Optical connector and ferrule

Abstract

This optical connector comprises: a plurality of optical fibers; a ferrule having a plurality of fiber holes through which the plurality of optical fibers are inserted, two positioning holes, and a connection end surface in which the plurality of fiber holes and the two positioning holes are opened; and a housing for holding the ferrule. The connection end surface is inclined with respect to a virtual plane perpendicular to a longitudinal direction of the plurality of fiber holes when viewed from a juxtaposing direction in which the two positioning holes are arranged. The housing has a housing-side contact surface, and the ferrule has a ferrule-side contact surface that limits the amount of protrusion of the ferrule from the housing by coming into contact with the housing-side contact surface. In a state in which the housing-side contact surface and the ferrule-side contact surface are in contact with each other, the ferrule is swingable about a swing center axis with respect to the housing. The swing center axis is located at a position at which the housing-side contact surface and the ferrule-side contact surface are in contact with each other, and extends in an orthogonal direction that is orthogonal to both the longitudinal direction and the juxtaposing direction.

Description

Optical Connectors and Ferrules

[0001] The present invention relates to an optical connector and a ferrule. This application claims priority to Japanese Patent Application No. 2023-114788, filed on July 12, 2023, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses an optical connector equipped with a ferrule having an inclined connection end face. By inclining the connection end face of the optical fiber in this way, the amount of light reflection at the connection point can be reduced. Furthermore, because the connection end face is inclined, when connecting a pair of optical connectors, the ferrule slides relative to the connection end face of the other connector. Taking this amount of displacement into account, the position of the optical fiber at the connection end face is offset in advance relative to the positioning pin.

[0003] Japanese Patent Application Publication No. 2019-101232

[0004] In optical connectors with tilted connection end faces, the actual displacement may be smaller than the designed displacement amount, causing axial misalignment between the optical fibers of the pair of optical connectors and increasing the optical connection loss.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to reduce optical connection loss in a ferrule and optical connector having an inclined connection end face.

[0006] An optical connector according to aspect 1 of the present invention comprises a plurality of optical fibers, a ferrule having a plurality of fiber holes through which the plurality of optical fibers are inserted, two positioning holes, and a connection end face through which the plurality of fiber holes and the two positioning holes open, and a housing for holding the ferrule, wherein the connection end face is inclined with respect to an imaginary plane perpendicular to the longitudinal direction of the plurality of fiber holes when viewed from the parallel direction in which the two positioning holes are arranged, the housing has a housing side contact surface, and the ferrule has a ferrule side contact surface that contacts the housing side contact surface to limit the amount of protrusion of the ferrule from the housing, and when the housing side contact surface and the ferrule side contact surface are abutting, the ferrule can swing relative to the housing around a swing center axis, and the swing center axis is located at a position where the housing side contact surface and the ferrule side contact surface contact, and extends in an orthogonal direction perpendicular to both the longitudinal direction and the parallel direction.

[0007] A second aspect of the present invention is the optical connector according to the first aspect, wherein the housing-side contact surface is a curved surface.

[0008] The ferrule of aspect 3 of the present invention is a ferrule that is partially accommodated inside the housing of an optical connector, and comprises a plurality of fiber holes through which a plurality of optical fibers can be inserted, two positioning holes, a connection end face into which the two positioning holes and the plurality of fiber holes open, and a ferrule side contact surface that contacts the housing to limit the amount of protrusion of the ferrule from the housing, wherein the connection end face is inclined with respect to an imaginary plane perpendicular to the longitudinal direction of the plurality of fiber holes when viewed from the parallel direction in which the two positioning holes are arranged, and the ferrule side contact surface is a curved surface.

[0009] A fourth aspect of the present invention is a ferrule according to the third aspect, which has two recesses arranged on either side of the ferrule-side contact surface in the parallel direction, and the two recesses are recessed relative to the ferrule-side contact surface toward the opposite side of the connection end face in the longitudinal direction.

