JP2015068835A - Optical transmission module and endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission module 1 with high productivity.SOLUTION: The optical transmission module 1 comprises: an optical element 10 in which a light-emitting part 11 for outputting an optical signal is located at a first prescribed position from a side face thereof; an optical fiber 50 for transmitting the optical signal; a holding member 40 in which a first through hole 40H, through which the optical fiber 50 is inserted, is located at a second prescribed position from a side face thereof; and a wiring substrate 20, having a first recess 20X, a second recess 20Y, and a through hole 20H, in which the holding member 40 is joined in a state of being fitted into the first recess 20X and the optical element 10 is joined in a state of being fitted into the second recess 20Y and in which the first through hole 40H of the holding member 40 is disposed right above the light-emitting part 11 of the optical element 10.

Description

  The present invention relates to an optical transmission module including an optical element, an optical fiber, and a holding member into which the optical fiber is inserted, and an endoscope having the optical transmission module.

  The endoscope has an imaging unit including an imaging element such as a CCD at the distal end of an elongated insertion unit. In recent years, use of an imaging device having a high pixel number for an endoscope has been studied. When an image sensor with a large number of pixels is used, the amount of signal transmitted from the image sensor to the signal processing device increases. Therefore, instead of electrical signal transmission via metal wiring using electrical signals, the optical signal is transmitted via an optical fiber. Optical signal transmission is preferred. For optical signal transmission, an E / O module (electric-optical converter) that converts an electric signal into an optical signal and an O / E module (optical-electric converter) that converts an optical signal into an electric signal are used. .

  For example, Japanese Patent Laid-Open No. 2013-025092 discloses an optical element that inputs or outputs an optical signal, a substrate on which the optical element is mounted, and an optical fiber insertion that transmits an optical signal that is input and output from the optical element. An optical transmission module is disclosed that includes a holding portion that has a through hole and is mounted and arranged side by side in the thickness direction of the optical element.

  The optical transmission module needs to accurately align the relative position between the optical element and the holding member (ferrule) into which the optical fiber is inserted. That is, if the center position of the light emitting part of the optical element is shifted from the center position of the through hole of the holding part, the amount of light incident on the optical fiber is reduced and the signal is attenuated.

  Here, in order to reduce the burden on the subject and secure the observation field of view, it is preferable to make the outer diameter and length of the distal end portion of the insertion portion of the endoscope as small as possible. For this reason, an optical transmission module for an endoscope is required to have a very small size compared to an optical transmission module for general communication. Therefore, when trying to improve productivity while further reducing the size and diameter of an optical transmission module for an endoscope, it is particularly important to align the optical element and the optical fiber with higher accuracy. It becomes a problem.

JP 2013-025092 A

  An embodiment of the present invention aims to provide a highly productive light transmission module and an endoscope having the light transmission module.

  In the optical transmission module according to the embodiment of the present invention, an optical fiber that transmits an optical signal, and a first through hole having the same inner diameter as the outer diameter of the optical fiber into which the optical fiber is inserted are first predetermined from the side. The holding member in the position, the light receiving unit to which the optical signal is input or the light emitting unit to output the optical signal are the optical element in the second predetermined position from the side, the first positioning unit, and the second positioning unit And the second through hole, and the side surface of the holding member is joined in a state of contacting the first positioning portion, and the side surface of the optical element is joined in the state of contacting the second positioning portion. And a substrate on which the first through hole of the holding member is disposed immediately above the light emitting portion of the optical element.

  In an endoscope according to another embodiment, an optical fiber that transmits an optical signal, and a first through-hole having the same inner diameter as the outer diameter of the optical fiber into which the optical fiber is inserted are first predetermined from the side. The holding member in the position, the light receiving unit to which the optical signal is input or the light emitting unit to output the optical signal are the optical element in the second predetermined position from the side, the first positioning unit, and the second positioning unit And the second through hole, and the side surface of the holding member is joined in a state of contacting the first positioning portion, and the side surface of the optical element is joined in the state of contacting the second positioning portion. And a substrate on which the first through hole of the holding member is disposed immediately above the light emitting portion of the optical element, and has a light transmission module at the distal end portion of the insertion portion.

  According to the embodiment of the present invention, a highly productive light transmission module and an endoscope having the light transmission module can be provided.

