JP2520566B2 - Package fluff inspection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting fluff on the surface of a synthetic fiber package, and more particularly to a method for inspecting fluff of a package which can be efficiently inspected with a simple device without overlooking minute fluff. Is.

[0002]

2. Description of the Related Art Synthetic yarn is formed by assembling a plurality of synthetic fibers. For example, one synthetic fiber thread is composed of 36 elementary fibers of several μm. If the fiber is cut, fluff occurs on the side surface of the synthetic fiber. Synthetic yarns with a lot of fluff are defective synthetic yarns and must be rejected by inspection. When the synthetic fiber is packaged, it is not possible to see the inner layer, so inspect the fluff that appears on the surface, and if there are many fluffs, consider that the inner layer also has fluff corresponding to it. become.

Conventionally, the fluff of a package is visually inspected. The place to be inspected is the end face. Since the end faces are formed to be substantially flat, it is easy to apply light from a desired angle, and fluff can be found over a relatively wide range. The quality of the entire package will be determined based on the inspection result of the fluff on the end surface.

The fluff appearing on the end face is
Although they are curled or have various shapes, each has a diameter of several μm to 10 μm. The thing of this size is
It may be barely visible with the naked eye, or it may not be visible. Also, depending on the angle of light, it may or may not be visible. Therefore, the fluff inspection worker requires skill and is extremely tired. In addition, since it is a human work, it is impossible to quantify the inspection contents or mass process.

[0005]

Unmanned inspection of fluff is an important issue from the viewpoint of factory rationalization and quality control. To unattend these visual inspections,
It is common to introduce an optical sensor. However, it is difficult to realize it due to the problems described below.

Conventionally, an optical sensor often used for appearance inspection is an optical sensor called a line sensor or an area sensor in which a large number of sensor elements are arranged. By capturing an object with a line sensor, an area sensor, or the like and processing the image, various shape defects can be detected. The popular line sensor has 51 elements.
The number is two, and the number of elements is at most about 2000. Of course, the greater the number of elements, the more expensive the line sensor. This number of elements defines the resolution. That is, when one line image is composed of 512-bit pixels, 10
The resolution for an object field having a width of about 10 cm is 10 cm / 5.
It is 12 bits.

However, the diameter of the fluff is several μm to 10 μm.
Therefore, in order to image fluff on at least one pixel, the width of the object field must be limited to a narrow range of about 20 mm even in the case of a 2000-bit line sensor. Moreover, the size of one sensor element is several μm to 10 μm.
Since it is μm, it is necessary to configure the optical system so that the width of the object field and the width of the line sensor are approximately 1: 1 or more. On the other hand, the package width is usually 15
Since it is from cm to 25 cm, it is impossible to observe the entire package width at once with one line sensor.

If a large number of line sensors are arranged side by side, a line sensor with an extraordinarily large number of elements is formed, or if the line sensor can be moved, the required resolution can be obtained, but the apparatus is very complicated. In addition, it is expensive and has great disadvantages.

Further, in order to inspect the entire end face, the above-mentioned resolution is required in the vertical and horizontal directions. Therefore, the number of times of imaging becomes the number of times corresponding to this resolution, and the time spent for imaging and its image processing is enormous. Will be things.

As described above, since the fluff is extremely fine, it is difficult to introduce an optical sensor into the fluff inspection.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a fluff inspection method for a package, which enables efficient inspection with a simple device without overlooking the minute fluff.

[0012]

In order to achieve the above object, the present invention irradiates a package with directional light,
The light reflected from the package outline is imaged by overexposure, and the fluff of the package is detected from the image.

[0013]

The image pickup means such as a camera or an optical sensor forms an image according to the amount of incident light (exposure). For example, the photosensor outputs a pixel output according to the amount of light incident on the element. Even if the object is small, if the amount of light emitted from it is large or the sensitivity is high, it is possible to obtain a pixel output corresponding to it. This tendency is the same with the naked eye, and even with a little illumination, if the light is intense or the eyes are squint, even small fluff can be found. The present invention has been made based on such findings. Further, the fact that the synthetic fiber as the object has a property of strongly reflecting light is effectively utilized.

By irradiating the package with light having directivity, reflected light with less diffusion can be obtained. When the image pickup means is exposed to the package contour, the reflected light from the fluff enters the image pickup means without being attenuated by diffusion. When imaging is performed with overexposure by increasing the light amount of the light source, opening the diaphragm, or increasing the sensitivity of the optical sensor, sufficient pixel output can be obtained even though the diameter of the fluff is small.

In particular, in the method of accumulating (releasing) electric charges in accordance with the amount of incident light such as CCD, the overexposed elements are saturated and the electric charges leak between adjacent elements one after another. The resulting image is recognized as a blur. This phenomenon is a problem in normal usage of the image pickup means, but is effectively utilized in the present invention. That is, an image of one pixel or more can be obtained from the fluff having a size corresponding to one pixel or less. In this way, the fluff is imaged as if it were magnified.

The image due to overexposure can be easily detected because the fluff is enlarged. Further, even with a line sensor having a small number of elements, it is possible to observe the entire package width at once.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the structure of a basic optical system. The light source 2 is provided in the extension direction of the end surface 1 a with respect to the package 1. Further, the image pickup means (optical sensor) 3 is provided at different angles in the extension direction of the end face 1a. Package 1
The fluff indicated by K above has a diameter of several μm to 10 μm and is difficult to see with the naked eye. The package 1 is placed on a tray (not shown) and rotationally driven by a drive system (not shown).

The light source 2 comprises a halogen lamp 4 and a collimating mirror 5 arranged behind it.
The light emitted from the light source 2 to the package 1 is a substantially parallel light having a certain width, and the end face 1a of the package 1 is
It is illuminated particularly brightly in a predetermined range along one radius from the bobbin 7 to the outer periphery of the package 1. The brightness of the light source 2 is set so that the brightness in that range is about 5,000 lux. Even if a fluorescent lamp is used as the light source 2, a brightness of 4 to 5,000 lux can be obtained, but the light is easily diffused, the amount of reflected light is reduced, and the contrast is difficult to obtain. In this respect, since the light of the halogen lamp 4 is collimated and used, the amount of reflected light is large and the contrast can be easily obtained. Further, the halogen lamp 4 contains a large amount of light in the short wavelength range, and causes the synthetic fiber to generate strong reflected light.

The optical sensor 3 is an area sensor 8 composed of a CCD and has light receiving elements arranged in 512 bits horizontally and several bits vertically. The area sensor 8 is provided with a light control means in the lens portion, and the exposure can be adjusted. Since the halogen lamp 4 having high brightness is used as the light source 2, the range of exposure adjustment is large and the adjustment is easy. Since the focus of the area sensor 8 has obtained a brightness of about 5,000 lux, the area sensor 8 is overexposed. Since the optical sensor 3 faces the contour of the package 1, only light from the background can be obtained if there is no protrusion such as fluff K on the contour. Here, the background image is black because there is nothing in the background. If there is light reflected from the fluff K, the image becomes white.

FIG. 2 is a top view of the optical system. The range in which the light source 2 is particularly brightly illuminated is the range of θ, and the depth of focus of the area sensor 8 is also set so as not to exceed the range of θ. θ is, for example, 20 °.

FIG. 3 shows a processing system. The drive circuit for supplying the clock signal CLK to the area sensor 8 is interlocked with the drive system for rotationally driving the package 1, and gives the image pickup timing for each rotation angle θ (here, 20 °). The video signal VIDEO of the area sensor 8 is input to the A / D converter 33 via the filter 32. A / D converter 33
Is output from the memory (RAM) 34, CPU 35, I / O
It is input to a computer such as 36. The 18 images taken at every rotation angle of 20 ° are temporarily stored in the memory 3
4 and image processing is performed.

The image and the result of the image processing will be described based on an actual example. 4A to 4C, an image P captured by the area sensor 8 and an image P thereof are all shown.
3 shows an edge waveform E obtained by performing edge processing on the. Although diagonal lines are drawn in the image P, the shaded areas are actually bright areas (white) and the surrounding areas are unexposed areas (black). As can be seen from the figure, in the image P, the images of the bobbin 7 and the package 1 are thickly blurred due to overexposure. Since the image P is subjected to appropriate edge processing, the edge waveform E well represents the upper boundary of the image P, that is, the contour of the end face 1a.

