P‐74: Thin Film Polarizers: Optical and Color Characteristics, Thermostability

Ignatov, Leonid; Lazarev, Pavel; Ovchinnikova, N. A.

doi:10.1889/1.1833083

Cited by 23 publications

(24 citation statements)

References 3 publications

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“…[2][3][4] A few reports are known on patterned polarizers based on the combination of lyotropic dyes and photoalignment layers. [5,6] In all cases the polarization performance is insufficient for almost all mainstream LCD applications (N < 25).…”

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confidence: 99%

High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

et al. 2006

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The most essential passive optical element in liquid-crystal displays (LCDs) is the polarizer. Polarizers are indispensable for the displaying of the information content and important front-of-screen performance parameters, such as brightness and contrast, are strongly influenced by the performance of the polarizer. Currently, the most widely used polarizers for LCD applications are derivatives of the H-sheet polarizer as invented by E. H. Land in 1938.[1] These dichroic polarizers are based on uniaxially stretched poly(vinyl alcohol) that is impregnated with iodine or doped with dichroic dyes. These sheet polarizers show excellent optical performances that can be expressed by the polarization efficiency (PE) in combination with the single-piece transmittance (T sp ; transmission of unpolarized light through a single polarizer) aswhere T p and T c are defined as the transmission of unpolarized light through two polarizers with their transmission axis parallel and perpendicular, respectively, and where A ʈ and A ⊥ are defined as the absorbance parallel and perpendicular to the average orientation of the long axis of the chromophores, respectively. The polarizer performance can also be expressed by a single parameter; the dichroic ratio (N)For high-end sheet polarizers such as those applied in LCD monitors or flat-panel televisions, the performance exceeds a polarization efficiency (PE) of 99.9 % at a single-piece transmission of 43.5 %, corresponding to N exceeding 50. Unfortunately, two triacetylcellulose (TAC) layers are needed in conventional polarizers to protect the stretched poly(vinyl alcohol) film on both sides against moisture and to obstruct relaxation effects under influence of heat and/or humidity by which the PE value would deteriorate. Further, an adhesive layer is needed in order to laminate the polarizer to the display. The necessary use of protective and adhesive layers adds unnecessary thickness to H-sheet polarizers. Finally, these polarizers show limited thermal stability and low resistivity against solvents. Numerous advantages are foreseen when the traditional sheet polarizers are replaced by ultrathin coatable polarizers situated on the inside of the cell (in-cell). Apart from a significant reduction in display thickness and weight, the positioning of the polarizers inside the cell eliminates all parallax-related issues and is beneficial to the robustness of the display. Furthermore, substrates that otherwise would be rejected because of their birefringence, e.g., thin, low-weight, and strong plastic foils or cheap, low-quality glass substrates, can be used when the polarizers are situated inside the LCD cell. The optimal position of the coatable polarizers inside the LCD cells can vary between display designs, however, it is beneficial to place the polarizers beneath the electrodes in order to prevent the need for increased driving voltages of the LCD panels.One possible approach to obtaining thin, coatable polarizers is based on the use of lyotropic liquid-crystalline dyes that form a crys...

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High‐Contrast Thin‐Film Polarizers by Photo‐Crosslinking of Smectic Guest–Host Systems

et al. 2006

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“…Качество поляризаторов, определяющих их практическую значимость, характеризуется такими параметрами, как поляризующая эффективность E p и среднее пропускание неполяризованного света Т. Эти два параметра зависят от толщины слоя поляризующего покрытия, а также параметра ориентационного порядка в нем S. Общей характеристикой молекулярного порядка S является дихроичное отношение K и степень поляризации получаемого поляризованного светового потока при прохождении или отражении через поляризатор неполяризованного света V [7][8][9][10][11][12][13][14].…”

Section: основная частьunclassified

Optically Anisotropic and Interferential Remedies: Properties, Technologies, Applications

Kozenkov¹,

Spakhov²,

Belyaev³

et al. 2016

Liq. Cryst. and their Appl.

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“…Dichroic dyes are doped liquid crystal polymers and the mixing is coated on a substrate. The film thickness is in the order of submircometers [3][4][5][6][7]. However, the dichroic ratio is not high enough, so such polarizers are not satisfactory for practical use.…”

Section: Introductionmentioning

confidence: 99%