JP2008261956A - Optical transmission line, optical transmission module, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission line that enables stable bidirectional optical transmission by using a simple constitution. <P>SOLUTION: The optical transmission line 4, enabling bidirectional optical transmission, has at least two core parts 11a, 11b comprising a material having translucency and a cladding part 12 comprising a material having a refractive index different from that of the core parts 11a, 11b and is configured to make the light emitted from a light-emitting part 6 guided through light incidence faces of the core parts 11a, 11b into the core parts 11a, 11b and exit to the outside from exiting faces of the core parts 11a, 11b. The light incidence face of the first core part 11a together with the light exit face of the core part 11b different from the first core part 11a, and the light exit face of the first core part 11a together with the light incidence face of the core part 11b different from the first core part 11a, are disposed on outer faces mutually different from each other in the outer faces forming the optical transmission line 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical interconnection for connecting circuit boards in an information transmission apparatus such as a cellular phone with an optical signal, and more particularly to an optical transmission line for transmitting an optical signal, an optical transmission line module, and an electronic device. Is.

  In recent years, with increasing CPU clock frequency, higher I / O paths and memory buses have been demanded. However, with conventional electrical wiring, crosstalk and electromagnetic radiation become more conspicuous as the speed increases, so there is a limit to increasing the data transmission speed. In order to solve such a problem, a method of transmitting data by connecting a CPU and various application circuits using an optical wiring such as an optical waveguide (optical transmission path) has been attempted.

  The optical waveguide has a double structure of a core called a core and a sheath called a clad covering the core, and the refractive index of the core is higher than that of the clad. That is, the optical signal incident on the core is propagated by repeating total reflection inside the core.

  Here, a schematic configuration of the optical transmission module will be described below with reference to the drawings. FIG. 24A is a perspective view showing an appearance of the light transmission module, and FIG. 24B is a perspective view showing an interior view of a mobile phone including the light transmission module. FIG. 25 is a top view showing a state where substrates provided in the device are connected by an optical transmission module.

  The optical transmission module 100 includes a communication processing unit connected to a CPU board, a communication processing unit connected to an application circuit board, and a highly bent optical waveguide. Each communication processing unit includes an optical transmission unit including a light source driving circuit and a light emission unit (VCSEL), and an optical reception unit including a light reception unit (PD) and a reception (amplifier) IC. Thus, each communication processing unit has a transmission function and a reception function. Therefore, for example, a communication processing unit connected to the CPU board can upload a signal from the CPU, and can download a signal from the LCD driver on the application circuit board.

  Note that the optical transmission module 100 illustrated in FIG. 25 has a configuration in which an upstream signal and a downstream signal are transmitted through different transmission paths in a single optical transmission medium.

  However, the conventional optical waveguide has a problem in that the reception sensitivity at the light receiving portion deteriorates due to crosstalk (crosstalk) generated between the light emitting portion and the light receiving portion, and stable light transmission cannot be performed.

  Therefore, as a method for reducing the crosstalk, a technique has been proposed in which the light emitting unit and the light receiving unit are optically separated from each other on the same substrate, that is, the isolation is improved. Specifically, for example, the methods shown in the following Patent Documents 1 to 3 can be mentioned.

  As shown in FIG. 26, Patent Document 1 discloses a technique for ensuring optical isolation by separating a transmission signal and a reception signal having different wavelengths of optical signals with a wavelength filter.

  In Patent Document 2, as shown in FIG. 27, the light is transmitted by shifting the positions of the light emitting part and the light receiving part in the light transmission direction when light is transmitted in the optical waveguide, and separating the distance between them. A technique for improving isolation is disclosed.

Patent Document 3 discloses a technique for improving optical isolation by cutting a clad part at 45 degrees and shielding a cut inclined surface as shown in FIG.
JP 2005-316291 A (published on November 10, 2005) JP 2004-198579 (published July 15, 2004) JP 2005-4204 (January 6, 2005)

  However, the techniques of Patent Documents 1 to 3 have the following problems.

  That is, in the technique of Patent Document 1, since a light source and a light receiving element having at least two wavelengths are required, the entire system becomes complicated and the cost increases. Further, since a passive element such as a wavelength filter is required, the size of the entire system is increased.

  Further, in the technique of Patent Document 2, since it is necessary to form the light entrance and the light exit at different positions in the same light transmission direction in the optical transmission medium, the shape of the end face becomes complicated and the manufacturing process is complicated. It will become. In addition, since the optical transmission direction of the transmission signal and the optical transmission direction of the reception signal are the same direction, the optical signal component that is not introduced into the core and propagates back and forth in the cladding, that is, noise light enters the light receiving unit, It leads to deterioration of reception sensitivity.

  Moreover, in the technique of patent document 3, since it is necessary to make a core part and a clad part into a different shape in the end surface of an optical waveguide, a manufacturing process will be complicated. Further, since the light incident end surface and the light emitting end surface are arranged to face each other, noise light propagating in the cladding is emitted from the light emitting end surface, and the reception sensitivity is deteriorated as in the problem of Patent Document 2. Resulting in.

  As described above, in the configuration of the conventional optical transmission path capable of bidirectional optical transmission, the structure becomes complicated in order to improve the optical isolation, so that it is difficult to perform stable optical transmission with a simple configuration. It is.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical transmission line, an optical transmission module, and an electronic device that are capable of stable bidirectional optical transmission with a simple configuration. It is in.

  In order to solve the above problems, an optical transmission line in the present invention is composed of at least two core parts made of a material having translucency and a material having a refractive index different from the refractive index of the core part. The light irradiated from the light source is introduced into the core part from the light incident surface of the core part, and the light transmitted through the core part is emitted to the outside from the light emitting surface of the core part. An optical transmission path configured to allow bidirectional optical transmission, the light incident surface of the first core portion and the light emitting surface of the core portion different from the first core portion, In addition, the light emitting surface of the first core portion and the light incident surface of the core portion different from the first core portion are provided on different outer surfaces of the outer surfaces forming the optical transmission path. It is.

  According to the above configuration, in the optical transmission path that enables bidirectional optical transmission, the light incident surface of the first core unit and the light emitting surface of the core unit different from the first core unit, and The light emitting surface of the first core portion and the light incident surfaces of the core portion different from the first core portion are provided on different outer surfaces among the outer surfaces forming the optical transmission path. That is, the light transmission direction when entering the core portion from the light incident surface is different from the light transmission direction when light transmitted through the core portion reaches the light exit surface.

