JP3135075B2 - Appearance inspection method and apparatus, magnetic head inspection method and apparatus, and magnetic head manufacturing facility - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection object, for example, whether a thin film magnetic head used in a magnetic disk device for a large computer or the like has a defect or foreign matter, and whether the defect or foreign matter exists. In the case where a defect is detected, a defect and a foreign substance can be detected in a distinguished state, and a visual inspection method and a device thereof. The present invention relates to a magnetic head manufacturing facility provided with a magnetic head inspection device at a final stage on a head manufacturing line.

[0002]

2. Description of the Related Art A thin-film magnetic head main body is assumed as an appearance inspection target in which a concave defect or a convex foreign substance may be present on the surface. One or more edges are formed on the surface of the thin-film magnetic head main body so that rail surfaces are formed in the same direction. Chips and voids are formed as concave defects on the edge portions and the flat surface (rail surface). However, since these concave defects have a significant effect on the flying characteristics of the thin-film magnetic head body on the surface of the magnetic disk, it is strictly necessary to determine whether these concave defects have occurred at the final stage on the production line. It is something that needs to be inspected.

Here, the thin-film magnetic head will be described. FIGS. 11A and 11B show the entire thin-film magnetic head and the main body of the thin-film magnetic head, respectively. The thin-film magnetic head body is movable in the radial direction of the magnetic disk while facing the surface of the magnetic disk, and floats on the surface of the magnetic disk while maintaining a small gap by the high-speed rotation of the magnetic disk itself. While reading the information recorded on the magnetic disk, the information is recorded on the surface of the magnetic disk. As shown in FIG. 1B, the magnetic head main body is provided with a magnetic head element 9 and a rail surface 10 for giving a floating force to the magnetic head main body itself.
There is a possibility that a concave defect often occurs at the upper portion or the longitudinal edge of the rail surface 10. FIG. 12A shows a thin-film magnetic head in which a chip 11 or a void 12 exists as a defect, and FIGS.
FIG. 12D shows a line AA ′ in FIG.
The vertical cross-sections taken along the line BB 'and the line CC' are also shown. As can be seen from FIGS. 12B to 12D, the chip 11 and the void 12 are present as concave defects. It has become. Among these concave defects, the defect due to the chip 11 is particularly likely to occur. This is because the thin-film magnetic head body is configured as a sintered body such as a ceramic, but when a large external force is applied to the edge, a crack is generated at a part of the edge and this is separated as a fragment, which is As a result, chipping 11 occurs. Chip 1
If the shape and dimension 1 exceed a certain size, the flying characteristics of the magnetic head main body are greatly affected, so the chip 11 must be strictly detected as a defect. Also, if the cavity inside the material formed when sintering the ceramic is exposed on the surface by cutting etc.,
A depression is formed on the rail surface 10, and the depression is referred to as a void 12. If the shape of the void 12 becomes large, the presence or absence of a defect is determined as a defect for the same reason as the chip 11 in the final manufacturing stage. Strict inspection.

As described above, it is necessary to inspect whether or not a defect exists on a thin-film magnetic head. However, a technique for detecting a defect in a magnetic head has not been known so far. The following paper describes the technology. A method of detecting chips and voids by imaging and detecting an image of an inspection target for each of bright-field illumination and dark-field illumination, which are ordinary microscope illumination methods, is processed. E Transactions on Pattern Analysis and Machine Intelligence, Vol. 10, No. 6, 1988, pp. 830-848 (IEEE Transactions on Pattern
Analysis and Machine Intelligence, Vol. 10, No. 6, (19
88) pp830-848) “Machine Vision Algorithm for Automated Inspection of Sin-Film Disk Head” (Machine
Vision Algorithms for Automated Inspection of Thin
-Film Disk Head). When an image is captured by bright-field illumination, the reflected light is specularly reflected on the normal rail surface, whereas if a chip or void exists as a concave defect on the rail surface or its edge, In the concave defect, the reflected light is scattered, and the entire concave defect area is detected as dark. On the other hand, when an image is captured by dark-field illumination, reflected light that is specularly reflected on a normal rail surface is not detected, but scattered reflected light from a concave defect is detectable. The entire defect area is detected brighter than the normal rail surface. Therefore, by utilizing such a difference in reflected light due to such a difference in illumination method, a chip or a void can be detected as a defect.

[0005]

By utilizing the technique described in the above-mentioned paper, chips and voids existing on the thin-film magnetic head can be detected as concave defects. By the way, usually, it is inevitable that a convex foreign substance such as dust adheres to the inspection object. Since the surface shape of the convex foreign substance itself is generally variously inclined with respect to the surrounding flat surface, it is detected as dark by bright field illumination as well as chipped or voided, and bright by dark field illumination. Therefore, the convex foreign matter is detected similarly to the concave defect. However, since the foreign matter itself can be removed from the thin film magnetic haze by cleaning later, it is necessary to detect the convex foreign matter and the chipping / void as a concave defect in a distinguished state. . However, in the technique described in the transcript, since only normal bright-field illumination and dark-field illumination are used for image detection, both convex foreign matter and concave defects (chip / void) are detected. At the same time, it is possible to detect them at the same time, but it is impossible to detect them while the convex foreign matter and the concave defect are clearly discriminated.

