Ink Jet Head Discrete Circulation Paths for Ejection Stability
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Solution Overview
Problem
The existing ink jet recording apparatuses face challenges in achieving high-density nozzle arrangements for higher image resolution due to the requirement of a relatively large space for common supply and circulation flow paths, leading to increased size and production costs, and instability in ink ejection caused by pressure fluctuations near the nozzles.
Innovation Solution
The design incorporates a head chip with discrete circulation flow paths branching from the nozzles and a common circulation flow path, along with a common supply liquid chamber on the upper surface, which allows for ink circulation and reduces pressure fluctuations, enabling a smaller, more stable, and cost-effective ink jet head with high-resolution capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common supply flow path and common circulation flow path are provided in the head chip, then ink circulation is achieved and air bubbles are removed, but the head chip size increases and nozzle density decreases
Solution Approach 1:
The circulation flow path is divided into discrete individual circulation flow paths for each nozzle, with each path branching from the ink supply flow path near its corresponding nozzle. This segmentation allows compact arrangement of circulation paths without requiring a large common circulation channel, thus reducing head chip area while maintaining ink circulation functionality for each nozzle.
Solution Approach 2:
The discrete circulation flow paths are arranged to overlap with the ink supply flow path in the plan view, with circulation paths positioned beneath or alongside the supply flow path. This nested arrangement allows both flow paths to coexist in a compact space, reducing the overall head chip area while maintaining both ink supply and circulation functions.
2Reliability
If circulation flow paths are formed in the vicinities of nozzles, then ink circulation is improved, but pressure fluctuations occur and ejection stability decreases
Solution Approach 1:
The circulation flow path is extracted as a separate discrete path that branches from the ink supply flow path and returns to it, rather than being integrated into the main supply path. This extraction allows the circulation function to be performed independently without disrupting the primary ink supply flow, thus maintaining pressure stability while achieving effective ink circulation.
Solution Approach 2:
The circulation flow path is designed with different cross-sectional areas at different locations: a larger cross-sectional area near the nozzle to minimize pressure fluctuations, and a smaller cross-sectional area farther from the nozzle to reduce space requirements. This local variation in geometry optimizes both pressure stability and compactness.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The present invention addresses the problem of providing an ink jet head and the like having a flow path allowing circulation of ink, the ink jet head being small and capable of achieving high resolution, improving injection stability, and reducing manufacturing costs. An ink jet head 1 of the present invention is characterized by being provided with: a head chip 2 provided with a plurality of nozzles N, a plurality of pressure chambers 311 communicating with the nozzles N, a plurality of piezoelectric elements 42 provided to correspond to the plurality of pressure chambers 311, a plurality of sep - arate circulation flow paths 102 which are diverted from an ink flow path extending from an inlet 311a of the pressure chambers 311 to an outlet Nb of the nozzles N, and which are capable of discharging ink inside the pressure chambers 311, and a common circulation path 703 with which at least two of the plurality of separate circulation flow paths 102 communicate; and a commonly supplied liquid chamber 3a provided on a top face of the head chip 2 and storing the ink to be commonly supplied from a plurality of ink supply holes 601 formed on the top face of the head chip 2 to each of the plurality of pressure chambers 311.