| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a conventional concealable sheet using a colored semitransparent sheet that a record in an uncolored portion other than a portion wherein matters to be memorized are recorded is also hard to be identified because light reflected on the portion of the recorded matters is shaded partially at least since the recorded matters need to be concealed by coloring the sheet. SOLUTION: By forming at least one surface so that a Y value in a 45°diffusion method is set to 4.5-12.6, part of the reflected light of a portion covered with the sheet becomes unable to reach the eye due to the scattering of the light, and thus visual discrimination between the colored portion and the recorded portion located therein can be made difficult. Accordingly, the portion other than the colored portion being the object of learning by memorization can be identified through the sheet. COPYRIGHT: (C)2008,JPO&INPIT
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