A first object of the present invention is to focus on the fact that chips and voids are present in a concave shape with respect to a flat portion, and that foreign matters are present in a convex shape with respect to a flat portion. Another object of the present invention is to provide a visual inspection method and a visual inspection method which can be detected in a clearly distinguished state. A second object of the present invention is to provide a magnetic head inspection method and a magnetic head inspection method in which the appearance inspection target is a magnetic head. Third of the present invention
An object of the present invention is to provide a magnetic head manufacturing facility that can detect concave defects and convex foreign substances existing on the magnetic head more stably and clearly in a final stage on the magnetic head manufacturing line. is there.

[0007]

The first object of the present invention is basically to provide a photographed image for an inspection area which is illuminated from above with the inspection area on the visual inspection object being renewable. Is extracted by performing a binarization process on the region, and the oblique illumination is performed at different times while facing each other from diagonally above in the same direction as the edge forming direction, after extracting the region where the concave defect / convex foreign matter exists. By calculating and comparing the brightness distribution in each of the areas where the concave defects and convex foreign substances are present in the captured image for the inspection area to be inspected,
An XYZ stage which is achieved by discriminating whether each of the area portions is a concave defect or a convex foreign substance, and which can be arbitrarily moved in the X, Y, and Z directions with the appearance inspection object placed thereon. An epi-illumination system that illuminates the inspection area on the appearance inspection object from above the inspection area, and the inspection area is obliquely upward in the same direction as the edge forming direction, and at different times in a state of facing each other. Two-way oblique illumination system for oblique illumination, a TV camera that captures an inspection area under each of an epi-illumination state and an oblique illumination state, and an inspection area that is epi-illuminated from the TV camera A region where a concave defect or a convex foreign object is present is extracted by binarizing the captured image with respect to the image, and then at different times in a state of being opposed to each other from diagonally above in the same direction as the edge forming direction. The above inspection area illuminated obliquely An image for discriminating whether each of the region portions is a concave defect or a convex foreign object by calculating and comparing the brightness distribution in each of the regions where the concave defect and the convex foreign object are present in the captured image with respect to This is achieved by configuring to include processing means.

The second object is basically based on the first object.
This is achieved by limiting the appearance inspection target to the magnetic head for the purpose of (1), and detecting the convex foreign matter and the concave defect existing on the magnetic head in a distinguished state by the same method and configuration.

The third object is basically achieved by providing the above-described magnetic head inspection apparatus at a final stage on a magnetic head manufacturing line.

[0010]

[Function] When the inspection area on the visual inspection object is illuminated from above from above, since the reflected light is scattered in both the convex foreign matter and the concave defect, the convex foreign matter and the concave defect are present. The part of the area which is in the dark is detected as a dark part. Therefore, by binarizing the captured image of the inspection area under the epi-illumination state, the area where the concave defect / convex foreign substance exists can be extracted. On the other hand, when the inspection area is obliquely illuminated at different times from the diagonally upper side in the same direction as the edge forming direction and at different times, the reflected light in the oblique illumination direction is different between the convex foreign matter and the concave defect. A clear difference is observed in the scattering state. That is, for example, when the concave defect is illuminated obliquely from the upper left direction,
While scattered reflected light is detected only from the right side of the concave defect,
When the convex foreign material is illuminated obliquely from the upper left, the scattered reflected light is detected only from the left side of the convex foreign material. Conversely, when the concave defect is illuminated obliquely from the upper right, the scattered reflected light is detected only from the left side of the concave defect, while the convex foreign matter is obliquely illuminated from the upper right. When illuminated in one direction, the scattered reflected light is detected only from the right side of the convex foreign matter. Therefore, based on the captured image for the inspection area under the oblique illumination state, the brightness distribution in each of the areas where the concave defects and the convex foreign substances are present is calculated and compared. Whether the defect is a concave defect or a convex foreign material can be easily and reliably discriminated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to FIGS. 1 to 10. Before describing the present invention in detail, its theoretical background will be described as follows. That is, normally, it is almost unavoidable that foreign matter such as dust adheres to the inspection object as a convex shape. Here, when bright field illumination and dark field illumination are performed on the convex foreign matter and the concave defect, 2 (A) to 2 (D) show the state of the reflected light at the point. Until now, the appearance inspection of the thin-film magnetic head has been performed exclusively by hand using a metallographic microscope and detecting the reflected light from the inspection object, as shown in FIGS. 2A and 2B. As described above, when the bright field illumination is performed on the chip 11, the void 12, and the convex foreign substance 13 as the concave defect, the reflected light is scattered at each of the concave defect and the convex foreign substance 13. Therefore, if an image of the concave defect and the convex foreign material 13 is taken through the objective lens 4, the region corresponding to the concave defect and the convex foreign material 13 in the taken image is a normal portion of the surrounding area. Is detected as a darker region than that of. On the other hand, when dark field illumination is performed, as shown in FIGS. 2 (C) and 2 (D), the reflected light is specularly reflected in the normal portion, contrary to the bright field illumination.
Are not detected through the concave defect, the convex foreign matter 1
3 respectively, the reflected light is scattered. Therefore, if an image of the concave defect and the convex foreign material 13 is taken through the objective lens 4, the region corresponding to the concave defect and the convex foreign material 13 in the taken image is a normal portion of the surrounding area. Is detected as a region that is brighter than. As described above, the chip 11 as a concave defect, the void 12, and the convex foreign matter 13 can be detected by performing bright-field illumination or dark-field illumination on the inspection target area. However, since the convex foreign matter 13 can be removed by subsequent cleaning, the convex foreign matter 13 and the concave defect need to be detected in a distinguished state. Up to now, as described above, since only bright-field illumination and dark-field illumination have been used, the chip 11 as a concave defect, the void 12, and the convex foreign substance 13 can both be detected. However, the two could not be detected in a clearly discriminated state.

