Dual Passivation Layer Structure for LCD Voltage Holding Ratio
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Solution Overview
Problem
Conventional LCDs face challenges in maintaining a high Voltage Holding Ratio (VHR) when reducing drive frequency, leading to screen flicker and reduced aperture ratio due to the need for additional TFTs and signal lines to adjust parasitic capacitance.
Innovation Solution
The use of a dual passivation layer structure in the array substrate, where the first passivation layer is between the pixel and common electrode, and the second passivation layer is between the common electrode and data line, allows for independent control of storage and parasitic capacitance without introducing additional TFTs or signal lines, thereby maintaining high VHR and aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive frequency is reduced to save power, then energy consumption decreases, but the Voltage Holding Ratio (VHR) becomes low causing screen flicker
Solution Approach 1:
The patent changes the physical parameter of passivation layer thickness to control capacitance values. By setting the first passivation layer thickness to 6500Å or less and the second passivation layer thickness to 1500-5000Å, the invention dynamically adjusts the storage capacitance and parasitic capacitance to maintain VHR at low drive frequencies without increasing power consumption
Solution Approach 2:
The invention creates a dynamic capacitance control system where the dual passivation layer structure enables automatic adjustment of storage and parasitic capacitance based on drive frequency conditions, allowing the system to adapt to different operating states and maintain stable performance
2Reliability
If additional TFTs and signal lines are introduced to adjust parasitic capacitance, then VHR is maintained, but the aperture ratio is reduced affecting display quality
Solution Approach 1:
The patent transitions from a planar capacitor design to a multi-layer vertical structure by introducing a dual passivation layer system. This dimensional change allows independent control of storage capacitance (first passivation layer) and parasitic capacitance (second passivation layer) without requiring additional lateral space, thereby maintaining aperture ratio while achieving VHR control
Solution Approach 2:
The invention segments the capacitance control function into two independent passivation layers with different thickness ranges. The first passivation layer (6500Å or less) controls storage capacitance while the second passivation layer (1500-5000Å) controls parasitic capacitance, allowing separate optimization of each capacitance component without interfering with each other or requiring additional circuit elements
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 solution effectively maintains high VHR and aperture ratio by maximizing parasitic capacitance within a reasonable range, preventing screen flicker and ensuring normal data line function without affecting display quality.
Implementation Method 1
a parasitic capacitor Cst1 is formed between the common electrode line 103 and the pixel electrode 105
Implementation Method 2
the parasitic capacitor Cst2 is formed between the electrode 104 and the pixel electrode 105
Data Source
AI summary
An array substrate and a display device are disclosed. The array substrate includes: a TFT, a pixel electrode layer driven by the TFT, a data line, a first passivation layer and a common electrode layer disposed on a substrate, the data line is for driving the TFT, the first passivation layer is disposed between the pixel electrode layer and the common electrode layer, the array substrate further includes a second passivation layer disposed between the common electrode layer and the data line and located in a region corresponding to the data line.