MIS Storage Capacitor Polysilicon Flicker Reduction
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Solution Overview
Problem
Flicker in LCDs is exacerbated by the difference in leakage between positive and negative gray scale voltages due to TFT storage capacitor capacity differences, which worsens with lower source drive voltages used to reduce power consumption.
Innovation Solution
An array substrate design incorporating a MIS storage capacitor formed by a polycrystalline semiconductor layer and metal layers with an insulating layer in between, where the polycrystalline semiconductor layer is heavily doped with Be, allowing the capacity to vary with gray scale voltage, reducing leakage by forming a cavity or blocking layer depending on voltage polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lower source drive voltage is applied to reduce power consumption, then power consumption is reduced, but the gray scale voltage difference between adjacent gray scales is reduced and flicker is aggravated
Solution Approach 1:
The patent changes the electrical parameters of the storage capacitor by heavily doping the polysilicon layer with Be to achieve high conductivity type. This parameter change allows the capacitor to maintain sufficient voltage difference for driving liquid crystal at lower source voltages while reducing flicker through the formation of blocking layers that prevent charge leakage.
Solution Approach 2:
The patent replaces the conventional storage capacitor structure with a MIS (Metal-Insulator-Semiconductor) type capacitor using heavily doped polysilicon. This substitution creates a system where electrical field effects and semiconductor physics replace traditional capacitor designs, enabling better performance at lower voltages.
2Reliability
If the storage capacitor applies positive and negative gray scale voltage, then the capacitor functions to store charge, but difference leakage is formed because leakage applying negative gray scale voltage is bigger than positive gray scale voltage
Solution Approach 1:
The patent converts the harmful effect of voltage polarity-dependent leakage into a beneficial mechanism by utilizing the semiconductor properties of heavily doped polysilicon. The high doping concentration creates blocking layers that prevent leakage, transforming what would be a defect into a functional advantage for charge storage stability.
Solution Approach 2:
The patent employs a composite structure combining metal electrodes, insulator layers, and heavily doped polysilicon semiconductor material. This composite MIS capacitor structure leverages the properties of each material to achieve low leakage and stable charge storage, with the polysilicon layer serving as both the semiconductor active layer and the capacitor electrode.
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 design reduces the capacity difference between positive and negative gray scale voltages, thereby mitigating flicker and ensuring improved display quality.
Implementation Method 1
the polycrystalline semiconductor layer is heavily doped with Be
Implementation Method 2
form a MIS storage capacitor of the array substrate
Data Source
AI summary
An array substrate, a liquid crystal display panel and a liquid crystal display device of the present disclosure provided are designed to form a MIS storage capacitor by the polycrystalline semiconductor layer, the first metal layer and the insulating layer between the two or the polycrystalline semiconductor layer, the second metal layer and the insulating layer between the two. When one side of the first metal layer or the second metal layer is receiving the negative gray scale voltage, a P—Si in the polycrystalline semiconductor layer will gather to form a cavity, when receiving the positive gray scale voltage, a blocking layer will be formed on the P—Si to reduce the capacity of the MIS storage capacitor.