US3721976A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Keyboard coding and interlock system
Assignee: Omron Systems Inc
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Filing: 1971-02-01
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Granted: 1973-03-20
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Expires: 1991-02-01
Abstract
Abstract A keyboard coding and interlock system wherein the key switches are single contact, two terminal switches coupled to two sides of a logic circuit matrix with substantially fewer input lines than the number of key switches. Pulse means are provided for alternately sampling the input lines on each side of the matrix to determine the condition of the key switches and storage means are provided for producing a binary output indicating the openclosed condition of the switches. A decoding matrix fully decodes the output of the encoding logic matrix.
Inventors
- 👤 H Kuijsten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:50
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/26; H04M1/515
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
154 words
A keyboard coding system comprising a plurality of key circuits each comprising a single contact, two terminal switch, said switches being arranged in a plurality of groups, a logic circuit matrix comprising a plurality of groups of input lines, each of said key switches in a key switch group having a first terminal coupled in common to a particular input line in one of said groups of input lines and having a second terminal coupled to a particular input line in the other group of input lines, the second terminals of the key switches in each group being coupled to different ones of the lines in said second group of input lines, means for sampling each of said groups of input lines in succession to determine the open-closed state of the switches coupled to the input lines in said group, and means in said logic circuit for storing said switch state as binary logic.
Claim 2
Dependent Claim
154 words
A keyboard coding system comprising a plurality of key circuits each comprising a single contact, two terminal switch, said switches being arranged in a plurality of groups, a logic circuit matrix comprising a plurality of groups of input lines, each of said key switches in a key switch group having a first terminal coupled in common to a particular input line in one of said groups of input lines and having a second terminal coupled to a particular input line in the other group of input lines, the second terminals of the key switches in each group being coupled to different ones of the lines in said second group of input lines, means for sampling each of said groups of input lines in succession to determine the open-closed state of the switches coupled to the input lines in said group, and means in said logic circuit for storing said switch state as binary logic.
Claim 3
Dependent Claim
42 words
A keyboard coding system as claimed in claim 1 wherein said sampling means comprises means for coupling on state potential to each input line and means for periodically coupling off state potential to each of said groups of input lines in sequence.
Claim 4
Dependent Claim
68 words
A keyboard coding system as claimed in claim 2 wherein said storage means comprises a plurality of binary storage circuits, one coupled to each separate input line, each storage circuit registering the condition of the key switches coupled via one terminal to its associated input line at the time the input line coupled to said key switch via its other terminal is connected to said off state potential.
Claim 5
Dependent Claim
20 words
A keyboard coding system as claimed in claim 1 wherein said plurality of groups of input lines comprises two groups.
Claim 6
Dependent Claim
92 words
A keyboard coding system as claimed in claim 1 wherein said sampling means comprises a pulse generator for producing a plurality of series of pulses, the pulses in said different series alternating in time, and switch means coupled to each group of input lines operated by said series of pulses to alternately ground said groups of lines in sequence, said storage means being coupled to each input line in each group for registering the ground condition of the line in the other group coupled thereto via the associated key switch when closed.
Claim 7
Dependent Claim
22 words
A keyboard coding system as claimed in claim 5 wherein said storage means comprises a flip-flop circuit coupled to each input line.
Claim 8
Dependent Claim
131 words
A keyboard coding system as claimed in claim 1 wherein said sampling means comprises a source of potential coupled to each of said input lines, a plurality of line switches, one being coupled to each input line and operable to connect ground to its associated line, timing means for operating the line switches coupled to said one group of input lines alternately with the line switches coupled to said other group of input lines whereby ground is coupled from the lines in one of said groups to the lines in the other of said groups via an associated key switch when closed, said storage means coupled to each input line in each group operating to register the ground condition transmitted to its associated input line via an associated closed key switch.
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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |