Liquid Discharge Head Ink Circulation Viscosity Control
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Solution Overview
Problem
The evaporation of volatile components from the discharge port in liquid discharge heads leads to increased ink viscosity, causing discharge speed variations and accuracy issues, particularly during prolonged pauses, which can result in clogging and flow resistance.
Innovation Solution
A liquid discharge head design incorporating a circulation system with a discharge port configuration that allows for the circulation of ink between the discharge port and a flow passage, using a supply flow passage and a recovery flow passage to maintain ink viscosity and prevent clogging, with specific regions of varying viscosity within the discharge port to manage evaporation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink is circulated through a flow passage to prevent viscosity increase, then discharge port clogging is prevented, but the liquid discharge head requires additional flow passages and circulation mechanisms increasing device complexity
Solution Approach 1:
The patent combines the circulation function with the existing discharge port structure by forming the flow passage between the discharge port forming member and substrate, eliminating the need for separate circulation channels. The supply and recovery flow passages are integrated into the same structural components that form the discharge ports, merging multiple functions into a unified structure.
Solution Approach 2:
The discharge port forming member and substrate serve dual purposes: they form the discharge ports for liquid ejection and simultaneously create the flow passage for ink circulation. The heating resistors provide both thermal energy for discharge and thermal energy for preventing viscosity increase through circulation, enabling multi-functionality with existing components.
2Speed
If heating resistors are used to prevent ink viscosity increase, then discharge speed stability is improved, but energy consumption increases
Solution Approach 1:
The heating resistors are positioned specifically in the flow passage where ink circulation occurs, providing localized heating only where needed to prevent viscosity increase. This targeted approach heats the ink in the circulation path without requiring continuous heating of the entire discharge port area, reducing overall energy consumption while maintaining discharge speed stability.
Solution Approach 2:
The circulation system with heating resistors operates continuously or periodically to pre-prevent viscosity increase before it affects discharge performance. By maintaining ink flow and temperature in advance, the system avoids the need for higher energy input during actual discharge operations to compensate for viscosity problems.
3Manufacturing precision
If the discharge port opening is small to improve resolution, then manufacturing precision is improved, but ink flow resistance increases
Solution Approach 1:
The patent extracts the flow resistance problem from the discharge port itself by creating a separate circulation path that allows ink to flow around rather than through the small discharge opening. The circulation system provides an alternative flow route that bypasses the restriction, reducing the burden on the small discharge port while maintaining precision.
Solution Approach 2:
The circulation system ensures continuous ink flow through the flow passage, maintaining constant movement and preventing stagnation. This continuous circulation keeps the ink flowing smoothly into the small discharge ports without interruption, compensating for the high resistance that would otherwise occur at the restricted opening.
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 solution effectively suppresses the increase in ink viscosity and maintains discharge quality by circulating ink and managing evaporation, reducing the risk of clogging and ensuring consistent discharge performance.
Implementation Method 1
a heating element disposed in the flow passage and configured to heat the liquid flowing through the flow passage
Implementation Method 2
the flow passage, the supply flow passage, and the recovery flow passage are configured such that the liquid inside the flow passage is capable of being circulated
Data Source
AI summary
A liquid discharge head includes a discharge port; a flow passage; a discharge port part; a supply flow passage; and a recovery flow passage. The flow passage, the supply flow passage, and the recovery flow passage are configured such that the liquid inside the flow passage is capable of being circulated between the inside of the flow passage and the outside of the flow passage. An opening of the discharge port is configured such that a liquid surface of the liquid within the opening of the discharge port has a first region and that a second region, and a viscosity of the liquid in the first region is 1.2 or more times higher than a viscosity of the liquid in the second region.