JPH11304714A - Method for inspecting both front and rear surfaces of transparent plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a scratch and dust on the front and reverse sides of a transparent plate to be recognized, by comparing images that are picked up using an image pick-up means with different image pick-up angles from the entire surface of the transparent plate, while relatively moving the image pick-up means and the transparent plate from one end part to the other of the transparent plate. SOLUTION: The image of the entire part of the surface of a transparent plate that is placed on the upper surface of a movable table 1 is picked up by two image pick-up means 5 and 6 with different image pick-up angles θ1, while moving a transparent plate 4 in a direction marked by an arrow 3 from one end part to the other for the image pick-up means 5 and 6. The images of a scratch and dust that exist on a front surface 4a and a rear surface 4b in the transparent plate 4 appear in the image being picked up by the image pickup means 5 and 6. Since the image pick-up means 5 and 6 are provided with telecentric optical systems 7 and 8, the picked-up image loses perspective and the sizes of the scratch and dust on the front and rear surfaces 4a and 4b of the transparent plate become equal. Therefore, by comparing the images being picked up by the image pick-up means 5 and 6 with a CPU, they are processed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent plate for a liquid crystal display device or the like, which optically distinguishes scratches on the front and back surfaces and dust and the like adhering to the front and back surfaces. It relates to the inspection method.

[0002]

2. Description of the Related Art As is well known, a very common liquid crystal display device is composed of two transparent plates, which are filled with liquid crystal therebetween and overlapped with each other. The structure is such that a transparent protective film is attached to the surface of one transparent plate on the display side, and a polarizing film is attached to the back surface of the other transparent plate.

However, during the production of this liquid crystal display element, not only the front and back surfaces of both transparent plates may be scratched or dusty, but also the protective film and the polarizing film may be scratched or dusty. May be attached, and these scratches and / or dust shadows appear as defects in characters or figures displayed when the liquid crystal display element is turned on.

Therefore, conventionally, an image photographed with the surface of the liquid crystal display element turned off and an image photographed with the surface of the liquid crystal display element turned on are combined, and the combined image is damaged and / or damaged. Alternatively, the presence or absence of the flaw and / or dust is inspected by comparing an image taken in a state where the surface of a non-defective liquid crystal display element having no dust shadow is lit.

[0005]

However, this method is
The presence or absence of scratches and / or dust in the area of the liquid crystal display element that appears as a character or figure displayed when lit can be recognized, but the part of the liquid crystal display element other than the area that appears as a character or figure when lit. However, since the presence or absence of scratches and / or dust cannot be recognized, there is a problem that the presence or absence of scratches and / or dust cannot be inspected over the entire surface of the liquid crystal display element.

[0006] The present invention solves this problem, and the presence or absence of scratches and / or dust on both the front and back surfaces, and whether the scratches and / or dust is present on one or both of the front and back surfaces. Quickly and over the entire surface
An object of the present invention is to provide an inspection method that can be surely recognized.

[0007]

In order to attain this technical object, the present invention provides a method for producing a transparent plate, comprising the steps of providing at least two photographing surfaces each having a telecentric optical system and having different photographing angles. By means, the photographing means and the transparent plate are photographed while relatively moving from one end to the other end of the transparent plate, and the images photographed by each photographing means are compared with each other. I do. "

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. In the figure, reference numeral 1 denotes a movable table configured to move in the direction of arrow 3 by an actuator 2.
A transparent plate 4 to be inspected for the presence or absence of scratches or dust on the front surface 4a and / or the back surface 4b is placed on the upper surface of the substrate.

Above the movable table 1, a first photographing means 5 such as a CCD camera and a second photographing means 6 also like a CCD camera are provided with a transparent plate 4 mounted on the movable table 1.
Is arranged downward so as to photograph the surface 4a of the camera.
One of the first photographing means 5 of each of the photographing means 5 and 6,
For example, if the transparent plate 4 is perpendicular to the transparent plate 4, the other second photographing means 6 is appropriately inclined with respect to the first photographing means 5 by an angle θ1.
The surface 4a is photographed by changing the photographing angle by the two photographing means 5 and 6.

One of the first and second photographing means 5 and 6 has a convex lens 7a and this lens 7a.
Is mounted with a telecentric optical system 7 comprising a stop 7b provided at a position of a front focal point 7a ', and the other second photographing means 6 has a convex lens 8a and this lens 8a.
A telecentric optical system 8 including a stop 8b provided at the front focal point 8a 'in FIG.

Each of the photographing means 5 and 6 is provided with a lens 7 of a telecentric optical system 7 and 8 mounted on each of them.
It is needless to say that the transparent plate 4 is provided at a position where the front surface 4a and the back surface 4b of the transparent plate 4 are located within the range of the depth of focus with respect to the rear focal point in FIGS. Reference numeral 9 denotes a central processing unit (CPU). The central processing unit (CPU) 9 operates the movable table 1, each of the photographing means 5, 6 and illumination means (not shown) to thereby control the movable table 1 The surface 4a of the transparent plate 4 placed on the transparent plate 4
, While controlling in such a manner as to capture the entirety from one end 4c to the other end 4d while moving in the direction of, and processing the images taken by the respective photographing means 5 and 6 as described below. Furthermore, this central processing unit (CP
U) 9 is connected to a monitor television 10 for displaying the image.

The entire surface of the transparent plate 4 placed on the upper surface of the movable table 1 is photographed by the two photographing means 5 and 6 having different photographing angles θ1. When the image is taken while moving in the direction of arrow 3 from one end to the other end of the means 5 and 6, the images taken by the two image taking means 5 and 6 include the surface 4 a of the transparent plate 4. The image of the existing scratches and / or dust appears, and at the same time, the image of the scratches and / or dust existing on the back surface 4b of the transparent plate 4 also appears.

Moreover, each of the two photographing means 5, 6
The provision of the telecentric optical systems 7 and 8 eliminates the perspective in the captured images, and the images of the scratches and / or dust on the front surface 4a of the transparent plate 4 and the back surface 4b of the transparent plate 4 respectively. The wound and / or dust image will appear the same size. Therefore, the images photographed by the photographing means 5 and 6 are transferred to a central processing unit (CPU) 9.
Thus, image processing is performed so as to be compared with each other.

In this case, for example, as shown in FIG. 2, four scratches and / or dusts A1, A2, A3, and A4 are arbitrarily formed only on the surface 4a of the transparent plate 4 along the moving direction indicated by the arrow 3. Are present at the intervals L 1, L 2, L 3, the image taken by moving the surface 4 a of the transparent plate 4 in the direction shown by the arrow 3 by the first photographing means 5 includes:
As shown in FIG. 3, each scratch and / or dust A on the surface 4a
Four images A1 ', A at 1, A2, A3, A4
2 ', A3', A4 'are each scratch and / or dust A1, A
2, A3 and A4 appear at intervals L1 ', L2' and L3 'corresponding to intervals L1, L2 and L3. As shown in FIG. 4, the images taken while moving include each of the scratches and / or dust A1, A2, A on the surface 4a.
Four images A1 ", A2", A3 ", A in 3 and A4
4 ″ is an interval L1 ″, L corresponding to the interval L1, L2, L3 of each scratch and / or dust A1, A2, A3, A4.
2 ", L3".

Therefore, comparing the image shown in FIG. 3 photographed by the first photographing means 5 with the image shown in FIG. 4 photographed by the second photographing means 6, each image A 1 in the image shown in FIG. , A2 ', A3', A4 '
1 ', L2', L3 'and the distance L between the images A1 ", A2", A3 ", A4" in the image shown in FIG.
1 ", L2", and L3 "are the same as in FIG.
A1 ', A2', A3 ', A in the image shown in FIG.
4 'and images A1 ", A2",
Since A3 "and A4" have the same arrangement,
The transparent plate 4 has scratches and / or dust A1, A2, A3,
A4 is present and each of these scratches and / or dust A
It can be seen that 1, A2, A3, and A4 exist only on the surface 4a of the transparent plate 4.

For example, as shown in FIG. 5, only three scratches and / or dust B are formed on the rear surface 4b of the transparent plate 4.
When 1, B2 and B3 are present at arbitrary intervals S1 and S2 along the movement direction indicated by the arrow 3, the surface 4a of the transparent plate 4 is moved by the first photographing means 5 in the direction indicated by the arrow 3. In the photographed image, as shown in FIG. 6, three images B1 ', B2', and B3 'on each of the scratches and / or dust B1, B2, and B3 on the back surface 4b are included in each of the scratches and / or dust B.
Intervals corresponding to intervals S1, S2 of intervals 1, 1, B2, B3
1 'and S2', an image taken while moving the front surface 4a of the transparent plate 4 in the direction indicated by the arrow 3 by the second photographing means 6 includes the back surface 4a as shown in FIG.
The three images B1 ″, B2 ″, B3 ″ at each of the scratches and / or dust B1, B2, B3 of FIG.
The interval S corresponding to the intervals S1 and S2 of the intervals B2 and B3
1 "and S2".

Therefore, comparing the image shown in FIG. 6 photographed by the first photographing means 5 with the image shown in FIG. 7 photographed by the second photographing means 6, each image B1 in the image shown in FIG. ', B2', B3 ', the spacing S1', S2 '
And images B1 ″, B2 ″, B in the image shown in FIG.
While the distances S1 "and S2" between 3 "are the same,
Scratches and / or images in the image taken by the first photographing means 5
Or each image B1 ', B2', B3 'of dust B1, B2, B3
And images B1 ″, B2 ″, B of the flaws and / or dust B1, B2, B3 in the image photographed by the second photographing means 6.
3 "means that the first photographing means 5 and the second photographing means 6 are shifted from each other by the distance E along the moving direction indicated by the arrow 3 by appropriately setting the inclination angles different from each other by the angle θ1. Is detected, the transparent plate 4 has scratches and / or dust B1, B2, and B3, and furthermore, each of these scratches and / or dust B1, B2, and B3.
3 is found to be present only on the back surface 4b of the transparent plate 4.

Further, for example, as shown in FIG. 8, four scratches and / or dust A are formed on the surface 4a of the transparent plate 4.
In addition to the fact that 1, A2, A3 and A4 exist at arbitrary intervals L1, L2 and L3 along the movement direction shown by arrow 3,
If three scratches and / or dust B1, B2, and B3 also exist on the back surface 4b of the transparent plate 4 at arbitrary intervals S1 and S2 along the movement direction indicated by the arrow 3, the front surface 4a of the transparent plate 4 As shown in FIG. 9, the image photographed while moving in the direction indicated by arrow 3 by the first photographing unit 5 includes
Each scratch and / or dust A1, A on the surface 4a of the transparent plate 4
Four images A1 ', A2', A at 2, A3, A4
3 ', A4' is each wound and / or dust A1, A2, A3,
Interval L corresponding to interval L1, L2, L3 of A4
At the same time as appearing at 1 ', L2', L3 ', each of the three images B1', B2 ', B3' on the back surface 4b of the transparent plate 4 and / or the dusts B1, B2, B3 is formed by each of the scratches and / or Dust B
Intervals corresponding to intervals S1, S2 of intervals 1, 1, B2, B3
Appears at 1 ', S2'.

However, the image A appearing in the image of FIG.
1 ', A2', A3 ', A4' and B1 ', B2', B
With only 3 ′, it is not possible to recognize whether each of the scratches and / or dust appearing on these images exists on the front surface 4a or the back surface 4b of the transparent plate 4, and the front surface 4a When one of the scratches and / or dust A1 on the back surface 4b overlaps with one of the scratches and / or dust B1 on the back surface 4b when viewed from the shooting direction by the first shooting means 5, in the image of FIG. Since one image B1 'of one scratch and / or dust B1 on 4b will be hidden by one image A1' of one scratch and / or dust A1 on the front surface 4a, one scratch and / or dust B1 on the back surface 4b. Can not recognize the existence of.

On the other hand, as shown in FIG. 10, the image taken by moving the surface 4a of the transparent plate 4 by the second photographing means 6 in the direction indicated by the arrow 3 includes, as shown in FIG. Alternatively, four images A1 ", A2", A3 ", and A4" on the dusts A1, A2, A3, and A4 are formed at intervals L1, L2, and L3 of the scratches and / or dusts A1, A2, A3, and A4.
At the same time as the intervals L1 ", L2", L3 ", and at the same time, each scratch and / or dust B1, B2, B3
Are appeared at intervals S1 ", S2" corresponding to the intervals S1, S2 of the scratches and / or dust B1, B2, B3, and the back surface 4b.
The three images B1 ", B2", B3 "of each of the scratches and / or dust B1, B2, B3 are obtained by appropriately setting the first photographing means 5 and the second photographing means 6 to different inclination angles from each other by an angle θ1. , Each scratch and / or dust A1, A on the surface 4a
Four images A1 ″, A2 ″, A in 2, A3 and A4
3 "and A4" are shifted by a distance E along the movement direction indicated by arrow 3.

However, the image A appearing in the image of FIG.
1 ', A2', A3 ', A4' and B1 ', B2', B
With only 3 ', it is not possible to recognize which of the front surface 4a and the rear surface 4b of the transparent plate 4 each of the scratches and / or dust appearing these images is. Therefore, comparing the image shown in FIG. 9 taken by the first photographing means 5 with the image shown in FIG. 10 taken by the second photographing means 6, the image shown in FIG. Or each image A1 ', A by dust A1, A2, A3, A4
The distances L1 ', L2', 2 ', A3', A4 '
L3 'and back surface 4b scratches and / or dust B1, B2, B3
The distance S between the images B1 ', B2', B3 '
1 ', S2' and the images A1 ", A2", A of the surface 4a by A1, A2, A3, A4 in the image shown in FIG.
The distance L1 ", L2", L3 "between 3" and A4 "and the distance S1" between the respective images B1 ", B2", B3 "due to the scratches and / or dust B1, B2, B3 on the back surface 4b. , S
2 ″ is the same, while the scratches and / or dusts A1, A2, A3, A4 in the image captured by the first
And images A1 ', A2', A3 'of B1, B2, B3,
A4 'and B1', B2 ', B3' and scratches and / or dust A1, A in the image photographed by the second photographing means 6.
2, A3, A4 and B1, B2, B3 images A1 ″, A
2 ", A3", A4 "and B1", B2 ", B3" mean that the first photographing means 5 and the second photographing means 6 have different inclination angles by an appropriate angle .theta. Since it is displaced by the distance E along the direction, by detecting the presence of this dislocation, the transparent plate 4 is provided with scratches and / or dust A1, A2, A3, A4 and B
1, B2 and B3 are present, and each of these wounds and / or
Or dust A1, A2, A3, A4 and B1, B2, B3
Is found to exist over both the front surface 4a and the back surface 4b of the transparent plate 4.
Scratches and / or dust on the surface 4a
Or, even if it overlaps with dust, the presence of the scratches and / or dust on the back surface 4b can be surely recognized.

When the object to be inspected is a two-layered transparent plate such as a liquid crystal display device, as shown in FIG. Third photographing means 1 having telecentric optical system 12
1 to the second photographing means 6 at an appropriate angle θ2 (provided that θ
By disposing at different photographing angles by 2 ≠ θ1), all of the overlapping scratches and / or dust when viewed from the second photographing means 6 can be recognized.

In the above-described embodiment, the photographing means 5, 6, 11 are immovable, and the transparent plate 4, which is the object to be inspected, is moved in the direction of the arrow 3. The present invention is not limited to this, and each of the photographing means 5, 6, and 11 may be configured to move in the direction of the arrow 3 while the transparent plate 4 to be inspected is immovable. , 6,1
Needless to say, both the transparent plate 1 and the transparent plate 4 may be moved at the same time.

[0024]

As described above, the present invention provides:
The entire surface of the transparent plate is telecentric optical system, and at least two photographing means having photographing angles different from each other, the respective photographing means and the transparent plate are relatively moved from one end to the other end of the transparent plate. The images taken by the respective photographing means are compared with each other to determine whether or not there are scratches and / or dust on both the front and back surfaces of the transparent plate, and whether the scratches and / or dust are present. It is possible to quickly and reliably recognize whether dust exists on one or both of the front surface and the back surface over the entire surface of the transparent plate.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part showing a case where scratches and / or dust are present on the surface of a transparent plate.

FIG. 3 is a photographed image by a first photographing means in FIG. 2;

FIG. 4 is an image photographed by a second photographing means in FIG. 2;

FIG. 5 is an enlarged sectional view of a main part showing a case where scratches and / or dust are present on the back surface of the transparent plate.

FIG. 6 is an image photographed by a first photographing means in FIG. 5;

FIG. 7 is an image captured by a second image capturing means in FIG.

FIG. 8 is an enlarged sectional view of a main part showing a case where scratches and / or dust are present on the front and back surfaces of the transparent plate.

FIG. 9 is a photographed image by a first photographing means in FIG.

FIG. 10 is an image captured by a second image capturing unit in FIG.

[Explanation of symbols]

 Reference Signs List 1 movable table 3 moving direction 4 transparent plate 4a surface of transparent plate 4b back surface of transparent plate 5 first photographing means 6 second photographing means 11 third photographing means 7, 8, 12 telecentric optical system 9 central processing unit (CPU) 10 Monitor tv

Claims (1)

[Claims] 1. The entire surface of a transparent plate is provided with at least two photographing means each having a telecentric optical system and having a photographing angle different from each other. A method of inspecting both front and back sides of a transparent plate, wherein images are taken while moving from one end to the other end of the transparent plate, and images taken by the respective photographing means are compared with each other.