inclined surface side and the right end of the emission section on the vertical plane side are
Since it is necessary to match the end of the irradiation area, the tolerance for positional deviation between the irradiation area and the emission section is small. However, in the present embodiment, since the width of the emission section is wider than the width of the irradiation area, even if the irradiation area is shifted with respect to the emission section, light can be branched, and It is possible to increase the tolerance for positional deviation from the emission unit.

In the second embodiment, FIG.
As shown in FIGS. 8A and 8B, as shown in FIGS.
The emission units 122 and 123 may be increased one by one in the order of the emission units.

Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, relay lenses 130 projecting from back surface 102 in a convex shape are provided at three portions where total propagation light on back surface 102 of optical branching device 10 is totally reflected.
Is formed.

According to the present embodiment, the relay lens 13
With 0, it is possible to correct the angle of propagation of the incident light to the optical branching device, the propagation angle of the propagation light propagating in the optical branching device, and the propagation angle due to the spread of the propagation light. It can be performed more efficiently. This relay lens can be provided in each of the above-described embodiments and modifications.

The amount of light emitted from the emission section of the optical branching device described in each of the above embodiments and modifications is detected by guiding it to a light receiving element provided on the light emission side.
As described with reference to FIG. 7, the dispersion of the emitted light amount can be reduced to 10% or less by dividing the emission unit into a plurality. However, in order to reduce the variation of the detected light amount to 10% or less, the emitted light is reduced. This can be achieved by making the light receiving area of the light receiving element larger than the irradiation area of the above, or by condensing outgoing light on the light receiving area of the light receiving element using a condenser lens. For example, a laser beam (LD530)
And in the case of a three-branch and three-segment optical branching device in which the diameter of the light receiving area is 2 mm, the transmitted laser beam (L
D530) is adjusted to collimated light having a diameter of about 1.8 mm, and the width of one refraction surface is set to 0.2 m.
m, the variation in the detected light amount is 10%
Can be realized. In each of the above embodiments and modifications, the number of exit apertures is set to N1, N2, N3,.
.., Nn, where N1 ≦ N2 ≦ N3 ≦... ≦ Nn
There is a relationship.

An optical data bus can be formed by arranging the above-described optical branching devices in a plurality of rows in parallel. Next, an embodiment of the signal processing device of the present invention in which a plurality of circuit boards are optically connected to each other by an optical data bus configured using the above-described optical branching device will be described.

As shown in FIG. 11, this embodiment includes an optical data bus 300 in which a plurality of rows of optical branching devices 10 are fixed on a supporting substrate 200 as a base.
Also, a plurality of board connectors 40 are provided on the support board 200.
0 is fixed at a predetermined interval.

On the support substrate 200, a power supply line and an electric wiring 210 for transmitting an electric signal are provided.
The electric wiring 210 is connected to each board connector 400. In addition, the signal light incident body where the signal light is incident on the inclined surface of the optical branching device 10 constituting the optical data bus 300 and the position corresponding to the position immediately above the light emitting section, and the light emitting / receiving element as the signal light emitting body that emits the signal light A plurality of elements 520 are fixed, and a circuit board 500 having a plurality of electronic circuits 510 is mounted on the board connector 400. The electronic circuit 510 outputs an electric signal for transmission and processes the electric signal transmitted and converted via the optical data bus.

When each of the circuit boards 500 is mounted on the board connector 400, as shown in FIG. 12, each light emitting / receiving element 520 is connected to the optical branching device 1 constituting an optical data bus.
0, and the board connector 400 is electrically connected to the electronic circuit 510. The electric signal output from the electronic circuit is converted into signal light by the light emitting / receiving element and emitted. The signal light emitted from the light emitting / receiving element corresponding to the inclined surface of the light splitting device enters the optical splitting device, is split by the light splitting device, and is received by the light emitting / receiving element corresponding to the emission section of the light splitting device. The signal light received by the light emitting and receiving element is converted into an electric signal and input to an electronic circuit, and a predetermined process is performed in the electronic circuit.

In order to input and output signal light from the intermediate circuit board 500, a beam splitter 540 may be used.

