US4550310A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Touch sensing device
Assignee: Fujitsu Ltd
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Filing: 1982-10-28
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Granted: 1985-10-29
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Expires: 2002-10-28
Abstract
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.
Inventors
- 👤 Hisashi Yamaguchi
- 👤 Toru Asano
- 👤 Kazuhiro Takahara
- 👤 Keizo Kurahashi
- 👤 Shizuo Andoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:53
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/96; H03K17/962; H03K17/9622; H03K2017/9602; H03K2017/9604; H03K2017/9606; H03K2017/9613
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
130 words
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.
Claim 2
Dependent Claim
130 words
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.
Claim 3
Dependent Claim
17 words
A touch sensing device as set forth in claim 1, wherein said impedance element is an inductor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-28 | 1989-04-29 | 1989-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-28 | 1993-04-29 | 1993-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-28 | 1997-04-29 | 1997-10-29 | $7700.00 | Window Closed / Lapsed |