Ferrule

Abstract

Reduce the bend of the optical fiber insertion hole and arrange the position of the opening of the optical fiber insertion hole with higher precision. 【Solution means】An adhesive injection hole for injecting an adhesive for fixing an optical fiber, which opens in a first surface, which is a predetermined surface, among the surfaces adjacent to the connection end surface, which is the surface where the optical fiber insertion hole and the guide pin hole are open; a first recess provided at a position facing the adhesive injection hole on a second surface, which is a surface facing the first surface, among the surfaces adjacent to the connection end surface; and a second recess provided in a portion of the first surface where the optical fiber insertion hole is formed inside the first surface are formed. The first recess does not communicate with the optical fiber insertion hole, the guide pin hole, and the adhesive injection hole, and the second recess does not communicate with the optical fiber insertion hole, the guide pin hole, the adhesive injection hole, and the first recess.

Description

Technical Field

[0001] The present invention relates to a ferrule, and more particularly to a ferrule of an optical fiber connector for connecting a plurality of optical fibers.

Background Art

[0002] An optical fiber connector is used as a component for connecting and disconnecting optical fibers from each other or between an optical fiber and an optical fiber component. A ferrule is a member that aligns by a sleeve or a guide pin and holds and fixes an optical fiber.

[0003] Also, it has been proposed to form a recess on the outer surface on the side opposite to the side where the adhesive injection window of the ferrule for an optical connector is formed (see, for example, Patent Document 1). Further, in order to eliminate the warp in the left - right direction of the ferrule for an optical connector, eliminate the deviation in the position of the optical fiber insertion hole with respect to the center of the guide pin hole, and enable a low - loss connection, it has also been proposed to provide a recess on the lower surface of the ferrule body that is approximately the same size as the window (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when attempting to form the ferrule of an optical fiber connector by injection molding or transfer molding, the optical fiber insertion hole for passing the optical fiber will be bent. When polishing the surface where the optical fiber insertion hole is open, the position of the opening of the optical fiber insertion hole will shift. As a result, when the ferrules are fitted together, the optical axis of the optical fiber will shift, leading to a large connection loss.

[0006] The present invention has been made in view of such a situation, and aims to make the bending of the optical fiber insertion hole smaller and enable the position of the opening of the optical fiber insertion hole to be arranged with higher accuracy.

Means for Solving the Problems

[0007] The ferrule according to one aspect of the present invention is a ferrule of an optical fiber connector for connecting a plurality of optical fibers, and is a ferrule formed from resin. It has optical fiber insertion holes for passing each of a plurality of optical fibers arranged in parallel with each other, two guide pin holes arranged in parallel with the optical fiber insertion holes and sandwiching the optical fiber insertion holes, an adhesive injection hole for injecting an adhesive for fixing the optical fiber, which opens on a first surface that is a predetermined surface among the surfaces adjacent to the connection end surface where the optical fiber insertion holes and the guide pin holes open, a first recess provided at a position facing the adhesive injection hole on a second surface that is a surface facing the first surface among the surfaces adjacent to the connection end surface, and a second recess formed in a portion of the first surface where the optical fiber insertion hole is formed inside the first surface. The first recess is composed of a first concave portion having a predetermined depth from the second surface, and a second concave portion having a greater depth from the second surface compared to the depth of the first concave portion and disposed on the connection end face side. The first recess does not communicate with the optical fiber insertion hole, the guide pin hole, and the adhesive injection hole, and the second recess does not communicate with the optical fiber insertion hole, the guide pin hole, the adhesive injection hole, and the first recess.

[0008] The second recess can extend to a portion of the first surface where each of the two guide pin holes is formed inside the first surface.

[0009] The second recess can be formed symmetrically with respect to a second virtual plane that is orthogonal to a first virtual plane including, in a plane, a plurality of center lines of optical fiber insertion holes arranged parallel to each other and that intersects a central portion of the connection end face.

[0010] The first recess can be blocked from the adhesive injection hole by a thin-walled portion having a thickness thinner than that of other portions.

[0012] The bottom-side corners of the first recess can be formed in a curved surface shape.

Advantages of the Invention

[0013] As described above, according to the present invention, the bend of the optical fiber insertion hole can be made smaller, and the position of the opening of the optical fiber insertion hole can be arranged with higher accuracy.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0015] Hereinafter, with reference to FIGS. 1 to 11, the ferrule of the embodiment of the present invention will be described.

[0016] First, the configuration of the ferrule 11 of an embodiment of the present invention will be described. FIGS. 1 and 2 are perspective views for explaining the outline of the configuration of the ferrule 11 of the embodiment of the present invention. FIG. 3 is a six-view drawing showing the configuration of the ferrule 11. FIG. 4 is an end face view of a cut portion on the AA' line shown in FIG. 3(A) showing the configuration of the ferrule 11. FIG. 5 is an end face view of a cut portion on the BB' line, CC' line, DD' line, or EE' line shown in FIG. 3(F) showing the configuration of the ferrule 11. FIG. 5(A) is an end face view of a cut portion on the BB' line shown in FIG. 3(F). FIG. 5(B) is an end face view of a cut portion on the CC' line shown in FIG. 3(F). FIG. 5(C) is an end face view of a cut portion on the DD' line shown in FIG. 3(F). FIG. 5(D) is an end face view of a cut portion on the EE' line shown in FIG. 3(F).

[0017] In the following description, when the device is fitted, the connection end face, which is the face in contact with another device when fitted, is defined as the front side, and the front-back direction is illustrated by the Y-axis, the left-right direction is illustrated by the X-axis, and the up-down direction is illustrated by the Z-axis. Further, in the following, in the Y-axis direction, the lower right side in FIG. 1 is simply referred to as the front side, and in the Y-axis direction, the upper left side in FIG. 1 is simply referred to as the rear side (the back side). Furthermore, in the following, in the X-axis direction, the lower left side in FIG. 1 is simply referred to as the left side, and in the X-axis direction, the upper right side in FIG. 1 is simply referred to as the right side. Additionally, in the following, in the Z-axis direction, the upper side in FIG. 1 is simply referred to as the upper side, and in the Z-axis direction, the lower side in FIG. 1 is simply referred to as the lower side. Note that the rear side (the back side) is the positive direction of the Y-axis, the right side is the positive direction of the X-axis, and the upper side is the positive direction of the Z-axis. Also, the Z-axis direction is simply referred to as the up-down direction, the X-axis direction is simply referred to as the left-right direction, and the Y-axis direction is simply referred to as the front-back direction. Furthermore, the direction along the plane parallel to the X-axis and the Y-axis is also simply referred to as the horizontal direction. Additionally, the direction that forms a relatively small angle with the horizontal direction and the horizontal direction are also referred to as the lateral direction, and the direction that forms a relatively small angle with the up-down direction and the up-down direction are also referred to as the longitudinal direction. The same applies to the following figures.

[0018] The ferrule 11 is a member that aligns with a sleeve or a guide pin and holds and fixes an optical fiber. For example, the ferrule 11 is an MT (Mechanically Transferable) connector ferrule. Here, the sleeve is a tubular member that aligns two ferrules by its inner diameter. The guide pin is a rod-shaped member that aligns two ferrules by its outer diameter. The ferrule 11 is used in an optical fiber connector such as an MPO (Multi-fiber Push On) connector or an MT connector. The optical fiber connector is a component for connecting and disconnecting optical fibers or between an optical fiber and an optical fiber component. For example, the ferrule 11, together with a housing, constitutes an optical fiber connector plug which is an optical connector attached to an optical fiber. For example, the ferrule 11 is attached to the end of an optical fiber cord. The optical fiber cord is a collection of a plurality of optical fibers protected by a sheath. For example, an optical fiber cord called a tape-shaped optical fiber cord is configured by arranging optical fibers protected by a sheath in a tape shape.

[0019] The ferrule 11 is molded from a resin. For example, the ferrule 11 is manufactured by injection molding a thermoplastic resin such as PPS (Poly Phenylene Sulfide) or PEEK (Poly Ether Ether Ketone). Also, for example, the ferrule 11 is manufactured by transfer molding using a thermosetting resin such as an epoxy resin. That is, the ferrule 11 is a ferrule of an optical fiber connector for connecting a plurality of optical fibers and is a ferrule molded from a resin.

