WO2014112653A1

WO2014112653A1 - Image generation device, defect inspection device, and defect inspection method

Info

Publication number: WO2014112653A1
Application number: PCT/JP2014/051160
Authority: WO
Inventors: 麻耶尾崎
Original assignee: 住友化学株式会社
Priority date: 2013-01-16
Filing date: 2014-01-15
Publication date: 2014-07-24
Also published as: JPWO2014112653A1; TW201435333A; JP6191623B2; CN104919306A; KR20150106878A; CN104919306B; TWI607212B; KR102111823B1

Abstract

A defect inspection device (100) is provided with: a transport unit (11) that transports a sheet-like molded body; a light irradiation unit (12) that irradiates light on the sheet-like molded body; an imaging unit (13) that generates two-dimensional image data by means of an imaging operation; a boundary extraction unit (1411) that extracts boundary line parts between light and dark parts in two-dimensional images represented by the two-dimensional image data; a re-extraction unit (1412) that connects the boundary line parts extracted by the boundary extraction unit (1411) to form apparent boundary lines, smooths the apparent boundary lines in such a manner that sharp peaks appearing on the apparent boundary lines disappear, and extracts, from the two-dimensional image data, pixels constituting intrinsic boundary lines obtained by smoothing; and a synthesizing unit (1413) that generates one-dimensional image data comprising the pixels extracted by the re-extraction unit (1412), and generates inspection image data by synthesizing a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data.

Description

Image generating apparatus, defect inspection apparatus, and defect inspection method

The present invention relates to an image generation apparatus that generates image data for inspecting a defect in a sheet-like molded body, a defect inspection apparatus including the image generation apparatus, and a defect inspection method.

Conventionally, an inspection using a camera is known as a method for inspecting a defect of a sheet-like molded body such as a polarizing film or a retardation film. For example, Japanese Patent Application Laid-Open No. 2007-333563 (Patent Document 1) irradiates a sheet-shaped molded body with light by a light source, and captures a transmitted light image transmitted and refracted through the sheet-shaped molded body with a line sensor camera. Thus, the defects of the sheet-like molded body are inspected. In addition, a method for inspecting a defect of a sheet-like molded body by capturing a reflected light image instead of capturing a transmitted light image is also conventionally known.

With reference to FIG. 10, an example of a method for inspecting the presence or absence of a dot-like dent defect generated in a sheet-like molded body with a line sensor camera will be described. Sheet materials L shown in FIG. 10, it is assumed that the point-shaped indentations defect L ₁ occurs in the width direction X center. The sheet-like molded body L is conveyed in one of the longitudinal directions Y. As a result, as shown in FIGS. 10 (a) to 10 (c), the dent defect L1 sequentially moves in _one of the longitudinal directions Y. To do.

As shown in FIG. 10 (a) ~ FIG 10 (c), the light source (not shown) extending in the width direction X, and the light portion L ₂ and the dark L ₃ occurs in the sheet materials L. Light source is fixed is located, that the sheet-shaped molded body L is transported, the position of the bright portion L ₂ would sequentially move in the longitudinal direction Y while on sheet materials L. The bright portion near the boundary line between L ₂ and the dark L ₃ are formed so that the imaging range B, the line sensor camera (not shown) is provided. Line sensor camera is positioned relative to the light source is fixed, the sheet-like shaped body L is transported stably and recessed defects L ₁ as long as not near the imaging area, FIG. 10 (a) and 10 ( As shown in c), the images in the vicinity of the boundary line between the bright part L ₂ and the dark part L ₃ are the same, and the images G ₁ and G ₃ acquired by the line sensor camera are also the same. However, as shown in FIG. 10 (b), if the dent defect L ₁ is near the imaging area, an image of the vicinity of the boundary between the bright portion L ₂ and the dark L ₃ is changed by the recess viewed defective L _1, the As a result, unlike the images G ₁ and G ₃ , the dark portion L ₃ is greatly reflected in the image G ₂ acquired by the line sensor camera. Accordingly, as shown in FIG. 10 (d), the by sequentially combining images acquired by the line sensor camera, it is possible to synthesize the test image G ₄ where the position of the defect L ₁ indentation by dark part is shown .

The defect inspection method described with reference to FIG. 10 is based on the premise that the sheet-like molded body L is stably conveyed as described above. However, the sheet-like molded body L may flutter during conveyance and is not necessarily conveyed stably. If the sheet-like molded product L flutters during conveyance, the positional relationship between the sheet-like molded product L, the line sensor camera, and the light source changes, and the defect inspection method may not find a defect well.
In the present invention, the state in which the sheet-like molded body flutters is a state in which, for example, when the sheet-like molded body is conveyed in the horizontal direction, a part or all of the sheet-like molded body is shaken violently up and down. For example, when the sheet-shaped molded body is conveyed in the vertical direction, it means a state in which part or all of the sheet-shaped molded body is swaying violently from side to side.

The case where the sheet-like molded object L flutters is demonstrated using FIG. 11 (a) and 11 (b), no fluttering occurs, the same state as in FIGS. 10 (a) and 10 (b), and in FIG. 11 (c), fluttering occurs. And As shown in FIG. 11 (c), when the sheet materials L flutters, dents even without defects L ₁ is in the vicinity of the imaging area, the image is changed by the fluttering of the vicinity of the boundary between the bright portion L ₂ and the dark L ₃ As a result, unlike the images G ₁ and G ₂ , the dark portion L ₃ may be greatly reflected in the image G ₅ acquired by the line sensor camera. In this case, the test image G ₆ which would indicate the position of the defect L ₁ indentation by dark portion, as shown in FIG. 11 (d), the dent defect L ₁ would occur dark portion unrelated, dents the defective L ₁ is likely to be misjudged as a defect even unrelated position. In a state different fluttering and 11, when the dent defect L ₁ is near the imaging area, also it is possible that the image acquired by the line sensor camera is not incorporated-through dark portion L _3, sheet materials L May be misjudged so that there are no defects.

