US3803592A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Keyboard and digital circuit therefor
Assignee: Magna Donnelly Corp
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Filing: 1972-09-11
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Granted: 1974-04-09
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Expires: 1992-09-11
Abstract
Abstract In a mechanically operated keyboard employing keys having a multiplicity of electrical switch contacts for providing an encoded electrical output signal corresponding to and uniquely identifying individual key stations; a digital circuit provides a strobe output signal only when all of the electrical switch contacts associated with a given key station have been actuated. In one digital circuit for providing a strobe output signal, each switch contact is assigned a digital weight, and a strobe output is generated only when a predetermined digital count indicative of complete switch closures has occurred. In another digital circuit, the number of closures of switch contacts of a key station are compared in a digital comparator with stored closure signals from a preceding key station actuation to develop a strobe output signal only when the signals are different thereby indicating that a different key station has been actuated or the same key station re-actuated. In still another embodiment of the digital circuit employed with the keyboard, a read-only-memory is employed to detect the number of closures and provides an encoded output for each key station which uniquely identifies the key station and simultaneously produces an enable signal for the generation of a strobe pulse, only when complete contact closures have been effected.
Inventors
- 👤 D Hatley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:39
CPC Classifications
H; H04; H04L; H04L13/00; H04L13/16
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
242 words
A data generating system for providing electrical data signals comprising: a keyboard having a plurality of key stations each representing a symbol for which an electrical data signal is to be generated, each key station comprising an electrical switch having a plurality of fixed electrical contacts which are contacted by a single movable electrical contact, said switch being coupled to a source of operating power and to keyboard output terminals, said fixed contacts of each key station being selected and coupled to said keyboard output terminals such that a unique electrical signal is applied to said output terminals for each key station when actuated to move said movable contact into electrical contact with said fixed contacts associated therewith wherein each of said keyboard output terminals is assigned a predetermined digital weight, and wherein said fixed contacts of each key station are selected to provide an electrical output signal which uniquely identifies each key station and which actuates a plurality of keyboard output terminals that have the same predetermined sum of weighted digital counts for every key station; and electrical circuit means coupled to said keyboard output terminals for detecting and counting the sum of digital weights of the keyboard output terminals actuated and for generating a strobe output pulse only when said predetermined sum is detected indicating that a key station switch has all of the switch contacts associated therewith properly closed to provide an accurate data output signal from said system.
Claim 2
Dependent Claim
242 words
A data generating system for providing electrical data signals comprising: a keyboard having a plurality of key stations each representing a symbol for which an electrical data signal is to be generated, each key station comprising an electrical switch having a plurality of fixed electrical contacts which are contacted by a single movable electrical contact, said switch being coupled to a source of operating power and to keyboard output terminals, said fixed contacts of each key station being selected and coupled to said keyboard output terminals such that a unique electrical signal is applied to said output terminals for each key station when actuated to move said movable contact into electrical contact with said fixed contacts associated therewith wherein each of said keyboard output terminals is assigned a predetermined digital weight, and wherein said fixed contacts of each key station are selected to provide an electrical output signal which uniquely identifies each key station and which actuates a plurality of keyboard output terminals that have the same predetermined sum of weighted digital counts for every key station; and electrical circuit means coupled to said keyboard output terminals for detecting and counting the sum of digital weights of the keyboard output terminals actuated and for generating a strobe output pulse only when said predetermined sum is detected indicating that a key station switch has all of the switch contacts associated therewith properly closed to provide an accurate data output signal from said system.
Claim 3
Dependent Claim
47 words
The system as defined in claim 1 wherein said electrical circuit includes an adder circuit having weighted input terminals coupled to corresponding weighted keyboard output terminals to detect the weighted sum of keyboard terminals actuated and provide output signals at output terminals representative of the detected sum.
Claim 4
Dependent Claim
91 words
The system as defined in claim 2 wherein said electrical circuit further includes a decoding network coupled to said output terminals of said adder network and responsive to signals therefrom to provide a first control signal when said predetermined sum of counts is detected by said adder network indicating that all of the contacts of a key station are closed, a second control signal when none of said switch contacts of a key station are closed, and a third control signal indicating that more than one key station is simultaneously actuated.
