JP3585214B2 - Strip sheet inspection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention, as an inspection target, a band-shaped sheet having a low reflectivity fed out at a constant payout speed, for example, a black rubber-like sheet or a conductive sheet coated with a black conductive paint, and defects on the front surface and the back surface are subjected to image processing. Related to inspection technology.
[0002]
[Prior art]
Defects in the belt-like sheet fed at a constant feeding speed are usually inspected by an image processing device from an image from a line type TV camera. When the feeding speed of the band-shaped sheet is increased, the scan time for capturing one line of the line-type TV camera is shortened, and the exposure time of the line-type TV camera is correspondingly shortened. In the inspection process, the defect is not clearly seen by direct illumination with a high-frequency fluorescent lamp or a halogen light source.
[0003]
Therefore, as shown in FIG. 1, in order to increase the illuminance of the observing portion of the band-shaped sheet 1 to be inspected, that is, the band-shaped field of view of the line type TV camera 2, the light from the rod-shaped light source 4 is lined using the cylindrical lens 3. In general, the light was condensed in a shape and the illuminance of the observation part was increased. According to this inspection, a defect having a clear contrast independent of the direction of illumination is clearly visible, but a defect having a small contrast is hardly visible by direct light from such a fixed-direction illumination. In the defect inspection as described above, using the illumination by indirect illumination is the best method for increasing the contrast, but in this case, the light energy is diffused, and the image becomes dark when the line type TV camera 2 is used. Would.
[0004]
[Problems to be solved by the invention]
In the conventional method, in order to process a defect of the belt-like sheet 1 having a low reflectance fed out from the raw roll at a high speed by using the line type TV camera 2, the direct light condensed in a line has to be used. However, in the case of a defect whose appearance is different depending on the illumination angle, the method of FIG. 1 lowers the reliability of the inspection. Therefore, indirect illumination which does not depend on the illumination angle as shown in FIG. 2 has to be used.
[0005]
In the indirect illumination shown in FIG. 2, the lower part of the ring illumination 5 is shielded from light, and light is emitted only upward from the ring illumination 5. Of the first order or more is reflected by the inner surface of the sheet and reaches the belt-shaped sheet 1.
[0006]
The illumination light is given from all directions by the internal reflection of the hemispherical dome 6, so that the illumination has a uniform intensity. Compared to the illumination at a certain angle as shown in FIG. Illumination by the dome 6 is suitable for defect inspection of the strip-shaped sheet 1 having a low reflectance.
[0007]
However, according to the indirect illumination, the energy of the illumination is diffused in a plane, so that the illuminance per unit area of the observation unit becomes darker than when the light is condensed in a line shape. It cannot be used in image processing using the camera 2.
[0008]
An object of the present invention is to provide an image of a sufficient illuminance in the inspection of a belt-like sheet having a low reflectance, and to perform an image processing so that defects on the front surface, the back surface, and the edge of the belt-like sheet can be inspected with high reliability. It is to be.
[0009]
[Means for Solving the Problems]
The inefficiency of illumination when the line type TV camera 2 is used with indirect light as shown in FIG. 2 is that only a part of the linear energy that can be received out of the light energy irradiated in a planar manner is used. Because there is only. Therefore, use of an area TV camera instead of the line TV camera 2 will be considered.
[0010]
Since the belt-shaped sheet 1 is fed at a high speed of, for example, 30 m / min, it generally depends on the resolution of the image of the area type TV camera, but the shutter is generally released for about 1/1000 second to 1/10000 second, or the strobe light is emitted. If is not used, an image flows at the time of imaging.
[0011]
For example, in the case as shown in FIG. 3, the width of the band-shaped sheet 1 is 50 mm, and the image size of the area type TV camera is 64 mm × 48 mm in VGA size (Sh640dot × Sv480dot). The image resolution of the area type TV camera is 0.1 mm. If the belt-like sheet 1 is fed at a speed of 30 m / min, the moving distance of the belt-like sheet 1 during the exposure time should be within 0.05 mm of 1/2 of the image resolution in order to prevent the image from flowing. Therefore, it is necessary to set the exposure time to 1/10000 second. Further, for continuous inspection, it is necessary to take an image by overlapping the belt-shaped sheet 1. Therefore, it is necessary to take an image every time the belt-shaped sheet 1 moves by 45 mm. , 0.09 seconds.
