Inkjet Nozzle Driving Pulse Sequence for Large Dot Stability
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Solution Overview
Problem
Large inkjet printers face challenges in stabilizing ink injection for high-speed printing of large dots, leading to unevenness and image quality issues due to meniscus overflow and wettability deviations at the nozzle.
Innovation Solution
A liquid injection device with a controller generating a specific sequence of driving pulses to expand and contract the pressure chamber, ensuring stable injection of multiple ink drops that merge to form a large dot, with optimized timing and speed to prevent meniscus attachment and improve landing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the printing gap is increased to inject a larger ink drop, then the dot size is improved, but the ink injection becomes destabilized
Solution Approach 1:
The patent divides a single large ink drop injection into multiple sequential injections of smaller ink drops. The controller generates multiple driving pulses within one liquid drop injection period, causing the nozzle to inject several smaller drops that merge on the recording medium to form the desired large dot, thereby maintaining injection stability while achieving the required dot size
Solution Approach 2:
The patent employs periodic driving pulses with specific timing intervals to control the injection of multiple ink drops. The controller generates driving pulses at predetermined time points within the injection period, creating a rhythmic injection pattern that ensures each drop is injected at optimal timing, preventing meniscus overflow and maintaining consistent drop formation
2Productivity
If the driving frequency is increased to print at a higher speed, then the productivity is improved, but the ink injection becomes destabilized
Solution Approach 1:
The controller generates multiple driving pulses at specifically timed intervals within each injection period, creating a periodic injection pattern. This structured timing ensures that even at high printing speeds, each ink drop is injected at optimal moments when the pressure chamber and meniscus are in favorable states, preventing destabilization
Solution Approach 2:
The patent dynamically adjusts the timing and number of driving pulses based on the injection period and desired dot size. The controller adapts the injection sequence to maintain stability across varying printing conditions and speeds, optimizing the balance between productivity and injection reliability
3Quantity of substance
If a large liquid drop is injected from the nozzle, then the dot size is improved, but meniscus overflow occurs causing unevenness in wettability distribution
Solution Approach 1:
The patent segments the total liquid volume into multiple smaller drops injected in sequence. Each smaller drop is injected under controlled conditions that prevent meniscus overflow, ensuring uniform wettability. The cumulative effect of multiple uniform drops achieves the desired total dot size without the wettability unevenness that would result from a single large drop
Solution Approach 2:
The patent uses multiple partial injections to achieve the full dot size requirement. Rather than attempting to inject the complete volume in one action (which causes meniscus overflow), the system performs several smaller injection actions that collectively deliver the required amount of ink with consistent wettability characteristics
4Quantity of substance
If the ink drop injection is performed with larger volume, then the dot mass is improved, but the ink drop becomes curved while jumping decreasing image quality
Solution Approach 1:
The patent divides the total ink volume into multiple smaller drops that are injected sequentially. Each smaller drop maintains a proper spherical shape and follows a consistent trajectory during flight to the recording medium. The cumulative mass of these uniformly shaped drops achieves the desired dot mass without the trajectory curvature problems associated with large-volume single drops
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 solution enhances the stability and precision of ink drop injection, reducing variance in dot size and position, and alleviates satellite and mist issues, thereby improving printing quality and throughput.
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
a pressure generator coupled with the vibration plate and located to expand and contract the pressure chamber
Data Source
AI summary
A liquid injection device includes a liquid injection head and a controller that generates a driving signal including first through fourth driving pulses in one liquid drop injection period and supplies the driving signal to the liquid injection head. The discharge time period of each of the first and second driving pulses is preferably set to about (½)×Tc. The start timing of the second driving pulse is preferably set to about m×Tc (m≧1) after the start of the first driving pulse. The second ink drop is preferably set to be injected at a speed of the first ink drop or higher. The start timing of the third driving pulse is preferably set to about (n+(½))×Tc (n≧1) after the start of the second driving pulse. The start timing of the fourth driving pulse is preferably set to about p×Tc (p≧2) after the start of the third driving pulse. The fourth ink drop is injected at a speed of the third ink drop or higher.