JP6508763B2 - Surface inspection device - Google Patents

Description

  The present invention relates to a surface inspection apparatus, for example, an apparatus for inspecting a defect present on the surface of a product or part.

  2. Description of the Related Art It is performed inspection using an image captured by a camera whether a surface of a product or part has a defect such as a scratch or a foreign substance attached thereto. In this case, the surface is illuminated to make it easy to see defects, and an area camera or a line camera is used to image the inspection object.

  In addition, imaging by a line camera incorporating a line sensor (an imaging device in which light receiving elements of one pixel are arranged in a line shape) has a cylindrical surface, an elongated plate, and a sheet other than high resolution and wide field of view at high speed. When an object such as is moved in synchronization with a camera and continuously imaged, or a high directivity (the reflected light of the illumination is not diffused and the direction of reflection is limited, for example, It is used when imaging the surface of the metal member finished smooth).

By the way, when a surface defect is confirmed by an image, depending on the direction of the light and the shape of the defect, it may be difficult to see from a certain direction, but it may be seen well from different directions.
For example, when illumination is directed toward a highly directional inspection object and a wide area is imaged by an area camera, for example, a gently inclined uneven defect etc. has high directivity, so it is only within a limited range in the screen. Can only be taken. In addition, when using a line camera, it is possible to capture a wide range of images by moving the workpiece while capturing a limited range of images, but since the direction in which imaging is easy varies depending on defects, one camera I can not check it.
In order to cope with this case, it is necessary to install a plurality of line cameras so as to image the surface to be observed from different angles, or to switch the illumination and image a plurality of times.
However, when mounting a plurality of line cameras or switching the illumination to capture an image, there is a problem that the structure of the apparatus becomes complicated and the cost increases.
In the "defect inspection method and apparatus thereof" of Patent Document 1, two or one line camera for surface defect inspection and one line camera for internal defect inspection are used while moving the inspection object on its surface. Although a surface defect inspection and an internal defect inspection are simultaneously performed by obtaining a two-dimensional image by a camera in which a plurality of line sensors are mounted in the camera, the surface defect is inspected using reflected light from the surface A line sensor and a line sensor for inspecting internal defects using light transmitted from the surface to the inside are provided, and reflected light on the surface of the inspection object is not observed from different angles.

Japanese Patent Application Laid-Open No. 9-304297

  An object of the present invention is to provide a surface inspection apparatus capable of surface inspection with a simple structure.

(1) In the invention according to claim 1, a plurality of illumination means for separately illuminating the first predetermined area and the second predetermined area of the cylindrical surface inspection object, and an imaging device capable of selecting a plurality of imaging areas. When an image of the illuminated said first predetermined area and the second predetermined region was a projection means for projecting the image pickup device, from each of the said imaging device projected the first predetermined area a second predetermined region a selecting means for selecting an imaging area of a line shape extending in the axial direction of the surface inspection object, a moving means for moving the surface inspection object, relative movement speed of the surface inspection object get the surface image of each imaging area which is the selected in synchronism with, prior Symbol selected imaging each region, an image acquisition means for constructing a two-dimensional image from the acquired image, the two-dimensional and the construct From the image said surface inspection pair Comprising detection means for detecting a defect on the surface of the object, wherein the plurality of illumination means, wherein are arranged the line shape along a direction perpendicular to the imaging region of a surface inspection device, characterized in that I will provide a.
(2) In the second aspect of the present invention, the plurality of illumination means may be equal to the first predetermined area, in which the distances from the virtual line on the surface inspection object which is the shortest distance from the imaging device are equal. The surface inspection apparatus according to claim 1, wherein the second predetermined area is separately illuminated .
(3) In the third aspect of the present invention, the illumination means may include at least one of the first predetermined area and the second predetermined area along a line direction of the line-shaped imaging area. It illuminates from a different direction, The surface inspection apparatus of Claim 1 or Claim 2 characterized by the above-mentioned.
(4) In the invention according to claim 4 , the surface inspection apparatus according to claim 1, 2 or 3 , wherein the imaging regions of the respective line shapes are parallel to each other. provide.
(5) In the invention described in claim 5, wherein the selection means, the imaging area of one or more of the line shape with respect to each of the first predetermined area and the second predetermined region of the surface inspection object selecting, to provide a surface inspection apparatus according to any one of claims of claims 1 to 4, characterized in that.

