Print Head Priming Verification via Temperature Monitoring

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Solution Overview

Problem

Inkjet print heads often develop obstructions due to dried ink, leading to issues like missing printed output, and existing priming methods are not effective in ensuring sufficient fluid flow through the print head.

Innovation Solution

A printing system with a controller, temperature sensor, and external priming system that applies fluid pressure to purge the print head, using temperature monitoring to determine if fluid is properly passing through, thereby reducing print head temperature and clearing obstructions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional priming methods are used to move ink through the print head, then the print head can be primed, but it cannot be verified whether sufficient fluid flow has occurred to clear obstructions

Engineering Contradiction:
Improveverification of priming effectivenessVSAvoidpriming verification system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism by monitoring temperature sensor readings before and during priming operations. The controller compares temperature data to determine if sufficient fluid flow has occurred, providing verification of priming effectiveness without requiring complex additional hardware.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The print head system uses its own temperature sensor and processing capabilities to self-verify priming effectiveness. The existing temperature sensing infrastructure is leveraged to provide priming verification, eliminating the need for separate verification devices.

Inventive Principle:
Principle #25Self-service

2Productivity

If external fluid pressure is applied to purge the print head, then fluid flow through the print head increases and temperature decreases, but it is difficult to determine when sufficient purging has occurred

Engineering Contradiction:
Improvefluid flow rate through print headVSAvoidsufficient fluid flow detection
Core Design Contradiction:
ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The system continuously monitors temperature sensor readings during priming operations and provides feedback to the controller. This enables real-time determination of whether sufficient fluid flow has occurred, allowing the system to stop priming at the appropriate moment and avoid both under-priming and excessive priming.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses temperature changes as an indicator of fluid flow status. By monitoring temperature variations during priming, the system can detect when sufficient fluid has passed through the print head, analogous to using color changes as indicators in other processes.

Inventive Principle:
Principle #32Color changes

3Reliability

If priming is performed frequently to clear obstructions, then print head reliability improves, but energy consumption and operational time increase

Engineering Contradiction:
Improveprint head functionalityVSAvoidpriming operation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial priming by using external fluid pressure to push fluid through the print head rather than relying on complete pump cycles. This partial action approach clears obstructions more efficiently while reducing the time and energy required compared to conventional full priming operations.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

By monitoring temperature changes during priming, the system can determine when obstructions have been cleared and stop the priming operation at the precise moment effectiveness is achieved. This prevents unnecessary continuation of priming operations, reducing wasted time and energy.

Inventive Principle:
Principle #23Feedback

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

Effectively purges the print head, ensuring successful ink flow and preventing obstructions, as indicated by rapid temperature drops during priming, thus maintaining print quality.

Implementation Method 1

a priming system configured to apply a fluid pressure externally to the print head to purge the print head with fluid

Methodology Applied
Scientific EffectFluid pressure: Pressure Increase

Implementation Method 2

The controller is configured to activate the priming system for purging the printhead with fluid, monitor a signal from the temperature sensor

Methodology Applied
Scientific EffectTemperature sensing: Temperature Gradient

Implementation Method 3

purging the print head with fluid has an effect of reducing the print head temperature

Methodology Applied
Scientific EffectConvective cooling: Convection

Data Source

PatentEP2310209B1Verifying a maintenance process on a print head
Publication Date: 2021.05.26 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP2310209B1 patent drawingFigure 1
  • EP2310209B1 patent drawingFigure 2
  • EP2310209B1 patent drawingFigure 3A~3B

AI summary

The present invention is embodied in a printing system (100) that includes a print head (120) having a controller (110), a temperature sensor (116) and a priming system (126) configured to apply a fluid pressure externally to the print head (120) to purge the print head with fluid, wherein purging the print head (120) with fluid has an effect of reducing the print head temperature. The controller (110) is configured to activate the priming system (126) for purging the printhead (120) with fluid, monitor a signal from the temperature sensor (406), and determine (418) whether activating the primer has resulted in sufficient fluid passing through the print head (120) based upon monitoring the signal from the temperature sensor (116).