US3716850A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronous detector for monopulse key sampling electronic keyboard
Assignee: International Business Machines Corp
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Filing: 1971-12-21
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Granted: 1973-02-13
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Expires: 1991-12-21
Abstract
Abstract A synchronous detector for monopulse key sampling in electronic keyboards. A variable threshold feedback network prevents false sampling due to signal distortions caused by ''''key bounce,'''' and the like. A single output pulse, in synchronism with and of the same time duration as system clock pulses, is produced at the detector output, in response to the clock pulses being capacitively coupled to its input, upon key depression. The single pulse, used to identify the key depressed via a decode circuit, permits ''''key roll.
Inventors
- 👤 D Fisher
- 👤 P Pleshko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:43
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/01; H03K3/013; H03M; H03M11/00; H03M11/02
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
257 words
A detector circuit for producing a single output pulse in response to each key depression, comprising: triggered gate means having input means and a pair of outputs and responsive at its input means to produce signal indications at one of its pair of outputs when said key is in an undepressed condition and to produce signal indications at the other of its pair of outputs when said key is in a depressed condition; level producing means having two inputs and two outputs with one of its two inputs coupled to the said one of said pair of outputs of said triggered gate means to produce at one of its two outputs in response to said signal indications from said gate means one level change and with the other of its two inputs coupled to the said other of said pair of outputs of said triggered gate means to produce at the other of its two outputs in response to said signal indications from said gate means another level change; feedback means coupling the said one of said two outputs of said level producing means to the said input means of said triggered gate means to prevent triggering of latter due to signal distortions including those from key bounce; and gate means responsive to both the said another level change at the said other of said two outputs of said level producing means and the said signal indications of the said other output of said triggered gate means to produce said single output pulse for each key depression.
Claim 2
Dependent Claim
257 words
A detector circuit for producing a single output pulse in response to each key depression, comprising: triggered gate means having input means and a pair of outputs and responsive at its input means to produce signal indications at one of its pair of outputs when said key is in an undepressed condition and to produce signal indications at the other of its pair of outputs when said key is in a depressed condition; level producing means having two inputs and two outputs with one of its two inputs coupled to the said one of said pair of outputs of said triggered gate means to produce at one of its two outputs in response to said signal indications from said gate means one level change and with the other of its two inputs coupled to the said other of said pair of outputs of said triggered gate means to produce at the other of its two outputs in response to said signal indications from said gate means another level change; feedback means coupling the said one of said two outputs of said level producing means to the said input means of said triggered gate means to prevent triggering of latter due to signal distortions including those from key bounce; and gate means responsive to both the said another level change at the said other of said two outputs of said level producing means and the said signal indications of the said other output of said triggered gate means to produce said single output pulse for each key depression.
Claim 3
Dependent Claim
257 words
A detector circuit for producing a single output pulse in response to each key depression, comprising: triggered gate means having input means and a pair of outputs and responsive at its input means to produce signal indications at one of its pair of outputs when said key is in an undepressed condition and to produce signal indications at the other of its pair of outputs when said key is in a depressed condition; level producing means having two inputs and two outputs with one of its two inputs coupled to the said one of said pair of outputs of said triggered gate means to produce at one of its two outputs in response to said signal indications from said gate means one level change and with the other of its two inputs coupled to the said other of said pair of outputs of said triggered gate means to produce at the other of its two outputs in response to said signal indications from said gate means another level change; feedback means coupling the said one of said two outputs of said level producing means to the said input means of said triggered gate means to prevent triggering of latter due to signal distortions including those from key bounce; and gate means responsive to both the said another level change at the said other of said two outputs of said level producing means and the said signal indications of the said other output of said triggered gate means to produce said single output pulse for each key depression.
Claim 4
Dependent Claim
257 words
A detector circuit for producing a single output pulse in response to each key depression, comprising: triggered gate means having input means and a pair of outputs and responsive at its input means to produce signal indications at one of its pair of outputs when said key is in an undepressed condition and to produce signal indications at the other of its pair of outputs when said key is in a depressed condition; level producing means having two inputs and two outputs with one of its two inputs coupled to the said one of said pair of outputs of said triggered gate means to produce at one of its two outputs in response to said signal indications from said gate means one level change and with the other of its two inputs coupled to the said other of said pair of outputs of said triggered gate means to produce at the other of its two outputs in response to said signal indications from said gate means another level change; feedback means coupling the said one of said two outputs of said level producing means to the said input means of said triggered gate means to prevent triggering of latter due to signal distortions including those from key bounce; and gate means responsive to both the said another level change at the said other of said two outputs of said level producing means and the said signal indications of the said other output of said triggered gate means to produce said single output pulse for each key depression.
Claim 5
Dependent Claim
19 words
The detector as set forth in claim 1 wherein said output pulse is produced in synchronism with clock pulses.
Claim 6
Dependent Claim
22 words
The detector as set forth in claim 2 wherein said output pulse is of the same time duration as said clock pulses.
Claim 7
Dependent Claim
39 words
The detector as set forth in claim 3 wherein the time duration of said one level change from the said one of said two outputs of said level producing means corresponds to the time duration of said key depression.
Claim 8
Dependent Claim
55 words
The detector as set forth in claim 1 wherein the said input means of said triggered gate means comprises two inputs with one of said two inputs continuously coupled to a source of clock signals and with the other of said two inputs coupled to said source of clock signals when said key is depressed.
Claim 9
Dependent Claim
30 words
The detector as set forth in claim 5 wherein the said other of said two inputs is capacitively coupled to said source of clock signals when said key is depressed.
Claim 10
Dependent Claim
40 words
The detector as set forth in claim 6 wherein said input means includes amplifying means coupled between said two inputs and said triggered gate means and wherein said feedback means is coupled to the said other of said two inputs.
Claim 11
Dependent Claim
39 words
The system as set forth in claim 7 wherein the time duration of said one level change from the said one of said two outputs of said level producing means corresponds to the time duration of each said depression.
Claim 12
Dependent Claim
25 words
The system as set forth in claim 8 wherein said triggered gate means, sad level producing means and said gate means comprise NOR logic circuits.
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) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |