Electrophoretic Display Voltage Balancing for Pixel Deterioration

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Electrophoretic display devices experience image blurring and pixel deterioration due to current leakage during image rewriting, particularly when pixels with different gray levels are updated, leading to imbalance in voltage polarities and potential corrosion.

Innovation Solution

A control device applies a first voltage multiple times when changing the gray level from one level to another, and a second voltage with a different polarity multiple times when reversing the change, ensuring equal applications of both voltages across pixels to cancel out charges and maintain a balanced DC state, thereby controlling pixel deterioration and blurring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If voltage is applied only to pixel electrodes corresponding to extracted pixels for image rewriting, then high-speed image rewriting is achieved, but image blurring occurs at pixels that are not rewritten due to leakage of electric current

Engineering Contradiction:

Improveimage rewriting speedVSAvoidimage clarity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent divides the pixel electrodes into two groups: selected pixels requiring rewriting and non-selected pixels maintaining their current state. By applying voltage selectively only to the segmented group of selected pixels, the system achieves high-speed rewriting while preventing current leakage to non-selected pixels, thus avoiding image blurring.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different voltage conditions to different regions of the display. Selected pixel electrodes receive rewriting voltages while non-selected pixel electrodes are maintained at a potential that prevents current leakage. This local differentiation allows high-speed rewriting in specific areas without affecting the overall image quality.

Inventive Principle:

Principle #3Local quality

2Productivity

If voltage is applied only to selected pixel electrodes for rewriting, then rewriting speed is improved, but pixel deterioration progresses due to imbalance in voltage polarities caused by current leakage

Engineering Contradiction:

Improverewriting speedVSAvoidpixel durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the potentially harmful effect of current leakage into a beneficial control mechanism. By intentionally applying compensating voltages to non-selected pixels, the system uses the leakage phenomenon to its advantage, balancing the voltage polarities and preventing pixel deterioration while maintaining high rewriting speed.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent implements a feedback mechanism where the voltage application to non-selected pixels is determined by the state of selected pixels and the observed current leakage patterns. This feedback control ensures that voltage polarities remain balanced, preventing pixel deterioration while maintaining efficient rewriting operations.

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If refreshing is performed to cancel image blurring from current leakage, then image clarity is maintained, but pixel deterioration accelerates due to imbalance in voltage polarities

Engineering Contradiction:

Improveimage clarityVSAvoidpixel lifespan

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent employs periodic voltage applications to non-selected pixels in a controlled manner. Instead of continuous refreshing that causes polarity imbalance, the system applies compensating voltages periodically and selectively, maintaining image clarity while preventing pixel deterioration through balanced voltage cycling.

Inventive Principle:

Principle #19Periodic action

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 effectively reduces pixel blurring and deterioration by balancing voltage applications, maintaining a stable DC state and preventing corrosion, allowing for high-speed image rewriting while extending the lifespan of display elements.

Implementation Method 1

White particles and black particles that are charged with mutually opposite polarities are contained in each of the microcapsules. Upon application of a voltage to the row electrode and the column electrode, a potential difference is generated between an electrode provided on the drive circuit and a counter electrode disposed opposite to the electrode through the microcapsules. As a result, white particles and black particles within the microcapsules migrate by the effect of electric fields generated by the potential difference

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentUS9024981B2Control device, display device, electronic apparatus and controlling method

Publication Date: 2015.05.05 E INK CORP

AI summary

An application control changes a first image displayed with a plurality of pixels composing the entirety or a part of a display section to an image in the first gray level displayed with the plurality of pixels, and thereafter display a second image displayed with the plurality of pixels. Also, the application control device controls an application device such that the numbers of application of the first voltage and the second voltage to each of the plurality of pixels are equal to each other from a state in which each of the plurality of pixels lastly assumes the first gray level before the first image is displayed until a state in which each of the plurality of pixels first assumes the first gray level after the first image is displayed.