Piezoelectric Head Deterioration Sensing by Integrated Current
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Solution Overview
Problem
Existing methods for determining the deterioration of a liquid ejecting apparatus, such as an ink jet printer, are inaccurate due to factors like environmental temperature and applied voltage, in addition to the number of ejecting cycles, leading to unreliable estimation of the piezoelectric body's condition.
Innovation Solution
A method and apparatus that utilize a voltage application circuit to gradually change voltage from a first to a second voltage, integrating the current generated to acquire the degree of deterioration based on information regarding the integral value or maximum strain of the piezoelectric body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the degree of deterioration is estimated based only on the number of times of ejecting, then the estimation process is simple, but the accuracy of deterioration assessment is insufficient due to ignoring temperature and voltage factors
Solution Approach 1:
The patent replaces the mechanical counting method (simple ejecting cycle counting) with an electrical measurement system that integrates current values. By measuring the integral of current flowing through the piezoelectric body during voltage application, the system obtains a more accurate deterioration indicator that inherently accounts for temperature and voltage effects, thus improving measurement precision while maintaining reasonable system complexity
Solution Approach 2:
The patent introduces the integral current value as an intermediary parameter that mediates between the complex physical conditions (temperature, voltage, cycle count) and the deterioration assessment. This intermediary measurement captures the cumulative effect of all operating conditions on the piezoelectric body, providing a comprehensive deterioration metric without requiring direct measurement of each individual factor
2Measurement precision
If environmental temperature and applied voltage are considered in deterioration estimation, then the accuracy of deterioration assessment improves, but the complexity of the assessment method increases
Solution Approach 1:
The patent merges the effects of temperature, voltage, and ejecting cycle count into a single integrated measurement - the integral current value. By applying a voltage to the piezoelectric body and integrating the resulting current over time, the system combines multiple deterioration-influencing factors into one comprehensive parameter, improving assessment accuracy without proportionally increasing system complexity
Solution Approach 2:
The piezoelectric body itself serves as the sensor for deterioration detection. The current flowing through the piezoelectric body during voltage application naturally reflects its deteriorated state, eliminating the need for separate sensors or complex measurement systems. The component being assessed performs the assessment function, simplifying the overall system while improving accuracy
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
Accurately assesses the deterioration of the piezoelectric body by considering integral current values and strain, providing a reliable measure of the apparatus's condition.
Implementation Method 1
a piezoelectric body configured to apply pressure to the liquid in the pressure chamber to eject the liquid from the nozzle
Implementation Method 2
acquire a degree of deterioration of the piezoelectric body, based on information regarding an integral value of a current generated when the voltage applied to the piezoelectric body is gradually changed
Data Source
AI summary
A liquid ejecting apparatus includes: a liquid ejecting head including a nozzle that ejects liquid, a pressure chamber, and a piezoelectric body that applies pressure to the liquid in the pressure chamber to eject the liquid from the nozzle; a voltage application circuit configured to apply a voltage to the piezoelectric body; and an acquisition section configured to acquire a degree of deterioration of the piezoelectric body, based on information regarding an integral value of a current generated when the voltage applied to the piezoelectric body is gradually changed from a first voltage to a second voltage.