  Therefore, an optical signal that is not introduced into the core part but propagates through the clad part, that is, noise light, is not incident on the light receiving part. Specifically, for example, when performing bidirectional communication between a CPU board and an LCD driver, noise light derived from an optical signal incident from the CPU board side is a surface facing the light incident surface in the optical transmission path. Reflected. Conventionally, the transmission direction of the reflected noise light coincides with the transmission direction of the optical signal incident from the LCD driver side with respect to the light emitting surface, so that the noise light is incident on the light receiving portion and the reception sensitivity is deteriorated. I was invited. However, in the configuration of the present invention, as described above, since both transmission directions are different, noise light is not incident on the light receiving unit. As a result, it is possible to prevent the reception sensitivity from deteriorating and to perform stable optical transmission.

  Further, since it is not necessary to provide a new passive element as in the prior art in order to stabilize the optical transmission, it is possible to prevent the entire system using the optical transmission path from becoming large. Furthermore, since it is not necessary to make the outer shape of the optical transmission line complicated, it can be manufactured by a general cutting method, so that the manufacturing process can be prevented from becoming complicated.

  As described above, according to the above configuration, it is possible to provide an optical transmission line capable of stable bidirectional optical transmission with a simple configuration.

  In the optical transmission path according to the present invention, in the above configuration, the light incident surface and the light emitting surface of the core part are formed obliquely with respect to the light transmission direction when light is transmitted in the core part. The light emitted from the light source is introduced into the core part by being reflected at the light incident surface, and the light transmitted within the core part is reflected to the outside by being reflected at the light emitting surface. You may be comprised so that it may radiate | emit.

  According to said structure, it becomes possible to set it as the structure which arrange | positions a light source to a perpendicular | vertical direction with respect to an optical transmission direction with respect to an optical transmission line. Therefore, for example, when it is necessary to arrange an optical transmission path parallel to the substrate surface, a light source is disposed between the optical transmission path and the substrate surface so that light is emitted in the normal direction of the substrate surface. Just install it. Such a configuration is easier to mount than a configuration in which, for example, the light source is installed so as to emit light parallel to the substrate surface, and the configuration can be made more compact.

  In the optical transmission path of the present invention, in the above configuration, the light incident surface and the light emitting surface of the core portion may be formed at 45 degrees with respect to the optical transmission direction.

  Accordingly, the light emitted from the light source arranged in the direction perpendicular to the light transmission direction and reflected by the light incident surface can be reliably introduced into the core part, and the light reflected by the light emitting surface can be introduced. Thus, the light can be reliably emitted to the light receiving portion arranged in the direction perpendicular to the light transmission direction.

  In the optical transmission path according to the present invention, in the above configuration, the light incident surface of the core portion is formed at 45 degrees with respect to the light transmission direction, while the light emitting surface of the core portion is It may be formed at approximately 40 degrees with respect to the optical transmission direction.

  According to said structure, since the light-projection surface of the said core part is formed at about 40 degree | times with respect to the said optical transmission direction, out of the light which propagates the inside of an optical transmission path and arrives at a light-projection surface Further, it is possible to efficiently reflect and output to the outside high-order mode light having a large propagation angle and a large incident angle with respect to the light exit surface. As a result, the amount of light received by the light receiving unit can be increased, and an increase in reflection loss due to mode change due to deformation of the optical transmission path can be suppressed, so that the optical transmission efficiency can be further improved.

  In the optical transmission line according to the present invention, in the above configuration, the core part is bent in a direction different from the extending direction of the optical transmission line in the optical transmission line. The curvature radius of the shaft may be formed in a range of 1 to 2 mm.

  Said structure consists of an optical transmission line which has a refractive index difference which does not produce a loss even if an optical transmission line is bent and used to the range of a curvature radius of 1-2 mm. Therefore, for example, it is possible to provide a flexible optical transmission line that can be sufficiently used as an optical wiring in a small electronic device.

  Further, the optical transmission line according to the present invention has the above configuration, wherein the core portion is bent in a direction different from the extending direction of the optical transmission line in the optical transmission line. It is formed obliquely with respect to the light transmission direction when light is transmitted in the core part, and light transmitted in the core part is formed on the light emitting surface side in the obliquely formed bent part. It may be configured to be reflected.

  According to said structure, the light transmitted in the said core part is reflected in the said light-projection surface side in the bending part formed diagonally.

  Moreover, the optical transmission line in this invention WHEREIN: The said structure WHEREIN: The reflection plate which reflects the light transmitted in the said core part may be provided in the said bending part.

  According to said structure, the reflecting plate which reflects the light transmitted in the said core part is provided in the said bending part. Therefore, since bending loss can be further reduced, the stability of optical transmission can be further improved.

  Further, the optical transmission line according to the present invention is the first bending direction that most permits the bending of the optical transmission line in the cross section perpendicular to the optical transmission direction when the light is transmitted in the core portion in the above configuration. When the length of the core part in the direction 1 is the thickness d and the length of the core part in the second direction perpendicular to the first direction is the lateral width w, the lateral width w at least on the light incident surface of the core part. However, the width may be longer than the thickness d, and the lateral width w may decrease from the entrance on the light incident side toward the exit on the light exit side.

  Here, for high-speed transmission, it is desirable that the light receiving surface of the light receiving element constituting the light receiving unit is smaller. In this regard, according to the above configuration, the lateral width w of the core portion decreases from the entrance on the light incident side toward the exit on the light exit side. Thereby, compared with the conventional structure, since the area | region of the exit used as the light emission side can be made small, the area | region of the light radiate | emitted from an optical transmission path can be made small. Therefore, the irradiation area on the light receiving surface of the light receiving element can be reduced, and the amount of light that can be received by a small light receiving element in the light receiving portion can be increased. Therefore, the transmission speed can be increased as compared with the conventional configuration.

  In the optical transmission line according to the present invention, in the above configuration, the light incident surface and the light emitting surface of the core portion may be provided with a reflecting plate that reflects light emitted from the light source.

  According to said structure, since the reflecting plate which reflects the light irradiated from the light source is provided in the light-incidence surface and light-projection surface of the said core part, more light irradiated from the light source is in a core part. And more light can be emitted from the core portion to the light receiving portion. Thereby, since the light quantity which a light-receiving part light-receives can be increased, optical transmission efficiency can be improved.

  In order to solve the above problems, an optical transmission module according to the present invention includes the above-described optical transmission path, at least two light emitting units that irradiate light to the light incident surface of the optical transmission path, and the light. It is a structure provided with at least 2 light-receiving part which light-receives the light radiate | emitted from the light-projection surface of a transmission line.

