JPH06347226A - Visual inspection apparatus for inner surface of deep bottom product - Google Patents

Abstract

PURPOSE:To improve the inspection accuracy and efficiency of visual inspection for the inner surface of a deep-bottom product. CONSTITUTION:The position of a concave lens in the optical-axis direction at the upper side of a cup C is adjusted by the manipulation of a handle 17. The obtained virtual image P of the inner surface of the cup C is contained within the focal depth of a camera 12. A zoom ratio is adjusted by moving a zoom lens 12a, and the image is focused on the full imaging plane. Thus, the entire image of the cup C can be picked up by one time without the out of focus. The large entire image is obtained as much as possible, and the inspection accuracy is also secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for inspecting the inner surface of deep-bottomed articles such as paper or plastic cups stored in a vending machine, and more particularly, to improve inspection efficiency while ensuring inspection accuracy. Regarding technology.

[0002]

2. Description of the Related Art By visually observing the inner surface of a deep-sealed article such as a cup made of paper or other material, minute holes, dirt, flaws, dent wrinkles,
Inspecting for defects such as tears and molding defects (hereinafter simply referred to as defects) causes severe eye fatigue and results in poor efficiency after long-term inspections, leading to lower inspection accuracy and unfavorable health conditions. .

Therefore, an automatic visual inspection method is conceivable, in which an imaging device such as a camera is used to image and analyze the inner surface of a deep-sealed article.

[0004]

However, as described above, when an image is picked up by a normal camera, if the image is picked up from above the article, the image of the inner peripheral side surface has a smaller image pickup area than the bottom surface. Therefore, in order to simultaneously inspect the appearance of the inner peripheral side surface and the bottom surface of the deep-sealed article with high accuracy, the inner surface composed of the bottom surface and the inner peripheral side surface at a wide angle with the imaging section of the camera sufficiently close to the inner surface of the deep-sealed article. We use the close-up imaging method that images the entire image at the same time, but in the case of deep objects, the optical path length to the imaging surface of the camera greatly differs near the bottom and near the opening, so the focus depth of the camera must be deviated. As a result, a portion where an image is formed on the image pickup surface is generated, and a portion that is out of the depth of focus is defocused. Further, there is a problem that the camera is intruding into the cup and it is not possible to take an image during continuous conveyance.

Therefore, such a close-up image pickup method of a camera is not suitable as a visual inspection method for deep-seated articles. In addition, a method in which a fixed camera equipped with a CCD line sensor and a rotary optical system that relatively rotates about an axis with respect to a deep-sealed article are combined to continuously scan the inner peripheral side surface and the bottom surface to capture an image on the CCD line sensor ( There is a Japanese Patent Application No. 3-220014), but it was expensive.

The present invention has been made in view of the above-mentioned conventional problems, and the ratio of the imaging length of the inner peripheral side surface to the bottom surface even if it is separated from the deep-deep article by interposing an appropriate optical system. It is possible to inspect images at the same time by increasing the number of images and to inspect them efficiently, and at the same time, it is possible to inspect various articles with different depths only by adjusting the vertical position of the optical system to ensure sufficient inspection accuracy. An object of the present invention is to provide a visual inspection device for the inner surface of a deep-seated article.

[0007]

Therefore, a visual inspection apparatus for an inner surface of a deep article according to the present invention is equipped with a zoom lens in the visual inspection apparatus for inspecting the inner surface of a deep article having a bottom surface and an opening. A concave lens is disposed outside the focal length of the imaging camera and between the deep article to be inspected, and the imaging and the inspection are performed so that the center of the deep article and the optical axis of the imaging unit substantially coincide with each other. It is characterized in that the position is provided with a transport positioning means for transport positioning.

Further, the concave lens may be freely movable and adjustable in the optical axis direction according to the depth of the deep-bottomed article. Further, an annular illumination means for illuminating the inner surface of the deep-bottom article to be inspected may be provided on the outer peripheral side of the concave lens.

[0009]

The virtual image of the inner surface of the deep article obtained by the concave lens located above the deep article opening at the predetermined position where the deep article has been conveyed by the conveyance positioning means becomes smaller as the distance from the concave lens increases. As compared with a direct view image that does not pass through a concave lens, a portion near the bottom is relatively small, and a portion near the opening is relatively large.

If a concave lens having a short focal length is selected and used, the entire virtual image is further reduced. As a result, the entire virtual image obtained by the concave lens can be kept within the depth of focus by focusing the image pickup means. It is possible to obtain the whole image without being in love with the pin. In addition, by setting the focal length of the concave lens appropriately according to the depth of the deep article and the inclination angle of the inner surface, the ratio of the side image to the bottom image formed on the image sensor (CCD area sensor, etc.) can be determined. You can get closer to 1: 1. That is, since the unit length of the inclined surface (for example, 1 mm) and the unit length of the bottom surface (1 mm) are equal, the ratio of the length of the virtual image obtained by the concave lens and the length of the image formed on the image sensor is equalized. , Can be used as an image for visual inspection.

