Optical receptacle and sleeve

Abstract

An optical receptacle includes a fiber stub; and a sleeve having a sleeve main body where the fiber stub is installed, the sleeve supported by a supporting surface of a supporting member. In the optical receptacle, a leaning prevention member is provided at the sleeve; the leaning prevention member is formed so as to extend outward from the sleeve main body; and the leaning prevention member prevents leaning of the sleeve main body from the supporting surface by coming in contact with the supporting surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a related art optical receptacle;

FIG. 2 is a schematic view for explaining a wiggle characteristic;

FIG. 3 is a cross-sectional view of a fiber stub in a case where a load is applied by a sleeve with a slit forming part;

FIG. 4 is a cross-sectional view for explaining problems occurring in the sleeve with the slit forming part;

FIG. 5 is a cross-sectional view for explaining leaning of the fiber stub;

FIG. 6 is a cross-sectional view for explaining a worst case condition model of loss;

FIG. 7 is a cross-sectional view of an optical receptacle of an embodiment of the present invention;

FIG. 8 is a view showing a first example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 8-(A) is a left side view, and FIG. 8-(B) is a front view;

FIG. 9 is a cross-sectional view for explaining operation of the optical receptacle of an embodiment of the present invention;

FIG. 10 is a view showing a second example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 10-(A) is a left side view, and FIG. 10-(B) is a front view;

FIG. 11 is a view showing a third example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 11-(A) is a left side view, and FIG. 11-(B) is a front view; and

FIG. 12 is a view showing a fourth example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 12-(A) is a left side view, and FIG. 12-(B) is a front view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description is given below, with reference to the FIG. 7 through FIG. 12 of embodiments of the present invention.

FIG. 7 is a cross-sectional view of an optical receptacle 20 of an embodiment of the present invention. FIG. 8 is a view showing a first example of a sleeve 25A provided in the optical receptacle 20 of the embodiment of the present invention, FIG. 8-(A) is a left side view, and FIG. 8-(B) is a front view. In FIG. 8, the sleeve 25A is enlarged.

As shown in FIG. 7, the optical receptacle 20 includes a fiber stub 22, the sleeve 25A, a sleeve case 28, and others. The optical receptacle 20 is fixed to an optical device housing 29. The optical device housing 29 is a communication device such as a router device. The fiber stub extends from a supporting surface 29A of the optical device housing 29.

The fiber stub 22 has a structure where an optical fiber 24 is provided in the center of a ferrule 23. The fiber stub 22 is installed inside the sleeve 25A.

In this embodiment, the sleeve 25A is a precision sleeve where a slit forming part is not formed. The sleeve 25A is formed by a sleeve main body 26 and a leaning prevention plate 30. The sleeve main body 26 has a cylindrical-shaped configuration. An internal diameter of the sleeve main body 26 is minutely processed so as to be slightly greater than an external diameter of a plug ferrule 11 (see FIG. 9) inserted in the sleeve main body 26 by several μm.

The leaning prevention plate 30 extends outward from the sleeve main body 26. By the leaning prevention plate 30 and the supporting surface 29A contacting each other, leaning of the sleeve main body 26 against the supporting surface 29A can be prevented. In this embodiment of the present invention, three pieces of the leaning prevention plate 30 are formed on the sleeve main body 26 at even intervals.

In addition, the leaning prevention plate 30 may be formed in a body with the sleeve main body 26. The leaning prevention plate 30 may be fixed to the sleeve main body 26 by welding or the like. Furthermore, as shown in FIG. 7, the distance between an end part of the leaning prevention plate 30 and the supporting surface 29A, indicated by an arrow L1 in FIG. 7 and FIG. 8-(B), is shorter than the distance between the contact surface 22a and the supporting surface 29A of the fiber stub 22, indicated by an arrow L2 in FIG. 7 (L1<L2).

FIG. 9 is a cross-sectional view for explaining operation of the optical receptacle 20 of the embodiment of the present invention.

In the optical receptacle 20 shown in FIG. 9, a plug ferrule 11 provided in a connector 10 is inserted in the sleeve 25A. The contact surface 22a of the fiber stub 22 and a contact surface 11a of the plug ferrule 11 are connected so that the optical fiber 24 and an optical fiber 12 are optically connected to each other. The sleeve case 28 protects the sleeve 25 and fixed to the supporting surface 29A.

Next, a function of the leaning prevention plate 30 provided on the sleeve 25A of the embodiment of the present invention is discussed. As discussed above, the optical receptacle 20 of the embodiment of the present invention has a structure where plural leaning prevention plates 30 are provided on the outer periphery of the sleeve main body 26 in order to prevent the sleeve 25A from leaning, namely in order to prevent the inclination θs in FIG. 5.

A surface of the leaning prevention plate 30 coming in contact with the supporting surface 29A is flat and the leaning prevention plate 30 is adhered to the supporting surface 29A. In addition, as discussed above, the leaning prevention plates 30 are arranged in a radial manner around the sleeve main body 26 having the cylindrical-shape configuration. Because of this, as compared with the precision sleeve 6 shown in FIG. 5 having no leaning prevention plates 30, even if the external force is applied in a direction perpendicular to the optical axis, it is possible to improve stabilization against this.

In addition, as discussed above, the distance L1 in the longitudinal direction (optical axis direction) of the leaning prevention plate 30 is shorter than the distance L2 between the contact surface 22a and the supporting surface 29A of the fiber stub 22 (L1<L2). The distance L1 of the leaning prevention plate 30 does not directly influence the inclination θs of the sleeve 25A at the connection time of the connector 10.

However, in a case of a standard type optical receptacle 20, a connection part of the sleeve case 28 is situated in the vicinity of the contact surface 22a, namely the PC end surface, where the plug ferrule 11 and the fiber stub 22 come in contact with each other. Since the contact surface 22a and the learning prevention plate 30 may interfere with each other, it is generally preferable that the distance L1 does not allow the leaning prevention plate 30 to reach the contact surface 22a.

In addition, an external diameter indicated by an arrow “W” in FIG. 8-(A) of the sleeve 25A including the leaning prevention plate 30 also does not directly influence the inclination θs of the sleeve 25A. However, the external diameter indicated by an arrow “W” in FIG. 8-(A) of the sleeve 25A including the leaning prevention plate 30 may be a limitation on mounting. In the case of a standard type optical receptacle 20, the external configuration of the sleeve 25A including the leaning prevention plate 30 is not larger than that of the sleeve case 28. Considering the LC connector standard, the external diameter indicated by the arrow “W” in FIG. 8-(A) of the sleeve 25A including the leaning prevention plate 30 is equal to or less than 2.9 mm.

In addition, an allowable error Le of the supporting surface 29A is normally determined by the external diameter W of the leaning prevention plate 30 and the inclination θs of the sleeve 27A at the time of connection of the connector 10 being a target. The allowable error Le of the supporting surface 29A indicates a manufacturing error in the optical axial direction at an end point situated furthest from the center of the sleeve 25A and the leaning prevention structure.

At the end point, if an error from the center is equal to or less than the allowable error “Le” of the supporting surface 29A, the inclination of the sleeve 25A is equal to or less than θs in the ideal case. The average of a circular part of the sleeve 25A coming in contact with the supporting surface 29A can be substituted for the center of the sleeve 25A having imaginary coordinates. For example, if “W” equals to 2.5 mm, the allowable error Le at the supporting surface is approximately 99.1 μm.

Next, functions of the sleeve 25A and the optical receptacle 20 of the embodiment of the present invention are discussed with reference to FIG. 9.

There is extremely little play of the sleeve 25A fixed to the supporting surface 29A in three-dimensional directions, namely X, Y and Z directions. Zirconium oxide that is a material of the precision sleeve 25A has a limited deformation amount due to the external force.

In addition, an internal diameter of the precision sleeve 25A is processed in precision. The shift due to manufacturing error of the fiber stub 22 is maximum d=1.75 μm. In this case, while the loss is approximately 0.53 dB, this is a worst case value and almost no influence is applied in actuality.

FIG. 9 shows positional relationships of the plug ferrule 11, the fiber stub 22, and the sleeve 25A when the external force is applied to the connector 10. The external force applied to the connector 10 is applied to the plug ferrule 11. In the example shown in FIG. 9, a load F1 is applied downward.

On the other hand, the plug ferrule 11 is inclined at an angle of θs by the external force. Simultaneously, the plug ferrule 11 is inclined at angle of θ due to differences of the internal diameter of the plug ferrule 11 and the external configuration of the ferrule 23 (fiber stub 22). In other words, the contact surface 11a of the plug ferrule 11 is inclined at an angle of θ+θs with the contact surface 22a of the fiber stub 22.

External forces F2 and F3 generated at the leaning prevention plate 30 by the load F acts in substantially perpendicular directions compared to the supporting surface 29A, the supporting surface 29A adhering to the leaning prevention plate 30. In FIG. 9, the external force F2 generated at the leaning prevention plate 30 situated at the lower part acts as a force pressing the supporting surface 29A. On the other hand, the external force F3 generated at the leaning prevention plate 30 situated at the upper part acts as a force so that the leaning prevention plate 30 is separated from the supporting surface 29A.

However, the difference between the internal diameter of the sleeve 25A and the external configuration of the fiber stub 22 is extremely small. Therefore, the sleeve 25A is caught by the fiber stub 22, so that the sleeve 25A is securely prevented from leaving and the sleeve 25A remains fixed to the optical receptacle 20. Accordingly, since the sleeve 25A is supported by the supporting surface 29A, the inclination θs of the sleeve 25A does not exceed a target limitation value. Hence, optical loss at the angle of θ+θs can be limited to be equal to or less than the target value.

Thus, according to the optical receptacle 20 of the embodiment of the present invention, the falling of the sleeve 25A due to manufacturing unevenness of the fiber stub 22 is stabilized by the leaning prevention plate 30 adhering to the supporting surface 29A. Hence, it is possible to stabilize the wiggle characteristic.

In addition, according to the embodiment of the present invention, since the load (external force) is not directly applied to a base part of the fiber stub 22 provided by press fitting, all of loads are not applied to a press fitting part. Therefore, it is possible to improve reliability.

