JP2000105833A - Method and system for surface inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely perform the inspection of a surface state such as defect inspection on an object to be inspected by removing the influence of variance of elements of a linear image sensor constituting a camera. SOLUTION: Digital image data obtained by scanning the object 10 which moves relatively in a vertical scanning direction along a space axis (horizontal scanning direction) by a digital camera having a linear image sensor 13 are inputted to an arithmetic processor 16, which performs an arithmetic process in the direction of the time base (vertical horizontal scanning direction) by using an N-line memory 17 and a correlator 18 to obtain the surface state of the object 10 through a decision unit 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having an image sensor for inspecting molded articles and other various objects to be inspected for defects such as scratches and dirt. The present invention relates to a surface inspection method and system which can be removed to enable high-precision inspection.

[0002]

2. Description of the Related Art For example, when inspecting a surface defect of an object to be inspected such as an extruded product, a drawn molded product, a roll molded product, etc., a one-dimensional image formed by arranging photoelectric conversion elements one-dimensionally is conventionally used. 2. Description of the Related Art A method has been adopted in which a test object is one-dimensionally scanned by a camera such as a CCD camera using a sensor (line image sensor), and arithmetic processing is performed on image data obtained thereby.

A two-dimensional image sensor used for a video camera or the like usually has only a few hundred pixels in the viewing width direction, whereas a line image sensor integrates thousands of imaging pixels in the viewing width direction. Therefore, by using a line image sensor, it is possible to perform a surface inspection of an inspection object such as steel, paper, or a film having a wide width that cannot be achieved by a two-dimensional image sensor.

In such a camera, the reading accuracy of the brightness by the image sensor varies depending on the photoelectric conversion element. This element variation is caused by a difference in sensitivity between the individual photoelectric conversion elements constituting the image sensor, and is called element variation, and usually takes a value of about 3%. In the above-described conventional surface inspection system, it is not possible to detect a minute defect or the like unless there is a brightness change exceeding the range of the element variation. It is said that the accuracy of visual light / dark detection is 1/1500 to 1/2000, so a surface inspection system using a line image sensor has only 1 / 60th the accuracy of visual inspection, and it is impossible to substitute visual inspection. And has been.

In a field such as an electronic copying machine, as a method of compensating for device variations of an image sensor, device variations of a scanner image sensor are obtained in advance and stored in a RAM, and based on this, the device variations are corrected. Methods are also being considered. The element variation is determined based on the variation in image data when a uniform original whose entire surface is white is read by the image sensor.

However, according to this method, when the brightness or color of the background is limited, such as a document, the element variation can be obtained relatively easily. Since there are many types of brightness, color, shape, and the like, and the brightness of illumination light also changes in various ways, it has been extremely difficult to obtain element variations corresponding to all of these.

[0007]

As described above, in the surface inspection using a camera including a conventional image sensor, it is difficult to remove the influence of the element variation of the photoelectric conversion element, and the improvement of the inspection accuracy is limited. was there.

The present invention provides an inspection method and an inspection system capable of accurately inspecting a surface state such as detecting a defect on an inspection object by removing the influence of element variation of an image sensor constituting a camera. The purpose is to:

[0009]

In order to solve the above-mentioned problems, a surface inspection method according to the present invention provides image data obtained by scanning an object to be inspected in the direction of a spatial axis by a camera having an image sensor. In contrast, a fundamental feature is that the surface state of the inspection object is inspected by performing arithmetic processing in the time axis direction.

[0010] More specifically, the surface inspection method according to the present invention relates to a camera having an image sensor configured by arranging a plurality of photoelectric conversion elements at least in the main scanning direction. The surface state of the inspection object is inspected by performing arithmetic processing on the image data output from the camera in the sub-scanning direction while relatively moving in the sub-scanning direction orthogonal to the vertical direction.

A surface inspection system according to the present invention has an image sensor configured by arranging a plurality of photoelectric conversion elements at least in a main scanning direction, and relatively moves in a sub-scanning direction orthogonal to the main scanning direction. A camera that scans the object to be inspected in the main scanning direction and outputs image data, and performs an arithmetic operation on the image data output from the camera in the sub-scanning direction to obtain a surface state of the inspection object And a processing device.

As described above, according to the present invention, image data output from a camera having an image sensor is
By calculating the surface state of the inspection object by performing arithmetic processing in the time axis direction (sub-scanning direction), it is possible to perform a high-precision surface inspection that eliminates the influence of element variations of the image sensor. That is, the image data corresponding to the individual elements of the image sensor is not affected by the element variation on the time axis, and basically changes only depending on the surface state of the inspection object. When the arithmetic processing is performed in the time axis direction as described above, if the quantization accuracy of the image data is sufficiently high, the inspection of the surface state such as the presence or absence of a defect can be performed more accurately.

According to one aspect of the present invention, the arithmetic processing unit stores N consecutive main scanning lines (N is an integer of 1 or more) of image data output from the camera.
A line memory, a correlator for calculating a correlation value between input and output image data of the N-line memory, and a magnitude of the correlation value output from the correlator to determine a surface state inspection result of the inspection object. And a determiner for obtaining. The determiner is composed of, for example, a comparator.

With this configuration, the correlation between the surface states of two positions separated from each other by N main scanning lines in the sub-scanning direction on the inspection object is obtained. For example, if one of these two positions has a defect, If the correlation value increases, a defect is detected.

According to another aspect of the present invention, there is provided an arithmetic processing device comprising:
An N-line memory for storing image data of N consecutive main scanning lines (N is an integer of 1 or more) output from the camera, and a correlation for obtaining a correlation value between input and output image data of the N-line memory And a determiner that determines the magnitude of the correlation value output from the correlator and obtains an inspection result of the surface state of the inspection object, and sets the value of N to N
., N2, N3,... And a plurality of different arithmetic processing units.

With this arrangement, each of the arithmetic processing units has N1 on the inspection object in the sub-scanning direction.
Main scanning line, N2 main scanning line, N3 main scanning line ...
, The correlation between the surface states at two positions separated by different distances is obtained, respectively, so that N1, N2, N
A defect having a size corresponding to the value of 3,... Is detected. Moreover, the detection of the defects having different sizes is performed simultaneously and in parallel.

An arithmetic processing unit according to another aspect of the present invention comprises:
A plurality of line memories that store image data for a plurality of continuous main scanning lines output from the camera, and an adder that adds the image data output from the camera and the image data output from the plurality of line memories. And a determiner for determining the magnitude of the added value output from the adder to obtain an inspection result of the surface state of the inspection object.

According to this configuration, the image data obtained corresponding to the same element of the image sensor is added, so that the image data (added value) input to the determiner can be input without being affected by the element variation. Can be large,
In the output stage of the one-dimensional image sensor, even a low-contrast defect having a very small image signal level can be easily detected.

According to another aspect of the present invention, there is provided an arithmetic processing apparatus comprising: a line memory group for storing image data for a plurality of continuous main scanning lines output from a camera; and a first memory selected from the line memory group. A first adder for adding image data output from a plurality of line memories in a group, and a second addition for adding image data output from a plurality of line memories in a second group selected from the line memory group A correlator for obtaining a correlation value between the added values output from the first and second adders; and a surface state of the inspection object by determining the magnitude of the correlation value output from the correlator. And a determiner for obtaining the inspection result of

According to such a configuration, when the reference levels of the image data respectively input to the two adders are different due to the effects of thermal disturbance noise of the image sensor and ripples of the illumination light source of the inspection object. However, the difference in the reference level is canceled in the course of the correlation calculation by the correlator, and the defect can be detected more accurately.

