KR102665420B1 - Optical coupling structure, optical coupling method, camera module - Google Patents

Abstract

[Project] Provide an optical coupling structure, optical coupling method, and camera module that can improve alignment workability during assembly and reduce manufacturing costs.
[Solution] An optical coupling structure that transmits light between a light emitting element 20 having a light emitting portion 21a and an optical fiber 30, has a parallel back surface 12 and a surface 13, and has a thickness. It has a substrate 10 on which a through hole 11 penetrating in the direction is formed, and a spherical lens 22 in the light emitting portion 21a, and the spherical lens 22 is directed to the inside of the through hole 11. On the side of the light emitting element 20 mounted on the back surface 12 of the substrate 10 and the surface 13 of the through hole 11, the opening end 31 is opposite to the light emitting element 20. In addition to surrounding and holding the installed optical fiber 30 and the end portion of the optical fiber 30, the bottom surface 41a is in contact with the surface 13 of the substrate 10. ), a normal ferrule 40 with a flat bottom, and the ferrule 40 is surrounded and held, and the bottom surface 51a is in contact with the surface 13 of the substrate 10, A regular bottomed jig (50) is provided, fixed to (13).

Description

Optical coupling structure, optical coupling method, camera module {OPTICAL COUPLING STRUCTURE, OPTICAL COUPLING METHOD, CAMERA MODULE}

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

Conventionally, as a form of communication for transmitting data, non-contact optical proximity space transmission has been used. Optical near-space transmission converts electrical signals, such as video or audio, into optical signals for transmission, and converts them back into electrical signals on the receiving side for use (for example, see Patent Document 1). Specifically, an electric signal is emitted as an optical signal from a light emitting element such as a laser diode, and is transmitted to a receiving device through a transmission means such as an optical fiber, and the receiving device converts the optical signal into an electric signal for use.

In addition, in the conventional optical coupling structure for communication using light, loss of light is suppressed by installing a lens between the light-emitting element and the optical fiber to suppress the diffusion of light emitted from the light-emitting element, and the loss of light into the optical fiber is suppressed. By increasing the incident efficiency of light, the reliability of communication is being improved.

Japanese Patent Publication No. 2004-64430

In the light coupling structure, since light has the characteristic of excellent straight travel, it is necessary to increase the positional accuracy of the components that transmit and receive light. However, in the conventional optical coupling structure, when assembling components such as light-emitting elements, lenses, and optical fibers, the alignment work of adjusting the inclination and position of the light-emitting elements, lenses, and optical fibers becomes complicated and time-consuming, thereby reducing manufacturing costs. There was a problem that was increasing.

Therefore, the present invention focuses on the above problems and aims to provide an optical coupling structure, an optical coupling method, and a camera module that can improve alignment workability during assembly and reduce manufacturing costs. Do this.

The optical coupling structure of the present invention transmits light between a photoelectric element having a light emitting portion or a light receiving portion and an optical fiber, and includes a first surface and a second surface extending parallel to the first surface. The photoelectric device has a substrate having a surface and a through hole formed therethrough in the thickness direction, and an optical system in the light emitting unit or the light receiving unit, and is mounted on the first surface of the substrate so that the optical system is directed to the inside of the through hole. an element, and, on the side of the through hole facing the second surface, an optical fiber with an open end facing the photoelectric element, and an end portion of the optical fiber that surrounds and holds the optical fiber. At the same time, a normal ferrule with a bottom whose bottom is in contact with the second surface of the substrate, and a ferrule that surrounds and holds the ferrule, are provided on the second surface of the substrate. The bottom is in contact with the second surface, and a regular bottomed jig is provided, which is fixed to the second surface.

The present invention can provide an optical coupling structure, an optical coupling method, and a camera module that can improve alignment workability during assembly and reduce manufacturing costs.

1 is a cross-sectional view schematically showing an optical coupling structure according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing a camera module including the light coupling structure shown in FIG. 1.
FIG. 3 is a cross-sectional view schematically showing a modified example of the light coupling structure shown in FIG. 1.
FIG. 4 is a cross-sectional view schematically showing another modification of the light coupling structure shown in FIG. 1.
FIG. 5 is a cross-sectional view schematically showing another modified example of the light coupling structure shown in FIG. 1.

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

[Light coupling structure, and light 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 penetrating in the thickness direction is formed in the substrate 10, and the substrate 10 has a back surface 12 (see section 12) on which a PAD 15 on which the light emitting element 20 is mounted is provided. first side) and a surface 13 (second side) on which the optical fiber 30 is mounted. 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. In addition, the light emitting element 20 is mounted in the opening on the back surface 12 side of the through hole 11, and the opening end 31 of the optical fiber 30 is installed in the opening on the surface 13 side of the through hole 11. As it is arranged, the light emitting element 20 and the open end 31 of the optical fiber 30 face each other.

In addition, 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 may change, which may cause noise. It is desirable not to reflect the light L of the light emitting element 20 on the inner surface. Therefore, it is preferable that the inner surface of the through hole 11 is not coated so that the light L of the light emitting device 20 is not reflected.

The light emitting element 20 includes a light emitting element main body 21 having a light emitting unit 21a, a spherical lens 22 (optical system) mounted on the light emitting unit 21a side of the light emitting element main body 21, and , has a terminal 23 installed on the light emitting portion 21a side. In addition, the light emitting element 20 is mounted on 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. It is done. Additionally, a terminal 23 is provided on the upper surface of the light emitting element body 21 (the surface on the spherical lens 22 side).

Additionally, the light L emitted from the light emitting element body 21 is designed to be condensed through the spherical lens 22. The spherical lens 22 determines the amount of light L emitted from the light emitting element 20, the degree of diffusion, the distance to the opening end 31 of the optical fiber 30, that is, the through hole of the substrate 10 ( Considering the dimensions of 11), it is desirable to select a lens with a focal length such that the loss of light L is as small as possible.

In the state where the light emitting element 20 is mounted on the substrate 10, the optical axis of the light emitting element 20 is parallel to the through hole 11 of the substrate 10, and the back surface 12 of the substrate 10 It is vertical.

The terminal 23 is, for example, an annular plate-shaped member made of metal, is installed on the upper surface of the light emitting element body 21, and is electrically connected to the PAD 15 provided on the substrate 10. Connect to . The terminal 23 functions as a terminal for inputting an electric signal to the light emitting element 20. In addition, for example, with the PAD 15 installed on the back surface 12 of the substrate 10 and the terminal 23 electrically connected, the terminal 23 and the PAD 15 are bonded using a conductive adhesive. do. By this, the substrate 10 and the light emitting element 20 are physically fixed.

In addition, the method of electrical connection between the PAD 15 and the terminal 23 is not particularly limited, and may be performed using a wire or the like. Generally, a light-emitting element has a terminal installed on its lower surface (a surface opposite to the light-emitting part), and the electrical connection between this terminal and the board is made by connecting a wire to the terminal. A light-emitting device having terminals on the bottom may be applied to the optical coupling structure 100 of this embodiment, but it is necessary to extend a wire from the terminal on the bottom of the light-emitting device to the PAD on the back of the substrate for connection. Furthermore, it is necessary to physically fix the top surface of the light emitting device and the back 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 light emitting element 20 and the substrate 10 are physically fixed, and the terminal 23 and the PAD are connected. Electrical connection to (15) can be performed in one process, and the wire installation process can be omitted, thereby reducing manufacturing costs. In addition, this connection method can improve connection reliability because wire deterioration or disconnection does not occur, and can be suitably used in the present embodiment.

The optical fiber 30 has an open end 31 installed in relation to the light emitting element 20 through the through hole 11 of the substrate 10. Additionally, in the optical fiber 30, light L emitted from the light-emitting element 20 enters from the opening end 31 on the light-emitting element 20 side and is transmitted through the inside of the optical fiber 30.

The optical fiber 30 is easier to handle than an optical fiber made only of glass, is more cost-effective, does not require soldering between the substrate 10 and the ferrule 40 as described later, and is not affected by heat. Since there is no such thing, an optical fiber containing plastic can be used suitably. Additionally, 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 of the optical fiber 30, and includes a bottomed ferrule body 41 having a bottom having a bottom 41a, and a ferrule. It is installed through the main body 41 and has an optical fiber holding portion 42 that holds the optical fiber 30. Additionally, in the optical coupling structure 100, the bottom surface 41a on the tip side of the ferrule 40 is in contact with the surface 13 (second surface) of the substrate 10.

The alignment jig 50 surrounds and holds the ferrule 40, and has a bottom 51a in contact with the surface 13 of the substrate 10, and has a bottom fixed to the surface 13 (for example, For example, it is the absence of a cylindrical shape. In addition, it is a member for aligning the optical axis of the light emitting element 20 and the optical fiber 30, and is a member for inserting a normal aligning jig body 51 with a bottom having a bottom surface 51a and a ferrule 40. It has a ferrule insertion portion (52). In addition, the outer shape of the ferrule 40 and the inner shape of the ferrule insertion portion 52 of the alignment jig 50 are almost the same, and when the ferrule 40 is inserted and mounted on the alignment jig 50, The ferrule 40 and the alignment jig 50 can be integrated without misalignment.

In addition, 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. In addition, when the bottom surface 51a of the alignment jig 50 is in contact with the surface 13 of the substrate 10, the optical axis of the optical fiber 30 is parallel to the through hole 11, and the substrate 10 It is perpendicular to the surface 13.

Next, the light coupling method of this embodiment will be described. The light coupling method of the present embodiment is a method of assembling the above-described light coupling structure 100, and includes a substrate having a parallel back surface 12 and a surface 13 and formed with a through hole 11 penetrating in the thickness direction. On the back surface 12 of (10), a light emitting element 20 having a spherical lens 22 in the light emitting portion 21a is provided, and the spherical lens 22 is directed toward the inside of the through hole 11 of the substrate 10. In the through hole 11, the optical fiber 30 ) A process of contacting the bottom surface 51a of the alignment jig 50 to the surface 13 so that the opening end 31 of the light emitting element 20 faces each other, and the optical axis of the light emitting element 20 and the optical fiber 30 It includes a step of performing active alignment with the optical axis, and a step of fixing the alignment jig 50 to the surface 13 of the substrate 10 after the active alignment. Hereinafter, these processes will be described in detail.

First, the light emitting element 20 is mounted on the back surface 12 of the substrate 10. At this time, the spherical lens 22 of the light emitting element 20 is directed toward the inside of the through hole 11. Furthermore, with the PAD 15 installed on the back surface 12 of the substrate 10 and the terminal 23 electrically connected, the terminal 23 and the PAD 15 are bonded using a conductive adhesive. By this, 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 mounted. The ferrule 40 holding the optical fiber 30 inside is inserted into the careful jig 50, and with the tip positions of the ferrule 40 and the careful jig 50 aligned, the optical fiber 30 and the ferrule ( 40), the jig (50) is integrated into one piece. Furthermore, the bottom surface 51a of the alignment jig 50 holding the ferrule 40 is brought into contact with the surface 13 of the substrate 10. At this time, the optical axis of the light emitting element 20 becomes perpendicular to the back surface 12 of the substrate 10, and the optical axis of the optical fiber 30 becomes perpendicular to the surface 13 of the substrate 10. Additionally, the back surface 12 and the 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 in parallel.

Furthermore, active alignment of the optical axes of the light emitting element 20 and the optical fiber 30 is performed by adjusting the position of the alignment jig 50. At this time, as described above, the optical axis of the light emitting element 20 and the optical axis of the optical fiber 30 are held in parallel. In addition, 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 constant (substrate 10). (with thickness dimensions of) is maintained. Therefore, when performing active alignment of the optical axis, only alignment is performed on a horizontal plane parallel to the substrate 10, and alignment of distance and inclination in the relative direction does not need to be performed.

After alignment of the optical axis is completed, the alignment jig 50 and the board 10 are connected by soldering. Additionally, at this time, soldering heat is not directly applied to the optical fiber 30 and ferrule 40. Additionally, the connection method between the alignment jig 50 and the board 10 is not particularly limited, and connection methods other than soldering may be used. With the above, assembly of the light coupling structure 100 is completed.

In the assembled light 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 of the substrate 10. It passes through the inside of (11) and enters the opening end (31) of the optical fiber (30). Light incident on the optical fiber 30 passes through the interior of the optical fiber 30 and is transmitted. In this way, light transmission is possible using the light coupling structure 100.

The optical coupling structure 100 of the present embodiment is an optical coupling structure that transmits light between a light emitting element 20 having a light emitting portion 21a and an optical fiber 30, and has a parallel back surface 12 and a surface 13. ), a substrate 10 on which a through hole 11 penetrating in the thickness direction is formed, a spherical lens 22 in the light emitting portion 21a, and a spherical lens 22 inside the through hole 11. A light emitting element 20 is mounted on the back surface 12 of the substrate 10 so as to face the light emitting element 20, and on the surface 13 side of the through hole 11, an opening end 31 is installed to face the light emitting element 20. The optical fiber 30, a normal ferrule 40 having a bottom that surrounds and holds the end of the optical fiber 30 and the bottom surface 41a is in contact with the surface 13 of the substrate 10, and the ferrule 40 ) is surrounded and held, and the bottom surface 51a is in contact with the surface 13 of the substrate 10, and is provided with a normal aligning jig 50 with a bottom fixed to the surface 13.

