JP4355064B2 - Periodic pattern inspection method and apparatus - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
INDUSTRIAL APPLICABILITY The present invention provides a periodic pattern suitable for application to inspection of products such as shadow masks and aperture grills used in color television cathode-ray tubes in which periodic patterns such as periodically formed openings are formed. The present invention relates to an inspection method and apparatus.
[0002]
[Prior art]
As a technique for inspecting defects such as pattern unevenness in products (periodic pattern products) such as shadow masks and aperture grills used in color television cathode-ray tubes, in which periodic patterns such as periodically formed openings are formed. For example, as disclosed in Japanese Patent Laid-Open No. 6-229736, an image of a product is input by an area sensor camera such as a CCD camera and a periodic pattern is inspected based on the input image. .
[0003]
[Problems to be solved by the invention]
However, when the inspection is performed using the area sensor as described above, since the periodic pattern product must be imaged in a stationary state, the product cannot be inspected while continuously moving the product. Therefore, there was a problem that the inspection efficiency was low.
[0004]
Therefore, according to Japanese Patent Application No. 10-280709, the present applicant moves the periodic pattern product between the line sensor camera and the light source and scans the line sensor camera at a predetermined scan rate. By inputting the transmitted light image as a product image and inspecting the periodic pattern based on the product image, the periodic pattern product can be inspected while continuously moving the periodic pattern product. The technology has already been proposed.
[0005]
Here, the proposed periodic pattern inspection apparatus whose principal part configuration is shown in FIG. 13 will be described in detail.
[0006]
This inspection apparatus is an inspection that is a periodic pattern product such as a shadow mask between the line sensor camera 10, a fluorescent lamp (linear light source) 12 disposed opposite to the camera 10, and the camera 10 and the fluorescent lamp 12. The upstream and downstream belt conveyors 14A and 14B, which are transport means for moving the object W, and the line sensor camera 10 are scanned at a predetermined scan rate, and the transmitted light of the moving inspection object W is transferred to the workpiece. (Product) An image processing device 16 is provided which inputs as an image and performs image processing to inspect a periodic pattern based on the workpiece image. Further, between the line sensor camera 10 and the fluorescent lamp 12 Is provided with a diffusion plate 18 for making the irradiation light from the fluorescent lamp 12 uniform.
[0007]
The upstream belt conveyor 14A and the downstream belt conveyor 14B convey the inspection object W in the direction of the arrow, and a gap perpendicular to the conveyance direction indicated by the arrow is formed between the two, and the fluorescent lamp passes through the gap. Illumination light from 12 can be applied to the line sensor camera 10.
[0008]
Here, although not shown, the line sensor camera 10 is arranged in a row in a direction orthogonal to the transport direction, and scans (scans) once in the same direction at a predetermined scan rate. It is composed of a CCD (Charge Coupled Device) line sensor capable of capturing an image for a line. The fluorescent lamp 12 is arranged in parallel with the scanning direction of the line sensor camera 10.
[0009]
The line sensor camera 10 will be described in detail. The camera 10 starts scanning in synchronization with the start pulse and starts capturing an image for one line. This image capturing is required for an image to be input. By repeating the number of lines, an image for one screen is formed. The scan rate of the line sensor camera 10 means an interval at which the start pulse is repeated. When the charge accumulated so far is transferred to the CCD by the scan started by the first start pulse, until the next start pulse. The exposure is continued, and therefore the amount of accumulated light can be adjusted by changing the start pulse interval, that is, the scan rate. The maximum scan rate of the line sensor camera 10 is determined by the maximum video frequency and the number of pixels in the minimum necessary time per scan. When high-speed scanning is required, a model with a higher maximum video frequency and a smaller number of pixels can be scanned faster.
[0010]
The image processing device 16 inputs the light source image by scanning the line sensor camera 10 at a scan rate equal to or lower than the saturation light receiving amount in the state where the inspection object W is not present, and the work image corresponding to the light source image. A transmittance image is created, and the periodic pattern is inspected using the transmittance image. This function will be described in detail later.
[0011]
When the inspection is started by the proposed inspection apparatus, the following preparations are made in advance.
[0012]
First, when the inspection object W is located between the line sensor camera 10 and the fluorescent lamp 12 as shown in FIG. 13 and the camera 10 is scanned, the scan is performed so that the workpiece image can be optimally captured. Set the rate.
[0013]
Specifically, if the input image data is displayed with 256 gradations of 0 to 255 after AD conversion, the gradation is as large as possible within a range where the received light amount is saturated and the gradation value does not exceed 255. Set the scan rate to a value. When the optimum scan rate, that is, the scanning interval is determined, the moving speed of the inspection object W, that is, the upstream side that rotates in synchronization with the target aspect ratio (aspect ratio) is set so that the created work image has a target aspect ratio (aspect ratio) The conveyance speed by the belt conveyors 14A and 14B on the downstream side is adjusted and set to the value.
[0014]
By the way, if the work image captured under the above conditions has unevenness in the light intensity depending on the location of the fluorescent lamp 12 itself, shading resulting from this will be included, and this unevenness will change over time. Therefore, here, in order to prevent erroneous inspection caused by the light source, a light source image is created in advance by imaging the light source itself, a transmittance image is created based on the ratio of the work image to the light source image, The shadow mask periodic pattern is inspected using the image. Briefly describing this transmittance image, I1 is the image data captured without the sample (shadow mask), I is the image data captured with the sample, and Io is the image data representing the dark current of the CCD line sensor. Then, the transmittance T of the point on the sample can be calculated as T = (I-Io) / (I1-Io). Here, I, Io, and I1 are pixel data at corresponding positions. By performing this for each pixel, transmittance image data that is not affected by shading of the light source and long-term fluctuations can be obtained.
[0015]
However, when creating a light source image, it is not possible to input an image under the same imaging conditions as when a shadow mask is captured and a work image is input. The reason for this is that, as shown in FIGS. 14A and 14B, the magnitude of the amount of light emitted from the same light source when there is no inspection object W and when there is no inspection object is conceptually indicated by the thickness of the arrow. If the aperture ratio of the periodic opening (periodic pattern) formed in the object W is a shadow mask, it is as low as 15 to 30%, for example. About 5 times the case. For this reason, if an image is input under the same conditions, the charge of the CCD line sensor is saturated and a white image is formed, and unevenness of the light source cannot be imaged.
[0016]
Therefore, here, when inputting a light source image to be used for creating a transmittance image, as shown in the perspective view of FIG. 15 corresponding to FIG. The camera 10 is scanned and input at a scan rate equal to or lower than a saturated received light amount at which charges accumulated by photoelectric conversion in each element are saturated, that is, at a scan rate that is, for example, 5 times faster when inputting a work image, Let it be a light source image. If the scan rate for capturing the light source image is determined, the light source image may be input for one scan immediately before capturing the work image, for example, and stored in the memory. If a light source image corresponding to the size of the work image is necessary, the stored image data can be created by repeating (copying) the number of scans of the work image.
[0017]
Next, when the slow scan rate (A) and the fast scan rate (B) at which the work image and the light source image can be appropriately input are determined by the above-described method, the book scan is performed using both scan rates. The inspection operation according to the embodiment will be described with reference to the flowchart of FIG.
[0018]
First, before the inspection object W is conveyed, the scan rate of the line sensor camera 10 is increased, the scan rate (B) is set, a light source image is input, and the image data for one scan is stored in the memory. Save (step 31).
[0019]
Next, the scan rate is decreased, the scan rate (A) is set again, and when the inspection object W is conveyed at a constant speed by the upstream belt conveyor 14A, the scan rate (A ) At regular intervals, and the entire image is input as a work image (step 32).