  According to the above configuration, it is possible to provide an optical transmission module capable of stable bidirectional optical transmission with a simple configuration.

  In the optical transmission module according to the present invention, in the configuration described above, the light emitting unit irradiates the optical transmission line with light from a direction substantially perpendicular to the optical transmission direction in the optical transmission line. The light transmission path may be configured to introduce the light emitted from the light emitting part into the core part by reflecting the light on the light incident surface.

  According to said structure, it becomes possible to set it as the structure which arrange | positions a light emission part to a perpendicular | vertical direction with respect to an optical transmission direction with respect to an optical transmission line. Therefore, for example, when it is necessary to arrange an optical transmission path parallel to the substrate surface, the light emitting unit emits light in the normal direction of the substrate surface between the optical transmission path and the substrate surface. It would be good to install. Such a configuration is easier to mount than a configuration in which, for example, the light emitting unit is installed so as to emit light in parallel to the substrate surface, and the configuration can be made more compact.

  The optical transmission path in the present invention is an optical transmission path that enables bidirectional optical transmission as described above, and is a light incident surface of the first core section and a core section different from the first core section. The light emitting surfaces of the first core portion and the light incident surfaces of the core portion different from the first core portion are different from each other among the outer surfaces forming the optical transmission path. It is the structure provided in.

  As a result, it is possible to prevent noise light from entering the light receiving portion and prevent deterioration of reception sensitivity, and thus stable light transmission is possible. Therefore, it is possible to provide an optical transmission path capable of stable bidirectional optical transmission with a simple configuration.

  In addition, by providing the optical transmission path, it is possible to provide an optical transmission module that can perform stable bidirectional optical transmission with a simple configuration.

  An embodiment of the present invention is described below with reference to the drawings.

(Configuration of optical transmission module)
FIG. 2 shows a schematic configuration of the optical transmission module 1 in the present embodiment. As shown in the figure, the optical transmission module 1 includes, for example, a first communication processing unit 2 connected to a CPU board, a second communication processing unit 3 connected to, for example, an application circuit board, and a first communication. An optical transmission line 4 serving as an optical wiring connecting the processing unit 2 and the second communication processing unit 3 is provided.

  The first communication processing unit 2 and the second communication processing unit 3 include a light emission drive unit 5 and a light emission unit (light source) 6, a light receiving unit 7 and an amplification unit 8, respectively.

  The light emission driving unit 5 drives the light emission of the light emitting unit 6 based on an electric signal input from the outside. The light emission driving unit 5 is configured by, for example, an IC (Integrated Circuit) for light emission driving. Although not shown, the light emission drive unit 5 is provided with an electrical connection portion with an electrical wiring for transmitting an electrical signal from the outside.

  The light emitting unit 6 emits light based on drive control by the light emission driving unit 5. The light emitting unit 6 is configured by a light emitting element such as a VCSEL (Vertical Cavity-Surface Emitting Laser). The light emitted from the light emitting unit 6 is applied to the light incident side end of the optical transmission line 4 as an optical signal.

  The light receiving unit 7 receives light as an optical signal emitted from the light emitting side end of the optical transmission path 4 and outputs an electrical signal by photoelectric conversion. The light receiving unit 7 is configured by a light receiving element such as a PD (Photo-Diode).

  The amplifying unit 8 amplifies the electrical signal output from the light receiving unit 7 and outputs it to the outside. The amplifying unit 8 is configured by an amplification IC, for example. Although not shown, the amplifying unit 8 is provided with an electrical connection with electrical wiring for transmitting an electrical signal to the outside.

  The optical transmission path 4 is a medium that transmits the light emitted from the light emitting unit 6 to the light receiving unit 7. Details of the configuration of the optical transmission line 4 will be described later.

  Thus, since the first communication processing unit 2 and the second communication processing unit 3 have a transmission function and a reception function, respectively, for example, in the first communication processing unit 2 connected to the CPU board, A signal (upstream signal) from the CPU can be uploaded, and a signal (downstream signal) from the LCD driver can be downloaded. That is, the optical transmission module 1 has a configuration capable of bidirectional optical communication.

  FIG. 3 schematically shows the state of optical transmission in the optical transmission line 4. As shown in the figure, the optical transmission line 4 is constituted by a columnar member having flexibility. A light incident reflection surface (light incident surface) 4A is provided at the light incident side end of the light transmission path 4, and a light output reflection surface (light emitting surface) 4B is provided at the light output side end. It has been. In the figure, for convenience of explanation, optical transmission in only one direction is shown.

  The light emitted from the light emitting unit 6 is incident on the light incident side end portion of the light transmission path 4 from a direction perpendicular to or substantially perpendicular to the light transmission direction of the light transmission path 4. The incident light travels in the optical transmission line 4 by being reflected by the light incident reflection surface 4A. The light that travels through the optical transmission path 4 and reaches the light output side end is reflected by the light output reflection surface 4B, thereby being perpendicular or substantially perpendicular to the optical transmission direction of the optical transmission path 4. Is emitted. The emitted light is irradiated to the light receiving unit 8, and photoelectric conversion is performed in the light receiving unit 8.

  According to such a configuration, the light emitting unit 6 as a light source can be arranged in a direction perpendicular to the light transmission direction in the light transmission path 4. Therefore, for example, when it is necessary to arrange the optical transmission path 4 parallel to the substrate surface, light is emitted between the optical transmission path 4 and the substrate surface in the normal direction of the substrate surface. The light emitting unit 6 may be installed. Such a configuration is easier to mount than a configuration in which, for example, the light emitting unit 6 is installed so as to emit light parallel to the substrate surface, and the configuration can be made more compact. This is because the general configuration of the light emitting unit 6 is larger in size in the direction perpendicular to the direction of emitting light than in the direction of emitting light. Furthermore, the present invention can also be applied to a configuration in which a light emitting element for planar mounting having an electrode and a light emitting portion 6 in the same plane is used.

  The optical transmission line 4 shown in the figure has a configuration in which the light incident surface 4A and the light emission surface 4B are inclined as described above. However, both ends of the optical transmission line 4 in this embodiment are light. The configuration may be orthogonal to the transmission direction. That is, the outer shape of the optical transmission line 4 may be formed in a rectangular parallelepiped as shown in FIG.

