Droplet Ejecting Head Nozzle Hole Geometry for Laser Machining Precision
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Solution Overview
Problem
Existing droplet ejecting heads, such as inkjet printheads, face challenges in achieving precise and accurate nozzle hole formation due to difficulties in focusing laser beams and positioning the nozzle plate accurately, leading to rounded intersections and variations in nozzle shape, which affect ink ejection performance.
Innovation Solution
The droplet ejecting head features nozzle holes with a taper portion that linearly increases in diameter from the jetting end to the inflow end, connected by a surface where the diameter increases more significantly than if the taper were extended at a constant angle, ensuring a relationship of D1 > D2 < 1.2×D2, which enhances uniform droplet flow and ejection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam machining is used to form nozzle holes, then the nozzle holes can be tapered with high precision, but the laser beam cannot be accurately focused at a point resulting in rounded intersections and shape variations
Solution Approach 1:
The patent applies parameter changes by modifying the nozzle hole geometry to include a connecting portion with a specific diameter relationship (D1 > D2 but smaller than 1.2×D2). This parameter adjustment compensates for the rounding effect of laser machining, ensuring that even with rounded intersections, the effective nozzle opening maintains the desired shape and size for consistent droplet ejection.
2Ease of manufacture
If the nozzle plate is positioned relative to the laser beam focal point, then machining can be performed, but positioning accuracy and precision are difficult to achieve leading to varying degrees of rounding or chamfering
Solution Approach 1:
The patent applies beforehand cushioning by designing the connecting portion of the nozzle hole with a diameter D1 that is larger than the ideal diameter D2 but controlled to be smaller than 1.2×D2. This pre-compensation accounts for the inevitable rounding that occurs during laser machining, ensuring that the final effective nozzle opening maintains the desired precision without requiring perfect positioning accuracy.
3Reliability
If the open ends on the ink jetting side are strictly controlled, then ink ejection performance is improved, but the open ends on the ink inflow side are less strictly controlled allowing shape variations
Solution Approach 1:
The patent applies parameter changes by establishing a specific diameter relationship for the connecting portion (D1 > D2 but smaller than 1.2×D2) that compensates for loose control of the inflow end. This parameter adjustment ensures that even with variations in inflow end shape, the overall nozzle hole geometry maintains the desired characteristics for consistent ink ejection performance.
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 ensures consistent and improved droplet ejection performance by regulating the diameter of the inflow end within specific limits, stabilizing ink flow and jet speed, and allowing for the selection of nozzle plates with optimal ink ejection characteristics.
Implementation Method 1
the side of the plate material to be the surface opposite to the nozzle surface, or the surface on the ink inflow side, is irradiated with the laser beam
Implementation Method 2
a plate material to be the nozzle plate is perforated with a laser beam
Implementation Method 3
The piezoelectric actuator is superposed on a surface of the cavity unit opposite to the nozzle surface, so as to selectively pressurize the pressure chambers to eject an ink droplet
Data Source
AI summary
A droplet ejecting head including a nozzle plate having nozzle holes each ejecting a droplet and comprising: a jetting end open at a first surface of the plate; an inflow end open at a second surface of the plate; a taper portion between the jetting end and a vicinity of the inflow end, where a diameter of the nozzle hole linearly increases from the jetting end to the vicinity so as to have a taper angle; a connecting portion comprising a surface connecting the taper portion and the inflow end, at the connecting portion the diameter increasing more greatly than at the taper angle; and where D1 and D2 respectively represent the diameter of the nozzle hole at the inflow end and at an imaginary inflow end obtained if the taper portion extends at the taper angle up to the second surface, D2<D1<1.2×D2.