Head Module Cover Gap Design for Adhesive Reliability
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Solution Overview
Problem
Existing liquid discharge heads face challenges in protecting the nozzle plate's peripheral edges and maintaining adhesive reliability due to temperature changes, leading to potential liquid accumulation and adhesive deterioration.
Innovation Solution
A head module design featuring a cover that covers the nozzle plate's discharge surface, with a bonded surface closer to the channel substrate and a thin adhesive layer, creating a gap between the cover and nozzle plate to prevent adhesive bonding and reduce liquid accumulation, while using a heat radiating member for thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover is bonded directly to the nozzle plate, then sealing performance is improved, but liquid accumulates between the cover and nozzle plate causing adhesive deterioration
Solution Approach 1:
The patent introduces a gap between the cover and nozzle plate as an intermediary space that prevents direct contact bonding. This gap acts as a mediator that eliminates liquid accumulation while maintaining sealing through the adhesive applied to the channel substrate, thereby resolving the contradiction between sealing performance and adhesive reliability
Solution Approach 2:
The patent extracts the bonding interface from direct contact between the cover and nozzle plate by positioning the bonded surface on the channel substrate instead. This separation removes the harmful liquid accumulation zone while preserving the sealing function through the adhesive layer on the channel substrate
2Reliability
If the cover covers the entire discharge surface, then protection of the nozzle plate is improved, but thermal management becomes difficult
Solution Approach 1:
The patent applies local quality by providing protection only where needed - the cover protects the channel substrate and peripheral edges of the nozzle plate, while leaving the discharge surface exposed for thermal management. This selective protection approach resolves the contradiction between protection and thermal management
3Strength
If adhesive is applied in a thick layer, then bonding strength is improved, but adhesive deterioration accelerates due to liquid accumulation
Solution Approach 1:
The gap between the cover and nozzle plate serves as an intermediary that prevents liquid from reaching the adhesive layer. This allows the use of sufficient adhesive thickness for bonding strength while protecting the adhesive from liquid-induced deterioration, resolving the contradiction between bonding strength and adhesive durability
Data Source
AI summary
A head module includes a head and a cover. The head includes a nozzle plate and a channel substrate. The nozzle plate includes a nozzle configured to discharge liquid from a discharge surface of the nozzle plate. The channel substrate includes an individual channel communicated with the nozzle. The channel substrate has a surface facing the nozzle plate. The cover covers at least one side of the discharge surface of the nozzle plate of the head. An outer shape of the nozzle plate is smaller than an outer shape of the channel substrate. The cover has a bonded surface bonded to the surface of the channel substrate in an outer area of the nozzle plate with an adhesive. The bonded surface of the cover is closer to the channel substrate than the discharge surface of the nozzle plate is.