| 摘要 |
<p>PURPOSE:To prevent a lowering in the quantity of light by making the depth dimension of a blackboard main body thin and omitting a mirror by bending the route of a writing medium at a press part to arrange an optical system and an optical reading part between a pair of rollers and allowing an optical reading part to be directly opposed to the surface of the medium. CONSTITUTION:A writing medium 6 is bent by tension rollers 15, 16 to form a wide space part 14, and an optical system 11 consisting of a light source 8 and a reflecting plate 9 and an optical reading part 10 are arranged to said space part 14. The writing medium 6 is rotated and the reflected image from the writing medium 6 illuminated by a light source 8 is directly formed on the CCD image sensor of the optical reading part 10. By this method, the incident light path 19 to the optical reading part 10 is not blocked by the writing medium 6. Further, a mirror for reflecting the image of the writing medium 6 to the optical reading part 10 can be omitted.</p> |
