Liquid Discharging Head Repolarization for Droplet Uniformity

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Solution Overview

Problem

Existing liquid discharging heads, such as ink-jet print heads, face challenges in maintaining uniform droplet discharging characteristics due to high non-uniformity in droplet speeds and masses among nozzles, leading to poor image quality and increased costs and assembly time, with existing polarization correction methods failing to provide stable adjustments over time.

Innovation Solution

A liquid discharging head with a repolarization process that adjusts the polarization sensitivity and voltage for each piezoelectric element to maintain uniform droplet discharging characteristics, using a combination of polarization sensitivity adjustment and polarization voltage adjustment to stabilize the droplet discharge operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If polarization correction is applied to adjust droplet discharging characteristics, then non-uniformity of droplet speeds and masses is reduced, but the adjustment becomes unstable over time and the correction process loses usable endurance

Engineering Contradiction:

Improveuniformity of droplet discharging characteristicsVSAvoidstability of polarization adjustment over time

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing a repolarization process on the piezoelectric element before final polarization correction. This preliminary repolarization stabilizes the piezoelectric element's properties, ensuring that subsequent polarization adjustments remain stable over time and do not drift during operation, thus maintaining both precision and reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical state of the piezoelectric element by applying repolarization treatment that modifies its internal polarization parameters. This parameter change makes the piezoelectric element less sensitive to subsequent polarization adjustments, ensuring long-term stability of the droplet discharging characteristics while maintaining the ability to perform precise corrections

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If precision of piezoelectric elements and components is increased to improve droplet discharge uniformity, then manufacturing costs and assembly time increase

Engineering Contradiction:

Improveuniformity of droplet discharging characteristicsVSAvoidmanufacturing cost and assembly time

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the approach from improving component precision to adjusting operational parameters. By applying repolarization and polarization correction to the piezoelectric element, the system achieves uniform droplet discharge using standard-precision components, thereby avoiding increased manufacturing costs and assembly time while maintaining high manufacturing precision in the output

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical approach of improving component precision with an electrical field approach. Instead of manufacturing more precise piezoelectric elements and components, the system uses electrical repolarization and polarization correction fields to achieve the desired uniformity, simplifying manufacturing while maintaining performance

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach enables stable droplet discharge with low non-uniformity, improving image quality and reducing manufacturing costs by maintaining the precision of components and assembly, while extending the usable endurance of the polarization correction process.

Implementation Method 1

a piezoelectric element as a pressure generator for generating pressure to press ink inside a liquid chamber

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a so-called polarization correcting method for correcting the non-uniformity of the droplet discharging speeds or droplet masses among the nozzles

Methodology Applied

Scientific EffectPolarization correction: Polarisation

Data Source

PatentUS9009973B2Method of manufacturing liquid discharging head

Publication Date: 2015.04.21 RICOH CO LTD

AI summary

A method for manufacturing a liquid discharging head, the method including forming a plurality of nozzles that discharge liquid droplets, forming a plurality of piezoelectric elements that generate pressure for discharging liquid droplets from the respective nozzles; and performing a repolarization process on the piezoelectric elements to set non-uniformity of the droplet discharging characteristics of the nozzles to be in a predetermined range by combining adjustment of a polarization sensitivity and adjustment of a polarization voltage for each of the piezoelectric elements.