Piezoelectric Inkjet Head Drive Control for Element Life Extension
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Solution Overview
Problem
Ink-jet printers with line heads face premature degradation of piezoelectric elements due to high usage frequency, leading to reduced drive performance and shortened lifespan, as the polarization of piezoelectric layers weakens with repeated drive pulses, making it difficult to extend the life of these elements.
Innovation Solution
A printing apparatus with a controller that adjusts the discharge energy applied to the liquid based on usage thresholds, reducing the energy when a predetermined value is exceeded to prolong the life of the piezoelectric elements by applying a lower discharge energy when forming dots on the printing medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezoelectric element is driven with high frequency to maintain printing performance, then printing productivity is improved, but the life of the piezoelectric element deteriorates due to polarization weakening
Solution Approach 1:
The patent applies dynamics by making the drive pulse characteristics adjustable rather than fixed. The controller dynamically changes the drive pulse width and amplitude based on the accumulated usage count of each piezoelectric element, allowing the system to adapt to degradation and extend element life while maintaining printing productivity.
Solution Approach 2:
The patent changes physical parameters (drive pulse width and amplitude) based on usage conditions. When the usage count exceeds a threshold, the controller reduces the drive pulse width and/or amplitude to lower the discharge energy, thereby reducing strain on the piezoelectric element and extending its operational life.
2Duration of action of stationary object
If the discharge energy is reduced to extend piezoelectric element life, then element durability is improved, but printing quality may deteriorate
Solution Approach 1:
The patent applies partial action by selectively reducing discharge energy only for specific piezoelectric elements that have exceeded usage thresholds, while maintaining full discharge energy for elements with lower usage counts. This allows the system to extend life for worn elements without compromising overall printing quality.
Solution Approach 2:
The patent uses feedback mechanisms where the controller monitors the usage count of each piezoelectric element and adjusts drive parameters accordingly. This feedback loop ensures that discharge energy is reduced only when necessary based on actual element condition, maintaining printing quality while extending element life.
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 prolongs the life of the piezoelectric elements by reducing the strain on them, allowing for continued printing without significant degradation in image quality, even when usage thresholds are met, thereby extending the operational life of the ink-jet head.
Implementation Method 1
a piezoelectric actuator arranged on the upper surface of the flow passage unit to apply a pressure to an ink inside the pressure chambers. The piezoelectric actuator has three piezoelectric layers which are stacked on the upper surface of the flow passage unit, and common electrodes and individual electrodes which are formed respectively on the lower surface and upper surface of the uppermost piezoelectric layer so as to sandwich the uppermost piezoelectric layer on the portions facing the plurality of pressure chambers.
Implementation Method 2
when a drive pulse is applied to an individual electrode to generate a potential difference between the individual electrode and a common electrode which is maintained at the ground potential, in the same direction as the direction of polarization of the piezoelectric layer, a downward electric field is generated in the portion of the piezoelectric layer sandwiched by those electrodes.
Data Source
AI summary
A printing apparatus includes: a liquid discharge head which includes a nozzle which discharges a liquid, and a discharge energy applying section which applies a discharge energy to the liquid to be discharged from the nozzle; a drive section which drives the discharge energy applying section; and a controller which controls the drive section based on a parameter about a usage amount of the discharge energy applying section; and when one dot is formed on a printing medium by discharging the liquid, if a predetermined threshold value is not exceeded by the parameter, the controller controls the drive section to drive the discharge energy applying section so that a first discharge energy is applied to the liquid, and otherwise, the controller controls the drive section to drive the discharge energy applying section so that a second discharge energy lower than the first discharge energy is applied to the liquid.