CA2045606A1 - Inspection device on the basis of dark field illumination - Google Patents
Inspection device on the basis of dark field illuminationInfo
- Publication number
- CA2045606A1 CA2045606A1 CA002045606A CA2045606A CA2045606A1 CA 2045606 A1 CA2045606 A1 CA 2045606A1 CA 002045606 A CA002045606 A CA 002045606A CA 2045606 A CA2045606 A CA 2045606A CA 2045606 A1 CA2045606 A1 CA 2045606A1
- Authority
- CA
- Canada
- Prior art keywords
- video camera
- illuminating means
- dark field
- field illumination
- illuminating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
-
- 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
- G01N21/8806—Specially adapted optical and illumination features
-
- 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
-
- 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
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/958—Inspecting transparent materials or objects, e.g. windscreens
-
- 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
- G01N21/8806—Specially adapted optical and illumination features
- G01N2021/8822—Dark field detection
- G01N2021/8825—Separate detection of dark field and bright field
Landscapes
- 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)
Abstract
1 Dunkelfeldbeirchtung PCT
HEUFT-QUALIPLUS B.V.
INSPECTION DEVICE ON THE BASIS OF DARK FIELD ILLUMINATION
A b s t r a c t A Device for inspecting with dark field illumination objects with at least one transparent portion, for instance glass bottles (3) is disclosed. The device comprises illuminating means (1); positioning means for placing the object such that that object can be illuminated by the illuminating means; a video camera (6) for sensing that object and generating video signals, which illuminating means (1) and which video camera (6) are disposed relative to the positioning means such that the video camera (6) senses no image in the case of a homogeneous transparent portion of an object without unhomogeneous parts, enclosures, bubbles, dirt or other deviations, and imaging means such as at least one positive lens (2) and/or at least one positive mirror (7) which are placed between the illuminating means (1) and the positioning means and which image the illuminating means (1) in the vicinity of the objective (5) of the video camera.
Fig. 1
HEUFT-QUALIPLUS B.V.
INSPECTION DEVICE ON THE BASIS OF DARK FIELD ILLUMINATION
A b s t r a c t A Device for inspecting with dark field illumination objects with at least one transparent portion, for instance glass bottles (3) is disclosed. The device comprises illuminating means (1); positioning means for placing the object such that that object can be illuminated by the illuminating means; a video camera (6) for sensing that object and generating video signals, which illuminating means (1) and which video camera (6) are disposed relative to the positioning means such that the video camera (6) senses no image in the case of a homogeneous transparent portion of an object without unhomogeneous parts, enclosures, bubbles, dirt or other deviations, and imaging means such as at least one positive lens (2) and/or at least one positive mirror (7) which are placed between the illuminating means (1) and the positioning means and which image the illuminating means (1) in the vicinity of the objective (5) of the video camera.
Fig. 1
Description
PCT/EP90/0200~ Dunkelfeldbelichtung HEUFT-QUALIPLUS B.V. PCT
INSPECTION DEVICE ON THE BASIS OF DARK FIELD ILLUMINATION
. . _ The invention relates to a device for inspecting with dark field illumination objects with at least one transparent portion, for instance glass bottles, which device comprises: -1) illuminating means;
INSPECTION DEVICE ON THE BASIS OF DARK FIELD ILLUMINATION
. . _ The invention relates to a device for inspecting with dark field illumination objects with at least one transparent portion, for instance glass bottles, which device comprises: -1) illuminating means;
2) positioning means for placing an object such that that object can be illuminated by the illuminating means; and 3) a video camera for sensing that object and genè-rating video signals, which illuminating means and which video camera are disposed relative to the positioning means such that the video camera senses no image in the case of a homogeneous transparent portion of an object without unhomogeneous parts, enclosures, bubbles, dirt or other deviations.
Such a device is known. The drawback of the known dark field illumination is that the illumination of an object is not homogeneous, whereby the detection sensitivity and there-with the detection reliability varies from place to place.
A further drawback of the known illuminating method is that at different posiLions of an inspected object the light has to be deflected through different angles to reach the camera and result in the forming of corresponding video sig-nals.
In practice, only a very limited region can be inspected with sufficient reliability using the known dark field illumi-nation. This is the reason why it has not been possible up to the present time to use a dark field illumination for instance for bottles, particularly larger bottles to roughly 300 mm in `
. ~ ,.
2~
h(~i(Jht sllch as wine bottla~-;, sof t dri.nk bottlc.s and the like.
'I'he inv(:nltion has for i.t.s obje(,t to ~rovi.de a device wharewit:h practi.(al homoyeneous illumi.nation can he obtained in a large re(~:i.c)n, whil.e the di.fferences in deflection of the lic3ht rec7uired -to reach the camera remain very li.mited.
'I'he i.nvention provide.; or this purpose a device of the ~;ta-ted typa characteri~.ed by ~ ) imaging mean, such as at least one positive lens an(~/or at lea~t one positive mirror which are placed between :10 the i.:l.1umi.nati.ng means and thc positioning means and which image the ill.uml.nating means in the vicini.ty of the objective of: thc~ video cclmera.
lt i.5 noted that hy ":i.lluminating means" must be general-.Ly un(l~rstood ~;ources of electromagnetic radiation. This l.'j there~ore ,i.ncludes for instance ultraviolet radiation and infrarl?d radi.at:i.on which cannot strictly speaking be con-si.d~red as "li.ght".
'I'here. are deviations in transparent holders such as ~ ;F7Urc35, crac:ks and the .like which emit directional l,ight due to thcir ref:1ectin~ properties. In this respect it can be advantageous to make use not o~ one for instance more or less point~shaped light source but of for instance two light sour-caF7 wh;.ch are separated spatially such that the mentioned aults can be detected. Cy:l.indrical objects ~uch as glass 2~ bottl.cs, jam jars and the J.ike have for instance the general propertjes of a cylindr.ica:l., positi.ve lens. Use can be made Por .7uch obJects of an arrangemellt with two light sources pl.aced vert:ica.L:I.y one above the other.
'.I:`he stat(3d princi.p:l.e o.t` more than one light source can :.10 ba ~nara~ ecl. An excellent homogene.ity and a great detection re,l..klbi.Lity is ensured wi.th an embodiment whereill the i,llumi-nat:il)g mealls compri.se an ill.uminated part surrounding an unillum.illata(l part. [lse can for example be made of an annular t ~.ou:rce. wh.i.(ll surroullds an uni:l:l.uminated part. It can en<3,rt:l1l.y ba3 stated irl t:h,is respect that the uniL:Luminated 2 ~
part is decisive for the detection sensitivity. The more the distance to the camera transversely of the optical axis of the camera increases, the smaller the detection sensitivity becomes. The more the said distance decreases, the greater the detection sensitivity becomes. Certainly in the case of successive inspection of mass produced objects transported by a conveyor belt it has to be ensured however that the optical stability of the system is not endangered for the ~ake of a great detection sensitivity.
If desired the unilluminated part could serve as secon-dary light source that emits light of another type. This can for instance be light of another colour or with a different polarization direction. By means of this secondary light source each object can thus also be inspected with through-passing light as well as with dark field illumination.
In the case of objects which do not automatically allow of inspection because due to their shape they systematically result in an image in the video camera, also in the case they wholly satisfy the set norm, the device according to the invention can be embodied such that the shape of the illumina-ted part is adapted to the form of an object for inspection.
If desired it is also possible to work in per se known manner with so-called electronic masks which are included for in-stance in software in a signal processing unit which further processes the video signals coming from the video camera.
Attention is also generally drawn in this regard to the fact that in per se known manner the video signals can be used to control ejection means in the case of an object not satisfying the norm.
A very light and inexpensive device is embodied with a Fresnel lens. Such a lens can be manufactured to large dimen-sions for instance by injection moulding of transparent plas-tic.
With respect to the detection sensitivity it is further noted that the further the distance of a holder for inspection 2 ~
-from the video camera, the greater -the detection sensitivity becomes. That is, the more the said distance increases, the smaller the deflection of light necessary to result in a detected fault.
The invention will now be elucidated with reference to the annexed drawing, wherein:
Fig. 1 shows a first embodiment of the device according to the invention;
Fig. 2 shows a similar device with a mirror; and Fig. 3 shows another embodiment.
` Fig. 1 shows schematically a light source 1 which illumi-nates a glass bottle 3 via a positive Fresnel lens 2. The light source 1 is imaged at a position designated 4. This position is located adjacent to the objective lens 5 of a video camera 6. If no object 3 is present, no light reaches the video camera 6. Nor does any light reach the video camera 6 in the case of an object 3 satisfying the norm. Only in the case of a deviation such as unhomogeneous parts, enclosures, bubbles, dirt, glass splinters and the like does a reflection or deflection of the light take place such that the video camera 6 senses light. The video signal is transmitted to signal processing means (not drawn) for further use.
Fig. 2 shows a disposition corresponding with fig. 1, with the difference however that instead of the Fresnel lens 2 use is made of a concave, i.e. positive, mirror 7. Reference is otherwise made to the discussion of fig. 1.
Fig. 3 shows a disposition which in contrast with fig. 1 is augmented with a second light source 8 which is imaged at a position 9. It can be seen from the figure that this light source 8 is also imaged adjacently of the objective lens 5 of video camera 6. The table below gives a comparison between a typical side wall inspection device for glass bottles and the device according to the invention.
!
Table Bottle Deviation Known Device accord-number side wall ing to the inspector invention _ -- --Detection Detection percentage percentage 1 stone 100 lO0 2 stone 100 0 3 air bubble 0 100 4 air bubble o 75 irregular glass 0 o 6 air bubble 0 100 7 irregular glass 75 lO0 15 8 air bubble 0 lO0 9 stone 90 lO0 stone 100 lO0 11 irregular glass 0 100 12 irregular glass 0 100 20 13 irregular glass 0 50 14 irregular glass 0 100 It can be seen from this table that only the stones can be detected with sufficient reliability by the known inspec-tion device. The device according to the invention disposed in this case as side wall inspector gives clearly better results.
Such a device is known. The drawback of the known dark field illumination is that the illumination of an object is not homogeneous, whereby the detection sensitivity and there-with the detection reliability varies from place to place.
A further drawback of the known illuminating method is that at different posiLions of an inspected object the light has to be deflected through different angles to reach the camera and result in the forming of corresponding video sig-nals.
In practice, only a very limited region can be inspected with sufficient reliability using the known dark field illumi-nation. This is the reason why it has not been possible up to the present time to use a dark field illumination for instance for bottles, particularly larger bottles to roughly 300 mm in `
. ~ ,.
2~
h(~i(Jht sllch as wine bottla~-;, sof t dri.nk bottlc.s and the like.
'I'he inv(:nltion has for i.t.s obje(,t to ~rovi.de a device wharewit:h practi.(al homoyeneous illumi.nation can he obtained in a large re(~:i.c)n, whil.e the di.fferences in deflection of the lic3ht rec7uired -to reach the camera remain very li.mited.
'I'he i.nvention provide.; or this purpose a device of the ~;ta-ted typa characteri~.ed by ~ ) imaging mean, such as at least one positive lens an(~/or at lea~t one positive mirror which are placed between :10 the i.:l.1umi.nati.ng means and thc positioning means and which image the ill.uml.nating means in the vicini.ty of the objective of: thc~ video cclmera.
lt i.5 noted that hy ":i.lluminating means" must be general-.Ly un(l~rstood ~;ources of electromagnetic radiation. This l.'j there~ore ,i.ncludes for instance ultraviolet radiation and infrarl?d radi.at:i.on which cannot strictly speaking be con-si.d~red as "li.ght".
'I'here. are deviations in transparent holders such as ~ ;F7Urc35, crac:ks and the .like which emit directional l,ight due to thcir ref:1ectin~ properties. In this respect it can be advantageous to make use not o~ one for instance more or less point~shaped light source but of for instance two light sour-caF7 wh;.ch are separated spatially such that the mentioned aults can be detected. Cy:l.indrical objects ~uch as glass 2~ bottl.cs, jam jars and the J.ike have for instance the general propertjes of a cylindr.ica:l., positi.ve lens. Use can be made Por .7uch obJects of an arrangemellt with two light sources pl.aced vert:ica.L:I.y one above the other.
'.I:`he stat(3d princi.p:l.e o.t` more than one light source can :.10 ba ~nara~ ecl. An excellent homogene.ity and a great detection re,l..klbi.Lity is ensured wi.th an embodiment whereill the i,llumi-nat:il)g mealls compri.se an ill.uminated part surrounding an unillum.illata(l part. [lse can for example be made of an annular t ~.ou:rce. wh.i.(ll surroullds an uni:l:l.uminated part. It can en<3,rt:l1l.y ba3 stated irl t:h,is respect that the uniL:Luminated 2 ~
part is decisive for the detection sensitivity. The more the distance to the camera transversely of the optical axis of the camera increases, the smaller the detection sensitivity becomes. The more the said distance decreases, the greater the detection sensitivity becomes. Certainly in the case of successive inspection of mass produced objects transported by a conveyor belt it has to be ensured however that the optical stability of the system is not endangered for the ~ake of a great detection sensitivity.
If desired the unilluminated part could serve as secon-dary light source that emits light of another type. This can for instance be light of another colour or with a different polarization direction. By means of this secondary light source each object can thus also be inspected with through-passing light as well as with dark field illumination.
In the case of objects which do not automatically allow of inspection because due to their shape they systematically result in an image in the video camera, also in the case they wholly satisfy the set norm, the device according to the invention can be embodied such that the shape of the illumina-ted part is adapted to the form of an object for inspection.
If desired it is also possible to work in per se known manner with so-called electronic masks which are included for in-stance in software in a signal processing unit which further processes the video signals coming from the video camera.
Attention is also generally drawn in this regard to the fact that in per se known manner the video signals can be used to control ejection means in the case of an object not satisfying the norm.
A very light and inexpensive device is embodied with a Fresnel lens. Such a lens can be manufactured to large dimen-sions for instance by injection moulding of transparent plas-tic.
With respect to the detection sensitivity it is further noted that the further the distance of a holder for inspection 2 ~
-from the video camera, the greater -the detection sensitivity becomes. That is, the more the said distance increases, the smaller the deflection of light necessary to result in a detected fault.
The invention will now be elucidated with reference to the annexed drawing, wherein:
Fig. 1 shows a first embodiment of the device according to the invention;
Fig. 2 shows a similar device with a mirror; and Fig. 3 shows another embodiment.
` Fig. 1 shows schematically a light source 1 which illumi-nates a glass bottle 3 via a positive Fresnel lens 2. The light source 1 is imaged at a position designated 4. This position is located adjacent to the objective lens 5 of a video camera 6. If no object 3 is present, no light reaches the video camera 6. Nor does any light reach the video camera 6 in the case of an object 3 satisfying the norm. Only in the case of a deviation such as unhomogeneous parts, enclosures, bubbles, dirt, glass splinters and the like does a reflection or deflection of the light take place such that the video camera 6 senses light. The video signal is transmitted to signal processing means (not drawn) for further use.
Fig. 2 shows a disposition corresponding with fig. 1, with the difference however that instead of the Fresnel lens 2 use is made of a concave, i.e. positive, mirror 7. Reference is otherwise made to the discussion of fig. 1.
Fig. 3 shows a disposition which in contrast with fig. 1 is augmented with a second light source 8 which is imaged at a position 9. It can be seen from the figure that this light source 8 is also imaged adjacently of the objective lens 5 of video camera 6. The table below gives a comparison between a typical side wall inspection device for glass bottles and the device according to the invention.
!
Table Bottle Deviation Known Device accord-number side wall ing to the inspector invention _ -- --Detection Detection percentage percentage 1 stone 100 lO0 2 stone 100 0 3 air bubble 0 100 4 air bubble o 75 irregular glass 0 o 6 air bubble 0 100 7 irregular glass 75 lO0 15 8 air bubble 0 lO0 9 stone 90 lO0 stone 100 lO0 11 irregular glass 0 100 12 irregular glass 0 100 20 13 irregular glass 0 50 14 irregular glass 0 100 It can be seen from this table that only the stones can be detected with sufficient reliability by the known inspec-tion device. The device according to the invention disposed in this case as side wall inspector gives clearly better results.
Claims (5)
1. Device for inspecting with dark field illumination objects with at least one transparent portion, for instance glass bottles, which device comprises:
1) illuminating means;
2) positioning means for placing an object such that that object can be illuminated by the illuminating means; and 3) a video camera for sensing that object and gene-rating video signals, which illuminating means and which video camera are disposed relative to the positioning means such that the video camera senses no image in the case of a homogeneous transparent portion of an object without unhomogeneous parts, enclosures, bubbles, dirt or other deviations, characterized by 4) imaging means such as at least one positive lens and/or at least one positive mirror which are placed between the illuminating means and the positioning means and which image the illuminating means in the vicinity of the objective of the video camera.
1) illuminating means;
2) positioning means for placing an object such that that object can be illuminated by the illuminating means; and 3) a video camera for sensing that object and gene-rating video signals, which illuminating means and which video camera are disposed relative to the positioning means such that the video camera senses no image in the case of a homogeneous transparent portion of an object without unhomogeneous parts, enclosures, bubbles, dirt or other deviations, characterized by 4) imaging means such as at least one positive lens and/or at least one positive mirror which are placed between the illuminating means and the positioning means and which image the illuminating means in the vicinity of the objective of the video camera.
2. Device as claimed in claim 1, characterized in that the illuminating means comprise at least two light sources.
3. Device as claimed in claim 1, characterized in that the illuminating means comprise an illuminated part surround-ing an unilluminated part.
4. Device as claimed in claim 3, characterized in that the shape of the illuminated part is adapted to the shape of an object for inspection.
5. Device as claimed in claim 1, characterized in that the imaging means comprise a Fresnel lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002045606A CA2045606A1 (en) | 1990-12-14 | 1990-12-14 | Inspection device on the basis of dark field illumination |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002045606A CA2045606A1 (en) | 1990-12-14 | 1990-12-14 | Inspection device on the basis of dark field illumination |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2045606A1 true CA2045606A1 (en) | 1992-06-15 |
Family
ID=4147912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002045606A Abandoned CA2045606A1 (en) | 1990-12-14 | 1990-12-14 | Inspection device on the basis of dark field illumination |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2045606A1 (en) |
-
1990
- 1990-12-14 CA CA002045606A patent/CA2045606A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |