JP2015212646A - Inspection apparatus for sheet-like object and inspection method of sheet-like object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection apparatus for sheet-like object capable of properly performing fabric weight inspection on various sheet-like objects.SOLUTION: An illumination device 302 and an imaging apparatus 303 are disposed at the same side relative to a perpendicular line at an imaging position 102 on the surface of a sheet-like object 301. Each of the illumination device 302 and the imaging apparatus 303 is arranged to have different angle relative to the imaging position 102. With this, an image of the sheet-like object 301 is taken via internal diffusion light which is reflected inside the sheet-like object 301 free from influences of surface reflection light or internally transmitting reflection light. Thus, the weight per unit area of the sheet-like object 301 is properly inspected free from the influences due to the thickness and color thereof.

Description

  The present invention relates to a sheet inspection apparatus and a sheet inspection method for continuously measuring the basis weight of a traveling sheet.

  As a conventional measurement and inspection apparatus for continuously measuring a sheet-like object, a transmission illumination device and a line CCD camera are arranged at a predetermined interval, and the sheet-like object is passed between them to transmit the illumination light. Some of them were measured by measuring the basis weight.

FIG. 8 is a diagram showing the configuration of a conventional measurement / inspection apparatus.
FIG. 8A is a configuration diagram of the imaging unit of the measurement and inspection apparatus described in Patent Document 1. FIG.
In FIG. 8A, in the conventional measurement and inspection of a sheet-like object, an illumination device 302 is provided below the traveling sheet-like object 301 to be inspected, and the sheet-like object 301 is irradiated with light. Then, the light irradiated from the illumination device 302 and transmitted through the sheet-like object 301 is measured by the line CCD camera 303, and the transmitted light is digitized as transmission luminance by the control device 304.

  The control device 304 calculates the transmittance from the digitized transmitted light in the presence of the sheet-like object 301 and the digitized transmitted light in the absence of the sheet-like object 301, and has created the transmittance in advance. The basis weight is derived by comparing with the basis weight conversion curve (see, for example, Patent Document 1).

The basis weight is a unit representing the mass per unit area of a sheet-like material such as cloth.
FIG. 8B is a diagram illustrating the measurement / inspection apparatus described in Patent Document 2, and is a configuration diagram of an imaging unit of the measurement / inspection apparatus.

  In FIG. 8B, a reflector 305 having a color opposite to the color of the detected sheet-like object 301 is installed under the traveling sheet-like object 301 to be inspected. Devices 307 a and 307 b are installed on the upper portion of the sheet-like object 301. The light emitted from the illumination devices 307 a and 307 b passes through the sheet-like object 301, reflects off the reflecting plate 305, passes through the sheet-like object 301 again, and then the luminance value is measured by the color line CCD camera 306.

  Furthermore, the control device 304 performs numerical inspection of the luminance value (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 9-256267 JP-A-6-50873

  However, in the conventional configuration shown in FIG. 8A, when the sheet-like object 301 is formed on a base material that does not transmit light, inspection is performed because transmitted light does not enter the line CCD camera 303. I can't do anything.

  Further, in the conventional configuration shown in FIG. 8B, the reflecting plate 305 of the sheet-like object 301 is set to the opposite blue color when the sheet-like object 301 is red, and the lighting devices 307a and 307b are blue. By using the illumination, the blue light entering the color line CCD camera 306 is extracted to measure the basis weight.

  However, when the sheet-like material 301 is white or translucent, black is the opposite color, but since the illumination of black is difficult, the illumination devices 307a and 307b are white. For this reason, when the reflecting plate 305 is black, white light is not sufficiently reflected by the black reflecting plate 305, and reflection on the surface of the sheet-like object 301 becomes dominant, so that the basis weight measurement cannot be performed correctly.

  Further, even if the reflecting plate 305 is made of a metal that is close to total reflection such as stainless steel so as to pass through the sheet-like object 301, transmitted light can be reflected by the reflecting plate 305, but the influence of surface reflection is excluded. Since it is not possible, the basis weight measurement cannot be performed correctly.

  Furthermore, when the sheet-like object 301 is formed on a base material that does not transmit light, it can be changed to a reflector and the base material can be of the opposite color. In the case of a semi-transparent film, the influence of surface reflection cannot be excluded and the basis weight measurement cannot be performed correctly.

As described above, in the conventional method using visible light, there is no method capable of correctly performing the basis weight inspection on the white or translucent sheet-like material 301 formed on the non-transmissive substrate.
The present invention solves the above-described conventional problems, and an object thereof is to correctly perform a basis weight inspection on various sheet-like objects.

  In order to achieve the above object, a sheet inspection apparatus according to the present invention is a sheet inspection apparatus that inspects a sheet formed on a substrate in a traveling state. An illuminating device that irradiates the imaging position with irradiation light, and an imaging device that is arranged at different positions on the same side as the illuminating device with respect to the normal of the sheet-like object at the imaging position and continuously images the sheet-like object And a control device that inspects the sheet-like object by analyzing the luminance of an image captured by the imaging device.

  The sheet inspection method of the present invention is a sheet inspection method for inspecting a sheet formed on a substrate while traveling, from an illumination device to an imaging position of the sheet. The sheet-like object by an illuminating step of irradiating irradiation light, and an imaging device arranged at a different position on the same side as the illuminating device with respect to the normal of the sheet-like object at the imaging position in a state where the irradiation light is irradiated And an inspection process for inspecting the sheet-like object by analyzing the luminance of the image captured by the imaging apparatus.