Further, the virtual image reduced by the concave lens can be adjusted to the zoom lens to form an image of the deep article on the image pickup surface of the image pickup device, and a predetermined size is detected.
It is possible to secure an image of a sufficient size (to secure resolution). Further, by adjusting the distance in the optical axis direction of the concave lens with respect to deep-deep articles having different depths and opening sizes, the size of the virtual image and the position in the height direction are changed, and the entire virtual image is focused by the imaging means. It can fit within the depth.

Further, by providing the annular illumination means, the inner surface of the deep article is illuminated, a bright image is obtained, and the inspection accuracy can be improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, the overall schematic configuration will be described with reference to FIG. 1. The appearance inspection apparatus for deep-bed articles according to the present embodiment is a deep-bed article that is an object to be inspected, specifically, a cup made of paper or plastic. Conveying positioning part (conveying positioning means) that conveys the cup C to a predetermined position while positioning it
And an imaging unit that images the inner surface of the inspection object at the predetermined position,
An inspection section for inspecting defects on the inner surface based on the imaging result and an ejection section for ejecting defective products based on the inspection result are configured.

Next, a series of operations will be described. The mass-produced cups C are sequentially placed on the conveying flat belt 1 at equal pitch intervals and conveyed. A pair of positioning belts 2A and 2B driven by two pulleys are installed at predetermined positions on both sides of the transport flat belt 1 on the upstream side of the transport path, and a pair of positioning belts 2A and 2B are provided between the positioning belts 2A and 2B. By transporting while sandwiching C, the cups C are aligned in a line and transported while being positioned in the central portion of the transport flat belt 1 in the width direction.

Positioning belts 2A, 2B on the conveying path
A passage sensor 3 that detects passage of the cup C is installed at a predetermined position on the downstream side. The passage sensor 3 is composed of, for example, a set of a light emitter 3A and a light receiver 3B, and when the light emitted from the light emitter 3A is blocked by the cup C and is not received by the light receiver 3B, the cup C moves to a predetermined position. A signal indicating that it is passing is output to the detection unit.

An imaging unit is installed above the cup C at a predetermined position where the passage sensor 3 detects the cup C. The image pickup unit will be described in detail later, but a concave lens
11 and a camera 12 with a zoom lens are mainly configured to image the inner surface of the cup C in synchronism with the output of a passage signal from the passage sensor 3. On the other hand, if detected within a predetermined time, an alarm is issued as an error and the operation is stopped.

The signal picked up by the image pickup unit is output to the inspection unit indicated by the chain line in the figure. In the inspection section, the image pickup signal from the image pickup device (area sensor consisting of CCD, etc.) of the camera is A / D converted by the A / D device, preprocessed by the preprocessing circuit, and then temporarily stored in the field memory. Then, the analyzer analyzes the defect data, compares the prepared defect data with the reference data prepared in advance, and determines whether the product is a good product or a defective product. The discharge control circuit counts the number of passing cups C and determines the defective product. A discharge signal for discharging the cup C determined to be output to the discriminator 4 described later. Further, the original image of the cup C stored in the field memory, the analysis by the analyzer, the judgment result, etc. are selectively displayed on the monitor through the selector, and at the same time, the analysis, judgment result is output to the totaling circuit and recorded. To be done. The timing of each processing described above is performed by the timing control circuit.

At a predetermined position on the downstream side of the image pickup section, a discriminator 4 is installed which is driven by receiving a discharge signal when it is determined that the defective product is present. Although it is placed on the belt 1 and conveyed to a predetermined position and moves to the subsequent process, the arm 4a of the discriminator 4 is swiveled to move the cup C to a flat position for the cup C judged to be defective. The belt 1 is sandwiched and discharged to the opposite side, and is dropped and stored in the defective product storage box 5.

Next, the structure and operation of the image pickup section will be described in detail with reference to FIGS. The concave lens 11 and the zoom lens 12a are attached so that the optical axis of the cup C moved to a predetermined position detected by the passage sensor 3 coincides with the optical axis, and
A camera 12 having a built-in CCD area sensor (imaging device) is provided. Here, the concave lens 11 is set such that its focal length is substantially equal to the depth of the deep-bottomed article having the reference shape.
The reference shape is the depth and diameter of the object to be measured, such as the depth of a commercially available cup used in vending machines (about 37 mm to 100 mm).
mm) and aperture (approximately 60 mm to 120 mm) have a roughly average value. Further, the diameter of the concave lens 11 has the maximum aperture diameter among the cups having different aperture diameters, but the one having a diameter sufficient to image the entire aperture is used. The side wall of the main body of the camera 12 is connected to and supported by the support body 13 via a bracket, and is attached to an annular opening integrally formed at the lower end of the support body 13. A guide piece 14 extending in the axial direction is fixed, and an outer wall of the guide piece 14 is formed with a female screw portion 14a protruding in the outer diameter direction. The zoom lens 12a is positioned and installed with respect to the concave lens 11 at a height position separated by a focal length (shortest imaging distance) of the concave lens 11.

The female screw portion 14a is the flange portion 15 of the frame 15.
Ball screw (or die cast screw) installed in a.
16 and the guide piece 14 has a flange 15a.
When the handle 17 fixed to the upper end of the ball screw 16 is rotationally engaged with the vertical groove formed in the shaft, the support body 13, the concave lens 11 and the camera 12 are integrated through the guide piece 14. It can be moved and adjusted along the optical axis. Then, the concave lens 11 and the entire image pickup camera 12 are moved up and down as a unit to set a suitable height (for example, in the case of the cup C having the illustrated shape, about twice), and by adjusting the zoom lens 12a, Image sensor (CCD area sensor, etc.) Fully magnified to capture an image.

At the outer peripheral edge of the concave lens 11 of the support 13,
An annular illumination lamp 18 is attached as an illumination means, and the illumination lamp 18
A reflector 19 is installed to cover the upper part of the above, and a diffusing plate 20 formed on the textured surface is installed below, respectively, and the light emitted from the illumination lamp 18 is directed toward the lower optical axis by the reflector 19. It is directed and diffuses through the diffuser plate 20 to evenly illuminate the inner surface of the cup C.

The function of the image pickup unit will be described. First, prior to the inspection, the cup C to be inspected is placed at a predetermined position detected by the passage sensor 3 with the conveyor belt 1 stopped, and the handle 17 is rotated to operate the concave lens.
The distance between 11 and the cup C is adjusted so that the distorted virtual image P is obtained with the entire inner peripheral inclined side surface and the bottom surface of the cup C within the depth of focus.

Here, the virtual image P created by the concave lens 11
Becomes smaller in inverse proportion to the distance from the concave lens 11 to the imaged portion of the cup C. As a result, as shown in FIG. 3, the entire image is reduced as compared with the case where the concave lens 11 is not provided, but comparing the ratios of the image portions, the image of the bottom surface having a large distance is relatively small, and the inner circumference is small. The image on the side surface is distorted in such a way that the deeper portion closer to the bottom surface is smaller, and the closer the portion is to the opening, the larger the image is.

As a result, by focusing the camera 12, the entire virtual image can be contained within the depth of focus, and at the same time, the length ratios of the respective parts of the image formed on the flat image pickup surface can be made substantially equal. For example, when the bottom surface of the cup C and the inner peripheral side surface have a flaw of the same length, the flaw formed on the bottom surface is considerably larger in the image formed on the flat image pickup surface by the camera without the concave lens according to the present invention. Although it becomes a long image, when an image is taken using the concave lens 11 as in the present invention, an image having substantially the same length is obtained.

Next, as described above, the zoom lens 12a is moved and adjusted in the optical axis direction to adjust the zoom ratio so that an image enlarged to the full extent of the image pickup device can be obtained. By forming an image in the maximum range of the imaging surface in this way, the actual length of the flaw with respect to the length of the image of the flaw can be obtained in advance from the ratio with the dimension of the measured cup C. Defects can be inspected by comparing with the level. Normal commercial cup depth (about 37 mm to 100 mm) and caliber
For each cup (about 60 mm to 120 mm), the resolution necessary to inspect for defects of at least 0.3 mm or more on their inner surface can be sufficiently ensured.

[0026]

As described above, according to the present invention, a concave lens is provided between the focal length of an image pickup camera equipped with a zoom lens and the outward direction, and a virtual image of the inner surface of a deep-sealed article is picked up. As a result, the entire image formed on the imaging surface can be contained within the depth of focus to obtain an image free of focus, and the appearance in which the size ratios of the bottom surface image and the inner surface image are equalized The inspection image can be obtained, and the inspection accuracy can be improved by forming the entire image on the entire imaging surface by adjusting the zoom ratio.

Further, by arranging the concave lens so that the concave lens can be moved and adjusted in the optical axis direction, it becomes possible to deal with various deep-bottomed articles having considerably different depths and diameters. Further, by providing the annular illuminating means on the outer peripheral side of the concave lens, the inner surface of the deep-sealed article can be efficiently illuminated and a bright image can be obtained, so that the inspection accuracy can be improved.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional view showing a configuration of an image pickup unit according to the above embodiment.

FIG. 3 is a view showing a deep-view article in which a direct-view image without passing through a concave lens and a virtual image through a concave lens are compared with each other.

[Explanation of symbols]

 1 Transport flat belt 2A, 2B Positioning belt 3 Pass sensor 11 Concave lens 12 Camera 12a Zoom lens 14 Guide piece 14a Ball screw

Claims (3)

[Claims] 1. A visual inspection apparatus for inspecting an inner surface of a deep-sealed article having a bottom surface and an opening, wherein a deep-sealed article to be inspected is outside the focal length of an imaging camera equipped with a zoom lens. The deep bottom is characterized in that a concave lens is disposed between the deep bottom article and a conveyance positioning means for conveying and positioning the center of the deep article and the optical axis of the image pickup section at a substantially coincident position. Visual inspection device for the inner surface of articles. 2. The appearance inspection apparatus for a deep-sealed article according to claim 1, wherein the concave lens is freely movable and adjustable in the optical axis direction according to the depth of the deep-sealed article. 3. The inner surface of the deep article according to claim 1, further comprising annular illumination means for illuminating the inner surface of the deep article to be inspected, on the outer peripheral side of the concave lens. Appearance inspection device.