JPH095056A - Surface deformation inspection device - Google Patents

Abstract

PURPOSE: To detect deformation, together with its magnitude, of a material surface to be inspected. CONSTITUTION: Strip-shaped light sources 6 are disposed so that they project light obliquely from both sides of a linear sensor 5, with an optical system plane through which light incident on the linear sensor 5 passes matching with ridgeline of a can 1, and the light regularly reflecting thereon is not incident on the linear sensor 5. The can 1 is rotated by a rotating device 2 and its rotational positions are detected by an encoder 3. A two-dimensional picture image is produced from the rotational positions and outputs of the linear sensor 5 by a picture image processor, the picture image being binary-processed, and deformation is detected and its magnitude is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the surface deformation of an object to be inspected, and more particularly to a surface deformation inspection apparatus for inspecting the surface deformation of a can or the like.

[0002]

2. Description of the Related Art In the case of an aluminum can filled with beer or the like, when a mouth of the aluminum can filled with a liquid such as beer is wound with a seamer to seal it, a rotating force is applied to the lid of the can. Buckling occurs due to the shearing force generated on the side of the
Buckling deformation such as elongated linear depressions in the circumferential direction occurs on the surface of the can. Several methods for inspecting such deformation have been proposed in the past.

[0003]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 7-31137
In the publication, the entire circumference of the can is captured as a plurality of images, and each image is compared with a previously captured normal image, and if there is a difference, it is determined as a defect. However, since a difference occurs due to the shift of the imaging position between the normal image and the inspection image, in order to avoid this, the normal image is compared with a slightly thickened or thinned normal image. As described above, there are problems that a process for changing a normal image is necessary and that it is difficult to determine a printing defect and a defect due to deformation.

In Japanese Examined Patent Publication No. 3-52015, a cylindrical object is imaged from a plurality of directions to discriminate stains or scratches on print marks, characters, etc. Regions are divided in the circumferential direction, and normal patterns and detected patterns are represented by combinations of the regions, and the defects are detected by comparison. However, in this case, there is a problem that a defect similar to a print mark cannot be identified.

Japanese Patent Publication No. 4-29021 discloses a method of illuminating the surface of an object to be inspected with an incline obliquely and comparing the light amounts of light and dark images of the indented part to detect an indentation or the like. However, there is a problem that the illumination is only from one direction and the size of the defect is unknown.

Japanese Patent Publication No. 6-54224 discloses a technique for detecting the three-dimensional shape of an object to be inspected by using a laser beam. However, when the position of the object to be inspected is not constant or the object to be inspected is not constant. There is a problem that the position of the reflected image of the laser is easily deviated when the surface changes in distance with respect to the image pickup device.

Japanese Patent Publication No. 10583/1992 discloses a method of detecting an abnormality on the surface of an object from the ratio of vertical reflection and oblique reflection by performing vertical illumination and oblique illumination from the same light source with a light emitting and receiving set using an optical fiber. However, there is a problem that the size of the defect is unknown.

There is also a method of projecting a parallel slit light group on the surface of an object to be inspected and imaging a striped pattern to determine the stripe distortion, but an optical system for generating a large number of slit beams and a striped pattern. The strain detection / analysis system was required, resulting in a complicated device.

The present invention has been made in view of the above-mentioned problems, and a surface on which the deformation of the surface of the object to be inspected can be detected relatively easily and the size thereof can be detected relatively easily. An object is to provide a deformation inspection device.

[0010]

In order to achieve the above object, according to the invention of claim 1, a linear sensor for imaging an object to be inspected and the object to be inspected in a plane of an optical system through which light incident on the linear sensor passes. An object is illuminated obliquely from both sides of the linear sensor with respect to the object to be inspected, and a strip-shaped light source arranged so that reflected light from a non-deformed location does not enter the linear sensor, and the object to be inspected is the linear object. A moving unit that moves in a direction substantially orthogonal to the optical system plane of the sensor, a moving amount detecting unit that detects the moving amount of the moving unit, and a two-dimensional image from the detected moving amount and the output of the linear sensor. Image generating means for generating and analyzing the two-dimensional image,
And a deformation detecting means for detecting the deformation of the surface of the inspection object.

According to a second aspect of the present invention, the deformation detecting means connects the adjacent point-like images appearing in the two-dimensional image to each other, and judges that the combined length is equal to or more than a certain value as the deformation. The combined length is the length of deformation.

In the third aspect of the present invention, the belt-shaped light source is a light-emitting source, a light guide for guiding the light from the light source, a distributor for converting the light from the light guide into belt-shaped distributed light, and light from the distributor. And a cylindrical lens for condensing the light.

[0013]

According to the first aspect of the invention, the object to be inspected is illuminated within the plane of the optical system of the linear sensor, and the reflected light from the surface of the illuminated object to be inspected is reflected from the undeformed portion. Light does not enter the linear sensor, but at least part of the reflected light of the deformed portion enters the linear sensor. The belt-shaped light source obliquely irradiates the object to be inspected from both sides of the linear sensor, and when there is a depression or a projection-like deformation in the irradiated portion, the reflected light from this deformation is incident on the linear sensor. Band-shaped light sources are arranged on both sides of the linear sensor so that reflected light is emitted from both the descending shape and the ascending shape of the depressions and protrusions and is incident on the linear sensor. The inspection object is moved by the moving means in a direction substantially orthogonal to the optical system plane of the linear sensor,
The image incident on the linear sensor changes. The image generating means generates a two-dimensional image from the movement amount and the output of the linear sensor, and the deformation detecting means analyzes the two-dimensional image to detect the deformation. As a result, the deformation can be distinguished from the printed matter and detected relatively easily. In addition, when the deformation has an indentation or a protrusion region that is close to a linear shape, it is preferable that the scanning direction of the linear sensor and the deformation direction intersect so as to be close to a right angle. The strip light source is located in the optical plane of the linear sensor and illuminates the inspection area in a strip shape diagonally from both sides of the linear sensor, so that the inspection area is illuminated correctly even if the distance between the linear sensor and the inspection surface changes. .

According to the second aspect of the present invention, the reflected light reflected by the depressions or protrusions is not incident on the linear sensor from a certain angle among the angles of the descending and ascending shapes of the depressions or protrusions. In many cases, even if the deformation is continuous, the image obtained from the linear sensor is a collection of separated points. For this reason, point-like images that are close to each other are connected to each other, and those having a length equal to or greater than a certain value are modified to be distinguished from those due to noise. In addition, this combined length is the length of deformation.

According to the third aspect of the present invention, the belt-shaped light source is guided by the light emitting source and a plurality of optical fibers for guiding the source light, or one light guide made of a transparent resin such as a quartz rod or acrylic. The distributed light becomes strip-shaped distributed light, and the cylindrical lens irradiates the object to be inspected.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a configuration of an embodiment of the present invention, FIG. 1A is a side view, and FIG. 1B is a sectional view taken along line XX of FIG. In this embodiment, the deformation of a cylindrical surface such as a beer can or juice can, for example, when the mouth of an aluminum can filled with a liquid such as beer is tightly wound with a seamer and sealed, rotation is applied to the lid of the can. This device detects buckling deformation caused by the shearing force generated on the side surface of the can, and detects an elongated recess formed in the circumferential direction of the can.

Reference numeral 1 is a can of the object to be inspected. Characters and patterns are printed on the surface of the can, and the undeformed surface is glossy and specularly reflects the irradiation light. 2 is a rotating device for rotating the can 1, 3
Is an encoder that detects this rotational position. 4 is a can 1
It is a can holder rotation plate that holds down and rotates smoothly. Reference numeral 5 is a linear image sensor, which is a line sensor with a camera, and is arranged so that the scanning line of the linear image sensor 5 is parallel to the central axis C of the can 1. A plane including the center line C of the can 1 and a line where the image pickup elements of the linear image sensor 5 are arranged is referred to as an optical system plane of the linear image sensor 5. Reference numeral 6 denotes a band-shaped light source, which is symmetrically arranged with respect to the linear image sensor 5. The band-shaped illumination light passes through the above-mentioned optical system plane, illuminates the ridge line 7 of the can 1, and specularly reflected light is directed to the linear image sensor 5. It is arranged obliquely to the ridge line 7 of the can 1 so as not to enter. With such a configuration, the ridge line 7 of the can 1
The linear image sensor 5 captures an image of the linear inspection area of the ridge line 7 that is illuminated by the linear light source 6, and the can 1 is rotated to capture an image of the entire circumference of the can 1.

FIG. 2 is a view showing an example of the strip light source 6.
The halogen lamp 10 is covered with a spherical reflection mirror 11, and light is incident on a fiber bundle composed of a large number of optical fibers 12. The optical fiber array 13 forms a distributor by arranging the fibers of the fiber bundle in one row in a strip shape, and a cylindrical lens 14 is provided at the tip to act as a condenser lens. As a result, band-shaped light can be emitted. 1 instead of using a cylindrical lens
You may use the slit which combined individually or more than one.

FIG. 3 is a view showing another example of the strip light source 6. (A) shows a vertical cross-sectional view, and (B) is a horizontal cross-sectional view of the distributor. Halogen lamp 10 and spherical reflection mirror 11
To form a light emitting light source. The reflection mirror 11 is connected to the quartz rod 15 and guides the light of the halogen lamp 10 to a distributor 16 which distributes the light into band-shaped light. The distributor 16 is a transmission triangular prism plate 16a forming a top wall as shown in FIG.
And a triangular prism plate 16b for reflection, which constitutes a side wall and a bottom wall,
An end plate 16c forming an end plate and an end plate 16d forming a connecting portion with the quartz rod 15 are formed. The direction of the prism is the direction orthogonal to the irradiation light from the quartz rod 15 in the transmitting triangular prism plate 16a, and the reflecting triangular prism plate 1
In 6b, the direction is the same as the irradiation light. Quartz rod 1
Part of the irradiation light from No. 5 is directly incident on the transmitting triangular prism plate 16a, and the rest is reflected by the reflecting triangular prism plate 16a and the mirror plates 16c and 16d, and then is incident on the transmitting triangular prism plate 16a, and quartz. The light emitted from the rod 15 is almost perpendicular to the light emitted from the rod 15, and is emitted as a band-shaped light by the cylindrical lens 14. The quartz rod 15 may be made of a transparent resin such as acrylic.

FIG. 4 is a block diagram showing the structure of the image analysis apparatus. The interface 20 of the linear image sensor 5 outputs the synchronization signal c to the linear image sensor 5,
Enter image information. Also, an encoder pulse representing the rotational position of the can 1 and a start pulse are input from the encoder 3. The input analog image information is converted into digital data and is output in synchronization with the pulse signal of the encoder 3. The input buffer 21 temporarily stores this digital data. The program memory 22 stores a program that defines the operation of this device, and according to this program, the CPU 2
Reference numeral 3 controls the entire apparatus, and the image processor 24 performs gradation processing, binarization processing, image analysis, etc. of the input image data. The grayscale image memory 25 stores the grayscale image data,
The binarization memory 26 stores the binarized image data. The output buffer 27 temporarily stores the data to be output, the D / A converter 28 converts this output from digital to analog data, and the CRT 29 displays this output data on the screen.
The operator inputs instructions and data from the keyboard 30.

FIG. 5 shows a time chart of the interface 20 of the linear image sensor 5. Start signal a
To start the operation. Encoder pulse b is 1 of can 1
For example, 1000 pulses are output per rotation, but they can be thinned out by setting with a DIP switch. Horizontal scanning is performed by the synchronizing signal c from the interface 20, and the analog video signal d is input in synchronization with this. The signals a to c are asynchronous signals, and c and d
Is a synchronization signal. a, b, d are input signals, and the data processing of the interface 20 is performed based on these signals. The input video signal d is converted into 8-bit digital data, and the video signal for one scan immediately after the encoder pulse b is input is written in the line memory of the interface 20 as the 1H video signal e. Next, the data of this e is converted into the data from the address 0, and is output as the interface output f from the next encoder pulse. Along with this, the vertical synchronizing signal g and the horizontal synchronizing signal h
Is output. The horizontal synchronizing signal h is a signal synchronized with the encoder pulse b.

FIG. 6 is a diagram for explaining a method for detecting the hollow portion of the can 1. The linear image sensor 5 and the belt-shaped light source 6 are arranged so that the reflected light k of the light emitted from the belt-shaped light source 6 on the ridge line 7 of the can 1 is specularly reflected and does not enter the linear image sensor 5. However, in FIG. 6, among the irradiation light that hits the recess 32 by the irradiation light from the belt-shaped light source 6a on the right side, the recess 32
The reflected light m of the irradiation light that hits a certain inclination is incident on the linear image sensor 5. Similarly, the band-shaped light source 6 on the left side
Reflected light n of the irradiation light that hits a certain inclination of the recess 32 by the irradiation light from b also enters the linear image sensor 5.
In this way, by irradiating the linear image sensor 5 obliquely from the left and right, the recessed portion 32 can be captured. The incident light does not have a continuous shape due to the inclination of the depression, but becomes a dotted dot shape. If there is a protrusion, it can be captured in the same manner.

Next, the operation of this embodiment will be described. As shown in FIG. 1, a beer can 1 to be inspected is set on a rotating device 3, is pressed by a can pressing rotary plate 4, and is rotated at a constant speed. An encoder pulse that indicates the rotational position is output from the encoder 3 that is directly connected to the rotary shaft of the rotating device 3. At the same time, the strip-shaped light source 6 is turned on to irradiate the ridge line 7 of the can 1. The linear image sensor 5 receives a one-dimensional image centered on the ridge line 7 and having a predetermined width.
One scan is performed for each horizontal synchronizing signal input from 0, and the analog video signal d shown in FIG. 5 is output. Since the interface output f obtained by digitizing the video signal d is output for each horizontal synchronizing signal h synchronized with the encoder pulse b, a two-dimensional image can be obtained by moving and displaying this in the vertical direction. The image processor 24 shown in FIG. 4 binarizes the input image into a binary image and stores it in the binarization memory 26. In this binary image, the image of the portion input by the reflection of the depression 32 or the projection is represented as a set of points having a size. An operation flow for detecting a deformation such as a dent or a protrusion from this binary image will be described.

FIG. 7 is an operation flow chart of the image analysis apparatus shown in FIG. The image input to the linear image sensor 5 is output to the interface 20 as a video signal and is output from the interface 20 as digital image data. This image data is input via the input buffer 21 (S1), and the image processor 24 performs image processing. First, the reflection part is extracted by the shading process (S2). The reflection portion is an image formed by reflection from a deformed portion such as a dent or a protrusion on the surface of the can 1, and is composed of a shining portion. The density near the boundary between the shining part and the dark part is extracted by amplifying the density difference by gradation conversion. Next, the extracted reflection portion is binarized to obtain a binary image (S3).

FIG. 8 shows an example of a binary image of the can 1. The collection of central dots represents the depression 32 of the can 1. The thick lines on both ends represent the irregularities on the top and bottom of the can. Since the top and bottom of the can are not a cylindrical surface but have irregularities and have strength, they are not subject to inspection, and the part excluding this part is defined as an inspection area in advance, and the inspection area is cut out to set a frame ( S4). A thickening process for connecting adjacent points is performed on the binary image of the inspection area (S5). By this connection, one defect (deformation) is displayed. However, since the length of deformation (the length of the binary image in the direction perpendicular to the scanning line of the linear image sensor) is measured, the deformation is contracted to the length of the binary image shown in FIG. 8 in the direction perpendicular to the scanning line. FIG. 9 shows a thickened image obtained by subjecting the binary image of FIG. 8 to the thickening process and the contraction process in the length direction. Horizontal lines at equal intervals represent scales for reading the length of deformation. The length of this thickened image is measured (S6), and this length is compared with a preset value A as a reference value for inspection (S7). If the set value A or less, the can 1 is a good product (S8), and if the set value A is exceeded, it is a bad product (S9), and the result is output by image display or the like (S1).
0). The length of the deformation on the binary image is accurately measured by previously measuring the ratio of the known length on the surface of the can 1 to the length represented by the binary image. be able to.

As described above, the deformation of a cylindrical surface such as a can can be detected and the length thereof can be measured. However, the object to be inspected 1 is made flat and the linear image sensor 5 is used.
By moving in the direction perpendicular to the scanning line and detecting the amount of this movement by the number of pulses of the encoder, the planar surface deformation can also be detected. In this case, the strip light source 6
Is radiated from both sides of the linear image sensor 5 obliquely with respect to the inspection object 1 in the plane of the optical system of the linear image sensor 5 as in the case of the can 1. When detecting a linear concave or convex deformation, the linear sensor may have a longitudinal direction in the direction perpendicular to the linear direction.

Further, in the embodiment, the shining portions of the binary image are combined by expanding, and further reduced to the original binary image in the direction perpendicular to the scanning line. However, numerical reduction is performed instead of reduction. Alternatively, instead of the expansion processing, the setting value A may be a value obtained by adding the double length of the expanded pixel to the original binary image.

[0028]

As is apparent from the above description, the present invention is directed to the object to be inspected diagonally from both sides of the linear sensor.
By irradiating the band-shaped light source within the plane of the optical system of the linear sensor, it is possible to detect the deformation of the depressions or protrusions and measure the length thereof. Since the deformation is measured from the image of the reflected light from the deformed part of the inspection object, the measurement is not affected by the printing of characters or patterns on the surface of the inspection object.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present embodiment, (A) is a side view,
(B) is an XX sectional view of (A).

FIG. 2 is a diagram showing an example of a configuration of a strip light source.

FIG. 3 is a diagram showing another example of the configuration of the strip light source.

FIG. 4 is a block diagram illustrating a configuration of an image processing apparatus according to an embodiment.

FIG. 5 is a timing chart of an interface of the image processing apparatus.

FIG. 6 is a diagram illustrating reflection from a hollow portion.

FIG. 7 is an operation flow diagram of image analysis.

FIG. 8 is a diagram in which an image of a depression is binarized and is represented as a collection of light spots.

FIG. 9 is a diagram in which a group of light spots shown in FIG. 8 are connected, expanded, and represented as one dent.

[Explanation of symbols]

 1 Can 2 Rotating Device 3 Encoder 4 Can Holding Rotating Plate 5 Linear Image Sensor 6 Linear Light Source 7 Ridge Line 10 Halogen Lamp 11 Reflection Mirror 12 Optical Fiber 13 Optical Fiber Array 14 Cylindrical Lens 15 Quartz Rod 16 Distributor 16a Transmission Triangular Prism Plate 16b Reflective triangular prism plate 16c, 16d End plate 20 Interface 23 CPU 24 Image processor 25 Gray image memory 26 Binary memory 32 Recess

Claims (3)

[Claims] 1. A linear sensor for imaging an object to be inspected, and the object to be inspected is obliquely illuminated from both sides of the linear sensor within an optical system plane through which light incident on the linear sensor passes. A belt-shaped light source arranged so that reflected light from a non-deformed location does not enter the linear sensor, and a moving means for moving the inspection object in a direction substantially orthogonal to an optical system plane of the linear sensor, A movement amount detection means for detecting the movement amount of the movement means, an image generation means for generating a two-dimensional image from the detected movement amount and the output of the linear sensor, and an analysis of the two-dimensional image, A surface deformation inspection apparatus, comprising: a deformation detection unit that detects deformation of the surface of the inspection object. 2. The deformation detecting unit connects adjacent point-like images appearing in the two-dimensional image to each other, determines that the combined length is a certain value or more as deformation, and determines the combined length. The surface deformation inspection apparatus according to claim 1, wherein the deformation length is set. 3. The band-shaped light source comprises a light-emitting source, a light guide for guiding the light from the light source, a distributor for converting the light from the light guide into a band-shaped distributed light, and a cylindrical body for collecting the light from the distributor. The surface deformation inspection apparatus according to claim 1, wherein the surface deformation inspection apparatus comprises a lens.