Patent ID: 7859522
Filing Date: 2010-12-28
Classification: G06F

Abstract:
1. A control method for eliminating noises in a touch panel device including an excitation transducer for exciting a surface acoustic wave upon application of a burst wave and a reception transducer for receiving the surface acoustic wave and converting the same into a reception signal that are arranged at a peripheral portion of a detection area so that a position of an object touching the detection area is detected in accordance with a change in the reception signal in a given single detecting operation during which a plurality of burst waves are applied, the control method comprising: obtaining, in said given single detecting operation, the reception signal comprising a plurality of time domain waveforms each of which corresponding to each of the plurality of burst waves that are applied, said given single detecting operation comprising a plurality of first periods each of which corresponding to a period of each of the plurality of time domain waveforms and a plurality of second periods each of which corresponding to a period between but excluding any two of the plurality of time domain waveforms that are adjacent to each other; comparing, in said given single detecting operation, a difference between one of the time domain waveforms of the reception signal that is allowed to pass through in one of the plurality of first periods and another of the time domain waveforms of the reception signal that is allowed to pass through in another of the plurality of first periods immediately following said one of the plurality of first periods, with a first threshold value, the difference being taken between said one of the time domain waveforms and said another of the time domain waveforms at positions corresponding to each other on a time axis of the time domain waveforms; determining that a first noise is present when said difference exceeds the first threshold value, and determining that the first noise is absent when said difference does not exceed the first threshold value; comparing, in said given single detecting operation, a signal level of the reception signal allowed to pass through in any of the plurality of second periods with a second threshold value; determining that a second noise is present when the signal level of the reception signal allowed to pass through in said any of the plurality of second periods exceeds the second threshold value, and determining that the second noise is absent when the signal level of the reception signal allowed to pass through in all of the plurality of second periods remains at or below the second threshold value; and detecting the position of the object based on the reception signal in said given single detecting operation only if it is determined that both the first noise and the second noise are absent, and skipping detecting the position of the object if it is determined that at least one of the first noise and the second noise is present.