Now, in the present invention, chipping 1 as a concave defect
1, voids 12, and convex foreign substances 13 are to be detected in a clearly distinguished state.
Shows the principle of discrimination detection. As shown in FIG. 3A, when oblique illumination is performed on the flat portion as a normal portion from the right or left direction, the reflected light from the flat portion can be detected in any case. There is nothing. However, as shown in FIG. 3B, when oblique illumination is performed on the chip 11 or the void 12 from, for example, the right direction, the scattered reflected light from the inclined surface facing the illumination light source causes the objective lens 4 to emit light. It can be detected via Therefore, if an image corresponding to the chip 11 or the void 12 is detected via the objective lens 4, the left side of the region corresponding to the chip 11 or the void 12 is detected brighter than the right side in the captured image. Things.
Such a situation is the same even when oblique illumination is performed from the left. On the other hand, as shown in FIG.
When oblique illumination is performed on the convex foreign material 13 from the right or left direction, the scattered reflected light from the convex foreign material 13 can be detected in any case. Therefore, when oblique illumination from the left is performed, if the image of the convex foreign matter 13 is detected via the objective lens 4, the convex foreign matter 13 is detected in the captured image.
In the corresponding area, the left side is detected brighter than the right side. Such a situation is the same even when oblique illumination is performed from the right. As described above, when the oblique illumination is performed on the concave defect or the convex foreign material 13, the generation / detection position of the scattered reflected light differs depending on the direction of the oblique illumination. Can be detected in a state where the convex foreign matter 13 and the concave defect are discriminated.

Here, when oblique illumination is performed on the concave defect or the convex foreign material 13, an image of the concave defect or the convex foreign material 13 is used in an area corresponding to the concave defect or the convex foreign material 13. A method for quantifying the brightness distribution will be described with reference to FIGS. 4A and 4B. FIG. 4A shows diffuse reflection when oblique illumination is performed on the convex foreign matter 13 from the right. The state of light and the captured image of the convex foreign matter 13 at that time, and FIG. 12B shows the state of scattered reflected light when oblique illumination is performed on the concave defect from the right direction. FIG. 3 shows captured images for concave defects at the time. As can be seen from FIG. 2 described above, in the captured image of the convex foreign matter 13 and the concave defect under the oblique illumination state, the brightness of the area corresponding to the convex foreign matter 13 and the concave defect is higher than that of the flat part. Because of its small size, binarization processing is performed on a captured image so that a region corresponding to a convex foreign substance 13 and a concave defect can be easily extracted from the image. If the position of the center of gravity on the area in each of the extracted region portions is obtained and an XY coordinate system having this as an origin is assumed, the brightness distribution in each of the region portions can be easily quantified. It has become something. As shown in FIG. 4A, when the oblique illumination is performed on the convex foreign matter 13 from the right direction, since the scattered reflected light is detected on the X-axis positive direction side, the area portion thereof is detected. Within the above, the calculated total value of the product of the brightness and the X coordinate value of each pixel is obtained with a positive (+) sign. on the other hand,
As shown in FIG. 7B, when the oblique illumination is performed on the concave defect from the right side, since the scattered reflected light is detected on the negative side of the X-axis, each pixel in the region is not reflected. The sum of the product of the brightness and the X coordinate value in the above is obtained with a negative (-) sign. Therefore,
If the sign of the calculated sum is positive, it can be discriminated as a convex foreign substance, and if it is negative, it can be discriminated as a concave defect. However, in practice, the convex foreign matter 13 and the concave defect generally have complicated shapes, so that the above-described ideal reflection characteristics are not always obtained. In the end, not only the oblique illumination from the right direction but also the oblique illumination from the left direction, the operation sum value is obtained in the same manner, and by determining the sign of the difference of the operation sum value, it is possible to make the operation more stable. Thus, it is possible to reliably discriminate between the convex foreign matter 13 and the concave defect.

As described above, even if oblique illumination is performed on the object to be inspected from the left and right, the direction of the oblique illumination with respect to the object to be inspected must be appropriately set. . FIGS. 5A to 5D show how reflected light is generated depending on the direction of oblique illumination with respect to the thin-film magnetic head. As shown in FIG. 5A, when the installation direction of the oblique illumination light source 2 is set to be orthogonal to the edge forming direction on the thin-film magnetic head 1, the rail surface is enlarged in FIG. As shown in the figure, the reflected light from the point A on the rail surface cannot be detected, but the scattered reflected light from the point B on the chip facing the oblique illumination can be detected. At point C on the edge, the oblique illumination light is scattered by the edge itself, so that the scattered reflected light can be detected. On the other hand, FIG.
As shown in FIG. 5C, when the installation direction of the oblique illumination light source 2 is set to be parallel to the edge forming direction on the thin-film magnetic head 1, the rail surface is shown in an enlarged state in FIG. In addition, the reflected light from point A 'on the rail surface cannot be detected, but B' on the chip facing oblique illumination.
The scattered reflected light from the point can be detected. At point C 'on the edge, the oblique illumination light is regularly reflected, and the reflected light cannot be detected. As described above, in the present invention, in order to detect the presence or absence of convex foreign substances and concave defects present on the rail surface and edges, it is necessary to detect only the scattered reflected light from the convex foreign substances and concave defects. In addition, as shown in FIG. 5A, it is not preferable that the installation direction of the oblique illumination light source 2 is set to be orthogonal to the edge forming direction on the thin-film magnetic head 1. This is because the scattered reflected light from the point C acts as a disturbance when capturing an image. As shown in FIG. 5C in which the scattered reflected light does not occur as a disturbance, the oblique illumination light source 2 needs to have its installation direction set.

Although the theoretical background of the present invention has been described above, the present invention will be described in more detail hereinafter. FIG. 1 shows a configuration of an example of a visual inspection apparatus according to the present invention. This is shown as a magnetic head. In this case, the thin-film magnetic head 1 itself is mounted on the XYZ stage 3 so as to be arbitrarily set in the X, Y, and Z directions. X
When the YZ stage 3 is appropriately driven, the inspection area is updated by irradiating the illumination light from the oblique illumination light source 2 to the rail surface as the inspection area on the thin-film magnetic head 1 and its vicinity. On the other hand, it is possible to discriminate whether a concave defect or a convex foreign substance is present in the inspection area, and if so, the type thereof. As shown, a pair of oblique illumination light sources 2 are installed diagonally above in the same direction as the longitudinal direction of the rail surface, and the illumination light from these oblique illumination light sources 2 is transmitted to an inspection area on the thin-film magnetic head 1. While being illuminated, the inspection area is illuminated from above by illuminating the illumination light from the epi-illumination light source 6 from above through the half mirror 5 and the objective lens 4. Each time the inspection area is placed in the epi-illumination state and the one-way oblique illumination state, an image of the inspection area is picked up and detected by the TV camera 7 via the objective lens 4 and the half mirror 5. The taken and detected images are sequentially image-processed by the image processing device 8, thereby achieving the intended purpose.

Now, the operation and processing in the appearance inspection apparatus will be specifically described. FIG. 6 shows an example of the operation and processing.
It shows a processing procedure flow. In this case,
First, in a state where the inspection area is in the epi-illumination state, an image of the inspection area is imaged and detected by the TV camera 7 (processing procedure 20), and the presence of a convex foreign substance or a concave defect is determined from the imaged and detected image. The area portion is to be extracted by the binarization process (procedure 21). After that,
In the same manner the image to the inspection area under the left oblique illumination state is captured and detected (procedure 22), luminance distribution M _L is the arithmetic processing of the convex particle or concave defects corresponding area portion respectively (this operation The processing is described as being quantified by (described later) (processing procedure 2).
3). Thereafter, an image of the inspection area under the oblique rightward illumination state is similarly captured and detected in the same manner, and a brightness distribution M _R in each of the convex foreign matter and concave defect corresponding area portions is obtained by arithmetic processing. (Procedures 24 and 25). As described above, the brightness obtained distribution M _L, on the difference _{M SUB (= M L -M R} ) is obtained from M _R, by the sign of the difference M _SUB is determined, that When a convex foreign substance or a concave defect exists in the inspection area, the convex foreign substance or the concave defect can be detected in a state where the type is discriminated (processing procedure 2).
6).

[0017] Here, the brightness distribution M _L, if specifically described method for quantifying M _R, the brightness distribution M _L, M _R
Is quantified by the following equation:

[0018]

(Equation 1)

Here, M is an evaluation value of the brightness distribution, s is an area where a concave defect or a foreign substance exists, and B (x, y) is the brightness of a pixel at a coordinate value (x, y). Is shown. As a result, the brightness distributions M _L and M _R in each of the convex foreign matter and concave defect corresponding area portions are quantified, and the brightness distribution can be objectively evaluated. 7, FIG. 7 shows imaged / detected images for convex foreign matter and concave defects (chips and voids) with respect to oblique illumination from the left and right sides. However, M _L and M have already been described above. the value of _R is oblique illumination direction and a convex foreign matter, by combining whether the concave defects respectively, since the obtained as having a predetermined code, the difference M _SUB
Absolute value in (= M _L -M _R) is as large, yet numerals convex foreign substance, corresponding to the concave defects respectively, negative, has become one obtained as a positive. As a result, when a convex foreign substance or a concave defect exists in the inspection area, the type of the difference M _SUB can be determined more stably and surely by determining the sign of the difference M _SUB. .

The appearance inspection method and apparatus for the thin-film magnetic head to be inspected have been described above.
As can be seen from the operation / processing procedure flow in the example shown in FIG. 6, the types of the convex foreign matter and the concave defect are discriminated for the first time by sequentially performing the epi-illumination, the leftward oblique illumination, and the rightward oblique illumination. However, by simultaneously performing the epi-illumination, the leftward oblique illumination, and the rightward oblique illumination, it is possible to more quickly discriminate the type. FIG. 8 shows the configuration of another example of a visual inspection device capable of discriminating such a type. Basically, a light source with different wavelengths is used for epi-illumination, leftward oblique illumination, and rightward oblique illumination, and a color TV camera that can accurately and spectrally separate light of these wavelengths is used.
By simultaneously performing the epi-illumination, the leftward oblique illumination, and the rightward oblique illumination, the type can be discriminated more quickly. As shown in FIG. 8, the difference from the one shown in FIG. 1 is that the epi-illumination light source 6, the left oblique illumination light source 2, and the right oblique illumination light source 2 each have a green (G) filter 3.
0, a blue (B) filter, and a red (R) filter 32 are provided.
3 is used. This allows epi-illumination,
Since images for leftward oblique illumination and rightward oblique illumination can be simultaneously imaged and detected by the color TV camera 33 via the objective lens 4, the types of the convex foreign matter and the concave defect can be discriminated more quickly. Things.

