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US5285197A
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Method and apparatus for automatic selection of scan rates for enhanced VGA-compatible monitors
Assignee: NEC-MITSUBISHI ELECTRONICS DISPLAY OF AMERICA Inc A DELAWARE Corp
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Filing: 1991-08-28
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Granted: 1994-02-08
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Expires: 2011-08-28
Abstract
Abstract An apparatus for determining a plurality of video signal characteristics including analog video frequency, horizontal sync frequency and vertical sync frequency produced by a graphics controller providing the video signal to a video display monitor, includes a memory storing bits which correspond to a set of operating characteristics of the video display monitor, a first circuit coupled to the memory for producing voltage fluctuations on a line based on the stored bits in response to a signal which corresponds to a command to set the characteristics of the video signal provided to the video display monitor, and a second circuit for sensing the voltage fluctuations so as to permit determination of the set of operating characteristics. The first circuit includes a switch operatively coupled between a video line and ground to allow grounding of the video line based on the bits so as to produce the voltage fluctuations. The second circuit comprises a logic element for detecting the voltage fluctuations. A method for determining the operating capabilities of the video display monitor is also disclosed.
Inventors
- 👤 Thomas J. Schmidt
- 👤 Richard Atanus
- 👤 James F. Murray
- 👤 Arnold J. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:50
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/14; G06F3/153; G09; G09G; G09G1/00; G09G1/06; G09G1/14; G09G1/16; G09G2370/00; G09G2370/04; G09G2370/042
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
142 words
In a computer system having a video display monitor connected to circuitry adapted to provide a video signal having a plurality of video signal characteristics including an analog video frequency, a horizontal sync frequency and a vertical sync frequency, a method for determining the video signal characteristics which the monitor will support comprising the steps of: generating a first signal corresponding to the maximum video signal characteristics supported by the video display monitor in response to reception of a second signal corresponding to a video display monitor identification command; and sensing the first signal so as to permit determination of the maximum video display signal characteristics, wherein said second signal is a signal corresponding to a video mode change, wherein said first signal has a predetermined pulse width and wherein said sensing step comprises determining said pulse width of said first signal.
Claim 2
Dependent Claim
142 words
In a computer system having a video display monitor connected to circuitry adapted to provide a video signal having a plurality of video signal characteristics including an analog video frequency, a horizontal sync frequency and a vertical sync frequency, a method for determining the video signal characteristics which the monitor will support comprising the steps of: generating a first signal corresponding to the maximum video signal characteristics supported by the video display monitor in response to reception of a second signal corresponding to a video display monitor identification command; and sensing the first signal so as to permit determination of the maximum video display signal characteristics, wherein said second signal is a signal corresponding to a video mode change, wherein said first signal has a predetermined pulse width and wherein said sensing step comprises determining said pulse width of said first signal.
Claim 3
Independent Claim
169 words
An apparatus for selecting one of a plurality of video signal characteristics including an analog video frequency, a horizontal sync frequency, and a vertical sync frequency produced by circuitry providing the video signal to a video display monitor, comprising: a first circuit for generating a first signal responsive to a second signal corresponding to a command to set the characteristics of the video signal provided to the video display monitor; and a second circuit for sensing said first signal so as to permit identification of a set of operating characteristics of said video display monitor from a plurality of sets of predetermined operating characteristics, wherein said first circuit is a switch element for grounding a passive network so as to produce said first signal having a plurality of predetermined durations, each of said predetermined durations corresponding to said set of operating characteristics for said video display monitor and wherein said second circuit further comprises a timing circuit so as to permit determination of said duration of said first signal.
Claim 4
Independent Claim
169 words
An apparatus for selecting one of a plurality of video signal characteristics including an analog video frequency, a horizontal sync frequency, and a vertical sync frequency produced by circuitry providing the video signal to a video display monitor, comprising: a first circuit for generating a first signal responsive to a second signal corresponding to a command to set the characteristics of the video signal provided to the video display monitor; and a second circuit for sensing said first signal so as to permit identification of a set of operating characteristics of said video display monitor from a plurality of sets of predetermined operating characteristics, wherein said first circuit is a switch element for grounding a passive network so as to produce said first signal having a plurality of predetermined durations, each of said predetermined durations corresponding to said set of operating characteristics for said video display monitor and wherein said second circuit further comprises a timing circuit so as to permit determination of said duration of said first signal.
Claim 5
Dependent Claim
44 words
The apparatus of claim 2, wherein said first circuit comprises a resistor disposed in the video display monitor, said resistor being operatively coupled to a capacitor so as to permit said capacitor to be charged and discharged responsive to operation of said switch element.
Claim 6
Dependent Claim
13 words
The apparatus of claim 3, wherein said second signal is a digital signal.
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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) | 1997-02-07 | 1997-08-09 | 1998-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-07 | 2001-08-09 | 2002-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-07 | 2005-08-09 | 2006-02-08 | $7700.00 | Window Closed / Lapsed |