[0020] The ferrule 11 is provided with a connection portion 21 and a boot mounting portion 22. The connection portion 21 holds an optical fiber and contacts another device when being fitted. The boot mounting portion 22 has a shape that protrudes in the vertical and horizontal directions with respect to the connection portion 21, and a boot for preventing buckling (crippling) due to the contact between the optical fiber and the ferrule 11 is mounted thereon.

[0021] The outer shape of the connection part 21 of the ferrule 11 is generally formed in a rectangular parallelepiped shape. The front surface of the connection part 21 of the ferrule 11 is a connection end surface 31 which is the surface in contact with another device when the ferrule 11 is fitted to another device. The upper surface 32, the left side surface 33, the right side surface 34 and the bottom surface 35 are adjacent to the connection end surface 31. The upper surface 32 is a plane with a larger area than each of the left side surface 33 and the right side surface 34. The left side surface 33 is the side surface arranged on the left when the connection end surface 31 is arranged on the front side and the upper surface 32 is arranged on the upper side. The right side surface 34 is the surface facing the left side surface 33. The right side surface 34 is the side surface arranged on the right when the connection end surface 31 is arranged on the front side and the upper surface 32 is arranged on the upper side. The bottom surface 35 is the surface facing the upper surface 32. The bottom surface 35 is a plane with a larger area than each of the left side surface 33 and the right side surface 34.

[0022] A plurality of optical fiber insertion holes 61 and two guide pin holes 62 are formed in the ferrule 11. The optical fiber insertion holes 61 are formed in the connection part 21. Optical fibers are respectively inserted into the optical fiber insertion holes 61. More specifically, the cores of the optical fibers with the sheaths removed and end-processed are respectively inserted into the optical fiber insertion holes 61. The plurality of optical fiber insertion holes 61 are arranged parallel to each other. One end of the optical fiber insertion hole 61 opens to the connection end surface 31. The other end of the optical fiber insertion hole 61 opens to the adhesive injection hole 41. The guide pin holes 62 are for inserting guide pins for positioning when fitting with another device. The two guide pin holes 62 are arranged so as to sandwich the optical fiber insertion holes 61. Also, the two guide pin holes 62 are arranged parallel to the optical fiber insertion holes 61. One end of the guide pin hole 62 opens to the connection end surface 31. The other end of the guide pin hole 62 opens to the rear end surface of the boot mounting part 22.

[0023] Thus, the optical fiber insertion holes 61 are holes for passing each of the plurality of the optical fibers, and are arranged in parallel with each other. The guide pin holes 62 are arranged in parallel with the optical fiber insertion holes 61 and sandwich the optical fiber insertion holes 61 therebetween.

[0024] An optical fiber cord insertion port 45 is formed in the rear end face of the boot mounting portion 22. The end portion of the optically fiber cord that has been end-processed is inserted into the optical fiber cord insertion port 45.

[0025] Further, an adhesive injection hole 41 is formed in the upper surface 32. The adhesive injection hole 41 opens to the upper surface 32. After an optical fiber is inserted into the ferrule 11, an adhesive for fixing the optical fiber is injected into the adhesive injection hole 41. Further, the adhesive injection hole 41 communicates with the plurality of optical fiber insertion holes 61 and the optical fiber cord insertion port 45. An optical fiber groove 63 is formed inside the adhesive injection hole 41. The optical fiber groove 63 is composed of grooves that guide each of the cores of the end-processed optical fibers to the respective optical fiber insertion holes 61. The optical fiber groove 63 is formed on the bottom surface side of the adhesive injection hole 41 at a position where the other end of the optical fiber insertion hole 61 opens. The optical fiber groove 63 is formed in a groove shape that is open at the upper side so as to be able to hold each of the cores of the end-processed optical fibers.

[0026] Thus, the adhesive injection hole 41 is a hole for injecting an adhesive for fixing the optical fiber, which opens to the upper surface 32 adjacent to the connection end surface 31, which is the surface on the side that contacts another device when fitted and is the surface where the optical fiber insertion holes 61 and the guide pin holes 62 open.

[0027] A recess 42 is formed in the bottom surface 35. The recess 42 is formed at a position facing the adhesive injection hole 41. The recess 42 does not communicate with the optical fiber insertion holes 61, the guide pin holes 62, and the adhesive injection hole 41. The recess 42 also does not communicate with the optical fiber cord insertion port 45.

