Liquid Ejection Head with Shared Circulation for Bidirectional Printing
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Solution Overview
Problem
Existing liquid ejection heads face issues with bubble retention and liquid thickening near ejection ports, and bidirectional printing causes color unevenness due to differing liquid ejection order in forward and backward scanning, leading to increased head size when implementing a liquid circulation system for same-color ejection port arrays.
Innovation Solution
A liquid ejection head design with a single circulation unit supplying and collecting liquid to multiple ejection port arrays of the same color, using a compact channel member and circulation path within the head to maintain fluidity and reduce head size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid circulation system is introduced into a liquid ejection head for bidirectional printing, then liquid thickening and bubble formation are suppressed, but the head size increases due to multiple circulation units required for same-color ejection port arrays
Solution Approach 1:
The patent merges multiple circulation functions into a single circulation unit by using a common circulation channel that serves multiple ejection port arrays of the same color. This integration allows one circulation unit to handle liquid circulation for all same-color arrays, eliminating the need for separate circulation units for each array and thereby reducing head size while maintaining reliable ejection performance.
Solution Approach 2:
The circulation channel is designed with multi-functionality to serve multiple ejection port arrays simultaneously. The channel structure allows liquid to be circulated to and from multiple same-color ejection port arrays through a single circulation unit, making the circulation system universal rather than dedicated to individual arrays, thus reducing the overall number of circulation units needed.
2Reliability
If multiple circulation units are provided for each ejection port array of the same color, then liquid circulation is ensured, but the device complexity and head size increase
Solution Approach 1:
The patent combines multiple circulation functions into a single circulation unit with a shared circulation channel. Instead of providing separate circulation units for each ejection port array, the design merges the circulation paths so that one circulation unit can efficiently serve multiple same-color arrays, thereby reducing device complexity while ensuring reliable liquid circulation.
3Productivity
If ejection port arrays are arranged for bidirectional printing, then printing speed is improved, but color unevenness occurs due to different liquid ejection orders in forward and backward scanning
Solution Approach 1:
The patent employs asymmetric arrangement of ejection port arrays and their corresponding circulation channels. By strategically positioning the arrays and channels in an asymmetric configuration, the design ensures that liquid is supplied to arrays in a consistent order during both forward and backward scanning, preventing color unevenness while maintaining high-speed bidirectional printing capability.
Data Source
AI summary
A liquid ejection head includes an ejection unit, a channel member, and a circulation unit. The ejection unit includes an ejection port array in which ejection ports configured to eject a liquid are arrayed, and a communication channel communicating with the ejection port array. The channel member includes a channel that supplies and collects the liquid to and from the communication channel. The circulation unit supplies the liquid to the channel of the channel member and collects the liquid from the channel of the channel member. The ejection unit further includes a plurality of ejection port arrays that eject a liquid of the same type, and a plurality of communication channels corresponding to the plurality of ejection port arrays. The channel member includes a plurality of individual channels respectively through which the plurality of communication channels communicate with one of the circulation unit as a single circulation unit.