Liquid Discharging Head Drive Method for High Viscosity Ink
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Solution Overview
Problem
Existing liquid discharging heads face challenges in discharging droplets when the viscosity of the liquid is high, as they struggle to generate sufficient pressure fluctuations to overcome the increased resistance.
Innovation Solution
A drive method for a liquid discharging head that employs a specific waveform pattern for the drive signal, comprising multiple drive pulses that alternately decrease and increase pressure within a pressure chamber, ensuring effective liquid column formation and droplet discharge even with high viscosity inks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-pulse drive signal is used, then the device structure remains simple, but droplet discharge fails when liquid viscosity is high
Solution Approach 1:
The drive signal is segmented into multiple distinct pulses (first pulse for liquid column formation, second pulse for droplet discharge) instead of using a single pulse. This segmentation allows each pulse to be optimized for its specific function, enabling reliable droplet discharge from high-viscosity liquids while maintaining a relatively simple overall device structure.
Solution Approach 2:
The first drive pulse performs a preliminary action by forming a liquid column in the nozzle before the second pulse discharges the droplet. This preliminary liquid column formation is essential for overcoming high liquid viscosity and ensures that the subsequent droplet discharge is reliable, without requiring complex structural modifications.
2Reliability
If multiple drive pulses are supplied to form liquid columns, then droplet discharge reliability improves for high viscosity inks, but the drive signal complexity increases
Solution Approach 1:
The drive signal waveform is divided into two distinct pulses with different characteristics: the first pulse creates a positive pressure region for liquid column formation, and the second pulse creates a negative pressure region for droplet discharge. This segmentation enables reliable droplet discharge from high-viscosity liquids while keeping the waveform structure manageable through clear functional separation.
Solution Approach 2:
The drive signal utilizes parameter changes in pressure (positive pressure for column formation, negative pressure for discharge) and timing (sequential pulse delivery) to achieve reliable droplet discharge from high-viscosity inks. These parameter variations allow the system to overcome viscosity-related discharge failures without requiring complex additional hardware.
3Reliability
If pressure fluctuations are increased to discharge high viscosity liquid, then droplet discharge capability improves, but liquid column stability deteriorates
Solution Approach 1:
The pressure fluctuation process is segmented into two phases: the first pulse generates a positive pressure region that stabilizes the liquid column for proper formation, and the second pulse generates a negative pressure region that enables droplet discharge. This temporal segmentation of pressure phases allows the system to achieve both liquid column stability and droplet discharge capability, overcoming the trade-off that would exist with continuous high-pressure fluctuations.
Solution Approach 2:
The drive signal employs periodic action through alternating pressure regions (positive pressure followed by negative pressure) to first form a stable liquid column and then discharge the droplet. This periodic pressure variation enables the system to maintain liquid column stability during formation while achieving effective droplet discharge, resolving the contradiction between stability and discharge capability.
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 method enables stable and efficient discharge of droplets from the liquid discharging head, even with inks having viscosities of 20 millipascal seconds or more, by forming and growing liquid columns through controlled pressure fluctuations, ensuring consistent printing performance.
Implementation Method 1
a drive element that displaces by being supplied with a drive signal, a pressure chamber inside which pressure is increased or decreased according to a displacement of the drive element
Implementation Method 2
forming a first liquid column in which a liquid surface inside the discharging portion protrudes in the discharging direction by supplying a drive signal, which has a first waveform including a first drive pulse having a first drive component that causes the pressure inside the pressure chamber to decrease and a second drive component that causes the pressure inside the pressure chamber to increase
Data Source
AI summary
Provided is a drive method of a liquid discharging head including a first step of forming a first liquid column by supplying a drive signal having a first waveform to a drive element, and a second step of, when the first liquid column is formed, forming a second liquid column by supplying a drive signal having a second waveform to the drive element, and thereafter discharging a part or all of liquid constituting the second liquid column as a droplet, in which when a drive signal having the first waveform but not having the second waveform is supplied to the drive element, a droplet is not discharged from the discharging portion, and when a drive signal having the second waveform but not having the first waveform is supplied to the drive element, a droplet is not discharged from the discharging portion.