  According to the present invention, the surface inspection apparatus can be made into a simple structure.

It is a figure for demonstrating a surface inspection apparatus. It is a figure for demonstrating an example of an image. It is a figure for demonstrating the case where the unevenness of moderate inclination is formed as a defect. It is a figure for demonstrating the example which set the imaging region of line shape according to the shape of the surface. It is explanatory drawing in the case of illuminating simultaneously the line used as several imaging object by one illumination. It is explanatory drawing in the case of illuminating several predetermined area | regions using several illumination. It is explanatory drawing in the case of illuminating from one direction with respect to one predetermined area | region with several illumination.

(1) Outline of Embodiment The camera 3 (FIG. 1A) is a CMOS area camera having a sufficient number of pixels for imaging a workpiece or a defect.
The camera 3 can select a plurality of arbitrary regions among light receiving elements (pixels) two-dimensionally integrated on the imaging device of the area sensor 6, and can read an image by the selected region (WOI described later) function).

  Then, in the surface inspection apparatus 1, only the image of the line to be imaged is read by setting the area to be imaged to a plurality of line shapes in the imaging device of the area sensor 6 by the WOI function. As a result, the area sensor 6 can have the same function as virtually configuring a plurality of line cameras. In addition, since the amount of image data to be read is reduced, high speed reading can be performed. Depending on the directivity of the defect, etc., it is also possible to widen the line width for imaging.

When illumination from different angles is required, a single illumination 2 illuminates a predetermined area corresponding to the positions of a plurality of line-shaped imaging areas specified, and the lines to be imaged differ from the illumination Because of the positional relationship, imaging with different illumination conditions can be performed for each line.
If it is necessary to make a difference in illumination conditions beyond this, prepare a plurality of illuminations 2a, illuminations 2b, ..., illuminate predetermined areas under different conditions, and set lines to be imaged in each predetermined area .

Alternatively, the same surface may be illuminated with a plurality of illuminations 2a, illuminations 2b,..., And line-shaped imaging regions may be set at locations corresponding to the portions.
In order to inspect a highly directional uneven defect, it is effective to apply rectangular illumination and provide a plurality of lines to be imaged. In the case of imaging a cylindrical object, a line to be imaged is designated within a range in which the object is in focus.

When taking an image, the image is acquired while synchronizing the image capturing speed and the movement of the object, as in the conventional imaging technology with a line camera. Thereby, images of a plurality of imaging locations can be obtained simultaneously.
When capturing an image, the computer 4 connects the acquired line-shaped images to create a two-dimensional image for each imaging region.

As described above, when the surface inspection apparatus 1 is used, it is possible to obtain an image equivalent to a state in which a plurality of line cameras are installed at different positions by a single camera 3 having a WOI function.
As a result, high-speed imaging equivalent to installing a plurality of line cameras can be performed with a simple configuration, and images can be efficiently obtained.
And if this technique (technology which comprises a plurality of line cameras with area sensor 6) is used, an uneven defect which imaging in one direction is difficult can be simultaneously imaged from a plurality of directions.

(2) Details of the Embodiment Each drawing of FIG. 1 is a diagram for describing a configuration of the surface inspection apparatus according to the present embodiment and a mechanism for detecting a defect on the surface.
FIG. 1A is a view for explaining the configuration of the surface inspection apparatus.
The surface inspection apparatus 1 is configured using the illumination 2, the camera 3 incorporating the area sensor 6, the computer 4, the drive device 5 and the like.
The illumination 2 functions as an illumination unit that illuminates a predetermined area (surface) of the surface inspection target, and is, for example, an illumination device that illuminates the surface to be inspected of the workpiece 15 from one direction.

  There are various illumination methods by the illumination 2, but in the present embodiment, a predetermined area is illuminated by rectangular illumination. Illumination such as parallel light or diffused light is used according to the reflection of the surface of the inspection object and the characteristics of the illumination.

  Although not shown, the illumination 2 is fixed to the surface inspection apparatus 1 and illuminates the surface of the workpiece 15 at a predetermined brightness and a predetermined angle and distance. The adjustment of the angle and the distance can be performed by the worker for each work 15 while looking at the image with the camera 3.

The camera 3 is fixed to the surface inspection apparatus 1 toward the illuminated area of the workpiece 15 and projects an image of the surface of the workpiece 15 on a complementary metal oxide semiconductor (CMOS) area sensor 6 and the area sensor 6 Area camera comprising an optical system for imaging.
The camera 3 can designate an arbitrary area of the imaging device of the area sensor 6 and selectively read out the image projected on the area. This function is called WOI (Windows Of Interest).

The optical system of the camera 3 is configured by combining a plurality of lenses and a focus adjustment mechanism that adjusts the positional relationship to adjust the focus, and the like, and projection means for projecting an image of the illuminated surface onto the imaging surface Acts as.
A commercially available product (for example, CSC12M25BMP19 made of Toshiba Terry's 12 million pixel CMOS camera) can be used as the camera 3, whereby cost reduction can be achieved.

The area sensor 6 is an imaging device in which a plurality of light receiving elements (pixels) are integrated on a plane, and converts an image projected and formed on the surface into an electrical image signal.
Usually, the line camera can capture only the image on the line, but the area sensor 6 can image the area of the surface of the workpiece 15 in the area mode (mode for reading the entire projected two-dimensional image). Therefore, the operator can adjust the positions and angles of the illumination 2 and the camera 3 while viewing the image, so that the adjustment is easy.

In the surface inspection apparatus 1, as shown in FIG. 1 (b), an image is read out from the imaging region of the line shape at the position of the line A and the line B in the imaging device of the area sensor 6.
Of the imaging devices of the area sensor 6, the imaging line A on the workpiece 15 shown by the dotted line in FIG. 1 (a) and the imaging line are shown by the line-shaped imaging areas located on line A and line B in FIG. Image B.

Then, the surface of the inspection target (workpiece 15) is relatively moved in the direction of the arrow P (direction intersecting with the lines A and B).
When the image of each imaging line A and imaging line B is read in synchronization with this relative movement and a two-dimensional image is generated for each line, the two-dimensional image of the entire surface corresponding to line A and line B correspond. A two dimensional image of the entire surface is obtained.
The slide in the direction of the arrow P in the inspection target is performed by moving at least one of the inspection target and the camera 3 relative to the other. However, when the camera 3 is moved, the illumination 2 is also moved synchronously as necessary (for example, when the illumination is limited to the imaging line A and the periphery of the imaging line B).

A two-dimensional image of the entire surface of the inspection object read at line A is referred to as an image A, and a two-dimensional image of the entire surface of the inspection object read at line B is referred to as an image B.
Line A and line B are parallel positions. This facilitates the correspondence between the image A and the image B. For example, when it is desired to combine the image A and the image B, the relative distance between the line A and the line B may be corrected and then combined.

  The operator operates the area used for imaging from the computer 4 and sets the line A and the line B at an arbitrary position, or sets more lines C, D,... Can.

That is, by using the WOI function, it is possible to set an area of an arbitrary line shape from the surface of the area sensor 6 and pick up an image at a plurality of corresponding positions.
Therefore, the operator can set the most suitable line in the area sensor 6 in accordance with the work 15.
As described above, the WOI function functions as a selection unit that selects a plurality of lines of the imaging device on the imaging surface.

  In the surface inspection apparatus 1, a plurality of line cameras are virtually configured on a single area sensor 6 by setting an arbitrary line in the area sensor 6, and the line camera illuminates it from one direction with the illumination 2, Such a configuration is particularly effective when the surface of the work 15 has directivity.

For example, FIG. 1C shows the case where the work 15 is metal and the surface 20 is flat. In this case, the incident angle of the incident light 21 by the illumination 2 and the reflection angle of the reflected light 22 become equal. Arrows indicate the traveling direction of light.
In this case, when the surface is viewed from a direction 24 (specular reflection direction) in which the reflected light 22 is seen, the entire surface glows and appears bright, and when the surface is viewed from a direction 23 different from the reflected light 22, the surface appears dark.

Further, as shown in FIG. 1D, when there is a deep concave defect 25 on the surface, in the concave defect 25, the direction of the reflected light 26 is different from that of the reflected light 22 (not shown).
In this case, when the surface is viewed from the direction 24, the reflected light 26 does not reach the direction 24, so the portion of the concave defect 25 appears dark and the other normal portions appear bright. On the other hand, when the surface is viewed from the direction 27 of the reflected light 26 at the concave defect 25, the portion of the concave defect 25 appears bright and the other normal portions appear dark.

Furthermore, when there is a gently inclined concave defect 28 on the surface of FIG. 1 (e), the reflected light at the concave defect 28 becomes almost the same as the reflected light 22 at the normal part, and viewed from the direction 24 Looks bright and it is difficult to tell the difference from the normal part.
In this case, although not shown, since light is scattered at a weakly inclined portion, when the image is taken from a position deviated from the regular reflection direction, the portion of the inclination looks bright (or dark) by scattered light and the concave defect 28 is identified. be able to.

Although the concave defect has been described above, the same applies to a convex defect (for example, when a protrusion or a foreign substance is attached).
As described above, in the case of a material with high directivity of reflected light, the reflected light is directed in a specific direction, and defects are found when the surface is photographed using a plurality of line cameras illuminated from one direction and located at different positions. The probability can be increased, and the reliability of the test result can be improved.

Referring back to FIG. 1A, the computer 4 is configured using a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a storage device, an interface, and the like.
The CPU performs various information processing and control in accordance with a program stored in a storage device or the like. In the present embodiment, for example, the program stored in the storage device is executed by the CPU to form the image generation unit 7, the image recognition unit 8, and the drive control unit 9.

The ROM is a read only memory, and stores basic programs and parameters when the computer 4 operates.
The RAM is a readable and writable memory, and provides a working memory when the CPU operates.
The storage device is configured using a storage medium such as a hard disk, and stores programs for operating the computer 4 and image data.

The interface is a connection device that connects the computer 4 to the camera 3 and the drive device 5 by signal lines, and the computer 4 communicates with the camera 3 and the drive device 5 via the interface.
As a result, the computer 4 can receive image data for each line from the camera 3 for the camera 3 or set a line for reading an image on the area sensor 6. The operation of the drive device 5 can be controlled.

Although not shown, a keyboard, a mouse, a monitor screen and the like are also connected to the interface.
On the monitor screen, the operation screen of the surface inspection apparatus 1 (setting of lines on the area sensor 6, etc.), an image received from the camera 3, inspection results, etc. are displayed. The operations required for surface inspection can be performed.

The image generation unit 7 receives the image data read by the line A and the line B of the area sensor 6 from the camera 3 and combines them individually into a two-dimensional image to obtain individual image data for each of the line A and line B ( Generate an image A, an image B). The generated image data is stored in a RAM, a storage device, or the like.
As described above, the image generation unit 7 acquires an image (surface image) for each line to be an imaging target projected onto the line-shaped imaging area in synchronization with the movement of the work 15 and synthesizes a two-dimensional image. It functions as an image acquisition means.

  The positions corresponding to the line A and the line B are indicated by broken lines in the work 15 in the drawing. As shown in the figure, since the angles at which the line A and the line B are captured from the camera 3 are different, by reading the images at the line A and the line B, images (image A and image B) viewed from different angles are obtained. be able to.

The image recognition unit 8 recognizes a defect existing on the stored image A and the image B, and determines whether or not the surface of the workpiece 15 has a defect. The image recognition unit 8 outputs the determination result on a monitor screen or the like.
For example, when a defect is found in at least one of the image A and the image B, the image recognition unit 8 determines that there is a defect.

As a result, even if a defect can not be found in one of the images due to light addition or subtraction, a defect can be found in the other image, or the accuracy of defect determination can be improved by combining the respective images. The image recognition method is similar to that of the conventional one.
As described above, the image recognition unit 8 functions as a detection unit that detects a surface defect based on the image of each line to be imaged which is acquired by the area sensor 6.

The drive control unit 9 can control the rotation start / end, the rotation direction, the rotation speed, and the like of the drive device 5 according to an instruction from the computer 4.
By this rotation operation, the camera 3 can obtain a two-dimensional image from the surface of the workpiece 15 at line A and line B.
The drive control unit 9 functions as a moving unit that moves the surface of the workpiece 15 relative to the illumination unit and the imaging device relative to the line-shaped imaging region selected by the line in the surface.

  The work 15 is, for example, an axis of a precision machine made of metal, and is held at a predetermined position of the surface inspection apparatus 1 by a holding mechanism (not shown). The holding mechanism can rotate the work 15 around the axial center by the drive device 5.

In the present embodiment, the work 15 is a cylindrical member, but this is merely an example, and various shapes such as a flat member (for example, an end face of a gear) or a tapered member can be used.
In any case, a two-dimensional image can be obtained from the image of the surface at line A and line B by moving the inspection surface in one direction in the plane to which the surface belongs.

In the surface inspection apparatus 1 configured as described above, the surface inspection is performed as follows.
First, the worker fixes the work 15 to the holding mechanism, applies rectangular light from the light 2, and adjusts the position, direction, brightness, etc. of the light 2 while looking at the light condition.
Next, the operator sets the camera 3 in the area mode and installs the camera 3 in the direction in which light is reflected while viewing the image of the work 15 by the camera 3 from the monitor screen.
Then, the operator sets lines A and B at appropriate positions while watching the image of the work 15 and drives the drive device 5 and the camera 3 to cause the computer 4 to perform an inspection.

If the surface of the work 15 has an uneven defect, the inclination direction of the uneven defect changes the direction in which light is reflected, and in the regular reflection direction, the defect appears dark relative to the normal surface. The computer 4 detects a defect by recognizing these changes.
When the inclination of the uneven defect is gentle, the difference in brightness of the defect becomes small and the difference from the periphery becomes difficult to take, but the defect is also recognized by line A or line B at a position slightly deviated from the regular reflection direction.

Each figure of FIG. 2 is a figure for demonstrating an example of the image A and the image B. FIG.
FIG. 2A is a view showing an imaging surface of the area sensor 6.
An image 16 of the workpiece 15 illuminated by the illumination 2 is formed on the imaging surface of the area sensor 6. The image 16 is moved by the driving device 5 in the arrow direction at a constant speed.
In the area sensor 6, two lines A and B parallel to each other are set, and two parallel line-shaped imaging regions are configured by imaging devices located in these lines.

Then, the image 16 is read by the line A and the line B in synchronization with the movement of the image 16, and when the read image is synthesized, the image A and the image B are obtained.
The image 17 of the defect projected onto the image 16 also moves with the image 16, is read at line A, line B, and is recorded in image A, image B.

FIG. 2B shows an example of the image A.
In the image A, the image 17 of the defect appears dark with respect to the bright surface, and it can be easily determined as a defect by image recognition.
FIG. 2C shows an example of the image B.
In the image B, the image 17 of the defect is also brightly reflected on the bright surface, and image recognition is more difficult than the image A.
As described above, since the image 17 of the defect has different brightness from the normal surface depending on the viewing angle, it is possible to ensure the detection of the defect by capturing an image on the line A and the line B with different imaging positions. it can.

Each figure of FIG. 3 is a figure for demonstrating the case where the unevenness | corrugation of a gentle inclination is formed as a defect on the surface of test object.
FIG. 3A is a view showing a cross section of the workpiece 15 and an image A corresponding thereto. The image A is an image obtained by copying the surface of the work 15 from the regular reflection direction.
On the surface of the work 15, a defect due to the gently inclined recess 18 is formed.
Most of the reflected light from the recess 18 is reflected in the same direction as the normal surface, so in the image A taken from the regular reflection direction, the image 19 of the recess is as bright as the normal surface and difficult to distinguish. There is.

