Kyoung-Moon Lim

Method for Providing Electrovibration with Uniform Intensity

Electrovibration is a type of surface haptics that can modulate lateral forces acting between a fingertip and a touch surface. Electrovibration is fast, consumes little power, and does not involve the use of any mechanical actuators. However, it suffers from problems such as nonuniform perceived intensity due to varying environmental impedances, as well as possible electric shock, which have to be solved for commercialization. In this paper, a current feedback method is proposed to provide uniform intensity of electrovibration, regardless of the varying environmental impedances. The proposed method can also prevent electric shock. To show the effectiveness of the proposed method, a hardware prototype was developed and a user study was conducted. The user study result shows that the proposed current control method can provide significantly more uniform perceived intensity of electrovibration as compared with the conventional voltage control method.

A Novel Five-Photomask Low-Temperature Polycrystalline Silicon CMOS Structure for AMLCD Application

A novel five-mask low-temperature polycrystalline silicon (LTPS) CMOS structure was verified by manufacturing the thin-film transistor test samples using the proposed five-mask LTPS CMOS process. In integrating the five-mask CMOS structure, a selective contact barrier metal formation process was developed, without additional photomask steps, to solve the issue of high-contact-resistance problem encountered inevitably in the contact between the indium tin oxide and doped polycrystalline silicon (poly-Si) source-drain layers. The five-mask CMOS technology was also confirmed by manufacturing a five-mask CMOS panel for the active-matrix liquid-crystal-display application.

Optical modeling of lenticular array for autostereoscopic displays

We suggested a mathematical model describing optical phenomena at the surface of a lenticular array for autostereoscopic displays in 2-view system and simulated the angular distribution of light using Monte Carlo methods under actual design conditions. By comparing the results of our simulation model with those of the conventional simulation tool, we showed good agreement between our model and conventional tool in calculating the angular distribution of light. We also achieved simulation time of 60% faster than the conventional design tool. From the results, we think our optical model is very useful for designing optical parameters of autostereoscopic displays.

New approach on calculating multi-view 3D crosstalk for autostereoscopic displays

In this study, we suggest a new concept of 3D crosstalk for auto-stereoscopic displays and obtain 3D crosstalk values of several multi-view systems based on the suggested definition. First, we measure the angular dependencies of the luminance for auto-stereoscopic displays under various test patterns corresponding to each view of a multi-view system and then calculate the 3D crosstalk based on our new definition with respect to the measured luminance profiles. Our new approach gives just a single 3D crosstalk value for single device without any ambiguity and shows similar order of values to the conventional stereoscopic displays. These results are compared with the conventional 3D crosstalk values of selected auto-stereoscopic displays such as 4-view and 9-view systems. From the result, we believe that this new approach is very useful for controlling 3D crosstalk values of the 3D displays manufacturing and benchmarking of the 3D performances among the various auto-stereoscopic displays.