Optical waveguides – Integrated optical circuit
Reexamination Certificate
2000-01-10
2001-01-30
Ullah, Akm E. (Department: 2874)
Optical waveguides
Integrated optical circuit
Reexamination Certificate
active
06181842
ABSTRACT:
TECHNICAL FIELD
This invention relates to waveguide arrays for digitizing user input positions, and more particularly such arrays with collimating optics integrated into a one piece structure with the arrays.
BACKGROUND
Heretofore digitizing arrays have employed external collimating optics for focusing an array of light beams propagating from a send waveguide array to a receive array. The collimating optics were typically an array of collimating lenses which was secured to the send array during assembly. The collimating array was not an integral part of the waveguide array, and did not have a precisely defined position relative to the waveguides. During assembly, the optics were manually (or mechanically) placed next to the waveguides for securing. Precise optical alignment under such unrestrained conditions was difficult resulting in misalignment. This assembly misalignment introduced a corresponding indexing error between the waveguides and the optics which degraded the collimation causing limited the position resolution of the light beams. However, the prior art light beam density was sufficient for selecting icon symbols from a displayed menu.
SUMMARY
It is therefore an object of this invention to provide a waveguide array for a position digitizer with optics integrated into a one piece structure with the waveguides defining a precise and fixed position relationship therebetween.
It is another object of this invention to provide such a structure in which the optics have a predetermined template position relationship with the waveguides.
It is a further object of this invention to provide such a structure in which the optics are physically embedded in the waveguide support substrate and do not require assembly.
It is a further object of this invention to provide such a structure in which the optics are in improved alignment with the waveguides.
It is a further object of this invention to provide such a structure in which the end of each waveguide is contoured to cooperate with the optics.
It is a further object of this invention to provide such a structure in which the send light spreads prior to collimation.
It is a further object of this invention to provide such a structure in which the digitizing light beams have improved collimation and/or collection.
It is a further object of this invention to provide such a structure in which the light beams have reduced cross-talk therebetween.
It is a further object of this invention to provide such a structure in which the detected light has a higher signal to noise ratio.
It is a further object of this invention to provide such a structure in which detection cells have a higher linear density than the receive waveguides.
Briefly, these and other objects of the present invention are accomplished by providing a send substrate and an opposed receive substrate spaced from the send substrate defining a free space region therebetween. Send waveguides are embedded in the send substrate. Each send waveguide has a free space end proximate the free space region and a light source end, and guides constrained send light from the source end to the space end. The space ends of the send waveguides form a parallel send array for sending a generally parallel array of unconstrained send light beams across the free space region to the receive substrate. Corresponding receive waveguides are embedded in the receive substrate. Each receive waveguide has a free space end proximate the free space region and a light detect end, and guides constrained receive light from the space end to the detect end. The space ends of the receive waveguides form a parallel receive array, and are in optical association with the corresponding send waveguide of the send array. Each receive waveguide receives at least a portion of the light beam from the corresponding send waveguide, which becomes constrained receive light in that receive waveguide. An array of send optical systems are embedded in the send substrate between the send array and the free space region. One send optical system is in an optically aligned fixed position relative to each send waveguide. The optical system enhances the collimation of the constrained send light from that aligned send waveguide, for enhancing the collimation of the light beams crossing the free space region. Thus, a higher portion of the light beam is received by the corresponding receive waveguide.
REFERENCES:
patent: 4848879 (1989-07-01), Nishimura et al.
patent: 5119448 (1992-06-01), Schaefer et al.
patent: 5465265 (1995-11-01), Ota
patent: 5485318 (1996-01-01), Lebby et al.
patent: 5835458 (1998-11-01), Bischel et al.
Francis Daniel A.
Graham David S.
Hentzel Paul
Poa Sana, Inc.
Ullah Akm E.
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