Inkjet Head Drive Waveform Timing for Velocity Deviation
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Solution Overview
Problem
Inkjet recording devices face challenges in suppressing velocity deviation caused by resonance frequency variations among piezoelectric actuators when handling multi-tone waveforms, leading to suboptimal recording quality.
Innovation Solution
The implementation of an inkjet recording device with multiple actuators and a drive signal comprising multiple drive waveform elements, where the time between drive waveform cycles is adjusted to fall within the range of 1.1 to 1.4 times the natural vibration cycle, ensuring uniform droplet speed across channels and minimizing satellite droplet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a multi-tone waveform with many tones (5 or more) is used to express fine gradation, then the recording quality should be improved, but variation in resonance frequency among piezoelectric actuators causes velocity deviation that deteriorates recording quality
Solution Approach 1:
The patent applies parameter changes by adjusting the drive waveform generation frequency to be lower than the reference frequency, and modifying the duty ratio of drive waveform elements based on cumulative liquid discharge amounts. This compensates for velocity deviations caused by resonance frequency variations among piezoelectric actuators, ensuring consistent droplet ejection speeds across all channels while maintaining fine gradation capability with 5 or more tones.
2Quantity of substance
If droplet discharge motions are continued to unite multiple droplets for gradation control, then the liquid amount per droplet can be adjusted for shading control, but unwanted microdroplets (satellites) are generated that deteriorate recording quality
Solution Approach 1:
The patent employs periodic action by using multiple drive waveform elements with specific timing intervals between them. The drive waveforms are applied periodically with controlled intervals that allow droplets to unite properly without generating satellite droplets. This periodic drive pattern enables precise control of liquid amount while suppressing harmful satellite formation.
3Device complexity
If the waveform generation frequency is set for a reference channel to simplify multi-tone waveform generation, then the device complexity is reduced, but velocity variation among channels cannot be suppressed due to resonance frequency variation
Solution Approach 1:
The patent applies local quality by individually adjusting the duty ratio of drive waveform elements for each channel based on its specific liquid discharge characteristics. Instead of using a uniform frequency for all channels, each channel receives customized drive parameters that compensate for its resonance frequency variations, ensuring velocity uniformity while maintaining relatively simple waveform generation structure.
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 effectively suppresses velocity deviation among inkjet heads, enhancing the quality of recording by maintaining consistent droplet speed and reducing unwanted microdroplet generation, thereby improving image gradation and overall print quality.
Implementation Method 1
a plurality of actuators which give a pressure change to the ink in the plural inkjet heads by a prescribed drive operation
Implementation Method 2
when Tc is the natural vibration cycle determined from the inkjet head structure, time Ts from the start point of the drive waveform to the start point of the subsequent drive waveform fulfills the relationship 1.1≤Tc≤Ts≤1.4Tc
Data Source
AI summary
The present invention discharges ink from a plurality of inkjet heads and is used when performing drive whereby one droplet or a plurality of droplets are discharged onto and united on one pixel. A drive signal includes a drive waveform comprising N number (N being an integer of at least 2) of drive waveform elements and is configured so as to fulfil the relationship 1.1 Tc≤Ts≤1.4 Tc, when Tc is the natural vibration cycle determined from the inkjet head structure and Ts is the time from the start point of the drive waveform to the start point of the subsequent drive waveform. As a result, velocity deviation caused by the resonant frequency of a piezoelectric actuator driving the inkjet head can be suppressed when driving an inkjet head using multiple gradations.