Shield Electrode Design for LCD Peripheral Noise and Sealing
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Solution Overview
Problem
Liquid crystal display devices with in-plane electric field systems face issues with view angle characteristics and reliability due to potential fluctuations and noise effects at the periphery of the display region, particularly caused by the interaction between ITO films and sealants, leading to incomplete shielding and sealing problems.
Innovation Solution
A liquid crystal display device design where scanning line leads are covered by a shield electrode with a potential identical to the first electrode, and an insulative film is placed between the shield electrode and the sealant, ensuring continuous coverage and preventing charging effects, while maintaining sealing reliability by avoiding direct contact between the ITO film and the sealant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If scanning line leads are covered with ITO conductive film to reduce noise effects, then shielding effect is improved, but adhesion between ITO and sealant deteriorates causing sealing reliability problems
Solution Approach 1:
An insulative film is introduced as an intermediary layer between the ITO conductive film and the sealant. This mediator prevents direct contact between the two materials, eliminating the adhesion problem while preserving the shielding effect of the ITO film against noise from scanning line leads.
Solution Approach 2:
The structure is segmented into distinct functional layers: the ITO conductive film for shielding, the insulative film for isolation, and the sealant for sealing. This segmentation allows each layer to perform its specific function without interfering with adjacent layers, resolving the conflict between shielding and sealing reliability.
2Area of stationary object
If frame at periphery is reduced to enlarge display screen, then display area is improved, but potential fluctuation effects at periphery worsen
Solution Approach 1:
The shield electrode structure is designed to preemptively counteract potential fluctuation effects at the periphery before they can affect the display. By extending the shielding coverage to the peripheral regions where frame has been reduced, the system prevents harmful potential fluctuations from developing.
Solution Approach 2:
The potential fluctuation effects that arise from reducing the frame are converted into a benefit through the shield electrode design. The same peripheral region that becomes more susceptible to noise due to frame reduction is simultaneously equipped with enhanced shielding, turning the vulnerability into an opportunity for improved noise management.
3Object-affected harmful factors
If shield electrode extends below sealant to cover scanning line leads, then shielding coverage is improved, but sealing structure complexity worsens
Solution Approach 1:
The insulative film serves multiple functions simultaneously: it provides electrical isolation between the conductive ITO film and the sealant, maintains the shielding effectiveness of the shield electrode, and simplifies the sealing structure by eliminating the need for separate isolation structures. This multi-functionality reduces overall complexity while improving shielding.
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 effectively prevents blanking phenomena at the display region's periphery by shielding scanning signals and maintains reliable sealing, enhancing the display's view angle characteristics and overall performance.
Implementation Method 1
a shield electrode formed coplanar with the first electrode is extended as far as a portion below the sealant while covering the scanning line leads
Implementation Method 2
an insulative film is placed between the shield electrode and the sealant
Implementation Method 3
an IPS (in plane switching system) of operating liquid crystal molecules by an electric field in a horizontal direction has excellent characteristics
Data Source
AI summary
A liquid crystal display device includes a TFT substrate having a display region with first and second electrodes, TFTs, scanning signal lines connected to the TFTs, a counter substrate, a liquid crystal layer sandwiched between the TFT and counter substrates, and sealed by a sealant, scanning line leads connected to the scanning signal lines and formed outside of the display region, video signal line leads connected to the video signal lines and formed outside of the display region and a shield electrode formed on the TFT substrate covering the scanning line leads but not the video signal line leads. The second electrode is connected to one of the TFTs, and liquid crystal molecules of the liquid crystal layer are driven by an electric field, which is generated between the first and second electrodes. The shield electrode is electrically connected to the first electrode and overlapped with the sealant in plan view.