JP2004184397A - Method for inspecting defect in shape of band-like body and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inspecting defect in shape of a band-like body and apparatus therefor, which can inspect both of the defect in shape having a size larger than the thickness of the band of light and the defect in shape having a size about the thickness of the band of light, by the apparatus at a low-cost. <P>SOLUTION: A light band LB is formed on the surface of the band-like body, by irradiating the surface of the band-like body with a band-like light IL traversing the band-like body 1. A reflection image RI of the light band LB reflected on the surface of the band-like body is projected on a screen 15. The reflection image RI on the screen 15 is imaged by a 2-dimensional imaging device 20, in which the defect in shape having the size larger than the thickness of the band of light is detected, according to the curvature of the light band LB, and in which the defect in shape having the size about the thickness of the band of light is detected, according to the local contrast of the light band LB. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a shape defect of a band, which is made of metal, plastic or other material and optically detects a shape defect of the band moving relatively to an inspection device, and an apparatus therefor.
[0002]
[Prior art]
In a strip such as a steel plate, a shape defect that may impair product quality needs to be discovered early in the manufacturing stage, and manufacturing conditions must be changed to prevent the occurrence of a shape defect in a subsequent product. For this reason, a shape defect is inspected while moving the belt-like body in the production line. The shape defect includes a shape defect over a relatively wide range (hereinafter referred to as a wide-area shape defect), and a small shape defect such as a concave portion or a convex portion having a diameter of about 10 mm or less caused by a foreign substance attached to a roll in a production line. (Hereinafter referred to as a locally defective shape). Various inspection methods such as electromagnetic and optical methods have been developed as inspection methods for shape defects. Among them, the optical inspection method is widely used because a shape defect can be detected and detected in a non-contact manner.
[0003]
As one of them, the light is projected on the band from just above the band through the slit to form a linear band of light, and the real image is taken with a video camera from an oblique direction and the band is distorted from the straight line. There is a light section method for observing the shape. As another method, there is a method of irradiating the surface of the band-like body with a rod-like light source, photographing a virtual image of the rod-like light source with a video camera, and detecting a distortion of an image caused by a defective shape from a video signal. These methods can detect a wide area shape defect, but it is difficult to detect a local shape defect.
[0004]
As a method for solving the above-mentioned disadvantage, there is a method of scanning the belt-like body surface in the width direction with a laser beam and receiving a reflected beam with a light receiving element to detect a shape defect (for example, see Patent Document 1). In this method, a large number of light receiving elements are arranged in the lateral direction over the entire width of the band, or the reflected beam is condensed toward the center of the width of the band with a columnar lens, and the large number of light receiving elements are applied to the surface of the band. It is necessary to arrange in the line direction (vertical direction). However, the arrangement of a large number of light receiving elements causes a failure, and it is very difficult to keep the sensitivity uniform, and the signal processing circuit becomes complicated. Further, a scanning device having a high-precision scanning mirror for condensing the reflected beam in the width direction is required. Since the inspection width per scanning mirror is limited, a plurality of scanning mirrors must be arranged, which makes the inspection apparatus very expensive.
[0005]
[Patent Document 1]
JP-A-61-254809 (second page, upper right column, third paragraph-same page, lower left column, first paragraph, and FIG. 1)
[0006]
[Problems to be solved by the invention]
It is an object of the present invention to provide a method and an apparatus for inspecting a shape defect of a strip which can detect both a wide-area shape defect and a local shape defect with a low-cost device.
[0007]
[Means for Solving the Problems]
The first method for inspecting a shape defect of a band according to the present invention is a method for illuminating the surface of a moving band and inspecting the shape defect of the band based on a change in an illumination image due to the shape of the band. Irradiating a band-like light traversing the band-like body to form a light band on the band-like body surface, projecting a reflection image of the light band reflected on the band-like body surface onto a screen, and capturing the reflection image on the screen with a two-dimensional imaging device. I do. A shape defect larger than the thickness of the light band due to the bending of the light band is detected, and a shape defect having a size approximately equal to the thickness of the light band is detected based on the local density of the light band.
