Continuous-Flow Inkjet Print Head for Uniform Nozzle Temperature
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Solution Overview
Problem
Inkjet print heads experience temperature non-uniformity due to ink heating along the length of the print head, leading to non-uniform droplet formation and visible print artefacts.
Innovation Solution
A print head design with a centralized ink entry port and two ink return ports at opposite ends, forcing ink to circulate in opposite directions along the nozzle array, reducing the ink path length and contact time with heat-generating elements, thereby improving temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink flows along the entire length of the print head from one end, then continuous ink supply is achieved, but temperature non-uniformity increases leading to non-uniform droplet formation
Solution Approach 1:
The ink supply system is segmented into multiple entry ports distributed along the nozzle array rather than a single entry port at one end. This divides the ink flow path into shorter segments, reducing the distance ink travels and minimizing temperature gradients along the flow path, thereby maintaining uniform temperature across all nozzles while ensuring continuous supply.
Solution Approach 2:
The ink entry ports are arranged in a direction transverse to the nozzle array rather than parallel to it. This dimensional change creates a multi-dimensional ink distribution network where ink can enter from multiple locations simultaneously, reducing the effective flow path length in the direction of the nozzle array and improving temperature uniformity.
2Productivity
If ink circulation path is long, then thorough ink circulation is achieved, but contact time with heat-generating elements increases causing temperature non-uniformity
Solution Approach 1:
The circulation path is segmented into multiple shorter flow paths originating from distributed entry ports. Each segment has reduced length and thus reduced exposure time to heat-generating elements, while collectively they provide comprehensive ink circulation across the entire print head array.
Solution Approach 2:
The ink flow path is optimized to rush through the pressure chambers more quickly by reducing path length and eliminating unnecessary detours. This reduces the residence time of ink in contact with heated surfaces, minimizing temperature rise while maintaining effective circulation.
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 significantly reduces temperature and pressure non-uniformity across the nozzle array, enhancing droplet formation consistency and improving print quality.
Implementation Method 1
ink flows from the ink entry port to the first ink return port and the second ink return port in opposite directions parallel to the first direction, i.e., along the length L of the droplet forming device in heat exchanging contact with the droplet forming device
Implementation Method 2
an actuator for generating pressure waves in a liquid in a pressure chamber that is connected to the nozzle
Implementation Method 3
the print head heats up due to resistance of the present electrical traces and due to energy dissipation of the actuators
Data Source
AI summary
The present invention relates to an inkjet print head comprising an ink handling system comprising an ink entry port arranged to supply ink at a central position with reference to the length of the nozzle array, in particular at a position halfway the length of the nozzle array. The ink handling system further comprises two ink return ports, each arranged at each opposite end of the nozzle array for decentralized ink return. The ink handling system is configured such that in operation ink is circulated through the ink handling system such that the ink flows from the ink entry port to both ink return ports in opposite directions in heat exchanging contact with the droplet forming device. In another aspect, the invention relates to a printer comprising at least one print head according to the present invention.