Parallel Channel Ink Heating Body for MEMS Print-Head Temperature Uniformity
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Solution Overview
Problem
Modern drop-forming units with micro-electro-mechanical systems (MEMS) face low heat transfer efficiency for heating ink to the desired printing temperature, lacking temperature control and requiring a narrower temperature range due to short ink channels, which affects ink drop quality.
Innovation Solution
A heating device with a thermally conductive solid body featuring parallel channels that heat ink via contact with channel walls, providing pressure equalization through a passage to ensure uniform ink flow and residence time across channels, ensuring consistent temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ink channels in MEMS print-heads are shortened to accommodate high ink flow rates, then productivity is improved, but heat transfer efficiency deteriorates resulting in poor temperature uniformity
Solution Approach 1:
The heating system is segmented into multiple parallel heating channels (e.g., 300 channels) within the heating body. Each channel independently heats ink that flows in parallel, allowing high total ink flow rate while maintaining adequate heating length per channel. This segmentation resolves the contradiction by distributing the ink flow across multiple pathways, each with sufficient residence time for heat transfer.
Solution Approach 2:
The invention transitions from a single-dimensional heating approach (one long channel) to a multi-dimensional arrangement (many parallel channels in a three-dimensional heating body). This dimensional change allows simultaneous achievement of short channel length (for high flow rate) and sufficient heating surface area (for temperature uniformity) by utilizing spatial distribution of multiple channels.
2Device complexity
If ink channels are made short for MEMS compatibility, then device complexity is reduced, but heat transfer efficiency deteriorates requiring longer heating length
Solution Approach 1:
Multiple short heating channels are merged into a single integrated heating body made of thermally conductive material. The combined effect of many parallel channels provides sufficient total heating surface area and heat transfer capacity, achieving energy efficiency while keeping individual channel lengths short for MEMS compatibility.
3Productivity
If parallel channels are used to increase ink throughput, then productivity is improved, but temperature uniformity deteriorates due to varying flow distribution
Solution Approach 1:
The heating body provides uniform thermal properties throughout its structure, ensuring that each local channel region operates under identical thermal conditions. This local uniformity in heating characteristics, combined with pressure equalization, ensures that all channels heat ink to the same temperature regardless of flow distribution variations.
Solution Approach 2:
Pressure equalization passages are incorporated to equalize the pressure potential at the inlet of all parallel channels. This creates equipotential conditions that promote uniform flow distribution across all channels, ensuring consistent residence time and heat transfer conditions, thereby maintaining temperature uniformity while achieving high throughput.
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 achieves high ink throughput and temperature uniformity, effectively addressing the challenges of MEMS print-heads by heating ink to a precise temperature range before it reaches the drop-forming unit, enhancing ink drop quality and compatibility with various ink types.
Implementation Method 1
a heating body for transferring heat to liquid ink in contact with the heating body... wherein the plurality of substantially parallel channels are arranged to, in operation, convey the liquid ink from the top side to the bottom side of the heating body whereby the ink is heated via contact with walls of the channels
Implementation Method 2
wherein the heating device comprises a passage arranged separated from the receptacle and to provide a fluid connection between the top side and the bottom side of the heating body, which passage in operation provides pressure equalization between the top side and the bottom side of the heating body
Data Source
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AI summary
The present invention relates to an ink supply system (1) for supplying ink to a drop-forming unit (40) of a print-head (50) in a printing apparatus. The ink supply system (1) comprises: a reservoir (2) for holding or storing a volume of liquid ink to be supplied to a drop-forming unit (40) in a print-head (50), and a heating device (10) arranged upstream of the reservoir (2) for heating the ink to an desired operating temperature. The heating device (10) comprises a heating body (11) for transferring heat to the ink, wherein the heating body (11) comprises a plurality of channels (12) which extend from an topside (13) of the heating body (11) to an bottom side (14) of the heating body (11) for conveying the ink to the reservoir (2), whereby the ink is heated via contact with walls of the channels (12). The heating body (11) typically comprises a substantially monolithic body of a highly thermally conductive material and the plurality of channels (12) are substantially parallel channels which extend through the heating body (11). The invention also relates to a print-head (50) of a printing apparatus incorporating the ink supply system (1), and to the heating device (10).