Liquid Ejecting Head Grounding for Noise Suppression
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Solution Overview
Problem
Liquid ejecting heads, such as ink jet type recording heads, face issues with noise emission due to the conductive cover acting as a planar antenna, especially when not sufficiently grounded, leading to inadequate grounding and amplification of noise, particularly in designs with large areas or multiple covers arranged in parallel.
Innovation Solution
A liquid ejecting head design featuring a conductive base, multiple head main bodies with switching and pressure generating elements, conductive covers separated from the base, and conduction portions that connect the base and covers at multiple locations, ensuring the covers are grounded and preventing noise emission and external noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cover is made of a conductive material and has a relatively large area, then the cover can effectively shield against external noise, but the ground becomes inadequate and the cover functions as a planar antenna, causing noise emission
Solution Approach 1:
The cover is divided into multiple separate conductive cover portions instead of using a single large cover. Each cover portion is individually grounded through conduction portions, preventing any single portion from functioning as an effective antenna while maintaining overall noise shielding capability through multiple distributed grounding points
Solution Approach 2:
Multiple conduction portions are arranged in a specific pattern (including intersecting directions) to create a three-dimensional grounding network. This spatial distribution transforms the grounding approach from a single-plane connection to a multi-dimensional structure, effectively reducing antenna effects while maintaining shielding performance
2Productivity
If multiple covers are arranged in parallel, then the device can handle higher liquid ejection capacity, but amplification and directivity occur making the covers function as antennas and deteriorating performance
Solution Approach 1:
Multiple separate conductive cover portions are used instead of a single large cover, with each portion independently grounded. This segmentation prevents the parallel arrangement from creating effective antenna structures while maintaining the liquid ejection capacity through multiple head main bodies
Solution Approach 2:
Each conductive cover portion has localized grounding through dedicated conduction portions positioned at specific locations. This local grounding approach ensures that each small portion is effectively grounded, preventing noise amplification while allowing multiple portions to work together for high productivity
3Device complexity
If the cover is not sufficiently grounded, then the device structure remains simple, but the cover functions as a planar antenna and noise is emitted from the cover
Solution Approach 1:
The grounding structure is segmented into multiple conduction portions distributed across the base, providing sufficient grounding without requiring a complex single-point grounding system. This distributed approach achieves effective noise suppression with relatively simple individual components
Solution Approach 2:
The conduction portions serve multiple functions: they provide grounding for the conductive covers, structurally support the head main bodies, and help position the switching and pressure generating elements. This multi-functionality achieves sufficient grounding without adding significant structural complexity
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 noise emission from the liquid ejecting head by grounding the covers and protecting the switching and pressure generating elements from external noise, improving the reliability and performance of the device.
Implementation Method 1
a plurality of conduction portions which conduct the base and the cover to each other at a plurality of locations
Data Source
AI summary
There are provided a conductive base; a plurality of head main bodies which are held by the base and each have a switching element and a pressure generating element for discharging a liquid in a pressure generating chamber; a plurality of covers which are separated from the base, at least one of the pressure generating element and the switching element being sandwiched between the base and each of the covers; and a plurality of conduction portions which each conduct the base and the cover to each other at a plurality of locations.