Anti-static additive for pressure-sensitive adhesives and its effect on light leakage in liquid crystal display

Yang, Min; Ko, Seung-Woo; Choi, Hyoung Jin

doi:10.1016/j.jiec.2010.01.030

Cited by 9 publications

(5 citation statements)

References 14 publications

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“…Typically, TFT-LCDs are aged at a standard high temperature (60°C) for durability evaluation. 4,5) Depending on the Young's modulus of pressure-sensitive adhesives (PSA) layer, two light leakage phenomena are observed in twisted nematic (TN) mode displays after durability test: (1) light leakage that is concentrated on the edges of LCD panel having hard PSA (PSA-h) and (2) funnel-shaped light leakage in LCD with soft PSA (PSA-s), as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

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Effects of thermomechanical properties of polarizer components on light leakage in thin-film transistor liquid-crystal displays

Lin

Chen

et al. 2015

Jpn. J. Appl. Phys.

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In this paper, we present static thermal analysis of stress and strain on a thin-film transistor liquid-crystal display (TFT-LCD) panel and their correlation with light leakage phenomena under high-temperature durability test. Three-dimensional (3D) finite element analysis (FEA) is coupled with experimental parameters of key components of the TFT-LCD panel for the analysis. A strong correlation exists between light leakage and retardation difference induced by stress on triacetyl cellulose (TAC) films. Moreover, shrinkage in stretched poly(vinyl alcohol) (PVA) film and modulus of the adhesive layer are key factors affecting stress distribution and displacement of polarizer stack. An increase in Young's modulus (E) of the adhesive layer effectively reduces polarizer shrinkage and light leakage at the center of the panel. A TAC film with lower Young's modulus and/or coefficient of thermal expansion (CTE) is also an effective solution.

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Section: Introductionmentioning

confidence: 99%

“…For instance, light leakage occurs when light from the LCD unit is not completely blocked and leads to loss of detail and contrast of display. [1][2][3] Such problems are generally identified and rectified during product durability test. Typically, TFT-LCDs are aged at a standard high temperature (60 °C) for durability evaluation.…”

Section: Introductionmentioning

confidence: 99%

Effects of thermomechanical properties of polarizer components on light leakage in thin-film transistor liquid-crystal displays

Lin

Chen

et al. 2015

Jpn. J. Appl. Phys.

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“…[8][9][10] An inherent problem of lamination-based structures such as an LCD polarizer is dimensional instability, which causes distortion of polarizer films upon the completion of fabrication processes or after thermal and=or humidity cycling testing, resulting in light-leakage phenomena. 7,[10][11][12][13][14][15][16][17][18] Such thermally induced distortion is mainly driven by mismatches in the coefficients of thermal expansion (CTE) and modulus (E) between different functional films, and between these films and the substrate. This stress may impose serious reliability issues and cause mechanical failure of films, such as warpage, 7) contact peel-off 13,16) and phase retardation or light-leakage phenomena.…”

Section: Introductionmentioning

confidence: 99%

“…This stress may impose serious reliability issues and cause mechanical failure of films, such as warpage, 7) contact peel-off 13,16) and phase retardation or light-leakage phenomena. 18) To date, a vast amount of studies [13][14][15][16][17][19][20][21] have focused on the relationship between modified materials such as adhesive layers, and their optical characteristics, with the aim of reducing light-leakage. For example, the evolution and relaxation ability of key components such as PSA films have been studied 13,16,17,20) by exploring the dependence of their elastic (GA) or loss (GAA) moduli as a function of either frequency or temperature.…”

Section: Introductionmentioning

confidence: 99%

Stress and stress relaxation behaviors of multi-layered polarizer structures under a reliability test condition characterized by use of a bending beam technique

Lin

Hsieh

et al. 2015

Jpn. J. Appl. Phys.

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The bending curvature, stresses, and stress relaxation of various multi-layered structures with different adhesive layers pertaining to the polarizer in a thin-film transistor liquid-crystal display (TFT-LCD) have been successfully characterized by using bending beam technique under reliability test. To be more specific, three different types of pressure-sensitive adhesive (hard-, middle-, and soft-type) and various poly(vinyl alcohol) (PVA) stretched directions are devised to examine to key stress contributors and correlations with light leakage. The shrinkage stress in stretched PVA film and stress relaxation ability of pressure-sensitive adhesives (PSA) layers are found to be the key factors determining the stress distribution and out-of-plane displacement of a polarizer stack. For hard-type PSA, its polarizer stack generates the highest bending curvature with maximum out-of-plane displacement but minimum in-plane displacement, leading to anisotropic stress distribution with high stress around the edges. On the other hand, polarizer stack with soft-type PSA yields the maximum in-plane displacement but the minimum out-of-plane displacement, resulting in isotropic stress distribution.

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“…One of the most serious problems of TFT‐LCDs is a phenomenon called “light leakage” . It stands for “unevenness” or irregular pattern in screen uniformity at low light conditions caused by temperature gradient and non‐uniform thermal stress distribution from the backlight.…”

Section: Introductionmentioning

confidence: 99%

Effect of chemical structure of acrylic pressure‐sensitive adhesives for polarizing film on light leakage phenomenon in TFT‐LCDs

Nam

Lee

et al. 2011

Polymers for Advanced Techs

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Increasing image quality in thin‐film transistor liquid crystal displays (TFT‐LCD) is a recognized challenge for electronic companies and specialists working in this area. One of the main problems in TFT‐LCDs is a phenomenon called “light leakage”, affecting black–white contrast and color brightness. It occurs because of a heat‐induced shrinkage and disorientation of the polarizing film of TFT‐LCD, which controls the intensity of the light from the backlight unit. Improvement of the light leakage can be achieved through using a pressure‐sensitive adhesive (PSA) used for assembling the polarizing film onto the TFT‐LCD panel. In this paper, eight acrylic/methacrylic monomers with high glass transition temperature (Tg) were employed for synthesis of the polymers for the adhesive. Effect of structure, Tg, and elasticity modulus of the synthesized polymers on the light leakage was investigated simultaneously for 2.5‐ and 7.0‐in. size samples. We demonstrated that the light leakage can be minimized through two different mechanisms—high stress relaxation of the polymers with low Tg and low modulus and high shrinkage resistance of the polymers with high Tg and high modulus. The results of this work indicate a possibility to develop a universal PSA for polarizing film in TFT‐LCDs of different sizes that will have a positive effect on manufacturing productivity and lowering prices of digital devices. Copyright © 2011 John Wiley & Sons, Ltd.

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Anti-static additive for pressure-sensitive adhesives and its effect on light leakage in liquid crystal display

Cited by 9 publications

References 14 publications

Effects of thermomechanical properties of polarizer components on light leakage in thin-film transistor liquid-crystal displays

Effects of thermomechanical properties of polarizer components on light leakage in thin-film transistor liquid-crystal displays

Stress and stress relaxation behaviors of multi-layered polarizer structures under a reliability test condition characterized by use of a bending beam technique

Effect of chemical structure of acrylic pressure‐sensitive adhesives for polarizing film on light leakage phenomenon in TFT‐LCDs

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