Claim 5
Dependent Claim
39 words
The system as defined in claim 3 wherein said electrical circuit further includes a strobe pulse generating circuit coupled to said decoding network and responsive to generate a strobe output pulse only upon receiving a first control signal therefrom.
Claim 6
Dependent Claim
67 words
The system as defined in claim 4 wherein said strobe pulse generating circuit includes an inhibiting circuit coupled to said decoding network and responsive to said second or third control signals to condition said strobe generating circuit to generate a strobe pulse upon receiving a first control signal and inhibiting successive strobe pulse generation until additional second or third control signals are received from said decoding network.
Claim 7
Dependent Claim
48 words
The system as defined in claim 2 wherein each of said keyboard output terminals is assigned a predetermined digital weight such that when all of the switch contacts are closed as a key station is actuated, the sum of the digital weights will always be an odd number.
Claim 8
Dependent Claim
88 words
The system as defined in claim 6 wherein said movable contact includes a plurality of contact fingers aligned to contact associated fixed contact when said key station is actuated, said movable contact formed such that predetermined ones of said fingers contact associated fixed contacts first and the keyboard output terminals coupled to these fixed contacts are assigned even numbered weights, and a predetermined odd number of other movable contact fingers contact associated fixed contacts last and the fixed contacts associated therewith are assigned unitary or odd numbered weights.
Claim 9
Dependent Claim
65 words
The system as defined in claim 7 wherein said electrical circuit includes network means coupled to said keyboard output terminals for developing a first control signal when all of the switch contacts of a key station are closed as indicated by an odd sum of counts from said keyboard, and for developing a second control signal when none of the keyboard output terminals are actuated.
Claim 10
Dependent Claim
60 words
The system as defined in claim 8 wherein said electrical circuit further includes storage circuit means for storing data signals received at input terminals thereon said input terminals coupled to said keyboard output terminals, a pulse input terminal, and output terminals for providing output signals corresponding to stored input signals when a pulse is applied to said pulse input terminal.
Claim 11
Dependent Claim
49 words
The system as defined in claim 9 wherein said electrical circuit further includes pulse generating means coupled to said network means and to said pulse input terminal of said storage means, said generating means responsive to said first control signal from said network to generate a strobe output pulse.
Claim 12
Dependent Claim
61 words
The system as defined in claim 10 wherein said electrical circuit further includes a comparator coupled to said input and output terminals of said storage circuit for comparing signals thereon and for producing an enable signal at an output terminal thereof when signals at said storage circuit output terminal are different than signals at said input terminals of said storage circuit.
Claim 13
Dependent Claim
46 words
The system as defined in claim 11 wherein said pulse generating means includes inhibit circuit means coupled to said output terminal of said comparator for preventing the generation of a strobe output pulse by said pulse generator unless an enable signal is received from said comparator.
Claim 14
Dependent Claim
51 words
The system as defined in claim 12 wherein said pulse generating means develops a clock pulse applied to said pulse input terminal of said storage circuit whenever said pulse generating means receives a first or a second contral signal from said network means together with an enable signal from said comparator.
Claim 15
Dependent Claim
216 words
An electrical keyboard for providing data signals comprising a plurality of key stations for generating electrical data signals uniquely identifying a symbol associated with each of said key stations, an electrical switch associated with each key station and comprising a single movable contact having a plurality of contact fingers, and an array of associated fixed contacts which are electrically coupled to said single movable contact when said key station is actuated by an operator, a source of operating power coupled to said fixed contacts, output terminals associated with said keyboard and coupled to said fixed contacts of each key station so as to receive electrical signals therefrom when each key station is actuated; and a read-only-memory circuit having input terminals coupled to said output terminals of said keyboard and having data output terminals and first and second control signal output terminals, said memory programmed to convert output signals from said keyboard output terminals to data output signals and to provide a first control signal at said first control signal output terminal indicative that a predetermined number of switch contacts of a key station are closed and to provide a second control signal at said second control signal output terminal indicative of the condition that none of the switch contacts of a key station have been closed.
