WO2013021968A1 - Inspection method and inspection device for flaw in resin molded product - Google Patents

Abstract

Provided are an inspection method and an inspection device which are capable of objectively and quantitatively evaluating a flaw in a resin molded product used as an interior material or the like of a vehicle. An inspection method and an inspection device for a flaw in a resin molded product subjected to surface texturing. With a linear flaw having a gradient property formed by continuous change of a load in a given direction on a resin molded product as the subject of inspection, the inspection method comprises an irradiation step of irradiating the linear flaw with light, an image acquisition step of acquiring a microscopic image of the linear flaw, an image processing step of processing the microscopic image, and a determination step of determining the state of the linear flaw on the basis of the result of the image processing. The inspection device is provided with an irradiation means (11) for irradiating the linear flaw with light, an image acquisition means (14) for acquiring a microscopic image of the linear flaw, an image processing means (21) for processing the microscopic image, and a determination means (22) for determining the state of the linear flaw on the basis of the result of the processing.

Description

Method and apparatus for inspecting scratches in resin molded products

The present invention relates to an inspection method and an inspection device for a flaw in a resin molded product having a textured surface.

Resin molded products used for automobile interior materials such as dashboards are generally subjected to graining. Various effects are brought about by applying a texture to the resin molded product. For example, when a surface of a resin molded product is scratched, it is difficult to distinguish the wrinkles from the scratches even when viewed under natural light, and the scratches are not noticeable. Since the texture can be seen as a pattern and the design is improved, the resin molded product can be placed at a position where it is easily noticeable. Since wrinkles play a role of anti-slip, even when an object is placed on a resin molded product, the object is difficult to move and is stable. As a result of the progress of development, in recent years, there are a wide variety of grain shapes and the choices of users are increasing.

In selecting a resin molded product for use in automobile interior materials from among a plurality of candidates, the results of various tests and inspections conducted in advance are considered. For example, there is an inspection in which the surface of a resin molded product is scratched, and the ease of scratching and the difficulty of conspicuousness are compared. Specifically, using a metal member or the like having a sharp tip, multiple scratches of different degrees are applied, and light is applied to the periphery of the scratched part, and the appearance and state of the wound are checked with the naked eye or an appearance inspection device. Inspect. However, in the case of resin molded products that have been subjected to wrinkle processing, when irradiated with light, not only diffused light and reflected light from scratches but also diffused light and reflected light from wrinkles are received. It is hard to do. As a result, there is a possibility that the wrinkles may be mistaken as scratches, and there is a problem that the accuracy of the inspection is lowered.

2. Description of the Related Art Conventionally, in order to detect a foreign object, a flaw, or the like attached to a subject, a wound detection apparatus including an illumination unit that emits illumination light and an imaging unit that captures a subject illuminated by the illumination unit as a dark field image. (For example, see Patent Document 1).
According to Patent Document 1, it is supposed that a direction-dependent scratch can be detected in a short time with high accuracy.

Also, bright field image creation means, dark field image creation means, display means for displaying bright field images and dark field images, and display control for controlling to simultaneously display dark field images and bright field images on the display means There has been a defect inspection apparatus characterized in that it has a means (see, for example, Patent Document 2).
According to Patent Document 2, the bright field image and the dark field image of the inspection object are simultaneously displayed on the display device, so that the inspector compares the two images and there is a minute defect that cannot be displayed in the bright field image. It is said that it can be confirmed.

Japanese Patent Application Laid-Open No. 2005-127989 JP 2001-183301 A

However, the invention described in Patent Document 1 does not consider a subject whose surface has been subjected to graining, and therefore it is difficult to reliably distinguish between a grain and a flaw when a grain is present. Here, the scratches on the resin molded product subjected to the texture processing include gloss scratches, whitening scratches, and the like. In general, whitening scratches can be confirmed mainly in the dark field, and glossy scratches can be confirmed in the bright field. Therefore, even if the texture and the scratch can be distinguished by the invention described in Patent Document 1 for observing the dark field image, it is impossible to distinguish between the gloss scratch and the whitening scratch.

Even in the invention described in Patent Document 2, it is difficult to say that a wrinkle and a flaw can be reliably distinguished when a wrinkle is present because a subject whose surface has been wrinkled is not considered. Since the inspector visually compares the bright field image and the dark field image, the result varies depending on the ability of the inspector, the inspection environment, and the like, and the accuracy of the inspection is expected to be low.

Since it is difficult to mechanically inspect the surface of a subject that has undergone embossing, it is difficult to mechanically inspect the surface, and in most cases it is inspected visually. However, in the visual inspection, the result cannot be digitized, and the result varies depending on the inspector. For example, when inspecting, it is difficult to make the angle at which the inspector faces the subject constant. Therefore, it is not always possible to derive an accurate inspection result.

Thus, at present, an inspection method and an inspection apparatus for accurately inspecting the state of scratches on a resin molded product whose surface has been subjected to embossing have not been developed yet. The present invention has been made in view of the above-described problems, and is used for an interior material of a car by paying attention to the property of light received from a wrinkle and a flaw when a subject is irradiated with light. It is an object of the present invention to provide an inspection method and an inspection apparatus that can objectively and quantitatively evaluate a scratch in a resin molded product.

The characteristic configuration of the method for inspecting scratches in the resin molded product according to the present invention for solving the above problems is
A method for inspecting a flaw in a resin molded product having a textured surface,
With respect to the resin molded product, it is intended to inspect a linear wound having an inclination formed by a load continuously changing along a certain direction,
An irradiation step of irradiating the line wound with light;
An image acquisition step of acquiring a microscopic image of the flaw;
An image processing step for processing the microscope image;
A determination step of determining the state of the flaw based on an image processing result;
It is to include.

