Liquid Crystal Display Columnar Projection Misalignment Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid crystal display devices face misalignment issues between upper and lower substrates due to thermal expansion differences, leading to uneven brightness and display failures, particularly in larger screens with varying polarizing plate thicknesses.
Innovation Solution
Incorporating a columnar projection on the opposite substrate that corresponds to the contact hole on the TFT substrate, with specific height and diameter relationships, to anchor and prevent misalignment, while ensuring a consistent cell gap using a columnar spacer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If columnar spacers of different heights are used to reduce frictional resistance between substrates, then misalignment that has occurred can be easily fixed, but occurrence of misalignment between substrates itself cannot be suppressed
Solution Approach 1:
The invention forms a projection structure on the substrate surface before assembling the liquid crystal display device. This projection is preliminarily positioned to engage with a corresponding recess in the opposite substrate, preventing misalignment from occurring in the first place during thermal expansion. The preliminary action of creating this mechanical interlock structure eliminates the need for post-assembly misalignment correction.
Solution Approach 2:
The projection and recess structures act as intermediary mechanical features between the substrates. These intermediary structures provide a physical reference and constraint system that mediates the relationship between substrates with different thermal expansion coefficients, preventing relative displacement while still allowing for the use of columnar spacers of different heights for friction reduction.
2Reliability
If a contact portion area is expanded to form a columnar spacer matching the contact portion, then stable control of panel gap is achieved, but pixel aperture ratio and transmittance are lowered
Solution Approach 1:
The invention divides the substrate surface into distinct functional regions: a small contact portion area for forming the columnar spacer that ensures stable panel gap control, and a larger pixel electrode area for maintaining high aperture ratio. The contact portion is segmented as a separate functional element with specific area constraints, allowing it to be optimized independently from the pixel aperture requirements.
Solution Approach 2:
The invention applies local quality by creating a localized contact portion with specific geometric properties (area and shape) that differ from the surrounding pixel regions. This local area is optimized for mechanical stability and spacer formation, while the rest of the substrate maintains optimal characteristics for light transmission and pixel performance.
3Manufacturing precision
If a concave part of multilayer structure film is used to position columnar spacer, then positional variation of spacer is suppressed, but the concave part occupies significantly large region and lacks step structure for accurate positioning
Solution Approach 1:
The invention employs asymmetric geometric structures: a projection with a specific cross-sectional shape (different from circular) that engages with a corresponding asymmetric recess. This asymmetric design provides inherent directional guidance and precise positioning without requiring a large symmetric concave area, achieving high manufacturing precision with minimal space consumption.
Solution Approach 2:
The invention transitions from a two-dimensional concave area approach to a three-dimensional projection-recess interlocking system. By adding the vertical dimension with the projection height and creating a complementary recess, precise positioning is achieved through geometric constraint in multiple dimensions rather than relying on the lateral extent of a concave part.
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
Effectively suppresses misalignment between substrates, preventing uneven brightness and ensuring a stable cell gap, thereby improving image quality and maintaining pixel aperture ratio.
Implementation Method 1
when a temperature change occurs between upper and lower substrates due to a use environment condition or lighting of a backlight, because rates of thermal expansion of the upper and lower substrates are different, misalignment of one substrate to another substrate in a surface direction occurs
Implementation Method 2
reduction of a frictional resistance between the substrate and an opposite substrate is attempted with a taller spacer
Data Source
AI summary
A display device includes a first substrate having a plurality of TFTs, a passivation film, and a plurality of pixel electrodes, and a second substrate arranged with a gap with the first substrate. The passivation film has a plurality of contact holes, and the plurality of pixel electrodes are connected to the plurality of TFTs via the plurality of contact holes. The second substrate has a plurality of columnar spacers for ensuring the gap with the first substrate, and a plurality of columnar projections for misalignment prevention formed at positions corresponding to the contact holes. The number of the plurality of columnar projections is less than the number of the plurality of columnar spacers.