| 摘要 |
<p>A writing board (10) for use with a chalk writing instrument, comprises a sheet element (12) having a major side defining a writing surface (14). The writing surface has a rough profile provided by a plurality of pyramidal - shaped protuberances (16) which are arranged in rows in a grid pattern. The protuberances provide an abrasive surface for rubbing off particles of the chalk writing instrument which are deposited onto the writing surface for marking the sheet element. The spacing between adjacent protuberances is less than the width of a chalk writing instrument thereby to ensure that the writing instrument cannot pass between two adjacent protuberances without contacting the protuberances when using the writing instrument to mark the sheet element.</p> |
