JP3744278B2 - Signal processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an optical data bus responsible for transmission of an optical signal and a signal processing apparatus including data transmission / reception using the optical data bus.
[0002]
[Prior art]
  With the recent 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, so a data bus board (motherboard) that connects each circuit board (daughter board) with a bus structure requires a large number of connection connectors and connection lines. A parallel architecture has been adopted.
[0003]
  Here, parallel buses have been improved by increasing the number of connection lines and making them parallel, but the operation speed of the parallel bus has been improved. The speed may be limited by the operating speed of the parallel bus. In addition, the problem of electromagnetic noise due to the increase in the density of parallel bus connection wiring is also a major limitation for improving the processing speed of the system.
[0004]
  In order to solve such a problem and to improve the operation speed of the parallel bus, use of an in-system optical connection technique called optical interconnection has been studied.
[0005]
  The outline of the optical interconnection technology is as follows: “Koji Uchida, 9th Circuit Packaging Conference 15C01, pp. 201-202 "and Hisami Tomuro et al. Current Status and Trend of Optical Interconnection Technology, IEEE Tokyo Section Denshi Tokyo No. 33 pp. 81-86, 1994 ", various forms have been proposed depending on the contents of the system configuration.
[0006]
  Among various types of conventionally proposed optical interconnection technologies, Japanese Patent Application Laid-Open No. 2-41042 discloses an example in which an optical data transmission method using a high-speed, high-sensitivity light emitting / receiving device is applied to a data bus. Has been. Here, light emitting / receiving devices are arranged on both front and back surfaces of each circuit board, and light emitting / receiving devices on adjacent circuit boards incorporated in the system frame are spatially coupled by light between the circuit boards. A serial optical data bus for transmission is described.
[0007]
  In this method, the signal light sent from one circuit board is optically / electrically converted by the adjacent circuit board, and is further converted electrical / optically by that circuit board, and the signal is then sent to the adjacent circuit board. The light is transmitted between all circuit boards incorporated in the system frame while repeating photoelectric conversion on each circuit board.
[0008]
  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, data transmission between circuit boards uses optical coupling with free space by light receiving / light emitting devices arranged on each circuit board, so it is arranged on both sides of adjacent circuit boards. Optical alignment of the light emitting / receiving devices that are being performed is required and all circuit boards must be optically coupled. Furthermore, since they are coupled through free space, interference (crosstalk) between adjacent optical data transmission paths occurs, and data transmission failure is also expected. It is also expected that data transmission failure will occur due to scattering of signal light by the environment within the system frame, such as dust. Furthermore, since the circuit boards are arranged in series, if any of the boards is removed, the connection is interrupted there, and an extra circuit board is required to make up for it. That is, there is a problem that the circuit boards cannot be freely inserted and removed, and the number of circuit boards is fixed.
[0009]
  On the other hand, a data transmission technique between circuit boards using a two-dimensional array device is disclosed in Japanese Patent Application Laid-Open No. 61-196210.
[0010]
  The technique disclosed herein includes a plate having two parallel surfaces and is opposed to a light source, and optically connects between circuit boards via a diffraction grating disposed on the plate surface and an optical path formed by a reflective element. It is a method to join to.
[0011]
  In this system, there is a problem that light emitted from one point can be connected to only one fixed point, and all circuit boards cannot be exhaustively connected like an electric bus. In addition, an integrated complex optical system using a diffraction grating and a reflecting element is required, and positioning is difficult, so that interference (crosstalk) between adjacent optical data transmission paths is caused by the positional deviation of the optical element. There is a problem that data transmission failure is expected. Furthermore, since the connection information between the circuit boards is determined by the diffraction grating and the reflecting element arranged on the plate surface, there is a problem that the circuit boards cannot be freely attached and detached and the expandability is low.
[0012]
  Another technique for data transmission between circuit boards using a two-dimensional array device is disclosed in Japanese Patent Laid-Open No. 4-134415. The technology disclosed herein includes a lens array in which a plurality of lenses having a negative curvature are formed on a surface of a transparent material having a higher refractive index than air, and light emitted from the light source. An optical data bus comprising an optical system for allowing incidence from the side surface of the lens array is described. A system using a region having a low refractive index or a hologram instead of a plurality of lenses having negative curvature is also disclosed.
[0013]
  In this system, the light incident from the side surface is distributed on the surface and emitted from the plurality of lenses having the negative curvature, the low-refractive-index region or the portion where the hologram is formed. . Therefore, it is conceivable that the intensity of the outgoing signal varies depending on the positional relationship between the incident position and a plurality of lenses, an area having a low refractive index that changes to this, and the outgoing position on the surface on which the hologram is formed. Further, it is considered that the rate at which light incident from the side faces escapes from the opposite side faces is high, and the efficiency of light used for signal propagation is low. Furthermore, since it is necessary to arrange the optical input element of the circuit board at a position of a plurality of lenses having a negative curvature formed on the surface, a low refractive index area or a hologram that changes to the lens, the circuit board is arranged. There are various problems such as low flexibility and low expandability.
[0014]
  As means for solving these problems, JP-A-10-123350 discloses a sheet-like optical data bus. Since this method diffuses and propagates the signal light incident on the common signal path, a plurality of circuit boards having light receiving and emitting portions can be reliably optically coupled by simple attachment, and precise optical Does not require manual alignment. In addition, the number of circuit boards and mounting positions can be freely changed, so that a highly flexible system with high expandability can be constructed. In addition, since the transmission path is used, it has the advantages of being resistant to dust and the like, and is resistant to temperature changes because it does not require optical alignment.
[0015]
  In the optical data bus, since light is diffused in all directions, more light is emitted to the outside without the light receiving element. Therefore, the amount of light reaching the light receiving portion is reduced and the light intensity is very weak, which causes problems in speeding up and lowering power consumption.
[0016]
  In order to solve the above problems, an optical data bus is disclosed in Japanese Patent Laid-Open No. 10-62657. In this optical data bus, signal light incident from a signal light incident portion provided on an arbitrary side of a sheet-shaped optical data bus is diffused in a light diffusion portion corresponding to each incident portion, and light composed of a core and a clad. A method of propagating to a signal light emitting unit arranged with a transmission layer interposed therebetween has been proposed.
[0017]
  In this system, signal light is emitted through a sheet-like optical transmission line by controlling the diffusion distribution of light in the light diffusion part corresponding to each incident part by arranging the signal light incident part and the signal light emitting part. Since the light can be effectively guided in the direction of the section, the transmission efficiency in the sheet-like optical data bus is improved, and the speed and power consumption can be reduced.
[0018]
[Problems to be solved by the invention]
  However, even if a method of controlling the light diffusion distribution according to the arrangement of the signal light incident part and the signal light emission part is used, the following new problem is raised and the fluctuation of the output signal due to this problem is obvious. Became.
[0019]
  That is, as shown in FIG. 9, the signal light L emitted from the light emitting element 70 is converged on the light diffusion portion 76 by the lens 74 provided on the side surface of the optical data bus main body 72. Then, the signal light L is diffused by the light diffusing unit 76, passes through the Fullel lens 78, is collected by the condenser lens 82 mounted on the circuit board 80, and is received by the light receiving element 84.
[0020]
  Here, each circuit board 80 on which the light receiving element 84 is mounted has optical data with an interval (for example, 10 mm) between the thickness of the circuit board 80 itself and the thickness of the circuit mounted on the circuit board 80. The bus main body 72 is disposed in a direction orthogonal to the light exit surface 86. Therefore, the light receiving elements 84 mounted on the circuit boards 80 are also necessarily arranged at this interval (10 mm).
[0021]
  For this reason, the distance of the circuit board 80 is sufficiently large with respect to the light receiving surface of the light receiving element 84, and a part of the signal light L (arrow in FIG. 9) diffused by the light diffusion portion 76 is not received by the light receiving element 84. It becomes useless.
