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US08546741B2 Compact optical finger navigation system based on speckles with an optical element including an optical redirection surface 有权
基于具有包括光学重定向表面的光学元件的斑点的紧凑型光学手指导航系统

Compact optical finger navigation system based on speckles with an optical element including an optical redirection surface
Abstract:
An optical finger navigation device includes an image sensor, a tracking surface, and an optical element. The image sensor generates an image representative of light detected at a pixel array that has a pixel pitch which at least partially defines a surface area of a pixel. The tracking surface is approximately parallel to the image sensor. A first distance between and substantially orthogonal to planes of the tracking surface and the image sensor is insufficient under a set of illumination constraints to produce at the image sensor a speckle size above a threshold. The threshold is approximately one order of magnitude less than the pixel pitch. The optical element is interposed between the tracking surface and the image sensor. The optical element includes at least one optical redirection surface to redirect light along an optical path of a second distance between the tracking surface and the image sensor.
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