JP2020060491A - 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 flaw detection device and the like that can favorably detect flaws formed on a transparent film.

  Patent Document 1 discloses a method for detecting a flaw (defect) generated in a light transmissive film. Here, a binary reference transmission type having a predetermined lattice spacing on one surface of the light transmissive film. By projecting a lattice image, a reference transmission type lattice image that appears on the other surface through the light transmissive film is captured, and the transmitted light is refracted by the light transmissive defect of the light transmissive film, The presence / absence of a light transmissive defect is detected by extracting a shaded area that occurs in the image data of the captured reference transmission type lattice image.

Japanese Patent Laid-Open No. 2015-75483

  The above-described conventional flaw detection method can satisfactorily detect flaws formed on the light-transmissive film, but there is a problem that particularly linear flaws extending long and thin are still insufficient.

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

  In order to achieve the above object, in the flaw detection device for a light transmissive product according to the first aspect of the present invention, a light transmitting region (42a) that transmits light from a diffused light source (5) and a non-light transmitting region (42b) that does not transmit light. And the filter member (4) positioned so that the light transmitted through the light transmitting region (42a) is incident on the light transmissive product (2) and the light transmissive product (2). A flaw image (Fw) appearing on the product surface corresponding to the non-light-transmitting region (42b) by imaging the product surface of the light-transmitting product (2) positioned on the side opposite to the filter member (4). And an image pickup means (6) for acquiring

  In the first aspect of the present invention, the diffused light from the light source passes through the light-transmitting region of the filter member and enters not only the product surface facing the region but also the product surface facing the non-light-transmitting region. Almost all output light that passes through the light-transmitting region of the filter member substantially vertically and is incident on the surface of the product that faces the region is almost incident on the image capturing means to generate a white region on the captured image. The output light that obliquely passes through the light region and is incident on the surface of the product that faces the non-light-transmitting region of the filter member is hardly incident on the image pickup means, so that a black region on the captured image is generated. If there is a flaw on the product surface of the light transmissive product, the output light is scattered by the flaw and enters the image pickup means, so that a flaw image with high brightness is generated in the black region. In the white area, the overall brightness is high and the flaw image is buried and invisible.

  In the flaw detection device for a light transmissive product according to the second aspect of the present invention, the filter member (4) is composed of a flat body, and the translucent region (42a) and the non-translucent region (42b) of the filter member (4) are formed. The strips are alternately formed in parallel with a predetermined width.

  According to the second aspect of the present invention, it is effective for detecting a long and continuous linear flaw generated on the product surface of the light transmissive product.

  In the flaw detection device for a light-transmitting product according to the third aspect of the present invention, the transparent film (2), the filter member (4) and the image pickup means (6) are relatively moved at a predetermined speed, and the image pickup means (6) is moved. ) Is operated at a cycle corresponding to the relative movement.

  According to the third aspect of the present invention, when the light transmissive product is in the form of a strip that continues for a long time, it is possible to reliably detect a flaw locally generated on the product surface.

  In the flaw detection method for a light transmitting product according to the fourth aspect of the present invention, a light transmitting region (42a) that transmits light from the light source (5) and a non-light transmitting region (42b) that does not transmit light are formed, and the light transmitting region (42b) is formed. The light transmitted through 42a) is incident on the light transmissive product (2), and the product surface of the light transmissive product (2) is imaged to appear on the product surface corresponding to the non-light transmissive region (42b). Acquire a flaw image (Fw).

  Also in the fourth invention, the same operational effect as in the first invention can be obtained.

  The reference numerals in the parentheses refer to corresponding relationships with specific means described in the embodiments described later.

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

It is the whole perspective view showing an example of composition of a flaw detection device. It is a figure which shows an example of the image which produced the linear flaw. It is a conceptual diagram which shows an example of the image which detected the linear flaw which moves relatively. It is a conceptual diagram which shows an example in the whole image of the linear flaw obtained by image processing.

  The embodiments described below are merely examples, and various design improvements made by those skilled in the art are also included in the scope of the present invention without departing from the scope of the present invention.

  FIG. 1 shows the overall structure of the flaw detection device. In FIG. 1, a band-shaped light-transmitting film 2 having a constant width is conveyed as an example of a light-transmitting product on the conveying rollers 11 and 12 in the diagonal front-back direction. A constant tension is applied to the light-transmitting film 2 by a tension roller 13, and in this state, the driving roller 14 in contact with the conveying roller 11 conveys the light-transmitting film 2 at a constant speed in the direction of the arrow in the figure. The drive roller 14 is connected to a motor 15, and the motor 15 is rotationally controlled by the output of the motor control unit 31.

  Below the horizontally transparent light-transmitting film 2, a plate-shaped filter member 4 is arranged in parallel with the film surface by being held by holding frames 41 on both sides. The lateral width (left and right direction in the figure) of the filter member 4 is approximately the same as the width of the light transmissive film 2, and the vertical width thereof makes it possible to grasp the overall image of linear defects described later according to the moving speed of the light transmissive film 2. It is long enough. Then, in the filter member 4, a transparent light-transmitting region 42a that transmits light and a black non-light-transmitting region 42b (see FIG. 3) that does not transmit light are parallel to each other with a predetermined width in the longitudinal direction, which is the moving direction of the light-transmitting film 2. The strips are alternately formed. The non-translucent region 42b is formed by forming a non-translucent 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 larger diameter than that 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 of the filter member 4 from below. The flat light source 5 is connected to the power supply unit 51.

  A CCD camera 6 as an image pickup means is provided above the light-transmitting film 2 conveyed horizontally so that the focus thereof is on the light-transmitting film 2. The CCD camera 6 is connected to the image processing unit 61, images the film surface of the lower light-transmitting film 2 at regular time intervals, and the acquired image is sent 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.

  An example of an image obtained by picking up the film surface with the CCD camera 6 is shown in FIG. The image is such that strip-shaped white regions Rw and black regions Rb alternately appear corresponding to the strip-shaped translucent regions 42a and the non-translucent regions 42b of the filter member 4 behind the light transmissive film 2. The reason is that since the output light from the flat light source 5 is diffused light, the film that passes through the transparent region 42a of the filter member 4 and faces the non-transparent region 42b as well as the film surface that faces the region 42a. It also enters the surface. In this case, almost all of the output light that passes through the light transmitting 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 that obliquely passes through the transparent region 42a and is incident on the film surface of the filter member 4 facing the non-transparent region 42b is hardly incident on the CCD camera 6, so that the black region Rb is generated. It is.

  Here, if there is a linear flaw 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 flat light source 5 is scattered by the linear flaw portion and enters the CCD camera 6 to form an image of the linear flaw, but the transparent area 42a. In the white region Rw on the image corresponding to, the entire (background) luminance (brightness) is high, and thus 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-light-transmitting region 42b, the luminance of the whole (background) is low, so that the luminance of the linear flaw portion is higher than that of the surrounding area 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 a linear flaw on the film surface moves and passes over the filter member 4. FIG. 3 shows a case where the light transmissive film 2 is passing 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, the image is taken at regular intervals. Accordingly, as shown in (1) to (3) of FIG. 3, an image in which a partial white image Fw of a moving linear flaw is generated in the black region Rb is obtained. Therefore, the white image Fw of the linear flaw in each image is extracted as a black image by image processing, and when the time positions of these images are aligned and overlapped, the black of the entire linear flaw is displayed on a white background as shown in FIG. The 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, as long as the filter member has a size capable of covering the entire light-transmitting film (light-transmitting product), it is not necessary to move the both members relatively. Further, the light-transmitting regions and the non-light-transmitting regions do not necessarily have to be alternately formed in parallel strips having a predetermined width. Furthermore, the flaws to be detected by the present invention are not limited to linear flaws, but may be spot-like or plane-like flaws (defects). The light-transmissive product is not limited to a film, and includes flat plates such as plastic and glass, and three-dimensional products other than flat plates.

2 ... Light transmissive film, 4 ... Filter member, 42a ... Translucent region, 42b ... Non-translucent region, 5 ... Flat light source, (diffuse light source), 6 ... CCD camera (imaging means), Fw ... (defect image) .

Claims (4)

A light-transmitting region that transmits the light from the diffused light source and a non-light-transmitting region that does not transmit the light are formed, and a filter member positioned so that the light transmitted through the light-transmitting region enters the light-transmitting product, and the light. An image pickup unit that is positioned on the opposite side of the filter member with the transparent product interposed therebetween, images the product surface of the light-transmitting product, and acquires a flaw image that appears on the product surface corresponding to the non-light-transmitting region. A flaw detection device for a light-transmitting product. The flaw detection device for a light-transmissive product according to claim 1, wherein the filter member is formed of a flat body, and the light-transmitting regions and the non-light-transmitting regions of the filter member are alternately formed in parallel strips having a predetermined width. 3. The light transmissive product, the filter member and the image pickup means are moved relative to each other at a predetermined speed, and the image pickup means is operated at a cycle corresponding to the moving speed of the relative movement. A flaw detection device for the light-transmitting product described. A light-transmitting region that transmits light from a light source and a non-light-transmitting region that does not transmit light are formed, and light transmitted through the light-transmitting region is incident on a light-transmitting product to image the product surface of the light-transmitting product. A flaw detection method for a light transmissive product, characterized in that a flaw image appearing on the product surface corresponding to the non-light-transmitting region is acquired.