Touch sensing device
AssigneeFujitsu Limited
InventorsHisashi Yamaguchi, Toru Asano, Kazuhiro Takahara, Keizo Kurahashi, Shizuo Andoh
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Abstract
A new type touch sensing device comprises a touch panel with a plurality of transparent touch electrodes, a LC parallel resonant circuit connected to the touch electrode and an oscillation circuit. The LC resonant circuit has a resonant point on a same frequency with the oscillation frequency of the oscillation circuit. The touch/non-touch condition to the touch electrode is detected as a change of voltage value at the connecting point of the LC resonant circuit and touch electrode with an increased ON-OFF ratio.
Claims2
A touch sensing device for detecting a touched condition of a touch electrode wherein the capacitance of said touch electrode changes when said touch electrode is touched and not touched, said device comprising:
- (a) an oscillator means for generating a constant frequency AC signal;
- (b) parallel resonant circuit means, said resonant circuit means being tuned to the frequency of said oscillator means;
- (c) impedance circuit means coupling said oscillator means to said resonant circuit means;
- (d) an impedance element connected in series with said resonant circuit means, said impedance element also being connected to said touch electrode;
- (e) wherein the touched and not touched conditions of said touch electrode is detected as a change in voltage at the connecting point of said impedance circuit means and said resonant circuit means.
Dependencies are inferred from the claim text.