JPH0431755A - Apparatus for inspecting defect of sheet-shaped material - Google Patents

Abstract

PURPOSE:To make it possible to discriminate the printed part of the surface of a sheet-shaped material and the defective parts such as wrinkles and floats with a simple constitution by judging the position relationship between the high luminance part and the low luminance part of the defective part which is obtained by the emission of light that is approximately in parallel with a sheet from the side of the sheet. CONSTITUTION:An area-type CCD camera 1 of an image input part which is attached to a fixed part 8, a light source 4 and an optical-fiber lightguide 5 are made to traverse as a unitary body with a traverse mechanism 7. In this way, light is emitted on a material 6B from the optical-fiber lightguide 5 which is provided approximately in parallel with the material 6B that is higher by several mm. Thus, the bright and dark parts, i.e. the high luminance part and the low luminance part, are generated in the sequence of (bright dark) at the wrinkle part and the floating part on the surface of the material 6B. Only the dark part appears in the printed part in comparison with the normal part. The reflectivity and the position relationship are discriminated with the camera 1 and an image processing device 2 based on the kind of the protecting paper 6B. The defective part and the printed part are discriminated accurately and readily with the simple constitution.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a sheet-like object defect inspection device for detecting defects on the surface of a sheet-like object. The present invention relates to an inspection device that can identify defects such as wrinkles and detect only the defects.

[Prior Art] When a protective paper that covers the surface of a resin plate or the like is attached to the resin plate, defects such as wrinkles and lifting may occur.

Although defects in such sheet-like objects have conventionally been visually inspected, sheet-like object defect inspection apparatuses that automate the inspection are also used. Such a defect inspection apparatus for sheet-like objects uses a two-dimensional image input device and an image processing device.

To illuminate the sheet-like object to be inspected, a song-shaped high-frequency fluorescent lamp or a ring-shaped fiber optic lamp is used.The object is irradiated from above, and the reflected light is transmitted to a two-dimensional image input device. There are many things that I read. The n7 image signals obtained by the two-dimensional image input device are input to the image memory of the image processing device, and from this image data, normal areas and defective areas can be determined. After this data is binarized, it is Defect inspection is performed by measuring the defective portion within the window.

In addition, when the object to be inspected is a protective paper for a resin board and the protective paper is printed in various colors, using a filter that has the same wavelength characteristics as the color of the printed part can eliminate wrinkles on the protective paper. It becomes possible to detect only defects in

[Problems to be Solved by the Invention] In such conventional sheet-like defect inspection devices, when the color of the printed portion of the protective paper changes, the filter must be replaced, and the same filter must be replaced. When there are parts of different colors in the printed part of the object to be inspected, filters cannot cope with the problem. Furthermore, the protective paper itself comes in a variety of colors, making it difficult to accurately determine printed areas and defective areas using only a filter.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a defect inspection device for a sheet-like object, which can clearly distinguish printed parts on the surface of a sheet-like object from defective parts such as wrinkles and floating with a simple configuration.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, light is irradiated from a direction substantially parallel to the surface of a sheet-like object, and the brightness of one side surface irradiated with the wrinkled or floating light is The brightness is lowered so that the other side becomes a shadow and the brightness is lower, and defects such as wrinkles are detected from the positional relationship between the high and low brightness areas and are determined to be printed parts. .

That is, according to the present invention, an illumination means that is substantially parallel to the surface of the sheet-shaped object to be inspected that is moving in a certain direction and irradiates the surface of the object to be inspected from a direction that is substantially perpendicular to the certain direction; a two-dimensional image input device that images the surface of the object to be inspected from a direction substantially perpendicular to the surface of the object to be inspected; and a luminance signal component of the image data of the two-dimensional image input device is processed to determine the direction of irradiation by the illumination means. A defect inspection apparatus for a sheet-like object is provided, which has means for detecting that the positional relationship between a high brightness part and a low brightness part is a predetermined positional relationship of 5.

[Function] Since the sheet-like object defect inspection apparatus of the present invention has the above configuration,
Obtained by irradiating light almost parallel to the sheet from the side of the sheet. By determining the positional relationship between high and low brightness areas of the defective area, that is, when the sheet is irradiated from the left side. When the high brightness area is to the left of the low brightness area, this is determined to be a defect. On the other hand, the printed area has lower brightness than the peripheral area, so it cannot be confused with a defective area.

[Embodiment] An embodiment of the sheet-like object defect inspection apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

The objects to be inspected are protective papers 6A and 6B pasted on both sides of the acrylic resin plate 14. As protective paper 6A16B,
There is paper or resin film (white, colorless and transparent), and the width is approximately 3
m, it is moving at a constant speed along with the acrylic resin plate in a direction perpendicular to the plane of the drawing.

l is area type (two-dimensional) CCD with electronic shutter function
It is a camera and constitutes a two-dimensional image input device. The area type CCD camera 1 inspects the protective paper 6B pasted on the lower surface of the acrylic resin plate 14, and the inspection range is horizontal as shown in FIG. 200 mm in the direction perpendicular to the Since the inspection range is approximately 1/15 of the width of the object to be inspected 6B, the image input parts of the area type CCD camera 1, light source 4, and optical fiber light guide 5 are moved to the fixing part 8 by the traverse mechanism 7.
It is attached to and traverses as one.

Further, when the inspected object 6B comes to the inspection position, an inspection start signal is output to the image processing device 2.

4 is a light source, which uses a 100W halogen lamp. 5 is an optical fiber light guide, and the arrangement of the emitting part is I x 300 mm. The output part of the optical fiber light guide 5 is installed several mm above and almost parallel to the object to be inspected 6B, so that the object to be inspected 6B passes therethrough. The light source 4 and the optical fiber light guide 5 constitute illumination means.

With this illumination means, it is possible to generate brightness and darkness, that is, high-luminance areas and low-luminance areas, in the (bright-dark) order at the wrinkled and raised areas on the surface of the protective paper 6B. The printed part is only a dark part compared to the normal part. However, since the reflectance differs depending on the type of protective paper 6B, it can be said that light and dark occur in the order of (dark-bright).

In addition, since the illumination means must be in the form of a line, optical fiber illumination and fluorescent lamps are not suitable. The present inventors adopted an optical fiber/SL illumination system in which the emitting portions are arranged in a line as described above because the light intensity is high.

Reference numeral 2 denotes an image processing device that processes the output signal of the CCD camera 1. First, the image of the area type CCD camera 1 is A/D converted into an 8-bit digital signal and input into the image memory. A specified range of this image memory is set as a window, and edges showing changes in brightness-darkness or dark-brightness are detected in this range. There are various edge detection methods, but it is carried out by taking the difference with a Sobel operator, and the value after processing with the Sobel operator is 10.
When the above is reached, it is determined to be an edge. Further, in the above judgment, the edge coordinates are measured, and when the rising coordinate is the falling coordinate, an NG signal is output. Here, the coordinates are one-dimensional coordinates in the direction of irradiation by the illumination means, and the closer to the illumination means the smaller the value.

This image processing device 2 constitutes a means for detecting that the positional relationship between the high-luminance portion and the low-luminance portion in the irradiation direction is a predetermined one using the illumination means. This image processing device 2 operates according to the following principle. That is, the image data obtained by reading with the two-dimensional image input device is as follows.

a) Normal part There are differences in image data depending on the variety, but there is no change in brightness.

b) Printed part Light and dark occur in the order of (dark-bright) in the printed area.

C) Light and dark areas occur in the order of (light-dark) in the wrinkled and lifted areas of the defective area protective paper.

Therefore, as mentioned above, set a window in an arbitrary range, use a Sobel operator, etc., to detect rising edges and edges from one end of the window, and then calculate the difference in the coordinates of the two. And it becomes as follows.

Printed area: Coordinates of rising edge Coordinates of falling edge Defected area... Coordinates of rising edge - Coordinates of falling edge Therefore, from this positional relationship, the defective area can be detected and the above-mentioned NG signal can be output. I can do it.

Reference numeral 3 denotes a monitor TV, which displays an image of the object to be inspected 6B, measured values of the coordinates of machining and cutting, and judgment results (OK or NG) in response to the output of the image processing device 2.

FIG. 2 is a diagram showing an example of the inspection procedure of the present invention.

The object to be inspected 6B is moving from the top to the bottom in FIG. 2 as shown by the arrow. The image input section shows the field of view of the CCD camera 1, and the traverse mechanism 7 moves left and right for 7.5 seconds/3.
When the inspected object 6B reaches the inspection position after moving at a speed of m, an inspection start signal is inputted to the image processing device 2 from the control circuit 16.

Note that the CCD camera 1 and the traverse mechanism 75 are controlled by a control circuit 16. When the inspection start signal is input, the area type CCD camera l detects 174,000
Using the second electronic shank function, an image is input and input into the image memory of the image processing device 2. The blur in this image data is 0.1 mm and does not affect the inspection. The image data is also displayed on the monitor TV3. It processes the image data in the image memory and outputs an NG signal if there is a defect.

