Liquid Crystal Display with Reflective Area Reducing Power
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Solution Overview
Problem
The power consumption of liquid crystal display devices increases with larger screen sizes, limiting their usage time, especially in portable electronic devices, due to inefficient energy management in active matrix liquid crystal display devices using lateral electric fields.
Innovation Solution
The liquid crystal display device incorporates a transmissive and reflective display area with a common electrode extending over both areas, a thinner liquid crystal layer in the reflective area to impart a phase difference, and a retardation plate between the polarizer and substrate in the reflective area, optimizing electric field alignment and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lateral electric field mode (IPS or FFS) is used in active matrix liquid crystal display devices, then switching performance and viewing angles are improved, but power consumption increases
Solution Approach 1:
The patent applies different liquid crystal layer thicknesses to different display regions: a first thickness in the transmissive display area and a second (thinner) thickness in the reflective display area. This local differentiation allows optimization of optical performance and power consumption in each region, reducing overall power consumption while maintaining switching performance.
Solution Approach 2:
The patent changes the thickness parameter of the liquid crystal layer between different display areas. By setting the liquid crystal layer thickness to be thinner in the reflective display area compared to the transmissive display area, the patent optimizes the optical path and reduces the energy required for liquid crystal switching, thereby lowering power consumption while maintaining display quality.
2Area of stationary object
If the screen size becomes larger, then display area and resolution are improved, but power consumption increases
Solution Approach 1:
The patent divides the display into different regions (transmissive and reflective areas) with different liquid crystal layer thicknesses. The reflective display area uses a thinner liquid crystal layer, which reduces the energy required for switching and lowers overall power consumption, allowing for larger screen sizes without proportionally increasing power consumption.
Solution Approach 2:
The patent utilizes different operating modes (transmissive and reflective) that can be activated based on environmental lighting conditions. The reflective mode, with its thinner liquid crystal layer and no backlight requirement, consumes less power and can be periodically activated in suitable lighting conditions, reducing average power consumption for larger displays.
3Use of energy by moving object
If a reflective display area is added to reduce power consumption, then energy usage is reduced, but device complexity increases
Solution Approach 1:
The patent combines transmissive and reflective display areas within a single liquid crystal display device structure. By integrating both display modes in one device with a common electrode configuration and shared liquid crystal layer, the patent reduces overall device complexity compared to having separate transmissive and reflective display units, while still achieving reduced power consumption through the reflective area.
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 configuration reduces power consumption by allowing the liquid crystal display device to operate with reduced energy usage, eliminating the need for a backlight in the reflective area and enhancing viewing angles and display quality while maintaining high transmittance and resolution.
Implementation Method 1
the liquid crystal layer being configured to have a less thickness in the reflective display area than in the transmissive display area, to impart a phase difference of 1/4 wavelength to light passing at an OFF time in the reflective display area
Implementation Method 2
liquid crystal molecules are switched by a lateral electric field which is substantially parallel to a major surface of the array substrate
Implementation Method 3
a retardation plate disposed between the second polarizer and the second substrate in the reflective display area, and configured to impart a phase difference of 1/2 wavelength
Data Source
AI summary
According to one embodiment, a liquid crystal display device includes a first substrate including a transmissive pixel electrode disposed in a transmissive display area, and a reflective pixel electrode with a planar plate shape which is disposed in a reflective display area, a second substrate including a common electrode, a liquid crystal layer being configured to have a less thickness in the reflective display area than in the transmissive display area, to impart a phase difference of ¼ wavelength to light passing at an OFF time in the reflective display area, and to impart no phase difference to light passing at an ON time in the reflective display area, and a retardation plate disposed between a second polarizer and the second substrate in the reflective display area.