(Configuration of optical transmission line)
FIG. 1A is a perspective view showing a schematic configuration of the optical transmission line 4 in the present embodiment, and FIG. 1B is a top view thereof. As shown in FIG. 1A and FIG. 1B, the optical transmission line 4 has a rectangular parallelepiped shape, and columnar core portions 11a and 11b with the optical transmission direction as an axis, and core portions 11a, 11a, The clad part 12 is provided so as to surround the periphery of 11b. The core parts 11a and 11b and the clad part 12 are made of a light-transmitting material, and the refractive index of the core parts 11a and 11b is higher than the refractive index of the clad part 12. Thereby, the optical signals incident on the core portions 11a and 11b are transmitted in the optical transmission direction by repeating total reflection inside the core portions 11a and 11b.

  The optical transmission line 4 in the present embodiment has a configuration in which at least two core portions 11a and 11b are formed in a single transmission medium. When the core parts 11a and 11b are composed of two, one is used for uplink signal transmission and the other is used for downlink signal transmission. Thereby, bidirectional communication of the optical transmission module 1 becomes possible. Note that the optical transmission module 1 of the present embodiment may have a configuration in which a plurality of optical transmission paths 4 in which a plurality of core portions 11 are formed in a single transmission medium are provided in parallel. .

  As a material constituting the core parts 11a and 11b and the clad part 12, glass or plastic can be used. However, in order to constitute the optical transmission line 4 having sufficient flexibility, an acrylic type, It is preferable to use resin materials such as epoxy, urethane, and silicone. Moreover, you may comprise the clad part 12 with gas, such as air. Further, the same effect can be obtained even when the clad part 12 is used in a liquid atmosphere having a smaller refractive index than the core parts 11a and 11b. The cross-sectional shapes of the core portions 11a and 11b on the plane perpendicular to the light transmission direction are rectangular.

  Here, in FIGS. 1A and 1B, the extending direction of the optical transmission line 4 is the Z direction, the vertical direction of the paper, that is, the height (thickness) direction in the section of the optical transmission line is the Y direction, A direction perpendicular to the YZ plane, that is, a lateral direction in the cross section of the optical transmission line 4 is defined as an X direction. In the figure, the optical transmission line 4 is described as a configuration in which two core portions 11a and 11b are formed in a single transmission medium.

  As shown in FIG. 1A, the two core portions 11 a and 11 b are configured such that the end surfaces of the core portions 11 a and 11 b are not formed in the same plane among the outer surfaces that form the optical transmission path 4. It is. Specifically, for example, on the first communication processing unit 2 side, when the light incident side end surface of the core unit 11a is formed on the light incident surface 4A of the optical transmission line 4, the light emitting side of the core unit 11b The end surface is not formed on the light incident surface 4A, but is formed, for example, on the side surface (light emitting surface) 4B of the light transmission path 4. Similarly, on the second communication processing unit 3 side, when the end surface on the light emitting side of the core portion 11a is formed on the light incident surface 4A of the light transmission path 4, the end surface on the light incident side of the core portion 11b is For example, it is formed on the side surface (light emitting surface) 4B of the light transmission path 4 without being formed on the incident surface 4A. Moreover, the light emission part 6 and the light-receiving part 7 are provided corresponding to the end surface of the core part 11a, and the end surface of the core part 11b, respectively.

  As described above, the optical transmission line 4 according to the present embodiment includes the light incident surface of the first core portion 11a, the light emitting surface of the core portion 11b different from the first core portion 11a, and the first core. The light emitting surface of the portion 11 a and the light incident surface of the core portion 11 b different from the first core portion 11 a are provided on different outer surfaces among the outer surfaces forming the optical transmission path 4.

  According to said structure, the distance between the light-incidence surface of the core part 11a and the light-projection surface of the core part 11b, and the distance between the light-incidence surface of the core part 11b, and the light-projection surface of the core part 11a That is, the distance between the light emitting part 6 and the light receiving part 7 corresponding to each core part can be increased as compared with the conventional case. The light incident direction (Z direction) from the light emitting part 6 into the core part 11a, the light emitting direction (X direction) from the core part 11b to the light receiving part 7, and the light from the light emitting part 6 into the core part 11b. The incident direction (Z direction) and the light emission direction (X direction) from the core portion 11a to the light receiving portion 7 are orthogonal to each other.

  Here, an optical signal (noise light, solid line arrow in FIG. 1B) that is not introduced into the core portion 11a and propagates in the cladding portion 12 is an end face of the optical transmission line 4 on the second communication processing unit 3 side. And is emitted from the light incident surface 4A.

  In the optical transmission line 4 of the present embodiment, the light propagating through the core portion 11b is emitted from a direction orthogonal to the emission direction of the noise light emitted from the light incident surface 4A. And the light-receiving part 7 is provided in the direction orthogonal to the emission direction of noise light corresponding to the emission direction of the light emitted from the core part 11b. For this reason, noise light is not incident on the light receiving unit 7, so that it is possible to prevent degradation of reception sensitivity that has occurred in the past.

  Moreover, since the optical transmission line 4 of the present embodiment can be formed by a general cutting method, the manufacturing cost is not increased.

  In the above configuration, the light emitting unit 6 and the light receiving unit 7 are provided corresponding to the end surface of the core unit 11a and the end surface of the core unit 11b, respectively. As another configuration, as shown in FIG. Further, the arrangement of the light emitting unit 6 and the light receiving unit 7 is reversed, that is, the light receiving unit 7 is provided corresponding to the end face of the core part 11a, and the light emitting part 6 is provided corresponding to the end face of the core part 11b. May be. Thus, the position where the light emitting unit 6 and the light receiving unit 7 are provided is not particularly limited. This also applies to the examples shown below.

(Modification 1)
In the configuration of the optical transmission line 4 of the present embodiment, a modified example of the configuration shown in FIGS. 1A and 1B will be described. FIG. 5A shows a perspective view of the optical transmission line 4 as the first modification, and FIG. 5B shows a top view thereof. 6A shows a cross-sectional view of the optical transmission line 4 in the Z direction, and FIG. 6B shows a side view of the optical transmission line 4 in the X direction.

  In the example shown in FIG. 5A and FIG. 5B, the end surfaces of the core portions 11a and 11b in the optical transmission line 4 are the end surfaces of the optical transmission line 4 (light incident reflection surface 4A and light output reflection surface 4B). Correspondingly inclined. The inclination angle of the end faces of the core portions 11a and 11b is set to 45 degrees, for example. Therefore, the cross-sectional shape of the optical transmission line 4 is trapezoidal as shown in FIGS. 6 (a) and 6 (b). As a result, the light emitting unit 6 and the light receiving unit 7 can be arranged in a direction perpendicular to the light transmission direction in the light transmission path 4 (Y direction). Further, the distance between the light emitting unit 6 and the light receiving unit 7 can be increased as compared with the conventional configuration.

  A reflecting plate such as a reflecting mirror may be provided on the inclined surfaces of both end faces of the core parts 11a and 11b. Thereby, more light emitted from the light emitting part 6 can be introduced into the core parts 11a and 11b, and more light can be emitted from the core parts 11a and 11b to the light receiving part 7. . Thereby, since the light quantity which the light-receiving part 7 light-receives can be increased, optical transmission efficiency can be improved.

(Modification 2)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 7 shows a top view of the optical transmission line 4 as the second modification.

  In the example shown in the figure, the inclined end surfaces of the core portions 11a and 11b in the optical transmission line 4 are formed at different angles. In the optical transmission line 4 of the present embodiment, the end face of the core part 11a and the end face of the core part 11b are formed on different end faces in the optical transmission line 4, for example, both end faces of the core part 11a, that is, the light emitting part 6 The end surface on the side and the end surface on the light receiving unit 7 side can be formed at different angles. Specifically, the angle of the end surface on the light emitting unit 6 side with respect to the lower surface irradiated with light to the optical transmission path 4 is, for example, 45 degrees, and the angle of the end surface on the light receiving unit 7 side (shaded portion in FIG. 7) is It can be formed in a range of approximately 40 degrees, for example, 30 to 40 degrees.

  Thereby, similarly to the modification 1, it is possible to prevent deterioration of the reception sensitivity, and out of the light that propagates through the core portion 11a and reaches the inclined end surface formed on the light emission surface 4B, with respect to the light emission surface 4B. High-order mode light having a large incident angle can be efficiently reflected and output to the outside. As a result, the amount of light received by the light receiving unit 7 can be increased, and an increase in reflection loss due to mode change due to deformation of the optical transmission path 4 can be suppressed, so that the optical transmission efficiency can be further improved. . Further, since the inclined end face of the optical transmission line 4 can be formed by a general cutting method, the manufacturing cost is not increased.

  In the second modification, the position of the light receiving unit 7 may be shifted. FIG. 8 shows an enlarged cross-sectional view of a portion A surrounded by a circle in FIG. As shown in the figure, the center position of the light receiving unit 7 is shifted from the optical axis reflection position in the light transmission direction (X direction). As described above, by forming the angle θ of the end surface on the light receiving unit 7 side, for example, approximately 40 degrees, the light emission region from the light emitting / reflecting surface 4B to the light receiving unit 7 is expanded in the light transmission direction. The light receiving efficiency can be further improved by adopting the above configuration.

(Modification 3)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 9 shows a top view of the optical transmission line 4 as the third modification.

  In the optical transmission line 4 in the present embodiment, as described above, the end face of the core portion 11a and the end face of the core portion 11b are formed on different end faces in the optical transmission line 4, as shown in FIG. The core portions 11a and 11b have bent portions in the transmission medium. Therefore, bending loss occurs at the bent portion. The bending loss is a loss of light caused by bending the optical transmission line 4. When this bending loss occurs, the amount of light received by the light receiving unit 7 decreases, so that stable light transmission becomes difficult and a communication error occurs.

  Here, the bending loss will be described in detail as follows. The light transmitted through the optical transmission line 4 is transmitted in the optical transmission direction by repeating total reflection inside the core unit 11. Here, in order for the light to be totally reflected, the incident angle with respect to the inner surface of the core portion 11 needs to be equal to or larger than a predetermined angle. On the other hand, when the optical transmission line 4 is bent, the probability that the incident angle of light hitting the inner surface of the core portion 11 opposite to the bent direction becomes small increases. As a result, the transmitted light is not totally reflected on the inner surface of the core portion 11, and a part thereof is transmitted to the outside. The loss of light generated here becomes the bending loss. Therefore, in order to reduce this bending loss, it is effective to increase the radius of curvature of the core portion 11 when the optical transmission line 4 is bent.

  Therefore, in the example shown in FIG. 9, the bent portions of the core portions 11 a and 11 b in the optical transmission line 4 are bent at the curvature radius R. Specifically, the curvature radius R is preferably set to 1 to 2 mm in consideration of the size of the optical transmission line 4 and the refractive index difference between the core portions 11a and 11b and the cladding portion 12. Note that the above refractive index difference is generally about 3 to 5% in an optical transmission line for bidirectional communication. If the refractive index difference is smaller than 3%, there is a problem that the loss due to bending increases. Further, when the difference in refractive index is larger than 5%, there are problems that many unnecessary modes occur and high-speed transmission of optical signals becomes difficult.

  According to the configuration of the third modification, since the radius of curvature of the core portions 11a and 11b can be increased, bending loss can be reduced.

(Modification 4)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 10 is a top view of the optical transmission line 4 as the fourth modification.

  In the example shown in the figure, an inclined surface is formed in the bent portion of the core portions 11a and 11b with respect to the optical transmission direction. Even in this configuration, the same effect as the configuration of the third modification, that is, the configuration in which the radius of curvature is increased can be obtained. Furthermore, you may provide a reflective mirror in the said inclined surface. Thereby, since reflection efficiency can be improved, a bending loss can further be reduced.

(Modification 5)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 11 shows a top view of the optical transmission line 4 as the fifth modification. Here, in the rectangular cross-sectional shape of the core portions 11a and 11b, the length of the long side is defined as the lateral width w, and the length of the short side is defined as the thickness d.

  In the example shown in the figure, the lateral width w of the core portions 11a and 11b on the light incident surface 4A of the optical transmission line 4 gradually decreases in a tapered shape as the distance from the light incident surface 4A increases, that is, the lateral width w. Is continuously decreasing. Further, the lateral width w of the core portions 11a and 11b is longer than the thickness d at least on the light incident surface 4A of the core portions 11a and 11b. The lateral width w of the core portions 11a and 11b is set to a preferable range for the purpose of reducing the coupling loss.

  Here, the coupling loss is a loss of light that occurs when light from the light source (corresponding to the light emitting unit 6) enters the optical transmission line 4. This will be described in detail as follows. A certain amount of space is provided between the light source and the optical transmission path 4. This is provided to absorb an error in the installation position of the light source and the optical transmission line 4 and an error in the component size. That is, the light emitted from the light source enters the optical transmission line 4 via the above-described interval. Here, the light emitted from the light source cannot be completely incident on the optical transmission line 4, and the loss of light generated here becomes the coupling loss.

  In high-speed transmission, it is desirable that the light receiving surface of a light receiving element such as a PD constituting the light receiving unit 7 is smaller. This is because, due to the influence of the parasitic capacitance of the light receiving element, which increases as the light receiving surface of the light receiving element increases, the rounding of the signal increases, leading to deterioration in transmission efficiency.

  As described above, the core portions 11a and 11b are set to have a lateral width that reduces the coupling loss on the light incident surface 4A, and gradually decrease in a tapered shape as the distance from the light incident surface 4A increases. Therefore, the area of light emitted radially from the light emitting surfaces of the core portions 11a and 11b can be reduced, and the spot diameter (irradiation area) on the light receiving surface of the light receiving element can be reduced. As a result, the amount of light that can be received even on a small light receiving surface in the light receiving unit 7 can be increased, so that the transmission speed in the optical transmission module 1 can be increased.

(Modification 6)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 12A shows a top view of the optical transmission line 4 as the sixth modification.

  In the example shown in the drawing, four core portions 11 are provided in the optical transmission line 4. Thereby, a large volume of data can be transmitted at high speed in bidirectional communication. Thus, the quantity of the core part 11 is not specifically limited, At least 2 or more should just be provided so that two-way communication is possible, the size of the optical transmission module 1, and data transmission capacity | capacitance The data transmission rate is set in consideration.

  In addition, since the light emission part 6 and the light-receiving part 7 are provided according to the quantity of the core part 11, the data transmission from the 1st communication processing part 2 to the 2nd communication processing part 3 like this modification 6 12 (b) and FIG. 12 in the case where a plurality of data transmission core units 11a and a plurality of data transmission core units 11b from the second communication processing unit 3 to the first communication processing unit 2 are provided. As shown to (c), the light emission part 6 and the light-receiving part 7 can be comprised with an array element. Thereby, while being able to achieve size reduction of the optical transmission module 1, cost can be reduced.

(Modification 7)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 13A shows a top view of the optical transmission line 4 as the modified example 7, and FIG. 13B shows a cross-sectional view of the optical transmission line 4 along the line AA ′ in the Z direction. Yes.

  In the example shown in the figure, in the optical transmission line 4, four core portions 11 are provided in parallel in the X direction and stacked in the Y direction. Thereby, the magnitude | size of the width direction (X direction) of the optical transmission line 4 can be made small. Therefore, according to the optical transmission module according to the modified example 7, in bidirectional communication, a large amount of data can be transmitted at high speed, and the width direction of the optical transmission line 4 can be reduced in size. As described above, according to the configuration in which the plurality of core portions 11 are stacked, even when the number of the core portions 11 is further increased in order to cope with a future increase in data capacity, it is possible to prevent the optical transmission module 1 from being enlarged. Can do.

(Modification 8)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 14 is a top view of the optical transmission line 4 as the eighth modification.

  In the example shown in the figure, two optical transmission lines 4 including two core portions 11a and 11b are provided in parallel. Also with this configuration, it is possible to obtain the same effects as the configurations of the modified examples 6 and 7.

  Further, according to the configuration of the present modification 8, when the small capacity data is transmitted at a low speed, the single optical transmission line 4 is provided, and the large capacity data needs to be transmitted at a high speed. In this case, the optical transmission line 4 can be configured to be suitable for the data transmission capacity, the data transmission speed, etc. Thus, according to the configuration of the optical transmission line 4 described above, versatility of the optical transmission line 4 can be improved. Further, not only the connection between the CPU and the LCD but also the CPU and an application such as a camera module that require high-speed data transmission can be connected in parallel.

(Modification 9)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIGS. 15A and 15B are top views of the optical transmission line 4 as the ninth modification.

  In the example shown in FIG. 15A, both end portions of the optical transmission line 4, that is, the light incident reflection surface 4A and the light output reflection surface 4B are inclined at 45 degrees with respect to the light transmission direction (θ in FIG. 8). In addition, the light receiving unit 6 and the light emitting unit 7 are respectively provided with the central axis of the optical transmission line 4 as a boundary. Further, the core portions 11a and 11b are viewed in a direction in which the extending directions of the core portions 11a and 11b are orthogonal to the light incident reflection surface 4A and the light output reflection surface 4B as viewed from above in FIG. It is the structure bent in the optical transmission line so that. The inclination angles φ1 and φ2 (FIG. 15B) of the light incident reflection surface 4A and the light emission reflection surface 4B formed in a V shape with respect to the central axis are the same so that the light transmission efficiency is optimal. Or different values.

  FIG. 15B is a diagram for explaining functions in the optical transmission line 4 of the ninth modification. As shown in the figure, the optical signal is emitted from the light emitting unit 6 in a direction perpendicular to the optical transmission line 4. On the other hand, the noise light propagating through the clad portion 12 is emitted in a direction corresponding to the inclination angles φ1 and φ2 with respect to the central axis of the optical transmission line 4. Therefore, the inclination angles φ1 and φ2 are set to appropriate angles. By setting to, noise light can be emitted in a direction avoiding the light receiving unit 7, and the influence of noise light via the optical transmission path 4 can be greatly reduced. Note that the positions of the light emitting unit 6 and the light receiving unit 7 in the X direction and the Z direction are changed in the X direction and the Z direction of the optical transmission path 4 by changing the bending positions of the core parts 11a and 11b in the optical transmission path 4. You may comprise so that it may become asymmetric with respect to a central axis.

  According to the configuration of the light transmission path 4 of the present modification 9, the inclination angles φ1 and φ2 of the light incident reflection surface 4A and the light output reflection surface 4B with respect to the central axis of the light transmission path 4 can be easily set to optimum values, respectively. Since it can be set, more stable optical transmission is possible, and the quality of optical transmission can be improved.

(Modification 10)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 16 is a top view of the optical transmission line 4 as the tenth modification.

  In the example shown in the figure, when viewed from the upper side of the drawing, both ends of the light transmission path 4, that is, the light incident reflection surface 4A and the light exit reflection surface 4B are extended in the light transmission path 4 (Z direction). It is the structure formed so that it may incline with respect to. The light emitting unit 6 is disposed immediately below the core 11 at the end of the light transmission path 4 on the light emitting unit 6 side (Y direction), while the light receiving unit 7 is the end of the light transmission path 4 on the light receiving unit 7 side. This is a configuration in which the position is shifted from the position immediately below (Y direction) of the core portion 11 in the direction of emission according to the inclination angle of the light exit reflection surface 4B. As a result, both ends of the optical transmission line 4 are seen in FIG. 16 from the upper side of the drawing as compared to the configuration in which the light transmission part 4 and the light receiving part 6 are perpendicular to the extending direction (Z direction) of the optical transmission line 4. Since the distance between the parts 7 can be increased by Δ1 and Δ2, the influence of noise light can be reduced.