It is a perspective view of the optical transmission module of a 1st embodiment. It is an exploded view of the optical transmission module of 1st Embodiment. It is sectional drawing of the optical transmission module of 1st Embodiment. It is a top view of the optical transmission module of a 1st embodiment. It is an exploded sectional view of the optical transmission module of a 1st embodiment. It is an exploded view of the modification 1 of the optical transmission module of the modification 1 of 1st Embodiment. It is an exploded view of the modification 2 of the optical transmission module of the modification 1 of 1st Embodiment. It is an exploded sectional view of the optical transmission module of a 2nd embodiment. It is an exploded sectional view of the optical transmission module of modification 1 of a 2nd embodiment. It is an exploded view of the optical transmission module of the modification 2 of 2nd Embodiment. It is an exploded sectional view of the optical transmission module of modification 3 of a 2nd embodiment. It is a perspective view of the endoscope of a 3rd embodiment.

<First Embodiment>
The optical transmission module 1 according to the first embodiment will be described with reference to FIGS. The optical transmission module of this embodiment is an E / O module that converts an electrical signal into an optical signal. In FIG. 5 and subsequent figures, the optical fiber 50 is not shown.

  The optical transmission module 1 includes an optical element 10, a wiring board 20, a holding member 40, and an optical fiber 50. In the optical transmission module 1, the optical element 10, the wiring board 20 that is a substrate, and the holding member 40 are arranged side by side in the thickness direction of the optical element 10.

  The optical element 10 is a surface emitting laser (vertical cavity surface emitting laser; VCSEL) chip having a light emitting unit 11 that outputs light of an optical signal. The optical fiber 50 transmits the output optical signal. The holding member 40 disposed on the upper side of the optical element 10 has the optical fiber 50 inserted into a first through hole 40H (hereinafter also referred to as “through hole 40H”) having an inner diameter substantially the same as the outer diameter of the optical fiber 50. ing. Here, “substantially the same” means that the outer diameter of the optical fiber 50 and the wall surface of the first through-hole 40H formed in the holding member 40 are substantially in the same diameter. ”Means shape / size.

  For example, the ultra-small optical element 10 having a planar view size of 250 μm × 300 μm includes a light emitting unit 11 having a diameter of 20 μm and an external connection electrode 12 that supplies a drive signal to the light emitting unit 11. A reflective film may be disposed on the main surface of the optical element 10 that faces the light emitting portion forming surface.

  The optical element 10 is flip-chip mounted on the wiring board 20. That is, the wiring board 20 is a substrate having a wiring (not shown) including the connection electrode 21 connected to the external connection electrode 12 of the optical element 10. As the substrate of the wiring board 20, an FPC substrate, a ceramic substrate, a glass epoxy substrate, a glass substrate, a Si substrate, or the like is used. For example, the Au bump of the optical element 10 is ultrasonically bonded to the external connection electrode 12 of the wiring board 20. Although not shown, a resin such as an underfill material or a sidefill material may be injected into the joint portion. After the solder paste or the like is printed on the wiring board 20 and the optical element 10 is disposed, the solder may be melted and mounted by reflow or the like. The wiring board 20 may include a processing circuit for converting an electrical signal from the imaging unit into a drive signal for the optical element 10.

  The wiring board 20 has a recess 20X as a first positioning portion formed in the first main surface 20SA, and a recess 20Y as a second positioning portion formed in the second main surface 20SB. A second through-hole 20H (hereinafter also referred to as “through-hole 20H}) penetrating the first main surface 20SA and the second main surface 20SB is formed.The through-hole 20H of the wiring board 20 is an optical path. It becomes.

  The substantially rectangular parallelepiped holding member 40 is formed with a cylindrical through hole 40H having substantially the same outer diameter as the optical fiber 50 to be inserted. The inner diameter of the through hole 40H is particularly preferably slightly larger than the outer diameter of the optical fiber 50 from the viewpoint of positioning accuracy. That is, by inserting the optical fiber 50 through the through hole 40H of the holding member 40, the central axis of the optical fiber 50 can be made coincident with the central axis of the through hole 40H.

