Printhead Priming via Variable Vacuum Pressure Profile

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Solution Overview

Problem

The existing methods for priming a printhead assembly in imaging devices require multiple iterations, leading to increased noise, longer priming times, and excessive ink usage, particularly when dealing with unused or newly manufactured devices, as they struggle to efficiently evacuate air without drawing in additional air.

Innovation Solution

A single priming process with a unique pressure profile that adjusts the vacuum levels at different stages to effectively evacuate air from the printhead assembly, reducing repetitive processes and minimizing ink wastage, involves a gradual increase in vacuum pressure to ensure both ink and air are drawn through the nozzles without pulling in additional air.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple iterations of priming are performed to evacuate air from the printhead assembly, then the air evacuation is more thorough, but the priming time increases and excessive ink is consumed

Engineering Contradiction:
Improveair evacuation effectivenessVSAvoidpriming time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by varying the vacuum pressure level through different operational phases rather than maintaining a constant pressure. The system transitions from an initial phase with lower vacuum pressure to a final phase with higher vacuum pressure, optimizing both air evacuation effectiveness and priming time efficiency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The priming process is segmented into distinct phases: an initial phase where the vacuum pump operates at a first pressure level to draw ink into the printhead, and a final phase where it operates at a second, higher pressure level to evacuate air. This segmentation allows each phase to be optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

2Reliability

If multiple iterations of priming are performed to evacuate air from the printhead assembly, then the air evacuation is more thorough, but ink consumption increases

Engineering Contradiction:
Improveair evacuation effectivenessVSAvoidink consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The priming process is segmented into distinct phases: an initial phase where the vacuum pump operates at a first pressure level to draw ink into the printhead, and a final phase where it operates at a second, higher pressure level to evacuate air. This segmentation allows each phase to be optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies dynamics by varying the vacuum pressure level through different operational phases rather than maintaining a constant pressure. The system transitions from an initial phase with lower vacuum pressure to a final phase with higher vacuum pressure, optimizing both air evacuation effectiveness and priming time efficiency.

Inventive Principle:
Principle #15Dynamics

3Reliability

If multiple iterations of priming are performed to evacuate air from the printhead assembly, then the air evacuation is more thorough, but the noise increases

Engineering Contradiction:
Improveair evacuation effectivenessVSAvoidnoise
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The priming process is segmented into distinct phases: an initial phase where the vacuum pump operates at a first pressure level to draw ink into the printhead, and a final phase where it operates at a second, higher pressure level to evacuate air. This segmentation allows each phase to be optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies dynamics by varying the vacuum pressure level through different operational phases rather than maintaining a constant pressure. The system transitions from an initial phase with lower vacuum pressure to a final phase with higher vacuum pressure, optimizing both air evacuation effectiveness and priming time efficiency.

Inventive Principle:
Principle #15Dynamics

4Loss of time

If high vacuum pressure is applied from the start to evacuate air quickly, then the priming time is reduced, but additional air is drawn into the printhead through the ink cartridge

Engineering Contradiction:
Improvepriming timeVSAvoidair evacuation effectiveness
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by first drawing ink into the printhead assembly during the initial phase before applying high vacuum pressure. This preliminary ink presence in the printhead prevents air from being drawn through the ink cartridge during the subsequent high-pressure evacuation phase.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The priming process is segmented into distinct phases: an initial phase where the vacuum pump operates at a first pressure level to draw ink into the printhead, and a final phase where it operates at a second, higher pressure level to evacuate air. This segmentation allows each phase to be optimized for its specific function.

Inventive Principle:
Principle #1Segmentation

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 significantly reduces the time and noise associated with priming, while minimizing ink consumption by using a single prime with a tailored pressure profile that effectively evacuates air without drawing in additional air, thus enhancing the efficiency and user experience.

Implementation Method 1

the printhead assembly must be primed by evacuating air from the printhead assembly and drawing ink therein

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 2

A single priming process with a unique pressure profile that adjusts the vacuum levels at different stages to effectively evacuate air from the printhead assembly

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentEP3105062B1Methods and apparatus to prime a printhead assembly
Publication Date: 2019.08.21 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3105062B1 patent drawingFigure 1
  • EP3105062B1 patent drawingFigure 2
  • EP3105062B1 patent drawingFigure 3~4

AI summary

Methods and apparatus to prime a printhead assembly are disclosed. An example method includes drawing ink into a printhead assembly by operating a pump in fluid communication with the printhead assembly for a first period of time at a first speed. An amount of ink drawn into the printhead assembly during the first period is to be sufficient to cover nozzles of a die at an outlet of the printhead assembly. The example method further includes evacuating air within the printhead assembly by operating the pump for a second period of time after the first period of time at a second speed greater than the first speed.