Optical EngineeringScalable highly-sensitive optical touch keyboards
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Due to the need of a highly sensitive touch keyboard for the disabled, we propose no-moving-parts optical touch keyboard architectures based on the use of light splitting and blocking concepts. Light splitting via a fiber optic splitter is also introduced to reduce the precise optical alignment technique required in our free-space-based optical touch keyboard. Several key features are accomplished, including high switch sensitivity, scalability, ease of implementation, and low electrical power consumption. Our free-space-based 5×4 optical touch keyboard prototype shows a key activating time of 19 ms for a keyboard scanning rate of 180 ms per 20 keys. Our optical touch keyboard prototype is also tested in more than 4000 key operations under environmental illuminations from a typical 400 lux to a high 3000 lux without keyboard failure, thus promising good use in practice.