In addition, while it is most suitable to use the present invention in the precision sleeve as discussed above, the present invention can be applied to a split sleeve 25B as shown in FIG. 10 where the slit forming part 27 is formed in the sleeve main body 26. Here, FIG. 10 is a view showing a second example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 10-(A) is a left side view, and FIG. 10-(B) is a front view.

As discussed above, the wiggle characteristic is improved by using the precision sleeve. Similarly, in the sleeve 25B where the slit 27 is formed, depending on the optical characteristic, it is possible to obtain a better characteristic as compared with the precision sleeve. In this case, depending on the optical characteristic, it may be possible to improve the wiggle characteristic by using the split sleeve 25B having the slit forming part 27.

In this case, it can be expected to improve the wiggle characteristic due to leaning of the split sleeve 25B having the slit forming part 27. However, a main reason of degradation of the wiggle characteristic of the sleeve 25B is the above-discussed elastic deformation. Therefore, the elastic deformation may not be prevented by the sleeve 25B. Thus, an effect achieved by the sleeve 25B may be limited.

In addition, in the above-discussed example, three leaning prevention plates 30 are provided on the sleeve main body 26. However, the number of the leaning prevention plate 30 is not limited to three. For example, as shown in FIG. 11, six leaning prevention plates 30 may be provided on the sleeve main body 26. Here, FIG. 11 is a view showing a third example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 11-(A) is a left side view, and FIG. 11-(B) is a front view. Thus, by increasing the number of the leaning prevention plates 30, the load applied to the sleeve 25C is dispersed to plural leaning prevention plates 30 and thereby stabilization can be improved.

FIG. 12 is a view showing a fourth example of a sleeve provided in the optical receptacle of the embodiment of the present invention, FIG. 12-(A) is a left side view, and FIG. 12-(B) is a front view. As shown in FIG. 12, a leaning prevention ring 31 may be provided on the sleeve main body 26 having the cylindrical-shaped configuration and an end surface 31a of the leaning prevention ring 31 may come in contact with the supporting surface 29A. This structure is equivalent to a structure where the number of provided leaning prevention plates 30 is large and the most stable against the external force.

The present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention.

This patent application is based on Japanese Priority Patent Application No. 2006-178477 filed on Jun. 28, 2006, the entire contents of which are hereby incorporated by reference.

Claims

1. An optical receptacle, comprising: a fiber stub; anda sleeve having a sleeve main body where the fiber stub is installed, the sleeve supported by a supporting surface of a supporting member;wherein a leaning prevention member is provided at the sleeve;the leaning prevention member is formed so as to extend outward from the sleeve main body;the leaning prevention member prevents leaning of the sleeve main body from the supporting surface by coming in contact with the supporting surface; andan internal diameter of the sleeve main body is greater than an external diameter of a plug ferrule inserted in the sleeve main body several μm.

2. The optical receptacle as claimed in claim 1, wherein the leaning prevention member is a plate-shaped member having a structure where at least three portions extend in a radial manner from the center of the sleeve main body having a cylindrical-shaped configuration and an end part comes in contact with the supporting surface.

3. The optical receptacle as claimed in claim 2, wherein a length in a longitudinal direction of the plate-shaped member is shorter than a length between a contact surface of the fiber stub and the supporting surface.

4. The optical receptacle as claimed in claim 1, wherein the leaning prevention member is provided on the sleeve main body having a cylindrical-shaped configuration in a ring shape; andan end surface of the leaning prevention member comes in contact with the supporting surface.

5. The optical receptacle as claimed in claim 1, wherein a slit forming part extending in a longitudinal direction is formed in the sleeve main body.

6. A sleeve provided in an optical receptacle where a fiber stub is provided, the sleeve being supported by a supporting surface of a supporting member, the sleeve comprising: a sleeve main body where the fiber stub is installed; anda leaning prevention member formed so as to extend outward from the sleeve main body, the leaning prevention member being configured to prevent leaning of the sleeve main body from the supporting surface by coming in contact with the supporting surface,wherein an internal diameter of the sleeve main body is greater than an external diameter of a plug ferrule inserted in the sleeve main body by several μm.

7. The sleeve as claimed in claim 6, wherein the leaning prevention member is a plate-shaped member having a structure where at least three portions extend in a radial manner from the center of the sleeve main body having a cylindrical-shaped configuration and an end part comes in contact with the supporting surface.

8. The sleeve as claimed in claim 7, wherein a length in a longitudinal direction of the plate-shaped member is shorter than a length between a contact surface of the fiber stub and the supporting surface.

9. The sleeve as claimed in claim 6, wherein the leaning prevention member is provided on the sleeve main body having a cylindrical-shaped configuration in a ring shape; andan end surface of the leaning prevention member comes in contact with the supporting surface.

10. The sleeve as claimed in claim 6, wherein a slit forming part extending in a longitudinal direction is formed in the sleeve main body.

11. An optical receptacle comprising: a sleeve having a sleeve main body where a fiber stub is installed,wherein an internal diameter of the sleeve main body is greater than an external diameter of a plug ferrule inserted in the sleeve main body by several μm.