JP3941578B2 - Optical transmission device and optical data bus system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical transmission apparatus and an optical data bus system that use a translucent medium that transmits optical signals between a plurality of circuit boards or devices.
[0002]
[Prior art]
With the development of very large scale integrated circuits (VLSI), the circuit functions of circuit boards (daughter boards) used in data processing systems have increased significantly. As the circuit function increases, the number of signal connections to each circuit board increases. Therefore, a data bus board (motherboard) that connects each circuit board (daughter board) with a bus structure requires a large number of connection connectors and connection lines. A parallel architecture is adopted. The parallel bus has been improved by making the connection lines multi-layered and miniaturized, thereby improving the operation speed of the parallel bus. However, the processing speed of the system may be limited by the operation speed of the parallel bus due to the signal delay caused by the capacity between the connection lines and the connection line resistance. In addition, the problem of electromagnetic noise (EMI) due to the high density of parallel bus connection wirings is also a major limitation for improving the processing speed of the system. Therefore, optical interconnection, which is mainly in the trunk line system, has been applied to the field of electrical wiring between substrates.
[0003]
For example, Japanese Patent Laid-Open No. 2-41042 discloses an optical data transmission system using a light emitting / receiving device. Among them, light emitting / receiving devices are arranged on both the front and back sides of each circuit board, and light emitting / receiving devices on adjacent circuit boards incorporated in the system frame are spatially coupled with each other by light. A serial optical data bus for loop transmission has been proposed. In this method, the signal light sent from a certain circuit board is optical / electrically converted by the adjacent circuit board, and further converted by the circuit board again, and then the signal light is transmitted to the adjacent circuit board. Each circuit board is sequentially arranged in series and transmitted between all circuit boards incorporated in the system frame while repeating photoelectric conversion and electrical / optical conversion on each circuit board. For this reason, the signal transmission speed depends on the optical / electrical conversion / 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 coupling between circuit boards uses optical coupling with free space between light receiving / light emitting devices arranged on each circuit board, interference between adjacent optical data transmission paths. (Crosstalk) occurs and data transmission failure is expected. It is also expected that data transmission failure will occur due to scattering of signal light by the environment within the system frame, such as dust.
[0004]
Japanese Patent Application Laid-Open No. 61-196210 discloses a method for optically coupling circuit boards through a diffraction path disposed on the plate surface and an optical path constituted by a reflective element. In this system, since light emitted from one point can be connected to only one fixed point, all circuit boards cannot be connected comprehensively like an electric bus.
[0005]
Japanese Patent Laid-Open No. 2000-81524 discloses a technique for performing optical transmission and reception between a pair of light emitting and receiving elements on the same substrate through a through hole provided in the substrate. In this technique, communication between light emitting and receiving elements on the same surface is also realized by using two through holes and an optical waveguide. However, in this technology, it is not possible to communicate by connecting multiple chips or daughter boards like a backplane bus, and broadcast communication from one chip or daughter board to multiple chips or daughter boards. I can't.
[0006]
Several techniques have also been proposed for data transmission between circuit boards using an optical connecting device having a branch element.
Japanese Patent Laid-Open No. 58-42333 shows 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 increases, and each mirror needs to be optically aligned with the light emitting / receiving device. In addition, the transmitted light that has passed through the half mirror has almost half the light intensity with respect to the incident, so if you repeat branching and transmission multiple times, the light intensity becomes weak, and sufficient light intensity at the light receiving device is obtained. There is a problem that signal transmission becomes impossible.
[0007]
Japanese Patent Application Laid-Open No. 4-134415 discloses a system in which signal light is incident from a side surface of a lens array in which a plurality of lenses are formed and is emitted from each lens. In this method, since the amount of emitted light increases as the lens is closer to the incident position of light, there is a concern about variations in the intensity of the emitted signal due to the positional relationship between the incident position and the emitted position. In addition, since the rate at which light incident from the side faces escapes from the opposite side faces is high, the utilization efficiency of the incident light quantity is low.
[0008]
A star coupler that equalizes the intensity of the branched signal light is disclosed in Japanese Patent Laid-Open No. 9-184941. In this star coupler, generally, one end of a plurality of optical fibers is bundled and fixed, a light guide path wide enough to cover the plurality of optical fibers is brought into contact with one end face, and a light diffusing reflection means is provided on the other end face. I have.
