초록 ▼

Wrinkles on polymer film as surface defect are inspected. The film is transported on an inspecting surface having a color for absorbing light. A dot pattern having dots on a transparent test chart sheet, facing the film, is photographed by image pickup upon reflection of the dot pattern on the film

Wrinkles on polymer film as surface defect are inspected. The film is transported on an inspecting surface having a color for absorbing light. A dot pattern having dots on a transparent test chart sheet, facing the film, is photographed by image pickup upon reflection of the dot pattern on the film positioned on the inspecting surface. A length of the dots being photographed is measured according to image data, to obtain length information of 1-5. A length data table of the dots is created by arranging the length information of 1-5 at locations of the dots. Occurrence of a wrinkle is determined at one of the locations if a difference between the dots occurs in the length information of 1-5 in the length data table. To a rear of the test chart sheet, inspecting light is applied, passes through, and becomes incident upon the film.

대표청구항 ▼

What is claimed is: 1. A surface defect inspecting method comprising steps of: transporting film on an inspecting surface having a color for absorbing light; photographing a dot pattern having dots on a dot pattern test chart by image pickup upon reflection of said dot pattern on said film position

What is claimed is: 1. A surface defect inspecting method comprising steps of: transporting film on an inspecting surface having a color for absorbing light; photographing a dot pattern having dots on a dot pattern test chart by image pickup upon reflection of said dot pattern on said film positioned on said inspecting surface; measuring a length of said dots being photographed according to image data obtained by said image pickup, to obtain length information; creating a length data table of said dots by arranging said length information at locations of said dots; and determining occurrence of a surface defect at one of said locations if a difference between said dots occurs in said length information in said length data table. 2. A surface defect inspecting method as defined in claim 1, wherein said dots have a diameter equal to or more than 1 mm and equal to or less than 3 mm, and are arranged at a pitch equal to or more than 3 mm and equal to or less than 5 mm. 3. A surface defect inspecting method as defined in claim 1, wherein said dots are arranged so that dots in a first dot array thereof are offset in a zigzag manner from dots in a second dot array thereof. 4. A surface defect inspecting method as defined in claim 3, wherein said dots have a black color. 5. A surface defect inspecting method as defined in claim 3, wherein a transparent test chart sheet constitutes said test chart and is disposed to face said film; inspecting light is applied to a rear of said test chart sheet, passes through, and becomes incident upon said film. 6. A surface defect inspecting method as defined in claim 5, wherein said inspecting surface is a peripheral surface of an inspecting roller, and a diameter of said inspecting roller is equal to or more than 250 mm and equal to or less than 500 mm. 7. A surface defect inspecting method as defined in claim 6, wherein said peripheral surface of said inspecting roller is finished by mat finish. 8. A surface defect inspecting method as defined in claim 6, wherein said film contacts on said inspecting roller at a wrap angle equal to or more than 120 degrees and equal to or less than 180 degrees. 9. A surface defect inspecting method as defined in claim 8, wherein said determining step includes: classifying said dots into an acceptable dot and an unacceptable dot in said length data table according to said length; splitting said length data table into blocks with a prescribed area, to acquire amounts of said unacceptable dot per said blocks; if said amounts of said unacceptable dot per said blocks are more than a prescribed value, determining suspected defective blocks therewith retrieved among said blocks; defining a suspected defective pattern by continuation of adjacent suspected defective blocks among said suspected defective blocks; said surface defect is determined from said suspected defective pattern by evaluating a shape thereof. 10. A surface defect inspecting method as defined in claim 9, wherein said acceptable dot has a length of length information equal to a predetermined middle rank length information, and said unacceptable dot has a length of length information higher or lower than said predetermined middle rank length information. 11. A surface defect inspecting method as defined in claim 9, wherein said surface defect is constituted by a wrinkle on said film. 12. A surface defect inspecting method as defined in claim 11, wherein adjacent suspected defective blocks being consecutive in any one of vertical, horizontal and diagonal directions are retrieved among said suspected defective blocks, and combined to define a defective pattern, and said wrinkle is constituted by said defective pattern. 13. A surface defect inspecting method as defined in claim 12, wherein said wrinkle is graded in prescribed grades according to a number of said suspected defective blocks. 14. A surface defect inspecting method as defined in claim 11, wherein said suspected defective blocks are plotted at points defined on a two-dimensional coordinate system; a gradient and intercept of a straight line, which passes said points or vicinity of said points, are obtained by least square approximation, and said suspected defective pattern is determined from said straight line according to said gradient and said intercept thereof, said wrinkle being determined by evaluating said suspected defective pattern. 15. A surface defect inspecting method as defined in claim 14, wherein said wrinkle is graded in prescribed grades according to a length of said straight line. 16. A surface defect inspecting method as defined in claim 15, wherein said surface defect is detected before winding said film in producing said film. 17. A surface defect inspecting method as defined in claim 1, wherein said length information is information for expressing said length of said dots stepwise in plural ranks. 18. A surface defect inspecting method as defined in claim 1, wherein said measuring step includes: detecting image portions in said image data by edge point detection of image density; and measuring said image portions detected by said edge point detection, so as to obtain said length information of said dots being photographed. 19. A surface defect inspecting method as defined in claim 1, wherein each of said blocks in said length data table is constituted by a predetermined plural number of said dots. 20. A surface defect inspecting method as defined in claim 1, wherein an alarm signal is output when said surface defect is detected. 21. A surface defect inspecting method as defined in claim 1, wherein if a plurality of said surface defect are detected, a largest one of said plurality of said surface defect is selected. 22. A surface defect inspecting method as defined in claim 1, wherein said film is subjected to removal of said surface defect when said surface defect is detected. 23. A surface defect inspector comprising: a transporting mechanism for transporting film on an inspecting surface having a color for absorbing light; a dot pattern test chart for indicating a dot pattern having dots; an image pickup device for photographing said dot pattern by image pickup upon reflection of said dot pattern on said film positioned on said inspecting surface; a determiner for measuring a length of said dots being photographed according to image data obtained by said image pickup, to obtain length information, for creating a length data table of said dots by arranging said length information at locations of said dots, and for determining occurrence of a surface defect at one of said locations if a difference between said dots occurs in said length information in said length data table. 24. A surface defect inspector as defined in claim 23, further comprising: a transparent test chart sheet, disposed to face said film, for constituting said test chart; a surface light source for applying inspecting light to a rear of said test chart sheet, for passing through and becoming incident upon said film. 25. A surface defect inspector as defined in claim 23, wherein said inspecting surface is a peripheral surface of an inspecting roller, and a diameter of said inspecting roller is equal to or more than 250 mm and equal to or less than 500 mm. 26. A surface defect inspector as defined in claim 25, wherein said peripheral surface of said inspecting roller is finished by mat finish. 27. A surface defect inspector as defined in claim 25, wherein said film contacts on said inspecting roller at a wrap angle equal to or more than 120 degrees and equal to or less than 180 degrees. 28. A surface defect inspector as defined in claim 25, wherein said test chart and said image pickup device are disposed higher than said inspecting roller; an angle defined between an optical axis of said surface light source and an optical axis of said image pickup device is equal to or more than 30 degrees and equal to or less than 60 degrees.