As described in the above problem, the conventional technology cannot accurately and quantitatively inspect the state of scratches on the resin molded product that has been subjected to embossing. This is because it was not assumed that the resin molded product in which the wrinkles exist was inspected. That is, in the prior art, there has been no technical idea for distinguishing between wrinkles and scratches.
Even if an attempt is made to inspect a scratch on a resin molded product that has been subjected to embossing, there are various types of injuries, and embossing is an obstacle to distinguish these objectively and quantitatively. Therefore, accurate inspection is difficult.
In this respect, the method for inspecting a flaw in a resin molded product of this configuration is a method for inspecting a flaw in a resin molded product having a textured surface, and a load is continuously applied to the resin molded product along a certain direction. Inspecting a graded wound that is formed by a change in the target, an irradiation process for irradiating the wound with light, an image obtaining process for obtaining a microscope image of the wound, and a microscope image Image processing step, and a determination step of determining the state of the flaw based on the image processing result, so that the presence or absence or state of the flaw of the resin-molded product subjected to the texture processing is accurately determined The inspection can be performed, and the inspection result can be quantified. As a result, it is possible to objectively and quantitatively evaluate the state of the flaw.

In the method for inspecting scratches in the resin molded product according to the present invention,
In the image acquisition step, a bright-field image and a dark-field image of the flaw are acquired,
In the image processing step, on the basis of the bright field image and the dark field image, a required adjustment area and an adjustment unnecessary area are set in the microscope image, and the bright field image and the dark field image are set for the adjustment area. Generating a combined composite image, selecting the bright field image or the dark field image for the adjustment unnecessary region, binarizing the gradation of the composite image and the image of the adjustment unnecessary region according to the same handling rule,
In the determination step, it is preferable to determine the presence or absence of whitening scratches that are the state of the line wound based on the image processing result obtained in the image processing step.

The method for inspecting a scratch in a resin molded product according to the present invention acquires a bright-field image and a dark-field image of the flaw in the image acquisition step. In the field-of-view image, gloss scratches, whitening scratches, and wrinkles can be recognized. In the image processing step, areas that require adjustment and areas that do not need to be adjusted are set in the microscope image based on the bright-field and dark-field images, so it is possible to exclude areas that are surely determined when determining the presence or absence of whitening scratches. Thus, a quick and simple test result can be derived. Generates a composite image that combines the bright-field image and dark-field image for the adjustment-needed region, and selects the bright-field image or dark-field image for the adjustment-unnecessary region, and has the same gradation in the composite image and the image in the adjustment-unnecessary region Since binarization is performed according to the handling rules, only whitening scratches are selectively or relatively emphasized. In the determination step, based on the image processing result obtained in the image processing step, it is possible to objectively and quantitatively evaluate the presence or state of the whitening wound in order to determine the presence or absence of the whitening wound that is the state of the line wound. It becomes possible.

In the method for inspecting scratches in the resin molded product according to the present invention,
For the resin molded product before the line flaw is formed, further execute a preparatory step of acquiring a bright field reference image and a dark field reference image in advance,
In the image processing step, it is preferable that the bright field reference image and the dark field reference image are further used when setting the adjustment required area and the adjustment unnecessary area.

The method for inspecting a scratch in a resin molded product according to the present invention further performs a preparatory step for acquiring a bright-field reference image and a dark-field reference image in advance for a resin molded product before a linear scar is formed. The embossing can be recognized in the bright field reference image and dark field reference image of the resin molded product that does not exist. In the image processing step, since the bright field reference image and the dark field reference image are used when setting the adjustment required area and the adjustment unnecessary area, an area that is surely determined when determining the presence or absence of whitening damage, that is, whitening damage In addition, it is possible to accurately exclude areas where it is difficult to misidentify glossy scratches and wrinkles, and a more accurate inspection result can be derived.

In the method for inspecting scratches in the resin molded product according to the present invention,
The adjustment-necessary area is a first adjustment-necessary area in which a comparison result of gradations of the bright field reference image and the bright field image is different from a comparison result of gradations of the dark field reference image and the dark field image. It is preferable to include a region.

In the method for inspecting a scratch in a resin molded product according to the present invention, the adjustment area needs to be compared with the gradation comparison result of the bright field reference image and the bright field image, and the gradation comparison result of the dark field reference image and the dark field image. Since the first adjustment area, which is a different area, is included, it is possible to improve the determination accuracy of whitening scratches that can be confirmed mainly in the dark field, and lead to a clearer inspection result. As a result, it is possible to more objectively and quantitatively evaluate the presence or state of whitening damage.

In the method for inspecting scratches in the resin molded product according to the present invention,
The adjustment-necessary region is a second adjustment-necessary region in which a gradation comparison result between the bright-field reference image and the dark-field reference image is different from a gradation comparison result between the bright-field image and the dark-field image. It is preferable to include a region.

In the method for inspecting a scratch in a resin molded product according to the present invention, the adjustment area needs to be compared with the gradation comparison result of the bright-field reference image and the dark-field reference image, and the gradation comparison result of the bright-field image and the dark-field image. Since the second adjustment area, which is a different area, is included, it is possible to clarify the area in which the line flaw including the glossy flaw and the whitening flaw exists and lead to a more accurate inspection result. As a result, it is possible to more objectively and quantitatively evaluate the presence or state of whitening damage.

In the method for inspecting scratches in the resin molded product according to the present invention,
The adjustment required area is preferably the entire area of the microscope image.

In the method for inspecting scratches on the resin molded product according to the present invention, the adjustment area is the entire area of the microscope image, so even if it is difficult to distinguish between the adjustment area and the adjustment unnecessary area, the adjustment is made uniformly. By doing so, reliable test results can be derived. As a result, it is possible to objectively and quantitatively evaluate the presence and state of whitening scratches.

In the method for inspecting scratches in the resin molded product according to the present invention,
When the said damage is not confirmed by the said determination process, it is preferable to perform the light adjustment process which adjusts the light irradiated at the said irradiation process.

The method for inspecting a scratch in a resin molded product according to the present invention performs a light adjustment step of adjusting the light irradiated in the irradiation step when the scratch is not confirmed in the determination step. Can be obtained, and an accurate inspection result can be derived. As a result, it is possible to objectively and quantitatively evaluate the presence and state of whitening scratches.

In the method for inspecting scratches in the resin molded product according to the present invention,
In the image acquisition step, a bright-field image and a dark-field image of the flaw are acquired,
In the image processing step, on the basis of the bright field image and the dark field image, a required adjustment area and an adjustment unnecessary area are set in the microscope image, and the bright field image and the dark field image are set for the adjustment area. After generating the combined composite image, a difference image is generated by subtracting the composite image from the bright field image or the dark field image, and the bright field image or the dark field image is selected for the adjustment unnecessary region, The gradation of the difference image and the image of the adjustment unnecessary area is binarized according to the same handling rule,
In the determination step, it is preferable to determine the presence or absence of a glossy flaw that is the state of the line flaw based on the image processing result obtained in the image processing step.

The method for inspecting a scratch in a resin molded product according to the present invention acquires a bright-field image and a dark-field image of the flaw in the image acquisition step. In the field-of-view image, gloss scratches, whitening scratches, and wrinkles can be recognized. In the image processing process, areas that require adjustment and areas that do not require adjustment are set in the microscopic image based on the bright-field and dark-field images, so it is possible to exclude areas that are surely determined when determining the presence or absence of gloss flaws. Thus, a quick and simple test result can be derived. After generating a composite image that combines the bright-field image and the dark-field image for the adjustment-necessary area, a difference image is generated by subtracting the composite image from the bright-field image or the dark-field image, and the bright-field image or dark-field for the adjustment-free area. Since the visual field image is selected and the gradation of the difference image and the image of the adjustment unnecessary region is binarized according to the same handling rule, only the glossy flaw is selectively or relatively emphasized. In the determination step, based on the image processing result obtained in the image processing step, it is possible to objectively and quantitatively evaluate the presence or state of the gloss flaw in order to determine the presence or absence of the gloss flaw that is the state of the line flaw. It becomes possible.

In order to solve the above problems, the characteristic configuration of the scratch inspection apparatus in the resin molded product according to the present invention is
A device for inspecting scratches on a resin molded product having a textured surface,
With respect to the resin molded product, it is intended to inspect a linear wound having an inclination formed by a load continuously changing along a certain direction,
Irradiating means for irradiating the line wound with light;
An image acquisition means for acquiring a microscopic image of the flaw;
Image processing means for processing the microscope image;
Determining means for determining the state of the flaw based on an image processing result;
It is in the point with.

The inspection apparatus for scratches in a resin molded product according to the present invention is an inspection apparatus for scratches in a resin molded product whose surface is textured, and a load is continuously applied to the resin molded product along a certain direction. It is intended to inspect graded flaws formed by change, irradiation means for irradiating light to the flaws, image acquisition means for obtaining a microscope image of the flaws, and processing the microscope images Image processing means for determining, and determination means for determining the state of the flaw based on the image processing result;
Therefore, it is possible to accurately inspect the presence or state of a line flaw of a resin molded product that has been subjected to embossing, and to digitize the inspection result. As a result, it is possible to objectively and quantitatively evaluate the state of the flaw.

It is the schematic of the scratch apparatus used with the test | inspection method which concerns on this invention. It is the schematic of the inspection apparatus which concerns on this invention. It is each enlarged view of (a) circular grain, (b) leather grain, and (c) pear texture grain. It is explanatory drawing regarding the setting method of the adjustment area | region / adjustment unnecessary area | region in 2nd embodiment and 3rd embodiment. (A) a bright-field image of (i) a resin-molded product before making a flaw, and (ii) a glossy flaw, (iii) a glossy and whitening flaw, and (iv) a resin-molded product with a whitening flaw, It is the figure which showed the binarized image of (b) dark field image, (c) the composite image of a bright field image and a dark field image, and (d) the composite image. FIG. 6 is an enlarged view of an approximately 0.2 mm square region surrounded by a square in each image shown in FIG. 5, and is represented by a gray scale of 256 gradations for each pixel. FIG. 7 is a gradation diagram showing gradation values for each pixel in the 256 gradation gray scale image shown in FIG. 6. 8 (i) and (ii) show the gradation values based on the 256 gradation gray scale images of FIGS. 6 (i) and (ii) and the gradation diagrams of FIGS. 7 (i) and (ii). It is the figure which showed the histogram which took the horizontal axis and took the number of pixels on the vertical axis. FIGS. 9 (iii) and (iv) show the gradation values based on the 256 gradation gray scale images of FIGS. 6 (iii) and (iv) and the gradation diagrams of FIGS. 7 (iii) and (iv). It is the figure which showed the histogram which took the horizontal axis and took the number of pixels on the vertical axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a method for inspecting scratches in a resin molded product and an inspection apparatus according to the present invention will be described in detail below with reference to FIGS. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

FIG. 1 is a schematic view of a scratch device used in the inspection method according to the present invention. FIG. 2 is a schematic view of an inspection apparatus according to the present invention.

The present invention relates to an inspection method and an inspection device for a flaw in a resin molded product whose surface is textured, and is formed by continuously changing the load along a certain direction with respect to the resin molded product. An inspection target is a line scar (scratch scratch) having an inclination. As the material of the resin molded product, polypropylene (PP), polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polyacetal (polyacetal) used as automobile interior materials are used. POM) and polylactic acid resin (PL). FIG. 3 shows an example of a resin molded product having a textured surface. (A) is what is called a circular texture which is one of geometric textures, (b) is a leather texture, and (c) is a non-geometric texture called a satin texture. “The load changes continuously” means that the load continuously increases or decreases. Inclined flaws formed by continuously changing the load are generally formed by increasing the load continuously at a constant rate as described later. Not limited. For example, a case where the load increases gradually or a case where the load increase rate gradually decreases is included. Moreover, it is sufficient that the load is in a tendency to increase or decrease when the entire load application section is viewed, and a section of a constant load may be included in the load application section. By continuously changing the load along a certain direction, a flaw having a gradient in which depth, width, or both gradually change along the length direction is formed. In addition, when the line scar having such a gradient is irradiated with light, the brightness of the reflected light or diffused light may gradually change. When creating a line wound, the scratch device shown in FIG. 1 is used, and when inspecting the line wound, an inspection apparatus shown in FIG. 2 is used.

<Scratch device>
The scratch device 5 mainly includes a chip 1 that scratches a sample (resin molded product) S, a head 2 that houses the chip 1 so that it can be inserted and removed, a rail 3 that slides the head 2, and a protruding amount of the chip 1 and the head 2 It is comprised from the control part 4 (for example, computer) which controls the movement distance. A stainless sphere 1a having a diameter of about 1 mm is attached to the tip of the chip 1. In order to create an inclined line wound (scratch operation), the head 2 is slid along the rail 3 while the tip of the chip 1 is in contact with the sample S, and the chip 1 is gradually moved from the head 2. By projecting, the load applied to the chip 1 is gradually increased. The inspector can confirm the distance at which the scratch operation is performed and the load applied to the chip 1 by looking at the graph displayed on the screen of the control unit 4. In this embodiment, when the distance at which the scratch operation is performed is 100 mm, the load increases approximately linearly from 0 to 50N. The relationship between the scratch distance and the load can be changed according to the state of the sample S, the inspection conditions, and the like. Since the sphere 1a is attached to the tip of the chip 1, the width of the scratch in plan view increases to a size corresponding to the diameter of the sphere 1a as the chip 1 moves, that is, as the load increases. To do. In order to make the width of the scratch in plan view constant, it is possible to use a cylindrical metal member instead of the sphere 1a. In this case, the influence of the change in reflected light due to the increase in the scratch width can be suppressed.

<Inspection device>
The inspection apparatus 100 includes an optical microscope 10 and a calculation unit 20. The optical microscope 10 includes a light source 11 that is an irradiation unit, a half mirror 12 that reflects light from the light source 11 and transmits light transmitted from the sample S, an objective lens 13 that directly observes the sample S, and an image acquisition unit. An imaging unit 14 is provided. The optical microscope 10 further includes a regulator 15 that is a light adjusting unit. The regulator 15 adjusts the intensity of light emitted from the light source 11, the position of the light source 11, the position and number of lenses (not shown), the aperture of the objective lens 13, and the like. By operating the regulator 15, for example, when the incident angle of light with respect to the sample S is adjusted to 0 °, a bright field is obtained at a position where the light receiving angle from the sample S is 0 °. When the incident angle of light with respect to the sample S is adjusted to 45 °, a dark field can be obtained at a position where the light receiving angle from the sample S is 0 °. Here, the bright field is a field when the reflected light from the sample S is received, and the dark field is a field when the diffused light from the sample S is received. The imaging unit 14 includes an imaging element 14a such as a CCD. The imaging device 14a acquires light transmitted from the sample S as a bright field image and a dark field image. The computing unit 20 is usually a computer and includes an image processing unit 21 and a determination unit 22. The image processing unit 21 and the determination unit 22 have the functions of a central processing unit (CPU) of a computer. Further, the image processing means 21 and the determination means 22 may be realized on computer software.

<Inspection method>
In the inspection method of the present invention, an irradiation process, an image acquisition process, an image processing process, and a determination process are mainly executed. Furthermore, a preparation process and a light adjustment process can be performed as needed. Hereinafter, each step will be described.

<Irradiation process>
The irradiation process is executed using the light source 11 built in the optical microscope 10. Examples of the light source 11 include an LED, a sodium lamp, and a halogen lamp. The regulator 15 which is a light adjusting means is operated to focus the light from the light source 11 with a lens (not shown), and the sample S arranged on the stage 16 is irradiated with light through the half mirror 12. The light irradiation angle (incident angle) can be switched in the objective lens 13. As shown in FIG. 2, light having a small irradiation angle is irradiated as linear light, and light having a large irradiation angle is irradiated as annular light. In the present embodiment, as the sample S to be irradiated, a resin molded product made of polypropylene subjected to the satin finish shown in FIG. 3C is used. First, an irradiation process is performed on the sample S before the line scar is formed (<preparation process> described later).

<Image acquisition process>
The image acquisition process is executed by the imaging unit 14 that is an image acquisition unit connected to the lens barrel 17 of the optical microscope 10. The imaging unit 14 can use a digital camera. The light transmitted from the sample S passes through the objective lens 13 and the half mirror 12 and forms an image on the image sensor 14 a of the image capturing unit 14.
As described above, in the irradiation process, when the objective lens 13 is operated and the irradiation light is refracted, for example, by 45 ° with respect to the optical axis L and irradiated on the surface of the sample S, the image acquisition process includes: A dark field image of the sample S can be acquired. On the other hand, when the irradiation light is irradiated onto the surface of the sample S at an irradiation angle of 0 ° with respect to the optical axis L, a bright field image of the sample S can be acquired in the image acquisition step.

<Preparation process>
In the present invention, a bright-field image is obtained for the microscopic image of the sample S before the flaw is formed by the method described in <Irradiation step> and <Image acquisition step> as necessary for preparation of the inspection. It is preferable to acquire a dark field image (which is defined as a bright field reference image and a dark field reference image). By performing the preparatory process, it is possible to recognize only the wrinkles in the bright field reference image and the dark field reference image of the sample S where no flaws exist, so that in the subsequent <image processing step> Can be more accurately distinguished.

<Creating wounds>
The sample S subjected to the above-described satin finish texture processing is used to scratch the sloped line by changing the load continuously along a certain direction using the scratch device 5. The scratch can be created in a direction perpendicular to the direction in which the wrinkle flows by selecting a portion that is likely to be damaged in the sample S subjected to the wrinkle processing, that is, a portion having a large wrinkle unevenness. preferable.
In order to create a line flaw on the textured sample S, if a certain distance is moved while applying a load to the chip 1, a glossy region (glossy flaw) is generated in the initial stage. The gloss scratch is a state in which the surface of the object is leveled and there is almost no difference from the peripheral part, but gloss due to reflected light can be confirmed. If the movement of the chip 1 is continued as it is, a microscopic destruction region appears on the surface of the sample S in the middle stage. For example, when the material of the sample S is polypropylene, a scaly scar with a pattern like a periodic wrinkle appears, and when it is polycarbonate, a microcrack appears. Some gloss flaws are also found in the microscopic destruction region, but the gloss gradually decreases. As the microscopic destruction region further progresses, a sudden whitening occurs. This whitened portion is called a whitening wound. The whitening scratches appear as white as a result of the surface of the sample S being roughened by the plastic deformation of the material due to the chip 1 being rubbed against the sample S and the light being diffused. When the chip 1 continues to move, the surface structure of the sample S is broken macroscopically and cutting flaws appear in the later stage. Since the surface of the cutting flaw is greatly roughened, it looks clearly white with the naked eye.

<Acquisition of bright field image and dark field image>
The sample S with the line scar is placed on the stage 16 of the optical microscope 10, and a bright field image and a dark field image are acquired by the method described in the above <irradiation step> and <image acquisition step>.
In this embodiment, images before and after the formation of flaws are acquired for the same sample S. However, two samples S are prepared, and flaws are formed only on one sample S, both It is also possible to acquire and inspect the image.
A bright-field image and a dark-field image can recognize glossy scratches, whitening scratches, and wrinkles, but the degree of recognition in each image is different. That is, in the bright field image, the reflected light is dominant, so that the gloss flaw is mainly recognized. On the other hand, in the dark field image, diffused light is dominant, and thus whitening scratches are mainly recognized. However, since some reflected light is received, glossy scratches may be recognized. The wrinkles are recognized in the bright field image and the dark field image.

<Image processing process>
The image processing step is executed by the calculation unit 20. In the image processing step, first, the adjustment required area and the adjustment unnecessary area are set in the microscope image acquired by the imaging unit 14.
The area that needs to be adjusted is an area that may be affected by the scratch operation that is not clearly affected (in other words, the state has changed substantially from before the scratch operation. A region that may not be) and is at least part of a microscopic image. The adjustment unnecessary area is an area that is reliably affected by the scratch operation and an area that is not reliably affected. Hereinafter, setting rules for the adjustment required area and the adjustment unnecessary area will be described as embodiments.

[First embodiment]
In the present embodiment, the adjustment required area and the adjustment unnecessary area are set based on the bright field image and the dark field image. For example, a bright-field image and a dark-field image are represented by a gray scale of 256 gradations for each pixel, and a numerical value difference of the gradation of each pixel at the corresponding position is taken. A region where the difference value is not substantially zero is determined as a region requiring adjustment, and the other regions are determined as regions that do not require adjustment. “Substantially not zero” can be defined as, for example, when the absolute value of the difference exceeds 20 or when the difference exceeds 10% of 256 gradations. As a result, it is possible to exclude a region that is surely determined in determining the presence or absence of whitening scratches, and a quick and simple inspection result can be derived.
Next, the adjustment required area and the adjustment unnecessary area can be set in the microscope image based on the bright field reference image, the dark field reference image, the bright field image, and the dark field image. FIG. 4 is an explanatory diagram regarding a setting method of the adjustment required area / adjustment unnecessary area in the second embodiment and the third embodiment.

[Second Embodiment]
In the present embodiment, the adjustment area is a first adjustment area in which the gradation comparison result of the bright field reference image and the bright field image is different from the gradation comparison result of the dark field reference image and the dark field image. including. The gradation comparison result is a result of representing an image with a gray scale of 256 gradations for each pixel and comparing the numerical values of the gradations of the pixels at the corresponding positions. For example, an area where the difference between the numerical values of the gradations of the bright-field reference image and the bright-field image and the numerical value of the gradations of the dark-field reference image and the dark-field image are not substantially the same as the first adjustment area To do. “Substantially the same” can be defined as a case where the error is within ± 10% or a case where the absolute value of the error is within 20 based on the gradation of the bright field image. Specifically, first, a difference (BA) between the bright field reference image (A) and the bright field image (B) is obtained, and the dark field reference image (C) and the dark field image (D) are obtained. Take the difference (DC). Next, a logical operation between the difference (BA) and the difference (DC) is performed. An exclusive OR (XOR) area obtained by this logical operation is determined as the first adjustment area. By setting the first adjustment area, it is possible to improve the accuracy of whitening damage determination that can be confirmed mainly in the dark field. In other words, it is possible to accurately exclude areas that are reliably judged in determining the presence or absence of whitening flaws, that is, areas that are difficult to misidentify whitening flaws, glossy flaws, and wrinkles, leading to more accurate inspection results. I can do it.

[Third embodiment]
In the present embodiment, the adjustment required area is a second adjustment area in which the gradation comparison result of the bright field reference image and the dark field reference image is different from the gradation comparison result of the bright field image and the dark field image. including. For example, an area where the difference between the numerical values of the gradations of the bright-field reference image and the dark-field reference image and the numerical value of the gradations of the bright-field image and the dark-field image are not substantially the same as the second adjustment area To do. The meaning of “substantially the same” is the same as in the second embodiment described above. Specifically, first, a difference (CA) between the bright field reference image (A) and the dark field reference image (C) is obtained, and the bright field image (B) and the dark field image (D) are obtained. The difference (DB) is taken. Next, a logical operation between the difference (CA) and the difference (DB) is performed. The exclusive OR (XOR) area obtained by this logical operation is determined as the second adjustment area. By setting the second adjustment area, it is possible to clarify the area where the line flaw including the gloss flaw and the whitening flaw is present, so that a more accurate inspection result can be derived. As a result, it is possible to more objectively and quantitatively evaluate the presence or state of whitening damage.

[Fourth embodiment]
The adjustment required area may be an area that includes both the first adjustment area and the second adjustment area described in the second embodiment, the third embodiment, and FIG. In this case, it is possible to clarify the region where the lineage flaws including the gloss flaws and the whitening flaws exist while improving the judgment accuracy of the whitening flaws that can be confirmed mainly in the dark field. Can lead.

[Adjustment unnecessary area setting]
When the adjustment required area and the adjustment unnecessary area are set in the microscope image based on the bright field reference image, the dark field reference image, the bright field image, and the dark field image, the adjustment unnecessary area includes the bright field reference image and the bright field image. The comparison result of the gray scale and the comparison result of the dark field reference image and the dark field image are substantially the same, and the comparison result of the bright field reference image and the dark field reference image. This is a region where the gradation comparison results of the bright field image and the dark field image are substantially the same. These areas have no gradation change in each image before and after the scratch operation, and are not reliably affected by the scratch operation, or substantially the same gradation in each image before and after the scratch operation. It is expected that this is a case that has a change and is reliably influenced by the scratch operation. Therefore, these areas are adjustment unnecessary areas. Specifically, as shown in FIG. 4, a logical sum (AND) area obtained by a logical operation is determined as an adjustment unnecessary area.

In this way, by setting the adjustment required area and the adjustment unnecessary area in the microscopic image, it is possible to exclude the adjustment unnecessary area which is a reliable area when determining the presence or absence of whitening scratches, and efficiently inspecting. I can do it. Since operations such as generation of a composite image, which will be described later, are performed not on the entire image but only on a necessary area, a quick and accurate inspection result can be derived.
Next, in the image processing step, a composite image that combines the bright-field image and the dark-field image is generated for the adjustment required area. Specifically, a gray scale is created by the average value of the gradation of each pixel of the bright field image and the dark field image. Here, the average value may be a general arithmetic average or a weighted average. By synthesizing the images, there is an effect that the difference in gradation in each image is canceled out for glossy scratches and wrinkles. As a result, whitening scratches are selectively or relatively emphasized in the composite image, and can be reliably recognized.

In some cases, it is preferable that the adjustment area is the entire area of the microscope image. When it is difficult to distinguish between the adjustment required area and the adjustment unnecessary area, for example, when the difference in the numerical values of the gradations of the bright field image and the dark field image is not substantially the same in all areas, the bright field reference image and the bright field image The difference between the numerical values of the gradation and the numerical values of the dark field reference image and the dark field image are not substantially the same in all regions, and the gradations of the bright field reference image and the dark field reference image When the difference between the numerical values and the difference between the numerical values of the gradations of the bright field image and the dark field image are not substantially the same in the entire region, the adjustment required region is the entire region of the microscope image. Even when it is troublesome to discriminate between the adjustment necessary area and the adjustment unnecessary area, the entire area of the microscope image can be regarded as the adjustment area and the inspection can be performed. Even in such a case, an accurate inspection result can be derived by generating a composite image in which the bright field image and the dark field image are combined for the entire region of the microscope image. As a result, it is possible to objectively and quantitatively evaluate the presence and state of whitening scratches.

For the adjustment unnecessary region, a bright field image or a dark field image is selected. In the adjustment unnecessary region, since the gradation is substantially the same in the bright-field image and the dark-field image, any image can be selected. Since whitening scratches are mainly recognized in the dark field image, it is preferable to select the dark field image. As a result, whitening scars are selectively or relatively emphasized in the image.
In the image processing step, finally, the gradation of the composite image and the image of the adjustment unnecessary area is binarized according to the same handling rule. That is, a threshold value in 256 gradations is determined, and when it is larger than the threshold value, it is white, and when it is smaller than the threshold value, it is black. The threshold value is a value that can change depending on the type of grain formed on the sample S, the coloring state of the sample S, the inspection environment, and the like. For example, in a composite image of a region that surely includes whitening flaws, the threshold value is set to 110 in consideration of the pixel value of the portion corresponding to the whitening flaws, and if the pixel value is 110 or more, it is regarded as a whitening flaw and is less than 110 If so, it can be regarded as a glossy flaw or grain.

<Judgment process>
The determination step is executed by the calculation unit 20 and determines the presence or absence of whitening scratches, which are the state of line scars, based on the result of the image processing step. Specifically, a white area in the binarized image is determined as an area where a whitening defect exists. As a result, it is possible to reliably recognize whitening scratches and to objectively and quantitatively evaluate the presence and state of whitening scratches. As a result, it is possible to determine a position where a whitening scratch starts in a linear scratch having a slope formed by the load continuously changing along a certain direction.

<Light adjustment process>
In the determination step, when no whitening damage is confirmed, it is possible to adjust the light irradiated in the irradiation step by the regulator 15 (light adjustment step). The light adjustment step includes adjusting light irradiation angle (incident angle), intensity, color tone, wavelength, coherency, and the like. By executing the light adjustment step, it is possible to reliably acquire a microscopic image of a flaw, so that a quick and accurate inspection result can be derived. As a result, it is possible to objectively and quantitatively evaluate the presence and state of whitening scratches.

[Image processing for inspection of gloss scratches]
In the above-described embodiment, the image processing process for improving the inspection accuracy of glossy scratches has been mainly described. However, in the present invention, it is possible in principle to improve the inspection accuracy of glossy scratches. That is, when it is desired to emphasize the gloss flaw, the next image processing step may be executed. First, a composite image that combines a bright-field image and a dark-field image is generated for a region that needs adjustment. Similar to the above embodiment, the composite image is obtained, for example, by creating a gray scale based on the average value of the gradation of each pixel of the bright field image and the dark field image. Here, the bright-field image is an image in which gloss flaws are mainly recognized, the dark-field image is an image in which whitening flaws and some gloss flaws are recognized, and the composite image has selective or relative whitening flaws. The image is emphasized. Therefore, in consideration of the characteristics of these images, a difference image is generated by subtracting the composite image from the bright field image or the dark field image. The obtained difference image is an image obtained by subtracting the elements of whitening scratches from a state where glossy scratches and whitening scratches are mixed. For this reason, the difference image results in an image in which gloss flaws are selectively or relatively emphasized. As described above, if the difference image is used, it is possible to reliably recognize the gloss flaw.

Next, an embodiment relating to a method and an inspection device for scratches in the resin molded product of the present invention will be described. In this example, a bright-field image and a dark-field image of a resin molded product with a line flaw are acquired, and the entire area of the inspection target area (an area of about 0.2 mm square surrounded by a square to be described later) needs to be adjusted. Considering the region, a composite image of both images was created. The bright-field reference image and dark-field reference image regarding the resin molded product before the line flaw is formed are not used.

Specifically, a scratch device (in accordance with SCRATCH TESTER (manufactured by Kato Tech Co., Ltd.), ISO19252 (ASTM D7027-05)) is applied to a resin molded product made of polypropylene subjected to a satin finish as shown in FIG. 3 (c). Used to create graded scratches by continuously increasing the load along a certain direction. Then, using an inspection device (an image acquisition system equipped with BX51 made by Olympus as an optical microscope), the microscopic image of the resin molded product with a line wound is in the initial stage, middle stage, and late stage of the scratch operation. Three corresponding images were acquired. The three images are shown as three regions surrounded by a rectangle in the entire image of the scratch in FIG. Each part is selected from an area where (ii) only glossy scratches, (iii) only glossy scratches and whitening scratches, and (iv) only whitening scratches from the upstream side along the scratch direction arrow. did. FIGS. 5 (ii) to (iv) show (a) a bright-field image, (b) a dark-field image, and (c) a bright-field image and a dark-field image at each position of the resin molded product with a line scar. A composite image and (d) a binary image of the composite image are shown. The binarized image will be described later.

FIGS. 6 (ii) to (iv) show an enlarged area of about 0.2 mm square surrounded by a square in each image shown in FIGS. 5 (ii) to (iv), and a gray scale of 256 gradations for each pixel. FIG. FIG. 5 (iii) shows a region where glossy scratches and whitening scratches coexist, but the area of about 0.2 mm square surrounded by a square contains only glossy scratches for the convenience of data. Wounds are not included. FIGS. 7 (ii) to (iv) are gradation diagrams in which gradation values are described for each pixel in the 256 gradation gray scale image shown in FIG. 1 corresponds to black, and 256 corresponds to white. Therefore, the smaller the value, the lower the brightness and the closer to black, and the higher the value, the lightness increases and approaches white. An appropriate threshold value is determined from the 256 gradation gray scale image of FIG. 6 and the gradation diagram of FIG. In this example, the binarized image shown in FIG. 5D was obtained by setting the gradation exceeding 115 where whitening damage was recognized (that is, 116th out of 256 gradations) as a threshold value. (Ii) in FIG. 8 and (iii) to (iv) in FIG. 9 are based on the 256 gradation gray scale image in FIG. 6 and the gradation diagram in FIG. It is the figure which showed the histogram which took the number on the vertical axis | shaft. This histogram shows the distribution of the numerical values of the gradation in each area of the 0.2 mm square.
In the present invention, gradation is shown by selecting three places (initial stage, middle stage, and late stage) of the line scar, but it is preferable to sequentially acquire each image for the entire line wound. As a result of grasping the gradation of the entire flaw, it is possible to objectively determine the position where the whitening flaw starts.

From the binary image shown in FIG. 5D, it is clear that as the scratch distance increases, the proportion of whitening scratches in the entire image increases. 6 and 7, it can be seen that the image of the whitening scratch has a high brightness, and the image of the gloss scratch has a lower brightness than the whitening scratch. Comparing FIG. 8 (ii) and FIG. 9 (iii), even if the same scratches are present, FIG. 9 (iii) shows that the histogram of the composite image is shifted to the higher brightness side than FIG. 8 (ii). I understand that.
8 (ii), 9 (iii), and (iv), the maximum value, minimum value, and average value of gradation values for each pixel are also shown. 8 (ii) and 9 (iii), there is almost no difference between the average value of the bright field image and the average value of the dark field image, but the average value of the bright field image of FIG. 9 (iv) is 116, the average value of the dark field image was 143, and the difference between them was 27. From this, it can be seen that in the region with whitening damage, the difference in gradation between the bright field image and the dark field image is large.

In FIG. 9 (iii), when comparing a bright field image and a dark field image, a relatively bright part in the bright field image is a relatively dark part in the dark field image, and the two are just reversed. Can be read. Further, when the maximum value and the minimum value in each image of FIG. 9 (iii) are compared, the difference is 96 from the maximum value = 142 and the minimum value = 46 in the bright field image, and the maximum value in the dark field image. = 116, minimum value = 57, the difference is 59. On the other hand, in the composite image, the difference is 36 because the maximum value = 99 and the minimum value = 63. That is, the histogram distribution of the composite image is smaller than the histogram distribution of the bright field image and the dark field image. From this, it was found that when the dark-field image and the bright-field image are synthesized, the gradation of the glossy flaws in each image is averaged and canceled out, so that the glossy flaws are not noticeable in the synthesized image. . That is, the influence of the gloss flaw on the dark field image can be reduced by the bright field image. As a result, whitening scratches are selectively or relatively emphasized in the composite image, and can be reliably recognized.

