KR20080093236A - Method and apparatus for inspecting substrate using high reflection and transmission efficiency and phase delay of transmitted light - Google Patents

Abstract

In the present invention, defects such as unsighted defects, such as unseen defects, are frequently observed in the substrate inspection before bonding in the inspection of the substrate before bonding of the upper plate or the lower plate for the liquid crystal display device. Improve reflection and transmission efficiency for clearer inspection, and retard the transmitted light by retarding the phase of transmitted light similarly to the role of the liquid crystal before bonding before bonding, so that inspection can be performed in an environment similar to that after bonding. The present invention relates to a substrate inspection method and apparatus capable of improving the yield of a liquid crystal panel after the substrate is determined in advance so that the defective substrate does not proceed to the bonding process and is bonded. According to the present invention, a substrate inspection method for inspecting a state of a substrate by irradiating light to the substrate includes polarization means for passing light in a specific vibration direction, phase delay means for generating a phase difference between two vibration direction components of light, and Contacting one transparent mirror having a predetermined reflectance and transmittance in turn, placing a substrate on the one transparent mirror, irradiating light under the polarizing means, and by the light irradiated under the polarizing means. Inspecting light transmitted through the substrate.

Description

Method and Apparatus for Inspecting Substrate Using High Reflection and Transmission Efficiency and Phase Delay of Transmitted Light {Method and Apparatus for Inspecting Substrate with High Efficiency Reflection and Transmission and Phase Shift of Transmission Light}

1 is a view for explaining a substrate inspection apparatus according to the prior art.

2 is a view for explaining a reflection test of a substrate before bonding for a liquid crystal display.

3 is a view for explaining the transmission inspection of the substrate before bonding for the liquid crystal display device.

4 is a view for explaining a liquid crystal state visual inspection of a substrate after bonding for a liquid crystal display device.

5 is a diagram for describing a final inspection such as a driving state of a substrate after bonding for a liquid crystal display.

6 is a view for explaining linear polarization of light.

7 is a view for explaining circular polarization of light.

8 is a diagram for explaining elliptical polarization of light.

9 is a view for explaining the phase delay of light.

10 is a diagram for describing color shift due to phase delay of light.

11 is a diagram for explaining contrast ratio CR of a stain.

12 is a view for explaining a substrate inspection apparatus according to an embodiment of the present invention.

FIG. 13 is a view for explaining a specific configuration between the near-field illumination system of FIG. 12 and the substrate placed thereon.

14 is a flowchart illustrating a substrate inspection method according to an embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

121: rotating unit

122: near-field transmission illumination system

131: BLU (Back Light Unit)

132: diffuser plate

133: polarizing film

134: phase retardation film

135: one-sided transparent mirror

123: pre-bonding substrate for liquid crystal display

The present invention relates to a device and a method for inspecting a substrate for a liquid crystal display device, and in particular, a defect such as uneven visual inspection in the substrate inspection before bonding of the upper plate or the lower plate for the liquid crystal display device in the inspection of the substrate after bonding. As the phenomenon occurs frequently, the reflection and transmission efficiency should be improved so that defects such as stains can be examined more clearly in the inspection of the substrate before bonding, and the transmitted light is phased similarly to the role of the liquid crystal before bonding before bonding. A substrate inspection method capable of delaying the inspection in an environment similar to that after bonding so as to determine a defective substrate before bonding so that the defective substrate does not proceed to the bonding process and to improve the yield of the liquid crystal panel after the bonding; Relates to a device.

1 is a view for explaining a substrate inspection apparatus according to the prior art. Referring to FIG. 1, a pre-bonding test substrate for a liquid crystal display device is fixed to a predetermined frame configured to move on a rotation means.

The inspector may observe defects such as unevenness due to non-uniformity of electrodes, color filters, column spacers, and the like on the substrate by observing the light reflected from the reflecting illumination system, and may determine a good / bad substrate. This inspection can also be done by taking and analyzing an image using a camera at the inspector's location. For example, as shown in FIG. 2, a CF (color filter) substrate (a glass substrate before bonding including a color filter for a liquid crystal display) may be R (red), G (green), or B (blue) color. When the filter cells 21 are applied and a foreign matter adheres to the CF substrate or defects 22 due to various causes during the process are present, the inspector can determine the color of light reflected from the corresponding portion of the CF substrate. Can be determined as a defective substrate having defects such as unevenness.

In addition, as shown in FIG. 3, the inspector observes light passing through the CF substrate through the light emitted from the transmissive illumination system, thereby causing defects such as spots from the color of light transmitted from the non-uniform portion 32 of the color filter cells 31. Can be determined. Since the transmission illumination system for illumination at the time of transmission inspection is 3m or more away from the CF substrate, the inspection apparatus as shown in FIG. 1 has a problem of taking up a lot of space.

The above reflection inspection and transmission inspection can also be performed on a TFT (Thin Film Transistor) substrate (a glass substrate before bonding including a TFT for a liquid crystal display device), and a top plate (CF substrate) and a bottom plate (TFT) for a liquid crystal display device. Prior to the bonding of the substrate), inspection is mainly performed to detect defects such as spots in reflection inspection rather than transmission inspection.

On the other hand, in the inspection of the substrate after the bonding of the upper plate (CF substrate) and the lower plate (TFT substrate) for the liquid crystal display device, the final inspection such as the liquid crystal state visual inspection as shown in FIG. 4 and the driving state as shown in FIG. 5 is performed.

For visual inspection of the liquid crystal state, as shown in FIG. 4, the polarizing film 42 is placed on the BLU (Back Light Unit) 41, and the bonding substrate 43 is placed thereon. The inspector observes the light emitted from the BLU 41 through the polarizing film 42 and the bonding substrate 43 through the polarizing film 44, so that the uneven state of the liquid crystal enclosed in the bonding substrate 43 is observed. Defects such as spots can be determined from abnormality of the transmitted light. At this time, in order to take advantage of the color shift phenomenon in which R, G, and B are strong in different directions depending on the light propagation direction due to the phase delay in the liquid crystal, the inspector rotates the polarizing film 44 to The defect is judged by observing abnormality of each color in the direction.

For the final inspection such as the driving state, as shown in FIG. 5, the polarizing film 52 is placed on the BLU (Back Light Unit) 51, and the bonding substrate 53 and the polarizing film 54 are placed thereon. The inspector observes defects such as specks by analyzing the light emitted from the BLU 51 through the polarizing film 52, the bonding substrate 53, and the polarizing film 54 through the naked eye or an image taken by the camera. It can be judged whether or not there was a defect in the whole process of the liquid crystal panel until it adhere | attached. In this case, a signal V required for actual driving of the bonded substrate 53, that is, a signal required for driving a gate line, a data line, or the like is probed and applied to a device capable of high precision alignment. Observe the R, G, and B spots for each color and whether the specific image is normal.

However, there is a problem that a substrate, which is determined to be a good substrate in the pre-bonding inspection method, is often determined to be defective due to defects such as stains in the post-bonding inspection. That is, in the reflection test before bonding, the liquid crystal encapsulated at the time of bonding cannot be observed to reflect the influence on the CF substrate or the TFT substrate before bonding, so that unstained spots before bonding may appear in a changed environment after bonding. For example, the recent tendency is to increase the transmittance of the color filter and to lower the reflectance. Therefore, in the reflection inspection of the substrate after bonding, the light transmitted through the color filter may be reflected back to the color filter. Light reflection environment can vary. In addition, although the above-mentioned transmissive inspection before bonding is an auxiliary inspection, since the transmissive illumination system is separated from the inspection substrate by more than 3 m or more, the roughness may not be easily determined, such as a defect. Therefore, due to such problems, unseen spots before bonding may appear in a changed environment after bonding, which may cause an increase in bonding process cost or a decrease in yield of the liquid crystal panel after bonding due to failure to find a defective substrate early.

The present invention has been made to solve the above problems of the prior art, an object of the present invention, in order to be able to inspect in an environment similar to the environment after the bonding in the substrate inspection before bonding, in order to be able to inspect the liquid crystal after the bonding before In a similar manner, the present invention provides a substrate inspection method and apparatus capable of inspecting defects such as stains more clearly by retarding transmitted light.

 In addition, another object of the present invention is to increase the reflection and transmission efficiency in order to more clearly inspect the defects such as stains in the inspection of the substrate before bonding, the substrate that can easily detect even defects such as fine stains An inspection method and apparatus are provided.

Further, another object of the present invention is to facilitate detection of defects such as stains in the inspection of the substrate before bonding, to determine a defective substrate before bonding so that the defective substrate does not proceed to the bonding process, and then To provide a substrate inspection method and apparatus that can improve the yield.

According to one aspect of the present invention for realizing the technical problem described above, the substrate inspection method for inspecting the state of the substrate by irradiating light to the substrate, the polarization means for passing the light in a specific vibration direction, two vibration directions of light Contacting phase retardation means for generating a phase difference of the components, and one transparent mirror having a predetermined reflectance and transmittance of light, and placing a substrate on the one transparent mirror; Irradiating light under the polarizing means; And inspecting light transmitted through the substrate by light irradiated under the polarizing means.

In the inspecting step, the color shift is inspected while rotating the other polarization means on the substrate, and the substrate may be a top plate or a bottom plate before bonding for the liquid crystal display.

In the inspecting step, the light passing through the diffuser plate complementing the uniformity of the light from the light source is irradiated under the polarizing means.

After placing the substrate, irradiating light on the substrate; And inspecting the light reflected from the substrate by the light irradiated on the substrate.

According to another aspect of the present invention for realizing the above technical problem, the substrate inspection method for inspecting the reflection and transmission state of the substrate, the polarizing means for passing the light in a specific vibration direction, the light of the two above the polarizing means Contacting phase retardation means for generating a phase difference between the vibration direction components, and one transparent mirror having a predetermined reflectance and transmittance of light, and placing a pre-bonding substrate for the liquid crystal display on the one transparent mirror; And performing reflection inspection of the substrate by irradiating light on the substrate, or performing transmission inspection of the substrate by irradiating light under the polarizing means.

According to another aspect of the present invention for realizing the above technical problem, the substrate inspection apparatus for inspecting the reflection and transmission state of the substrate, BLU (Back Light Unit); A diffusion plate that complements the uniformity of light from the BLU on the BLU; A polarizing film on the diffusion plate; A phase retardation film placed on the polarizing film and generating a phase difference between two vibration direction components of light; And a one-sided transparent mirror placed on the phase retardation film, placing a substrate to be inspected on the one-sided transparent mirror, and irradiating light with a light source means on the substrate to perform a reflection test on the substrate, and in the BLU Irradiate light to perform a transmission inspection on the substrate.

According to another aspect of the present invention for realizing the above technical problem, the substrate inspection apparatus for inspecting the reflection and transmission state of the substrate, the rotation unit supported by the rotation axis; And a near-field transmission illumination system mounted on the rotation unit, placing a substrate to be inspected on the near-field transmission illumination system, and adjusting the inclination angle of the substrate by using the rotation unit, and the near-field transmission illumination system of the rotation unit The inspection position is adjusted by moving along a guide, and the near-field transmission illuminator touches a polarizing film, a phase retardation film that generates a phase difference between two vibration direction components of light, and one transparent mirror having a predetermined reflectance and transmittance of light. By using the above structure, the reflection efficiency of the light is increased during the reflection inspection on the substrate placed on the one-side transparent mirror, and the light from the light source under the polarization film is transmitted through the polarization film, Passing through the phase delay film, the one-sided transparent mirror and the substrate It is characterized by. The substrate inspection apparatus may further include a reflection illumination system that irradiates light on the substrate during the reflection inspection.

Hereinafter, with reference to the accompanying drawings and the contents described in the accompanying drawings will be described in detail a preferred embodiment of the present invention. However, embodiments and drawings to be described below are not to be construed as limiting or limiting the scope of the technical idea of the present invention. Like reference numerals in the drawings denote like elements.

First, in order to facilitate understanding of the present invention, a color shift phenomenon in the liquid crystal will be described with reference to FIGS. 6 to 11.

In the bonding process of the upper plate (CF substrate) and the lower plate (TFT substrate) for a liquid crystal display device, a sealing agent is applied to an edge of one substrate, for example, a TFT substrate, and the other substrate, for example, The CF substrate is formed by dispersing a column spacer (CS) such that the two substrates have a predetermined gap between the two substrates, attaching the two substrates, injecting liquid crystal using a capillary phenomenon, and then sealing the injection hole.

At this time, the liquid crystal injected between the CF substrate and the TFT substrate is an optically anisotropic material, and when light passes through the liquid crystal, it causes a birefringence phenomenon. As the electromagnetic wave, light is a synthesized wave represented by a vector sum of two waves oscillating in the direction of the coordinate axis Ex and Ey perpendicular to the electric field E as shown in FIGS. 6 to 8. Therefore, when light passes through the liquid crystal, a phase difference occurs between the waves due to the difference in the propagation speed along the vibration direction of each wave of light, that is, the Ex and Ey directions, and the birefringence according to the different polarization directions Light of color is observed from different angles. As described below, the polarization state of the liquid crystal may be in the form of linear, circular, ellipse, and the like. In the liquid crystal of the IPS (In-Plane Switch) mode, the liquid crystal may be changed through an initial molecular arrangement or an arrangement change depending on an applied voltage. It is possible to change to the desired polarization state.

6 is a view for explaining linear polarization of light. For example, when the light passes through the liquid crystal and the phase difference between the two waves 61 and 62 oscillating in the Ex and Ey directions is an integer multiple of π, as shown in FIG. 6, the synthesized wave E 63 is the coordinate axis Ex. Vibrates at a diagonal of and Ey, and this is called linear polarization.

7 is a view for explaining circular polarization of light. For example, if the phase difference between the two waves 71 and 72 oscillating in the Ex and Ey directions when light passes through the liquid crystal is an odd multiple of? / 2, the synthesized wave E 73 as shown in FIG. Rotates the electric field plane by the coordinate axes Ex and Ey in a circular manner, and this is called circular polarization.

8 is a diagram for explaining elliptical polarization of light. For example, if the phase difference between two waves 81 and 82 oscillating in the Ex and Ey directions when light passes through the liquid crystal is an even multiple of π / 4, the synthesized wave E 83 as shown in FIG. 8. Rotates the electric field plane by the coordinate axes Ex and Ey in an ellipse, and this is called elliptical polarization.

9 is a view for explaining the phase delay of light. For example, as shown in FIG. 9, when the unpolarized original light is passed through the polarizing film so as to pass only light in a specific vibration direction, and then passes through a phase retarder such as a polymer film or a liquid crystal, in the two coordinate axes Ex and Ey directions The polarization state changes due to the phase difference between two oscillating waves, and thus color shift occurs. The phase difference between the two waves in the phase retarder, that is, the phase retardation Δø, is represented by Equation 1, the wavelength of light λ, the cell gap of the liquid crystal, or the thickness d of the phase retarder. , Birefringence (Δn).

[Equation 1]

1.67π의 위상 지연으로 인하여, 도 9 및 도 10과 같이 타원 편광을 유지하며, 좌표축 Ex와 Ey에 의한 전기장 평면을 타원으로 회전한다. 또한, 이때, [수학식 1]에 따라, R의 파장의 빛도 870π/650

1.34π의 위상 지연으로 인하여, 도 9 및 도 10과 같이 타원 편광을 유지하며, 좌표축 Ex와 Ey에 의한 전기장 평면을 타원으로 회전한다. 따라서, 위와 같 이 액정을 통과하는 빛을 편광 필름을 회전하며 관찰할 때, 여러 방향에 따라 화이트(white), R, G, B 등의 빛이 관측되며, 도 10과 같이, 우대각에서는 R, G의 보색인 노랑(yellow) 빛이 관측될 수 있다. For example, when the combined light of R (red) with a wavelength of 650 nm, G (green) with a wavelength of 520 nm, and B (blue) light with a wavelength of 435 nm passes through the liquid crystal, the phase delay in the IPS mode liquid crystal is set to B. Assuming that an integer multiple of 2π of the wavelength (λΔø = 870π), the light of the wavelength of B maintains linear polarization and vibrates at diagonals of the coordinate axes Ex and Ey, as shown in FIGS. 9 and 10. At this time, according to [Equation 1], the light of the wavelength of G is 870π / 520

Due to the phase delay of 1.67π, elliptical polarization is maintained as shown in FIGS. 9 and 10, and the electric field plane by the coordinate axes Ex and Ey is rotated to the ellipse. In this case, according to Equation 1, the light having a wavelength of R is also 870π / 650.

Due to the phase delay of 1.34π, elliptical polarization is maintained as shown in FIGS. 9 and 10, and the electric field plane by the coordinate axes Ex and Ey is rotated to the ellipse. Therefore, when observing light passing through the liquid crystal while rotating the polarizing film as described above, light of white, R, G, B, etc. is observed in various directions, as shown in FIG. , Yellow light, the complementary color of G, can be observed.

과 G의 얼룩(114)의 적분값

의 비율로 나타낼 수 있다. 이때, 일반적으로 [수학식 2]와 같이, R, G, B 전체에 대한 얼룩의 명암비(CR) 보다는 G의 빛만 투과시킬 때의 얼룩의 명암비(CR')값이 크다. 11 is a diagram for explaining contrast ratio CR of a stain. In the liquid crystal display, the luminance of light passing through the liquid crystal is about 500 lux, and the transmittance 111 of B, the transmittance 112 of G, and the transmittance of the wavelengths as shown in FIG. By integrating the transmittance 113 of R, the luminance, which is the luminance per unit area, can be calculated. In this case, when the G spot 114 is formed as shown in FIG. 11, the contrast ratio CR of the blot is represented by Equation 2, and the B transmittance 111, the G transmittance 112, and the R transmittance ( 113) Sum of Integral Values

Integral of b and G blob 114

It can be expressed as a ratio. In this case, as shown in Equation 2, the contrast ratio (CR ') value of the stain when only the light of G is transmitted is larger than the contrast ratio (CR) of the stain to the entire R, G, and B.

[Equation 2]

Therefore, in the present invention, as described below, in the substrate inspection of the upper plate (CF substrate) or the lower plate (TFT substrate) for the liquid crystal display device, a phase retardation means is used to create an environment similar to that after the bonding. The color shift is performed according to the polarization state change by the phase retardation means, so that light of various colors can be observed at different angles, and the contrast ratio of each color is increased. Thus, even defects such as fine stains can be easily and more clearly inspected.

12 is a view for explaining the substrate inspection apparatus 120 according to an embodiment of the present invention. Referring to FIG. 12, a substrate inspection apparatus 120 according to an embodiment of the present invention is mounted on a rotating unit 121 and a rotating unit 121 installed to be supported by a rotating shaft 126. And may include a near-field transmission illumination system 122.

The rotary shaft 126 may be supported by a support mechanism on a predetermined stage that can move back, forth, left, and right, and the rotary shaft 126 by a predetermined rotation drive device (eg, a motor) to adjust the inclination angle. As the rotation rotates, the rotation unit 121 bitten by the rotation shaft 126 may also rotate with the rotation shaft 126 as the central axis. The near-field illumination system 122 for mounting and holding the substrate 123 to be inspected is installed to slide along a predetermined guide (for example, a rail structure) of the rotating unit 121. Thus, it is possible to adjust the vertical position of the inspection position during inspection of the large-area substrate.

In addition, although not shown in Figure 12, the substrate inspection apparatus 120 according to an embodiment of the present invention is a reflection illumination system for irradiating light on the substrate 123 to be inspected on the near-field transmission illumination system 122 at the time of reflection inspection It may further include.

In the present invention, as described below, in the reflection inspection, the light emitted from the light source of the reflective illumination system is irradiated to the substrate 123 to be inspected to inspect the reflected light, and in the transmission inspection, the short-range transmission illumination system 122 Light emitted from the mounted light source is inspected to pass through the substrate 123 to be inspected.

Herein, the substrate 123 to be inspected may be a top plate (CF substrate) or a bottom plate (TFT substrate) for bonding. In addition, various substrates may be placed on the near field illumination system 122 to inspect whether a predetermined thin film such as a transparent conductive film, an oxide film, a metal thin film, or a single color filter is appropriately coated on a transparent substrate such as glass. In particular, through a reflection test or a transmission test of a top plate (CF substrate) or a bottom plate (TFT substrate) before bonding for a liquid crystal display device, the inspector may apply or coat electrodes, color filters, and column spacers on the substrate 123. Defects such as unevenness due to nonuniformity, etc. can be confirmed, and a good / bad substrate can be discriminated.

A detailed configuration between the near-field illumination system 122 of FIG. 12 and the substrate 123 disposed thereon is shown in FIG. 13. Referring to FIG. 13, a short-range transmissive illumination system 122 for placing and holding a substrate 123 to be inspected according to an embodiment of the present invention may include a BLU (Back Light Unit) 131 and a diffusion plate 132. ), A polarizing film 133, a phase retardation film 134, and one transparent mirror 135.

12 illustrates an embodiment of the substrate inspection apparatus 120 for facilitating the handling of the substrate 123 when the length of one side of the substrate 123 to be inspected is large, such as 2 m and 3 m. Note that it is also possible to implement the substrate inspection apparatus and method of the present invention irrespective of whether the substrate is large or small by using only the near-field illumination system 122.

The BLU 131 is used as a light source for transmitting light upward from the bottom of the substrate 123 during the transmission inspection, and the illuminance of the light source itself so that the illuminance after transmission is about 500 lux as in a typical liquid crystal display (LCD). May be used at about 10,000 lux or more.

The diffuser plate 132 on the BLU 131 complements the uniformity of light coming from the BLU 131. That is, the diffusion plate 132 is used so that light generated from the BLU 131 having a general fluorescent lamp can be incident on the front surface of the substrate 123 with uniform and high luminance. In addition, a light guide plate, a prism plate, or the like may be further used on the diffusion plate 132 to increase luminance and improve a viewing angle.

The polarizing film 133 disposed on the diffuser plate 132 blocks light unnecessary for transmission among the light passing through the diffuser plate 132 and passes light in a specific vibration direction traveling upwardly.

The phase retardation film 134 disposed on the polarizing film 133 serves to act as a liquid crystal encapsulated when the CF substrate and the TFT substrate for the liquid crystal display are bonded together. It is possible to change the polarization state of light by generating a phase difference between components (wave components oscillating in the two coordinate axes Ex and Ey directions of the electric field plane, respectively).

As described above, when the liquid crystal encapsulated in the liquid crystal display device is an IPS mode liquid crystal, a phase delay of π or 2π occurs for B (blue) light incident on the liquid crystal and may be linearly polarized. In this case, G (green) and R (red) light have different phase retardation values as they pass through the liquid crystal due to the difference in birefringence, and as described in the description of FIG. Ellipses can be polarized. Liquid crystals of various modes may be applied to the liquid crystal display, and a phase amount of light may vary according to the liquid crystal applied.

Therefore, in the present invention, the phase retardation amount of the phase retardation film 134 may be variously selected to play a role similar to that of the liquid crystal after bonding in the substrate inspection before bonding the CF substrate and the TFT substrate for the liquid crystal display device. For example, for light causing linearly polarized light, a full-wave retarder (2π delay), a half-wave retarder (π delay), a quarter-wave retarder (π / 2 delay), or a 1/8 wavelength retarder ( π / 4 delay) and the like can be used as the phase delay film 134.

The one-sided transparent mirror 135 placed on the diffuser plate 132 is a film-type structure having a predetermined reflectance (for example, 50%) and transmittance (for example, 50%) of light. In order to increase the efficiency and during the transmission inspection, a part of the light emitted from the BLU 131 is transmitted toward the substrate 123 to be transmitted.

In the present invention, the polarizing film 133 is contacted with the polarizing film 133, the phase retardation film 134, and the one-sided transparent mirror 135 and then placed on the substrate 123 to be inspected thereon. The light from the BLU 131 below the light passes through the diffuser plate 132 to pass the polarizing film 133, the phase retardation film 134, the one-way transparent mirror 135, and the color filter 137 of the substrate 123. Visually inspect the light coming through (139 of FIG. 13) or analyze the image taken by the camera. Therefore, in the inspection of the substrate before bonding of the CF substrate and the TFT substrate for the liquid crystal display device, it is easy to detect defects such as stains in an environment similar to the environment after bonding in advance, such as phase retardation of transmitted light using the phase retardation film 134. Therefore, it is easy to determine whether the substrate is a bad substrate before bonding of the upper plate and the lower plate for the liquid crystal display device, and the defective substrate, which is determined as a good substrate because the determination is not clear as in the past, does not proceed to the bonding process. The failure determination rate of the panel, that is, the liquid crystal panel, can be reduced.

In addition, in the present invention, as well as using the light of the BLU 131 more efficiently than the method of irradiating light with a transmissive illumination system at a long distance as shown in FIG. 1, the uniformity or luminance improvement by the diffuser plate 132 is used. Therefore, the transmission efficiency is increased, and defects such as fine spots on the substrate 123 can be more clearly and easily inspected at high luminance.

In the present invention, in the reflection inspection, light is reflected from the color filter 137 or the like of the substrate 123 by irradiating light with the light source means (reflected illumination system) on the substrate 123 to be inspected (138 of FIG. 13). Visually inspect or analyze images taken with the camera. At this time, since light is reflected from the one-way transparent mirror 135 as shown in FIG. 13, the reflection efficiency is increased, and defects such as minute stains on the substrate 123 are more clearly and easily at high brightness of the reflected light. You can check it out. In the reflection inspection, light may be reflected from the polarizing film 133 or the phase retardation film 134 as well as the one-way transparent mirror 135, so that the reflection efficiency may be further increased.

On the other hand, as shown in Figure 12 in the case of inspecting by fixing the substrate 123 to be inspected in the near-field transmission system 122 with a predetermined holder, while adjusting the inclination angle of the substrate 123 while rotating the rotating unit 121, reflection and Transmissive inspection can be carried out, and the near-field transmission illuminator 122 can move along a predetermined guide of the rotation unit 121, so that the reflection and transmittance inspection can be performed by adjusting an appropriate up and down position of the substrate 123 by using this. .

Hereinafter, a method for inspecting a substrate according to an embodiment of the present invention will be described in more detail with reference to FIG. 14.

First, the CF substrate or the TFT substrate for the liquid crystal display to be inspected is placed on and fixed on the polarizing film 133, the phase retardation film 134, and the one-way transparent mirror 135, which are in contact with each other in the near-field illumination system 122. Let's do it. Regardless of the size of the substrate, the substrate 123 may be placed and inspected on the near-field transmission illumination system 122 as shown in FIG. 13, and when the apparatus of FIG. 12 is used, the rotation of the substrate 123 may be performed using the rotating unit 121. By adjusting the inclination angle, or by moving the near-field illumination system 122 along a predetermined guide of the rotation unit 121 to adjust the appropriate upper and lower positions to perform the reflection and transmission inspection.

By examining the reflection, that is, by irradiating the light on the substrate 123 and the light reflected from the substrate 123 by the irradiated light, it is possible to inspect whether there is a defect or the like according to the light reflection state of the base. At that time, the BLU 131 of FIG. 13 is turned off. In the transmission inspection, that is, when the backlight from the BLU 131 is transmitted through the substrate 123, the BLU 131 of FIG. 13 is used to inspect whether there is a defect or the like according to the light transmission state of the substrate 123. ) Is on. In the transmission test, the BLU 131 may be adjusted in advance in a state in which brightness thereof is adjusted in advance or a predetermined means so that the illuminance of the light transmitted onto the substrate 123 has an appropriate illuminance of about 500 lux (S141). The diffusion plate 132 placed on the BLU 131 allows the light to be uniformly and high luminance to the front surface (S142).

 In the reflection inspection, the polarizing film 133, the phase retardation film 134, and the one-sided transparent mirror 135, in particular, the one-sided transparent mirror 135 serve as an auxiliary means for increasing the reflection efficiency, and the polarizing film 133 in the transmission inspection. The block prevents unnecessary light from transmitting and only the light in a specific vibration direction proceeds to be transmitted (S143). In addition, the light passing through the polarizing film 133 in the transmission inspection passes through the phase retardation film 134 and the two vibration direction components of the light of each of R, G, and B colors (in the two coordinate axes Ex and Ey directions of the electric field plane). Each oscillating wave component) causes a phase difference, and thus the polarization state of light is changed similarly to the applied liquid crystal (S144). Part of the light passing through the phase retardation film 134 is partially transmitted by the one-way transparent mirror 133, and the light passing through the one-way transparent mirror 133 passes through the substrate 123 and comes out of the substrate 123 (S145). .

In general, since the reflectance of the color filter or the transparent conductive film of the substrate 123 before bonding for the liquid crystal display is improved in order to improve the luminance, the polarization film 133 and the phase delay in the reflection inspection are developed. Among the film 134 and the one-sided transparent mirror 135, in particular, if there is no one-sided transparent mirror 135, the reflected light is less and defect detection such as staining is not easy, but in the present invention, the one-sided transparent mirror 135 or the polarizing film ( Since light may be reflected from the 133 or the phase retardation film 134, defects such as minute stains on the substrate 123 may be more clearly and easily according to the brighter reflected light (138 of FIG. 13). Can be checked (S146).

Further, in the transmission inspection, light from the BLU 131 under the polarizing film 133 passes through the diffusion plate 132, the polarizing film 133, the phase retardation film 134, the one-way transparent mirror 135, and the substrate 123. When inspecting the light (139 of FIG. 13) passing through), defects such as minute stains on the substrate 123 may be more clearly and easily according to the increase in transmission efficiency by the near-field transmission system 122 and high luminance. Can be tested.

In particular, in the transmission inspection of the substrate before bonding of the CF substrate and the TFT substrate for the liquid crystal display device using the change in the polarization state of the light by the phase retardation film 134, the inspection is performed in an environment similar to the environment in which the liquid crystal after the bonding is present in advance. Because of this, it is possible to prevent the defective substrate having defects such as stains from proceeding to the bonding process. For example, when the amount of phase retardation of the phase retardation film 134 is π with respect to the B light, the B light transmitted over the substrate 123 is linearly polarized and the polarizing film 136 is disposed on the substrate 123 as shown in FIG. 13. As you rotate), you can see the B-light appearing color shifted in a certain direction. In addition, in the above example, the G and R light may be elliptically polarized (possibly circularly polarized), and may be different from the direction in which B light appears when the polarizing film 136 is observed while rotating on the substrate 123. You can see the G and R lights that appear color shifted in the other direction, or yellow light that is a mixture of them. In addition, white light can be observed from the other direction. Therefore, when visually inspecting the light transmitted over the substrate 123 or analyzing the image photographed by the camera, defects such as stains, which are not easily seen in the conventional method of observing the same color in all directions, are used by the color shift phenomenon. In light such as G, R, it can be observed well. Accordingly, it is possible to greatly contribute to preventing the phenomenon that the stain which was not seen in the substrate before bonding is found after bonding.

The substrate inspection apparatus and method according to the present invention can be modified and applied in various forms within the scope of the technical idea of the present invention. For example, in the embodiments of the present invention, the diffusion plate, the polarizing film, the phase retardation film, and the like contacted on the BLU is preferably in the form of a flexible film, but if necessary, they maintain similar functions or functions. It may be replaced by various structures such as hard plastic form or glass form. After all, the embodiments and drawings are merely for the purpose of describing the details of the invention, and are not intended to limit the scope of the technical idea of the invention, the scope of the present invention is not limited to the claims to be described later and It should be judged to include an even range.

As described above, in the substrate inspection apparatus and method according to the present invention, similarly to the role of the liquid crystal after the bonding before the bonding, the transmission light is delayed and inspected, so that staining and the like in an environment similar to the environment after bonding in the substrate inspection before bonding are performed. You can check the defect more clearly.

In the substrate inspection apparatus and method according to the present invention, in the inspection of the substrate before bonding, the reflection and transmission efficiency are increased by using a one-way transparent mirror, so that defects such as fine stains can be easily detected. You can check the defects more clearly.

 In addition, in the substrate inspection apparatus and method according to the present invention, since defects such as stains and the like are easily detected in the inspection of the substrate before bonding, the defective substrate can be determined in advance before bonding so that the defective substrate does not proceed to the bonding process. Therefore, the yield of the liquid crystal panel after bonding can be improved.

Claims (9)

In the substrate inspection method for inspecting the state of the substrate by irradiating the substrate with light, Polarizing means for passing light in a specific vibration direction, phase retardation means for generating a phase difference between two vibration direction components of light, and one transparent mirror having a predetermined reflectance and transmittance of light in contact therewith, Placing the substrate; Irradiating light under the polarizing means; And Inspecting light transmitted through the substrate by light irradiated under the polarizing means; Substrate inspection method comprising a. The method of claim 1, wherein the checking comprises: And inspecting the color shift while rotating the other polarization means on the substrate. The method of claim 1, wherein the substrate is a top plate or a bottom plate before bonding for a liquid crystal display device. The method of claim 1, wherein in the inspecting step, Light passing through a diffuser plate that complements the uniformity of light from a light source is irradiated under the polarizing means. The method of claim 1, wherein after placing the substrate, Irradiating light on the substrate; And Inspecting light reflected from the substrate by light emitted from the substrate; Substrate inspection method further comprising. In the substrate inspection method for inspecting the reflection and transmission state of the substrate, Polarizing means for passing light in a specific vibration direction, phase retardation means for generating a phase difference between two vibration direction components of light on the polarizing means, and one transparent mirror having a predetermined reflectance and transmittance of light, Placing a substrate before bonding for the liquid crystal display on the one transparent mirror; And Irradiating light on the substrate to perform reflection inspection of the substrate or irradiating light under the polarizing means to perform transmission inspection of the substrate Substrate inspection method comprising a. In the substrate inspection apparatus for inspecting the reflection and transmission state of the substrate, BLU (Back Light Unit); A diffusion plate that complements the uniformity of light from the BLU on the BLU; A polarizing film on the diffusion plate; A phase retardation film placed on the polarizing film and generating a phase difference between two vibration direction components of light; And One-way transparent mirror on the phase retardation film Including, Placing a substrate to be inspected on the one-sided transparent mirror, irradiating light with a light source means on the substrate to perform reflection inspection on the substrate, and irradiating light on the BLU to perform transmission inspection on the substrate. Substrate inspection apparatus, characterized in that. In the substrate inspection apparatus for inspecting the reflection and transmission state of the substrate, A rotating unit supported by the rotating shaft; And A near-field transmission illumination system mounted on the rotation unit, Placing a substrate to be inspected on the near-transmission illuminator, adjusting the inclination angle of the substrate using the rotation unit, and moving the near-transmission illuminator along the guide of the rotation unit to adjust the inspection position, The short-range transmissive illumination system uses the polarized film, a phase retardation film for generating a phase difference between two vibration direction components of light, and a structure in which a unidirectional transparent mirror having a predetermined reflectance and transmittance of light is sequentially contacted. The reflection efficiency of light is increased during the reflection inspection on the substrate placed thereon, and the light from the light source under the polarization film is transmitted through the polarization film, the phase retardation film, the one-sided transparent mirror and the transmission inspection on the substrate; And a substrate inspection device for passing through the substrate. The method of claim 8, Reflective illumination system for irradiating light on the substrate during the reflection test Substrate inspection apparatus further comprising.

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