Methods for driving bistable electro-optic displays, and apparatus for use therein

A method of driving a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, the 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;
• generating a lifetime signal representing the operating time of said one pixel;
• 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, said output signal being generated dependent upon said lifetime signal.

A method of driving a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, the 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;
• generating a residence time signal representing the time since said one pixel underwent a transition;
• 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, said output signal being generated dependent upon said residence time signal.

A device controller for controlling a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

• storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display, said storage means also being arranged to store data representing a least one prior state of each pixel prior to said initial state thereof;
• 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 look-up table, the impulse required to change the initial state of said one pixel to the desired final state;
• and
• output means for generating an output signal representative of said impulse.

A device controller for controlling a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

• storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display,
• input means for receiving an input signal representing a desired final state of at least one pixel of the display, said input means also being arranged to receive a temperature signal representing the temperature of at least one pixel of the display;
• calculation means for determining, from the input signal, the stored data representing the initial state of said pixel, said temperature signal, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state;
• and
• output means for generating an output signal representative of said impulse.

A device controller for controlling a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

• storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display,
• input means for receiving an input signal representing a desired final state of at least one pixel of the display;
• lifetime signal generation means arranged to generate a lifetime signal representing the operating time of said pixel
• calculation means for determining, from the input signal, the stored data representing the initial state of said pixel, said lifetime signal, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state;
• and
• output means for generating an output signal representative of said impulse.

A device controller for controlling a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

• storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display,
• input means for receiving an input signal representing a desired final state of at least one pixel of the display;
• residence time signal generation means for determining the residence time since said one pixel last underwent a transition and for generating a residence time signal representing said residence time;
• calculation means for determining, from the input signal, the stored data representing the initial state of said pixel, said residence time signal, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state;
• and
• output means for generating an output signal representative of said impulse.

A device controller comprising:

• storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display;
• 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 state of said pixel, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state;
• and
• output means for generating an output signal representative of said impulse, the output signal representing a plurality of pulses varying in at least one of voltage and duration, the output signal representing a zero voltage after the expiration of a predetermined period of time.

A driver circuit comprising:

• output lines arranged to be connected to drive electrodes of an electro-optic display;
• first input means for receiving a plurality of 2-bit numbers representing the voltage and polarity of signals to be placed on the drive electrodes;
• and
• second input means for receiving a clock signal,
• the driver circuit being arranged such that, upon receipt of the clock signal, the driver circuit displays voltages selected from R+V, R and R−V on its output lines, where R is a reference voltage and V is the maximum difference from the reference voltage which the driver circuit can assert.

A method for driving an electro-optic display having a remnant voltage, the method comprising:

• (a) applying a first driving pulse to a pixel of the display;
• (b) measuring the remnant voltage of the pixel after the first driving pulse;
• and
• (c) applying a second driving pulse to the pixel following the measurement of the remnant voltage, the magnitude of the second driving pulse being controlled dependent upon the measured remnant voltage to reduce the remnant voltage of the pixel.