JP3417494B2 - Method and apparatus for inspecting surface undulation of glass substrate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting the surface waviness of a plate-shaped material used as a substrate for a liquid crystal display device to obtain the surface waviness of a plate-shaped material as a luminance distribution.

[0002]

Glass substrates for use in the Related Art A liquid crystal display device,
It is necessary to suppress surface waviness within the specified range, and surface waviness is inspected in the shipping inspection process. The inspection method of the surface waviness is measured by using a contact type surface roughness meter
What it is, the occurrence of scratches due stylus is concerned, total inspection since the measuring time is long is not possible.
On the other hand, if a non-contact surface roughness meter using a laser displacement meter is used, it may be possible to solve the problem of scratches and long measurement time. It cannot be obtained with high precision.

[0003]

By the way, radiated light or parallel light from a point light source is applied to a glass substrate from an oblique direction .
Case, the light reflected from the surface of the glass substrate, the intensity unevenness occurs depending on the surface waviness of the glass substrate is known. However, in the glass substrate for a liquid crystal display device , a part of visible light is reflected on the front surface of the glass substrate, and the other visible light is transmitted through the glass substrate and partly reflected on the back surface. Therefore, since the reflected light from the glass substrate includes the visible light reflected on the front surface and the visible light reflected on the back surface, it is difficult to accurately inspect the surface waviness of the glass substrate. There is.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a surface waviness inspection method and device for a plate-like material, which can easily inspect waviness only on the surface of the glass substrate. And

[0005]

According to the present invention, the surface of a glass substrate is exposed to ultraviolet light so that it is reflected by the surface of the glass substrate.
The reflected ultraviolet light is projected onto the glass substrate ,
Of the ultraviolet light reflected by the surface of the glass substrate, the glass substrate
Irradiate the surface of the fluorescent screen member with ultraviolet light having a wavelength reflected on the surface of the plate, and display the luminance distribution of visible light corresponding to the surface waviness of the glass substrate on the front surface or the back surface of the fluorescent screen member, The brightness distribution signal obtained by imaging the brightness distribution of the visible light displayed on the front surface or the back surface of the fluorescent screen member by the image capturing means is subjected to image processing, and
A glass substrate characterized by determining the surface waviness of the glass substrate
A surface waviness inspection method for a plate and an apparatus for carrying out the method.

[0006]

According to the present invention, since the glass material used in the liquid crystal display device is generally opaque to ultraviolet rays, part of the ultraviolet rays projected onto the glass substrate is reflected only on the surface of the glass substrate, The fluorescent screen member is illuminated. Therefore, on the front surface or the back surface of the fluorescent screen member, the brightness distribution of visible light corresponding to the undulation of only the surface of the glass substrate is displayed. The imaging unit images the brightness distribution of visible light displayed on the front surface or the back surface of the fluorescent screen member. The image processing section image-processes the luminance distribution signal obtained from the image pickup means to obtain the surface waviness of the plate-shaped material.

As described above, by using the ultraviolet light as the light source, the ultraviolet light reflected only on the surface can be obtained in the case of the glass substrate, and further, by using the fluorescent screen member, the image pickup means for the visible light is obtained. The ultraviolet intensity distribution can be imaged with.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method and apparatus for inspecting surface waviness of a plate-like material according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an overall view of a surface waviness inspection apparatus for plate-like materials according to the present invention. As shown in FIG. 1, the surface waviness inspection device for a plate-shaped material includes an ultraviolet light projecting means 12 and a fluorescent screen member 1.
4, a camera (imaging means) 16 and an image processing unit 18. The ultraviolet light projecting means 12 has a case 19, and an ultraviolet lamp 20 is housed at the upper end of the case 19. A spherical reflecting mirror 22 is provided around the ultraviolet lamp 20. A pinhole 22A is opened below the reflecting mirror 22. As a result, the ultraviolet light 21A projected from the ultraviolet lamp 20 is emitted through the pinhole 22A, so that the ultraviolet light 21A is in a state of radiated light projected from the point light source.

Ultraviolet wavelength selection filters 24A and 24B are provided below the pinhole 22A, and the reflection mirror 2 is provided below the ultraviolet wavelength selection filters 24A and 24B.
6 is arranged in an inclined state. The ultraviolet wavelength selection filters 24A and 24B extract the short wavelength (about 250 nm) ultraviolet light 21B included in the ultraviolet light 21A. The ultraviolet light 21B extracted by the ultraviolet wavelength selection filters 24A and 24B is totally reflected by the reflection mirror 26, and the case 19
It is ejected to the left of the case 19 through the opening hole 19A. Then, the ultraviolet light 21B emitted from the opening hole 19A
Irradiates a glass substrate 27 described later from an oblique direction. On the left side of the case 19, a glass receiving portion 32 is arranged,
The glass substrate 27 to be inspected is placed horizontally. Then, the ultraviolet light 21B is applied to the glass substrate 27 at a constant inclination angle (about 10 degrees) (see FIG. 2).

A guide rail 3 is provided on the left side of the glass receiving portion 32.
4 is arranged so as to extend in the direction of arrow AB. A movable body 36 is supported on the guide rail 34 so as to be movable in the directions of arrows AB, and the fluorescent screen 14 is vertically provided at the right end of the movable body 36. The fluorescent screen 14 is coated with a fluorescent substance in the form of a film in this example, and the ultraviolet light 2 reflected by the surface of the glass substrate 27 is used.
When the intensity distribution of 1B is applied to the surface of the fluorescent screen 14, the luminance distribution of visible light corresponding to the intensity distribution of the ultraviolet light 21B is extracted on the fluorescent screen 14. Since the fluorescent screen 14 moves in the direction of arrow AB along the guide rail 34 via the moving body 36, the ultraviolet light 21B reflected on the surface of the glass substrate 27 specifies the surface waviness of the glass substrate 27. Intensity distribution corresponding to wavelength and waviness height with a good signal / noise ratio (S / N ratio), fluorescent screen 1
4 can be illuminated.

Further, the camera 1 is provided at the left end of the moving body 36.
6 is provided. The camera 16 has a fluorescent screen 14
The brightness of visible light displayed above is sensed, and the signal obtained by photoelectrically converting the brightness of the fluorescent screen 14 is transmitted to the image processing unit 18. As described above, since the fluorescent screen 14 senses the luminance distribution converted from ultraviolet light to visible light, a normal camera for visible light can be used. Therefore, the surface waviness inspection apparatus can be provided at a lower cost than when using a camera and a lens for ultraviolet light. The image processing unit 18, based on the signal transmitted from the camera 16,
A fluorescence intensity image 38 (see FIG. 3) corresponding to the brightness distribution on the fluorescent screen 14 is obtained, and the data string of the fluorescence intensity image is stored as measurement data.

The characteristics of the surface waviness of the glass substrate 27 will be described. As shown in FIG. 2, the surface waviness of the glass substrate 27 is formed in a linear striped pattern with a certain waviness length S in the Y-axis direction. In FIG. 2, H represents the height of the surface waviness of the glass substrate 27. As described above, the surface of the glass substrate 27 having such a surface waviness characteristic is exposed to the ultraviolet light 2 as described above.
1B is irradiated from the direction of the arrow, and the surface of the fluorescent screen 14 is irradiated with the ultraviolet light 21B reflected on the surface.

Therefore, the intensity distribution of the ultraviolet light 21B corresponding to the surface waviness of the glass substrate 27 is displayed on the surface of the fluorescent screen 14, and the surface waviness of the glass substrate 27 is supported on the front surface or the back surface of the fluorescent screen 14. The brightness distribution of visible light is displayed (see FIG. 3). In FIG. 3, the “solid line” indicates a high-luminance line and the “dashed line” indicates a low-luminance line. The high-luminance line and the low-luminance line are constant in correspondence with the surface waviness of the glass substrate 27. The swell length S is displayed. That is, the fluorescent screen 1
On the front surface or the back surface of No. 4, the luminance change period and the amount of luminance change due to visible light are displayed, and there is a strong correlation between the surface waviness length S of the glass substrate 27 and the luminance change period on the fluorescent screen 14. Further, there is a strong correlation between the surface waviness height H of the glass substrate 27 and the brightness change amount on the fluorescent screen 14.

By the way, the image processing section 18 performs addition processing in order to increase the S / N ratio of the fluorescence intensity image 38. As an example of the addition processing, the image processing unit 18 uses the fluorescence intensity image 3
8 is divided into four, for example, and the divided image 38A and image 3 are divided.
8B, image 38C, and image 38D (see FIG. 5) are horizontally added (added in the X direction) to the data strings of the respective images. This allows
The S / N ratio of the data string of the fluorescence intensity image 38 can be increased. Although the fluorescence intensity image 38 is divided into four in this addition processing, it is possible to divide the fluorescence intensity image 38 into other than four.
Considering increasing the / N ratio, the range of 4 to 8 divisions is optimal.

The image processing section 18 also performs bandpass filter processing on the horizontally added data sequence. And
The image processing unit 18 obtains the brightness change period and the brightness change amount based on the data string subjected to the bandpass filter processing.
In this way, the brightness change period and the brightness change amount are obtained by the image processing unit 18, so that the surface waviness length S and the surface waviness height H of the glass substrate 27 are estimated based on the brightness change period and the brightness change amount. be able to.

The operation of the surface waviness inspection apparatus for plate-like materials according to the present invention constructed as described above will be described. First, the glass substrate 27 is placed on the glass receiving portion 32, and then the ultraviolet light 21A emitted from the ultraviolet lamp 20 is applied to the pinhole 22A.
Inject through. The ultraviolet light 21A emitted from the pinhole 22A is the ultraviolet wavelength selection filters 24A and 24B.
Then, the short wavelength (about 250n included in the ultraviolet light 21A
The ultraviolet light 21B of m) is extracted. Extracted UV light 2
1B is totally reflected by the reflection mirror 26 and emitted from the opening hole 19A of the case 19 to the left of the case 19. Then, the ultraviolet light 21B emitted from the opening hole 19A irradiates the glass substrate 27 at an inclination angle of about 10 degrees.

The ultraviolet light 21B applied to the glass substrate 27 is reflected by the surface of the glass substrate 27 and illuminates the surface of the fluorescent screen 14. Therefore, the intensity distribution corresponding to the surface waviness of the glass substrate 27 by the ultraviolet light 21B is displayed on the surface of the fluorescent screen 14, and the brightness distribution by visible light is displayed on the front surface or the back surface of the fluorescent screen 14. In this state, the front surface or the back surface of the fluorescent screen 14 is sensed by the camera 16 to obtain a fluorescence intensity image 38 corresponding to the luminance distribution on the fluorescent screen 14, and the luminance distribution obtained from the fluorescence intensity image 38 is used as measurement data. Image processing unit 18
Remember. Note that the image processing unit 18, the luminance distribution of the sample for flat glass having a high flatness of the surface are stored as reference data obtained by the above process.

Next, the image processing section 18 subtracts the reference data from the measurement data to obtain the correction data, and stores the obtained correction data. Next, the image processing unit 18 converts the fluorescence intensity image 38 into an image 38A, an image 38B, and an image 38.
C, image 38D is divided into four, and each image is horizontally added to increase the S / N ratio. Next, the image processing unit 18 applies a band-pass filter to the horizontally added data to obtain a luminance change cycle, and further, the image processing unit 18 obtains the amount of luminance change based on the horizontally added data. Then, based on the obtained brightness change period and brightness change amount, the glass substrate 27
The surface waviness length S and the surface waviness height H are estimated and it is determined whether or not the surface waviness of the inspected glass substrate 27 is within the specified values.

In the above embodiment, the S / N of the fluorescence intensity image 38 is
The case where the addition processing is adopted to increase the ratio has been described, but the present invention is not limited to this, and S may be used in other processing such as differentiation processing.
The / N ratio may be increased. In the case of the differential processing, the fluorescence intensity image 38 is differentiated in the Y direction to obtain a luminance distribution curve 38A (see FIG. 3) such that the change points of the luminance have peaks, and the obtained luminance distribution curve 38A is set in the X direction. To increase the S / N ratio.

In the above-described embodiment, the case where the ultraviolet light 21A is the radiant light projected from the point light source has been described, but the present invention is not limited to this, and the projected ultraviolet light can be parallel light, and the same effect can be obtained.

[0021]

As described above, according to the method and apparatus for inspecting the surface waviness of a plate-like material according to the present invention, ultraviolet light is reflected on the surface of the plate-like material and the fluorescent screen member is irradiated with the reflected light. Thus, even when the plate-shaped material is plate glass, it is possible to obtain the ultraviolet light in which the ultraviolet light is reflected only on the surface of the plate glass, and further, the brightness distribution on the fluorescent screen member is imaged by the imaging means for visible light. You can Therefore, the surface waviness of the plate-shaped material can be easily inspected, and a low-cost surface waviness inspection device can be provided.

[Brief description of drawings]

FIG. 1 is an overall view of a surface waviness inspection device for plate-like materials according to the present invention.

FIG. 2 is an explanatory diagram of a glass substrate inspected by a surface waviness inspection apparatus for plate-like materials according to the present invention.

FIG. 3 is an explanatory diagram illustrating a luminance distribution on a fluorescent screen used in a surface waviness inspection device of a plate-shaped material cutting device according to the present invention.

FIG. 4 is a front view of a fluorescence intensity image obtained by an image processing unit.

FIG. 5 is a diagram illustrating a state in which a fluorescence intensity image obtained by an image processing unit is divided into four.

[Explanation of symbols]

10 ... Plate waviness surface waviness inspection device 12 ... Ultraviolet light projecting means 14 ... Fluorescent screen (fluorescent screen member) 16 ... Camera (imaging means) 18 ... Image processing unit 21A, 21B ... UV light 27 ... Glass substrate (plate material)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ryo Yoshida 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory (56) Reference JP-A-5-256630 (JP, A) JP-A-52 -82260 (JP, A) JP 60-58536 (JP, A) Actual development 57-61549 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11/00- 11/30 G01N 21/88

Claims (2)

(57) [Claims] 1. A purple color so that it is reflected on the surface of a glass substrate.
And projecting ultraviolet light having a wavelength which is reflected by the surface of the glass substrate of the external light on the glass substrate, the reflected by the surface of the glass substrate, of the ultraviolet light sulfate
Irradiate the surface of the fluorescent screen member with ultraviolet light having a wavelength reflected by the surface of the substrate, and display the brightness distribution of visible light corresponding to the surface waviness of the glass substrate on the front surface or the back surface of the fluorescent screen member. Wherein the brightness distribution signal obtained by imaging the brightness distribution of the visible light displayed on the front surface or the back surface of the fluorescent screen member with an imaging means is image-processed to obtain the surface waviness of the glass substrate. Method for inspecting surface waviness of glass substrate . 2. A violet color so that it is reflected on the surface of the glass substrate.
And ultraviolet light projecting means for projecting ultraviolet light having a wavelength which is reflected by the surface of the glass substrate of the external light on the glass substrate, is reflected by the surface of the glass substrate, nitric among the ultraviolet light
A fluorescent screen member that is arranged so that the surface is irradiated with ultraviolet light having a wavelength reflected by the surface of the sub-substrate , and the luminance distribution of visible light corresponding to the surface waviness of the glass substrate is displayed on the front or back surface. An image pickup unit for picking up the luminance distribution of the visible light displayed on the fluorescent screen member; and an image processing unit for image-processing the luminance distribution signal obtained from the image pickup unit to obtain the surface waviness of the glass substrate. An apparatus for inspecting surface waviness of a glass substrate , comprising: