Performance of a Novel Optical Compensation Film Based on Negative     Birefringence of Discotic Compound for Wide-Viewing-Angle     Twisted-Nematic Liquid-Crystal Displays

Mori, Hiroyuki; Itoh, Y.; Nishiura, Yosuke; Nakamura, T.; Shinagawa, Yukio

doi:10.1143/jjap.36.143

Cited by 215 publications

(107 citation statements)

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“…27,28 Although a viewing angle improvement can be achieved by both rodlike and discotic LC networks, most commercial devices make use of the latter. 29,30 For STN displays, a film containing an LC network with the same but opposite supertwist is added to the optical stack. These films solve the color problems that STN displays intrinsically have.…”

Section: ■ Polymer Propertiesmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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Monolithically ordered liquid crystal polymer networks are formed by the photoinitiated polymerization of multifunctional liquid crystal monomers. This paper describes the relevant principles and methods, the basic structure− property relationships in terms of mesogenic properties of the monomers, and the mechanical and optical properties of the polymers. Strategies are discussed to control the molecular orientation by various means and in all three dimensions. The versatility of the process is demonstrated by two examples of films with a patterned molecular order. It is shown that patterned retarders can be made by a two-step polymerization process which is successfully employed in a transflective display principle. A transflective display is a liquid crystal display that operates in both a reflective mode using ambient light and a transmissive mode with light coming from a backlight system. Furthermore, a method is discussed to create a patterned film in a single polymerization process. This film has alternating planar chiral nematic areas next to perpendicularly oriented (so-called homeotropic) areas. When applied as a coating to a substrate, the film changes its surface texture. During exposure to UV light, it switches from a flat to a corrugated state.

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Section: ■ Polymer Propertiesmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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“…The molecular polarizability tensor of orientation birefringence in each segment is assumed to show uniaxial anisotropy because each segment in an amorphous polymer can rotate freely around the orientation axis and can allow the complex chemical structures of each segment to be averaged. Assuming that the molecular polarizability tensor can be described using equation (3), which is based on this segment model, then the polarizability tensor is described in the Cartesian coordinate system using equations (4) and (5). The relationship between the molecular polarizability of the single segment unit and that coordinate system is shown in Figure 6.…”

Section: Theoretical Study Of Bdcmentioning

confidence: 99%

“…1,2 The two most important functions of retardation films are to control the three-dimensional refractive indices and the wavelength dispersion of the birefringence. 3 Retardation films can be divided broadly into two categories: a polymer-stretching type 4 and a liquid crystal type 5 that uses its spontaneous orientation. When referred to in this paper, the retardation film can be assumed to be of the former type unless otherwise specified.…”

Section: Introductionmentioning

confidence: 99%

“…5,6 The refractive-index anisotropy control of retardation films is one of the most effective solutions for improving performance and reducing costs and has become the standard means of improving the viewing angle. 5 A second important development, which can address issues such as color dispersion and the contrast of FPDs, is the control of the birefringence dispersion on retardation films. Figure 2 shows a typical example of the effect of birefringence dispersion control (BDC) of the retardation film in a reflective LCD with a single polarizer.…”

Section: Introductionmentioning

confidence: 99%

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Copolycarbonate optical films developed using birefringence dispersion control

Uchiyama

Ono

Ikeda

et al. 2012

Polym J

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A retardation film is a type of optical film that is widely used as a polarization transformation material to improve the image quality of flat panel displays (FPDs). One of the issues associated with retardation films has been the wide-banding of birefringence dispersion. A conventional optical design method that uses double-layered retardation films has been adopted to achieve wide-band properties. However, this conventional method has problems that have led to the demand for a single retardation film with wide-band birefringence properties. This situation motivated us to develop birefringence dispersion control (BDC) and to develop new polymers based on our novel molecular design. Wide-band characteristics are obtained using copolymers or miscible blends of polymers comprised of positive and negative anisotropic monomer units at specific volume fractions. The wide-band properties appear in a narrow range near the birefringence zero point, which is determined by the monomer volume fractions. The relationship between the orientation functions and birefringence dispersion is also clarified using theoretical studies, polarized IR and birefringence measurements. We have successfully industrialized a wide-band retardation film consisting of a newly developed copolycarbonate (co-PC) with a fluorene ring using the novel BDC theory. This film exhibits superior optical properties in FPDs.

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“…Several types of these so-called wide-viewingangle foils have been demonstrated. For instance discotic polymeric network films with a tilted optical axis, applied between the LCD cell and the polarizer, gave an enormous improvement on the angular dependence of contrast and grey scale inversion [30,31]. Comparable improvements of the optical performance are obtained from crossed tilted calamitic liquid crystalline networks [32].…”

Section: Functional Polymer For a Brighter Displaymentioning

confidence: 99%

Review: Progress in liquid crystal displays by new developments in functional polymers

2001

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Functional polymers have become essential in the functioning and performance of many products for information and communication technologies. Special polymers have been constructed with an accurate control over their morphology to a size down to the wavelength of light. These polymers improve liquid crystal displays on eye-catching properties like brightness and viewing angle. The improved energy efficiency is crucial for the mobile communication equipment in today's information society.

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Performance of a Novel Optical Compensation Film Based on Negative Birefringence of Discotic Compound for Wide-Viewing-Angle Twisted-Nematic Liquid-Crystal Displays

Cited by 215 publications

References 0 publications

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Copolycarbonate optical films developed using birefringence dispersion control

Review: Progress in liquid crystal displays by new developments in functional polymers

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