JP7271329B2 - Lighting device and visual inspection device equipped with the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an illumination device that can be suitably used when inspecting the appearance of a substrate having a metal film formed on its surface, and an appearance inspection apparatus provided with this illumination device.

2. Description of the Related Art Conventionally, a visual inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 2007-64801 is known as an apparatus for imaging an appearance of an electronic component and inspecting its defects. This appearance inspection apparatus includes a transport mechanism that transports an electronic component in a predetermined transport direction, an imaging mechanism that captures an image of the surface of the electronic component that is transported by the transport mechanism and passes through an imaging area, and an imaging area that is scanned by the transport mechanism. A lighting device that illuminates the electronic component being transported, a determination processing unit that determines the quality of the appearance of the electronic component based on the image of the electronic component captured by the imaging mechanism, and the operation of the lighting device and the imaging mechanism. and a control unit for controlling.

The lighting device includes a first light projecting means, a second light projecting means, and a third light projecting means, and each light projecting means includes a plurality of annularly arranged light projecting sections for irradiating light toward the electronic component. are arranged coaxially in the axial direction of the annularly arranged light projecting units.

The first light projecting means is arranged such that the irradiation optical axis of the light projecting portion is inclined by 15° to 35° with respect to the axis thereof, and the first light projecting means is arranged so as to irradiate the electronic component with blue light. The second light projecting means is arranged such that the irradiation optical axis of the light projecting part is inclined by 40° to 50° with respect to the axis thereof, and the second light projecting means is arranged to irradiate the electronic component with red light. The third light projecting means is arranged such that the irradiation optical axis of the light projecting part is inclined by 55° to 75° with respect to the axis thereof, and the third light projecting means is arranged to irradiate the electronic component with red light. Configured.

The imaging mechanism is arranged such that its imaging optical axis is positioned within the arrangement ring of the light projecting section of each light projecting means. Further, the control unit controls the light projecting means so that the light projecting means that emit light of the same color among the light projecting means emits light toward the electronic component, and the electronic component emits light. While passing through the imaging area, the light projecting means for irradiating light is switched to switch the color of the light irradiated to the electronic component, and the imaging mechanism is controlled to cause the electronic component to emit light. It is configured to take an image of the surface of the electronic component for each color of the irradiated light. The determination processing unit is configured to perform quality determination based on each image captured for each color of light irradiated to the electronic component.

In addition to surface defects such as cracks, scratches, and chips, electronic components also have internal defects such as the lifting of laminated dielectrics and internal electrodes. Illuminated by a single conventional high intensity lamp, the image obtained by the imaging mechanism will highlight certain defects, while others will be characterized to a discernible level. I had a difficult problem. For this reason, illumination using a single high-intensity lamp has not been able to detect all defects with high accuracy.

According to the appearance inspection apparatus disclosed in JP-A-2007-64801 described above, illumination of blue light by the first light projecting means and illumination of red light by the second light projecting means and the third light projecting means are performed. In addition to switching the lighting, the imaging mechanism captures images of the electronic components under illumination of each color. Defects occurring on the surface and inside of parts can be detected with high accuracy.

That is, by illuminating the electronic component using only blue light, the characteristics of defects present on the surface of the electronic component, such as cracks and scratches, can be highlighted to an identifiable level. defects can be detected with high accuracy. In addition, by illuminating an electronic component with only red light, it is possible to highlight to a recognizable level defects that occur inside the electronic component, such as the lifting of laminated dielectrics and internal electrodes. Defects existing on the surface of electronic components can be detected with high accuracy.

Japanese Patent Application Laid-Open No. 2007-64801

By the way, at present, a ceramic substrate is being developed in which a metal film as an electrode or a wiring is formed on a ceramic substrate. In the case of this substrate, there are defects such as scratches and defects in the metal film, defects such as chipping and cracks occurring in the peripheral edge of the ceramic portion of the substrate, and defects such as contamination that may occur on the entire surface of the ceramic substrate. There is a demand for a visual inspection apparatus that can detect defects in the product with high precision.

At the same time, there is also a demand for a visual inspection apparatus capable of performing visual inspection more efficiently by shortening the processing time for this visual inspection compared with the conventional one.

The present invention has been made in view of the above circumstances, and provides a visual inspection apparatus capable of detecting defects in a substrate having a metal film on its surface with high accuracy and more efficiently than the conventional apparatus, and the visual inspection apparatus. The object is to provide an illumination device used for inspection.

The present invention for solving the above problems is
A lighting device used for inspecting the appearance of a substrate having a metal film formed on its surface,
a first lighting unit, the optical axis of which is set so as to be perpendicular to the substrate surface, and which emits light of either blue or red;
a second illumination unit arranged closer to the substrate than the first illumination unit and irradiating green light toward the substrate surface;
a third lighting unit configured to irradiate the substrate surface with light from the periphery thereof, and irradiating the substrate surface with light of a color different from that of the irradiation light of the first lighting unit, either blue or red; It relates to a lighting device.

The present invention also provides an appearance inspection apparatus for inspecting the appearance of a substrate having a metal film formed on its surface,
a transport device for transporting the substrate;
an imaging camera disposed corresponding to an inspection position set on the transport path of the transport device and capturing an image of the substrate transported to the inspection position;
the illumination device disposed corresponding to the inspection position and illuminating the board conveyed to the inspection position;
A determination device that processes the image captured by the imaging camera and determines whether the appearance of the substrate is good or bad,
The imaging camera includes an element that detects red light, an element that detects green light, and an element that detects blue light, and is configured to output image data detected by each element,
The judging device relates to an appearance inspection device configured to judge whether the appearance of a board is good or bad based on each image data corresponding to each detected color output from the imaging camera.

According to this appearance inspection apparatus, the substrate is transported by the transporting device and passed through the inspection position set on the transport path of the transporting device. Then, at this inspection position, the substrate is illuminated by the illumination device, and an image of the surface thereof is captured by the imaging camera. is determined (determined).

As described above, the imaging camera includes an element that detects red light (red light detection element), an element that detects green light (green light detection element), and an element that detects blue light (blue light detection element). Each element is provided and configured to output image data detected by each element.

The imaging camera may have any configuration as long as it has such a function. ), a line sensor in which a plurality of green light detection elements are arranged in a row (line sensor for green), and a line sensor in which a plurality of blue light detection elements are arranged in a row (line sensor for blue) are provided on the substrate. One that is arranged side by side along the transport direction can be exemplified. In this case, the image data output from the line sensor for red, the line sensor for green, and the line sensor for blue are image data corresponding to each detected color.

Alternatively, the imaging camera may be an area sensor camera in which red light detection elements, green light detection elements, and blue light detection elements are alternately arranged in a mosaic pattern. In this case, image data corresponding to red is formed by extracting the data output from the red light detection element among the data output from the area sensor camera, and the data output from the green light detection element is extracted. By doing so, image data corresponding to green is formed, and image data corresponding to blue is formed by extracting data output from the blue photodetector.

Further, the illumination device simultaneously illuminates the substrate at the inspection position with the first illumination section, the second illumination section, and the third illumination section. The first illumination unit is set so that the optical axis of the illumination light is orthogonal to the substrate surface, and emits light of one color selectively set from blue or red. This first illumination unit is mainly for detecting defects such as scratches, defects (including complete disconnection and partial disconnection), and shape abnormalities in the metal film formed on the substrate.

According to the findings of the present inventors, there are red metals such as gold and copper that reflect a lot of red light, and white metals such as silver, magnesium, and aluminum that reflect a lot of blue light. Therefore, in the first irradiation section, red light is selected as irradiation light when the metal film is of a reddish color such as gold or copper. In the case of white materials such as gold and copper, blue light is selected as irradiation light.

Thus, most of the light emitted from the first irradiation unit is reflected in the portion where the metal film is appropriately present. In the damaged portion, the light is diffusely reflected and the amount of reflected light is small. Similarly, in the portion where the metal film is missing, the light is absorbed in the missing portion and the amount of reflected light is reduced.

When the light emitted from the first irradiation unit is red, when the light reflected by the substrate is incident on the imaging camera, it is detected by the red photodetector and turned red. Corresponding image data is generated and becomes image data having a luminance value corresponding to the amount of incident reflected light. Similarly, when the light emitted from the first irradiation unit is blue, when the light reflected by the substrate is incident on the imaging camera, it is detected by the blue light detection element and converted to blue. Corresponding image data is generated and becomes image data having a luminance value corresponding to the amount of incident reflected light.

The determination unit generates a grayscale image by, for example, binarizing the image data corresponding to the color of the light emitted from the first irradiation unit using a predetermined threshold value, and the generated grayscale image is used as a reference. By comparing the grayscale image, scratches, defects, and shape abnormalities of the metal film are detected, and when scratches, defects, and shape abnormalities are detected, the substrate is determined to be defective.

Further, the second illumination section is arranged closer to the substrate than the first illumination section, and is configured to irradiate the substrate surface with green light. This second lighting section is mainly for detecting dirt on the substrate. According to the findings of the present inventors, green light has a characteristic that its absorption rate differs depending on the color of the substrate surface, that is, the amount of reflected light differs.

Thus, when green light emitted from the second irradiation unit, reflected by the substrate, and having a different amount of reflected light depending on the color of the substrate surface is incident on the imaging camera, the green light is detected. This is detected by the device, image data corresponding to green is generated, and image data having a luminance value corresponding to the amount of incident reflected light is generated.

The determination unit generates a grayscale image from the image data corresponding to green, for example, by binarizing with a predetermined threshold value, and compares the generated grayscale image with a reference grayscale image to obtain a substrate. Dirt on the surface is detected, and if dirt is detected, the substrate is determined to be defective.

The third illumination unit is configured to irradiate the substrate surface with light from its surroundings, and irradiates light of a color different from that of the illumination light of the first illumination unit, either blue or red. Configured. That is, when the first illumination unit emits red light, the third illumination unit emits blue light, and when the first illumination unit emits blue light, , the third lighting unit is configured to emit red light. This third illumination unit is mainly for detecting defects such as chips and cracks that occur on the periphery of the substrate.

If there is a chip or crack on the peripheral edge of the substrate, the light emitted from the third lighting unit is diffusely reflected at the portion where the chip or crack exists. less.

When the light emitted from the third irradiation unit is blue, when the light reflected by the substrate is incident on the imaging camera, it is detected by the blue light detection element and turned blue. Corresponding image data is generated and becomes image data having a luminance value corresponding to the amount of incident reflected light. Similarly, when the light emitted from the third irradiation unit is red, when the light reflected by the substrate is incident on the imaging camera, it is detected by the red photodetector and turned red. Corresponding image data is generated and becomes image data having a luminance value corresponding to the amount of incident reflected light.

The determination unit generates a grayscale image by, for example, binarizing the image data corresponding to the color of the light emitted from the third irradiation unit using a predetermined threshold value, and the generated grayscale image is used as a reference. A chip or crack generated on the peripheral edge of the substrate is detected by comparing the grayscale image, and if a chip or crack is detected, the substrate is determined to be defective.

As described above, according to this visual inspection apparatus, red or blue light, green light, and blue or red light are simultaneously emitted from the first irradiation section, the second irradiation section, and the third irradiation section, respectively. is applied to the substrate, and the reflected light is made incident on an imaging camera equipped with a red photodetector, a green photodetector, and a blue photodetector, and the image data detected by each device is obtained. Based on each image data obtained, the judgment device is configured to judge whether the appearance of the substrate is good or bad. Defects such as chips and cracks that are formed can be detected with high accuracy.

In addition, since the various defects described above can be determined with a single image taken by the imaging camera, the processing time for the appearance inspection can be further shortened compared to the conventional method in which images are taken multiple times for each color of illumination. can be performed, and the visual inspection can be performed more efficiently.

In the present invention, each of the first illumination section, the second illumination section, and the third illumination section may have a plurality of light emitting diodes as light sources.

In the present invention, each of the second lighting section and the third lighting section includes a plurality of light emitting diodes arranged in a ring as a light source, and the light emitting diodes constituting the second lighting section are With respect to a plane parallel to the surface of the substrate, the angle of inclination of the optical axis toward the substrate is set within a range of 5° to 45°, and the light-emitting diodes constituting the third lighting unit emit the light A mode in which the axis is set within a range in which the angle of inclination toward the side opposite to the substrate is 5° and the angle of inclination toward the substrate is 15° with respect to a plane parallel to the surface of the substrate. can take

In this way, by arranging the plurality of light-emitting diodes in a ring, the substrate can be more uniformly illuminated by the second illumination section and the third illumination section. high visual inspection can be realized. Further, by setting the optical axis of the light-emitting diodes constituting the second lighting section at the above angle, the substrate surface can be more uniformly illuminated, and the optical axis of the light-emitting diodes constituting the third lighting section is at the above angle, the periphery of the substrate can be illuminated with higher illuminance.

As described above, according to the visual inspection apparatus according to the present invention, defects such as flaws, defects, and shape abnormalities in the metal film formed on the substrate, stains on the substrate surface, and chips and cracks formed on the peripheral edge of the substrate can be detected. It can be detected with high accuracy.

In addition, since the various defects described above can be determined with a single image taken by the imaging camera, the processing time for the appearance inspection can be shortened compared to the conventional method in which images are taken multiple times for each color of illumination. It is possible to perform the visual inspection more efficiently.

1 is an explanatory diagram showing the configuration of a visual inspection apparatus according to an embodiment of the present invention; FIG. It is an explanatory view for explaining an operation in the 1st illumination part concerning this embodiment. It is an explanatory view for explaining an operation in the 1st illumination part concerning this embodiment. It is an explanatory view for explaining an operation in the 1st illumination part concerning this embodiment. It is an explanatory view for explaining an operation in the 1st illumination part concerning this embodiment. It is an explanatory view for explaining the composition of the 2nd illumination part concerning this embodiment. It is an explanatory view for explaining the composition of the 3rd illumination part concerning this embodiment.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The inspection target of the appearance inspection apparatus of this example is a ceramic substrate having a gold film formed on its surface as an electrode and/or wiring, and having a rectangular shape in plan view.

As shown in FIG. 1, the visual inspection apparatus 1 of this embodiment is arranged above a transport device 2 for transporting a substrate K and an inspection position set on a transport path of the transport device 2. an imaging camera 5 that captures an image of the substrate K transported to a position; and an illumination that is disposed between the imaging camera 5 and the substrate K at the inspection position and illuminates the substrate K transported to the inspection position. A device 10, a control device 30 that controls the operations of the conveying device 2, the imaging camera 5, and the lighting device 10, and a determination device 35 that processes the image captured by the imaging camera 5 and determines whether the appearance of the substrate K is good or bad. and

The conveying device 2 includes a horizontally rotatable disk-shaped glass plate 3 and a driving motor (not shown) for horizontally rotating the glass plate 3. , the substrates K which are aligned by an appropriate alignment supply device (not shown) and sequentially supplied onto the glass plate 3 are transported in the direction of rotation thereof.

The illumination device 10 includes a first illumination section 11, a second illumination section 18, and a third illumination section 25 arranged between the imaging camera 5 and the glass plate 3 at the inspection position. . The first lighting unit 11, the second lighting unit 18 and the third lighting unit 25 are vertically arranged side by side. is provided.

The first illumination unit 11 has a rectangular shape in a plan view, and includes a cylindrical main body 12 with upper and lower openings, and a half mirror disposed in the main body 12 at an angle of approximately 45 degrees with respect to the horizontal plane. 13, a plurality of red LEDs 15 arranged in multiple rows and multiple columns so that the optical axis is oriented in the horizontal direction and provided so as to face the half mirror 13, a base 16 for holding the red LEDs 15, a red A glass plate 14 is arranged vertically between the LED 15 and the half mirror 13 and partitions the area where the red LED 15 is arranged and the area where the half mirror 13 is arranged. The main body 12 is open at the top and bottom of the region where the half mirror 13 is provided, and the top and bottom of the region where the red LED 15 is provided is closed with a lid. Also, the lighting of the red LED 15 is controlled by the controller 30 .

The first illumination unit 11 is arranged so that the half mirror 13 is positioned directly below the imaging camera 5 . In the first illumination unit 11, the red LED 15 irradiates the half mirror 13 with red light having directivity in the horizontal direction. It is reflected at an angle and the reflected light is projected onto the substrate K located in the lower inspection position. Such illumination is generally called coaxial illumination or epi-illumination.

The first illumination unit 11 mainly detects defects such as scratches, defects (including complete disconnection and partial disconnection), and shape abnormalities in the metal film (gold film) formed on the substrate K. The reason why the red LED 15 is used in this example is as follows.

That is, according to the findings of the present inventors, there are red metals such as gold and copper that reflect a lot of red light, and white metals such as silver, magnesium, and aluminum that reflect a lot of blue light. . The substrate K of this example uses a red LED because a gold film is formed as the metal film.

FIG. 2 is a diagram conceptually showing the state of reflection when a gold film is irradiated with red light having directivity in the vertical direction. Similarly, FIG. FIG. 4 is a diagram conceptually showing the state of reflection when green light having a directivity of 2 is irradiated, and FIG. FIG. 5 is a diagram conceptually showing the state of reflection when a gold film is irradiated with general white light having no directivity. In FIGS. 2 to 5, the shaded portion is the gold film, the dashed arrows indicate the irradiated light and the reflected light, and the dashed line indicates the brightness level of the reflected light.

As described above, gold is a reddish metal that reflects a large amount of red light and readily absorbs light of other colors. Therefore, when the gold film is irradiated with red light, as shown in FIG. 2, most of the light is specularly reflected on the smooth surface, so that the amount of reflected light is large and the reflected light exhibits a high luminance level. On the other hand, if there is a scratch S on the surface of the film, as shown in FIG. The luminance level of the portion where the

On the other hand, when a gold film is irradiated with green light or blue light, these lights are easily absorbed by the gold film, so the amount of reflected light is less than that of red light, and the brightness level of the reflected light is lower than that of red light. (See FIGS. 3 and 4). In addition, if there is a scratch S on the surface of the film, the portion of the scratch S is diffusely reflected, and the amount of light reflected upward is reduced. , there is no significant difference from the brightness level of the reflected light in the portion without the flaw S, so the presence or absence of the flaw S cannot be determined with a significant difference (see FIGS. 3 and 4). In addition, when the gold film is irradiated with non-directive white light, the reflected light exhibits a brightness level similar to that of the green light. There is no difference and this cannot be determined accurately (see Figure 5).

Thus, according to the first irradiation unit 11, since the amount of reflected light increases in the portion where the gold film is appropriately present, the luminance level is high, and when the gold film has a scratch S, the amount of reflected light increases. , the amount of reflected light is extremely reduced due to irregular reflection at the scratch S, and the luminance level is extremely low. If there is, the red irradiation light is absorbed by the defective portion and the amount of reflected light is extremely reduced, resulting in an extremely low luminance level.

Due to the above operation, it is possible to detect defects such as scratches, film defects, and shape abnormalities in the gold film formed on the substrate K. FIG. This also applies to reddish metals other than gold, such as copper.

The second lighting section 18 is arranged below the first lighting section 11 as described above, and has a support plate 19 provided with an opening penetrating vertically at a position corresponding to the opening of the main body 12. , a cylindrical member 20 attached to the lower surface of the support plate 19, and arranged in multiple rows and multiple rows on the inner peripheral surface of the cylindrical member 20, and green illumination light is directed toward the surface of the substrate K at the inspection position. and a diffusion film 22 provided inside the green LEDs 21 arranged in a ring. The lighting of the green LED 15 is controlled by the controller 30 .

