Xros, Inc.

Philip Downing

Armand P Neukermans

Timothy G Slater

A beam (38) of electromagnetic radiation deflected by a moving mirror plate (56) of a micromachined scanner (54) produces a two dimensional ('2D') raster (132) on a scanned surface (28) of a block (34). The block (34) is transparent to electro-magnetic radiation of pre-established wavelengths. A radiation inlet-face (36) of the block (34) admits the beam (38) that then impinges on the scanned surface (28) to exit the block (34) through a radiation outlet-face (42). After exiting the block (34), the beam (38) impinges upon a radiation detector (142). Total internal reflection ('TIR') of the beam (38) from the scanned surface (28) at fingerprint valleys and frustration of TIR at fingerprint ridges causes the radiation detector (142) to produce a time-varying electrical signal that represents the fingerprint. The scanned surface (28) may be formed by a patch (302) of resilient material, that may be tinted to be transparent only at the pre-established wavelength of the electro-magnetic radiation.

Compact, simple, 2D raster, image-building fingerprint scanner

Two torsion bars project from a reference member to support at least one plate or frame-shaped first dynamic member for rotation about an axis of the torsion bars. In one embodiment, a frame-shaped first dynamic member and a second pair of torsion bars, oriented non-parallel to the first torsion bars, support a second dynamic member for rotation about an axis that is collinear with the second pair of torsion bars. The vibrational frequency of the principal torsional vibrational mode of the dynamic members are respectively lower by at least 20% than the vibrational frequency of any other vibrational mode thereof. Either an electrostatic or electromagnetic drive means imparts rotary motion to the dynamic members about the collinear torsion bar axis(es). The reference member, the torsion bars and the dynamic member(s) are all monolithically fabricated from a stress-free semiconductor layer of a silicon substrate.

Micromachined members coupled for relative rotation by torsion bars

An improved micromachined structure used for beam scanners, gyroscopes, etc. includes a reference member from which project a first pair of axially aligned torsion bars. A first dynamic member, coupled to and supported from the reference member by the torsion bars, oscillates in one-dimension about the torsion bar's axis. A second dynamic member may be supported from the first dynamic member by a second pair of axially aligned torsion bars for two-dimensional oscillation. The dynamic members respectively exhibit a plurality of vibrational modes each having a frequency and a Q. The improvement includes means for altering a characteristic of the dynamic member's frequency and Q. Coupling between dynamic members permits altering the second dynamic member's frequency and Q by techniques applied to the first dynamic member. Some techniques disclosed also increase oscillation amplitude or reduce driving voltage, and also increase mechanical ruggedness of the structure.

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Saratoga, CA, United States of America

Philip Downing