Drive Circuit Ripple Reduction in Liquid Ejecting Apparatus
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Solution Overview
Problem
Existing liquid ejecting apparatuses face challenges in maintaining high precision of the drive signal waveform due to increased load current and parasitic inductance, leading to noise and ripple in the drive signal, which affects the precision of ink ejection in high-speed and high-resolution printing.
Innovation Solution
A liquid ejecting apparatus with a drive circuit that includes a comparator, a transistor pair, and a control signal generation circuit, where the high-side and low-side transistors are alternately set on based on the comparison between the source drive signal and a feedback signal, reducing ripple and improving the similarity of the drive signal to the source drive signal, thereby enhancing waveform precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of nozzles is increased to satisfy high-speed and high-resolution printing demands, then productivity is improved, but the load current increases greatly causing noise and ripple in the drive signal which deteriorates manufacturing precision
Solution Approach 1:
The patent introduces a feedback mechanism where the drive signal is fed back to the comparator to compare with the source drive signal. This feedback loop enables real-time monitoring and correction of voltage deviations caused by parasitic inductance, thereby maintaining drive signal precision even when driving a large number of nozzles simultaneously.
Solution Approach 2:
The patent introduces an intermediary circuit between the drive circuit and the piezoelectric elements that includes a comparator and control signal generation circuit. This intermediary monitors the drive signal quality and dynamically adjusts transistor switching to compensate for noise and ripple, acting as a mediator that protects the precision of the drive signal despite high load conditions.
2Use of energy by moving object
If D grade amplification scheme is used to improve energy efficiency, then use of energy is improved, but power consumed by the low pass filter cannot be ignored which worsens loss of energy
Solution Approach 1:
The patent extracts and removes the low pass filter from the D grade amplification system. By eliminating this energy-consuming component, the system maintains the energy efficiency benefits of D grade amplification while avoiding the additional power consumption associated with filtering, thus reducing overall energy loss.
Solution Approach 2:
Instead of using a low pass filter to achieve smooth output in D grade amplification, the patent inverts the approach by using a comparator-based feedback system that actively monitors and corrects voltage deviations. This alternative method achieves the same smoothing effect without the energy penalty of traditional filtering.
3Speed
If the voltage of source drive signal changes rapidly to improve response speed, then speed is improved, but the change rate of load current increases which worsens the noise level due to parasitic inductance
Solution Approach 1:
The feedback mechanism continuously compares the actual drive signal voltage with the source drive signal voltage. When rapid voltage changes cause current spikes that generate noise through parasitic inductance, the feedback loop detects the deviation and triggers corrective switching actions to suppress the noise and maintain signal integrity.
Solution Approach 2:
The comparator-based control system performs preliminary anti-action by detecting voltage deviations before they propagate as noise. The control signal generation circuit proactively adjusts transistor switching to counteract the effects of rapid current changes, preventing noise generation rather than correcting it after occurrence.
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 improves the precision of the drive signal waveform and ink ejection, reducing errors and maintaining high precision even at high load capacities and frequencies, suitable for high-speed and high-resolution printing.
Implementation Method 1
a piezoelectric element is used for a liquid ejecting apparatus, such as an ink jet printer, that ejects ink and thus prints an image or a document
Implementation Method 2
a comparator compares a voltage of a source drive signal which is a source of the drive signal and a voltage of a feedback signal
Implementation Method 3
switching operation of a transistor pair which is configured with a high-side transistor and a low-side transistor is controlled based on a modulation signal
Implementation Method 4
the source drive signal is amplified by filtering an output signal of the transistor pair with a low pass filter
Data Source
AI summary
Provided a liquid ejecting apparatus including: a head that includes a piezoelectric element which is displaced by application of a drive signal; a transistor pair that includes a high-side transistor and a low-side transistor and outputs the drive signal; and a control signal generation circuit which generates a first control signal that controls switching operation of the high-side transistor and a second control signal that controls switching operation of the low-side transistor, in which the high-side transistor is set to be on and thus a voltage of the drive signal rises, and the low-side transistor is set to be on and thus the voltage of the drive signal drops, and in which the control signal generation circuit generates the first control signal and the second control signal in such a manner that the high-side transistor and the low-side transistor are alternately set to be on.