| 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. In the process, an output vector is generated to contain signal values indicative of light received by the light sensor arrangement on a set of detection lines (step 52), and a two-dimensional attenuation field on the touch surface is represented by one or more two-dimensional basis functions. Each basis function defines an attenuation strength within its two-dimensional extent. The process reconstructs the attenuation field from the output vector (step 54), based on a mapping of the set of detection lines to each basis function. In the reconstruction, an estimated attenuation field is calculated by optimizing at least one of the attenuation strength and the location of each basis function such that the estimated attenuation field yields the output vector. The estimated attenuation field is then processed for extraction of the touch-related data (step 56). |
