JPH08101140A - Sheet fish-eye measuring method and device - Google Patents

Abstract

PURPOSE: To provide a fish-eye measuring method and device for a sheet which can make automatic measurement of fish-eye greater than 70μm in the sheet accurately. CONSTITUTION: A sheet to be measured is placed on a stage 8 which is movable along two axes with. a locational accuracy of 5μm or below and one view field of a camera 14 is determined so that the value obtained by dividing it by the number of picture elements becomes below 70μm for sensing of fish-eyes over 70mm in the sheet 4. The arrangement comprises the camera 14 to photograph the surface of the sheet 4 in the view field, a judging means 18 to subject the image photographed by the camera 14 to a binary processing for every picture element and judge as a fish-eye those of the picture elements having a lightness over a certain gradation, a measuring means 20 to measure the number of generated fish-eyes within the field and the corresponding area, a driving means 12 which shifts the stage 8 so that the scope of the sheet 4 photographed by the camera 14 is dislocated one view field by view fie.ld, and a counting means 22 which counts the number of fish-eves measured for each view field and their area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring fish eyes (referred to as spotted heterogeneous substances) present in a sheet or film of synthetic resin such as soft vinyl chloride or synthetic rubber.

[0002]

2. Description of the Related Art Soft vinyl chloride sheets and the like are manufactured by kneading. In the kneading, if the kneading is carried out uniformly, no granular part called fisheye (non-gelled part) is formed, but it is extremely difficult to knead it completely uniformly, and fisheye will occur. . If the number and size of the fish eyes are within a predetermined reference range, there is no problem as a sheet product, and if it exceeds the reference range, it is necessary to discharge it as a defective product.

Conventionally, for example, the number and size of fish eyes in a soft vinyl chloride sheet have been measured by an operator by observing a sheet having a size of 100 mm × 100 mm with a microscope or the like. However, such work is extremely complicated, and automation of the work has been desired.

As a method of automating such work,
There is a method of using an image processing device.

[0005]

However, in the existing image processing apparatus, the number of pixels is limited to about 512 × 512, and one field of view of the camera is, for example, 100 mm × 1.
If it is 00 mm, a single pixel is 195 μm (1
Since it corresponds to (00 mm ÷ 512 pixels), a fish eye smaller than 195 μm cannot be detected. However, according to the inspection standard of the sheet, for example, 100 mm of the sheet
In the range of × 100mm, 70 which can be recognized by human eyes
A fish eye of μm or larger must be detected.

Therefore, the field of view of the camera is reduced and the image processing is performed several times. However, if the image processing is performed several times, the operator needs to shift the sheet, and automatic measurement cannot be performed. In addition, since it is operated by a person, it takes extra time and has an adverse effect. Furthermore, it is necessary to avoid measuring at the same place, which is troublesome.

Conventionally, the pigment of the sheet is contained in the material before kneading the sheet and kneaded to prepare the sheet. However, at the initial stage of kneading, the material containing the pigment spills out from the kneading roll to some extent. For this reason, the color of the sheet is not constant, and there is a possibility that the fish eyes cannot be accurately detected during image processing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet fish eye measuring apparatus and a measuring method capable of accurately and accurately measuring a fish eye of a sheet having a minimum size of 70 μm or more. .

[0009]

In order to achieve the above object, a sheet fish eye measuring apparatus according to the present invention comprises:
In order to detect the stage on which the sheet to be measured is placed and which can be moved in two axial directions with an accuracy of 5 μm or less, and a fish eye of 70 μm or more present on the sheet, one field of view of the camera has a number of pixels. The value divided by is 70μ
Determine a field of view of the camera so that m or less, and the camera that captures the surface of the sheet in that field of view and the image captured by the camera are binarized for each pixel, and If a pixel having a brightness equal to or higher than the key is determined to be a fish eye, and a pixel having a brightness lower than the gradation is determined not to be a fish eye, and a pixel determined to be the fish eye is adjacent, The area of pixels in the adjacent range is determined as the area of a single fish eye, and a measuring unit that measures the number and area of fish eyes in one visual field, and the sheet imaged by the camera. A driving unit that moves the stage so as to shift the range for each visual field, and a totaling unit that totals the number and area of fish eyes measured for each visual field are included.

In order to detect a fish eye of 70 μm or more present on the sheet, the method for measuring the fish eye of the sheet according to the present invention is such that the value obtained by dividing one field of view of the camera by the number of pixels is 70 μm or less. A step of determining one field of view of the camera and imaging the surface of the sheet with the one field of view, and binarizing the image captured by the camera for each pixel to obtain a pixel having a brightness equal to or higher than a certain gradation. Is determined to be a fish eye, and a pixel having a brightness equal to or lower than the gradation is determined not to be a fish eye, and when the pixels determined to be a fish eye are adjacent to each other, The step of determining the area of the pixel as the area of a single fish eye and measuring the number and area of the fish eyes in one visual field, and shifting the range of the sheet imaged by the camera for each visual field , The method includes a step of moving a sheet or a camera and a step of totaling the number and area of fish eyes measured for each of the visual fields.

When the sheet is prepared by kneading, it is preferable that the material to be put into the kneading device does not contain the pigment, and the pigment is added in the step during the kneading.

[0012]

In the measuring method using the seat fisheye measuring apparatus according to the present invention, one field of view of the camera is
3.5mm x 23.5mm. When the number of pixels of the camera is, for example, 512 × 512, the length of the sheet corresponding to one pixel is 23.5 mm ÷ 512 = 0.046 mm =
It becomes 46 μm. Therefore, in this case, 46 μm
The above fish eyes can be detected.

The discriminating means discriminates, for example, a binarization level gradation of 256, and a pixel portion having a brightness of, for example, 60 or more, as a part of a fish eye. In the measuring means, when the pixels determined to be fish eyes are adjacent to each other, the area of the pixels in the adjacent range is
The area (size) of a single fish eye is determined, and the number and area of fish eyes in one visual field are measured.

When the image pickup in the visual field of the camera is completed, the camera or the sheet, preferably the sheet, is
It moves so as to shift by one visual field, an image is taken in the next visual field, and the number and area of fish eyes are measured in the same manner as described above. In the counting means, the number and area of fish eyes in each visual field are totaled, and the number and area of fish eyes in each visual field are totaled and totaled, for example, 100 mm ×
The number and area of fish eyes on a sheet with a size of 100 mm are totaled. The result can be displayed on a monitor or the like. It can also be printed out on paper.

In the present invention, the XY stage on which the sheet is placed has a positioning accuracy of 5 μm or less, preferably 2 μm.
Since the movement is controlled with a degree of accuracy, the overlapping portion in the adjacent visual fields can be set to 5 μm or less, preferably 2 μm or less, and an error caused by detecting the same fish eye is almost eliminated.

When the sheet is prepared by kneading,
By not adding the pigment to the material initially put in the kneading device, but by adding the pigment in the process of kneading, a constant amount of pigment is always included in the sheet every time the sheet is made, and the color of the sheet changes. It becomes constant, and the detection error in image processing is reduced.

[0017]

The sheet fisheye measuring apparatus and method according to the present invention will be described in detail below with reference to the examples shown in the drawings. FIG. 1 is a schematic configuration diagram of a fisheye measuring apparatus according to an embodiment of the present invention, and FIG. 2 is 15 × 1.
FIG. 4 is a diagram showing an original image of a sheet in a field of view of 3 mm, FIG. 3 is a diagram showing a black and white inverted display after binarizing the original image of the sheet, FIG.
Is a diagram in which fisheye parts are given continuous symbols, FIG. 5 is a histogram showing the distribution of fisheyes in each area range, FIG. 6 is a histogram showing the distribution of fisheyes in each equivalent circle diameter range, and FIG. 7 is a number FIG. 8 is a graph showing the area of each attached fish eye, and FIG. 8 is a graph showing the equivalent circle diameter of each numbered fish eye.

