Cylindrical object surface inspection system

• US 6,169,600 B1
• Filed: 11/20/1998
• Issued: 01/02/2001
• Est. Priority Date: 11/20/1998
• Status: Expired due to Fees

• Current Assignee: Acuity Brands, Inc.
• Original Assignee: Acuity Brands, Inc.
• Inventors: Ludlow, Jonathan
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US09/197,077
• Time in Patent Office: 774 Days
• Field of Search: 356/237.1, 356/237.2, 356/371, 356/446, 131/905
• US Class Current: 356/237.1
• CPC Class Codes: A24C 5/3412 by means of light, radiation or electrostatic fields A24C5/3406 takes precedence
• CPC Class Codes: G01N 21/952 Inspecting the exterior surface of cylindrical bodies or wires G01N21/956 takes precedence
• CPC Class Codes: Y10S 131/905 Radiation source for sensing condition or characteristic

Abstract

An inspection system and method for optically inspecting substantially the entire circumference of a cylindrical surface, such as a cigarette is provided. The system includes first and second moveable supports for supporting and transporting the cigarette so that a first side of the cylindrical surface of the cigarette is presented to a first visual inspection apparatus and a second side, which includes at least those portions of the cylindrical surface of the cigarette not included in the first side, is presented to a second visual inspection apparatus. Each visual inspection apparatus includes an illumination source for illuminating the presented side of the cigarette'"'"'s surface. Each illumination source is configured to direct light onto the cigarette'"'"'s surface substantially in the direction of the longitudinal axis of the cigarette at a low, acute angle with respect to the longitudinal axis. An image of each presented side of the cigarette is captured using an image capture device, which is preferably a time domain and integration (TDI) camera. The system also includes multiple inspection system processors for processing the captured images.

Claims

1. An inspection system for optically inspecting substantially an entire circumference of a cylindrical surface of a cylindrical object comprising:

a first movable support for supporting and transporting a cylindrical object so that a first side of a cylindrical surface of said cylindrical object is presented to a first visual inspection apparatus;

a first illumination source for illuminating said first side of said cylindrical surface when said first side of said cylindrical surface is presented to said first visual inspection apparatus, said first illumination source configured to direct light onto said cylindrical surface along a longitudinal axis of said cylindrical surface at a low, acute angle with respect to said longitudinal axis of said cylindrical object being inspected;

a second movable support for receiving said cylindrical object from said first movable support and for supporting and transporting said cylindrical object so that a second side of said cylindrical surface is presented to a second visual inspection apparatus, said second side of said cylindrical surface including at least all portions of said cylindrical surface which are not included in said first side;

a second illumination source for illuminating said second side of said cylindrical surface when said second side of said cylindrical surface is presented to said second visual inspection apparatus, said second illumination source configured to direct light onto said cylindrical surface along said longitudinal axis of said object at a low, acute angle with respect to said longitudinal axis of said cylindrical object; and

wherein said first and said second visual inspection apparatus comprise first and second image capture devices for capturing first and second images of said cylindrical object, said first image corresponding to said first side of said cylindrical surface and said second image corresponding to said second side of said cylindrical surface.

2. The inspection system as claimed in claim 1, wherein said first and said second visual inspection apparatus further comprise means to prevent airborne contaminants from settling on the inspection apparatus components.

3. The inspection system as claimed in claim 2, wherein said means to prevent airborne contaminants for setting on said inspection apparatus components comprises a sealed enclosure for housing said components, said enclosure including a window through which images are captured.

4. The inspection system as claimed in claim 3 further comprising an air curtain proximate said window, for providing a low velocity flow of air in the area intermediate said window and said cylindrical object being inspected.

5. The inspection system as claimed in claim 1, wherein at least one of said image capture devices comprises a time domain and integration (TDI) camera.

6. The inspection system as claimed in claim 5 further comprising an image processor, for processing said first and second images to identify visually detectable defects in said first and second sides of said cylindrical surface.

7. The inspection system as claimed in claim 6, wherein said cylindrical object being inspected comprises a cigarette.

8. The inspection system as claimed in claim 1, wherein at least one of said first and second visual inspection apparatuses further comprises an image widener, for allowing at least one of said first and second image capture devices to capture an image of said cylindrical surface that includes greater than one half of said cylindrical surface.

