JPH04270949A - Apparatus for detecting flaw - Google Patents

Abstract

PURPOSE:To detect not only a flaw such as the air bubble contained in a transparent film but also a flaw such as the fine surface flaw of said film. CONSTITUTION:A light source 11 is provided in a box body 10 having an opening part 16 and a shield plate 12 whose outer peripheral surface A is positioned outside the opening inner peripheral surface B of the opening part 16 is provided between the light source 11 and the opening part 16. A photographing apparatus is provided within the range surrounded by the segments L connecting the outer peripheral surface A of the shield plate 12 and the opening inner peripheral surface B of the opening part 16 at a great distance from the intersecting point (r) of the segments L outside the box body 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detection device for detecting defects in a translucent member such as a film.

0002

[Prior Art] Conventionally, as a device for detecting defects in a film, etc., an object to be measured such as a film is illuminated with light from below, and an image of the object to be measured is captured using an imaging device such as a CCD camera installed above the object to be measured. A method of photographing and detecting defects (transmitted light observation method) has been put into practical use.

0003

[Problems to be Solved by the Invention] However, with conventional defect detection devices, the light that has passed through the film also enters the lens of the imaging device, making it difficult to see images of defects. could not be detected.

Therefore, an object of the present invention is to provide a defect detection device that can detect defects such as transparent bubbles contained in a translucent measurement object, and can also accurately detect defects such as surface scratches on the measurement object. It is to provide.

[0005]

[Means for Solving the Problems] A defect detection device of the present invention includes a light source provided in a box body having an opening, and an outer circumferential surface between the light source and the opening and an inner circumferential surface of the opening. A shielding plate located on the outer side is provided, and an imaging device is installed within the range surrounded by the line segment at a distance from the intersection of the line segment connecting the outer peripheral surface of the shielding plate and the inner peripheral surface of the opening on the outside of the box. It has been established.

The operation of the present invention will be explained using FIG. The light emitted from the light source 11 provided inside the box body 10 is reflected by the lower surface of the shielding plate 12, the inner surface of the bottom plate 13, and the inner surface of the side plate 14, which serve as reflective surfaces, and is irradiated to the outside through the opening 16 of the upper plate 15. Ru. At this time, in the line segment L connecting the outer circumferential surface A of the shielding plate 12 and the inner circumferential surface B of the opening 16 of the upper plate 15, the light emission angle θ becomes the minimum. The light ray L whose exit angle θ is the minimum
is hereinafter referred to as the minimum exit angle ray.

The width of the shielding plate 12 is a, and the opening 1 of the upper plate 15 is
The width of 6 is c, and the distance between the upper plate 15 and the shielding plate 12 is b. Further, in the minimum exit angle ray L, the distance between the point γ where the ray L intersects and the upper wall 15 is X, and the spread of the ray at an arbitrary distance Z from the intersection γ is V. At this time, X,
The relationships among Z, V, a, b, and c are as shown in the equations (■) and (■). X=b×c/(a-c)
...■V=c×Z/X=(a-c)×Z
/b...■

[0008] Now, the upper plate 1
Assuming that a lens with an effective aperture D is placed at a position X+Z from 5, the light from the light source 11 will not enter the lens if the condition (2) below is satisfied. D<V
...■

Therefore, when an imaging device for defect image detection such as a CCD camera or a photo camera is provided so as to satisfy the condition of formula (2), and an object to be measured is placed between the imaging device and the box 10 and observed, If there are defects such as scratches or internal air bubbles on the surface, light will be scattered at those areas, and only the defect image will stand out brightly, resulting in a very clear image.

[0010] In this way, it is possible to detect defects such as transparent air bubbles contained within a transparent film, which was previously impossible, and at the same time, it is also possible to detect defects such as minute surface scratches, which were previously difficult to detect.

[0011] The shape of the box 10 is not limited to a cube;
It may be cylindrical, spherical, etc., and the lower surface of the shielding plate 12 is not a reflective surface but merely shields light, and the light from the light source is reflected only by the inner surface of the box and does not pass through the opening. It may be irradiated from.

Furthermore, the object to be measured is not limited to a transparent film, but may be any light-transmitting object, and may not be in the form of a sheet. Furthermore, the defects to be measured are not limited to bubbles and surface scratches, but can be detected as long as they scatter light and make the image appear brighter, such as internal scratches and impurities.

[0013]

[Embodiment] An embodiment of the present invention will be described with reference to FIG. 10 is a cubic box consisting of a top plate 15, a side plate 17, and a bottom plate 18. The inner surface 19 of the top plate 15 is treated with anti-reflection treatment such as black matte coating, and the inner surface 14 of the side plate and the inner surface of the bottom plate are 13 is coated with aluminum or the like so that it functions as a reflecting mirror. A circular opening 16 is formed in the top plate 15, and a light source 11 is provided on the inner surface 13 of the bottom plate. In addition, 12 is a shielding plate, which is formed into a circular shape with an outer diameter larger than the opening 16. The lower surface is coated with aluminum so that it functions as a reflecting mirror, and the upper surface is coated with black gloss. Anti-reflective treatment such as erase painting has been applied. Reference numeral 20 denotes a holding plate for holding the shielding plate 12, and is made of a transparent plate such as a glass plate so that light can pass therethrough. 21 is an object to be measured such as a film, and 22 is a C for observing a defect image.
It is an imaging device such as a CD camera, and is arranged so that the relationship of the above-mentioned equation (2) is satisfied.

The light from the light source 11 is reflected by the lower surface of the shielding plate 12, the inner surface 13 of the bottom plate, and the inner surface 14 of the side plates, and is reflected by the opening 1 of the upper plate 15.
6 and illuminates the measurement object 21. The illuminated measurement object 21 is observed by an imaging device 22 . The imaging device 22 is
Since the arrangement is such that the relationship of equation (2) above is satisfied, the light from the light source 11 does not enter the imaging device 22, and only the defective image stands out brightly, thereby preventing minute scratches on the film surface.
Air bubbles inside can also be clearly detected.

[0015] Furthermore, the lower surface of the shielding plate 12 is used as a reflective surface,
Since the light from the light source 11 is reflected by the shielding plate 12, the bottom plate 18, and the side plate 17 and is irradiated from the opening 16, the thickness of the box 10 can be reduced, and the device can be made smaller. Note that the opening 16 and the shielding plate 12 are not limited to circular shapes.

[0016]

According to the defect detection device of the present invention, it is possible to detect defects such as air bubbles contained in the object to be measured, and at the same time, it is possible to detect defects such as minute surface scratches on the object to be measured.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an overview of the principle of the present invention.

FIG. 2 is a cross-sectional view of one embodiment of the present invention.

[Explanation of symbols]

10 Box body 11 Light source 12 Shielding plate 16 Opening 22 Imaging device

Claims (2)

[Claims] 1. A box having an opening, a light source provided inside the box, and a light source provided between the light source and the opening, the outer circumferential surface of which is located outside the inner circumferential surface of the opening. and an imaging device provided within a range surrounded by the line segment at a distance from an intersection on the outside of the box body of a line segment connecting the outer circumferential surface of the shield plate and the inner circumferential surface of the opening of the opening. A defect detection device comprising a device. 2. A cubic box with an opening in the top plate and reflective surfaces on the inner surfaces of the side plates and the bottom plate, a light source provided inside the box, and a light source provided between the light source and the opening. a shielding plate whose outer peripheral surface is located outside the inner peripheral surface of the opening and whose lower surface is a reflective surface, and a line segment connecting the outer peripheral surface of this shielding plate and the inner peripheral surface of the opening of the opening. and an imaging device provided within a range surrounded by the line segment at a distance from the intersection on the outside of the box.