KR20140024186A - Reflective lc modulator and apparatus using the same - Google Patents

Reflective lc modulator and apparatus using the same Download PDF

Info

Publication number
KR20140024186A
KR20140024186A KR1020120090873A KR20120090873A KR20140024186A KR 20140024186 A KR20140024186 A KR 20140024186A KR 1020120090873 A KR1020120090873 A KR 1020120090873A KR 20120090873 A KR20120090873 A KR 20120090873A KR 20140024186 A KR20140024186 A KR 20140024186A
Authority
KR
South Korea
Prior art keywords
liquid crystal
substrate
light
crystal modulator
modulator
Prior art date
Application number
KR1020120090873A
Other languages
Korean (ko)
Inventor
노봉규
Original Assignee
세심광전자기술(주)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 세심광전자기술(주) filed Critical 세심광전자기술(주)
Priority to KR1020120090873A priority Critical patent/KR20140024186A/en
Publication of KR20140024186A publication Critical patent/KR20140024186A/en

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1306—Details
    • G02F1/1309—Repairing; Testing
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1326—Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Liquid Crystal (AREA)

Abstract

The present invention relates to a liquid crystal modulator (Thin Film Transistor) and TFT (Thin Film Transistor) substrate 500 inspection apparatus that reduces the interference effect of the vibration generated by using the air flotation method. The liquid crystal modulator has an air layer having a thickness of 20 to 50 μm on a TFT substrate, and measures the voltage of the pixel to determine whether there is a defect. The lower substrate of the liquid crystal modulator was very thin (20-40 탆), making it difficult to produce a dielectric mirror having more than 13 layers due to thermal expansion coefficient differences of thin films. In this case, light leaking from the dielectric mirror returned from the TFT substrate and caused interference, resulting in poor measurement accuracy. In the present invention, a light absorbing layer formed of an organic film is disposed on a substrate below the liquid crystal cell to block light leaking to the TFT substrate. Such a structure can be expected to improve productivity by accurately inspecting a TFT substrate.

Description

Reflective liquid crystal modulator and TFT substrate inspection device using the same {REFLECTIVE LC MODULATOR AND APPARATUS USING THE SAME}

The present invention relates to a liquid crystal modulator (Thin Film Transistor) substrate inspection apparatus using the same, and more particularly to a reflective liquid crystal modulator having a light absorption layer and a TFT substrate inspection apparatus using the same.

A TFT film includes a liquid crystal substrate for displaying an image, a backlight for supplying light to the liquid crystal substrate, and a driver for supplying power to the backlight and the liquid crystal substrate and generating control signals. The liquid crystal substrate is composed of a top plate, a bottom plate, and a liquid crystal layer disposed therebetween. On the opposing surfaces of the upper plate and the lower plate facing each other around the liquid crystal layer, a common electrode and a pixel electrode including a thin film transistor TFT are formed. The TFT array is operated by a signal output from the driver to display an image. In order for a liquid crystal substrate to display an image, electrodes and TFTs forming each pixel must be driven correctly. Therefore, before bonding the upper and lower substrates, it is necessary to inspect the pixel electrodes of the TFT substrates (usually the lower substrates) for defects. Currently, a method of inspecting whether a TFT substrate is defective by using an LC modulator is widely used.

1 is a perspective view of a liquid crystal modulator. FIG. 2 is an exploded view of the liquid crystal modulator of FIG. 1. The liquid crystal modulator can be largely divided into a body 100, left and right air buoys (Air Plate, 300, 400) and a frame 200 attached to an external optical unit. Attach the left and right air buoys (300, 400) to the body first, and put the body with the air buoy in the frame 200 to assemble.

The liquid crystal modulator moves to various places on the TFT substrate 500 and inspects the entire area of the TFT substrate 500. Figure 3 shows a plan view (a), a front view (b) and a perspective view (c) of the air buoy. The air buoy has six holes 302 left and right, and blows air at a constant pressure so that the liquid crystal modulator maintains a constant height above the TFT substrate 500. One of the six holes is paired with one at the left and one at the left and one at the left and one at the right and each at the measurement height, or safely Adjust the height to move. The measurement height is usually between 20 and 60 µm, and when it moves, the height is increased to 100 to 120 µm to prevent scratches caused by dust and debris between the modulator and the TFT substrate 500. The vandal-shaped structure 303 and the isolation dam 301 in the air buoy adjust the flow of air to ensure stability when the liquid crystal modulator changes its height to move after finishing the measurement and when the movement is completed and descends to the measuring position. It is an important factor in reducing the time required.