In FIG. 4A, the edge waveform E has three small protrusions k. These are due to the limit of fluff K that can be determined as fluff K. Package 1
The diameter of the fluff K is about 15 μm to 25 cm, and the diameter of the fluff K is about several μm.
Such an edge waveform E cannot be obtained with 12-bit resolution. According to the method of the present invention, since the image is thick, the edge waveform E having the protrusion k is obtained, and the fluff K can be determined based on the protrusion k. FIG. 4B shows the detection of the loop-shaped fluff K based on the protrusion k. In FIG. 4C, a large number of protrusions k corresponding to the simple fluff K and the loop-shaped fluff K appear. In this way, not only the presence or absence of the fluff K but also the shape can be detected.

A general CCD, one element having a width of 10 μm and 512 elements / line, has a width of 5.12 mm. If the width of the field and the width of the CCD are used in a nearly one-to-one relationship, the width of the field becomes 5.12 mm. However, according to the results of the present invention, fluff is detected when the field width is 60 mm. Even if the diameter of the fluff is 10 μm, the image is 12 times thicker. Also, the size of the fluff is 8
It has been obtained that the size of the protrusions appearing on the edge waveform E becomes 5 bits when the thickness is μm.

Although the irradiation direction of the light source light is the extension direction of the end surface 1a of the package 1 in this embodiment, the fluff can be detected in any irradiation direction. Further, although the focus position is set to the center of θ and the depth of focus is set to θ, it is not necessary to strictly set this and there may be some error. That is,
Since the light source 2 is strong, strong reflected light can be obtained from the fluff that the light is shining on, and a thick and bright image can be obtained even in a so-called defocused state.

The lack of focus restrictions favors a reduction in processing time. This is because the depth θ that can be observed at one time can be large. The fact that the depth θ can be set large allows the synchronous rotation angle θ of imaging to be set large. For example, if images are taken every θ = 20 °,
A full circumference inspection will be achieved by processing only 18 images. Moreover, if one image is processed during the imaging time interval (= 20 ° rotation time), all image processing can be completed in real time while the package 1 rotates once.

Next, an application example of the present invention will be described.

As shown in FIG. 5, a package inspecting section 51, which constitutes a portion related to optical inspection of the package inspecting apparatus, includes a light-shielding box 52 and various inspections housed in the box 52. Optical systems 53 to 58 and a conveyor 59 penetrating the box 52. The light-shielding box 52 blocks unnecessary light from the outside and absorbs light on the inner surface to form an environment advantageous for optical measurement. Package 1
Is mounted on a pedestal 60, and the pedestal 60 is placed on a conveyor 59 to be conveyed. Pedestal 6
Reference numeral 0 denotes an axis in which the shaft is erected at the center of the disk, and the package 1 can be mounted by inserting the package 1 into the axis. The mounted package 1 is hooked in the middle of the shaft and floats from the disc. In the box 52,
Openings 61 are provided on both sides thereof so that the packages 1 mounted on the pedestal 60 can be put in and taken out.
Are provided so as to extend across the space between both openings 61.
The right side of the figure is the upstream side of the conveyor 59. Conveyor 59
The uppermost stream is outside the box 52, and a surface processing unit 63 for processing the surface of the package is formed there. On the other hand, the uppermost stream of the conveyor 59 ends at the downstream opening 61 of the box 52, and another conveyor 64 having a conveying direction intersecting with the paper surface is provided outside the box 52 so as to connect to this end. . The conveyor 64 is formed with a weighing unit 65 that measures the weight of the package.

Three stop positions S1 to S3 are set on the conveyor 59 in the box 52, and a pedestal rotation drive mechanism 66 for rotating the pedestal 60 is provided at each of these stop positions so as to be retractable. Has been. The various optical inspections described below are performed during conveyance by the conveyor 59, or while the conveyor 59 is stopped and the pedestal rotation drive mechanism 66 appears and the package is rotated at that position.

The optical system which constitutes the package inspection section 51 includes a twill inspection optical system 53 and a bunch inspection optical system 5.
4, shape (step winding) inspection optical system 55, shape (bulge)
The inspection optical system 56, the dirt inspection optical system 57, and the fluff inspection optical system 58 of the present invention. The crossover inspection optical system 53 includes an optical system 53a facing the upper end surface of the package 1 at the first stop position S1 of the conveyor 59 and an optical system 53b facing the side surface of the package obliquely from below. It consists of individual optical systems.

The bunch inspection optical system 54 is installed at the first stop position S1 so as to face the bunch portion of the package 1 from the direction intersecting the plane of the drawing. The bunch inspection optical system 54 detects a bunch from the spectral characteristic of the bobbin and the spectral characteristic of the yarn. The shape (step winding) inspection optical system 55 faces the upper end surface of the package 1 at the first stop position S1 and detects the presence or absence of step winding and the size thereof.

The shape (bulge) inspection optical system 56 includes a second
It is provided upstream of the stop position S2 and detects the size of the bulge during the package transportation. The shape (bulge) inspection optical system 56 includes a front surface 56a and a back surface 56b, which face the upper and lower end surfaces of the package 1, respectively. The dirt inspection optical system 57 faces the end surface of the package 1 at the second stop position S2 and detects dirt from the dirt spectral characteristics and the thread spectral characteristics. The dirt inspection optical system 57 also has a front 57a and a back 57b.

Although the third stop position S3 is the position at which the fluff inspection is performed, the fluff inspection optical system 58 has the first stop position S3.
It is placed in the vicinity of 1. A front 58a and a back 58b are installed at different positions on the both sides of the conveyor 59. The fluff inspection optical system 58, that is, the light source 2 described in the above embodiment.
The area sensor 8 is provided so as to face the package 1 at the third stop position S3 from the upstream side. The front fluff inspection optical system 58a is located on the extension of the upper end surface of the package 1, and the back fluff inspection optical system 58b is located on the extension of the lower end surface of the package 1. In this way, the fluff inspection optical system 58 faces the contour of the package 1 and the inner surface of the box body 52 that is the background does not reflect light, so images obtained from the front and back fluff inspection optical systems 58, respectively. And the edge-processed waveform thereof have a shape as shown in FIG.

In the package inspection unit 51, each optical system in the box 52 irradiates with light of a type suitable for each inspection content in a required direction. These lights are arranged so as not to interfere with each other in other optical systems. In particular, the fluff inspection optical system 58 emits a strong light source from the vicinity of the first stop position S1, but the light has directivity and is directed in the horizontal direction. It does not affect the other optical systems that use it, and vice versa. In addition, although the optical path length of the fluff inspection optical system 58 is longer than that of other optical systems, it can be arranged at a position that forms an acute angle with respect to the longitudinal direction of the conveyor 59. It can be formed with high storage efficiency.

[0036]

The present invention exhibits the following excellent effects.

(1) Since the image in which the fluff is magnified is obtained by the overexposure, it is possible to detect the minute fluff without missing it, and it is possible to improve the quality of the package.

(2) Since the detection accuracy is high even if a special light source or image pickup means is not used, the apparatus becomes simple.

(3) Since images are taken by overexposure, a relatively wide range of the package can be inspected at once, and the entire package can be inspected efficiently.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of a basic optical system for a method of the present invention.

FIG. 2 is a plan view of the optical system of FIG.

FIG. 3 is a block diagram of a processing system for the method of the present invention.

FIG. 4 is an image diagram showing an actually measured image and an edge waveform.

5A and 5B are views of a package inspection unit showing an application example of the present invention, in which FIG. 5A is a plan view and FIG. 5B is a front view.

[Explanation of reference numerals] 1 package 2 light source 3 imaging means

Claims (1)

(57) [Claims] 1. A package is irradiated with directional light, and reflected light from a package contour is imaged by overexposure.
A fluff inspection method for a package, which comprises detecting fluff of the package from the image.