• Journal of Information Display
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• v.10 no.4
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• pp.175-179
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• 2009

As the physical properties of nematic liquid crystals vary with respect to temperature, the performances of liquid crystal displays (LCDs) are highly dependent on temperature. Additionally, it is well known that the electro-optic characteristics of LCDs, such as transmittance and threshold voltage, also rely on the LCD switching modes. The temperature dependence of the electro-optic characteristics of the wide-viewing-angle LCD modes, such as in-plane switching (IPS), multidomain vertical alignment by patterned electrode (PVA), and fringe-field switching (FFS), have been studied, and the results showed that the FFS mode has lower temperature dependence compared to the IPS and PVA modes. Since the liquid crystal (LC) reorients in different ways in each mode, this result is associated with the temperature dependence of LC's bend and twist elastic constants, and also with the position of the main reorientation, either in the middle or on the surface of the LC layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1234-1240
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• 2004

We studied on the electro-optic characteristics and dynamic stability according to an undesirably defined pretilt angle induced in high step coverage of pixel area for the Twisted Nematic (TN) / Fringe-Field Switching (FFS) mode. In case of the TN mode, LC directors twist reversely near the edges of thin-film-transistor and black matrix where the pretilt angle of the LC is not well defined. Therefore, the voltage-dependent dynamics of the LC in TN mode is unstable and shows the bad electro-optic characteristics. On the other hand, in case of the FFS mode, the LCs are twisted parallel to the bottom substrate by fringe electric field and the electro-optic characteristic is not influenced by the pretilt angle of the LC which is not well defined.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.524-528
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• 2002

Conventional hybrid aligned nematic liquid crystal display (HAN-LCD) has several advantages on low operating voltage, fast response time and rubbing free on one substrate. We have fabricated a new hybrid aligned nematic display driven by fringe field. The new device exhibits much wider viewing: angle than that of the conventional HAN mode, owing to almost in-plane rotation of the LC director. Furthermore, we have developed the device that reveals more efficient electro-optic characteristics by placing common electrode on top and bottom substrates. In this paper, the electro-optic characteristics of the novel cell are investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.171-171
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• 2010

Electro-optic characteristics of liquid crystal display using fringe field switching(FFS) device depend on many parameters such as cell retardation, electrode structure, rubbing angle, cell gap and dielectric anisotropy. In this paper, the light efficiency of FFS mode will be analyzed to confirm the electro-optic characteristics according to positive dielectric anisotropy such as transmittance, operating voltage and response time.

• Transactions on Electrical and Electronic Materials
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• v.4 no.1
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• pp.24-28
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• 2003

We have studied the influence of rubbing angles with respect to in-plane field direction on electro-optic characteristics of in-plane switching (IPS) liquid crystal display. The results show that the threshold voltage increases and the operational voltage decreases as the rubbing angle increases. Further, the total response time and also response times associated with grey-to-grey transitions become fast as the rubbing angle decreases.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.703-706
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• 2009

The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.

• Current Optics and Photonics
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• v.6 no.3
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• pp.323-331
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• 2022

Electro-optic modulator (EOM) takes a vital role in connecting the electric and optical fields. Here, we present a heterogeneously integrated EOM based on the lithium niobate-on-insulator (LNOI) platform. The key modulation waveguide structure is a field-enhanced slot waveguide formed by embedding silicon nanowires in a thin-film lithium niobate (LN), which is different from the previously reported LN ridge or etchless LN waveguides. Based on such slot structure, optical mode field area is reduced and enhanced electric field in the slot region can interact well with LN material with high Electro-optic (EO) coefficient. Therefore, the improvements in both aspects have positive effects on enhancing the modulation performance. From results, the corresponding EOM by adding such modulation waveguide structure achieves better performance, where the key half-wave-voltage-length product (V_𝜋L) and 3 dB EO bandwidth are 1.78 V·cm and 40 GHz under the electrode gap width of only 6 ㎛, respectively. Moreover, Lower V_𝜋L can also be achieved. With these characteristics, such field-enhanced waveguide structure could further promote the development of LNOI-based EOM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.190-190
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• 2009

Liquid crystals (LCs) which utilize the phase above blue phase temperature range are also known to format the optically nanostructured composites devices based on Kerr effect these days. We report electro-optical characteristics of the polymer-stabilized cholestric LCs by using UV curable monomers at the different temperatures such as blue phase temperature range, blue phase-isotropic transition temperature, and isotropic temperature range. The devices exhibit different electro-optic characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.677-681
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• 2013

Apart from the deposition of alignment layer, alignment process needs to be involved for alignment of liquid crystal (LC) molecules. To simplify manufacturing process, several method were used such as rubbing, ion-beam irradiation, UV irradiation, and lithography. But, eventually it needs another treatment for LC alignment. Here, we suggested Si induced polyimide (PI) alignment layer at low temperature. Using this method, we are able to eliminate the alignment process and found that the alignment and electro-optic performance are much better than that of the rubbed PI LC cells. Compared to the rubbed PI cells, the response time was decreased by 70% and C-V characteristics have hysteresis-free.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.437-440
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• 2002

Characteristics of holographic polymer dispersed liquid crystal(HPDLC) were studied according to various matrix materials to improve the electro-optic properties. Various types of polyurethane acrylates (PUAs) have been designed and synthesized. The morphologies of these gratings were measured by atomic force microscopy(AFM) and electro-optic properties were obtained with UV-visible spectroscopy. Real time measurements of grating fabrication have been obtained according to PUA structures. High reflection efficiency was obtained by modifying the molecular structure.