Drive Signal Circuit With Switchable Inductance for High-Frequency Piezo Drive
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Solution Overview
Problem
Existing liquid ejecting apparatuses using piezoelectric elements face challenges in achieving high-frequency drive signals due to insufficient drive circuit performance.
Innovation Solution
A drive signal output circuit comprising a modulation circuit, an amplifier circuit, and a demodulation circuit with an inductive and capacitive circuit, and a switch circuit to modulate, amplify, and demodulate signals, allowing for switching between different inductance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional amplifier circuit is used to drive piezoelectric elements, then the circuit structure is simple, but the drive signal frequency is insufficient to achieve high-frequency operation
Solution Approach 1:
The drive circuit is segmented into three functional modules: modulation circuit (generates modulated drive signal), amplifier circuit (amplifies the modulated signal), and demodulation circuit (recovers the drive signal). This segmentation allows each module to be optimized for its specific function, enabling high-frequency operation while maintaining manageable overall complexity
Solution Approach 2:
A modulated signal is introduced as an intermediary between the base drive signal and the final amplified drive signal. The modulation circuit modulates the base signal at a higher frequency, the amplifier amplifies this modulated signal, and the demodulation circuit recovers the final drive signal. This intermediary approach enables the amplifier to operate at higher frequencies than would be possible with conventional direct amplification
2Adaptability or versatility
If the inductance value of the inductive circuit is fixed, then the circuit design is simple, but the drive signal frequency cannot be optimized for different operating conditions
Solution Approach 1:
The inductive circuit transitions from a fixed inductance design to a dynamic inductance switching design. The switch circuit enables selective connection of different inductors (L1, L2, L3) based on operating conditions, allowing the total inductance to be dynamically adjusted. This dynamic adaptation optimizes the drive signal frequency for different liquid ejection requirements while the control logic manages the switching complexity
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
Enhances the capability to generate high-frequency drive signals for efficient operation of piezoelectric elements, improving the ejection of liquids in the liquid ejecting apparatus.
Implementation Method 1
The demodulation circuit includes an inductive circuit, a capacitive circuit, and a switch circuit. The amplified modulated signal is input to a first end of the inductive circuit, and a second end of the inductive circuit is electrically coupled to a first end of the capacitive circuit. The demodulation circuit outputs the drive signal from a coupling point where the second end of the inductive circuit and the first end of the capacitive circuit are electrically coupled.
Implementation Method 2
As a liquid ejecting apparatus that forms an image or a document on a medium by ejecting liquid, an apparatus using a piezoelectric element is known. In such a liquid ejecting apparatus, piezoelectric elements are provided corresponding to respective nozzles from which liquid is ejected, and each of the piezoelectric elements is driven based on a drive signal.
Data Source
AI summary
A drive signal output circuit outputs a drive signal for driving a capacitive load and includes: a modulation circuit that modulates a base drive signal on which the drive signal is based, and outputs the modulated base drive signal as a modulated signal, an amplifier circuit that amplifies the modulated signal and outputs the amplified modulated signal, and a demodulation circuit that demodulates the amplified modulated signal and outputs the demodulated signal as the drive signal. The demodulation circuit includes an inductive circuit, a capacitive circuit, and a switch circuit. The amplified modulated signal is input to a first end of the inductive circuit. A second end of the inductive circuit is electrically coupled to a first end of the capacitive circuit. The switch circuit switches an inductance value of the inductive circuit between a first inductance value and a second inductance value different from the first inductance value.