Electrophoretic Display Device Using Segmented Voltage Control for Intermediate Color Rendering
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Solution Overview
Problem
Existing electrophoretic display devices face complexity in displaying multiple gray scales and intermediate colors without using a color filter, with existing methods requiring intricate voltage control for precise color rendition.
Innovation Solution
An image display device with a memory property that uses electrophoretic particles of three or more kinds, each with distinct threshold voltage characteristics, applying specific voltages during sub-frame periods to achieve desired color densities and gray scales, including intermediate colors and shades, through a systematic driving method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple kinds of electrophoretic particles with different threshold voltages are used to display multiple gray scales and intermediate colors, then color rendering capability is improved, but voltage control complexity increases
Solution Approach 1:
The voltage control period is segmented into multiple sub-frame periods, with each sub-frame dedicated to controlling a specific electrophoretic particle type. This segmentation allows independent control of each particle kind's migration, enabling precise gray scale and color control without complex simultaneous control of multiple particles.
Solution Approach 2:
The control method applies voltage to specific particle types in a predetermined sequence during sub-frame periods. By controlling particles in a planned sequence rather than simultaneously, the system achieves precise color mixing while simplifying the control logic through temporal separation of control actions.
2Adaptability or versatility
If a color filter is used to display colors, then color rendering is achieved, but device structure becomes more complex
Solution Approach 1:
The color filter layer is completely removed from the display structure. Instead of using a color filter to select colors, the invention uses multiple electrophoretic particles with different colors that can be independently controlled to mix colors optically, eliminating the need for the color filter component entirely.
Solution Approach 2:
The invention changes the fundamental parameter for color control from optical filtering to electrical control of particle migration. By controlling the voltage applied to different electrophoretic particles, the system determines which particles migrate to the display surface, thereby controlling color without any optical filtering components.
3Device complexity
If simple voltage control is used, then device complexity is reduced, but ability to display multiple gray scales and intermediate colors deteriorates
Solution Approach 1:
The control period is divided into multiple sub-frame periods, each dedicated to a specific electrophoretic particle type. This temporal segmentation allows simple, sequential control of each particle type while achieving complex color and gray scale display through the combination of controlled particle migrations during different sub-frames.
Solution Approach 2:
The system uses periodic voltage application during sub-frame periods to control particle migration. By applying voltage in a periodic, sequential manner to different particle types, the system achieves precise control over multiple gray scales and intermediate colors through the periodic action of controlling each particle type in turn.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables simple configuration for displaying single colors, intermediate colors, and shades of gray, improving color rendition and reducing complexity in voltage control, thereby enhancing display capabilities.
Implementation Method 1
an electrophoretic display device of a type that displays white and black colors by active-matrix driving method... by applying a voltage corresponding to pixel data between the pixel electrode and facing electrode and by moving the white and black pigments up and down
Data Source
AI summary
An image display device expresses multiple colors including intermediate colors and an electrophoretic particle making up the image display device includes n-kinds of (n>2) charged particles each having colors and threshold value voltages each being different from one another. A specified period during which a voltage is applied includes a resetting period for applying a resetting voltage, a first, . . . , kth, . . . , nth voltage applying periods and a voltage to be applied includes a resetting voltage, 0V, first voltage (absolute value) to be applied within the first voltage applying period, 0V, kth voltage (absolute value) to be applied within kth voltage applying period, and 0V voltage, nth voltage (absolute value) to be applied within an nth voltage applying period. Relationships: |first applied voltage|>|kth applied voltage|>|nth voltage| and |first applied voltage|<|kth voltage|<|nth voltage| are satisfied.