[0028] As shown in FIGS. 4 and 5, the recess 42 is composed of a recessed portion 71 and a recessed portion 72. The recessed portion 72 is formed in a recessed shape with a predetermined depth from the bottom surface 35. The recessed portion 71 communicates with the recessed portion 72, has a greater depth from the bottom surface 35 compared to the depth of the recessed portion 72, and is disposed on the connection end surface 31 side. By doing so, when molding the ferrule 11, the flow rate of the resin can be suppressed, the bend of the optical fiber insertion hole 61 can be made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged with higher accuracy. Since the recessed portion 71 and the recessed portion 72 are provided in the recess 42, sufficient length can be taken for controlling the flow of the resin when molding the ferrule 11, and the flow rate of the resin can be adjusted.

[0029] Also, the bottom-side corner (inner corner portion) of the recess 42 is formed in a curved surface shape. For example, the bottom-side corner of the recess 42 is formed in a spherical crown shape. Since the bottom-side corner of the recess 42 is formed in a curved surface shape, when molding the ferrule 11, turbulence is less likely to occur in the resin flow. Thereby, the position of the opening of the optical fiber insertion hole 61 can be arranged with higher accuracy. If the bottom-side corner of the recess 42 is formed in an angular shape, when molding the ferrule 11, turbulent flow will occur in the resin, residual stress will occur around the optical fiber insertion hole 61, and distortion will occur.

[0030] As shown in FIG. 4, a thin portion 81 is formed between the bottom surface of the adhesive injection hole 41 and the bottom surface of the recess 42. The thickness of the thin portion 81 is formed thinner than the thickness of other portions in the ferrule 11. More specifically, the thin portion 81 is formed between the optical fiber groove 63 formed on the bottom surface of the adhesive injection hole 41 and the bottom surface of the recessed portion 71.

[0031] Since the thin-walled portion 81 is formed, when molding the ferrule 11, the flow rate of the resin can be suppressed, the bending of the optical fiber insertion hole 61 can be made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged more accurately. Further, since the thin-walled portion 81 is formed, the balance of the residual stress applied around the optical fiber insertion hole 61 can be achieved at the position where the other end of the optical fiber insertion hole 61 is open. Therefore, the tensile and pressing forces applied around the optical fiber insertion hole 61 become smaller, the bending of the optical fiber insertion hole 61 can be made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged more accurately.

[0032] By providing the recessed portions 71 and 72 in the recess 42, forming the bottom corner on the bottom side of the recess 42 into a curved surface shape, and forming the thin-walled portion 81, the variation in the position of the opening of the optical fiber insertion hole 61 can be made 0.1 μm or less. As a result, it is possible to manufacture the ferrule 11 suitable for connecting a single-mode optical fiber with good yield, which has been extremely difficult in the past.

[0033] As described above, the recess 42 is provided at a position facing the adhesive injection hole 41 on the bottom surface 35 facing the upper surface 32 adjacent to the connection end surface 31, and does not communicate with the optical fiber insertion hole 61, the guide pin hole 62, and the adhesive injection hole 41.

[0034] As described above, the bending of the optical fiber insertion hole 61 can be made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged more accurately.

[0035] Next, the configuration of the ferrule 101 according to an embodiment of the present invention will be described. FIGS. 6 and 7 are perspective views for explaining the outline of the configuration of the ferrule 101 according to the embodiment of the present invention. FIG. 8 is a six-sided view showing the configuration of the ferrule 101. FIG. 9 is a cross-sectional end view of the cutting portion along the line AA' or BB' shown in FIG. 8(A) showing the configuration of the ferrule 101. FIG. 9(A) is a cross-sectional end view of the cutting portion along the line AA' shown in FIG. 8(A). FIG. 9(B) is a cross-sectional end view of the cutting portion along the line BB' shown in FIG. 8(A).

[0036] FIG. 10 is an end face view of a cut portion on line CC’, DD’, EE’ or FF’ shown in FIG. 8(F), showing the configuration of the ferrule 101. FIG. 10(A) is an end face view of the cut portion on line CC’ shown in FIG. 8(F). FIG. 10(B) is an end face view of the cut portion on line DD’ shown in FIG. 8(F). FIG. 10(C) is an end face view of the cut portion on line EE’ shown in FIG. 8(F). FIG. 10(D) is an end face view of the cut portion on line FF’ shown in FIG. 8(F).

[0037] FIG. 11 is an end face view of a cut portion on line GG’ or HH’ shown in FIG. 8(F), showing the configuration of the ferrule 101. FIG. 11(A) is an end face view of the cut portion on line GG’ shown in FIG. 8(F). FIG. 11(B) is an end face view of the cut portion on line HH’ shown in FIG. 8(F).

[0038] The ferrule 101 is a member that aligns and holds and fixes the optical fiber by a sleeve or a guide pin. For example, the ferrule 101 is an MT connector ferrule. The ferrule 101 is used for an optical fiber connector such as an MPO connector or an MT connector. For example, the ferrule 101 constitutes an optical fiber connector plug, which is an optical connector attached to an optical fiber together with a housing. For example, the ferrule 101 is attached to the end of an optical fiber cord.

[0039] The ferrule 101 is molded from a resin. For example, the ferrule 101 is manufactured by injection molding a thermoplastic resin such as PPS or PEEK. Also, for example, the ferrule 101 is manufactured by transfer molding using a thermosetting resin such as an epoxy resin. That is, the ferrule 101 is a ferrule of an optical fiber connector for connecting a plurality of optical fibers and is a ferrule molded from a resin.

[0040] The ferrule 101 is formed with a connection part 121, a boot mounting part 122, a connection end face 131, an upper face 132, a left side face 133, a right side face 134, a bottom face 135, an adhesive injection hole 141, a recess 142, a recess 143, a recess 144, an optical fiber cord insertion port 145, an optical fiber insertion hole 161, a guide pin hole 162, an optical fiber groove 163, a depression 171, a depression 172, and a thin wall part 181.

[0041] The connection part 121, the boot mounting part 122, the connection end face 131, the upper face 132, the left side face 133, the right side face 134, the bottom face 135, the adhesive injection hole 141, the recess 142, the optical fiber cord insertion port 145, the optical fiber insertion hole 161, the guide pin hole 162, the optical fiber groove 163, the depression 171, the depression 172, and the thin wall part 181 are respectively the same as the connection part 21, the boot mounting part 22, the connection end face 31, the upper face 32, the left side face 33, the right side face 34, the bottom face 35, the adhesive injection hole 41, the recess 42, the optical fiber cord insertion port 45, the optical fiber insertion hole 61, the guide pin hole 62, the optical fiber groove 63, the depression 71, the depression 72, and the thin wall part 81 described with reference to FIGS. 1 to 5, and thus their descriptions will be omitted as appropriate.

[0042] Also, an adhesive injection hole 141 and a recess 143 are formed in the upper face 132. The adhesive injection hole 141 opens in the upper face 132. After an optical fiber is inserted into the ferrule 101, an adhesive for fixing the optical fiber is injected into the adhesive injection hole 141. Further, the adhesive injection hole 141 communicates with a plurality of optical fiber insertion holes 161 and the optical fiber cord insertion port 145.

[0043] The recess 143 is formed in the upper face 132. As shown in FIGS. 9(A), 10(C), and 10(D), the recess 143 is formed above a part of the optical fiber insertion hole 161. That is, the recess 143 is provided in the part of the upper face 132 where the optical fiber insertion hole 161 is formed inside the upper face 132. More specifically, the recess 143 is formed above the part of the optical fiber insertion hole 161 on the side of the adhesive injection hole 141 where the other end of the optical fiber insertion hole 161 opens.

[0044] Also, as shown in FIGS. 9(B), 10(A), 10(B), and 10(C), the recess 143 is formed above a respective part of each of the two guide pin holes 162. That is, the recess 143 is provided on the upper surface 132 of the part of the upper surface 132 where each of the two guide pin holes 162 is formed inside. More specifically, as shown in FIG. 9(B), the recess 143 is formed above the central portion in the front-rear direction of each part of the two guide pin holes 162. The recess 143 does not communicate with the optical fiber insertion hole 161, the guide pin hole 162, the adhesive injection hole 141, the recess 142 described later, and the recess 144 described later.

[0045] The recess 143 is formed around the opening of the adhesive injection hole 141 on the upper surface 132. The recess 143 is formed in a U-shaped (U-shaped) form when viewed from above so as to surround the front side, the right side, and the left side of the rectangular opening of the adhesive injection hole 141. That is, the recess 143 is formed on the connection end face 131 side, the left side face 133 side, and the right side face 134 side with respect to the rectangular opening of the adhesive injection hole 141. In other words, the recess 143 is formed above the fiber insertion hole 161 and the guide pin hole 162.

[0046] As shown in FIGS. 9 and 10, the bottom corner (inner corner) of the recess 143 is formed in a curved surface shape. For example, the bottom corner of the recess 143 is formed in a spherical crown shape. Also, in the part of the recess 143, the part close to the connection end face 131 and close to the opening of the optical fiber insertion hole 161 protrudes toward the connection end face 131 side.

[0047] Also, the recess 143 is formed symmetrically with respect to a virtual plane defined by the Z-axis and the Y-axis and passing through the central position of the connection end face 131 in the X-axis direction. That is, the recess 143 is a virtual second plane orthogonal to a virtual first plane passing through the centers of the optical fiber insertion holes 161 arranged in parallel to each other, and is formed symmetrically with respect to the virtual second plane intersecting the central portion of the connection end face 131.

[0048] Thus, the recess 143 is provided on the upper surface 132 of the portion where the optical fiber insertion hole 161 is formed inside the upper surface 132. Further, the recess 143 is provided on a part of the upper surface 132 of the portion where each of the two guide pin holes 162 is formed inside the upper surface 132.

[0049] The recess 143 is formed so as to surround three sides of the rectangular opening of the adhesive injection hole 141 on the upper surface 132, that is, three sides including the side on the connection end surface 131 side and the sides adjacent to the side on the connection end surface 131 side.

[0050] Note that the recess 143 may be formed only above the portion of the optical fiber insertion hole 161. Further, the recess 143 may be formed only above each portion of the two guide pin holes 162.

[0051] Since the recess 143 is provided, the distortion due to the residual stress of the resin generated when the ferrule 11 is molded is suppressed, the bending of the optical fiber insertion hole 61 is made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged with higher accuracy. Further, the bending of the guide pin hole 162 is made smaller, and the position of the opening of the guide pin hole 162 can be arranged with higher accuracy.

[0052] On the bottom surface 135, a recess 142 and a recess 144 are formed. The recess 142 is formed at a position facing the adhesive injection hole 141. The recess 142 does not communicate with the optical fiber insertion hole 161, the guide pin hole 162, and the adhesive injection hole 141. The recess 142 does not communicate with the optical fiber cord insertion port 145 either.

[0053] The recess 142 is composed of a recessed portion 171 and a recessed portion 172. The thin wall portion 181 is formed thinner than the wall thickness of other portions in the ferrule 101.

[0054] The recess 144 is formed in the bottom surface 135. As shown in FIGS. 9(A), 10(C), and 10(D), the recess 144 is formed below a part of the optical fiber insertion hole 161. That is, the recess 144 is provided in the part of the bottom surface 135 where the optical fiber insertion hole 161 is formed inside. More specifically, the recess 144 is formed below the part of the optical fiber insertion hole 161 on the side of the adhesive injection hole 141 where the other end of the optical fiber insertion hole 161 is open.

[0055] Also, as shown in FIGS. 9(B), 10(A), 10(B), and 10(C), the recess 144 is formed below a part of each of the two guide pin holes 162. That is, the recess 144 is provided in the part of the bottom surface 135 where each of the two guide pin holes 162 is formed inside. More specifically, as shown in FIG. 9(B), the recess 144 is formed below the central part in the front-rear direction of each of the two guide pin holes 162. The recess 144 does not communicate with the optical fiber insertion hole 161, the guide pin hole 162, the adhesive injection hole 141, the recess 142, and the recess 143.

[0056] The recess 144 is formed around the opening of the recess 142 in the bottom surface 135. The recess 144 is formed in a U-shaped (U-shaped) manner when viewed from below so as to surround the front side, the right side, and the left side of the rectangular opening of the recess 142. That is, the recess 144 is formed on the connection end face 131 side, the left side face 133 side, and the right side face 134 side with respect to the rectangular opening of the recess 142. In other words, the recess 144 is formed below the optical fiber insertion hole 161 and the guide pin hole 162.

[0057] As shown in FIGS. 9 and 10, the corners (inner corners) on the bottom side of the recess 144 are formed in a curved surface shape. For example, the corners on the bottom side of the recess 144 are formed in a spherical crown shape. Also, in the part of the recess 144 that is close to the connection end face 131 and close to the opening of the optical fiber insertion hole 161, it protrudes toward the connection end face 131 side.

[0058] Further, the recess 144 is a virtual plane defined by the Z-axis and the Y-axis, and is formed symmetrically with respect to a virtual plane passing through the center position of the connection end face 131 in the X-axis direction. That is, the recess 144 is a virtual second plane orthogonal to a virtual first plane passing through the centers of the optical fiber insertion holes 161 arranged in parallel to each other, and is formed symmetrically with respect to the virtual second plane intersecting the central portion of the connection end face 131.

[0059] Thus, the recess 144 is provided in the bottom surface 135 at the portion of the bottom surface 135 where the optical fiber insertion holes 161 are formed inside. Further, the recess 144 is provided in the bottom surface 135 at the portion of the bottom surface 135 where each of the two guide pin holes 162 is formed inside.

[0060] Furthermore, the recess 143 is a virtual plane defined by the X-axis and the Y-axis, and is formed symmetrically with the recess 144 with respect to a virtual plane passing through the center position of the connection end face 131 in the Y-axis direction. That is, the recess 143 is formed symmetrically with the recess 144 with respect to a virtual plane parallel to the upper surface 132 and the bottom surface 135, which is sandwiched between the upper surface 132 and the bottom surface 135.

[0061] Thus, the recess 144 is formed so as to surround three sides of the rectangular opening of the recess 142 in the bottom surface 135, which are the side on the connection end face 131 side and the two sides adjacent to the side on the connection end face 131 side.

[0062] Note that the recess 144 may be formed only below the portion of the optical fiber insertion hole 161. Further, the recess 144 may be formed only below each portion of the two guide pin holes 162.

[0063] Since the recess 144 is provided, distortion due to residual stress of the resin generated when forming the ferrule 11 can be suppressed, the bending of the optical fiber insertion hole 61 can be made smaller, and the position of the opening of the optical fiber insertion hole 61 can be arranged with higher accuracy. Further, the bending of the guide pin hole 162 can be made smaller, and the position of the opening of the guide pin hole 162 can be arranged with higher accuracy.

[0064] By providing either one or both of the recess 143 and the recess 144, the variation in the position of the opening of the optical fiber insertion hole 161 can be made smaller than 0.1 μm. Thereby, it is possible to manufacture the ferrule 11 suitable for connection of a single-mode optical fiber with good yield, which has been extremely difficult in the past.

[0065] As described above, according to the present invention, the bending of the optical fiber insertion hole can be made smaller, and the position of the opening of the optical fiber insertion hole can be arranged with higher accuracy.

[0066] Thus, the ferrule 101 is a ferrule of an optical fiber connector for connecting a plurality of optical fibers and is formed from a resin. The ferrule 101 has an optical fiber insertion hole 161 for passing each of the plurality of optical fibers arranged parallel to each other, two guide pin holes 162 arranged parallel to the optical fiber insertion hole 161 and sandwiching the optical fiber insertion hole 161, and an adhesive injection hole 141 that opens in a predetermined surface among the surfaces adjacent to the connection end surface 131, which is the surface on the side in contact with another device when fitted and is the surface where the optical fiber insertion hole 161 and the guide pin holes 162 open, specifically, on the upper surface 132. The adhesive injection hole 141 is a hole for injecting an adhesive for fixing the optical fiber. A recess 142 is provided at a position facing the adhesive injection hole 141 on the bottom surface 135, which is the surface opposite to the upper surface 132 among the surfaces adjacent to the connection end surface 131. A recess 144 is formed in a portion of the bottom surface 135 where the optical fiber insertion hole 161 is formed inside. The recess 142 does not communicate with the optical fiber insertion hole 161, the guide pin holes 162, and the adhesive injection hole 141. The recess 144 does not communicate with the optical fiber insertion hole 161, the guide pin holes 162, the adhesive injection hole 141, and the recess 142.

[0067] The recess 144 can be formed in a portion of the bottom surface 135 where each of the two guide pin holes 162 is formed inside.

[0068] The recess 144 can be formed symmetrically with respect to a virtual bottom surface 135 that is orthogonal to a virtual upper surface 132 passing through the centers of the optical fiber insertion holes 161 arranged parallel to each other and intersects the central portion of the connection end surface 131.

