• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.879-882
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• 2008

The discotic liquid crystal in compensating film used for the viewing angle improvement of the twist nematic liquid crystal display panel is analyzed. For the optical characterization of the compensating film, we measured the polarization state of the light passing through the film as the tilt angle and the azimuth angle of the film were varied, and then we compared the measured polarization state with the calculated one. Finally we suggested the best fit configuration of the discotic liquid crystal.

• 폴리머
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• 제30권5호
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• pp.373-379
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• 2006

플로로글루시놀과 중합가능한 피리딘 유도체의 수소결합을 이용해 디아세틸렌과 아크릴로일 그룹을 함유 한 새로운 중합가능한 원반형 액정들을 제조하였고 제조된 액정들의 광중합 거동을 조사하였다. 합성된 원반형 액정 복합체들은 메소겐의 방향족 고리의 개수에 따라 원반형 컬럼상과 장방형 컬럼상을 형성하였다. 원반형 액정복합체들의 광중합은 액정상에서 자외선을 조사하여 수행하였다. 자외선 조사 후 디아세틸렌과 아크릴로일 그룹이 선택적으로 중합되었으며, 짧은 공액구조의 디아세틸렌 올리고머를 가지는 가교 고분자들이 1,4-반응에 의해 형성됨을 적외선 분광법과 자외선-가시광선 분광분석을 통해 확인하였다. X-선 회절 실험 결과, 페닐피리딘을 함유한 원반형 액정 복합체의 컬럼상 질서는 광중합 후에도 유지되었고, 바이페닐 단위를 지닌 액정 복합체의 장방형 컬럼상 질서는 라멜라 질서로 변화됨을 확인하였다.

• 접착 및 계면
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• 제15권4호
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• pp.161-168
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• 2014

페놀과 피리딘 간의 단일 수소결합을 이용하여 새로운 형태의 자기 집합된 원반형 액정을 제조하고 그 액정 특성을 조사하였다. 원반형 구조 설계를 위해 phloroglucinol을 중심부 분자로, 체계적으로 알킬사슬 길이를 변화시킨 trans-4-alkoxy-4'-stilbazole을 주변 물질로 사용하였다. 적외선 분광 분석을 통해 중심부 분자와 주변 물질 사이의 분자간 수소결합이 성공적으로 형성됨을 확인하였고, 또한 수소결합의 안정성이 분자 정렬에 의해 크게 영향을 받음을 확인하였다. 자기 집합된 원반형 액정 복합체는 원반형 메소겐 주위의 알킬 사슬 길이에 따라 다른 액정상들을 나타내었다. 긴 알킬사슬을 함유하는 액정 복합체의 경우 육방형 컬럼상이 나타났으며, 상대적으로 짧은 사슬을 갖는 다른 액정 복합체에서는 네마틱 컬럼상이 형성되었다. 이는 자기 집합된 원반형 액정 복합체의 액정상 구조가 원반형 핵 단위 주변의 알킬사슬 길이에 의해 크게 영향을 받음을 의미하였다.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1101-1104
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• 2008

We have studied electro-optic characteristics to improve viewing angle of the in-plain switching (IPS) liquid crystal display using an compensation film. The IPS mode shows relatively large light leakage and color shift in diagonal directions in a dark state. To solve this problem, we have compensated the low contrast ratio in diagonal directions using one optimized discotic film and adjusting TAC films of polarizers. The compensated IPS mode shows wide viewing angle characteristics that region of CR 50:1 is over $60^{\circ}$ of polar angle in all directions. The optimized IPS cell exhibits much better performances than other methods do in terms of CR and color uniformity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.518-521
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• 2004

We have investigated about compensation film to reduce the light leakage at an oblique angle in-plane switching mode. It is well known that uncompensated in-plane switching (US) and fringe field switching (FFS) liquid crystal displays (LCDs) have much better viewing angle than other modes owing to the in-plane rotation of the LC director. However, to accomplish optimal viewing angle characteristics in these devices, they must be compensated by one or more films. So, in this paper, we have studied how to reduce the light leakage with viewing angle using discotic film in dark state.

• Bulletin of the Korean Chemical Society
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• 제9권2호
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• pp.98-101
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• 1988

A pure columnar cholesterogen based on the octasubstituted phthalocyanine $(PcH_2)$, S-(+)-2, 3, 9, 10, 16, 17, 23, 24-octakis[5-(dodecyloxy)-2-oxa-pentyl]-phthalocy anine(1a), is described. To evaluate a cholesteric character of 1a, the corresponding achiral $PcH_2$ 1b and the copper complex of chiral $PcH_2$ 1a (CuPc), S-(+)-2,3,9,10,16,17,23,24-octakis[4-(dodecyloxy)- 2-oxapentyl]-phthalocyanine(2a) were also prepared. The chiral 1a exhibited a typical cholesteric texture change in which the transition of platelet (blue phase) to fan-shape texture was observed (K－M－I), whereas the corresponding achiral 1b showed only a focal conic texture (K－ M－I). This is the first instance of a pure columnar cholesterogen observed with discotic liquid crystal systems.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.294-295
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• 2006

Field sequential liquid crystal display (FSLCD) has advantages such as a high transmittance due to no use of color filter and high color reproductivity because of LED backlight for a luminance source. However, to realize FSLCD response time of the LCD must be below 5ms. In this paper, we have chosen electrically controlled birefringence (ECB) mode for this application and studied film compensation to improve the operating voltage and viewing angle and to achieve a fast response time optimizing the condition of the discotic film and TAC film, operating voltage decreases to 5V, and viewing angle range is $160^{\circ}$ at horizontal and vertical direction, respectively and $120^{\circ}$ in diagonal direction. (contrast ratio > 10:1) and optimized cell exhibits a fast response time of 4ms in most grey levels.

• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.483-484
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• 2005

The field sequential liquid crystal display (FSLCD) does not need a color filter so that it is suitable for high resolution display. However, FSLCD has a drawback which requires a fast response time of sub-5 ms. We have studied the FSLCD with electrically controlled birefringence (ECB) mode. The ECB mode exhibits fast response time, high transmittance, low operating voltage and adequate viewing angle with a help of optical compensation films. In this paper, we present electro-optic characteristics of the ECB mode using a discotic film.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.610-613
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• 2009

New rod-disc liquid crystal (LC) molecule RD12 (12 is the number of carbon atoms between the rod and disc mesogenic liquid crystals) was synthesized via the chemical attachment of six cyanobiphenly calamitic mesogens linked to the triphenyl discotic mesogen with six alkyl chain linkage. Aligning characteristics associated with homogenous alignment is investigated at first and then field-dependent molecular reorientation under a vertical electric field is studied. Interestingly, they show abnormal slow molecular transition from initiate state (no electric field condition) to certain voltage. In this condition, we observe the molecular competition during reorientation. However, once a tilting direction of disk molecules are defined, the frustration is not observed anymore. The origin of this phenomenon is explained with a suggested model for the first time.