JP2012078144A - Surface defect inspection device for transparent body sheet-like material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable defect inspection device detecting defects without omission by forming, in a clear contrast image, an image of a rugged defect with small curvature changes formed on a transparent body sheet-like material surface.SOLUTION: The surface defect inspection device for sheet-like materials includes: lighting means having a mechanism reflecting light by a mirror that is disposed in an irradiation direction of parallel light emitted from a light source, in inspecting a rugged defect formed on a sheet-like material surface of a traveling transparent body; a curved-surface screen transmitting the parallel light obliquely to the traveling direction of the sheet-like material and forming an image with the transmitted light; imaging means having a mechanism capable of adjusting an angle, with a focal point on a curvature radius of the curved surface of the screen used as a start point, so as to focus the light that forms the image on the curved surface of the screen; and signal processing means for detecting the light that forms the image on the screen by the imaging means, as a contrast signal.

Description

  The present invention relates to a low-cost inspection apparatus that detects and determines an irregular defect on the surface of a transparent sheet in-line.

  In recent years, the requirement standards for foreign substances and defects of optical films used for liquid crystals and the like and high-functional films used for electronic equipment parts are becoming stricter. These sheet-like materials are manufactured in a clean room, and quality control is performed by detecting foreign matters and defects on the sheet-like material by a defect inspection machine in the production line. However, a dent defect or a convex defect (hereinafter referred to as a concavo-convex defect) may occur on the surface of the sheet-like material due to a foreign matter adhering to a roll or the like in the process. In order to detect this irregularity defect, a defect inspection machine that transmits light and detects it by changing the density of transmitted light is installed, but this detection method has a small density difference caused by the irregularity defect, There was a problem of missing a defect. In addition, irregular inspections outside the quality standard may be found by visual inspection before shipment, and in that case, there is a problem that it leads to a huge loss of waste and loss of opportunity. In addition, there is a risk of missing the uneven defect even in the visual inspection and shipping, which may cause a great loss.

  In order to solve this problem, in the line of sheet-like material, the linear light of the fluorescent lamp is projected obliquely from the running direction, the transmitted light is captured as a light / dark signal by the CCD camera, and the dent is made while correcting the unevenness of the light quantity. A method for inspecting uneven defects such as the above has been proposed (for example, see Patent Document 1). However, the uneven defect with small curvature change is inferior in parallelism with linear light composed of a fluorescent lamp or the like, so that the difference from the transmitted light of the sheet-like material having no defect is small and the defect may be overlooked. There was a problem.

  Also, in the line of sheet-like material, irradiate parallel light from an oblique direction, detect transmitted light and reflected light with independent optical systems and image sensors, and compare and collate each intensity distribution to detect uneven defects A method of inspection (for example, see Patent Document 2) has been proposed. However, since this method requires two optical systems and an image sensor, the apparatus is costly. Further, it is difficult to adjust the optical axes of a plurality of optical systems together, and it takes a lot of time. There was a problem.

JP2009-236493 JP 2001-41719 A

  The present invention solves the above-mentioned problems of the prior art, and forms defects in a state where the curvature change having a small curvature generated on the surface of the transparent sheet is in the state where it becomes the clearest bright and dark image. An object of the present invention is to provide a defect inspection apparatus that can detect without omission and has high reliability.

As a result of intensive studies, the present inventors have found that the above problems can be solved, and have completed the present invention.
That is, the present invention provides an illumination means having a mechanism for reflecting by a mirror arranged in the irradiation direction of the parallel light emitted from the light source in the inspection of the uneven defect generated on the surface of the traveling transparent sheet.
A curved screen for transmitting the parallel light obliquely with respect to the traveling direction of the sheet and imaging the transmitted light; and
Imaging means having a mechanism capable of adjusting the angle from the focal point on the curvature radius of the curved surface of the screen so as to focus the light imaged on the curved surface of the screen;
Signal processing means for detecting light imaged on the screen by the imaging means as a light and dark signal;
It is related with the surface defect inspection apparatus of the sheet-like material characterized by comprising.

