Optical inspection system

• US 5,954,206 A
• Filed: 06/20/1997
• Issued: 09/21/1999
• Est. Priority Date: 07/25/1995
• Status: Expired due to Term

• Current Assignee: Odenberg Engineering Limited
• Original Assignee: Oseney Limited
• Inventors: Moynihan, Maurice, Mallon, John
• Primary Examiner(s): Milef, Boris
• Application Number:
  US08/765,842
• Time in Patent Office: 823 Days
• Field of Search: 209/577, 209/580-582, 209/587, 209/639
• US Class Current: 209/580
• CPC Class Codes: B07C 5/342 according to optical properties, e.g. colour according to radiation transmittivity B07C5/3416
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features

Abstract

An optical inspection system inspect products passed through an inspection region. Light is directed onto the products form optical control units including light emitting diodes. Light emitted from the diodes is directed by cylindrical lenses onto the products at a specified target region, and a sensor detects light reflected from the products. Focussing is achieved by an outer row of the diodes being displaced outwardly relative to axes of respectively cylindrical lenses, so that light originating from the outer rows of diodes converges towards that passing along a central axis extending from a central row of the diodes through a central lens to the target region, light from all rows of the diodes being therefore focussed substantially at the target region.

Claims

1. An optical inspection system for edible natural products comprising:

an inspection region through which said products pass;

at least one means for directing light onto said products during their passage through said inspection region; and

means for detecting light returned from said products;

wherein said at least one light directing means comprises an optical system for focusing light substantially at a specified target region within said inspection region through which target region said products travel during their said passage through said inspection region;

said at least one light directing means and said returned light detecting means are separated from said inspection region by light-transmitting but product-impermeable means wherein there is a spacing between the target region and the light-transmitting but product-impermeable means;

said at least one light directing means comprises a plurality of rows of light emitting sources, each row of said plurality of rows comprising a multiplicity of said light emitting sources;

said optical system comprises a lens system for said focusing of light emanating from said light emitting sources substantially at said target region;

said lens system comprises a plurality of lens system portions, a respective lens system portion corresponding to each of said plurality of rows of light emitting sources; and

each of said plurality of rows of light emitting sources is positioned relative to the respective lens system portion corresponding therewith so that light from each row of said plurality of rows focuses substantially at said target region at said spacing from said light-transmitting but product impermeable means; and

wherein at least one of said lens portions is angularly disposed relative to the respective row of light emitting sources associated with said at least one lens portion so as to focus light onto said target region.

2. An inspection system according to claim 1, wherein said plurality of lens system portions comprises a plurality of cylindrical lens portions defined by portions of a single unitary lens structure.

3. An inspection system according to claim 1, wherein one of said rows of light emitting sources comprises light sources of at least one first wavelength and another of said rows comprises light sources of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, said means for detecting returned light comprises an axial array of sensors located in substantial proximity to said plurality of rows of light emitting sources, and said at least one light directing means is located so that the central optical axis of said at least one light directing means is aligned to focus on said target region.

4. An inspection system according to claim 1, comprising a plurality of said light directing means, wherein each of said plurality of light directing means comprises at least three rows of light emitting sources, a central row comprising light sources for emitting light of at least one first wavelength being flanked by at least two rows comprising light sources for emitting light of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, at least one row comprising light sources of said at least one second wavelength being located to each side of said central row, said means for detecting returned light being located substantially centrally between two of said plurality of said light directing means, and wherein

said means for detecting returned light comprising an elongate axial array of sensors mounted on an optic bar, and said two of said plurality of said light directing means are mounted one to each side of said optic bar so that the central optical axis of each of said two of said plurality of said light directing means is aligned to focus on said target region.

5. A system according to claim 1 wherein said spacing between said target region and said light-transmitting but product-impermeable means is 290 mm.

