Liquid Ejection Head Thermal Insulation for Density Uniformity
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Solution Overview
Problem
High-speed liquid ejection heads face challenges in maintaining image quality due to temperature differences between recording element substrates and excessive heat discharge, leading to density unevenness in printed materials, especially in full-line configurations where ink circulation and heat management are inadequate.
Innovation Solution
A liquid ejection head design incorporating insulation members with specific thermal resistance values and materials to manage heat transfer between recording element substrates and support members, ensuring efficient energy distribution and reduced temperature differences, while maintaining high-speed printing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed printing is implemented using a full-line head with multiple recording element substrates, then printing speed is improved, but temperature difference between substrates increases causing density unevenness
Solution Approach 1:
The support member is divided into multiple heat-insulating portions, each corresponding to a recording element substrate. This segmentation isolates the thermal influence between adjacent substrates, preventing heat accumulation and temperature differences that cause density unevenness in full-line high-speed printing.
Solution Approach 2:
Heat-insulating portions are introduced as intermediary elements between recording element substrates and the support member. These portions act as thermal barriers that reduce heat transfer from the substrates to the support member and between adjacent substrates, thereby maintaining uniform temperature and density across the printing surface.
2Power
If thermal system is used for ink ejection, then ejection performance is improved, but temperature rise of ink occurs influencing image quality
Solution Approach 1:
Heat-insulating portions serve as intermediary thermal barriers between the recording element substrates and the support member. This insulation prevents excessive heat from the thermal ejection process from transferring to the ink supply system, thereby maintaining stable ink temperature and consistent image quality during high-power operation.
Solution Approach 2:
The support member is segmented into multiple heat-insulating portions that individually manage heat from each recording element substrate. This segmentation localizes thermal influence and prevents cumulative heat buildup that would otherwise raise ink temperature and degrade image quality.
3Power
If piezoelectric system of shear mode is used, then ejection capability is achieved, but energy efficiency is low causing excessive heat generation
Solution Approach 1:
Heat-insulating portions are positioned between the recording element substrates and the support member to act as thermal intermediaries. This insulation captures and isolates the waste heat generated by the inefficient shear mode piezoelectric ejection, preventing it from accumulating and excessively heating the ink, thereby improving overall energy utilization.
4Productivity
If continuous operation is performed for high-speed printing, then productivity is improved, but cooling time cannot be provided leading to excessive heat accumulation
Solution Approach 1:
The support member is divided into multiple independent heat-insulating portions, each managing heat from individual recording element substrates. This segmentation allows heat to be distributed and managed locally, enabling continuous operation without cumulative heat accumulation that would otherwise require cooling pauses.
Solution Approach 2:
Heat-insulating portions act as thermal intermediaries that prevent direct heat transfer from recording element substrates to the support member during continuous operation. This insulation maintains more stable temperatures, enabling sustained high-speed printing without excessive heat buildup that would necessitate cooling interruptions.
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 solution effectively suppresses temperature differences and heat discharge, ensuring consistent image quality and reduced power consumption during high-speed printing, even with increased calorific values, by optimizing thermal resistance and energy efficiency in the liquid ejection head.
Implementation Method 1
The piezoelectric system uses deforming force of a piezoelectric element
Implementation Method 2
The thermal system involves boiling ink by applying heat thereto to utilize bubbling force caused thereby
Implementation Method 3
boiling ink by applying heat thereto
Implementation Method 4
a material such as alumina having high thermal conductivity is used for the support member 102
Data Source
AI summary
A liquid ejection head includes, a first support member including a flow path for supplying liquid and an opening communicating with the flow path; at least one second support member that includes an individual liquid chamber communicating with the opening and arranged on the first support member along the flow path; and a recording element substrate including an energy-generating element for generating energy for ejecting the liquid, and a supply port for supplying the liquid to the energy-generating element, the supply port communicating with the individual liquid chamber, the recording element substrate being supported by a back surface of the second support member with respect to an opposite surface thereof facing the first support member. When P (μJ/pL) represents energy to be input per ejection liquid droplet volume in the energy-generating element, thermal resistance R (K/W) of a shortest heat transfer path of the second support member between the recording element substrate and the first support member satisfies:R≧1.4/ln{0.525e1.004P−0.372}−1.