Claim 16
Dependent Claim
216 words
An electrical keyboard for providing data signals comprising a plurality of key stations for generating electrical data signals uniquely identifying a symbol associated with each of said key stations, an electrical switch associated with each key station and comprising a single movable contact having a plurality of contact fingers, and an array of associated fixed contacts which are electrically coupled to said single movable contact when said key station is actuated by an operator, a source of operating power coupled to said fixed contacts, output terminals associated with said keyboard and coupled to said fixed contacts of each key station so as to receive electrical signals therefrom when each key station is actuated; and a read-only-memory circuit having input terminals coupled to said output terminals of said keyboard and having data output terminals and first and second control signal output terminals, said memory programmed to convert output signals from said keyboard output terminals to data output signals and to provide a first control signal at said first control signal output terminal indicative that a predetermined number of switch contacts of a key station are closed and to provide a second control signal at said second control signal output terminal indicative of the condition that none of the switch contacts of a key station have been closed.
Claim 17
Dependent Claim
62 words
The keyboard as defined in claim 14 and further including a pulse generator circuit coupled to said memory circuit and responsive to said first and second control signals therefrom to generate a strobe output pulse only when a key station is properly actuated as indicated by the presence of said first control signal, said pulse generator further operable to generate clock pulses.
Claim 18
Dependent Claim
123 words
The keyboard as defined in claim 15 and further including a storage circuit for receiving data output signals from said memory circuit and storing said signaLs, said storage circuit having a clock pulse input terminal for receiving said clock pulses from said pulse generator and being responsive thereto to apply said stored input signals to output terminals associated with said storage circuit; said keyboard further including a digital comparator having input terminals coupled to said input terminals of said storage circuit and to said output terminals of said storage circuit for comparing the signals stored in said storage circuit with succeeding input signals applied thereto and for providing an enable signal at an output terminal thereof only when the compared signals are different.
Claim 19
Dependent Claim
53 words
The keyboard as defined in claim 16 wherein said pulse generator further includes inhibit circuit means coupled to said output terminal of said digital comparator and responsive to enable signals therefrom to condition said pulse generator to generate a strobe output pulse when a first control signal is received from said read-only-memory circuit.
Claim 20
Dependent Claim
179 words
An electrical circuit for use in detecting the closure state of a plurality of switch contacts associated with each key station of a mechanically operated electrical keyboard having a plurality of output terminals electrically coupled to said switch contacts, said circuit comprising: first circuit means having a plurality of input terminals coupled to the keyboard output terminals for counting the number of keyboard output terminals which are actuated and for generating output signals representative thereof; second circuit means coupled to said first circuit means for providing a first control signal in response to said output signals from said first circuit means when a predetermined number of output terminals of said keyboard are actuated indicating that all of the switch contacts are properly closed and wherein said second circuit means further provides a second control signal in response to said output signals from said first circuit means when none of said keyboard output terminals are actuated; and a pulse generator coupled to said second circuit means and responsive to said first control signal therefrom to generate a strobe output pulse.
Claim 21
Dependent Claim
179 words
An electrical circuit for use in detecting the closure state of a plurality of switch contacts associated with each key station of a mechanically operated electrical keyboard having a plurality of output terminals electrically coupled to said switch contacts, said circuit comprising: first circuit means having a plurality of input terminals coupled to the keyboard output terminals for counting the number of keyboard output terminals which are actuated and for generating output signals representative thereof; second circuit means coupled to said first circuit means for providing a first control signal in response to said output signals from said first circuit means when a predetermined number of output terminals of said keyboard are actuated indicating that all of the switch contacts are properly closed and wherein said second circuit means further provides a second control signal in response to said output signals from said first circuit means when none of said keyboard output terminals are actuated; and a pulse generator coupled to said second circuit means and responsive to said first control signal therefrom to generate a strobe output pulse.
