Liquid Ejection Head Flow Resistance Equalization
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Solution Overview
Problem
Ink jet type printing heads experience uneven pressure loss in channels leading to pressure chamber, resulting in uneven ink droplet formation and deteriorated image quality due to differences in channel length between printing element substrates.
Innovation Solution
A liquid ejection head configuration with a distribution channel and collection channel system, where the distribution openings are arranged in series and collection openings are parallel, with adjusted flow resistances to equalize pressures across multiple printing element substrates, ensuring consistent ink droplet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple printing element substrates are used to increase productivity, then the output is improved, but the pressure uniformity deteriorates due to different channel lengths
Solution Approach 1:
The patent applies local quality by creating different flow resistance characteristics in different regions of the common channel. Specifically, the channel portion corresponding to the first printing element substrate has a larger cross-sectional area than the channel portion corresponding to the second printing element substrate, thereby providing different flow resistances to different substrates. This local differentiation compensates for the different channel lengths and achieves uniform pressure distribution across all substrates, resolving the contradiction between using multiple substrates for productivity and maintaining pressure uniformity.
2Area of stationary object
If channel length is increased to supply liquid to multiple pressure chambers, then the coverage is improved, but the pressure loss becomes uneven
Solution Approach 1:
The patent implements local quality by varying the cross-sectional area of the common channel at different positions along its length. The channel has a larger cross-sectional area where it supplies the first printing element substrate (which has a longer channel) and a smaller cross-sectional area where it supplies the second printing element substrate (which has a shorter channel). This local adjustment of channel dimensions compensates for the different path lengths and ensures that pressure loss is balanced across all substrates, thereby maintaining pressure uniformity while achieving wide coverage.
Solution Approach 2:
The patent applies parameter changes by modifying the cross-sectional area parameter of the common channel along its length. By changing the geometric parameter (cross-sectional area) of the channel in response to the varying channel lengths of different printing element substrates, the patent achieves compensation for pressure loss differences. This parameter adjustment ensures that despite the different distances from the liquid supply to various pressure chambers, the pressure remains uniform across all substrates.
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 configuration effectively equalizes pressures in pressure chambers, reducing droplet size variability and improving image quality by minimizing pressure differences between substrates.
Implementation Method 1
in the collection channel, a flow resistance between the first collection opening and the branch point is smaller than a flow resistance between the second collection opening and the branch point
Data Source
AI summary
A liquid ejection head includes a first printing element substrate, a second printing element substrate, and a liquid supply member. The liquid supply member includes a distribution channel arranged upstream the first printing element substrate and the second printing element substrate and a collection channel arranged downstream the first printing element substrate and the second printing element substrate. In the distribution channel, a first distribution opening and a second distribution opening are arranged in series manner to be arrayed in this order from an inlet opening. In the collection channel, a first collection opening and a second collection opening are arranged parallel to each other to be connected with an outlet opening by way of a branch point. In the collection channel, a flow resistance between the first collection opening and the branch point is smaller than a flow resistance between the second collection opening and the branch point.