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 throughflow is achieved, but temperature non-uniformity increases
Solution Approach 1:
The single ink return path is segmented into two separate return paths at opposite ends of the print head. This divides the long single-path flow into two shorter parallel paths, reducing the maximum flow path length and minimizing temperature gradients along the ink delivery channels.
Solution Approach 2:
The ink entry port is positioned at the center of the print head in the longitudinal dimension, while return ports are distributed at both ends. This spatial arrangement in multiple dimensions creates balanced flow paths that reduce thermal non-uniformity while maintaining continuous throughflow capability.
2Device complexity
If ink entry port is at one end of the print head, then simple ink supply is achieved, but temperature non-uniformity across nozzles increases
Solution Approach 1:
The ink supply system is segmented with one central entry port and two distributed return ports. This segmentation creates multiple shorter flow paths compared to a single long path, reducing the distance ink travels and minimizing heat accumulation along the flow path.
Solution Approach 2:
The ink entry port is positioned at the central location of the print head rather than at one end, creating locally optimized flow distribution. This central positioning ensures more uniform ink delivery to nozzles across the entire array, addressing local temperature variations.
3Reliability
If ink path length is long, then complete ink circulation is achieved, but contact time with heat-generating elements increases
Solution Approach 1:
The circulation path is segmented into two parallel shorter paths by positioning return ports at both ends of the print head. This reduces the maximum path length ink must travel, decreasing contact time with heat-generating elements while maintaining complete circulation through the dual-path configuration.
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 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
Data Source
Figure 1~2B
Figure 3A~3B
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.