  The through-hole 40H may have a prismatic shape as long as the optical fiber 50 can be held on its inner surface in addition to the cylindrical shape. The material of the holding member 40 is a metal member such as ceramic, Si, glass, or SUS. In addition, the holding member 40 may not be a substantially rectangular parallelepiped, but may be a substantially columnar shape or a substantially conical shape.

  The first main surface 20SA of the wiring board 20 has a rectangular recess 20X, and the second main surface 20SB has a rectangular recess 20Y. The inner dimension (XY in-plane dimension) of the recess 20X is substantially the same as the outer dimension (XY in-plane dimension) of the holding member 40, and the inner dimension (XY in-plane dimension) of the recess 20Y is the outer dimension of the optical element 10. It is substantially the same as (XY in-plane dimension).

  And it joins in the state which the holding member 40 fitted to the recessed part 20X, and is joined in the state which the optical element 10 fitted to the recessed part 20Y. In other words, the outer peripheral side surface (outer peripheral surface) of the holding member 40 is in contact with the wall surface of the concave portion 20X that is the first positioning portion, and the outer peripheral side surface of the optical element 10 is that of the concave portion 20Y that is the second positioning portion. It is in contact with the wall. In addition, although an adhesive is used for joining, description is abbreviate | omitted.

  The light emitting portion 11 of the optical element 10 is located at a predetermined position (first predetermined position) from the outer peripheral surface in the XY plane. The through hole 40H of the holding member 40 is at a predetermined position (second predetermined position) from the outer peripheral surface in the XY plane.

  For this reason, the optical element 10 and the holding member 40 that are both fitted to the wiring board 20 are in a predetermined positional relationship. Specifically, the first predetermined position, the second predetermined position, the (wall surface) position of the recess 20X, and the recess so that the through hole 40H of the holding member 40 is disposed on the light emitting unit 11 of the optical element 10. The 20Y (wall surface) position is set. For this reason, when the holding member 40 is fitted into the recess 20X and the optical element 10 is fitted into the recess 20Y, the center of the optical fiber 50 is disposed at the center position of the through hole 40H.

  That is, the first predetermined position and the second predetermined position are the center of the light emitting unit 11 and the center of the through hole 40H of the holding member 40 in a state where the optical element 10 and the holding member 40 are fitted to the wiring board 20. Are arranged so as to be coaxial with the center of the through hole 20H of the wiring board 20.

  The optical transmission module 1 is highly productive because the optical element 10 and the optical fiber 50 are aligned by being fitted to the wiring board 20 at the time of manufacture.

  The positional accuracy of the first positioning part (recess 20X), the second positioning part (recess 20Y), the through hole 20H of the wiring board 20, the light emitting part 11 and the through hole 40H of the holding member 40 is, for example, ± 5 μm. Is preferably within.

That is, when the diameter of the through hole 20H of the wiring board 20 is substantially the same as the diameter of the optical fiber 50, the through hole 20H is at a predetermined position (third predetermined position) with respect to the recesses 20X and 20Y. When the diameter of the through hole 20H is sufficiently larger than the diameter of the optical fiber 50, for example, when it is twice or more larger, the positional accuracy of the through hole 20H differs from the positional accuracy of the positioning portion and is strictly controlled. There is no need to do.

<Modification>
Next, optical transmission modules 1A and 1B according to modifications of the first embodiment will be described. Since the optical transmission modules 1A and 1B are similar to the optical transmission module 1, components having the same functions are denoted by the same reference numerals and description thereof is omitted.

In the optical transmission modules 1A and 1B of the modified example, like the optical transmission module 1, the wiring board 20D has the first positioning portion on the first main surface 20SA, and the second positioning on the second main surface 20SB. Part.
The optical transmission modules 1 </ b> A and 1 </ b> B have the same effects as the optical transmission module 1.

  In the optical transmission module 1A of Modification 1 shown in FIG. 6, the holding member 40A is a first positioning portion of the wiring board 20A in which the upper surface has a substantially conical shape with a flat surface and the bottom of the holding member 40A is fitted. The recess 20XA is circular.

  That is, the shape of the fitting portion in plan view is not limited to a rectangle, but may be a circle like the optical transmission module 1A, or may be a polygon or an ellipse.

  Next, in the optical transmission module 1B of Modification 2 shown in FIG. 7, there are two convex portions 22B1 and 22B2 that are first positioning portions on the first main surface 20SA of the wiring board 20B.