6. An optical inspection system for edible natural products comprising:

an inspection region through which said products pass;

at least one means for directing light onto said products during their passage through said inspection region; and

means for detecting light returned from said products;

wherein said at least one light directing means comprises an optical system for focusing light substantially at a specified target region within said inspection region through which target region said products travel during their said passage through said inspection region;

said at least one light directing means and said returned light detecting means are separated from said inspection region by light-transmitting but product-impermeable means wherein there is a spacing between the target region and the light-transmitting but product-impermeable means;

said at least one light directing means comprises a plurality of rows of light emitting sources, each row of said plurality of rows comprising a multiplicity of said light emitting sources;

said optical system comprises a lens system for said focusing of light emanating from said light emitting sources substantially at said target region;

said lens system comprises a plurality of lens system portions, a respective lens system portion corresponding to each of said plurality of rows of light emitting sources; and

each of said plurality of rows of light emitting sources is positioned relative to the respective lens system portion corresponding therewith so that light from each row of said plurality of rows focuses substantially at said target region at said spacing from said light-transmitting but product impermeable means; and

wherein said plurality of lens system portions comprises a plurality of individual cylindrical lens portions defining a lens assembly in which the individual cylindrical lens portions are located substantially in edge contact with one another.

7. An inspection system according to claim 6, wherein one of said rows of light emitting sources comprises light sources of at least one first wavelength and another of said rows comprises light sources of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, said means for detecting returned light comprises an axial array of sensors located in substantial proximity to said plurality of rows of light emitting sources, and said at least one light directing means is located so that the central optical axis of said at least one light directing means is aligned to focus on said target region.

8. An inspection system according to claim 6, comprising a plurality of said light directing means, wherein each of said plurality of light directing means comprises at least three rows of light emitting sources, a central row comprising light sources for emitting light of at least one first wavelength being flanked by at least two rows comprising light sources for emitting light of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, at least one row comprising light sources of said at least one second wavelength being located to each side of said central row, said means for detecting returned light being located substantially centrally between two of said plurality of said light directing means, and

wherein said means for detecting returned light comprising an elongate axial array of sensors mounted on an optic bar, and said two of said plurality of said light directing means are mounted one to each side of said optic bar so that the central optical axis of each of said two of said plurality of said light directing means is aligned to focus on said target region.

9. A system according to claim 6, wherein said spacing between said target region and said light-transmitting but product-impermeable means is 290 mm.

10. An optical inspection system for edible natural products comprising:

an inspection region through which said products pass;

at least one means for directing light onto said products during their passage through said inspection region, and

means for detecting light returned from said products;

wherein said at least one light directing means comprises an optical system for focusing light substantially at a specified target region within said inspection region through which target region said products travel during their said passage through said inspection region;

said at least one light directing means and said returned light detecting means are separated from said inspection region by light-transmitting but product-impermeable means wherein there is a spacing between the target region and the light-transmitting but product-impermeable means;

said at least one light directing means comprises a plurality of rows of light emitting sources, each row of said plurality of rows comprising a multiplicity of said light emitting sources,

said optical system comprises a lens system for said focusing of light emanating from said light emitting sources substantially at said target region,

said lens system comprises a plurality of lens system portions, a respective lens system portion corresponding to each of said plurality of rows of light emitting sources;

each of said plurality of rows of light emitting sources is positioned relative to the respective lens system portion corresponding therewith so that light from each row of said plurality of rows focuses substantially at said target region at said spacing from said light-transmitting but product impermeable means; and

wherein at least one of said rows of light emitting sources is laterally displaced relative to an optical axis of the respective lens portion associated with said at least one row.

11. An inspection system according to claim 10, wherein said plurality of lens system portions comprises a plurality of cylindrical lens portions defined by portions of a single unitary lens structure.

12. An inspection system according to claim 10, wherein one of said rows of light emitting sources comprises light sources of at least one first wavelength and another of said rows comprises light sources of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, said means for detecting returned light comprises an axial array of sensors located in substantial proximity to said plurality of rows of light emitting sources, and said at least one light directing means is located so that the central optical axis of said at least one light directing means is aligned to focus on said target region.

13. An inspection system according to claim 10, comprising a plurality of said light directing means, wherein each of said plurality of light directing means comprises at least three rows of light emitting sources, a central row comprising light sources for emitting light of at least one first wavelength being flanked by at least two rows comprising light sources for emitting light of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, at least one row comprising light sources of said at least one second wavelength being located to each side of said central row, said means for detecting returned light being located substantially centrally between two of said plurality of said light directing means, said means for detecting returned light comprising an elongate axial array of sensors mounted on an optic bar, and said two of said plurality of said light directing means being mounted one to each side of said optical so that the central optical axis of each of said two of said plurality of said light directing means is aligned to focus on said target region.

14. A system according to claim 10, wherein said spacing between said target region and said light-transmitting but product-impermeable means is about 290 mm.

15. An optical inspection system for edible natural products comprising:

an inspection region through which said products pass;

at least one means for directing light onto said products during their passage through said inspection region; and

means for detecting light returned from said products;

wherein said at least one light directing means comprises an optical system for focusing light substantially at a specified target region within said inspection region through which target region said products travel during their said passage through said inspection region;

said at least one light directing means and said returned light detecting means are separated from said inspection region by light-transmitting but product-impermeable means wherein there is a spacing between the target region and the light-transmitting but product-impermeable means;

said at least one light directing means comprises a plurality of rows of light emitting sources, each row of said plurality of rows comprising a multiplicity of said light emitting sources;

said optical system comprises a lens system for said focusing of light emanating from said light emitting sources substantially at said target region;

said lens system comprises a plurality of lens system portions, a respective lens system portion corresponding to each of said plurality of rows of light emitting sources; and

each of said plurality of rows of light emitting sources is positioned relative to the respective lens system portion corresponding therewith so that light from each row of said plurality of rows focuses substantially at said target region at said spacing from said light-transmitting but product impermeable means; and

wherein at least one of said lens portions is angularly disposed relative to the respective row of light emitting sources associated with said at least one lens portion so as to focus light onto said target region.

16. An inspection system according to claim 15, wherein one of said rows of light emitting sources comprises light sources of at least one first wavelength and another of said rows comprises light sources of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, said means for detecting re turned light comprises an axial array of sensors located in substantial proximity to said plurality of rows of light emitting sources, and said at least one light directing means is located so that the central optical axis of said at least one light directing means is aligned to focus on said target region.

17. An inspection system according to claim 15, comprising a plurality of said light directing means, wherein each of said plurality of light directing means comprises at least three rows of light emitting sources, a central row comprising light sources for emitting light of at least one first wavelength being flanked by at least two rows comprising light sources for emitting light of at least one second wavelength, said at least one second wavelength being different from said at least one first wavelength, at least one row comprising light sources of said at least one second wavelength being located to each side of said central row, said means for detecting returned light being located substantially centrally between two of said plurality of said light directing means, and

wherein said means for detecting returned light comprising an elongate axial array of sensors mounted on an optic bar, and said two of said plurality of said light directing means are mounted one to each side of said optic bar so that the central optical axis of each of said two of said plurality of said light directing means is aligned to focus on said target region.

18. A system according to claim 15, wherein said spacing between said target region and said light-transmitting but product-impermeable means is 290 mm.

19. An optical inspection system for edible natural products comprising:

(a) an inspection region through which said products pass,

(b) at least one means for directing light onto said products during their passage through said inspection region, and

(c) means for detecting light returned from said products,

wherein

(i) said at least one light directing means comprises an optical system for focussing light substantially at a specified target region within said inspection region through which target region said products travel during their said passage through said inspection region,

(ii) said at least one light directing means and said returned light detecting means are separated from said inspection region by light-transmitting but product-impermeable means,

(iii) said at least one light directing means is disposed so that the spacing between said target region and said light-transmitting but product-impermeable means is sufficient to substantially minimize build-up of unwanted matter on a surface of said light-transmitting but product-impermeable means directed towards said target region,

(iv) said at least one light directing means comprises a plurality of rows of light emitting sources, each row of said plurality of rows comprising a multiplicity of said light emitting sources,

(v) said optical system comprises a lens system for said focussing of light emanating from said light emitting sources substantially at said target region,

(vi) said lens system comprises a plurality of lens system portions, a respective lens system portion corresponding to each of said plurality of rows of light emitting sources,

(vii) at least one row of said plurality of rows of light emitting sources is positioned relative to the respective lens system portion associated with said at least one row so that light from each row of said plurality of rows focusses substantially at said target region at said spacing from said light-transmitting but product impermeable means, and

(viii) said light emitting sources are arranged in a plurality of substantially parallel rows, and each lens system portion comprises at least one substantially cylindrical lens portion extending generally parallel to the respective row of light emitting sources.