4 is a cross-sectional view of a conventional liquid crystal modulator body 100. The polarizing plate 8 is attached to one side of the support substrate 7 and the liquid crystal cell 10 is attached to the other side. The polarizing plate uses what has an adhesive agent on itself. The liquid crystal cell 10 is attached to the support substrate 7 using a transparent adhesive 6 through which light is transmitted. The lower substrate 1 of the liquid crystal cell 10 grinds the glass to make a thickness of about 20 to 40 μm. Between the lower substrate 1 and the liquid crystal 3 is a reflective film 2 made of a dielectric material. The remaining reference numeral 4 denotes a common electrode, and the reference numeral 5 denotes a liquid crystal cell upper plate. When the surface resistance of the dielectric reflector is low, the sensitivity is decreased by diluting to the average electric field by the resistive component of the dielectric reflector. The dielectric material should be selected so that the surface resistance is 10G 10 / ㎠ or more. The mode of the liquid crystal mainly uses TN (Twist Nematic). The liquid crystal modes are broadly classified into scattering type, polarizing type and absorption type. The scattering type uses a property in which light scattering varies according to a voltage change applied to a liquid crystal, such as a polymer dispersed liquid crysta (PDLC). The absorption type uses a light absorption characteristic that varies depending on a voltage change applied to the liquid crystal, such as a guest host (GH). Polarization type is the most commonly used mode in liquid crystal display devices, and at least one polarizer is required. The polarization characteristic of the light passing through the liquid crystal varies depending on the voltage applied to the liquid crystal. Typical polarization types include vertical alignment (VA) and twist nematic (TN).

The flatness of the liquid crystal modulator body is very important for the pixel of the TFT substrate to set the defective position accurately at about 80 mu m. The thickness of the support substrate is about 35 mm thick, the deviation of the thickness is about ± 10㎛, and the flatness of the cross section is about ± 1.2㎛.

5 is a schematic view for explaining the principle of operation of the liquid crystal modulator. The TFT substrate 500 has a configuration in which a pixel electrode 502 is formed on the glass substrate 501. The voltage V (B) is applied between the pixel electrode 502 formed on the glass substrate 501 of the TFT substrate 500 and the common electrode 4 of the liquid crystal modulator. In the TFT substrate, the liquid crystal modulator maintains a constant height. 6 is an equivalent circuit in this state. In FIG. 6, the capacitance of the lower substrate of the liquid crystal modulator and the dielectric reflective film is ignored. The capacitance C (LC) of the liquid crystal layer and the capacitance C (Air) of the air layer are connected in series. If a failure occurs that the normal voltage is not applied to the pixel electrode, the voltage applied to the liquid crystal is different, it is possible to determine whether the pixel electrode is defective by utilizing the polarization reflection characteristics of the liquid crystal due to the change in the applied voltage.

7 is a schematic diagram of a substrate inspection apparatus using a conventional liquid crystal modulator. A light splitter 42 generating and outputting a predetermined beam, a beam splitter 42 reflecting the beam from the light source 41 to the liquid crystal modulator 100, and a beam splitter after being reflected from the liquid crystal modulator ( The imaging lens 43 collects the beams passed through 42 and the image detector 44 measures the intensity of the beam collected from the imaging lens 43. If the voltage applied to the pixel electrode is different from the normal value, the polarization reflection characteristic of the light passing through the liquid crystal is changed and the light intensity is changed. In the conventional image detector, the light passing through the liquid crystal is received and then converted into an electrical signal to determine whether the pixel electrode is defective.