In the light 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 in parallel. In addition, 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 constant (substrate 10). (with thickness dimensions of) is maintained. Therefore, when performing active alignment of the optical axis, only alignment in a horizontal plane parallel to the substrate 10 needs to be performed. From this, the optical coupling structure 100 of the present embodiment can improve alignment workability during assembly and reduce manufacturing costs.

In addition, in the light coupling method of the present embodiment, since the light coupling structure 100 is used, when performing active alignment of the optical axis, only alignment in a horizontal plane parallel to the substrate 10 needs to be performed, and the alignment work only needs to be performed. Performance can be improved and manufacturing costs can be reduced.

［Camera module］

Next, the camera module 200 of this embodiment will be described. As shown in FIG. 2, the camera module 200 is a system unit 230 having a case 210, an imaging module 220, and a board 231 on which the system IC, etc. are mounted. and an optical communication module 240. The imaging module 220, the system unit 230, and the optical communication module 240 are installed inside the case 210.

The imaging module 220 is a substrate on which a lens unit 221 installed in the opening 211 of the case 210 and an imaging device such as a CCD sensor are installed, and which photoelectrically converts the light received through the lens unit 221. It has (222). The optical communication module 240 is a member that transmits an image signal to an external device through optical communication, and is a connector that connects the optical coupling structure 100 described above and the optical coupling structure 100 and an external device. )(241).

Since the camera module 200 of the present embodiment includes the light coupling structure 100, the alignment workability can be improved and the manufacturing cost can be suppressed when assembling the light coupling structure 100.

In addition, the present invention is not limited to the above-described embodiments, and includes other configurations that can achieve the purpose of the present invention, and modifications such as those shown below are also included in the present invention. In the following modifications, the same components as those in the above-described embodiment are given the same reference numerals, and descriptions are omitted.

In the above-described embodiment, a spherical lens was used as the optical system, but an aspherical lens may be used instead of the spherical lens to condense the light of the light emitting element. In addition, it is sufficient to suppress diffusion and loss of light from the light emitting element, and as in the light coupling structure 100A shown in FIG. 3, instead of a converging lens, the light LA from the light emitting element 20A is parallel You may also use a collimator lens 22A that produces light. However, since spherical lenses such as ball lenses are cheaper than aspherical lenses or collimator lenses, spherical lenses are more suitably used in the light coupling structure of the present invention in order to suppress manufacturing costs.

Additionally, in the light coupling structure, a recess may be provided in the substrate. FIG. 4 is a cross-sectional view schematically showing the light coupling structure 100B in which the recess 14 is formed in the substrate 10B. In the substrate 10B, a depression 14 is formed by notching in the thickness direction from the surface 13 of the substrate 10B, and a ferrule 40 is fitted into the depression 14. It is done. The inner shape of the recessed portion 14 is formed to be 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.

Additionally, the bottom surface 14a of the recess 14 is parallel to the surface 13 of the substrate 10. In the light coupling structure 100B, the ferrule 40 is held in the alignment jig 50 with the bottom surface 41a of the ferrule 40 protruding from the bottom surface 51a of the alignment jig 50. Using the careful jig 50 holding the ferrule 40, the bottom surface 41a of the tip of the ferrule 40 is brought into contact with the bottom surface 14a of the depression 14, and the tip of the careful jig 50 is brought into contact with the bottom surface 14a of the depression 14. The bottom surface 51a is brought into contact with the surface 13 of the substrate 10 and fixed. As a result, like the light coupling structure 100, the optical axis of the optical fiber 30 becomes parallel to the through hole 11 and is perpendicular to the bottom surface 14a of the recess 14.

By forming the recess 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 is more concentrated and the light is incident on the optical fiber 30B. You can do it. Therefore, compared to the optical fiber 30 used in the optical coupling structure 100 that does not form the recess 14, it can correspond to the optical fiber 30B with a thin core wire. Additionally, by adjusting the depth of the recess 14, the distance between the light emitting element 20 and the optical fiber 30B can be set to a desired size.

