• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.17-19
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• 2009

The voltage and frequency dependence of voltage holding ratio (VHR) in a homogeneously-aligned liquid-crystal (LC) cell is studied in this paper. The discharge curves with different scan frequencies are obtained and the saturation phenomenon of VHR is observed under specific amplitudes of driving voltage. Our results suggest a reasonable concept to improve the VHR in LC displays without increasing the frame rate.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1469-1471
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• 1994

This paper describes the structure and electrical characteristics of a shorted anode p-i-n switch. The device showed a significant improvement in the threshold voltage-to-holding voltage ratio, which is due to the suppression of the hole injection from the anode and to the gold gettering at the anode side. The shorted anode devices with a $100{\mu}m$ channel length have a threshold voltage of 300 volts and a holding voltage of 5.5 volts.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.174-177
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• 2001

The voltage holding ratio (VHR) and Residual DC property in the in-plane switching (IPS) cell was studied Several IPS cells which have different concentrations of cynao liquid crystals (LCs) and different resistivities of fluorine LCs were fabricated VHR and residual DC voltage in the IPS cells using the capacitance-voltage (C-V) hysteresis method was measured. We found that the VHR of the IPS cell was decreasing with increasing concentration of cyano LC. The residual DC voltage of the IPS cell was decreasing with increasing concentration of cyano LCs. We suggest that the high polarity of cyano LC helps reducing the residual DC voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.169-172
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• 2002

The voltage holding ratio(VHR) and the residual DC property in the in-plane switching (IPS) cells on a polyimide surface was studied. Several IPS cells which have different concentrations of cyano liquid crystals (LCs) were fabricated. We found that the VHR of the IPS cell was decreased with increasing concentration of cyano LCs. Also, the VHR of the IPS cell was increased with increasing specific resistivity of fluorine LCs. The residual DC voltage of the IPS cell by capacitance-voltage (C-V) hysteresis method was decreased with increasing concentration of cyano LCs. The residual DC property of the IPS cell on the rubbed PI surface can be improved by high polarity of cyano LC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.110-114
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• 2014

In this study, we report the doping effect of graphene quantum dots (QDs) in nematic liquid crystal (NLC) system on rubbed polyimide (PI) surface. The good LC alignment and high thermal stability in QD-LC cell system on rubbed PI surfaces can be measured. Also, the low threshold voltage of QD-TN cell was observed about 2.77 V. The fast response time of 13.2 ms for QD-TN cell can be achieved. Finally, the good voltage holding ratio of QD-TN cell on rubbed PI surface was measured.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.7
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• pp.69-76
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• 1995

A new device structure has been developed for p-i-n switches. In this structure, the phosphorus-diffused n$^{+}$ layter adjacent to the boron-doped anode is used to short the p$^{+}$ anode-channel(i-region). This change in the anode electrode structure results in a significant improvement in the threshold voltage-to-holding voltage($V_{Th}/V_{h}$) ratio, which is due to the suppression of the hold injection from the anode by the n$^{+}$ layer. The shorted anode p-i-n devices of a 100 .mu.m channel length show an extremely high threshold voltage in the 250~300 V range and a low holding voltage in the 5~9 V range. These features of the device are expected to acdelerate their practical application to power switching circuits.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.537-540
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• 1999

Effect of alignment layers on pretilt angle generation and electrical characteristics in nematic liquid crystal(NLC) by using photo-alignment techniques on polyimide (PI) surface with side chain were studied. The generated pretilt angle of the NLC on rubbed PI surface with 1-layer is almost the same as that of the 2-layers. However, the generated pretilt angle of the NLC on photo-induced PI surface with 2-layers is larger than that of the 1-layer. Therefore, the pretilt angle of the NLC on photo-induced PI surface is attributed to surface roughness due to photo-depolymerization of the polymer with UV light irradiation on PI surface. Next we observed the same characteristics of voltage-transmittance (V-T) and response time for 1- and 2-layers on PI surface. We also observed the same voltage holding ratio (VHR) characteristics for 1- and 2-layers on photo-aligned PI surface. Consequently, we suggest that the VHR of photo-aligned TN-LCD is higher than that of the rubbing-aligned TN-LCD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.113-116
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• 1998

In this paper, we studied the electro-optical(EO) performance of photo-aligned twisted nematic(TN)-liquid crystal display(LCD) with oblique non-polarized ultraviolet(UV) light irradiation on polyimide(Pl) surface. We observed that the voltage-transmittance and response time characteristics of photo-aligned TN-LCD is almost same compared to conventional TN-LCD. Also, we observed that the voltage-holding-ratio(VHR) of photo-aligned TN-LCD is almost same compared to conventional TN-LCD.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1385-1387
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• 1998

In this paper, we studied the electro-optical(EO) performance of photo-aligned twisted nematic(TN)-liquid crystal display(LCD) with oblique non-polarized ultraviolet (UV) light irradiation on polyimide (PI) surface. The monodomain alignment of photo-aligned TN-LCD is obtained with an angle of incidence of $85^{\circ}$ on PI surface. Also, we observed that the voltage transmittance and response time characteristics of photo-aligned TN-LCD is almost same compared to rubbing treated TN-LCD. Finally, we measured that the voltage-holding-ratio(VHR) of photo-aligned TN-LCD is almost same compared to rubbing treated TN-LCD.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.472-475
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• 2005

The electrical performances of liquid crystal (LC) cells with chloromethylated polyimide (CMPI) alignment layers were investigated. The CMPI layer was previously reported as a multifunctional layer that does role of LC alignment and planarization layer as well as photo-alignment material with high photosensitivity and excellent thermal stability. The capacitance-voltage (C-V) characteristics of LC cells with CMPI alignment layers were measured. Mechanical rubbing of the CMPI layer did not generate much difference in residual DC when compared to commercial PI. However, the LC cell with photo-oxidation CMPI layer shows a high residual DC value and a corresponding low voltage holding ratio (VHR) due to the photo-induced ionic charges on the alignment layer.