Ink Viscosity Detection via Residual Vibration Attenuation
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Solution Overview
Problem
Existing inkjet recording devices face challenges in accurately detecting small changes in ink viscosity due to variations in ON-resistance/ON-period of switching elements, leading to inconsistent ink ejection speeds and potential nozzle clogging, which affects image quality.
Innovation Solution
A method that calculates the attenuation ratio of residual vibration waveforms in the inkjet recording head to accurately detect ink viscosity, using a band-pass filter to minimize noise and variations, allowing for precise detection of small changes in viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the residual vibration detection unit uses a switching element to connect the piezoelectric element to the detection circuit, then the residual vibration waveform can be acquired, but variations in the ON-resistance/ON-period of the switching element cause large variations in the elapsed period measurement, reducing measurement precision
Solution Approach 1:
The patent extracts the measurement of vibration cycle and elapsed period from the conventional amplitude-based detection method. By separately measuring the vibration cycle (using a zero-crossing detector) and the elapsed period (using a timer), the system eliminates the dependency on switching element characteristics, thereby improving measurement precision and reliability of ink viscosity detection
Solution Approach 2:
The patent replaces the conventional amplitude-based detection method (which relies on analog signal processing and switching elements) with a time-based measurement method using digital counters and timers. This substitution of measurement principle eliminates the harmful effects of switching element variations on measurement precision
2Measurement precision
If the first half-wave amplitude value is calculated based on the ratio between vibration cycle and elapsed period, then ink viscosity can be detected, but switching element variations directly affect the elapsed period, causing large variations in amplitude values and preventing detection of small viscosity changes
Solution Approach 1:
The patent uses the measured vibration cycle and elapsed period to calculate the ink viscosity, and this detected viscosity information is fed back to correct the drive waveform. The system continuously monitors viscosity changes and adjusts the drive parameters accordingly, enabling detection of small viscosity changes while maintaining consistent ejection performance
Solution Approach 2:
The patent changes the measurement parameter from amplitude-based detection to time-based detection (measuring the elapsed period until the vibration waveform reaches a reference voltage). This parameter change eliminates the influence of switching element variations and enables precise detection of small viscosity changes
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
This approach enables accurate detection of ink viscosity changes, ensuring consistent ink ejection speeds and preventing nozzle clogging, thereby improving image quality by maintaining constant ejecting speed and amount.
Implementation Method 1
immediately after a drive voltage (drive waveform) is applied, a residual pressure wave in the individual liquid chamber (ink channel) vibrates (residual vibration) the piezoelectric element
Implementation Method 2
a piezoelectric element is used as a pressure generator element to pressurize the ink in an ink channel to cause a vibration plate that forms a wall of the ink channel to vibrate
Implementation Method 3
calculating an attenuation ratio of the residual vibration waveform... using a band-pass filter to minimize noise and variations
Data Source
AI summary
A liquid viscosity detecting method is performed in a liquid droplet ejecting device that includes a piezoelectric type droplet ejecting head to which a drive waveform is applied to pressurize a liquid chamber to eject a liquid droplet, a drive waveform generator to apply the drive waveform to the droplet ejecting head, and a residual vibration detector. The method includes detecting, by the residual vibration detector, amplitude values of multiple cycles of a residual vibration waveform occurring within the liquid chamber after the drive waveform is applied; calculating an attenuation ratio based on the amplitude values; and calculating a liquid viscosity in the liquid chamber based on the attenuation ratio.