JPH04364450A - Defect inspecting and identifying apparatus - Google Patents

Abstract

PURPOSE:To detect the defect of a surface positively and highly accurately by picking up the image of a material under inspection with an image sensing device having the general-purpose applications. CONSTITUTION:A defect inspecting and identifying apparatus is formed of an image sensing device 12 for picking up the image of a material under inspection, a processing device 20 for converting the data from the image sensing device 12 into the digital image, inspecting the good/bad states of the surface of the material under inspection 10 through a CPU 23 and identifying the kinds of the defects such as irregularities, foreign matters, blurred parts and the like and an output part 30. The processing device 20 corrects the concentration gradient of a lighting 11 and discriminates between the presence and the absence and the kinds of the defects based on the difference between the maximum and minimum values of the corrected concentration profile and the difference between the positions or by comparing the average value of the concentration profile with a threshold value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting and identifying defects on the surface of tapes, films, etc.

0002

2. Description of the Related Art Conventionally, a device for detecting defects existing on a surface has been used, for example, as shown in Japanese Patent Laid-Open No. 55-70732, which irradiates the surface of an object to be inspected with a He-Ne laser beam. There is a method for inspecting the surface condition based on the degree to which light is scattered in arbitrary directions due to unevenness.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional surface condition inspection apparatus using the light irradiation-scattering method has the following problems:
There are the following problems.

(2) The optical system is complicated and the device becomes large. ■Poor detection ability for streak-like defects flowing in the line direction. ■Detection results do not necessarily match the sense perceived by the human eye.

(2) When inspecting wide tapes, films, etc., the detection ability at both ends is low. ■If the sensitivity is set high, even non-defects may be detected, such as foreign substances due to pulp on the tape surface.

[0006] The defect inspection/identification apparatus of the present invention aims to reliably inspect the state of defects in a state similar to that seen by the human eye, using a compact device configuration.

[0007]

[Means for solving the problem] Defect inspection of the present invention 1
The identification device includes an illumination device that illuminates the surface of the object to be inspected, an imaging device that images the surface of the object to be inspected, a processing device that inspects the surface condition of the object to be inspected based on the imaging result of the imaging device, and a processing device that A surface defect inspection device comprising an output section that outputs the inspection results of the device, and emits light from the upper side of the object to be inspected diagonally from the side, and images the reflected light from the upper surface of the object to be inspected. , the processing device corrects the density gradient caused by illumination from the average density at each end of the image, determines the maximum and minimum values and their positions from the corrected density profile, and inspects defects from the difference between the maximum and minimum values and the position difference. This is a defect inspection/identification device that is characterized by the ability to identify defects.

[0008] The defect inspection/identification device according to the second aspect of the present invention also includes an illumination device that illuminates the surface of the object to be inspected, an imaging device that images the surface of the object to be inspected, and a device that detects the object to be inspected based on the imaging result of the imaging device. This is a surface defect inspection device comprising a processing device for inspecting the surface condition of a body and an output section for outputting the inspection results of the processing device, and the device projects light from diagonally horizontally on the top surface of the object to be inspected. , the reflected light is imaged from the top surface of the object to be inspected, and the processing device corrects the density gradient due to illumination from the average density at each end of the image, calculates the average value from the corrected density profile, and sets it to a predetermined threshold value. Defect inspection characterized in that if one or more signals are present, it is determined that there is a defect, and the type of defect is identified by comparing the signal with a predetermined threshold value of 2 or less and the corrected concentration profile. It is an identification device.

[0009]

[Function] According to the present invention, the following effects (1) to (4) are achieved. ■
The surface condition can be inspected using a versatile imaging device such as a television camera, and the device configuration can be made compact.

■ Surface wrinkles can be detected reliably with a sense similar to that of humans. ■The defect inspection/identification device according to claim 1 of the present invention corrects the density gradient caused by illumination from the average density of each end of the image captured by the imaging device, and calculates maximum and minimum values and their positions from the corrected density profile. Defects are inspected and identified based on the differences in maximum and minimum values and positional differences.

Further, the defect inspection/identification device according to claim 2 of the present invention corrects the density gradient due to illumination from the average density of each end of the image captured by the imaging device, and calculates the average value from the corrected density profile. If a signal of a predetermined threshold of 1 or more is present, it is determined that there is a defect, and the type of defect is identified by comparing the signal of a predetermined threshold of 2 or less with the corrected density profile.

0012

[Example] Fig. 1 is a block diagram showing an example of the defect inspection/identification device of the present invention, Fig. 2 is a flow diagram showing the inspection/identification procedure of the device of the invention 1, and Fig. 3 is a flow diagram showing an example of the defect inspection/identification device of the invention 2. Flowchart showing the inspection/identification procedure of the device, FIG. 4 is a diagram explaining the concentration gradient correction method, FIG. 5 is a schematic diagram of the concentration profile before and after correction of the concentration gradient, and FIG. 6 is a diagram showing the concentration difference and position. FIG. 7, which is a diagram showing the relationship between the differences, is a diagram showing the concentration profile of each defect.

[0013] The defect inspection/identification device includes an imaging device 12,
It has an illumination 11, a processing device 20, and an output section 30, and inspects and identifies defects in the object to be inspected 10. The basic operations of the defect inspection/identification apparatus are as follows: 1) The object to be inspected 10 is illuminated with the illumination 11 from diagonally above the object, and the reflected light is imaged by the imaging device 12.

