JP4358955B2 - Foreign matter inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting foreign matter existing between a transparent substrate such as a glass substrate having a polarizing film attached to the surface thereof and the polarizing film.
[0002]
[Prior art]
In recent years, a liquid crystal display device (LCD) has attracted attention as a small and lightweight display device that replaces a cathode ray tube. FIG. 6 schematically shows a configuration of a general LCD 1. As shown in FIG. 6, the LCD 1 is a rectangle (for example, a rectangle) in plan view, and includes a cell 2 and a backlight 3. The cell 2 includes a pair of upper and lower transparent glass substrates 4 and 5, a color filter 6, a liquid crystal 7 and a color filter array substrate 8 sandwiched between the glass substrates 4 and 5. It consists of polarizing films 9 and 10 adhered to the outer surfaces 4a and 5a of the glass substrates 4 and 5, respectively, and the surface 9a of the upper polarizing film 9 is the display screen of the LCD 1. The backlight 3 is provided so as to be in close contact with the surface 10 a of the lower polarizing film 10.
[0003]
By the way, in the manufacturing process of LCD1 of the said structure, after the glass substrates 4 and 5 pass a glass substrate conveyance line, although the polarizing films 9 and 10 are affixed on the outer surfaces 4a and 5a of the glass substrates 4 and 5, Foreign matter such as dust adheres to the glass substrates 4 and 5 while passing through the glass substrate transport line, or foreign matter such as dust adheres to the polarizing films 9 and 10 before passing through the polarizing film transport line. The foreign matter enters not only between the front surfaces 9 a and 10 a of the polarizing films 9 and 10 but also between the glass substrate 4 and the back surface 9 b of the polarizing film 9 and between the glass substrate 5 and the back surface 10 b of the polarizing film 10. there is a possibility. For this reason, conventionally, the foreign matter is inspected by using a laser scattering measurement method in which laser light is irradiated obliquely from above the glass substrate 4 and scattered light from the foreign matter is detected by a photodetector. It was.
[0004]
[Problems to be solved by the invention]
However, the polarizing films 9 and 10 are extremely thin with a thickness of about 100 μm at most. Therefore, foreign matters are present on any of the front surfaces 9a and 10a and the rear surfaces 9b and 10b of the thin polarizing films 9 and 10. It was extremely difficult to determine whether it was attached. This is due to the depth of focus of the photodetector, and the thinner the polarizing films 9, 10, the more difficult it is. In particular, in the polarizing films 9 and 10 attached to the transparent substrates such as the glass substrates 4 and 5, the inspection can be performed only from one side, that is, the surfaces 9a and 10a side of the polarizing films 9 and 10. First, whether the foreign matter is present on the front surfaces 9a, 10a of the polarizing films 9, 10, or the back surfaces 9b, 10b of the polarizing films 9, 10, that is, the back surfaces of the glass substrates 4, 5 and the polarizing films 9, 10 It was not possible to easily determine whether it exists between 9b and 10b.
[0005]
The above-described problems are generally caused not only in LCDs but also in transparent substrates having a polarizing film attached to the surface.
[0006]
The present invention has been made in consideration of the above-mentioned matters, and its purpose is to reliably detect foreign matter existing between a transparent substrate such as a glass substrate used in an LCD and a polarizing film, for example. It is providing the foreign material inspection apparatus which can do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to a transparent substrate having a polarizing film attached to the surface thereof, light having a polarizing plane parallel to the polarizing plane of the polarizing film, and the polarizing film. By irradiating light having a polarization plane orthogonal to the polarization plane of the film from the side of the polarization film, and comparing information based on the respective scattered light generated at that time, foreign matter existing between the transparent substrate and the polarization film is removed. It can be detected.
[0008]
For example, in an LCD, a polarizing film is necessarily attached to one surface of a glass substrate as a transparent substrate. As shown in FIG. 3, this polarizing film has the property of transmitting or not transmitting incident light depending on the polarization direction of incident light. That is, in this figure, when the light 18 from the light source 14 has a polarization plane parallel to the polarization plane of the polarization film 9, it passes through the polarization film 9 as indicated by reference numeral 18 ′. When the light 19 has a polarization plane orthogonal to the polarization plane of the polarization film 9, the light 19 cannot be transmitted through the polarization film 9.
[0009]
In the invention described in claim 1, the polarizing surface of the polarizing film is used with respect to a transparent substrate that skillfully utilizes the properties of the polarizing film 9 (or 10) as described above and has a polarizing film attached to the surface. when light having a plane of polarization parallel irradiated from the polarization film side, if the foreign object is present respectively on the front and back surfaces of the polarizing film, but scattered light from both the foreign matter can be obtained, and the polarization plane of the polarizing film When light having an orthogonal polarization plane is irradiated from the polarizing film side, scattered light can be obtained only from the foreign matter present on the surface of the polarizing film, even if the foreign matter exists on the front and back surfaces of the polarizing film. Therefore, each of the scattered light generated when two light beams each having a polarization plane parallel to the polarization plane of the polarization film and a polarization plane orthogonal to the polarization plane of the polarization film are respectively detected by the photodetector. By comparing the output of the light detector (scattered light information), foreign matter present on the back surface of the polarizing film can be determined.
[0010]
The invention described in claim 2, irradiates with light from the back side of the transparent substrate polarizing film is adhered to a surface, light having a polarization plane orthogonal to the polarizing film side and the polarization plane of the polarizing film irradiating the, by comparing the information based on each of the scattered light generated at that time, and to be able to detect foreign material existing between the polarizing film and the transparent substrate.
[0011]
In the invention according to the second aspect, the light scattered from the foreign matter existing on both the front and back surfaces of the polarizing film is obtained by irradiating light from the back side of the transparent substrate. By irradiating light having a polarization plane orthogonal to the polarization plane of the polarizing film from the polarizing film side, even if foreign matters exist on both the front and back surfaces of the polarizing film, the light is scattered only from the foreign matters existing on the surface of the polarizing film. I can't get light. Therefore, each of the scattered light generated when light is irradiated from the back side and the polarizing film side of the transparent substrate is detected by the photodetector, and the output (scattered light information) of each photodetector is compared, thereby polarizing the light. Foreign matter present on the back surface of the film can be discriminated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment of the present invention. In this embodiment, it is assumed that the LCD to be inspected is in a stage before the backlight 3 is attached, that is, in a semi-finished product state with only the cell 2, and is denoted by reference numeral 1A in FIG. In FIG. 1, 11 can freely move in each of three directions perpendicular to each other, the X direction (left-right direction in the figure), the Y direction (direction perpendicular to the paper surface), and the Z direction (up-down direction in the figure). The LCD 1A is held horizontally at the inspection stage.
[0013]
In this embodiment, two irradiation optical systems and two detection optical systems are provided. That is, in FIG. 1, reference numerals 12 and 13 denote irradiation optical systems provided above both ends of the inspection stage 11 in the X direction. These irradiation optical systems 12 and 13 are composed of light sources 14 and 15 and condenser lens arrays 16 and 17. The light sources 14 and 15 are both laser light sources, and one light source 14 emits light 18 (for example, p-polarized laser light) having a polarization plane parallel to the polarization plane of the polarizing film 9 on the upper side of the LCD 1A. The other light source 15 is configured to emit light (for example, s-polarized laser light) 19 having a polarization plane orthogonal to the polarization plane of the polarizing film 9. That is, the two laser light sources 14 and 15 respectively emit p-polarized laser light 18 and s-polarized laser light 19 whose polarization planes are 90 ° different from each other. Each of the condenser lens arrays 16 and 17 is formed by arraying refractive index distribution lenses such as cylindrical lenses, and has a length that can irradiate the entire width (length in the Y direction) of the LCD 1A. Have. The condensing lens arrays 16 and 17 are intended to improve the sensitivity by focusing the laser beams 18 and 19, and are not necessarily required.
[0014]
In FIG. 1, reference numerals 20 and 21 denote detection optical systems provided between the irradiation optical systems 12 and 13 at an appropriate interval right above the inspection stage 11. These detection optical systems 20 and 21 include photodetectors 22 and 23 and condenser lens arrays 24 and 25. The photodetectors 22 and 23 are made of, for example, a CCD array sensor, and are horizontally provided in the Y direction. The condensing lens arrays 24 and 25 are provided below them (on the side closer to the inspection stage 11) so as to correspond to the photodetectors 22 and 23. For example, the refractive index of a SELFOC lens (trade name) or the like. It consists of an array of distributed lenses. The detection optical systems 20 and 21 have such a length that the entire width direction of the LCD 1A can be detected.
[0015]
Next, the operation of the foreign matter inspection apparatus having the above configuration will be described with reference to FIG. Now, as shown in FIG. 2, suppose that the foreign materials 26 and 27 exist in the surface 9a and the back surface 9b of the polarizing film 9, respectively. For example, first, when the p-polarized laser beam 18 that is a light having a polarization plane parallel to the deflection plane of the polarizing film 9 is irradiated from one laser light source 14 to the LCD 1A from the surface 9a side of the polarizing film 9, As indicated by reference numerals 18a and 18b, scattered light is generated from both of the foreign matters 26 and 27 existing on the front surface 9a and the back surface 9b of the polarizing film 9, respectively. These scattered light 18a and 18b are respectively detected by the photodetector 22. , 23.
[0016]
Next, when the s-polarized laser light 19, which is light having a polarization plane orthogonal to the polarization plane of the polarizing film 9, is irradiated from the other laser light source 15 to the LCD 1 </ b> A from the surface 9 a side of the polarizing film 9, As shown by 19a, scattered light is generated from the foreign material 26 present on the front surface 9a of the polarizing film 9, but the s-polarized laser light 19 cannot pass through the polarizing film 9, and therefore exists on the back surface 9b of the polarizing film 9. Scattered light is not generated from the foreign matter 27 to be scattered, and the scattered light 19 a from the foreign matter 26 is detected by, for example, the photodetector 22.
[0017]
That is, when the foreign matters 26 and 27 are present on the front surface 9a and the back surface 9b of the polarizing film 9, when the polarizing film 9 is irradiated with the p-polarized laser light 18 having a polarization plane parallel to the polarization plane, When scattered light 18a and 18b from foreign substances 26 and 27 on both sides of the front surface 9a and the back surface 9b is obtained , when the s-polarized laser light 19 having a polarization plane orthogonal to the polarization plane of the polarization film 9 is irradiated to the polarization film 9 The scattered light 19a can be obtained only from the foreign matter 26 on the surface 9a side.
[0018]
Therefore, the information on the scattered light 18a and 18b obtained when the polarizing film 9 is irradiated with the p-polarized laser light 18 and the information on the scattered light 19a obtained when the s-polarized laser light 19 is irradiated are compared. By doing so, it is possible to specify only the foreign matter 27 present on the back surface 9b side of the polarizing film 9.
[0019]
In order to fully inspect the polarizing film 9 in the LCD 1A, the inspection stage 11 may be appropriately moved in the X and Y directions. In the example shown in FIG. 2, for the inspection of the foreign matter in the polarizing film 10, for example, the LCD 1 </ b> A in a semi-finished state with only the cell 2 is turned over and the same as described above is performed. Can be identified. In the above-described embodiment, two detection optical systems 20 and 21 are provided. However, only one detection optical system may be used. Further, only one irradiation optical system may be provided so that the p-polarized laser beam 18 and the s-polarized laser beam 19 can be switched and output by a single irradiation optical system.
[0020]
In the first embodiment described above, the foreign matter was inspected in the LCD 1A in the semi-finished product state. However, as shown in FIG. 6, in the finished product LCD 1 in which the cell 2 and the backlight are combined, It is preferable to inspect as shown in FIGS. Hereinafter, this will be described as a second embodiment.
[0021]
4 and 5, reference numerals 31 and 32 denote an irradiation optical system and a detection optical system, respectively. The irradiation optical system 31 includes a light source 33 and a condenser lens array 34, and the detection optical system 32 includes a photodetector 35. And a condensing lens array 36.
[0022]
The light source 33 emits light (for example, s-polarized laser light) 37 having a polarization plane orthogonal to the polarization plane of the polarizing film 9 (see FIG. 5), similarly to the light source 15 in the first embodiment. It is configured. The condensing lens array 34 is formed by arraying refractive index distribution lenses such as cylindrical lenses, and has a length that can irradiate the entire width (length in the Y direction) of the LCD 1.
[0023]
The photodetector 35 is composed of a CCD array sensor and is provided in the Y direction in the same manner as the photodetector 23 in the first embodiment. The condensing lens array 36 is provided below the condensing lens array 36 so as to correspond to the photodetector 35, and is composed of an array of refractive index distribution lenses such as a SELFOC lens (trade name). The detection optical system 32 has a length that can detect the entire width direction of the LCD 1.
[0024]
Next, the operation of the foreign substance inspection apparatus having the above configuration will be described with reference to FIG. Now, as shown in FIGS. 5A and 5B, it is assumed that foreign substances 38 and 39 are present on the front surface 9a and the back surface 9b of the polarizing film 9, respectively. In this embodiment, the light 40 from the backlight 3 provided on the back surface (lower surface) side of the cell 2 is also used.
[0025]
That is, as shown in FIG. 5A, when the foreign matter 38 existing on the surface 9a side of the polarizing film 9 is irradiated with the light 40 from the backlight 3 and the s-polarized laser light 37 from the laser light source 33, the foreign matter is irradiated. In FIG. 38, as indicated by reference numerals 37 ′ and 40 ′ in FIG. 5A, scattered light is generated due to the s-polarized laser light 19 and the backlight light 40 being irradiated onto the foreign matter 38. The scattered light 37 ′ and 40 ′ are detected by the photodetector 35. On the other hand, as shown in FIG. 5B, when the foreign matter 39 existing on the back surface 9b side of the polarizing film 9 is irradiated with the light 40 from the backlight 3 and the s-polarized laser light 37 from the laser light source 33, Since only the light 40 from the light 3 is transmitted through the polarizing film 9 and the s-polarized laser light 37 cannot be transmitted through the polarizing film 9, scattering caused by the light 40 from the backlight 3 being applied to the foreign matter 39. Only light 40 ′ is generated, and this scattered light 40 ′ is detected by the photodetector 35.
[0026]
Therefore, also in this embodiment, as in the first embodiment, when the foreign matters 38 and 39 are present on the front surface 9a and the back surface 9b of the polarizing film 9, the light 40 from the backlight 3 is polarized. When the film 9 is irradiated, scattered light 40 ′ from the foreign matters 38 and 39 on both sides of the front surface 9 a and the back surface 9 b is obtained, whereas s-polarized laser light 37 having a polarization plane orthogonal to the polarization plane of the polarization film 9 is obtained. When the polarizing film 9 is irradiated, scattered light 37 ′ can be obtained only from the foreign matter 38 on the surface 9 a side.
[0027]
Therefore, the information (scattering light information) of the scattered light 40 ′ obtained when the polarizing film 9 is irradiated with the light 40 from the backlight 3 and the scattered light obtained when the s-polarized laser light 37 is irradiated. By comparing the information 37 ′ (foreign surface foreign matter information), only the foreign matter 39 present on the back surface 9b side of the polarizing film 9 can be specified.
[0028]
In any of the above-described embodiments, the polarizing films 9 and 10 are attached to the glass substrates 4 and 5. However, in the present invention, the polarizing films 9 and 10 are transparent substrates other than the glass substrate. It can also be applied to those pasted on.
[0029]
【The invention's effect】
As described above, according to the foreign matter inspection apparatus of the present invention, foreign matter existing between a transparent substrate such as a glass substrate and a polarizing film can be reliably detected, which greatly improves the quality of an LCD, for example. Can contribute.
[0030]
In particular, according to the first aspect of the present invention, an LCD in a semi-finished product state can be inspected during the manufacturing process, and the yield in the manufacturing process can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing a configuration of a foreign matter inspection apparatus according to a first embodiment.
FIG. 2 is a diagram for explaining the operation of the apparatus.
FIG. 3 is a diagram for explaining the characteristics of a polarizing film.
FIG. 4 is a perspective view schematically showing a configuration of a foreign matter inspection apparatus according to a second embodiment.
FIG. 5 is a diagram for explaining the operation of the apparatus.
FIG. 6 is a cross-sectional view schematically showing a configuration of an LCD.
[Explanation of symbols]
4, 5 ... Transparent substrate, 9, 10 ... Polarized film, 18, 19 ... Irradiated light, 18a, 18b, 19a ... Scattered light, 26, 27 ... Foreign matter, 37, 40 ... Irradiated light, 37 ', 40' ... Scattered Light, 38, 39 ... Foreign matter.

Claims (2)

With respect to the transparent substrate having the polarizing film attached to the surface, the polarizing film side includes light having a polarizing plane parallel to the polarizing plane of the polarizing film and light having a polarizing plane orthogonal to the polarizing plane of the polarizing film. The foreign matter inspection apparatus characterized in that the foreign matter existing between the transparent substrate and the polarizing film can be detected by comparing information based on each scattered light generated at that time. Irradiates with light from the back side of the transparent substrate polarizing film is adhered to the surface, irradiated with light having a polarization plane orthogonal to the polarizing film side and the polarization plane of the polarizing film, each of the scattered light generated at that time A foreign matter inspection apparatus characterized in that foreign matter existing between the transparent substrate and the polarizing film can be detected by comparing information based on the above.

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