Liquid Ejecting Drive Circuit with Staged Amplification and Level Shifting
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Solution Overview
Problem
Existing drive circuits for piezoelectric-based liquid ejecting apparatuses, such as inkjet printers, face challenges in waveform accuracy and switching element losses, necessitating improvements in signal modulation and amplification to enhance drive signal quality.
Innovation Solution
A drive circuit design incorporating a modulation circuit, level switching signal generation, and amplification level shift circuit with specific on-resistance configurations for switching elements to improve drive signal accuracy and efficiency, including a demodulation circuit to output the final drive signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional amplification circuit is used to amplify the base drive signal, then the drive signal can be generated, but the waveform accuracy deteriorates and switching element losses increase
Solution Approach 1:
The amplification process is divided into multiple stages with different functions: a first amplification circuit amplifies the base drive signal to generate an intermediate signal, while a second amplification circuit amplifies the intermediate signal to generate the final drive signal. This segmentation allows each stage to be optimized for its specific function, improving overall waveform accuracy and reducing losses.
Solution Approach 2:
An intermediate signal is introduced as a mediator between the base drive signal and the final drive signal. The intermediate signal serves as a transition stage that allows for better control and optimization of the amplification process, thereby improving waveform accuracy and reducing switching element losses.
2Loss of energy
If the on-resistance of switching elements is reduced to decrease losses, then switching element losses decrease, but the waveform accuracy of the drive signal deteriorates
Solution Approach 1:
Different switching elements are assigned different on-resistance values according to their specific functions in the amplification circuit. The first switching element in the first amplification circuit has a different on-resistance than the second switching element in the second amplification circuit, allowing each to be optimized for its local requirements rather than using a uniform design.
Solution Approach 2:
The on-resistance parameter of switching elements is varied based on their position and function in the amplification circuit. By changing the on-resistance parameter appropriately for each switching element, the circuit achieves both low losses and high waveform accuracy simultaneously.
3Device complexity
If a single-stage amplification circuit is used, then the device complexity is reduced, but the drive signal waveform accuracy deteriorates
Solution Approach 1:
The amplification circuit is segmented into multiple stages, each performing a specific amplification function. This segmentation improves waveform accuracy by allowing progressive amplification with appropriate buffering and signal conditioning at each stage, while the modular structure keeps the overall design manageable.
Data Source
AI summary
A drive circuit includes a modulation circuit that outputs a modulation signal, a level switching signal generation circuit that generates a level switching signal, an amplification level shift circuit that includes a first switching element and a second switching element that perform switching in response to the modulation signal, and a third switching element and a fourth switching element that perform switching in response to the level switching signal, outputs an amplified modulation signal obtained by amplifying the modulation signal, or outputs a signal obtained by shifting a potential of the amplified modulation signal, and a demodulation circuit that demodulates the signal output from the amplification level shift circuit, and outputs the drive signal. On-resistances of the first switching element and the second switching element are larger than an on-resistance of the third switching element and an on-resistance of the fourth switching element.