An arithmetic processing device according to still another aspect of the present invention includes a first inspection mode for performing arithmetic processing on image data output from a camera in a sub-scanning direction to obtain a surface state of an inspection object; A second inspection mode is provided in which arithmetic processing is performed on the data in a direction oblique to the main scanning direction and the sub-scanning direction to obtain the surface state of the inspection object.

This arithmetic processing unit has a two-dimensional memory array for storing image data for a plurality of continuous main scanning lines output from a camera, for example, and performs first and second inspections from the two-dimensional memory array. The image data is read in a read pattern corresponding to the mode, and an arithmetic process is performed on the read image data.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a configuration of a surface inspection system according to a first embodiment of the present invention. In FIG. 1, an inspection object 10 is, for example, an extruded product, a drawn product, a roll product, or the like, and moves in a direction indicated by an arrow Y (sub-scanning direction) during surface inspection. A digital camera 11 is installed facing the inspection object 10.

The digital camera 11 includes the imaging lens 1
2. One-dimensional image sensor 13, such as CCD line image sensor, amplifier 14, and A / D converter 15
The image of the surface of the inspection object 10 is formed on the one-dimensional image sensor 13 via the imaging lens 12. Inspection object 10 by one-dimensional image sensor 13
Assuming that the upper reading width is 1, when the imaging lens 12 is a standard lens, the distance (object distance) from the camera 11 to the inspection object 10 is set to about 1.5.

The one-dimensional image sensor 13 is configured by arranging a plurality of (for example, 5120) photoelectric conversion elements in a direction indicated by an arrow X (main scanning direction), and a direction orthogonal to the main scanning direction. The inspection object 1 that moves relatively in the (sub-scanning direction) is scanned in the main scanning direction on the inspection object 10.
The surface state of 0 is read and an image signal is output. The image signal output from the one-dimensional image sensor 13 is amplified by an amplifier 14, further converted into 8-bit parallel digital data by an A / D converter 15, and output from the digital camera 11 as image data.

Image data output from the digital camera 11 is input to the arithmetic processing unit 16. The arithmetic processing device 16 outputs an inspection result of the surface state of the inspection object 10 by performing arithmetic processing on the input image data in the Y direction. In this example, the N line memory 1
7, a correlator 18 and a determiner 19. Here, N is an arbitrary integer of 1 or more.

The N-line memory 17 is a memory for storing image data for N main scanning lines inputted from the digital camera 11, and stores the number of photoelectric conversion elements (for example, 5120 elements) in the one-dimensional image sensor 13. N
It is composed of a double-stage shift register or FIFO (first-in first-out) memory.

Image data input / output to / from the line memory 17;
That is, the image data input from the digital camera 11 and the image data output from the line memory 17 are input to the inputs A and B of the correlator 18. Correlator 18
Is a circuit for performing a correlation operation between input and output image data of the line memory 18 given to the input A and the input B to obtain a correlation value between the two image data, and is specifically constituted by a subtractor or a divider. You.

Here, the image data input to the inputs A and B of the correlator 18 respectively correspond to the image signals obtained from the same element of the one-dimensional image sensor 13.
That is, since the input B is delayed from the input A of the correlator 18 by N main scanning lines by the line memory 17, the input A is the i-th (i =
When the image data corresponding to the elements (1, 2,...) Is input, the image data of the Nth main scanning line corresponding to the same i-th element is input to the input B from the line memory 17.

The correlation value output from the correlator 18 is input to the determiner 19, and its magnitude is determined. Judge 19
Is constituted by, for example, a comparator. In this example, the presence or absence of a surface defect of the inspection object 10 is determined by comparing the correlation value output from the correlator 18 with an appropriate threshold value TH. It is output as the status check result.

That is, if there is a defect on the inspection object 10, the size of the image data corresponding to the same element of the one-dimensional image sensor 13 in the vicinity of the defect accompanies the sub-scan, that is, the inspection object 10 Since the correlation value obtained by the correlator 18 becomes larger and exceeds the threshold value TH in the determiner 19 due to the temporal change along with the relative movement of the Can be. The determination result of the determiner 19 is processed by, for example, a personal computer and displayed on a display device (not shown).

