Cap Air Hole Design for Inkjet Printhead Bubble Prevention
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Solution Overview
Problem
Image forming apparatuses with vertical recording heads face issues with air bubble formation and residual waste ink accumulation, leading to non-ink-ejecting problems and wiper contamination, due to the obstruction of ink absorbents in the cap's air and suction holes.
Innovation Solution
The design includes a cap with a suction hole and an air hole that are not obstructed by the ink absorbent, ensuring a flow passage between them, and the absorbent's top surface is retracted from contact with the nozzle surface to prevent air bubble entry and residual ink accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ink absorbent is arranged in the cap to absorb discharged ink, then the ink ejection stability is improved, but the air hole and suction hole are obstructed causing air bubble formation and non-ink-ejecting problems
Solution Approach 1:
The cap is divided into distinct functional zones: an upper air hole region, a middle flow passage region, and a lower suction hole region. The ink absorbent is positioned only in the lower region where it absorbs discharged ink without obstructing the air hole or suction hole, which are located in the upper and middle regions respectively. This spatial segmentation allows each component to perform its function independently without interfering with others.
Solution Approach 2:
The ink absorbent is extended in the vertical direction (depth dimension) rather than horizontally blocking the holes. By arranging the absorbent to extend vertically from the nozzle surface downward, it absorbs ink effectively while leaving the air hole and suction hole open in the horizontal plane, eliminating the obstruction problem.
2Reliability
If the ink absorbent is arranged in the cap to absorb discharged ink, then the ink ejection stability is improved, but residual waste ink accumulates in the cap contaminating the wiper
Solution Approach 1:
The cap is segmented into functional zones with the suction hole positioned in the lower region to effectively remove waste ink. The ink absorbent is positioned to absorb discharged ink but not block the suction path. This segmentation ensures that waste ink can be continuously removed through the suction hole while the absorbent maintains its ink absorption function.
Solution Approach 2:
The suction operation is performed continuously or repeatedly to maintain continuous removal of waste ink from the cap. This continuous action prevents residual waste ink from accumulating and contaminating the wiper, while the ink absorbent continuously absorbs discharged ink to maintain stable ejection.
3Reliability
If the cap is designed to cover the nozzle surface completely, then the prevention of ink drying and dust contamination is improved, but air bubble formation occurs during airing operation
Solution Approach 1:
The cap is segmented with distinct openings: an air hole in the upper region for airing operation and a suction hole in the lower region for waste ink removal. This segmentation allows the cap to maintain complete coverage of the nozzle surface for protection while providing dedicated pathways for air exchange and waste removal without causing air bubble formation.
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 prevents air bubble-induced non-ink-ejecting issues and reduces residual waste ink in the cap, maintaining stable ink flow and extending wiper lifespan by ensuring effective suction and cleaning operations.
Implementation Method 1
a suction hole formed on the bottom portion to be connected with a negative pressure generating mechanism to suck the discharged ink
Implementation Method 2
an ink absorbent arranged in the closed space so as to be contacted with the nozzle surface
Data Source
AI summary
An image forming apparatus including a recording head having a nozzle surface on which multiple nozzles to eject droplets are arranged in a line; a suction device; and a cap to cover the nozzle surface of the recording head. The cap includes a suction hole to connect a space formed by the cap and the nozzle surface with the suction device; an air hole to connect the space with air; and an absorbent located inside the cap. The top surface of the absorbent is retracted from the contact portion of the cap to be contacted with the nozzle surface so that when the nozzle surface is capped with the cap, a flow passage is secured between the air hole to the suction hole without obstructed by the absorbent.