Patent EP0569974A2 successfully refreshed from Google Patents.
EP0569974A2
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Gray level addressing for LCDS
Assignee: In Focus Systems Inc
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Filing: 1993-05-12
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Granted: —
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Expires: 2013-05-12
Abstract
Abstract Method and apparatus for providing gray level addressing for passive liquid crystal display (LCD) panels having overlapping row and column electrodes defining pixels are disclosed. Depending upon whether the rows are being addressed by "standard" or "Swift" addressing, the signals for applying to the column electrodes are determined by different calculations, in all of which modes the amplitudes of the column signals are related to the gray level desired to be displayed by the individual pixels. For a split interval system, column signals of appropriate amplitude and polarity are applied during different subintervals of a characteristic time interval of the display panel depending upon the method of addressing the rows. In the full interval mode, the column signals applied over a full time interval are based on the desired gray level of all the pixels in the column, adjusted to provide the proper rms voltage across all the pixels so that they display the desired gray levels.
Inventors
- 👤 Terry J. Scheffer
- 👤 R. Conner Arlie
- 👤 Benjamin R. Clifton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:05
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/2007; G09G3/2011; G09G3/34; G09G3/36; G09G3/3611; G09G3/3622; G09G3/3625; G09G2310/00; G09G2310/02; G09G2310/0264; G09G2310/027; G09G3/2014; G09G3/2018; G09G3/2022
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
102 words
A method for addressing a passive, rms-responding display in which multiple overlapping first and second electrodes positioned on opposite sides of an rms-responding material define an array of pixels that display information in more than two gray levels, the method comprising: applying first signals to corresponding first electrodes during a frame period; and applying second signals of changing magnitude to corresponding second electrodes during characteristic time intervals of the frame period, the magnitude of each second signal during a characteristic time interval being related to the desired gray level of at least one of the pixels defined by the corresponding second electrode.
Claim 2
Dependent Claim
103 words
The method of claim 1, in which the characteristic time intervals are divided into subintervals, the first signals are pulses of amplitude S, and the second signals are of magnitudes X for one of the subintervals and Y for another of the subintervals, X and Y being determined by the equations: where D is related to the non-select rms voltage, V ns , across a pixel by: S is related to D by: S = √ N ¯ D, where N is the number of first electrodes in the display, and f is a desired gray level fraction varying between zero and one.
Claim 3
Dependent Claim
31 words
The method of claim 1, in which the first signals select pixels defined by corresponding first electrodes once during each frame period and the characteristic time intervals are divided into subintervals.
Claim 4
Dependent Claim
35 words
The method of claim 1, in which the first signals select pixels defined by only one of the corresponding first electrodes during each characteristic time interval and the characteristic time intervals are divided into subintervals.
Claim 5
Dependent Claim
33 words
The method of claim 1, in which the first signals select pixels defined by a corresponding first electrode more than once during the frame period and the time intervals are divided into subintervals.
Claim 6
Dependent Claim
34 words
The method of claim 1, in which the first signals select pixels defined by more than one corresponding first electrodes during a characteristic time interval, and the characteristic time intervals are divided into subintervals.
Claim 7
Dependent Claim
110 words
The method of claim 6, in which: the gray level of each pixel is described by a gray word composed of multiple gray bits, and the second signals are of magnitudes X for one of the subintervals and Y for another of the subintervals, X and Y being determined by the equations: X= 1 2 [p+√ 2q+p² ¯ ], and Y = 1 2 [p-√ 2q-p² ¯ ], where and where n is the number of gray bits in the gray level word, g is the position of the gray bit in the gray level word, and G g is the column signal magnitude for the g th gray bit.
Claim 8
Dependent Claim
93 words
The method of claim 1, in which the desired gray levels of the pixels are represented by pixel information elements, the values of which vary between a lower and an upper limit, and in which multiple virtual information elements are associated with virtual pixels defined by a virtual first electrode overlapping the second electrodes, the method further including: applying to the second electrodes second signals having magnitudes related to the values of the information elements and the virtual information elements of the respective pixels and virtual pixels defined by the corresponding second electrode.
Claim 9
Dependent Claim
58 words
The method of claim 8, in which the magnitudes of the second signals are proportional to the virtual information elements of the virtual pixels defined by the overlap of the corresponding second electrodes with the virtual first electrode during a time interval in which none of the pixels defined by the overlapping first and second electrodes are selected.