9. The inspection system as claimed in claim 8, wherein said image widener comprises a convex cylindrical lens.

10. The inspection system as claimed in claim 9, wherein said image widener further comprises a concave cylindrical lens in combination with said convex cylindrical lens.

11. The inspection system as claimed in claim 8, wherein said image widener comprises at least one prism.

12. The inspection system as claimed in claim 11, wherein said image widener further comprises at least one mirror in combination with said at least one prism.

13. The inspection system as claimed in claim 8, wherein said image widener comprises a reflective optics lens.

14. The inspection system as claimed in claim 1, wherein at least one of said first and second visual inspection apparatuses further comprises at least one mirror oriented in the field of vision of said image capture device to redirect said image to satisfy space considerations.

15. A method of inspecting substantially an entire circumference of a cylindrical surface of a cylindrical object comprising the steps of:

supporting said object along a longitudinal axis and transporting said object so that a first side of the cylindrical surface is presented to a first visual inspection apparatus;

illuminating said first side of said cylindrical surface with an illumination source configured to direct light upon said first side of the cylindrical surface in a longitudinal direction along an illumination axis which is oriented at a low, acute angle with respect to said longitudinal axis;

capturing a first image of said cylindrical object, said first image corresponding to said first side of said cylindrical surface using a first image capture device, while said first side is illuminated by said first illumination source;

analyzing said first image using an image processor to identify defects in the first side of the cylindrical surface;

transporting said cylindrical object so that a second side of the cylindrical surface of the cylindrical object is presented to a second visual inspection system, said second side of said cylindrical surface including at least all portions of said cylindrical surface which are not included in said first side;

illuminating said second side of said cylindrical surface with an illumination source configured to direct light upon said second side of said cylindrical surface along said illumination axis;

capturing a second image of said cylindrical object with a second image capture device said second image corresponding to said second side of said cylindrical surface while said second side is illumination by said second illumination source; and

analyzing said second image using an image processor to identify defects appearing in the second side of the cylindrical surface.

16. The method as claimed in claim 15, wherein at least one of said steps of analyzing said first and said second images comprises transforming at least one portion of at least one of said images into a gradient image portion and analyzing said gradient image portion using an image processor.

17. The method as claimed in claim 16, wherein at least one of said illuminating steps comprises unevenly illuminating said surface.

18. An inspection system for detecting visually detectable defects in cigarettes, said system comprising:

a first visual inspection apparatus comprising a first TDI camera, for capturing a first image of said cigarette, said first image corresponding to a first side of said cigarette;

a first movable support for supporting at least one cigarette along its longitudinal axis and for transporting said cigarette so that the first side of said cigarette is presented to said first visual inspection apparatus;

a first illumination source oriented to direct light substantially along said longitudinal axis of said at least one cigarette at a first, low, acute angle with respect to said longitudinal axis, for illuminating said first side of said cigarette when said first side is presented to said first visual inspection apparatus;

a second visual inspection apparatus comprising a second TDI camera, for capturing a second image of said cigarette, said second image corresponding to a second side of said cigarette;

a second movable support for supporting at least one cigarette along its longitudinal axis and for transporting said cigarette so that the second side of said cigarette is presented to said second visual inspection apparatus; and

a second illumination source oriented to direct light substantially along said longitudinal axis of said at least one cigarette at a second, low, acute angle with respect to said longitudinal axis, for illuminating said second side of said cigarette when said second side is presented to said second visual inspection apparatus.

19. The inspection system as claimed in claim 18, wherein said first and second low, acute angles are substantially in the range of 10 to 30 degrees.

20. The inspection system as claimed in claim 18 further comprising an image processor for analyzing said first and second captured images to detect defects in said first and second sides of said cylindrical surface.

21. The inspection system as claimed in claim 20, wherein said image processor comprises a gradient filter to transform said first and second captured images into first and second gradient images.

22. The inspection system as claimed in claim 21, wherein said gradient filter comprises a vertical edge filter.