Light-scattering-based high contrast optical touch sensor architectures in transmissive and reflective configurations

Transmissive and reflective optical touch switch architectures based on the use of light scattering are proposed. Key features include high ON/OFF switching ratio, tunable sensitivity, ease of implementation, and no leakage optical beam incident on the user. Experimental proof of concept using a visible laser diode and a plastic Dove prism arranged in the transmissive configuration shows a high 24.4 dB contrast ratio which is a hundred times higher than obtained in the previous total internal reflection-based optical touch switch. In addition, switching response in milliseconds is also investigated for both lifting and sliding the fingertip out of the touching surface of the optical touch switch. Our light scattering-based optical touch switch also supports multiple keystroke operation.

[1]  S. Sheem,et al.  Total internal reflection integrated-optics switch: a theoretical evaluation. , 1978, Applied optics.

[2]  L. Cai,et al.  Interferometer for small-angle measurement based on total internal reflection. , 1998, Applied optics.

[3]  H. Li,et al.  Measurement method of the refractive index of biotissue by total internal reflection. , 1996, Applied optics.

[4]  A. Chaabi,et al.  Acoustic plate mode touch screen , 1991 .

[5]  D. Su,et al.  Refractive-index measurement based on the effects of total internal reflection and the uses of heterodyne interferometry. , 1997, Applied optics.

[6]  H. Harry Asada,et al.  Fingernail touch sensors: spatially distributed measurement and hemodynamic modeling , 2000, Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No.00CH37065).

[7]  Interferometer based on total internal reflection. , 1995, Applied optics.

[8]  A. Wang,et al.  Investigation and application of the frustrated-total-internal-reflection phenomenon in optical fibers. , 1997, Applied optics.

[9]  D. Land,et al.  Theoretical determination of parameters for optimum surface specificity in overlayer attenuated-total-reflection infrared spectroscopy. , 1998, Applied optics.

[10]  Hong Zhang,et al.  Sensing contact with analog resistive technology , 1999, IEEE SMC'99 Conference Proceedings. 1999 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.99CH37028).

[11]  W B Spillman,et al.  Frustrated-total-internal-reflection multimode fiber-optic hydrophone. , 1980, Applied optics.

[12]  J. Schotland,et al.  Three-dimensional total internal reflection microscopy. , 2001, Optics letters.