Inkjet Nozzle Selection for Uniform Quantum Dot Ink Distribution

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Solution Overview

Problem

Inkjet printing processes for display devices like LCD, PDP, and LED panels face luminance non-uniformity and yield reduction due to uneven mixing of additives in quantum dot ink across nozzles, leading to mura (uneven patterns).

Innovation Solution

A substrate processing method and apparatus that calculate the density of ink patterns formed by multiple nozzles and select nozzles to achieve uniform ink distribution within pixel areas based on calculated grayscale values, ensuring consistent inkjetting across the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If quantum dot ink with various organic/inorganic substances is used to improve function, then the functionality of the ink is enhanced, but the additives are not uniformly mixed inside the inkjet head causing density differences between nozzles

Engineering Contradiction:

ImprovefunctionalityVSAvoiduniformity of ink distribution

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system performs preliminary measurement of ink density for each nozzle before actual printing. By calculating the density of ink patterns jetted by each nozzle in advance, the system identifies nozzles with non-uniform ink distribution and adjusts their usage accordingly, preventing mura defects before they occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the operational parameters of individual nozzles based on measured ink density. By selecting or excluding specific nozzles for jetting into pixel areas based on their calculated grayscale values, the system compensates for variations in ink additive concentration and achieves uniform overall ink distribution

Inventive Principle:

Principle #35Parameter changes

2Productivity

If ink is jetted by multiple nozzles to form ink patterns, then printing productivity is improved, but density differences between nozzles cause luminance non-uniformity and mura

Engineering Contradiction:

Improveprinting speedVSAvoidluminance uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system applies local quality control by treating each nozzle individually based on its measured ink density characteristics. Each nozzle is assigned a grayscale value reflecting its ink uniformity, and the control unit selectively uses nozzles with acceptable grayscale values for specific pixel areas, ensuring local uniformity while maintaining overall productivity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system implements feedback control by measuring the actual ink density output of each nozzle and using this information to guide nozzle selection during printing. The calculated grayscale values provide feedback on nozzle performance, allowing the system to adjust which nozzles are activated to maintain luminance uniformity across the printed substrate

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12011934B2Substrate processing apparatus and the method thereof

Publication Date: 2024.06.18 SYSTEM ENGINEERING MEGA SOLUTION CO LTD

AI summary

A substrate processing apparatus and a substrate processing method are provided, which can improve the yield by minimizing the occurrence of stains. The substrate processing method includes forming on the substrate a plurality of ink patterns spaced apart from each other by jetting ink onto the substrate by using a plurality of nozzles, calculating the density of each of the plurality of ink patterns, and selecting at least one nozzle for jetting ink into one pixel area based on respectively calculated densities of the plurality of ink patterns.