FIGS. 9A and 9B show the transmission characteristics of the three types of filters 30 to 32 and the spectral sensitivity characteristics of the color TV camera 33 used in the visual inspection apparatus. However, with such a filter transmission characteristic and a color TV camera spectral sensitivity characteristic, it is possible to simultaneously perform epi-illumination, leftward oblique illumination, and rightward oblique illumination. illumination,
Images (green image, blue image, red image) for leftward oblique illumination and rightward oblique illumination can be obtained.
The binarization processing of the green image is performed by the image processing device 8 to extract an existing area portion of a convex foreign substance or a concave defect. FIGS. 10A and 10B show the state of scattered reflected light when leftward oblique illumination and rightward oblique illumination are simultaneously performed on a concave defect and a convex defect, respectively. are, but this case also the brightness distribution of the above M _L, M _R
Equivalent brightness distribution M _B, which is intended to M _R can be considered. Therefore, when a convex foreign matter or a concave defect exists in the inspection area, the type of the difference M _SUB can be determined to determine the type more stably, quickly, and reliably. It is.

Finally, the magnetic head manufacturing equipment will be described. In the final stage on the magnetic head manufacturing line, the concave defect and the convex foreign matter existing on the magnetic head are more stably and clearly discriminated. In the case where the appearance inspection apparatus shown in FIG. 1 or FIG. 8 is provided as a magnetic head inspection apparatus at the final stage on a magnetic head production line, it is present on the magnetic head immediately after production. The convex foreign matter and the concave defect can be discriminated more stably (quickly) and reliably.
If the presence of a convex foreign substance is found as a result of the discrimination, a necessary measure, that is, the magnetic head is cleaned as a foreign substance removing process.

[0023]

As described above, according to the first to third aspects, the concave defect and the convex foreign substance existing on the object to be inspected are made more stable and clearly discriminated. In the case of the appearance inspection method and the apparatus which can be detected, and in the case of claim 4 to 6, the concave defect and the convex foreign object existing on the appearance inspection object are more stably and quickly and clearly discriminated. In the case of the appearance inspection method and apparatus according to claims 7 to 9, which can be detected in a state where the magnetic head is detected, the concave defect and the convex foreign substance existing on the magnetic head are more stably and clearly distinguished. A magnetic head inspection method and apparatus capable of being detected in a state are further provided.
According to the second aspect, there is provided a magnetic head inspection method and apparatus capable of detecting a concave defect and a convex foreign matter existing on a magnetic head more stably, quickly, and in a clearly distinguished state. And 14, magnetic head manufacturing equipment capable of more stably (swiftly) distinguishing the type of the convex foreign matter and the concave defect existing on the magnetic head immediately after the manufacture, and reliably discriminating the types thereof. It has been done.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a visual inspection apparatus according to the present invention.

FIGS. 2A to 2D are views for explaining states of light reflected from each of a chip, a void, and a foreign matter;

FIGS. 3A to 3C are diagrams for explaining the state of reflected light due to oblique illumination.

FIGS. 4A and 4B are diagrams for explaining a method for quantifying the brightness distribution of an image.

FIGS. 5A to 5D are views showing states of reflected light due to differences in oblique illumination directions.

FIG. 6 is a diagram showing an operation / processing procedure flow in the appearance inspection apparatus shown in FIG. 1;

FIG. 7 is a diagram for explaining a method for determining whether a foreign object is missing or void.

FIG. 8 is a diagram showing a configuration of another example of the appearance inspection apparatus according to the present invention;

FIGS. 9A and 9B are respectively a transmission characteristic and a color TV of a filter used in the appearance inspection apparatus.
Diagram showing spectral characteristics of camera

FIGS. 10A and 10B are diagrams for explaining a processing method for an image obtained by performing blue oblique illumination and red oblique illumination on each of a chip, a void, and a foreign substance;

FIGS. 11A and 11B are diagrams showing a thin-film magnetic head as an example of a visual inspection object and a main body of the thin-film magnetic head, respectively.

FIG. 12A shows a thin film magnetic head in which a chip or a void exists as a defect, and FIGS. 12B to 12D.
Are longitudinal sectional views taken along the line AA ', the line BB', and the line CC 'in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic head (body), 2 ... Oblique illumination light source, 3 ... XY
Z stage, 4 ... objective lens, 5 ... half mirror, 6 ...
Epi-illumination light source, 7 TV camera, 8 image processing device, 1
0: rail surface, 11: chip (concave defect), 12: void (concave defect), 13: convex foreign matter, 30: green filter,
31: blue filter, 32: red filter, 33: color TV camera

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Kubota 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi, Ltd. Production Engineering Laboratory (56) References JP-A-62-24105 (JP, A) JP-A-3-130607 (JP, A) JP-A-59-153108 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/88-21/958 G01B 11/30 G11B 5/455

Claims (14)

(57) [Claims] 1. A method according to claim 1, wherein a concave defect or a convex foreign substance is present on a visual inspection target having one or more edges formed in one direction, and whether the concave defect or the convex foreign substance is present. Is an appearance inspection method in which a concave defect and a convex foreign matter are detected in a discriminated state, and the reflected light is illuminated from above from above with the inspection area on the appearance inspection object being renewable. A binarization process is performed on the captured image for the inspection area to extract the area where the concave defect / convex foreign substance is present, and then, from the diagonally upper side in the same direction as the edge forming direction, the time is set in a state of facing each other. By calculating and comparing the brightness distribution in each of the regions where the concave defect / convex foreign matter is present in the captured image with respect to the inspection region which is obliquely illuminated differently, each of the region portions has a concave shape. Whether it is a defect or a convex foreign matter An appearance inspection method that can be discriminated. 2. A method according to claim 1, wherein a concave defect or a convex foreign substance is present on an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign substance is present. In order to detect the concave defect and the convex foreign matter in a distinguished state, in a state in which the inspection area on the visual inspection object is renewable, an image captured for the inspection area that is illuminated by incident light from above is taken. By performing the binarization process, a region where a concave defect or a convex foreign substance is present is extracted, and then obliquely illuminated at different times in an opposite state from diagonally above in the same direction as the edge forming direction. By calculating and comparing the brightness distribution in each of the areas where the concave defect / convex foreign matter exists in the captured image with respect to the inspection area,
An appearance inspection method in which each of the area portions is discriminated as to whether it is a concave defect or a convex foreign matter, and the brightness distribution in each of the area portions where the concave defect or the convex foreign matter exists is calculated and calculated. When compared, the coordinate value of each pixel in the area portion and the coordinate value of the pixel in the area portion for each oblique illumination from two directions in a coordinate system having the center of gravity position on the area in the area portion as the origin. The sum of the product with the brightness at
Appearance inspection method in which each of the regions where a concave defect or a convex foreign substance is present is discriminated as a concave defect or a convex foreign substance using the sign of the difference of the total value for each oblique illumination from the direction. . 3. A method of determining whether a concave defect or a convex foreign substance is present on a visual inspection object having one or more edges formed in one direction, and determining whether the concave defect or the convex foreign substance is present. Is a visual inspection device that detects a concave defect and a convex foreign material in a distinguished state, and is capable of arbitrarily moving in the X, Y, and Z directions with the visual inspection object mounted thereon. XY
A Z stage, an epi-illumination system for epi-illuminating an inspection area on the visual inspection object from above the inspection area, and a time in a state where the inspection area is opposed to the inspection area from diagonally above in the same direction as the edge forming direction. A two-way oblique illumination system that performs oblique illumination differently, a TV camera that captures an inspection area located under each of an epi-illumination state and an oblique illumination state, and epi-illumination from the TV camera The area where the concave defect / convex foreign matter is present is extracted by binarizing the captured image for the inspection area in which it is located. By calculating and comparing the brightness distribution in each of the regions where the concave defect and the convex foreign matter are present in the captured image with respect to the inspection region which is differently illuminated obliquely, each of the region portions has the concave defect. Or Configuration of the appearance inspection apparatus and an image processing means for discriminating whether the Jo foreign matter. 4. A method of determining whether a concave defect or a convex foreign object is present on a visual inspection object having one or more edges formed in one direction, and determining whether the concave defect or the convex foreign object is present. Is an appearance inspection method in which a concave defect and a convex foreign matter are quickly detected in a distinguished state. Binary processing is performed on a captured image of an inspection region that is illuminated with incident light at a specific wavelength to extract a region where a concave defect or a convex foreign object is present, while forming an edge in parallel with the incident illumination. A region where a concave defect or a convex foreign object is present in a captured image with respect to the inspection region, which is obliquely illuminated at the second and third specific wavelengths at the same time while facing each other from the obliquely upper side in the same direction as the direction. Calculate and compare the brightness distribution of each A visual inspection method in which each of the regions is discriminated as to whether it is a concave defect or a convex foreign matter. 5. A method for determining whether a concave defect or a convex foreign object is present on a visual inspection target having one or more edges formed in one direction, and determining whether the concave defect or the convex foreign object is present. In the state where the inspection area on the visual inspection object is renewable, the incident light is illuminated with incident light at the first specific wavelength from above so that the concave defect and the convex foreign substance can be quickly detected in a distinguished state. A binarization process is performed on the captured image for the inspection area to extract a region where a concave defect or a convex foreign substance is present, and, in parallel with the incident illumination, from the obliquely upper side in the same direction as the edge forming direction. Calculate the brightness distribution in each of the areas where the concave defects and the convex foreign substances are present in the captured image with respect to the inspection area which is simultaneously obliquely illuminated at the second and third specific wavelengths in the opposed state. The area portion by comparing An appearance inspection method for discriminating whether each is a concave defect or a convex foreign matter, wherein a brightness distribution in each of the regions where the concave defect and the convex foreign matter are present is calculated and compared. In this case, in a coordinate system having the origin at the position of the center of gravity on the area of each of the region portions, 2
