Patent US4015254A successfully refreshed from Google Patents.
US4015254A
Expired / Lapsed
US
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Keyboard encoding circuit utilizing an A/D converter
Assignee: Motors Liquidation Co
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Filing: 1975-12-04
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Granted: 1977-03-29
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Expires: 1995-12-04
Abstract
Abstract Various switches of a keyboard are connected with a voltage divider network to establish an analog voltage for respective switch closures. The analog voltage is stored on a capacitor and converted by an analog-to-digital converter for input to a computer.
Inventors
- 👤 Earl R. Strandt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:54
CPC Classifications
H; H03; H03M; H03M11/00; H03M11/22; H03M11/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
106 words
A keyboard encoding circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, voltage divider means connecting one side of each of said switches with said source for establishing a different predetermined voltage on the other side of each of said switches in response to closure of respective ones of said switches, storage means connected with the other side of each of said switches for storing the voltage associated with closure of a particular keyboard switch, means for converting the voltage stored to a digital value, and means for clearing said storage means subsequent to conversion of said voltage to said digital value.
Claim 2
Dependent Claim
106 words
A keyboard encoding circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, voltage divider means connecting one side of each of said switches with said source for establishing a different predetermined voltage on the other side of each of said switches in response to closure of respective ones of said switches, storage means connected with the other side of each of said switches for storing the voltage associated with closure of a particular keyboard switch, means for converting the voltage stored to a digital value, and means for clearing said storage means subsequent to conversion of said voltage to said digital value.
Claim 3
Dependent Claim
101 words
A keyboard encoder circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, a plurality of voltage divider resistors connected with said source and establishing a different value at each of a plurality of junctions, means connecting one side of each of said switches with a respective one of said junctions, a capacitor connected with the other side of each of said switches whereby said capacitor is charged to a voltage associated with closure of a particular keyboard switch, means for converting the voltage stored on said capacitor to a digital value, and means for discharging said capacitor.
Claim 4
Dependent Claim
101 words
A keyboard encoder circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, a plurality of voltage divider resistors connected with said source and establishing a different value at each of a plurality of junctions, means connecting one side of each of said switches with a respective one of said junctions, a capacitor connected with the other side of each of said switches whereby said capacitor is charged to a voltage associated with closure of a particular keyboard switch, means for converting the voltage stored on said capacitor to a digital value, and means for discharging said capacitor.
Claim 5
Dependent Claim
152 words
A keyboard encoding circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, a plurality of voltage diveder resistors serially connected across said source for establishing a different voltage at each junction between said resistors, means connecting one side of each of said switches with a respective one of said junctions, a capacitor connected with the other side of each of said switches whereby said capacitor is charged to the voltage established at the junction connected with the particular keyboard switch upon closure of the switch, multiplexing means including a plurality of channels one of which is connected with said capacitor, an analog-to-digital converter connected with the output of said multiplexer, computer means responsive to the output of said analog-to-digital converter and providing a clearing signal in response to conversion of any one of said different voltages, semiconductor switch means responsive to said clearing signal for discharging said capacitor.
Claim 6
Dependent Claim
152 words
A keyboard encoding circuit comprising a plurality of manually actuable keyboard switches, a source of voltage, a plurality of voltage diveder resistors serially connected across said source for establishing a different voltage at each junction between said resistors, means connecting one side of each of said switches with a respective one of said junctions, a capacitor connected with the other side of each of said switches whereby said capacitor is charged to the voltage established at the junction connected with the particular keyboard switch upon closure of the switch, multiplexing means including a plurality of channels one of which is connected with said capacitor, an analog-to-digital converter connected with the output of said multiplexer, computer means responsive to the output of said analog-to-digital converter and providing a clearing signal in response to conversion of any one of said different voltages, semiconductor switch means responsive to said clearing signal for discharging said capacitor.
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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) | 1980-03-28 | 1980-09-27 | 1981-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-28 | 1984-09-27 | 1985-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-28 | 1988-09-27 | 1989-03-29 | $7700.00 | Window Closed / Lapsed |