21.4: Development of Low-Retardation TAC FILM for Color-Shift Improvement in LCDs

Yasuda, Tomokazu; Ito, Tadashi; Nakayama, H.; Fukagawa, Nobutaka; Nishiura, Yousuke; Mihatashi, Keiji

doi:10.1889/1.2451409

Cited by 3 publications

(6 citation statements)

References 3 publications

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“…Instead, a low-retardation triacetyl cellulose (TAC) polarizer is used. Th e TAC fi lm has almost no birefringence, and improves the color shift that occurs under diagonal off -axis viewing in the IPS mode [34].…”

Section: Compensation Fi Lms For Va and Ips Modesmentioning

confidence: 95%

Technical evolution of liquid crystal displays

2009

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I n 1888, more than a century ago, the Austrian botanist FriedrichReinitzer discovered an intermediate state of matter between isotropic liquid and lattice-structured crystal [1][2][3]. Th is state, later termed liquid crystal (LC), remained merely a novelty for many years until suitable applications for the technology began to become apparent. From the late 1960s, following the realization that various display applications were possible, the popularity of liquid crystal as a research fi eld expanded rapidly, attracting the interest of many scientists who made fundamental contributions to the technologies that have led to the spectacular success of liquid crystal displays (LCDs) [3][4][5][6][7][8][9][10][11][12][13]. Th e development of the twisted nematic (TN) [4] and supertwisted nematic (STN) [5] cell confi gurations, along with the necessary manufacturing technologies [6][7][8][9], resulted in the birth of the LCD industry in the late 1970s and early 1980s. The subsequent development of thin-film transistor (TFT) technology provided a further boost to the industry in the late 1980s [14,15]. Th e boom was signifi cantly supported by the advancement of material technologies such as the highly reliable manufacturing of liquid crystal base materials, and the development of polymers for the alignment layer, color fi lter materials, and sheet-type polarizers formed from the poly(vinyl alcohol)-iodine complex.In the 1990s, LCDs occupied an important position in the display market primarily through notebook applications, although the cathode ray tube (CRT) continued to dominate the desktop monitor and television markets. Th e plasma display panel (PDP), which appeared in the commercial market in 1997, pioneered the large-area fl at panel display market. It was widely predicted at the time that PDPs would maintain the lead in the large-area display market and that LCDs in small-display information technology (IT) applications would soon be replaced by new technologies such as displays based on organic light-emitting diodes (OLEDs) [16,17]. Such predictions were based on the belief that the LCD technology suff ered from serious limitations in terms of both off -axis image quality and moving picture quality, and also that it had proved diffi cult to obtain reasonable manufacturing yields of large-area TFT panels. However, these predictions, as we now know, turned out to be incorrect. Th e application of LCDs has expanded rapidly in recent years from purely information technology (IT) applications to the television and mobile display markets, and now even to very-large-area digital information displays (DIDs).Interestingly, while LCDs penetrated the traditional territories of other display technologies including CRTs and PDPs, attracting inevitable and heavy competition from these technologies, the most critical competitors were in fact alternative LCD technologies. A range of LCD modes and technologies are now applied in the same areas of application and are compared directly with one another in the market. In applicat...

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Section: Compensation Fi Lms For Va and Ips Modesmentioning

confidence: 95%

Technical evolution of liquid crystal displays

2009

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“…For example, TAC film is used today as the polarizer substrate in automotive LCD displays. 4 In lab testing, an LC cell comprising two sheets of 40-micron TAC film enclosing LC material between the two substrates was biaxially thermoformed to a spherical radius of 100 mm and showed no change in performance (Fig. 7).…”

Section: Biaxial Curvature and The Potential Of Thermoformingmentioning

confidence: 99%

Solving Optical Performance and Comfort with One Solution

Cain¹

2023

Information Display

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“…12,13 Therefore, the regulation of the orientation birefringence of optical films has been investigated intensely. 3,4,9,10,14,15 It has been reported that the orientation birefringence (Δn) of a polymer is determined together by the segmental polarizability and the orientation degree (f) 15−17 Here, Δn 0 denotes the intrinsic birefringence of a polymer. n ̅ , ρ, M and N A are the average refractive index, the density, the relative molecular mass, and the Avogadro's constant, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Among various kinds of optical films, cellulose triacetate (CTA) film is widely used as the polarizer protective film and the optical compensation film because of its excellent transparency and heat resistance. − As a matter of course, as an optical film, the control of optical retardation of CTA film is essential to make it suitable for multiple application modes . For instance, CTA films are expected to have zero retardation when used as polarizer protective films, while they should have appropriate retardations for the application of optical compensation films. , Meanwhile, with the ever-increasing demands of thinner display panels, thinner CTA films are desired . However, as the intrinsic birefringence of cellulose esters themselves are very small, a thinner thickness would narrow the adjustable scope of optical retardation. , Therefore, the regulation of the orientation birefringence of optical films has been investigated intensely. ,,,,, …”

Section: Introductionmentioning

confidence: 99%

“…For instance, CTA films are expected to have zero retardation when used as polarizer protective films, while they should have appropriate retardations for the application of optical compensation films. , Meanwhile, with the ever-increasing demands of thinner display panels, thinner CTA films are desired . However, as the intrinsic birefringence of cellulose esters themselves are very small, a thinner thickness would narrow the adjustable scope of optical retardation. , Therefore, the regulation of the orientation birefringence of optical films has been investigated intensely. ,,,,, …”

Section: Introductionmentioning

confidence: 99%

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Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

Min

Han

et al. 2021

ACS Appl. Polym. Mater.

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By physical blending of the rigid-rod-like 4-cyano-4′-pentylbiphenyl (5CB) molecule with the cellulose triacetate (CTA), we have prepared the CTA/5CB blend films with different weight fractions of 5CB molecules (ω 5CB ) ranging from 0 to 15%. Even if only a small amount of 5CB molecules are added to the CTA matrix, the orientation birefringence of the stretched blend films becomes positive. With the increasing ω 5CB and the strain ε, the orientation birefringence gets significantly increased. The orientation degrees of CTA chains and 5CB molecules in the stretched blend films are acquired from the infrared dichroism measurements. Then, the nematic interaction strength between CTA chains and 5CB molecules is evaluated to be about 0.43. As ω 5CB ≥ 10%, aggregation of 5CB molecules occurs in the stretched blend films, while it does not affect the transmittance of films. We further show that the aggregation can improve the orientation birefringence of blend films significantly because of the strong nematic interaction between 5CB molecules. A physical picture at the molecular level is proposed to explain why the orientation birefringence of the stretched blend films gets increased. Finally, the orientation birefringence diagrams of the pure CTA films and the CTA/5CB blend films stretched at two different temperatures (170 and 200 °C) in the strain weight fraction of 5CB molecule (ε-ω 5CB ) space are established. We expect that these diagrams would provide a great potential guiding significance for the fabrication of CTA retardation films with specific values of orientation birefringence (Δn in ), such as quarter-wave film and half-wave films.

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21.4: Development of Low-Retardation TAC FILM for Color-Shift Improvement in LCDs

Cited by 3 publications

References 3 publications

Technical evolution of liquid crystal displays

Technical evolution of liquid crystal displays

Solving Optical Performance and Comfort with One Solution

Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

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