Liquid Ejection Device Stabilizes Large Drops via Periodic Driving Pulses
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Solution Overview
Problem
Inkjet recording devices face challenges in stabilizing large liquid drop injection, leading to satellite drop formation and ink mist, which degrade printing quality, especially when increasing printing gap or throughput.
Innovation Solution
A liquid injection device with a controller generating specific driving pulses to expand and contract the pressure chamber, ensuring the second liquid drop is injected at a higher speed than the first, and timed to merge properly, reducing satellite drop and mist formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the printing gap is enlarged to inject larger liquid drops, then the dot size is increased, but satellite drops and ink mist are generated due to meniscus instability
Solution Approach 1:
The patent applies periodic driving pulses with specific timing intervals to the pressure chamber. The first driving pulse is applied at a timing that allows the liquid drop to be injected while the meniscus is in a stable state. The second driving pulse is applied after a predetermined time period to inject the next liquid drop. This periodic action with optimized timing prevents meniscus instability and eliminates satellite drops and ink mist while maintaining large drop injection.
2Productivity
If the driving frequency is increased to print at high speed, then the throughput is improved, but satellite drops and ink mist are generated due to rapid meniscus formation
Solution Approach 1:
The patent implements periodic driving pulses with optimized timing intervals that accommodate high-speed printing requirements. By carefully controlling the period between pulses and ensuring the second pulse occurs when the meniscus has stabilized, the system achieves high throughput while preventing satellite drop formation. The periodic nature of the driving signal maintains rhythmic liquid ejection without causing meniscus instability.
3Volume of moving object
If multiple driving pulses are used in multi-dot system to form larger dots, then the dot size is increased, but the complexity of control increases
Solution Approach 1:
The patent simplifies the control of multi-dot systems by using periodic driving pulses with fixed, optimized timing intervals. Instead of complex variable timing control, the system applies pulses at regular periods that naturally accommodate the formation of larger dots through multiple ejections. This periodic approach reduces control complexity while maintaining the ability to form large dots and prevents satellite drop generation.
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
Stabilizes large liquid drop injection, preventing satellite drops and mist, thereby improving printing quality and precision even at increased throughput or larger printing gaps.
Implementation Method 1
an actuator that is in contact with the pressure chamber and includes a piezoelectric element... When a driving pulse is transmitted to the actuator, the piezoelectric element is contracted or extended based on the driving pulse
Implementation Method 2
Tc is a Helmholtz characteristic vibration period of the liquid injection head... The first driving pulse maintains the pressure chamber in an expanded state for a time period of about (1⁄2)×Tc
Data Source
AI summary
A liquid injection device includes a liquid injection head and a controller including a driving signal generator generating a driving signal including, in one liquid drop injection period, a first driving pulse and a second driving pulse, and a driving signal supplier. The first driving pulse maintains the pressure chamber in an expanded state for a time period of about (½)×Tc; and the second driving pulse starts at a timing that is about n×Tc after the start of the first driving pulse, n being an integer satisfying n≥2, to maintain the pressure chamber in the expanded state for the time period of about (½)×Tc, and to inject the second liquid drop at a speed higher than, or equal to, a speed at which the first liquid drop is injected.