<Reference example>
As a reference, a bright-field image and a dark-field image (that is, a bright-field reference image and a dark-field reference image) of a resin molded product before a line scar was obtained, and a composite image was created by combining both images. FIG. 5 (i) shows (a) a bright-field image (bright-field reference image), (b) a dark-field image (dark-field reference image), and (c) a bright-field image in a resin-molded product before making a line scar. A composite image of (bright-field reference image) and a dark-field image (dark-field reference image), and (d) a binary image of the composite image are shown. FIG. 6 (i) is an enlarged view of an area of about 0.2 mm square surrounded by a square in each image shown in FIG. 5 (i) and is represented by a gray scale of 256 gradations for each pixel. FIG. 7 (i) is a gradation diagram in which numerical values of gradations are described for each pixel in the 256 gradation gray scale image shown in FIG. 6 (i). FIG. 8 (i) shows the gradation value on the horizontal axis and the number of pixels on the vertical axis based on the 256 gradation gray scale image of FIG. 6 (i) and the gradation diagram of FIG. 7 (i). It is the figure which showed the histogram.

Comparing the maximum value, minimum value, and average value of the gradation values for each pixel shown in FIGS. 8 (i), (ii), and 9 (iii), (iv), FIG. 8 (i) , (Ii) and FIGS. 9 (iii) and (iv), the average values become 59, 71, 82 and 129. From this, it is clear that the brightness increases as the scratch distance increases. According to FIG. 8 (i), in the bright field image, the difference was 74 because the maximum value = 110 and the minimum value = 36. This difference is considered to be due to the effect of embossing. On the other hand, in the composite image, the difference was 52 because the maximum value = 89 and the minimum value = 37. The histogram distribution of the composite image was smaller than the histogram distribution of the bright field image. Thus, it was found that the effect of embossing can be reduced by synthesizing the bright field reference image and the dark field reference image. In the inspection of line flaws in a resin molded product to which wrinkles are applied, a bright-field reference image and a dark-field reference image are used in addition to a bright-field image and a dark-field image when setting an adjustment-necessary region and an adjustment-unnecessary region. Therefore, it is possible to accurately exclude areas that are reliable in determining the presence or absence of whitening wounds, that is, areas that are difficult to misidentify whitening wounds and wrinkles, and can lead to more accurate inspection results. is expected.

The method and apparatus for inspecting scratches in a resin molded product according to the present invention are intended for resin molded products whose surface is textured, and in addition to automobile interior materials, for example, interior materials for buildings, It can also be used for resin molded products used as exterior materials for home appliances.

10 Optical microscope 11 Light source (irradiation means)
14 Imaging unit (image acquisition means)
14a Image sensor 15 Regulator (light adjustment means)
20 Computer (calculation unit)
21 Image processing means 22 Judging means 100 Inspection device S Sample (resin molded product)

Claims (9)

1. A method for inspecting a flaw in a resin molded product having a textured surface,
   With respect to the resin molded product, it is intended to inspect a linear wound having an inclination formed by a load continuously changing along a certain direction,
   An irradiation step of irradiating the line wound with light;
   An image acquisition step of acquiring a microscopic image of the flaw;
   An image processing step for processing the microscope image;
   A determination step of determining the state of the flaw based on an image processing result;
   For inspecting flaws in resin molded products including
2. In the image acquisition step, a bright-field image and a dark-field image of the flaw are acquired,
   In the image processing step, on the basis of the bright field image and the dark field image, a required adjustment area and an adjustment unnecessary area are set in the microscope image, and the bright field image and the dark field image are set for the adjustment area. Generating a combined composite image, selecting the bright field image or the dark field image for the adjustment unnecessary region, binarizing the gradation of the composite image and the image of the adjustment unnecessary region according to the same handling rule,
   The method for inspecting a flaw in a resin molded product according to claim 1, wherein in the determination step, the presence or absence of a whitening flaw that is the state of the line flaw is determined based on the image processing result obtained in the image processing step.
3. For the resin molded product before the line flaw is formed, further execute a preparatory step of acquiring a bright field reference image and a dark field reference image in advance,
   The method for inspecting a flaw in a resin molded product according to claim 2, wherein, in the image processing step, the bright field reference image and the dark field reference image are further used in setting the adjustment required area and the adjustment unnecessary area.
4. The adjustment-necessary area is a first adjustment-necessary area in which a comparison result of gradations of the bright field reference image and the bright field image is different from a comparison result of gradations of the dark field reference image and the dark field image. The method for inspecting a flaw in a resin molded product according to claim 3 including a region.
5. The adjustment-necessary region is a second adjustment-necessary region in which a gradation comparison result between the bright-field reference image and the dark-field reference image is different from a gradation comparison result between the bright-field image and the dark-field image. The inspection method of the crack in the resin molded product according to claim 3 or 4 containing a field.
6. The method for inspecting a flaw in a resin molded product according to any one of claims 2 to 5, wherein the adjustment required region is the entire region of the microscope image.
7. The inspection of a flaw in a resin molded product according to any one of claims 1 to 6, wherein when the line flaw is not confirmed in the determination step, a light adjustment step of adjusting light irradiated in the irradiation step is executed. Method.
8. In the image acquisition step, a bright-field image and a dark-field image of the flaw are acquired,
   In the image processing step, on the basis of the bright field image and the dark field image, a required adjustment area and an adjustment unnecessary area are set in the microscope image, and the bright field image and the dark field image are set for the adjustment area. After generating the combined composite image, a difference image is generated by subtracting the composite image from the bright field image or the dark field image, and the bright field image or the dark field image is selected for the adjustment unnecessary region, The gradation of the difference image and the image of the adjustment unnecessary area is binarized according to the same handling rule,
   The method for inspecting a flaw in a resin molded product according to claim 1, wherein in the determination step, the presence or absence of a gloss flaw that is the state of the line flaw is determined based on the image processing result obtained in the image processing step.
9. A device for inspecting scratches on a resin molded product having a textured surface,
   With respect to the resin molded product, it is intended to inspect a linear wound having an inclination formed by a load continuously changing along a certain direction,
   Irradiating means for irradiating the line wound with light;
   An image acquisition means for acquiring a microscopic image of the flaw;
   Image processing means for processing the microscope image;
   Determining means for determining the state of the flaw based on an image processing result;
   Inspection device for scratches on resin molded products with

Images