  Here, FIG. 17 and FIG. 18 show a schematic configuration of the optical transmission module 1 when the optical transmission line 4 as the first and eighth modifications is applied to the optical transmission module 1. In the example shown in FIG. 18, one optical transmission path 4 connects the CPU and the LCD driver, and the other optical transmission path 4 connects the CPU and the camera module.

(Modification 11)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIG. 17 shows a top view of the optical transmission line 4 as the eleventh modification.

  In the example shown in the figure, both ends of the optical transmission line 4, that is, the light incident reflection surface 4A and the light output reflection surface 4B are inclined at 45 degrees (θ in FIG. 8) with respect to the light transmission direction, for example. The shape is opposite to the shape of both end portions of the optical transmission line 4 shown in FIG. Note that the inclination angles φ3 and φ4 of the light incident reflection surface 4A and the light emission reflection surface 4B formed in a V shape with respect to the central axis have the same value or different values so that the light transmission efficiency is optimal. Can be set.

  In addition, the light receiving unit 6 and the light emitting unit 7 are each provided with the central axis of the optical transmission line 4 as a boundary. Specifically, the light emitting unit 6 is disposed immediately below the core unit 11 (Y direction) at the end of the optical transmission line 4 on the light emitting unit 6 side, while the light receiving unit 7 is the light receiving unit of the optical transmission line 4. This is a configuration that is shifted from the position immediately below the core 11 (Y direction) at the end portion on the 7 side in the direction of emission according to the inclination angle of the light emission reflection surface 4B. Thereby, both ends of the optical transmission line 4 are compared with the configuration in which the both ends of the optical transmission line 4 are perpendicular to the extending direction (Z direction) of the optical transmission line 4 as viewed from above in FIG. Since the distance between the parts 7 can be increased by Δ3, the influence of noise light can be reduced.

(Modification 12)
In the configuration of the optical transmission line 4 of the present embodiment, another modification of the configuration shown in FIGS. 1A and 1B will be described. FIGS. 18A to 18C are top views of the optical transmission line 4 as the modified example 12, respectively. Each of the optical transmission lines 4 shown in FIGS. 18A to 18C has the same shape as the outer shape of each of the optical transmission lines 4 shown in the modified examples 1, 9, and 11. In the optical transmission line 4 of the present modification 12, each of the light emitting unit and the light receiving unit is arranged on the same end side. Therefore, in each optical transmission line 4, the transmission directions of the optical signals transmitted through the two core portions 11a and 11b are the same.

  Also in the configuration of the optical transmission line 4 of the present modification 12, the distance between the light emitting units and the light receiving units can be increased as compared with the conventional configuration, so that the influence of noise light can be reduced. And stable optical transmission is possible.

  Here, schematic configurations of the optical transmission module 1 in the case where the optical transmission line 4 as the first and eighth modifications are applied to the optical transmission module 1 are shown in FIGS. 19 and 20, respectively. In the example shown in FIG. 20, one optical transmission path 4 connects the CPU and the LCD driver, and the other optical transmission path 4 connects the CPU and the camera module.

(Optical transmission line manufacturing method)
Here, an example of a method for manufacturing the above-described optical transmission line 4 will be briefly described. FIG. 21 is a top view illustrating an example of a method for manufacturing the optical transmission line 4. As the manufacturing method, for example, an optical transmission line can be manufactured by cutting a wafer at once. As described above, the optical transmission path 4 compatible with bidirectional communication capable of stable optical transmission can be manufactured by a simple method. Further, the wafer of the optical transmission line 4 made of a polymer can be manufactured at low cost and with high accuracy by duplication using a mold.

(Application examples)
The optical transmission line 4 of the present embodiment can be applied to the following application examples, for example.

  First, as a first application example, it is used for a hinge part in a foldable electronic device such as a foldable mobile phone, a foldable PHS (Personal Handyphone System), a foldable PDA (Personal Digital Assistant), and a foldable notebook personal computer. it can.

  FIGS. 22A and 22B show an example in which the optical transmission line 4 is applied to a foldable mobile phone 40. That is, FIG. 22A is a perspective view showing the appearance of a foldable mobile phone 40 with the built-in optical transmission path 4.

  FIG. 22B is a perspective plan view of the hinge portion (portion surrounded by a broken line) in FIG. As shown in this figure, the optical transmission line 4 is connected to a control unit provided on the main body side, a display unit provided on the lid side, and the like by being wound and bent around a holding rod in the hinge part. ing.

  By applying the optical transmission line 4 to these foldable electronic devices, high-speed and large-capacity communication can be realized in a limited space. Therefore, it is particularly suitable for devices that require high-speed and large-capacity data communication, such as a foldable liquid crystal display device, and are required to be downsized.

  As a second application example, the optical transmission line 4 can be applied to an apparatus having a drive unit such as a printer head in a printing apparatus (electronic device) or a reading unit in a hard disk recording / reproducing apparatus.

  FIG. 23A and FIG. 23B show an example in which the optical transmission path 4 is applied to the printing apparatus 50. FIG. 23A is a perspective view showing the appearance of the printing apparatus 50. As shown in this figure, the printing apparatus 50 includes a printer head 51 that performs printing on the paper 52 while moving in the width direction of the paper 52, and one end of the optical transmission path 4 is connected to the printer head 51. Has been.

  FIG. 23B is a block diagram of a portion to which the optical transmission path 4 is applied in the printing apparatus 50. As shown in this figure, one end of the optical transmission line 4 is connected to a printer head 51, and the other end is connected to a main body side substrate 53 in the printing apparatus 50. The main body side substrate 53 is provided with control means for controlling the operation of each part of the printing apparatus 50.

  Therefore, the optical transmission line 4 according to the present embodiment is suitable for these driving units. Further, by applying the optical transmission line 4 to these drive units, high-speed and large-capacity communication using the drive units can be realized.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  The optical transmission line module and the optical transmission line in the present invention can be applied to an optical communication path between various devices, and can also be used as a flexible optical wiring as a wiring in a device mounted in a small and thin consumer device. Applicable.