The dielectric reflective film 2 provided in the liquid crystal modulator is formed by alternately depositing two materials having different refractive indices. Silicon dioxide (SiO2) is used as the low refractive index material and titanium dioxide (TiO2) is used as the high refractive index material. The coating conditions of the dielectric reflective film are well known. The product of the refractive index and the thickness is 25% of the wavelength of the reflected light. The material of the liquid crystal cell lower plate 1 is a glass substrate having a thickness of about 20 to 40 μm. The dielectric reflecting film can be peeled off only when the deposition temperature is 120 ° C. or higher, and the film can be formed hard to maintain reliability. The reflectivity of the dielectric reflective film mainly depends on the number of layers. To increase the reflectivity, the number of layers to be coated must be large. If the number of layers of the dielectric reflective film is large, unevenness or flatness may occur due to the difference in the coefficient of thermal expansion between the dielectric reflective film and the glass under the liquid crystal cell. Since the bottom plate of the liquid crystal cell is thin and there is a difference in thermal expansion coefficient from the dielectric reflecting film, the dielectric reflecting film is made 13 or less layers. In this case, the reflectivity of the dielectric reflective film varies depending on the process, but is about 60 to 80%. 8 is an explanatory view showing that light leaking from the dielectric reflecting film is reflected by the TFT substrate and returned to the liquid crystal modulator. In FIG. 8, it is assumed that light enters the liquid crystal modulator slightly inclined. The incident light I (0) may be classified into light I (1) reflected by the dielectric reflective film and light I (2) reflected by the TFT substrate through the dielectric reflective film and passed through the dielectric reflective film. Since the liquid crystal modulator is buoyed by air to maintain a constant height, vibration is generated to a certain height direction. Due to this vibration, the path of light I (2) returning from the TFT substrate is continuously changed, and thus, I (1) and I (2) cause mutual interference, and the image detector recognizes that the light intensity is different. If the phase difference between the two lights is δ, the light intensity I of the detector may be represented by Equation 1 below.

Figure pat00001

Since the phase difference varies from region to region due to the vibration of the conventional liquid crystal modulator, there is a problem in that the intensity of light is uneven in the detector and the accuracy of the measurement is lowered.

Korean Patent Publication No. 10-2008-0069080 (July 25, 2008) Korean Patent Publication No. 10-2007-0112495 (November 27, 2007)

An object of the present invention is to propose a liquid crystal modulator capable of stably inspecting a TFT electrode of a lower substrate even in the vertical vibration generated in an air support system using a liquid crystal modulator.

The liquid crystal modulator according to the present invention includes a light absorbing layer that blocks light leaking from the dielectric reflective film, thereby blocking light reflected from the TFT substrate by the leaked light. Therefore, the liquid crystal modulator according to the present invention can stably check whether the TFT electrode of the lower substrate is defective even if vertical vibration occurs in accordance with the air flotation method.

The liquid crystal modulator according to the present invention can absorb light leaking from the dielectric reflective film by including a light absorbing layer, thereby removing the light reflected back from the TFT substrate by the leaked light and incident again to the liquid crystal modulator, thereby applying an air flotation method. However, since interference light generated by vibration does not occur, the measurement accuracy is increased, so that the pixel defect of the TFT substrate can be precisely inspected.

Furthermore, in the liquid crystal modulator of the present invention, the light absorbing layer is formed of an organic film, so that the elasticity is small and stretches well. Therefore, the lower substrate forming the liquid crystal modulator does not stress.

1 is a perspective view of a conventional liquid crystal modulator.
2 is an exploded view of the liquid crystal modulator of FIG.
3 is a schematic view of an air buoy.
4 is a cross-sectional view of a conventional liquid crystal modulator body.
5 is a schematic diagram of a substrate inspection apparatus using a conventional liquid crystal modulator.
6 is an equivalent circuit diagram illustrating an operation of a conventional liquid crystal modulator.
7 is a schematic view of a conventional TFT substrate inspection apparatus.
8 is an explanatory diagram for explaining the effect of light leaking from a conventional liquid crystal modulator dielectric reflector.
Figure 9 is a cross-sectional view of the liquid crystal modulator body of one embodiment according to the present invention.
10 is an explanatory view showing that light is blocked in the liquid crystal modulator of an embodiment according to the present invention;
11 is a schematic diagram of a substrate inspection apparatus using a liquid crystal modulator of the present invention.
12 is a wavelength distribution of a light source and leakage light.

