| 摘要 |
<p>The present invention relates to a writing board with reference lines which are invisible from a distance, and to a process for its fabrication. The board is comprised of at least one support substrate (110) and one writing substrate (120) which are interconnected, wherein the reference lines (130) are so printed that they remain inserted between the support substrate and the writing substrate thereby increasing their durability. The reference lines (130) can be clearly seen by a person which is close to the writing board, while they are invisible for a person standing far from the board.</p> |