  As a preferred embodiment, the signal processing means detects the level of the detected light / dark signal as a concavo-convex defect using a threshold value, and determines the size and shape of the concavo-convex defect, and the surface of the sheet-like object The present invention relates to a defect inspection apparatus.

  As a preferred embodiment, the light reflected by the mirror of the illumination means is transmitted at an incident angle of 10 ° to 60 ° with respect to the traveling direction of the sheet-like material. About.

  As a preferred embodiment, the imaging means has a mechanism for adjusting the angle about the focusing position as an axis so as to match the imaging position of the curved screen in conjunction with the deflection angle of the mirror of the illumination means. The present invention relates to a sheet-like surface defect inspection apparatus.

  As a preferred embodiment, a one-dimensional image sensor is used for the imaging means, and a light / dark signal for each scan is accumulated while updating a certain number of lines by the signal processing means, and a plurality of threshold values are set according to the level of the light / dark signal. The surface defect of the sheet-like material is characterized by judging the size of the concave and convex shapes and the size of the concave and convex according to the level of the brightness signal, and determining the size of the concave and convex defect from the width exceeding the threshold It relates to an inspection device.

  According to the present invention, even a concave-convex defect having a small curvature change on the surface of a transparent sheet can be detected with high sensitivity, and the defect can be detected without omission. A highly reliable defect inspection apparatus capable of determining the size in real time can be obtained. As a result, it is possible to detect the process abnormality at an early stage, prevent the loss expansion, and perform highly reliable quality control.

It is a schematic diagram which shows an example of the uneven | corrugated defect inspection apparatus of the transparent body sheet-like object surface concerning embodiment of this invention. It is a schematic diagram which shows an example of the screen shape which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the screen shape which concerns on embodiment of this invention. It is a schematic diagram which shows the imaging image of the uneven | corrugated defect by the incident angle of the light to the sheet-like object which concerns on embodiment of this invention.

  The defect inspection apparatus for a transparent sheet according to the present invention has a deflection angle by a mirror arranged in the irradiation direction of parallel light emitted from a light source in the inspection of uneven defects generated on the surface of a traveling transparent sheet. Illumination means having a mechanism for adjusting and reflecting the light, a curved screen for transmitting the parallel light obliquely with respect to the traveling direction of the sheet-like material, and forming an image of the transmitted light, An imaging means having a mechanism capable of adjusting the angle from the focal point of the curved surface of the screen so as to focus the light focused on the curved surface from any position in the dark field direction, and the screen by the imaging means. And signal processing means for detecting the light imaged as a light / dark signal.

  In the defect inspection apparatus for a transparent sheet according to the present invention, the signal processing means detects the detected light / dark signal level as a concavo-convex defect based on a threshold value, and determines the size and shape of the concavo-convex defect. It is characterized by.

  Here, the uneven defect is a defect in which the surface of the sheet-like material pressed against a foreign object is curved and recessed, and the opposite surface bulges in a convex shape. Both surfaces are concave or both surfaces are convex. Includes defects.

  Here, the parallel light means light composed of light components that are nearly parallel to the optical axis in the illumination direction without overlapping each light beam, and each light beam overlaps. It also includes light having a predetermined angle spread with respect to the optical axis in the illumination direction.

  Further, by projecting parallel light obliquely with respect to the traveling direction of the sheet-like material and projecting it onto the screen to form an image, the projection-and-depression defect has a light and darkness due to the refracting action equivalent to the lens. That is, the image of the part where the light is collected is bright, and the image of the part where the light is not incident by refraction is dark.

  Here, as the properties of the screen surface, a projected image is formed by selecting a rough surface on which light diffuses instead of a mirror surface on which light is regularly reflected.

  Here, the curved surface in the traveling direction of the screen has a curvature radius with the in-focus position of the imaging means as the diameter, so that the in-focus position is the rotation axis no matter where the projected image is formed on the curved surface of the screen. By adjusting the camera angle, the camera will always be in focus. In addition, the cross-section in the traveling direction of the screen is the same in the width direction of the sheet-like object, and the position of the curved surface of the screen on which the projection image is formed is the same in the width direction in the inspection area in the width direction of the sheet-like object. .

  Here, the imaging position of the projected image on the curved surface of the screen is determined by the incident angle of the parallel light adjusted by the mirror of the illumination means, and the angle of the imaging means is geometrically determined from the rotation angle of the mirror.

  Here, the image pickup means uses a one-dimensional image sensor camera or the like, continuously picks up images formed on the screen, and detects shadows caused by the irregular defects as light and dark electrical signals. By determining this light / dark electrical signal with a plurality of threshold values by the signal processing means, the size of the uneven defect can be detected by the shadow density, and the cross-sectional change magnitude of the uneven defect proportional to the shadow density can be detected. Can be estimated.

  According to the above configuration, the parallel light is transmitted obliquely with respect to the traveling direction of the sheet-like object by the mirror, the light imaged on the curved screen is imaged from the focal point by adjusting the angle, and the detected light / dark signal Can be inspected based on a plurality of threshold values to inspect the size of the concavo-convex defect and the size of the concavo-convex.

  The defect inspection apparatus for a transparent sheet according to the present invention is characterized in that the light reflected by the mirror of the illumination means is transmitted at an incident angle of 10 ° to 60 ° with respect to the traveling direction of the sheet. The present invention relates to a surface defect inspection apparatus for sheet-like materials.

  Here, the difference in brightness between the part of the uneven defect imaged on the screen and the part without the uneven defect is due to the change in curvature of the uneven defect, the incident angle of the parallel light illumination, the average thickness and refraction of the sheet-like object. In order to cause a difference in optical density between light and dark even with a slight uneven defect with a small change in curvature, it is advantageous to make the incident angle shallower than the sheet-like material. . By making the incident angle shallower, even a slight uneven defect can cause a difference in optical density between light and dark, and the inspection area of the sheet-like object can be widened. Therefore, it is preferable to set the inspection area of the sheet-like object by adjusting the incident angle within a range in which the difference in brightness between the uneven defect that needs to be detected and the texture can be distinguished.

  Therefore, it is preferable to determine the optimum angle of incidence according to the product such as the average thickness and refractive index of the sheet-like material and the change in curvature of the irregular defect. More preferably, uneven defects to be detected for each kind of sheet-like material are sampled in advance, an appropriate incident angle is investigated, registered in the signal processing means, and the incident angle is automatically set to an appropriate value for each kind. To adjust the angle of the mirror of the illumination means.

  Therefore, it is excellent in that it can be configured under optimum optical conditions for the type of sheet material and the uneven defect to be detected, and the highly sensitive uneven defect can be inspected.

  In the defect inspection apparatus for a transparent sheet-like material according to the present invention, the imaging means is interlocked with the deflection angle of the mirror of the illumination means changed to adjust the oblique incident angle with respect to the sheet-like material, The present invention relates to an apparatus for inspecting a surface defect of a sheet-like object, characterized by having a mechanism for adjusting an angle with an in-focus position as an axis so as to match an imaging position.

  Here, it is difficult for the one-dimensional image sensor camera of the image pickup unit to focus accurately while the target sheet-like object is moving, but it is a curved screen with the focus distance of the image pickup unit as the radius. Therefore, by adjusting the angle of the imaging means around the in-focus position, the projected image of the concavo-convex defect will be in focus regardless of the position on the screen, and highly sensitive defect inspection can be performed. Are better.

  Here, since the image formation position on the curved surface of the screen of the projected image is determined by the incident angle of the parallel light adjusted by the mirror of the illumination means, a one-dimensional image sensor camera that is the image pickup means in conjunction with the rotation angle of the mirror, etc. It is preferable to adjust the angle.

  A defect inspection apparatus for a transparent sheet according to the present invention uses a one-dimensional image sensor as an image pickup means, accumulates a light / dark signal for each scan while updating a certain number of lines by the signal processing means, and determines the level of the light / dark signal. A plurality of threshold values are set according to the level of the light / dark signal, and the concave / convex judgment and the size of the concave / convex shape are estimated based on the level of the light / dark signal. The present invention relates to a surface defect inspection apparatus for sheet-like materials.

  Here, the one-dimensional image sensor used for the imaging means is converted into a one-dimensional electric signal continuously according to the scan rate and output as a light / dark signal, and based on the line speed of the sheet-like material converted from the encoder, Two-dimensional image information can be obtained by integrating the light and dark signals in a time series by a signal processing device.

  Here, the fall width of the light / dark signal depends on the curvature change of the concavo-convex defect, and the concave defect has a dark area in the center of the projected image and a bright surrounding, and the convex defect has a darkness in the projected image. The brighter the central area, the darker the surroundings, and the greater the change in curvature, the darker the projected image of the concave defect and the brighter the projected image of the convex defect.

  According to the above configuration, by determining with a plurality of threshold values at the level of the light / dark signal, it is possible to determine the concave and convex shapes of the detected defect and estimate the size of the concave and convex portions. Judgment is possible as the size of the uneven defect by density.

  Below, the uneven | corrugated-shaped defect inspection apparatus of the transparent body sheet-like material surface concerning this invention is demonstrated based on FIG. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  FIG. 1 is a schematic diagram showing an example of a concavo-convex defect inspection apparatus on the surface of a transparent sheet according to an embodiment of the present invention.

  In FIG. 1, the illumination unit 1 that irradiates parallel light obliquely from the MD of the traveling transparent sheet 6, the traveling direction of the transparent sheet 6 is MD, the width direction is TD, An adjusting means (not shown) that adjusts the angle of the parallel light around the rotation axis A by the mirror 2, the screen 3 that forms an image of the light transmitted through the transparent sheet 6, and the image formed on the screen 3 are combined. In the case where the imaging means 4 for detecting as a light / dark signal at an appropriate angle from the focal distance r and the irregular sheet-like defect (not shown) in the transparent sheet-like object 6, the level of the light / dark signal is determined by a plurality of threshold values. And signal processing means 5 for detecting the irregularity defect and determining the shape and size of the irregularity defect.

  Further, the image pickup means 4 is controlled by a control means such as a stepping motor (not shown) around the rotation axis B of the image pickup means 4 in order to accurately pick up an image formed at any position on the screen 3 at the focal distance r. Adjust the angle. The rotation angle of the imaging means 4 is obtained by geometric calculation based on the control signal of the mirror 2 angle adjustment stepping motor or the like, or the rotation angle of the mirror 2 based on the detection signal by a rotary encoder (not shown). Can do. Further, it is preferable that an angle adjusting stepping motor or the like (not shown) is also installed in the image pickup means 4 to adjust the rotation angle of the image pickup means 4 in conjunction with the rotation angle of the mirror 2.

  Moreover, the traveling speed of the transparent sheet 6 can be converted from an encoder installed on a nearby roll (not shown).

  Here, the uneven defect is a defect in which the surface of the sheet-like material pressed against a foreign object is curved and recessed, and the opposite surface bulges in a convex shape. Both surfaces are concave or both surfaces are convex. Includes defects. The irregular defect is mainly a defect in which a surface on which a foreign object is pressed against a sheet-like material on a roll or a nip roll is curved and recessed, and the opposite surface bulges in a convex shape. If the sheet is pressed and dents are formed on both sides of the sheet or if there are dents on the roll side, the sheet may be a convex defect. Naturally, the direction, size, and height difference of the unevenness of the defect changes depending on the size and hardness of the foreign matter that comes into contact.

  Here, the parallel light refers to light composed of light components that are nearly parallel to the optical axis in the illumination direction without overlapping each light component of the light flux. In FIG. 1, the light source of the illumination means 1 is preferably a point light source such as a xenon light source, and can be a parallel light beam having a certain spread by a collimator lens or the like at the exit window of the point light source. Even if the light beam is enlarged away from the exit window, the light components do not overlap.

  In addition, in order to irradiate parallel light limited to the inspection area of the transparent sheet-like object 6, a mask (not shown) is placed between the illumination means 1 and the mirror, so that a slit-like parallel parallel to the TD. It is preferable in that it can be light and prevents erroneous detection due to light irregularly reflected by a peripheral roll or the like.

  Here, it is preferable that the mirror 2 used in the illumination unit 1 is an optical mirror having a reflectance of 85% or more from the viewpoint of suppressing the attenuation of the light amount.

  Further, it is preferable to arrange the rotation axis A on the reflection surface of the mirror 2 and to accurately control the rotation axis with, for example, a stepping motor of 0.36 ° / pulse. Naturally, the amount of change in the reflection angle with respect to the amount of change in the incident angle at the mirror 2 is doubled, and the rotation angle of the mirror 2 is such that the light transmitted through the transparent sheet 6 is within the range of the screen 3. It is preferable to limit.

  Further, the rotation axis A of the mirror 2 is arranged on a circular locus whose radius is the in-focus distance r about the rotation axis B of the imaging unit 4, so that the imaging unit 4 rotates from the rotation angle of the mirror 2. This is preferable in that it is easy to calculate the corner geometrically.

  Here, the screen 3 has a curved surface on the locus of a circle having a focus distance r centered on the rotation axis B of the image pickup means 4, so that an image can be taken at any position on the screen 3. It is preferable in that the focusing operation is not required every time the incident angle of the parallel light is changed only by adjusting the angle of the means 4.

  FIG. 2 is a schematic diagram illustrating an example of the shape of the screen 3.

  In FIG. 2, the screen 3 having a curved surface with the in-focus distance r as the radius of curvature has the same MD cross-section, so that slit-like light parallel to TD is TD even on the screen surface. Form images in parallel.

  Further, the processing accuracy of the curved surface of the screen 3 may be within the range of the depth of field determined by the light receiving lens used for the image pickup means 4 and the optical detection conditions, and preferably processed to about 1/10 of the depth of field. .

  Moreover, the diffusing surface of the screen 3 can be realized by selecting a material that diffusely reflects or by applying a white coating on a metal, and it is preferable that the surface has no color spots.

  FIG. 3 is a schematic diagram illustrating an example of the shape of the screen 3.

  In FIG. 3, the screen 3 is processed into a multi-step plane with the in-focus distance r as the radius of curvature, and the cross section of the MD has the same shape as that of the TD so that slit-like light parallel to the TD can be obtained on the screen surface. An image is formed parallel to TD. In this case, since the image formation position on the screen is stepwise, the angle of the mirror 2 of the illumination unit 1 is also adjusted stepwise, and the angle adjustment of the image pickup unit 4 is also stepwise, so the angle of the mirror 2 The angle of the imaging means 4 can be uniquely extracted from the database registered in advance without performing geometric calculation.

  Further, the processing accuracy of the surface of the screen 3 may be within the range of the depth of field determined by the light receiving lens used for the image pickup means 4 and the optical detection conditions, and preferably processed to about 1/10 of the depth of field. .

  Moreover, the diffusing surface of the screen 3 can be realized by selecting a material that diffusely reflects, or by applying a white paint or a diffusion sheet to a metal, and it is preferable that the surface has no color spots.

In FIG. 1, slit-like parallel light specularly reflected at a position where the mirror 2 of the illuminating means 1 is horizontal passes through the incident position P _B at an incident angle θ _B with respect to the transparent sheet-like object 6 and is imaged means. When the image forming position P _B ′ on the horizontal tangent line of the screen 3 as viewed from the vertical direction 4 is used as a reference and the incident angle θ _L of the parallel light is shallow, the mirror 2 is adjusted from the reference position to the rotation angle α to be incident. The light transmitted through the position P _L is imaged on the screen 3 at P _L ′, and the imaging means 4 is adjusted to an angle of θ _L ′ from the reference position and deepens to the incident angle θ _U of the parallel light. Is adjusted from the reference position to the rotation angle β, the light transmitted through the incident position P _U is imaged on P _U ′ on the screen 3, and the imaging means 4 is adjusted to an angle θ _U ′ from the reference position.

  FIG. 4 is a schematic diagram illustrating an example of an imaging image of a concavo-convex defect depending on an incident angle of light on a sheet-like object according to an embodiment of the present invention.

In FIG. 4, R is an image diagram in the case where one side is convex, one side is concave, and a lens-like concave / convex defect is projected from the vertical direction with parallel light and imaged at the same magnification, and the average density of the dark portion of the projected image Is assumed to be D _0, and assuming a circular defect in which the horizontal and vertical diameters are a ₀ = b ₀ , an image of a projected image is obtained when the incidence of parallel light on the sheet is changed from a deep angle to a shallow angle. showed that. In contrast to the projected image B at the reference incident angle θ _B in FIG. 1, the projected image A with a deep incident angle θ _U has a darker density and a larger image, and the projected image C with a deep incident angle θ ₁ has a dark portion. The image is dense and small. The density of the projected image is D ₀ <D ₁ <D ₂ <D ₃ , the maximum diameter of MD is b ₁ > b ₂ > b ₃ ≧ b ₀ , and the maximum diameter of TD is a ₁ > a ₂ > a _3. > A ₀ , the aspect ratio is b ₀ / a ₀ = 1, and 1 ≧ b ₁ / a ₁ > b ₂ / a ₂ > b ₃ / a ₃ .

  Here, it is preferable to adjust the incident angle of the light to the transparent sheet 6 so that the brightness of the projection image of the concavo-convex defect becomes the clearest on the screen. Although the density of the image increases and minor irregularities can be detected, the formation noise of the sheet-like material is also emphasized, and there is a risk of false detection. Although the density becomes small and minor uneven defects are difficult to detect, the risk of false detection can be reduced because the formation noise of the sheet is reduced.

  Here, it is preferable that the condition of the incident angle is determined as an optimum angle according to the type such as the average thickness and refractive index of the sheet-like material and the change in curvature of the irregular defect. In addition, the irregularities to be detected for each kind of sheet-like material are sampled in advance, the appropriate incident angle is investigated, registered in the signal processing means 5, and the incident angle is automatically set to an appropriate value for each kind. It is more preferable to adjust the angle of the mirror 2 of the illuminating means 1, and as a result of intensive studies by the inventors, it has been confirmed that the incident angle is in the range of 10 ° to 60 °.

  In FIG. 1, a one-dimensional light / dark signal detected by the image pickup means 4 is accumulated in the signal processing means 5 and synthesized in time series to obtain a two-dimensional image such as a defect, and the shape can be determined.

  In addition, a one-dimensional image sensor is used as the image pickup means 4 and the light / dark signal for each scan is accumulated while the number of lines is updated by the signal processing means 5, and the number of lines exceeding the threshold is determined as the size of the MD defect. TD is extracted as the size of the TD defect from the falling width of the light / dark signal of each line, combined with the data of the MD size, and two-dimensionalized to determine the size, area, and shape of the defect. preferable.

  Here, the one-dimensional image sensor of the image pickup means 4 outputs a one-dimensional light / dark signal continuously according to the scan rate, and signals the one-dimensional light / dark signal based on the line speed of the sheet-like material converted from the encoder or the like. Two-dimensional image information is obtained by integrating the processing means 5 in time series. The signal processing means 5 can convert the distance per scan as the MD minimum unit from the line speed and scan rate converted from the encoder, etc., and convert it as the MD length of the concavo-convex defect by multiplying it with the number of detected lines.