The diffusion film 22 is a tapered annular film that expands in diameter downward, and has the effect of dispersing the directional green light emitted from the green LED 21 during its transmission. . Thus, the green light transmitted through the diffusion film 22 is uniformly applied to the surface of the substrate K, and the surface of the substrate K is illuminated with a uniform amount of light.

This second illumination unit 18 is mainly an illumination for detecting stains on the substrate K. As shown in FIG. According to the findings of the present inventors, green light has characteristics that its absorption rate differs depending on the color of the surface of the substrate K, that is, the amount of reflected light differs, and the luminance level of the reflected light also differs. Therefore, it is possible to determine whether or not the surface of the substrate K has dirt or the like on the basis of the change in the luminance level of the reflected light.

In order to uniformly illuminate the entire surface of the substrate K with a level of light that enables detection of contamination on the surface of the substrate K, the optical axis of the green LED 21 must be aligned with the substrate K as shown in FIG. It is preferable that the inclination angle toward the substrate K side, that is, the inclination angle toward the bottom is set within a range of 5° to 45° with respect to the plane R parallel to the surface.

The third illumination section 25 is arranged below the second illumination section 18, as described above, and has a ring-shaped member 26 having a diameter larger than that of the diffusion film 21, and an inner portion of the ring-shaped member 26. A plurality of blue LEDs 27 are arranged evenly in the circumferential direction on the peripheral surface and irradiate blue illumination light toward the peripheral edge of the substrate K at the inspection position. The lighting of the blue LED 27 is also controlled by the controller 30 .

The third illumination unit 25 is mainly used for detecting defects such as chips and cracks that occur on the peripheral edge of the substrate K. As shown in FIG. If there is a chip or crack on the peripheral edge of the substrate K, the light emitted from the blue LED 27 is diffusely reflected at the portion where the chip or crack exists. less and its brightness level will be lower. Therefore, it is possible to determine whether or not there is a defect such as chipping or cracking on the peripheral edge of the substrate K from the change in the luminance level of the reflected light.

The imaging camera 5 includes an element that detects red light (red light detection element), an element that detects green light (green light detection element), and an element that detects blue light (blue light detection element), It is configured to output image data detected by each element.

That is, the imaging camera 5 receives the reflected light emitted from the red LED of the first irradiation unit 11 toward the surface of the substrate K and reflected by the surface of the substrate K with the red photodetector, and detects the luminance level output image data according to Similarly, the imaging camera 5 receives the reflected light emitted from the green LED of the second irradiation unit 18 toward the surface of the substrate K and reflected by the surface of the substrate K with the green light detection element. It outputs image data according to the luminance level. In addition, the imaging camera 5 receives the reflected light emitted from the blue LED of the third irradiation unit 25 toward the surface of the substrate K and reflected by the surface of the substrate K with the blue light detection element, and measures the brightness of the light. Output image data according to the level.

The imaging camera 5 may have any configuration as long as it has the functions described above. line sensor), a line sensor in which a plurality of green light detection elements are arranged in a row (line sensor for green), and a line sensor in which a plurality of blue light detection elements are arranged in a row (line sensor for blue) , arranged side by side along the direction in which the substrate K is conveyed. In this case, the image data output from the line sensor for red, the line sensor for green, and the line sensor for blue are image data corresponding to each detected color.

Alternatively, the imaging camera 5 may be an area sensor camera in which red light detection elements, green light detection elements, and blue light detection elements are alternately arranged in a mosaic pattern. In this case, image data corresponding to red is formed by extracting the data output from the red light detection element among the data output from the area sensor camera, and the data output from the green light detection element is extracted. By doing so, image data corresponding to green is formed, and image data corresponding to blue is formed by extracting data output from the blue photodetector.

The judging device 35 is configured to judge whether the appearance of the board K is good or bad based on each image data corresponding to each detected color output from the imaging camera 5 . Specifically, the determination device 35 determines whether the appearance of the board K is good or bad as follows.

As described above, when the red LED of the first irradiation unit 11 irradiates the surface of the substrate K with red light, the portion where the gold film is properly present has a large amount of reflected light, so that the luminance level is high. If there is a scratch on the gold film, the light is diffusely reflected at the scratch and the amount of reflected light is extremely reduced, resulting in an extremely low luminance level. When the underlying ceramic portion is exposed, the red irradiation light is absorbed by the defective portion and the amount of reflected light is extremely reduced, resulting in an extremely low luminance level. Such reflected red light is detected by the red light detection element of the imaging camera 5 , and image data corresponding to red corresponding to the luminance level is output from the imaging camera 5 to the determination device 35 .

The determination device 35 generates a grayscale image by binarizing the image data corresponding to red with a predetermined threshold value, and compares the generated grayscale image with a reference grayscale image to determine whether the metal film is scratched or not. Defects and shape abnormalities are detected, and if damage, defects, or shape abnormalities are detected, the substrate K is determined to be defective.

The green light emitted from the green LED 21 of the second irradiation unit 18 to the surface of the substrate K has a different amount of reflected light depending on the color of the surface of the substrate K, and the reflected light varies depending on the color of the surface of the substrate K. corresponding luminance level. Then, such reflected light of green light is detected by the green light detection element of the imaging camera 5 , and image data corresponding to green corresponding to the luminance level is output from the imaging camera 5 to the determination device 35 .

The determination device 35 generates a gradation image by binarizing the image data corresponding to green with a predetermined threshold value, and compares the generated gradation image with a reference gradation image to determine the substrate K. The presence or absence of contamination on the surface is detected, and if contamination is detected, the substrate K is determined to be defective.

In addition, if there is a chip or crack on the peripheral edge of the substrate K, the blue light emitted from the blue LED of the third illumination unit 25 to the surface of the substrate K is diffusely reflected at the portion where the chip or crack exists. Therefore, the amount of light reflected toward the imaging camera 5 is smaller than that of the other portions, and the luminance level thereof is lowered. Such reflected light of blue light is detected by the blue light detection element of the imaging camera 5 , and image data corresponding to blue corresponding to the luminance level is output from the imaging camera 5 to the determination device 35 .

The determination device 35 generates a gradation image by binarizing the image data corresponding to blue with a predetermined threshold value, and compares the generated gradation image with a reference gradation image to determine the substrate K. Chipping and cracks generated on the peripheral edge are detected, and when chipping and cracks are detected, the substrate K is determined to be defective.

According to the appearance inspection apparatus 1 of this example configured as described above, from the red LED 15 of the first irradiation unit 11, the green LED 21 of the second irradiation unit 18, and the blue LED 27 of the third irradiation unit 25, , the substrate K is irradiated with red, green and blue light, respectively. Red light, green light and blue light reflected by the substrate K pass through the half mirror 13 and enter the imaging camera 5, respectively. Image data corresponding to each color detected by the detection element, the green light detection element, and the blue light detection element are output to the determination device 35 according to the luminance level thereof.

Next, the judging device 35 judges whether the appearance of the board K is good or bad based on the input image data corresponding to each color. Therefore, according to the visual inspection apparatus 1 of this embodiment, defects such as flaws, defects, and shape abnormalities in the metal film formed on the substrate K, stains on the surface of the substrate K, and chipping and cracks formed on the peripheral edge of the substrate K can be highly inspected. It can be detected with precision.

In addition, since the various defects described above can be discriminated with a single image taken by the image pickup camera 5, the processing time for the appearance inspection can be shortened compared to the conventional method in which images are taken multiple times for each color of illumination. can be performed, and the visual inspection can be performed more efficiently.

Although specific embodiments of the present invention have been described above, specific modes that the present invention can take are not limited to those described above.

For example, if the metal film formed on the substrate K is white, such as silver, magnesium, or aluminum, the red LEDs 15 are replaced with blue LEDs. In the case of whitish metals, since blue light is likely to be reflected, the above-described action is reversed between blue light and red light. Specifically, whitish metals reflect a large amount of blue light and tend to absorb light of other colors. It is specularly reflected, and the brightness level of the reflected light increases, but if there is a scratch, the blue light is diffusely reflected at the scratch, and the amount of reflected light in the upward direction is extremely small. The luminance level of the portion where the

On the other hand, when a white metal film is irradiated with green or red light, the light is easily absorbed by the gold film. will be relatively low. In addition, if the surface of the metal film has a scratch, the portion of the scratch causes diffuse reflection, and the amount of light reflected upward is reduced. Since there is no significant difference from the luminance level of the reflected light in the portion without the scratch, the presence or absence of the scratch cannot be determined with a significant difference.

Similarly, when there is a defect in the metal film and the underlying ceramic portion is exposed, the blue irradiation light is absorbed by the defect and the amount of reflected light is extremely reduced. extremely low.

When a whitish metal film is formed on the substrate K, by using blue light as the illumination light, defects in the metal film, such as flaws, defects, and shape abnormalities, can be eliminated. detection becomes possible. In this case, the blue LED 27 of the third illumination section 25 is replaced with a red LED.

REFERENCE SIGNS LIST 1 appearance inspection device 2 conveying device 5 imaging camera 10 lighting device 11 first lighting unit 13 half mirror 15 red LED
18 second lighting unit 21 green LED
22 diffusion film 25 third lighting unit 27 blue LED
K substrate

Claims (3)

An appearance inspection apparatus for inspecting the appearance of a substrate having a metal film formed on its surface,
a transport device for transporting the substrate;
an imaging camera disposed corresponding to an inspection position set on the transport path of the transport device and capturing an image of the substrate transported to the inspection position;
an illumination device disposed corresponding to the inspection position and illuminating the board conveyed to the inspection position;
a determination device that processes the image captured by the imaging camera and determines whether the appearance of the substrate is good or bad;
A control device that controls the conveying device, the imaging camera and the lighting device,
The imaging camera includes an element that detects red light, an element that detects green light, and an element that detects blue light, and is configured to output image data detected by each element,
The determination device is configured to determine whether the appearance of the substrate is good or bad based on each image data corresponding to each detected color output from the imaging camera,
The lighting device
a first illumination unit, the optical axis of which is set so as to be orthogonal to the surface of the substrate at the inspection position , and which emits light of either blue or red;
With respect to the substrate at the inspection position, it is arranged closer to the substrate than the first illumination unit, and includes a plurality of light sources arranged in a ring shape, and a ring-shaped diffusion film provided inside the light sources. a second illumination unit that irradiates the surface of the substrate at the inspection position with green light that has passed through the diffusion film ;
With respect to the substrate at the inspection position, a plurality of illumination devices arranged closer to the substrate than the second illumination unit and annularly arranged radially outside the diffusion film of the second illumination unit a third illumination unit that includes a light source and emits blue or red light of a different color from the illumination light of the first illumination unit toward the surface of the substrate at the inspection position ;
When the substrate is transported to the inspection position, the control device illuminates the substrate by simultaneously irradiating light from the first illumination unit, the second illumination unit, and the third illumination unit, and An appearance inspection apparatus , wherein an image of the substrate is captured by the imaging camera . 2. The visual inspection apparatus according to claim 1, wherein each of said first illumination section, said second illumination section, and said third illumination section comprises a plurality of light emitting diodes as light sources. The light-emitting diodes constituting the second illumination unit have an optical axis tilted toward the substrate at an angle of 5° to 45° with respect to a plane parallel to the surface of the substrate at the inspection position. and the optical axis of the light-emitting diode constituting the third illumination unit is inclined at an angle of 3. The visual inspection apparatus according to claim 2, wherein the inclination angle is set within a range of 5[deg.] and an inclination angle toward the substrate side of 15[deg.].

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