The imaging device 12 transfers a multivalued image sampled pixel by pixel to the inspection device 20. 2) The inspection device 20 converts the photographic data of the imaging device 12 into an A/D
The converter 21 quantizes, for example, 8 bits (256 gradations) to create a digital image of M*N pixels, which is input to the image memory 22.

3) The inspection device 20 uses the CPU 23 to inspect the surface for defects based on the image input to the image memory 22. 4) The output device 30 displays the inspection results of the inspection device 20 and generates an alarm if necessary.

Note that as the imaging device 12, a television camera or a line sensor having a spatial resolution of M can be used. When a line sensor is used, the line sensor and the object to be inspected are moved relative to each other, and the resulting N groups of data are stored in the image memory 22.

The inspection device 20 does not necessarily have the image memory 22.
The output data of the A/D converter 21 is sent directly to the CPU without using
23 may be entered. The flow up to abnormality determination according to the first invention will be explained with reference to FIG.

1) Average density μL at both left and right ends of the image
, find μR. That is, the density of coordinates (i, j) is expressed as f(i
,j) as

[0019]

[Math 1]

[0020]

[Math 2]

[0021] 2) From these density average values, the density gradient due to illumination is corrected according to the following equation. The illumination is projected from the left side of the screen to the right side, and if the quantization is 8 bits and the density after correction is g (i, j),

[0022]

[Math 3]

[0023] However, a=(μR-μL)/255+μ
Lb: Any 3) The maximum value M from the density profile in the corrected direction
Xj, minimum value MNj and their positions PXj, PNj
4) Calculate the density difference ΔMj and position difference ΔPj, and 5) From this distribution, identify defects such as unevenness, foreign matter, and blurring.

[0024] At this time, the average value μj is determined for the entire region, and the concentration profiles are determined one after another for determination. However, the connectivity is checked, and the determination is made when the concentration difference is maximum, and the result is Output.

Further, the flow up to abnormality determination according to the second invention will be explained with reference to FIG. 1) Calculate the density average values μL and μR at both left and right ends of the image. That is, if the density of coordinates (i, j) is f(i, j),

[0026]

[Math 4]

[0027]

[Math 5]

[0028] 2) From these density average values, the density gradient due to illumination is corrected according to the following equation. The illumination is projected from the left side of the screen to the right side, and if the quantization is 8 bits and the density after correction is g (i, j),

[0029]

[Math 6]

[0030] However, a=(μR-μL)/255+μ
Lb: Arbitrary 3) Average value μ from the density profile in the corrected direction
4) If the density profile exceeds the average value, determine that there is a defect. 5) Set a certain value Td from the average value, compare it with the density profile Pj, and judge it as unevenness, foreign matter, or blurring. Defects μj
-Td>Pj: Unevenness or foreign matter μj-Td≦Pj: Classified as blur.

6) A certain value Ts is set from the average value and compared with the density profile Pjs, and it is determined that μj-Ts>Pjs: foreign matter μj-Ts≦Pjs: unevenness.

[0032] At this time, density profiles are obtained and judged one after another, but the previous judgment result is memorized.
If the next determination at the same position is the same as the previous one, it is determined that the defects are connected, and the results including their size are output.

[0033]

As described above, according to the present invention, defects in an object to be inspected can be reliably inspected and defects can be classified using a compact device configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a flowchart showing the flow of abnormality determination according to the first invention.

FIG. 3 is a flowchart showing the flow of abnormality determination according to the second invention.

FIG. 4 is a diagram illustrating a concentration gradient correction method.

FIG. 5 is a schematic diagram of density profiles before and after density gradient correction.

FIG. 6 is a diagram showing the relationship between density difference and position difference according to the first invention.

FIG. 7 is a diagram showing a concentration profile of defects according to the second invention.

[Explanation of symbols]

10 Object to be inspected 11　　　　　　　　Lighting device 12 Imaging device 20 Processing equipment 21 A/D converter 22 Image memory 23 CPU 30 Output section

Claims (2)

[Claims] 1. An illumination device that illuminates the surface of an object to be inspected, an imaging device that images the surface of the object to be inspected, and a processing device that inspects the surface state of the object to be inspected based on the imaging result of the imaging device. This is a surface defect inspection device comprising an output unit that outputs the inspection results of the processing device, and the device projects light from the upper surface of the object to be inspected in an oblique horizontal direction, and images the reflected light from the upper surface of the object to be inspected. Then, the processing device corrects the density gradient due to illumination from the average density at each end of the image, determines the maximum and minimum values and their positions from the corrected density profile, and identifies defects from the difference between the maximum and minimum values and the position difference. A defect inspection/identification device characterized by inspection and identification. 2. An illumination device that illuminates the surface of the object to be inspected, an imaging device that images the surface of the object to be inspected, and a processing device that inspects the surface state of the object to be inspected based on the imaging result of the imaging device. This is a surface defect inspection device comprising an output unit that outputs the inspection results of the processing device, and the device projects light from the upper surface of the object to be inspected in an oblique horizontal direction, and images the reflected light from the upper surface of the object to be inspected. Then, the processing device corrects the density gradient due to illumination from the average density of each end of the image, calculates the average value from the corrected density profile, and determines that there is a defect if a signal of a predetermined threshold of 1 or more is present. A defect inspection/identification apparatus characterized in that the type of defect is identified by comparing a signal of a predetermined threshold value 2 or less with the corrected density profile.