• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.161-167
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• 2011

In this paper, we propose an in-plane switching (IPS) mode for liquid crystal displays (LCDs) that, in principle, is free of retardation of the LC cell. Basically, the optical configuration of the LC cell consists of an A-plate and an LC layer for switching between the dark and bright states. We could achieve a fast response time compared with the conventional in-plane LC cell because the free retardation condition of the proposed LC cell enables us to reduce the cell gap even by quarter-wave retardation without any change of the optimized LC material in the transmissive mode. Experiments for verification of the proposed in-plane switching LC cells have shown a significant reduction of the rising time and falling time simultaneously due to the small cell gap. Furthermore, we also proposed an optical configuration for wide viewing property of the retardation free IPS LCD by applying the optical films. We proved the wide-view property of the retardation free IPS LCD by comparing its optical luminance with the calculated optical property of the conventional IPS LCD.

• 반도체디스플레이기술학회지
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• 제20권4호
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• pp.55-61
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• 2021

In this paper, we proposed and implemented defect detection methods of polarized film with half-wave phase retardation plates. We investigated the principles of phase retardation compensation and optical principle of half-wave phase retardation plates. We analyzed of samples of polarized film with half-wave phase retardation plates. The optical defect detection methods are proposed and the performance is validated with experiments.

• Design & Manufacturing
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• 제6권1호
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• pp.90-94
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• 2012

Recently, injection molding process became more popular than ever to produce large quantities of high precision products. Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical products. Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. Generally, quantitative value of birefringence can be measured with polarizing microscope using the compensator. However, it is difficult to measure low order retardation with microscope, so developing a measurement system for low order optical path difference is in need. In the present paper, a system using Photo Elastic Modulator (PEM) is demonstrated to measure low phase retardation in injection-molded products.

• 한국광학회지
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• 제11권1호
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• pp.19-24
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• 2000

액정 표시소자에 쓰이는 위상판의 시야각특성을 확장된 존즈행렬과, 이것의 뽀앙카레공(Poincare sphere)에서의 기하학적 회전변환으로 해석하였다. 위상판의 회전변환 특성은 시야각이 바뀌면 회전축은 적도선 위에 있고, 회전각이 시야각에 따라 크게 변한다. 광축의 방향이 다른 두 장의 위상판을 겹쳐쓰면 이런 특성을 보정할 수 있고, 이 방법을 써서 BTN 셀의 시야각 특성을 개선할 수 있었음을 보였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.433-436
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• 2002

Retardation liquid crystal films with a profiled titled optic axis (splay films) of both nematic and discotic types are used as compensation films for twisted nematic displays (TN-LCD). A new method is developed to characterize retardation vs. inclination (retardation profile) of splay films by three parameters: "full retardation" $d^{\ast}{\triangle}n$, "inplane retardation" $R_0$ and "retardation difference" $R_d$ . Splay films with the same retardation profile but with different tilt profile (retardation invariants) are discovered. Splay films with different structure parameters but belong to the same retardation invariant have the same compensation opportunities for TN-LCD.

• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.457-461
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• 2012

A real-time method to measure full field retardation near quarter wavelength is proposed. The circularly polarized beam passes through a sample with a large aperture. The measuring beam then goes through a quarter-wave plate and is then split by a Wollaston prism. An image with two sub-images is then detected by a high-speed image sensor. The full field retardation near quarter wavelength can be obtained in real time by processing the image. The measured retardation is independent of the fast axis angle of the sample and the fluctuation of the initial intensity. In experiments, a wedge waveplate is measured with different fast axis angle and initial intensity, and the full field retardations are acquired. The maximum and standard deviation of the full field retardation is $1.5^{\circ}$ and $0.4^{\circ}$. The validity of the method is verified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1603-1605
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• 1996

We have studied the static electricity and optical retardation generated by rubbing the surfaces of polyimide (PI) and polyamide (PA) films. The static electricity increases with the rubbing strength (RS) and varies with the different PI films. We also investigated how the differences in the rubbing fabric affects the magnitude of the induced static electricity; the order of this effect is nylon > rayon > cotton. The induced static electricity is not only directly related to the values of the specific resistivity of the rubbed PI films, but also the RS and the ability of the rubbing fabric to generate and add a static electric charge. The order of the optical retardation produced by the rubbing fabraic on rubbed PI films is nylon > rayon > cotton, coinciding with the order of the generated static electricity.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.365-365
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• 2006

The wavelength dispersion of birefringence (or retardation) is very important property for optical use of polymer films. Birefringence free film and retardation film have been widely used for applications such as liquid crystal display (LCD). In this study, miscible polymer blends which consist of polymers of positive and negative birefringence were found. By operating composition and orientation of molecules in the transparent blend films, the behavior of wavelength dispersion of birefringence (retardation) was controlled. The applicability to wideband birefringence free film and quarter wave (retardation) film was discussed.

• 한국광학회지
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• 제11권3호
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• pp.158-162
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• 2000

본 논문에서는 기존의 회전펴광자법에서 낮은 셀갭을 측정할 경우 발생하는 문제점을 보완하기 위하여 수치 해석적인 방법과 위상지연판을 이용한 방법을 도입하였으며 실험적 결과로부터 낮은 셀갭이 측정됨을 보였다.

• 한국광학회지
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• 제24권2호
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• pp.77-85
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• 2013

시료를 회전시키는 기존의 시료회전형 타원계에서 시료를 고정시키고 편광자모듈을 회전시키는 모듈회전형 타원계로 구조를 변경하고 광원교체와 회전모듈 동기화, 배경 미세이방성 보정 등을 통해서 위상지연값 측정정밀도를 $3{\sigma}$ <0.005 nm 까지 향상시켰다. 개선된 모듈회전형 타원계를 사용하고 RVD(Retardation Vector Difference) 방법을 도입함으로써 1.0 nm 정도의 잔류이방성을 가지는 유리기층의 효과를 배제한 러빙된 Polyimide 배향막의 순수 배향효과만에 의한 초미세 광학이방성을 정밀하게 측정하는 방법을 제시하였다. 순수 러빙으로 인한 배향막의 위상지연값은 0.05 nm 에서 0.15 nm 정도의 크기를 가짐을 확인하였다.