Process and apparatus for the optical inspection of a transparent region of a container, in particular the mouth region

• US 5,661,294 A
• Filed: 08/30/1996
• Issued: 08/26/1997
• Est. Priority Date: 12/06/1993
• Status: Expired due to Fees

• Current Assignee: Elpatronic AG
• Original Assignee: Elpatronic AG
• Inventors: Buchmann, Christa, Burri, Karl-Georg
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US08/706,300
• Time in Patent Office: 361 Days
• Field of Search: 250/223, 356/240, 356/428, 209/524-526
• US Class Current: 250/223.00B
• CPC Class Codes: G01N 21/9054 Inspection of sealing surface and container finish

Abstract

To photograph the mouth region of a bottle, a light-emitting surface is arranged below the mouth region to be photographed. The light-emitting surface is illuminated by means of an illuminating device and the image of the illuminated mouth region is directed to a camera by a mirror arrangement (5,6,11). The light-emitting surface makes it possible to image the mouth region in transmitted light, facilitating detection of defects and soiling in the mouth region from the interpretation of the image recorded by the camera.

Claims

1. Process for the optical inspection of a transparent mouth region of a bottle, comprising the steps of:

arranging at least one substantially homogeneous light-emitting surface in a substantially surrounding relationship with the container and positioned completely below the mouth region to be inspected for directing light from below the mouth region upwardly towards the mouth region and through the mouth region,

directing light transmitted through and exiting from the mouth region further upwardly to at least one optical element positioned above the mouth region, and

directing the transmitted light from the at least one optical element to a camera so that the mouth region can be photographed using the transmitted light.

2. Process according to claim 1, wherein the optical element includes a mirror arrangement.

3. Process according to claim 1, characterized in that imaging is performed by at least one refracting body, in particular a prism, or by at least one refracting body in combination with at least one mirror.

4. Process according to claim 1, characterized in that the image is produced by means of optical fibres.

5. Process according to claims 1, characterized in that each bottle to be inspected is surrounded, below the region, by a reflecting surface forming the light-emitting surface, the inspection stage is performed by illuminating the reflecting surface and recording the camera picture, and the reflecting surface is removed from the container.

6. Process according to claim 5, characterized in that reflecting surface for each bottle is formed by the joining of at least two parts.

7. Apparatus for optically inspecting a transparent mouth region of a container which produces an image of the region comprising:

an illuminating device for emitting light,

a reflecting surface which is illuminated by and reflects light from the illuminating device and which is arranged around the container and below the region to be inspected to reflect and transmit light upwardly through the mouth region,

a camera, and

optical means positioned completely above the mouth region to be inspected for directing light which is transmitted from the reflecting surface and through the mouth region further upwardly to the camera so that the camera images the mouth region in transmitted light.

8. Apparatus according to claim 7, characterized in that the illuminating device is constituted by an annular array of light-emitting diodes.

9. Apparatus according to claim 7, characterized in that the reflecting surface is constituted by an internal conical surface open towards the illuminating device.

10. Apparatus according to claim 7, characterized in that in addition to the light-emitting surface a mirror surface is provided to reflect light from the container for observation.

11. Apparatus according to claim 7, characterized in that the reflecting surface is curved over at least part of its extent.

12. Apparatus for optical inspection as defined in claim 7 wherein the optical means is a prism/mirror arrangement.

13. Apparatus for optical inspection as defined in claim 7 wherein the optical means is an arrangement of optical fibers.

14. Apparatus according to claim 7, characterized by a conveyor system for conveying upright containers, a device for positioning the light-emitting surface with a container to be inspected and removing it therefrom, and an inspection apparatus comprising at least one camera for photographing the container region illuminated by the light-emitting surface.

15. Apparatus according to claim 14, characterized in that the device for positioning and removing the light-emitting surface comprises two turntables whose rotation is synchronized with the conveyor system, each carrying light-emitting segments which combine to form the light-emitting surface providing said illumination for the inspection apparatus.

16. Apparatus for optical inspection as defined in claim 7 wherein the optical means is a prism arrangement.

17. Apparatus according to one of claim 16, characterized in that the prism made in one piece or composed of several parts is provided.

18. Apparatus for optical inspection as defined in claim 7 wherein the optical means is a mirror arrangement.

19. Apparatus according to claim 18, characterized in that the mirror arrangement comprises at least one parabolic mirror.

20. Apparatus according to claim 18, characterized in that the optical means comprises a conical mirror having an external conical surface pointing towards the camera.

21. Apparatus according to claim 20, characterized in that the conical mirror is surrounded by a cylindrical mirror, and an annular mirror (6) is arranged above the cylindrical mirror.

22. Apparatus according to claim 20, characterized in that a further conical mirror is arranged above the first conical mirror.

23. Apparatus according to claim 18, characterized in that the prism/mirror arrangement comprises a rotationally symmetrical body acting as a prism, which has at least two reflecting faces.

24. Apparatus according to claim 23, characterized in that the prism is provided with at least one curved face.

25. Apparatus according to claim 23, characterized in that a correcting arrangement is provided in front of or behind the prism.

26. Process for the optical inspection of a transparent mouth region of a bottle, comprising the steps of:

emitting light rays from a location completely below the mouth region of a bottle upwardly towards and through the mouth region to be inspected, the bottle having a longitudinal axis which intersects the mouth region;

reflecting the light rays transmitted through the mouth region obliquely toward the longitudinal axis by means of a first mirror, the first mirror being symmetrical with respect to the longitudinal axis and positioned completely above the mouth region;

reflecting light rays reflected by the first mirror by means of a second mirror, the second mirror being symmetrical with respect to the longitudinal axis and positioned above the mouth region to reflect light rays from the first mirror generally along the longitudinal axis; and

photographing the mouth region using the light reflected from the second mirror by means of a camera positioned on the longitudinal axis whereby the ray path, before a final reflection to the camera, extends at an oblique angle to the longitudinal axis of the container.

27. The process of according to claim 26, wherein during the steps of reflecting light, the second mirror comprises a conical mirror with its external conical surface pointing towards the camera, and the first mirror comprises a cylindrical mirror which surrounds the conical mirror and an annular mirror arranged above the cylindrical mirror.

28. The process according to claim 26, characterized in that the mirror arrangement comprises a conical mirror with its external conical surface pointing towards the camera and a mirror in the form of a frustum of a cone with its base located above the apex of the conical mirror.

29. The process according to claim 26, characterized in that the mirror arrangement comprises at least one parabolic mirror or a spherical mirror.