Print Head Ink Supply with Local Pressure Control
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Solution Overview
Problem
Inkjet printers experience unwanted pressure fluctuations in the supply arrangement, leading to printing errors due to flow resistances and long pipes/hoses, which are difficult to regulate, especially when multiple print heads are connected, causing mutual pressure influences and quality issues in the print image.
Innovation Solution
A closed, air-tight supply container is associated with each print head, connected via a short line, equipped with a pressure sensor and controller to regulate ink flow, maintaining negative pressure and minimizing pressure fluctuations by adjusting the fluid pressure in the supply container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a network of pipes and hoses is used to supply ink to multiple print heads, then ink can be distributed to all print heads, but pressure fluctuations occur due to flow resistances and long pipes leading to printing errors
Solution Approach 1:
The patent divides the ink supply system into individual supply lines for each print head, with each line having its own backpressure tank and pump. This segmentation eliminates the pressure fluctuations caused by long common pipes and flow resistances, as each print head receives ink through a short, dedicated supply line with controlled pressure.
Solution Approach 2:
Each print head is equipped with its own backpressure tank positioned at a specific height to create the required negative pressure locally. This local arrangement ensures that each print head operates with optimal pressure conditions independent of other print heads, preventing mutual pressure influences.
2Ease of operation
If print heads are connected via long pipes and hoses, then ink can reach all print heads, but flow resistances cause pressure fluctuations and printing errors
Solution Approach 1:
The system replaces the single network of long pipes with multiple short, individual supply lines. Each supply line connects the ink storage container directly to a specific print head through a short path, minimizing flow resistances and eliminating the pressure fluctuations that degrade print quality.
3Device complexity
If a single intermediate ink container is used for all print heads, then the supply arrangement is simplified, but mutual pressure influences occur leading to large pressure fluctuations
Solution Approach 1:
The single intermediate ink container is replaced with individual backpressure tanks for each print head. Although this increases the number of components, it eliminates mutual pressure influences by providing independent pressure control for each print head, ensuring stable operation.
Solution Approach 2:
Each backpressure tank acts as an intermediary element between the ink storage container and the print head. The tank creates a localized negative pressure environment that isolates each print head from pressure fluctuations in the main ink supply system.
4Reliability
If a backpressure tank is used to create negative pressure, then ink leakage is prevented, but pressure regulation over the large volume is difficult
Solution Approach 1:
The large-volume backpressure tank is replaced with multiple small-volume backpressure tanks, one for each print head. The reduced volume of each individual tank makes pressure regulation much easier and more responsive, while still maintaining the necessary negative pressure to prevent ink leakage.
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 solution reduces pressure fluctuations at the print head, allows precise pressure monitoring and adjustment for each print head, eliminating the need for a backpressure tank, simplifying the design, and preventing mutual influence between print heads, resulting in improved print quality.
Implementation Method 1
Due to the lower position of the intermediate ink container, a negative pressure (i.e. a pressure that is below the ambient pressure) is statically created
Implementation Method 2
a pump (14), with the aid of which the ink (122) is conveyed from the storage container (12) into the supply line (16)
Implementation Method 3
A sensor (126) is provided that is configured to determine a measurement value for the fluid pressure in the supply container (120)
Data Source
AI summary
A closed supply container that is filled with air and ink is associated with a print head in a one-to-one association. During a printing process, ink is drawn from the supply container into the print head via a connecting line, such that a negative pressure in the supply container is increased. A sensor in the supply container measures the negative pressure and transmits a measurement value to a controller that switches a valve associated with the supply container so that ink is conveyed from an ink storage container into the supply container of the measurement value falls below a predetermined first lower limit value of the pressure such that the fluid pressure in the supply container increases.