According to the inspection system of the present embodiment, a high-precision inspection can be performed without the influence of the element variation of the one-dimensional image sensor 13. Hereinafter, this effect will be described in more detail with reference to FIG.

FIG. 2 is a conceptual diagram of image data output from the digital camera 11 and shows a case where the surface state of the inspection object 10 is uniform. This image data is 25
Six gradations, that is, data in which the brightness changes in 256 steps according to the surface state of the inspection object 10, for example, in the X direction (main scanning direction = space direction) in 1/2000 seconds
120 points scanned, Y direction (sub-scan direction = time axis direction)
Is output at a cycle of 2000 times / second.

The element variation of the one-dimensional image sensor 13, that is, the brightness variation of the image data in the X direction is usually 3
%, And no effective method has been found in the field of surface inspection to suppress this device variation. On the other hand, in the present invention, the image data corresponding to each element of the one-dimensional image sensor 13 is not affected by the element variation when viewed on the time axis, and the image data corresponding to the same element is focused on. By performing a calculation process in the Y direction (time axis direction) to inspect the surface state of the inspection object 10, high-precision inspection in which the influence of element variation is removed is enabled.

In this case, variation in image data corresponding to the same element of the one-dimensional image sensor 13 poses a problem. If the conversion accuracy of the A / D converter 15 is set to 8 bits, the Since the data has 256 gradations and the change in brightness can be detected with an accuracy of 1/256, the variation of the image data corresponding to the same element is about 0.4%.
It can be kept sufficiently small as follows. A / D
If the conversion accuracy of the converter 15 is increased to, for example, 10 bits, 12 bits,..., The variation in the image data is further reduced.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
1 shows a configuration of an arithmetic processing device according to the embodiment. This arithmetic processing device has a plurality (three in this example) of arithmetic processing units 16-1, 16-2, and 16-3 having the same configuration as the arithmetic processing device 16 shown in FIG. It is configured.

That is, the arithmetic processing unit 16-1 has N
Line memory 17-1, correlator 18-1, and determiner 1
9-1, and the arithmetic processing unit 16-2 has N
Line memory 17-2, correlator 18-2, and determiner 1
9-2, and the arithmetic processing unit 16-3 has N
Line memory 17-3, correlator 18-3, and determiner 1
9-3. Judgers 19-1, 19-2,
19-3 is constituted by, for example, a comparator similarly to the first embodiment, and appropriately set threshold values TH1, T
H2 and TH3 are given.

Here, each processing unit 16-1, 1
6-2, 16-3 each N line memory 17-
Assuming that N of 1, 17-2, 17-3 is N1, N2, N3, these are, for example, N1 = 1, N2 = 30-40, N3
= 79 is set to a different value. By doing so, the arithmetic processing units 16-1, 16-2, 1
In 6-3, defects having different sizes on the inspection object 10 are respectively detected.

That is, the arithmetic processing unit 16-1 detects a "micro defect" in which the brightness sharply changes between adjacent main scanning lines.
In 6-2, a medium-sized "normal defect" whose brightness gradually changes over 30 to 40 lines is detected, and the arithmetic processing unit 16-3 further detects a very wide range of about 80 lines. A “color unevenness defect” whose lightness changes is detected. Arithmetic processing unit 16-
1, 16-2 and 16-3 determiners 19-1 and 19-
The determination results of 2, 19-3 are processed by, for example, a personal computer and displayed on a display device (not shown).

FIG. 4 is a display example of the inspection result in this embodiment. Defect images 41, 4 having different colors, for example, so that the above-mentioned "micro defect", "normal defect", and "uneven color defect" can be distinguished from each other on the image of the inspection object 10.
2, 43 are displayed. From such a display, it is possible to clearly understand how various kinds of defects are distributed on the inspection object 10.

