System for detecting small openings in hollow bodies

Abstract

Light source and light sensor on opposite sides of wall of container detect pinhole or crack in container wall, with container rejection means operable by light sensor.

I claim: 
     
       1. Apparatus for testing for any random perforation in the walls of container bodies having brightly reflective interior surfaces, comprising means to make light-tight engagement with the end of the wall at the open end of a container body, means to sense light passed from within the container body to said open end, and light source means to illuminate the outside of the container body walls to be tested, whereby light from said light source means can pass through any random perforation in said walls to be tested, and thence enter the interior of the container to pass directly or by reflection from .Iadd.the brightly reflective interior surfaces .Iaddend.within the container body .Iadd.directly .Iaddend.to the light sensing means, thus indicating whether the container body is perforated. 
     
     
       2. Apparatus .[.according to claim 1,.]. .Iadd.for testing for any random perforation in the walls of container bodies having brightly reflective interior surfaces, comprising means to make light-tight engagement with the end of the wall at the open end of a container body, means to sense light passed from within the container body to said open end, and light source means to illuminate the outside of the container body walls to be tested, whereby light from said light source means can pass through any random perforation in said walls to be tested, and thence enter the interior of the container to pass directly or by reflection from within the container body to the light sensing means, thus indicating whether the container body is perforated, and further .Iaddend.including means to press the container body against said .[.member.]. .Iadd.first means .Iaddend.and thereby tend to open up any edge crack at the open end of the container body, whereby light from the light source means will tend to pass through the edge crack to be detected by the light sensing means. 
     
     
       3. Apparatus according to claim 2, in which said light sensing means has its light sensitive element positioned entirely outside of the interior of the container body and in which an open passage is provided for transmission of light passing from the interior of the container body to the light sensitive element. 
     
     
       4. A method for testing the side walls and bottom of an open ended metal container having brightly reflective interior surfaces, which comprises the steps of interposing a light barrier between the interior and exterior surfaces of the container, pressing a portion of the barrier against the end of the side walls at the open end of the container exposing the exterior surfaces of the container to light rays, and sensing light passing .Iadd.directly or by reflection from the brightly reflective interior surfaces within the container directly .Iaddend.toward the open end of the .[.can.]. .Iadd.container .Iaddend.from its interior, thereby detecting any light passing from outside the container through any random perforation through its walls into the interior of the container.