[0020]
Then, the image data of the work image for each scan is divided by the image data of the light source image (pixel value for each corresponding pixel) to create a transmittance image, and the periodic pattern is inspected based on the transmittance image ( Step 33). Thereafter, when the next inspection is performed, the process returns to the above step and the above operation is repeated (step 34). By doing in this way, it can test | inspect correctly, moving the test object W. FIG.
[0021]
As described in detail above, according to the proposed inspection apparatus, it is not necessary to make the inspection object W stand still in order to input an image, so that the tact time of the inspection apparatus can be shortened, and the inspection object can be reduced. Since the image can be input while being moved, there is an excellent advantage that a large product can be inspected reliably.
[0022]
However, in the periodic pattern inspection technique using the proposed inspection apparatus described in detail above, it is necessary to create an accurate transmittance image in order to perform high-accuracy inspection. Since it is important to capture the light source light and input the latest light source image, it has become clear that there are the following new problems.
[0023]
For example, as shown in FIG. 17 corresponding to FIG. 13, a plurality of inspection objects W in which the periodic pattern P is formed in a rectangular range indicated by a two-dot chain line have gaps in the front and rear in order to increase the conveyance efficiency. When connected and transported in such a manner, the light source 12 cannot be directly imaged by the line sensor camera 10, and a light source image cannot be input. Although this problem is not shown in the drawings, this problem also occurs when an inspection object W having a predetermined size is placed on a transport holder cassette (transport member) made of a frame, and the cassette is connected and transported. It happens in the same way. Incidentally, in this case, if the cassette is the inspection object W in FIG. 16, the inspection object corresponds to the pattern P indicated by the two-dot chain line.
[0024]
In addition, as shown in FIG. 18, the inspection object W is conveyed in the length direction indicated by the arrow in a continuous shape in which the periodic pattern P in which the object W falls within the rectangular range of the two-dot chain line is formed at a predetermined interval (period). Similarly, the light source 12 cannot be directly imaged. As described above, when the light source image cannot be input, a new problem arises that the inspection itself based on the transmittance image by the proposed technique cannot be performed.
[0025]
The present invention has been made in order to solve the above-mentioned new problems. An inspection object having a predetermined shape or a conveyance member on which the inspection object is connected is connected, or an inspection object having a continuous shape is connected. Even when inspecting while moving between the light source and the line sensor camera, since the light source image can be input reliably, the periodic pattern inspection method capable of performing high-precision inspection based on the transmittance image And providing an apparatus.
[0026]
[Means for Solving the Problems]
The present invention relates to a periodic pattern inspection method, in which a periodic pattern product is moved between a line sensor camera and a light source, the line sensor camera is scanned, and a transmitted light image of the product is input as a product image. In addition, in a state where the periodic pattern product does not exist, the line sensor camera is scanned to input a light source image, a transmittance image of the product image with respect to the light source image is created, and the transmittance image is used to A periodic pattern inspection method for inspecting a periodic pattern, wherein a slit is formed in a pattern non-formation portion of the periodic pattern product in a width direction perpendicular to the moving direction, and the line sensor camera passes through the slit. By inputting a slit light source image and arranging the slit light source image for a plurality of lines to create the light source image, the problem is solved. It is that persists.
[0027]
In the periodic pattern inspection method, the present invention also scans the line sensor camera while moving the periodic pattern product between the line sensor camera and the light source, and uses the transmitted light image of the product as a product image. In the state where the periodic pattern product does not exist, the line sensor camera is scanned to input a light source image, a transmittance image of the product image with respect to the light source image is created, and the transmittance image is used. A periodic pattern inspection method for inspecting the periodic pattern, wherein the periodic pattern product is formed with a predetermined length in a moving direction, and the product is held and moved by a conveyance member, and the conveyance A slit is formed in the product non-holding part of the product member in the width direction perpendicular to the moving direction, and the slit light source image is input by the licensor camera through the slit. , By creating the light image of the slit light source image a plurality of lines arranged is obtained by solving the above problems as well.