[0069] A recess 143 can be further formed in a portion of the upper surface 132 where the optical fiber insertion hole 161 is formed inside. The recess 143 does not communicate with the optical fiber insertion hole 161, the guide pin holes 162, the adhesive injection hole 141, the recess 142, and the recess 144.

[0070] The recess 143 can be formed in a portion of the upper surface 132 where each of the two guide pin holes 162 is formed inside the upper surface 132.

[0071] The recess 143 can be formed symmetrically with respect to a virtual bottom surface 135 that is orthogonal to a virtual upper surface 132 passing through the centers of the optical fiber insertion holes 161 arranged in parallel to each other and that intersects the central portion of the connection end surface 131.

[0072] The recess 143 can be formed symmetrically with respect to the recess 144 with respect to a virtual surface that is sandwiched between the upper surface 132 and the bottom surface 135 and that is parallel to the upper surface 132 and the bottom surface 135.

[0073] The recess 142 can be blocked from the adhesive injection hole 141 by a thin-walled portion 181 having a thickness thinner than that of other portions.

[0074] The recess 142 can be composed of a recessed portion 172 having a predetermined depth from the bottom surface 135 and a recessed portion 171 having a depth deeper than that of the recessed portion 172 from the bottom surface 135 and being disposed on the connection end surface 131 side.

[0075] The bottom-side corner of the recess 142 can be formed in a curved surface shape.

[0076] Moreover, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

Explanation of Reference Numerals

[0077] 11 ferrule, 21 connection part, 22 boot mounting part, 31 connection end face, 32 upper surface, 33 left side surface, 34 right side surface, 35 bottom surface, 41 adhesive injection hole, 42 recess, 45 optical fiber cord insertion port, 61 optical fiber insertion hole, 62 guide pin hole, 63 optical fiber groove, 71 and 72 recessed parts, 81 thin part 81, 101 ferrule 1, 121 connection part, 122 boot mounting part, 131 connection end face, 132 upper surface, 133 left side surface, 134 right side surface, 135 bottom surface, 141 adhesive injection hole, 142 to 144 recesses, 145 optical fiber cord insertion port, 161 optical fiber insertion hole, 162 guide pin hole, 163 optical fiber groove, 171 and 172 recessed parts, 181 thin part

Claims

1. A ferrule of an optical fiber connector for connecting a plurality of optical fibers, the ferrule being formed from resin, wherein a plurality of optical fiber insertion holes for passing each of the plurality of optical fibers arranged parallel to each other; two guide pin holes arranged parallel to the optical fiber insertion holes and sandwiching the optical fiber insertion holes; a hole for injecting an adhesive for fixing the optical fiber, which opens in a first surface that is a predetermined surface among the surfaces adjacent to the connection end surface where the optical fiber insertion holes and the guide pin holes open; a first recess provided at a position facing the adhesive injection hole on a second surface that is a surface facing the first surface among the surfaces adjacent to the connection end surface; a second recess provided in a portion of the first surface where the optical fiber insertion hole is formed inside among the first surfaces; are formed, the first recess is composed of a first recessed portion having a predetermined depth from the second surface and a second recessed portion having a greater depth from the second surface compared to the depth of the first recessed portion and being disposed on the connection end surface side; the first recess does not communicate with the optical fiber insertion hole, the guide pin hole, and the adhesive injection hole; the second recess does not communicate with the optical fiber insertion hole, the guide pin hole, the adhesive injection hole, and the first recess ferrule.

2. The ferrule according to claim 1, wherein the second recess extends to a portion of the first surface where each of the two guide pin holes is formed inside among the first surfaces of the ferrule.

3. The ferrule according to claim 2, wherein the second recess is a second virtual plane orthogonal to a first virtual plane that includes in-plane a plurality of center lines of the optical fiber insertion holes arranged parallel to each other, and is formed symmetrically with respect to a second virtual plane that intersects the central portion of the connection end surface.

4. The ferrule according to claim 1, wherein the first recess is blocked from the adhesive injection hole by a thin-walled portion having a thinner wall thickness than other portions ferrule.

5. The ferrule according to claim 1, wherein the bottom corner of the first recess is formed in a curved surface shape.

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