Piezoelectric Inkjet Head Re-expansion Signal for Droplet Stability
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Solution Overview
Problem
Existing liquid ejecting apparatuses, such as ink jet printers, face issues with elongated tail portions and secondary droplet ejection due to rapid voltage changes, particularly when ejecting high-viscosity inks, which hinder high-speed and stable printing.
Innovation Solution
The apparatus incorporates a driving signal with a re-expansion element that includes a primary and secondary expansion element, each with a distinct voltage variation ratio, to stabilize the meniscus vibration and reduce tail portions of ejected droplets, allowing for high-speed and stable ejection of ink droplets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the voltage is rapidly changed by increasing the driving voltage of the expansion element to cut ink columns and reduce voltage application time, then high-speed ejection is achieved, but the vibration of the meniscus after ejection is increased, causing secondary ink droplets to be ejected and influencing the ejection of the next ink droplets
Solution Approach 1:
The expansion element is divided into a first expansion element and a second expansion element with different voltage variation ratios. The first expansion element has a larger voltage variation ratio for rapid expansion to cut ink columns, while the second expansion element has a smaller voltage variation ratio to gently stabilize the meniscus, preventing secondary droplet ejection and ensuring stable next droplet ejection.
Solution Approach 2:
The patent changes the voltage variation ratio parameter between the first and second expansion elements. The first expansion element uses a larger voltage variation ratio for rapid action, while the second expansion element uses a smaller voltage variation ratio for stabilization, thereby resolving the contradiction between ejection speed and ejection stability.
2Manufacturing precision
If such a problem occurs, provision of an expansion element for expanding pressure generation chambers and cutting ink columns after a contraction element is suggested, then ink column cutting is improved, but the tail portions of ejected ink droplets are lengthened and high-speed printing cannot be performed
Solution Approach 1:
The expansion element is segmented into first and second expansion elements with different voltage variation ratios. The first expansion element provides rapid expansion for precise ink column cutting, while the second expansion element provides controlled expansion to minimize tail portion lengthening, enabling both precise cutting and high-speed printing.
Solution Approach 2:
By changing the voltage variation ratio parameter between the first and second expansion elements, the patent achieves precise ink column cutting with the first element (larger voltage variation ratio) while the second element (smaller voltage variation ratio) prevents excessive tail portion lengthening, thereby enabling high-speed printing.
3Loss of time
If a voltage is rapidly changed by increasing the driving voltage of the expansion element, then the time for applying the voltage is reduced enabling high-speed ejection, but the vibration of the meniscus of the ink of the nozzle openings after the ink droplets are ejected is increased
Solution Approach 1:
The voltage application process is segmented into two phases: the first expansion element applies voltage rapidly with a larger voltage variation ratio to reduce application time, while the second expansion element applies voltage more gradually with a smaller voltage variation ratio to stabilize the meniscus after ejection, reducing vibration.
Solution Approach 2:
The patent changes the voltage variation ratio parameter between the first and second expansion elements. The first expansion element uses a larger voltage variation ratio to minimize voltage application time for high-speed ejection, while the second expansion element uses a smaller voltage variation ratio to minimize meniscus vibration after ejection.
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 reduces the tail portions of ejected droplets and stabilizes meniscus vibration, enabling high-speed and stable ink ejection, even with high-viscosity inks, thereby improving printing efficiency.
Implementation Method 1
a longitudinal vibration piezoelectric element, a deflection piezoelectric element, a device using electrostatic force and a heating device may be used
Implementation Method 2
a longitudinal vibration piezoelectric element, a deflection piezoelectric element, a device using electrostatic force and a heating device may be used
Data Source
AI summary
A liquid ejecting apparatus includes a liquid ejecting head including pressure generation chambers communicating with nozzle openings for ejecting a liquid and pressure generation units which cause pressure variations in the pressure generation chambers. A driving unit supplies, to the pressure generation units, a driving signal including an expansion element for expanding the pressure generation chambers. A contraction element contracts the pressure generation chambers and a re-expansion element expands the pressure generation chambers before the liquid is ejected from the nozzle openings by the contraction element. The re-expansion element includes a primary expansion element at the contraction element side that expands the pressure generation chambers. A secondary expansion element has at least a variation portion having a voltage variation ratio different from a voltage variation ratio of the primary expansion element in continuation to the primary expansion element and expands the pressure generation chambers.