(Third Embodiment) FIG. 5 shows a second embodiment of the present invention.
1 shows a configuration of an arithmetic processing device according to the embodiment. The arithmetic processing unit 20 according to the present embodiment includes a plurality of cascade-connected line memories 21-1 to 21-3 and an addition for obtaining an addition value of input / output image data of the line memories 21-1 to 21-3. It comprises a device 22 and a determiner 23.

That is, digitized image data from the digital camera 11 of FIG. 1 is input to the first-stage line memory 21-1 and the adder 22, and is output from the first-stage line memory 17-1. Image data is input to the second-stage line memory 21-2 and the adder 22, and similarly, the image data output from the second-stage line memory 21-2 is input to the third-stage line memory 21-3. Is input to the adder 22, and the image data output from the third-stage line memory 21-3 is further input to the adder 22. Then, an adder 22 calculates an added value of these four image data.

The added value output from the adder 22 is input to the determiner 23. The determiner 23 is composed of, for example, a comparator as in the first embodiment. In this example, the comparator 23 compares the addition value output from the adder 22 with an appropriate threshold value TH to determine the surface defect of the inspection object 10. The presence or absence is determined, and the determination result is output as a surface state inspection result.

The four image data input to the adder 22 have a delay time of one main scanning line with respect to each other by the line memories 21-1 to 21-3. This corresponds to an image signal obtained over four continuous main scanning lines. Therefore,
At a certain point in time, the adder 22 adds image data obtained corresponding to the same element of the one-dimensional image sensor 12. This addition operation is performed on image data obtained over four main scanning lines corresponding to the respective elements of the one-dimensional image sensor 13, and the same addition operation is sequentially performed on one main line as the inspection object 10 moves. This is sequentially performed on image data obtained over four continuous main scanning lines shifted by scanning lines.

As described above, when the image data obtained corresponding to the same element of the one-dimensional image sensor 12 is added, that is, when the image data is added in the sub-scanning direction (time axis direction), there is no influence of the element variation. , Determiner 23
The input image data (added value) can be made large, and it is possible to easily detect even a low-contrast defect such as a very low image signal level at the output stage of the one-dimensional image sensor 13.

In FIG. 5, three line memories 21-1 to 21-3 are cascade-connected for simplicity. However, actually, about 10 to several tens of line memories are cascade-connected.
It is desirable that the adder 22 adds the image data of 10 to several tens of continuous main scanning lines.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
1 shows a configuration of an arithmetic processing device according to the embodiment.
The arithmetic processing device 30 according to the present embodiment includes cascade-connected line memory groups 31-1 to 31-7, a multiplexer 32, two adders 33-1 and 33-2, a correlator 34, and a determiner 35. You.

The digitized image data from the digital camera 11 shown in FIG.
1, the image data and the line memory group 31-
The image data of the output of 1-31-7 is
Is input to The multiplexer 32 selects two groups from the line memory groups 31-1 to 31-7, inputs image data output from the first group of line memories to the first adder 33-1, The image data output from the line memory of the group is added to the second adder 33-
Enter 2

In FIG. 6, the line memory groups 31-1 to 31-1
The number 31-7 is seven, but is actually a large number of several to several hundred. In FIG. 6, the adders 33-1 and 33-2 are used.
Although four pieces of image data are input to each of them, actually ten to several hundred pieces of image data are input.

The first adder 33-1 adds image data output from the first group of line memories selected by the multiplexer 32 from the line memory groups 31-1--1-31-7. In this case, the image data obtained over several tens of main scanning lines that correspond to the same element of the one-dimensional image sensor 13 is added.

Similarly, in the second adder 33-2, the multiplexers 31-1 to 31-7 output the signals from the line memories 31-1 to 31-7.
In order to add the image data output from the line memory of the second group selected in step 2, the image data is continuous corresponding to the same element of the one-dimensional image sensor 13 at a certain point in time, and the first adder 33- The main scanning line to which the image data is added at 1 is the number 1 where the position in the sub-scanning direction is adjacent or separated
Image data obtained over 0 main scanning lines are added.

The thus obtained addition value from the first adder 33-1 and the addition value from the first adder 33-2 are subjected to a correlation operation by the correlator 34, and the correlation value is output. The correlator 34 is specifically configured by a subtractor or a divider.

The correlation value output from the correlator 34 is
In the same manner as in the first embodiment, for example, the presence or absence of a surface defect of the inspection object 10 is determined by being input to a determination unit 35 configured by a comparator and comparing with an appropriate threshold value TH. It is output as a surface condition inspection result.

According to the present embodiment, the image data input to the adder 33-1 and the adder 33 are affected by, for example, the thermal disturbance noise of the one-dimensional image sensor 13 and the ripple of the light source illuminating the inspection object 10. Even when the reference levels of the image data input to -2 are different, the difference of the reference levels is canceled in the course of the correlation operation of the correlator 34, and only the change of the image data corresponding to the defect is extracted. Thus, the defect can be detected more accurately.

(Fifth Embodiment) FIG. 7 shows a fifth embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration of an arithmetic processing device according to the embodiment. The arithmetic processing device 50 according to the present embodiment includes a two-dimensional memory array 51, a read control circuit 52, and an arithmetic processing block 53.

The digitized image data from the digital camera 11 shown in FIG. 1 is written into the two-dimensional memory array 51 for a plurality of continuous main scanning lines. The two-dimensional memory array 51 is a memory that can be read in arbitrary pixel units, unlike a normal line memory, and the position of a read pixel is controlled by a read control circuit 52. The image data read from the two-dimensional memory array 51 is input to the arithmetic processing block 53. The arithmetic processing block 53 performs processing corresponding to, for example, the adder 22 and the determiner 23 in FIG. 5, or the multiplexer 32, the adders 33-1 and 33-2, the correlator 34, and the determiner 35 in FIG. Things.

The read control circuit 52 performs a read operation so that image data is read from the two-dimensional memory array 51 in a read pattern corresponding to the inspection mode of the surface inspection according to an inspection mode signal given from a system controller (not shown). Controlled. There are basically two inspection modes (for convenience, a standard inspection mode and a special inspection mode). An inspection mode signal corresponding to these inspection modes is supplied to the read control circuit 52.

Specifically, in the case of the standard inspection mode, the read control circuit 52 performs a read operation equivalent to a plurality of line memories in which the two-dimensional memory array 51 is cascade-connected as in the third and fourth embodiments. The position of the read pixel of the two-dimensional memory array 51 is controlled so as to perform the above operation. As a result, similarly to the third and fourth embodiments, image data corresponding to input / output of each line memory is read out from the two-dimensional memory array 51 in the sub-scanning direction as shown by the oblique line 61 in FIG. The arithmetic processing is performed by the arithmetic processing block 53.

On the other hand, in the special inspection mode, the read control circuit 52 causes the two-dimensional memory array 51 to read image data from the two-dimensional memory array 51 in a direction oblique to the main scanning direction and the sub-scanning direction. Is controlled. That is, as shown by the oblique line 62 in FIG. 8, if the image data of the j-th pixel is read from the i-th main scanning line, the image of the j + 1-th pixel is read from the next i + 1-th main scanning line. data,
From the (i + 2) th main scanning line, the image data of the pixel at a position shifted by one pixel in the main scanning line direction is sequentially read out for each adjacent main scanning line, such as the image data of the (j + 2) th pixel. The arithmetic processing is performed by the processing block 53.

