Column Spacer Height Measurement via Refractive Index Contrast

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Solution Overview

Problem

In liquid crystal display (LCD) manufacturing, maintaining accurate cell gaps is challenging due to the difficulty in measuring the height of column spacers, which affects the quality and defect ratio of LCD devices.

Innovation Solution

Incorporating a non-light transmissive material layer with a different refractive index under the column spacer allows for accurate height measurement by reflecting light, improving the manufacturing process and reducing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a column spacer is used to maintain cell gap, then the cell gap can be maintained, but the height measurement of the column spacer becomes difficult

Engineering Contradiction:

Improvecell gap maintenanceVSAvoidcolumn spacer height measurement

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

A non-light transmissive material layer is introduced as an intermediary between the column spacer and the substrate. This layer has a different refractive index from the column spacer, creating a visible interface that enables light-based height measurement methods to accurately determine the column spacer height while maintaining its cell gap function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The non-light transmissive material layer creates a contrast in light transmission properties at the interface with the column spacer. This contrast allows measurement instruments to detect the height of the column spacer by observing light reflection or transmission patterns, solving the measurement difficulty without affecting the spacer's mechanical function

Inventive Principle:

Principle #32Color changes

2Ease of manufacture

If a uniform material is used for the column spacer, then the manufacturing process is simplified, but the height measurement accuracy is reduced

Engineering Contradiction:

Improvecolumn spacer manufacturingVSAvoidcolumn spacer height measurement

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The structure combines the column spacer material with a non-light transmissive material layer having a different refractive index. This composite structure maintains ease of manufacture through sequential deposition processes while enabling accurate height measurement through the refractive index contrast at the material interface

Inventive Principle:

Principle #40Composite materials

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 enhances the accuracy of LCD device manufacturing by enabling precise height measurement of column spacers, thereby improving product quality and reducing defects.

Implementation Method 1

a non-light transmissive material layer under the column spacer, the non-light transmissive material layer being in contact with a lower surface of the column spacer and formed of a non-light transmissive material having a different refractive index from the column spacer

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS10007154B2Liquid crystal display device

Publication Date: 2018.06.26 LG DISPLAY CO LTD

AI summary

Provided is a display device. The display device includes: a TFT array substrate; a column spacer on the TFT array substrate; and a non-light transmissive material layer under the column spacer, the non-light transmissive material layer being in contact with a lower surface of the column spacer and formed of a non-light transmissive material having a different refractive index from the column spacer.