Inkjet Head Driving Signal Control for Reliable Ejection
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in reliably ejecting ink when the travel speed of the printing head relative to the paper is reduced below a steady speed, leading to inconsistent ink ejection due to changes in the state of the outlets, affecting printing accuracy.
Innovation Solution
The method involves generating an ejection timing signal as the printing medium moves relative to the inkjet head and inputting a driving signal based on writing data, with additional non-ejection driving signals being input between ejection timing signals when the ejection interval exceeds twice the basic time period, allowing for reliable ink ejection even at reduced speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the travel speed of the head is reduced to be lower than a steady speed determined in accordance with a basic time period, then printing can be performed with extended time period, but the state of the vicinity of each outlet is changed and ink ejection becomes unreliable
Solution Approach 1:
The patent applies periodic action by inputting non-ejection driving signals at regular intervals between ejection operations. When the time period between ejection operations exceeds the basic time period, non-ejection driving signals are inserted to maintain periodic stimulation of the piezoelectric element, preventing state changes in the outlet vicinity while still achieving extended ejection intervals for slow-speed printing.
Solution Approach 2:
The patent changes the driving signal parameters dynamically based on the ejection interval. When the time period between ejection operations is equal to or longer than the basic time period, the system switches from continuous ejection-mode signals to a combined pattern of ejection signals and non-ejection signals, adjusting the frequency and timing parameters to maintain reliable operation at extended intervals.
2Reliability
If non-ejection driving signals are input between ejection driving signals when ejection interval is long, then ink ejection reliability is maintained, but device complexity increases due to additional signal control
Solution Approach 1:
The control system automatically determines whether to insert non-ejection driving signals based on the calculated ejection interval. The system self-regulates by comparing the actual time period between ejection operations against the basic time period and autonomously adjusting the driving signal pattern without external intervention, simplifying the overall control architecture while maintaining reliability.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the ejection interval and adjusting the driving signal pattern accordingly. The control unit calculates the time period between successive ejection operations and uses this feedback to determine whether non-ejection signals should be inserted, creating a closed-loop system that adapts to varying printing speeds while maintaining consistent ejection reliability.
Data Source
AI summary
A timing signal generator generates an ejection timing signal each time a printing paper travels a predetermined distance relative to a head, and a driving signal generator inputs a driving signal based on writing data to the head each time an ejection timing signal is generated. In the course of printing, when an interval between two continuous ejection timing signals is equal to or longer than twice a basic time period of input of driving signal which is fixed for a head, a non-ejection driving signal which is a driving signal indicating a non-ejecting operation is input to the head between two driving signals respectively associated the two continuous ejection timing signals. Accordingly, it is possible to reliably and properly perform ejection of ink based on writing data with a time period equal to or longer than the basic time period.