[0012]
The charge may be charged to a strobe light source, for example, a light-emission condenser of a xenon lamp at each time interval of the imaging, and a flash (light emission) may be performed while a shutter of the area type TV camera is open. Since the flash (light emission) time at this time is about 0.00001 seconds, the shutter opening time is set to about 1/1000 seconds, and during this time, a strobe light with an energy amount of about 1 J may be emitted. By using this method, the brightness of one pixel of the input image is equal to the brightness of one pixel when the line-type TV camera 2 in FIG. Obtainable.
[0013]
Specifically, the present invention provides a belt-like sheet inspection apparatus that inspects front and back defects of a belt-like sheet by image processing while feeding out a belt-like sheet having a low reflectance of an inspection target at a constant feeding speed. Two area-type TV cameras that are placed opposite to each other and have a shutter function to image the front and back of the belt-like sheet, and two area-type TV cameras at fixed time intervals corresponding to the feeding speed of the belt-like sheet. A TV camera control unit for simultaneously instructing the strobes to open, a lighting control unit for simultaneously instructing the two strobe light sources to emit light in synchronization with a shutter opening command for the area type TV camera, and a light emission command from the lighting control unit. The strobe light source emits light in response to a signal, and the light from the strobe light source is reflected by a hemispherical dome-shaped reflecting surface placed opposite to each other with the belt-shaped sheet in between. Two illumination means for irradiating the front and back surfaces of the band-shaped sheet, and two image processing units for image-processing the image of the band-shaped sheet from each area type TV camera and inspecting front and back defects of the band-shaped sheet; Front and back defect determining means for determining the front and back defects of the belt-shaped sheet by integrating the inspection results from each image processing means.
[0014]
Further, the band-shaped sheet inspection apparatus uses the light from the illuminating unit on the opposite side as the transmitted illumination to detect the position of the band-shaped sheet and the edge chipping detection in the image of one band-shaped sheet picked up. Is used as epi-illumination for detecting defects on the front and back of the belt-shaped sheet.
[0015]
The hemispherical dome-shaped reflecting surface has a rectangular observation window having a minimum size such that the observation window of the area type TV camera is not reflected as a shadow in a captured image when observed by the area type TV camera on the same side.
[0016]
The strip-shaped sheet inspection apparatus detects a break of one strip of the strip-shaped sheet by each image processing means, outputs the inspection result of the front and back sides to the front and back defect determination means in a unit of one strip, integrates the inspection result, and collects the inspection result of the front and back of the strip-shaped sheet. Perform defect determination.
[0017]
The image processing means includes an NG data storage unit for recording the captured image determined as NG together with the inspection value, and a video memory, D / D A converter is provided.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 4 shows a belt-shaped sheet inspection apparatus 10 of the present invention. It is assumed that the belt-shaped sheet 1 to be inspected is running at a constant payout speed as described above. The TV camera control unit 11 issues a trigger signal to the two area type TV cameras 12a and 12b at regular time intervals. Each of the area-type TV cameras 12a and 12b is directed to the front and back surfaces of the belt-shaped sheet 1, and receives a trigger signal from the TV camera control unit 11 and simultaneously opens an electronic shutter for about 1/1000 second.
[0019]
The illumination control unit 14 receives the output signal from the TV camera control unit 11 so that the two strobe light sources 13a and 13b emit light simultaneously during the time when the electronic shutters of the area type TV cameras 12a and 12b are open. And the strobe light sources 13a and 13b. For this reason, the illumination control unit 14 captures the feeding speed of the belt-shaped sheet 1 and outputs an output signal at the same timing as a shutter opening command (trigger signal) from the TV camera control unit 11 to the area type TV cameras 12a and 12b. Then, after a delay of about 0.00001 seconds to 0.00005 seconds, the electronic circuit is configured to instruct the strobe light sources 13a and 13b to emit light.
[0020]
Each of the strobe light sources 13a and 13b emits a strong light of about 1 J for about 0.00001 seconds by discharging the charge charged in the light emitting capacitor in response to a light emission command from the illumination control unit 14. . Of course, at this time, the shutter of each area type TV camera 12a, 12b is open. Irradiation light from each of the strobe light sources 13a and 13b is sent to ring illumination guides 8a and 8b through optical fiber cables 7a and 7b, respectively, and distributed in a ring shape, and is reflected by reflection surfaces 9a and 9b inside the hemispherical domes 6a and 6b. The first and higher order reflections are performed, and the front and back surfaces of the belt-shaped sheet 1 are irradiated as indirect light.