(A) is a perspective view which shows schematic structure of the optical transmission path in this embodiment, FIG.1 (b) is the top view. It is a figure which shows schematic structure of the optical transmission module in this embodiment. It is a figure which shows typically the state of the optical transmission in an optical transmission line. It is a top view which shows another structure of the optical transmission line shown in FIG.1 (b). (A) is a perspective view which shows schematic structure of the optical transmission line as the modification 1, (b) is the top view. (A) is sectional drawing of the Z direction in the optical transmission line of the modification 1, (b) is a side view of a X direction. FIG. 10 is a top view illustrating a schematic configuration of an optical transmission line as a second modification. FIG. 8 is an enlarged cross-sectional view of a portion A surrounded by a circle in FIG. 7. FIG. 10 is a top view illustrating a schematic configuration of an optical transmission line as a third modification. FIG. 10 is a top view illustrating a schematic configuration of an optical transmission line as a fourth modification. FIG. 10 is a top view illustrating a schematic configuration of an optical transmission line as a fifth modification. (A) is a top view which shows schematic structure of the optical transmission line as the modification 6, (b) is a top view which shows the state which comprised the light emission part by the array element, (c) is light reception. It is a top view which shows the state which comprised the part by the array element. (A) is a top view which shows schematic structure of the optical transmission line as the modification 7, (b) is AA 'sectional drawing of this optical transmission line 4. FIG. FIG. 10 is a top view showing a schematic configuration of an optical transmission line as a modification example 8. (A) and (b) are the top views which show schematic structure of the optical transmission line as the modification 9. As shown in FIG. FIG. 16 is a top view illustrating a schematic configuration of an optical transmission line as a tenth modification. FIG. 16 is a top view showing a schematic configuration of an optical transmission line as a modification 11. (A)-(c) is a top view which shows schematic structure of the optical transmission line as the modification 12. FIG. It is a top view which shows schematic structure of the optical transmission module at the time of applying the optical transmission line as the modification 1 to an optical transmission module. It is a top view which shows schematic structure of the optical transmission module at the time of applying the optical transmission line as the modification 8 to an optical transmission module. It is a top view which shows an example of the manufacturing method of an optical transmission line. (A) is a perspective view which shows the external appearance of the foldable mobile phone provided with the optical transmission line according to the present embodiment, and (b) is a perspective view of the hinge part in the foldable mobile phone shown in (a). It is a top view. (A) is a perspective view which shows the external appearance of the printing apparatus provided with the optical transmission line concerning this embodiment, (b) is a block diagram which shows the principal part of the printing apparatus shown to (a). (A) is a perspective view which shows the external appearance of an optical transmission module, (b) is a perspective view which shows the internal appearance of the mobile telephone provided with this optical transmission module. It is a top view which shows the state which connected between the board | substrates provided in an apparatus with the conventional optical transmission module. It is a figure which shows schematic structure of the conventional optical transmission module. It is a figure which shows schematic structure of the conventional optical transmission module. It is a figure which shows schematic structure of the conventional optical transmission module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical transmission line module 2 1st communication processing part 3 2nd communication processing part 4 Optical transmission line 4A Light incident reflective surface (light incident surface)
4B Light exit reflection surface (light exit surface)
5 Light emission drive unit 6 Light emission unit (light source)
7 Amplifying section 8 Light receiving section 11, 11a, 11b Core section 12 Clad section

Claims (12)

The core includes at least two core portions made of a light-transmitting material and a clad portion made of a material having a refractive index different from the refractive index of the core portion. The light that is introduced into the core part from the light incident surface of the part and transmitted through the core part is configured to be emitted to the outside from the light emitting surface of the core part, thereby enabling bidirectional light transmission. An optical transmission line,
The light incident surface of the first core unit and the light emitting surface of the core unit different from the first core unit, and the light emitting surface of the first core unit and the core unit different from the first core unit The light transmission paths are provided on different outer faces among the outer faces forming the optical transmission path. The light incident surface and the light exit surface of the core part are formed obliquely with respect to the light transmission direction when light is transmitted in the core part,
Light emitted from the light source is introduced into the core part by being reflected at the light incident surface, and light transmitted within the core part is emitted to the outside by being reflected at the light exit surface. The optical transmission line according to claim 1, wherein the optical transmission line is configured as described above.   The light transmission path according to claim 2, wherein the light incident surface and the light emitting surface of the core portion are formed at 45 degrees with respect to the light transmission direction.   The light incident surface of the core portion is formed at 45 degrees with respect to the light transmission direction, while the light emission surface of the core portion is formed at approximately 40 degrees with respect to the light transmission direction. The optical transmission line according to claim 2.   The core portion has a radius of curvature of the central axis of the core portion in a range of 1 to 2 mm when bent in a direction different from the extending direction of the optical transmission path in the optical transmission path. The optical transmission line according to any one of claims 1 to 4, wherein the optical transmission line is formed. In the optical transmission line, the core part is bent in a direction different from the extending direction of the optical transmission line, and the bent part is in the optical transmission direction when light is transmitted in the core part. And diagonally formed,
The light transmitted in the core portion is configured to be reflected toward the light emitting surface side in the obliquely formed bent portion. An optical transmission line as described in 1.   The optical transmission path according to claim 6, wherein the bent portion is provided with a reflecting plate that reflects light transmitted in the core portion. In the cross section perpendicular to the light transmission direction when light is transmitted in the core portion, the length of the core portion in the first direction as the bending direction that most permits the bending of the light transmission path is the thickness d, When the length of the core portion in the second direction perpendicular to the direction of 1 is the lateral width w,
At least in the light incident surface of the core portion, the lateral width w is longer than the thickness d,
The optical transmission line according to claim 1, wherein the lateral width w decreases from an entrance on the light incident side toward an exit on the light exit side.   The light transmission according to any one of claims 2 to 8, wherein a reflecting plate that reflects light emitted from a light source is provided on a light incident surface and a light emitting surface of the core portion. Road. The optical transmission line according to any one of claims 1 to 9,
At least two light emitting units for irradiating light to the light incident surface of the light transmission path;
An optical transmission module comprising: at least two light receiving units that receive light emitted from a light emitting surface of the optical transmission path. The light emitting unit irradiates light from the direction substantially perpendicular to the light transmission direction in the light transmission path with respect to the light transmission path,
The optical transmission module according to claim 10, wherein the optical transmission path introduces light emitted from the light emitting unit into the core unit by reflecting the light on a light incident surface.   An electronic apparatus comprising the optical transmission module according to claim 10.