The inspection range is 200 mm, and the inspection is performed at intervals of 0.5 seconds/field of view. Therefore, if the moving speed of the inspected object 6B is 3 m/min, the inspection will be carried out at intervals of 750 mm in the moving direction. Become. When the NG signal is output, the device cuts the inspection object 6B to a predetermined length, removes the defective portion and cuts it, or reapplies the protective paper to the defective portion.

FIG. 3 is a diagram showing an example of an object to be inspected by the apparatus of the present invention.

The protective paper, which is the object to be inspected 6B, is printed with lines 9, marks 10, and the like in various colors. In addition, wrinkles 11 are formed at an angle within a few degrees with respect to the moving direction of the inspected object 6B shown by the arrow.
may occur.

FIG. 4 is a diagram showing an example of an output signal waveform of the CCD camera 1 in the apparatus of the present invention. This example shows the CCD output signal waveform in the dotted line portion of FIG. In the portion of line 9 and mark 10, brightness and darkness occur in the order of (dark→bright). Furthermore, in the wrinkles 11, light and dark occur in the order of (bright-dark).

FIG. 5 is a flowchart showing the image processing procedure in the present invention. That is, the image processing device 2 has CPU, R
It is composed of an AMSROM, an interface, etc., and this CPU operates according to the flow shown in this flowchart.

In this flow, inspection is first started by inputting a start signal. Next, a multivalued image is input from the CCD camera 1 using the electronic shutter function. Detects the coordinates of the changing point (rising edge) of (dark → bright) within the specified window range within the field of view, and also detects the coordinates of the changing point (rising edge) of (bright - dark) within the specified window range. Find the coordinates of.

From the size relationship of the above coordinates, if the rising edge coordinate > the falling edge coordinate, then the defective part, the rising edge coordinate - the falling edge coordinate, the printed part, the rising edge coordinate = the falling edge coordinate, that is, the change When the coordinates of a point cannot be detected, it is determined that it is a normal part. If it is determined to be defective, an NG signal is output.

The inspection is continued by repeating this flow. When the inspection in one field of view is completed, the CCD camera is moved by the traverse mechanism 7 as shown in FIG. 2, and the same measurement is performed in the next field of view.

[Effects of the Invention] As is clear from the detailed explanation above, the sheet defect inspection apparatus of the present invention irradiates light from the side of the inspected object, and applies high brightness to defective areas such as wrinkles. Since this method creates low parts and low parts and checks their positional relationship, it is easy and accurate to distinguish between defective parts and printed parts. In addition, it is possible to inspect wrinkles and lifting regardless of changes in the reflectance of the protective paper or color diversity of printed matter, making it highly effective as a defect inspection device for sheet-like materials.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the sheet-like object defect inspection apparatus according to the present invention, FIG. 2 is a diagram showing an example of the inspection procedure according to the present invention, and FIG. FIG. 4 is a diagram showing an example of a CCD output signal waveform of the apparatus of the present invention, and FIG. 5 is a flowchart showing an image processing procedure in the present invention. 1... CCD camera, 2... Image processing device, 3...
・Monitor TV, 4...Light source, 5...Optical light kite, 6A, 6B...Test object, 7...Torano gear mechanism, 8...Fixing part, 9...・Print lines,
10... Mark, 11... Wrinkle, 14... Acrylic board, 16... Control circuit. inventor

Claims (2)

[Claims] (1) An illumination means that illuminates the surface of the object to be inspected from a direction substantially parallel to the surface of the object to be inspected that is moving in a certain direction and substantially perpendicular to the certain direction; a two-dimensional image input device that images the surface of the object to be inspected from a direction substantially perpendicular to the surface; and a two-dimensional image input device that processes the brightness signal component of the image data of the two-dimensional image input device to determine the brightness in the direction of irradiation by the illumination means. A defect inspection device for a sheet-like object, comprising means for detecting that the positional relationship between a high brightness portion and a low brightness portion is a predetermined positional relationship. (2) The means for detecting that the positional relationship between the high-luminance portion and the low-luminance portion is a predetermined one includes the illumination of the rising edge and the falling edge obtained by processing the image data. 2. A defect inspection apparatus for sheet-like objects according to claim 1, comprising means for detecting coordinates in a direction and means for detecting a difference between the coordinates.