US3660833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for producing characters on a cathode ray tube display by intensity controlled point-to-point vector generation
Assignee: HP Inc
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Filing: 1970-05-11
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Granted: 1972-05-02
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Expires: 1990-05-11
Abstract
Abstract An alpha-numeric character generating system receives digital codes representing characters and controls a CRT to trace a plurality of vectors which in combination form the characters displayed. A read-only memory provides in sequence a plurality of sets of X, Y and Z parameters for each character. Succeeding X and Y parameters are each stored in corresponding alternate registers. The sets of X and Y parameters define the end points of the vectors forming a character. Two digital to analog converters responsive to the X and Y parameters, respectively, provide signals for deflecting the CRT beam. The inputs of the digital to analog converters are transferred between corresponding alternate registers to cause the CRT beam to trace from one vector end point to the next in sequence. A toggle circuit responsive to the Z parameter associated with each set of X and Y parameters controls the transfer time between registers and thus the brightness of each vector traced on the CRT screen.
Inventors
- 👤 Walter T Blejwas Jr
- 👤 Anthony R Kaseta
- 👤 Rene Colen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:08
CPC Classifications
G; G09; G09G; G09G1/00; G09G1/06; G09G1/08; G09G1/10
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
287 words
Apparatus responsive to digital codes representative of characters for controlling a cathode ray tube to display said characters in a predetermined coordinate system, said apparatus comprising: programming means including digital memory for providing in sequence a plurality of sets of first, second and third digital parameters in response to each of said character codes, said first and second parameters defining end points of each of the vectors forming a character and said third parameter defining the time interval during which each vector between said end points is to be traced by the beam to said cathode ray tube; first and second circuit means respectively responsive to said first and second digital parameters from said programming means for providing signals to deflect the beam of said cathode ray tube, each of said first and second circuit means including: a digital to analog converter; first and second register means for alternately storing successive digital parameters provided in sequence by said programming means; means for coupling the digital input of said digital to analog converter to one or the other of said register means; and means for controlling the coupling means of said first and second circuit means to transfer the digital inputs of said digital to analog converters simultaneously and gradually from one to the other of the corresponding first and second register means according to a time transfer function determined in response to said third parameter from said programming means; whereby the outputs of said digital to analog converters produce deflection signals for tracing vectors during selected time intervals between end points which are stored in succession in said first and second register means and provided in a predetermined sequence by said programming means thereby to generate characters.
Claim 2
Dependent Claim
287 words
Apparatus responsive to digital codes representative of characters for controlling a cathode ray tube to display said characters in a predetermined coordinate system, said apparatus comprising: programming means including digital memory for providing in sequence a plurality of sets of first, second and third digital parameters in response to each of said character codes, said first and second parameters defining end points of each of the vectors forming a character and said third parameter defining the time interval during which each vector between said end points is to be traced by the beam to said cathode ray tube; first and second circuit means respectively responsive to said first and second digital parameters from said programming means for providing signals to deflect the beam of said cathode ray tube, each of said first and second circuit means including: a digital to analog converter; first and second register means for alternately storing successive digital parameters provided in sequence by said programming means; means for coupling the digital input of said digital to analog converter to one or the other of said register means; and means for controlling the coupling means of said first and second circuit means to transfer the digital inputs of said digital to analog converters simultaneously and gradually from one to the other of the corresponding first and second register means according to a time transfer function determined in response to said third parameter from said programming means; whereby the outputs of said digital to analog converters produce deflection signals for tracing vectors during selected time intervals between end points which are stored in succession in said first and second register means and provided in a predetermined sequence by said programming means thereby to generate characters.
Claim 3
Dependent Claim
45 words
The apparatus of claim 1 wherein the coupling means of said first and second circuit means each includes a pair of variably conducting means coupled respectively from the corresponding first and second register means to the digital input of the corresponding digital to analog converter.
Claim 4
Dependent Claim
90 words
The apparatus of claim 2 wherein said means for controlling said coupling means includes: generator means providing two predetermined waveforms coupled to the pair of variably conducting means in each of said first and second circuit means for causing complementary conduction of the variably conducting means of each pair between conducting and non-conducting states; and means for adjusting said two waveforms in response to said third digital parameter from said programming means to thereby vary the rate of change of said variably conducting means between said conducting and non-conducting states.
Claim 5
Dependent Claim
30 words
The apparatus of claim 3 said two predetermined waveforms being ramp signals having opposite polarity slopes; and said adjusting means being operable to vary the slopes of said ramp signals.
Claim 6
Dependent Claim
91 words
The apparatus of claim 3 wherein said generator means includes: two capacitors each having an output terminal for providing one of said two predetermined waveforms; means providing a current source; means providing a current sink; switching means operable alternately in first and second modes for selectively coupling said two capacitors to said current source and said current sink, said first mode being operable to charge one of said capacitors and discharge the other of said capacitors, said second mode being operable to discharge said one capacitor and charge said other capacitor.
