Extracting touch data that represents one or more objects on a touch surface

摘要

A touch-sensing apparatus is based on frustrated total internal reflection (FTIR). The apparatus comprises a panel, in which sheets of light are propagated by internal reflection between a touch surface and an opposite surface. A light sensor arrangement is optically connected to the panel to measure transmitted light energy on detection lines across the touch surface. Each detection line represents a light path across the touch surface from a light source to a light sensor. An object that touches the touch surface will frustrate the propagating light and cause a local attenuation among the detection lines. A data processor is connected to the light sensor arrangement and configured to execute a process for extracting touch-related data.

主权项

1. A method in a touch-sensing apparatus, said touch-sensing apparatus including a light transmissive panel that defines a touch surface and an opposite surface, a light source arrangement for providing sheets of light inside the light transmissive panel, wherein said sheets of light include light that propagates by internal reflection between the touch surface and the opposite surface, and a light sensor arrangement for measuring transmitted light energy, wherein the light source arrangement and the light sensor arrangement are arranged to define a grid of detection lines on the touch surface, each detection line representing a light path across the touch surface from the light source arrangement to the light sensor arrangement, and wherein the touch-sensing apparatus is configured such that one or more objects touching the touch surface causes a local attenuation in said grid of detection lines, said method comprising:
obtaining an output vector containing signal values indicative of light received by the light sensor arrangement on a set of detection lines; representing a two-dimensional attenuation field on the touch surface by at least one two-dimensional basis function, wherein the or each basis function defines an attenuation strength within the two-dimensional extent of the or each respective basis function, and the or each basis function overlaps with at least one other basis function; and calculating an estimated attenuation field, based on a mapping of said set of detection lines to the or each basis function, by optimizing at least one of the attenuation strength and the location of the or each basis function such that the estimated attenuation field yields the output vector; and processing the estimated attenuation field for extraction of touch data relating to said one or more objects.