[0010] A fifth aspect of the present invention is a ferrule according to the third or fourth aspect, which has two ferrule-side contact surfaces including the ferrule-side contact surface, and the two ferrule-side contact surfaces are provided at different positions in an orthogonal direction that is orthogonal to both the longitudinal direction and the parallel direction.

[0011] A sixth aspect of the present invention is a ferrule according to any one of the third to fifth aspects, further comprising a protrusion that protrudes in an orthogonal direction that is orthogonal to both the longitudinal direction and the parallel direction, the protrusion having the ferrule-side contact surface.

[0012] According to the above aspects of the present invention, it is possible to reduce optical connection loss in a ferrule and optical connector with an inclined connection end face.

[0013] 1 is a perspective view of an optical connector according to the present embodiment. FIG. 1 is a view taken in the direction of an arrow II in FIG. 1. FIG. 2 is a view of the optical connector of FIG. 1 as seen from the tip side. FIG. 3 is a perspective view of the ferrule of FIG. 1. FIG. 4 is a cross-sectional view taken in the direction of an arrow V-V in FIG. 1. FIG. 5 is a schematic view showing how two optical connectors according to the present embodiment are connected. FIG. 6 is a schematic view showing how two optical connectors according to the present embodiment are connected. FIG. 7 is a view explaining the position of a positioning pin of a male optical connector inside a positioning hole of a female optical connector. FIG. 8 is a view explaining the position of a positioning pin of a male optical connector inside a positioning hole of a female optical connector. FIG. 9 is a schematic view showing how a ferrule swings relative to a housing in the optical connector of the present embodiment. FIG. 10 is a schematic view of an optical connector according to a first modified example. FIG. 11 is a schematic view of an optical connector according to a second modified example. FIG. 12 is a schematic view of an optical connector according to a third modified example. FIG. 13 is a schematic view of an optical connector according to a fourth modified example.

[0014] The optical connector and ferrule of this embodiment will be described below with reference to the drawings. As shown in FIG. 1, the optical connector 1 includes a ferrule 10, a housing 20, a boot 30, and a plurality of optical fibers F. The ferrule 10 has a plurality of fiber holes 12 and two positioning holes 13 formed therein. An optical fiber F is inserted through each of the fiber holes 12. However, some of the fiber holes 12 may not have an optical fiber F inserted therethrough. In other words, the number of optical fibers F may be less than the number of fiber holes 12. The ferrule 10 has a connection end face 11. The fiber holes 12 and the positioning holes 13 open in the connection end face 11. The housing 20 has an opening 21. A portion of the ferrule 10 protrudes outside the housing 20 through the opening 21.

[0015] (Direction Definition) In this specification, the direction in which the multiple fiber holes 12 extend is referred to as the longitudinal direction Z. The side of the longitudinal direction Z toward the connection end face 11 (+Z side) is referred to as the tip side. The opposite side (-Z side) is referred to as the base side. The direction in which the two positioning holes 13 are aligned is referred to as the parallel direction X. The direction perpendicular to both the longitudinal direction Z and the parallel direction X is referred to as the perpendicular direction Y.

[0016] The housing 20 holds a portion of the ferrule 10 therein. The tip end (the end on the +Z side) of the ferrule 10 protrudes from the housing 20. The housing 20 contains a pin clamp 40, a biasing member 50 (see FIG. 5 ), and the like. The biasing member 50 biases the ferrule 10 toward the connecting end face 11, which is the tip side. The biasing member 50 may be, for example, a coil spring. The pin clamp 40 is disposed between the biasing member 50 and the ferrule 10. The biasing force of the biasing member 50 is transmitted to the ferrule 10 via the pin clamp 40. However, the pin clamp 40 may not be disposed, and the biasing member 50 may be in direct contact with the ferrule 10.

[0017] Figure 2 is a view of the tip of the optical connector 1 as viewed from the parallel direction X. An imaginary plane P shown in Figure 2 is a plane perpendicular to the longitudinal direction Z. The connection end face 11 is inclined with respect to the imaginary plane P as viewed from the parallel direction X. The angle between the connection end face 11 and the imaginary plane P is, for example, 8°. However, this angle can be changed. In this way, the inclination of the connection end face 11 of the ferrule 10 has the effect of suppressing the occurrence of Fresnel reflection when two optical connectors 1 are connected.

[0018] After the ferrule 10 is formed by injection molding, a part or all of the connection end face 11 may not be inclined with respect to the imaginary plane P. After molding, the connection end face 11 may be polished to make the connection end face 11 inclined with respect to the imaginary plane P. During polishing, the optical fiber F may be protruded from the fiber hole 12, and the connection end face 11 may be polished together with the optical fiber F.

[0019] As shown in Fig. 3, the ferrule 10 of this embodiment has a total of 12 fiber holes 12 formed therein. These fiber holes 12 are arranged in a single row. That is, one row (hereinafter referred to as a fiber row) including 12 fiber holes 12 is arranged. The fiber holes 12 included in the fiber row are arranged side by side in the parallel direction X. Note that the ferrule 10 may have two or more fiber rows. The number of fiber holes 12 included in one fiber row may be changed.

[0020] 3 , the housing 20 has a first restricting portion 22 and a second restricting portion 23. The first restricting portion 22 and the second restricting portion 23 protrude toward the inside of the opening 21. The first restricting portion 22 and the second restricting portion 23 are arranged to sandwich the ferrule 10 therebetween. The first restricting portion 22 and the second restricting portion 23 restrict the ferrule 10 from falling off toward the tip end of the housing 20.

[0021] As shown in FIG. 4 , the ferrule 10 has a first end face 14 and a second end face 15 facing the orthogonal direction Y. A first recess 14a is formed in the first end face 14, and a second recess 15a is formed in the second end face 15. A ferrule-side contact surface 14b and two relief portions 14c are formed on the inner wall of the first recess 14a. The ferrule-side contact surface 14b faces the tip side (+Z side). As shown in FIG. 5 , the first restricting portion 22 fits inside the first recess 14a. The first restricting portion 22 has a housing-side contact surface 22a that contacts the ferrule-side contact surface 14b.

[0022] As shown in FIG. 5 , the biasing force of the biasing member 50 presses the ferrule-side contact surface 14b against the housing-side contact surface 22a. This contact between the ferrule-side contact surface 14b and the housing-side contact surface 22a determines the amount of protrusion of the ferrule 10 relative to the housing 20. In this embodiment, the ferrule-side contact surface 14b is a curved surface that is convex toward the tip (+Z side). Therefore, with the ferrule-side contact surface 14b and the housing-side contact surface 22a in contact, the ferrule 10 can swing relative to the housing 20. The central axis of this swing (hereinafter referred to as the swing central axis C) is located at the position where the ferrule-side contact surface 14b and the housing-side contact surface 22a contact. The swing central axis C extends in the orthogonal direction Y. When the ferrule 10 swings, the angle of the connection end face 11 with respect to the parallel direction X changes. A mechanism that swings the ferrule 10 in this manner is referred to as a "swing mechanism."

[0023] The two recesses 14c are connected to both ends of the ferrule-side contact surface 14b in the parallel direction X. The two recesses 14c are recessed toward the base end (-Z side) with respect to the ferrule-side contact surface 14b. The formation of the recesses 14c makes it easier for the ferrule 10 to swing relative to the housing 20. As a result, optical connection loss is stabilized when optical connectors 1 are connected to each other multiple times.

[0024] As shown in Fig. 3, the second restricting portion 23 fits into the second recess 15a. Although not shown, the second restricting portion 23 has a second housing-side contact surface, and the second recess 15a has a second ferrule-side contact surface. In other words, the ferrule 10 has two ferrule-side contact surfaces, and the housing 20 has two housing-side contact surfaces. The two ferrule-side contact surfaces are located at different positions in the orthogonal direction Y. Like the first recess 14a, the second recess 15a may also have two relief portions.

