JPH07325038A - Fluff measuring method for sheet-like object and measuring apparatus therefor - Google Patents

Abstract

PURPOSE:To quantitatively measure the number of fluff and the surface area of the fluff by radiating laser luminous fluxes, taking an image of a luminous part where the laser light rays are reflected disorderly by the fluffs, and analysing the image. CONSTITUTION:A conical reflection mirror is attached to the tip part of a semiconductor laser oscillator. The laser light rays are reflected and become slitted luminous fluxes 5 in a fan-shape and the vertical angle of the conical mirror is so set as to make the angle of the fan-shaped fluxes be 100 degrees and the thickness of the luminous fluxes be 2-3mm. The luminous fluxes and the surface of a paper sheet are so set as to form no gap between them. The luminous fluxes proceed in parallel to the surface of the paper sheet while being brought into contact with the surface of the paper sheet and an image of the bright point where the luminous fluxes impinge the fluffs K is taken by CCD camera from the upper side. The quantity of the light and the surface area of the formed image are photo-electrically converted and further A/D converted to quantitative digital signals. Then, the digital signals are converted to be binary values by a proper threshold, displayed as a two-dimension image by image processing, stored in a computer, and the number and the surface area of the fluffs K are measured based on the stored two-dimension image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the area and number of minute fluff present on the surface of a sheet-like material such as paper, and an apparatus therefor.

[0002]

2. Description of the Related Art Fibers are exposed on the surface of paper and fluffed, which sometimes causes fine fluffs having a height of several tens to several hundreds of microns, and the fluff may cause a problem in processing the paper. . For example, when various chemicals are applied to paper, the coating liquid adheres to the fluff portion to cause stains, and when electronically copying the paper, the toner adheres to the fluff portion and the paper surface It will cause the stain.

However, there is no standard in JIS for a method for quantitatively measuring the fluffed state, and there is no measuring device at present. The conventional inspection method is
I put a paper sample in a dark room, illuminate it with a flashlight, and visually check the condition of fluff, and count the number,
This is a very troublesome work, and there is a problem in that there are large errors due to individual differences in measurement results.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a novel method for quantitatively, objectively and rapidly measuring the fluffing of a sheet-like material such as paper, and an apparatus therefor. The present inventors irradiate a slit light flux on the surface of the paper in a certain direction, and light diffusely reflected by the fluff is photographed by a pixel camera to measure the light amount and the area, and the measured value is digitized and binarized,
The inventors have found that the area and number of fluffs can be quantified with high accuracy by using an image processing method, and have completed the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention irradiates a slit-shaped light beam in a direction parallel to the sheet-like material so as to come into contact with the surface of the sheet-like material. The light diffusely reflected by the fluff existing on the surface of the object is photographed by a pixel camera installed above the surface of the sheet-like object, the light quantity and the area of the diffusely reflected light are measured, and the light quantity and the area are photoelectrically converted. And digitally converting and storing in a computer, the obtained digital signal is binarized, and the binarized signal is two-dimensionally displayed and image-processed.
A fluffing measuring method for a sheet-like material, comprising measuring the area and number of fluffing portions of the sheet-like material.

Further, according to the present invention, a supporting member for fixing the sheet-like object on a plane, a light source for irradiating the surface of the sheet-like object with a slit-shaped light beam, and a fluff of the sheet-like object are provided. A pixel camera that captures diffusely reflected light, a freezer that fixes the image of the camera, a photoelectric converter and an A / D converter that convert the light amount and area of the image, and the obtained digital signal are stored. This is a device for measuring the fuzz of a sheet-like material, which comprises a computer for binarizing and analyzing an image.

The light source is not particularly limited as long as it can obtain a slit-shaped light beam having a constant thickness, but it is preferable to use a laser beam having a large directivity and a convergent property. Is suitable as a semiconductor laser because of its small output and compact size. It is also possible to use a halogen lamp as a light source and install a large number of optical fibers in parallel to obtain a slit-shaped light beam.

An embodiment of the present invention uses laser light,
A case will be described in which a reflecting mirror is used to form a fan-shaped slit-shaped light beam and the fluffing of paper is measured. It is important that this light flux is irradiated substantially parallel to the surface of the paper and in contact with the paper surface, and it is impossible to accurately measure if there is a gap between the light flux and the paper surface.

The angle of the sector is about 100 degrees, and the thickness of the luminous flux is 2 to 3 mm. In the conical reflecting mirror shown in the drawings of the embodiments described later, the size and apex angle of the cone and the reflection position of the laser light are determined so that the laser light flux satisfies the above conditions. When the sheet of the subject is a quadrangle, it is preferable that four sets of the above laser light oscillators and reflecting mirrors are installed and irradiated from the four corners of the sheet. The degree of contact between the laser beam and the paper surface can be adjusted by finely adjusting the sheet supporting and fixing plate in the height direction. If there is no obstacle, the laser light beam goes straight as it is, but if there is fuzz in the middle, it will be diffusely reflected and the amount of light upward will increase, and that portion will appear to shine. A pixel camera installed above the sheet captures this shining portion and creates an image. A CCD camera is suitable as the pixel camera, and the number of pixels is 40 mm x 4 depending on the size of the subject sheet to be measured.
If the measurement area is about 0 mm, 512 bits x 5
Use the 12-bit one.

The created image is fixed by an image freezer, and then the light amount and area are photoelectrically converted, and further A / D converted and quantized into a digital signal. The quantization level may be 256 for plain paper. The quantized signal is binarized by an appropriate threshold value, and the image is two-dimensionally displayed as a set of 0 and 1 by a usual image processing method and stored in a computer.

