Method for detecting pin holes and the like in sheet material for packaging and similar applications
AssigneeBeltronics, Inc.
InventorsRobert Bishop, Krikor Bezjian
Life of this patent
Estimating the term…
Abstract
This disclosure is concerned with the optical detection of pin holes or similar aberrations in sheet material, such as metal or metalized packaging materials that are to enclose and seal contents therewithin, with the aid of a reflective-wall cavity structure over which the sheet material is placed and light-sealed and the walls of which are shaped to enable external light leaking through the pin hole or the like to become multiply reflected from the cavity walls and the underside of the sheet to impinge upon photodetecting means at an appropriate portion of the walls, thus to enable detection of such leak, and, if desired, location of the pin hole or the like.
Claims5
A method of pin-hole detection in a sheet to be used as part of a sealed enclosure, that comprises, placing the sheet over an open-mouth light-reflecting or light-scattering walled cavity;
- light-sealing the periphery of the sheet over the cavity mouth;
- brightly illuminating the outer surface of the sheet to cause light to leak through any pin hole therein into the cavity;
- shaping the light-reflecting cavity walls to insure multiple and randomly distributed light reflections including from the inner surface of the sheet within the cavity as light enters the pinhole;
- and detecting a signal from such multiply reflected light at a predetermined region within the cavity which statistically will receive at least part of such multiply reflected light to register the presence of the pin hole.
Dependencies are inferred from the claim text.