[0025] Next, the operation of the optical connector 1 and the ferrule 10 configured as above will be described.

[0026] 6A and 6B are schematic diagrams illustrating the connection of two optical connectors 1. One of the two optical connectors 1 is male, and the other is female. The male optical connector 1 has two positioning pins 13p. Each positioning pin 13p passes through two positioning holes 13 in the male ferrule 10 and is held by a pin clamp 40. The two optical connectors 1 are positioned by inserting the male positioning pins 13p into the female positioning holes 13.

[0027] Here, the connection end faces 11 in this embodiment are inclined. Therefore, when the connection end faces 11 of the two optical connectors 1 are brought into contact with each other, a component force f is generated as shown by the arrow in FIG. 6B. The component force f acts in a direction that moves the ferrule 10 in the orthogonal direction Y. Here, the outer diameter of the positioning pin 13p is smaller than the inner diameter of the positioning hole 13. In other words, a gap exists between the positioning pin 13p and the positioning hole 13. This gap is provided for the purpose of making it easier to insert the positioning pin 13p into the positioning hole 13.

[0028] 7A and 7B show examples of the position of the male-side positioning pin 13p inside the female-side positioning hole 13. FIG. 7A shows an ideal state, while FIG. 7B shows a non-ideal state. For ease of understanding, the size of the gap between the positioning pin 13p and the positioning hole 13 is exaggerated in FIGS. 7A and 7B. As shown in FIG. 7A, in an ideal state, the center of the positioning pin 13p and the center of the female-side positioning hole 13 coincide in the parallel direction X. In this state, the distance between the center of the positioning pin 13p and the center of the positioning hole 13 is referred to as the design displacement dY. Taking the design displacement dY into consideration, the dimensions of the ferrule 10 are determined so that the fiber holes 12 of the two optical connectors 1 are properly positioned relative to each other. A specific example of the "dimension" is the distance between each fiber hole 12 in the orthogonal direction Y relative to the positioning hole 13.

[0029] However, when connecting two optical connectors 1, the optical connectors 1 may be tilted relative to each other. In this case, as shown in FIG. 7B , the center of the male positioning pin 13p may be displaced in the parallel direction X relative to the center of the female positioning hole 13. In this state, the magnitude of the displacement in the orthogonal direction Y between the center of the positioning pin 13p and the center of the positioning hole 13 is referred to as the actual displacement amount ΔY. If the actual displacement amount ΔY differs from the designed displacement amount dY, the positions of the fiber holes 12 of the two optical connectors 1 will be misaligned. This will result in an increase in optical connection loss.

[0030] Therefore, the optical connector 1 of this embodiment is configured so that the ferrule 10 can swing relative to the housing 20 while the ferrule-side contact surface 14b and the housing-side contact surface 22a are in contact with each other. Specifically, as shown in FIG. 8 , the ferrule 10 swings around the swing central axis C. In FIG. 8 , the position of the ferrule 10 after swinging is indicated by the reference symbol 10′. Although the pin clamp 40 is omitted in FIG. 8 , the ferrule 10 can swing regardless of whether the pin clamp 40 is present or not. Because the ferrule 10 is swingable, even if the state shown in FIG. 7B temporarily occurs when connecting two optical connectors 1, the position of the ferrule 10 is prevented from being fixed in that state. In other words, the state shown in FIG. 7B can be transitioned to the state shown in FIG. 7A.

[0031] The mechanism of this transition will be explained in more detail. When at least one of the ferrule-side contact surface 14b and the housing-side contact surface 22a is curved, the ferrule 10 can swing as shown in FIG. 8 . Conversely, when both the ferrule-side contact surface 14b and the housing-side contact surface 22a are flat, the position of the ferrule 10 is constrained by the contact between the two flat surfaces. More specifically, because the force applied in the parallel direction X cannot be released, the ferrule 10 cannot shift in the perpendicular direction Y, in which the connecting end face 11 is inclined. In this constrained state, once the position of the ferrule 10 reaches the position shown in FIG. 7B , the position of the ferrule 10 is unlikely to change any further.

[0032] In contrast, the ferrule 10 is able to swing relative to the housing 20, which alleviates the constraints on the ferrule's position. When connecting two optical connectors 1, a component force f (see FIG. 6B) generated by the inclination of the connecting end face 11 acts to bring the ferrule 10 into the state shown in FIG. 7A. In other words, the presence of the "swing mechanism" more reliably exerts the effect of the component force f, allowing the actual displacement amount ΔY to approach the designed displacement amount dY. Therefore, the amount of misalignment between the fiber holes 12 of the pair of optical connectors 1 is reduced. As a result, the optical connection loss can be reduced.

[0033] In this embodiment, the ferrule-side contact surface 14b is a curved surface. However, the ferrule-side contact surface 14b may be a flat surface. In this case, if the housing-side contact surface 22a is a curved surface, the ferrule 10 can swing relative to the housing 20. If the housing 20 can swing, the effect of reducing optical connection loss can be obtained.

[0034] As described above, the optical connector 1 of this embodiment includes a plurality of optical fibers F, a ferrule 10, and a housing 20 that holds the ferrule 10. The housing 20 has a housing-side contact surface 22a. The ferrule 10 has a ferrule-side contact surface 14b that contacts the housing-side contact surface 22a to limit the amount of protrusion of the ferrule 10 from the housing 20. With the housing-side contact surface 22a and the ferrule-side contact surface 14b in contact, the ferrule 10 can swing relative to the housing 20 about a swing central axis C. The swing central axis C is located at a position where the housing-side contact surface 22a and the ferrule-side contact surface 14b contact each other, and extends in the orthogonal direction Y that is orthogonal to both the longitudinal direction Z and the parallel direction X.

[0035] Furthermore, a portion of the ferrule 10 of this embodiment is housed inside the housing 20 of the optical connector 1. The ferrule 10 includes a plurality of fiber holes 12 through which a plurality of optical fibers F can be inserted, two positioning holes 13, a connection end face 11 in which the two positioning holes 13 and the plurality of fiber holes 12 open, and a ferrule-side contact surface 14b that contacts the housing 20 to limit the amount of protrusion of the ferrule 10 from the housing 20. When viewed from the parallel direction X in which the two positioning holes 13 are aligned, the connection end face 11 is inclined with respect to an imaginary plane P (see FIG. 2 ) that is perpendicular to the longitudinal direction Z of the plurality of fiber holes 12. The ferrule-side contact surface 14b is a curved surface.

[0036] According to the optical connector 1 or ferrule 10 having the above configuration, the optical connection loss can be reduced.

[0037] The ferrule 10 may also have two recesses 14c arranged to sandwich the ferrule-side contact surface 14b in the parallel direction X. The two recesses 14c may be recessed on the opposite side (-Z side) of the connecting end face 11 in the longitudinal direction Z with respect to the ferrule-side contact surface 14b. In this case, when the ferrule 10 swings relative to the housing 20, a portion of the housing-side contact surface 22a can enter the recesses 14c. This makes it easier for the ferrule 10 to swing relative to the housing 20.

[0038] The ferrule 10 may also have two ferrule-side contact surfaces, including the ferrule-side contact surface 14b. The two ferrule-side contact surfaces may be provided at different positions in the orthogonal direction Y. In this way, by abutting the two ferrule-side contact surfaces against the housing 20 at different positions in the orthogonal direction Y, the posture of the ferrule 10 can be stabilized.

[0039] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0040] Modifications of this embodiment will be described with reference to FIGS. 9 to 12. The pin clamp 40 is omitted in FIGS. 9 to 12. The pin clamp 40 may not be necessary. In the example of FIG. 9, the ferrule-side contact surface 14b is flat, and the housing-side contact surface 22a is curved. In this case, the ferrule 10 can also swing relative to the housing 20. In other words, if either the ferrule-side contact surface 14b or the housing-side contact surface 22a is curved, the ferrule 10 can swing.

[0041] In the example of Fig. 10, a recess recessed toward the tip end (+Z side) is formed in the first restricting portion 22. The inside of this recess serves as the housing-side contact surface 22a. In the example of Fig. 11, a recess recessed toward the base end (-Z side) is formed in the ferrule 10. The inside of this recess serves as the ferrule-side contact surface 14b. In the example of Fig. 12, a protrusion 14P is formed in the ferrule 10. The protrusion 14P protrudes outward in the orthogonal direction Y from the first end surface 14 of the ferrule 10. The outer peripheral surface of this protrusion 14P serves as the ferrule-side contact surface 14b.

[0042] 9 to 12 can achieve the same effects as the above-described embodiment. FIGS. 9 to 12 show the structure on the first end face 14 side of the ferrule 10. However, a similar structure may also be provided on the second end face 15 side. For example, the ferrule 10 in the example of FIG. 12 may have, in addition to the protrusion 14P, a second protrusion that protrudes outward from the second end face 15 in the orthogonal direction Y. The outer peripheral surface of the second protrusion may then be the ferrule-side contact surface. In other words, the ferrule 10 may have two protrusions, and the outer peripheral surfaces of the two protrusions may each be the ferrule-side contact surface.

[0043] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, and the above-described embodiments and variations may be combined as appropriate, without departing from the spirit of the present invention.

[0044] 1... Optical connector 10... Ferrule 11... Connection end face 12... Fiber hole 13... Positioning hole 14b... Ferrule side contact surface 14c... Relief portion 14P... Protrusion 20... Housing 22a... Housing side contact surface C... Swing center axis F... Optical fiber P... Virtual plane X... Parallel direction Y... Orthogonal direction Z... Longitudinal direction

Claims

1. Multiple optical fibers, A ferrule having a plurality of fiber holes through which the plurality of optical fibers are inserted, two positioning holes, and a connecting end face through which the plurality of fiber holes and the two positioning holes open, The housing comprises a ferrule, The aforementioned connection end face is inclined with respect to a virtual plane perpendicular to the longitudinal direction of the plurality of fiber holes, when viewed from the parallel direction in which the two positioning holes are arranged. The housing has a housing-side contact surface, The ferrule has a ferrule-side contact surface that contacts the housing-side contact surface to limit the amount of the ferrule protruding from the housing, With the housing-side contact surface and the ferrule-side contact surface in contact, the ferrule is able to pivot about the pivot axis relative to the housing. The pivot axis is located at the position where the housing-side contact surface and the ferrule-side contact surface are in contact, and extends in an orthogonal direction perpendicular to both the longitudinal direction and the parallel direction, in an optical connector.

2. The optical connector according to claim 1, wherein the housing-side contact surface is curved.

3. A ferrule, partly housed inside the housing of an optical connector, Multiple fiber holes through which multiple optical fibers can be inserted, Two positioning holes, The connection end face through which the two positioning holes and the plurality of fiber holes are opened, A ferrule-side contact surface, which contacts the housing to limit the amount the ferrule protrudes from the housing, is provided, The aforementioned connection end face is inclined with respect to a virtual plane perpendicular to the longitudinal direction of the plurality of fiber holes, when viewed from the parallel direction in which the two positioning holes are arranged. The ferrule has a curved contact surface.

4. It has two relief portions arranged so as to sandwich the ferrule-side contact surface in the parallel direction, The ferrule according to claim 3, wherein the two relief portions are recessed with respect to the ferrule-side contact surface toward the opposite side of the connecting end surface in the longitudinal direction.

5. Having two ferrule-side contact surfaces, including the aforementioned ferrule-side contact surface, The ferrule according to claim 3 or 4, wherein the two ferrule-side contact surfaces are provided at different positions in orthogonal directions perpendicular to both the longitudinal direction and the parallel direction.

6. It is provided with protrusions that project in an orthogonal direction perpendicular to both the longitudinal direction and the parallel direction, The ferrule according to claim 3 or 4, wherein the projection has the ferrule-side contact surface.