Detecting the locations of a plurality of objects on a touch surface

摘要

An apparatus is controlled to detect locations of a plurality of objects on a touch surface of a panel. An input scanner arrangement introduces at least three beams of radiation into the panel for propagation by internal reflection, and sweeps the beams inside the panel across a sensing area, preferably in at least two different principal directions. At least one radiation detector is arranged to receive the beams from the input scanner arrangement while they are swept across the sensing area. A data processor is connected to the radiation detector(s) and operated to identify the locations based on an attenuation of the beams caused by the objects touching the touch surface within the sensing area, the attenuation being identifiable from an output signal of the radiation detector(s). Each output signal may be further processed to generate a transmission signal, by dividing the output signal by a background signal which represents the output signal without any object on the touch surface.

主权项

1. A method for detecting a location of at least one object on a touch surface on a radiation transmissive panel, said method comprising:
obtaining at least two output signals from a detection arrangement which is optically coupled to one or more elongate outcoupling sites on said radiation transmissive panel, each of said one or more elongate outcoupling sites extending along a length of an edge of said radiation transmissive panel, each of said one or more elongate outcoupling sites being configured to optically couple radiation propagating through said radiation transmissive panel out of said radiation transmissive panel to said detection arrangement, the radiation propagating through said radiation transmissive panel by internal reflection between the touch surface and an opposite surface of said radiation transmissive panel, said at least two output signals representing a respective spatial distribution of said radiation along said one or more elongate outcoupling sites; generating at least two transmission signals, wherein said generating includes dividing said at least two output signals by a background signal; and identifying said location based on peaks in said at least two transmission signals.