Here, taking as an example the case where the arithmetic processing block 53 is composed of the adder 22 and the determiner 23 as shown in FIG. 5, the adder 22 receives data from the two-dimensional memory array 51. The image data read in a direction oblique to the main scanning direction and the sub-scanning direction are added, and the added value is determined by the determiner 23. This special inspection mode is effective when inspecting oblique streak-like defects on the inspection object.

In the above description, the two-dimensional memory array 51
When image data is read in a direction oblique to the main scanning direction and the sub-scanning direction from, pixels at the reading position are shifted by one pixel in the main scanning direction between adjacent main scanning lines as shown by oblique lines 62 in FIG. However, it goes without saying that the amount by which the pixel at the readout position is shifted can be changed as appropriate, such as 2 pixels, 3 pixels, etc., and the direction in which the readout position is shifted is also set to the lower left in the example of FIG. It is also possible to go down to the right.

In each of the above embodiments, the case where a camera having a one-dimensional image sensor is used has been described. However, the present invention can be applied to a case where a camera having a two-dimensional image sensor is used.

[0063]

As described above, according to the present invention, the image data obtained by scanning the object to be inspected in the direction of the spatial axis by the camera having the image sensor is processed in the direction of the time axis. And inspecting the surface state of the inspection object, thereby removing the influence of the element variation of the one-dimensional image sensor and accurately inspecting the surface state such as the presence or absence of a defect on the inspection object. .

The present invention is effective for inspecting the surface of an object such as an extruded product, a drawn product, a roll product, and more specifically, for example, for mounting “H steel”, “pipe”, and electronic components. "Steel strip" made of stepped copper alloy used for
`` Cooling fins '' made of aluminum molding material applied to the heat radiating parts of various electronic devices, heat exchange parts of air conditioners, etc., `` Resin covers '' made of resin molded products for exposed mounting wires and pipes, "Flat cable" which is a parallel electric wire with a color code, "Foods" with a long cross section such as Naruto, Spaghetti, Kintaro candy, etc. "Belt", "Eraser", "Pile", "Rail", "Aluminum sash", "Insulator", "Aluminum wheel", "Corrugated sheet"
For example, it can be applied to surface inspection of various objects.

Of these, for example, a flat cable with a color code is a cable in which coated electric wires of different colors are integrated in parallel, and the brightness differs for each coating color, so that the main scanning direction (the direction of the spatial axis). Although the conventional inspection system which performs the arithmetic processing cannot perform the surface inspection, according to the present invention, the image data is arithmetically processed in the sub-scanning direction (the direction of the time axis), so that such a brightness difference for each color can be obtained. Surface inspection can be performed without being affected by the above.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a surface inspection system according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of image data output from a digital camera for explaining a basic principle of the present invention.

FIG. 3 is a block diagram showing a configuration of an arithmetic processing unit in a surface inspection system according to a second embodiment of the present invention.

FIG. 4 is a view showing a display example of an inspection result in the embodiment.

FIG. 5 is a block diagram showing a configuration of an arithmetic processing unit in a surface inspection system according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an arithmetic processing unit in a surface inspection system according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of an arithmetic processing unit in a surface inspection system according to a fifth embodiment of the present invention.

FIG. 8 is a view for explaining the operation of the embodiment;

[Description of Signs] 10 ... Inspection object 11 ... Digital camera 12 ... Imaging lens 13 ... One-dimensional image sensor 14 ... Amplifier 15 ... A / D converter 16 ... Processing unit 16-1 to 16-3 ... Processing unit 17, 17-1 to 17-3 N-line memory 18, 18-1 to 18-3 Correlator 19, 19-1 to 19-3 Judgment device 20 Arithmetic processor 21-1 to 21-3 Line memory 22 Adder 23 Judgment device 30 Arithmetic processing unit 31-1 to 31-7 Line memory 32 Multiplexer 33-1 33-2 Adder 34 Correlator 35 Judge 41 Small defect Defect image of 42... Defect image of normal defect 43... Defect image of uneven color defect 50... Processing unit 51... Two-dimensional memory array 52.

Claims (11)

[Claims] 1. A surface condition of an inspection object by subjecting image data obtained by scanning an inspection object in a direction of a spatial axis by a camera having an image sensor to a processing in a direction of a time axis. A surface inspection method characterized by inspecting a surface. 2. An object to be inspected is relatively moved in a sub-scanning direction orthogonal to the main scanning direction with respect to a camera having an image sensor configured by arranging a plurality of photoelectric conversion elements at least in the main scanning direction. A surface inspection method for inspecting a surface state of the inspection object by performing an arithmetic process on the image data output from the camera in the sub-scanning direction. 3. An image sensor comprising a plurality of photoelectric conversion elements arranged at least in a main scanning direction, wherein said image sensor is mounted on an inspection object which moves relatively in a sub-scanning direction orthogonal to said main scanning direction. A camera that scans in the main scanning direction and outputs image data, and an arithmetic processing device that performs arithmetic processing on the image data in the sub-scanning direction to obtain a surface state of the inspection object. Surface inspection system. 4. An N-line memory for storing image data of N consecutive main scanning lines (N is an arbitrary integer of 1 or more) outputted from the camera, and A correlator that calculates a correlation value between input and output image data, and a determiner that determines the magnitude of the correlation value output from the correlator and obtains an inspection result of the surface state of the inspection object. The surface inspection system according to claim 3, wherein: 5. An N-line memory for storing image data of N consecutive main scanning lines (N is an integer of 1 or more) outputted from the camera, and an arithmetic and logic unit for the N-line memory. A correlator for calculating a correlation value between input and output image data, and a determiner for determining a magnitude of the correlation value output from the correlator and obtaining an inspection result of a surface state of the inspection object. 4. The surface inspection system according to claim 3, comprising a plurality of arithmetic processing units having different values of N from each other. 6. The arithmetic processing unit comprises: a plurality of line memories for storing image data of a plurality of continuous main scanning lines output from the camera; and an image data output from the camera and the plurality of lines. An adder that adds image data output from the memory, and a determiner that determines the magnitude of the added value output from the adder and obtains an inspection result of the surface state of the inspection object. The surface inspection system according to claim 3, wherein 7. A line memory group for storing image data for a plurality of continuous main scanning lines output from the camera, and a plurality of a first group selected from the line memory group. A first adder for adding image data output from a line memory, a second adder for adding image data output from a plurality of line memories in a second group selected from the line memory group, A correlator for calculating a correlation value between the added values output from the first and second adders, and an inspection of the surface state of the inspection object by determining the magnitude of the correlation value output from the correlator. The surface inspection system according to claim 3, further comprising: a determiner for obtaining a result. 8. The surface inspection system according to claim 4, wherein the correlator is a subtractor or a divider. 9. The apparatus according to claim 3, wherein said determination unit obtains an inspection result of a surface state of said inspection object by comparing an input correlation value with a predetermined threshold value.
8. The surface inspection system according to claim 1. 10. An image sensor comprising a plurality of photoelectric conversion elements arranged at least in a main scanning direction, wherein said image sensor is mounted on an inspection object which moves relatively in a sub-scanning direction orthogonal to said main scanning direction. A camera that scans in the main scanning direction and outputs image data, a first inspection mode in which arithmetic processing is performed on the image data in the sub-scanning direction to determine a surface state of the inspection object, On the other hand, an arithmetic processing unit having a second inspection mode for obtaining a surface state of the inspection object by performing arithmetic processing in a direction oblique to the main scanning direction and the sub-scanning direction is provided. Surface inspection system. 11. The arithmetic processing unit has a two-dimensional memory array for storing image data of a plurality of continuous main scanning lines output from the camera, and the first and second memory arrays are stored in the two-dimensional memory array. 11. The surface inspection system according to claim 10, wherein the image data is read in a read pattern according to the second inspection mode, and the read image data is subjected to an arithmetic processing.