LCD Sub-Pixel Driving with Non-Overlapping Gate Signals
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Solution Overview
Problem
Liquid crystal displays (LCDs) face challenges in maintaining visibility and transmittance due to the degradation of side visibility caused by refractive anisotropy in liquid crystal materials, particularly when viewing angles are large, and existing methods to address this often result in reduced transmittance and increased complexity with additional signal lines.
Innovation Solution
The implementation of a liquid crystal display (LCD) structure with two sub-pixels and a specific driving method that includes distinct gate lines and switching elements, where the gate-on voltage periods for different gate lines do not overlap, allowing for differential charging of liquid crystal capacitors and a transformation capacitor, thereby improving visibility and transmittance without adding signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If one pixel electrode is divided into two sub-pixel electrodes with different voltages to improve visibility, then side visibility is improved, but transmittance is reduced and device complexity increases
Solution Approach 1:
The pixel electrode is divided into two sub-pixel electrodes (first sub-pixel electrode and second sub-pixel electrode) that can be independently controlled with different voltages. This segmentation allows different voltage applications to compensate for viewing angle effects, improving side visibility while maintaining a manageable structure through the use of existing gate lines.
Solution Approach 2:
Existing gate lines are utilized for multiple purposes: the first gate line controls the first switching element, the second gate line controls the second switching element, and the transformation gate line controls the third switching element. This multi-functionality approach avoids adding new signal lines, thereby improving visibility without significantly increasing device complexity.
2Ease of operation
If signal lines are added to control the second switching element, then sub-pixel voltage control is achieved, but transmittance of the display panel is reduced
Solution Approach 1:
The gate lines are designed to serve multiple functions within the pixel structure. The first gate line and second gate line are used to control different switching elements, while the transformation gate line is used to control the third switching element that manages the transformation capacitor. This approach achieves sub-pixel voltage control without adding dedicated signal lines that would block light and reduce transmittance.
3Productivity
If the first switching element and second switching element are controlled with overlapping gate-on periods, then both sub-pixel electrodes can be charged, but charging problems occur in the sub-pixel electrode connected to the second switching element
Solution Approach 1:
The gate lines are controlled with periodic, non-overlapping timing sequences. The first gate line is activated during a first period to charge the first liquid crystal capacitor, then deactivated. Subsequently, the transformation gate line is activated during a second period to charge the second liquid crystal capacitor through the transformation capacitor. This periodic, sequential control ensures reliable charging of both sub-pixel electrodes without interference or charging problems.
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 approach enhances side visibility and maintains high transmittance by ensuring the liquid crystal capacitors are charged efficiently, reducing the voltage difference and improving luminance uniformity across the display.
Implementation Method 1
A liquid crystal layer typically includes a liquid crystal material having refractive anisotropy. Due to the refractive anisotropy of the liquid crystal material, a change in color and a change in contrast become substantially large according to a viewing angle.
Implementation Method 2
The LCD generates an electric field in a liquid crystal layer by applying voltage to a field generating electrode, determines a direction of liquid crystal molecules of a liquid crystal layer, and controls polarization of incident light
Implementation Method 3
one of two sub-pixel electrodes is connected to a transformation capacitor through a second switching element
Data Source
AI summary
A liquid crystal display, the liquid crystal display comprises a plurality of gate lines which includes a first gate line, a transformation gate line, and a second gate line; a data line; and a pixel, wherein the pixel includes a first liquid crystal capacitor which includes a first sub-pixel electrode and a common electrode and a second liquid crystal capacitor which includes a second sub-pixel electrode and a common electrode; a first switching element connected to the first gate line, the data line, and the first sub-pixel electrode; a second switching element connected to the first gate line, the data line, and the second sub-pixel electrode; a third switching element connected to the transformation gate line and the second switching element; a transformation capacitor which includes a first terminal connected to the second gate line and a second terminal connected to the third switching element; and a first period where a gate-on voltage Von is applied to the first gate line and a second period where the gate-on voltage Von is applied to the transformation gate line do not overlap each other and, a gate-off voltage Voff is applied to the second gate line during the second period.