Electrophoretic Display Driving Voltage Control
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Solution Overview
Problem
Conventional color display technologies face challenges in achieving bright and saturated white and black states while maintaining color gamut, often resulting in dim and unsaturated colors due to the limitations of sub-pixel reflectance and the need for additional sub-pixels, which can increase costs and reduce backplane yield.
Innovation Solution
A method for driving a display cell filled with electrophoretic fluid comprising two types of pigment particles with opposite charge polarities dispersed in a solvent, applying a driving voltage of 1 to 20% of the full driving voltage to achieve color states, allowing for uniform pigment arrangement and intense color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color filters are added on top of black/white sub-pixels to achieve color display, then color display capability is improved, but white state brightness deteriorates (white level becomes dim)
Solution Approach 1:
The patent applies a low driving voltage (1-20% of full driving voltage) to achieve a partial color state where pigment particles are partially aligned, allowing the display to show intense solvent color without requiring full particle migration. This parameter change in voltage application enables simultaneous achievement of color saturation and white state brightness.
Solution Approach 2:
Instead of requiring complete particle migration to achieve color display, the patent uses partial action by applying reduced voltage that causes partial particle alignment. This partial alignment is sufficient to produce intense color while maintaining better white state brightness compared to conventional approaches.
2Illumination intensity
If a fourth white sub-pixel is added to compensate for dim white state, then white level brightness is improved, but color saturation deteriorates (colors become light and unsaturated)
Solution Approach 1:
By changing the voltage parameter to a low range (1-20% of full voltage), the patent achieves partial particle alignment that produces intense solvent color. This eliminates the need for a fourth white sub-pixel while maintaining both white state brightness and color saturation.
Solution Approach 2:
The patent makes the colored solvent serve multiple functions: it acts as both the color display medium and the white state reflector. When particles are partially aligned with low voltage, the solvent color is intense; when particles are fully migrated, the white state is bright. This multi-functionality eliminates the need for separate white sub-pixels.
3Illumination intensity
If dual switching mode with extra electrodes is used to achieve high quality white and black states, then display quality is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the colored solvent perform multiple functions: it provides color display, white state reflection, and black state absorption. This eliminates the need for complex dual switching circuitry with extra electrodes, reducing device complexity while maintaining display quality.
Solution Approach 2:
By using different voltage levels (low voltage for color state, high voltage for black/white states), the patent achieves multiple display states using the same electrode structure, eliminating the need for extra switching electrodes and complex circuitry.
4Ease of manufacture
If sub-pixel area is reduced to accommodate more color sub-pixels, then color display capability is improved, but white state brightness deteriorates (each sub-pixel reflects only one third of desired white)
Solution Approach 1:
The colored solvent serves dual purposes as both color display medium and white state reflector. This allows the same sub-pixel area to be used for both color and white state display, eliminating the need to reduce sub-pixel area and maintaining full white state brightness.
Solution Approach 2:
The patent uses a composite system of charged pigment particles dispersed in colored solvent, where the combination provides both color display and white state reflection functions within the same sub-pixel structure, maintaining area efficiency.
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
This approach enables the achievement of high-quality white and black states along with vibrant colors by uniformly arranging pigment particles, enhancing color saturation and brightness without increasing costs or reducing backplane yield.
Implementation Method 1
A method for driving a display cell filled with an electrophoretic fluid comprising two types of pigment particles carrying opposite charge polarities
Implementation Method 2
applying a driving voltage which is about 1 to about 20% of the full driving voltage to achieve color states, allowing for uniform pigment arrangement and intense color representation
Data Source
AI summary
A method for driving a display cell filled with an electrophoretic fluid comprising two types of pigment particles carrying opposite charge polarities and of two contrast colors wherein said two types of pigment particles are dispersed in a solvent of a color, which method comprises driving said display cell to a color state which color is the color of the solvent by applying a driving voltage which is about 1 to about 20% of the full driving voltage.