EP0479450A2
Expired / Lapsed
EP
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Brightness control for flat panel display
Assignee: Raytheon Co
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Filing: 1991-09-19
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Granted: —
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Expires: 2011-09-19
Abstract
Abstract For controlling the brightness of a matrix-addressed flat panel CRT display (70) of a type having intersecting column and row conductors (72,74) forming, respectively, the cathode and gate electrodes of a field electron emission array (76), the brightness control effected by controlling both the duty cycle and the voltage applied to the drive lines of the intersecting conductors (72,74). A periodic staircase waveform having progressively increasing voltage steps (VROW) is sequentially applied to the row conductors (74). The voltages (VROW) at each of the steps are selected to enable electron beam currents which proved brightness levels which are twice the brightness of the previous step. Binary-coded video brightness data are simultaneously applied to all of the column conductors (72). The combined voltages at the intersections of the selected conductors cause a sequence of electron emissions onto luminescing means which result in a corresponding sequence of illumination intervals. The human optic system integrates this illumination sequence into the selected brightness level. In addition, the overall brightness of the display is controlled by gating (84) the waveforms for the column conductors (74) with a pulse train comprising a sequence of adjustable, uniform-width pulses from an adjusting one shot (88).
Inventors
- 👤 Peter C. Dunham
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 11:29
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/22; H; H01; H01J; H01J31/00; H01J31/08; H01J31/10; H01J31/12; H01J31/123; H01J31/125; H01J31/127; G09G3/2007; G09G3/2011; G09G3/2014
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
260 words
In a flat panel display comprising a backing structure having a planar surface including a first plurality of substantially parallel conductors disposed across said surface and a second plurality of substantially parallel conductors disposed across said surface, said conductors of said first plurality intersecting said conductors of said second plurality, but electrically isolated therefrom; and further comprising means at each intersection of said first and second pluralities of conductors for emitting an electron beam current therefrom in response to a potential difference between said intersecting conductors; an apparatus for controlling the electron beam current from said emitting means at each of said intersections, said apparatus comprising: first source means for coupling a periodic signal individually to said first plurality of conductors, said periodic signal comprising a plurality of steps of different voltage levels; and second source means for coupling a brightness control signal to said second plurality of conductors, said brightness control signal being driven between a first reference potential and a second reference potential in response to a binary-coded, video input signal, wherein the voltage difference between the voltage level steps of said periodic signal coupled individually to said first plurality of conductors and said second reference potential of said brightness control signal coupled to said second plurality of conductors generates an electron beam current from the emitting means at the intersection of the conductor of said first plurality coupled to said first source means and the conductor of said second plurality coupled to said second source means, said electron beam current varying in accordance with said voltage difference.
Claim 2
Dependent Claim
287 words
A flat panel display comprising: a backing structure having a first planar surface including a first plurality of substantially parallel conductors disposed across said surface and a second plurality of substantially parallel conductors disposed across said surface, said conductors of said first plurality intersecting said conductors of said second plurality, but electrically isolated therefrom; means at each intersection of said first and second pluralities of conductors for emitting an electron beam current therefrom in response to a potential difference between said intersecting conductors; a face structure having a second planar surface adjacent said first surface including means on said second surface responsive to electron beam current for providing luminescence; and means for controlling the electron beam current from said emitting means at each of said intersections, said controlling means including: first source means for coupling a periodic signal individually to said first plurality of conductors, said periodic signal comprising a plurality of steps of different voltage levels; and second source means for coupling a brightness control signal to said second plurality of conductors, said brightness control signal being driven between a first reference potential and a second reference potential in response to a binary-coded, video input signal, wherein the voltage difference between the voltage level steps of said periodic signal coupled individually to said first plurality of conductors and said second reference potential of said brightness control signal coupled to said second plurality of conductors is sufficient to generate an electron beam current from the emitting means at the intersection of the conductor of said first plurality coupled to said first source means and the conductor of said second plurality coupled to said second source means, said electron beam current varying in accordance with said voltage difference.
Claim 3
Dependent Claim
37 words
The flat panel display according to Claim 1 or 2 wherein said first plurality of conductors comprise row conductors and said second plurality of conductors comprise column conductors, said row conductors being orthogonal to said column conductors.
Claim 4
Dependent Claim
56 words
The flat panel display according to Claim 1 or 2 wherein said second source means couples brightness control signals simultaneously to all of said second plurality of conductors, to thereby simultaneously enable generation of electron beam current from all of the emitting means along the conductor of said first plurality coupled to said first source means.
Claim 5
Dependent Claim
23 words
The flat panel display according to Claim 1 or 2 wherein said periodic signal has a staircase waveform of progressively increasing voltage steps.
Claim 6
Dependent Claim
35 words
The flat panel display according to Claim 5 wherein the voltages at each of said waveform steps are selected to provide successive levels of electron beam current which are related according to a binary progression.
Claim 7
Dependent Claim
46 words
The flat panel display according to Claim 1 or 2 wherein said first source means includes: means for storing digital representations of each of said plurality of voltage level steps; and means responsive to said storing means for converting said digital representations into analog voltage levels.
Claim 8
Dependent Claim
18 words
The flat panel display according to Claim 7 wherein said storing means includes a programmable read-only memory (PROM).
Claim 9
Dependent Claim
36 words
The flat panel display according to Claim 1 or 2 further including means for adjusting the voltage levels of said steps of said periodic signal and said first reference potential relative to said second reference potential.
Claim 10
Dependent Claim
45 words
The flat panel display according to Claim 1 or 2 further including means for gating said binary-coded, video input signal at each voltage level step of said periodic signal, said gating means including means for generating a signal having a waveform of equal, adjustable-length pulses.
References Cited (Backward Citations)
No citation records indexed.
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