Photo-Addressable Electrochromic Display for Full-Color Passive Applications
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Solution Overview
Problem
Current passive displays, particularly full-color e-papers, face challenges such as poor color purity, low contrast, and limited scalability, along with high manufacturing costs and slow switching times.
Innovation Solution
A photo-addressable reflective display utilizing electrochromic materials controlled by a pair of electrodes, with a photoconductor layer sensitive to infrared light and an infrared filtering material to achieve full-color capabilities and fast switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If liquid crystal displays with multiple stacked layers are used to achieve full-color display, then color capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention divides the display into three separate single-color display regions (red, green, blue) that can be independently controlled by three different infrared wavelengths. Each region contains electrochromic material tuned to respond to a specific wavelength, allowing full-color display through spatial segmentation rather than temporal or stacked layer segmentation.
Solution Approach 2:
The invention transitions from the conventional approach of stacking layers in the vertical dimension to using spectral dimension (wavelength separation) to achieve color differentiation. By using three distinct infrared wavelengths to control three color regions, the patent achieves full-color capability without increasing vertical layer complexity.
2Ease of operation
If active matrix architecture is used to control display pixels, then display functionality is improved, but manufacturing cost and scalability are worsened
Solution Approach 1:
The invention extracts and removes the complex active matrix electrode structure entirely. Instead of using individual addressable electrodes for each pixel, the patent uses a simplified architecture where three continuous electrodes control three color regions through wavelength-selective photoconductors, dramatically reducing manufacturing complexity while maintaining display functionality.
Solution Approach 2:
The three electrodes in the invention serve multiple functions: they act as both control electrodes for color selection and as reflective surfaces for display. Each electrode is associated with a specific color region and wavelength, allowing single electrodes to perform what would traditionally require multiple specialized components.
3Ease of operation
If conventional photoconductive materials are used that are sensitive to visible light, then addressing capability is improved, but cross-talk between adjacent pixels increases
Solution Approach 1:
The invention applies local quality by making each photoconductive material selective to a specific infrared wavelength range. The red region photoconductor responds only to red infrared wavelength, green to green infrared, and blue to blue infrared, creating localized spectral responsiveness that prevents cross-talk between adjacent color regions while maintaining effective light addressing capability.
4Use of energy by stationary object
If electrochromic materials are used for passive display, then energy consumption is reduced, but switching speed is worsened
Solution Approach 1:
The invention uses periodic pulsed infrared illumination to drive the electrochromic switching. By applying short duration infrared pulses at appropriate intervals, the system achieves fast effective switching while maintaining the low energy consumption characteristics of passive electrochromic displays, as the materials only need to switch state during the pulse duration rather than maintaining continuous power.
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
The solution enables the creation of full-color passive displays with improved color purity, contrast, and scalability, while reducing manufacturing costs and achieving rapid image changes, suitable for both indoor and outdoor applications.
Implementation Method 1
an organic photosensitive layer capable of absorbing addressing light, generating a charge carrier and enabling a current flow between two electrodes
Implementation Method 2
Light driven electrochromic display... a light modulation layer comprising liquid crystals
Data Source
AI summary
The present invention concerns a photo-driven display, reflective display comprising first and second electrode layers, a photoconductor layer, provided between said electrode layers, said photoconductor layer comprising a material that is sensitive to infrared light, and an electrochromic material layer.