The setting of the threshold value is a very important condition for carrying out the present invention, but it must be empirically determined for each product type based on the data obtained by repeating a large number of measurements. That is, it is necessary to change the setting of the threshold value between the varieties in which the fine fluff of several tens μ is a problem and the varieties in which the fluff of several hundred μ is the first problem.

The number and area of fluff are measured from a two-dimensional image stored by a computer, and the pixels (fluff portion) binarized by 1 at that time are continuously connected vertically or horizontally. If it is, it is determined that there is one fluff having a large area. Then, the area of the fluff is obtained from the number of consecutive pixels, and the number of fluffs is counted. Thus, the frequency distribution and total area of each area of fluff can be known.

If necessary, it is also possible to display the image of the CCD camera on a monitor-television and to see the state of the two-dimensional distribution of the binarized image by a conventional means. Needless to say, the measurement according to the present invention is performed in a dark room, so the apparatus of the present invention is installed in a dark room covered with a cover.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the main part of the device of the present invention. Tested
1 is placed on the support plate 9. The support plate is perforated with a number of small holes 10. The support plate 9 is placed on a vacuum box 11, and the inside of the vacuum box is a vacuum pump (not shown).
The sheet is kept in a vacuum, and the entire surface of the sheet is brought into close contact with the support plate to keep the sheet flat.

The semiconductor laser oscillator 3 is a commercially available output 5
An mWW wavelength of 670 nm (red light) was used. The conical reflecting mirror 4 shown in the figure is attached to the tip of the transmitter. Ray
The light is reflected to form a fan-shaped slit-shaped light beam 5,
The angle of the sector is 100 degrees, and the apex angle of the cone is set so that the thickness of the luminous flux is 2-3 mm. Although the reflection point of the laser light is on the generatrix of the cone, the distance between the reflection point and the cone axis is determined so that the light beam satisfies the above conditions. It is important in the present invention to obtain a light flux satisfying the above conditions by using a reflecting mirror having a special shape, which enables accurate measurement of fluff.

FIG. 4 shows the relationship between the luminous flux and the paper surface. The relationship between the luminous flux and the height of the paper surface can be finely adjusted by an adjusting device (not shown), but the lower thickness of the luminous flux is about 0.5 mm. It is necessary for the portion to hit the paper support plate so that no gap is created between the light flux and the paper surface.

The luminous flux travels straight in parallel with the paper surface while being in contact with the paper surface, but when it hits the fluff that is an obstacle, it is diffusely reflected, and that portion appears bright when viewed from above. For taking a picture, the CCD camera 6 is installed above the paper surface at a distance of about 300 mm. As the camera, a commercially available Sony XC-77CE was used. The total field of view area is 44 x 44 mm and the number of pixels is 512 x 51
Select 2 bits and the measurement area of the test sheet is 40 x 25 m
m. The total number of pixels for the measurement field of view is 135,72
The visual field (resolution) of 0 and 1 pixel is 0.0074 mm ² .

The quantization level is 256 and the image density is 0.
Digitally convert to an integer of ~ 255. As a method of determining the threshold value, for each varieties, a method in which the number of fluffs is calculated by calculating an average value by performing measurements by many eye measurements on the same sample and comparing the measured value according to the present invention with a quantized value The threshold value is determined for each product type.

Table 1 shows the measurement results for two types of woodfree paper. The high-quality paper (A) is a type having a large influence of fluffing, and the threshold is 13, and the high-quality paper (B) is a type having less fluffing, and the threshold is 33. The number of fluffs and the evaluation by the conventional visual method are also shown, but they are almost the same as the measurement results by the present invention.

[0020]

[Table 1]

[0021]

According to the method and apparatus of the present invention, the fluff existing on the surface of the sheet-like material is optically measured and image-analyzed, so that the number of fluff which is conventionally visually observed and It became possible to measure the area quantitatively and objectively. It is an invention useful for quality control of shipped products and examination of measures for preventing fuzzing.

[Brief description of drawings]

FIG. 1 is a perspective view of the device of the present invention.

FIG. 2 shows a laser light transmitter.

FIG. 3 is a plan view of a reflecting mirror and a laser beam.

FIG. 4 is a side view schematically showing that a laser light beam illuminates a paper surface and is diffusely reflected by fluff.

FIG. 5 is a flow sheet for performing the method of the present invention.

[Explanation of symbols]

1 ... Inspected sheet, 2 ... Irradiation light transmitter, 3 ...
The transmitter, 4 ・ ・ Reflector, 5 ・ ・ Irradiation luminous flux, 6 ・ ・ C
CD camera, 7 ... Focus adjustment screw 8 ... Slide surface, 9 ... Support plate, 10 ... Pore, 11
..Vacuum boxes K ... Fuzz, S ...

Claims (2)

[Claims] 1. A slit-shaped light beam is irradiated in a direction parallel to the sheet-like material so as to come into contact with the surface of the sheet-like material, and diffuse reflection is caused by fluff existing on the surface of the sheet-like material. The light to be captured is photographed by a pixel camera installed above the surface of the sheet-like object, and the light quantity and area of the diffusely reflected light is measured, and the light quantity and area are photoelectrically and digitally converted and stored in a computer. The obtained digital signal is binarized, and the binarized signal is two-dimensionally displayed and image-processed to measure the area and the number of fluffed portions of the sheet-like material. A method for measuring the fluffing of a sheet-like material, characterized by 2. A support member for fixing a sheet-shaped article in a plane, a light source for irradiating the surface of the sheet-shaped article with a slit-shaped light beam, and irregular reflection by the fluff of the sheet-shaped article. A pixel camera that captures light, a freezer that fixes the image of the camera, a photoelectric converter and an A / D converter that convert the light amount and area of the image, and a binary signal that stores the obtained digital signal. A device for measuring the fuzz of a sheet-like object, which comprises a computer for performing image analysis and image analysis.