Liquid Ejecting Head Shield Grounding Noise Suppression
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Solution Overview
Problem
Liquid ejecting heads, such as ink jet type recording heads, face issues with noise and static electricity interference causing malfunction or destruction of the pressure generating and switching elements in the head chip, as noise picked up by the metal cover is transferred through the printed circuit board.
Innovation Solution
A liquid ejecting head is designed with a head chip that includes a first conductive path for grounding and a second conductive path for connecting the shield to ground, preventing noise and static electricity from being transmitted to the head chip, and a conductive shield is placed between the head chip and the ejecting medium to protect it from external noise and static electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal cover is grounded to a printed circuit board to provide shielding, then noise and static electricity are picked up and transferred to the head chip, causing malfunction or destruction
Solution Approach 1:
The grounding path is divided into two separate conductive paths: a first conductive path for the head chip and a second conductive path for the shield. This segmentation prevents noise and static electricity from transferring between the head chip and shield through a common grounding path, thereby protecting the head chip while maintaining shielding effectiveness.
Solution Approach 2:
An insulating member is introduced as an intermediary between the first conductive path and the second conductive path. This insulating member prevents electrical connection between the two grounding paths, blocking the transfer of noise and static electricity while allowing both paths to function independently for their respective shielding and grounding purposes.
2Reliability
If the first conductive path and second conductive path are provided, then noise and static electricity transmission is suppressed, but device complexity increases
Solution Approach 1:
The shield structure serves multiple functions: it provides electromagnetic shielding for the head chip, acts as a separate grounding path through the second conductive path, and works in conjunction with the first conductive path to suppress noise and static electricity transmission. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The insulating member serves as an intermediary that enables the two conductive paths to coexist without electrical interference. By placing the insulating member between the paths, the design achieves reliable protection from noise and static electricity while maintaining manageable structural complexity through a single insulating component.
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 configuration effectively suppresses radiation of noise from the head chip, protects it from external noise and static electricity, and prevents malfunction or destruction of the pressure generating and switching elements, ensuring reliable operation.
Implementation Method 1
a conductive shield is placed between the head chip and the ejecting medium to protect it from external noise and static electricity
Implementation Method 2
a first conductive path for connecting the head chip to a ground on the outside of the liquid ejecting head; and a second conductive path for connecting a shield of the head chip to the ground
Data Source
AI summary
There are provided a head chip which ejects a liquid based on an electric signal; a first conductive path for connecting the head chip to a ground on the outside of a liquid ejecting head; and a second conductive path for connecting a shield of the head chip to the ground.