Additionally, the present invention can also be applied to a light coupling structure that includes a light receiving element as a photoelectric element. The light 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 body 61, a light receiving portion 61a, a spherical lens 22, and a terminal 63. In the light coupling structure 100C, light enters the optical fiber 30 from an open end opposite to the open end 31, passes through the inside of the optical fiber 30, and is transmitted to the open end 31. Furthermore, light LC passes through the inside of the through hole 11 of the substrate 10 from the open end 31 of the optical fiber 30 and reaches the spherical lens 22. Light LC is condensed by the spherical lens 22 and received by the light receiving portion 61a.

In the light coupling structure 100C, similar to the light coupling structure 100 of the above-described embodiment, the distance and inclination in the relative direction between the light receiving element 60 and the optical fiber 30 are determined by the surface of the substrate 10 ( 13) and the back surface 12 can be made almost constant, so there is no need to adjust the distance and inclination in the relative direction. From this, the optical coupling structure 100C can improve alignment workability during assembly and reduce manufacturing costs.

In addition, the best configuration, method, etc. for carrying out the present invention are disclosed in the above description, but the present invention is not limited thereto. In other words, the present invention has been especially shown and described mainly with respect to specific embodiments, but without departing from the scope of the technical idea and purpose of the present invention, the shapes, materials, In terms of quantity and other detailed configuration, a person skilled in the art can add various modifications.

Accordingly, the description limiting the shape, material, etc. disclosed above is provided as an example to facilitate understanding of the present invention, and does not limit the present invention, so the limitations on the shape, material, etc. are part of the description. , or descriptions of the names of members excluding all limitations are included in the present invention.

100, 100A, 100B, 100C: Optical coupling structure
200: Camera module
10: substrate
11: Through hole
12: Back side (side 1)
13: Surface (second side)
14: Notch
14a: Bottom of recess 14
15:PAD
20: Light-emitting element (photoelectric element)
21a: light emitting unit
22: Spherical lens (optical system)
22A: Collimator lens (optics)
23, 63: terminal
30, 30B: optical fiber
40: Ferrule
41a: bottom
50: Careful jig
51a: bottom
60: Light receiving element (photoelectric element)
61a: light receiving unit

Claims (7)

In the optical coupling structure for transmitting light between an optoelectronic element having a light emitting unit or a light receiving unit and an optical fiber,
A substrate having a first surface and a second surface extending parallel to the first surface, and having a through hole extending in the thickness direction;
The photoelectric element has an optical system in the light emitting unit or the light receiving unit, and is mounted on the first surface of the substrate so that the optical system is directed to the inside of the through hole;
The optical fiber, on the side of the through hole facing the second surface, has an open end facing the photoelectric element;
a regular ferrule with a bottom that surrounds and holds the end of the optical fiber;
In addition to surrounding and holding the ferrule, a regular jig with a bottom is provided, the bottom of which is in contact with the second surface of the substrate and fixed to the second surface,
On the second surface of the substrate, a recess is formed by notching in the thickness direction of the substrate and having an inner shape larger than the outer shape of the ferrule, and the bottom surface of the recess is formed. Parallel to the second side,
The ferrule is in contact with the bottom of the recess and is fitted,
Light-coupled structure. According to paragraph 1,
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,
An optical coupling structure in which the optical axis of the photoelectric element and the optical axis of the optical fiber are held in parallel. According to claim 1 or 2,
An optical coupling structure wherein the optical fiber is an optical fiber containing plastic. According to claim 1 or 2,
An optical coupling structure in which the terminal of the photoelectric element is provided on a side of the photoelectric element facing the optical system. A substrate having a first surface and a second surface extending parallel to the first surface, and having a through hole extending in the thickness direction;
A photoelectric element having an optical system in a light emitting unit or a light receiving unit,
optical fiber,
a regular ferrule with a bottom surrounding and holding an end of the optical fiber;
Equipped with a regular jig with a bottom that surrounds and retains the ferrule,
A recess is formed on the second surface of the substrate by notching in the thickness direction of the substrate and having an inner shape larger than the outer shape of the ferrule, and the bottom of the recess is formed on the second surface. In the optical coupling method for transmitting light between the photoelectric element and the optical fiber using an optical coupling structure parallel to the
A step of mounting the photoelectric element on the first surface of the substrate with the optical system facing into the through hole of the substrate;
The bottom of the careful 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 ferrule is placed on the bottom of the recessed portion. The process of touching,
A process of performing active alignment between the optical axis of the photoelectric element and the optical axis of the optical fiber;
After active alignment, comprising fixing the alignment jig to the second side of the substrate,
Optical coupling method. A camera module comprising the light coupling structure according to claim 1 or 2. delete