Inkjet Recording Head Meniscus Stability via Dynamic Ejection Control
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Solution Overview
Problem
Inkjet printers face issues with meniscus breakage due to pressure differences in ink passages, leading to abnormal ink droplet ejection when multiple ejection openings simultaneously eject ink, causing a shortage of ink supply and increased passage resistance.
Innovation Solution
A recording apparatus with a predictive system that adjusts ejection signal frequencies and movement speeds to maintain a stable pressure difference across ejection openings, using first and second ejection signals with different frequencies and conveyance speeds to prevent meniscus breakage without enlarging the ink passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cross-sectional areas of the common ink passage are enlarged to reduce passage resistance, then ink supply to individual ink passages is improved, but the inkjet head size increases
Solution Approach 1:
The patent applies dynamics by making the ink ejection frequency variable rather than fixed. The control unit adjusts the ejection frequency of ink droplets based on the detected position of the leading end of the recording sheet. When the leading end is detected, the ejection frequency is reduced to prevent meniscus breakage; during normal operation, the frequency returns to the standard high frequency. This dynamic adjustment allows the system to maintain small passage cross-sections while preventing ink supply shortage through temporal modulation of ejection rates.
Solution Approach 2:
The patent changes the parameter of ejection frequency dynamically. By switching between a first ejection frequency (reduced frequency) and a second ejection frequency (standard high frequency) based on the position of the recording sheet's leading end, the system optimizes ink supply without requiring enlarged passages. This parameter change approach resolves the contradiction by using temporal variation rather than spatial enlargement.
2Productivity
If multiple ejection openings simultaneously eject ink droplets, then recording efficiency is improved, but pressure difference becomes insufficient and meniscus breakage occurs
Solution Approach 1:
The patent applies preliminary anti-action by detecting the position of the leading end of the recording sheet in advance and preemptively reducing the ejection frequency before meniscus breakage can occur. When the leading end is detected, the control unit immediately switches to the first (reduced) ejection frequency, preventing the pressure difference from falling below the threshold that would cause meniscus breakage. This anticipatory action maintains reliability while allowing high-productivity operation during normal conditions.
Solution Approach 2:
The patent implements periodic action by rhythmically switching between two ejection frequency modes. The system operates at high frequency (second ejection frequency) during normal recording to maintain productivity, and periodically switches to low frequency (first ejection frequency) when the leading end of the recording sheet is detected. This periodic modulation of ejection frequency prevents continuous high-rate ejection from causing meniscus instability, thus maintaining reliability.
3Reliability
If the ejection frequency is reduced to prevent meniscus breakage, then meniscus stability is improved, but recording speed decreases
Solution Approach 1:
The patent uses periodic action to switch between high and low ejection frequencies based on the position of the recording sheet. The system maintains high recording speed by operating at the second (high) ejection frequency during normal conditions, and only temporarily reduces to the first (low) frequency when the leading end is detected. This periodic switching minimizes the impact on overall recording speed while ensuring meniscus stability at critical moments.
Solution Approach 2:
The patent applies dynamics by making the ejection frequency adaptive rather than fixed. The control unit dynamically adjusts the ejection frequency based on real-time detection of the recording sheet's leading end position. This dynamic adjustment allows the system to maintain high speed during normal operation and only reduce speed temporarily when necessary to prevent meniscus breakage, thus minimizing the trade-off between speed and reliability.
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 prevents meniscus breakage and ensures stable ink droplet ejection while maintaining a smaller recording head size, effectively addressing the ink supply issues and passage resistance challenges.
Implementation Method 1
a piezoelectric element which changes volume in accordance with an applied voltage
Implementation Method 2
a meniscus formed in one of the ejection openings, the atmosphere and the liquid sandwiching the meniscus
Data Source
AI summary
A recording apparatus includes a calculator, a predictor, and a head controller. Assuming that first ejection signals are supplied to a recording head, the calculator calculates variations in total amount of liquid to be ejected, for respective constant periods of time. The predictor predicts, based on one or more calculated variations, whether a pressure difference between the atmosphere and liquid falls below a threshold value, the atmosphere and the liquid sandwiching a meniscus formed in one of the ejection openings. When the predictor predicts that the pressure difference falls below the threshold value, the head controller controls signal supply to the recording head so that second ejection signals are supplied to the recording head, the second ejection signals having a lower frequency than first ejection signals.