Liquid Ejection Head Flow Layout for Ink Circulation and Heat Control
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Solution Overview
Problem
Conventional liquid ejection heads using a differential pressure system require additional mechanisms like pumps and pressure adjusting mechanisms, leading to increased size and potential excessive temperature rise due to the operation of energy generating elements for ink circulation.
Innovation Solution
A liquid ejection head incorporating a first energy generating element for ejecting ink and a second energy generating element for circulating ink within individual flow passages, with a configuration that suppresses excessive temperature rise by optimizing the arrangement and operation of these elements.
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 the pump function from the head structure and relocates it to the main body of the recording apparatus. This separation allows the head to maintain a compact size while the main body houses the circulation mechanism, resolving the contradiction between achieving ink circulation and maintaining small apparatus size.
Solution Approach 2:
The pressure adjusting mechanism is designed to serve multiple functions: it not only adjusts pressure for ink circulation but also controls ejection pressure for the nozzles. This multi-functionality reduces the need for separate mechanisms, thereby reducing overall apparatus size while maintaining reliable ink circulation.
2Reliability
If a second energy generating element is added to circulate ink in individual flow passages, then ink circulation is improved, but temperature of the liquid ejection head rises excessively
Solution Approach 1:
The patent introduces a heat dissipation structure as an intermediary between the second energy generating element and the surrounding environment. This mediator transfers excess heat away from the liquid ejection head, allowing the second energy generating element to continue circulating ink effectively without causing excessive temperature rise.
Solution Approach 2:
The heat dissipation structure is strategically positioned around specific areas where the second energy generating element operates, providing localized cooling where it is most needed. This targeted approach allows effective heat management without requiring the entire head structure to be redesigned for thermal management.
3Reliability
If pumps and pressure adjusting mechanisms are provided, then ink circulation is achieved, but the recording apparatus main body and head increase in size
Solution Approach 1:
The patent segments the ink circulation system into distinct functional modules: the pump is located in the main body while the pressure adjusting mechanism is integrated into the head structure. This segmentation allows each component to be optimized independently and reduces overall structural complexity by distributing functions across different locations.
Solution Approach 2:
The patent merges the pressure adjusting function with the existing head structure, integrating it into the nozzle assembly rather than adding it as a separate external component. This merging reduces the number of discrete parts and simplifies the overall apparatus structure while maintaining the necessary ink circulation capability.
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 circulates ink while minimizing temperature increase, reducing the need for external pumps and maintaining efficient ink flow without enlarging the apparatus size.
Implementation Method 1
a first energy generating element that generates energy for ejecting ink
Implementation Method 2
a second energy generating element that generates energy for causing liquid to flow
Implementation Method 3
the temperature of the liquid ejection head will excessively rise due to heat generated by driving the second energy generating element
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
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.