| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a writing utensil which suppresses a reduction amount of ink and has a valve function capable of performing an air exchange appropriately in accordance with a pressure change in an ink tank. <P>SOLUTION: In the writing utensil, a liquid film which allows the interior and exterior of an ink tank to be communicated with each other so as to exchange air in accordance with the reduced pressure state in the ink tank and the increased pressure state in an ink tank due to a rise of environmental temperature when the ink is ejected from the pen tip connected with the ink in the ink tank is disposed on a continuous hole through which the interior and exterior of the ink tank are communicated with each other, wherein, when the surface tension of the liquid is T (mN/m) and the cross section area of the communication hole is S (mm<SP>2</SP>), a capillary diameter D (mm) of the continuous hole falls into the numerical value range of 0.0003T≤D≤0.015T and a distance length h (mm) of the continuous hole falls into the numerical value range of 0.00032/S≤h≤6/S. <P>COPYRIGHT: (C)2011,JPO&INPIT |
