Liquid Crystal Display Ridges Prevent Alignment Film Scratches

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Solution Overview

Problem

In liquid crystal display devices with active matrix substrates featuring a top gate type oxide semiconductor TFT, the columnar spacers can cause scratches in the alignment film due to external stress, leading to reduced display quality.

Innovation Solution

The implementation of a liquid crystal display device design where the active matrix substrate includes a lower source structure with a top gate type oxide semiconductor TFT, featuring a configuration with first and second ridges on the substrate surface to prevent columnar spacer-induced scratches, and base conductive layers that overlap the source wiring lines to enhance stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a lower source structure is adopted in the active matrix substrate, then the contact hole depth is reduced and yield is improved, but columnar spacers cause scratches in the alignment film due to external stress

Engineering Contradiction:

Improvecontact hole precisionVSAvoidalignment film scratches

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

A protective film is introduced as an intermediary layer between the alignment film and the columnar spacers. This protective film absorbs the mechanical stress and contact pressure from the columnar spacers, preventing scratches on the alignment film while allowing the lower source structure to maintain its manufacturing advantages

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film is formed in advance before the columnar spacers are positioned and before external stress is applied to the device. This pre-positioned protective layer acts as a cushion that prevents direct contact between the columnar spacers and the alignment film, thereby preventing scratches before they can occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Adaptability or versatility

If source wiring lines are positioned above gate wiring lines, then routing flexibility is improved, but deep contact holes are required and substrate flattening becomes difficult

Engineering Contradiction:

Improvewiring routing flexibilityVSAvoidcontact hole depth

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The conventional wiring arrangement is inverted by positioning the source wiring lines below the gate wiring lines instead of above them. This inverted configuration reduces contact hole depth and simplifies substrate flattening while the patent compensates for routing flexibility through alternative wiring design approaches

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11226529B2Liquid crystal display device

Publication Date: 2022.01.18 SHARP KK

AI summary

A liquid crystal display device includes an active matrix substrate, a counter substrate, and a liquid crystal layer. The active matrix substrate includes a top gate type oxide semiconductor TFT a plurality of gate wiring lines a plurality of source and an interlayer insulating layer The counter substrate includes a plurality of columnar spacers provided on a second substrate. Each columnar spacer is disposed in an intersecting region where the gate wiring line and the source wiring line intersect. A front face of the active matrix substrate on the liquid crystal layer side includes a plurality of first ridges overlapping the plurality of gate wiring lines and a plurality of second ridges overlapping the plurality of source wiring lines.