JPH0823530B2 - Object observation apparatus and method for inspecting inner wall surface of cylindrical object using the apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an object observation apparatus that executes predetermined image processing such as measurement using an image obtained by imaging an object, and an object observation apparatus that uses this apparatus, for example. The present invention relates to an inspection method for inspecting the inner wall surface of a cylindrical object such as a cap fitted to a balance port or a container for canning (hereinafter, simply referred to as “cap”).

<Prior Art> FIG. 8 shows an appearance of a cap fitted to a bottle mouth. Conventionally, this type of cap is formed by drawing a metal plate, and when this processing is properly performed, the cap 1 having flat inner and outer wall surfaces as shown in FIG. 8 (1) is obtained. . However, vertical wrinkles 2 as shown in FIG. 8 (2) may be formed on the entire peripheral surface in the vicinity of the opening edge on the inner surface of the cap due to a pressing failure or the like. When the cap 1 having such vertical wrinkles 2 is fitted into the bottle mouth, it causes air leakage and the like, so it is necessary to inspect the inner surface of the cap and remove the cap 1 of this kind as a defective product.

Conventionally, this type of inspection relies on visual inspection by workers, but since the inspection location is the inner surface of the cap, it is not easy to reliably determine the presence or absence of vertical wrinkles and overlook defective products. This causes a decrease in inspection accuracy. Further, since the inspection is performed manually, not only the inspection speed is slow and the inspection efficiency is low, but also the work load on the worker is heavy, which causes excessive fatigue.

Therefore, recently, it has been proposed to automate this kind of inspection by image technology (Japanese Patent Laid-Open No. 62-82344). This device irradiates diffused light on the inner surface of the cap by an annular illumination device having a diffuse reflection surface, and determines the defect on the inner surface of the cap by an image obtained by capturing the reflected light.

<Problems to be Solved by the Invention> However, in the above device, since the diffuse reflection surface is located between the optical system of the imaging device and the object, diffusion from the light source of the illumination device or the diffuse reflection surface is caused. The light is incident on the optical system of the camera, and the diffused light is also diffused to a portion other than the inner surface portion of the cap to be inspected. Therefore, there is a problem that the accuracy of the obtained image is lowered and the inspection result is also inaccurate.

As described above, in order to accurately extract the image of the specific portion of the target object, it is necessary to block the incidence of the illumination light on the optical system of the camera and regulate the irradiation range of the target object.

The present invention has been made to solve the above problems, and when a subject is imaged under illumination by an annular light source and observation processing is performed, a light shielding unit is provided around the optical system of the imaging device. By adjusting the position, it is possible to block the illumination light from entering the optical system and regulate the irradiation range to the target object, and obtain an image that accurately reflects the characteristics of the target object for precise observation. It is an object of the present invention to provide an object observation device that can obtain a result, and an inner wall surface inspection method for a cylindrical object using the object observation device.

<Means for Solving Problems> An object observation apparatus according to a first aspect of the present invention provides an image pickup means for picking up an object, an annular light source arranged around the image pickup means, and illumination light from the annular light source. And an image processing unit that performs a predetermined process using an image captured below, and the observation object is irradiated with illumination light from the annular light source around the optical system of the imaging unit. However, a light shielding portion is provided to prevent the light from directly entering the optical system, and the position of the light shielding portion is adjusted so that the illumination light from the annular light source irradiates only a predetermined area of the observation target. I have to.

A second invention is a method for inspecting the inner wall surface of an object using an image obtained by imaging a cylindrical object, wherein an annular light source is provided around the imaging means. By blocking the incidence of illumination light from the annular light source to the optical system of the imaging means at a predetermined position between the annular light source and the object, and irradiating the illumination light only on the bottom surface of the object to diffusely reflect the illumination light. The indirect illumination light for irradiating the inner wall surface of the object is generated, and the reflected light of the indirect illumination light is imaged by the imaging means.

<Operation> By providing a light-shielding portion around the optical system to block the illumination light from entering the optical system and adjusting the position of the light-shielding portion, the illumination light from the annular light source can be emitted only in a predetermined area of the observation target. Since the irradiation range of the illumination light is regulated so as to irradiate the object, only a specific position of the observation object can be illuminated and an appropriate and accurate observation result can be obtained.

Furthermore, in the second invention, the illumination light is blocked from entering the optical system between the annular light source and the cylindrical object, and the illumination light is diffusely reflected by irradiating only the bottom surface of the object. Indirect illumination light due to irregular reflection is applied to the inner wall of the object. An image obtained by picking up the reflected light from the inner wall makes it possible to highly accurately determine a defect occurring on the inner wall.

<Embodiment> FIG. 1 shows a wrinkle inspection device for an inner surface of a cap according to an embodiment of the present invention. In this example of the apparatus, the inspection target is the metal cap fitted in the bottle mouth, but the present invention is not limited to this, and the inspection object can be a canned container or the like.

The apparatus shown in the figure is for inspecting a large number of daily inspection objects 4 conveyed by the conveyer conveyor 3 at a predetermined inspection position one after another at high speed for the presence or absence of vertical wrinkles on the inner wall surface of the cap. 6, video monitor 7, light pen 8, object detection sensor 9, strobe lighting device 10, strobe control device 1
It is composed of 1 etc.

The TV camera 5 is, for example, a two-dimensional CCD camera,
The video signal VD for imaging the inspection object 4
_i is given to the controller 6. The controller 6 binarizes the video signal VD _i from the television camera 5 and executes various calculations and processing relating to wrinkle inspection. The video monitor 7 displays an image of the inspection object 4 and the like, and also displays a menu and measurement / judgment results. The light pen 8 is used for menu selection and the like, and sets an inspection program in combination with the video monitor 7. The object detection sensor 9 is a photoelectric switch or the like and detects that the inspection object 4 has reached the inspection position. The strobe illumination device 10 uses, for example, a ring strobe as a light source, and applies strobe illumination to the moving object 4 to be inspected to form a still image. The strobe control device 11 performs control regarding strobe light emission, for example, control such as light emission prohibition at the light reception prohibition timing of the television camera 5.

The television camera 5 and the strobe lighting device 10 are individually mounted on columns (not shown) so that their heights can be adjusted, and after adjusting their respective heights with respect to the object 4 to be inspected, they can be fixed to the positions with screws or the like. Has become.

FIG. 2 shows an example of an assembly structure of the television camera 5 and the strobe lighting device 10. The strobe lighting device 10 surrounds the TV camera 5 with the wide-angle lens 12 mounted at the center. It has been deployed.

Although the strobe lighting device 10 in the illustrated example uses the ring strobe 13 as a light source, it may have a structure in which glass fibers are arranged in a ring and the light of the filament is guided by each glass fiber. The ring strobe 13 is housed in a housing 14, and a diffusion plate 41 is arranged in the irradiation direction of strobe light source light.

Further, the strobe lighting device 10 has a configuration for restricting the irradiation range of the strobe light source light by the ring strobe 13 and for restricting the strobe light source light from directly irradiating the inner wall surface of the inspection object 4. It includes a light-shielding hood 15 attached to the wide-angle lens 12 of the television camera 5 and a light-shielding plate 16 disposed below the strobe lighting device 10.

The light-shielding hood 15 is the ring strobe 13 and the inspection object 4
Is provided between the wide-angle lens 12 and the wide-angle lens 12 to block the incident light to the wide-angle lens 12 and to restrict the direct irradiation of the inner wall surface of the inspection object 4 with the strobe light source light. By adjusting the mounting position to the front and back, the tip edge of the light shielding hood 15 can be moved back and forth between the ring strobe 13 and the inspection object 4. The light-shielding hood 15 may be a dedicated hood or a lens hood.
Further, by forming the light-shielding hood 15 in a structure capable of expanding and contracting in the radial direction, the tip edge of the light-shielding hood 15 can be advanced and retracted between the ring strobe 13 and the inspection object 4.

