| 摘要 |
<p>The equipment is for automatically detecting knots, rot, and other faults in sawn wood which passes under an array of inspection heads. The operation of the equipment depends on the light reflecting properties of sawn wood, which is composed mainly of tracheid cells lying along the grain of the wood. A light beam is reflected considerably more efficiently across the grain than along it. The basic detector consists of a light source (2) which directs a beam of light on to the surface of the wood (1) so that a photo detector (4) is illuminated by the reflected beam. A wall (3) prevents direct illumination and a threshold detection circuit (5) fed by the photodiode is used to detect when the reflected light, and so the grain direction, has changed. An array of such elements is mounted across the wood surface to be inspected, and the surface is then passed beneath it.</p> |
