Liquid Ejection Head Layout for Pump-Free Ink Circulation
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Solution Overview
Problem
Conventional liquid ejection heads using a differential pressure system require mechanisms like pressure adjusting mechanisms and pumps, leading to increased size and potential excessive temperature rise due to heat generated by the second energy generating element for ink circulation.
Innovation Solution
A liquid ejection head design with a first and second energy generating element in individual flow passages, arranged in intersecting directions, and specific opening configurations to facilitate ink circulation without pumps, reducing temperature rise and apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential pressure system with pumps and pressure adjusting mechanisms is used to circulate ink, then ink circulation is achieved, but the apparatus size increases
Solution Approach 1:
The patent extracts and eliminates the pump and pressure adjusting mechanism from the ink circulation system. Instead of using these external mechanical components, the invention uses a thermal field generated by the ejection energy generating element itself to drive ink circulation through thermal expansion and convection, thereby reducing apparatus size while maintaining circulation functionality
Solution Approach 2:
The ejection energy generating element is given a dual function: it not only generates energy for ejecting ink droplets but also generates thermal energy to drive ink circulation. This multi-functionality eliminates the need for separate circulation mechanisms, reducing overall apparatus complexity and size
2Reliability
If a second energy generating element is used to cause liquid to flow in individual flow passages, then ink circulation is achieved, but temperature of the liquid ejection head excessively rises
Solution Approach 1:
The patent applies local quality by creating localized thermal fields only in specific regions where ink circulation is needed. The thermal energy is generated locally in the flow passages rather than heating the entire head, and the heating is concentrated in areas where it most effectively drives circulation without causing excessive overall temperature rise
Solution Approach 2:
The invention uses periodic heating cycles where the second energy generating element is activated in alternating sequences to drive ink flow in different directions or regions. This periodic action allows heat dissipation between cycles, preventing excessive temperature accumulation while maintaining effective circulation
3Reliability
If pumps and pressure adjusting mechanisms are provided to circulate ink, then ink circulation is achieved, but the recording apparatus main body and head increase in size
Solution Approach 1:
The patent removes the pump and pressure adjusting mechanism from the system, replacing them with a thermal-driven circulation mechanism. This extraction of unnecessary components directly reduces device complexity while maintaining the essential ink circulation function
Solution Approach 2:
The system uses its own ejection energy generating element to provide the thermal energy needed for ink circulation. The ejection element serves itself by generating waste heat that is then utilized to drive circulation, eliminating the need for external circulation mechanisms and reducing overall system complexity
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 effectively circulates ink, reduces waste, and maintains stable ejection performance by minimizing temperature increase and apparatus size, improving throughput and yield.
Implementation Method 1
a plurality of first energy generating elements disposed at positions corresponding to respective ejection nozzles in the plurality of first individual flow passages and the plurality of second individual flow passages, the first energy generating elements configured to generate energy for ejecting liquid from the ejection nozzles
Implementation Method 2
a plurality of second energy generating elements aligned with respective first energy generating elements in the second direction in the plurality of first individual flow passages and the plurality of second individual flow passages, the second energy generating elements configured to generate energy for causing liquid to flow
Implementation Method 3
a first flow passage disposed on a side of the second ejection nozzle array opposite to the first ejection nozzle array in the second direction, the first flow passage configured to communicate with first ends of the plurality of first individual flow passages
Implementation Method 4
a plurality of first openings arranged in the first direction and disposed in the first flow passage, a first opening of the plurality of first openings configured for liquid to flow into or flow out of the first flow passage
Data Source
AI summary
A liquid ejection head is provided, in which first flow passage with which a one end of a first individual flow passage communicates, a second flow passage with which a the other end of the first individual flow passage and a one end of a second individual flow passage communicate, a third flow passage with which a the other end of the second individual flow passage communicates, and a plurality of first, second, and third openings that are disposed respectively in the first flow passage, the second flow passage, and the third flow passage and cause liquid to flow in or flow out are included, and, when sizes of non-open parts between two first openings, two second openings, and two third openings that are adjacent to each other in a first direction are respectively denoted by D1, D2, and D3, D1>D2 and D3>D2 are satisfied.