In the following, preferred embodiments, advantages and features of the present invention will be described in detail with reference to the accompanying drawings.

9 is a cross-sectional view of the liquid crystal modulator body 600 of one embodiment according to the present invention. The liquid crystal modulator body 600 according to the present invention includes a liquid crystal 3 between a liquid crystal cell lower substrate 1 having a reflective film 2 provided thereon and a liquid crystal cell upper substrate 5 provided with a common electrode 4. The liquid crystal cell upper substrate 5 is bonded to the support substrate 7 using the transparent adhesive agent 6, and the polarizing plate 8 is provided on the support substrate 70. . The reflective film 2 is provided on the upper portion, the liquid crystal 3 is provided on the reflective film 2, and the light absorption layer 9 is provided on the lower substrate 1 below the liquid crystal cell.

In the process of forming the light absorbing layer 9 on the substrate below the liquid crystal cell, stress or deformation should not be applied to the substrate below the liquid crystal cell. Therefore, it has to have excellent elasticity and absorb light even though the thickness is thin. At the same time, the resistivity of the glass substrate must be large. Such materials are suitable for forming an R (Red) color filter, a G (Green) color filter, a B (Blue) color filter, or a BM (Black Matrix) used in a TFT LCD. It is preferable to use one substance or to mix two or more substances.

10 is an explanatory diagram showing a process of blocking light in the liquid crystal modulator of the present invention. The light absorbing layer 9 is formed below the liquid crystal cell lower substrate 1 so that light leaking from the reflective film 2 is absorbed to block light leaking to the TFT substrate 500.

11 is a schematic diagram of a substrate inspection apparatus using the liquid crystal modulator of the present invention. Substrate inspection apparatus according to the present invention has the same configuration as the substrate inspection apparatus shown in FIG. As shown in FIG. 11, the liquid crystal modulator according to the present invention can be seen that light is blocked in the light absorption layer so that leakage light is not transmitted to the TFT substrate 500. Therefore, even if the height of the liquid crystal modulator using the air flotation method is changed by vibration, since there is no light leaking to the TFT substrate 500, it can be measured accurately.

The image detector 44 is usually composed of a CCD module, which has the highest sensitivity in the 900 nm wavelength portion. Therefore, red light is advantageous when using visible light as a light source. 12 is a relative distribution curve of transmittance or brightness of light according to the wavelength of the light source and the leaked light. The horizontal axis represents wavelength and the unit is nm. The vertical axes of (A) and (E) are relative luminance distributions, and the vertical axes of (B), (C) and (D) represent absolute transmittance. FIG. 11A is a wavelength distribution curve of a red LED light source having a maximum luminance at 636 nm, and is a relative wavelength distribution in which the wavelength at which light is emitted is viewed as 100. FIG. FIG. 11B shows an example of a wavelength transmission curve when the number of dielectric thin films TiO 2 / SiO 2 is 11. The relative distribution of light leaking from the ductile thin film is shown in FIG. As the light absorbing layer 9, a green color filter commonly used in a TFT LCD is applied. The green color filter is coated by spin coating. The viscosity of the green color filter is less than about 20 cps, and the thickness is controlled by the number of revolutions in the spin coater. When the body of the liquid crystal modulator is 13 cm, a light absorption layer of about 1.0 to 1.5 m can be formed between 500 to 1000 rpm. Fig. 11 (D) is a transmission curve of the 1,0 탆 green color filter. The light transmittance near 550 nm is large, but the transmittance is less than 5% for the wavelength of red light. 11 (e) is a wavelength distribution of light leaking from the liquid crystal modulator when the light absorption layer of the present invention is applied. It can be seen that the light of the light source is mostly reflected or absorbed by the liquid crystal modulator, so that the light incident on the TFT substrate 500 is very weak in intensity.

Although the preferred embodiments of the present invention have been described and illustrated using specific terms, such terms are only for clarity of the present invention, and the embodiments and the described terms of the present invention are described in the technical scope and scope of the following claims. It is obvious that various changes and changes can be made without departing from the system. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should be regarded as being within the scope of the claims of the present invention.

