Session Index

S7. Display and Solid State Lighting

Display and Solid State Lighting I
Friday, Dec. 2, 2022  13:00-15:00
Presider: Chih-Lung Lin、Ko-Ting Cheng
Room: 2F A203
13:00 - 13:30
Manuscript ID.  0904
Paper No.  2022-FRI-S0701-I001
Invited Speaker:
Chih-Lung Lin
Driving Schemes for AMOLED and Micro-LED Displays
Chih-Lung Lin, National Cheng Kung University (Taiwan)

Active-matrix organic light-emitting diode (AMOLED) and micro-light-emitting diode (micro-LED) displays are expected to be the next -generation of display technology. In this talk, the characteristics of thin-film-transistors (TFTs), and their operation principles, pixel circuits, and driving schemes are systematically investigated for promising high-resolution, high-brightness, and high-image-quality display applications. For AMOLED displays, the electrical issues of devices, the classification of driving methods, and the comparison of various pixel circuits are introduced. To extend the period of sensing of threshold voltage (VTH) variations of TFTs, a high-resolution AMOLED pixel circuit that uses overlapping compensation times is presented. The increased sensing period of 33.3 μs results in a higher contrast ratio and more precise VTH compensation than those with sensing periods of 4.3 and 2.2 μs. Also, a pixel circuit with a leakage-prevention method (LPM) is proposed to balance the off currents at the gate node of the driving TFTs, which eliminates the drop in the driving voltage, for AMOLED smartwatch displays at a low frame rate of 15 Hz. For micro-LED displays, the recent development trends, power consumption issues, and the pulse-width modulation (PWM) driving method of micro-LEDs are analyzed. A mini-LED driving circuit that adopts the PWM driving method is proposed for use in a liquid-crystal display (LCD) backlight. Since this circuit uses the PWM method, the mini-LED can be operated at the a high luminance-efficacy point, reducing the power consumption of the mini-LED driving circuit by more than 21% compared to that of a circuit driven by pulse amplitude modulation (PAM). Finally, the pros and cons of the driving schemes for AMOLED and micro-LED displays and their future perspectives are discussed

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13:30 - 14:00
Manuscript ID.  0905
Paper No.  2022-FRI-S0701-I002
Invited Speaker:
Chi-Chang Liao
There is light; there is infinity display
Chi-Chang Liao, IRIS Optronics Co., Ltd (Taiwan)

Unique Characteristics of Cholesteric Liquid Crystal Display
* Vivid picture - Infinite Color
* Self-powered by solar cell - Infinite Power
* Various application - Infinite Usage Scenario

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14:00 - 14:15
Manuscript ID.  0316
Paper No.  2022-FRI-S0701-O001
Chi-Shun Yang Image quality improvement of transparent waveguide display based on a twisted nematic mode polymer-stabilized liquid crystal
Chi-Shun Yang, Heng-Yi Tseng, Kuan-Wu Lin, Li-Min Chang, Guan-Yu Lu, Cheng-Chang Li, National Sun Yat-Sen University (Taiwan); Sheng-Wen Wang, Ko-Ting Cheng, National Central University (Taiwan); Tsung-Hsien Lin, National Sun Yat-Sen University (Taiwan)

This study uses a twisted nematic mode polymer-stabilized liquid crystal (TN mode PSLC) and combined with a crossed polarizer to make a transparent waveguide display. PSLC scatters the edge-lit light with a great polarization selectivity when applied voltage so the majority of the scattered light can pass the analyzer with small loss. On the other hand, most of the background light was absorbed by the analyzer in the ON state. With this structure, we can display waveguide light by scattering while keeping off the background light to achieve better image quality.

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14:15 - 14:30
Manuscript ID.  0290
Paper No.  2022-FRI-S0701-O002
Yen-Hsun Chen Lattice Analyzing of Three-Dimensional Photonic Liquid Crystals by a Diffraction Method
Yen-Hsun Chen, Po-Chang Chen, Duan-Yi Guo, Ting-Mao Feng, Hung-Chang Jau, Tsung-Hsien Lin, National Sun Yat-sen University (Taiwan)

In this work, we propose a method based on angle-dependence Bragg reflection to simulate the diffraction pattern of a three-dimensional liquid crystalline photonic crystal (3D LCPC). The simulated diffraction pattern goes well fitting with the experiment one so that we can extract the lattice parameters of a 3D LCPC. In addition, we can construct a wavelength-scanned 3D diffraction pattern of a 3D LCPC with different lattice symmetries to analyze their dispersion relation.

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14:30 - 14:45
Manuscript ID.  0396
Paper No.  2022-FRI-S0701-O003
Zhi-Qun Wang Control of large-area orderliness of electrically-induced 2D supramolecular chiral microstructures by 1D microgroove structures
Zhi-Qun Wang, Yu-Jun Wong, Chia-Rong Lee, National Cheng Kung University (Taiwan)

Self-assembled periodic micro/nanostructure responses triggered by external excitation often occur in anisotropic self-assembled supramolecular systems such as liquid crystal systems. However, the orderliness of these structures is barely controlled. This study sets a precedent that large-area ordering of 2D supramolecular chiral microstructures based on electro-induced Helfrich deformation can be achieved by utilizing the guidance of pre-established 1D periodic microgrooves on substrate. The influences of depth and spacing of microgrooves on the arrangement of the 2D microgrid structure were also investigated. It is expected that this method could be applied to general self-assembled periodic microstructures regardless of external stimuli or materials.

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14:45 - 15:00
Manuscript ID.  0057
Paper No.  2022-FRI-S0701-O004
Wei-Ting Hsu Planar alignment of nematic liquid crystal networks via microchannels
Wei-Ting Hsu, Yu-Chieh Cheng, National Taipei University of Technology (Taiwan)

In this study, we use two-photon technology to fabricate two-dimensional microchannel structures which can control the liquid crystal (LC) alignment of liquid crystal networks (LCN). These micro-channels can achieve horizontal alignment of LC without electrical control. Moreover, a programmable soft actuator with a high-resolution complex pattern of LC alignment could be achieved. Such a planar liquid crystal alignment method provides great applications in biomimetic small-scale actuators and medical microsystems.

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