Dynamic drive methods and apparatus for a bistable liquid crystal display

A method for displaying information comprising the steps of:

• a) providing a layer of bistable liquid crystal material and arranging electrodes on opposed sides of the liquid crystal material to form an array of display elements;
• b) coupling the electrodes to a drive circuit for energizing the electrodes to selectively activate the display elements of the array to one of a first and a second final display state;
• and
• c) addressing selected display elements of the array by sequentially energizing the liquid crystal material at a selected display element location with a preparation signal during a preparation phase, reducing the preparation signal to a post-preparation signal during a post-preparation phase, adjusting the post-preparation signal to a selection signal for selecting a desired final display state during a selection phase, changing the selection signal across the display element to an evolution signal during an evolution phase which creates a state which can change to one of two final display states for each display element after completion of the addressing step, wherein said final display state remains indefinitely until said addressing steps are repeated.

A display apparatus comprising:

• a) a layer of bistable liquid crystal material;
• b) multiple electrodes spaced on opposite sides of the liquid crystal layer for applying selected activation voltages across multiple picture elements of the liquid crystal layer;
• and
• c) control electronics for sequentially setting a display state of multiple picture elements of the liquid crystal layer comprising circuitry for:
• i) applying a preparation signal across a selected picture element during a preparation phase;
• ii) applying a post-preparation across said selected picture element during a post-preparation phase;
• iii) applying a selection signal across said selected picture element during a selection phase to select a selection state which evolves into one of two final display states;
• and
• iv) applying an evolution signal across said selected picture element during an evolution phase and creating an evolution state which changes to one of two final display states after completion of the applying steps, wherein said final display state remains indefinitely until said energizing steps are repeated.

A method of addressing a bistable liquid crystal material disposed between electrodes arranged on opposed sides of said liquid crystal and adapted to selectively apply an electric field through said liquid crystal material, said method comprising the steps of:

• energizing said electrodes to establish a preparation voltage across said liquid crystal material during a preparation phase;
• energizing said electrodes to establish a selection voltage across said liquid crystal material during a selection phase for selecting one of two final display states for said liquid crystal;
• and
• permitting said liquid crystal to exhibit the final display state without further energizing said electrodes, wherein at least one of the final display states is different than a preparation state of the liquid crystal material during said selection phase and creating a state which changes to one of two final display states after completion of the addressing method, wherein said final display state remains indefinitely until said energizing steps are repeated.

A method for displaying information comprising the steps of:

• a) providing a layer of bistable liquid crystal material and arranging electrodes on opposed sides of the liquid crystal material to form an array of display elements;
• b) coupling the electrodes to a drive circuit for energizing the electrodes to selectively activate the display elements of the array to one of a first and a second final display state;
• and
• c) addressing selected display elements of the array by sequentially energizing the liquid crystal material at a selected display element location with a preparation signal during a preparation phase, providing a selection signal for selecting a desired final display state during a selection phase, and then allowing the display element to exhibit the desired final display state without further energizing said electrodes and creating a state which can change to one of two final display states after completion of the addressing steps, wherein said final display state remains indefinitely until said addressing steps are repeated.

A display apparatus comprising:

• a) a layer of bistable liquid crystal material;
• b) multiple electrodes spaced on opposite sides of the liquid crystal layer for applying selected activation voltages across multiple picture elements of the liquid crystal layer;
• and
• c) control electronics for sequentially setting a display state of multiple picture elements of the liquid crystal layer comprising circuitry for:
• i) applying a preparation signal across a selected picture element during a preparation phase to cause the liquid crystal layer to exhibit a preparation texture;
• and
• ii) applying a selection signal across said selected picture element during a selection phase to select a predetermined final display state wherein at least one of the predetermined final display states is different than the preparation texture of the liquid crystal material during said selection phase and creating a state which can change to one of two final display states after completion of the addressing method without further energizing said selected picture element, wherein said final display state remains indefinitely until said applying steps are repeated.