The light shielding plate 16 is a black bakelite plate having a circular hole 17 in the center thereof, and is for preventing the strobe light source light from irradiating the outer wall surface of the inspection object 4. In the case of this embodiment, the irradiation range is adjusted by adjusting the vertical position of the light shielding plate 16. However, the irradiation range may be adjusted, for example, by forming the circular hole 17 to be expandable and contractible.

The strobe light source light regulated by the light shielding hood 15 and the light shielding plate 16 is guided to the inner bottom portion of the inspection object 4. In the case of the illustrated example, a milk-white resin packing 20 is attached to the inner surface of the bottom of the inspected object 4, and the strobe light source light is diffusely reflected on the surface of the packing 20 to be generated as indirect illumination light. The indirect illumination light is applied to the inner wall surface of the inspection object 4, particularly near the opening edge where vertical wrinkles occur. When such indirect illumination is optimally performed, the binary image obtained by imaging the non-defective product is an image 18 of the object to be inspected as shown in FIG. 4 (1).
Appears in white, the background portion (indicated by diagonal lines in the figure) appears in black, and the binary image obtained by imaging the defective product shows a white image 18 of the object to be inspected as shown in FIG. 4 (2). A vertical wrinkle image 19 will appear in the circle.

FIG. 3 shows a circuit configuration example of the controller 6 in the wrinkle inspection apparatus. In the figure, the television camera 5 picks up an image of the inspection object 4 and outputs a video signal VD _i ,
Takes in the video signal VD _i and binarizes it to generate a binary image. The binarization threshold control unit 24 uses the video signal VD
A threshold value for binarizing _i is set to control the binarizing process of the binarizing unit 23.

The reference pattern storage memory 25 is for registering a binary image obtained by imaging a non-defective sample as a reference pattern, and the measurement pattern storage memory 26 is an image obtained by imaging the inspection object 4. Is stored as a measurement pattern. The window storage memory 27 is a portion for storing an observation window and a measurement window which will be described later, and the memory control unit 28 controls reading and writing of image data with respect to each of the memories 15 to 17.

The observation window is for defining the observation range of the binary image, and is formed to have a sufficient size to include the cap image 18 as shown by W ₁ in FIG. 4 (1). Further, the measurement window is for observing the bright and dark image 19 of the vertical wrinkles in this image 18, and as shown by W ₂ in FIGS. 4 (1) and (2), it is slightly concentric with the image 18 and slightly out of the contour of the image 18. It is formed in a ring shape with a small diameter.

Next, the arithmetic processing unit 29 executes the arithmetic operation for obtaining the barycentric position of the contour of the binary image and the arithmetic operation for counting the number of black pixels in the measurement window W ₂ under the control of the arithmetic control unit 30. Further, the central processing unit 31 decodes and executes the program of the ROM 32, reads and writes data to and from the RAM 33, and determines the shift amount of the position of the center of gravity of the binary image, and the presence or absence of wrinkles from the measurement result of the number of black pixels. Performs various processes such as The address control unit 34 generates addresses of the ROM 32 and the RAM 33 and controls reading / writing of instructions and data. Central processing unit 31
Controls the input / output operation, takes in a detection signal from the object detection sensor 9 through the measurement synchronization input interface section 36, and outputs a strobe trigger signal for strobe emission through the strobe control interface section 37 for determination output. The determination signal is output via the interface unit 37.

The display synthesizing unit 38 takes in a grayscale image from the television camera 5 based on the designation from the display image designating unit 39, or reads out a binary image or a window stored in each of the memories 25 to 27, and if necessary, This is for synthesizing images, and the image is the video monitor interface
It is sent to the video monitor 7 via 40.

