• Journal of Information Display
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• v.5 no.2
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• pp.6-9
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• 2004

We have developed the Scan-backlight Stereoscopic LCD that is a kind of field-sequential -Stereoscopic LCD combining the Dual- Directional- Backlight and the fast-response OCB panel. The Dual-Directional-Backlight using a double-sided prism sheet can change the direction of light by switching the LED light sources. The OCB panel using Feed-Forward Drive can realize frame rate of 120 Hz. As a result, the Scan-backlight Stereoscopic display works at its original resolving power, and produces flicker-free stereoscopic images. This auto- stereoscopic display can resolved the problems of the double images and the pseudoscopic images in case of watching at oblique angles.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.255-258
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• 2004

We have developed the Scan-backlight Stereoscopic LCD that is a kind of field-sequential -Stereoscopic LCD combining the Dual-Directional-Backlight and the fast-response OCB panel. The Dual-Directional-Backlight using a double-sided prism sheet can change the direction of light by switching the LED light sources. The OCB panel using Feed-Forward Drive can realize frame rate of 120 Hz. As a result, the Scan-backlight Stereoscopic display works at its original resolving power, and produces flicker-free stereoscopic images. This auto stereoscopic display can resolved the problems of the double images and the pseudoscopic images in case of watching at oblique angles.

• Current Optics and Photonics
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• v.4 no.5
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• pp.421-427
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• 2020

A novel privacy-protection device to prevent visual hacking is realized by using a directional backlight and facial recognition. The proposed method is able to overcome the limitations of previous privacy-protection methods that simply restrict the viewing angle to a narrow range. The accuracy of user tracking is accomplished by the combination of a time-of-flight sensor and facial recognition with no restriction of detection range. In addition, an experimental demonstration is provided to verify the proposed scheme.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.799-806
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• 2016

We present a polarization-dependent prism array film for controlling the viewing angle distribution of liquid crystal (LC) display panels without loss of light efficiency. On a directional backlight unit, our polarization-dependent prism array film, made into a stacked bilayer with a well-aligned liquid crystalline reactive mesogen (RM) layer on the UV-imprinted prism structure, can continuously control the light refraction function of the prism array by electrically switching incident polarization states of a polarization-controlling layer prepared by a twisted nematic LC mode. The viewing angle control properties of the polarization-dependent prism array film are analyzed under different prism angle and refractive index conditions of the RM layer. A simple analytic model is also presented to describe the intermediate viewing angle distributions with continuously varying applied voltages and incident polarization states.

• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.247-255
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• 2011

The optical performance of LLF(Lenticular Lens Film)-based backlight was studied by using optical simulation as functions of the aspect ratio and the refractive index of lenticular lenses. In order to perform reliable simulation, the BSDF(bi-directional scattering distribution function) of the scattering dots on the bottom surface of the light guide plate was obtained as a superposition of the Lambertian and the elliptic Gaussian distribution components by comparing the experimental results and the simulation for the luminance distribution on the light guide. Based on this approach, an appropriate BSDF of the scattering dots of the light guide was constructed. The resultant values of the optimized aspect ratio and the refractive were found to be 1.25 and 1.65, respectively. In spite of the hybrid aspects of LLF incorporating both diffusing and collimating functions, the optical performance, in particular the on-axis luminance of LLF-based backlight was inferior by about 20% compared to that of conventional backlights adopting one prism film. However, the combination of two lenticular lens films resulted in comparable luminance gain as well as smooth decrease in the luminance with the viewing angle without exhibiting any side lobes.

• Korean Journal of Optics and Photonics
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• v.31 no.4
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• pp.176-182
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• 2020

The possibility of replacing the condensing-prism film used in conventional backlight units with a light-guide plate engraved with a submicrometer-periodic diffraction grating was investigated. The optimal period for the diffraction grating was determined through simulation and experiment, and the transmission-mode efficiency of the diffraction grating was calculated in terms of the polar angle and azimuthal angle of the incident light. In addition, the effects of the two methods of optimizing the polar angle and the directional angle were compared by simulation, by suggesting the shape and configuration of the light-guide plate, so that more light could be extracted by diffraction. By using a ray-tracing program, the luminance angular distribution of the light-guide plate engraved with the diffraction grating was calculated and compared to the luminance angular distribution for each actual prototype.