Print Head Piezo Drive Signal Stabilization
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Solution Overview
Problem
In ink jet printers, unintended electric charges accumulate on piezoelectric elements due to leakage currents or noise, leading to unstable voltage, unintended displacement, and potential cracks in the vibration plate, affecting ink ejection accuracy.
Innovation Solution
A print head design incorporating a low pass filter circuit and dual switch circuits to control the drive signal to the piezoelectric elements, ensuring stable voltage and preventing unintended displacement by switching between drive signal supply states based on a switching control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single switch circuit is used to control drive signal supply to the piezoelectric element, then the device complexity is reduced, but the electric potential stability deteriorates due to charge accumulation
Solution Approach 1:
The single switch circuit is segmented into two switch circuits (first and second switch circuits) that operate in coordination. The first switch circuit controls the main drive signal path while the second switch circuit controls a discharge path to ground, allowing independent control of charge accumulation and discharge processes to maintain electric potential stability
Solution Approach 2:
A low pass filter circuit is introduced as an intermediary component between the drive signal source and the piezoelectric element. This filter circuit smooths out voltage fluctuations and prevents high-frequency noise from causing unintended charge accumulation, thereby stabilizing the electric potential without requiring additional switch circuits
2Use of energy by moving object
If the switch circuit is controlled to block drive signal supply, then energy consumption is reduced, but unintended charge accumulation occurs leading to piezoelectric element displacement
Solution Approach 1:
Before completely blocking the drive signal supply to reduce energy consumption, the second switch circuit is activated in advance to provide a discharge path for accumulated charges. This preliminary action prevents unintended charge accumulation that would otherwise cause piezoelectric element displacement and maintain ejection accuracy during low-power states
Solution Approach 2:
The control circuit monitors the operational state of the piezoelectric element and dynamically adjusts the switching of both switch circuits. When charge accumulation is detected or anticipated, the second switch circuit is activated to discharge charges, providing feedback control that maintains ejection accuracy while optimizing energy consumption
3Stability of the object's composition
If drive signal is continuously supplied to maintain stable voltage, then electric potential stability is improved, but unintended displacement occurs due to accumulated charges
Solution Approach 1:
Instead of continuous drive signal supply, the system employs periodic switching of the two switch circuits. The first switch circuit supplies drive signals in periodic bursts to maintain necessary voltage levels, while the second switch circuit periodically activates to discharge accumulated charges, creating a rhythmic on-off pattern that maintains stability without causing unintended displacement
Solution Approach 2:
The system transitions from a static continuous supply mode to a dynamic switching mode where both switch circuits are controlled based on real-time operational requirements. The switching timing and duration are dynamically adjusted to maintain electric potential stability while preventing charge accumulation that would cause precision loss in displacement control
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
The solution stabilizes the electric potential of piezoelectric elements, reducing unintended displacement and crack formation in the vibration plate, thereby enhancing the accuracy and reliability of ink ejection.
Implementation Method 1
a piezoelectric element that includes a first electrode supplied with a drive signal and a second electrode supplied with a reference voltage signal and is displaced by a difference in electric potential between the first electrode and the second electrode
Data Source
AI summary
A print head includes a piezoelectric element that includes a first electrode supplied with a drive signal and a second electrode supplied with a reference voltage signal and is displaced by a difference in electric potential between the first electrode and the second electrode, a cavity that is filled with a liquid ejected from a nozzle along with the displacement of the piezoelectric element, a vibration plate that is disposed between the cavity and the piezoelectric element, a low pass filter circuit that is supplied with the drive signal, a first switch circuit that switches between supplying and not supplying the drive signal to the first electrode, and a second switch circuit that switches between supplying and not supplying the drive signal after passing through the low pass filter circuit to the first electrode.