| 摘要 |
<p>JPD/lm 23278 3/7/80 A-1 MOISTURE DETECTOR A moisture detector for plywood veneer receives veneer sheets from a dryer on a conveyor and suitably includes adjacently spaced transmitting and receiving plates. A transmitting plate extends the full width of the conveyor, and is supplied from a transformer winding with a high A.C. voltage which is thereby capacitively coupled to the veneer. Receiving plates are shielded and segmented, and are connected to separate detector circuits for operating veneer-marking sprayers when a receiving plate receives an A.C. signal of predetermined value indicative of moisture in the wood. Each detector circuit and receiving plate shield are returned to a first potential reference below conveyor ground level in common with the transformer winding return. Conveyor ground is connected to a tapped voltage divider disposed across the transformer winding whereby a conductive path is provided to the veneer, for example when the veneer becomes substantially shorted to the conveyor by moisture. The last mentioned conductive path can alternatively be employed for moisture detection even in the absence of a transmitting plate.</p> |
