46‐3: Image Adaptive Refresh Rate technology for Ultra Low Power Consumption

You, Bong-Hyun; Nam, Hui; Lee, Hyojin

doi:10.1002/sdtp.13958

Cited by 20 publications

(17 citation statements)

References 11 publications

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“…It has the maximum value for the foveation point in the center of a panel, while it gets to be the minimum for the foveation point in the uppermost and lowermost positions of a panel. To support fixed frame and line times even at this variable effective number of lines, the variation on the vertical blank length, which is recently used to support the variable frame rate in gaming and low power display applications [24,25], maintains the total number of vertical lines including vertical active and blank areas at the constant number. For example, when the effect numbers of lines at the center and uppermost positions are 1456 and 928 for the vertical resolution of 4800 lines [14], the vertical blank lengths are set to be 14 and 542, respectively.…”

Section: Variable Clock Generationmentioning

confidence: 99%

Variable Clock and EM Signal Generation Scheme for Foveation-Based Driving OLED Head-Mounted Displays

2021

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An image processing pipeline and multi-output shift register of a foveation-based driving scheme are proposed for the realization of immersive head-mounted displays in 2019. In addition, this paper describes a variable clock generation circuit to manipulate output waveforms of shift registers in the foveated display. The EM circuit for OLED displays is also introduced to support the control signal to keep OLEDs of pixels from emitting light during the compensation. Especially, the EM circuit consists of only four TFTs and one capacitor and gives rise to pulses of variable widths corresponding to the resolution of a driven display area. A variable clock generation scheme is verified with 60 Hz 1440 × 2560 monitor, eye-tracker, PSoC board and FPGA board. An EM circuit is simulated by SPICE for 9600 lines and 120 Hz foveated displays.

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Section: Variable Clock Generationmentioning

confidence: 99%

Variable Clock and EM Signal Generation Scheme for Foveation-Based Driving OLED Head-Mounted Displays

2021

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“…For example, a dynamic operation technique in f d , adaptable to several types of display contents, has been proposed, where low f d , normal f d , and high f d operations are selected for standby or sleep, normal, and gaming or video modes, respectively. [10][11][12] However, reducing the operation frequency in LCDs is still challenging because the image flickering perceived by the naked human eyes becomes more severe with decreasing f d . [13][14][15][16][17][18][19][20] Thus, commercially achievable frequencies for LCD driving remain between 20 and 30 Hz.…”

Section: Introductionmentioning

confidence: 99%

“…[5,6] Recently, additional efforts have been devoted to improving power saving by adopting local dimming techniques in backlight units or by improving the operation scheme in logic parts. [7][8][9][10] In LCDs operated by alternating current (AC) signal voltages to avoid charge-induced image flickering, the power consumption by the operation circuits can be expressed as follows [10]…”

Section: Introductionmentioning

confidence: 99%

Flicker‐Free Fringe‐Field Switching Liquid Crystal Display Operable at Extremely Low Frequencies for Power Saving

Choi

Lee

et al. 2021

Adv Eng Mater

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A fringe‐field switching (FFS) liquid crystal (LC) mode used with a negative dielectric LC (n‐LC) that is operable at an extremely low‐frequency signal voltage regime, without image flickering, is proposed. By doping charge‐trapping fullerenes (doping concentration: 0.2 wt%) into a low‐resistivity polyimide LC alignment layer of the FFS n‐LC mode, the mobile ionic‐charge density within the n‐LC layer can be drastically decreased. Thus, excellent voltage‐holding ratios of 98.24% and 87.91% are achievable in the proposed FFS n‐LC mode at low operation frequencies of 0.5 Hz and 0.2 Hz, respectively, corresponding to the improvement rates of 155.69% and 1127.05% at each operation frequency, compared with the FFS n‐LC mode without the fullerene doping case. The evaluation results by the modulation flicker level reveal that the operation frequency of the proposed device scheme can be decreased significantly (≈0.2 Hz) without inducing the perceptible image‐flickering problems.

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“…However, with increasing pixel density, the mobile display panels suffer from power consumption issues. Because the power consumption level in driving circuits is proportional to the operation frequency [6,7], extensive efforts have been made to reduce the operation frequency level of FFS LC modes without degrading the image quality [8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Photocontrollable Resistivity Change in Nanoparticle-Doped Liquid Crystal Alignment Layer: Voltage Holding and Discharging Properties of Fringe-Field Switching Liquid Crystal Modes

Choi

Lee

et al. 2021

Crystals

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In liquid crystal (LC) displays, deriving an optimum resistance level of an LC alignment polyimide (PI) layer is important because of the trade-off between the voltage holding and surface-discharging properties. In particular, to apply a power-saving low-frequency operation scheme to fringe-field switching (FFS) LC modes with negative dielectric LC (n-LC), delicate material engineering is required to avoid surface-charge-dependent image flickering and sticking problems, which severely degrade with lowering operation frequency. Therefore, this paper proposes a photocontrolled variable-resistivity PI layer in order to systematically investigate the voltage holding and discharging properties of the FFS n-LC modes, according to the PI resistivity (ρ) levels. By doping fullerene into the high-ρ PI as the photoexcited charge-generating nanoparticles, the ρ levels of the PI were continuously controllable with a wide tunable range (0.95 × 1015 Ω∙cm to 5.36 × 1013 Ω∙cm) through Ar laser irradiation under the same LC and LC alignment conditions. The frequency-dependent voltage holding and discharge behaviors were analyzed with photocontrolled ρ variation. Thus, the proposed experimental scheme is a feasible approach in PI engineering for a power-saving low-frequency FFS n-LC mode without the image flickering and image sticking issues.

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46‐3: Image Adaptive Refresh Rate technology for Ultra Low Power Consumption

Cited by 20 publications

References 11 publications

Variable Clock and EM Signal Generation Scheme for Foveation-Based Driving OLED Head-Mounted Displays

Variable Clock and EM Signal Generation Scheme for Foveation-Based Driving OLED Head-Mounted Displays

Flicker‐Free Fringe‐Field Switching Liquid Crystal Display Operable at Extremely Low Frequencies for Power Saving

Photocontrollable Resistivity Change in Nanoparticle-Doped Liquid Crystal Alignment Layer: Voltage Holding and Discharging Properties of Fringe-Field Switching Liquid Crystal Modes

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