Liquid Ejection Head Layout for Ink Circulation Temperature Control
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Solution Overview
Problem
Existing liquid ejection heads with both a first and second energy generating element for ink circulation face issues with temperature variation due to heat generated by the second energy generating element, which can lead to increased size and complexity.
Innovation Solution
A liquid ejection head design with a first and second energy generating element, where the second energy generating element is positioned to minimize temperature variation by controlling the flow resistance in the individual flow passages, and includes a temperature sensor to regulate the second energy generating element's operation based on detected temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a second energy generating element is added to induce liquid flow, then ink circulation is achieved without pumps, but temperature variation occurs due to heat generation
Solution Approach 1:
The liquid ejection head is divided into multiple independent ejection units, each with its own first and second energy generating elements. This segmentation allows localized flow induction without requiring a single large heat-generating element, thereby reducing overall temperature variation while maintaining ink circulation capability.
Solution Approach 2:
The second energy generating element is positioned to create local flow induction only where needed in the flow passage, rather than heating the entire liquid volume. This localized approach minimizes unnecessary heat generation and resulting temperature variation while still achieving effective ink circulation.
2Productivity
If differential pressure method is used for ink circulation, then ink flows from inlet to outlet, but pressure adjusting mechanism and pump are required increasing size
Solution Approach 1:
The pump and pressure adjusting mechanism are completely removed from the system. Instead, the second energy generating element directly induces liquid flow through localized energy generation, extracting the circulation function from complex mechanical components and implementing it through a simpler thermal field approach.
Solution Approach 2:
The mechanical pump-based circulation system is replaced with a thermal field-based system. The second energy generating element uses thermal energy to induce liquid flow, substituting mechanical movement with thermal diffusion and convection mechanisms, thereby eliminating the need for mechanical circulation components.
3Reliability
If second energy generating element drives liquid flow, then circulation is achieved, but heat generation causes temperature variation
Solution Approach 1:
The second energy generating element operates periodically rather than continuously, inducing liquid flow in cycles. This periodic operation allows thermal energy to dissipate between cycles, preventing excessive temperature accumulation while maintaining effective ink circulation and improving temperature stability.
Solution Approach 2:
The first energy generating element continuously performs liquid ejection while the second energy generating element periodically induces flow. This combination ensures continuous useful action for ink delivery while the periodic flow induction prevents thermal accumulation, maintaining both circulation stability and temperature control.
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 suppresses temperature variation, reduces the need for pumps, and minimizes the size and complexity of the recording apparatus, improving throughput and reducing waste ink usage.
Implementation Method 1
first energy generating elements provided at positions corresponding to the ejection nozzles in the plurality of first individual flow passages and the plurality of second individual flow passages, the first energy generating elements generating energy for ejecting liquid from the ejection nozzles
Implementation Method 2
second energy generating elements provided side by side with the 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 generating energy for causing the liquid to flow
Implementation Method 3
a temperature sensor provided in the second non-opening part; and a control unit for controlling driving of the second energy generating element based on the temperature detected by the temperature sensor
Data Source
AI summary
A liquid ejection head includes a first flow passage with which one end of a first individual flow passage communicates, a second flow passage with which the other end of the first individual flow passage and one end of a second individual flow passage communicate, a third flow passage with which the other end of the second individual flow passage communicates, and a plurality of first, second, and third openings provided in the first, second, and third flow passages, respectively, for allowing liquid to flow into or from each passage. When D1, D2, and D3 are defined as the sizes of the non-opening parts between two adjacent first, second, and third openings, respectively, then D2>D1 and D2>D3. The driving of the second energy generating element is controlled based on the temperature detected by the temperature sensor provided in the non-opening part between the second openings.