Abstract
We propose a novel method for appropriately controlling the luminance distribution of liquid crystal displays (LCDs) for different usage environments by using electric-field-driven liquid crystal (ELC) lenses. The LCD systems are composed of quasi-collimated backlights (QCBLs), LC panels, and ELC lenses that are used as diffusers. To achieve a wide viewing angle, light is diffused with the ELC lenses by controlling its retardation with the voltage applied to the electrodes. For private use, a narrow viewing angle is achieved by turning the ELC lenses off so that the collimated light from the QCBLs passes directly through the liquid-crystal layer of the ELC lens and travels without diffusion. To validate the proposed method, we simulated the luminance distributions of the wide-view and narrow-view modes by using a finite difference method (FDM) and Taguchi’s design of experiments method. The simulation results show that the light distribution of the wide-view mode was 84.3% similar to the ideal Lambertian distribution and was wider than that of IPS-LCDs with wide viewing angle characteristics. In addition, the light distribution of the narrow-view mode had a full width at half maximum of 7°. The luminance of the exiting light at viewing angles of 20° and above was calculated to be close to 0.
Highlights
Liquid crystal displays (LCDs) have played a leading role in the display market by virtue of their long service life, low power consumption, and low price
An LCD system was equipped with the electric-field-driven liquid crystal (ELC) diffuser, and the light distribution was calculated by ray tracing, and the viewing angles could be switched by the voltages applied to the diffuser
The diffuser can be driven at a lower voltage, and the vertical component of the electric field near the electrodes can be appropriately controlled
Summary
Liquid crystal displays (LCDs) have played a leading role in the display market by virtue of their long service life, low power consumption, and low price. Several types of the LCDs for controllable viewing angles have been reported: Dividing the pixels according to the viewing angles [7,8,9], additional viewing angle control systems [10,11], switchable viewing angle backlight systems [12,13] These methods reduce the resolution and brightness compared to the conventional LCDs, or use unique liquid crystals such as the blue phase and discotic phase, thereby causing problems in temperature reliability and fabrication. A new method is proposed to electrically control the viewing angle of LCDs in various usage environments by using an electric-field-driven liquid crystal (ELC) lens [18] as a diffuser in front of the LCD. An LCD system was equipped with the ELC diffuser, and the light distribution was calculated by ray tracing, and the viewing angles could be switched by the voltages applied to the diffuser
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