Claim 10
Dependent Claim
69 words
The method of claim 1, in which the desired gray levels of the pixels are represented by pixel information elements, the values of which vary between a lower and an upper limit, and in which the magnitude of each second signal during at least one of the characteristic time intervals is related to the value of the pixel information elements of each pixel defined by the corresponding second electrode.
Claim 11
Dependent Claim
45 words
The method of claim 10, in which the magnitude or each second signal during one of the characteristic time intervals is related to a sum of the squares of the value of the pixel information elements of each pixel defined by the corresponding second electrode.
Claim 12
Dependent Claim
115 words
The method of claim 1, in which the desired gray levels of the pixels are represented by pixel information elements, the values of which vary between a lower and an upper limit, and in which the magnitude of each second signal during the time interval is proportional to a sum of products of the value of the information element of each pixel defined by the corresponding second electrode and the amplitude of the first signal of the corresponding first electrode, the magnitude of the second signal being determined by adding to the product a term related to the square of the values of the information elements of the pixels defined by the corresponding second electrode.
Claim 13
Dependent Claim
148 words
The method of claim 1, in which the desired gray levels of the pixels are represented by pixel information elements, the values of which vary between a lower and an upper limit, the method further including: generating at least one virtual first signal for at least one virtual first electrode that overlaps the second electrodes and provides a plurality of virtual pixels having associated virtual pixel information elements of value: where N is the number of first electrodes in the display and I i are the pixel information elements of the corresponding first electrode; and applying the first signals to select pixels defined by the corresponding first electrodes and virtual pixels defined by the corresponding virtual electrode, the magnitude of each second signal being proportional to the pixel information element and the virtual pixel information element of the selected pixels and virtual pixels, respectively, during the time interval.
Claim 14
Dependent Claim
196 words
The method of claim 1, in which the first signals select pixels defined by each corresponding first electrode during more than one time interval of the frame period, and the desired gray levels of pixels are represented by pixel information elements the values of which vary between a lower and an upper limit, the method further including: generating at least one virtual first signal for at least one virtual first electrode that overlaps the second electrodes and defines a plurality of virtual pixels having desired gray levels represented by virtual information elements, the magnitude of each second signal at any time interval being determined by: where N is the number of first electrodes, I i is the pixel information element at a pixel defined by the corresponding second electrode and a particular first electrode, F i is the amplitude of the first signal applied to the corresponding first electrode during the time interval, V k is the virtual information element at a virtual pixel defined by the corresponding second electrode and a particular virtual first electrode, and F k is the amplitude of the first signal associated with that virtual first electrode during the time interval.
Claim 15
Independent Claim
113 words
An apparatus for addressing an rms-responding, passive display in which multiple overlapping first and second electrodes positioned on opposite sides of an rms-responding material define an array of pixels to display information in more than two gray levels, comprising: means for applying first signals to the first electrodes during a frame period; and means for applying to the second electrodes during characteristic time intervals of the frame period second signals of changing magnitudes representative of the information to be displayed, the magnitude of each second signal at any time interval during the frame period being related the desired gray level of at least one of the pixels defined by the corresponding second electrode.
Claim 16
Dependent Claim
15 words
The apparatus of claim 15, in which the characteristic time intervals are divided into subintervals.
Claim 17
Dependent Claim
26 words
The apparatus of claim 16, in which the means for applying the first signals selects pixels defined by a single first electrode during each time interval.
Claim 18
Dependent Claim
25 words
The apparatus of claim 16, in which the means for applying the first signals selects pixels defined by multiple first electrodes during each time interval.
Claim 19
Dependent Claim
69 words
The apparatus of claim 15, in which the desired gray levels of the pixels are represented by pixel information elements, the values of which vary between a lower and an upper limit, and in which the magnitude of each second signal during at least one of the characteristic time intervals is related to the value of the pixel information elements of each pixel defined by the corresponding second electrode.
Claim 20
Dependent Claim
32 words
The apparatus of claim 19, in which a second signal is applied during a time interval in which none of the pixels defined by the overlapping first and second electrodes is selected.
Claim 21
Dependent Claim
84 words
The apparatus of claim 19, in which the magnitude of each second signal during the time interval is proportional to a sum of products of the value of the information element of each pixel defined by the corresponding second electrode and the amplitude of the first signal of the corresponding first electrode, the magnitude of the second signal being adjusted by adding to the product a term related to the values of the information elements of the pixels defined by the corresponding second electrode.
References Cited (Backward Citations)
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