| 摘要 |
An apparatus is operated to determine a location of at least one object on a touch surface of a light transmissive panel. An illumination arrangement in the apparatus is operated to introduce beams of radiation into the panel for propagation by internal reflection between the touch surface and the opposite surface, and to sweep each beam along the touch surface within a sensing area. Thereby, the sensing area is illuminated such that an object that touches the touch surface within the sensing area causes at least two beams to be temporarily attenuated. The illumination arrangement is arranged such that each beam, downstream of the sensing area, is swept along one or more elongate outcoupling sites on the panel. At least one light sensor, which is optically coupled to the outcoupling site, is operated to measure the received energy of the beam within the outcoupling site. A data processor is operated to obtain, from the light sensor, an output signal indicative of the received energy of the beam within the outcoupling site as a function of time, and to identify, based on the output signals for the different beams, the location of the object.
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