Touch sensing device
First Claim
1. A touch sensing device having a plurality of touch sensing electrodes defining positions to be sensed and having an impedance between corresponding ones of the electrodes, said device comprising:
- a touch sensing circuit to which said touch sensing electrodes are sequentially and selectively connected, said touch sensing circuit including-an oscillator for supplying an AC signal to said selected touch sensing electrode; and
a buffer circuit means for isolating the AC signal from the selected touch electrode and for supplying the AC signal to the non-selected touch sensing electrodes, so that the non-selected touch sensing electrodes are clampled to substantially the same potential as that of the selected electrodes and an impedance between the adjacent touch electrodes is negligible.
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Accused Products
Abstract
A transparent finger touch sensing device having a sensing circuit including a resonator for sensing a touch an oscillator for supplying an AC signal to the resonator, a buffer circuit for isolating an output of the oscillator from each selected touch electrodes and for supplying the oscillator output to the remaining non-selected touch electrodes when the sensing circuit is sequentially connected to the touch sensing electrodes, is disclosed. Thereby, the selected touch electrodes and non-selected touch electrodes are maintained at a voltage having the same phase and the same level and the inter-electrode impedance is substantially negligible.
54 Citations
5 Claims
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1. A touch sensing device having a plurality of touch sensing electrodes defining positions to be sensed and having an impedance between corresponding ones of the electrodes, said device comprising:
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a touch sensing circuit to which said touch sensing electrodes are sequentially and selectively connected, said touch sensing circuit including- an oscillator for supplying an AC signal to said selected touch sensing electrode; and a buffer circuit means for isolating the AC signal from the selected touch electrode and for supplying the AC signal to the non-selected touch sensing electrodes, so that the non-selected touch sensing electrodes are clampled to substantially the same potential as that of the selected electrodes and an impedance between the adjacent touch electrodes is negligible. - View Dependent Claims (2)
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3. A touch sensing device for a touch keyboard having electrodes arranged to define key positions, each electrode having a selected and a non-selected state, said device comprising:
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oscillator means for generating an AC signal; selection means, operatively connected to said oscillator means, for placing in the selected state, desired ones of the electrodes and for applying said AC signal to said selected electrodes; and buffer means, operatively connected to said oscillator means and to said selection means, for amplifying said AC signal and for providing said amplified signal to the non-selected electrodes. - View Dependent Claims (4, 5)
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Specification