When data transmission between circuit boards is performed using such a coupler, the number of fibers connected to the light emitting / receiving elements increases as the number of connection boards increases, which complicates the configuration and increases the size of the apparatus. Occurs.
[0009]
As a solution to the above problems, there is an optical signal transmission device described in Japanese Patent Laid-Open No. 2002-62457. This device is formed by providing a plurality of steps at one end, a translucent medium having a plurality of input / output portions for entering and exiting an optical signal, and a reflection reflected in the direction of the plurality of input / output portions. Means. Accordingly, an optical signal transmission device capable of mutual communication between a plurality of circuit boards and modules can be realized with a simple configuration.
[0010]
[Problems to be solved by the invention]
However, since a circuit board and a module having an input / output part are also directly or indirectly installed on the substrate on which the light transmitting medium is provided, there are a plurality of deviations when attaching the transparent medium to the substrate. This may cause misalignment between the light emitting / receiving portion of the light emitting element and the light emitting / receiving element provided on the circuit board or the like, the optical fiber end portion, or the like. In particular, as in the case of the optical signal transmission device described above, when an incident / exit surface of an optical signal inclined (for example, 45 degrees) to the light transmitting medium is formed at the light incident / exiting portion located at the end of the light transmitting medium. It may be difficult to use the tip of the inclined surface for positioning.
[0011]
That is, as shown in FIGS. 5A and 5B, when the concave portion 7 is provided as the dropping portion of the substrate 2 in order to fix the translucent medium 1, the inclined portion is abutted against the inner wall of the concave portion 7. When trying to position, the translucent medium 1 may be lifted according to the inclination at the time of abutting, and there is a possibility that the positional accuracy and fixation are insufficient. In particular, when the depth of the concave portion 7 is designed to be equal to or shallower than the thickness of the translucent medium 1, this problem becomes significant. In addition, as the positioning, it is conceivable to use the reflecting means side facing the entrance / exit part 9 as the abutment side, but since the reflecting means side at a position away from the entrance / exit part serves as a positioning reference, the translucent medium The manufacturing tolerance in the longitudinal direction greatly affects, and there is a possibility that the alignment accuracy with the incident / exiting portion located at the other end of the reflecting means is deteriorated.
[0012]
Accordingly, it is an object of the present invention to provide an optical transmission apparatus and an optical data bus system capable of accurately aligning a translucent medium and a light emitting / receiving element responsible for input / output of an optical signal.
[0013]
[Means for Solving the Problems]
An object of the present invention is an optical transmission device including a translucent medium having a plurality of stepped portions at one end and a light reflecting portion at the other end, wherein a positioning portion is formed on at least one of the plurality of stepped portions. This is achieved by an optical transmission device in which light incident / exit portions are respectively formed in the remaining stepped portions. Here, a light incident / exit portion can be further formed at the step portion where the positioning portion is formed. Preferably, the positioning portion has a vertical surface, and the light incident / exiting portion has an inclined surface. The positioning portion can be provided on any of the plurality of stepped portions, but it is particularly preferable that the positioning portion is provided on the center step or the lowest step. A light reflection / diffusion part may be provided instead of the light reflection part provided in the translucent medium.
[0014]
The optical data bus system according to the present invention transmits data by an optical signal using the above-described optical transmission device. The light receiving / emitting element in the optical data bus system and the translucent medium of the optical transmission device can be accurately aligned.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1A and 1B are diagrams showing an embodiment of an optical transmission apparatus according to the present invention, where FIG. 1A is a plan view and FIG. 1B is a side view. As shown in the figure, this apparatus has a plurality of step portions 11 at one end of a translucent medium 10 and a light reflecting portion 12 at the other end. Here, instead of the light reflecting portion 12, a light reflecting diffusion portion may be provided. A positioning portion 13 is formed at the lowest step of the plurality of step portions 11. The positioning portion 13 has a vertical surface 14. A light incident / exit portion 15 is formed in each of the remaining steps. Each light incident / exit section 15 has an inclined surface 16.
[0016]
In this embodiment, an optical signal incident from above the paper surface from one of the light incident / exiting portions is reflected by the inclined surface (45 degrees) 16 and propagates in the light transmitting medium 10 toward the light reflecting portion 12. After being reflected by the light reflecting portion 12, it propagates in the opposite direction, is reflected by the inclined surface 16 of each light incident / exiting portion, and is emitted upward from the paper surface from the light incident / exiting portion. The lowermost step portion is not used as a light incident / exit portion because a vertical surface for positioning is formed and no inclined surface is formed.