The present invention is to solve such a problem, in the image generation apparatus for generating image data for inspecting the defects of the sheet-shaped molded body, due to fluttering of the sheet-shaped molded body, An object of the present invention is to provide an image generation apparatus capable of preventing erroneous determination of the presence or absence of a defect, a defect inspection apparatus including the image generation apparatus, and a defect inspection method.

The present invention
An image generation device that generates image data for inspecting a defect in a sheet-like molded body,
A transport unit for transporting the sheet-shaped molded body in the longitudinal direction of the sheet-shaped molded body;
A light source that includes a light source that extends linearly in the width direction of the sheet-like molded body, and that irradiates the sheet-like molded body with light by the light source;
An imaging unit that performs an imaging operation on the sheet-like molded body being conveyed to generate two-dimensional image data representing a two-dimensional image, and includes a bright part corresponding to the light source and the bright part in the two-dimensional image An imaging unit that performs multiple imaging operations on the sheet-like molded body at a position including a dark part having a lower brightness than the part;
An inspection image data generation unit that generates inspection image data from a plurality of two-dimensional image data generated by the imaging unit,
A boundary extraction unit that extracts a boundary part between the bright part and the dark part in each two-dimensional image represented by each two-dimensional image data;
The boundary line is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there are no sharp peaks appearing on the apparent boundary line. A re-extraction unit that extracts the pixels constituting the two-dimensional image data;
Synthesis that generates one-dimensional image data composed of pixels extracted by the re-extracting unit, and similarly generates a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data to generate inspection image data. And
An inspection image data generation unit including:
An image generation apparatus is provided.

The present invention also provides
The image generating device;
A display unit for displaying an image represented by the inspection image data generated by the inspection image data generation unit of the image generation device;
A defect inspection apparatus is provided.

The present invention also provides
A defect inspection method for inspecting defects in a sheet-like molded body,
In a state where the sheet-shaped molded body is conveyed in the longitudinal direction of the sheet-shaped molded body while irradiating the sheet-shaped molded body with light by a light source extending linearly in the width direction of the sheet-shaped molded body. An imaging step of performing an imaging operation on a molded body to generate two-dimensional image data representing a two-dimensional image, and the brightness of the bright part corresponding to the light source in the two-dimensional image is lower than that of the bright part An imaging step of performing an imaging operation a plurality of times on the sheet-like molded body so as to include a dark part; and
A boundary extraction step for extracting a boundary portion between the bright portion and the dark portion in the name two-dimensional image represented by each two-dimensional image data generated in the imaging step;
The boundary line is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there are no sharp peaks appearing on the apparent boundary line. A re-extraction step of extracting pixels constituting the two-dimensional image data;
1-dimensional image data composed of the pixels extracted in the re-extraction step is generated, and a plurality of 1-dimensional image data obtained from a plurality of 2-dimensional image data is similarly combined to generate inspection image data. Process,
A display step of displaying an image represented by the inspection image data generated in the synthesis step;
A defect inspection method including

According to the present invention, in the image generation device, a plurality of two-dimensional image data are obtained by performing a plurality of imaging operations on the sheet-shaped molded body in a state where light is irradiated on the sheet-shaped molded body being conveyed. Is generated. Then, a boundary line portion between a bright portion and a dark portion in each two-dimensional image represented by each two-dimensional image data is extracted. Next, the boundary line portion is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there is no sharp peak appearing on the apparent boundary line. The pixels constituting the original boundary line obtained by the smoothing are re-extracted from the two-dimensional image data, and one-dimensional image data including the pixels constituting the original boundary line is generated. Similarly, a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data are combined to generate inspection image data.

When a defect is generated in the sheet-shaped molded body, when the sheet-shaped molded body is stably conveyed and a defect is located near the boundary line portion, the apparent boundary is caused by the defect. The line is a distorted curve with sharp peaks. Therefore, the original boundary line obtained by smoothing the apparent boundary line is different from the apparent boundary line. Further, when a defect is generated in the sheet-like molded article, the sheet-like molded article flutters during conveyance, and when the defect is not located near the boundary line portion, By fluttering, the apparent boundary line becomes a gentle curve. Therefore, the original boundary line obtained by smoothing the apparent boundary line is almost the same curve as the apparent boundary line or the same curve as the apparent boundary line.

Therefore, one-dimensional image data composed of pixels constituting the original boundary line is generated from each two-dimensional image data, and a plurality of the obtained one-dimensional image data is synthesized to obtain inspection image data. Thus, it is possible to generate inspection image data indicating the position of the defect according to the positional relationship between the bright part and the dark part. As a result, it is possible to determine the presence or absence of defects in the sheet-like molded body based on the inspection image data, and prevent erroneous determination of the presence or absence of defects due to flapping of the sheet-like molded body. be able to.

According to the present invention, a defect inspection apparatus includes the image generation apparatus according to the present invention and a display unit. The display unit displays an image represented by the inspection image data generated by the inspection image data generation unit of the image generation apparatus. By viewing the image displayed on the basis of the image data for inspection by the display unit, it is possible to determine the presence / absence of a defect, and an erroneous determination is made regarding the presence / absence of a defect due to flapping of the sheet-like molded product. Can be prevented.

According to the present invention, in the defect inspection method, a plurality of imaging operations are performed on the sheet-shaped molded body in a state where light is irradiated on the sheet-shaped molded body being conveyed in the imaging process. Two-dimensional image data is generated. Then, in the boundary extraction step, a boundary line portion between a bright part and a dark part in each two-dimensional image represented by each two-dimensional image data is extracted. Next, in the re-extraction step, the boundary line portion is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there is no sharp peak appearing on the apparent boundary line. The pixels constituting the original boundary line obtained by smoothing are re-extracted from the two-dimensional image data. Further, in the synthesizing step, one-dimensional image data composed of pixels constituting the original boundary line is generated, and a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data is synthesized in the same manner to obtain a bright portion. Then, inspection image data indicating the position of the defect is generated based on the positional relationship between the dark portions and the image represented by the inspection image data is displayed in the display step. The presence or absence of defects can be determined by looking at the image displayed based on the image data for inspection displayed in the display process. It can be prevented from happening.

It is a perspective view which shows the defect inspection apparatus 100 which concerns on this invention. 1 is a block diagram showing a defect inspection apparatus 100 according to the present invention. It is process drawing which shows the defect inspection method which concerns on this invention. It is a figure which shows the mode of the sheet-like molded object K. FIG. It is a figure which shows the image obtained by imaging with respect to the sheet-like molded object K. FIG. It is a figure which shows the image obtained by imaging with respect to the sheet-like molded object K. FIG. It is a figure which shows the image obtained by imaging with respect to the sheet-like molded object K. FIG. It is a figure which shows the image obtained by imaging with respect to the sheet-like molded object K. FIG. FIG. 10 is a diagram for describing a specific example of processing by a re-extraction unit 1412. It is a figure for demonstrating an example of the method of test | inspecting the presence or absence of the dotted | punctate dent defect which arose in the sheet-like molded object L with the line sensor camera. It is a figure for demonstrating the case where the sheet-like molded object L flutters.

Hereinafter, an image generation apparatus, a defect inspection apparatus, and a defect inspection method according to the present invention will be described. FIG. 1 is a perspective view showing a defect inspection apparatus 100 according to the present invention. FIG. 2 is a block diagram showing a defect inspection apparatus 100 according to the present invention. FIG. 3 is a process diagram showing a defect inspection method according to the present invention. The defect inspection apparatus 100 is an apparatus for inspecting a defect of a sheet-like molded body, and is an apparatus capable of performing the defect inspection method according to the present invention, which is a method for inspecting the defect. The defect inspection apparatus 100 can inspect, for example, an optical film such as a polarizing film or a retardation film as a sheet-like molded body, and is particularly suitable for inspection of a long optical film wound and stored in a web shape. ing.

The sheet-like molded body is made of a resin such as a thermoplastic resin, for example. As the sheet-like molded body made of resin, for example, the thermoplastic resin extruded from the extruder is passed through the gaps between the rolls to give the surface smoothness and gloss, and the take-up roll cools the transport roll. However, what was shape | molded by being taken up is mentioned. The thermoplastic resin used as the material of the sheet-like molded body is, for example, methacrylic resin, methyl methacrylate-styrene copolymer, polyolefin such as polyethylene and polypropylene, polycarbonate, polyvinyl chloride, polystyrene, polyvinyl alcohol, and triacetyl cellulose resin. Etc. The sheet-like molded body may consist of only one of these thermoplastic resins, or may be a laminate of a plurality of types of these thermoplastic resins.

The sheet-like molded body may have any thickness. For example, the sheet-like molded body may have a relatively thin thickness such as a polarizing film or a retardation film, generally called “film”, and a relatively thick thickness generally called “plate”. You may have.

Examples of such defects in the sheet-like molded product include so-called nicks (point defects) caused by bubbles, fish eyes, foreign matter, tire marks, dent marks, scratches, and crease marks generated during molding. knick) and linear defects (line defects) such as so-called original stripes caused by the difference in thickness.

As shown in FIGS. 1 and 2, the defect inspection apparatus 100 includes an image generating apparatus 1 according to the present invention and a display unit 21. The image generation apparatus 1 of the defect inspection apparatus 100 includes a conveyance unit 11 that conveys the sheet-shaped molded body K in one of the longitudinal directions (hereinafter referred to as “Y direction”), and the width direction (hereinafter, referred to as “sheet-shaped molded body K”). A light irradiation unit 12 having a light source extending linearly in the “X direction”, an imaging unit 13 that performs an imaging operation on the sheet-like molded body K and generates two-dimensional image data representing a two-dimensional image; And an information processing device 14. The information processing apparatus 14 includes an inspection image data generation unit 141, and the inspection image data generation unit 141 includes a boundary extraction unit 1411, a re-extraction unit 1442, and a synthesis unit 1413. The information processing apparatus 14 also includes a conveyance control unit (not shown) that controls the operation of the conveyance unit 11. The information processing apparatus 14 is realized by a PC (Personal Computer) or the like. Note that the inspection image data generation unit 141 in the information processing apparatus 14 is an internal hardware of the image processing board or the imaging unit 13 such as a field-programmable gate array (FPGA) or a general-purpose computing on graphics processing unit (GPGPU). Can also be realized.

As shown in FIG. 3, the defect inspection method according to the present invention includes an imaging step S1, a boundary extraction step S2, a re-extraction step S3, a synthesis step S4, and a display step S5.
In the imaging step S <b> 1, the light source of the light irradiation unit 12 is in a state where the sheet-like molded body is conveyed in the Y direction by the conveyance unit 11 while irradiating the sheet-shaped molded body K with the light source of the light irradiation unit 12. The imaging unit 13 performs a plurality of imaging operations on the sheet-shaped molded body K so that the two-dimensional image includes a bright part corresponding to the above and a dark part whose luminance is lower than that of the bright part.

The boundary extraction step S2 changes from a bright part to a dark part in each two-dimensional image represented by each two-dimensional image data generated by the imaging unit 13 in the imaging step S1, or from a dark part to a bright part. In this step, the boundary line portion is extracted by the boundary extraction portion 1411.
In the re-extraction step S3, the re-extraction unit 1412 connects the boundary line portions obtained in the boundary extraction step S2 to form an apparent boundary line, and the sharp peak appearing on the apparent boundary line is eliminated. This is a step of smoothing the apparent boundary line and extracting the pixels constituting the original boundary line obtained by the smoothing from the two-dimensional image data.