[0028]
The present invention is also directed to a periodic pattern inspection apparatus, a line sensor camera, a light source disposed opposite to the camera, a conveying unit that moves a periodic pattern product between the camera and the light source, and the line sensor. Scanning the camera, inputting a transmitted light image of the moving periodic pattern product as a product image, scanning the line sensor camera in the absence of the periodic pattern product, inputting a light source image, A periodic pattern inspection apparatus comprising: an image processing unit that creates a transmittance image of the product image with respect to a light source image and inspects the periodic pattern using the transmittance image, the line sensor camera A timing sensor for detecting the moving periodic pattern product is installed, and the image processing procedure is determined. Based on a detection signal input from the timing sensor, a slit light source is formed by the line sensor camera through a slit formed in a width direction orthogonal to the moving direction in a pattern non-formation portion of the periodic pattern product. The problem is similarly solved by inputting an image and arranging the slit light source images for a plurality of lines to create the light source image.
[0029]
That is, in the present invention, a slit is formed in the non-patterned portion of the periodic pattern product, and a light source image can be input from the slit by a line sensor camera. Even when inspecting while connecting and moving, or when inspecting while continuously moving periodic pattern products of continuous shape, the light source image can be input reliably, so the period based on the transmittance image Sex patterns can be inspected with high accuracy.
[0030]
Further, in the present invention, even when a periodic pattern product having a predetermined length is held and moved by a conveying member, a light source image is input through a slit formed in a product non-holding portion of the conveying member. Similarly, the periodic pattern can be inspected with high accuracy.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0032]
FIG. 1 is a schematic perspective view showing a main configuration of a periodic pattern inspection apparatus according to an embodiment of the present invention.
[0033]
In the inspection apparatus of the present embodiment, a timing sensor 20 that detects a moving inspection object (periodic pattern product) W at a predetermined position is installed, and a detection signal from the sensor 20 and a pre-input that will be described later. On the basis of information such as image input conditions to be performed, the image processing device 16 performs an operation for determining the timing for inputting a workpiece (product) image and a light source image, and each image is set at the timing set by the processing device 16. , And a control for inspecting the periodic pattern based on the created transmittance image is performed.
[0034]
As the timing sensor 20, as shown in FIG. 2A, a photoelectric sensor having a projector 20A composed of a light source such as an LED or a semiconductor laser, and a light receiver 20B disposed opposite thereto is used. Can do. In this case, a through hole H for timing detection is previously formed in the inspection object W at a predetermined position. By doing so, the object W is transported, and the light receiver 20B changes from the OFF state where the light beam from the projector 20A is blocked to the ON state where the light enters from the through hole H as shown in the figure. The timing can be determined on the basis of the signal output at the time.
[0035]
As shown in FIG. 5B, the timing sensor 20 includes a CCD area sensor camera 20C and a controller 20D, and is attached in advance to a predetermined position of the inspection object W with a high contrast color. The timing mark M having a specific shape may be determined with reference to the time when the output of the camera 20C entering the field of view is turned on.
[0036]
The inspection apparatus according to the present embodiment is substantially the same as the proposed inspection apparatus shown in FIG. Therefore, description of common functions is omitted here.
[0037]
In the present embodiment, the inspection object W has a periodic pattern P whose range is indicated by a two-dot chain line rectangle as shown in FIG. , Formed as a continuous band-like body formed with a period indicated by a one-dot chain line. When such a continuous inspection target image W is inspected by the inspection apparatus, a transmitted light image (work image) for the pattern P can be input, but the light source 12 itself cannot be input.
[0038]
Therefore, in the present embodiment, the pattern non-formation portion of the inspection object W indicated by hatching in the drawing is a light source image capturing area Ar, and a slit is formed in the area as shown in FIG. (Through hole) SL is formed, and the light source 12 can be input by the line sensor camera 10 through the slit SL.
[0039]
Hereinafter, the slit SL will be described in detail. In order to create an accurate transmittance image over the entire pattern P, it is important that the length in the width direction of the slit SL exceeds the width indicated by the broken line corresponding to the width of the pattern P. As shown in the enlarged view (C) of the figure, the slit width LH is arbitrary as long as it is greater than or equal to the resolution of the line sensor camera 10 in the sub-scanning direction, that is, greater than or equal to one pixel. Further, the end in the length direction may be a semicircular shape with R added to the corner portion, or may be a rectangle indicated by a two-dot chain line.
[0040]
Further, as shown in FIG. 4, the slit SL is continuously formed in a full width provided one for each pattern formation period indicated by a one-dot chain line in the length direction of the inspection object W. By continuously forming the slit SL in this way, a light source image can be input every time a periodic pattern is input, so that an accurate transmittance image can always be created. However, the slit SL is not limited to the continuous formation provided for each period of the pattern P, but it is needless to say that the slit SL may be a full width discontinuous formation provided for every two or more periods.
[0041]
The slit formed in the inspection object W may have a continuous partial width as shown in FIG. This is a pattern in which the slit SL having the full width shown in FIG. 4 is formed with a partial width of substantially 1/3, and the slits SL1 to SL3 having the partial widths are indicated by alternate long and short dashed lines. Each formation cycle is shifted by the same width, and in this way, a light source image for the entire width can be input every three cycles. Here, in order to allow the light source image for the entire width to be input completely in three cycles, the partial width slits SL1 to SL3 are partially overlapped at the ends as indicated by broken lines. Is formed.
[0042]
By adopting such a partial width continuous shape, it is possible to input a light source image at a constant periodic interval, so that it is possible to create an accurate transmittance image in the same manner, and there are through holes only in a part of the width direction. Since it is not formed, there is an advantage that even a thin plate-like inspection object W can be prevented from decreasing in strength. However, the partial width slit is not limited to the continuous shape for each period as described above, but may be a discontinuous shape formed with an interval of one period or more as in the case of the full width.
[0043]
Next, the operation of this embodiment will be described according to the flowchart shown in FIG.
[0044]
First, in step 1, parameters are set. Here, as parameters, (1) product size (width and length), (2) slit type (full width / partial width, continuous / discontinuous), and (3) number of slit divisions in the case of partial width (4) Image input conditions such as a slit formation period in the case of discontinuity are determined.
[0045]
Next, as in the case of the proposed inspection, the scan rate for the product (work) image is set (step 2), and when the signal from the timing sensor 20 for image input is input, Imaging is performed (steps 3 and 4).
[0046]
When continuity is set, which means that slits are formed every one cycle as a parameter in the step (YES in step 5), the scan for the light source image is performed as in the case of the proposed inspection. The rate is set (changed) (step 6), the signal input from the timing sensor 20 is input and a light source image is taken, and when this is completed, the process returns to step 2 (steps 7 and 8).
[0047]
On the other hand, if it is determined in step 5 that continuity is not set, i.e., it is determined that the slit is not formed every period, it is determined in step 9 whether or not it is the timing for capturing a light source image, i.e., this stage. To determine whether or not there is a slit at a predetermined position. If NO (NO), the process returns to step 3 to capture the next product image. If YES (YES), the same step as in the continuous case is performed. A light source image is taken according to 6-8. In the determination of step 9, it is determined by counting the slit period set as a parameter to determine that it is the timing of imaging, or the presence / absence of a slit is transmitted each time the signal is input from the timing sensor 20 in step 3 above. To make decisions.
[0048]
When a light source image is captured in steps 6 to 8, images are input for several scan lines in the vicinity of the slit position in order to reliably capture the light source. Then, as shown in the procedure of FIG. 7, the projection processing of the luminance in the width direction is performed for each line image in units of one line of line images (step 11), and each of the plurality of line images is projected. Among them, a coordinate having the maximum projection result (sum of luminance for all pixels) is detected (step 12), and a line image for one scan of the coordinate is set as a slit light source image for light source image creation.
