US3750160A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Keyboard with roll-over feature
Assignee: US Philips Corp
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Filing: 1971-11-03
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Granted: 1973-07-31
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Expires: 1991-11-03
Abstract
Abstract In a keyboard two or more keys may be jointly depressed. The keys are successively interrogated and the decision that a ''''new'''' key is interrogated is obtained in that in this event there is no equality with the code data of keys contained in a store. When the keys are released the code data of this key are erased or rendered inoperative.
Inventors
- 👤 J Elzinga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:22
CPC Classifications
H; H03; H03M; H03M11/00; H03M11/20; H04; H04L; H04L25/00; H04L25/38; H04L25/40
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
208 words
A keyboard apparatus, comprising a plurality of keys; commutating means for successively interrogating each of the plurality of keys; a storage device comprising first elements wherein coded data corresponding to a depressed key maybe stored and additional elements wherein coded data corresponding to additional depressed keys may be stored, the storage device being connected as a shift register; detection means responsive to the interrogation of a depressed key for providing a storage signal, the storage device operating in response to the storage signal to store the coded data corresponding to the first interrogated depressed key in the first storage element; comparison means connected to the first storage elements and to the additional storage elements for providing an output gating signal in response to a dissimilarity between the coded words stored in the first storage element and words stored in the additional storage elements; an output terminal; an output device operating in response to the output gating signal for providing the coded word stored in the first storage element to the output terminal; the detection means further providing a shift pulse delayed in time with respect to the storage signal and in advance of the interrogation of the next key in response to the interrogation of a depressed key.
Claim 2
Dependent Claim
208 words
A keyboard apparatus, comprising a plurality of keys; commutating means for successively interrogating each of the plurality of keys; a storage device comprising first elements wherein coded data corresponding to a depressed key maybe stored and additional elements wherein coded data corresponding to additional depressed keys may be stored, the storage device being connected as a shift register; detection means responsive to the interrogation of a depressed key for providing a storage signal, the storage device operating in response to the storage signal to store the coded data corresponding to the first interrogated depressed key in the first storage element; comparison means connected to the first storage elements and to the additional storage elements for providing an output gating signal in response to a dissimilarity between the coded words stored in the first storage element and words stored in the additional storage elements; an output terminal; an output device operating in response to the output gating signal for providing the coded word stored in the first storage element to the output terminal; the detection means further providing a shift pulse delayed in time with respect to the storage signal and in advance of the interrogation of the next key in response to the interrogation of a depressed key.
Claim 3
Dependent Claim
57 words
A keyboard apparatus as claimed in claim 1, further comprising means for cyclically interrogating the successively interrogated keys; a rest key comprising a circuit interrogated once during each interrogation cycle for providing the detection means with a key signal analogous to that of a permanently depressed key; and wherein at least three additional storage elements are provided.
Claim 4
Dependent Claim
58 words
Keyboard apparatus as claimed in claim 1, wherein the commutating means comprises a clock pulse source having at least two different frequencies, the interrogation proceeding at the higher of the two clock pulse frequencies in a rest condition wherein no depressed keys are detected, and operating at the lower clock pulse frequency in response to the storage signal.
Claim 5
Dependent Claim
53 words
Apparatus as claimed in claim 1, further comprising blocking device means operating in response to the depression of a subsequent key within a predetermined time period after the depression of a first key for preventing the output device from providing the coded word corresponding to the second depressed key to the output terminal.
References Cited (Backward Citations)
US3675239A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |