Liquid Ejection Head Meniscus Control for Satellite Dot Elimination
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Solution Overview
Problem
Conventional ink jet heads experience deterioration in print quality due to ink droplets flying extended in the flight direction, resulting in satellite dots and mists on the medium.
Innovation Solution
A liquid ejection head with an actuator and control unit that applies specific pulses to expand and contract a pressure chamber, including a first contraction pulse and a second contraction pulse, where the second contraction pulse width includes a time point when the meniscus flow velocity becomes zero for the third time, to manage ink droplet ejection and prevent extended flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple ejection pulse is applied to the actuator, then the device complexity is low, but the ink droplet flies in an extended state causing satellite dots and mists
Solution Approach 1:
The patent applies periodic pulse signals to the actuator, specifically using a multi-stage contraction process with first and second contraction pulses separated by a predetermined time period. This periodic action controls the meniscus to move in and out of the nozzle multiple times, preventing extended ink droplet flight and eliminating satellite dots and mists, thereby improving print quality through structured temporal control patterns.
Solution Approach 2:
The patent applies a first contraction pulse before the second contraction pulse, with the first pulse causing the meniscus to move into the nozzle and the second pulse causing it to move out. This preliminary action sequence prepares the ink meniscus in controlled stages, ensuring proper droplet formation before ejection and preventing extended flight states that cause print quality deterioration.
2Speed
If the pressure chamber is contracted to a small volume rapidly, then the ejection speed is high, but the meniscus control becomes unstable causing extended flight
Solution Approach 1:
The patent uses periodic contraction pulses with a predetermined time period between the first and second contraction pulses. This periodic action allows the meniscus to oscillate in a controlled manner, moving into and out of the nozzle repeatedly, which stabilizes the meniscus during rapid volume changes and prevents extended ink droplet flight while maintaining high ejection speed.
Solution Approach 2:
The patent dynamically controls the pressure chamber volume by applying sequential contraction pulses that cause the meniscus to move dynamically in and out of the nozzle. This dynamic control, timed to include when the meniscus flow velocity becomes zero, maintains meniscus stability during rapid volume changes while enabling high-speed ejection.
3Productivity
If the pressure chamber volume is reduced significantly, then the ink droplet ejection is effective, but satellite dots and mists are generated
Solution Approach 1:
The patent applies periodic contraction pulses where the second contraction pulse is timed to include the moment when the meniscus flow velocity becomes zero after moving into the nozzle. This periodic action ensures effective ink droplet ejection by achieving significant volume reduction while simultaneously preventing satellite dots and mists by controlling the meniscus to complete its oscillation cycle, eliminating extended flight states.
4Duration of action of moving object
If the meniscus moves continuously outside the pressure chamber, then the ejection is continuous, but the ink droplet extends in flight direction
Solution Approach 1:
The patent implements periodic meniscus movement by applying sequential contraction pulses that cause the meniscus to oscillate in and out of the nozzle. This periodic action maintains continuous ejection capability while preventing droplet extension by ensuring the meniscus completes full oscillation cycles, with the second contraction pulse timed to include when the meniscus flow velocity becomes zero, thereby eliminating extended flight states and maintaining proper droplet shape.
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 satellite dots and mists, maintaining print quality by ensuring ink droplets are ejected effectively, thereby enhancing the overall print quality.
Implementation Method 1
an actuator 16 configured to expand or contract a pressure chamber 15 communicating with a nozzle 8
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
According to one embodiment, there is provided a liquid ejection head including an actuator and a control unit. The actuator expands or contracts a pressure chamber communicating with a nozzle that ejects ink. The control unit applies an expansion pulse for expanding the pressure chamber to the actuator, and then applies a first contraction pulse for contracting the pressure chamber to a first volume to the actuator, and then applies a second contraction pulse for contracting a volume of the pressure chamber to a second volume smaller than the first volume to the actuator. A width of the second contraction pulse includes a first time point when, after changing from the first contraction pulse to the second contraction pulse, a meniscus formed in the nozzle changes from a state of progressing inside the pressure chamber to a state of progressing outside the pressure chamber.