Transflective Display Mode Switching via Liquid Crystal Inversion Frequency
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Solution Overview
Problem
Transflective display devices face challenges in reducing power consumption while maintaining visibility under external light and avoiding flicker, as they require a backlight for dark environments, leading to increased power consumption and user discomfort due to low driving speeds.
Innovation Solution
A display device with a liquid crystal layer, transparent electrode, and reflective electrode, where the reflective electrode is divided into pixel electrodes with openings, allowing for switching between reflective and transmissive display modes by adjusting the liquid-crystal inversion frequency, enabling efficient power use and reduced flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thickness of the liquid crystal layer in the transmissive display area is made approximately twice that of the reflective display area, then the phase differences are equalized between transmitted and reflected light, but the aperture ratio in the reflective display area is reduced and the screen becomes darker in room environments
Solution Approach 1:
The patent employs dynamic control of the liquid crystal layer thickness through a variable optical path length mechanism. By adjusting the thickness of the liquid crystal layer in the transmissive display area dynamically, the system can equalize phase differences between transmitted and reflected light while maintaining adequate aperture ratio and screen brightness in different viewing environments.
2Use of energy by moving object
If the drive circuit operates at low speed with inversion frequency lower than 30 Hz, then power consumption is reduced, but flicker occurs causing user discomfort
Solution Approach 1:
The patent utilizes periodic action by operating the drive circuit at optimized inversion frequencies that balance power consumption and flicker reduction. By carefully selecting the inversion frequency timing and duration, the system achieves low power consumption operation while maintaining display stability and user comfort through rhythmic refresh cycles that avoid the critical flicker fusion threshold.
3Illumination intensity
If the backlight is turned on to perform transmissive display, then visibility in dark environments is improved, but power consumption increases
Solution Approach 1:
The patent implements multi-functionality by designing the display device to operate in multiple modes (reflective mode and transmissive mode) using the same hardware components. The liquid crystal layer serves both reflective and transmissive functions, allowing the system to adapt to different lighting environments without requiring separate display systems, thereby reducing overall power consumption while maintaining visibility across various conditions.
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 allows for reduced power consumption and minimized flicker, enabling effective display in both reflective and transmissive modes, improving user experience and visibility in various lighting conditions.
Implementation Method 1
The reflective electrode is arranged on a side of the liquid crystal layer opposite to the transparent electrode and reflects light reaching from the liquid crystal layer
Implementation Method 2
The pixel is configured to display black when a same potential is applied between the pixel electrode and the transparent electrode and display white when a predetermined voltage difference is applied between the pixel electrode and the transparent electrode
Data Source
AI summary
According to an aspect, a display device includes a liquid crystal layer, a transparent electrode, a reflective electrode, a drive circuit, and a controller. The controller is configured to switch a mode between a first mode for driving the drive circuit at a liquid-crystal inversion frequency of a first frequency so that screen display using light reflected by the reflective electrode is performed and a second mode for driving the drive circuit at a liquid-crystal inversion frequency of a second frequency higher than the first frequency so that screen display using light passing through the opening of the reflective electrode is performed.