| 摘要 |
All tip retractable pens have no caps to cover their pen tips, instead their pen tips or tip protection covers are retractable such as mechanical ball pens, twisted ball pens or telescopic ball pens. Theirs pen tips will be same direction to theirs clips, and always point to ground either in writing or any time unused. Because theirs structure as retractable pen, they don't need caps. To make retractable pen be able to use liquid ink, this invention use spool valves inside the liquid ink cartridge, which also applies on the pen tip is same direction with its pen clip or has no cap to cover its pen tip. Using an air valve, a pen tip valve, a valve rod, and a pushing or twist action to change valves result as unused state: the pen tip valve close ink path and the air valve opens to vent expansion air. And as writing state: the air valve closed to create a vacuum to hold ink in tube and the p en tip valve open the ink to pen tips and air vents through an outlet at top of valve rod to balance pressure.
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