FIG. 3B is a view showing a cross section of the workpiece 15 and an image B corresponding thereto. The image B is an image taken from the position where the surface of the work 15 is shifted from the regular reflection direction.
Since the image B is photographed from the position shifted from the regular reflection direction with respect to the image A, the normal surface appears dark, while the sensitivity of the unevenness of the recess 18 in the image is high, the contrast is improved, and the inclined portion Is clearly visible, so that the image 19 of the recess can be clearly projected.
In the illustrated example, the left side of the concave image 19 appears brighter than the normal surface, and the right side appears darker than the normal surface.

As described above, shallow defects or gently inclined uneven defects formed on the surface of a highly directional work may not show shallow defects or gently inclined uneven defects due to directivity when imaged from only one direction. Because there are, it is effective to image from multiple directions.
By the way, in the case of a minute defect such as a precision part, the difference in relative imaging position is slight. The imaging studies by the present inventors were smaller than 1 mm and very small relative to the size of the camera.

Thus, when the difference in imaging position is close, it is impossible to install a plurality of line cameras in a close position, so a plurality of line sensors in a single area sensor 6 as in the surface inspection apparatus 1 The method of constructing is particularly effective.
If a plurality of line cameras are to be used, it is necessary to move the camera or the illumination and then to perform imaging a plurality of times. In this case, the imaging time becomes long, which is not practical.

In addition, although it is conceivable to provide a plurality of imaging systems and install the camera and the illumination respectively, the positional relationship becomes indeterminate by changing the holding of the work, so that each image is combined or the number of defects is accurately determined. There is a drawback that it is difficult to count. In addition, the scale of the device also increases.
Furthermore, although it is conceivable to take an image taken from one optical system using a line camera equipped with a plurality of line sensors, there is also a need to independently manufacture a dedicated camera, and in addition to illumination, objects, There is a problem that it is difficult to adjust the settings of the camera.
On the other hand, in the surface inspection apparatus 1, a plurality of line sensors in proximity to the area sensor 6 can be easily configured by the operation of the computer 4.

FIG. 4 is a diagram for explaining an example in which the lines A to C are set in accordance with the shape of the surface.
An image 16 of the work 15 is projected on the area sensor 6. Since the surface of the work 15 is a cylindrical surface, it is represented by a bright part 31 (regular reflection direction) by the illumination 2, a slightly dark part 32, 33 (part slightly deviated from the regular reflection direction) represented by oblique lines, and a wavy line. Dark portions 34, 35 are formed.

The operator selects the line of the imaging device corresponding to the brightest position (the position of regular reflection) and the both sides (the position shifted from the regular reflection) while checking the image on the monitor screen of the image 16.
Here, the line B of the bright portion 31 is set, the line A and the line C are set in the slightly dark portions 32 and 33, and the line B is positioned at the center of the line A and the line C.

Since the camera 3 uses the area sensor 6, it is convenient for adjusting the position of the illumination 2 while checking the image of the actual object in this way, and for selecting the position of the line to be taken. That is, the line sensor can be set according to the actual item while confirming the actual item.
As described in FIG. 3, even if the defect is not noticeable in the line B located in the regular reflection direction, there is a possibility that the flaw can be found in the lines A and C at a position slightly shifted from the regular reflection direction. high.

FIGS. 4B, 4C, and 4D show examples of the image A, the image B, and the image C taken at line A, line B, and line C, respectively.
In the image A, the contrast of the image 41 of the defect of the recess is high, and detection of the defect is easy.
In the image B, the image 41 of the defect of the concave portion clearly shows the image 42 of the dirt defect attached to the surface of the unclear one, and can be easily detected as the defect.
In the image C, both the image 41 of the defect of the recess and the image 42 of the dirt defect are unclear.
As described above, by capturing images with lines set at a plurality of positions with respect to the regular reflection direction, it is possible to cope with a plurality of defects having unique reflection characteristics, and to increase the probability of finding defects. .

Next, the illumination method and the number of illuminations of the workpiece 15 by the illumination 2 will be described.
FIG. 5 is an explanatory view in the case of simultaneously illuminating a plurality of line areas by one illumination.
As shown in FIG. 5A, one illumination 2 illuminates a predetermined area 51a including a plurality of lines (lines A to C in the figure) on the cylindrical surface of the work 15.