[0017]
Although the lengths of the plurality of step portions are described at the same pitch in the figure, the lowermost step portion is not used for optical transmission and the substrate is not attached, so it is the same as the length of the other step portions. There is no need to make it. Therefore, it is desirable to shorten the length of the lowermost step part from the viewpoint of manufacturing tolerance in the longitudinal direction or size reduction. Moreover, although the width | variety of the several level | step-difference part is described by the same pitch, since the step part of the lowest step is not utilized for optical transmission, it is not necessary to make it the same as the width | variety of other stairs. Therefore, it is desirable to narrow the width of the lowermost stepped portion from the viewpoint of light utilization efficiency within a range where there is no problem in positioning due to abutment. Since the lowermost step portion is located at the most distal portion of the translucent medium, there is an advantage that it can be easily used as a positioning portion.
[0018]
2A and 2B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a side view. As shown in the figure, this apparatus has a plurality of stepped portions 21 at one end of a translucent medium 20 and a light reflecting portion 22 at the other end. The light reflection part 22 can be replaced with a light reflection diffusion part. A positioning portion 23 and a light incident / exit portion 24 are formed at the lowermost step of the plurality of step portions 21. Light incident / exit portions 25 are formed in the remaining steps. The positioning portion 23 has a vertical surface 26, and the light incident / exiting portions 24 and 25 each have an inclined surface 27. In this figure, the widths 261 and 271 of the vertical surface 26 and the inclined surface 27 in the lowermost stepped portion 21 are described with substantially the same dimensions, but from the viewpoint of light utilization efficiency, the width 261 of the vertical surface 26. Should be smaller.
[0019]
In this embodiment, an optical signal incident from above the paper surface from one of the light incident / exiting portions is reflected by the inclined surface (45 degrees) 27 and propagates in the light transmitting medium 20 toward the light reflecting portion 22. After being reflected by the light reflecting portion 22, it propagates in the opposite direction, is reflected by the inclined surface 27 of each light incident / exit portion, and is emitted upward from the paper surface from the light incident / exit portion. Since the lowermost step portion is formed with an inclined surface as well as a vertical surface for positioning, it is also used as a light incident / exit portion.
[0020]
3A and 3B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, wherein FIG. 3A is a plan view and FIG. 3B is a side view. As shown in the figure, this apparatus has a plurality of step portions 31 at one end of a translucent medium 30 and a light reflecting portion 32 at the other end. The light reflecting portion 32 can be replaced with a light reflecting / diffusing portion. A positioning portion 33 is formed at the center of the plurality of step portions 31. The positioning portion 33 has a vertical surface 34. That is, the step portion at the center is not used as a light incident / exit portion. Light incident / exit portions 35 are formed in the remaining steps. Each light incident / exit section 35 has an inclined surface 36. When the positioning portion is provided in the central stage as described above, the distance from the positioning portion to each light incident / exiting portion can be relatively minimized, so that the manufacturing tolerance in the longitudinal direction can be reduced and the alignment accuracy is improved.
[0021]
In this embodiment, an optical signal incident from above the paper surface from one of the light incident / exiting portions is reflected by the inclined surface (45 degrees) 36 and propagates in the light transmitting medium 30 toward the light reflecting portion 32, After being reflected by the light reflecting portion 32, it propagates in the opposite direction, is reflected by the inclined surface 36 of each light incident / exiting portion, and is emitted upward from the paper surface from the light incident / exiting portion. The step portion of the central stage is not used as a light incident / exit portion because a vertical surface for positioning is formed and no inclined surface is formed.
[0022]
4A and 4B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, in which FIG. 4A is a plan view and FIG. 4B is a side view. As shown in the figure, this apparatus has a plurality of step portions 41 at one end of a translucent medium 40 and a light reflecting portion 42 at the other end. The light reflecting portion 42 can be replaced with a light reflecting / diffusing portion. A positioning portion 43 and a light incident / exiting portion 44 are formed at the center of the plurality of step portions 41. Light incident / exit portions 45 are formed in the remaining steps. The positioning portion 43 has a vertical surface 46, and the light incident / exiting portions 44 and 45 have inclined surfaces 47 and 48, respectively. In this figure, the widths of the vertical surface 46 and the inclined surface 47 in the stepped portion 41 at the center stage are described with substantially the same dimensions, but from the viewpoint of light utilization efficiency, the width of the vertical surface 46 should be smaller. desirable.