  As described above, the basis weight inspection can be correctly performed on various sheet-like objects.

The figure which illustrates the structure of the imaging part of the sheet-like object inspection apparatus of this invention The figure explaining the relationship between the brightness of reflected light when a sheet-like object is irradiated with light, and a basis weight. The figure explaining the relationship between the illumination angle in this invention, an imaging angle, and brightness The figure explaining the whole structure of the sheet-like object inspection apparatus of this invention The figure which shows the inspection flow of the sheet-like object inspection method of this invention The figure explaining the detail of the image conversion step in the sheet-like object inspection method of this invention The figure explaining the detail of the detailed inspection step in the sheet-like object inspection method of this invention The figure which shows the structure of the conventional measurement inspection device

Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example a sheet-like material formed on a non-translucent substrate.
FIG. 1 is a diagram illustrating a configuration of an imaging unit of a sheet inspection apparatus according to the present invention. In FIG. 1, the same components as those in FIG.

In FIG. 1, a sheet-like object 301 is created on a non-permeable base material 101 and is supplied in a running state.
As the non-permeable base material 101, stainless steel is used this time.
The non-permeable base material 101 is stainless steel this time, but may be a thin metal material such as copper or iron, and does not need to be a target color.

  A line CCD camera 303 which is an example of an imaging device is installed at a position of an imaging angle 104 from the traveling surface 103 which is the surface of the traveling sheet 301. The line CCD camera 303 images the imaging position 102 of the traveling surface 103 of the sheet-like object 301 formed on the base material 101. The imaging angle 104 is an angle formed by a line connecting the line CCD camera 303 and the imaging position 102 and the traveling surface 103.

  Further, an illumination device 302 that illuminates the imaging position 102 is installed so that the angle with respect to the traveling surface 103 becomes the illumination angle 105. That is, the illumination angle 105 is an angle formed by a line connecting the illumination device 302 and the imaging position 102 and the traveling surface 103.

  The control device 106 issues a lighting command to the illumination device 302, reads the data of the line CCD camera 303 by the control device 106, performs processing, and performs a fabric inspection of the sheet-like object 301. In the following description, a case where a captured image is generated by selecting a pixel while changing the illuminance of the illumination device 302 is taken as an example. However, the illuminance can be fixed and the captured image can be used as it is for inspection.

  In this embodiment, the line CCD camera 303 uses a 5120-pixel camera with a resolution of about 50 μm / pixel and performs imaging with a width of 256 mm, and the imaging angle 104 is set to 45 degrees as an example. . The illumination device 302 uses white LED illumination having an illumination width of about 400 mm and generating substantially parallel light, and the illumination angle 105 is set to 75 degrees.

  In the sheet-like object inspection apparatus according to the present embodiment, the light irradiated from the illumination device 302 is regularly reflected on the sheet-like object 301, and the direction in which the light is regularly reflected is defined as a regular reflection axis 107. The line CCD camera 303 is arranged so that the avoidance angle 108, which is an angle formed by the regular reflection axis 107 and the imaging angle 104, has a certain angle or more. In other words, the line CCD camera 303 is arranged on the same side as the illumination device 302, that is, on the side different from the regular reflection axis 107 with respect to the normal of the traveling surface 103 at the imaging position 102, so that the regular reflected light is line CCD camera. It arrange | positions so that it may not inject into 303. FIG.

  In this example, the brightness data of the captured image that has been converted into data is processed as 8-bit data from 0 to 255, but may be processed as brightness data of 12 bits, 16 bits, or 32 bits.

FIG. 2 is a diagram for explaining the relationship between the brightness of the reflected light and the basis weight when the sheet-like material is irradiated with light.
FIG. 2A is a conceptual diagram illustrating an optical path through which incident light is reflected.

  In FIG. 2A, the irradiation light 201 emitted from the illumination device 302 hits the sheet-like object 301 and is divided into internal penetrating light 202 and surface reflected light 203. Further, among the internal penetrating light 202, the strongest light travels straight and is reflected by the base material 101 to become internally transmitted reflected light 204 and internally diffused light 205. A part of the internal diffused light 205 is considered to be emitted from the sheet-like material 301.

At this time, the surface reflected light 203 and the internally transmitted reflected light 204 are reflected so that the angle direction of the regular reflection shaft 107 is the brightest.
FIG. 2B is a diagram for conceptually explaining the relationship of the brightness to the basis weight. Here, regardless of the arrangement position of the line CCD camera 303, the respective light amounts of reflected light and diffused light are theoretically shown as brightness.

Since the surface reflected light 203 is almost reflected from the surface, it can be considered that the brightness is almost constant regardless of the basis weight as shown in the figure.
The internal transmitted / reflected light 204 is considered to be bright because the base material 101 is made of stainless steel this time and does not attenuate when the basis weight is small, and becomes dark when the basis weight is large.

  The internal diffused light 205 is diffused after entering the inside of the sheet-like material 301 and exits in various directions. However, the basis weight of the sheet-like material increases, the internal transmitted reflected light 204 decreases, and the basis weight is increased. It tends to increase accordingly.

In FIG. 2B, the brightness is converted into 8-bit data acquired by the CCD camera 303 which is an imaging device, and is expressed in the range of 0-255.
Here, when the imaging device 303 is installed in the direction of the regular reflection axis 107, the light received by the imaging device 303 is a combination of the surface reflected light 203, the internal transmitted reflected light 204, and the internal diffused light 205. The degree of influence of the internally transmitted reflected light 104 varies depending on the thickness of the sample, and the captured brightness differs even when the basis weight is the same. In other words, the brightness of the thin sample 206 increases the proportion of the light that passes through the sample, so that the internal transmitted reflected light 204 increases and the influence of the internal transmitted reflected light 204 becomes stronger. Brightly detected. On the other hand, the brightness of the thick sample 207 is less than 200, which is darker than the brightness of the thin sample 206, because the ratio of the light transmitted through the sample is reduced, and the surface reflected light 203 is constant and the internal transmitted reflected light 204 is reduced. Is detected. From the above, the regular reflection direction combined light 208, which is a combination of the surface reflected light 203, the internal transmitted reflected light 204, and the internal diffused light 205, becomes unstable regardless of the basis weight. Therefore, when inspecting samples having different thicknesses, the basis weight cannot be calculated from the detected brightness.

  On the other hand, when the imaging device 303 is arranged at an angle that is not easily influenced by the internal transmitted / reflected light 204, the influence of the internal diffused light 205 is dominant in the received light, and the thin sample 206 is darker than the thick sample 207. However, the basis weight and brightness can be uniquely determined and can be measured.

  The sheet-like object inspection apparatus and the sheet-like object inspection method of the present invention are characterized by the arrangement positional relationship between an illumination device that irradiates light to the sheet-like object and an imaging device that images the sheet-like object. That is, the illuminating device irradiates light to the imaging position of the sheet-like object. The imaging device is disposed at a position where the surface reflected light, which is reflected from the surface of the sheet-like object, is not incident. Specifically, the illumination device and the imaging device are arranged on the same side with respect to the perpendicular at the imaging position on the surface of the sheet-like object. And the direction of the illuminating device and imaging device seen from the imaging position is varied. That is, the illumination device and the imaging device are arranged at different positions on the opposite side to the direction in which the reflected light is irradiated with respect to the above-described normal.

  By arranging the illumination device and the imaging device in such a positional relationship, the internal diffused light reflected inside the sheet-like object is reduced while the captured image suppresses the influence of the surface reflected light and the internally transmitted reflected light. Since the captured image is obtained, the influence of the thickness and color of the sheet-like material can be suppressed, and the basis weight and the like can be accurately inspected.

Hereinafter, specific examples of the relationship between the illumination angle, the imaging angle, and the brightness in the sheet-like object inspection apparatus and inspection method of the present invention will be described with reference to FIGS.
FIG. 3 is a diagram for explaining the relationship between the illumination angle and the imaging angle and the brightness in the present invention.

  FIG. 3A is a relationship diagram when the illumination angle 105 is set to 75 degrees, and the angle between the regular reflection shaft 107 and the traveling surface 103 is 105 degrees. The regular reflection angle 402 is an opposite angle, and the angle formed by the traveling surface 103 of the regular reflection shaft 107 is 75 degrees.

  In this figure, the thin sample tendency 401 is the brightness when the thin sample 206 is imaged by changing the imaging angle 104 from 15 degrees to 165 degrees every 15 degrees when the illumination angle 105 is set to 75 degrees. Show the trend.

However, the measurement is not performed near the imaging angle of 75 degrees because it interferes with the illumination device 302.
The thin sample tendency 401 shows a tendency that the brightness is the brightest when the image is taken from the direction of the regular reflection angle 402 of the illumination, and gradually becomes darker as it deviates from it.

On the other hand, the thicker sample tendency 403 shows a tendency that the brightness is brightest between 90 degrees and the regular reflection angle 402, and gradually becomes darker as it deviates therefrom.
If it is away from the regular reflection angle 402 by an avoidance angle of about 108, the influence of the internal transmitted reflected light 204 is reduced, and the influence of the internal diffused light 205 tends to be strong, so that it is suitable for the inspection of the basis weight.

  In this example, the measurable range 404 is a range of 15 degrees to 60 degrees and 150 degrees to 165 degrees in which the thick sample tendency 403 is detected brighter than the thin sample tendency 401.

  Further, within the measurable range 404, a condition where the brightness difference 405 between the thin sample tendency 401 and the thick sample tendency 403 is 48 or more is set as a good measurement range 406 and set as a range where the basis weight can be determined.

FIG. 3B is a diagram illustrating the relationship of the imaging range with respect to the illumination angle, and is a relationship diagram in which the illumination angle of FIG. 3A is confirmed in a wide range.
FIG. 3B shows the relationship when the illumination angle 105 is changed in the range of 15 to 165 degrees and the imaging angle 104 is changed from 30 to 90 degrees.

  When the illumination angle 105 is changed from 15 degrees to 90 degrees and the imaging angle 104 is changed from 105 degrees to 165 degrees, the imaging angle 104 is set to 15 degrees to 75 degrees, and the illumination angle 105 is set to 105 degrees. It has the same meaning as the data obtained by setting ˜165 degrees.

  When data at a plurality of angles are collected in this way, the measurement inappropriate range 407 is obtained when the avoidance angle 108 is 30 degrees or less, and when the avoidance angle 108 that is the difference between the illumination angle 105 and the imaging angle 104 is 45 degrees or more, It was found to be a measurable range 404.

  Further, the good measurement range 406 in which the luminance difference 405 is 48 or more has the avoidance angle 108 of 45 degrees or more, the illumination angle 105 and the imaging angle 104 are both 45 degrees or more and 75 degrees or less, and the illumination angle 105 It was found that the imaging angle 104 was 15 degrees or more apart. As can be seen from the above specific examples, the arrangement positions of the imaging device and the illumination device are determined based on the following two points. The first point is that if the imaging device is arranged within a certain range from the regular reflection axis 107, the influence of the regular reflection light becomes strong, which is not suitable for measurement. The second point is that when the imaging angle 104 and the irradiation angle 105 are below a certain level, the amount of light obtained itself is reduced, which is not suitable for measurement. In addition to the material, configuration, and structure of the measurement target, these points are comprehensively influenced by the illumination device, the imaging device, and the like, and the range is determined. Therefore, in addition to the material, configuration, and structure of the measurement target, the arrangement positions of the imaging device and the lighting device are determined by the lighting device, the imaging device, and the like.

A configuration example of the sheet inspection apparatus and sheet inspection method of the present invention based on the above results will be described.
First, FIG. 4 is a diagram for explaining the overall configuration of the sheet inspection apparatus of the present invention.

  In FIG. 4, an illuminating device 302 that irradiates the sheet-like object 301 with irradiation light while changing the brightness based on the illumination information 502 sent from the illumination switching function 501 is provided above the sheet-like object 301.

  Irradiation light is applied to the sheet-like object 301 from the illumination device 302, and light reflected by the sheet-like object 301 is measured by the line CCD camera 303. In the image input unit 503, the reflected light is corrected after being converted to reflected luminance, and is converted into data as a captured image 504.

  This time, the illumination information 502 for setting the irradiation light is set by 8-bit data of 0 to 255. That is, the illumination information 502 is expressed by a set value from 0 to 255 in which the illumination light becomes brighter as the set value increases. When the illumination information 502 is set to 0, it means that the illumination is turned off. In addition, this time, the reflected luminance data of the captured image 504 converted into data is processed with 8-bit data of 0 to 255, but may be processed with luminance data of 12 bits, 16 bits, or 32 bits. .

The captured image 504 that has been converted into data is composed of 5120 pixels in the horizontal direction and 30 lines in the traveling direction, and is sent to the measurement inspection unit 505 in the control device 106 after imaging.
Data for each traveling direction of the captured image 504 is referred to as line data. In the captured image 504, line data 506 in the middle of switching the irradiation light of the illumination device 302 and line data 507 after the irradiation light has been switched reliably. Is composed of a collection of data that appears repeatedly.

  The measurement inspection unit 505 extracts only the line data 507 after the irradiation light of the illumination device 302 has been switched reliably from the captured image 504, and integrates the line data 507 into a group for each irradiation light setting. Separate setting images 508a to 508c are created.

  In this embodiment, the irradiation light setting is set to three types, 1000 captured images 504 are used, the horizontal direction is 5120 pixels, and the traveling direction is 1000 lines of irradiation light-specific setting images 508a to 508c. However, during the creation and inspection, the next image capturing and image input are performed in parallel, and the entire area of the sheet-like object 301 can be inspected.

  Among them, the setting image 508a for each of the brighter irradiation lights has the illumination information 502 set to 50, the setting image for each irradiation light 508b has the lighting information 502 set to 30, and the second setting image 508c for each irradiation light is also the same. The lighting information 502 is set to 30.

The number of lines 1000 depends on the memory capacity of the control device 106, and a larger number of lines can be set as the memory capacity increases.
The basis weight inspection image 509 is selected from the setting images 508a to 508c for each irradiation light, and an image with optimal illumination conditions is selected for each pixel, converted from transmission luminance data to basis weight data, and then the basis weight is inspected. As a result.

  Similarly, the detailed inspection image 510 is selected and synthesized from the setting images 508a to 508c for each irradiation light for each pixel, and is subjected to detailed inspection for foreign matters, perforations, and the like. The detailed inspection image 510 and the basis weight inspection image 509 are the same image, but are used after being subjected to image processing according to the inspection purpose, as will be described later.

A combination of the above-mentioned basis weight inspection and detailed inspection results is displayed on the inspection result screen 511.
The inspection image creation method and inspection method will be described in detail later.

  The illumination switching function 501 generates illumination information 502 to the illumination device 302 and creates a signal to the image input unit 504 based on a signal from the position measurement device 512 that measures the position of the sheet-like object 301. .

Next, the operation of the measurement inspection unit 505 will be described with reference to FIGS.
FIG. 5 is a diagram showing an inspection flow of the sheet-like object inspection method of the present invention.
In FIG. 5, the image selection step S61 is a step of creating the setting images 508a to 508c for each irradiation light from the captured image 504, and since it has been described before, details are omitted here.

  In the next image conversion step S62, a noise-removed image is created from the irradiated light setting images 508a to 508c by image compression in accordance with the manufacturing conditions of the target sheet 301.

