JP7210120B2 - Optical coupling structure, optical coupling method, camera module - Google Patents

Description

The present invention relates to an optical coupling structure, an optical coupling method, and a camera module.

2. Description of the Related Art Conventionally, as one form of communication for transmitting data, optical proximity space transmission by a non-contact system has been used. Optical proximity space transmission converts electrical signals such as video and audio into optical signals for transmission, and converts them back into electrical signals on the receiving side for use (see Patent Document 1, for example). Specifically, an electrical signal is emitted as an optical signal from a light-emitting element such as a laser diode, transmitted to a receiver via a transmission means such as an optical fiber, and converted from the optical signal to an electrical signal in the receiver for use. .

In addition, in a conventional optical coupling structure for communication using light, loss of light is reduced by providing a lens between a light emitting element and an optical fiber for suppressing diffusion of light emitted from the light emitting element. Reliability of communication is improved by suppressing it and increasing the efficiency of light incident on the optical fiber.

Japanese Unexamined Patent Application Publication No. 2004-064430

Since the optical coupling structure is characterized by the fact that light travels straight, it is necessary to improve the positional accuracy of components that transmit and receive light. However, in the conventional optical coupling structure, when assembling parts such as a light-emitting element, a lens, and an optical fiber, alignment work for aligning the inclination and position of the light-emitting element, the lens, and the optical fiber is complicated and time-consuming. There is a problem that the manufacturing cost increases.

Therefore, the present invention focuses on the above-described problems, and provides an optical coupling structure, an optical coupling method, and a camera module capable of improving alignment workability during assembly and suppressing manufacturing costs. The purpose is to

The optical coupling structure of the present invention is an optical coupling structure for optical transmission between a photoelectric element having a light emitting portion or a light receiving portion and an optical fiber, the optical coupling structure having parallel first and second surfaces and a thickness direction of and an optical system in the light emitting unit or the light receiving unit, and attached to the first surface of the substrate so that the optical system faces the inside of the through hole. The photoelectric element, the optical fiber having an open end facing the photoelectric element on the second surface side of the through hole, and a bottomed cylindrical shape surrounding and holding the end of the optical fiber. and a bottomed cylindrical alignment jig that surrounds and holds the ferrule and is fixed to the second surface of the substrate with the bottom surface in contact with the second surface , A counterbore portion is formed on the second surface of the substrate by cutting in the thickness direction of the substrate, and the bottom surface of the counterbore portion is parallel to the second surface. The ferrule is abutted and fitted.

INDUSTRIAL APPLICABILITY The present invention can provide an optical coupling structure, an optical coupling method, and a camera module capable of improving workability of alignment during assembly and suppressing manufacturing costs.

It is a sectional view showing typically an optical coupling structure concerning one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a camera module having the optical coupling structure shown in FIG. 1; 1. It is sectional drawing which shows typically the modification of the optical coupling structure shown in FIG. 1. It is sectional drawing which shows typically the other modified example of the optical coupling structure shown in FIG. 1. It is sectional drawing which shows typically the other modified example of the optical coupling structure shown in FIG.

An optical coupling structure, an optical coupling method, and a camera module according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. The optical coupling structure 100 of the present embodiment has a substrate and can be widely applied to optical transmission between a photoelectric element having a light emitting portion or a light receiving portion and an optical fiber. be able to. In addition, the camera module 200 of the present embodiment can be applied, for example, as an imaging component of an in-vehicle camera such as a drive recorder.

[Optical Coupling Structure and Optical Coupling Method]
As shown in FIG. 1, the optical coupling structure 100 includes a substrate 10, a light emitting element 20 (photoelectric element), an optical fiber 30, a ferrule 40, and an alignment jig 50.

A through hole 11 is formed through the substrate 10 in the thickness direction, and the substrate 10 has a back surface 12 (first surface) provided with a PAD 15 to which the light emitting element 20 is attached, and an optical fiber 30 is attached. , and a front surface 13 (second surface). In the substrate 10 , the front surface 13 and the back surface 12 are parallel, and the through hole 11 is perpendicular to the front surface 13 and the back surface 12 . Further, the light emitting element 20 is attached to the opening of the through hole 11 on the back surface 12 side, and the open end 31 of the optical fiber 30 is arranged on the opening of the through hole 11 on the front surface 13 side. , the light emitting element 20 and the open end 31 of the optical fiber 30 face each other.

If the light L from the light emitting element 20 is reflected on the inner surface of the through hole 11, the phase of the light L changes and noise may occur. is preferred. Therefore, it is preferable that the inner surface of the through hole 11 is not coated so as not to reflect the light L from the light emitting element 20 .

The light-emitting element 20 includes a light-emitting element main body 21 having a light-emitting portion 21a, a spherical lens 22 (optical system) attached to the light-emitting portion 21a side of the light-emitting element main body 21, a terminal 23 provided on the light-emitting portion 21a side, have The surface of the light emitting element 20 on the side of the spherical lens 22 is attached to the back surface 12 of the substrate 10 so that the spherical lens 22 faces the inside of the through hole 11 of the substrate 10 . A terminal 23 is provided on the upper surface (the surface on the spherical lens 22 side) of the light emitting element main body 21 .

Also, the light L emitted from the light emitting element main body 21 is designed to converge through the spherical lens 22 . The spherical lens 22 is formed by considering the amount of light L emitted from the light emitting element 20, the degree of diffusion, and the distance to the open end 31 of the optical fiber 30, that is, the size of the through hole 11 of the substrate 10. It is preferable to choose a lens with a focal length that causes as little loss as possible.

With the light emitting element 20 attached to the substrate 10 , the optical axis of the light emitting element 20 is parallel to the through hole 11 of the substrate 10 and perpendicular to the back surface 12 of the substrate 10 .

The terminal 23 is, for example, an annular plate-like member made of metal, is provided on the upper surface of the light emitting element main body 21 , and is electrically connected to the PAD 15 provided on the substrate 10 . The terminal 23 functions as a terminal for inputting electrical signals to the light emitting element 20 . Further, for example, in a state in which the PAD 15 provided on the back surface 12 of the substrate 10 and the terminal 23 are electrically connected, the terminal 23 and the PAD 15 are bonded using a conductive adhesive. Thereby, the substrate 10 and the light emitting element 20 are physically fixed.

A method of electrically connecting the PAD 15 and the terminal 23 is not particularly limited, and may be performed by a wire or the like. In general, a light-emitting element is provided with terminals on its lower surface (the surface opposite to the light-emitting portion), and the terminals are electrically connected to the substrate by connecting wires to the terminals. A light-emitting element having a terminal on the bottom surface may be applied to the optical coupling structure 100 of this embodiment, but it is necessary to extend and connect a wire from the terminal on the bottom surface of the light-emitting element to the PAD on the back surface of the substrate. Furthermore, it is necessary to physically fix the upper surface of the light emitting element and the lower surface of the substrate using a non-conductive adhesive or the like.

On the other hand, in the connection method using the terminal 23 of the light emitting element 20 and the PAD 15 of the present embodiment, the physical fixing of the light emitting element 20 and the substrate 10 and the electrical connection between the terminal 23 and the PAD 10 are combined into one. It is possible to reduce the manufacturing cost by omitting the wire attachment process. Moreover, since this connection method does not cause wire deterioration or disconnection, the connection reliability can be improved, and it can be suitably used in the present embodiment.

The optical fiber 30 has an open end 31 facing the light emitting element 20 through the through hole 11 of the substrate 10 . In the optical fiber 30 , the light L emitted from the light emitting element 20 enters from the open end 31 on the light emitting element 20 side and is transmitted inside the optical fiber 30 .

Since the optical fiber 30 is easier to handle and less expensive than an optical fiber made of only glass, it does not require soldering between the substrate 10 and the ferrule 40 as will be described later, and is less affected by heat. Therefore, optical fibers containing plastic can be preferably used. Optical fibers containing plastic include optical fibers made only of plastic, optical fibers made of plastic and glass, and the like.

The ferrule 40 is a member that surrounds and holds the end portion of the optical fiber 30. The ferrule body 41 has a bottomed tubular shape (for example, a cylindrical shape) having a bottom surface 41a, and the ferrule body 41 is provided so as to pass through the ferrule body 41. and an optical fiber holding portion 42 for holding the optical fiber 30 . Further, in the optical coupling structure 100 , the bottom surface 41 a on the tip side of the ferrule 40 is in contact with the front surface 13 (second surface) of the substrate 10 .

The alignment jig 50 surrounds and holds the ferrule 40 and has a bottomed tubular shape (for example, a cylindrical shape) fixed to the front surface 13 of the substrate 10 with the bottom surface 51 a in contact with the front surface 13 . is a member of Also, a member for aligning the optical axis of the light emitting element 20 and the optical fiber 30, a bottomed cylindrical alignment jig main body 51 having a bottom surface 51a, and a ferrule insertion portion for inserting the ferrule 40 52. In addition, the outer shape of the ferrule 40 and the inner shape of the ferrule inserting portion 52 of the alignment jig 50 are substantially the same. 50 can be integrated without positional deviation.

The bottom surface 51a of the alignment jig 50 is perpendicular to the optical axis of the optical fiber 30 when the ferrule 40 is inserted. Further, in a state in which the bottom surface 51 a of the alignment jig 50 is in contact with the front surface 13 of the substrate 10 , the optical axis of the optical fiber 30 is parallel to the through hole 11 and the front surface 13 of the substrate 10 . and perpendicular to

Next, the optical coupling method of this embodiment will be described. The optical coupling method of the present embodiment is a method of assembling the optical coupling structure 100 described above, which has a parallel flat surface 12 and a front surface 13, and a through hole 11 penetrating in the thickness direction is formed. a step of attaching a light emitting element 20 having a spherical lens 22 in a light emitting portion 21a to the rear surface 12 of the substrate 10 so that the spherical lens 22 faces the inside of the through hole 11 of the substrate 10; The bottomed tubular alignment jig 50 holding the bottomed tubular ferrule 40 held by the holder is placed on the front surface so that the open end 31 of the optical fiber 30 and the light emitting element 20 face each other in the through hole 11 . 13, performing active alignment between the optical axis of the light emitting element 20 and the optical axis of the optical fiber 30, and after the active alignment, the alignment jig 50 is placed on the substrate. and securing to the front surface 13 of . These steps will be specifically described below.

First, the light emitting element 20 is attached to the back surface 12 of the substrate 10 . At this time, the spherical lens 22 of the light emitting element 20 is made to face the inside of the through hole 11 . Furthermore, in a state in which the PAD 15 provided on the back surface 12 of the substrate 10 and the terminal 23 are electrically connected, the terminal 23 and the PAD 15 are bonded using a conductive adhesive. Thereby, the substrate 10 and the light emitting element 20 are physically fixed so that the optical axis of the light emitting element 20 is parallel to the through hole 11 .

Next, the optical fiber 30 is attached. The ferrule 40 holding the optical fiber 30 inside is inserted into the alignment jig 50, and the optical fiber 30, the ferrule 40, and the alignment jig 50 are assembled in a state where the tip positions of the ferrule 40 and the alignment jig 50 are aligned. are integrated. Further, the bottom surface 51 a of the alignment jig 50 holding the ferrule 40 is brought into contact with the front surface 13 of the substrate 10 . At this time, the optical axis of the light emitting element 20 is perpendicular to the back surface 12 of the substrate 10 and the optical axis of the optical fiber 30 is perpendicular to the front surface 13 of the substrate 10 . Further, the back surface 12 and the front surface 13 of the substrate 10 are parallel. As a result, the open end 31 of the optical fiber 30 and the light emitting element 20 face each other, and the optical axis of the light emitting element 20 and the optical axis of the optical fiber 30 are held parallel.

Furthermore, by adjusting the position of the alignment jig 50, active alignment of the optical axes of the light emitting element 20 and the optical fiber 30 is performed. At this time, the optical axis of the light emitting element 20 and the optical axis of the optical fiber 30 are held parallel as described above. In the direction in which the light emitting element 20 and the open end 31 of the optical fiber 30 face each other, the distance between the light emitting element 20 and the open end 31 of the optical fiber 30 is kept constant (to the thickness dimension of the substrate 10). Therefore, when active alignment of the optical axis is performed, only alignment in the horizontal plane parallel to the substrate 10 may be performed, and alignment in the relative direction for distance and tilt may not be performed.

After the alignment of the optical axis is completed, the alignment jig 50 and the substrate 10 are connected by soldering. At this time, the heat of soldering is not directly applied to the optical fiber 30 and the ferrule 40 . Also, the method of connecting the alignment jig 50 and the substrate 10 is not particularly limited, and a connection method other than soldering may be used. As described above, the assembly of the optical coupling structure 100 is completed.

In the assembled optical coupling structure 100, as shown in FIG. 1, the light L emitted from the light emitting element 20 is condensed when passing through the spherical lens 22 and passes through the through hole 11 of the substrate 10. and enters the open end 31 of the optical fiber 30 . Light entering the optical fiber 30 is transmitted through the inside of the optical fiber 30 . In this way, light can be transmitted through the optical coupling structure 100 .

The optical coupling structure 100 of this embodiment is an optical coupling structure for optical transmission between a light emitting element 20 having a light emitting portion 21a and an optical fiber 30, and has a parallel helical surface 12 and a front surface 13. , a substrate 10 having a through hole 11 penetrating in the thickness direction, and a spherical lens 22 in a light emitting portion 21a. a light emitting element 20 provided with a light emitting element 20 formed thereon, an optical fiber 30 provided with an open end 31 facing the light emitting element 20 on the front surface 13 side of the through hole 11, and an end portion of the optical fiber 30 being surrounded and held. , a cylindrical ferrule 40 with a bottom having a bottom surface 41a in contact with the front surface 13 of the substrate 10, and the ferrule 40 are surrounded and held, and the bottom surface 51a is in contact with the front surface 13 of the substrate 10, and a bottomed cylindrical alignment jig 50 fixed to the front surface 13 .

In the optical coupling structure 100 of this embodiment, the optical axis of the light emitting element 20 and the optical axis of the optical fiber 30 are held parallel. In the direction in which the light emitting element 20 and the open end 31 of the optical fiber 30 face each other, the distance between the light emitting element 20 and the open end 31 of the optical fiber 30 is kept constant (to the thickness dimension of the substrate 10). Therefore, when performing active alignment of the optical axis, it is only necessary to perform alignment in a horizontal plane parallel to the substrate 10 . Therefore, with the optical coupling structure 100 of the present embodiment, it is possible to improve the workability of alignment during assembly and reduce the manufacturing cost.

In addition, according to the optical coupling method of the present embodiment, since the optical coupling structure 100 is used, when performing active alignment of the optical axis, it is only necessary to perform alignment in a horizontal plane parallel to the substrate 10, which improves alignment workability. can be improved, and manufacturing costs can be suppressed.

[The camera module]
Next, the camera module 200 of this embodiment will be described. As shown in FIG. 2 , the camera module 200 includes a housing 210 , an imaging module 220 , a system section 230 having a substrate 231 on which system ICs and the like are mounted, and an optical communication module 240 . The imaging module 220 , the system section 230 and the optical communication module 240 are provided inside the housing 210 .

The imaging module 220 includes a lens portion 221 provided in the opening 211 of the housing 210, and a substrate 222 provided with an imaging element such as a CCD sensor and photoelectrically converting light received through the lens portion 221. . The optical communication module 240 is a member that transmits a video signal to an external device by optical communication, and has the above-described optical coupling structure 100 and a connector 241 that connects the optical coupling structure 100 and the external device.

