KR101305366B1 - Inspecting method for the rubbing state on alignment layer forming on substrate - Google Patents

Abstract

The present invention includes forming a liquid crystal layer on the rubbed alignment layer in a substrate having a rubbing completed alignment layer; Measuring a retardation value of the substrate having the liquid crystal layer through rubbing inspection equipment; By providing a rubbing test method comprising the step of determining whether the measured retardation value is within the error range to determine whether there is a rubbing defect, the uncertainty of the rubbing test, such as the result is changed according to the ability of the conventional inspector is eliminated In addition, it is possible to determine whether the defect through the numerically quantified data, there is an effect of proceeding a stable rubbing test.

Rubbing, alignment film, rubbing state, liquid crystal layer, thermal evaporation

Description

Inspecting method for the rubbing state on alignment layer forming on substrate}

Figure 1a and 1b is a step-by-step diagram showing a rubbing inspection method of a conventional substrate for a liquid crystal display device.

Figure 2a and 2b is a step-by-step diagram showing a rubbing inspection method of the substrate for a liquid crystal display device of the present invention.

3 is a view of a rubbing inspection method (visual inspection) of a substrate for a liquid crystal display device according to the present invention;

<Description of the symbols for the main parts of the drawings>

110 substrate 115 alignment film

120: liquid crystal layer 130: vacuum chamber

131: stage 133: hot plate

136: surface plate 139: liquid crystal

The present invention relates to a liquid crystal display device, and more particularly, to a rubbing inspection method of a substrate for a liquid crystal display device.

Recently, with the rapid development of the information society, the need for a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption has emerged.

Such a flat panel display may be divided according to whether it emits light or not. A light emitting display is one that displays an image by emitting light by itself, and a display is performed by displaying an image using an external light source. It is called a display device. The light emitting display includes a plasma display panel, a field emission display, an electro luminescence display, and the light receiving display includes a liquid crystal display. display).

Dual liquid crystal display devices are being actively applied to notebooks and desktop monitors because of their excellent resolution, color display, and image quality.

The liquid crystal display device arranges two substrates on which electrodes are formed so that the surfaces on which the two electrodes are formed face each other, injects a liquid crystal between the two substrates, and then applies a voltage to the two electrodes to form a liquid crystal. It is a device that expresses an image by controlling light transmittance by moving molecules.

The liquid crystal panel for a liquid crystal display device includes a process of manufacturing an array substrate in which pixel electrodes and thin film transistors, which are switching elements, are formed for each pixel, and a common electrode and red, green, and blue colors correspond to each pixel as opposed to the array substrate. After injecting the liquid crystal between the process of manufacturing the color filter substrate is formed and the array substrate and the color filter substrate produced through the two processes, and then proceeds to a series of bonding process is completed.

The liquid crystal panel manufacturing process is called a cell process, and the cell process combines two substrates with an alignment process for aligning liquid crystals in one direction to an array substrate on which thin film transistors are arranged and a color filter substrate on which a color filter is formed. ) Can be roughly divided into a cell gap forming process, a cell cutting process, and a liquid crystal injection process.

The alignment process among many processes for forming such a liquid crystal panel will be described in more detail.

The alignment process is divided into an alignment film forming process and a rubbing process.A polymer film is formed on an array substrate in which thin film transistors are arranged for each pixel and a color filter substrate in which red, green, and blue color filters are formed corresponding to the pixels of the array substrate. Phosphorus polyimide (Polyimide) is coated to form an alignment layer. The alignment film, which is the polyimide, is printed on the front surface of the array substrate and the color filter substrate so as to have a predetermined pattern mainly by a roll coating method. Thereafter, the two substrates on which the alignment layer is printed are preliminarily dried and baked to form a cured alignment layer.

Next, a rubbing process is performed on the upper and lower substrates on which the cured alignment layer is formed as a second step of the alignment process. The polymer chains on the surface of the alignment layer are aligned in a predetermined direction by rapidly rotating the wound roller having the grains aligned in one direction on the cured alignment layer surface and rubbing at pressure and speed with respect to the surface of the alignment layer. The rubbing is a main process of determining the initial alignment direction of the liquid crystal, and has a normal display drive and normal driving of the liquid crystal.

The substrate subjected to this rubbing process is subjected to a rubbing inspection to check whether rubbing is uniform. In this case, as shown in FIGS. 1A and 1B, pure water (DI) and clean dry air (CDA) are supplied. In the state where water vapor is formed on the alignment layer of the substrate 10 by spraying water vapor 22 on the surface of the rubbed substrate 10 by using the water vapor generator 20 to generate water vapor 22 by condensing it. It is progressing by performing visual inspection which observes the scattered degree using the light irradiated by the lamp (not shown) located in the lower part of the said board | substrate 10. FIG.

In the rubbing test using the water vapor 22, as shown in FIG. 1A, in the spraying water vapor 22, the inspection is performed because the light irradiated from the visual field of the inspector and the lamp (not shown) is covered by the water vapor 22. Since the water vapor 22 is sprayed onto the surface of the substrate 10, the visual inspection is performed on the portion A1 formed with the water vapor in the state where the water vapor is formed on the substrate 10.

However, in this case, the time for maintaining the water vapor 22 on the substrate 10 is typically less than 10 seconds, so the inspector should investigate whether rubbing failures have occurred for 10 seconds, and after 10 seconds have elapsed. Since the water vapor 22 is removed from the surface of the substrate 10, the water vapor 22 is to be injected again and then the inspection of the rubbing state should be performed.

Furthermore, even if the rubbing defect is found while the vapor 22 remains on the substrate 10, when the vapor 22 is removed, the place where the rubbing defect occurs is also disappeared. There is a problem that is difficult to do.

In addition, in the rubbing inspection using the water vapor 22, when the water vapor 22 is sprayed onto the substrate 10 using the water vapor generator 20, a water vapor phenomenon occurs in which not only water vapor but water droplets are splashed. The foreign matter in the air is trapped by the water vapor 22 and adsorbed onto the substrate 10 when exposed to the water vapor 22, thereby causing a defect caused by the foreign material.

In addition, the rubbing test using the water vapor 22 determines whether there is a defect with the degree of scattering of light, so it is impossible to check the minute defects when rubbing, and the efficiency and accuracy of the test are determined by the inspector's inspection ability. Since it is determined that the unskilled inspector does not detect the rubbing defects, there is a possibility that a large amount of defects may be caused due to the characteristics of the rubbing process that causes the whole defect when the defects occur.

In order to solve the above problems, the present invention is a rubbing test that can determine the presence or absence of defects through the quantified data irrespective of the tester's ability by replacing the rubbing state test using water vapor that cannot be quantified or depending on the tester's ability Its purpose is to provide a method.

In order to achieve the above object, a rubbing inspection method according to an exemplary embodiment of the present invention includes forming a liquid crystal layer on the rubbed alignment layer in a substrate having an alignment layer on which rubbing is completed; And irradiating the substrate having the liquid crystal layer using a lamp and determining rubbing defects through color change of the liquid crystal layer through which the irradiated light is transmitted or reflected, wherein the liquid crystal layer is formed by thermal deposition. Is characteristic.

In this case, the liquid crystal layer is characterized by being formed of a single liquid crystal (single LC).

In addition, the liquid crystal layer is characterized in that formed in a thickness of 10 ~ 20Å, the step of forming the liquid crystal layer by thermal deposition, the step of positioning the substrate in the chamber of the liquid crystal deposition equipment so that the alignment layer facing the ground; ; And vaporizing the liquid crystal by heating a liquid crystal facing the alignment layer, wherein the vaporization of the liquid crystal is performed by heating a hot plate provided in the chamber, and the chamber is in a vacuum atmosphere. By forming a vacuum chamber capable of forming a lower liquid crystal breaking point is characterized in that the vaporization of the liquid crystal is carried out in a lower temperature range than in the normal atmosphere.

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Hereinafter, preferred embodiments according to the present invention will be described with reference to the accompanying drawings.

The rubbing test according to the present invention is characterized in that the rubbing state can be quantified by measuring a specific value (retardation value) using a specific device, and by quantifying the degree of rubbing state through such a retardation measuring device. It is characterized by the improvement of the conventional rubbing inspection which depends on the observation ability of an inspector.

The rubbing test according to the present invention has a step to be pretreated due to its characteristics, and for retardation measurement, a liquid crystal layer having birefringence should be formed, and thus, a step of forming a liquid crystal layer on the substrate after rubbing should be performed.

The formation of the liquid crystal layer before rubbing inspection will first be described with reference to the drawings.

2A and 2B are diagrams illustrating steps of performing a rubbing test according to an exemplary embodiment of the present invention.

As shown in FIG. 2A, an alignment process is performed to form an alignment layer 115 by applying a polymer material such as polyimide to form an alignment layer 115, and after curing the substrate 110, a rubbing process is performed. To move on the stage 131 in 130.

Next, the substrate 110 positioned on the stage 131 in the vacuum chamber 130 is completely attracted to the stage 131 by vacuum adsorption, and then the stage 131 is inverted on the substrate 110. The alignment layer 115 formed in the vacuum chamber 130 is positioned to face the ground in the vacuum chamber 130.

Subsequently, after the substrate 110 in the vacuum chamber 130 is provided with a hot plate 133 capable of heating the surface to an appropriate temperature and a surface plate 136 containing liquid crystal 139 thereon, The hot plate 133 is heated to an appropriate temperature (60 ° C to 300 ° C) to vaporize the liquid crystal 139 contained in the surface plate 136 so as to be deposited on the rubbed alignment layer 115 to have a predetermined thickness. A liquid crystal layer having

In this case, the liquid crystal 139 used in the present invention may be a single unit having different characteristics of several dozen types to satisfy complex characteristics such as viscosity, phase transition temperature, driving voltage, viscosity, refractive index anisotropy, and dielectric anisotropy. It is also possible to use a mixture of liquid crystals, but this is expensive, and since it does not affect the quality of the product due to the characteristics of the present invention, it is preferable that the single liquid crystal (single LC) having refractive index anisotropy. An example of such a single LC is phenyl cyclo hexane (PCH), which is a mixture of 10-20 or more single LCs to satisfy the aforementioned characteristics. Its cost is lower than that of a mixed liquid crystal, so it is suitable to be used for inspection purposes.

In addition, the liquid crystal layer 120 formed by heating and vaporizing the single LC, ie, formed on the alignment layer 115 by thermal evaporation, preferably has a thickness t of about 10 kPa to about 20 kPa.

The formation of the material layer by thermal evaporation has a relatively even thickness over the entire surface of the substrate, and by controlling the deposition time, a material layer of even thickness, which is much thinner and more uniform than the method of coating or coating, can be formed. to be.

At this time, the chamber 130 for vaporizing and depositing the liquid crystal is preferably a vacuum chamber 130 that can form a vacuum atmosphere. In order to vaporize the liquid crystal 139 in a general atmosphere, the liquid crystal must be heated to about 200 ° C. to 300 ° C. or more, but when it is carried out in a vacuum atmosphere, the boiling point of the liquid crystal is about 60 ° C. to 150 ° C. Because it can be lowered. The liquid crystal 139 has a tendency that the inherent characteristics of the liquid crystal 139 are deteriorated when exposed to high temperature for a long time, and the lowering of the characteristics of the liquid crystal 139 due to such heating is relatively low in the vacuum atmosphere in the vacuum chamber 130. It can prevent by heating by vaporizing.

Meanwhile, instead of forming the liquid crystal layer 120 to have the thickness t as described above, when the liquid crystal layer is formed to have a thickness of 2 μm to 4 μm, which is the thickness of the liquid crystal layer injected into a conventional liquid crystal panel, the thermal evaporation characteristics thereof are used. It takes a lot of time, since the liquid crystal is a liquid state having a viscosity, when the thick formed, the flow occurs, etc. In view of all these points, the liquid crystal layer 120 is formed to have a thickness (t) of about 10 ~ 20Å Experimentally most preferred.

 Next, after discharging the substrate 110 having the liquid crystal layer 120 having a thickness t of about 10 μs to 20 μs in the vacuum chamber 130, a cell gap measuring apparatus capable of retardation measurement ( Go to 150).

As shown in FIG. 2B, the inside of the cell gap measuring device 150 is provided with a polarizer 153 under the substrate 110 on which the liquid crystal layer 120 is provided, and the polarizer (above the substrate 110). An analyzer 156 orthogonal to 153 is provided, and a detector 159 is provided on the analyzer 156.

When measured using a cell gap measuring device having such a configuration, the polarization axis of the polarizer 153 is θ based on the rubbing direction of the substrate 110, and the polarization axis of the analyzer 156 is equal to r. Suppose you have

In this state, when the light having a specific wavelength band (mainly helium-nedium laser) is irradiated under the polarizer 153, the irradiated light passes through the inside of the substrate 110. The rotationally polarized light is incident into the detector 159 through the analyzer 156 to perform cell gap measurement.

In this case, a typical cell gap is

라 정의되며,

Is defined as

Where d is the cell gap (liquid crystal layer thickness), λ is the wavelength of incident light, Φ is the difference between the rubbing direction of the lower substrate and the upper substrate when the liquid crystal panel is implemented (in the present invention has a value of 0), and Δn is the refractive index of the liquid crystal. It becomes anisotropic.

If this equation is defined, Δn · d = λm (m = 1,2,3 ..), and if there is a change in the wavelength value of light measured by the detector, there is a change in Δn · d value. In this case, since the cell gap d has a value of 10 μs to 20 μs, rubbing defects for each position may be detected based on the change degree of Δn for each position of the liquid crystal layer 120 in consideration of the change in the cell gap. .

That is, the liquid crystal molecules in the liquid crystal layer 120 according to the present invention are formed on the alignment layer 115 on which the liquid crystal layer 120 is rubbed and are arranged in the same direction because no electric field is applied. In this case, refractive index anisotropy The Δn value should have the same value for the entire surface of the substrate 110. Therefore, the value of Δn · d should be within the range of the error range of the value d multiplied by Δn. When the value of the change in the wavelength measured by the detector 159 is calculated based on the above equation, If there is a difference in birefringence anisotropy (Δn), this means that there is a problem in rubbing condition that the liquid crystal molecules in the liquid crystal layer 120 are located in different directions compared to other regions, or the inclination angle is larger or smaller. It is an indicator that a value has been obtained, which means a rubbing failure.

In this case, the cell gap measuring device 150 further includes a processing device 162 for storing and outputting the data so that the wavelength value measured by the detector and the position information of the measuring point can be known. Even the location of rubbing defects can be clearly seen.

On the other hand, the substrate characterized in that the liquid crystal layer formed of a predetermined thickness according to the present invention can be quantified the position and the degree of failure of rubbing through the above-described cell gap meter, the inspector inspects the rubbing state with the naked eye after rubbing You may.

That is, referring to FIG. 3, which illustrates visual inspection of a substrate on which a liquid crystal layer is formed after rubbing, the liquid crystal layer 120 having a predetermined thickness on the above-described rubbed alignment layer 115 is described. ) To observe the transmitted light by irradiating light through a lamp or the like from the bottom surface with respect to the formed substrate 110, or when the reflected light is observed by directly irradiating light onto the liquid crystal layer 120. 120), the light of consistent color should be observed, but when the light with some color difference is observed, the arrangement of the liquid crystal molecules in the part is wrong, which indicates that rubbing failure has occurred.

In the case of the present invention, even in rubbing defect inspection by the inspector, the liquid crystal layer disappears after a certain period of time like water vapor, so that the visual inspection is stable without additional work such as periodically spraying water vapor. This has the advantage that it can be implemented.

As described above, by allowing the rubbing inspection to be carried out through the measuring device according to the present invention, the uncertainty of the rubbing inspection, such as the result of which depends on the ability of the inspector, is eliminated, and furthermore, whether there is a defect through the numerically quantified data. Bar is determined, there is an effect of proceeding a stable rubbing inspection.

In the case of the rubbing inspection proposed by the present invention when proceeding with the visual inspection by the inspector, it is easy to check whether there is a defect, and the inspection can be continuously carried out without time limitation, and thus the accuracy of the visual inspection can be focused on the observation of the substrate surface. This has a rising effect.

Claims (11)

delete Forming a liquid crystal layer on the rubbed alignment layer in a substrate having a rubbing completed alignment layer; Irradiating a substrate having the liquid crystal layer with a light using a lamp and determining rubbing defects through color change of the liquid crystal layer through which the irradiated light is transmitted or reflected; And a liquid crystal layer is formed by thermal evaporation. The method of claim 2, The rubbing inspection method, characterized in that the liquid crystal layer is formed of a single liquid crystal (single LC). delete The method of claim 2, Forming the liquid crystal layer by the thermal evaporation, Positioning the substrate in the chamber of the liquid crystal deposition apparatus so that the alignment layer faces the ground; Vaporizing the liquid crystal by heating a liquid crystal positioned to face the alignment layer Rubbing inspection method characterized in that it further comprises a. 6. The method of claim 5, The vaporization of the liquid crystal is a rubbing inspection method, characterized in that by heating of the hot plate provided in the chamber. The method of claim 6, The chamber is made of a vacuum chamber capable of forming a vacuum atmosphere by reducing the liquid crystal break point so that the vaporization of the liquid crystal is carried out in a lower temperature range than in the normal atmospheric atmosphere. The method of claim 2, The rubbing inspection method, characterized in that the liquid crystal layer is formed in a thickness of 10 ~ 20Å. delete delete delete

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