Next, the operation of the above apparatus example will be described based on the flowcharts shown in FIGS. 5 and 6.

FIG. 5 shows a procedure for setting various inspection parameters in the above-mentioned apparatus example. First, in step 1 of FIG.
1)), a good quality sample is imaged by the TV camera 5 under natural illumination, a grayscale image of the good quality sample is displayed on the video monitor 7, and the focus of the TV camera 5 is capped while watching the image. Adjust the focus so that it fits near the opening edge. In the next step 2, the waveform display is designated by the display image designation unit 39 to display the video signal waveform at the proper place on the image on the video monitor 7, and then the aperture of the television camera 5 is adjusted while watching the waveform.
Finally, in step 3, the strobe lighting device 10 images the defective sample under illumination, and while observing the waveform display, the positions of the ring strobe 13 and the light shielding hood 15 are adjusted, and the imaging target and the background are displayed on the signal waveform. Set so that the level difference of is sufficiently large. Next, in step 4, the non-defective sample is imaged and the same fine adjustment is performed, and then in step 5, the position of the light shielding plate 19 is adjusted while observing the waveform.

Next, in step 6, the non-defective sample and the defective sample are binarized alternately by the binarization unit 23, and the binarization level is adjusted so that the two can be easily discriminated. The binary image of the sample is registered in the reference pattern storage memory 25 as a reference pattern.

Next, in step 8, the measurement window W _{2 is} added to the inspection area of the reference pattern (the portion where the bright and dark images of the vertical wrinkles appear).
After setting, the number of black pixels in the measurement window W ₂ is measured by the arithmetic processing unit 29 in the next step 9, and the measured value is set in the RAM 33 as an allowable value. Next, in step 10, for the binary image of the defective sample and the binary image of the other non-defective sample, the number of black pixels in the measurement window W ₂ is measured by the arithmetic processing unit 29, and the allowable value is finely adjusted. Then, in the following Step 11, the observation window W ₁
In 12, the measurement synchronization conditions and strobe emission intensity are set, and the inspection parameter setting work is completed.

FIG. 6 shows the procedure of wrinkle inspection of the inspection object 4 by the above-described example of the device, and step 21 in the figure determines whether the inspection object 4 has reached a predetermined inspection position. When the object to be inspected 4 on the transport conveyor 3 is detected by the object detection sensor 9, the detection signal is given to the central processing unit 31 of the controller 6, and the determination in step 21 becomes "YES". In the next step 22, the central processing unit 31 judges whether or not it is during the strobe light emission prohibition period. If the judgment is "NO", a strobe trigger signal is immediately given to the strobe controller 11, and the judgment is " In the case of "YES", after performing the delay operation for the prohibition period (step 23), a strobe trigger signal is given to the strobe control device 11 so that the ring strobe 13 of the strobe lighting device 10 emits strobe light at each timing ( Step 24).

The strobe light source light at this time is diffused by the diffusion plate 41, and then the diffused light is guided to the inside of the inspection object 4 by the restriction action of the light shielding hood 15 and the light shielding plate 16, and the inner wall surface of the inspection object 4 is inspected. The packing 20 on the bottom is irradiated without being directly irradiated onto the packing. As a result, the irradiation light is diffusely reflected by the packing 20 to be generated as indirect illumination light, and the indirect illumination light is applied to the inner wall surface of the inspection object 4.

Under this indirect illumination light, the television camera 5 images the object 4 to be inspected, the video signal VD _i thereof is binarized by the binarization unit 23, and the binary image is a measurement pattern storage memory. It is stored in 26 (step 25).

Next, in step 26, the arithmetic processing unit 29 extracts the contour of this measurement pattern, then calculates the center of gravity of the contour, and in the next step 27, calculates the amount of displacement of this center of gravity from the center of gravity of the contour of the reference pattern. calculate.

