Transflective LCD Optical Stack for Wide Viewing Angles
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Solution Overview
Problem
Existing transflective liquid crystal display devices suffer from poor viewing angle characteristics and high costs, particularly when used as in-cell type touch panels, and they exhibit insufficient brightness and viewability in varying illuminance environments.
Innovation Solution
A transflective liquid crystal display device with a configuration that includes a first and second phase difference layer, each comprising λ/2 and λ/4 plates, and a positive C plate, with electrodes on one substrate, and a liquid crystal layer with positive dielectric anisotropy, allowing for both reflective and transmissive modes, and incorporating a touch sensor function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transmissive liquid crystal display device is used, then brightness is sufficient in low illuminance environments, but viewability deteriorates in high illuminance environments such as outdoors under direct sunlight
Solution Approach 1:
The display device dynamically switches between transmissive and reflective modes based on ambient illuminance conditions. In low illuminance environments, the device operates in transmissive mode to provide sufficient brightness. In high illuminance environments, it switches to reflective mode to maintain viewability by utilizing reflected ambient light, thus adapting to varying lighting conditions.
Solution Approach 2:
The liquid crystal display device is designed with multi-functionality to perform both transmissive and reflective display modes within the same device structure. This allows the device to universally function in diverse illuminance environments, combining the advantages of both transmissive (brightness) and reflective (viewability in bright conditions) modes.
2Object-affected harmful factors
If a reflective liquid crystal display device is used, then viewability is good in high illuminance environments, but brightness becomes insufficient in low illuminance environments such as indoors or at night
Solution Approach 1:
The device dynamically adapts its display mode based on ambient lighting conditions. In high illuminance environments, it utilizes reflective mode to achieve good viewability by reflecting ambient light. In low illuminance environments, it switches to transmissive mode to maintain sufficient brightness, thus dynamically optimizing performance for different conditions.
Solution Approach 2:
The display device incorporates multi-functional capabilities to operate in both reflective and transmissive modes, enabling it to universally adapt to various illuminance conditions. This multi-functionality allows the device to maintain optimal performance whether used outdoors in bright light or indoors in dim lighting.
3Adaptability or versatility
If existing transflective liquid crystal display devices are used as in-cell type touch panels, then both reflective and transmissive modes are achieved, but viewing angle characteristics become poor and cost increases
Solution Approach 1:
The display device applies local quality optimization by configuring different optical characteristics in different regions. The liquid crystal layer and optical films are designed with specific properties that enhance viewing angle characteristics in the reflective region while maintaining transmissive mode capability, thereby improving overall adaptability without excessive complexity.
Solution Approach 2:
The device utilizes parameter changes in the liquid crystal layer, such as controlling the twist angle and pretilt angle, to optimize both reflective and transmissive display characteristics. By carefully adjusting these parameters, the device achieves good viewing angle characteristics while maintaining the transflective functionality, reducing the need for complex additional structures.
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 device provides excellent viewing angle characteristics and functionality as an in-cell type touch panel at a low cost, with improved viewability in any environment by combining reflective and transmissive modes.
Implementation Method 1
a liquid crystal layer between the substrates, and a pair of electrodes on one substrate to generate a transverse electrical field in the liquid crystal layer
Implementation Method 2
a reflective layer on the first substrate in a reflective region of each pixel
Implementation Method 3
a first phase difference layer including a λ/2 plate and a λ/4 plate, and a second phase difference layer including a λ/2 plate and a λ/4 plate
Data Source
AI summary
A transflective liquid crystal display device provided with a plurality of pixels, and includes: a first polarizer, a first phase difference layer, a first substrate, a liquid crystal layer, a second substrate, a second phase difference layer, and a second polarizer. The first substrate includes a reflective layer. The first phase difference layer includes a first λ/2 plate and a first λ/4 plate. The second phase difference layer includes a second λ/2 plate and a second λ/4 plate. At least one of the first phase difference layer and the second phase difference layer further includes a positive C plate. The liquid crystal layer takes a twist alignment when no voltage is applied. Each of the plurality of pixels includes a reflective region in which light is reflected by the reflective layer to perform display and a transmissive region in which light is transmitted to perform display.