Claim 22
Dependent Claim
44 words
The electrical circuit as defined in claim 18 wherein said second circuit means further provides a third control signal in response to said output signals from said first circuit means when the number of said output terminals actuated is less than said predetermined number.
Claim 23
Dependent Claim
51 words
The electrical circuit as defined in claim 19 wherein said pulse generator includes a retriggerable monostable multivibrator which responds to said first control signal to provide an output pulse with a pulse width greater than the contact bounce interval of said switch contacts associated with each key station of said keyboard.
Claim 24
Dependent Claim
44 words
The electrical circuit as defined in claim 20 wherein said pulse generator further includes a second multivibrator coupled to said first multivibrator and responsive to the trailing edge of said output pulse of said first multivibrator to provide an output signal in response thereto.
Claim 25
Dependent Claim
58 words
The electrical circuit as defined in claim 21 wherein said pulse generator further includes an inhibiting circuit coupled to said second circuit means and to said first multivibrator for inhibiting the operation of said first multivibrator after each strobe pulse has been generated until a second or third control signal has been received from said second circuit means.
Claim 26
Dependent Claim
220 words
The electrical circuit as defined in claim 24 wherein said inhibiting circuit means comprises: a logic OR gate having a first input terminal coupled to said second circuit means for receiving said second control signals therefrom and a second input terminal coupled to said second control circuit for receiving said third control signals therefrom, said OR gate including an output terminal; a hysteresis latch circuit having a first input terminal coupled to said strobe output terminal of said pulse generator, a second input terminal coupled to said output termInal of said OR gate, and an output terminal; an input logic AND gate having a first input termnal coupled to said second circuit means for receiving said first control signal therefrom, said input AND gate having a second input terminal coupled to said output terminal of said hysteresis latch circuit and an output terminal coupled to said first multivibrator; said latch circuit operable to provide a first output signal when a signal is applied to said second input terminal from said OR gate thereby conditioning said input AND gate to respond to said first control signal and to provide a second output signal conditioning said input AND gate not to respond to said first control signal when a strobe pulse is applied to said first input terminal of said latch circuit.
Claim 27
Dependent Claim
62 words
The electrical circuit as defined in claim 21 and further including a storage circuit having a plurality of input terminals for receiving data signals generated by said keyboard, a plurality of output terminals for providing data output signals and a clock input terminal for receiving clock pulses which actuate the storage circuit to apply data signals stored therein to said output terminals.
Claim 28
Dependent Claim
96 words
The electrical circuit as defined in claim 24 and further including a digital comparator having a plurality of first input terminals coupled to said input terminals of said storage circuit, a plurality of second input terminals coupled to said output terminals of said storage circuit, and an output terminal, said digital comparator operable to compare the data signals applied to said first input terminals with data signals applied to said second input terminals to provide an enable signal at said output terminal only when said signals applied to said first and second input terminals are different.
Claim 29
Independent Claim
153 words
A method of insuring that all of the switch contacts of a key station of a keyboard are closed before generating a strobe output signal which is employed to condition interface equipment to read the data output signal from the keyboard so as to provide accurate transmission of data between the keyboard and associated interface equipment coupled thereto comprising the steps of: weighting each switch contact of each key station with a predetermined digital weight; selecting a data code to uniquely identify each key station of the keyboard and provide a constant predetermined sum of digital counts for each key station of the keyboard; detecting the sum of digital counts for each key station by electrical means; and generating a strobe output pulse only when said predetermined sum of digital counts has been detected thereby indicating actuation of all of the switch contacts of a key station and an accurate data output signal.
Claim 30
Independent Claim
153 words
A method of insuring that all of the switch contacts of a key station of a keyboard are closed before generating a strobe output signal which is employed to condition interface equipment to read the data output signal from the keyboard so as to provide accurate transmission of data between the keyboard and associated interface equipment coupled thereto comprising the steps of: weighting each switch contact of each key station with a predetermined digital weight; selecting a data code to uniquely identify each key station of the keyboard and provide a constant predetermined sum of digital counts for each key station of the keyboard; detecting the sum of digital counts for each key station by electrical means; and generating a strobe output pulse only when said predetermined sum of digital counts has been detected thereby indicating actuation of all of the switch contacts of a key station and an accurate data output signal.
