Active Matrix Display Voltage Control via Storage Transistor
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Solution Overview
Problem
Transmissive type LCDs consume high power and suffer from dark image issues in bright environments, while reflective type LCDs have lower chroma and poor visibility in dark environments, and existing solutions for improving brightness and color shift in VA LCDs either limit pixel aperture or reduce transmittance ratio.
Innovation Solution
An active matrix display device with a plurality of pixels, source buses, gate buses, and a common bus, utilizing driving transistors, storage transistors, and storage capacitors to provide different voltages to liquid crystal units without lowering pixel aperture or transmittance ratio, employing a source voltage selector to switch between internal and external power sources for optimal voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plurality of gate lines and source lines are disposed to provide different voltages to each sub-pixel, then color shift is eliminated and brightness is improved, but pixel aperture area is limited
Solution Approach 1:
The patent merges the voltage control function for multiple sub-pixels into a single gate line by introducing a storage transistor that stores voltage information and sequentially supplies it to multiple liquid crystal units. This consolidation eliminates the need for separate gate lines for each sub-pixel, thereby preventing aperture area reduction while maintaining the ability to provide different voltages to different sub-pixels for color shift correction.
Solution Approach 2:
The storage transistor acts as an intermediary element that receives voltage signals from a single gate line and distributes them to multiple liquid crystal units at appropriate times. This intermediary mechanism enables voltage differentiation across sub-pixels without requiring multiple gate lines, thus preserving pixel aperture area while achieving the desired brightness and color uniformity.
2Ease of manufacture
If an impedance element is coupled to a liquid crystal unit in a particular sub-pixel in parallel, then different voltage can be applied to that sub-pixel, but the upper limit of voltage is lower resulting in lower transmittance ratio
Solution Approach 1:
The patent extracts the impedance element from the circuit configuration, removing the voltage limitation it imposed on liquid crystal units. By eliminating this constraint, the system can apply higher voltages to liquid crystal units in particular sub-pixels, thereby improving transmittance ratio while still enabling different voltage application for color shift correction through the storage transistor mechanism.
3Adaptability or versatility
If one pixel is divided into at least one pair of sub-pixels for light transmission and light reflection, then visibility in different environments is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by enabling a single gate line to control multiple liquid crystal units within a pixel through the storage transistor mechanism. This allows the same physical infrastructure (gate lines) to serve multiple sub-pixels with different voltage requirements, thereby supporting both transmissive and reflective modes without proportionally increasing device complexity.
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
Enables the provision of different voltages to liquid crystal units, enhancing brightness and reducing color shift without compromising pixel aperture or transmittance ratio, thus improving display performance across various environments.
Implementation Method 1
Alignment of liquid crystal molecules varies with variations in voltage applied thereto. A liquid crystal display (LCD) displays images by using the characteristics of the liquid crystal molecules and by transmitting/obstructing external light or backlight light.
Data Source
AI summary
An active matrix display device is provided, in which a plurality of different voltages are applied to a pixel having a plurality of liquid crystal units. The display device is composed of a plurality of pixels arranged in a matrix with rows and columns, and a plurality of gate and source lines corresponding to these pixels. Each of the pixels has at least two liquid crystal units L1˜L3, driving transistors T1˜T3 for controlling current flow from one of the source lines Si and Si+1 to a corresponding liquid crystal unit, a storage transistor connected between control electrodes of the driving transistors T1/T2 and a gate line Gj and operated based on the voltages of the source line Si, and a storage capacitor connected between the control electrodes of the driving transistors T1/T2 and a common line/previous gate line Gj−1 for holding a voltage by the storage transistor.