Conductive Element for Liquid Crystal Display Short-Circuit Prevention
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Solution Overview
Problem
In liquid crystal display panels using lateral electric field schemes, such as FFS, coverage defects in the insulating film can lead to short-circuits between electrodes due to level differences and exposed edge faces of switching device electrodes, compromising the manufacturing process and display performance.
Innovation Solution
A conductive element configuration with a first conductive film, a first insulating film exposing its edge face, a second insulating film covering the first, and an upper conductive film with openings that avoid overlapping with the edge face, preventing short-circuits by ensuring the upper conductive film is not disposed above overlapping locations, and enhancing the aperture ratio and orientation control of liquid crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel electrode connects to the switching device via a contact hole exposing the electrode edge face, then electrical connection is achieved, but level differences form in the insulating film making coverage defects more likely
Solution Approach 1:
The patent introduces a new spatial dimension by placing the common electrode in a different layer above the pixel electrode, separated by an insulating film. This vertical layering resolves the short-circuit risk by eliminating planar overlap between conductive elements while maintaining necessary electrical connections through controlled contact holes.
Solution Approach 2:
The insulating film acts as an intermediary barrier between the pixel electrode and common electrode. By positioning the common electrode opening to overlap the edge face region in plan view, the insulating film prevents direct contact while allowing the electrode edge face to serve as a reliable connection point, thus mediating between electrical connection requirements and short-circuit prevention.
2Area of stationary object
If the common electrode is disposed above overlapping locations in plan view, then aperture ratio is enhanced, but short-circuits occur due to insulating film coverage defects
Solution Approach 1:
The patent utilizes vertical layering to resolve the contradiction between maximizing aperture ratio and preventing short-circuits. By positioning the common electrode in an upper layer with openings that overlap the pixel electrode's edge face region in plan view, the design maximizes the effective aperture area while the insulating film in the vertical dimension prevents electrical short-circuits.
Solution Approach 2:
The patent applies local quality by specifically positioning the common electrode opening to overlap the edge face region of the pixel electrode rather than the central region. This localized positioning strategy maximizes aperture ratio while concentrating the potential short-circuit risk to a specific area that is managed by the insulating film's coverage properties.
3Reliability
If the edge face of the switching device electrode is exposed in the contact hole, then electrical connection is improved, but level differences increase making coverage defects more likely
Solution Approach 1:
The insulating film serves as an intermediary that bridges the level difference created by exposing the electrode edge face. By designing the common electrode opening to overlap this exposed edge face region, the patent allows the insulating film to fill and cover the level difference, maintaining electrical connection reliability while managing the complexity of insulating film formation through precise opening placement.
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 configuration effectively prevents short-circuits between conductive films, simplifies the manufacturing process, and enhances the aperture ratio and transmittance of liquid crystal display elements by controlling the orientation of liquid crystals.
Implementation Method 1
a pair of electrodes are disposed on one of the substrates, the TFT substrate, separated by an insulating film, with the electric field for driving the liquid crystal being generated between this pair of electrodes
Implementation Method 2
the direction of the electric field applied to the liquid crystal is generally parallel to the substrate surface, which makes it possible to improve visual characteristics
Data Source
AI summary
A conductive element includes: a first conductive film; a second conductive film connected to the first conductive film; a first insulating film covering the first conductive film and disposed in a layer below the second conductive film, the first insulating film having a contact hole exposing at least an edge face of the first conductive film and thereby connecting the second conductive film to the first conductive film; a second insulating film disposed in a layer above the second insulating film so as to straddle the contact hole; and a third conductive film disposed in a layer above the second conductive film with the second insulating film between the second and third conductive films, the third conductive film having a conductive film opening that contains a location overlapping the edge face of the first conductive film in a plan view.