Claim 7
Dependent Claim
54 words
The apparatus of claim 5, said means providing a current source including a plurality of incremental current sources; and said adjusting means including switching means responsive to said third parameter for coupling said incremental current source to said two capacitors to simultaneously charge one capacitor and discharge the other capacitor at the same rate.
Claim 8
Dependent Claim
136 words
The apparatus of claim 1 wherein in each of said first and second circuit means; said digital to analog converter includes: a weighted resistance network having a plurality of intermediate input tap points and an output providing analog signals; a plurality of current sources connectable respectively to the tap points of said resistance network; said first and second register means each includes switch means for conducting current from selected ones of said current sources to the corresponding tap points of said resistance network in response to said digital parameters; said coupling means includes a plurality of differentially conducting means corresponding respectively to said current sources, each of said differentially conducting means having first and second main current carrying paths for respectively coupling the corresponding one of said current sources to said first and second register means.
Claim 9
Dependent Claim
78 words
The apparatus of claim 7, said plurality of differentially conducting means of said coupling means each having first and second gate control inputs for controlling current conduction through said first and second main current carrying paths, respectively; and said means for controlling said coupling means including signal generating means providing waveforms to said first and second gate control inputs for causing complementary current conduction through said first and second main current carrying paths between conducting and non-conducting states.
Claim 10
Dependent Claim
63 words
The apparatus of claim 8, wherein said last named controlling means further includes means responsive to said third parameter for adjusting the waveforms applied to said first and second gate control inputs to thereby control the time interval during which current conduction through said first and second main current carrying paths changes from one to the other of said conducting and non-conducting states.
Claim 11
Dependent Claim
19 words
The apparatus of claim 7, wherein said plurality of current sources each provide the same magnitude of output current.
Claim 12
Independent Claim
367 words
A system responsive to digital codes representative of characters for controlling a cathode ray tube to display said characters on the screen thereof, said system comprising: programming means including a digital memory for providing in sequence a plurality of sets of first, second and third digital parameters in response to each of said character codes, said first and second parameters having values defining end points of vectors forming a character and said third parameter having values defining the time interval during which vectors between said end points are to be traced by the beam of said cathode ray tube; register means for storing the first and second digital parameters of the last two sets of parameters provided in sequence by said programming means, said register means being updated with each succeeding set of parameters provided by said programming means; digital to analog converter means responsive to said first and second digital parameters for providing deflection signals to position the beam of said cathode ray tube; means synchronized with said programming means for repeatedly transferring the digital inputs of said digital to analog converter means from the pair of first and second parameters in one set to the pair of first and second parameters in the next succeeding set of parameters stored in said register means, said transferring means being operable to effect a transfer according to a time function selected in response to the third parameter in said next succeeding set; said transferring means including: variably conducting means for coupling the digital inputs of said digital to analog converter means from one to the other of the succeeding pairs of first and second digital parameters stored in said register means; generator means providing a signal having a predetermined waveform for gradually changing the conduction of said variably conducting means; means for adjusting said waveform in response to said third parameter from said programming means to vary the rate of change of conduction of variably conducting means; whereby said digital to analog converter means produces deflection signals for tracing vectors of controlled intensity between successive end points which are stored in said register means and provided in a predetermined sequence by said programming means thereby to form characters.
Claim 13
Independent Claim
367 words
A system responsive to digital codes representative of characters for controlling a cathode ray tube to display said characters on the screen thereof, said system comprising: programming means including a digital memory for providing in sequence a plurality of sets of first, second and third digital parameters in response to each of said character codes, said first and second parameters having values defining end points of vectors forming a character and said third parameter having values defining the time interval during which vectors between said end points are to be traced by the beam of said cathode ray tube; register means for storing the first and second digital parameters of the last two sets of parameters provided in sequence by said programming means, said register means being updated with each succeeding set of parameters provided by said programming means; digital to analog converter means responsive to said first and second digital parameters for providing deflection signals to position the beam of said cathode ray tube; means synchronized with said programming means for repeatedly transferring the digital inputs of said digital to analog converter means from the pair of first and second parameters in one set to the pair of first and second parameters in the next succeeding set of parameters stored in said register means, said transferring means being operable to effect a transfer according to a time function selected in response to the third parameter in said next succeeding set; said transferring means including: variably conducting means for coupling the digital inputs of said digital to analog converter means from one to the other of the succeeding pairs of first and second digital parameters stored in said register means; generator means providing a signal having a predetermined waveform for gradually changing the conduction of said variably conducting means; means for adjusting said waveform in response to said third parameter from said programming means to vary the rate of change of conduction of variably conducting means; whereby said digital to analog converter means produces deflection signals for tracing vectors of controlled intensity between successive end points which are stored in said register means and provided in a predetermined sequence by said programming means thereby to form characters.
Claim 14
Dependent Claim
46 words
The apparatus of claim 11, further including means responsive to selected values of said third parameter for selectively blanking the beam of said cathode ray tube during operation of said transferring means, thereby to inhibit display of selected vectors traced during the formation of a character.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |