KR100848949B1 - Liquid Crystal Modulator and Apparatus for Testing Electrodes on Substrate - Google Patents

Abstract

The present invention relates to a liquid crystal modulator in which the gap agent is uniformly distributed so that the characteristics of the beam do not change in the liquid crystal layer and a substrate inspection apparatus using the same.

The liquid crystal modulator according to the present invention includes a lower substrate, an upper substrate located at a predetermined distance from the lower substrate, a liquid crystal layer positioned between the upper substrate and the lower substrate, and a liquid crystal layer in order to maintain a gap between the liquid crystal layer. And a common electrode formed on a surface of the upper substrate facing the lower substrate, and a reflecting plate formed on a surface opposite to the surface of the lower substrate contacting the liquid crystal layer.

LCD Modulator, LCD, Substrate Inspection System

Description

Liquid Crystal Modulator and Substrate Inspection Apparatus Using It {Liquid Crystal Modulator and Apparatus for Testing Electrodes on Substrate}

1 is a schematic diagram of a TFT substrate inspection apparatus by a voltage imaging method using a liquid crystal modulator according to the prior art.

2 is a cross-sectional view of a liquid crystal modulator according to the prior art.

3 is a cross-sectional view of a liquid crystal modulator for explaining a problem of the liquid crystal modulator according to the prior art.

4 is a cross-sectional view of the liquid crystal modulator for explaining the problem of another liquid crystal modulator according to the prior art.

5 is a cross-sectional view of the liquid crystal modulator according to the first embodiment of the present invention.

6 is a cross-sectional view of a liquid crystal modulator according to a second embodiment of the present invention.

7 is a cross-sectional view of the liquid crystal modulator for explaining the effect on the operation of the liquid crystal modulator according to the thickness of the lower substrate in the liquid crystal modulator according to the present invention.

<Description of Symbols for Major Parts of Drawings>

121, 121-1: Upper board

122, 122-1: common electrode

123, 123-1: liquid crystal layer

124, 124-1: lower substrate

125, 125-1: Reflector

126: optical gap agent

126-1: Attachable Gap Agent

The present invention relates to a liquid crystal modulator, and more particularly, to a liquid crystal modulator in which a gap agent is uniformly distributed so that a characteristic of a beam does not change in a liquid crystal layer and a substrate inspection apparatus using the same.

In general, the display device includes a liquid crystal display device, a plasma display device, and an organic light emitting device (Electro Luminance). BACKGROUND ART Liquid crystal display devices, which are widely used in recent years, include a liquid crystal panel for displaying an image, a backlight for supplying light to the liquid crystal panel, and a driving unit for supplying power to the backlight and the liquid crystal panel and generating a control signal to control them.

The liquid crystal plate is composed of an upper plate, a lower plate, and a liquid crystal layer positioned therebetween. A common electrode, a pixel electrode, and a plurality of thin film transistor (TFT) arrays are formed on surfaces of the upper and lower plates facing each other with respect to the liquid crystal layer. These electrodes and TFTs form pixels as the smallest unit of color for displaying an image. Accordingly, the electrodes and the TFT operate according to the signal output from the driver, so that the liquid crystal panel displays a predetermined image by the color displayed in pixel units.

As described above, in order for the liquid crystal panel to display an image, the electrodes forming each pixel must be driven correctly. To this end, the liquid crystal plate is subjected to an inspection process to determine whether each electrode is electrically defective before being mounted on the liquid crystal display.

Voltage image methods developed by PDI of the United States are used to examine defective pixels of a liquid crystal panel (hereinafter referred to as TFT liquid crystal panel) composed of TFT arrays. The voltage imaging method is a method of detecting a defect of a pixel of a TFT liquid crystal plate using a liquid crystal modulator. More specifically, the voltage imaging method detects pixel defects by applying a bias voltage between the pixel electrode of the TFT liquid crystal plate and the common electrode of the liquid crystal modulator, and then analyzes and analyzes the optical characteristics of the liquid crystal modulator. The voltage imaging method is described in detail with reference to the drawings.

Fig. 1 is a schematic view of a TFT liquid crystal plate inspection apparatus by a voltage imaging method using a liquid crystal modulator according to the prior art, and is composed of a liquid crystal toilet 20 and an optical portion 10.

The optical unit 10 reflects from the light source 4 for generating and outputting a predetermined beam, the beam splitter 3 for changing the direction of the beam emitted from the light source 4, and illuminating the liquid crystal modulator 20, and the liquid crystal modulator 20. And an image detector 1 that collects the beams that have passed through the beam splitter 3, and an image detector 1 that enters the beam collected from the imager 2.

The liquid crystal modulator 20 is positioned on the TFT liquid crystal plate 30 at a distance of about 20 μm.

The operation of the TFT liquid crystal panel inspection apparatus configured as described above is as follows.

The bias voltage V is applied to the pixel electrode 32 of the TFT liquid crystal panel 30 and the common electrode of the liquid crystal modulator 20, and the beam emitted from the light source 4 passes through the beam splitter 3 to the liquid crystal modulator 20. Is incident on. At this time, if the pixel electrode 32 of the TFT liquid crystal plate is defective, the voltage applied to the liquid crystal layer of the liquid crystal modulator is changed. Accordingly, the polarization state and the luminous intensity of the beam reflected by the liquid crystal modulator are different from the unbiased state and the luminous intensity of the incident beam.

In this way, the reflected beam from the liquid crystal modulator, which has a characteristic changed from the characteristic of the incident beam, is incident on the image detector 1 through the image forming lens 2. Then, the image detector 1 converts the beam incident from the liquid crystal modulator 20 into an electrical signal (for example, a voltage) and outputs the converted signal. Therefore, whether or not the state of the electrode 32 of the TFT liquid crystal plate 30 being inspected is determined through the output electric signal.

On the other hand, the flatness is important because the liquid crystal modulator 20 must be aligned at a constant height from the substrate on the TFT substrate. Referring to the structure of the conventional liquid crystal modulator in detail with reference to the drawings as follows.

2 is a cross-sectional view of the liquid crystal modulator 20-1 according to the prior art.

The conventional liquid crystal modulator 20-1 includes an upper substrate 21-1, an upper substrate 21-1, and a lower substrate located at a predetermined distance from the lower substrate 24-1 and the lower substrate 24-1. In order to maintain the gap between the liquid crystal layer 23-1 and the liquid crystal layer 23-1 positioned between 24-1, a spacer 26-1 and a lower substrate 24- in the liquid crystal layer are provided. The common electrode 22-1 formed on the surface of the upper substrate 21 facing 1) and the reflecting plate 25-1 formed on the surface opposite to the surface of the lower substrate in contact with the liquid crystal layer 23-1.

The upper substrate 21-1 is made of a relatively thick glass material to prevent bending. The lower substrate 24-1 is made of a glass material having a relatively thin thickness. The reflecting plate 25-1 is formed by alternately stacking thin films made of a dielectric material having a high refractive index on the surface of the lower substrate.

However, such a conventional liquid crystal modulator has the following problems.

First, the conventional liquid crystal modulator uses a spacer 26-1 so that the spacer 26-1 moves freely in the process of polishing the lower substrate 24-1. Therefore, as shown in FIG. 3, the gap agent 26-2 is collected in the liquid crystal layer 23-2. In this manner, when the gap agents are collected, the beam passing through the liquid crystal modulator does not change in polarization state at that portion, and thus the substrate inspection apparatus cannot accurately detect the defective state of the electrode of the TFT liquid crystal plate 30-2.

Further, when the lower substrate 24-3 of the conventional liquid crystal modulator is very thinly polished to about 20 mu m, the lower substrate 24-3 is bent like vinyl or paper as shown in FIG. When the lower substrate is bent, the thickness of the liquid crystal layer 23-3 varies depending on the position thereof, thereby increasing the variation in the thickness of the liquid crystal layer. Therefore, the beam reflected by the reflective layer 25-3 of the liquid crystal modulator 20-3 has a different polarization state, so that the substrate inspection apparatus cannot accurately detect the defective state of the electrode of the TFT liquid crystal plate.

Disclosure of Invention An object of the present invention is to provide a liquid crystal modulator in which a gap agent is uniformly distributed so as not to change a beam characteristic in a liquid crystal layer, and a substrate inspection apparatus using the same.

To this end, the liquid crystal modulator according to the present invention includes a lower substrate, an upper substrate located at a predetermined distance from the lower substrate, a liquid crystal layer positioned between the upper substrate and the lower substrate, and to maintain a gap between the liquid crystal layers. And a reflecting plate formed on a surface opposite to a surface of the lower substrate in contact with the liquid crystal layer, the fixing electrode having a fixed gap in the liquid crystal layer, a common electrode formed on the surface of the upper substrate facing the lower substrate.

According to the present invention, a substrate inspection apparatus using a liquid crystal modulator is achieved by including a liquid crystal modulator and an optical unit in which a gap agent is uniformly distributed so that the characteristics of a beam do not change in the liquid crystal layer.

The liquid crystal modulator may include a lower substrate, an upper substrate positioned at a predetermined distance from the lower substrate, a liquid crystal layer positioned between the upper substrate and the lower substrate, and a lower substrate formed to maintain a gap between the liquid crystal layer. In the process, the fixed gap agent fixed to the lower substrate positioned in the liquid crystal layer, a common electrode formed on the surface of the upper substrate facing the lower substrate, formed on the surface opposite to the surface of the lower substrate in contact with the liquid crystal layer It includes a reflector.

Here, the optical unit generates a light beam for generating and outputting a predetermined beam, a beam splitter for changing the direction of the beam emitted from the light source and shining on the liquid crystal modulator, and collecting the beams that have passed through the beam splitter after being reflected from the liquid crystal modulator. The main image includes an imaging lens and an image detector for incident a beam collected from the imaging lens.

Referring to the liquid crystal modulator 120 according to the present invention in detail with the drawings as follows.

5 is a cross-sectional view of the liquid crystal modulator 120 according to the first exemplary embodiment of the present invention, wherein the upper substrate 121 and the upper substrate 121 are located at a predetermined distance from the lower substrate 124 and the lower substrate 124. In order to maintain a gap between the liquid crystal layer 123 and the liquid crystal layer 123 positioned between the lower substrate 124, a photo spacer 126 in the liquid crystal layer and a surface of the upper substrate facing the lower substrate. The reflection electrode 125 is formed on a surface opposite to a surface of the lower substrate in contact with the common electrode 122 and the liquid crystal layer 123.

Here, the photo spacers 126 are made of a photosensitive member so as not to move in the liquid crystal layer. The process of forming the optical gap agent is as follows.

A photopolymer, such as a photo-resist, is formed by coating a substrate on the substrate in several micrometers, and then leaving only a specific portion of the coating portion in the exposure process. The optical gap agent thus formed does not move in the polishing process of thinning the lower substrate 124 and maintains its position. Therefore, when the liquid crystal modulator is finally manufactured, the optical gap agent is uniformly distributed in the liquid crystal layer 123.

On the other hand, the upper substrate 121 is made of a relatively thick glass material in order to prevent bending. The lower substrate 124 is made of a glass material having a relatively thin thickness. The reflector plate 125 is formed by alternately stacking thin films made of a dielectric material having a high refractive index on the surface of the lower substrate.

Therefore, the liquid crystal modulator according to the first embodiment of the present invention does not change the characteristics of the beam, thereby allowing the substrate inspection apparatus to accurately detect whether or not the substrate is defective.

6 is a cross-sectional view of the liquid crystal modulator 120-1 according to the second exemplary embodiment of the present invention, and the upper substrate 121-1 located at a predetermined distance from the lower substrate 124-1 and the lower substrate 124-1. ), A liquid crystal layer 123-1 positioned between the upper substrate and the lower substrate, an adhesive spacer 126-1 in the liquid crystal layer to maintain a gap between the upper and lower substrates, and a lower substrate. The common electrode 122-1 formed on the surface of the upper substrate and the reflective plate 125-1 formed on the surface opposite to the surface of the lower substrate in contact with the liquid crystal layer.

Here, the attachment type gap agent 126-1 includes the gap agent 121-3 and the coating layer 121-2 formed of resin on the outside thereof. A process of attaching the attachment type gap agent 126-1 to the substrate will be described below.

First, an auxiliary film-type gap agent is sprayed onto the substrate, and then heat is applied to the substrate to reach a predetermined temperature. Then, the gap agent 121-3 is attached to the substrate while the resin forming the coating layer melts. The gap agent 121-3 thus formed is maintained in its position without being moved in the polishing process of thinning the lower substrate 124-1. Therefore, when the liquid crystal modulator is finally manufactured, the gap agent 126-3 is uniformly distributed in the liquid crystal layer.

On the other hand, the upper substrate 121-1 is made of a relatively thick glass material in order to prevent bending. The lower substrate 124-1 is made of a glass material having a relatively thin thickness. The reflector 125-1 is formed by alternately stacking thin films made of a dielectric material having a high refractive index on the surface of the lower substrate.

Therefore, the liquid crystal modulator 120-1 according to the second embodiment of the present invention does not change the characteristics of the beam, so that the substrate inspection apparatus accurately detects whether the substrate is defective.

When the gap agent is attached to the lower substrate by the method described so far, the lower substrate is subjected to the polishing process. The polishing process will be described in detail with reference to the drawings.

7 is a cross-sectional view of the liquid crystal modulator for explaining the effect of the thickness of the lower substrate of the liquid crystal modulator (120-a, 120-b) on the operation of the liquid crystal modulator according to the present invention.

