Liquid Ejection Head Insulation via Connection Board
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Solution Overview
Problem
Existing liquid ejection heads face challenges in ensuring reliable insulation between the anti-cavitation film and other electrical wirings, particularly after assembly and when filled with liquid, due to potential conduction caused by static electricity or external forces, which can impair the anti-cavitation film's function and affect ejection performance.
Innovation Solution
A liquid ejection head design that includes an energy generating element covered by an electroconductive anti-cavitation film, a connection board with a connection pad for external electrical connection, and a method for performing an electric inspection of insulation between the anti-cavitation film and other electrical wirings in the final form, using a test pad and protective diodes to ensure accurate leakage current measurement and prevent false inspections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an electroconductive anti-cavitation film is used to protect the energy generating element, then the protection function is improved, but the risk of conduction with other electrical wirings increases
Solution Approach 1:
A connection board is introduced as an intermediary component between the anti-cavitation film and external electrical connections. The connection board provides a dedicated electrical path that prevents direct conduction between the anti-cavitation film and other electrical wirings, thus maintaining both protection and insulation functions
Solution Approach 2:
The electrical connection system is segmented into separate functional zones: the anti-cavitation film remains electrically isolated for protection, while the connection board handles electrical connections through dedicated pads. This segmentation prevents unwanted conduction while maintaining both functions
2Ease of manufacture
If electric inspection is performed before the liquid ejection head is completed, then the inspection process is simplified, but the inspection reliability in final form cannot be ensured
Solution Approach 1:
The connection board is prepared in advance with connection pads that are designed to electrically connect to the anti-cavitation film. This preliminary preparation enables reliable electrical inspection to be performed on the completed assembly without requiring complex reconfiguration
Solution Approach 2:
The connection board serves multiple functions: it provides electrical connection for the anti-cavitation film, enables inspection of insulation reliability, and maintains electrical isolation from other wirings. This multi-functionality allows reliable inspection in the final form without adding complexity
3Reliability
If the liquid ejection head is assembled and filled with liquid before inspection, then the final form inspection is performed, but the inspection complexity increases
Solution Approach 1:
The connection board acts as an intermediary that simplifies inspection in the final form by providing accessible connection pads. These pads enable electrical testing without requiring disassembly or complex access to the anti-cavitation film, reducing inspection complexity while maintaining reliability
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
Ensures reliable insulation between the anti-cavitation film and other electrical wirings in the final form of the liquid ejection head, maintaining the integrity of the anti-cavitation film and preventing performance degradation, even after assembly and when the head is filled with liquid.
Implementation Method 1
The liquid ejection head of this type includes an energy generating element which generates thermal energy in accordance with an electrical signal. The thermal energy causes air bubbles to be generated in the liquid
Implementation Method 2
If conduction is established between an electroconductive anti-cavitation film and other electrical wirings and a potential is generated, a charge transfers to the liquid and properties of the anti-cavitation film may be changed. It is therefore important that the anti-cavitation film is insulated from other electrical wirings with an insulating film
Implementation Method 3
a connection board electrically connected to the anti-cavitation film, and including a connection pad electrically connectable from outside
Data Source
AI summary
A liquid ejection head includes an energy generating element configured to generate energy used for ejection of a liquid, a print element board including an electroconductive anti-cavitation film provided to cover the energy generating element, and a connection board electrically connected to the anti-cavitation film and including a connection pad electrically connectable from outside.