Then, although the predetermined area 51a is illuminated by one illumination 2 (with the same light source), as shown in FIG. 5B, in the image 16 captured by the area sensor 6, each line A in the predetermined area 51a Lines A to C in the predetermined area 51b corresponding to C are set.
Therefore, a point Q (not shown) on the workpiece 15 is imaged at different angles on the three lines A to C as the workpiece 15 moves relative to each other. For this reason, it becomes possible to detect the various defects mentioned above by carrying out image processing of the two-dimensional picture of each work 15 obtained corresponding to each line A-C by relative movement of the work 15.
Although three lines A to C are targeted in FIG. 5, two lines A and B may be targeted, and four or more lines may also be targeted. This point is the same as in the case of setting a plurality of lines in a predetermined area illuminated by the same light source.

FIG. 6 is an explanatory view in the case of illuminating a plurality of predetermined areas using a plurality of illuminations.
FIG. 6A shows an example in which one predetermined area 52a of the cylindrical surface of the work 15 is illuminated with the illumination 2a, and the other predetermined area 53a is illuminated with the illumination 2b.
Thereby, the predetermined area 52a on the illumination 2a side of the surface of the work 15 and the predetermined area 53a on the illumination 2b side are individually illuminated.
A plurality of lines A to C are set for the predetermined area 52a, and one line D is set for the predetermined area 53a.

  In addition, since the image 16 by the area sensor 6 images the areas 52b and 53b corresponding to the plurality of predetermined areas 52a and 53a, when assuming the virtual line R on the shortest distance between the area sensor 6 and the work 15, The distance r from the imaginary line R to the line D and the distance r from the line A (or line B or C) are set to be equal. This is to make the area sensor 6 focus on both the predetermined area 52a and the predetermined area 53a because the cross section of the work 15 is circular.

As shown in FIG. 6A, the predetermined area 52a illuminated by the illumination 2a is set to be narrower than in the case of FIG.
Then, as shown in FIG. 6B, the central line B is set at the center of the area 52b photographed corresponding to the predetermined area 52a, and the lines A and C on both sides are closer to the center of the area 52b. It is set to both ends that are dark. As a result, defects are easily seen on the surface image corresponding to the lines A to C.

FIG. 7 is an explanatory view in the case of illuminating one predetermined area from a plurality of directions by a plurality of illuminations.
As shown in FIG. 7A, a line D is set in a predetermined area 54a. A predetermined area 54a is illuminated by the two illuminations 2b1 and 2b2 disposed along the direction of the line D.
By illuminating with illumination 2b1 and illumination 2b2 from both sides along the direction of line D in this manner, a defect having directivity in the direction intersecting the captured image obtained by the illumination of lines A, B, and C can be obtained. It can be projected on an image.
The illumination 2a1 and the illumination 2a2 may be disposed along a direction perpendicular to the line direction.

The predetermined area 52a in which the plurality of lines A to C are set and the illumination 2a of the area are the same as those in FIG.
The illumination 2a1 and the illumination 2a2 may be arranged along the line direction also in a predetermined region 52a (both in the case of FIG. 6 and in the case of FIG. 7) in which a plurality of lines A to C are set.
Furthermore, the illumination 2a1 and the illumination 2a2 may be arranged along the direction perpendicular to the line direction.

As described in FIGS. 5 to 7, the surface to be inspected can be illuminated with one or more illuminations on each of the given regions, assuming one or more given regions.
And one or a plurality of lines can be set in each predetermined area.

The illumination 2a and the illumination 2b can set not only the illumination direction but also the brightness and the color of light separately.
Thus, there are a plurality of illumination means and can illuminate the surface from different directions. Furthermore, the plurality of illumination means illuminate different surfaces that are subject to image acquisition by the selected line.