If the lower substrate 124-a is thin, the liquid crystal layer 123-a is impacted in the polishing process, and the thickness of the liquid crystal layer is uneven. If the lower substrate 124-b is thick, the voltage applied to the liquid crystal layer 123-b is reduced, so that the sensitivity is lowered.

When the thickness of the lower substrate is about 30 탆 or less, the lower substrate almost loses elastic force like paper or vinyl. Therefore, the thickness of the lower substrate is implemented to be larger than 30㎛. On the other hand, when the thickness of the lower substrate is 100 µm or more, the horizontal resolution of the substrate inspection apparatus is reduced.

On the other hand, spontaneous polarization is induced at the interface of the dielectric and charge is generated at the interface. Since the charge of the spontaneous polarization by the external electric field is caused by a difference of 100 μm, the horizontal resolution is inferior. The thickness of the lower substrate is smaller than the pitch of the unit pixels of the TFT substrates 130-a and 130-b. Since the pixel pitch of the TFT liquid crystal display device is about 100 μm, the thickness of the lower substrate of the liquid crystal modulator is smaller than 100 μm.

Therefore, the liquid crystal modulator according to the present invention implements the lower substrate in the range of 30 to 100 μm in view of the above elements.

Meanwhile, the substrate inspection apparatus using the liquid crystal modulator according to the present invention includes a liquid crystal modulator and an optical unit according to the first or second embodiment.

The optical unit generates a predetermined beam and outputs it, a beam splitter that changes the direction of the beam emitted from the light source, and illuminates the liquid crystal modulator, an imaging lens that collects beams that have passed through the beam splitter after being reflected from the liquid crystal modulator, and an imaging lens. It consists of an image detector that enters the beam collected from the.

In the embodiment of the present invention, the substrate inspection apparatus performs a defect inspection on the substrate of the TFT liquid crystal display device, but may be applied to other display apparatuses.

The liquid crystal modulator according to the present invention does not change the characteristics of the beam incident from the outside because the gap agent is uniformly distributed in the liquid crystal layer.

In addition, the substrate inspection apparatus using the liquid crystal modulator can accurately detect a defective state of the substrate.

Claims (7)

Lower Board, An upper substrate located at a predetermined distance from the lower substrate, A liquid crystal layer positioned between the upper substrate and the lower substrate, In order to maintain the gap of the liquid crystal layer, a fixing type gap agent in the liquid crystal layer, A common electrode formed on a surface of the upper substrate facing the lower substrate, And a reflector formed on a surface opposite to a surface of the lower substrate in contact with the liquid crystal layer. The method of claim 1, wherein the fixed gap agent Characterized in that it comprises photo spacers, The optical gap modulator is formed by coating a photopolymer such as a photoresist (PR) on the lower substrate with a thickness of several μm, and then leaving only a specific portion of the coating portion in an exposure process. . The method of claim 1, wherein the fixed gap agent It characterized in that it comprises an adhesive spacer (adhesive spacer), Here, the attachment type gap agent is a liquid crystal modulator, characterized in that the gap agent and a resin forming a coating on the outside thereof. Liquid crystal modulator in which the gap agent is uniformly distributed so that the characteristic of the beam does not change in the liquid crystal layer, It characterized in that it comprises an optical unit, Here, the liquid crystal modulator Lower Board, An upper substrate located at a predetermined distance from the lower substrate, A liquid crystal layer positioned between the upper substrate and the lower substrate, In order to maintain the gap of the liquid crystal layer, the fixing substrate is fixed to the lower substrate in the process of forming the lower substrate is located in the liquid crystal layer, A common electrode formed on a surface of the upper substrate facing the lower substrate, A reflection plate formed on a surface opposite to a surface of the lower substrate in contact with the liquid crystal layer; Here, the optical unit A light source for generating and outputting a predetermined beam; A beam splitter for changing the direction of the beam emitted from the light source to illuminate the liquid crystal modulator; An imaging lens for collecting beams reflected from the liquid crystal modulator and then passing through the beam splitter; And an image detector for incident a beam collected from the imaging lens. The method of claim 4, wherein the fixed gap agent Characterized in that it comprises photo spacers, The optical gap modulator is formed by coating a photopolymer such as a photoresist (PR) on the lower substrate with a thickness of several μm, and then leaving only a specific portion of the coating portion in an exposure process. Substrate inspection device using. The method of claim 4, wherein the fixed gap agent It characterized in that it comprises an adhesive spacer (adhesive spacer), Here, the adhesion type gap agent is a substrate inspection apparatus using a liquid crystal modulator, characterized in that the gap agent and a resin that forms a coating on the outside thereof. The method according to any one of claims 4 to 6, And the thickness of the lower substrate is smaller than the pitch of the pixels of the substrate to be inspected.

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