In the synthesizing step S4, one-dimensional image data including pixels extracted by the re-extracting unit 1412 in the re-extracting step S3 is generated by the synthesizing unit 1413, and a plurality of 1s obtained from a plurality of two-dimensional image data in the same manner This is a step of synthesizing the dimensional image data and generating inspection image data indicating the position of the dent defect or the convex defect by the change in luminance. For example, at the boundary line portion when changing from a bright portion to a dark portion, the position of the dent defect is shown as a dark portion.
The display step S5 is a step of displaying an inspection image represented by the inspection image data generated by the combining unit 1413 in the combining step S4 on the display unit 21.

Each step S1 to S5 will be described with reference to FIGS. FIG. 4 is a diagram showing a state of the sheet-shaped molded body K, and FIGS. 5 to 8 are diagrams showing images obtained by imaging the sheet-shaped molded body K. FIG. As shown in FIG. 4, it is assumed that a point-like dent defect K ₁ is generated in the sheet-like molded body K. Further, it is assumed that the sheet-like molded body K is conveyed in one direction in the Y direction in the order shown in FIGS. 4 (a), 4 (b), and 4 (c).

As shown in FIG. 4 (a), the light source of the light irradiation portion 12 extending linearly in the X direction, on a sheet-shaped molded body K, the bright portion K ₂ extending linearly in the X direction,該明portion K _{And a} dark portion K ₃ having a luminance lower than ₂ . The bright portion K ₂ extends linearly, no fluttering of sheet materials K molded sheet K is conveyed stably, and, when not in the vicinity of the recessed defect K ₁ GaAkira portion K ₂ It is. As shown in FIG. 4 (b), when in the vicinity of the recessed defect K ₁ GaAkira section K _2, bright portion K ₂ is not a straight line. FIG. 4 (c), unlike FIGS. 4 (a) and 4 (b), shows a case where the sheet-like shaped body K during conveyance is flapping, in this case, recessed defects K ₁ Ming Although part K ₂ is not in the vicinity, due to the fluttering of the sheet-like shaped body K, bright portion K ₂ is no longer a straight line.

A two-dot chain line A shown in FIG. 4 indicates an imaging range by the imaging unit 13. In imaging step S1, the imaging unit 13, within the imaging range, so that the dark portion K ₃ adjacent to the bright portion K ₂ and該明section K ₂ enters, performs the imaging operation. The two-dimensional image that is the imaging result in FIG. 4A is the two-dimensional image shown in FIG. 5A, and the two-dimensional image that is the imaging result in FIG. 4B is shown in FIG. The two-dimensional image which is a two-dimensional image and is the imaging result in FIG. 4C is the two-dimensional image shown in FIG. Each pixel constituting each two-dimensional image has an integer X coordinate value that continuously increases toward the right side in the X direction in FIGS. 5, 6, and 7, and an integer that continuously increases toward the lower side in the Y direction. Y coordinate values are assigned. In FIG. 5A, FIG. 6A, and FIG. 7A, the bright portion is a white portion and the dark portion is a hatched portion.

In the boundary extraction step S2, a boundary line portion is extracted by the boundary extraction unit 1411 from each two-dimensional image shown in FIGS. 5 (a), 6 (a), and 7 (a). The boundary part is, for example, a part of a part of the bright part in the two-dimensional image that is adjacent to the bright part and changes to a dark part having a larger Y coordinate value than the bright part. The boundary line portion can be extracted by a conventionally known edge extraction method. For example, with respect to the data of one pixel column along the Y direction in the two-dimensional image, the pixel of interest is sequentially selected from the pixel having the smallest Y coordinate value, and the luminance value of the pixel having one Y coordinate value larger than the pixel of interest is When the luminance value of the target pixel is greater than a predetermined threshold value, a pixel having a Y coordinate value larger by one than the target pixel may be extracted as a pixel constituting the boundary line portion. Hereinafter, the pixel extracted in this way is referred to as an extracted pixel. The boundary line portion constituted by the pixels extracted from the two-dimensional images shown in FIG. 5A, FIG. 6A, and FIG. And FIG. 7 (b) respectively. An apparent boundary line can be obtained by connecting the boundary portions of adjacent pixel columns.

When a defect exists in the vicinity of the boundary line between the bright part and the dark part, the apparent boundary line obtained in this way is affected by the defect and a sharp peak appears. The re-extraction step S3 is a step of obtaining a boundary line portion that forms an original boundary line excluding the influence of the defect. Therefore, in the re-extraction step S3, first, the apparent boundary line is smoothed so that there is no sharp peak in the apparent boundary line. For example, a peak whose peak height is a predetermined multiple of the peak width (for example, 1/2 to 2 times) or more is regarded as a sharp peak. The boundary line. In the re-extraction step S3, the pixels constituting the original boundary line thus obtained are extracted from the original two-dimensional image data. Hereinafter, the pixels extracted in this way are referred to as re-extracted pixels.
When there is no defect near the boundary between the bright part and the dark part, no sharp peak appears in the apparent boundary obtained in the boundary extraction step S2, and the original obtained in the re-extraction step S3. The boundary line is the same as the apparent boundary line obtained in the boundary extraction step S2. Therefore, when there is no defect near the boundary between the bright part and the dark part and there is no sharp peak in the apparent boundary obtained in the boundary extraction step S2, the re-extraction step S3 is substantially skipped. May be.

In FIG. 5B, FIG. 6B, and FIG. 7B, apparent boundary lines j ₁ , j ₂ , and j ₃ are shown by two-dot chain lines, respectively. Figure 5 boundary j ₁ shown in (b) is a straight line, the boundary line j ₃ shown in FIG. 7 (b), no sharp peaks are gentle curve. Therefore, for the two-dimensional image shown in FIG. 5A and the two-dimensional image shown in FIG. 7A, it is not necessary to re-extract the pixels in the re-extraction step S3, and the pixels constituting the apparent boundary line However, this is the pixel that constitutes the original boundary line. In contrast, the boundary line j ₂ shown in FIG. 6 (b) is a distorted curve with a sharp peak. This distortion boundaries j ₂ The smoothed curve is a straight line j ₄ shown by a broken line in Figure 6 (b). Therefore, the original boundary line is the same as j ₂ which is the apparent boundary line for the X coordinate values 1 to 4 and 8 to 10, and is the straight line j ₄ for the X coordinate values 5 to 7. In the re-extraction step S3, the data of the pixels constituting the obtained original boundary line is extracted from the original two-dimensional image data. FIG. 6C shows the re-extracted pixel extracted from the two-dimensional image shown in FIG. Among the re-extracted pixels, pixels having X coordinate values of 5 to 7 correspond to boundary portions distorted by defective portions included in the original two-dimensional image data, and have brightness values that are brighter or darker than other pixels.

In the synthesizing step S4, the synthesizing unit 1413 generates one-dimensional image data representing the one-dimensional image from the re-extracted pixels extracted from the respective two-dimensional images by the re-extracting unit 1412 in the re-extracting step S3. The one-dimensional image data is image data in which the X coordinate value and the luminance value of the re-extracted pixel are associated with each other. FIG. 5C, FIG. 6D, and FIG. 7C show one-dimensional images corresponding to the two-dimensional images shown in FIG. 5A, FIG. 6A, and FIG. Indicates.

Furthermore, in the synthesis step S4, a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data is synthesized in the same manner to generate inspection image data. In the synthesis, the one-dimensional image data corresponding to the two-dimensional image data previously generated by the imaging unit 13 has a smaller Y coordinate value, and 1 corresponding to the two-dimensional image data generated later by the imaging unit 13. Dimensional image data is obtained by continuously arranging and combining a plurality of one-dimensional image data in the Y direction so that the dimensional image data has a larger Y coordinate value and the X coordinate value of each one-dimensional image data remains unchanged. Is called. FIG. 8 shows an inspection image represented by inspection image data synthesized from the one-dimensional image data representing the one-dimensional image shown in FIGS. 5C, 6D, and 7C. .

In the synthesis step S4, binarization may be performed on each one-dimensional image data. The luminance value that serves as the threshold for binarization is set so that the bright pixel and the dark pixel in the one-dimensional image represented by the one-dimensional image data have different values after binarization. For example, the threshold value for binarization is an arithmetic average value of the maximum luminance value and the minimum luminance value in the one-dimensional image data. When binarization is performed, the image data for inspection is synthesized after binarization for each one-dimensional image data. Note that the binarization order is not limited to the above order, and after combining the one-dimensional image data, the binarization is performed on the combined two-dimensional image data. Image data may be generated.

In the display step S5, an inspection image represented by the inspection image data is displayed on the display unit 21. The inspection image is displayed on the display unit 21 based on, for example, the luminance value of each pixel so that the dark part is black and the bright part is white.

Such is performed by the defect inspection apparatus 100, according to the defect inspection method comprising the steps S1 ~ S5, when the defective K ₁ dent formed sheet K is occurring in FIG. 4 (b) as shown, the sheet-like shaped body K are conveyed stably, and, when a defect indentation near boundary portion is positioned by the concave viewed defective K _1, as shown in FIG. 6 (b) , the apparent border becomes a distorted curve j _2. Thus, the pixels in the two-dimensional image constituting a straight line j ₄ to the boundary line j ₂ was smoothed, as shown in FIG. 6 (c), will include a dark portion. Further, when the defective K ₁ dent formed sheet K is generated, as shown in FIG. 4 (c), the sheet-like shaped body K are flapping during transport, and, near the boundary portion when the not recessed defect K ₁ is located, the rattling of the sheet-like shaped body K, as shown in FIG. 7 (b), the boundary line j ₃ apparent becomes gentle curve. Accordingly, the smoothing and curve the boundary line j _3, or nearly the same curve as the boundary line j _3, or, the same curve as the boundary line j _3, the pixels in the two-dimensional image corresponding to the curve , Which is not greatly separated from the boundary line part which is a part of the bright part, is the same as that shown in FIG. Therefore, each one-dimensional image data shown in FIG. 6D and FIG. 7C is generated from each of these portions, and a plurality of one-dimensional image data is synthesized to obtain inspection image data. By this, it is possible to generate inspection image data indicating the position of the defect. As a result, the presence or absence of defects can be determined by looking at the inspection image shown in FIG. 8 displayed based on this inspection image data. It is possible to prevent an erroneous determination as to whether or not there is a defect.

The defect inspection apparatus 100 will be described in more detail below. 1 and 2 is a device that conveys a sheet-like molded body K continuous in the Y direction with a constant width in the Y direction. The transport unit 11 includes, for example, a sending roller and a receiving roller that transport the sheet-shaped molded body K in the Y direction, and the transport distance can be measured by a rotary encoder or the like. The conveyance speed at which the conveyance unit 11 conveys the sheet-like molded body K in the Y direction is set to, for example, 2 m / min to 30 m / min.

The light irradiation unit 12 is fixed to a linear light source extending in the X direction, which is a direction orthogonal to the Y direction, and a fixing (not shown) that fixes the position of the light source to a fixing position with respect to the sending roller and the receiving roller of the transport unit 11. A member. The light source is arranged on the same side as the imaging unit 13 or on the side opposite to the imaging unit 13 so that the surface of the sheet-like molded body K can be irradiated with light on the basis of the sheet-like molded body K. The light source is arranged so that the distance to the bright part on the surface of the sheet-like molded body K is, for example, 200 mm. The light source is not particularly limited as long as it emits light that does not affect the composition and properties of the sheet-like molded body K, such as a metal halide lamp, a halogen transmission light, and a fluorescent lamp.