Claim 31
Dependent Claim
168 words
In an electrical keyboard for providing electrical data signals uniquely identifying each key station of the keyboard, the combination of: a movable switch contact for each key station having a plurality of contact fingers adapted to contact associated fixed contacts of a key station when said key station is actuated, said movable contact having at least one contact finger which is last to make contact with an associated fixed contact wherein each contact finger of said movable switch contact except said at least one finger is assigned a predetermined even numbered digital weight, and said at least one contact finger is assigned a unitary weight; and electrical circuit means coupled to the switch contacts of each key station for counting the number of actuated switch contacts for each key station and responsive only to the closure of said at least one contact finger to generate a strobe output pulse upon detecting an odd numbered digital sum when all of the switch contacts of a key station are actuated.
Claim 32
Dependent Claim
168 words
In an electrical keyboard for providing electrical data signals uniquely identifying each key station of the keyboard, the combination of: a movable switch contact for each key station having a plurality of contact fingers adapted to contact associated fixed contacts of a key station when said key station is actuated, said movable contact having at least one contact finger which is last to make contact with an associated fixed contact wherein each contact finger of said movable switch contact except said at least one finger is assigned a predetermined even numbered digital weight, and said at least one contact finger is assigned a unitary weight; and electrical circuit means coupled to the switch contacts of each key station for counting the number of actuated switch contacts for each key station and responsive only to the closure of said at least one contact finger to generate a strobe output pulse upon detecting an odd numbered digital sum when all of the switch contacts of a key station are actuated.
Claim 33
Dependent Claim
161 words
A data generating system for providing electrical data signals comprising a keyboard with a plurality of key stations each representing a symbol for which an electrical data signal is to be generated wherein each key station comprises an electricaL switch having a plurality of fixed electrical contacts which are contacted by a single movable electrical contact, said switch being coupled to a source of operating power and to keyboard output lines having predetermined assigned digital weights, said fixed contacts of each key station being selected and coupled to said lines such that a unique electrical signal is applied to said lines for each key station when actuated, and wherein the sum of weighted lines is a predetermined constant; and electrical circuit means coupled to said lines for detecting the actuated lines and for generating a strobe output pulse only when all of the switch contacts of a key station are properly closed as indicated by the detection of said predetermined constant.
Claim 34
Dependent Claim
161 words
A data generating system for providing electrical data signals comprising a keyboard with a plurality of key stations each representing a symbol for which an electrical data signal is to be generated wherein each key station comprises an electricaL switch having a plurality of fixed electrical contacts which are contacted by a single movable electrical contact, said switch being coupled to a source of operating power and to keyboard output lines having predetermined assigned digital weights, said fixed contacts of each key station being selected and coupled to said lines such that a unique electrical signal is applied to said lines for each key station when actuated, and wherein the sum of weighted lines is a predetermined constant; and electrical circuit means coupled to said lines for detecting the actuated lines and for generating a strobe output pulse only when all of the switch contacts of a key station are properly closed as indicated by the detection of said predetermined constant.
Claim 35
Dependent Claim
139 words
In the system as defined in claim 28 wherein said circuit means includes means for preventing the generation of more than one strobe output pulse when a key station is actuated a single time to provide a hysteresis effect comprising: a storage circuit coupled to said output lines for storing a data output signal therein; a digital comparator coupled to said output lines and to said storage circuit for comparing data signals from each and generating an enabling signal when they differ; detector means coupled to said output lines to generate a first signal when said lines are actuated to provide said predetermined constant digital sum; and pulse generating means coupled to said comparator and to said detector means to generate a strobe pulse when an enabling signal and a first signal is received by said pulse generating means.
References Cited (Backward Citations)
US3676615A
Cited
US3720938A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |