Liquid Ejection Head ESD Protection via Conductive Layer
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Solution Overview
Problem
Conventional liquid ejection heads face challenges with dielectric breakdown in the insulating layer due to electrostatic discharge (ESD), particularly in compact configurations where space is limited for ESD protection elements like grounded-gate MOS, which are necessary to prevent such breakdowns.
Innovation Solution
A liquid ejection head design where the electrically conductive protection layer is connected to a common wiring substrate via connecting terminals, effectively dispersing and attenuating ESD currents without the need for additional protection elements within the element substrate, allowing for a more compact layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grounded-gate MOS is arranged as an ESD protection element within the element substrate, then the insulating layer is protected from ESD, but the area required for arranging the MOS makes it difficult to secure space within the element substrate
Solution Approach 1:
The ESD protection function is extracted from the element substrate and implemented through the electrically conductive protection layer that is electrically connected to the outside via connecting terminals. This removes the need for grounded-gate MOS within the substrate, eliminating the area constraint while maintaining ESD protection capability.
Solution Approach 2:
The electrically conductive protection layer serves multiple functions: it protects the heating element from thermal, physical, and chemical impacts, and simultaneously provides ESD protection when electrically connected to the outside. This multi-functionality eliminates the need for separate ESD protection elements.
2Reliability
If the electrically conductive protection layer is electrically connected to the outside via connecting terminals, then ESD currents are dispersed and attenuated without dielectric breakdown, but the configuration complexity increases
Solution Approach 1:
The electrically conductive protection layer is designed to perform both heating element protection and ESD protection functions simultaneously. By electrically connecting this multi-functional layer to the outside via connecting terminals, the system achieves ESD protection without requiring separate protection circuits, thereby avoiding increased configuration complexity.
3Reliability
If additional ESD protection elements are added within the element substrate, then ESD protection is enhanced, but the manufacturing cost and device complexity increase
Solution Approach 1:
The ESD protection function is extracted from the element substrate and implemented through the electrically conductive protection layer that is electrically connected to the outside via connecting terminals. This removes the need for grounded-gate MOS within the substrate, eliminating the area constraint while maintaining ESD protection capability.
Solution Approach 2:
The electrically conductive protection layer serves multiple functions: it protects the heating element from thermal, physical, and chemical impacts, and simultaneously provides ESD protection when electrically connected to the outside. This multi-functionality eliminates the need for separate ESD protection elements.
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
This design significantly reduces the likelihood of dielectric breakdown in the insulating layer, enabling a more compact and cost-effective liquid ejection head configuration without the need for additional ESD protection elements, while maintaining high image quality and reliability.
Implementation Method 1
a plurality of heating elements producing heat energy for liquid ejection by energization
Implementation Method 2
there is a case where dielectric breakdown occurs in the insulating layer of the element substrate resulting from electrostatic discharge
Data Source
AI summary
The liquid ejection head includes a plurality of element substrates including first and second element substrates and an electrical wiring substrate. The first and second element substrates each has a heating element array in which a plurality of heating elements producing heat energy for liquid ejection is arrayed, an electrically conductive protection layer covering the plurality of heating elements, an insulating layer arranged between the plurality of heating elements and the electrically conductive protection layer, and a connecting terminal for connecting to the outside. The electrical wiring substrate is electrically connected with the first and second element substrates via the connecting terminal. On the first and second element substrates, the connecting terminal includes a connecting terminal for the electrically conductive protection layer, and the electrically conductive protection layer is electrically connected to a common wiring provided on the electrical wiring substrate via the connecting terminal.