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 may be fitted with a compliant surface overlay to greatly improve sensing performance, minimize the affect of contaminants on and damage to the contact surface, to generally extend system life and to provide other benefits. The systems and processes 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 and are well suited for use with rear-projection and other display devices.

Description

REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. patent application No. 60 / 821,325, filed Aug. 3, 2006, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to techniques for enabling high-resolution multi-touch sensing displays based on frustrated total internal reflection. [0004] 2. Description of the Related Art [0005] Touch sensing is commonplace for single points of contact, but it is relatively difficult to sense multiple points of contact simultaneously or “multi-touch sensing.”[0006] One fairly straightforward approach for multi-touch sensing is to utilize multiple discrete sensors, with each sensor sensing a respective point of contact. For example, Tactex Control Inc. has a line of array sensors for use as floor sensors, security devices and other applications. As another example, the publication Lee, S., Buxton, W., and Smith, K. C., “A ...

AI Technical Summary

Benefits of technology

[0018] It is therefore an object of the present invention to provide multi-touch sensing display systems / processes that are relatively simple, inexpensive and scalable for providing high-resolution multi-touch sensing.

[0113] As yet another aspect, the compliant surface overlay includes a component that rejects ambient light of the same wavelengths as the light source, a component that reduces friction at the interaction surface, a component that reduces glare, and a component that provides a comfortable cushion for the user to depress.

Problems solved by technology

Touch sensing is commonplace for single points of contact, but it is relatively difficult to sense multiple points of contact simultaneously or “multi-touch sensing.”

Such systems, while less complex than systems that employ multiple active sensors, still entail numerous electrical connections and thus disadvantageously limit their application to uses that require relatively low resolution (e.g., under 100×100).

Furthermore, such systems are visually opaque and thus require the use of top-projection if to be integrated with a graphic display.

Finally, such systems have had problems with robustness given the feeble nature of the electrical signals they utilize.

However, these video based techniques are quite imprecise and are not able to determine if true touch contact has been made, a disparity that can be quite disturbing to the user.

However, another material at the interface can frustrate this total internal reflection, causing light to escape the waveguide there instead.

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