16-3: A Novel Transparent Screen Using Cholesteric Liquid Crystal Dots

Abstract

We have successfully developed a novel transparent screen using inkjet-printed cholesteric liquid crystal (CLC) dots. By precisely orienting the CLCs in spherical layers, this transparent screen has wide viewing angle for front projection, and achieves both low haze and high screen gain. The clearness of this innovative projected image can make augmented reality applications look much more realistic.Author Keywords transparent screen; cholesteric liquid crystal; inkjet; spherical orientation; wide viewing angle; front projection. Objectives and BackgroundTransparent screens are currently drawing great interest, as they enable the projected image to look as if it were floating in air. They have many applications, like augmented reality (AR) where a projected image is superimposed on a background object, digital signage, and head-up displays.In the past, various transparent screens have been proposed. Those using scattering by small particles [1,2,3], those making patterns with scattered particle portions and transparent portions [4], those using a microlens array [5], and those using a combination of prism-like structure and particle scattering [6] are known. However, in all of these transparent screens, if reflection intensity is raised, haze also becomes large. It has been difficult to avoid this trade-off relation and achieve both sufficient brightness and sufficient transparency. Moreover, as the forward scattering is strong in those screens using particle scattering, those screens are intrinsically limited to rear projection type displays as in Fig. 1(a), and open space on either side of the screen is required. This is a large restriction, especially in indoor applications that cannot install the projector on the rear side. For such applications, a transparent screen that allows front projection is desired.For further space-saving, a short focus projector as shown in Fig. 1(b) is also being developed [7]. As a short focus projector projects light from a point close to the screen at a sharply oblique angle, the screen needs to have a wide viewing angle.In this paper, we describe development of a novel transparent screen that resolves the abovementioned issues. This transparent screen consists of CLCs that are deposited using drop-ondemand inkjet technology [8]. Using our unique orientation controlling technology [9], we precisely control the orientation of the CLCs. This novel transparent screen has a wide viewing angle for front projection, and achieves both low haze and high screen gain.In 2-1 below, we explain the fundamental components and concepts of this technology. In 2-2, we describe the configuration of our novel transparent screen. In 2-3, the performance of the screen is described. Results and Discussion 2-1. Orientation Control of Cholesteric Liquid Crystal Dot:CLCs organize themselves into a helical layer structure in which the director axis of the liquid crystal molecules twists with each layer. CLC layers selectively reflect light of wavelength equal to the pitch of this helix, and the ...

42‐3: Novel Transparent Screen Combined with Light Guide System

“…However, it was difficult for the current transparent screen to achieve both properties, because it generally uses nano-particles (particles on the scale of tens to hundreds of nm) to scatter light [1,2], and the scattering is isotropic (Rayleigh scattering) or forward (Mie scattering). To achieve high transmittance and high image visibility simultaneously, we focused on cholesteric liquid crystals which have different optical properties, reflection, from scattering, and developed a transparent screen by controlling the dot-shape or waved-alignment of cholesteric liquid crystals [3,4].…”

70‐4: Higher‐Contrast and Lower‐Haze Transparent Screen Using Waving Cholesteric Liquid Crystals

“…In contrast, our previous transparent screen presented at SID 2016 [3] is made of cholesteric liquid crystal dots whose shapes are controlled by an inkjet apparatus. This is a front projection type screen which we could make low-haze as well as highcontrast using choresteric liquid crystal reflection ( Fig.2b).…”

Near‐Eye Display and Tracking Technologies for Virtual and Augmented Reality

“…Using silver nanoparticles and a front projector, Hsu et al [HZQ∗14] create a transparent screen that backscatters light at specific wavelengths. Yamamoto et al [YYN∗16] also describe a different approach to a wavelength‐selective front‐projection transparent screen using cholesteric liquid‐crystal dots .…”