Implementation of see-through liquid crystal displays using transparent light-guide plates

Abstract

As endeavor to develop future display devices, researches on various display devices have been studied recently. Especially, transparent displays are considered as one of the promising future device, and much attention has been drawn. In the way of its realization, head mounted displays (HUDs) and organic light emitting diodes (OLEDs) has been mainly studied. However, each of them has drawbacks; HUDs’ complexity in optical system and immature technologies for OLEDs. As a part of this endeavor, a new transparent display device, ‘see-through liquid crystal display (LCD)’, was developed in this thesis. Conventional LCDs, however, has not been considered as suitable technology for the transparent displays, mainly because key components, backlight unit (BLU) and color filter on the LC panel, are not transparent at all. Nevertheless, in the point that the LCD technology is versatile as used for from mobile devices to large TVs, and mature through long history in display industry, LCDs are very attractive technology for the transparent display. Therefore, in this thesis, LCDs were adopted as a backbone strategy, and key components which hinder LCDs from being transparent were eliminated or modified. Concept and operating principles of two types of see-through LCDs; a transmissive type and a reflective type, were proposed. Both types are normally transparent in non-operating mode. However, when operating, information is displayed on the transparent LC panel. For the realization of proposed devices, color filter was removed as the first step, so transmittance of the LCD panel was able to be enhanced dramatically. Instead field sequential color display (FSCD) scheme was introduced to realize full color without the color filter. For realization of FSCD, three primary color, red, green, and blue light sources were necessitated. In addition, a new transparent light-guide plate (LGP), which can replace the conventional BLU, while having the property of transparency, w...