[0021]
The hemispherical domes 6a and 6b are arranged at positions sandwiching the belt-shaped sheet 1 from the front side and the back side, and have observation windows 18a and 18b for imaging at the top. The reflection surfaces 9a and 9b on the inner surfaces of the hemispherical domes 6a and 6b are formed by a surface treatment layer having a glossy surface such as irregular reflection. Here, the hemispherical domes 6a and 6b, the optical fiber cables 7a and 7b, the illumination guides 8a and 8b, and the strobe light sources 13a and 13b constitute illumination means 19a and 19b.
[0022]
The image processing units 15a and 15b receive image signals from the area type TV cameras 12a and 12b, inspect the front and back surfaces of the belt-shaped sheet 1 for defects, and output the results to the front and back defect judgment unit 16. . Here, the front and back defect determination means 16 comprehensively determines the inspection result data of the front and back surfaces of the belt-shaped sheet 1 and outputs an NG signal to the outside when, for example, a defect is detected on either the front surface or the back surface. I do. The determination of the inspection result is performed for each screen. That is, the front and back defect determination means 16 performs the above determination for each visual field (claim 1).
[0023]
In the defect detection, a defect detection window slightly smaller than the band-shaped sheet 1 is set in a portion corresponding to the band-shaped sheet 1 of the image, and a binarization process or the like is performed in the window, and a defect such as a scratch is detected in a white area. Is detected as the size of At this time, it is important to cut out the image of the band-shaped sheet 1 from the background, but if the strobe light is emitted from both the front and back surfaces at the same timing as in the present invention, the background of the band-shaped sheet 1 becomes white. In the image of the belt-shaped sheet 1, the left and right edges can be easily cut out.
[0024]
FIG. 5 is a captured image showing the image of the belt-shaped sheet 1 and its background. The band-shaped sheet position detection window is a position including the image of the band-shaped sheet 1 and a white background of the image, and is set as a window having a width in consideration of a left-right shift with respect to the width of the image of the band-shaped sheet 1. , Are set inside the image of the belt-shaped sheet 1. In this captured image, the left and right edges are cut out by performing image processing in the belt-shaped sheet position detection window and performing edge detection processing. That is, when the band-shaped sheet 1 is viewed by the area-type TV camera 12a, the strobe light source 13b from the hemispherical dome 6b on the area-type TV camera 12b side transmits the band-shaped sheet on the image captured by the area-type TV camera 12a as transmitted light. The position of one image is easily detected.
[0025]
FIG. 6 shows a captured image of a defect such as a chipped edge generated at the edge of the belt-shaped sheet 1. In order to inspect such an edge defect, in addition to the defect inspection window, an edge chipping detection window is set so as to straddle each edge of both edges of the belt-shaped sheet 1. In the edge chipping detection window, if there is a chip in the edge, the chipping inside the image of the belt-shaped sheet 1 appears white due to the illumination on the opposite side. Therefore, the depth of the white cut from the edge is measured by image processing. Then, chipping of the edge can be easily detected. Of course, in a normal defect detection window, defects are viewed using the illuminating means 19a, 19b on the side of the area type TV cameras 12a, 12b (claim 2).
[0026]
The observation windows 18a, 18b for the TV cameras in the hemispherical domes 6a, 6b are usually hollowed out so as not to affect the visual field. If the observation windows 18a and 18b are small, a sufficient field of view required for observation cannot be obtained, and the outside of the hemispherical domes 6a and 6b is reflected around the field of view, so that the size is set as appropriate.
[0027]
FIG. 7 shows an image captured by the area type TV cameras 12a and 12b without the band-shaped sheet 1. Since the hemispherical domes 6a and 6b are placed so as to face each other with the band-shaped sheet 1 interposed therebetween, an image taken without the band-shaped sheet 1 shows the inner surface (reflection surface) of the opposite hemispherical domes 6a and 6b. 9a and 9b) appear white due to irregular reflection of the illumination light, but the illumination light does not enter the area type TV cameras 12a and 12b at the positions of the observation windows 18a and 18b, so that the images of the observation windows 18a and 18b appear black.
