Patent ID: 6927384

Claim:
A method of sensing and detecting the presence of an object at a touch pad device having one or more input functions, wherein the touch pad device has a designated interaction area for allowing a user to use the object to interact with the touch pad device for activating said one or more input functions depending on a location of the object, the designated interaction area having a periphery, and wherein the touch pad device has a surrounding area substantially surrounding the periphery of the designated interaction area, said method comprising the steps of: providing in the surrounding area at least one group of optical sensor components including a first light emitter, a second light emitter and a light receiver in the touch pad device at different locations thereof such that the receiver is capable of receiving a first amount of light emitted by the first light emitter and reflected by the object and a second amount of light emitted by the second light emitter and reflected by the object; wherein when the object is present at the touch pad device, causing a change in the first amount of light and the second amount of light, measuring separately the change in the first amount of light and the change in the second amount of light for providing a first signal and a second signal indicative of the respective changes; and determining the location of the object in the designated interaction area in relation to the first light emitter and the second light emitter by comparing the change in the first amount of light and the change in the second amount of light based on the first and second signals, wherein the change in the first amount of light and the second amount of light is an increased amount when the object is present at the touch pad device.