Since the camera module 200 of the present embodiment includes the optical coupling structure 100, it is possible to improve the alignment workability and reduce the manufacturing cost when assembling the optical coupling structure 100. FIG.

It should be noted that the present invention is not limited to the above-described embodiments, but includes other configurations and the like that can achieve the object of the present invention, and the following modifications and the like are also included in the present invention. In the following modified examples, the same reference numerals are given to the same configurations as in the above-described embodiment, and the description thereof is omitted.

In the above-described embodiments, a spherical lens is used as the optical system, but an aspherical lens may be used instead of the spherical lens to condense the light from the light emitting element. In addition, it is only necessary to suppress the light from the light emitting element from being diffused and lost. Instead of using a condensing lens, the light LA from the light emitting element 20A is collimated as in the optical coupling structure 100A shown in FIG. A different collimating lens 22A may be used. However, since a spherical lens such as a ball lens is cheaper than an aspherical lens or a collimating lens, a spherical lens is preferably used in the optical coupling structure of the present invention in order to reduce manufacturing costs.

Further, in the optical coupling structure, the substrate may be provided with a counterbore. FIG. 4 is a cross-sectional view schematically showing an optical coupling structure 100B in which a counterbore 14 is formed on a substrate 10B. A counterbore portion 14 is formed in the substrate 10B by notching the front surface 13 of the substrate 10B in the thickness direction, and a ferrule 40 is fitted in the counterbore portion 14 . The inner shape of the counterbore portion 14 is formed slightly larger than the outer shape of the ferrule 40 in order to align the optical axes of the light emitting element 20 and the optical fiber 30B.

A bottom surface 14 a of the counterbore portion 14 is parallel to the front surface 13 of the substrate 10 . In the optical coupling structure 100</b>B, the ferrule 40 is held by the alignment jig 50 with the bottom surface 41 a of the ferrule 40 projecting beyond the bottom surface 51 a of the alignment jig 50 . Using the alignment jig 50 holding the ferrule 40 , the bottom surface 41 a at the tip of the ferrule 40 is brought into contact with the bottom surface 14 a of the counterbore portion 14 , and the bottom surface 51 a at the tip of the alignment jig 50 is brought into contact with the front side of the substrate 10 . It is brought into contact with the surface 13 and fixed. As a result, the optical axis of the optical fiber 30 becomes parallel to the through hole 11 and perpendicular to the bottom surface 14 a of the counterbore 14 , similarly to the optical coupling structure 100 .

By forming the counterbore portion 14, the distance between the light emitting element 20 and the optical fiber 30B can be shortened, and the light from the light emitting element 20 can be incident on the optical fiber 30B in a state in which the light is more condensed. can. Therefore, compared with the optical fiber 30 used in the optical coupling structure 100 in which the counterbore 14 is not formed, the optical fiber 30B having a finer core wire can be used. By adjusting the depth dimension of the counterbore portion 14, the distance between the light emitting element 20 and the optical fiber 30B can be set to a desired dimension.

Moreover, the present invention can also be applied to an optical coupling structure having a light receiving element as a photoelectric element. The optical coupling structure 100C shown in FIG. 5 includes a light receiving element 60 as a photoelectric element. The light receiving element 60 has a light receiving element main body 61 , a light receiving portion 61 a , a spherical lens 22 and terminals 63 . In the optical coupling structure 100</b>C, light enters from the open end opposite to the open end 31 of the optical fiber 30 and is transmitted to the open end 31 through the inside of the optical fiber 30 . Furthermore, the light LC passes through the through hole 11 of the substrate 10 from the open end 31 of the optical fiber 30 and reaches the spherical lens 22 . The light LC is condensed by the spherical lens 22 and received by the light receiving portion 61a.

In the optical coupling structure 100C, the distance and inclination in the relative direction between the light receiving element 60 and the optical fiber 30 are aligned with the front surface 13 and the back surface 12 of the substrate 10, as in the optical coupling structure 100 of the above-described embodiment. Therefore, it is not necessary to align the distance and the inclination in the relative direction. Therefore, with the optical coupling structure 100C, the workability of alignment during assembly can be improved, and the manufacturing cost can be suppressed.