The light irradiation unit 12 may include a slit member disposed between the light source and the sheet-like molded body K. The slit member is, for example, a light-transmitting plate-like base material made of resin, and has a light-shielding property, and strip-shaped light-shielding region portions extending in the X direction are formed at predetermined intervals in the Y direction. It is a member. When the light irradiation part 12 is provided with such a slit member, a bright / dark pattern in which bright parts and dark parts extending in the X direction are alternately repeated can be formed on the surface of the sheet-like molded body K. This makes it possible to generate inspection image data.

The imaging unit 13 includes a CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) area sensor. The imaging unit 13 is arranged so that the surface of the sheet-shaped molded body K can be imaged on the same side as the light source or on the side opposite to the light source with the sheet-shaped molded body K as a reference, and transmission from the sheet-shaped molded body K is performed. Two-dimensional image data is generated by receiving light or reflected light. The imaging unit 13 may generate two-dimensional image data by one area sensor, or may generate two-dimensional image data from data acquired by a plurality of area sensors arranged in the X direction. The imaging unit 13 is arranged so that the imaging range is the entire region in the X direction of the sheet-like molded body K.

The length W in the Y direction of the imaging range shown in FIG. 1 is preferably at least twice as long as the conveyance distance of the sheet-like molded body K conveyed during the shutter time of the imaging unit 13. In other words, the length W in the Y direction of the imaging range is preferably set so that the imaging operation is performed twice or more for the same portion of the sheet-like molded body K. For example, when the shutter time of the imaging unit 13 is 1/30 seconds to 1 second, the length W in the Y direction of the imaging range is set to about 5 mm to 50 mm. In this way, by increasing the number of images of the same portion of the sheet-like molded body K, it is possible to inspect defects with high accuracy.

The display unit 21 is, for example, a liquid crystal display, an EL (Electroluminescence) display, a plasma display, or the like. The display unit 21 displays the inspection image represented by the inspection image data on the display screen.

The inspection image data generation unit 141 includes a control arithmetic circuit such as a CPU (Central Processing Unit), a volatile memory such as a DDR SDRAM (Double Data Rate Synchronous Random Access Memory), and a flash ROM (Mold Ready), an EPROM. (Registered trademark), and a non-volatile memory such as an HDD (Hard Disk Drive). Program data for functioning as a boundary extraction unit 1411, a re-extraction unit 1412, and a synthesis unit 1413 is stored in the non-volatile memory of the inspection image data generation unit 141, and inspection image data is stored in accordance with the program data. The generation unit 141 exhibits the functions of the boundary extraction unit 1411, the re-extraction unit 1412, and the synthesis unit 1413. The inspection image data generation unit 141 can also be realized by hardware inside the image processing board or the imaging unit 13 such as FPGA or GPGPU.

The boundary extraction unit 1411 extracts a boundary line part from the two-dimensional image indicated by the two-dimensional image data generated by the imaging unit 13 by a conventionally known edge extraction method. The re-extraction unit 1412 is obtained by connecting the boundary line portion to form an apparent boundary line, and smoothing and smoothing the apparent boundary line so that the sharp peak appearing in the apparent boundary line disappears. The pixels constituting the original boundary line are re-extracted from the two-dimensional image data. The synthesizing unit 1413 generates one-dimensional image data including the re-extracted pixels, and similarly generates a plurality of one-dimensional image data obtained from the plurality of two-dimensional image data, thereby generating inspection image data. To do.

The re-extraction by the re-extraction unit 1412 will be described in detail below. The re-extraction unit 1412 re-extracts pixels from the two-dimensional image by the following processes (1) to (8).

(1) Among the extracted pixels extracted by the boundary extraction unit 1411, the pixel having the smallest X coordinate value is set as the first pixel of interest. After the process (1), the process proceeds to the process (2).

(2) Extraction pixels constituting the boundary line portion, and a predetermined number in the + X direction from the target pixel (for example, a number of 1/40 to 1/20 of the total number of pixels in the X direction of the two-dimensional image to be extracted) ) And extraction pixels within the range up to the predetermined number in the −X direction, <1> the Y coordinate values of all the extraction pixels within these ranges are At least one of the extracted pixels in the range in the <2> + X direction and at least one of the extracted pixels in the range in the −X direction that are greater than or equal to the Y coordinate value and the attention pixel It is determined whether or not the condition of having a Y coordinate value larger than the Y coordinate value of the pixel is satisfied.
If both the conditions <1> and <2> are satisfied, the current target pixel is set as the peak vertex pixel, and the process proceeds to (3).
When neither or both of these <1> and <2> conditions are satisfied, if there is an extracted pixel whose X coordinate value is one larger than the current pixel of interest, one X coordinate value is present than the current pixel of interest. The large extracted pixel is changed to the next pixel of interest, and the process (2) is performed again.
When neither or both of these <1> and <2> conditions are satisfied, if there is no extracted pixel whose X coordinate value is one greater than the current pixel of interest, the process proceeds to (5).

A specific example of processing by the re-extraction unit 1412 will be described with reference to FIG. FIG. 9A shows a part of a two-dimensional image, and FIG. 9B shows a part of extracted pixels extracted from the two-dimensional image by the boundary extraction unit 1411. Set to 3 to the predetermined number, when the pixel of interest pixel P ₁ in FIG. 9 (b), the extraction pixel within the range including the target pixel, shown in FIG. 9 (c). Further, it sets 3 to the predetermined number, when the pixel of interest pixel P ₂ in FIG. 9 (b), the extraction pixel within the range including the target pixel, shown in FIG. 9 (d). The extraction pixel shown in FIG. 9 (c), the Y-coordinate value is included is smaller extracted pixels than Y coordinate value of the pixel P ₁ is the pixel of interest. Thus, the pixel P ₁ is not set to the peak apex pixels, X coordinate value is greater extracted pixels one is changed to the next target pixel than the pixel P _1. Each extract pixels all Y coordinates shown in FIG. 9 (d) is greater than the Y-coordinate value of the pixel P ₂ is the pixel of interest. Thus, the pixel P ₂ is set to the peak apex pixels, the processing proceeds to (3).

