Reflective Liquid Crystal Display for High-Contrast In-Cell Touch
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Solution Overview
Problem
Existing reflective liquid crystal display devices face challenges in achieving high contrast ratios and practical use as in-cell type touch panels due to low reflectance and decreased contrast when adopting a transverse electrical field mode, particularly in reflective modes.
Innovation Solution
A liquid crystal display device configuration with specific arrangements of substrates, retardation layers, and alignment films, including a λ/4 plate and λ/2 plate, along with positive and negative C plates, to enhance contrast ratio and enable reflection mode display, while using a positive-type or negative-type liquid crystal material with defined twist alignment angles and thickness direction retardation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transverse electrical field mode is adopted for reflective liquid crystal display device, then the device can be configured as in-cell type touch panel, but the reflectance is low and contrast ratio decreases
Solution Approach 1:
The patent changes the electrical field direction parameter from transverse to vertical, and optimizes the liquid crystal alignment angle parameter to achieve high reflectance in reflective mode while maintaining in-cell type touch panel configuration
Solution Approach 2:
The patent employs a composite structure combining vertical alignment liquid crystal layer with specific alignment films and electrode configurations to achieve both high reflectance and touch panel functionality
2Adaptability or versatility
If a transverse electrical field mode is adopted for reflective liquid crystal display device, then the device can be configured as in-cell type touch panel, but the contrast ratio decreases
Solution Approach 1:
The patent changes the electrical field direction parameter from transverse to vertical, and optimizes the liquid crystal alignment angle parameter to achieve high contrast ratio in reflective mode while maintaining in-cell type touch panel configuration
Solution Approach 2:
The patent employs a composite structure combining vertical alignment liquid crystal layer with specific alignment films and electrode configurations to achieve both high contrast ratio and touch panel functionality
3Adaptability or versatility
If vertical electrical field mode is adopted with both electrodes on active matrix substrate side, then in-cell type touch panel can be realized, but the reflectance remains low
Solution Approach 1:
The patent segments the electrode configuration by placing one electrode on the active matrix substrate side and the other electrode on the counter substrate side, which improves light reflection efficiency while maintaining in-cell type touch panel structure
Solution Approach 2:
The patent changes the electrode arrangement from a single-side configuration to a dual-side configuration across different substrates, creating a three-dimensional electrode structure that enhances reflectance
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 proposed configuration improves the contrast ratio and enables low-cost in-cell type touch panels capable of reflection mode display, addressing the limitations of existing reflective liquid crystal display devices.
Implementation Method 1
a liquid crystal layer held between the substrates, the liquid crystal layer includes a positive-type liquid crystal material or a negative-type liquid crystal material, and has a twist alignment when no voltage is applied
Implementation Method 2
a first electrode and a second electrode configured to generate a transverse electrical field in the liquid crystal layer
Implementation Method 3
the retardation layer includes a λ/4 plate and a λ/2 plate
Implementation Method 4
the first substrate includes a reflective layer that reflects light
Implementation Method 5
a first horizontal alignment film that is in contact with the liquid crystal layer, the second substrate includes a second horizontal alignment film that is in contact with the liquid crystal layer
Data Source
AI summary
A liquid crystal display device includes a first substrate, a liquid crystal layer, a second substrate, a retardation layer, and a polarizer in this order from a back face side, and includes a plurality of pixels arrayed in a matrix shape, in which the first substrate includes a reflective layer that reflects light, a first electrode and a second electrode that are capable of generating a transverse electrical field in the liquid crystal layer, and a first horizontal alignment film that is in contact with the liquid crystal layer, the second substrate includes a second horizontal alignment film in contact with the liquid crystal layer, the retardation layer includes a λ/4 plate and a λ/2 plate, the liquid crystal layer includes a positive-type liquid crystal material or a negative-type liquid crystal material, and has a twist alignment when no voltage is applied, and an angle formed by a polarization axis of the polarizer and an alignment direction of liquid crystal molecules defined by the first horizontal alignment film is within a predetermined range.