Patent US3698531A successfully refreshed from Google Patents.
US3698531A
Expired / Lapsed
US
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Solid state switch
Assignee: Illinois Tool Works Inc
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Filing: 1970-10-26
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Granted: 1972-10-17
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Expires: 1990-10-26
Abstract
Abstract The disclosure describes a keyboard switch having two magnetic cores and a plurality of permanent magnets. The permanent magnets are mounted on a keystem and are movable with respect to the cores to change the flux density in the cores and thus vary the coupling between an AC drive winding and one or more secondary output windings threading each core. Non-magnetic regions separate the permanent magnets and these regions are positioned such that flux changes in one core, resulting from movement of the keystem, are out of phase with the flux changes in the second core. The output signal from one core may be used to strobe or sample the output signals appearing on the secondary windings of the other core. When a plurality of the switches are incorporated in a keyboard, the switches possess an inherent ''''roll-over'''' capability. The disclosure also describes a keyboard circuit employing a plurality of the switches.
Inventors
- 👤 Victor M Bernin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:02
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/965; H03K17/97; B; B41; B41J; B41J5/00; B41J5/08; H03K17/972; H04; H04L; H04L13/00; H04L13/16
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
59 words
A solid state keyboard switch comprising: a data core and a strobe core; primary and secondary windings threading each of said cores; a plurality of magnets for selectively saturating said cores; and, means mounting said magnets for movement relative to said cores, said magnets being positioned relative to said cores to saturate said cores during overlapping intervals of time.
Claim 2
Dependent Claim
59 words
A solid state keyboard switch comprising: a data core and a strobe core; primary and secondary windings threading each of said cores; a plurality of magnets for selectively saturating said cores; and, means mounting said magnets for movement relative to said cores, said magnets being positioned relative to said cores to saturate said cores during overlapping intervals of time.
Claim 3
Dependent Claim
32 words
A solid state keyboard switch as claimed in claim 1 wherein: said mounting means comprises a keystem of magnetic material having first and second legs for carrying said magnets in reciprocating movement.
Claim 4
Dependent Claim
47 words
A solid state keyboard switch as claimed in claim 2 wherein said plurality of magnets includes three pairs of magnets one magnet of eaCh pair being mounted on said first leg of said keystem and the other magnet of each pair being mounted on said second leg.
Claim 5
Dependent Claim
90 words
A solid state keyboard switch as claimed in claim 3 wherein the magnets of said first pair are positioned to saturate said data core when said keystem is at one limit of its movement and saturate said strobe core when said keystem is at its other limit of travel, said magnets of said second pair saturating said data core when said keystem is at said other limit of travel, and said magnets of said third pair saturating said strobe core when said keystem is at said one limit of travel.
Claim 6
Dependent Claim
40 words
A solid state keyboard switch as claimed in claim 4 wherein said magnets are separated from each other by non-magnetic regions whereby said cores become unsaturated as said keystem moves from either of said limits of travel to the other.
Claim 7
Dependent Claim
106 words
A keyboard switch comprising: first and second magnetic cores; a depressable keystem of magnetic material having first and second legs extending on opposite sides of said cores; a plurality of permanent magnets mounted on the legs of said keystem for movement immediately adjacent said cores to thereby selectively concentrate saturating flux in said cores; a plurality of non-magnetic regions separating the permanent magnets on each leg; said magnets and said non-magnetic regions being positioned relative to said cores whereby the flux concentration in one of said cores begins to decrease before the flux concentration in said other core begins to decrease as said keystem is depressed.
Claim 8
Dependent Claim
106 words
A keyboard switch comprising: first and second magnetic cores; a depressable keystem of magnetic material having first and second legs extending on opposite sides of said cores; a plurality of permanent magnets mounted on the legs of said keystem for movement immediately adjacent said cores to thereby selectively concentrate saturating flux in said cores; a plurality of non-magnetic regions separating the permanent magnets on each leg; said magnets and said non-magnetic regions being positioned relative to said cores whereby the flux concentration in one of said cores begins to decrease before the flux concentration in said other core begins to decrease as said keystem is depressed.
Claim 9
Dependent Claim
43 words
A keyboard switch as claimed in claim 6 wherein said magnets and said non-magnetic regions are positioned relative to said cores to saturate both said cores when said keystem is not depressed or when it is depressed to its full extent of travel.
Claim 10
Dependent Claim
25 words
A keyboard switch as claimed in claim 7 and further comprising: a primary winding and at least one secondary winding threading each of said cores.
Claim 11
Dependent Claim
21 words
A keyboard switch as claimed in claim 8 wherein said cores are toroidal cores of a material having low magnetic remanence.
Claim 12
Dependent Claim
163 words
A keyboard comprising: a plurality of key switches each including, a strobe core and a data core; permanent magnet means mounted for movement on a keystem for saturating said cores when said keystem is either fully depressed or not depressed; non-magnetic regions separating said permanent magnet means whereby first said data core and then said strobe core becomes unsaturated as said keystem is depressed; a primary winding threading each of said cores; secondary winding means threading each of said strobe cores; data representing secondary winding means selectively threading said data cores in a coded pattern; means for applying an AC signal to all said primary windings whereby AC signals are produced on said secondary winding means threading the cores of a key as the keystem is depressed; and, means responsive to the AC signals on the secondary winding means of said strobe cores for controlling the transfer of the AC signals on said secondary winding means of said data cores from said keyboard.
Claim 13
Dependent Claim
163 words
A keyboard comprising: a plurality of key switches each including, a strobe core and a data core; permanent magnet means mounted for movement on a keystem for saturating said cores when said keystem is either fully depressed or not depressed; non-magnetic regions separating said permanent magnet means whereby first said data core and then said strobe core becomes unsaturated as said keystem is depressed; a primary winding threading each of said cores; secondary winding means threading each of said strobe cores; data representing secondary winding means selectively threading said data cores in a coded pattern; means for applying an AC signal to all said primary windings whereby AC signals are produced on said secondary winding means threading the cores of a key as the keystem is depressed; and, means responsive to the AC signals on the secondary winding means of said strobe cores for controlling the transfer of the AC signals on said secondary winding means of said data cores from said keyboard.
Claim 14
Dependent Claim
50 words
A keyboard as claimed in claim 10 wherein said means controlling the transfer of signals comprises: AC to DC signal converter means connected to the secondary winding means of said strobe cores; level detector means responsive to said converter means; and, pulse generator means responsive to said level detector means.
Claim 15
Dependent Claim
42 words
A keyboard as claimed in claim 11 and further comprising a further secondary winding means threading said data cores, and gating means responsive to said pulse generator means and said further secondary winding means for producing a strobe pulse controlling said transfer.
Claim 16
Dependent Claim
16 words
A keyboard as claimed in claim 11 wherein said level detector means comprises a Schmitt trigger.
Claim 17
Dependent Claim
24 words
A keyboard as claimed in claim 13 wherein said pulse generator means comprises a monostable multivibrator responsive to poSitive-going output signals from said trigger.
References Cited (Backward Citations)
US2814031A
Cited
US2997703A
Cited
US3129418A
Cited
US3160875A
Cited
US3403386A
Cited
US3363737A
Cited
US3585297A
Cited
US3488613A
Cited
US3495236A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |