| 摘要 |
PURPOSE:To reduce the slide resistance of a slide plug and to accurately prescribe said plug by providing a seal part composed of an elastic material to the slide plug in the direction crossing an ink chamber and forming the slide plug in a thin shape so that the slide plug comes into close contact with the ink chamber and bent by the pressure difference between both sides of the slide plug. CONSTITUTION:For example, at the time of the writing due to a white board marker, the ink chamber 2 is pressurized by a pump mechanism 5 to slide a slide plug 10 and the pressure in the ink chamber 2 is set so as to correspond to slide resistance. A seal part 17 is bent by this pressure and the edge part thereof on the side of ink is separated from the inner peripheral surface of the ink chamber 2 but the edge part of the seal part 17 on an air side is not separated from the inner peripheral surface of the ink chamber to hold a close contact state. When the pressure in the ink chamber 2 further rises, the curving of the seal part becomes large and, when the slide resistance becomes smaller than the load received by the slide plug 10 by the pressure in the ink chamber 2, the slide plug 10 begins to slide. Since the seal part 17 is largely curved even when the pressure in the ink chamber 2 changes slightly, the seal part 17 is largely curved even when there is an error in the contact pressure of the outer peripheral surface of the seal part 17 in an initial state, the error is compensated by the large curving of the seal part and the pressure error in the ink chamber 2 is small. |