According to the present embodiment, the optical data bus is constituted by providing a plurality of lines of optical branching devices which are incident from each circuit board, so that signal light can be transmitted and received between each circuit board. Become. Although an example in which signal light is transmitted and received between the circuit boards has been described above, at least one of the circuit boards has an electronic circuit that generates an electric signal and a light projection that converts the electric signal into signal light and emits the signal light. Only an element may be provided, or only a light receiving element for converting signal light incident on the circuit board into an electric signal and an electronic circuit for processing the converted electric signal may be provided.

[0048]

As described above, according to the present invention,
An optical branching device that can prevent transmission failure of signal light, transmits incident light to an emission position, and has a substantially uniform intensity of signal light emitted from the emission position, and has a high light use efficiency. It is possible to provide an optical data bus using a plurality of optical data buses and a signal processing device including the optical data bus and performing signal processing including transmission and reception of data.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an optical branching device according to the present invention.

FIG. 2 is a diagram showing an example of a field pattern of an edge-emitting laser diode.

FIG. 3A is a side view of the first embodiment of the optical branching device of the present invention, FIG. 3B is a top view, and FIG. 3C is a top view showing a modification of the emission unit.

FIG. 4 is a schematic diagram illustrating a relationship between a field pattern of a laser diode and a refraction surface of an emission unit.

FIG. 5 is a diagram illustrating a relationship between an emission position and an emission intensity when the number of divisions of an emission unit is changed in the three-branch optical branching device.

FIG. 6 is a diagram illustrating a relationship between an emission position and an emission intensity when the number of divisions of an emission unit is changed in the five-branch optical branching device.

FIG. 7 is a diagram showing a relationship between the number of divisions of an emission unit and a variation in emission intensity.

FIG. 8A is a side view showing a modification of the first embodiment, and FIG. 8B is an enlarged view of an emission section of this modification.

FIG. 9A is an enlarged view of an emission section of a second embodiment of the optical branching device of the present invention, and FIG. 9B is an enlarged view of an emission section of this modification.

FIG. 10A is a side view of a third embodiment of the optical branching device according to the present invention, and FIG. 10B is an enlarged view of a relay lens.

FIG. 11 is a perspective view of an embodiment of a signal processing circuit of the present invention.

FIG. 12 is a side view of the embodiment of the signal processing circuit of the present invention.

[Explanation of symbols]

 Reference Signs List 10 light branching device 121, 122, 123 emission part 111, 112, 113 refraction surface 520 light emitting / receiving element

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hidenori Yamada 430 Green Tech Nakai, Nakai-cho, Ashigarakami-gun, Kanagawa F-term in Fuji Xerox Co., Ltd. (Reference) 2H038 AA22 AA34 BA06 BA42

Claims (8)

[Claims] 1. A light-transmitting medium for transmitting a signal light by repeating internal reflection, an incident portion on which the signal light is incident, and a reflecting portion for internally reflecting the signal light are provided. An optical branching device, comprising: a plurality of emission units having a plurality of emission openings for emitting a part of signal light to the outside. 2. An optical branching device according to claim 1, wherein a relay lens for reflecting the incident light in the direction of said emission portion is formed. 3. The optical branching device according to claim 1, wherein the position of at least a part of the emission opening of each emission part is different from the irradiation area of the incident light. 4. The optical branching device according to claim 1, wherein the number of the emission openings is three or more. 5. When the number of the exit apertures is N1, N2, N3,..., Nn with respect to the exit section close to the entrance section, N1 ≦ N2 ≦ N3 ≦. The optical branching device according to claim 1. 6. The optical branching device according to claim 1, wherein said exit aperture is formed by a refraction surface. 7. An optical data bus comprising a plurality of optical branching devices according to claim 1 arranged in parallel. 8. An electronic circuit for generating an electric signal, a light projecting means having a signal light emitting body for converting the electric signal into a signal light and emitting the signal light, and a signal light incident and a signal light incident therethrough. A plurality of circuit boards on which at least one of a signal light incident body for converting to an electric signal and a light receiving means having an electronic circuit for processing the converted electric signal is mounted, and a circuit board according to any one of claims 1 to 6. A signal processing device comprising: a plurality of optical branching devices arranged in parallel; and an optical data bus optically coupled to at least one of the light projecting means and the light receiving means.