Piezoelectric Inkjet Head Residual Vibration Detection Circuit
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Solution Overview
Problem
Existing liquid discharging apparatuses face challenges in efficiently detecting residual vibration of piezoelectric elements due to high power voltage requirements, leading to increased dynamic range and noise issues in head abnormality detection.
Innovation Solution
A liquid discharging apparatus is designed with a first high-pass filter, a residual vibration detecting section, and specific switching configurations to AC couple the piezoelectric element and detecting section, reducing power voltage requirements and minimizing noise by using a third resistor for potential biasing and a third switch for signal clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the piezoelectric element is directly connected to the head abnormality detecting unit after switching from driving signal application to electromotive force detection, then the detection can be performed immediately, but the dynamic range of the detecting unit must be increased and high voltage power supply is required
Solution Approach 1:
A capacitor is introduced as an intermediary component between the piezoelectric element and the head abnormality detecting unit. This capacitor acts as a coupling element that blocks the high-voltage driving signal while allowing the low-voltage electromotive force to pass through, enabling the detecting unit to operate at low voltage without compromising detection accuracy
Solution Approach 2:
The connection path is segmented into two distinct stages: a driving signal application stage and an electromotive force detection stage. Switches are used to isolate these stages, ensuring that the high-voltage driving signal does not interfere with the low-voltage detection process, thereby allowing the detecting unit to operate at reduced voltage
2Loss of time
If the piezoelectric element is directly connected to detect residual vibration, then the detection response is immediate, but switching noise from the driving signal interferes with the detection
Solution Approach 1:
The capacitor serves as a noise-filtering intermediary that blocks high-frequency switching noise from the driving signal while allowing the lower-frequency electromotive force to pass through to the detecting unit, thereby reducing noise interference without delaying detection
Solution Approach 2:
The capacitor is pre-charged during the driving signal application stage, storing energy that maintains the potential level during the transition to detection mode. This preliminary action ensures a smooth transition without generating additional switching noise
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 allows for accurate detection of residual vibration at lower power voltages, reducing switching noise and operational complexity, while maintaining detection accuracy without delay.
Implementation Method 1
a piezoelectric element which is provided corresponding to the pressure chamber in order to discharge liquid droplets; a residual vibration detecting section which detects changes, in an electromotive force of the piezoelectric element in accordance with the residual vibration inside the pressure chamber
Data Source
AI summary
An ink jet printer is provided with a piezoelectric element which is provided corresponding to a pressure chamber in order to discharge liquid droplets, a driving signal generating section which generates a driving signal, a residual vibration detecting section which detects changes in an electromotive force of the piezoelectric element in accordance with the residual vibration inside the pressure chamber which occur after the driving signal is applied, a first switch which switches whether or not a driving signal is applied to the piezoelectric element, and a second switch which switches whether or not a change in the electromotive force is supplied to a first high-pass filter, where the second switch and the residual vibration detecting section are connected via a first capacitor of the first high-pass filter.