Liquid Dispensing Head With Matched Flow Resistance
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Solution Overview
Problem
In circulation type ink jet heads, the asymmetrical flow paths for ink supply and discharge lead to biased flow path resistance, making it difficult to control the pressure at the nozzle, which is typically negative with respect to atmospheric pressure.
Innovation Solution
The ink jet head design incorporates symmetrical supply-side and discharge-side flow paths with equal flow path resistances, utilizing piezoelectric elements to vibrate a vibration plate and adjust pressure chamber volumes for precise liquid ejection, and includes a drive circuit to control the piezoelectric elements for uniform pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If asymmetrical flow paths are used for ink supply and discharge, then the structure is simpler, but the flow path resistance becomes biased and pressure control at the nozzle becomes difficult
Solution Approach 1:
The patent applies asymmetry in reverse - it deliberately creates symmetrical flow paths where asymmetry would naturally occur. The supply-side flow path and discharge-side flow path are designed with equal lengths and equivalent resistance values, transforming the natural asymmetrical circulation structure into a symmetrical configuration to achieve balanced pressure control at the nozzle.
Solution Approach 2:
The patent changes the flow path resistance parameters by adjusting the dimensions, cross-sectional areas, and lengths of the supply-side and discharge-side flow paths. Specifically, it sets the flow path resistance of the supply side (R1) equal to that of the discharge side (R2) by modifying geometric parameters such as channel width, height, and length, thereby achieving balanced pressure distribution.
2Manufacturing precision
If symmetrical flow paths are designed with equal resistances, then pressure control at the nozzle is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by making specific modifications only to the flow path sections that require resistance balancing. Instead of redesigning the entire circulation system, it adjusts the cross-sectional areas or lengths of specific supply-side and discharge-side channels to achieve equal resistance, leaving other parts of the structure unchanged.
Solution Approach 2:
The patent segments the flow path into distinct supply-side and discharge-side sections, allowing independent design and optimization of each segment. By dividing the circulation system into controllable segments with measurable resistance values, it enables precise adjustment of each segment's dimensions to achieve overall symmetry without complicating the entire structure.
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 enables precise control of nozzle pressure, allowing for consistent liquid dispensing and improved image quality by maintaining equal flow path resistances, thus stabilizing the pressure at the nozzle regardless of ambient conditions or ink type.
Implementation Method 1
Piezoelectric elements positioned to vibrate the vibration plate to change a volume of the pressure chambers for ejecting the liquid from the plurality of nozzles
Data Source
AI summary
According to an embodiment, a liquid dispensing head includes a nozzle plate with a plurality of nozzles and a plurality of pressure chambers respectively communicating with the nozzles. A vibration plate is on a side of the pressure chambers opposite the nozzle plate. A supply-side flow path for liquid to be dispensed from the nozzle is on an inlet side of the plurality of pressure chambers. A discharge-side flow path for the liquid is on an outlet side of the pressure chambers. Piezoelectric elements are positioned to vibrate the vibration plate to change a volume of the pressure chambers for ejecting (dispensing) the liquid from the plurality of nozzles. The supply-side flow path is set to have a flow path resistance that is the same as a flow path resistance of the discharge-side flow-path.