(3) Among extracted pixels having an X coordinate value smaller than the peak vertex pixel, an extracted pixel having a Y coordinate value larger than the peak vertex pixel and the largest X coordinate value is set as a peak left end candidate pixel. Of the extracted pixels having an X coordinate value larger than that of the peak vertex pixel, an extracted pixel having a Y coordinate value larger than the peak vertex pixel and the smallest X coordinate value is set as a peak right end candidate pixel. When the pixel P ₂ is set to the peak apex pixels shown in FIG. 9 (b), the pixel P ₃ is the peak left candidate pixel, the pixel P ₄ reaches a peak right edge candidate pixel. After the process (3), the process proceeds to the process (4).

(4) The following processing (4-1) and processing (4-2) are performed sequentially or in parallel.
(4-1) It is determined whether or not the condition that the Y coordinate value of the extracted pixel whose X coordinate value is one smaller than the current peak left end candidate pixel is larger than the Y coordinate value of the current peak left end candidate pixel is satisfied.
When this condition is satisfied, the extracted pixel whose X coordinate value is one smaller than the current peak left end candidate pixel is changed to the next peak left end candidate pixel, and the process of (4-1) is performed again. If this condition is not satisfied, the current peak left edge candidate pixel is set to the peak left edge pixel corresponding to the current peak vertex pixel (the peak vertex pixel set most recently).
(4-2) It is determined whether or not the condition that the Y coordinate value of the extracted pixel whose X coordinate value is one larger than the current peak right end candidate pixel is larger than the Y coordinate value of the current peak right end candidate pixel is satisfied.
When this condition is satisfied, the extracted pixel having an X coordinate value one larger than the current peak right end candidate pixel is changed to the next peak right end candidate pixel, and the process of (4-2) is performed again. If this condition is not satisfied, the current peak right edge candidate pixel is set to the peak right edge pixel corresponding to the current peak vertex pixel (the peak vertex pixel set most recently).

After the peak left end pixel and the peak right end pixel corresponding to the current peak vertex pixel are set by the processing of (4-1) and the processing of (4-2), the current peak left end pixel or the current peak right end pixel has already been changed. It is determined whether or not the pixel is set as a peak left end pixel or peak right end pixel corresponding to the peak apex pixel.
When the current peak leftmost pixel or current peak rightmost pixel is already set to the peak leftmost pixel or peak rightmost pixel corresponding to another peak vertex pixel, the current peak vertex pixel and the corresponding current peak leftmost pixel and current peak rightmost pixel Cancel the setting. When the current peak left edge pixel or the current peak right edge pixel is not set to the peak left edge pixel or peak right edge pixel corresponding to another peak vertex pixel, the current peak vertex pixel and the corresponding current peak left edge pixel and current peak right edge pixel The setting is left as it is without cancellation.
After canceling the setting of the current peak vertex pixel, the current peak left end pixel, and the current peak right end pixel or leaving them as they are, if there is an extracted pixel whose X coordinate value is one larger than the current target pixel, the current peak pixel If the extracted pixel whose X coordinate value is one larger than the current target pixel is changed by changing the extracted pixel whose X coordinate value is one larger to the next target pixel and the process of (2) is performed again, (5) Proceed to the process.

In the example shown in FIG. 9 (b), by treatment of (1) to (4), the pixel P ₂ is set to the peak apex pixels, pixel P ₅ and pixel as a peak leftmost pixel and peak rightmost pixel corresponding P ₆ are respectively set. Further, the pixel P ₇ is set to another peak apex pixels, pixel P ₈ and the pixel P ₉ are respectively set as a peak leftmost pixel and peak rightmost pixel corresponding thereto.

(5) Among the peak vertex pixels, the pixel with the smallest X coordinate value is set as the first pixel of interest.
After the process (5), the process proceeds to the process (6).

(6) The distance in the X direction between the peak left end pixel and the peak right end pixel corresponding to the target pixel (the X coordinate value of the peak right end pixel−the X coordinate value of the peak left end pixel) is a predetermined number of pixels (for example, an extraction target) It is determined whether or not the condition that the total number of pixels in the X direction of the two-dimensional image is (the number of 1/20 to 1/5) or less is satisfied.
When this condition is satisfied, the process proceeds to (7).
If this condition is not satisfied and there is a peak vertex pixel having an X coordinate value larger than that of the current pixel of interest, the peak vertex pixel having an X coordinate value larger than that of the current pixel of interest and the closest X coordinate value is determined as the next pixel of interest. The process (6) is performed again.
When this condition is not satisfied, if there is no peak vertex pixel having an X coordinate value larger than that of the current pixel of interest, a series of processing ends.

(7) The distance in the Y direction between the current target pixel and the peak left end pixel corresponding to the current target pixel (Y coordinate value of the peak left end pixel−Y coordinate value of the peak vertex pixel), or the current target pixel and the current target pixel Of the distances in the Y direction with the corresponding peak right end pixel (Y coordinate value of the peak right end pixel−Y coordinate value of the peak apex pixel), the shorter distance is the distance in the X direction between the peak left end pixel and the peak right end pixel. It is determined whether or not a condition that a predetermined multiple (for example, ½ to 2 times) or more of (X coordinate value of peak right end pixel−X coordinate value of peak left end pixel) is satisfied is satisfied.
When this condition is satisfied, the process proceeds to (8).
If this condition is not satisfied and there is a peak vertex pixel having an X coordinate value larger than that of the current pixel of interest, the peak vertex pixel having an X coordinate value larger than that of the current pixel of interest and the closest X coordinate value is determined as the next pixel of interest. The process (6) is performed again.
When this condition is not satisfied, if there is no peak vertex pixel having an X coordinate value larger than that of the current pixel of interest, a series of processing ends.