[0022]
  In order to prevent this waste, when this condensing lens 82 is enlarged, there is a problem that if the optical data bus main body 72 is laminated to increase the number of bits, the lamination pitch becomes large.
[0023]
  On the other hand, if a cylindrical lens 90 having no curvature in the direction of arrow C in FIG. 10B is used and a light condensing action is provided in the direction of arrow D in FIG. If it advances, it will spread | diffuse in the direction of arrow C, and a part of signal light L will not inject into the light receiving element 84 on the circuit board 80. FIG.
[0024]
  For this reason, the light collecting effect cannot be obtained as a whole, and when the optical data bus main body 72 is stacked to increase the number of bits, the signal light L that is not incident on the light receiving element 84 is incident on another light receiving element. So-called crosstalk becomes a problem.
[0025]
  Therefore, an object of the present invention is to provide a signal processing device that can reduce loss of signal light emitted from an optical bus main body and improve light transmission efficiency.
[0026]
[Means for Solving the Problems]
  The signal processing device according to claim 1 is optically coupled to a plurality of incident light guides that propagate signal light and the incident light guide, and diffuses signal light emitted from any of the incident light guides. An optical bus main body that propagates in the optical bus main body, a plurality of output light guides that are optically coupled to the optical bus main body and propagate the signal light emitted from the optical bus main body, and a light receiving unit that receives the signal light propagated through the output light guide And a circuit board that performs signal processing based on a signal carried by the signal light, and includes a gap between adjacent output light guide paths and a difference in length between the adjacent output light guide paths. A circuit board having a light receiving portion that is set smaller and is optically coupled to an end portion of the outgoing light guide is arranged in parallel to the optical coupling surface of the optical bus body.
[0027]
  According to this configuration, the signal light emitted from the plurality of incident light guides is diffused, propagates in the optical bus body, and is emitted to the plurality of output light guides. This signal light is propagated through the outgoing light guide, and then received by a light receiving portion provided on the circuit board, and signal processing based on a signal carried by the signal light is performed.
[0028]
  Here, by providing a difference in the length of the adjacent outgoing light guides, the circuit board can be arranged in parallel to the optical coupling surface of the optical bus body at the end of the outgoing light guide.
[0029]
  Therefore, the circuit board does not become an obstacle, and it is possible to optically couple with the optical bus body by reducing the interval between the adjacent outgoing light guide paths.
[0030]
  For this reason, if the width of the optical coupling surface of the optical bus body is constant, many outgoing light guides can be optically coupled to the optical coupling surface of the optical bus body. Conversely, if the number of the outgoing light guide paths to be optically coupled is constant, the dimension in the width direction of the optical coupling surface of the optical bus body can be set small.
[0031]
  As a result, after propagating through the optical bus body, signal light that is not received by the light receiving unit and is wasted can be reduced, and transmission efficiency of signal light can be increased.
[0032]
  According to a second aspect of the present invention, a plurality of incident light guides that propagate signal light are optically coupled to the incident light guide, and the signal light emitted from any one of the incident light guides is diffused. The optical bus main body propagating in this manner and the optical bus main body are optically coupled to transmit the signal light emitted from the optical bus main body. A signal comprising: a plurality of outgoing light guides to be carried; and a circuit board that includes a light receiving unit that receives the signal light propagated through the outgoing light guides and performs signal processing based on a signal carried by the signal light. In the processing apparatus, the circuit board including the light emitting unit that sets an interval between the adjacent incident light guides to be smaller than a difference in length between the adjacent incident light guides and optically couples with an end of the incident light guide Are arranged in parallel to the optical coupling surface of the optical bus body.
[0033]
  According to this configuration, the signal light emitted from the plurality of incident light guides is diffused, propagates in the optical bus body, and is emitted to the plurality of output light guides. This signal light is propagated through the outgoing light guide, and then received by a light receiving portion provided on the circuit board, and signal processing based on a signal carried by the signal light is performed.
[0034]
  Here, by providing a difference in length between the adjacent incident light guides, the circuit board can be arranged in parallel to the optical coupling surface of the optical bus body at the end of the output light guide.
[0035]
  Therefore, the circuit board does not become an obstacle, and the interval between the adjacent incident light guides can be reduced and optically coupled to the optical bus body.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a signal processing device according to an embodiment of the present invention will be described with reference to the accompanying drawings. First, the configuration of the signal processing apparatus of the present embodiment will be described using the overall configuration diagram of the signal processing apparatus of FIG.
[0037]
  A sheet-like optical data bus main body (optical transmission layer) 14 for transmitting signal light is fixed at substantially the center of the surface of the substrate (motherboard) 12 constituting the signal processing device 10.
[0038]
  As shown in FIG. 6A, the optical data bus main body 14 includes a core layer 16 having a relatively high refractive index and clads having a refractive index smaller than that of the core layer 16 on both upper and lower surfaces of the core layer 16. It is formed of a laminate 24 in which transparent media 20 composed of layers 18 and light shielding layers 22 are alternately laminated, and functions as a multi-bit bus with a large transmission amount.
[0039]
  In the present embodiment, polymethyl methacrylate (PMMA) having a thickness of 20 mm per 20 permeable medium is used.
[0040]
  In addition, as shown in FIG. 2, six sets of waveguides 32A in which an incident light guide path 28A and an output light guide path 30A are paired are optically coupled to the first light transmission surface 26A of the optical data bus main body 14. Yes. The incident light guide path 28A is optically coupled to the optical data bus main body 14 via the light diffusion portion 34A. The optical data bus main body 14 and the plurality of waveguides 32A constitute an optical data bus 21.
[0041]
  Similar to the optical data bus main body 14, the waveguide 32 </ b> A is formed by alternately laminating the transmissive medium 20 including the core layer 16 and the clad layer 18 and the light shielding layer 22. Further, similarly to the optical data bus main body 14, polymethyl methacrylate (PMMA) having a thickness of 0.5 mm per layer of the transmissive medium 20 is used.
[0042]
  In the present embodiment, since the light emitting area of a light emitting element 38A described later is smaller than the light receiving area of the light receiving element 40A, the dimension of the width L1 of the incident light guide path 28A is 0.5 mm as shown in FIG. The width L2 of the output light guide 30A is set to 1.5 mm, and the width of the incident light guide 28A is set smaller than the width of the output light guide 30A.
[0043]
  As shown in FIG. 2, in this embodiment, the lengths of the two waveguides 32A (outgoing light guides 30A) optically coupled to the center of the first light transmission surface 26A of the optical data bus main body 14 are as follows. It is 25 mm and is formed the longest. Further, the lengths of the two waveguides 32A arranged adjacent to each other in the direction of the arrow A in the drawing of these waveguides 32A and optically coupled to the first light transmission surface 26A of the optical data bus main body 14 are 15 mm. Is formed. Furthermore, these waveguides 32A are arranged adjacent to each other in the direction of the arrow A in the drawing, that is, the lengths of the two waveguides 32A that are optically coupled to the first light transmission surface 26A of the optical data bus main body 14 are as follows. 5 mm, which is the shortest.
[0044]
  Further, as shown in FIG. 4, the adjacent outgoing light guide paths 30A are all arranged at a pitch of 3 mm (the sum of L2 and L3) with an interval L3 = 1.5 mm, and are arranged on the surface of the base 12. It is fixed.
[0045]
  As shown in FIGS. 2 and 3, a circuit board 36A is connected to the end of the waveguide 32A opposite to the end that is optically coupled to the optical data bus main body 14.
[0046]
  Specifically, the incident light guide path 28A is optically coupled to the light emitting element 38A mounted at the end on the circuit board 36A, and the output light guide path 30A is also adjacent to the inside of the light emitting element 38A on the circuit board 36A. Are optically coupled to the light receiving element 40A.
[0047]
  Each circuit board 36A is fixed on the base 12 so as to be parallel to the width direction (the direction of arrow A in the figure) of the first light transmission surface 26A of the optical data bus main body 14.
[0048]
  Although not shown, the circuit board 36A performs a signal generation circuit that generates a signal to be carried by the signal light emitted from the light emitting element 38A, and a signal processing based on the signal carried by the signal light received by the light receiving element 40A. A signal processing circuit is installed.
[0049]
  Here, as shown in FIG. 2, the length of the outgoing light guide 30 </ b> A is increased from the vicinity of both sides in the width direction (arrow A direction) of the first light transmission surface 26 </ b> A of the optical data bus body 14 to the center. Therefore, all the circuit boards 36A can be arranged in parallel to the first light transmission surface 26A of the optical data bus main body 14, respectively.
[0050]
  In the present embodiment, since the length differences L4 between the adjacent outgoing light guide paths 30A are all 10 mm, the circuit boards 36A are arranged at a pitch of 10 mm.
[0051]
  For this reason, as shown in FIGS. 2 and 4, the interval L3 between the adjacent output light guides 30A can be set smaller than the interval L4 between the circuit boards 36A, and in this embodiment, between the output light guides 30A. The interval L3 is set to 1.5 mm, that is, 3 mm pitch (the sum of L2 and L3).
[0052]
  On the other hand, the incident light guide path 28A, the output light guide path 30A, and the circuit board 36A as described above are also arranged in the same configuration on the second light transmission surface 26B of the optical data bus body 14, and the optical data bus body 14 and It is optically coupled.
[0053]
  That is, the second light transmission surface 26B of the optical data bus main body 14 is optically coupled with the waveguide 32B in which the incident light guide path 28B and the output light guide path 30B are paired. The optical coupling is performed at intervals of 1.5 mm (3 mm pitch). In this case as well, all the incident light guide paths 28B and the optical data bus main body 14 are optically coupled via the light diffusion portion 34B.
[0054]
  A circuit board 36B is connected to the end opposite to the end of the waveguide 32B that is optically coupled to the optical data bus main body 14. Specifically, the incident light guide path 28B is optically coupled to the light emitting element 38B mounted at the end on the circuit board 36B, and the output light guide path 30B is also adjacent to the inside of the light emitting element 38B on the circuit board 36B. Are optically coupled to the light receiving element 40B mounted thereon.
[0055]
  The circuit board 36B is fixed on the base 12 so as to be parallel to the width direction (the direction of arrow A in FIG. 2) of the second light transmission surface 26B of the optical data bus main body 14. Similarly, the circuit board 36B performs signal processing based on the signal carried by the signal light received by the light receiving element 40B and the signal generation circuit that generates the signal carried by the signal light emitted from the light emitting element 38B. A signal processing circuit is installed.
[0056]
  Further, as shown in FIG. 1, three other VLSI chips 43 are mounted on the base 12.
[0057]
  In this embodiment, the optical data bus main body 14, the incident light guides 28A and 28B, and the output light guides 30A and 30B are stacked. However, the present invention is not limited to this, and a single layer may be used.
[0058]
  Next, the operation and effect of the signal processing apparatus of this embodiment will be described.
[0059]
  First, a method for manufacturing the optical data bus main body 14 will be described. The optical data bus main body 14 is manufactured by heating a mold prepared in advance to the melting temperature of polymethyl methacrylate and pouring the molten polymethyl methacrylate into the mold. At this time, the optical data bus main body 14 and the output light guide paths 30A and 30B may be integrally formed.
[0060]
  Next, a method for manufacturing the incident light guide and the output light guide will be described. Hereinafter, description will be made with reference to the incident light guide path 28A and the output light guide path 30A.
[0061]
  Since the incident light guide path 28A and the output light guide path 30A need to be optically coupled with the optical data bus main body 14 with high accuracy, they are manufactured as follows.
[0062]
  That is, as shown in FIGS. 6A and 6B, in the waveguide 32A composed of the incident light guide path 28A and the output light guide path 30A, the cladding layer 18 made of an amorphous fluorine-based material is provided on both upper and lower surfaces of the core layer 16. The laminated body 24 formed by alternately laminating the transmissive medium 20 and the light shielding layer 22 are formed by cutting in the laminating direction.
[0063]
  In the case of this manufacturing method, one of the laminated bodies 24 cut is used as the optical data bus main body 14, and the remaining laminated body 24 is used as the waveguide 32A that becomes the incident light guide path 28A and the output light guide path 30A. For this reason, the height in the stacking direction of the optical data bus main body 14 is equal to the height in the stacking direction of the incident light guide path 28A and the outgoing light guide path 30A, and the optical data bus main body 14 or the optical data bus from the incident light guide path 28A. Loss of signal light transmitted from the main body 14 to the outgoing light guide path 30A is reduced. Further, by forming the optical data bus main body 14, the incident light guide path 28A and the output light guide path 30A into a prismatic shape such as a quadrangular prism, and unifying the cross-sectional shape of both of them into a quadrangular shape, the loss of signal light at the time of optical coupling is reduced. Reduced.
[0064]
  According to this manufacturing method, the positions of the core layer 16 of the optical data bus main body 14 and the core layers 16 of the incident light guide path 28A and the output light guide path 30A coincide with each other and can be optically coupled with high accuracy. .
[0065]
  After the optical data bus main body 14, the incident light guide path 28A, and the output light guide path 30A manufactured as described above are optically coupled, the signal light carrying the signal generated by the signal generation circuit of the circuit board 36A is a light emitting element. It is emitted from 38A.
[0066]
  As shown in FIG. 4, the signal light L propagates in the incident light guide path 28 </ b> A and is diffused by the light diffusion portion 34 </ b> A, and then from the first light transmission surface 26 </ b> A of the optical data bus body 14. Is incident on. Then, the signal light incident on the optical data bus main body 14 is transmitted through the core layer 16 of the optical data bus main body 14 while repeating total reflection.
[0067]
  Further, the signal light transmitted through the optical data bus main body 14 exits from the second light transmission surface 26B of the optical data bus main body 14 and enters the output light guide path 30B. As shown in FIG. 5, the signal light that has entered the outgoing light guide 30B propagates without loss while repeating total reflection, and is received by the light receiving element 40B on the circuit board 36B.
[0068]
  Thereafter, the signal processing circuit on the circuit board 36B performs signal processing based on the signal carried by the received signal light.
[0069]
  In the above description, the signal light is incident on the optical data bus main body 14 from the first light transmitting surface 26A of the optical data bus main body 14 and transmitted through the core layer 16 of the optical data bus main body 14, and then the second light is transmitted. Although the mode of emitting from the light transmitting surface 26B is shown, the signal light emitted from the light emitting element 38B on the circuit board 36B is diffused by the light diffusing unit 34B, and then the second light transmitting surface of the optical data bus main body 14 is used. It is also possible to enter the optical data bus main body 14 from 26B, transmit the optical data bus main body 14 and then emit the light from the first light transmitting surface 26A. Even in this case, the signal light propagates through one of the outgoing light guides 30A, and then is received by the light receiving element 40A on the circuit board 36A and is subjected to signal processing.
[0070]
  Here, the length of each output light guide path 30A that is optically coupled to the optical data bus main body 14 is from the side to the center in the width direction (direction of arrow A in FIG. 2) of the light transmission surface 26A of the optical data bus main body 14. Since the length is set to be long, each circuit board 36 </ b> A can be arranged so as to be parallel to the light transmission surface 36 </ b> A of the optical data bus main body 14.
[0071]
  For this reason, the circuit board 36A does not become an obstacle, and the interval (pitch) between the adjacent output light guides 30A can be set smaller than the interval (pitch) between the circuit boards 36A coupled to these output light guides 30A. it can.
[0072]
  That is, when the interval between the circuit boards 36A is 10 mm, unlike the conventional case where the interval between the light receiving elements 40A is inevitably set to 10 mm, the interval between the adjacent outgoing light guides 30A, and hence the adjacent light receiving elements 40A. Can be set to 1.5 mm (3 mm pitch).
[0073]
  Here, the transmission efficiency of the signal processing device of the present invention and the signal processing device of the prior art will be compared using FIG. 7 shows that the optical data bus main body 14 has a dimension in the direction of arrow B in FIG. 3 of 1 mm, the diameter of the light receiving element 40A is 0.8 mm, and four outgoing light guide paths 30A are set on the light transmitting surface 26A (four ports). Under the conditions, the light transmission efficiency at each output port when the pitch of the light receiving elements 40A is 3 mm, and the width of the optical data bus main body 14 is 1/3 of the conventional one, and the pitch of the light receiving elements 40A is 10 mm. The optical transmission efficiency at each output port (conventional) is shown.
[0074]
  As shown in FIG. 7, the light transmission efficiency is about three times that of the conventional transmission efficiency, and the pitch between the outgoing light guide paths 30A is reduced, and the light transmission surface 26A of the optical data bus main body 14 is correspondingly reduced. By reducing the width, the signal light that is not received by the light receiving element 40A and is wasted can be reduced, and the optical transmission efficiency can be improved.
[0075]
  As a result, the loss of the signal light emitted from the optical data bus main body 14 can be reduced, and the signal processing device 10 with low power consumption can be obtained, and the transmission efficiency of the signal light is extremely high. Even with the output (power), it is possible to cope with higher speed.
[0076]
  In the present embodiment, the pitch between the output light guides 30A is set to 3 mm, but it may be smaller than the pitch of each circuit board 36A. For example, when the circuit boards 36A are arranged at a pitch of 10 mm, the pitch between the outgoing light guide paths 30A can be set to 1 mm.
[0077]
  Here, since the reduction of the width L1 of the incident light guide path 28A is limited by the coupling relationship with the light emitting element 38A, the output light guide path 30A and the incident light guide path adjacent to the output light guide path 30A through a space are provided. It is preferable that the distance from 28A be smaller than the width L1 of the incident light guide path 28A.
[0078]
  Furthermore, the pitch of each circuit board 36A is not limited to 10 mm.
[0079]
  Next, a modification of the optical data bus described in the above embodiment will be described.
[0080]
  In addition, in the following description, the content which overlaps with the optical data bus main body 14 of the said embodiment is abbreviate | omitted suitably.
[0081]
  As shown in FIG. 8, the sheet-like optical data bus main body 14 constituting the optical data bus 50 of this modification has a transparent medium 20 composed of a core layer 16, a cladding layer 18, and a light shielding layer 22 alternately. It is laminated and configured. Four waveguides 52A are optically coupled to the first light transmission surface 26A of the optical data bus main body 14.
[0082]
  The waveguide 52A is composed of an incident light guide path 54A and an output light guide path 56A. Like the optical data bus main body 14, the transmissive medium 20 and the light shielding layer 22 are alternately stacked. ing. The optical data bus main body 14, the incident light guide path 54A, and the output light guide path 56A are formed by cutting from the same stacked body 24 in the stacking direction.
[0083]
  The length of the waveguide 52A is set so as to increase from one side of the first light transmission surface 26A of the optical data bus main body 14 to the other side. The interval between adjacent outgoing light guide paths 56A is set smaller than the difference in length between adjacent waveguides 52A (outgoing light guide paths 56A).
[0084]
  A circuit board 58A is connected to the end of the optical data bus main body 14 opposite to the end of the waveguide 52A that is optically coupled to the first light transmission surface 26A. That is, the light emitting element 60A mounted on the end of the circuit board 58A and the incident light guide path 54A are optically coupled, and the light receiving element 62A and the output waveguide 56A mounted on the inner side of the light emitting element 60A on the circuit board 58A. Are optically coupled.
[0085]
  Each circuit board 58A is arranged in parallel to the first light transmission surface 26A of the optical data bus main body 14.
