Patent US3743081A successfully refreshed from Google Patents.
US4777375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intrinsically safe matrix keypad having opto-couplers associated with each row and column of switches
Assignee: Teleco Oilfield Services Inc
•
Filing: 1987-07-29
•
Granted: 1988-10-11
•
Expires: 2007-07-29
Abstract
Abstract A matrix keypad is rendered intrinsically safe by use of a circuit employing a plurality of opto-couplers powered by a single intrinsically safe (IS) barrier.
Inventors
- 👤 Richard C. Bozzuto, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:59
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/795; H03K17/7955; H02; H02H; H02H9/00; H02H9/008
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
66 words
A matrix keypad comprising: keypad means including an array of switches defining at least one column of switches and at least one row of switches; first opto-coupler means associated with each row of switches; second opto-coupler means associated with each column of switches; and a single intrinsically safe barrier means being connected to said first opto-coupler means, said second opto-coupler means and said array of switches.
Claim 2
Dependent Claim
66 words
A matrix keypad comprising: keypad means including an array of switches defining at least one column of switches and at least one row of switches; first opto-coupler means associated with each row of switches; second opto-coupler means associated with each column of switches; and a single intrinsically safe barrier means being connected to said first opto-coupler means, said second opto-coupler means and said array of switches.
Claim 3
Dependent Claim
54 words
The keypad of claim 1 including: keypad scanning logic means communicating with said first opto-coupler means and said second opto-coupler means; and wherein, upon closure of a switch, said first and second opto-coupler means provide said keyboard scanning logic means with the row and column of the closed switch thereby identifying the closed switch.
Claim 4
Dependent Claim
88 words
The keypad of claim 2 wherein said first and second opto-coupler means comprise light emitter means associated with and spaced from light responsive means and wherein: each of said switches in said row and column of switches are connected to said light emitter means of said first opto-coupler means and said light responsive means of said second opto-coupler means; and and wherein said keypad scanning logic means communicates with said light responsive means of said first opto-coupler means and said light emitter means of said second opto-coupler means.
Claim 5
Dependent Claim
31 words
The keypad of claim 3 wherein: said barrier means is connected to said light emitter means of said first opto-coupler means and said light responsive means of said second opto-coupler means.
Claim 6
Dependent Claim
15 words
The keypad of claim 3 wherein said light emitter means comprises: a light emitting diode.
Claim 7
Dependent Claim
15 words
The keypad of claim 3 wherein said light responsive means comprises: a light dependent transistor.
Claim 8
Dependent Claim
15 words
The keypad of claim 5 wherein said light responsive means comprises: a light dependent transistor.
Claim 9
Dependent Claim
16 words
The keypad of claim 2 wherein: said keypad scanning logic means is stored in a computer.
Claim 10
Dependent Claim
16 words
The keypad of claim 3 wherein: said keypad scanning logic means is stored in a computer.
Claim 11
Dependent Claim
41 words
The keypad of claim 3 wherein: said light emitter means of said first opto-coupler means and said light responsive means of said second opto-coupler means and said array of switches and said barrier means are all connected in a first circuit.
Claim 12
Dependent Claim
35 words
The keypad of claim 3 wherein: said light detector means of said first opto-coupler means and said light responsive means of said second opto-coupler means and said barrier means are connected in a second circuit.
Claim 13
Dependent Claim
35 words
The keypad of claim 11 wherein: said light detector means of said first opto-coupler means and said light responsive means of said second opto-coupler means and said barrier means are connected in a second circuit.
References Cited (Backward Citations)
US3562540A
Cited
US3808502A
Cited
US4245650A
Cited
US4311990A
Cited
US4254407A
Cited
US4495421A
Cited
US4362934A
Cited
US4442425A
Cited
US4481423A
Cited
US4417824A
Cited
US4639727A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |