US3938642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic key touch control
Assignee: Individual
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Filing: 1974-05-17
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Granted: 1976-02-17
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Expires: 1994-05-17
Abstract
Abstract The "touch" or "feel" of a key in a keyboard is controlled by a system of permanent magnets. A first magnet is attached to one end of a key lever and the key lever is pivoted intermediate its ends. A bias spring is provided to normally bias the key lever against a stop. A second magnet is disposed adjacent the path of movement of the first magnet whereby the force required to depress the key lever is dependent upon the spring constant and the interaction of the fields of the magnets. The magnets are positioned such that, as the lever is depressed there is a repelling force between the magnets. Thus, the force required to depress the key is the sum of the spring bias force and the repelling force between the magnets as the first magnet is moved from the home position to a position opposite the second magnet, but is the difference between the spring bias force and the repelling force between the magnets as the key is further depressed.
Inventors
- 👤 Jaap Van Rumpt
- 👤 Joop A. Spermon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:21
CPC Classifications
B; B41; B41J; B41J5/00; B41J5/08; B41J5/26
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
159 words
In a keyboard having a key lever pivoted intermediate its ends, a bias means pivoting said key lever in one direction toward a home position, and a manually depressible key means for pivoting the key lever in the opposite direction away from said home position toward a limit position, the improvement comprising: a first permanent magnet attached to said key lever at one end thereof whereby said magnet travels an arcuate path between first and second positions as said key lever moves between said home and limit positions; and, a second permanent magnet disposed adjacent a point on said arcuate path that is between said first and second positions, said magnets being poled such that the magnetic fields of said magnets create a force that aids said bias means as said first magnet moves toward said point from said first position, and opposes said bias means as said first magnet moves away from said point toward said second position.
Claim 2
Dependent Claim
159 words
In a keyboard having a key lever pivoted intermediate its ends, a bias means pivoting said key lever in one direction toward a home position, and a manually depressible key means for pivoting the key lever in the opposite direction away from said home position toward a limit position, the improvement comprising: a first permanent magnet attached to said key lever at one end thereof whereby said magnet travels an arcuate path between first and second positions as said key lever moves between said home and limit positions; and, a second permanent magnet disposed adjacent a point on said arcuate path that is between said first and second positions, said magnets being poled such that the magnetic fields of said magnets create a force that aids said bias means as said first magnet moves toward said point from said first position, and opposes said bias means as said first magnet moves away from said point toward said second position.
Claim 3
Dependent Claim
92 words
The improvement as claimed in claim 1 wherein said bias means comprises means for exerting on said key lever a pivoting force greater than any exerted thereon by the interaction of said magnetic fields, and wherein the forces of said magnets, acting through said key lever and said key means sequentially feed back to an operator's finger on said key means force feelings of repulsion, null and then propulsion as said key lever is pivoted to thereby move said first magnet from said first position through said point to said second position.
Claim 4
Dependent Claim
14 words
The improvement as claimed in claim 2 wherein said bias means is a spring.
Claim 5
Dependent Claim
26 words
The improvement as claimed in claim 1 wherein each of said magnets includes two poles of one polarity bounding a single pole of the opposite polarity.
Claim 6
Dependent Claim
63 words
The improvement as claimed in claim 1 wherein each of said magnets includes two poles of one polarity bounding a single pole of the opposite polarity, two poles of opposite polarities on one magnet being disposed adjacent two poles on the other magnet when said key lever is in the home position, said adjacent poles on the two magnets being of opposite polarities.
Claim 7
Dependent Claim
60 words
The improvement as claimed in claim 1 wherein each of said magnets comprises two poles of one polarity bounding a center pole of the opposite polarity, said magnets being disposed whereby a pole of one polarity on one magnet is opposite a pole of the same polarity on the other magnet when said key lever is in the limit position.
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) | 1979-02-16 | 1979-08-18 | 1980-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-16 | 1983-08-18 | 1984-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-16 | 1987-08-18 | 1988-02-17 | $7700.00 | Window Closed / Lapsed |