Measuring dia of tree trunks etc. - using IR light curtain and analyser enabling vol. computation

摘要

A device measuring the dia. of round wooden articles, esp. tree trunks, has a light curtain through which the article is passed. The curtain is generated by light sources on one side and detected by receivers on the other side of the curtain. An evaluation circuit determines the dia. from the uninterrupted light paths. It performs very accurate dia. measurement and enables accurate calculation of vol. from several successive measurements of dia. The sources are for infra-red light. The i.r detectors are semiconductor components. Both sources and receivers are arranged in sloping rows with their centres a fixed vertical distance (a) apart. The top most element (22) of one line and the lowest (24) in the line above are the same vertical distance (a) apart.