In addition, although the best configuration, method, etc. for carrying out the present invention have been disclosed in the above description, the present invention is not limited thereto. Thus, although the present invention has been particularly illustrated and described primarily with respect to certain embodiments, it may be modified in any manner to such embodiments without departing from the spirit and scope of the invention. , materials, quantity, and other detailed configurations can be modified in various ways by those skilled in the art.

Therefore, the descriptions that limit the shape, material, etc. disclosed above are exemplified to facilitate understanding of the present invention, and do not limit the present invention. The description by the name of the member that removes all or part of the limitation such as is included in the present invention.

100, 100A, 100B, 100C Optical coupling structure 200 Camera module 10 Substrate 11 Through hole 12 Back surface (first surface)
13 Front surface (second surface)
14 Counterbore 14a Bottom surface 15 of counterbore 14 PAD
20 light-emitting element (photoelectric element)
21a light emitting unit 22 spherical lens (optical system)
22A collimating lens (optical system)
23, 63 Terminals 30, 30B Optical fiber 40 Ferrule 41a Bottom surface 50 Alignment jig 51a Bottom surface 60 Light receiving element (photoelectric element)
61a light receiving part

Claims (6)

An optical coupling structure for optical transmission between a photoelectric element having a light emitting portion or a light receiving portion and an optical fiber,
a substrate having a parallel first surface and a second surface and having a through hole penetrating in the thickness direction;
the photoelectric element having an optical system in the light emitting part or the light receiving part and attached to the first surface of the substrate so that the optical system faces the inside of the through hole;
the optical fiber having an open end facing the photoelectric element on the second surface side of the through hole;
a cylindrical ferrule with a bottom that surrounds and holds the end of the optical fiber;
a bottomed cylindrical alignment jig that surrounds and holds the ferrule and is fixed to the second surface of the substrate with the bottom surface in contact with the second surface ;
a counterbore formed by cutting in the thickness direction of the substrate is formed on the second surface of the substrate, and a bottom surface of the counterbore is parallel to the second surface;
An optical coupling structure in which the ferrule is fitted in contact with the bottom surface of the counterbore . the optical axis of the photoelectric element is perpendicular to the first surface of the substrate, and the optical axis of the optical fiber is perpendicular to the second surface of the substrate;
2. The optical coupling structure according to claim 1, wherein the optical axis of said photoelectric element and the optical axis of said optical fiber are held parallel. 3. An optical coupling structure according to claim 1 or 2, wherein said optical fiber is an optical fiber comprising plastic. The optical coupling structure according to any one of claims 1 to 3, wherein the terminals of the photoelectric element are provided on the optical system side of the photoelectric element. a substrate having a parallel first surface and a second surface and having a through hole penetrating in the thickness direction;
a photoelectric element having an optical system in a light emitting portion or a light receiving portion;
an optical fiber;
a cylindrical ferrule with a bottom that surrounds and holds the end of the optical fiber;
a cylindrical alignment jig with a bottom that surrounds and holds the ferrule,
The optoelectronic device is formed by using an optical coupling structure in which a counterbore is formed on the second surface of the substrate by cutting in a thickness direction of the substrate, and a bottom surface of the counterbore is parallel to the second surface. An optical coupling method for optical transmission between and the optical fiber,
a step of mounting the photoelectric element on the first surface of the substrate such that the optical system faces the inside of the through hole of the substrate ;
The bottom surface of the alignment jig is brought into contact with the second surface so that the open end of the optical fiber and the photoelectric element face each other in the through hole, and the a step of bringing the ferrule into contact with the bottom surface ;
performing active alignment between the optical axis of the photoelectric element and the optical axis of the optical fiber;
and fixing the alignment jig to the second surface of the substrate after active alignment. A camera module comprising the optical coupling structure according to any one of claims 1 to 4 .

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