P-131: Studies on Flickering in Low Frequency Driven Fringe-Field Switching (FFS) Liquid Crystal Display

Choi, Han Sol; Kim, Jin Hyun; Ham, Hyeong Gyun; Lim, Young Jin; Lee, Jae Myeong; Jin, Heung Yong; Manda, Ramesh; Kim, Min Su; Yang, Deng‐Ke; Lee, Seung Hee

doi:10.1002/sdtp.11034

Cited by 9 publications

(7 citation statements)

References 11 publications

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“…Consequently, intensive efforts to reduce the power consumption of this mode have been attempted by using the low‐ f driving when static images are being displayed. However, severe issues regarding image quality arise in the low‐ f driving, including image‐flickering owing to flexoelectric effect . The flexoelectric effect is a coupling between elastic deformation and electric polarization of liquid crystals in which the flexoelectric polarization is spontaneously induced by external electric field at a low f .…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystals for Superior Electro‐Optic Performance Display Device with Power‐Saving Mode

Kim

Jin

Lee

et al. 2018

Advanced Optical Materials

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for the additional power reduction in the liquid crystal driving scheme, for example, by reducing the driving frequency f. Displaying smooth and dynamic motion at high-frame rate has been an unquestionable direction to improve the performance of displays, but static images are also becoming significantly important as the application of displays diverges. Thus, as the f is in linear dependence on the power consumption of a module, low-f driving LCD is desired.In driving scheme of LCDs, some amount of electromagnetic radiant energy from the backlight is cut off by the combination of crossed polarizers and liquid crystalline medium while modulating polarization. In terms of energy loss in a liquid crystal layer, therefore, maximizing transmittance is an important factor to improve for better electro-optic performance. From this perspective, achieving both high optical transmittance and low-f driving would be a remarkable breakthrough in terms of power savings.There are two main streams of the initially homogeneous aligned light modulating mode in LCDs: fringe-field switching (FFS) and in-plane switching (IPS) modes. Both modes have a patterned electrode on the one side of two sandwiched substrates. In the IPS mode, patterned pixel (signal-swung) and common electrodes are interdigitated such that symmetrical lateral fields, which have the same translational periodicity with the electrode patterns, are formed between these two electrodes to rotating the liquid crystal director in plane; thus, reorientation occurs only in between the electrodes. In the FFS mode, on the other hand, a plain common electrode and a patterned pixel electrode are not on the same layer and separated by an insulation layer. With this structure, the electric fields form nonsymmetrical fringe shape and the field periodicity is half of the pitch of the electrode patterns. Thus, the rotation of the liquid crystal director takes place over the entire electrode area, which contributes more to the optical transmittance. [4,5] The FFS mode has been dominating the LCD market, especially in portable devices owing to the high aperture ratio, high transmittance, low operation voltage, wide-viewing angle, and touchscreen tolerance. [4,6] Consequently, intensive efforts to reduce the power consumption of this mode have been attempted by using the low-f driving when static images are being displayed. However, severe issues regarding image quality arise in the low-f driving, including image-flickering owing to flexoelectric effect. [7][8][9][10][11][12][13][14] The flexoelectric effect is a An advantageous factor for the technology of displays is low power consumption. For power-saving, low-frequency driving of liquid crystal displays (LCDs) is useful. However, an unacceptable performance drop, from image-flickering, occurs due to occurrence of the flexoelectric effect. Here, based on close agreement between experimental and simulated results, a new electro-optic mode with optimization of both electrode structures and physical properties of the liquid crystal...

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Section: Introductionmentioning

confidence: 99%

Liquid Crystals for Superior Electro‐Optic Performance Display Device with Power‐Saving Mode

Kim

Jin

Lee

et al. 2018

Advanced Optical Materials

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“…In order to use a low driving frequency to save energy, the image flickering problem must be solved. [9][10][11][12][13][14] In a previous paper, we showed that ionic effect and flexoelectric effect are the 2 factors responsible for the image flickering in FFS LCD. 15 Ions may cause 2 problems.…”

Section: Introductionmentioning

confidence: 95%

“…However, if the driving frequency is reduced, there is a problem that the brightness of the display may change with time, a phenomenon known as image flickering. In order to use a low driving frequency to save energy, the image flickering problem must be solved . In a previous paper, we showed that ionic effect and flexoelectric effect are the 2 factors responsible for the image flickering in FFS LCD .…”

Section: Introductionmentioning

confidence: 99%

Image flickering reduction by dimer and polymer stabilization in FFS liquid crystal display

et al. 2019

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Power consumption of a liquid crystal display, when it is used to display static images, can be reduced by using low frequency driving. However, when the driving frequency is decreased, the brightness of the display may change with time, a phenomenon known as image flickering. One factor responsible for the flickering issue is flexoelectric effect which is sensitive to the polarity of the applied voltage. We show that the flickering in fringe field switching (FFS) LCD can be significantly reduced by doping a liquid crystal dimer and using polymer stabilization. We demonstrated that 2 Hz driving frequency can be used to display static images.

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“…However, this low-frequency driving has recently been brought to huge attention owing to a serious image-quality drop, so-called image-flickering. Many reports show flexoelectric effect is one of main reasons of the image-flickering [1][2][3]. Flexoelectric effect is a coupling between geometric distortion of LC director field and the electric polarization [4].…”

Section: Introductionmentioning

confidence: 99%

P‐150: Flexoelectric Effect in Fine‐patterned In‐plane Switching (IPS) Mode

Cho

Ham

Lee

et al. 2017

Symp Digest of Tech Papers

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Low-frequency driving of liquid crystal displays can greatly reduce the power consumption, but the flexoelectric effect badly occurs as an optical fluctuation in space and time, so-called image-flickering. In a fringe-field switching (FFS) mode, both dynamic and static image flickering occur whereas, for an inplane switching (IPS) mode, dynamic image-flicker takes placewith no static flicker. However, the overall transmittance in IPS mode is relatively poor as compared to that of FFS mode. Here, we demonstrate that fine-patterned electrodes and negative dielectric anisotropy liquid crystal can greatly enhance the transmittance as high as that of FFS mode while keeping no static image flicker. The remained dynamic flicker can be also significantly reduced by increasing the magnitude of dielectric anisotropy of liquid crystals. We report the detailed behavior of voltage-and time-dependent transmittances.

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P-131: Studies on Flickering in Low Frequency Driven Fringe-Field Switching (FFS) Liquid Crystal Display

Cited by 9 publications

References 11 publications

Liquid Crystals for Superior Electro‐Optic Performance Display Device with Power‐Saving Mode

Liquid Crystals for Superior Electro‐Optic Performance Display Device with Power‐Saving Mode

Image flickering reduction by dimer and polymer stabilization in FFS liquid crystal display

P‐150: Flexoelectric Effect in Fine‐patterned In‐plane Switching (IPS) Mode

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