JP2020139964A - Flaw detection device and flaw detection method of light transmissive product - Google Patents

Abstract

To provide a flaw detection device of a light transmissive film capable of easily and reliably detecting a flaw generated in the light transmissive film, especially a linear flaw.SOLUTION: A flaw detection device includes: a filter member 4 that allows a light transmission area 42a for transmitting diffusion light from a plane light source 5 and a non-light transmissive area 42b for preventing diffusion light from being transmitted, and is positioned such that transmission light through the non-light transmissive area 42b impinges on a light transmissive film 2; and a CCD camera 6 that is positioned in a side opposite to the filter member 4 while sandwiching the light transmissive film 2 and captures a film surface of the light transmissive film 2 and acquires a linear flaw Fw appearing on a film surface corresponding to the non-light transmissive area 42b. The filter member 4 is constituted of a plane body, and the light transmission area 42a and the non-light transmission area 42b in the filter member 4 are alternately formed in a parallel strip shape having predetermined width.SELECTED DRAWING: Figure 1

Description

The present invention relates to a defect detecting device or the like capable of satisfactorily detecting a defect generated in a transparent film.

Patent Document 1 discloses a method for detecting a defect (defect) generated in a light-transmitting film, and here, a binary reference transmission type having a predetermined lattice spacing on one surface of the light-transmitting film. By projecting a lattice image, imaging a reference transmissive lattice image that passes through a light transmissive film and appears on the other surface, and refracting the transmitted light due to a light transmissive defect of the light transmissive film, the transmitted light is refracted. The presence or absence of a light transmission defect is detected by extracting the shading region generated in the image data of the captured reference transmission type lattice image.

JP 2015-75483

The above-mentioned conventional flaw detection method can satisfactorily detect flaws generated in a light-transmitting film, but there is a problem that detection of particularly elongated linear flaws is still insufficient.

Therefore, the present invention solves such a problem, and is a flaw detection device and a flaw detection device for light-transmitting products capable of easily and surely detecting defects caused in light-transmitting products, particularly linear flaws. The purpose is to provide a method.

In order to achieve the above object, in the defect detection device of the light transmissive product of the first invention, the light transmissive region (42a) through which the light from the diffused light source (5) is transmitted and the non-transmissive region (42b) through which the light is not transmitted are transmitted. Is formed, and the light transmissive product (2) is sandwiched between the filter member (4) positioned so that the light transmitted through the translucent region (42a) is incident on the light transmissive product (2). Image of the product surface of the light transmissive product (2) positioned on the side opposite to the filter member (4), and a flaw image (Fw) appearing on the product surface corresponding to the non-transmissive region (42b). It is provided with an imaging means (6) for acquiring.

In the first invention, the diffused light from the light source passes through the translucent region of the filter member and is incident not only on the product surface facing the region but also on the product surface facing the non-transmissive region. Almost all of the output light that passes through the translucent region of the filter member substantially vertically and is incident on the product surface facing the region is incident on the imaging means to generate a white region on the captured image, whereas it is transparent. Since the output light that passes diagonally through the light region and is incident on the product surface facing the non-transmissive region of the filter member is hardly incident on the imaging means, a black region on the captured image is generated. If there is a flaw on the surface of the light-transmitting product, the output light is scattered at the flawed portion and is incident on the imaging means, so that a highly bright defect image is generated in the black region. In the white region, the overall brightness is high, so the flawed image is buried and cannot be seen.

In the flaw detection device of the light transmissive product of the second invention, the filter member (4) is formed of a flat surface, and the translucent region (42a) and the non-transmissive region (42b) in the filter member (4) are formed. It is formed alternately in parallel strips of a predetermined width.

According to the second invention, it is effective for detecting elongated linear flaws generated on the product surface of a light-transmitting product.

In the defect detection device for the light transmissive product of the third invention, the transmissive film (2), the filter member (4) and the imaging means (6) are relatively moved at a predetermined speed, and the imaging means (6) is moved. ) Is operated at a cycle corresponding to the relative movement.

According to the third invention, when a light-transmitting product has a long-lasting strip shape or the like, a flaw locally generated on the product surface can be reliably detected.

In the method for detecting a defect of a light-transmitting product of the fourth invention, a light-transmitting region (42a) for transmitting light from a light source (5) and a non-transmissive region (42b) for not transmitting light are formed, and the light-transmitting region (42b) is formed. Light transmitted through 42a) is incident on the light transmissive product (2) to image the product surface of the light transmissive product (2) and appear on the product surface corresponding to the non-transmissive region (42b). Acquire a flaw image (Fw).

In the fourth invention, the same action and effect as in the first invention can be obtained.

The reference numerals in parentheses indicate the correspondence with the specific means described in the embodiments described later for reference.

As described above, according to the present invention, it is possible to easily and surely detect a defect generated in a light-transmitting product.

It is an overall perspective view which shows an example of the structure of the defect detection apparatus. It is a figure which shows an example of the image which caused the linear defect. It is a conceptual diagram which shows an example of the image which detected the linear defect which moves relative. It is a conceptual diagram which shows an example in the whole image of the linear defect obtained by image processing.

It should be noted that the embodiments described below are merely examples, and various design improvements made by those skilled in the art within the scope of the present invention are also included in the scope of the present invention.

FIG. 1 shows the overall configuration of the defect detection device. In FIG. 1, a strip-shaped light-transmitting film 2 having a constant width as an example of a light-transmitting product is conveyed on the conveying rollers 11 and 12 in the diagonally front-rear direction of the drawing. A constant tension is applied to the light transmissive film 2 by the tension roller 13, and in this state, the light transmissive film 2 is conveyed at a constant speed in the direction of the arrow in the drawing by the drive roller 14 in contact with the transfer roller 11. The drive roller 14 is connected to the motor 15, and the motor 15 is rotationally controlled by the output of the motor control unit 31.

Below the light-transmitting film 2 that is horizontally conveyed, a plate-shaped filter member 4 is arranged parallel to the film surface while being held on both sides by a holding frame 41. The width of the filter member 4 (in the left-right direction in the figure) is about the same as the width of the light-transmitting film 2, and the vertical width is such that the entire image of linear flaws described later can be grasped according to the moving speed of the light-transmitting film 2. It is long enough. A transparent translucent region 42a that transmits light and a black non-transmissive region 42b that does not transmit light (see FIG. 3) are parallel to the filter member 4 in the longitudinal direction, which is the moving direction of the light transmissive film 2. It is formed alternately in a strip shape. The non-transmissive region 42b is formed by forming a non-transmissive thin film on the surface of the filter member 4 formed of a translucent material.

Below the filter member 4, a rectangular flat light source 5 having a diameter larger than this is arranged. The flat light source 5 is a diffused light source in which a large number of white LEDs are arranged on a flat surface, and the output light of the flat light source 5 is incident on the entire surface from below the filter member 4. The planar light source 5 is connected to the power supply unit 51.

A CCD camera 6 as an imaging means is provided above the horizontally conveyed light-transmitting film 2 so that its focus is aligned with the light-transmitting film 2. The CCD camera 6 is connected to the image processing unit 61, images the film surface of the light transmissive film 2 below at regular time intervals, and sends the acquired image to the image processing unit 61. Here, an example of the distance between the CCD camera 6 and the light transmissive film 2 is 600 mm, and an example of the distance between the light transmissive film 2 and the filter member 4 is 40 to 100 mm.

FIG. 2 shows an example of an image obtained by photographing the film surface with the CCD camera 6. In the image, the band-shaped white region Rw and the black region Rb appear alternately corresponding to the band-shaped translucent region 42a and the non-transmissive region 42b of the filter member 4 behind the light transmissive film 2. The reason is that since the output light from the planar light source 5 is diffused light, the film passes through the translucent region 42a of the filter member 4 and faces not only the film surface facing the region 42a but also the non-transmissive region 42b. It also incidents on the surface. In this case, almost all of the output light that passes through the translucent region 42a of the filter member 4 substantially vertically and is incident on the film surface facing the region 42a is incident on the CCD camera 6 to generate the white region Rw. On the other hand, the output light obliquely passing through the translucent region 42a and incident on the film surface facing the non-transmissive region 42b of the filter member 4 hardly enters the CCD camera 6, so that the black region Rb is generated. It is.

Here, if there is a linear defect on the film surface of the light transmissive film, a part of the image Fw is generated in the black region Rb as shown in FIG. The reason for this is that if there is a linear flaw, the output light from the planar light source 5 is scattered at the linear flaw portion and is incident on the CCD camera 6, and an image of the linear flaw is generated, but the translucent region 42a Since the overall (background) brightness (brightness) is high in the white region Rw on the image corresponding to the above, the image of the linear flaw generated in the region Rw is buried and cannot be seen. On the other hand, in the black region Rb on the image corresponding to the non-transmissive region 42b, the brightness of the linear flaw portion is higher than that of the surroundings because the brightness of the whole (background) is low, and the white image Fw appears. is there.

FIG. 3 conceptually shows an example of an image of the film surface obtained by the CCD camera 6 when the light transmissive film 2 having linear flaws on the film surface moves and passes above the filter member 4. FIG. 3 shows a case where the light transmissive film 2 passes through the filter member 4 in the direction of the arrow in the figure. If there is a linear flaw on the light transmissive film 2, imaging can be performed at regular time intervals. Along with this, as shown in FIGS. 3 (1) to (3), an image in which a partially white image Fw of the moving linear flaw is generated in the black region Rb is obtained. Therefore, when the white image Fw of the linear flaw in each image is extracted as a black image by image processing and the time positions of these images are aligned and overlapped, the black color of the entire linear flaw is obtained on the white background as shown in FIG. Image Fb is obtained.

Instead of obtaining the entire linear flaw as a white image on a black background, it may be obtained as a black image on a white background. Further, the filter member and the CCD camera may be moved with respect to the stationary light transmissive film. Further, if the filter member has a size capable of covering the entire light transmitting film (light transmitting product), it is not necessary to move the two relative to each other. Further, the translucent region and the non-transmissive region do not necessarily have to be alternately formed in a parallel strip shape having a predetermined width. Further, the flaws to be detected by the present invention are not limited to linear flaws, and may be punctate or planar flaws (defects). The light-transmitting product is not limited to a film, but also includes a flat plate such as plastic or glass, and a three-dimensional product as well as a flat plate.

2 ... light transmissive film, 4 ... filter member, 42a ... translucent region, 42b ... non-transmissive region, 5 ... flat light source, (diffusion light source), 6 ... CCD camera (imaging means), Fw ... (defect image) ..

Claims (4)

A filter member in which a translucent region that transmits light from a diffused light source and a non-transmissive region that does not transmit light are formed so that the light transmitted through the transmissive region is incident on the light transmissive product, and the light. An imaging means that is positioned on the opposite side of the filter member across the transmissive product to image the product surface of the light transmissive product and obtains a defect image appearing on the product surface corresponding to the non-transmissive region. A flaw detection device for light-transmitting products. The defect detection device for a light-transmitting product according to claim 1, wherein the filter member is formed of a flat surface, and light-transmitting regions and non-transmissive regions of the filter member are alternately formed in a parallel strip shape having a predetermined width. According to claim 1 or 2, the light transmissive product, the filter member, and the imaging means are relatively moved at a predetermined speed, and the imaging means is operated at a cycle corresponding to the moving speed of the relative movement. Defect detector for the described light transmissive products. A translucent region that transmits light from a light source and a non-transmissive region that does not transmit light are formed, and the light transmitted through the translucent region is incident on the light transmissive product to image the product surface of the light transmissive product. A method for detecting a flaw in a light-transmitting product, which comprises acquiring an image of a flaw appearing on the surface of the product corresponding to the non-transmissive region.