  The holding member 40B can be disposed at a predetermined position with respect to the wiring board 20B by bringing the side surface of the wiring board 20B into contact with the side surfaces of the convex portions 22B1 and 22B2. That is, if the positioning portion has a convex portion 22B1 having a side surface that makes the X coordinate value unambiguous and a convex portion 22B2 having a side surface that makes the Y coordinate value unambiguous for positioning in the XY plane. Good.

  In the description of the first and second modifications, the positioning between the holding member and the wiring board has been described, but the same applies to the positioning between the optical element and the wiring board. Further, the two positioning portions may be different from each other. For example, the holding member may be fitted into the concave portion of the wiring board, and the two side surfaces of the optical element 10 may be in contact with the respective convex portions of the wiring board.

  When the external connection electrode 12 of the optical element 10 is disposed on the main surface facing the light emitting portion formation surface, the external connection electrode 12 is connected to the connection electrode 21 of the wiring board 20 by, for example, a bonding wire. Connected. That is, various methods can be used as the electrical connection method between the optical element 10 and the wiring board 20 according to the specifications of the optical element 10.

Second Embodiment
Since the optical transmission module 1C of the second embodiment is similar to the optical transmission module 1 and the like, components having the same function are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 8, in the optical transmission module 1C, the wiring board 20C has a recess 20XC that is the first positioning portion and a recess 20YC that is the second positioning portion on the first main surface 20SA.

  And the lower part of 40 C of holding members is fitting with the recessed part 20XC, and the optical element 10 is fitting with the recessed part 20YC.

  The optical transmission module 1C has the effect of the optical transmission module 1 and the like, and further has a short length (height).

  The optical transmission module 1C can be made shorter by increasing the depth of the recess 20YC.

<Modification>
Next, optical transmission modules 1D to 1F according to modifications of the second embodiment will be described. Since the optical transmission modules 1D to 1F are similar to the optical transmission module 1C, components having the same functions are denoted by the same reference numerals and description thereof is omitted.

  In the optical transmission modules 1D to 1F, similarly to the optical transmission module 1C, the wiring board 20D has a first positioning portion and a second positioning portion on the first main surface 20SB. And the optical transmission modules 1D-1F have the effect of the optical transmission module 1C.

  In the optical transmission module 1D of Modification 1 shown in FIG. 9, the wiring board 20D has a convex portion 22D as a first positioning portion and a concave portion 20YD as a second positioning portion on the first main surface 20SBA.

  The external connection electrode 12 of the optical element 10D and the connection electrode 21 of the wiring board 20D are connected by a bonding wire 19. In the optical transmission module 1D, the length (height) of the holding member itself can be further shortened by providing the concave portion in the portion facing the external connection electrode 12 of the holding member 40D.

  Next, in the optical transmission module 1E of Modification 2 shown in FIG. 10, the wiring board 20E has a convex portion 22E that is a first positioning portion and a concave portion 20YE that is a second positioning portion on the first main surface 20SA. . In FIG. 10, the external connection electrode 12 of the optical element 10 is not shown.

  The convex portions 22E having two orthogonal side surfaces are integrated with the two side surfaces of the wiring board 20E.

  Two orthogonal side surfaces of the holding member 40D are in contact with two orthogonal inner surfaces of the convex portion 22E. The optical element 10 is fitted in the recess 20YD.

  In the optical transmission module 1F of Modification 3 shown in FIG. 11, the wiring board 20F has a convex portion 22F having a function of the first positioning portion and a function of the second positioning portion on the first main surface 20SA. In FIG. 11, the external connection electrode 12 of the optical element 10 is not shown.

  That is, the convex portion 22 </ b> F is a first positioning portion whose outer peripheral side surface is in contact with the inner side surface of the holding member 40 </ b> F, and its inner peripheral side surface is a second positioning portion that is in contact with the side surface of the optical element 10.

  As described above, the positioning portion may be a concave portion or a convex portion, or may be formed on any main surface as long as it can uniquely define the position in the X direction and the position in the Y direction. Further, it may be a single member that can uniquely define the XY2 direction. Further, the positioning portion may be a part of the wiring board or may be a separate member disposed on the wiring board.