[0028]
FIG. 8 shows a captured image of the belt-shaped sheet 1 shifted in position. When the belt-shaped sheet 1 is displaced, the images of the observation windows 18a and 18b of the hemispherical domes 6a and 6b on the opposite side appear black at the edge of the image of the belt-shaped sheet 1, which adversely affects edge detection. In order to prevent this, the diameters of the observation windows 18a, 18b of the hemispherical domes 6a, 6b are determined assuming that the shapes and sizes of the two hemispherical domes 6a, 6b and the sizes and shapes of the observation windows 18a, 18b are the same. May be reduced, but this time, the outer surfaces of the hemispherical domes 6a and 6b on the observation side appear at the four corners of the image, which is also inconvenient. Further, by ensuring a sufficient distance between the area type TV cameras 12a and 12b and the belt-shaped sheet 1, the distance from the lens center of the area type TV cameras 12a and 12b to the observation windows 18a and 18b on the imaging side (observation side). By increasing the ratio of the distance from the lens centers of the area type TV cameras 12a and 12b to the opposite observation windows 18a and 18b, the images of the observation windows 18a and 18b of the opposite hemispherical domes 6a and 6b seen on the image are increased. Although there is a method of reducing the size, there are many cases where it is difficult due to restrictions on the size of the apparatus.
[0029]
Therefore, the observation windows 18a, 18b of the hemispherical domes 6a, 6b on the image capturing side have a field of view by matching the shape of the observation windows 18a, 18b of the hemispherical domes 6a, 6b with the shape of the image pickup device of the area type TV cameras 12a, 12b. The amount of the observing windows 18a, 18b on the opposite side applied to the edge of the belt-shaped sheet 1 can be minimized without blocking.
[0030]
FIG. 9 shows a state in which the shapes of the observation windows 18a and 18b of the hemispherical domes 6a and 6b are adjusted to the shapes of the imaging elements of the area type TV cameras 12a and 12b.
[0031]
FIG. 10 is a captured image without the band-shaped sheet 1. According to this, the images of the observation windows 18a and 18b opposite to the hemispherical domes 6a and 6b appear as rectangles. Although the diameters of the images of the round observation windows 18a, 18b of the hemispherical domes 6a, 6b in FIG. 7 are the same as the diagonal lengths of the images of the rectangular observation windows 18a, 18b, the images of the rectangular observation windows 18a, 18b are the same. The left and right widths are smaller than the diameters of the images of the round observation windows 18a and 18b.
[0032]
FIG. 11 shows a captured image in a state where the belt-shaped sheet 1 is displaced. This captured image is a case where the strip-shaped sheet 1 shifted in position is captured using the hemispherical domes 6a and 6b of the rectangular observation windows 18a and 18b. The displacement amount of the belt-shaped sheet 1 is the same as that in the case of FIG. 8, but the width of the observation windows 18a, 18b is small, so that the images of the observation windows 18a, 18b on the opposite side are the same as those of the belt-shaped sheet 1. It is hidden and invisible.
[0033]
As described above, the observation windows 18a and 18b have a minimum size such that the observation windows 18a and 18b do not appear as shadows in the captured image when observed by the area type TV cameras 12a and 12b on the same side by the illumination means 19a and 19b having a hemispherical dome shape. When the rectangular observation windows 18a and 18b are provided, an edge detection error caused by a displacement of the belt-shaped sheet 1 is less likely to occur (claim 3).
[0034]
Next, FIG. 12 shows a form of the belt-shaped sheet 1. The front and back surfaces of the belt-like sheet 1 are interspersed pattern separator is formed shall be the one strip from the separator of one pattern to the separator of the next pattern. For this reason , the inspection result must usually be a result for each strip including the front and back surfaces of the belt-shaped sheet 1.
[0035]
In the example of FIG. Inspects one strip from 11 to 15. In this inspection process, the adjacent visual fields overlap in the extension direction, and are set so as not to omit the inspection in the continuous inspection process. Since such a setting is determined by the feeding speed, the imaging interval, and the size of the visual field, the TV camera control unit 11 has secured the overlap between the visual fields in consideration of the feeding speed and the visual field size as described above. This is the imaging interval. Note that the overlap amount is obtained by a calculation formula [overlap amount = view size− (imaging interval T × delivery speed V)].
[0036]
FIG. 13 shows the internal configuration of the image processing units 15a and 15b. Image signals from the area type TV cameras 12 a and 12 b are A / D converted by the A / D converter 20 and input to the image memory 21. In accordance with the image processing program 23, the CPU 22 performs both image processing for defect detection, storage of inspection results in NG inspection result buffers 29 and 30, transfer of an image to be displayed on the displays 17a and 17b to the video memory 27, and the like. This is performed via the directional bus 25. The memory 24 is a work area when the image processing program 23 is executed.
[0037]
The I / F unit 31 transfers the data in the NG inspection result buffer 29 to the front / back defect determining unit 16. Thereafter, the CPU 22 transfers the data in the NG inspection result buffer 30 to the NG inspection result buffer 29. The contents of the video memory 27 are converted by the D / A converter 28 and displayed on the displays 17a and 17b. Here, the front and back defect determination means 16 performs a defect determination on the front and back surfaces of the belt-shaped sheet 1 for a plurality of images in one strip section by integrating the result data from the two image processing means 15a and 15b ( Claim 1 ).
[0038]
The image processing units 15a and 15b include an NG data storage unit 26. NG data storage unit 26 is a storage device such as a RAM or a hard disk storing the defect determination image, Ru is used when checking the operator an image in manual mode after the inspection in an automatic mode. The NG data includes an NG image and an inspection value corresponding to the NG image. When redisplaying the NG image in the manual mode, the NG image is transferred to the video memory 27 by the CPU 22 so that the NG images of the front and back surfaces of the belt-shaped sheet 1 are displayed on the respective displays 17a and 17b. The operator displays the NG image and the inspection value stored therewith (inspection value which is NG in comparison with the respective determination values of edge chipping detection and defect detection) to obtain any value. It is possible to know the history of the judgment. Further, the image processing units 15a and 15b have a function of reexamining the image. The operator can confirm by himself / herself whether or not the judgment value is appropriate by displaying the processed image at an intermediate stage for each step of the edge chipping and defect detection processing (claim 4 ). .
[0039]
Next, FIG. 14 shows the order of image processing for each visual field by the image processing program. The image processing means 15a and 15b A / D convert the image signals from the area type TV cameras 12a and 12b and store them in the image memory 21, and then detect the edge position. Perform one strip detection operation and detect one strip? Make a judgment. One strip detected? For example, after binarizing a screen, the image level (black = 0, white = 1) is projected in the Y-axis direction of the screen, a valley of the projected value is found, and a pattern break is detected. It is done by doing.
[0040]
As described above, each of the image processing units 15a and 15b has the NG test result buffer 29 and the NG test result buffer 30 as two buffers for storing the test results. 1 strip detection? When the result of the determination is Yes, that is, in the field of view with a pattern break, the image processing means 15a and 15b determine the edge of one strip under inspection (the lower side of the pattern break of the field of view No. 11 in FIG. 12). Chip detection and defect detection are performed, the inspection results are subjected to data logical operation with the NG inspection result buffer 29, and the edge of the next one strip (the upper side of the pattern segment of the field of view No. 11 in FIG. 12) is detected. Chip detection and defect detection are performed, and the inspection results are stored in an NG inspection result buffer 30. The data logical operation is performed by taking a logical sum with NG = 1 and OK = 0. Thereafter, the respective image processing units 15a and 15b transmit the contents of the NG inspection result buffer 29 from the I / F unit 31 to the front and back defect determination unit 16, and then transfer the data of the NG inspection result buffer 30 to the NG inspection result buffer. 29, and ends. 1 strip detection? As a result of the determination of No, that is, in a field of view without a pattern break, the image processing means 15a and 15b perform edge chipping detection and defect detection for one strip currently being inspected in the same manner as described above, and determine the inspection results. Data OR operation with the NG test result buffer 29 is performed, and the process reaches the end.
[0041]
【The invention's effect】
In the present invention, the following specific effects can be obtained. Even with a low-contrast band-like sheet fed out at high speed, an image with sufficient illuminance using illumination by indirect light can be obtained , and one strip of a long band-like sheet fed out at a constant payout speed is used as a break, The front and back surfaces of the one strip section are imaged as a plurality of overlapping visual fields by an area type TV camera, and the front and back defects are inspected in units of the one strip unit. The inspection can be streamlined, and the inspection can be streamlined, and the inspection omission in one strip section can be eliminated by a plurality of overlapping visual fields (claim 1) . By using the illumination of opposite as transmitted light to each other physician can be made compact optical system (claim 2). In addition, by providing a rectangular observation window having a minimum size, it is possible to reduce the influence of the displacement of the running position of the belt-shaped sheet (claim 3). Further stores with test values the captured image NG judgment, it is possible to sequentially display images in the process of re-examination, and confirmed by retesting the NG image, easily adjust the determination value (claim 4).
[Brief description of the drawings]
FIG. 1 is a perspective view of a conventional general observation method.
FIG. 2 is an explanatory diagram of indirect illumination by a hemispherical dome.
FIG. 3 is an explanatory diagram of a field of view by an area type TV camera.
FIG. 4 is an explanatory view of a belt-shaped sheet inspection apparatus according to the present invention.
FIG. 5 is an explanatory diagram of a positional relationship between a defect detection window and a band sheet position detection window on a captured image of the band sheet.
FIG. 6 is an explanatory diagram of an edge missing detection window on a captured image of a belt-shaped sheet.
FIG. 7 is an explanatory diagram of a captured image without a belt-shaped sheet.
FIG. 8 is an explanatory diagram of a captured image in a state where there is a strip-shaped sheet that is displaced.
FIG. 9 is a plan view of a hemispherical dome.
FIG. 10 is an explanatory diagram of a captured image without a belt-shaped sheet.
FIG. 11 is an explanatory diagram of a captured image in a state where there is a band-shaped sheet that is displaced.
FIG. 12 is an explanatory diagram of a separation between a front surface and a back surface of a belt-shaped sheet.
FIG. 13 is a block diagram of an image processing unit.
FIG. 14 is an explanatory diagram of the order of image processing for each visual field.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 strip-shaped sheet 2 line-type TV camera 3 cylindrical lens 4 rod-shaped light source 5 ring illumination 6, 6a, 6b hemispherical dome 7a, 7b optical fiber cable 8a, 8b ring illumination guide 9a, 9b reflection surface 10 strip-shaped sheet inspection device 11 TV camera control unit 12a, 12b Area type TV cameras 13a, 13b Strobe light source 14 Illumination control units 15a, 15b Image processing means 16 Front and back defect determination means 17a, 17b Displays 18a, 18b Observation windows 19a, 19b Illumination means 20 A / D converter 21 Image memory 22 CPU
23 Image processing program 24 Memory 25 Bidirectional bus 26 NG data storage unit 27 Video memory 28 D / A converter 29 NG inspection result buffer 30 NG inspection result buffer 31 I / F unit

Claims (4)

In an inspection apparatus for inspecting front and back defects of a band-shaped sheet by image processing while feeding a band-shaped sheet having a low reflectance at a constant feeding speed, the band-shaped sheet having a shutter function is placed opposite to each other with the band-shaped sheet interposed therebetween. And two area-type TV cameras for imaging the front and back surfaces of one strip as a plurality of fields of view overlapping in the feeding direction of the belt-like sheet, and two areas at regular time intervals corresponding to the feeding speed of the belt-like sheet. Camera control unit for simultaneously instructing the shutter opening of the type TV camera, an illumination control unit for simultaneously instructing the two strobe light sources to emit light in synchronization with the shutter opening instruction of the area type TV camera, and this illumination control unit The strobe light source emits light in response to a light emission command signal from the camera, and a hemispherical dome-shaped And two illumination means for illuminating the surface and the back surface of the belt-like sheet to reflect light from the strobe light source by reflecting surface, the belt-like sheet by image processing the front and back of the image for each field of view of the belt-like sheet from the area type TV camera Two image processing means for inspecting the front and back defects of the above, and a front and back defect judgment means for judging the front and back defects of the belt-shaped sheet by integrating the inspection results for each front and back visual field from each image processing means. ,
Each strip of the strip is detected by each image processing means, and the inspection result for each of a plurality of visual fields on the front and back within one strip is output to the front and back defect determination means in one strip unit, and the front and back inspection within one strip is performed. A band-shaped sheet inspection apparatus, which performs a defect judgment on the front and back of the band-shaped sheet based on the results. In the image of one band-shaped sheet taken, light from the illuminating unit on the opposite side is used as transmitted illumination for position detection and edge chipping detection of the band-shaped sheet, and light from the illuminating unit on the same side is used as epi-illumination as epi-illumination. 2. The belt-like sheet inspection apparatus according to claim 1, wherein the apparatus is used for detecting front and back defects. Provide a hemispherical dome-shaped reflecting surface with a rectangular observation window of the minimum size such that the observation window of the area-type TV camera does not appear as a shadow in the captured image when observed with the area-type TV camera on the same side as the hemispherical dome shape. The belt-like sheet inspection device according to claim 1, wherein: The image processing means includes an NG data storage unit for recording the picked-up image determined as NG together with the inspection value, and an image processing means capable of manually re-inspection and displaying sequentially the images being processed. The belt-shaped sheet inspection device according to claim 1.

Images