  Here, the defect image has a different aspect ratio depending on the incident angle, but it is a systematic error, so that it can be corrected based on the set incident angle.

  Here, the light / dark signal level of the image of the defect changes depending on the incident angle, but since it is a systematic change, comparison and verification can be performed after correction based on the set incident angle, and linked to the incident angle. By changing the threshold level of light and dark, it is possible to determine NG or OK depending on the curvature change of the concavo-convex defect.

  Here, the fall width of the light / dark signal depends on the curvature change of the concavo-convex defect, and the concave defect has a dark area in the center of the projected image and a bright surrounding, and the convex defect has a darkness in the projected image. The brighter the central area, the darker the surroundings, and the greater the change in curvature, the darker the projected image of the concave defect and the brighter the projected image of the convex defect.

  According to the above configuration, by determining with a plurality of threshold values at the level of the light / dark signal, it is possible to determine the concave and convex shapes of the detected defect and estimate the size of the concave and convex portions. Judgment is possible as the size of the uneven defect by density.

DESCRIPTION OF SYMBOLS 1 Illumination means 2 Mirror 3 Screen 4 Imaging means 5 Signal processing means 6 Transparent sheet-like material MD Running direction of transparent sheet-like material TD Width direction of transparent sheet-like material A Mirror rotation axis B Rotation axis of imaging means θ mirror of the reference incident angle theta _U incidence angle α incident angle below the reference angle of incidence on the film above the incident angle theta _L parallel light from the reference angle of incidence to the parallel light from the film theta _L to films _B parallel light Rotation angle β Mirror rotation angle of incident angle θ _U P Incident position of _B parallel light optical axis on film Incident position P _U parallel light optical axis above film incident position P _L Parallel light optical axis of film imaging position on the screen of the image forming position P _L 'incident angle theta _L on the screen of the incident angle theta _U' imaging position P _U on the screen of the incident angle theta _B 'incidence position P _B of the lower than the incident position of r Focusing distance of imaging means rotation angle of the image pickup means corresponding to theta _U rotation angle of the image pickup means corresponding to _{'P U' θ L 'P} L'

Claims (5)

In the inspection of the uneven defect generated on the surface of the traveling transparent sheet, the illumination means having a mechanism for reflecting by a mirror arranged in the irradiation direction of the parallel light emitted from the light source;
A curved screen for transmitting the parallel light obliquely with respect to the traveling direction of the sheet and imaging the transmitted light; and
Imaging means having a mechanism capable of adjusting the angle from the focal point on the curvature radius of the curved surface of the screen so as to focus the light imaged on the curved surface of the screen;
Signal processing means for detecting light imaged on the screen by the imaging means as a light and dark signal;
An apparatus for inspecting a surface defect of a sheet-like material, comprising: 2. The surface of a sheet-like object according to claim 1, wherein the signal processing means detects the level of the detected light / dark signal as a concavo-convex defect by a threshold value, and determines the size and shape of the concavo-convex defect. Defect inspection equipment. The surface defect of the sheet-like material according to claim 1 or 2, wherein the light reflected by the mirror of the illumination means is transmitted at an incident angle of 10 ° to 60 ° with respect to the traveling direction of the sheet-like material. Inspection device. 4. The imaging device according to claim 1, further comprising a mechanism that adjusts the angle about the focusing position as an axis so as to match the imaging position of the curved screen in conjunction with the deflection angle of the mirror of the illumination means. The surface defect inspection apparatus of the sheet-like object of any one of Claims 1. A one-dimensional image sensor is used as the imaging means, and a light / dark signal for each scan is accumulated while updating a certain number of lines by the signal processing means, and a plurality of threshold values are set according to the level of the light / dark signal. 5. The concave / convex determination or the size of the unevenness is estimated based on the level, and the size of the uneven defect is determined from a width exceeding a threshold value. Sheet surface defect inspection equipment.