Liquid Ejection Device Pump Sequencing for Head Air-Bubble Reduction
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Solution Overview
Problem
Air bubbles are likely to be generated in a liquid ejecting apparatus when a liquid with high surface tension is introduced, leading to their adhesion to the inner surfaces of the head, which can hinder proper ejection.
Innovation Solution
A method involving a first initial introduction process where a positive pressure pump is operated while the negative pressure pump is stopped, followed by both pumps being activated, and a wiper is used to form a meniscus, reducing gas entry and air bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both positive pressure pump and negative pressure pump are driven to circulate the inspection liquid, then the liquid circulation is effective, but air bubbles are generated and adhere to the head channel
Solution Approach 1:
The liquid circulation process is segmented into two distinct phases: a first phase where only the positive pressure pump operates to fill the head channel and discharge air bubbles, and a second phase where both pumps operate for normal circulation. This segmentation prevents air bubble generation during the circulation phase while ensuring effective liquid filling.
Solution Approach 2:
The positive pressure pump operates in advance to fill the head channel with inspection liquid and discharge air bubbles before the negative pressure pump is activated. This preliminary action ensures that air bubbles are removed before the circulation phase begins, preventing harmful air bubble adhesion during normal operation.
2Ease of operation
If the negative pressure pump is activated during initial liquid introduction, then liquid return is facilitated, but gas enters through nozzles and forms air bubbles in the head channel
Solution Approach 1:
The system performs preliminary action by activating the positive pressure pump first to fill the head channel and discharge air bubbles through the liquid return channel before activating the negative pressure pump. This ensures the head channel is free of air bubbles before the negative pressure pump operates, preventing gas entry through nozzles.
Solution Approach 2:
The positive pressure pump creates a preliminary counter-action to the negative pressure pump by filling the head channel with liquid and establishing positive pressure to prevent gas entry. This preliminary anti-action counteracts the potential harmful effect of gas entry that would occur if the negative pressure pump were activated first.
3Measurement precision
If inspection liquid with high surface tension is used, then inspection effectiveness is improved, but air bubbles are more likely to be generated and adhere to head surfaces
Solution Approach 1:
The operation is segmented into a filling phase with only the positive pressure pump active to handle high surface tension liquid and discharge air bubbles, followed by a circulation phase with both pumps active. This segmentation allows the high surface tension inspection liquid to be effectively introduced while preventing air bubble adhesion during circulation.
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 effectively prevents air bubbles from adhering to the head channels, ensuring smooth liquid flow and ejection.
Implementation Method 1
a positive pressure pump configured to apply positive pressure to supply the liquid from the tank to the head through the liquid supply channel
Implementation Method 2
a negative pressure pump configured to apply negative pressure to discharge the liquid from the head to the tank through the liquid return channel
Implementation Method 3
a third step of moving the wiper relative to the nozzle surface after the first step and before the second step
Data Source
Figure 1
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AI summary
Means by which a bubble is less likely to remain in a head in a case where a liquid having high surface tension is introduced from a tank to the head will be provided. An image recording apparatus 100 includes an ink sub-tank 47, a head module 49, a liquid supply channel 61, a liquid return channel 62, a positive pressure pump 63, a negative pressure pump 65, and a controller 130. The controller 130 is configured to execute an initial introduction process depending on acceptance of a first command indicating an initial introduction. The initial introduction process includes: a step S12 of driving the positive pressure pump 63 in a state that the negative pressure pump 65 is stopped; and a step S13 of driving the positive pressure pump 63 and the negative pressure pump 65 after the step S12.