Inkjet Printhead Bubble Priming via Thermal Expansion
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Solution Overview
Problem
Inkjet printheads often experience air bubbles in their ink channels, which can hinder printing performance, especially when the printer is first used or after long periods of inactivity, requiring effective priming methods to flush out these bubbles.
Innovation Solution
The method involves heating the liquid ink within the printhead to increase the size and reduce the surface tension of gaseous bubbles, making them easier to remove through the orifices, using thin film resistors to control the temperature and facilitate the priming process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional priming methods are used to flush air bubbles from the printhead, then the bubbles can be removed, but the process is time-consuming and may require multiple flushing cycles
Solution Approach 1:
The patent applies parameter changes by heating the ink to elevated temperatures (e.g., 50-100°C) during the priming process. This temperature change causes air bubbles to expand and become less dense, making them rise more quickly through the ink channels and exit the printhead nozzles faster, thereby reducing priming time while ensuring reliable bubble removal
Solution Approach 2:
The patent utilizes phase transitions by heating the ink to near-boiling temperatures, causing the liquid ink to approach phase change. This thermal state change reduces the surface tension of the ink and causes air bubbles to expand and coalesce, facilitating their rapid expulsion from the system during priming
2Ease of operation
If the printhead is heated to high temperatures to expand bubbles, then bubble removal is facilitated, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by applying heating cycles during the priming process rather than maintaining continuous high-temperature heating. The system heats the ink to expand bubbles, then allows cooling periods between heating cycles, which reduces overall energy consumption while still achieving effective bubble removal during the active heating phases
Solution Approach 2:
The patent applies self-service by utilizing the natural thermal expansion and buoyancy of air bubbles when heated. The heating process itself generates the expansion force that propels bubbles out of the printhead, eliminating the need for additional mechanical pumping or external pressure systems that would consume extra energy
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 effectively enlarges and reduces the surface tension of bubbles, allowing for easier removal and reducing the likelihood of subsequent bubble formation, thus improving printing efficiency and conserving ink.
Implementation Method 1
heating the liquid ink within the printhead to increase the size and reduce the surface tension of gaseous bubbles
Implementation Method 2
heating the liquid ink within the printhead to increase the size and reduce the surface tension of gaseous bubbles
Data Source
AI summary
A fluid-dispensing head includes a plenum configured to house fluid; at least one dispensing head orifice in fluid communication with the ink plenum; and at least one heating element configured to heat fluid in the head such that gas bubbles disposed within the fluid increase in surface area.