1. Field of the Invention
The present invention relates generally to an optical connector, and more particularly to an optical connector as an optical plug used for a multiplex transmission circuit, for example, of a vehicle such as motor vehicle and to an assembly method of the optical plug.
2. Description of the Related Art
An optical connector is used to connect an optical fiber cable with a transmitter, a receiver, or another optical fiber cable constituting the above multiplex transmission circuit.
Because the optical fiber cable is weak in extreme bending and distortion, the optical fiber cable is usually led out of the optical connector straight. In a circumstance, like in a vehicle, that various electric equipment and wiring harnesses are thickly arranged, however, the optical fiber cable is often led out of the optical connector, while being curved in a minimum bending radius.
Though an optical connector disclosed in Japanese Patent Application Laid-open No. 10-78534 is known as an optical connector with a curved optical fiber cable, an optical connector 1 shown in FIG. 11 is used.
Hereinafter, the above optical connector 1 will be described, referring to FIG. 11. The optical connector 1 consists of a receptacle (not illustrated) and an optical plug 2 to be coupled with the receptacle. The optical plug 2 has ferrule assemblies 3, a plug housing 4, and a spring cap 5.
The ferrule assembly 3 is formed by connecting a ferrule 8 on the end of an optical fiber cable 7 on which a compression spring 6 is arranged. One end of the compression spring 6 abuts against the ferrule 8.
The plug housing 4 couples with a coupling portion (not illustrated) of the receptacle and has longitudinal accommodating chambers 9 to accommodate the respective ferrule assemblies 3. And, a claw-like engaging projection 10 is protrusively-provided on each sidewall of the plug housing 4. (one engaging projection 10 is illustrated.)
The spring cap 5 consists of a lower spring cap 11 and an upper spring cap 12, which lower spring cap 11 engages the rear of the plug housing 4.
The lower spring cap 11 has an engaging portion 13 to engage the plug housing 4 and a leading-out direction restricting portion 14 to restrict the direction of the optical fiber cables. The engaging portion 13 is provided with four-sided holes 15 to engage the engaging projections 10 and fiber leading-out portions 16 against which the other ends of the respective compression springs 6 abut and through which the optical fiber cables 7 pass.
The leading-out direction restricting portion 14 curves the optical fiber cables 7 by about 90xc2x0 for leading them in a lateral direction. The curved optical fiber cables 7 are led outside out of an opening portion 17 provided on the leading-out direction restricting portion 14. A sidewall of the leading-out direction restricting portion 14, at a side of a smaller radius of curvature, is provided with a supporting surface 18 curving in a circular-arc. And, another sidewall of the leading-out direction restricting portion 14, at a side of a large radius of curvature, is provided with engaging projections 19 and ribs 20 to engage the upper spring cap 12 and is formed to make the optical fiber cables 7 curve.
The upper spring cap 12 is formed to cover the leading-out direction restricting portion 14 of the lower spring cap 11. And, a sidewall 21 of the upper spring cap 12 is provided with four-sided holes 22 to engage the above engaging projections 19 and guide grooves 23 to receive the above ribs 20.
With respect to the above-described optical connector 1, however, work efficiency for assembly following the ferrule assemblies 3 having been accommodated in the accommodating chambers 9 of the plug housing 4 is not good.
That is, it is not easy to engage the lower spring cap 11, in a state of accommodating the curved optical fiber cables 7 in its leading-out direction restricting portion 14, with the rear of the plug housing 4, which causes poor work efficiency.
More specifically, after having accommodated the optical fiber cables 7 in the leading-out direction restricting portion 14, the optical fiber cables 7 are held, the lower spring cap 11 is engaged with the plug housing 4, and the upper spring cap 12 is coupled with the lower spring cap 11.
Also, when the lower spring cap 11 is engaged with the plug housing 4, because the lower spring cap 11 has to be pushed against the compression spring 6 so that the holes 15 engage the engaging projections 10, the curved optical fiber cables 7 are apt to be moved due to the above movement of the lower spring cap 11 in the leading-out direction restricting portion 14, which would require repeated curving work for the cables 7.
The above poor work efficiency causes to increase the assembling cost.
In view of the foregoing, an object of the present invention is to provide an optical connector and an assembly method of an optical connector as an optical plug, wherein the assembly work efficiency is improved and the assembly cost is reduced.
In order to achieve the above-described object, as a first aspect of the present invention, an optical connector as an optical plug comprises: an optical fiber cable; a ferrule connected to an end of the optical fiber cable and constructing a ferrule assembly along with the optical fiber cable; a spring arranged over the optical fiber cable, an end of the spring pressing the ferrule; a plug housing to accommodate the ferrule assembly and the spring; and a spring cap to be connected to the plug housing for supporting another end of the spring, wherein the spring cap has a lower spring cap and an upper spring cap to couple with the lower spring cap, at least one of the spring caps engaging the plug housing, and the one of the spring caps has both of a straight path to straightly lead out the optical fiber cable in an axial direction of the ferrule and a curved path to curvingly lead out the optical fiber cable.
As a second aspect of the present invention, in the structure with the above first aspect, a closing portion to close a leading-out portion for the optical fiber cable arranged in the straight path is formed on the other of the spring caps.
As a third aspect of the present invention, in the structure with either one of the above first and second aspects, the curved path has a fiber cable fixing portion to check restoration of the optical fiber cable being in a curved state and to define the curved path from the straight path.
As a fourth aspect of the present invention, an assembly method of an optical plug, comprising a ferrule assembly, a plug housing, and a spring cap having a lower spring cap and an upper spring cap to couple with the lower spring cap, at least one of the spring caps engaging the plug housing and having a straight path and a curved path both for the optical fiber cable, comprises the steps of: a fiber terminal end treatment step for forming the ferrule assembly by putting a compression spring over the optical fiber cable and by connecting the ferrule to an end of the optical fiber cable; a ferrule assembly accommodation step for accommodating the ferrule assembly in the plug housing; a first spring cap assembly step for accommodating the optical fiber cable led out of the plug housing in the straight path straightly in an axial direction of the ferrule and engaging the one of the spring caps with the plug housing; a second spring cap assembly step for shifting the optical fiber cable from the straight path to the curved path; and a third spring cap assembly step for coupling the one of the spring caps with the other of the spring caps.
According to the above-described structure of the present invention, the following advantages are provided.
(1) Because the straight path and the curved path for the optical fiber cables are provided at least in either one, which engages the plug housing, of the upper spring cap and the lower spring cap, the spring cap having the paths can be engaged with the plug housing in a state that the optical fiber cables led out of the plug housing remain straight in the straight path. After the spring cap having the paths has been engaged with the plug housing, the straight optical fiber cables in the straight path are shifted into the curved path and then the other spring cap is coupled to the previous spring cap, whereby the assembly of the optical plug can be completed easily. Accordingly, though the present optical plug (i.e. the optical connector) has the same number of components as the prior art one, the assembly work efficiency can be improved by means of the above-described path change, thereby reducing the assembling cost.
(2) The assembly work efficiency can be improved and the assembling cost can be reduced, while remaining the appearance and the function unchanged.
(3) The paths can be clearly defined each other during assembly and the curved optical fiber cables are supported or fixed by the fiber cable fixing portion thereby to easily couple the spring caps, thereby further improving the assembly work efficiency.
(4) Though the present optical plug (i.e. the optical connector) has the same number of components as the prior art one, the assembly work efficiency can be improved by means of the above-described path change, thereby reducing the assembling cost.