| 摘要 |
PROBLEM TO BE SOLVED: To form a sharp display pattern and to completely erase the display pattern by the movement of an erasing magnet by using a specified white fluid and controlling the effective magnetic flux density on the bottom and surface of the panel to a specified range. SOLUTION: Cells 1 are held between the upper face 7 of a magnetic panel and the lower face 8 of the panel. In the cells 1, a white fluid consisting of paraffin 6 and titanium oxide particles 3, silicon oxide particles 4 and alumina particles 5 is sealed as well as magnetic particles 2 present on the lower face 8 of the panel. The proportion of titanium oxide to silicon oxide is 1:1 to 5:2 by weight. The proportion of the white fluid to the magnetic powder is 9:1 to 8:2 by weight. Further, the effective magnetic flux density on the panel bottom 8 when a magnetic pen 9 is brought into contact with the panel surface 7, and the effective magnetic flux density on the panel surface 7 when an erasing magnet 10 is brought into contact with the panel bottom 8 are both controlled to 100 to 300 gauss. |
