Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/90—Investigating the presence of flaws or contamination in a container or its contents

Definitions

• the present invention relates to the technical field of opto-electronic inspection of objects in the general sense such as flat articles or containers such as for example bottles, jars or flasks, of transparent or translucent nature with a view to detecting possible surface defects presented by a transparent or translucent object.
• the object of the invention aims more precisely to detect on a transparent or translucent object surface defects such as for example folds, combs, scrubs or fins under a ring.
• a device comprising a diffuse light source illuminating the object to be inspected.
• One or more cameras are placed in front of the light source in order to recover the light flux transmitted through the object.
• the defects presented by the object attenuate or deflect the transmitted light. These light variations are analyzed to identify and detect faults.
• Such a device is particularly suitable for viewing and detecting internal faults in the wall of the object.
• such a device does not allow visualization and detection of small transparent surface defects.
• the object of the invention is to propose a method for detecting surface defects presented by the external wall of a transparent or translucent object, comprising the following steps:
• the method consists in sending, on the surface of the external wall of the object, an incident light beam with an incident angle suitable for ensuring optimum reflection of the incident light beam.
• the method consists in placing the linear measurement sensor to recover the reflected beam at a reflection angle of value equal to that of the incident angle.
• the method consists, for an object of revolution having an axis of symmetry: - to choose, as linear zone of the external wall of the object, at least a part of a generator parallel to the axis of symmetry,
• Another objective of the invention is to propose a device for detecting surface defects presented by the external wall of a transparent or translucent object.
• the device according to the invention comprises:
• the detection device comprises a light source positioned relative to the object, so that the incident light beam makes an incident angle suitable for ensuring optimum reflection of the incident light beam.
• the linear measurement sensor is positioned, relative to the object, to recover the reflected beam, according to a reflection angle of value equal to that of the incident angle.
• the detection device the light source and the linear measurement sensor are positioned so as, respectively, to send the incident light beam and to recover the reflected light beam, for a zone linear of the external wall of the object, forming at least part of a generator of an object of revolution having an axis of symmetry, the displacement means ensuring the displacement of the object along its axis of symmetry over one revolution complete rotation.
• FIG. 1 is a perspective view illustrating the operating principle of the device according to the invention.
• Fig. 2 is a cross-sectional view showing the direction of the light beams according to the method according to the invention.
• Fig. 3 shows an example of an image obtained using the device according to the invention.
• Fig. 4 is a section showing another example of application of the object of the invention for the detection of faults on a flat wall.
• the subject of the invention relates to a method making it possible, using a device 1, to detect surface defects presented by the external wall 2 of a transparent or translucent object 3.
• the transparent or translucent object 3 is an object of revolution, such as a bottle, a pot or a flask having an axis of symmetry or of revolution X.
• the device 1 comprises a lighting source 4 designed to deliver a wide or diffuse light with a uniform or homogeneous character.
• This light source 4 is adapted to send an incident light beam 5 onto a surface of the external wall 2 of the object 3.
• the device 1 also comprises a linear measurement sensor 8, such as a linear camera capable of recovering the beam reflected 9 by a linear zone Z of the external wall 2, illuminated by the light source 4.
• the light source 4 is positioned with respect to the object 3, so that the incident light beam 5 makes an incident angle suitable for ensuring optimum reflection of the incident beam.
• the camera 8 is positioned so as to recover the light beam reflected by the linear zone Z of the external wall 2 of the object and illuminated by the light source 4.
• the array of photosensitive cells of the camera 8 is, of course, oriented along an axis parallel to the linear zone Z of the outer wall 2 to be inspected.
• the camera 8 is positioned to view a linear zone Z corresponding to at least part of a generator G parallel to the axis of symmetry X of the object of revolution.
• the object 3 is rotated along its axis of symmetry X over a complete revolution of the object 3, so as to allow the complete external surface of the object 3 to be inspected.
• the linear measurement sensor 8 which collects the reflected beam 9 is positioned relative to the normal of the linear zone Z of the external wall 2 of the object, according to a reflection angle ⁇ of value equal to the incident angle ⁇ between the normal to the surface of the linear zone Z and the incident light beam 5.
• the device also comprises means 12 ensuring a relative displacement between, on the one hand, the object 3 and, on the other hand, the source 4 and the linear measurement sensor 8, so as to move the linear measurement zone Z on the external wall 2 of the object.
• the displacement means 12 make it possible to ensure the rotation of the object around its axis of revolution over a complete revolution, in order to scan the entire surface of the external wall 2.
• the device according to the invention also comprises a unit 15 for analyzing and processing the light beams received by the measurement sensor 8.
• This analysis and processing unit 15 is suitable for creating an image and identifying, in the image, the presence of a surface defect corresponding to a dark area. It must be considered that the camera 8 delivers electronic signals representative of the light intensity received by each of the photosensitive cells of the camera 8.
• the analysis and processing unit 15 ensures the conversion of the analog signal into a coded digital signal on a certain number of bits, according to a determined gray scale. From these signals, an image is generated and then filtered, in order to obtain a final image I, such as that illustrated in FIG. 3.
• a surface defect is therefore characterized by the presence, in the image, of a dark zone s.
• the unit 15 analyzes this image, in order to calculate preset characteristics, such as the spatial position, the surface, the perimeter, the center of gravity or the gray level of the dark area s. These measured characteristics are then compared with threshold values to determine whether such a dark area corresponds to a surface defect.
• preset characteristics such as the spatial position, the surface, the perimeter, the center of gravity or the gray level of the dark area s.
• the object of the invention can be applied by sending an incident light beam 5 onto the surface of the wall 2 of the object and by disposing a linear measurement sensor 8 to recover the light beam reflected 9 by a linear zone Z of the external wall 2, illuminated by the light source 4.
• the linear measurement sensor 8 is positioned, relative to the normal to the surface, according to a reflection angle ⁇ equal to the incident angle ⁇ formed by the incident light beam 5.
• the surface of the wall 2 is moved linearly, in order to be able to scan a complete surface of the object 3.
• the object of the invention thus makes it possible to reliably detect surface defects which are difficult to detect, such as small transparent surface defects.
• the relative position between the light source 4 and the sensor 8 is such that it is possible to contrast as much as possible the defect sought with the reflected light 9.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Applications Claiming Priority (3)

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• 2002
  • 2002-10-25 FR FR0213361A patent/FR2846425B1/fr not_active Expired - Fee Related
• 2003
  • 2003-10-24 AU AU2003285456A patent/AU2003285456A1/en not_active Abandoned
  • 2003-10-24 EP EP03778457A patent/EP1558918A1/de not_active Ceased
  • 2003-10-24 WO PCT/FR2003/003165 patent/WO2004040277A1/fr not_active Application Discontinuation
  • 2003-10-24 US US10/532,613 patent/US7230229B2/en not_active Expired - Lifetime
  • 2003-10-24 CN CN200380101795.5A patent/CN1705874A/zh active Pending

Non-Patent Citations (1)

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