Inkjet Head Actuator Ink Circulation Mechanism
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Solution Overview
Problem
Conventional inkjet printers with external control mechanisms for ink circulation become large and costly, especially when supporting high-speed and high-resolution printing, and may face issues with pressure chamber size and flow path resistance.
Innovation Solution
The inkjet head uses its existing actuator to circulate ink by generating a distinct driving signal for ink circulation, differing from the ejection signal, which adjusts flow path resistances through ink feeding holes to facilitate ink circulation without an external control mechanism, allowing for high-speed and high-resolution printing without increasing size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external control mechanism is added for ink circulation, then ink circulation function is improved, but device size and cost increase
Solution Approach 1:
The actuator is designed to perform multiple functions: both ink ejection and ink circulation. By controlling the actuator with different driving signals (ejection signal for droplet ejection, circulation signal for ink circulation), the same hardware component achieves two different functions, eliminating the need for separate circulation control mechanisms and reducing device size and cost
Solution Approach 2:
The ink circulation function is achieved by the actuator itself without requiring external dedicated circulation control mechanisms. The actuator uses its own capability to create pressure changes that drive ink circulation through the feeding holes, making the system self-sufficient for both ejection and circulation needs
2Productivity
If multiple ink feeding holes are used for ink circulation, then ink circulation efficiency is improved, but flow path resistance control becomes complex
Solution Approach 1:
Different ink feeding holes are designed with different flow path resistances tailored to their specific functions. The first ink feeding hole (for ejection) has different resistance characteristics than the second ink feeding hole (for circulation). This local differentiation allows each hole to optimize its specific function while the actuator coordinates their operation through differential driving signals
Solution Approach 2:
The system dynamically controls the actuator with different driving signals depending on the desired function. During ejection, the actuator uses an ejection signal that optimizes flow through the first feeding hole. During circulation, a different circulation signal is applied that optimizes flow through the second feeding hole. This dynamic signal adjustment simplifies the management of multiple feeding holes with different resistances
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 configuration enables efficient ink circulation within the pressure chamber, reducing the need for external control mechanisms, supporting higher-speed and higher-resolution printing while minimizing size and cost, and avoiding potential damage from high pressures.
Implementation Method 1
when voltage is applied to the lower electrode 203 and the upper electrode 205 from the driver circuit 206, the piezoelectric body layer 204 expands/contracts in a direction perpendicular to its thickness direction
Implementation Method 2
The piezoelectric body layer 204 and the diaphragm 201 have different lengths, and this difference in length generates a curvature in the diaphragm 201, and as a result, the diaphragm 201 is displaced (curved) in its thickness direction
Implementation Method 3
This up-and-down movement of the actuator 101 applies pressure to the ink introduced into the pressure chamber 100a, and thereby ink droplets can be ejected through the nozzle hole 102a
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The flow path resistances of ink feeding holes (51, 52) of this pressure-type inkjet head (21) differ from each other. When ink is not being discharged, a driver circuit (46) generates a driving signal for circulating ink, which differs from a driving signal for discharging ink, and applies the driving signal for circulating ink to an actuator (32). The actuator (32) causes the flow rate of ink flowing from the respective ink feeding holes (51, 52) to differ between when ink is being drawn into a pressure chamber (31a) and when ink is being discharged from the pressure chamber (31a) and circulates the ink within the pressure chamber (31a) by being driven on the basis of the driving signal for circulating ink.