[0049]
FIG. 8A shows a projection result in which the image of a plurality of lines inputted by scanning with the slit as the center as described above, and the right side (B) of the luminance values of the images of each line are summed. showed that. In the case of this example, since the maximum luminance value is the fifth line from the top, the image of this line is a slit light source image as shown in FIG. That is, the brightest line is taken out as a line photographed at the center of the slit, and is taken as a slit light source image.
[0050]
Next, a method of creating a light source image for calculating a transmittance image using the slit light source image input as described above will be described. The first is a batch full width overwriting method. This is because the slit light source image created as described above is repeated so as to be substantially the same as the size of the product (work) image, and a light source image for calculation is created. All are replaced by new slit light source images.
[0051]
Now, if the periodic pattern portion formed in the t-th cycle is represented as a product t for convenience, and the slit light source image is represented by a thin rectangle (bar) with t added thereto, FIG. As shown in the image of the method, the light source image shown in FIG. 5A, which is created entirely by the slit light source image of the product t-1, is the next product as shown in FIG. This is a method of replacing all at once by the slit light source image of t. Incidentally, here, t means this time and t-1 means the previous time.
[0052]
The second is a batch full width average method, which is not shown in the figure, but does not replace the slit light source image of the product t-1 with a new one of the product t, as shown in FIG. The slit light source image of the product t in FIG. 5B is replaced with the average image data of both the product t-1 and the product t: {(t-1) + t} / 2, and the previous information is left. It is a method to make.
[0053]
The third is a sequential full width overwriting method, which updates the entire light source image by sequentially arranging slit light source images captured by different products line by line, as shown in FIG. In this case, as shown in FIG. 4B, the slit light source image of the oldest product t-n is replaced with the slit light source image of the latest product t so as to be sequentially updated and created. However, in the case of this sequential method, the light source image for one screen cannot be input immediately after the start of the inspection. Therefore, (1) First, the batch method is adopted temporarily, or (2) the latest light source image before that is used. It is necessary to store the image and update the image sequentially, or (3) in some cases, wait for the completion of one screen to perform the inspection.
[0054]
Fourth, as in the case of collective processing, the target slit light source image is not made to be the slit light source image of the product t as shown in FIG. And the average of the slit light source images of the new product t: the image data of {(t−n) + t} / 2.
[0055]
The fifth is a batch partial overwrite method. As shown in FIG. 11A, the entire light source image is composed of slit light source images divided into three in the vertical direction. This shows the light source image of the product t-1, and is created in combination with the slit light source images of the products t-3 and t-2. The light source image of the product t is created by collectively changing the slit light source image of the oldest product t-3 with the latest t data, as shown in FIG.
[0056]
The sixth is a batch partial average method, which is similar to the case of the full width described with reference to FIG. 8, and that the slit light source image of the product t in FIG. 11B is an image of {(t−3) + t} / 2. It is a method of replacing with data.
[0057]
The seventh is a sequential partial overwrite method, and an example of three divisions is shown in FIG. For convenience, only the slit light source images of the updated product t-1 and the updated product t-n are clearly shown in FIGS.
[0058]
The eighth is a sequential partial averaging method, which is also the same as in the case of the full width described above. When a new slit light source image is obtained, it is replaced with the average data of the old and new ones.
[0059]
According to the present embodiment described in detail above, a light source image can be input also for a continuous inspection object W, so that it is possible to inspect a periodic pattern using a transmittance image. In addition, since the light source image can be input in a minimum space called a slit (light source image capturing area), the influence on the tact time of the inspection line can be reduced.
[0060]
In addition, by making the slit configuration discontinuous, for example, when it is desired to inspect an inspection object under a certain period in the inspection line under the same conditions, by providing a slit at the beginning or end of the period, All inspection objects within the period can have the same light source image (same conditions).