1: bottom plate of liquid crystal cell 2: reflective film
3: liquid crystal 4: common electrode
5: liquid crystal cell upper plate 6: transparent adhesive
7: supporting substrate 8: polarizing plate
9: light absorption layer 10: liquid crystal cell
41: light source 44: image detector
100: liquid crystal modulator body 500: TFT substrate
600: liquid crystal modulator body

Claims (5)

In the liquid crystal modulator for inspecting whether the pixel electrode constituting the TFT substrate is defective by applying a voltage between the pixel electrode of the TFT substrate and the common electrode of the liquid crystal modulator.
With liquid crystal,
The lower substrate is provided under the liquid crystal,
The lower substrate is provided with a reflective film,
Liquid crystal modulator, characterized in that the light absorbing layer is provided on the lower substrate.
The method of claim 1,
The light absorption layer is a liquid crystal modulator, characterized in that formed of an organic film.
3. The method of claim 2,
The light absorbing layer is any one selected from a material forming an R (red) color filter, a G (green) color filter, a B (blue) color filter, and a BM (black matrix) used in a liquid crystal display. Liquid crystal modulator, characterized in that consisting of.
The method of claim 1,
The reflective film is a liquid crystal modulator, characterized in that provided on the upper substrate.
A TFT substrate inspection apparatus comprising any one of liquid crystal modulators selected from claim 1.
KR1020120090873A 2012-08-20 2012-08-20 Reflective lc modulator and apparatus using the same KR20140024186A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020120090873A KR20140024186A (en) 2012-08-20 2012-08-20 Reflective lc modulator and apparatus using the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020120090873A KR20140024186A (en) 2012-08-20 2012-08-20 Reflective lc modulator and apparatus using the same

Publications (1)

Publication Number Publication Date
KR20140024186A true KR20140024186A (en) 2014-02-28

Family

ID=50269276

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020120090873A KR20140024186A (en) 2012-08-20 2012-08-20 Reflective lc modulator and apparatus using the same

Country Status (1)

Country Link
KR (1) KR20140024186A (en)

Similar Documents

Publication Publication Date Title
US7808609B2 (en) Liquid crystal display device and repairing method thereof
US10690983B2 (en) Reflective display and preparation method thereof
CN102072437A (en) Illuminating device and display unit
JPH07318929A (en) Liquid crystal display device
US9195110B2 (en) Liquid crystal display device and process for producing the same
US20070115412A1 (en) Liquid crystal display device
US20150377708A1 (en) Optical system and array substrate detecting device
US8111397B2 (en) Plate inspection system and plate inspection method
TW201512736A (en) Liquid crystal modulator for detecting a defective substrate and inspection apparatus having the same
US8107078B2 (en) Detecting device and method for detecting unevenness of a glass substrate
US8064004B2 (en) Liquid crystal display apparatus and process for manufacturing the same
US8830461B2 (en) Inspection apparatus for display substrate
KR20140024186A (en) Reflective lc modulator and apparatus using the same
JP3925432B2 (en) Liquid crystal display
KR20100095048A (en) Liquid crystal modulator with metal mirror layer and thin film transistor substrate testing apparatus using the same
JP2010185920A (en) Device for inspecting alignment layer, method of inspecting alignment layer, and method for manufacturing electrooptical apparatus
KR20060092367A (en) Lc modulator with high resolution and high reliability and tft array tester using it
KR20100095046A (en) Liquid crystal modulator independency of base plate anisotropy and thin film transistor substrate testing apparatus using the same
KR100949485B1 (en) Detection equipment of cell gap in lcd and detection method with the same
TWI397742B (en) Polymer dispersed transflective liquid crystal display and a manufacturing method of the same
KR970000350B1 (en) Cell gap testing method of flat display panel
KR20110045882A (en) TFT array sensor using PDLC
US7964252B2 (en) Liquid crystal device, manufacturing method of liquid crystal device, and electronic apparatus including the liquid crystal device
CN115933241A (en) Display panel and display device
JP4332544B2 (en) Liquid crystal display

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E601 Decision to refuse application