The following modifications can be made to the surface inspection apparatus 1 described above.
In the present embodiment, the illumination 2 and the camera 3 are fixed and the work 15 is moved. However, these may be moved relative to each other, and the work 15 may be fixed and the illumination 2 and the camera 3 may be moved.
The illumination 2 is illuminated with white light, but may be illuminated with a combination of monochromatic light and some monochromatic light. This example is effective when the reflection characteristics of the defect differ depending on the wavelength of light.
Furthermore, it is also possible to polarize the light which the illumination 2 illuminates. This is effective when the polarization plane of the reflected light is different between the surface and the defect. In this case, a polarization filter is attached to the optical system of the camera 3.

According to the surface inspection apparatus 1 described above, the following effects can be obtained.
(1) A plurality of line-shaped imaging regions can be configured at arbitrary positions in the area sensor 6 having the WOI function by simple operation of the computer 4.
(2) By configuring the line-shaped imaging region in the area sensor 6, it is possible to virtually configure a plurality of line sensors at close positions which can not be configured by a plurality of line cameras.
(3) Since the imaging is performed from a plurality of positions, it is possible to image the uneven surface of the object to be inspected with high directivity.
(4) Since the positional relationship between a plurality of lines is known and images are read in synchronization with the movement of the work 15, it is possible to link the positional relationships between the images such as the image A and the image B, and illumination conditions differ. The differences when the images are acquired can be compared between the images.
(5) It is possible to obtain an image equivalent to a state in which the positions of a plurality of line cameras are shifted and installed by one commercially available inexpensive CMOS area camera that is easy to obtain and has sufficient operating software It is.
(6) The surface inspection apparatus 1 can be used to perform high-speed imaging equivalent to that of a line camera.
(7) It is possible to take an image with different illumination conditions with one camera 3 depending on the position of the line.
(8) The camera 3 can also be used as an area camera, which facilitates installation and adjustment of the equipment.
(9) Equipment investment costs can be reduced.

DESCRIPTION OF SYMBOLS 1 surface inspection apparatus 2, 2a, 2b illumination 3 camera 4 computer 5 drive device 6 area sensor 7 image generation part 8 image recognition part 9 drive control part 16 image 17 defect image 18 recessed part 19 recessed part image 20 surface 21 incident light 22 Reflected light 23, 24 direction 25 concave defect 26 reflected light 27 direction 28 concave defect 31 bright part 32, 33 slightly dark part 34, 35 dark part 41 image of defect of concave part 42 image of dirt 51, 52, 53 predetermined area

Claims (5)

A plurality of illumination means for separately illuminating the first predetermined area and the second predetermined area of the cylindrical surface inspection object;
An imaging device capable of selecting a plurality of imaging regions;
Projection means for projecting the image of the illuminated first predetermined area and second illuminated area onto the imaging device;
From each of the said first predetermined area projected on the image pickup device second predetermined region, and selecting means for selecting an imaging area of a line shape extending in the axial direction of the surface inspection object,
Moving means for relatively moving the surface inspection object;
Get the surface image of each imaging area which is the selected in synchronism with the relative movement speed of the surface inspection object, before Symbol selected imaging each region, to construct a two-dimensional image from the acquired image An image acquisition means,
Detection means for detecting defects on the surface of the surface inspection object from each of the constructed two-dimensional images;
Equipped with
The surface inspection apparatus according to claim 1, wherein the plurality of illumination units are disposed along a direction orthogonal to the line-shaped imaging region .   The plurality of illumination units illuminate separately the first predetermined area and the second predetermined area, in which the distances from the virtual line on the surface inspection target which is the shortest distance from the imaging device are equal.
The surface inspection apparatus according to claim 1, characterized in that:   The illumination unit illuminates at least one of the first predetermined area and the second predetermined area from a plurality of different directions along a line direction in the line-shaped imaging area.
The surface inspection apparatus according to claim 1 or 2, characterized in that: The line-shaped imaging areas are parallel to one another.
The surface inspection apparatus according to claim 1 , 2 or 3 characterized in that. It said selection means selects the image capturing area of one or more of the line shape with respect to each of said first predetermined region of the surface inspection object and said second predetermined area,
The surface inspection apparatus according to any one of claims 1 to 4 , characterized in that:

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