Capacitive Load Drive Circuit Noise Cancellation
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Solution Overview
Problem
Noise generated by potential changes in drive signals affects the signal quality in liquid ejection apparatuses, such as ink jet printers, leading to ejection failures and incorrect determination of ejection states.
Innovation Solution
A liquid ejection apparatus and capacitive load drive circuit design that uses two piezoelectric elements with specific drive signal waveforms, where the first drive signal transitions from one potential to another and back, and the second drive signal transitions in a complementary manner, with overlapping periods to minimize noise interference, and a flexible flat cable configuration to reduce noise impact on control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive signals are supplied to piezoelectric elements for liquid ejection, then liquid ejection function is achieved, but noise is generated that affects signal quality and causes ejection failures
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by converting the harmful noise generated during drive signal transitions into a beneficial effect. Specifically, the invention uses the noise period (when potential changes occur) to advance the transition timing of complementary piezoelectric elements. By making the second element transition earlier during the noise period, the system utilizes the unavoidable noise to achieve better overall noise cancellation, thereby improving signal quality and ejection reliability.
2Speed
If drive signal transitions are made faster to improve response, then ejection speed increases, but noise interference on signals increases
Solution Approach 1:
The patent applies 'Periodic action' by using periodic drive signals with specifically designed transition periods. The drive signals alternate between different potential levels in a periodic manner, with carefully controlled transition timing. The first piezoelectric element transitions during non-noise periods while the second element transitions during noise periods, creating a periodic pattern that maintains fast response while distributing noise interference across different time intervals for effective cancellation.
3Object-affected harmful factors
If overlapping drive periods are used for multiple piezoelectric elements, then noise cancellation is improved, but control complexity increases
Solution Approach 1:
The patent applies 'Segmentation' by dividing the drive signal control into distinct segments or phases. The control period is segmented into different regions: noise periods when the first element transitions, non-noise periods when the second element transitions, and overlapping periods where both elements are actuated. This segmentation simplifies the control logic by providing clear temporal boundaries for each element's transition, making the overlapping drive periods easier to manage despite the increased complexity of noise cancellation.
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 design effectively suppresses noise interference, reducing ejection failures and improving the accuracy of ejection state determination, thereby enhancing the reliability and performance of the liquid ejection apparatus.
Implementation Method 1
a first piezoelectric element that is actuated according to a supply of a first drive signal
Data Source
AI summary
A liquid ejection head includes a first piezoelectric element that is supplied with a first drive signal, and a second piezoelectric element that is supplied with a second drive signal, wherein the first drive signal transitions from a first potential to a second potential in a first period, maintains the second potential during a second period, and transitions from the second potential to the first potential in a third period, wherein the second drive signal transitions from a third potential to a fourth potential in a fourth period, maintains the fourth potential during a fifth period, and transitions from the fourth potential to the third potential in a sixth period, wherein the first period and the fourth period overlap, wherein the third period and the sixth period overlap, wherein the second potential is higher than the first potential, and wherein the fourth potential is lower than the third potential.