Liquid Crystal Display Subpixel Voltage Control for Side Visibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vertical alignment (VA) mode liquid crystal displays have lower side visibility compared to front visibility, which is addressed by dividing one pixel into two subpixels and applying different voltages to them without reducing the aperture ratio or decreasing luminance.
Innovation Solution
A liquid crystal display design featuring a substrate with a common voltage line, pixel electrodes, thin film transistors, and a boosting capacitor, where the common voltage line is formed in the same layer as the third source electrode and is electrically connected to it, allowing for differential voltage application between subpixels through capacitive coupling, enhancing side visibility without reducing luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If one pixel is divided into two subpixels with different voltages applied, then side visibility is improved, but device complexity increases due to additional voltage control requirements
Solution Approach 1:
The pixel is divided into two subpixels (first subpixel electrode and second subpixel electrode) that can be independently controlled with different voltages. This segmentation allows different voltage levels to be applied to adjacent regions, creating a gradient effect that improves side visibility while maintaining manufacturing simplicity through the use of existing TFT and capacitor structures
Solution Approach 2:
The invention changes the voltage parameter by using a boosting capacitor to create different voltage levels (Vdata and Vdata+ΔV) for the two subpixels. This parameter differentiation is achieved through controlled charging/discharging cycles of the capacitor during specific time periods, allowing voltage modulation without additional hardware complexity
2Ease of manufacture
If a boosting capacitor is used to differentiate voltages between subpixels, then side visibility is improved, but device complexity increases due to additional capacitor structures
Solution Approach 1:
The boosting capacitor serves multiple functions: it stores charge for voltage differentiation, acts as a temporary energy reservoir during voltage transitions, and enables the generation of different voltage levels for adjacent subpixels. By making the capacitor multi-functional, the invention avoids needing separate structures for each function, thereby reducing overall device complexity
Solution Approach 2:
The capacitor is pre-charged to a specific voltage level during a first time period before the actual voltage differentiation is needed. This preliminary charging action prepares the system in advance, allowing the second subpixel to receive a differentiated voltage during the second time period without requiring complex real-time voltage generation circuitry
3Ease of manufacture
If different voltages are applied to subpixels through capacitive coupling, then side visibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention merges the common voltage line with the source electrode layer, forming a multi-functional structure that serves as both a voltage reference and an electrode connection. This merging reduces the number of separate components and interfaces that would otherwise require high manufacturing precision, while still enabling the desired capacitive coupling effect between subpixels
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 design improves side visibility by allowing the charged voltage of one subpixel to be decreased and the other to be increased, maintaining equivalent luminance and aperture ratio, thus approximating the gamma curve of front visibility from the side.
Implementation Method 1
a boosting capacitor connected to the first subpixel electrode
Implementation Method 2
applying voltages to the field-generating electrodes to generate an electric field in the LC layer that determines the orientations of LC molecules therein to adjust polarization of incident light
Implementation Method 3
a light alignment method in which the alignment direction of the liquid crystal molecules and the alignment angle are controlled by irradiating light on the alignment layer
Data Source
AI summary
A liquid crystal display includes a substrate; a common voltage line formed on the substrate and transmitting a common voltage; a pixel electrode formed on the common voltage line and including a first subpixel electrode and a second subpixel electrode; a first thin film transistor connected to the first subpixel electrode, and including a first gate electrode, a first source electrode, and a first drain electrode; a second thin film transistor connected to the second subpixel electrode, and including a second gate electrode, a second source electrode, and a second drain electrode; a boosting capacitor connected to the first subpixel electrode; a third thin film transistor connected to the common voltage line and the boosting capacitor, and including a third gate electrode, a third source electrode, and a third drain electrode; and a fourth thin film transistor connected to the second subpixel electrode and the boosting capacitor, wherein the common voltage line is formed in the same layer as the third source electrode, and is electrically connected to the third source electrode.