Inkjet Head Pressure Response Valve for Negative Pressure Control
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Solution Overview
Problem
Existing inkjet apparatuses face challenges in maintaining a stable slightly negative pressure in the inkjet head, leading to deviations in ink droplet discharge direction and quality issues, due to limitations in the installation location of pressure adjustment units and instability in pressure control using decompression pumps.
Innovation Solution
An inkjet head unit with an operation mechanism featuring a pressure response valve that adjusts the flow of ink based on pressure differences, allowing for flexible installation location and maintaining a predetermined slightly negative pressure without stopping the ink flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water head difference type pressure adjustment unit is used to maintain negative pressure in the inkjet head, then the pressure can be stabilized, but the installation location is limited to positions lower than the inkjet head in the gravitational direction
Solution Approach 1:
The patent replaces the water head difference type pressure adjustment unit (which relies on gravitational potential energy) with a decompression pump system. This substitution eliminates the dependency on gravitational direction for pressure adjustment, allowing the pressure adjustment unit to be installed in various locations including above the inkjet head, thereby resolving the contradiction between pressure stability and installation location flexibility
Solution Approach 2:
The patent introduces a decompression pump as an intermediary device between the inkjet head and the ink tank. This intermediary actively regulates pressure through mechanical pumping action rather than passive water head difference, enabling flexible installation positioning while maintaining stable negative pressure conditions in the inkjet head
2Adaptability or versatility
If the pressure adjustment unit is installed at a position higher than the inkjet head, then installation flexibility is improved, but the inkjet head cannot be maintained in a predetermined slightly negative pressure state
Solution Approach 1:
The patent replaces the passive water head difference mechanism with an active decompression pump system that can generate and maintain negative pressure regardless of installation position. The decompression pump actively removes air or vapor from the ink supply system, maintaining stable negative pressure even when installed above the inkjet head, thus resolving the contradiction between installation flexibility and pressure control stability
3Reliability
If decompression pump output is increased to maintain negative pressure, then pressure control is improved, but the meniscus is pulled too much causing unstable ink droplet discharge
Solution Approach 1:
The patent implements a feedback control mechanism where the decompression pump operation is regulated based on the actual pressure conditions in the inkjet head. The pump operates to maintain a predetermined slightly negative pressure state, preventing excessive meniscus deformation while ensuring stable ink droplet discharge. This feedback control resolves the contradiction between pressure control reliability and ink droplet discharge stability
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 enables stable ink discharge by maintaining the inkjet head at a predetermined slightly negative pressure, improving image quality by ensuring consistent ink droplet direction and flow, while allowing for flexible installation of the pressure adjustment unit.
Implementation Method 1
a pressure response valve that adjusts the flow of ink based on pressure differences
Implementation Method 2
the negative pressure source configured to apply negative pressure to the inkjet head to supply the ink from the ink retaining unit to the inkjet head
Data Source
AI summary
There is provided an inkjet apparatus capable of adjusting pressure in an inkjet head to a predetermined slightly negative pressure without limitations on the installation location of a pressure adjustment unit and without stopping the flow of liquid. The inkjet apparatus includes an inkjet head for discharging ink droplets and an ink tank for retaining liquid to the inkjet head. The inkjet apparatus further includes a liquid feeding unit communicating with the inkjet head and configured to feed the liquid in the ink tank to the inkjet head by reducing the pressure in the inkjet head, an open-close valve configured to open or close a flow channel connecting the inkjet head and the liquid feeding unit, and a pressure adjustment unit configured to open or close the open-close valve according to a pressure difference between inside and outside of the flow channel to adjust the pressure in the inkjet head.