Inkjet Head Feedback Control for Uniform Bipolar Element Droplets

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Solution Overview

Problem

Existing inkjet printing technologies struggle to maintain a uniform number of bipolar elements per unit droplet of discharged ink, affecting the reliability of light emission in display devices.

Innovation Solution

An inkjet printing device equipped with a sensing unit that measures the number of bipolar elements in the discharged ink, adjusting the droplets to maintain a consistent number of bipolar elements on the target substrate, using an inkjet printing device with an ink circulation system and a probe device to align and disperse bipolar elements uniformly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional inkjet printing is used without sensing feedback, then the printing process is simple and fast, but the number of bipolar elements per unit droplet is not uniform

Engineering Contradiction:
Improveuniformity of bipolar elements per unit dropletVSAvoidcomplexity of printing system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system where a sensing unit measures the actual number of bipolar elements in discharged ink droplets and feeds this information back to a control unit. The control unit then adjusts printing parameters to maintain uniform distribution of bipolar elements per unit droplet, directly resolving the technical contradiction between manufacturing precision and device complexity.

Inventive Principle:
Principle #23Feedback

2Reliability

If the number of bipolar elements per unit droplet is not controlled, then the printing process is simple, but the light emission reliability of display devices deteriorates

Engineering Contradiction:
Improvelight emission reliabilityVSAvoidcomplexity of printing system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sensing unit measures the number of bipolar elements in discharged ink and provides feedback to the control unit, which adjusts printing parameters to ensure uniform distribution. This feedback mechanism guarantees light emission reliability by maintaining consistent bipolar element counts per droplet, while avoiding excessive complexity through targeted control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical control methods with a sensing and feedback-based control system. Instead of using complex mechanical mechanisms to control droplet composition, the system uses optical or electromagnetic sensing to measure bipolar element distribution and adjusts printing parameters accordingly, reducing mechanical complexity while improving reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If bipolar elements are not uniformly dispersed in ink, then the ink formulation is simple, but the printing quality and consistency deteriorate

Engineering Contradiction:
Improveprinting quality consistencyVSAvoidcomplexity of ink circulation system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The sensing unit monitors the distribution of bipolar elements in the ink and provides feedback to the control unit, which adjusts printing parameters to compensate for non-uniform dispersion. This ensures consistent printing quality even when bipolar elements are not perfectly uniformly dispersed in the ink, while managing system complexity through intelligent control.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control unit adjusts printing parameters such as droplet size, discharge frequency, or ink flow rate based on sensing feedback to compensate for non-uniform bipolar element dispersion. By changing these parameters dynamically, the system maintains printing quality consistency without requiring perfect initial uniformity in the ink formulation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4094946B1Inkjet printing device, method for printing bipolar elements, and method for manufacturing display device
Publication Date: 2025.07.30 SAMSUNG DISPLAY CO LTD
  • EP4094946B1 patent drawingFigure 1
  • EP4094946B1 patent drawingFigure 2
  • EP4094946B1 patent drawingFigure 3

AI summary

Provided are an inkjet printing device, a method for printing bipolar elements, and a method for manufacturing a display device. The inkjet printing device comprises: a stage; an inkjet head disposed above the stage and including a plurality of nozzles through which an ink comprising bipolar elements each having partial regions doped with different polarities is discharged; and an actuator disposed in the inkjet head to adjust the amount of droplets of the ink discharged through the nozzle; and at least one sensing unit disposed in the inkjet head to measure the number of bipolar elements discharged through the nozzle.