Optical sensor module

Abstract

An optical waveguide unit having board unit engaging vertical grooves and a board unit having engagement plate portions to be fitted in the vertical grooves and projections are individually produced, and the engagement plate portions and the projections are brought into fitting engagement with the vertical grooves of the optical waveguide unit. At this time, the projections are deformed to accommodate the tolerances of the components, thereby preventing wobbling and warpage of the board unit. Further, the vertical grooves of the optical waveguide unit are provided in proper positions with respect to a light transmission face of a core, and the engagement plate portions of the board unit are provided in proper positions with respect to the optical element. Therefore, the fitting engagement between the vertical grooves and the engagement plate portions permits proper positioning of the light transmission face of the core and the optical element for self-alignment.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 382,219, filed on Sep. 13, 2010, which is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an optical sensor module including an optical waveguide unit and a board unit mounted with an optical element.[0004]2. Description of the Related Art[0005]As shown in FIGS. 13A and 13B, an optical sensor module is produced by individually producing an optical waveguide unit W0 including an under-cladding layer 71, a core 72 and an over-cladding layer73 provided in this order, and a board unit E0 including an optical element 82 mounted on a substrate 81, and then bonding the board unit E0 to an end portion of the optical waveguide unit W0 with an adhesive or the like with the core 72 of the optical waveguide unit W0 in alignment with the optical element 82 of the board unit E0. In FIGS. 13A and 13B, reference numera...

AI Technical Summary

Benefits of technology

[0013]An optical sensor module which has smaller variations in optical coupling loss occurring between a core of an optical waveguide unit and an optical element of a board unit is provided. The optical sensor module includes: an optical waveguide unit; and a board unit coupled to the optical waveguide unit and mounted with an optical element; the optical waveguide unit including an under-cladding layer, a linear core provided on a surface of the under-cladding layer and serving as an optical path, an over-cladding layer covering the core, and board unit engaging portions provided in a pair in proper positions with respect to a light transmission face of the core in laterally opposite portions of the over-cladding layer; the board unit including a substrate, an optical element mounted on a predetermined portion of the substrate, to-be-engaged portions provided in a pair in proper positions with respect to the optical element in the substrate for fitting engagement with the board unit engaging portions, and a projection protruding laterally from at least one of the to-be-engaged portions and less rigid than the substrate; wherein the optical waveguide unit and the board unit are coupled to each other with the to-be-engaged portions and the projection of the board unit in fitting engagement with the engaging portions of the optical waveguide unit with the projection being deformed in abutment with a corresponding one of the engaging portions without warpage of the board unit.

[0014]The optical sensor module reduces vibrations in optical coupling loss occurring between the core of the optical waveguide unit and the optical element of the board unit and minimizes the optical coupling loss in the optical sensor module. The optical sensor module includes the optical waveguide unit and the board unit coupled to each other with the engaging portion of the optical waveguide unit in fitting engagement with the to-be-engaged portion of the board unit as shown in FIGS. 14A and 14B. More specifically, where a projection less rigid than the substrate is provided on at least one of the to-be-engaged portions of the board unit as protruding laterally from the one to-be-engaged portion, the projection deformable in abutment with the engaging portion to accommodate the tolerances of the components and, as a result, the board unit is stably coupled to the optical waveguide unit without the wobbling and the warpage of the board unit, thereby reducing the variations in optical coupling loss.

[0015]In the optical waveguide unit of the inventive optical sensor module, the board unit engaging portions, are located in proper positional relation with respect to the light transmission face of the core. In the board unit, the to-be-engaged portions to be brought into fitting engagement with the engaging portions are located in proper positional relation with respect to the optical element. With the to-be-engaged portions of the board unit in fitting engagement with the engaging portions of the optical waveguide unit, i.e., with the optical waveguide unit coupled to the board unit, self-alignment is established. In this state, the projection of the board unit is deformed in abutment with the engaging portion. Since the tolerances of the components are accommodated by the deformation, the wobbling and the warpage of the board unit are prevented. This reduces the variations in optical coupling loss occurring between the core of the optical waveguide unit and the optical element of the board unit.

[0016]In particular, the engaging portions provided in a pair in the laterally opposite portions of the optical waveguide unit may be vertical grooves extending thicknesswise of the optical waveguide unit, and the vertical grooves may each have a bottom having a width that is not greater than twice a thickness of each of the to-be-engaged portions. Further, the projection of the board unit may be positioned on the bottom of one of the vertical grooves. In this case, the board unit is more stably engaged with the optical waveguide unit. This more reliably prevents the wobbling and the warpage of the board unit.

Problems solved by technology

The alignment utilizing the self-aligning machine is highly accurate, but unsuitable for mass production with the need for labor and time.

However, the optical sensor module often suffers from significant variations in optical coupling loss occurring between the core 42 and the optical element 54.

If Ls>Lc, as shown in FIG. 15C, the board unit E1 wobbles (see an arrow F in FIG. 15C), resulting in inaccurate alignment and hence greater variations in optical coupling loss.

This results in greater variations in optical coupling loss.