Liquid Ejection Head Delay Waveforms for Density Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In piezoelectric inkjet heads with one-dimensional nozzle arrangements, density unevenness occurs due to sub delay times in a sawtooth wave shape that is discontinuous with respect to nozzle arrangements, leading to structural or fluid mutual interference and crosstalk.
Innovation Solution
A liquid ejection head with a drive circuit that generates drive waveforms with delay times varying in a triangular wave shape for all pressure chambers in one direction and a periodic wave shape in another direction, where the periodicity of the second delay time differs from the first, to minimize time differences between adjacent nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If sub delay time is used in a sawtooth wave shape for one-dimensional nozzle arrangement, then current concentration during simultaneous driving is avoided, but density unevenness occurs at discontinuous portions
Solution Approach 1:
The patent applies asymmetry by using a triangular wave shape for the sub delay time instead of a sawtooth wave shape. This asymmetric triangular waveform eliminates the discontinuous portions present in sawtooth waves, thereby preventing density unevenness while still avoiding current concentration during simultaneous nozzle driving.
Solution Approach 2:
The patent changes the waveform parameter from sawtooth to triangular wave for the sub delay time. This parameter change modifies the temporal distribution of delay times across nozzles, eliminating the discontinuous jumps that cause density unevenness while maintaining the current distribution benefits.
2Power
If delay time is optimized for current distribution, then simultaneous driving current concentration is reduced, but structural or fluid mutual interference (crosstalk) between nozzles occurs
Solution Approach 1:
The patent applies local quality by setting different delay time characteristics for different nozzle groups. The main delay time varies in a triangular wave shape across all nozzles, while the sub delay time varies periodically for grouped nozzles. This localized differentiation optimizes current distribution for each group while minimizing crosstalk between adjacent nozzles.
Solution Approach 2:
The patent segments nozzles into multiple groups and applies different delay time strategies to each group. By dividing nozzles into groups with periodic sub delay times and applying triangular wave main delay times across all groups, the system achieves both current distribution optimization and crosstalk reduction.
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
Prevents density unevenness and reduces crosstalk by optimizing delay times, ensuring consistent ejection speeds and preventing variations in nozzle performance.
Implementation Method 1
a plurality of pressure chambers that respectively communicate with the nozzles, a volume of each of the pressure chambers being varied to eject liquid through the corresponding nozzle; an actuator configured to vary the volumes of the pressure chambers independently according to drive waveforms respectively applied to the pressure chambers
Implementation Method 2
the drive circuit determines the first delay time based on a pressure propagation time of the liquid in the pressure chambers
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A liquid ejection head includes nozzles arranged in a first direction, pressure chambers respectively communicating with the nozzles, a volume of each chamber being varied to eject liquid through the nozzle, an actuator varying the volumes according to drive waveforms applied to the chambers, and a drive circuit generating a drive waveform for each chamber with a delay time to cause the liquid to be ejected with the delay time. The drive circuit determines the delay time to be a sum of: a first delay time for the particular chamber, the first delay time for all the chambers varying so as to have a triangular wave shape with respect to positions of the chambers, and a second delay time for the particular chamber, the second delay time for all the chambers varying so as to have a periodic wave shape with respect to the positions of the chambers.