US3668697A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noncontacting keyboard
Assignee: HP Inc
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Filing: 1970-09-24
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Granted: 1972-06-06
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Expires: 1990-09-24
Abstract
Abstract An array of keys is suspended over an array of transformers. The transformer secondaries are series connected together and the primaries are arranged in series connected pairs, the transformers of each pair being oppositely poled. A ferrite core is attached to each key. The primary pairs are electrically energized one at a time by a scanner, and the series connected secondaries are connected to a comparator. When a key is depressed the ferrite core on the key changes the mutual inductance between the primary and secondary of the corresponding transformer, causing the comparator to register a depressed key. An information output available from the scanner and comparator tells which key is depressed, and the scanner halts when a key is depressed to prevent an erroneous output due to more than one simultaneously depressed key.
Inventors
- 👤 David S Cochran
- 👤 Glenn E Mcghee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:45
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/965; H03K17/97; H03K17/972; H03M; H03M11/00; H03M11/20
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
292 words
A noncontacting keyboard comprising: an array of coreless transformers, each transformer having a first and a corresponding second winding, the first windings being series connected in one or more first groups and the second windings being series connected in one or more second groups, each first group containing an integral number of pairs of the first windings, and there being at least said integral number of second groups; energizing means connected to the first groups for applying signals thereto, the magnitude and polarity of the mutual inductance between the pairs of first windings in a first group and the corresponding second windings being selected for cancellatioN of signals induced on said corresponding second windings in response to signals on the first windings; an array of buttons arranged in a one to one correspondence with and physically proximate to the array of transformers, a pair of buttons corresponding to a pair of first windings and said buttons being supported for movement with respect to the transformers; magnetic flux changing means attached to each button for changing the mutual inductance between the first and second windings in one of the transformers when the button corresponding to that transformer is moved to change the proximity of the magnetic flux changing means with respect to the transformer; and circuit means connected to the second groups for giving an electrical indication of which button was moved, said circuit means including comparator circuitry for determining the polarity of a signal caused by the change in mutual inductance between the first and second windings of a transformer to identify which button in a pair buttons was moved and logic means responsive to the comparator circuitry for storing a digital indication of the polarity of the change in mutual inductance.
Claim 2
Dependent Claim
292 words
A noncontacting keyboard comprising: an array of coreless transformers, each transformer having a first and a corresponding second winding, the first windings being series connected in one or more first groups and the second windings being series connected in one or more second groups, each first group containing an integral number of pairs of the first windings, and there being at least said integral number of second groups; energizing means connected to the first groups for applying signals thereto, the magnitude and polarity of the mutual inductance between the pairs of first windings in a first group and the corresponding second windings being selected for cancellatioN of signals induced on said corresponding second windings in response to signals on the first windings; an array of buttons arranged in a one to one correspondence with and physically proximate to the array of transformers, a pair of buttons corresponding to a pair of first windings and said buttons being supported for movement with respect to the transformers; magnetic flux changing means attached to each button for changing the mutual inductance between the first and second windings in one of the transformers when the button corresponding to that transformer is moved to change the proximity of the magnetic flux changing means with respect to the transformer; and circuit means connected to the second groups for giving an electrical indication of which button was moved, said circuit means including comparator circuitry for determining the polarity of a signal caused by the change in mutual inductance between the first and second windings of a transformer to identify which button in a pair buttons was moved and logic means responsive to the comparator circuitry for storing a digital indication of the polarity of the change in mutual inductance.
Claim 3
Dependent Claim
38 words
A noncontacting keyboard as in claim 1 wherein the energizing means includes a signal source and scanning means for connecting one of said integral number of pairs of the first windings at a time to the signal source.
Claim 4
Dependent Claim
32 words
A noncontacting keyboard as in claim 2 wherein the circuit means includes latching circuitry to halt the scanning means when the circuit means gives an electrical indication that a button was moved.
Claim 5
Dependent Claim
19 words
A noncontacting keyboard as in claim 2 wherein the magnetic flux changing means is a piece of ferrimagnetic material.
Claim 6
Dependent Claim
18 words
A noncontacting keyboard as in claim 2 wherein the magnetic flux changing means is a piece of metal.
Claim 7
Dependent Claim
13 words
A noncontacting keyboard as in claim 2 wherein said integral number is one.
Claim 8
Dependent Claim
37 words
A noncontacting keyboard as in claim 2 wherein the circuit means includes digital coding means responsive to the comparator circuitry and the scanning means, the digital coding means giving a digital output corresponding to the button moved.
Claim 9
Dependent Claim
43 words
A noncontacting keyboard as in claim 7 including latching means for comparing the digital output corresponding to successive scans of the scanning means, the latching means giving an output in response to the same button being moved during at least two successive scans.
Claim 10
Dependent Claim
51 words
A noncontacting keyboard as in claim 5 wherein the transformers are metal foil spirals on a printed circuit board, the buttons are supported above the printed circuit board by spring means, and a button is actuated by depressing it, bringing said piece of metal in closer proximity to the corresponding transformer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |