Display Device Watermark Encoding via Modulated Cell Walls

Solution Overview

Problem

Existing display devices lack effective measures to distinguish between watermark and non-watermark areas, which is essential for security and decorative purposes, as they often rely on uniform cell sizes and shapes that do not provide sufficient visual differentiation.

Innovation Solution

The display device incorporates modulated display cells in the watermark area by varying wall width, thickness, or shape compared to the non-watermark area, allowing for distinguishable features that are only visible at certain angles or under specific lighting conditions, without interfering with regular image display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform cell sizes and shapes are used across the entire display surface, then manufacturing is simplified and consistency is maintained, but the ability to create distinguishable watermark areas is lost

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidwatermark distinguishability

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The patent applies local quality by creating display cells with different wall thicknesses in different regions of the display. Specifically, the watermark area contains display cells with first wall thicknesses while the non-watermark area contains display cells with second wall thicknesses. This allows the watermark information to be encoded locally without changing the overall manufacturing process, resolving the contradiction between manufacturing simplicity and watermark distinguishability.

Inventive Principle:

Principle #3Local quality

2Reliability

If display cell parameters are varied to create watermark areas, then security and decorative features are enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvesecurity against counterfeitingVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements parameter changes by varying the wall thickness parameter of display cells to create distinguishable watermark areas. The watermark area contains display cells with first wall thicknesses while the non-watermark area contains display cells with second wall thicknesses. This approach enhances security and decorative features through a single geometric parameter modification, avoiding the need for complex multi-parameter variations and keeping manufacturing relatively simple.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If thicker walls are used in watermark areas, then watermark visibility is improved, but the display cell volume for active material decreases

Engineering Contradiction:

Improvewatermark visibilityVSAvoiddisplay cell volume

Core Design Contradiction:

Illumination intensityVSVolume of moving object

Solution Approach 1:

The patent applies local quality by creating display cells with different wall thicknesses in different regions of the display. Specifically, the watermark area contains display cells with first wall thicknesses while the non-watermark area contains display cells with second wall thicknesses. This allows the watermark information to be encoded locally without changing the overall manufacturing process, resolving the contradiction between manufacturing simplicity and watermark distinguishability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2856460B1Display device with watermark

Publication Date: 2017.11.22 E INK CALIFORNIA LLC

Figure 1
Figure 2
Figure 3

AI summary

The present invention is directed to display devices comprising a watermark area and a non-watermark area. The watermark aims to protect against counterfeiting or to be used for decoration purposes. The watermark is visible at certain viewing angles and/or under certain lighting conditions and it does not interfere with displaying of the regular images.