Printhead Filter with Cross-Flushing for Nozzle Blockage

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Solution Overview

Problem

Conventional printheads face issues with particulate contamination, leading to nozzle blockages and reduced printing quality, especially in page-wide printing systems where all nozzles must operate simultaneously, and there is a need for effective filtration with minimal pressure loss and practical methods for forming printhead filters using MEMS fabrication techniques.

Innovation Solution

A printhead design incorporating a liquid source, a first substrate with defined nozzles, a liquid chamber, and a filter positioned between the substrate and the liquid chamber, utilizing a sieve-type filter with uniformly sized pores to effectively filter particulates while maintaining low pressure loss, and incorporating a cross-flushing mechanism to remove accumulated particulates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a filter is positioned at various locations in the fluid path to reduce particulate contamination, then nozzle blockage is reduced, but pressure loss across the filter increases

Engineering Contradiction:

Improvenozzle blockage preventionVSAvoidpressure loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent employs a porous filter structure with carefully controlled pore sizes and distributions. The filter is made from porous materials that allow liquid flow while trapping particulates, achieving a balance between filtration effectiveness and pressure loss. The porous structure provides large surface area for filtration without creating excessive flow resistance.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent optimizes filter parameters including pore size, pore distribution, filter thickness, and material properties to achieve the desired balance between particulate removal and pressure loss. By carefully selecting and adjusting these parameters, the filter provides adequate filtration while maintaining acceptable pressure characteristics for the printing system.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional filtration methods are used, then some particulate contamination is reduced, but adequate filtration with acceptable pressure loss is not achieved

Engineering Contradiction:

Improveparticulate contamination reductionVSAvoidfiltration system design

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The filter structure is designed to perform multiple functions simultaneously: filtration of particulates, pressure regulation, and flow distribution. The same filter component that removes particles also helps maintain pressure within acceptable ranges and ensures uniform liquid distribution across the nozzle array, reducing the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The use of porous materials with tailored pore structures enables effective particulate removal while maintaining low pressure loss. The porous structure provides large surface area for filtration without creating excessive flow resistance, achieving adequate filtration with a relatively simple filter design.

Inventive Principle:

Principle #31Porous materials

3Reliability

If filters are added to the printhead, then particulate contamination is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improveparticulate filtrationVSAvoidprinthead fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The filter structure is integrated with the printhead body as a unified component rather than being added as a separate assembly. The filter is formed as an integral part of the printhead during the same manufacturing process, eliminating the need for separate filter installation steps and reducing assembly complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs MEMS fabrication techniques to create the filter structure, replacing traditional mechanical filter assembly methods. The filter is formed using photo-imaging and etching processes that define regions of the substrate to be preferentially etched, allowing precise control of pore structures through standard semiconductor manufacturing processes.

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

The design ensures reliable operation of all nozzles in page-wide printing systems by effectively filtering particulates and maintaining acceptable pressure loss, thereby enhancing print quality and printhead reliability through the use of MEMS fabrication techniques.

Implementation Method 1

a filter positioned between the substrate and the liquid chamber

Methodology Applied

Scientific EffectPhysical filtration: Filter (physical)

Data Source

PatentUS8523327B2Printhead including port after filter

Publication Date: 2013.09.03 EASTMAN KODAK CO

AI summary

A printhead includes a liquid source, a first substrate, a filter, and a liquid chamber. Portions of the first substrate define a nozzle adapted to emit liquid from the liquid source. The liquid chamber includes a port. The liquid chamber is in fluid communication with the nozzle and the filter and is positioned between the first substrate and the filter.