As shown in FIG. 1, a fisheye measuring apparatus 2 for a sheet according to an embodiment of the present invention comprises an XY stage in which a sheet 4 to be measured is placed together with a light source box 6 and movable in two axial directions. Have eight. The XY stage 8
The movement is controlled with a positioning accuracy of 2 μm or less. X
The Y stage 8 is drive-controlled in conjunction with image processing by the image processing apparatus 10. In the present embodiment, the image processing apparatus 10 is controlled.
The driving is controlled by the driving means 12 inside the.

The sheet 4 is not particularly limited as long as it is a sheet in which fish eyes can be observed, but is, for example, a vinyl chloride sheet. This sheet is manufactured by kneading, but by not including the pigment in the material to be put into the kneading device, but by adding the pigment in the process during the kneading, a certain amount of the pigment is always included in the sheet. , The color of the sheet becomes constant, and the detection error in image processing is reduced.

The light from the light source box 6 illuminates the sheet 4 uniformly. A CCD camera 14 is arranged above the sheet 4. The effective number of pixels of the CCD camera 14 of this embodiment is 512 × 480 pixels. The resolution is, for example, 100,000 pixels. The range (one visual field) of the sheet imaged by the CCD camera 14 at one time is 23.5 × 21.5 mm in this embodiment. By setting this range as one field of view, the length of the sheet corresponding to one pixel of the camera is 23.5 mm ÷ 512 = 0.046 mm = 46 μm. As a result, fish eyes having a size of 46 μm or more can be detected. In the present invention, the camera is not limited to the CCD camera, and other cameras such as an image pickup tube can be used.

The CCD camera 14 is used in the image processing apparatus 1.
It is connected to the binarization processing means 16 of 0. The binarization processing means 16 sets the gradation of the binarization level to 256, and binarizes the image data. The binarized data is sent to the discriminating means 18, where the pixel portion having a brightness of 60 or higher is discriminated as a part of the fish eye. An original image of a sheet corresponding to one visual field before the binarization process is shown in FIG. As shown in FIG. 2, the pigment is not mixed in the fish eye portion of the sheet, the light from the light source box 6 shown in FIG. 1 is transmitted, and the fish eye is observed as a bright point. FIG. 3 shows an observation screen of the sheet in which black and white is further inverted after the binarization process is performed, and the black dots correspond to fish eyes. FIG. 4 shows a screen in which the fish eyes detected in FIG. The images shown in FIGS. 2 to 4 can be sequentially displayed on the screen of the monitor 26 or the personal computer 24 shown in FIG.

The image data discriminated by the discriminating means 18 is
When the pixels which are sent to the measuring means 20 and are determined to be fish eyes are adjacent to each other, the area of the pixels within the adjacent range is calculated as the area (size) of a single fish eye. Then, the number and area of fish eyes in one visual field are measured. The data measured by the measuring unit 20 is sent to the totaling unit, where various types of totaling are performed.
Interlocking with the image processing of the image processing apparatus 10, the X-axis is driven by the driving unit 12 each time the image pickup by the camera is completed for each visual field.
The Y stage 8 is driven and controlled, the sheet 4 is moved so as to be shifted by one visual field, an image is captured in the next visual field, and the number and area of fish eyes are measured in the same manner as described above.

The totaling means 22 totals the number and area of fish eyes in each visual field, and totals the total number and area of fish eyes in each visual field.
The number and area of fish eyes on a sheet of 0 mm x 100 mm are totaled. The result can be displayed on the monitor 26 or the monitor of the personal computer 24. It can also be printed out on paper.

FIG. 5 is a histogram showing the result of totaling the number of fish eyes in each area range, and FIG. 6 is a histogram showing the distribution of fish eyes in each equivalent circle diameter range. In FIGS. 5 and 6, the numbers described after or less than / indicate the area range of fisheyes, and the numbers described after% are the percentages of the total number of fisheyes in the area range. The equivalent circle diameter is
It is the diameter of the fish eye corresponding to the area of the fish eye.

FIG. 7 is a graph showing the area of each numbered fish eye, and FIG. 8 is a graph showing the equivalent circular diameter of each numbered fish eye. The screens shown in these figures also correspond to the monitor 26 or the computer 2 shown in FIG.
4 monitors can be displayed.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the drive unit 12 shown in FIG. 1 does not necessarily have to be provided in the image processing apparatus 10, and may be built in the personal computer 24 or the XY stage 8.

[0027]

As described above, according to the present invention, it is possible to accurately and automatically measure the fish eye of a sheet having a minimum size of 70 μm or more within a predetermined area. It is possible to instantly determine whether the product is defective. Further, since the XY stage on which the sheet is placed is controlled to move with a positioning accuracy of 5 μm or less, preferably about 2 μm, the overlapping portion in the adjacent visual fields is
It can be 5 μm or less, preferably about 2 μm or less, and an error caused by detecting the same fish eye again is almost eliminated.

When the sheet is prepared by kneading,
By not adding the pigment to the material to be put into the kneading roll, but by adding the pigment in the process during the kneading, a certain amount of the pigment is always contained in the sheet, and the color of the sheet becomes constant, and the image processing is performed. The detection error in is reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fisheye measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a view showing an original image of a sheet in a visual field of 15 × 13 mm.

FIG. 3 is a diagram showing black and white reverse display after binarizing an original image on a sheet.

FIG. 4 is a diagram in which a continuous code is added to a fish eye portion.

FIG. 5 is a histogram showing the distribution of fish eyes in each area range.

FIG. 6 is a histogram showing the distribution of fish eyes for each equivalent circular diameter range.

FIG. 7 is a graph showing the area of each numbered fish eye.

FIG. 8 is a graph showing the equivalent circular diameter of each numbered fish eye.

[Explanation of symbols]

 2 ... Sheet fisheye measuring device 4 ... Sheet 6 ... Light source box 8 ... XY stage 10 ... Image processing device 12 ... Driving means 14 ... CCD camera 16 ... Binarizing means 18 ... Discriminating means 20 ... Measuring means 22 ... Aggregating means 24 ... Personal computer 26 ... Monitor

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[Procedure amendment]

[Submission date] October 14, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG.

Claims (3)

[Claims] 1. A stage on which a sheet to be measured is placed and which can be moved biaxially with a positioning accuracy of 5 μm or less, and a camera for detecting a fish eye of 70 μm or more existing on the sheet. A camera that determines one field of view of the camera so that the value obtained by dividing one field of view by the number of pixels is 70 μm or less, and a camera that captures the surface of the sheet in that one field of view A binarization process is performed for each pixel, pixels with brightness above a certain gradation are judged as fish eyes, and pixels with brightness below that gradation are judged not to be fish eyes. When adjacent pixels are adjacent to each other, the area of the adjacent pixels is judged as the area of a single fish eye, and the number and area of fish eyes in one visual field are measured. Means and And a driving unit that moves the stage so as to shift the range of the sheet imaged by the camera for each visual field, and an aggregation unit that aggregates the number and area of the fish eyes measured for each visual field. Seat fisheye measuring device. 2. In order to detect fish eyes of 70 μm or more existing on a sheet, one field of view of the camera is determined so that a value obtained by dividing one field of view of the camera by the number of pixels is 70 μm or less, and one of the fields of view is determined. The step of imaging the surface of the sheet in the field of view, and the image captured by the camera is binarized for each pixel, and a pixel having a brightness equal to or higher than a certain gradation is determined as a fish eye, and the gradation If the pixels with the following brightness are judged not to be fish eyes, and if the pixels judged to be fish eyes are adjacent to each other, then the area of the pixels within the adjacent range is set to a single fish eye. , The step of measuring the number and area of fish eyes in one field of view, the step of moving the sheet or the camera so as to shift the range of the sheet imaged by the camera for each field of view, The above A fisheye measuring method for a sheet, comprising a step of totaling the number and area of fisheyes measured for each visual field. 3. When preparing the sheet by kneading,
Do not include pigment in the material initially put in the kneading device,
The fisheye measuring method for a sheet according to claim 2, wherein the pigment is added in a step during the kneading.