In the case of the example shown in FIG. 9B, the peak vertex pixel P ₂ and the corresponding peak left end pixel P ₅ and peak right end pixel P ₆ satisfy the conditions of (6) and (7). The peak vertex pixel P ₇ , and the corresponding peak left end pixel P ₈ and peak right end pixel P ₉ correspond to the distance between the peak vertex pixel P ₇ and the peak left end pixel P ₈ in the Y direction, and the peak vertex pixel P ₇ . distance in the Y direction between the peak rightmost pixel P ₉ is the 1/5 distance in the X direction between the peak leftmost pixel P ₈ and peak rightmost pixel P _9, a predetermined value (e.g., 1/2 to 2) times Therefore, the condition (7) is not satisfied.
Thus, only the sharp peak considered to be caused by the defect is selected according to the conditions (6) and (7), and the loose peak considered not to be caused by the defect is not selected.

(8) An expression representing a line segment connecting the peak left end pixel and the peak right end pixel corresponding to the current pixel of interest is calculated, and the pixels on the line segment are extracted to be re-extracted pixels. However, the line between two pixels M (x _p , y _q ) and N (x _p , y _q +1) located between the peak left end pixel and the peak right end pixel in the X direction and adjacent in the Y direction When the minute passes, the pixel N (x _p , y _q +1) is set as the re-extracted pixel. Among the extracted pixels extracted by the boundary extraction unit 1411, an extracted pixel having the same X coordinate value as that of the re-extracted pixel and having a Y coordinate value different from that of the re-extracted pixel is extracted as a pixel constituting the boundary line portion. Replace pixel with re-extracted pixel. In this way, the boundary portion obtained by replacing a part of the extracted pixels with the re-extracted pixels forms an original boundary line excluding the influence of the defect. As shown in FIG. 9 (e), the extracted pixel after replacement includes a dark portion corresponding to the boundary line portion distorted by the dent defect included in the original two-dimensional image data. It becomes possible to indicate the position of the dent defect.

Although the re-extraction unit 1412 performs re-extraction by the processes (1) to (8) above, the re-extraction method is not limited to this. For example, as another re-extraction method, a curve expressed by a function is fitted to the boundary line portion extracted by the boundary extraction unit 1411 to obtain a fitting curve (function curve), and then the fitting curve is calculated. A smoothed smoothing curve is obtained, and finally, a pixel in the two-dimensional image fitted to the smoothing curve may be used as an extraction pixel. Examples of functions used for fitting include n-order functions, Gaussian functions, Lorentz functions, Forked functions, and combinations of these functions. As a fitting evaluation method used for fitting, for example, the least square method can be used.

DESCRIPTION OF SYMBOLS 1 Image generation apparatus 11 Conveyance part 12 Light irradiation part 13 Imaging part 14 Information processing apparatus 21 Display part 100 Defect inspection apparatus 141 Inspection image data generation part 1411 Boundary extraction part 1412 Re-extraction part 1413 Synthesis | combination part

Claims

An image generation device that generates image data for inspecting a defect of a sheet-shaped molded body, the transport unit configured to transport the sheet-shaped molded body in the longitudinal direction of the sheet-shaped molded body,
A light source that includes a light source that extends linearly in the width direction of the sheet-like molded body, and that irradiates the sheet-like molded body with light by the light source;
An imaging unit that performs an imaging operation on the sheet-like molded body being conveyed to generate two-dimensional image data representing a two-dimensional image, and includes a bright part corresponding to the light source and the bright part in the two-dimensional image An imaging unit that performs multiple imaging operations on the sheet-like molded body at a position including a dark part having a lower brightness than the part;
An inspection image data generation unit that generates inspection image data from a plurality of two-dimensional image data generated by the imaging unit,
A boundary extraction unit that extracts a boundary part between the bright part and the dark part in each two-dimensional image represented by each two-dimensional image data;
The boundary line is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there are no sharp peaks appearing on the apparent boundary line. A re-extraction unit that extracts the pixels constituting the two-dimensional image data;
Synthesis that generates one-dimensional image data composed of pixels extracted by the re-extracting unit, and similarly generates a plurality of one-dimensional image data obtained from a plurality of two-dimensional image data to generate inspection image data. And
An inspection image data generation unit including:
An image generation apparatus comprising:
An image generation apparatus according to claim 1;
A display unit for displaying an image represented by the inspection image data generated by the inspection image data generation unit of the image generation device;
A defect inspection apparatus comprising:
A defect inspection method for inspecting defects in a sheet-like molded body,
In a state where the sheet-shaped molded body is conveyed in the longitudinal direction of the sheet-shaped molded body while irradiating the sheet-shaped molded body with light by a light source extending linearly in the width direction of the sheet-shaped molded body. An imaging step of performing an imaging operation on a molded body to generate two-dimensional image data representing a two-dimensional image, and the brightness of the bright part corresponding to the light source in the two-dimensional image is lower than that of the bright part An imaging step of performing an imaging operation a plurality of times on the sheet-like molded body so as to include a dark part; and
A boundary extraction step of extracting a boundary portion between the bright portion and the dark portion in each two-dimensional image represented by each two-dimensional image data generated in the imaging step;
The boundary line is connected to form an apparent boundary line, and the apparent boundary line is smoothed so that there are no sharp peaks appearing on the apparent boundary line. A re-extraction step of extracting pixels constituting the two-dimensional image data;
1-dimensional image data composed of the pixels extracted in the re-extraction step is generated, and a plurality of 1-dimensional image data obtained from a plurality of 2-dimensional image data is similarly combined to generate inspection image data. Process,
A display step of displaying an image represented by the inspection image data generated in the synthesis step;
Including defect inspection method.