METHODS FOR DRIVING BISTABLE ELECTRO-OPTIC DISPLAYS, AND APPARATUS FOR USE THEREIN
First Claim
1. A method of driving a bistable electro-optic display having a plurality of pixels, the method comprising:
- storing data representing at least an initial state of each pixel of the display;
storing first and second look-up tables;
receiving an input signal representing a desired final state of at least one pixel of the display; and
generating an output signal representing the impulse necessary to convert the initial state of said one pixel to the desired final state thereof, as determined from said look-up tables,wherein said second look-up table stores a plurality of standard waveforms, each of said plurality of standard waveforms having at least one parameter, and said first look-up table stores, for each combination of initial state and final state of a pixel, a pointer denoting which of the standard waveforms in the second look-up table is to be used for the transition from the initial state to the final state, and the value or values of the at least one parameter to be used in this standard waveform.
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Accused Products
Abstract
A bistable electro-optic display has a plurality of pixels, each of which is capable of displaying at least three gray levels. The display is driven by a method comprising: storing a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level; storing data representing at least an initial state of each pixel of the display; receiving an input signal representing a desired final state of at least one pixel of the display; and generating an output signal representing the impulse necessary to convert the initial state of said one pixel to the desired final state thereof, as determined from said look-up table. The invention also provides a method for reducing the remnant voltage of an electro-optic display.
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Citations
22 Claims
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1. A method of driving a bistable electro-optic display having a plurality of pixels, the method comprising:
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storing data representing at least an initial state of each pixel of the display; storing first and second look-up tables; receiving an input signal representing a desired final state of at least one pixel of the display; and generating an output signal representing the impulse necessary to convert the initial state of said one pixel to the desired final state thereof, as determined from said look-up tables, wherein said second look-up table stores a plurality of standard waveforms, each of said plurality of standard waveforms having at least one parameter, and said first look-up table stores, for each combination of initial state and final state of a pixel, a pointer denoting which of the standard waveforms in the second look-up table is to be used for the transition from the initial state to the final state, and the value or values of the at least one parameter to be used in this standard waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A device controller for controlling a bistable electro-optic display having a plurality of pixels, said controller comprising:
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storage means arranged to store data representing at least an initial state of each pixel of the display, said storage means also being arranged to store first and second look-up tables, said second look-up table storing a plurality of standard waveforms, each of said plurality of standard waveforms having at least one parameter, and said first look-up table storing, for each combination of initial state and final state of a pixel, a pointer denoting which of the standard waveforms in the second look-up table is to be used for the transition from the initial state to the final state, and the value or values of the at least one parameter to be used in this standard waveform; input means for receiving an input signal representing a desired final state of at least one pixel of the display;
calculation means for determining, from the input signal, the stored data representing the initial and prior states of said pixel, and the first and second look-up tables, the impulse required to change the initial state of said one pixel to the desired final state; andoutput means for generating an output signal representative of said impulse. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method of driving an active matrix electro-optic display comprising a layer of a bistable electro-optic medium and a two-dimensional array of pixel electrodes arranged to apply an electric field to the electro-optic medium, a plurality of column electrodes connected to columns of the two-dimensional array of pixel electrodes and a plurality of row electrodes connected rows of the two-dimensional array of pixel electrodes, such that each pixel electrode is uniquely defined by the intersection of one specific column electrode and one specific row electrode, the method comprising:
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(a) writing a first image on the electro-optic medium; (b) selecting the first row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the first row; (c) deselecting the first row of pixel electrodes, selecting the second row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the second row; (d) repeating the deselection and selection of rows of pixel electrodes in turn until all rows have been selected and voltages applied to all the pixel electrodes; and (e) repeating steps (b) to (d) at least once until a second image, different from the first image, is written on the electro-optic medium, the method further comprising storing data representing said second image in an image buffer, and using the data in the image buffer for all of steps (b) to (e) until the second image is written on the display.
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21. A method of driving an active matrix electro-optic display comprising a layer of a bistable electro-optic medium and a two-dimensional array of pixel electrodes arranged to apply an electric field to the electro-optic medium, a plurality of column electrodes connected to columns of the two-dimensional array of pixel electrodes and a plurality of row electrodes connected rows of the two-dimensional array of pixel electrodes, such that each pixel electrode is uniquely defined by the intersection of one specific column electrode and one specific row electrode, the method comprising:
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(a) writing a first image on the electro-optic medium; (b) selecting the first row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the first row; (c) deselecting the first row of pixel electrodes, selecting the second row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the second row; (d) repeating the deselection and selection of rows of pixel electrodes in turn until all rows have been selected and voltages applied to all the pixel electrodes; and (e) repeating steps (b) to (d) at least once until a second image, different from the first image, is written on the electro-optic medium, the method further comprising receiving data representing said second image;
calculating from data representing the first image, and the data representing the second image, the impulses needed to convert each pixel of the first image to the corresponding pixel of the second image;
storing data representing the calculated impulses in an impulse buffer; and
performing step (e) using the data in the impulse buffer.
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22. In a method of driving an active matrix electro-optic display comprising a layer of a bistable electro-optic medium and a two-dimensional array of pixel electrodes arranged to apply an electric field to the electro-optic medium, a plurality of column electrodes connected to columns of the two-dimensional array of pixel electrodes and a plurality of row electrodes connected rows of the two-dimensional array of pixel electrodes, such that each pixel electrode is uniquely defined by the intersection of one specific column electrode and one specific row electrode, the method comprising:
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(a) writing a first image on the electro-optic medium; (b) selecting the first row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the first row; (c) deselecting the first row of pixel electrodes, selecting the second row of pixel electrodes and applying voltages to the column electrodes, thereby applying voltages to the pixel electrodes in the second row; (d) repeating the deselection and selection of rows of pixel electrodes in turn until all rows have been selected and voltages applied to all the pixel electrodes; and (e) repeating steps (b) to (d) at least once until a second image, different from the first image, is written on the electro-optic medium, the improvement comprising, prior to the completion of step (e), receiving data representing a third image different from the first and second images;
calculating, from the current state of each pixel and the third image data, the impulses necessary to convert each pixel from its current state to the corresponding pixel of the third image; and
applying to the pixel electrodes the voltages needed to apply the calculated impulses, thereby causing the third image to be written on the medium without the medium first displaying the second image.
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Specification