Patent US3812491A successfully refreshed from Google Patents.
US3812491A
Expired / Lapsed
US
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Raster-scanned display devices
Assignee: Roadside Technology Services Ltd
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Filing: 1972-10-25
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Granted: 1974-05-21
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Expires: 1992-10-25
Abstract
Abstract A synthetic graphics generating system, using a C.R.T. scanned in a T.V. type raster. The video signal for each linescan is calculated digitally in real time, either during the linescan flyback periods, or during execution of the preceding linescan. The described system is used to generate a number of vectors, the calculations for which are performed on a time-shared basis by common circuitry. To prevent a stepped appearance, progressive increase and decrease in brightness is used, preferably using three discrete brightness levels.
Inventors
- 👤 C Barraclough
- 👤 J Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:47
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/20
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
142 words
Apparatus for generating a video signal for input to a raster-scanned display device to cause the device to display at least one graphical symbol, the apparatus comprising: an input store for holding, in digital form, input parameters of said at least one graphical symbol; digital data-processing means comprising means for calculating start and finish time positions of at least one video brightness level, for processing said parameters to produce a digital output characterizing said video signal; and at least one up/down counter for counting up when said digital output indicates a start of said video brightness level, and counting down when said digital output indicates an end of said level, together with means for producing a video signal having that brightness level only when the count of the counter is greater than zero, for converting said digital output into saie video signal.
Claim 2
Dependent Claim
142 words
Apparatus for generating a video signal for input to a raster-scanned display device to cause the device to display at least one graphical symbol, the apparatus comprising: an input store for holding, in digital form, input parameters of said at least one graphical symbol; digital data-processing means comprising means for calculating start and finish time positions of at least one video brightness level, for processing said parameters to produce a digital output characterizing said video signal; and at least one up/down counter for counting up when said digital output indicates a start of said video brightness level, and counting down when said digital output indicates an end of said level, together with means for producing a video signal having that brightness level only when the count of the counter is greater than zero, for converting said digital output into saie video signal.
Claim 3
Dependent Claim
97 words
Apparatus according to claim 1 wherein said digital data processing means comprises: a video store adapted to hold information characterising a portion of said video signal corresponding to at least one linescan of the raster; computing means for performing calculations on said parameters in respect of each linescan of the raster in turn to produce said information for loading into said video store; and read-out means for reading said information out of said video store, on completion of said calculations in respect of a linescan, to produce the portion of said digital output corresponding to that linescan.
Claim 4
Dependent Claim
58 words
Apparatus according to claim 2 wherein said input store comprises a plurality of storage locations for respectively holding parameters of a plurality of graphical symbols, and said computing means comprises means for addressing each of said storage locations in turn to enable said calculations to be performed on the parameters of each of said graphical symbols in turn.
Claim 5
Dependent Claim
63 words
Apparatus according to claim 2 wherein said video store comprises a plurality of words of storage space, respectively corresponding to successive segments of a linescan of the raster, and said read-out means comprises means for addressing each of said words in turn, at a predetermined rate, and means for converting the contents of a said word when so addressed into a digital output.
Claim 6
Dependent Claim
54 words
Apparatus according to claim 4 wherein said computing means comprises means for calculating in which of said segments of the linescan start and finish time positions of at least one video brightness level and means for loading digital codes signifying ''''start'''' and ''''finish'''' into the words of said video store corresponding to those segments.
Claim 7
Dependent Claim
53 words
Apparatus according to claim 5, wherein said input store comprises a plurality of storage locations for respectively holding parameters of a plurality of graphical symbols, and said computing means comprises means for addressing each of said locations in turn, in order of decreasing extent of the symbol in the direction of the linescan.
Claim 8
Dependent Claim
46 words
Apparatus according to claim 6, wherein said symbols are straight vectors, and said computing means comprises means for addressing said locations in order of decreasing tan theta , where theta is the angle between the vector and the direction perpendicular to the lines of the raster.
Claim 9
Dependent Claim
46 words
Apparatus according to claim 1 wherein said data processing means comprises means responsive to synchronisation signals from said raster scanned display device, for initiating the processing of said parameters, in connection with a linescan of the raster, during the linescan flyback period immediately preceding that linescan.
Claim 10
Dependent Claim
57 words
Apparatus according to claim 1 wherein said data processIng means comprises means for storing a number defining the position of a portion of said symbol within a linescan of the raster, and means for performing a predetermined algorithm, according to said parameters, to update said number to its appropriate value for a succeeding linescan of the raster.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |