Piezoelectric Pressure-Chamber Fill Detection for Liquid Ejection
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Solution Overview
Problem
Conventional image forming apparatuses lack a mechanism to determine the completion of ink filling in pressure chambers, leading to unnecessary continuation of filling processing.
Innovation Solution
Incorporation of a residual vibration detection circuit that analyzes the frequency of electric signals generated by piezoelectric elements to detect whether pressure chambers are filled with ink, using a drive signal that does not cause ink ejection, and determining the filled state based on specific frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink filling processing is continuously performed without determination mechanism, then ink supply reliability is improved, but processing time is increased and productivity deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the piezoelectric element detects vibration signals from the pressure chamber during ink filling. The determination processing portion analyzes these signals to generate determination results that feedback to control the filling process termination, enabling automatic stopping when filling is complete
Solution Approach 2:
The patent replaces mechanical level sensors or complex filling control mechanisms with an electrical detection system using the piezoelectric element. The piezoelectric element converts mechanical vibration into electrical signals that can be processed electronically to determine filling completion
2Productivity
If vibration detection is used to determine ink filling completion, then processing time is reduced and productivity is improved, but measurement precision may deteriorate due to signal noise
Solution Approach 1:
The patent introduces an output processing portion as an intermediary between the piezoelectric element and the determination processing portion. This intermediary processes the raw vibration signals, filtering and conditioning them to remove noise while preserving the essential filling completion information
Solution Approach 2:
The patent transforms the physical vibration parameter into an electrical signal parameter through the piezoelectric element. By analyzing changes in electrical signal characteristics (frequency, amplitude, waveform) rather than directly measuring mechanical vibration, the system achieves more precise and reliable detection
3Device complexity
If piezoelectric element is used for both ink ejection and vibration detection, then device complexity is reduced, but measurement precision deteriorates due to signal interference
Solution Approach 1:
The patent employs periodic drive signals applied to the piezoelectric element during ink filling. By using periodic excitation and analyzing the resulting periodic vibration responses, the system can distinguish between ejection-related signals and filling-related vibration signals through frequency domain analysis
Solution Approach 2:
The patent performs preliminary processing of the piezoelectric element output signals through the output processing portion before determination. This preliminary action separates the signal processing function from the determination function, allowing for noise filtering and signal conditioning that improves detection precision while maintaining the multi-functionality of the piezoelectric element
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
Enables precise determination of ink filling completion in pressure chambers, thereby optimizing ink supply and reducing unnecessary processing time.
Implementation Method 1
a piezoelectric element configured to change a pressure in the pressure chamber in response to an input of a drive signal
Implementation Method 2
an output processing portion configured to cause the piezoelectric element to output a first electric signal corresponding to vibration generated in the pressure chamber
Data Source
AI summary
A liquid ejection apparatus includes a nozzle, a pressure chamber, a piezoelectric element, an output processing portion, and a determination processing portion. The nozzle ejects a liquid. The pressure chamber communicates with the nozzle and contains the liquid. The piezoelectric element changes a pressure in the pressure chamber in response to an input of a drive signal. The output processing portion causes the piezoelectric element to output a first electric signal corresponding to vibration generated in the pressure chamber in response to the input of the drive signal to the piezoelectric element. The determination processing portion determines whether or not the pressure chamber is in a filled state in which the pressure chamber is filled with the liquid, based on a frequency of the first electric signal output by the output processing portion.