The sum of the product of the coordinate value of each pixel in the area portion and the brightness at the pixel for each oblique illumination from the direction is obtained, and the difference between the sum of the products of the oblique illumination from each of the two directions is calculated. An appearance inspection method, wherein a symbol is used to discriminate whether a concave portion or a convex foreign material is present in each of the regions where the concave defect or the convex foreign material is present. 6. A method according to claim 1, wherein a concave defect or a convex foreign substance is present on a visual inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign substance is present. Is a visual inspection device that allows a concave defect and a convex foreign material to be quickly detected in a discriminated state, and can be arbitrarily moved in the X, Y, and Z directions with the visual inspection object placed thereon. An XYZ stage, an epi-illumination system for epi-illuminating the inspection area on the appearance inspection object with a first specific wavelength from the top of the inspection area, and an edge forming direction for the inspection area in parallel with the epi-illumination. A two-way oblique illumination system that simultaneously obliquely illuminates at the second and third specific wavelengths in an opposed state from the obliquely upper side in the same direction, and under an epi-illumination state and a two-way oblique illumination state The inspection area that is located, the spectral characteristics for the first, second, and third specific wavelengths. A color TV camera that captures an image in accordance with the above, and a binarization process of a captured image from the color TV camera with respect to the inspection area that is illuminated by epi-illumination is performed to extract an area portion where a concave defect or a convex foreign substance exists. From the obliquely upper side in the same direction as the edge forming direction, the brightness distribution in each of the areas where the concave defects and the convex foreign substances are present in the captured image with respect to the inspection area that is obliquely illuminated in the opposite state is shown. By calculating and comparing,
A visual inspection device configured to include image processing means for discriminating whether each of the area portions is a concave defect or a convex foreign substance. 7. Whether or not a concave defect or a convex foreign object exists on a magnetic head as an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign object exists. In the case of the magnetic head inspection method in which the concave defect and the convex foreign matter are detected in a distinguished state, in a state where the inspection area on the appearance inspection target is renewable, By binarizing the captured image for the inspection area that is illuminated from above, the area where the concave defect / convex foreign substance is present is extracted, and then the relative position is determined from diagonally above in the same direction as the edge forming direction. By calculating and comparing the brightness distribution in each of the areas where the concave defect / convex foreign matter is present in the captured image with respect to the inspection area which is obliquely illuminated at different times in the facing state, Each area part is concave A magnetic head inspection method in which a defect or a convex foreign matter is discriminated. 8. Whether or not a concave defect or a convex foreign object exists on a magnetic head as an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign object exists. In this case, the inspection area is illuminated from above with the inspection area on the visual inspection object being renewable so that the concave defect and the convex foreign substance can be detected in a distinguished state. A region where a concave defect or a convex foreign object is present is extracted by binarizing the captured image with respect to the image, and then at different times in a state of being opposed to each other from diagonally above in the same direction as the edge forming direction. By calculating and comparing the brightness distribution in each of the regions where the concave defect / convex foreign matter exists in the captured image with respect to the inspection region that is obliquely illuminated, each of the region portions has a concave defect or a convex shape. Is discriminated as a foreign object In the magnetic head inspection method, when the brightness distribution in each of the regions where the concave defects and the convex foreign substances are present is calculated and compared, the area distribution in each of the regions is calculated. In a coordinate system with the center of gravity position as the origin, the sum of the product of the coordinate value of each pixel in the region and the brightness at the pixel for each of the oblique illuminations from two directions is obtained. A magnetic head inspection method in which each of the regions where the concave defect / convex foreign matter is present is discriminated as a concave defect or a convex foreign matter based on the sign of the difference of the sum value for each of the oblique illuminations. 9. Whether or not a concave defect or a convex foreign object exists on a magnetic head as an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign object exists. The magnetic head inspection apparatus is configured to detect the concave defect and the convex foreign matter in a discriminated state. An XYZ stage that can be moved to the front, an epi-illumination system that epi-illuminates the inspection area on the appearance inspection object from above the inspection area, and a diagonal upper part of the inspection area in the same direction as the edge forming direction. A two-way oblique illumination system that performs oblique illumination at different times in a state in which the illumination is performed, a TV camera that captures an inspection area located under each of an epi-illumination state and an oblique illumination state, and a , An image of the inspection area illuminated by epi-illumination The image is subjected to a binarization process to extract a region where a concave defect or a convex foreign substance is present, and then, obliquely from the upper side in the same direction as the edge forming direction at different times while facing each other. By calculating and comparing the brightness distribution in each of the regions where the concave defect / convex foreign substance is present in the captured image with respect to the inspection area to be illuminated, each of the region portions is a concave defect or a convex foreign substance. A magnetic head inspection apparatus having a configuration including image processing means for discriminating whether there is a magnetic head. 10. Whether or not a concave defect or a convex foreign object exists on a magnetic head as an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign object exists. Is a magnetic head inspection method in which a concave defect and a convex foreign matter are quickly detected in a discriminated state, wherein the inspection area on the appearance inspection target is renewable. Then, a binarized process is performed on a captured image of an inspection area that is illuminated with incident light at a first specific wavelength from above to extract an area portion where a concave defect / convex foreign substance is present, while parallelizing the incident illumination. Then, there is a concave defect or a convex foreign object in the picked-up image with respect to the inspection area which is obliquely illuminated at the second and third specific wavelengths at the same time while facing each other obliquely from above in the same direction as the edge forming direction. In each of the areas A magnetic head inspection method wherein the brightness distribution of each of the regions is calculated and compared to discriminate whether each of the regions is a concave defect or a convex foreign matter. 11. Whether or not a concave defect or a convex foreign substance is present on a magnetic head as an appearance inspection object having one or more edges formed in one direction, and whether the concave defect or the convex foreign substance is present. In this case, in order to quickly detect the concave defect and the convex foreign matter in a discriminated state, the first specific wavelength is set from the top while the inspection area on the visual inspection target is renewable. The binarization process is performed on the captured image of the inspection area that is illuminated by the incident light to extract the area where the concave defect / convex foreign matter is present, and in the same direction as the edge forming direction in parallel with the incident illumination. A concave defect in the captured image for the inspection area, which is simultaneously obliquely illuminated obliquely at the second and third specific wavelengths in a state of being opposed to each other from obliquely above
By calculating and comparing the brightness distribution in each of the areas where the convex foreign matter is present, it is possible to determine whether each of the areas is a concave defect or a convex foreign matter by a magnetic head inspection method. When calculating and comparing the brightness distribution in each of the regions where the concave defects and the convex foreign substances are present, a coordinate system using the center of gravity on the area in each of the regions as an origin is used. The sum of the product of the coordinate value of each pixel in the area and the brightness at the pixel for each of the oblique illuminations from the two directions is obtained, and the sum of the products of the oblique illuminations from the two directions is obtained. With the sign of the difference,
A method of inspecting a magnetic head, wherein a region where a convex foreign substance is present is discriminated as a concave defect or a convex foreign substance. 12. Whether or not a concave defect or a convex foreign substance exists on a magnetic head to be inspected for appearance in which one or more edges are formed in one direction, and whether the concave defect or the convex foreign substance exists. The magnetic head inspection device is configured to detect the concave defect and the convex foreign material promptly in a distinguished state.
An XYZ stage that can be arbitrarily moved in the Y and Z directions, an epi-illumination system that epi-illuminates an inspection area on the visual inspection object with a first specific wavelength from an upper direction of the inspection area, A two-direction oblique illumination system for simultaneously obliquely illuminating the inspection area at the second and third specific wavelengths in a state opposite to each other from diagonally above in the same direction as the edge forming direction; Color TV camera for imaging the inspection area under the one-side illumination state with spectral characteristics for the first, second, and third specific wavelengths, and the inspection area from the color TV camera which is illuminated by epi-illumination A binarization process is performed on a captured image to extract a region in which a concave defect or a convex foreign object is present, and then obliquely illuminated in an obliquely upper position in the same direction as the edge forming direction in a state of facing each other. For the above inspection area An image for discriminating whether each of the region portions is a concave defect or a convex foreign object by calculating and comparing the brightness distribution in each of the regions where the concave defect and the convex foreign object are present in the captured image. A magnetic head inspection device having a configuration including a processing unit. 13. A magnetic head manufacturing equipment comprising a magnetic head inspection device at a final stage on a magnetic head manufacturing line, wherein the magnetic head inspection device has at least one edge formed in one direction. Whether there is a concave defect or a convex foreign substance on the magnetic head as an appearance inspection object to be inspected, if the concave defect or the convex foreign substance exists, the concave defect and the convex foreign substance What is claimed is: 1. A magnetic head inspection apparatus which is detected in a discriminated state, comprising: an XYZ stage arbitrarily movable in X, Y, and Z directions with an appearance inspection object mounted thereon; An epi-illumination system that epi-illuminates the inspection area in the inspection area from above, and the inspection area is obliquely upward in the same direction as the edge forming direction.
Two-way oblique illumination system for oblique illumination at different times in opposing states, a TV camera for imaging an inspection area under each of an epi-illumination state and an oblique illumination state, and the TV camera From the above, after extracting the area where the concave defect / convex foreign matter exists by binarizing the captured image for the inspection area that is being illuminated by epi-illumination, from diagonally above in the same direction as the edge forming direction, By calculating and comparing the brightness distribution in each of the areas where concave defects and convex foreign substances are present in the captured image for the inspection area that is obliquely illuminated at different times in the opposed state, A magnetic head manufacturing facility configured to include image processing means for discriminating whether each of the area portions is a concave defect or a convex foreign substance. 14. A magnetic head manufacturing facility comprising a magnetic head inspection device at a final stage on a magnetic head manufacturing line, wherein the magnetic head inspection device has at least one edge formed in one direction. Whether there is a concave defect or a convex foreign substance on the magnetic head as an appearance inspection object to be inspected, if the concave defect or the convex foreign substance exists, the concave defect and the convex foreign substance What is claimed is: 1. A magnetic head inspection apparatus which is quickly detected in a discriminated state, comprising: an XYZ stage which can be arbitrarily moved in X, Y, and Z directions while an appearance inspection object is placed; An epi-illumination system that illuminates the inspection area on the target with incident light at a first specific wavelength from the upper direction of the inspection area, and faces the inspection area in parallel with the epi-illumination from diagonally above in the same direction as the edge forming direction. Second and third Simultaneously oblique illumination at a specific wavelength 2
The oblique illumination system and the inspection areas placed under the epi-illumination state and the bi-directional oblique illumination state are defined as first, second, and third directions.
TV imaging with spectral characteristics for specific wavelength
A binarizing process is performed on the captured image from the color TV camera with respect to the inspection region that is illuminated by epi-illumination to extract the region where the concave defect / convex foreign substance is present, and the edge forming direction and From diagonally above in the same direction,
By calculating and comparing the brightness distribution in each of the regions where the concave defect / convex foreign matter exists in the captured image with respect to the inspection region that is obliquely illuminated in the opposite state, each of the region portions is calculated. Image processing means for discriminating whether the defect is a concave defect or a convex foreign matter.