Visual inspection system for leather hide

• US 6,157,730 A
• Filed: 10/28/1999
• Issued: 12/05/2000
• Est. Priority Date: 02/09/1996
• Status: Expired due to Fees

• Current Assignee: Detlef E. Roever, Hartmut Kaebernick, Khoi Hoang, Wei Wen
• Original Assignee: Detlef E. Roever, Hartmut Kaebernick, Khoi Hoang, Wei Wen
• Inventors: Wen, Wei, Hoang, Khoi, Roever, Detlef E., Kaebernick, Hartmut
• Primary Examiner(s): Johns, Andrew W.
• Application Number:
  US09/429,208
• Time in Patent Office: 404 Days
• Field of Search: 382/108, 382/110, 382/111, 348/88, 348/89, 348/128, 348/131, 356/430, 356/431, 356/238.1, 356/237.2, 250/559.04, 250/559.05, 250/559.07, 250/559.45
• US Class Current: 382/110
• CPC Class Codes: C14B 17/005 Inspecting hides or furs
• CPC Class Codes: G01N 21/89 in moving material, e.g. running paper or textiles G01N21/90, G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G01N 21/8903 using a multiple detector array
• CPC Class Codes: G01N 33/447 Leather
• CPC Class Codes: G06T 2207/30124 Fabrics; Textile; Paper
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

A visual inspection system particularly designed for imaging relatively non-rigid materials. In order to identify defects and the position of defects and the position of defects on the material. The arrangement is particularly designed for handling leather hide. Defects in leather hide are presently identified by manual inspection. The present invention provides a visual inspection system for non-rigid materials comprising a mounting means for mounting a sample of the material, tensioning means for tensioning at least an area of the sample, an imaging means (3) for obtaining an image of the area of the sample under tension and processing means for processing the image to provide information on any defects which may exist.

Claims

1. A visual inspection system for non-rigid materials, comprising a mounting means for mounting a sample of the material, tensioning means for tensioning an area of the sample, an imaging means for obtaining an image of the area of the sample under tension, processing means for processing the image to provide information on any defects which may exist, drive and support means for supporting and moving the material sample relative to the imaging means whereby to tension and obtain images of a plurality of areas of the sample, wherein the tensioning means is arranged to apply tension to the area of the sample being imaged at any time in a first direction and in a second, different direction.

2. A visual inspection system in accordance with claim 1, comprising a former over which the material sample is tensioned to enable the imaging means to better perceive any defects in the material.

3. A visual inspection system in accordance with claim 2, the former being substantially elongate in shape and the tensioning means including means for applying tension in a direction substantially at right angles to a longitudinal axis of the former, whereby to tension the material sample over the former.

4. A visual inspection system in accordance with claim 3, wherein the tensioning means further comprises means for tensioning the material in a direction parallel with the longitudinal axis of the former.

5. A visual inspection system in accordance with claim 4, wherein a first surface of the former, over which the material sample is to pass, is formed by a plurality of at least partially convex or flat areas separated by depressions in the surface, and the tensioning means includes means for forcing portions of the material sample into the depressions as the material sample is passed over the former, whereby to tension the material sample over the convex or flat areas in a direction substantially parallel to the longitudinal axis of the former.

6. A visual inspection system in accordance with claim 2 wherein the former and imaging means are mounted for movement relative to each other, and compensation means are provided for automatically adjusting the relative positions of the former and imaging means in response to variations in thickness of the area of the material sample being tensioned, whereby to maintain a substantially fixed distance between the imaging means and the surface of the area of the sample being imaged.

7. A visual inspection system in accordance with claim 1, further comprising a light source for illuminating the area of the sample being imaged, the relative positions of the light source, imaging means and sample being arranged so that the imaging means perceives defect areas on the sample as having a different grey level than undefected areas.

8. A visual inspection system in accordance with claim 7, the light source providing a source of variable light intensity and incorporating focusing means for illuminating a strip of the sample.

9. A visual inspection system in accordance with claim 8, the light source being arranged to illuminate a strip of the sample.

10. A visual inspection system in accordance with claim 1, the drive and support means including a plurality of drive and support belts and wherein the arrangement of the plurality of belts is such that the material sample is supported throughout its movement relative to the imaging means.

11. A visual inspection system in accordance with claim 10, wherein a plurality of imaging windows are provided coincident with gaps in the belts the imaging means being arranged to obtain images of the areas of material sample passing by the imaging windows, whereby to obtain images of plurality of areas of the sample.

12. A visual inspection system in accordance with claim 1, wherein the second different direction is perpendicular to the first direction.

13. A visual inspection system in accordance with claim 1, wherein the imaging means comprises a charged coupled device (CCD) and a focusing means for focusing an image of the area being imaged onto the CCD.

14. A visual inspection system in accordance with claim 13, wherein the focussing means includes a pivotable mirror mounted close to the imaging area, whereby to result in increased focusing control.

15. A visual inspection system for non-rigid materials, comprising a mounting means for mounting a sample of the material, tensioning mean for tensioning at least an area of the sample, an imaging means for obtaining an image of the area of the sample under tension and processing means for processing the image to provide information on any defects which may exist, the processing means being arranged to statistically analyze gray levels of pixels imaged by the imaging device, by applying a normal distribution on either side of a medial gray level which is defined as undefected leather, and determining an extreme or extremes of the normal distribution as defining defected areas of leather.

16. A visual inspection system in accordance with claim 15, the processing means being arranged to produce a contour map showing the extent and location of defects in a material sample.

17. A visual inspection system in accordance with claim 16, the processing means further being arranged to scan the contour map with a template of predetermined area in order to determine the area of material which is useful for the manufacture of product.

18. A visual inspection system in accordance with claim 15, the processing means being arranged to analyze the image by analysing "cells" of the image separately, each cell forming a predetermined portion of the entire image.

19. A visual inspection system in accordance claim 15, the processing means being arranged to apply an edge detection algorithm to determine edges of defects in the material.

20. A visual inspection system in accordance with claim 19, the edge detection process comprising two stages, the first stage including an examination of each pixel in an edge and its surrounding area, and the second stage including an examination of the pixels on an edge and their surrounding area.

21. A visual inspection system for non-rigid materials, comprising a mounting means for mounting a sample of the material, tensioning means for tensioning at least an area of the sample, an imaging means for obtaining an image of the area of the sample under tension, processing means for processing the image to provide information on any defects which may exist, a former being substantially elongate in shape and defining a longitudinal axis, the former having a first surface, over which the material sample is to pass, formed by a plurality of at least partially convex or flat areas separated by depressions in the surface, and the tensioning means includes means for forcing portions of the sample material into the depressions as the material sample is passed over the former, whereby to tension the material sample over the convex or flat areas in a direction substantially parallel to the longitudinal axis of the former.