| 摘要 |
1,172,883. Proximity detectors. H. NIELSON & SON, MASKINFABRIK A/S. April 14, 1967 [April 15, 1966], No.17371/67. Heading G1N. An air cored differential transformer connected in a bridge circuit is used to detect the passage of metal articles on a conveyer to e.g. change the direction of travel of the article. The transformer coils are mounted coaxially in a potted unit with external guard plates to protect them from mechanical damage, and disposed so that one primary and secondary pair are nearer to the conveyer than the other pair Figs. 3, 4 (not shown). The output of the bridge may be fed to a pair of phase-sensitive amplifiers arranged to give equal and opposite D.C. output signals when the input is 90 degrees out of phase with the differential transformer supply voltage (i.e. when the bridge is balanced) and thus respond to phase change on unbalance, Fig.6 (not shown). |
