Inkjet Head Natural Frequency Oscillation Control
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Solution Overview
Problem
Current inkjet recording devices face challenges in reducing ink discharge volume without increasing nozzle dimensions or complexity, particularly due to the limitations of electrostatic attraction and precise pulse width requirements, which restrict the range of applicable inks and complicate control systems.
Innovation Solution
The design incorporates ink flow paths with specific natural frequency modes, where the second-order mode frequency is higher than the first-order mode, allowing pressure variations corresponding to the first-order mode to facilitate ink discharge, using piezoelectric members to deform and vary pressure, and applying square wave pulses with short rising and falling times to induce efficient ink droplet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nozzle dimension is decreased to reduce ink discharge volume, then the ink discharge volume is reduced, but the friction between ink and nozzle walls increases and stable droplet separation becomes difficult
Solution Approach 1:
The patent applies ultrasonic vibration to the nozzle orifice to generate acoustic cavitation in the ink, which reduces surface tension and enables stable droplet separation even in extremely small nozzles (1 μm or less). The vibration frequency is set to resonate with the natural frequency of the ink column in the nozzle, enhancing the effect.
Solution Approach 2:
The patent changes the physical state of the ink by applying ultrasonic vibration, which temporarily reduces surface tension and viscosity near the nozzle orifice. This parameter change allows the ink to separate stably into minute droplets despite the small nozzle dimension and high friction.
2Quantity of substance
If electrostatic attraction is used to discharge minute ink volumes, then the ink discharge volume is reduced, but the range of applicable inks is limited and the structure becomes complicated
Solution Approach 1:
The patent replaces the electrostatic attraction mechanism with a mechanical ultrasonic vibration mechanism. This substitution eliminates the need for voltage application near the orifice edges and removes ink charging requirements, thereby expanding the range of applicable inks while maintaining simple structure.
3Quantity of substance
If the pulse width is decreased to correspond to the second-order mode natural frequency, then the ink discharge time is reduced and ink volume is decreased, but the control system becomes complicated and circuit dimensions increase
Solution Approach 1:
The patent uses ultrasonic vibration at a fixed high frequency (20 kHz or above) to achieve rapid ink discharge. This mechanical vibration approach eliminates the need for precise pulse width control corresponding to second-order mode natural frequency, simplifying the control system while achieving the same effect of reduced ink volume.
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 approach enables a broader range of inks to be used while reducing ink discharge volume without increasing device dimensions or control complexity, allowing for stable and efficient discharge of minute ink droplets.
Implementation Method 1
piezoelectric members to deform and vary pressure
Implementation Method 2
each of the ink flow paths has a natural frequency of a first-order mode depending on a combination of the entire ink flow path and the ink and has a natural frequency of a second-order mode depending on a combination of a part of the ink flow path and the ink
Data Source
AI summary
An inkjet head comprising ink flow paths each including a nozzle in communication with a pressure chamber. Pressurizing sections vary pressure on the ink in the respective pressure chambers. Each of the ink flow paths has a natural frequency of a first-order mode and the ink and has a natural frequency of a second-order mode which is higher than the natural frequency of the first-order mode. Each of the pressurizing sections varies the pressure on the ink for a predetermined time corresponding to the natural frequency of the first-order mode, so that a predetermined volume of ink is discharged when a shift of a fluid level of the ink due to pressure oscillation of the second-order mode is superposed on a shift of a fluid level of the ink due to pressure oscillation of the first-order mode.