GB785223A - Improvements in or relating to apparatus for detecting the presence of foreign bodies on the bottoms of transparent vessels - Google Patents

Abstract

785,223. Photo-electric indicating arrangements. U.D. ENGINEERING CO., Ltd. Nov. 30, 1955 [Dec. 3, 1954], No. 35136/54. Class 40 (3). An apparatus for detecting the presence of a foreign body in the bottom of a transparent vessel such as a milk bottle comprises a cathode-ray tube located so that a scanning light beam therefrom is directed to explore the vessel bottom, a light-responsive device receiving the light transmitted therethrough, and means giving a response when the light received drops below a predetermined value. Support means for the vessel are necessary which avoid significant obstruction to the passage of the light and it is necessary to be able to adjust the area explored in order to examine different sized vessels. In one embodiment bottles 1 fed along a conveyer 2 are transferred across a knife-edged grid support 4 to a second conveyer 5. Below the grid is positioned a cathode-ray tube 7 the beam of the light from the scan of which is directed through the bottle to lightsensitive device 8 controlling an indicator and/or a device deflecting reject bottles. Various scan patterns may be used, notably a spiral pattern obtained by the use of a rotating electromagnetic deflecting field. It is essential that the scan does not extend beyond the inner edges of the bottom of the vessel being examined. In a preferred form the scanning mechanism is operated continuously and the light-sensitive system rendered effective only when a bottle is correctly positioned by switch means co-operating with the movement of the bottles. As the scanning can be effected very rapidly it is possible to move the bottles uninterruptedly through the test position without bringing them to rest if desired. In a modification the bottles may be supported by parallel rails fitting below their neck rings instead of on a grid. The cathode-ray tube may be positioned above or below the vessel as is most convenient and lenses, such as those shown at 12 and 13, may be necessary. Mirrors may be introduced into the light path so as to enable the cathode-ray tube and light-sensitive device to be mounted together above or below the test position (Fig. 5, not shown).