Liquid Ejecting Head Flow-Path Timing for Pressure Wave Control
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Solution Overview
Problem
Existing liquid ejecting heads with multiple pressure chambers for nozzle ejection lack effective drive control methods, leading to inefficiencies and potential issues such as excessive pressure wave attenuation and reduced ejection efficiency, particularly when using high-viscosity inks.
Innovation Solution
The liquid ejecting head incorporates a configuration where the flow path lengths from pressure chambers to the nozzle are varied, with shorter paths for some chambers, and the driving elements are timed and amplitude-adjusted to optimize pressure changes, ensuring synchronized and efficient ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple pressure chambers are used to eject liquid from one nozzle, then ejection efficiency can be improved, but pressure wave attenuation increases and control becomes difficult
Solution Approach 1:
The patent applies local quality by creating different flow path lengths from different pressure chambers to the nozzle. Specifically, the first pressure chamber has a shorter flow path while the second pressure chamber has a longer flow path. This allows each pressure chamber to be optimized for its specific distance to the nozzle, with driving elements applying appropriately timed and sized pressure changes to compensate for path length differences, thereby reducing overall pressure wave attenuation while maintaining high ejection efficiency
Solution Approach 2:
The patent implements preliminary action by timing the driving elements such that the second driving element (connected to the longer flow path) is driven earlier than the first driving element (connected to the shorter flow path). This preliminary action compensates for the longer travel time of pressure waves through the extended flow path, ensuring that pressure waves from all chambers arrive at the nozzle simultaneously and constructively, maximizing ejection efficiency while minimizing energy loss
2Productivity
If multiple pressure chambers are used to eject liquid from one nozzle, then ejection efficiency can be improved, but drive control complexity increases
Solution Approach 1:
The patent manages drive control complexity by implementing local quality through differentiated flow path design. Each pressure chamber is assigned a specific flow path length tailored to its position, with the first pressure chamber having a shorter path and the second having a longer path. This localized optimization allows the control system to manage each chamber independently based on its specific characteristics, making the overall control strategy more systematic and less complex than attempting to uniformly control all chambers
Solution Approach 2:
The patent reduces drive control complexity through preliminary action by pre-calculating and implementing specific timing offsets for each driving element. The control system is designed to drive the second driving element earlier than the first driving element based on the known flow path length differences. This predetermined timing strategy simplifies the control logic compared to real-time adaptive control, as the timing relationships are established in advance based on the fixed geometric configuration of the flow paths
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 reduces pressure wave attenuation, enhances ejection efficiency, and improves the ability to handle high-viscosity inks by aligning pressure wave timings and amplitudes, resulting in improved liquid ejection performance.
Implementation Method 1
a first driving element that changes the pressure in the first pressure chamber, and a second driving element that changes the pressure in the second pressure chamber
Data Source
AI summary
A liquid ejecting head includes a nozzle, first and second pressure chambers communicating with the nozzle, a first driving element configured to change a pressure in the first pressure chamber, and a second driving element configured to change a pressure in the second pressure chamber. A first flow path length of a flow path from the first pressure chamber to the nozzle is shorter than a second flow path length of a flow path from the second pressure chamber to the nozzle. In a driving method of a liquid ejecting head, at least the first and second driving elements are driven to eject a liquid from the nozzle, and a driving timing of the second driving element is earlier than a driving timing of the first driving element.