US4103289A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Calculator theft prevention device
Assignee: Individual
•
Filing: 1976-04-27
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Granted: 1978-07-25
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Expires: 1996-04-27
Abstract
Abstract A security device for an electronic calculator consists of an electronic circuit within the calculator which permits operation of the calculator only after the operator has correctly operated a predetermined sequence of keys. The circuit is connected to the sense and the digit drive lines of an electronic calculator having an electronically scanned keyboard. The circuit includes a key selection matrix, a valid actuation discriminator logic, an actuation sequence counter, an alarm inhibiter and an alarm which disables the proper functioning of the calculator.
Inventors
- 👤 Steven Kolber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:26
CPC Classifications
G; G06; G06F; G06F21/00; G06F21/70; G06F21/82; G06F21/83
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
145 words
A security device for a keyboard electronic instrument, in which instrument the keyboard has a plurality of cross-points and a plurality of sense lines and a plurality of digit lines connected thereto, said instrument having scanning means to interrogate the cross-points of said keyboard, the security device being connected to at least some of the digit lines and all of the sense lines, said device including a selection matrix connected to a plurality of the said sense lines and a plurality of the said digit lines, valid actuation discriminator means connected to said selection matrix, a sequence counter means connected to said valid actuation discriminator means to provide a sequence of pulses provided by the sequencing of the keys of said keyboard, and alarm means actuated unless inhibited by said validity means, said alarm means producing a pulse train to cause malfunction of said instrument.
Claim 2
Dependent Claim
145 words
A security device for a keyboard electronic instrument, in which instrument the keyboard has a plurality of cross-points and a plurality of sense lines and a plurality of digit lines connected thereto, said instrument having scanning means to interrogate the cross-points of said keyboard, the security device being connected to at least some of the digit lines and all of the sense lines, said device including a selection matrix connected to a plurality of the said sense lines and a plurality of the said digit lines, valid actuation discriminator means connected to said selection matrix, a sequence counter means connected to said valid actuation discriminator means to provide a sequence of pulses provided by the sequencing of the keys of said keyboard, and alarm means actuated unless inhibited by said validity means, said alarm means producing a pulse train to cause malfunction of said instrument.
Claim 3
Dependent Claim
47 words
A security device as in claim 1 wherein said selection matrix includes a matrix of connectors in which only a few of the possible connections are connected to provide a preselected output, those few connections corresponding to keys selected to be the unlocking keys of the instrument.
Claim 4
Dependent Claim
19 words
A security device as in claim 1 wherein said selection matrix is connected to all of said sense lines.
Claim 5
Dependent Claim
40 words
A security device as in claim 1 wherein said valid actuation discriminator means includes a plurality of "and" gates, each of said "and" gates being connected to one of said few connections and to one output of said sequence counter.
Claim 6
Dependent Claim
25 words
An instrument as in claim 1 and including a calculator chip having bit storage registers wherein said alarm means is connected to clear said registers.
Claim 7
Dependent Claim
37 words
A security device as in claim 1 and further including a shift register connected to at least one of said sense lines to provide a check that the key has been closed for a pre-selected time period.
Claim 8
Dependent Claim
16 words
A security device as in claim 6 and further including means to prevent multiple key entry.
Claim 9
Dependent Claim
41 words
A security device as in claim 1 wherein said keyboard electronic instrument is a solid-state electronic calculator and said pulse train causes the malfunction which is a useless display of numbers resulting from pseudo-key actuations duplicating the effect of key closures.
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) | 1981-07-24 | 1982-01-23 | 1982-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-24 | 1986-01-23 | 1986-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-24 | 1990-01-23 | 1990-07-25 | $7700.00 | Window Closed / Lapsed |