JPH03231144A - Apparatus for inspecting flaw of packed article - Google Patents

Abstract

PURPOSE:To accurately inspect a flaw without receiving the effect of the printing of a color or pattern by digitizing the two-dimensional image signal of the reflected light from an object to be inspected due to lateral illumination to compare the same with a preset threshold value. CONSTITUTION:The reflectivity of an object 5 to be inspected receives the effect of the incident angle of the illumination light of an illuminator 2. Therefore, when the lateral illumination is performed almost in parallel to the plane of the object 5 to be inspected, reflected light is not received at the flat part of the object 5 to be inspected in spite of a white color by the two-dimensional image input apparatus 3 arranged above the object 5 to be inspected. Reflected light is scattered at the broken and wrinkled part of the object 5 to be inspected even in a colorless transparent black case and a part thereof is received by the apparatus 3. That is, only the broken and wrinkled part of the object 5 to be inspected is inputted imagewise as a bright point by lateral illumination. The image data read by the apparatus 3 is converted to digital data by an A/D converter and this data is binarized on the basis of a preset value to be inputted to the image memory of an image processor 4. The indicated range of the image memory is set as a window and a bright point is detected within this range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a defect inspection device for packages, and in particular for packages packaged with a transparent film and whose printed pattern can be visually observed. Regarding inspection equipment for defects such as tears and wrinkles.

[Prior Art] Various automated visual inspection devices use image input devices that use two-dimensional image input devices.

For illumination in conventional devices, a ring-shaped high-frequency fluorescent lamp or a ring-shaped fiber optic lighting device is used to illuminate the object to be inspected from above. In addition, the reflected light is
Image signals from two-dimensional image input devices, which are often read by dimensional image input devices, are input to the image memory of the image input device, and after binarizing this image data into normal and defective areas, Measuring the defective area within the window,
Defect inspection is performed by this.

[Problems to be solved by the invention] However, the packaged items have various colors such as black, red, green, blue, and gray, and the printing includes various colors, patterns, and characters. Sometimes the same color as the packaging is used. Therefore, in the conventional technology, when the packaging and the packaged item are similar in color, the normal parts (the package and the packaged item without background, tears, and wrinkles) and defective parts (the packaging's tears, wrinkles, etc.) are It was not possible to differentiate the data by binarizing it.

What's more, the packaged items are decorated with ring-shaped lighting! Even if the illumination is performed, the glossiness of the packaging material or the packaged object makes it difficult to differentiate the image data of the normal part and the defective part by binarization, as described above, which is undesirable.

This invention was made based on the above-mentioned background, and its purpose is to eliminate defects such as tears and wrinkles in packages without being affected by the color or pattern printing of packages or packaged items. The object of the present invention is to provide a package inspection device that can accurately inspect packages.

[Means for solving the problem] The present inventors illuminate the inspection surface of the package from the side, and use a two-dimensional image input device from a direction perpendicular to the inspection surface to capture the inspection surface of the package. The present invention has been completed by discovering that inputting defects such as tears and wrinkles as bright spots and detecting the bright spot data included in the image signal of an image input device as defects is effective in achieving the object of the present invention. It has come to pass. In other words, the packaging defect inspection device of the present invention includes an illumination device that illuminates the inspection surface of the package from the side and reflects the defect from the inspection surface as a bright spot or bright line, and an illumination device that reflects the defect from the illuminated inspection object. An image input device that reads light and sends out a two-dimensional image signal.The sent out two-dimensional image signal is digitized within a pre-specified image memory window and compared with a pre-set threshold to determine whether there are defects. An image input device for determining:

In a preferred embodiment of the invention, the transmitted two-dimensional image signal can be binarized.

In a further preferred embodiment of the present invention, the emission part of the illumination device can be shaped like a line or a point extending parallel to the inspection surface.

In another aspect of the invention, the transmitted two-dimensional image signal can be multivalued.

[Function] The present invention having the above configuration exhibits the following function and operation.

The reflectance of the test object is affected by the refractive index of the test object, especially the incident angle of the illumination light. In the case of .49), the relationship between the incident angle of illumination light and the surface reflectance is as shown in FIG. From this figure 6, it can be seen that when the angle of incidence is around 90°, even if the color of the object to be inspected changes, the
The surface reflectance is close to 00%.

Therefore, if side illumination is performed almost parallel to the plane of the object to be inspected, that is, at an angle of incidence close to 90°, even if the object to be inspected is white, it will not be visible to the two-dimensional image input device installed above. The reflected light will not be received.

On the other hand, when the package is torn or wrinkled, the reflected light is scattered even if the inspected object is colorless, transparent, or black, and the illumination light is incident almost parallel to the inspected object's plane. Some are set above! The light is then received by a two-dimensional image input device.

Therefore, by using an illumination device that illuminates the inspection surface of the package from the side, it is possible to input an image of only the tears and wrinkles of the package as bright spots.

The illumination device does not need to be linear, and may be an optical fiber illumination, a fluorescent lamp with a slit, or a laser beam.

In a preferred embodiment of the present invention, the light emitting end of the illumination device is shaped like a line or a point, so that the size of the light source of the illumination device can be reduced, and bright lines can be seen more clearly to eliminate tears and wrinkles in the background and packaging. Alternatively, it can be reflected as a bright spot.

In the image data obtained by reading the illuminated package as described above with a two-dimensional image input device, only the tears and wrinkles of the package have a high CCD output level.

Further, in other parts, the CCD output is small.

This does not affect the color of the package or packaged items, and the CCD output level is low.

Therefore, if the read image data is binarized, it is possible to detect normal parts, backgrounds, and packages and items to be packaged without tears or wrinkles.
, defective parts (torn packaging, wrinkles, etc.) can be distinguished by "1".

To determine whether there is a defective part, set a window in an arbitrary range, check the image data from the edge of the window, and check that the image data changes from "0" to "1". good.

In the above, there are two directions for detecting edges: positive direction (left to right of the window, or top to bottom), and negative direction (right to left of the window, or 2 bottom to top). You can choose which one to do.

Furthermore, if there are variations in the light intensity of the bright spots and it is not possible to detect them with high precision by binarization, the 8-bit image can be processed for edge detection using a Sobel operator or the like.

[Examples] The present invention will be explained by specific examples with reference to the drawings.

Figure 1 shows the defect inspection system for packages of this invention! As shown in this figure, the package inspection device 1 of the present invention includes an illumination device 2 that illuminates the package 5 from the side.
, an image input device W3, and an image processing device 4 that digitizes the transmitted two-dimensional image signal within a pre-designated window of the image memory and compares it with a pre-set threshold to determine the presence or absence of a defect. It consists of

FIG. 2 is a schematic diagram showing an example of the device configuration of the present invention.

First, the device configuration will be explained. Inspection device 1 in this example
is transmitted through an illumination device 2 consisting of a light source 6 and an optical fiber light guide 7 optically connected to the light source, an image input device 3 of an area type CCD camera 8, and a prespecified image memory window range. an image input device 4, which has the function of digitizing the two-dimensional image signal obtained by the package and comparing it with a preset threshold value to determine the presence or absence of a defect, and an image of the package;
A monitor CRT 9 displays the degree of defects, judgment results (OK or NG), and when the package 5 moves to the inspection position on the belt conveyor 11, an inspection start signal is output to the image input device 4. It consists of a photoelectric switch 10.

The inspection package 5 in this example conveyed on the belt conveyor is a VTR tape, and the size is 200 x 105 x 2.
It is 6am. VTR case 4. : Ha, patterns and letters are printed in various colors. In some packaging films, the inspection surfaces are the top and side surfaces (two places), but only the top surface is shown in FIG.

The objects to be inspected 6 are moved on the belt conveyor in a tact manner at a moving speed of 60 pieces/minute, so they are inspected at a speed of less than 1 second/piece.

1 is used with an area type CCD camera. Area type C
The CD camera 1 is used to inspect the top surface, and its inspection range is 190x95as.

The photographing direction of the area type CCD camera 8 can be tilted, for example, by several degrees from perpendicular to the inspection package 5 to increase the intensity of reflected light from wrinkles and the like to facilitate detection.

The image input device 4 of this example has the following functions.

After the image from the area type CCD camera 8 is A/D converted with 8 bits, it is binarized with a preset value and input into the image memory of the input device.

A specified range of this image memory is set as a window, and bright spot detection is performed within this range.

Various bright spot detection methods have been published, but in this example, a Sobel operator was used.

Determine the presence or absence of bright spots using the above method, and if there are bright spots,
Outputs an NG signal, and outputs an OK signal if there is none.

The monitor CRT 9 displays the image of the inspection package 5, the measured value of the bright spot, and the judgment result (OK or NG).

The light source 6 uses a 100W halogen lamp.
The optical fiber light guide 7 has a 1.5X arrangement of the output part.
In the present invention, the output part of the optical fiber light guide 5, which has a diameter of 200 mm, is installed several inches above the inspection package 5 and approximately parallel to the inspection package 5/@5.

The photoelectric switch 10 outputs an inspection start signal to the image input device 4 when the inspection package 5 comes to the inspection position.

In this invention, illumination is performed from the side of the inspection object, and may be by using an optical fiber, a slit in a fluorescent lamp, or a laser beam. Although optical fiber lighting arranged in a line longer than the width of the label was used, point-shaped optical fiber lighting may also be used.

In this invention, side illumination is performed from one direction or from multiple directions, for example, so that bright lines or bright spots of defects can be obtained.
The inspection can be carried out from two directions: the traveling direction of the conveyor through which the inspection object flows and the direction perpendicular to this traveling direction.

Next, the operation of the apparatus shown in FIG. 2 will be explained.

The inspection package 5 is moving toward the front.

When the inspection object 5 reaches the inspection position, the photoelectric switch 1
0, an inspection start signal is input to the image processing device 4. At the same time, when the inspection object 5 reaches the inspection position, the side illumination of the light source 6 and the optical fiber light guide 7 causes the defective portion to be observed as a bright spot and the rest to be observed as black.

When the inspection start signal is input, an image is input by the area type CCD camera 8, and the image data input to the 0 image memory is input to the image memory of the image input device 4.
Binarization is performed using a prespecified threshold value. This image data is also displayed on the monitor CRT9.

Bright spots are detected in the image data of the image memory within a preset window, the presence or absence of a defective part is determined, and if a bright spot is present, an NG signal is output.

Next, a modification of the apparatus shown in FIG. 2 will be described.

Although the package 5 to be inspected is a VTR tape in this example, the present invention is not limited to this.
This can be done with each package.

The area type CCD camera 8 used is one without a shutter function, but if the inspection package 5 moves at a constant speed, it is necessary to use one with a shutter function or use strobe lighting. Become.

Binary data was used as the image data, but multi-value data (8
(bits/pixel) is also possible.

Although a line-shaped output part of the optical fiber light guide 7 is used, a point-shaped output part may be used.

Further, in the case of point-shaped sensors, it is preferable to use a plurality of point-shaped sensors, but if measurement is to be performed at 21 points in the X direction (movement direction), two point-shaped sensors may be used in the X direction.

When there are multiple inspection surfaces, an illumination device and an image input device may be provided for each inspection surface depending on the direction thereof.

FIG. 3 shows an example of the appearance of a VTR tape, which is an example of the object to be inspected according to the present invention.

There are three surfaces to be inspected: a top surface 12, a side surface 13, and a side surface 14. 15 indicates a tear, and 16 indicates a fold of the wrapping paper.

Fourth example showing an example of the image processing range in the inspection device of the present invention
The figure shows the top surface 12, side surface 13, and side surface 14 of the object to be inspected. The inspection range is indicated by the dotted line in the window 17.18.1
9, which is 5 cm inside the VTR tape size. This is to prevent the edge of the VTR tape on the optical fiber light guide side from being detected as a bright spot.

FIG. 5 is a flowchart showing a processing procedure by the apparatus of FIG. 2, which is an example of the inspection apparatus of the present invention.

First, a start signal is input, and the inspection package 5 is
It moves continuously and starts inspection in response to a start signal from the photoelectric switch 10.

Next, image input is performed, and image data is input from three locations: the top surface 12, side surface 13, and side surface 14 of the inspection object.

The same effect was obtained whether the image data was binary data or multivalued data.

Measure bright lines and bright spots from the obtained image data, detect bright lines and bright spots from window air, and determine the presence or absence of defects.

If no bright line or bright spot is detected, step to start signal input.

Finally, an NG signal is output, and if a bright line or bright spot is detected and it is determined that there is a defect, an NG signal is output,
Step to the start signal input of the first step.

[Effects of the Invention] The present invention enables accurate inspection of defects such as tears and wrinkles in packages without being affected by the color or pattern printing of packages or packaged items. It is highly effective as a defect inspection device.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a package defect inspection device of the present invention;
FIG. 2 is a diagram showing an example of a specific configuration of the device of the present invention;
3 is a diagram showing an example of the external appearance of a VTR tape of a package to be inspected by the present invention, FIG. 4 is a diagram showing an example of the image processing range in the apparatus of the present invention, and 55th! i is a flowchart showing the processing procedure in an example of the inspection apparatus of the present invention, and FIG. 6 is a line section showing the relationship between the incident angle and the surface reflectance. 1... Package defect inspection device, 2... Lighting device, 3
Image input device, 4... Image input device, 5. Packaging, 6
・Light source, 7 ・Optical fiber light guide, 8 Area type C
CD camera, 9.Monitor CRT, 1o.Photoelectric switch, 1. Belt conveyor, 12..Top surface, 13..Side surface, 14..Side surface, 15..Tear, 16..Crease,
17...window, 18...window, 19.
...Window patent ff 111 people Mitsubishi Rayon Co., Ltd. (:J6 3rd area θ) b) C)

Claims (1)

[Claims] 1. An illumination device that illuminates the inspection surface of a package from the side and reflects the defect from the inspection surface as a bright spot or bright line; and: reads the reflected light from the illuminated inspection object. An image input device that sends out a two-dimensional image signal: An image that digitizes the sent two-dimensional image signal within a pre-specified image memory window and compares it with a pre-set threshold to determine the presence or absence of defects. A processing device and a package defect inspection device consisting of: 2. Claim 1, wherein the transmitted two-dimensional image signal is binarized.
Defect inspection equipment for the described packages. 3. The package defect inspection device according to claim 1 or 2, wherein the light emitting section of the illumination device has a line shape or a dot shape extending parallel to the inspection surface. 4. Claim 1, wherein the transmitted two-dimensional image signal is multivalued.
Defect inspection equipment for the described packages.