Elimination of image flicker in a fringe-field switching liquid crystal display by applying a bipolar voltage wave

Oh, Seung-Won; Park, Jun‐Hee; Lee, Jihoon; Yoon, Tae–Hoon

doi:10.1364/oe.23.024013

Cited by 24 publications

(16 citation statements)

References 14 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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“…To investigate the image flickering phenomenon, we performed numerical calculation using a commercial simulation program, TechWiz LCD (Sanayi System Co., Korea). We investigated how the electrode spacing affects the image flickering phenomenon, with which we can examine the flexoelectric effect in an LC cell [9][10][11][12]. The LC parameters used for numerical calculations are as follows: the birefringence ǻn = 0.1029, the dielectric anisotropy ǻİ = 7.3, and the elastic constants K 11 = 12.6 pN, K 22 = 5.9 pN, and K 33 = 13 pN.…”

Section: Calculated Resultsmentioning

confidence: 99%

“…Meanwhile, low-frequency driving of a display panel to reduce power consumption, especially in mobile devices, has drawn much attention recently [4í6]. When an FFS LCD panel, the use of which has become a mainstream approach for mobile displays, is driven by a low-frequency electric field, image flicker due to the flexoelectric effect in the LCs can be detected by the naked human eye [7][8][9][10][11].…”

Section: Objective and Backgroundmentioning

confidence: 99%

“…Because the image flicker induced by the flexoelectric effect is related to flexoelectric anisotropy, which is expressed as ǻe Ł e s í e b , where e s and e b are the splay and bend flexoelectric coefficients, the image flicker can be reduced by decreasing ǻe [9]. If we apply a bipolar voltage wave instead of a unipolar wave to an FFS LCD panel, the image flicker induced by the transmittance difference between neighboring frames can be eliminated completely because the LC director distribution remains the same when the sign of the applied electric field is reversed [10]. However, this method may require three voltage levels.…”

Section: Objective and Backgroundmentioning

confidence: 99%

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P-130: Investigation on Image Flicker in an FFS-LCD Panel: Dependence on Electrode Spacing

Park

Baek

et al. 2016

SID Symposium Digest of Technical Papers

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In case an LCD panel is driven by a low-frequency fringe field, image flickering phenomenon is detected by the naked human eye. We investigated the dependence on the electrode spacing of the image flickering phenomenon induced by the flexoelectric effect in an FFS LCD panel. We found that the image flicker in an FFS LCD panel under low-frequency driving can be eliminated in a simple manner by optimizing the electrode spacing. Author Keywords liquid crystal; fringe-field switching; flexoelectric effect; flicker P-130 / S.-W. Oh SID 2016 DIGEST • 1607 ISSN 0097-966X/16/4703-1607-$1.00

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“…Therefore, the transmittances of the LCD in the 2 frames are different, and the brightness changes from one frame to the next frame. Previously, some research groups suggested a few methods to reduce the flickering, for example, Oh et al 21 applied a bipolar voltage, instead of a unipolar voltage, to reduce the flexoelectric effect. They also suggested to use redesigned electrode spacing to control the flickering issue.…”

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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Elimination of image flicker in a fringe-field switching liquid crystal display by applying a bipolar voltage wave

Cited by 24 publications

References 14 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

P-130: Investigation on Image Flicker in an FFS-LCD Panel: Dependence on Electrode Spacing

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

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