[0008]
The second method for inspecting a defective shape of a band according to the present invention is a method for illuminating a surface of a moving band and inspecting a defective shape of the band based on a change in an illumination image due to the shape of the band. A plurality of stripes of light parallel to the body surface were simultaneously irradiated at regular intervals in the direction of movement of the stripes to form a stripe pattern consisting of stripes of a plurality of light bands on the stripes, and the light was reflected by the stripes. The reflection image of the stripe pattern is projected on a screen, and the reflection image of the stripe pattern projected on the screen is captured by a two-dimensional imaging device. A shape defect larger than the thickness of the light band is detected from a change in the phase of the striped pattern, and a shape defect having a size about the thickness of the light band is detected from the local shading.
[0009]
In the second method for inspecting a shape defect of a strip, the spatial intensity distribution of the strip light may be a sine wave or a sine wave to which a bias is applied.
[0010]
A third method for inspecting a shape defect of a band according to the present invention is a method for illuminating a surface of a moving band and inspecting a shape defect of the band based on a change in an illumination image due to the shape of the band. The band-shaped light is irradiated onto the band-shaped body surface while applying a certain period of intensity modulation to form a flickering light band on the band-shaped body surface, and a reflection image of the light band reflected on the band-shaped body surface is projected on a screen to modulate the band-shaped light. The reflected image is captured by a time-delay integration type imaging device having a shift cycle proportional to the cycle. A shape defect larger than the thickness of the light band is detected from the change in the phase of the stripe of the image on the obtained stripe pattern, and a shape defect having a size approximately equal to the thickness of the light band is detected from the local shading.
[0011]
In the third method for inspecting a shape defect of a band, the intensity modulation waveform of the band light may be a sine wave or a sine wave to which a bias is applied. Alternatively, the band-like light irradiation intensity may be increased in a cycle of one time within the screen of the time delay integration type imaging apparatus.
[0012]
A first inspection apparatus for deflecting the shape of a strip according to the present invention illuminates a surface of a moving strip and inspects a defect in the shape of the strip based on a change in an illumination image. A band-shaped light irradiating device for irradiating band-shaped light to form a light band on a band-shaped body surface, a screen for projecting a reflection image of the light band reflected on the band-shaped body surface, and a two-dimensional imaging device for capturing a reflected image on the screen It consists of A shape defect larger than the thickness of the light band due to the bending of the light band is detected, and a shape defect having a size approximately equal to the thickness of the light band is detected based on the local density of the light band.
[0013]
A second inspection apparatus for deflecting the shape of a band according to the present invention illuminates the surface of a moving band and inspects the shape of the band based on a change in an illumination image. A strip light irradiating device for simultaneously irradiating a strip of light at a certain interval in the direction of movement of the strip to form a stripe pattern composed of a plurality of light band stripes on the strip surface, and a stripe reflected by the strip surface The screen includes a screen for projecting a reflection image of a pattern, and a two-dimensional imaging device for imaging a reflection image of a stripe pattern projected on the screen. A shape defect larger than the thickness of the light band is detected from a change in the phase of the striped pattern, and a shape defect having a size about the thickness of the light band is detected from the local shading.
[0014]
In the second apparatus for inspecting a shape defect of a strip, the spatial intensity distribution of the strip light may be a sine wave or a sine wave to which a bias is applied.
[0015]
The third band shape defect inspection apparatus of the present invention illuminates the surface of a moving band and inspects the band for a shape defect based on a change in an illumination image. A belt-shaped light irradiating device that irradiates the light while applying a constant period of intensity modulation to the screen, a screen that projects a reflection image of the light band reflected by the band-shaped body surface, and captures the reflection image with a shift period proportional to the modulation period of the band light And a time delay integration type imaging device. A shape defect larger than the thickness of the light band is detected from a change in the phase of the stripe in the obtained striped image, and a local shape defect is detected from the local shading.
[0016]
In the third apparatus for inspecting a shape defect of a band, the intensity modulation waveform of the band light may be a sine wave or a sine wave to which a bias is applied. Alternatively, the band-like light irradiation intensity may be increased in a cycle of one time within the screen of the time delay integration type imaging apparatus.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows one embodiment of the present invention, and is a schematic configuration diagram of an apparatus for inspecting a shape defect of a belt-like body. Here, a case where the strip is a steel plate will be described as an example. The width of the steel plate is 1200 mm, and the moving speed is 240 m / min.
[0018]
The shape defect inspection device mainly includes a belt-shaped laser beam irradiation device 10, a screen 15, a two-dimensional imaging device 20, and an image processing device 30.
[0019]
The belt-shaped laser beam irradiation device 10 irradiates the surface of the steel plate 1 with one belt-shaped laser beam IL to form a laser beam band LB on the steel plate surface. The belt-shaped laser light IL is applied over the entire width of the steel plate 1. The incident angle of the belt-shaped laser beam IL with respect to the steel plate surface is determined in advance by an experiment so that a reflected image can be obtained on the screen. As the belt-shaped laser beam irradiation device 10, a commercially available device is used. The thickness of the laser light band LB corresponding to the irradiation length in the L direction in FIG. 1 is determined according to the surface properties of the target.
[0020]
The screen 15 is located at a position facing the belt-shaped laser beam irradiation device 10 and projects a reflection image RI of the laser beam band LB regularly reflected from the steel plate surface. The screen 15 has a width such that an image corresponding to the entire width of the steel plate can be projected according to the spread angle β of the belt-shaped laser beam IL and the projection distance to the screen, and the vertical width has a reflected image RI changed according to the shape of the steel plate 1. The width is enough to fit.
[0021]
The two-dimensional imaging device 20 includes a video camera 22 provided with a CCD area sensor or a C / MOS area sensor. A plurality of the two-dimensional imaging devices are arranged along the board width direction C at a position facing the screen 15. The number of video cameras 22 is determined according to the inspection width and the resolution. When the inspection width is narrow, the number of video cameras 22 may be one. The video camera 22 captures a reflection image RI of the laser light band LB projected on the screen 15.
[0022]
In the case where the width of the image RI projected on the screen 15 is too wide in one belt-shaped laser beam irradiation device 10 with a wide inspection width, a plurality of belt-shaped By providing the laser light irradiation device 10 along the plate width direction C, it is possible to reduce the spread angle β of the belt-like light per unit.
[0023]
The image processing device 35 includes a computer including an input / output interface, an image memory, and the like, and a display (both are not shown). The image processing device 35 performs density correction, noise removal, image generation, and the like on the input image from the video camera 22. The display displays an image of the shape of the steel plate and data such as the type, position, and size of the shape. The moving amount of the steel sheet 1 is measured by a pulse signal transmitted from a pulse generator (both not shown) provided in the steel sheet conveying device. The position of the defective shape portion in the plate length direction L is obtained from the movement amount.
[0024]
The steel sheet 1 is unwound from a rewind reel and wound at a constant speed on a take-up reel (both not shown).
[0025]
In the apparatus configured as described above, the belt-like laser light IL emitted from the belt-like laser light irradiation device 10 is reflected on the steel plate surface, and the reflection image RI of the laser light band is projected on the screen 15. The reflection angle of the belt-shaped laser light IL changes on the inclined surface of the defective shape portion according to the inclination angle, and the position of the incident point of the reflected light RL on the screen 15 moves up and down by the principle of the optical lever.
[0026]
Shape defects larger than the thickness of the light band are detected by bending the reflected image of the laser light band. For example, as shown in FIG. 1, a reflection image RI having a shape curved along the plate width direction is projected on the screen 15. With the portion of the laser light band LB having the maximum light intensity distribution in the L direction as the center of the laser light band LB, noise due to minute fluctuation of the reflected image is removed, and the amount of bending from the reference line is obtained. A shape defect having a size approximately equal to the thickness of the light band is detected by a local light amount distribution of the reflected image RI of the laser light band LB. Since the reflected image of the defective shape portion is enlarged by the principle of optical leverage, it is possible to detect even a shape defect having a size as small as a minute light band. Therefore, it is possible to detect both a shape defect that is larger than the thickness of the light band and a shape defect that is about the same size as the light band.
[0027]
FIGS. 2A and 2C show cross sections passing through a point in the plate width direction of the steel plate 1 and along the plate length direction L. FIG. The point shows the state reflected on the steel plate surface. FIGS. 2B and 2D show the change in the incident position of the reflected light RL on the screen 15 along the plate width direction C. When the belt-shaped laser light IL is reflected by the flat portion of the steel plate 1, the belt-shaped laser light IR becomes a straight band extending in the plate width direction C as shown in FIG. In the case of a shape defect WD larger than the thickness of the light band, the band-shaped laser beam IL reflected on the surface inclined so as to fall forward as shown in FIG. Is reflected to the lower position. Conversely, as shown in FIG. 2 (c2), the belt-shaped laser light IL reflected on the surface that is inclined so as to rise forward is reflected on the screen 15 to a position above the straight belt. As a result, the shape defect WD larger than the thickness of the light band changes from a lower arc along the plate width direction C to an upper arc as shown in FIG. 2D.
[0028]
In the case of a local shape defect only in the width (thickness of the light band) in the moving direction of the belt-shaped laser light IL on the steel plate, the size is about the same as the thickness of the concave light band as shown in FIG. As shown in FIG. 3 (b), the defectively shaped CD has a shape in which a part of the band is narrowed. The convex local shape defect VD as shown in FIG. 3C has a shape in which a part of the band is swollen as shown in FIG. 3D. In the case where the thickness of the light band is extremely large with respect to the shape defect, the light amount at the center increases in the concave shape, the light amount at the peripheral portion decreases, and the light amount at the outside remains unchanged. In the convex shape, the light amount at the center decreases, the light amount in the vertical direction increases, and the light amount outside the light amount remains unchanged.
[0029]
Due to the change in the reflection image as described above, the defective shape is imaged as a grayscale image or a bird's-eye view of the belt-like body surface, or as a cross-sectional shape along the width direction of the belt-like body or a cross-sectional shape along the length direction at a certain position in the width direction. The information is displayed on the display of the processing device 35.
[0030]
FIG. 4 shows another embodiment of the present invention, and is a schematic configuration diagram of a steel plate shape defect inspection apparatus. Hereinafter, the same reference numerals are given to the same devices as those in FIG. 1, and the detailed description thereof will be omitted.
[0031]
The shape defect inspection device mainly includes a belt-shaped laser beam irradiation device 10, a screen 15, a two-dimensional imaging device 20, and an image processing device 35.
[0032]
The belt-shaped laser beam irradiation device 10 simultaneously irradiates a plurality of mutually parallel belt-shaped laser beams IL on the steel plate surface at a constant interval in the moving direction (length direction) L of the steel plate 1. In order to simultaneously irradiate a plurality of belt-like laser beams IL, one belt-like laser beam IL irradiated from the belt-like laser beam irradiator 10 is branched at the output unit 12, or the plurality of belt-like laser beam irradiators 10 are used. It is used by being arranged in the L direction. By one irradiation, a stripe pattern SP composed of a plurality of parallel stripes S of the laser beam band is formed on the flat steel plate surface. In order to inspect the steel plate surface without gaps, the imaging cycle of the video camera 22 is set shorter than the time required for the steel plate to move by the length of SP. In addition, since the steel plate is moving, in order to obtain a blur-free image, a method of shortening the exposure time of the video camera 22 sufficiently using an electronic shutter or the like, or using a method of causing the belt-shaped laser light IL to emit a pulse is used. .
[0033]
The thickness of one laser light band (the thickness of the stripe S) is determined according to the surface properties of the target. One stripe pattern SP is composed of about 10 to 300 stripes S, the stripe interval is about twice the thickness of the stripes, and the thickness of the bright part and the dark part is substantially equal. As the spatial intensity distribution (light intensity distribution in the plate length direction) in the direction orthogonal to the stripes of the band laser light IL, a rectangular wave RS shown in FIG. 5A or a sine wave SS shown in FIG. Can be These waveforms can be generated by the beam shape control of the belt-shaped laser beam irradiation device 10 or an optical filter provided in the output unit 12. As shown in FIG. 5B, it is desirable to apply a bias b to the belt-shaped laser light IL. By the bias b, even when there is a small shape defect in the dark part of the stripe, it can be detected as a change in the light amount in the dark part.
[0034]
The two-dimensional imaging device 20 and the screen 15 are the same as those shown in FIG.
[0035]
As shown in FIG. 6, the image processing device 35 includes an image input unit 36 that temporarily stores an image input from the two-dimensional imaging device 20, performs density correction, removes noise, and the like.
[0036]
The fringe phase and fringe brightness calculation unit 37 following the image input unit 36 calculates the fringe phase and the fringe brightness based on the input image from the image input unit 36. A shape defect larger than the thickness of the light band is detected from the phase shift of the stripe SS as shown in FIG. A shape defect whose size is about the thickness of the light band is detected by an average change in the amount of light over one cycle of the stripe. The fringe phase signal is input to the slope calculator 38, and the fringe light / dark signal is input to the fringe light / dark detector 40, respectively.
[0037]
The inclination calculator 38 measures the phase shift d of the fringe, and obtains the inclination θ of the defective shape portion. The fringe phase shift d is a shift in the fringe position changed due to a shape defect larger than the thickness of the light band, and the peak position of the light intensity of the fringe observed from the light intensity peak position of the fringe that should be in a flat case is shifted. Calculate by quantity. The band-shaped laser light IL reflected by the shape defect portion larger than the thickness of the light band moves up and down on the screen 15 according to the direction and angle of inclination of the shape defect portion. The relationship between the fringe phase shift amount d and the inclination θ is given by d = Atan2θ as shown in FIG. Here, A is the horizontal distance from the incident point of the belt-shaped laser light IL to the steel plate surface to the screen 15. The inclination θ is determined by θ = １ ／ tan ⁻¹ (d / A). Is positive in the clockwise direction from the horizontal plane. Further, the movement amount of the steel plate is input from the steel plate movement amount measuring device 25 including the pulse generator to the shape defect inclination calculating unit 38 which is larger than the thickness of the light band. The position of the defective shape portion in the plate length direction is obtained from the moving amount.
[0038]
The inclination θ obtained by the inclination calculation unit 38 is input to the shape restoration unit 39. The shape restoring unit 39 obtains the height h of the defective shape portion from the flat surface of the steel plate 1 by h = Xtan θ based on the stripe interval X and the inclination θ when the steel plate is flat. As a result, as shown in FIG. 7, a defective shape larger than the thickness of the light band is restored along the plate length direction.
[0039]
The fringe light / dark detector 40 detects an abnormal part VD from the fringe light / dark signal obtained by averaging the input image over one cycle of the fringe based on the fringe phase and the fringe light / dark signal from the fringe light / dark calculator 37 as shown in FIG. Then, the convex shape and the concave shape are determined from the abnormal portion pattern. That is, as shown in FIG. 10, a pattern in which the light intensity at the central portion in the abnormal portion pattern is lower than that in the peripheral portion represents the convex shape VD, and a pattern with a higher light intensity in the central portion represents the concave shape CD.
[0040]
The signals from the shape restoring unit 39 and the fringe light / dark detecting unit 40 are input to a shape defect judging unit 41, where the pass / fail of the shape defect is judged based on a preset pass / fail judgment criterion.
[0041]
The inspection result display unit 42 displays the image output from the shape defect determination unit 41 and data such as the type, size, position, and pass / fail result of the flaw.
[0042]
In the above-described embodiment, the stripe pattern SP including the stripes S of the plurality of laser light bands is simultaneously formed on the steel plate surface by the belt-shaped laser light irradiation device 10 that irradiates the plurality of belt-shaped laser lights IL. In the embodiment described below, a stripe-shaped image is obtained by irradiating a single strip laser beam while applying intensity modulation to a steel plate.
[0043]
In this embodiment, the configuration of the inspection apparatus is the same as that of the apparatus shown in FIG. 1, but the belt-shaped laser light irradiation device irradiates a band-shaped laser light IL whose intensity is modulated at a constant period. As the video camera, a TDI video camera provided with a TDI (time delay integration) area sensor is used instead of the CCD area sensor or the C / MOS area sensor. The TDI area sensor is composed of a plurality of one-dimensional pixel rows in which light receiving units are arranged in parallel, and has a time delay integration function of transferring and accumulating an image signal from one pixel row to an adjacent next pixel row at a constant period. FIG. 11 schematically shows a part of the TDI area sensor 50, in which pixels are arranged in a matrix of, for example, 1024 rows × 96 columns. The TDI video camera is arranged such that the row direction R in which the pixel columns 52 are arranged side by side and the plate length direction (moving direction) of the steel plate match. The TDI area sensor shifts the accumulated charges in the row direction R by applying a shift pulse from outside. In other words, when the laser image is received at point P and charge is accumulated, and then the laser is turned off and a shift pulse is applied, the stripes move in the R direction as shown in FIG. By setting the period of the shift pulse and the laser modulation period to a proportional value, a striped image can be obtained continuously. For example, if the laser modulation cycle is set to be eight times the cycle of the shift pulse, a striped pattern image in which one pixel has one cycle of stripes can be obtained.
[0044]
In this embodiment, when there is disturbance light in the surroundings, even if an optical band-pass filter or the like that transmits only near the wavelength of the laser is attached to the video camera 22 so that the TDI area sensor receives only the laser light. good.
[0045]
In the apparatus configured as described above, one strip-shaped laser beam applied to the steel plate surface moving at a constant speed at a constant period is imaged by a TDI video camera. As a result, a stripe pattern composed of stripes of the laser light band at a certain interval is imaged. The stripe width, the stripe interval, the method of detecting a shape defect, and the like are the same as those of the inspection apparatus shown in FIG. When a TDI video camera is used, the same stripe image can be obtained regardless of the position of the laser light band image in the R direction of the TDI area sensor shown in FIG. 11, so that the absolute position of the stripe cannot be identified. Therefore, in a cycle of one time in the screen of the TDI video camera, that is, when the number of pixel rows in the R direction of the TDI area sensor is 96, the light intensity for irradiating the belt-like laser light once every 96 shift pulses is changed. The intensity is increased so that the output from the TDI area sensor becomes high so that the absolute position of the stripe can be identified.
[0046]
In the present invention, the shape defect is detected as either the bending of the light band or the light / dark of the light band. However, if the surface reflection characteristic of the inspection object is a stable mirror surface, the light band is widened and the shape defect is detected. May be detected only by light and dark. By doing so, the detection processing of only light and dark is sufficient, so that the configuration of the image processing apparatus is simplified. On the other hand, when there is a pattern or dirt on the surface and the reflection characteristics change, it is difficult to distinguish whether the brightness of the light band is caused by a defective shape or a change in the reflection characteristics. It is preferable to reduce the thickness of the band and detect a shape defect only by bending the optical band.
