Chip on Glass HIRF Shielding via Internal Enclosure
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Solution Overview
Problem
Active Matrix Liquid Crystal Displays (AMLCDs) are vulnerable to damage from High Intensity Radiated Fields (HIRF) due to inadequate shielding, as current technologies like Indium Tin Oxide (ITO) coatings and wire mesh are insufficient against enhanced HIRF threats, allowing electromagnetic energy to penetrate and affect internal electronics.
Innovation Solution
A multilayer stackup on the AMLCD glass incorporating an impedance-controlled stripline cavity with internal conductive elements forms an enclosure around chip-on-glass traces, providing additional shielding and minimizing loop areas to protect driver chips from external threats, while allowing ITO trace layers for interconnecting flex cables and LCD cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO coating, wire mesh or micromesh is used to shield internal electronics from HIRF, then shielding capability is improved, but optical transmission performance deteriorates
Solution Approach 1:
The patent implements nested shielding structures where an internal conductive enclosure is placed within the display assembly, nested between the front glass and the liquid crystal layer. This internal enclosure provides additional shielding that works complementarily with the external ITO/mesh layers, achieving enhanced HIRF protection without requiring thicker external shielding materials that would block light.
Solution Approach 2:
The patent transitions from two-dimensional surface coatings (ITO, mesh) to a three-dimensional volumetric enclosure structure. By creating a conductive box-like enclosure that surrounds the driver circuitry in three dimensions, the shielding effectiveness is dramatically improved without increasing the optical path obstruction, since the enclosure walls are thin and strategically positioned.
2Reliability
If thicker shielding material is used to block HIRF, then protection capability is improved, but display visibility deteriorates
Solution Approach 1:
The internal conductive enclosure is nested within the display's existing structure, utilizing the space between the front glass and liquid crystal layer. This allows the shielding function to be achieved without adding external thickness that would interfere with light transmission to and from the display surface.
Solution Approach 2:
The enclosure is constructed using thin conductive film or shell structures that provide effective electromagnetic shielding while maintaining optical transparency. The thin walls of the enclosure suffice to block HIRF without creating significant optical obstruction, unlike thick bulk shielding materials.
3Device complexity
If driver chips are placed adjacent to the shield with only glass thickness separation, then device integration is improved, but susceptibility to HIRF increases
Solution Approach 1:
The driver chips are nested within the internal conductive enclosure, which is itself nested within the display assembly. This creates a nested protection hierarchy where the chips are surrounded by shielding material on multiple sides, significantly reducing their exposure to HIRF while maintaining compact integration.
Solution Approach 2:
The internal conductive enclosure acts as an intermediary barrier between the driver chips and the external HIRF environment. This intermediary structure provides a protective interface that allows the chips to remain integrated with the display while being isolated from harmful electromagnetic fields.
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
The solution significantly increases the immunity of AMLCDs to HIRF by creating an internal enclosure that effectively shields sensitive driver chips from external electromagnetic interference, enhancing protection beyond existing external shielding methods.
Implementation Method 1
one or a plurality of conductive elements disposed between the first protective conductive coating layer and the second protective conductive coating layer to form an enclosure around the driver layer
Data Source
AI summary
Various circuits may benefit from suitable protection. For example, certain displays, such as active matrix liquid crystal displays, may benefit from enclosures configured to protect driver circuits from high intensity radiated fields. A system can include a first protective conductive coating layer. The system can also include a first insulating layer on the first protective conductive layer. The system can further include a signal conductive layer on the insulating layer. The system can additionally include a driver layer mounted to the signal conductive layer. The system can also include a second insulating layer above the driver layer. The system can further include a second protective conductive coating layer on the second insulating layer. The system can additionally include one or a plurality of conductive elements disposed between the first protective conductive coating layer and the second protective conductive coating layer to form an enclosure around the driver layer.