The sheet-like material 301 targeted this time is a PVDF nonwoven fabric having a diameter of about 400 to 2000 nm by an electrospinning method, and the basis weight of the measurement target is a specification in a manufacturing range of about 0 to 12 g / m ^2. The range is the same.

  As a feature of production, although the object is not spun in a certain direction, fine yarns are stacked in various directions, and relatively random optical variations without repeatability occur. This becomes a noise factor and causes variations in measured values.

  Therefore, by experiments, relatively stable data was obtained when image compression of 1/5 to 1/200 (one side) was performed. As the compression ratio increases, the noise becomes smaller, but it becomes difficult to grasp a fine tendency. Therefore, in this time, in order to grasp a fine tendency, a measurement inspection by compression of 1/10 (one side) is performed. As the compression rate increases as the object weight decreases, the higher the compression rate, the greater the noise removal effect. Therefore, the compression rate may be changed for each of the irradiation light setting images 508a to 508c.

  Next, in order to convert and synthesize the basis weight with respect to the setting image by irradiation light after compression of the image size of 5120 × 1000 to the size of 512 × 100, the pixel is set for each pixel of each image. Create a flag map to use or not.

The flag map is created by determining the upper and lower thresholds according to the irradiation light condition used using Equation 1 and the adjacent irradiation light condition.

Flag nij = f1 (lower threshold n ≦ transmission luminance nij <upper threshold n) Equation 1

i: Horizontal position of image (1 to 512)
j: Travel direction position of image (1 to 100)
n: means a setting image for each irradiation light (1-3)
The setting image means data when the illumination is set to 50 when n = 1, the illumination is set to 30 when n = 2, and the illumination is set to 30 when n = 3.
Flag nij: Use / non-use flag data (valid: 1, invalid: 0)
f1 (): Returns 1 if the determination is correct, returns 0 if it is not correct Upper limit threshold n: Upper limit brightness threshold (0 to 255)
Lower threshold n: Lower luminance threshold (0 to 255)

Next, in accordance with the luminance basis weight conversion formula (Formula 2), data in which the data of each pixel is converted from the luminance into the basis weight is created from the post-compression irradiation light setting image.

Weight per unit area nij = fn (transmission luminance nij) Equation 2

Transmission luminance nij: Transmission luminance data (0 to 255) in each illumination setting of the setting image for each irradiation light after compression
Weight per unit area nij: Per unit weight data (0 to 15) in each illumination setting after luminance basis weight conversion
fn (): transmission luminance basis weight conversion formula

Next, in step s63 for synthesizing the basis weight, a plurality of basis weight data are synthesized. The composition is performed based on Expression 3 using a flag map for use / non-use of image data created by irradiation light setting and a weight-converted data table.

Composite weight ij: Weight of each position after synthesis This means that the average of the weight per unit area is obtained using only the data of the effective part at each pixel position.

In the next inspection step S64, it is determined whether or not the measured composite basis weight ij is within the non-defective range with respect to the reference value at each position, using Expression 4 and Expression 5.

Mass per unit defect ij = f2 (composite basis weight ij <weight per unit upper limit reference value ij)
Less weight per unit area ij = f2 (weight per unit lower limit reference value ij ≦ composite basis weight ij)

f2 (): Expression that returns 0 when the determination is correct, 1 when it is not correct ij: Multiple defective weight per unit area ij: Multiple defective data per unit area (good part: 0, defective part: 1)
Less weight per unit area ij: Less per unit area weight data (good part: 0, defective part: 1)
Basis weight lower limit reference value ij: judgment weight lower limit value (0 to 10)
Basis weight upper limit reference value ij: upper limit value for weight per unit area (0 to 10)

The basis weight amount upper / lower limit reference value ij may be the same at any position, and the determination may be made using only the upper limit reference value and the lower limit reference value, but there is a specific distribution even if the target basis weight is a non-defective product. In consideration of the case, it is possible to make a determination with different reference values at each position by making the upper and lower reference values exist for the number of pixels ij.

  In addition, when setting a plurality of vertices, connect the vertices with a 3D spline curve and set them, or measure the reference workpiece and use the value as the reference value. Simplification may be achieved.

  After labeling each data of the above-mentioned basis weight multiple defects and basis weight low defect by adjacent information, each labeled defect group is further updated according to judgment conditions such as length of one side and area. The good / bad judgment may be performed.

The detailed inspection step S65 performed in parallel with the fabric weight inspection is provided to detect detailed defects that may be missed in the compression process in the fabric weight measurement step.
In the next display step S66, a raw image of the setting image 508b according to the irradiation light having a medium brightness among the setting images 508a to 508c according to the irradiation light is displayed, and the basis weight multiple defect, the basis weight small defect, and the detail defect are graphically displayed. Display with a different color.

Next, an example of the image conversion step S62 will be described in detail with reference to FIGS.
FIG. 6 is a diagram for explaining the details of the image conversion step in the sheet-like object inspection method of the present invention, and is a diagram showing the dose.

  In FIG. 6, each pixel of each image is used with respect to each set image 508a to 508c by irradiation light, which is compressed to the irradiation light-specific setting image obtained by compressing each side to a size of 512 × 100. Create a flag map of whether or not to do so.

Here, a method for selecting the illumination information 502 to be used and a method for creating the upper and lower threshold values will be described in detail.
First, the measurement conditions this time are the measurement resolution,

Is defined on the condition that the measurement resolution is 10 or more and that the weight per unit area can be measured in the range of 0 to 12 g / cm ² .

  First, luminance basis weight conversion data is created in advance using a sample whose basis weight is known in each illumination information 502. Then, the upper and lower threshold range is determined using the luminance basis weight conversion data created in advance.

At that time, the basis weight range since 0~12g / cm ^2, if the basis weight is but measurement resolution even 12 g / cm ² determines the 10 or more lighting information 502, the illumination data is not the measurement resolution is more than 10, the same Since the resolution is improved by imaging a plurality of times under illumination conditions, the illumination conditions are determined in consideration of this point.

In this case, when the illumination is set to 30, since the measurement resolution is 8 when the basis weight is 12 g / cm ² , the relationship between the input luminance and the basis weight is as shown in a graph 701. Generally, when the number of times of imaging increases, the resolution becomes sqrt (n) times as large as the number of times of imaging n. When the illumination was set to 30, the measurement resolution was 8 at a basis weight of 12 g / cm ² , so by taking the image twice, the resolution increased by sqrt (2) ≈1.4142 times, and 8 × A measurement resolution of sqrt (2) ≈11.3 can be expected. Therefore, when the illumination is set to 30, the image is taken twice. Thus, when the illumination is set to 30, the measurement resolution can be expected to exceed 10 in the entire range of 0 to 12 g / cm 2 only by imaging twice.

  On the other hand, when the input luminance value is high, higher measurement resolution can be realized. Therefore, when the illumination is set to 30, in the range in which the measurement resolution is higher than when imaging is performed twice, the illumination 50 setting having a high input luminance value is also switched and used. A relationship between the input luminance and the basis weight when the illumination is set to 50 is shown at 702.

As conditions for switching the illumination to be used, the range was set on the condition that the measurement resolution was in a range exceeding 10 and that the measurement resolution was higher than the twice measurement when the illumination was set to 30. When the illumination is set to 50, the upper limit threshold is set to 220 because the input luminance is less than 220 and the measurement resolution exceeds 10. In addition, when the illumination is set to 50, the measurement resolution when the basis weight is 6 g / cm ² is 16, and when the illumination is set to 30, the basis weight is about 6 g / cm ² . The measurement resolution was about 15.5. Therefore, the lower limit threshold value of the input luminance when the illumination is set to 30 is set to 110 near the basis weight 6 g / cm ² .

  Further, the inspection can be performed if the measurement resolution is 10 or more, but it is possible to set the measurement resolution in a specific range to be increased. As an example of the setting, this time, when the illumination is set to 50, the image is taken once and the illumination is 30. In this case, the inspection is performed using the condition that the imaging is performed twice.

  As a result, when the illumination is set to 50, the lower limit threshold is 0, and the upper limit threshold 703 is 220. When the illumination is set to 30, the lower limit threshold 704 is 110, and the upper limit threshold is 255. .

  When using illumination switching, the lower limit threshold of the illumination setting when measuring the thinnest basis weight side is always 0, and the upper limit threshold of the illumination setting when measuring the thickest basis weight side is always 255. It is set as follows. This is for avoiding a state in which the detected basis weight is indefinite regardless of the input luminance.

This time, the illumination information 502 is created in increments of 5 from 20 to 40, and the luminance per unit weight conversion data in increments of 10 from 40 to 120 is created in advance.
As described above, in this measurement condition, the effective range threshold when the illumination information 502 is set to 50 is the upper limit threshold: 220, the lower limit threshold: 0, and the illumination information 502 is set to 30. The threshold values of the effective range are an upper limit threshold value: 255 and a lower limit threshold value: 110.

In this way, a flag map is created using Expression 7 with the determined upper and lower thresholds. Equation 7 is the same as Equation 1.

Flag nij = f1 (lower threshold n ≦ reflection luminance nij <upper threshold n) Equation 7

Upper threshold n: Upper luminance threshold (0 to 255)
The lower limit threshold n when n is the minimum value is 0.
Lower threshold n: Lower luminance threshold (0 to 255)
The upper threshold n when n is the maximum value is 255.

For example, if the illumination is set to 50 and n = 1, the lower threshold 1 is 0 and the upper threshold 1 is 220.
Next, in accordance with the luminance basis weight conversion formula, data obtained by converting the data of each pixel from the reflected luminance to the basis weight is created from the post-compression setting image for each irradiation light.

This time, the following conversion formula was used as Formula 8.

Weight per unit area nij = constant n1 × (luminance nij) ³ + constant n2 × (luminance nij) ² + constant n3 × (luminance nij) + constant n4

n: means a setting image according to light quantity (1-3)
When n = 1, the illumination is set to 50, when N = 2, the illumination is set to 30, and when N = 3, the illumination is set to 30.
Luminance nij: Luminance value constant n1, constant n2, constant n3, constant n4 of each pixel: constant for weight per unit area when illumination is n. For example, when illumination is set to 50 and n = 1, constant 11 is 1.6. X10-6, constant 12 is -0.0005, constant 13 is 0.0747, and constant 14 is -2.1095.

The conversion formula and each constant are set according to the object, and when the manufacturing conditions and materials change, it is necessary to calibrate again and set the constant.
This time, the luminance basis weight conversion is performed using the conversion formula. However, a table may be prepared without using the formula, and a conversion may be performed based on the table.

In addition, this time, setting was performed under the condition of 0 to 12 g / cm ² range measurement, but this is not a limiting condition, but by using brighter illumination conditions and imaging conditions, measurement of an object with a larger basis weight Is also possible.

Next, the detailed inspection step S65 will be described in detail with reference to FIGS.
FIG. 7 is a diagram for explaining the details of the detailed inspection step in the sheet-like object inspection method of the present invention. FIG. 7A is a flowchart of detailed inspection, and FIG. 7B is a diagram for explaining a defect.

In FIG. 7, small defects that may be overlooked in the compression process in the basis weight measurement are detected. It is the defect defect 801 and the foreign object defect 802 that are to be detected.
First, in the image conversion step S62, the image size is reduced by reducing the data size to 1/10, whereas in the noise removal step S81, the image size is changed by using a moving average filter of around 5 to 20 pixels. Noise is removed without change, and the image after the implementation is set as the illumination setting image for each irradiation light after noise removal.

  Next, in the flag creation step S82, the upper limit threshold value n and the lower limit threshold value n derived from the luminance weight per unit amount conversion formula are used for the illumination-specific illumination setting images 508a to 508c created in the noise removal step S81. Thus, an inspection flag map is created by Expression 9.

Inspection flag nst = f1 (lower threshold n ≦ transmission luminance nst <upper threshold n)

s: horizontal position of image (1-5120)
t: image traveling direction position (1 to 1000)
n: means a setting image for each irradiation light (1-3)
When n = 1, the illumination is set to 50, when n = 2, the illumination is set to 30, and when n = 3, the illumination is set to 30.
Inspection flag nst: Use / non-use flag data (valid: 1, invalid: 0)
f1 (): Expression that returns 1 if the determination is correct, and returns 0 if it is not correct Next, in the differentiation step S83, differentiation is performed in eight directions for each of the three setting images of the illumination by illumination after noise removal. Emphasize defects using filters. At this time, if a differential filter is used, difference data is obtained, so that a value of 128 is added to the result, and the data is shifted to the center of 128.

  In the next image synthesis step S84, the image is synthesized for shortening the examination time by using the previous inspection flag nst and the differential image data nst created in the differentiation step S73. Create st.

Differential image data nst: Data after differentiation at each position of the captured image (0 to 255)
Composite inspection data st: inspection data (0 to 255) at each position of the captured image
In the next labeling step S85, flaw defect candidate data v and foreign substance defect candidate data w are created for the composite inspection data st.

Scratch defect candidate data v is created as labeling data by extracting a pixel portion detected by synthetic inspection data st> threshold 803.
Similarly, the foreign substance defect candidate data w is created as labeling data by extracting pixel portions detected by the combined inspection data st <threshold 804.

Each labeling data stores information such as the position of the center of gravity, vertical size, horizontal size, area, average luminance, and the like.
The threshold value 803 is set in the range of luminance values 128 to 178, and the threshold value 804 is set in the range of luminance values 78 to 128.

In the next defect inspection step S86, the final inspection is performed on the defect defect candidate data v and the defect defect candidate data w, which are labeling data.
In the detailed inspection, there are cases where the amount of irradiation light used increases and the displacement of the measurement position increases. Therefore, this time, assuming that the target defect is 4 pixels or more, the detection capability is not affected even if it is shifted by 1 pixel.

  According to such a configuration, a traveling object is imaged under a plurality of irradiation light conditions, and the measurement resolution is kept within a certain range even for an object with a small basis weight and an object with a large basis weight using the imaging data. By acquiring the maintained image, the basis weight can be measured and inspected with high accuracy, and the defect inspection classified into the basis inspection and the classification can be performed in a smaller space, and the quality can be improved.

  INDUSTRIAL APPLICABILITY The present invention can continuously measure the basis weight of a running sheet-like material, and has a great effect as a basis weight measuring device. Further, for example, it is effective not only in measuring the basis weight but also in measuring the thickness and the concentration of the coloring material contained in the sheet-like material.

  Furthermore, the sheet-like object inspection apparatus and inspection method of the present invention can inspect a white or semi-transparent traveling sheet-like object created on a non-permeable substrate with a certain level of measurement inspection accuracy. It becomes.

  Not only in the field of continuously measuring the basis weight of sheet-like objects such as nonwoven fabrics and paper, or synthetic resin sheets, but depending on the object, multiple wavelengths with different wavelengths of visible light, that is, the color of visible light It can be applied not only to inspection under conditions, but also to inspection using electromagnetic waves that pass through sheet-like objects such as ultraviolet rays, x-rays, infrared rays, and ultrasonic waves as well as visible light.

  Further, in the above description, the case where the base material on which the sheet-like material is formed has no translucency has been described as an example. However, if the light transmitted through the sheet-like material is reflected by the base material, this reflected light is reflected. Can be inspected even on a sheet-like material formed on a translucent substrate.

  The present invention provides a sheet-like object inspection apparatus and sheet-like substance inspection method that can correctly perform a basis weight inspection on various sheet-like objects and continuously measure the basis weight of a sheet-like object while traveling. Useful.

DESCRIPTION OF SYMBOLS 101 Base material 102 Imaging position 103 Running surface 104 Imaging angle 105 Illumination angle 106 Control apparatus 107 Regular reflection axis 108 Avoidance angle 201 Irradiation light 202 Internal penetration light 203 Surface reflection light 204 Internal transmission reflection light 205 Internal diffused light 206 Sample 207 Sample 208 Combined light in regular reflection direction 301 Sheet-like object 302 Illumination device 303 Line CCD camera 304 Control device 305 Reflector 306 Color line CCD camera 307a Illumination device 307b Illumination device 401 Thin sample tendency 402 Regular reflection angle 403 Thick sample tendency 404 Measurable range 405 Luminance difference 406 Measurement good range 407 Measurement inappropriate range 501 Illumination switching function 502 Illumination information 503 Image input unit 504 Captured image 505 Measurement inspection unit 506 Line data in the middle of switching 507 Line data after switching 508a Irradiation light setting image 508b Irradiation light setting image 508c Irradiation light setting image 509 Weight measurement image 510 Detailed inspection image 511 Inspection result screen 512 Position measurement device S61 Image selection step S62 Image conversion Step S63 Step of synthesizing the basis weight S64 Inspection step S65 Detailed inspection step S66 Display step 701 Graph 702 Graph 703 Upper luminance threshold 704 Lower luminance threshold 801 Scratch defect 802 Foreign object defect 803 Threshold 804 Threshold S81 Noise removal step S82 Flag creation step S83 Differentiation Step S84 Image composition step S85 Labeling step S86 Defect inspection step

Claims (11)

A sheet inspection apparatus that inspects a sheet formed on a substrate in a traveling state,
An illumination device for irradiating the imaging position of the sheet-like object with irradiation light;
An imaging device that is arranged at different positions on the same side as the illumination device with respect to the normal of the sheet-like material at the imaging position and continuously images the sheet-like material;
A sheet-like object inspection apparatus, comprising: a control device that inspects the sheet-like object by analyzing luminance of an image captured by the imaging device.   2. The sheet inspection apparatus according to claim 1, wherein the inspection of the sheet is a basis weight measurement inspection and a defect inspection. An angle formed by a reflection optical axis in which the irradiation light irradiated from the illumination device is regularly reflected on the sheet-like object and a line connecting the imaging device and the imaging position is 45 degrees or more;
In addition, the angle between the line connecting the illumination device and the imaging position and the line connecting the imaging device and the imaging position with the traveling surface of the sheet-like object are both in the range of 15 degrees to 165 degrees. The sheet-like object inspection apparatus according to claim 1 or 2, characterized by the above-mentioned. An angle formed by a reflection optical axis in which the irradiation light irradiated from the illumination device is regularly reflected on the sheet-like object and a line connecting the imaging device and the imaging position is 45 degrees or more;
In addition, the angle between the line connecting the illumination device and the imaging position and the line connecting the imaging device and the imaging position with the traveling surface of the sheet-like object are both in the range of 45 degrees to 75 degrees,
3. The sheet shape according to claim 1, wherein an angle formed by a line connecting the illumination device and the imaging position and a line connecting the imaging device and the imaging position is 15 degrees or more. Inspection equipment. A sheet inspection method for inspecting a sheet formed on a substrate in a traveling state,
An illumination step of irradiating the imaging position of the sheet-like object with illumination light from an illumination device;
An imaging step of continuously imaging the sheet-like object by an imaging device disposed at a different position on the same side as the illumination device with respect to the normal of the sheet-like object at the imaging position in a state where the irradiation light is irradiated; ,
An inspection step of inspecting the sheet-like material by analyzing luminance of an image captured by the imaging device.   The sheet inspection method according to claim 5, wherein the inspection of the sheet is a basis weight measurement inspection and a defect inspection.   The sheet inspection method according to claim 6, wherein the defect inspection is performed by classifying the defect into a defect and a foreign matter defect. An angle formed by a reflection optical axis in which the irradiation light irradiated from the illumination device is regularly reflected on the sheet-like object and a line connecting the imaging device and the imaging position is 45 degrees or more;
In addition, the angle between the line connecting the illumination device and the imaging position and the line connecting the imaging device and the imaging position with the traveling surface of the sheet-like object are both in the range of 15 degrees to 165 degrees. The sheet-like object inspection method according to any one of claims 5 to 7, wherein: An angle formed by a reflection optical axis in which the irradiation light irradiated from the illumination device is regularly reflected on the sheet-like object and a line connecting the imaging device and the imaging position is 45 degrees or more;
In addition, the angle between the line connecting the illumination device and the imaging position and the line connecting the imaging device and the imaging position with the traveling surface of the sheet-like object are both in the range of 45 degrees to 75 degrees,
The angle formed by a line connecting the illumination device and the imaging position and a line connecting the imaging device and the imaging position is 15 degrees or more. The sheet-like object inspection method as described in 1.   The type and the number of the irradiation light to be irradiated are determined according to the measurement accuracy and the measurement range of the measurement target based on a calibration curve measured in advance. Item 1. The sheet inspection method according to Item 1.   The sheet-like material inspection method according to any one of claims 5 to 10, wherein the sheet-like material is a translucent material and is a non-woven fabric created by electrospinning.