[0023]
In the present embodiment, an optical signal incident from above the paper surface from one of the light incident / exiting portions is reflected by the inclined surface (45 degrees) 48 (47), and the light transmitting medium 40 is directed toward the light reflecting portion 42. After being reflected and reflected by the light reflecting portion 42, it propagates in the opposite direction, reflected by the inclined surfaces 47 and 48 of each light incident / exiting portion, and emitted from the light incident / exiting portion upward on the paper surface. Since the stepped portion of the central step is formed with an inclined surface as well as a vertical surface for positioning, it is also used as a light incident / exiting portion. In this embodiment, a positioning portion is provided in the central stage, and since the distance from the positioning portion to each light incident / exiting portion can be relatively minimized, the manufacturing tolerance in the longitudinal direction can be reduced, and the alignment accuracy can be increased. improves.
[0024]
The optical transmission apparatus according to the present invention is suitably used for an optical data bus system. The optical data bus system includes, for example, a translucent medium, a substrate having a reference portion that engages with a positioning portion of the translucent medium, and a connection portion that connects an input / output unit that inputs and outputs an optical signal. . A plurality of translucent media can be juxtaposed. Each translucent medium is provided with a positioning portion as described above, and a member that engages with the positioning portion is provided on the substrate corresponding to each positioning portion. Also, a connector connected to the connector insertion portion on the board side so that the light emitting / receiving elements provided on one circuit board face each other on the light incident / exit portions of a plurality of light transmitting media on the board Is provided. A connector is provided for each circuit board. Here, when it is necessary to position the circuit board so as to oppose the light incident / exiting portions of a plurality of translucent media, each positioning portion is related to the positioning portion serving as a reference with respect to the reference portion on the substrate. Therefore, positioning with a plurality of light incident / exit portions can be performed with high accuracy when the circuit boards are connected.
[0025]
By configuring as described above, it becomes possible to accurately perform alignment between the translucent medium and the light emitting / receiving element responsible for the input / output of the optical signal, and the light receiving / emitting element provided on the circuit board, the module or the like. It is possible to improve the coupling efficiency.
[0026]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the optical transmission apparatus and optical data bus system which can perform alignment with a translucent medium and the light emitting / receiving element which takes in / out of an optical signal with high precision can be obtained.
[Brief description of the drawings]
1A and 1B are diagrams showing an embodiment of an optical transmission apparatus according to the present invention, where FIG. 1A is a plan view and FIG. 1B is a side view.
2A and 2B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, in which FIG. 2A is a plan view and FIG. 2B is a side view.
3A and 3B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, in which FIG. 3A is a plan view and FIG. 3B is a side view.
4A and 4B are diagrams showing another embodiment of the optical transmission apparatus according to the present invention, in which FIG. 4A is a plan view and FIG. 4B is a side view.
FIGS. 5A and 5B are diagrams for explaining alignment of a translucent medium. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Translucent medium 11 Step part 12 Light reflection part 13 Positioning part 14 Vertical surface 15 Light incident / exit part 16 Inclined surface

Claims (7)

An optical transmission device provided with a transparent medium for propagating chromatic and optical signal light reflection portion at the other end has a plurality of stepped portions at one end, the positioning unit in at least one of the plurality of step portions An optical transmission device comprising: a light incident / exit portion for an optical signal formed on each of the remaining stepped portions , wherein the width of the positioning portion is narrower than the width of the light incident / exit portion . 2. The optical transmission device according to claim 1, wherein a light incident / exit portion is further formed at the step portion where the positioning portion is formed. 3. The optical transmission device according to claim 1, wherein the positioning portion has a vertical surface and the light incident / exiting portion has an inclined surface. The optical transmission device according to any one of claims 1 to 3, wherein the positioning portion is provided in a central step of the plurality of step portions. The optical transmission device according to any one of claims 1 to 3, wherein the positioning portion is provided at a lowermost step of the plurality of step portions. 6. The optical transmission device according to claim 1, wherein a light reflection / diffusion part is provided instead of the light reflection part. An optical data bus system, wherein data is transmitted by an optical signal using the optical transmission device according to claim 1.

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