  In the optical transmission module of the embodiment described above, an E / O module including a surface emitting laser chip is used as an optical element. However, even if an O / E module having, for example, a photodiode (PD) chip in which a light receiving portion for inputting an optical signal is formed is used as an optical element, the same effect is obtained.

  That is, an optical fiber that transmits an optical signal, a holding member in which the optical fiber is inserted, a first through hole having the same inner diameter as the outer diameter of the optical fiber, at a first predetermined position from a side surface, and the optical signal Has a light receiving portion at a second predetermined position from the side surface, a first positioning portion, a second positioning portion, and a second through hole, and the side surface of the holding member is the first side. The optical element is joined in contact with the positioning part, and the side surface of the optical element is joined in contact with the second positioning part, and the first of the holding member is directly above the light emitting part of the optical element. The O / E module including the substrate on which the through holes are arranged has high productivity.

<Third Embodiment>
Next, the endoscope 60 according to the third embodiment will be described. Since the light transmission modules 61A and 61B of the endoscope 60 are the same as the light transmission module 1 and the like of the embodiment of the present invention already described, description thereof is omitted.

  As shown in FIG. 10, the endoscope 60 is provided with an imaging unit 62 having an imaging element with a high pixel count disposed at the distal end portion 2, and a proximal end side of the insertion unit 65. An operation unit 66 and a universal cord 67 extending from the operation unit 66 are provided.

  The electrical signal output from the imaging unit 62 is converted into an optical signal by an E / O module 61A whose optical element is a surface emitting laser chip, and the optical element disposed in the operation unit 66 via the optical fiber 63 is a PD element. It is converted into an electric signal again by the O / E module 61B, which is a chip, and transmitted through the metal wiring 64. That is, a signal is transmitted through the optical fiber 65 in the small-diameter insertion portion 65.

  The E / O module 61A is ultra-compact because it has the same configuration as the optical transmission modules 1 to 1D and the like, but has high productivity. For this reason, the endoscope 60 has a thin tip end portion and insertion portion, but has high productivity.

  The O / E module 61B has a relatively large arrangement space, but preferably has the same configuration as the E / O module 61A, that is, the optical transmission modules 1 to 1D of the present invention.

  The present invention is not limited to the above-described embodiments and the like, and various modifications, combinations, and applications are possible without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1, 1A-1F ... Optical transmission module 10 ... Optical element 10D ... Optical element 11 ... Light emission part 20 ... Wiring board 20H ... 2nd through-hole 20X, 20Y ... Concave part 40 ... Holding member 40H ... 1st through-hole 50 ... Optical fiber 60 ... Endoscope

Claims (9)

An optical fiber for transmitting an optical signal;
A holding member in which the first through hole having the same inner diameter as the outer diameter of the optical fiber is inserted into the first optical fiber from the side surface at a first predetermined position.
A light receiving portion to which the optical signal is input or a light emitting portion to output the optical signal is an optical element at a second predetermined position from a side surface;
A first positioning portion; a second positioning portion; and a second through-hole, wherein the side surface of the holding member is joined in contact with the first positioning portion, and the side surface of the optical element is And a substrate that is bonded in contact with the second positioning portion and on which the first through hole of the holding member is disposed immediately above the light receiving portion or the light emitting portion. Optical transmission module.   The optical transmission module according to claim 1, wherein the substrate is a wiring board having a wiring electrically connected to an external connection electrode of the optical element.   The optical transmission module according to claim 2, wherein the substrate includes the first positioning portion on a first main surface and the second positioning portion on a second main surface.   The optical transmission module according to claim 2, wherein the substrate has the first positioning portion and the second positioning portion on a first main surface.   5. The optical transmission module according to claim 3, wherein the first positioning portion and the second positioning portion are a concave portion or a convex portion of the substrate, respectively.   The holding member is fitted with a first recess that is the first positioning portion of the substrate, and the optical element is fitted with a second recess that is the second positioning portion of the substrate. The optical transmission module according to claim 5.   The optical transmission module according to claim 1, wherein the optical element is a surface emitting laser element having the light emitting unit.   The optical transmission module according to claim 1, wherein the optical element is a photodiode element having the light emitting unit.   An endoscope comprising the optical transmission module according to any one of claims 1 to 8 at a distal end portion of an insertion portion.

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