[0086]
  On the other hand, the waveguide 52B and the circuit board 58B are similarly optically coupled to the second light transmission surface 26B of the optical data bus main body 14. In this case, the longest waveguide 52B is optically coupled to the second light transmission surface 26B at the position opposite to the shortest waveguide 52A among the waveguides 52A optically coupled to the first light transmission surface 26A. Yes. The next longest waveguide 52B is optically coupled to a position opposite to the next shortest waveguide 52A among the waveguides 52A optically coupled to the first light transmission surface 26A. As described above, the first light transmission surface 26A and the second light transmission surface 26B are optically coupled with the waveguides 52A and 52B having symmetrical lengths facing each other.
[0087]
  Similarly, the waveguide 52B includes an incident light guide path 54B and an output light guide path 56B. The incident light guide path 54B is optically coupled to the light emitting element 60B on the circuit board 58B, and the output light guide path 56B is coupled to the light receiving element 62B and the light. Are connected.
[0088]
  The circuit board 58B is arranged in parallel with the second light transmission surface 26B.
[0089]
  According to the optical data bus 50 of this modification, the waveguide 52A optically coupled to the first light transmission surface 26A and the circuit board 58A are rotated by 180 degrees, and optically coupled to the second light transmission surface 26B as it is. Can be made. That is, the circuit board 58B having the same configuration of the light emitting element 60A and the light receiving element 62A with respect to the circuit board 58A can be optically coupled to the second light transmission surface 26B.
[0090]
【The invention's effect】
  According to the signal processing device of the present invention, it is possible to reduce the loss of the signal light emitted from the optical bus main body and improve the light transmission efficiency.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a signal processing apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view showing a state in which a circuit board is coupled to an optical data bus constituting the signal processing apparatus.
FIG. 3 is a side view of FIG. 2;
FIG. 4 is a diagram showing a positional relationship of each waveguide.
FIG. 5 is a cross-sectional view showing a relationship between an outgoing light guide path and a light receiving element.
6A is a perspective view of a laminate in which a transmissive medium is laminated, and FIG. 6B is a perspective view of a waveguide formed by cutting the laminate.
FIG. 7 is a graph showing the relationship between optical transmission efficiency and output node.
FIG. 8 is a plan view of a modification of the optical data bus mounted on the signal processing apparatus of the present invention.
FIG. 9 is a plan view of a conventional optical data bus.
FIG. 10A is a partial plan view of a conventional optical data bus, and FIG. 10B is a longitudinal sectional view thereof.
[Explanation of symbols]
    10 Signal processing device
    14 Optical data bus body (optical bus body)
    28A, 28B, 54A, 54B Incident light guide
    30A, 30B, 56A, 56B Outgoing light guide
    36A, 36B, 58A, 58B circuit board
    40A, 40B, 62A, 62B Light receiving element (light receiving part)
    26A First light transmission surface (optical coupling surface)
    26B Second light transmission surface (optical coupling surface)

Claims (2)

A plurality of incident light guides that propagate signal light; and an optical bus body that optically couples with the incident light guide and diffuses and propagates signal light emitted from any of the incident light guides; A plurality of output light guides that are optically coupled to the optical bus body and propagate signal light emitted from the optical bus body; and a light receiving unit that receives the signal light propagated through the output light guide path; A circuit board that performs signal processing based on the signal carried;
In a signal processing device configured to include:
An interval between adjacent outgoing light guides is set smaller than a difference in length between adjacent outgoing light guides,
The signal processing apparatus, wherein the circuit board having the light receiving portion optically coupled to an end portion of the output light guide is disposed in parallel to the optical coupling surface of the optical bus body. A plurality of incident light guides that propagate signal light; and an optical bus body that optically couples with the incident light guide and diffuses and propagates signal light emitted from any of the incident light guides; A plurality of output light guides that are optically coupled to the optical bus body and propagate signal light emitted from the optical bus body; and a light receiving unit that receives the signal light propagated through the output light guide path; A circuit board that performs signal processing based on the signal carried;
In a signal processing device configured to include:
An interval between adjacent incident light guides is set smaller than a difference in length between adjacent incident light guides,
The signal processing apparatus, wherein the circuit board including the light emitting unit optically coupled to an end of the incident light guide is disposed in parallel to the optical coupling surface of the optical bus body.

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