[0047]
The present invention is not limited to the above embodiment. For example, the band may be a metal band other than steel such as copper or aluminum, or a plastic band. The light source may be a directional light source instead of the laser light. As the directional light source, for example, a combination of a white light source, a band-shaped optical fiber bundle and a rod lens, or a combination of a straight tube fluorescent lamp, a slit and a columnar lens is used. The light source is not limited to visible light, but may be light having a wavelength from ultraviolet to far-infrared, and a wavelength that is specularly reflected with respect to the roughness of the strip may be selected. In this case, a camera element is selected that matches the wavelength. Further, the stripe pattern of the light band may be formed by a rectangular wave instead of the sine wave. In the case of a rectangular wave, a waveform close to a sine wave can be obtained by filtering, or a fringe phase may be identified using a means such as binarization.
[0048]
【The invention's effect】
In the present invention, a belt-like body surface is irradiated with band-like light traversing the belt-like body to form a light band on the belt-like body surface, a reflection image of the light band is projected on a screen, and a reflection image on the screen is captured by a two-dimensional imaging device. I do. A shape defect larger than the thickness of the light band due to the bending of the light band is detected, and a shape defect having a size approximately equal to the thickness of the light band is detected based on the local density of the light band. Therefore, it is possible to detect both a shape defect that is larger than the thickness of the light band and a shape defect that is about the same size as the light band. In addition, since a shape defect is detected using the principle of the optical lever, a small shape defect can be detected. Furthermore, the entire width of the band can be inspected at one time, and scanning time in the width direction of the band is not required, so that a shape defect can be inspected at high speed.
[0049]
In the shape defect inspection device of the present invention, since there is no movable portion, the mechanism of the inspection device is simplified, and a large number of light receiving elements are not required. As a result, the inspection apparatus is inexpensive and the maintenance of the apparatus is simplified.
[Brief description of the drawings]
FIG. 1 shows one embodiment of the present invention, and is a schematic configuration diagram of a shape defect inspection apparatus for a band-shaped body.
FIG. 2 is a schematic diagram illustrating a reflection state of a band-shaped light at a shape defect portion that is larger than the thickness of a light band.
FIG. 3 is a schematic diagram illustrating a reflection state of a band-shaped light at a defective shape portion having a size approximately equal to the thickness of a light band.
FIG. 4 shows another embodiment of the present invention, and is a schematic configuration diagram of a device for inspecting a shape defect of a strip.
FIG. 5 is a diagram schematically showing light intensities of a plurality of laser light bands in the device shown in FIG. 4;
6 is a block diagram of an image processing device of the device shown in FIG.
FIG. 7 is an explanatory diagram of a method of restoring a shape defect using the image processing apparatus.
FIG. 8 is a diagram for explaining the relationship between the inclination θ of the defective shape portion and the position of the reflection image.
FIG. 9 is a diagram illustrating a method for detecting a shape defect having a size approximately equal to the thickness of a light band.
FIG. 10 is a schematic diagram showing a light amount distribution of a convex portion and a concave portion having a shape defect whose size is about the thickness of a light band.
FIG. 11 is a schematic diagram of an area sensor of a TDI video camera.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel plate (belt) 10 Belt laser irradiation device 15 Screen 20 Two-dimensional imaging device 30, 35 Image processing device 50 Area sensor IL of TDI camera IL Band laser light LB Laser light band RI Reflection image CD Poor concave shape VD Poor convex shape SP Stripe S Stripe

Claims (12)

In a method of illuminating the surface of a moving band and inspecting the shape of the band based on a change in an illumination image due to the shape of the band, the surface of the band is irradiated with band light crossing the band and light is irradiated on the surface of the band. A band is formed, a reflection image of the light band reflected by the band-shaped body surface is projected on a screen, the reflection image on the screen is imaged by a two-dimensional imaging device, and a shape defect larger than the width of the light band due to bending of the light band. And detecting a shape defect having a size approximately equal to the thickness of the light band at a local density of the light band. In a method of illuminating the surface of a moving band and inspecting the shape of the band based on a change in an illumination image due to the shape of the band, a plurality of band lights parallel to each other on the surface of the band are moved. At the same time, irradiate at a certain interval in the direction to form a stripe pattern consisting of a plurality of stripes of light bands on the belt-like body surface, project a reflection image of the stripe pattern reflected on the belt-like body surface onto a screen, and project it on the screen The reflected image of the striped pattern is captured by a two-dimensional imaging device, and a shape defect larger than the thickness of the light band is detected based on a change in the phase of the striped pattern. A method for inspecting a shape defect of a belt-like body, comprising detecting a defect. 3. The method according to claim 2, wherein the spatial intensity distribution of the band light is a sine wave or a biased sine wave. In a method of illuminating the surface of a moving band and inspecting the shape of the band based on a change in an illumination image due to the shape of the band, one band of light is irradiated on the surface of the band while applying intensity modulation at a fixed period. Forming a flickering light band on the band-shaped body surface, projecting a reflection image of the light band reflected on the band-shaped body surface onto a screen, and performing the reflection with a time delay integration type imaging device having a shift period proportional to the modulation period of the band light. An image is captured, and a shape defect larger than the width of the light band is detected from a change in the phase of the stripe of the obtained striped image, and a shape defect having a size approximately equal to the thickness of the light band is detected from the local shading. A method for inspecting a shape defect of a band-shaped body. 5. The method according to claim 4, wherein the intensity-modulated waveform of the band light is a sine wave or a biased sine wave. 6. The method for inspecting a defective shape of a belt-like body according to claim 4, wherein the intensity of the belt-like light irradiation is increased in a cycle of one time within the screen of the time delay integration type imaging apparatus. In a device that illuminates the surface of a moving band and inspects the shape of the band based on a change in an illuminated image, a band is formed by irradiating the band with surface light that crosses the band and forming a light band on the surface of the band. A light irradiating device, a screen for projecting a reflection image of the light band reflected on the band-shaped body surface, and a two-dimensional imaging device for imaging the reflection image on the screen, wherein the light band is bent and is larger than the thickness of the light band. An apparatus for inspecting a shape defect of a belt-like body, which detects a shape defect and detects a shape defect having a size approximately equal to the thickness of the light band at a local density of the light band. In a device that illuminates the surface of a moving band and inspects the shape of the band based on a change in an illuminated image, a plurality of band lights parallel to the surface of the band are spaced at regular intervals in the moving direction of the band. A belt-shaped light irradiating device that simultaneously irradiates and forms a stripe pattern composed of a plurality of stripes of light bands on the band-shaped body surface, a screen that projects a reflection image of the striped pattern reflected on the band-shaped body surface, and a screen projected on the screen. A two-dimensional imaging device that captures a reflected image of a striped pattern, detects a shape defect larger than the width of the light band from a change in the phase of the striped pattern, and detects a shape defect from local shading to about the size of the light band. An apparatus for inspecting a shape defect of a belt-like body, which detects a shape defect. 9. The apparatus according to claim 8, wherein the spatial intensity distribution of the band light is a sine wave or a sine wave to which a bias is applied. A device for illuminating the surface of a moving band and inspecting the shape of the band based on a change in an illuminated image, and irradiating one band of light to the surface of the band while applying intensity modulation at a constant period to the surface of the band. And a screen that projects a reflection image of a light band reflected by the band-shaped body surface, and a time delay integration type imaging device that captures the reflection image with a shift period proportional to the modulation period of the band light, and the obtained stripes A band-like body characterized by detecting a shape defect larger than the width of the light band from a change in the phase of the stripes of the pattern image and detecting a shape defect having a size of about the width of the light band from local shading. Shape defect inspection device. 11. The inspection apparatus according to claim 10, wherein the intensity modulation waveform of the band light is a sine wave or a sine wave to which a bias is applied. 12. The apparatus for inspecting a shape defect of a strip according to claim 10, wherein the irradiation intensity of the strip light is increased in a cycle of one time within the screen of the time delay integration type imaging apparatus.

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