Head Unit Capacitor Placement for Piezoelectric Drive Signal Stability
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Solution Overview
Problem
Existing techniques for reducing signal waveform distortion in piezoelectric element drive signals in liquid ejection apparatuses are insufficient, necessitating further improvements.
Innovation Solution
A head unit configuration with a first print head and drive unit that includes a first drive circuit, a reference voltage signal output circuit, a capacitor, and a wiring substrate, where the capacitor is positioned to minimize signal propagation distances and stabilize voltage values, ensuring optimal signal transmission to piezoelectric elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive signal is transmitted through the wiring substrate to the piezoelectric element, then the liquid ejection apparatus can operate, but signal waveform distortion occurs
Solution Approach 1:
A capacitor is introduced as an intermediary component between the drive circuit and the piezoelectric element. The capacitor serves as a voltage buffer that stabilizes the reference voltage signal, filtering out high-frequency noise and transient voltage fluctuations that cause waveform distortion. This mediator component allows the drive signal to be transmitted reliably while maintaining waveform precision.
Solution Approach 2:
The patent changes the electrical parameters of the signal transmission path by adding the capacitor, which modifies the impedance and voltage stability characteristics. The capacitor alters the time constant and voltage filtering properties of the circuit, transforming the signal transmission characteristics to reduce distortion while maintaining reliable operation.
2Manufacturing precision
If the capacitor is positioned closer to the output connector, then signal propagation distance is reduced and voltage stabilization is improved, but the wiring substrate layout becomes more complex
Solution Approach 1:
The capacitor is positioned asymmetrically in the wiring substrate layout, closer to the output connector rather than at the center or equal distance from both ends. This asymmetric placement optimizes the signal propagation path by reducing the distance between the capacitor and the output connector, thereby improving voltage stabilization at the critical point where the signal is delivered to the piezoelectric element.
Solution Approach 2:
The capacitor is strategically placed at a specific location in the wiring substrate where voltage stabilization is most needed - closer to the output connector. This local placement concentrates the voltage buffering function at the critical point of signal delivery, improving waveform precision where it matters most rather than distributing components uniformly throughout the circuit.
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 configuration reduces signal waveform distortion, enhancing the precision and reliability of ink ejection in liquid ejection apparatuses, thereby improving image quality and operational stability.
Implementation Method 1
a first capacitor having a first electrode supplied with the first reference voltage signal, and a second electrode supplied with a ground signal
Implementation Method 2
a liquid ejection apparatus using a piezoelectric element. The piezoelectric element is provided so as to correspond to each of a plurality of ejection parts in a print head. Further, by the piezoelectric element being driven in accordance with a drive signal, a corresponding amount of liquid to drive of the piezoelectric element is ejected from the ejection part corresponding thereto
Data Source
AI summary
A head unit includes a wiring substrate including a first side, a second side located so as to face the first side, and a first supply point supplied with a first drive signal, wherein a first capacitor having a first electrode supplied with a first reference voltage signal and a second electrode supplied with a ground signal is located between an output connector electrically coupled to a first print head and the first supply point when viewed along a second axis perpendicular to a first axis connecting the first side and the second side, and a shortest distance between the output connector and the first electrode is shorter than a shortest distance between the output connector and the second electrode, and a shortest distance between the first supply point and the first electrode is longer than a shortest distance between the first supply point and the second electrode.