Multi-touch sensing through frustrated total internal reflection

Abstract

High-resolution, scalable multi-touch sensing display systems and processes based on frustrated total internal reflection employ an optical waveguide that receives light, such as infrared light, that undergoes total internal reflection and an imaging sensor that detects light that escapes the optical waveguide caused by frustration of the total internal reflection due to contact by a user. The optical waveguide when fitted with a compliant surface overlay provides superior sensing performance, as well as other benefits and features. The systems and processes described provide true multi-touch (multi-input) and high-spatial and temporal resolution capability due to the continuous imaging of the frustrated total internal reflection that escapes the entire optical waveguide. Among other features and benefits, the systems and processes are scalable to large installations.

Description

technical field [0001] The present invention relates to techniques for realizing high-resolution multi-touch sensing based on frustrated total internal reflection. Background technique [0002] For a single point of contact, touch sensing is not surprising. One class of touch sensing techniques employs frustrated total internal reflection (FTIR). When light encounters the interface of a medium with a lower refractive index (for example, from glass to air), the light is refracted to a certain extent, and the degree of refraction depends on the incident angle of the light, and beyond a certain critical angle, the light is fully Internal reflection (TIR). Optical fibers, light pipes, and other optical waveguides rely on this phenomenon to efficiently transmit light with very little loss. However, another material at the interface can suppress this total internal reflection and instead cause light to escape the waveguide from there. [0003] Frustrated total internal reflect...

AI Technical Summary

Problems solved by technology

However, these machine vision-based techniques are quite imprecise and cannot determine whether a real touch contact has been made, which disparity may be very annoying to the user

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