[0061]
Furthermore, as described above, by making the configuration of the slit a partial width, it is possible to prevent a decrease in strength due to the slit being provided in the front width (the front and rear inspection objects are connected only at both ends).
[0062]
Although the present invention has been specifically described above, the present invention is not limited to that shown in the above embodiment, and various modifications can be made without departing from the scope of the invention.
[0063]
For example, the inspection object may have a predetermined length as described with reference to FIG. The object for forming the slit is not limited to the inspection object, and may be a conveyance member such as a conveyance holder cassette that holds the inspection object of a predetermined length.
[0064]
In the above-described embodiment, the slit is provided on the rear side with respect to the flow direction of the inspection object. However, the slit may be provided on the front side, and the partial width is not limited to the case of three divisions.
[0065]
Further, the inspection object is not limited to the shadow mask, but is also an aperture grill used for a color television cathode ray tube, a color separation filter for a color imaging device, a color filter for a liquid crystal display panel, a mesh electrode used for an electron tube, Unit patterns with certain optical properties and shapes, such as VDT filters, photomasks, Fresnel lenses, lenticular killer lenses, coating sheets, color sheets, and polarizing sheets, are regularly and repeatedly arranged in one or two-dimensional directions. There is a difference in the density of the industrial product, or the industrial pattern in which the single pattern is repeatedly arranged with its optical properties, shape, one-dimensional direction and two-dimensional arrangement pitch gradually changing, or plain or plain. Mention industrial products with small and uniform optical properties .
[0066]
【The invention's effect】
As described above, according to the present invention, the inspection object or a conveying member for mounting and conveying the inspection object is connected, or the inspection object having a continuous shape is placed between the light source and the line sensor camera. Even when passing through and inspecting, a light source image can be reliably captured. Therefore, the periodic pattern can be inspected based on the transmittance image created from the light source image.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main configuration of a periodic pattern inspection apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating an example of a timing sensor and a timing determination method.
FIG. 3 is an explanatory diagram showing features of the present invention.
FIG. 4 is an explanatory diagram showing characteristics of an inspection object used in the embodiment.
FIG. 5 is an explanatory view showing another feature of the inspection object used in the embodiment.
FIG. 6 is a flowchart showing the operation of the embodiment.
FIG. 7 is a flowchart showing a procedure for creating a light source image.
FIG. 8 is an explanatory diagram corresponding to the flowchart.
FIG. 9 is an explanatory diagram showing characteristics of a light source image by a batch full width overwriting method.
FIG. 10 is an explanatory diagram showing characteristics of a light source image by a sequential full width overwriting method.
FIG. 11 is an explanatory diagram showing characteristics of a light source image by a batch partial width overwriting method.
FIG. 12 is an explanatory diagram showing characteristics of a light source image by a sequential partial width overwriting method.
FIG. 13 is a perspective view showing the main configuration of the proposed inspection apparatus.
FIG. 14 is an explanatory diagram conceptually showing a difference in received light amount when capturing a light source image and a work image.
FIG. 15 is a perspective view showing the imaging state of the light source image of the proposed inspection apparatus.
FIG. 16 is a flowchart showing the operation of the proposed inspection apparatus.
FIG. 17 is an explanatory diagram showing problems of the proposed inspection technique.
FIG. 18 is another explanatory diagram showing problems of the proposed inspection technique.
[Explanation of symbols]
10. Line sensor camera
12 ... Fluorescent light
14 ... belt conveyor
14A: Upstream belt conveyor
14B ... Downstream belt conveyor
20 ... Timing sensor
W ... Inspection object

Claims (12)

While moving the periodic pattern product between the line sensor camera and the light source, the line sensor camera is scanned to input a transmitted light image of the product as a product image,
In the absence of the periodic pattern product, the line sensor camera is scanned to input a light source image, a transmittance image of the product image with respect to the light source image is created, and the periodicity is used using the transmittance image. A method for inspecting a periodic pattern for inspecting a pattern,
In the pattern non-formation part of the periodic pattern product, a slit is formed in the width direction orthogonal to the moving direction, and a slit light source image is input by the line sensor camera through the slit,
A periodic pattern inspection method, wherein the slit light source image is arranged for a plurality of lines to create the light source image. In claim 1,
The method for inspecting a periodic pattern, wherein the slit is formed to have a full width exceeding a formation range in a width direction of the periodic pattern. In claim 1,
A periodic pattern inspection method, wherein the periodic pattern product is formed in a continuous shape in the moving direction. In claim 3,
The slit is formed to have a full width that exceeds the formation range of the periodic pattern in the width direction, and is formed in the length direction of the product for each period of forming one or more periodic patterns. A periodic pattern inspection method. In claim 3,
The slit is formed with a partial width corresponding to a length obtained by dividing the entire width exceeding the formation range in the width direction of the periodic pattern, and one or more periodic patterns are formed in the product length direction. It is formed by shifting the position in the width direction so that when the slit light source image is input by the line sensor camera through each slit at every formation period, the slit light source image for the entire width is input as a whole. Inspection method for periodic patterns. While moving the periodic pattern product between the line sensor camera and the light source, the line sensor camera is scanned to input a transmitted light image of the product as a product image,
In the absence of the periodic pattern product, the line sensor camera is scanned to input a light source image, a transmittance image of the product image with respect to the light source image is created, and the periodicity is used using the transmittance image. A method for inspecting a periodic pattern for inspecting a pattern,
The periodic pattern product is formed with a predetermined length in the moving direction, and the product is held and moved by a conveying member, and
In the product non-holding portion of the conveying member, a slit is formed in the width direction orthogonal to the moving direction, and a slit light source image is input by the licensor camera through the slit,
A periodic pattern inspection method, wherein the slit light source image is arranged for a plurality of lines to create the light source image. In claim 1 or 6,
The line sensor camera is scanned a plurality of times in the vicinity of the slit to input a plurality of line images, the luminance values of all the pixels are added for each line image, and the line image having the maximum addition value is added to the slit light source image. The periodic pattern inspection method characterized by the above-mentioned. In claim 1 or 6,
A periodic pattern inspection method, wherein when creating the light source image, all of the slit light source images constituting the previous light source image are collectively changed based on the inputted current slit light source image. In claim 1 or 6,
A method for inspecting a periodic pattern, characterized in that, when creating the light source image, the oldest slit light source image constituting the previous light source image is sequentially changed based on the input current slit light source image. . A line sensor camera, a light source disposed opposite to the camera, a conveying means for moving the periodic pattern product between the camera and the light source, and transmission of the periodic pattern product moving by scanning the line sensor camera While inputting a light image as a product image, in a state where the periodic pattern product does not exist, scan the line sensor camera to input a light source image, create a transmittance image of the product image with respect to the light source image, An inspection apparatus for a periodic pattern comprising image processing means for inspecting the periodic pattern using the transmittance image,
In order to determine the image input timing by the line sensor camera, a timing sensor for detecting the moving periodic pattern product is installed,
Based on the detection signal input from the timing sensor, the line sensor passes through the slit formed in the width direction orthogonal to the moving direction in the pattern non-formation portion of the periodic pattern product. While inputting the slit light source image with the camera,
A periodic pattern inspection apparatus having a function of creating a light source image by arranging the slit light source images for a plurality of lines. In claim 10,
The periodic light pattern inspection apparatus, wherein the light source is a linear light source disposed in parallel with a scanning direction of a line sensor camera. In claim 10,
Inspection of periodic pattern characterized in that the conveying means has an upstream conveyor and a downstream conveyor, and the line sensor camera and the light source are arranged along a gap formed between the two conveyors. apparatus.

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