A 470 × 235-ppi poly-Si TFT-LCD for high-resolution 2-D and 3-D autostereoscopic displays Shin-ichi Uehara Naoyasu Ikeda Nobuaki Takanashi Masao Iriguchi Mitsuhiro Sugimoto Tadahiro Matsuzaki Hideki Asada Abstract — We have developed a 470 × 235-ppi poly-Si TFT-LCD with a novel pixel arrangement, called HDDP (horizontally double-density pixels), for high-resolution 2-D and 3-D autostereoscopic displays. 3-D image quality is especially high in a lenticular-lens-equipped 3-D mode because both the horizontal and vertical resolutions are high, and because these resolutions are equal. 3-D and 2-D images can be displayed simultaneously in the same picture. In addition, 3-D images can be displayed anywhere and 2-D characters can be made to appear at different depths with perfect legibility. No switching of 2-D/3-D modes is necessary, and the design’s thin and uncomplicated structure makes it especially suitable for mobile terminals. Keywords — 3-D, high resolution, poly-Si TFT-LCD. 1 Introduction A variety of 3-D displays not requiring special glasses have been recently developed for entertainment, medical, design, and other applications. Although they seem to hold promise for use as next-generation displays, a number of design problems remain. 3-D image quality suffers, for example, from low resolution (e.g., 52, 1 83, 2 and 166 ppi 3 ), lower than the resolution of ordinary 2-D displays currently used in commercial mobile phones, as shown in Fig. 1. One of our objectives has been to achieve high-quality 3-D images by designing a high-resolution 3-D display, one in which resolution is higher than that of ordinary 2-D displays. In addition, there are some problems in 3-D display resolution. In a conventional LCD, each pixel (containing three dots: red, green, and blue) is a square. For use in a 3-D display, one pixel must be assigned to the left eye and an- other to the right eye. Each set of left-eye/right-eye pixels, will then form a rectangle in which the length of the hori- zontal is twice that of the vertical. This means that horizon- tal resolution will only be half that of the vertical, which severely limits 3-D picture quality. Further, when 2-D char- acters are displayed, this arrangement may result in con- stituent elements of certain characters being missing, thus causing those characters to be illegible. We have responded to these problems by developing a 470 × 235-ppi poly-Si TFT-LCD with a novel pixel arrangement called HDDP for high-resolution 2-D and 3-D autostereoscopic displays. 3-D image quality is especially high in a lenticular-lens-equipped 3-D mode because both the horizontal and vertical resolutions are high, and because these resolutions are equal. 3-D and 2-D images can be dis- played simultaneously in the same picture. In addition, 3-D images can be displayed anywhere and 2-D characters can be made to appear at different depths with perfect legibility. No switching of 2-D/3-D modes is necessary, and the design’s thin and uncomplicated structure makes it espe- cially suitable for mobile terminals. 2 HDDP arrangement 2.1 Principle Figure 2 shows the principle of the HDDP arrangement. The HDDP arrangement incorporates rectangular pixels whose width is half that of their height. The horizontal pixel density is twice that of the vertical. As a result, each left- eye/right-eye set of pixels forms a square, and in a lenticu- lar-lens-equipped 3-D mode, horizontal resolution will equal that of the vertical. This not only results in high 3-D image quality, it also means that 2-D characters can be displayed with perfect legibility without the need for any sort of 2-D/3-D conver- Revised version of a paper presented at the 24th International Display Research Conference (Asia Display '04) held August 23–27, 2004, in Daegu, Korea. The authors are with SOG Research Laboratories, NEC Corp., 1120 Shimokuzawa, Sagmihara 229-1198, Japan; telephone +81-42-771-0689, fax -0780, e-mail: s-uehara@ak.jp.nec.com. © Copyright 2005 Society for Information Display 1071-0922/05/1303-0209$1.00 FIGURE 1 — Trends in display resolution. Journal of the SID 13/3, 2005 209