JP2000074849A - Foreign matter detecting method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a foreign matter in the reverse side from the obverse side of a specimen having light transmittability. SOLUTION: An image-picking-up means 12 is focused on the obverse B1 of a specimen B from an obverse B1 side of the specimen B to be image-picked up, and a foreign matter P in the obverse B1 side of the specimen B is detected based on a picked-up image. The means 12 is focused on the reverse B2 of the specimen B from the obverse B1 side of the specimen B to be image-picked up, and the foreign matter P is detected based on a picked-up image. The foreign matter P in the obverse B1 side of the specimen B detected at the time of the obverse image-picking up of the specimen B is compared with the foreign matter P detected at the time of the reverse image-picking up of the specimen B to detect the foreign matter P in the reverse B2 side of the specimen B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and an apparatus for detecting foreign matter on the back side of a test object having optical transparency.

[0002]

2. Description of the Related Art Conventionally, for example, in the production of a liquid crystal display panel, particle inspection has been performed for inspecting the degree of adhesion of foreign matter (particles) to the front and back surfaces of a glass substrate on which processes such as film formation are performed.

In this particle inspection, for example, the optical system of the imaging means is focused on the surface of the glass substrate, and the surface of the glass substrate is irradiated with light and imaged by the imaging means.
A foreign substance on the front surface side of the glass substrate is detected from the degree of light scattering based on the captured image information.

Further, when detecting foreign matter on the back side of the glass substrate, the front and back surfaces of the glass substrate are inverted, and the back surface of the glass substrate is opposed to the optical system of the image pickup means, and the focus of the optical system of the image pickup means is changed. Is aligned with the back surface of the glass substrate, the back surface of the glass substrate is irradiated with light, and an image is taken by the imaging means to detect a foreign substance on the back surface side of the glass substrate.

[0005]

However, in the conventional particle inspection, when a foreign substance on the back surface of the glass substrate is detected, a step of inverting the front and back surfaces of the glass substrate is required. This time increases, and the degree of adhesion of the inspected foreign matter on the front surface side may change while the front and back surfaces of the glass substrate are reversed, and there is a problem that foreign matter detection is not reliable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a foreign matter detection method and apparatus capable of detecting foreign matter from the front side to the back side of an inspection object.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided an image pickup apparatus in which the image pickup means focuses an image from the front side of an object having optical transparency to the back surface of the object and focuses the image on the back side of the object. By detecting the foreign matter on the back side of the sample, the foreign matter on the back side is detected from the front side of the inspection object.

The present invention is also directed to a method of imaging an object from the front side of a light-transmitting inspection object by focusing the imaging means on the surface of the inspection object, and extracting the image from the captured image to the surface side of the inspection object. Foreign matter is detected, an image is taken from the front side of the object to be inspected by focusing on the back surface of the object to be inspected, foreign matter is detected from the captured image, and the object detected when the surface of the object is imaged is detected. By comparing the foreign matter on the front side of the inspection object with the foreign matter detected at the time of imaging the back surface of the inspection object, detecting the foreign matter on the rear side of the inspection object, the foreign matter from the front side to the rear side of the inspection object. Is accurately detected.

Further, by moving the image pickup means and the object to be inspected relatively and moving the image pickup position of the object to be inspected by the image pickup means, foreign substances are detected in a predetermined detection area of the object to be inspected. .

Further, by irradiating light from the surface side of the object to be inspected, the foreign matter is reliably detected by the degree of scattering of the light applied to the foreign matter.

Further, by associating the imaging position of the object to be inspected with the illumination position, the foreign matter is reliably irradiated with the light and the foreign matter is reliably detected.

According to the present invention, there is provided an image pickup means for picking up an image from the front side of a light-transmitting object by focusing on a back surface of the object, and an image pick-up device based on an image picked up by the image pickup means. Detecting means for detecting foreign matter on the back side of the inspection object allows foreign matter on the back side to be detected from the front side of the inspection object.

Further, the present invention provides an image pickup means for picking up an image from the front side of an object having light transmissivity and focusing on the front and back surfaces of the object, respectively.
Detecting foreign matter on the front side of the object to be inspected from an image captured by focusing the imaging unit on the surface of the object to be inspected, and detecting an image captured by focusing the imaging unit on the back surface of the object to be inspected. Detecting means for detecting foreign matter; comparing the foreign matter on the front side of the inspection object detected by the detection means when imaging the front surface of the inspection object with the foreign matter detected when imaging the back surface of the inspection object; The provision of the calculating means for detecting foreign matter on the back side of the object enables accurate detection of the foreign matter on the back side from the front side of the inspection object.

Further, a moving means for relatively moving the image pickup means and the object to be inspected and moving the image pickup position of the object by the image pickup means is provided. The detection of foreign matter is performed for.

Furthermore, the provision of the illuminating means for irradiating light from the surface side of the object to be inspected makes it possible to reliably detect the foreign matter due to the scattering of the light applied to the foreign matter.

Further, by associating the imaging position of the object to be inspected by the imaging means with the illumination position by the illumination means, the light is reliably applied to the foreign matter and the foreign matter is reliably detected.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In the figure, a foreign matter detector attaches, for example, to the front and back surfaces of a flat glass substrate B, which is a light-transmitting object to be inspected and performs processing such as film formation in the manufacture of a liquid crystal display panel. Foreign matter (particle) P
Is used for particle inspection for detecting (inspection). Regardless of the actual front surface and back surface of the glass substrate B, one surface of the foreign matter detection device that is imaged facing the later-described imaging unit 12 is defined as a front surface B1, and the other surface opposite to the imaging unit 12 is defined as a back surface B2. explain.

The foreign matter detecting apparatus has a stage 11 as a moving means on which the glass substrate B is placed with the surface B1 facing upward, and the stage 11 moves the glass substrate B in the X direction and the Y direction, respectively. Be moved.

Above the stage 11, an image pickup means 12 is provided. The image pickup means 12 includes an image pickup device 13 such as a CCD, and an optical system 14 such as a lens that forms an image on the image pickup device 13. The optical axes of the image pickup device 13 and the optical system 14 The glass substrate B is disposed so as to be perpendicular to the surface B1, that is, configured to capture an image in a direction perpendicular to the surface B1 of the glass substrate B.

Illumination means 15 is provided on the side of the stage 11. The illuminating means 15 includes a light source unit 16 having a lamp (not shown) and an optical system 17 such as a lens for controlling light L emitted from the light source unit 16 and irradiating the light L from the surface B1 side of the glass substrate B. , The light L is incident on the surface B1 of the glass substrate B at a predetermined angle α.

The imaging position (the front surface B1 and the back surface B2 of the glass substrate B) by the imaging means 12 and the illumination position by the illumination means 15 correspond to each other.

The image pickup device 13 is connected through an image processing section 18 to an arithmetic processing section 19 having the functions of detecting means and calculating means.

The function of the detecting means of the arithmetic processing unit 19 is to detect foreign matter P on the surface B1 side of the glass substrate B from an image taken by focusing the surface of the glass substrate B by the imaging means 12, and The foreign matter P is detected from an image captured by focusing the imaging means 12 on the back surface B2 of the substrate B.

The function of the calculating means is to compare the foreign matter P on the front surface B1 side of the glass substrate B detected at the time of imaging the front surface of the glass substrate B with the foreign matter P detected at the time of imaging the back surface of the glass substrate B. The foreign matter P on the back surface B2 side of B is detected. In this embodiment, the surface of the glass substrate B
The number of foreign matter P on the B1 side is n1, and the foreign matter P detected during backside imaging
N, the total number of the foreign substances P on the front and back surfaces of the glass substrate B, and the number n2 of the foreign substances P on the back surface B2 side of the true glass substrate B
Then, the number n2 of the foreign substances P on the back surface B2 side of the true glass substrate B is obtained from the equation of n−n1 = n2.

The stage 11 has a drive unit 20 for moving the stage 11 in the X direction and the Y direction. The drive unit 20 is controlled by the arithmetic processing unit 19.

Next, a method for detecting foreign matter will be described.

After setting the glass substrate B on the stage 11, the focus of the optical system 14 of the imaging means 12 is adjusted to the surface B1 of the glass substrate B as shown in FIG.
Is irradiated from the front surface B1 side of the glass substrate B, and is imaged by the imaging means 12. The arithmetic processing unit 19 detects the foreign matter P on the surface B1 side of the glass substrate B from the degree of scattering of the light L by the foreign matter P based on the captured image information. Further, by moving the glass substrate B by the stage 11 and moving the imaging position (detection position) of the glass substrate B, the entire glass substrate B is imaged (detected), and foreign matter on the surface B1 side of the glass substrate B is detected. Find the number n1 of P.

As shown in FIG. 1B, the focus of the optical system 14 of the imaging means 12 is adjusted to the back surface B2 of the glass substrate B, and the illumination means
The light L of 15 is emitted from the surface B1 side of the glass substrate B, and is imaged by the imaging means 12. The arithmetic processing unit 19 detects the foreign matter P from the degree of scattering of the light L by the foreign matter P based on the captured image information. Further, the glass substrate B is moved by the stage 11, and the imaging position (detection position) of the glass substrate B is moved, so that the entire glass substrate B is imaged (detected). Since the foreign matter P on the front surface B1 is detected together with the foreign matter P on the side, the number n obtained by adding the number of foreign matter P on the front and back surfaces of the glass substrate B is obtained as the number of foreign matter P detected at the time of imaging the back surface.

Then, the arithmetic processing section 19 obtains the number n2 of the foreign substances P on the back surface B2 side of the true glass substrate B from the equation of n−n1 = n2. Therefore, the foreign matter P on the surface B1 side of the glass substrate B
N1 and the number n2 of foreign matter P on the back surface B2 side of the glass substrate B
Can be detected.

As described above, since the imaging means 12 focuses on the back surface B2 of the glass substrate B from the front surface B1 side of the glass substrate B and picks up an image, and detects the foreign matter P from the picked-up image,
Foreign matter P on the back surface B2 side from the front surface B1 side of the glass substrate B can be detected. Therefore, when detecting the foreign matter P on the back surface B2 of the glass substrate B, there is no need to invert the front and back surfaces of the glass substrate B as in the related art, so that the inversion process can be reduced and the time required for inspection can be shortened. In addition, while the front and back surfaces of the glass substrate B are reversed, the adhesion of the foreign matter P on the inspected surface does not change, and the foreign matter P can be reliably detected.

Further, the image pickup means 12 focuses on the surface B1 of the glass substrate B from the surface B1 side of the glass substrate B and picks up an image.
And, from the front surface B1 side of the glass substrate B, focus the image pickup means 12 on the back surface B2 of the glass substrate B and take an image,
The foreign matter P is detected from the captured image, and the foreign matter P on the front surface B1 side of the glass substrate B detected at the time of imaging the front surface of the glass substrate B is compared with the foreign matter P detected at the time of imaging the back surface of the glass substrate B. Accordingly, the foreign matter P on the back surface B2 side of the glass substrate B is detected, so that the foreign material P on the back surface B2 side from the front surface B1 side of the glass substrate B can be accurately detected.

Further, by irradiating the light L from the surface b1 side of the glass substrate B by the illuminating means 15, the foreign matter P can be reliably detected by the degree of scattering of the light L applied to the foreign matter P. At this time, by associating the imaging position (the front surface B1 and the back surface B2) of the glass substrate B by the imaging means 12 with the illumination position by the illumination means 15, the light L is reliably irradiated onto the foreign matter P, and Can be detected.

The correspondence between the imaging position (front surface B1 and back surface B2) of the glass substrate B by the imaging unit 12 and the illumination position by the illumination unit 15 is usually determined even when the imaging unit 12 and the illumination unit 15 are in a fixed state. Can be positively dealt with, but for example, the imaging unit 12 may be offset in the irradiation direction of the light L from the illumination unit 15 (for example, as compared with the case where the surface B1 of the glass substrate B is imaged). The optical system 14 in FIG. 1A may be offset to the right, or the irradiation angle α or the irradiation position of the light L of the illumination means 15 may be changed. Irradiation is reliably performed by P, and the foreign substance P can be detected more reliably.

Further, by providing two imaging means 12 for imaging the front surface B1 of the glass substrate B and for imaging the rear surface B2, foreign substances P on the front surface B1 and the rear surface B2 of the glass substrate B can be simultaneously detected. And the detection efficiency can be improved.

Further, the imaging means 12 and the illumination means 15 may be moved with respect to the glass substrate B by moving means.
Alternatively, the glass substrate B and the imaging means 12 and the illumination means 15 may be moved respectively, and in any case, the imaging means
12 and the glass substrate B are relatively moved so that the imaging means 12
The foreign substance P can be detected in a predetermined detection area of the glass substrate B by moving the imaging position of the glass substrate B by the method.

The object to be inspected is not limited to the glass substrate B of the liquid crystal display device, and the same operation and effect can be obtained by applying the invention to other objects having an optical transparency.

[0038]

According to the present invention, an image is picked up from the front side of a light-transmitting inspection object to the back surface of the inspection object by focusing the imaging means, and a foreign substance is detected from the picked-up image. In addition, it is possible to detect foreign matter on the back side from the front side of the inspection object.

Further, the imaging means focuses on the surface of the object to be inspected from the surface side of the object to be inspected, which is light-transmissive, and detects foreign matter on the surface side of the object from the captured image. Also, from the front side of the object to be inspected, the imaging means focuses on the back surface of the object to be imaged, detects foreign matter from the imaged image, and detects the foreign object detected at the time of imaging the surface of the object to be inspected. Since the foreign matter on the back side of the inspection object is detected by comparing the foreign matter on the front side of the inspection object with the foreign matter detected at the time of imaging the back side of the inspection object, the foreign matter on the back side of the inspection object is detected. Can be detected accurately.

[Brief description of the drawings]

1A and 1B show an embodiment of a foreign matter detection method and apparatus according to the present invention, wherein FIG. 1A is an explanatory view showing a foreign matter detection state on the front surface of an inspection object, and FIG. FIG. 9 is an explanatory diagram illustrating a detection state.

FIG. 2 is a perspective view of the foreign matter detection device.

[Explanation of symbols]

11 Stage as moving means 12 Imaging means 15 Illumination means 19 Arithmetic processing unit having functions of detecting means and calculating means B Glass substrate as inspection object B1 Front surface B2 Back surface

Claims (10)

[Claims] 1. An image pickup device, which focuses an image on a back surface of an object to be inspected from the front side of the object having optical transparency and picks up an image, and detects a foreign substance on the back side of the object from an image taken. A foreign matter detection method, characterized in that: 2. An image pickup device focuses on the surface of the object to be inspected from the surface side of the object to be inspected having optical transparency and picks up an image, and detects foreign matter on the surface side of the object to be inspected from the picked-up image. An image is taken from the front side of the inspection object by focusing the imaging means on the back surface of the inspection object, foreign matter is detected from the captured image, and the surface of the inspection object detected at the time of imaging the surface of the inspection object The foreign matter detection method according to claim 1, wherein the foreign matter on the back side of the inspection object is detected by comparing the foreign matter on the back side of the inspection object with the foreign matter detected at the time of imaging the back surface of the inspection object. 3. The foreign matter detection method according to claim 1, wherein the imaging means and the object to be inspected are relatively moved to move the imaging position of the object to be inspected by the imaging means. 4. The foreign matter detection method according to claim 1, wherein light is irradiated from the front side of the inspection object. 5. The foreign matter detection method according to claim 4, wherein the imaging position of the inspection object and the illumination position are associated with each other. 6. An imaging means for focusing and imaging the back surface of the inspection object from the front side of the inspection object having optical transparency, and an image pickup means for imaging the back surface of the inspection object from the image captured by the imaging means. A foreign matter detecting device, comprising: detecting means for detecting foreign matter. 7. An image pickup means for picking up an image from the front side of a light-transmitting object to be inspected with respect to a front surface and a back surface of the object to be inspected, and imaging the front surface of the object to be inspected. Detecting means for detecting foreign matter on the front side of the inspection object from an image captured by focusing the means, and detecting foreign matter from the image captured by focusing the imaging means on the back surface of the inspection object, The detecting means compares the foreign matter on the front side of the inspection object detected at the time of imaging the front surface of the inspection object with the foreign matter detected at the time of imaging the rear surface of the inspection object, and detects the foreign matter on the back side of the inspection object. A foreign matter detection device, comprising: 8. The apparatus according to claim 6, further comprising a moving unit that relatively moves the imaging unit and the object to be inspected, and moves an imaging position of the object to be inspected by the imaging unit. Foreign matter detection device. 9. An illumination device for irradiating light from the front side of an object to be inspected.
The foreign matter detection device according to any of the above. 10. The foreign matter detection device according to claim 9, wherein an imaging position of the object to be inspected by the imaging means is made to correspond to an illumination position by the illumination means.