Materials and Assembling Process of LCDs

Morozumi, Shinji

doi:10.1142/9789814368278_0005

Cited by 15 publications

(13 citation statements)

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“…Consider an empty LC cell with two glass substrates, two layers of ITO of thickness 150 nm [22] and two layers of polyimide of thickness 50 nm [22]. To calculate the reflectivity of such an LC cell, the characteristic matrix method [21] can be applied.…”

Section: Resultsmentioning

confidence: 99%

Inline Quality Control of Liquid Crystal Cells

Valyukh

Sorokin

Chigrinov

2015

J. Display Technol.

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Abstract-Inline quality control of liquid crystal (LC) cells is usually associated with a real time non-contact characterization of moved LC cells. Such a characterization enables inspection of the products quality and helps to find in time defects. In the paper, we analyze an approach for fast evaluation of LC cell gap uniformity. The approach is based on detecting interference patterns formed by the quasi-monochromatic light reflected from a tested LC cell. To speed up the data treatment, a simple analytic expression describing the intensity of light interacting with the multilayered structure of an LC cell is derived. The results of the simplified model are compared with rigorous simulations. Two experimental setups are discussed. A CCD camera is used for detecting the interference patterns.

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Section: Resultsmentioning

confidence: 99%

Inline Quality Control of Liquid Crystal Cells

Valyukh

Sorokin

Chigrinov

2015

J. Display Technol.

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“…This observation can provide quantitative information on the anisotropic tilted orientation of these cyanobiphenyls at the aligned layer surfaces. The SHG data fitting obtained from the rubbed 6FDA-11CBBP surfaces allowed us to determine six independent non-vanishing elements of v (2) CBBP . The corresponding values are: v (2) zzz = 1:0.2:0.032:±0.27:±0.16:±0.089 (errors of ± 5 %, ± 20 %, ± 5 %, ± 8 %, and ± 10 %).…”

Section: Anisotropic Orientation Of the Cyanobiphenyl Groups At The Rmentioning

confidence: 99%

“…The SHG experiments previously described cannot distinguish between these two possible orientations, and a SHG phase measurement was needed. This experiment utilizes a comparison of the SHG phase of v (2) xxx of 6FDA-11CBBP with that of 5CB monolayer adsorbed on a commercial P6 polyimide alignment surface that does not contain side chains. As shown in the interference patterns of these two cases in Figure 5, the measured SHG phases of v (2) xxx from 6FDA-11CBBP ( Fig.…”

Section: Anisotropic Orientation Of the Cyanobiphenyl Groups At The Rmentioning

confidence: 99%

“…A variety of high-resolution thin film transistor liquid-crystal displays (TFT-LCDs) have been developed and commercialized in laptop computers, desktop monitors, and other mobile telecommunication devices. [1,2] However, the problems of narrow viewing angles, gray-scale inversion, and color distortion in the addressed state (the electric field-on state) have prevented their use in large LCD television screens. The compensation of the angular dependence of the birefringence in the addressed state of conventional TFT-LCDs requires an optimized optical retardation film that possesses both a negative birefringence and an oblique optical axis.…”

Section: Introductionmentioning

confidence: 99%

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Assembly of Photopolymerizable Discotic Molecules on an Aligned Polyimide Layer Surface to Form a Negative Retardation Film with an Oblique Optical Axis

Hong

Tang

et al. 2003

Adv Funct Materials

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Ultraviolet (UV) polymerizable discotic liquid‐crystalline (DLC) molecules (2,3,6,7,10,11‐hexakis(4′‐acryloy‐m‐alkyloxybenzoyoxy)triphenylene [HAHBT‐m, where m was the number of methylene units, and here m = 6 (HAHBT‐6)]) were assembled to form a negative retardation film with an oblique optical axis on a specifically designed rubbing‐aligned polyimide layer surface [6FDA‐11CBBP (where 11 is the number of methylene units in the side chains)]. The side chains of this polyimide were terminated by cyanobiphenyl groups. Surface‐enhanced Raman scattering (SERS) and optical second harmonic generation results showed that rubbing caused a surface structural re‐arrangement in the alignment layer resulting in a negative pre‐tilt angle (θs) of –8.5° (which was in the direction opposite to the rubbing direction). The molecular topology at the rubbed surface was governed by a stable fold‐like bent structure of the cyanobiphenyl side chains, in which the CN groups preferentially pointed down towards the surface. When the DLC molecules were deposited onto the alignment surface and polymerized via UV irradiation to generate a new optical film, an oblique optical axis with an average tilt angle of –18.6° with respect to the film normal was detected using ellipsometric measurements. This tilted optical axis was developed by the DLC molecules being wedged on top of the cyanobiphenyl groups when in the bent conformation. Furthermore, the tilt angle difference between the θs at the alignment surface and at the air interface of the DLC molecules was attributed to a splay deformation of the DLC molecules along the film surface normal. Optical modeling has also confirmed our experimental observations.

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“…because color elements applied to the usual color filter layer easily fade at high temperatures. 10 At present, since there are no color elements with high temperature durability and good adaptability to the liquid crystal display (LCD) cell, the temperature of heat treatment during the cell assembling should be kept under 250°C. Therefore, it is necessary to obtain the information on the structural change of the CBDA-BAPP at the temperature lower than 250°C.…”

mentioning

confidence: 99%

Effect of Imidization Temperature and Spinning Condition on Structure of Polyimide Film Derived from Cyclobutanedianhydride and 2,2-Bis(4-aminophenoxyphenyl)propane

Kim

Park

1997

Polym J

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ABSTRACT:The polyimide derived from cyclobutanedianhydride and 2,2-bis(4-aminophenoxyphenyl)propane (CBDA-BAPP) is one of the typical materials for liquid crystal alignment layer in liquid crystal display (LCD). The effects ofimidization temperature and spinning condition on degree of imidization, and in-plane orientation of the CBDA-BAPP film were studied. The imidization temperature at 200"C was found to be insufficient for complete imidizaiion of the amic acid group. The in-plane orientations of the CBDA-BAPP films imidizcd at 200cc and 250''C were similar to each other, although they were higher than that of the film imidized at l 50°C. With increasing the spinning rate and decreasing the solution concentration in the spin-casting procedure, the degree of imidization was decreased, together with the increasing in-plane orientation which would be mainly governed by chain immobilization rate over the chain stiffness.KEY WORDS Cyclobutanedianhydride-2,2-Bis(4-aminophenoxyphenyl)propane / Thermal Imidization / Degree of Imidization / In-Plane Orientation / Residual Solvent / The polyimide derived from cyclobantanedianhydride and 2,2-bis(4-aminophenoxyphenyl)propane (CBDA-BAPP) has been used for liquid crystal alignment layer (SE-150, Nissan Chemical Industries Co., Ltd.) 1 -3 and can be also used as photoresist due to the decomposition of the cyclobutane ring by UV irradiation. 4 Among these applications, it is usually interfaced with substrate and prepared from the spin-coating of the polyamic acid on substrate followed by prebaking, and thermal imidization leading the structure evolution.The properties of polyimides are controlled by the change in the structure of film or coating, which is dependent on the conditions used to cure the polyamic acid. 5 -9 The imidization temperature, which is highly important in processing related to the conversion of amic acid group into imide and the molecular orientation of the imide chain, is often restricted in the production of liquid crystal alignment layer. because color elements applied to the usual color filter layer easily fade at high temperatures. 10 At present, since there are no color elements with high temperature durability and good adaptability to the liquid crystal display (LCD) cell, the temperature of heat treatment during the cell assembling should be kept under 250°C. Therefore, it is necessary to obtain the information on the structural change of the CBDA-BAPP at the temperature lower than 250°C.In addition, it should be noted that the spinning condition can vary with the degree of imidization and the molecular orientation, in turn, the properties of the film. 11 -l 3 The thickness of the film and the residual solvent content of the cast polyamic acid depend on spinning condition, and these differences could lead to the different structure of the resulting polyimide film.The present study reports the effect of imidization temperature and spinning conditions on degree of imidization, chain orientation of the CBDA-BAPP film 1 To whom correspondence shoul...

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Materials and Assembling Process of LCDs

Cited by 15 publications

References 0 publications

Inline Quality Control of Liquid Crystal Cells

Inline Quality Control of Liquid Crystal Cells

Assembly of Photopolymerizable Discotic Molecules on an Aligned Polyimide Layer Surface to Form a Negative Retardation Film with an Oblique Optical Axis

Effect of Imidization Temperature and Spinning Condition on Structure of Polyimide Film Derived from Cyclobutanedianhydride and 2,2-Bis(4-aminophenoxyphenyl)propane

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