FIG. 7 shows a state in which the center of gravity G of the measurement pattern and the center of gravity G _{0 of the} reference pattern are misaligned. In the figure,
(X, Y) is the coordinate of the center of gravity G of the measurement pattern, and (X ₀ ,
Y ₀ ) indicates the coordinates of the center of gravity G ₀ of the reference pattern, and the positional deviation amounts ΔX and ΔY of the center of gravity G with respect to the center of gravity G ₀ are as follows.

ΔX = X−X ₀・ ・ ・ ΔY = Y−Y ₀・ ・ ・ Next, the arithmetic processing unit 29 shifts the position of the center of gravity ΔX, ΔY.
After correcting the position of the measurement pattern based on, the measurement window W ₂ is set for the corrected measurement pattern, and the number of black pixels in the window is measured (step 28). The measured value is given to the central processing unit 31, and the central processing unit 31 determines whether or not the measured value is within a predetermined allowable value (step 29). As a result, when the count value is within the allowable value, the inspection object 4 is determined to be a good product, but when the count value exceeds the allowable value, the inspection object 4 is determined to be a defective product. Then, in step 30, the inspection object 4 is removed from the transfer line.

<Effects of the Invention> As described above, according to the present invention, a light-shielding portion is attached to the periphery of the optical system of the image pickup means to block the incidence of illumination light of the optical system from the annular light source by the light-shielding portion, and a predetermined area of the observation object. Since the position of the light shield is adjusted so that only the illumination light is irradiated, the illumination light from the annular light source is blocked from entering the optical system, and the irradiation range from the annular light source to the observation object is regulated. It is possible to obtain detailed and accurate observation results by irradiating only a specific part of the observation object.

Further, in the second invention, at the time of inspecting a cylindrical object, incidence of illumination light from the annular light source to the optical system is blocked between the annular light source and the inspection object, and this illumination light is made to reach the bottom surface of the inspection object. Since the indirect illumination light for irradiating the inner wall surface is generated by irradiating only the inner wall surface, the inner wall surface of the object can be precisely inspected.

[Brief description of drawings]

FIG. 1 is an external view showing a schematic configuration of a wrinkle inspection apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged view showing an assembly structure of a television camera and a strobe lighting device, and FIG. 3 is a controller. 4 is a block diagram showing an example of the circuit configuration of FIG. 4, FIG. 4 is an explanatory view showing binary images of a non-defective product and a defective product, FIG. 5 is a flowchart showing a procedure for setting inspection parameters, and FIG. 6 is a flowchart showing a procedure for wrinkle inspection. FIG. 7 is an explanatory view showing a state of displacement of the center of gravity, and FIG. 8 is a perspective view showing appearances of good and defective caps. 1 ... Cap, 4 ... Inspected object 5 ... TV camera, 6 ... Controller 10 ... Strobe lighting device, 11 ... Strobe control device 13 ... Strobe light source, 15 ... Shading hood 16 ... Shading plate , 20 …… Packing

Claims (2)

[Claims] 1. A predetermined process is executed using an image pickup means for picking up an image of an object, a ring-shaped light source arranged around the image pickup means, and an image picked up under illumination light from the ring-shaped light source. And an image processing means for performing light shielding for preventing the illumination light from the annular light source from irradiating the observation object but not directly entering the optical system around the optical system of the imaging means. The object observing device is provided with a section, and the position of the light shielding section is adjusted so that the illumination light from the annular light source irradiates only a predetermined region of the observation object. 2. A method for inspecting an inner wall surface of an object using an image obtained by imaging an object having a cylindrical shape, wherein an annular light source is provided around the imaging means, By blocking the incidence of illumination light from the annular light source to the optical system of the imaging means at a predetermined position between the annular light source and the object, and irradiating the illumination light only on the bottom surface of the object to diffusely reflect the object A method for inspecting an inner wall surface of a cylindrical object, which comprises generating indirect illumination light for irradiating the inner wall surface of the object and imaging the object under the indirect illumination light.