Research and development of a wide-viewing-angle and fast-response liquid crystal display mode, and its application to the high-quality full hi-vision liquid crystal display

The color LCD using micro color filters

Fig.1 The color LCD using micro color filters

The OCB mode LCD with fast response

Fig.2 The OCB mode LCD with fast response

The Field sequential color LCD (FS-LCD) without color filters

Fig.3 The Field sequential color LCD (FS-LCD) without color filters

Comparison of the conventional color LCD with color filters and the FS-LCD without them

Fig.4 Comparison of the conventional color LCD with color filters and the FS-LCD without them

15-inches and 6.5-inches FS-LCDs

Fig.5 15-inches and 6.5-inches FS-LCDs

Broadband communication infrastructure, high-performance cameras and information processing systems have been developed, and along with it, large-capacity and high-quality video image is widely used in the broadcasting and other mass media. In connection with it, the electronic display, especially the liquid crystal display (LCD), is becoming very important because of its outstanding features of a thin, light-weight, low power and a long life. Accordingly, it is demanded to the LCD to be further improvement of resolution and performance with low power for a next-generation display device.
This study is the result of research to pursue high performance LCDs for the above mentioned challenge aimed at practical application.
In terms of colorization of the LCD, Dr. Uchida devised the system which uses the micro color filters of red (R), green (G) and blue (B) in 1981, and it is now widely used as a color LCD [1,2] (Fig. 1). However, this system has drawbacks of energy loss due to light absorption by the color filters and difficulty in respect of high-resolution because one picture element (pixel) consists of three color sub-pixels. For this reason, it was necessary to exclude the color filters for low-power and high resolution.
In the mean time, he devised a new LCD mode named "optically compensated bend mode (OCB mode)" to improve the moving images in the development period of the liquid crystal television [3-11] (Fig. 2). This OCB mode LCD is composed of the liquid crystal cell with bend alignment and optically biaxial retardation films to compensate birefringence of the liquid crystal three-dimensionally, and its response is several tens of times faster than conventional LCD. Thereby, the display performance of the moving image is greatly improved, and Toshiba Matsushita Display Technologies, Inc. manufactured the OCB panel in 2004, and EIZO Nanao Corp. came to market a 23 inches high-quality liquid crystal television. Thereafter, high-speed response at low temperatures has attracted interest, and commercialization has progressed as a display for an automobile.
Using the fast response of this OCB mode, he proposed the field sequential color LCD (FS-LCD) which was a new color LCD without using the color filter in 1997 [12]. This color LCD incorporates three color backlights of R, G and B instead of the color filter, to emit the three colors turning them sequentially, and switches the display image of the liquid crystal panel in synchronization with the color back lights (Fig. 3, 4). The switching speed is fast enough for the human eye, which enable to achieve full-color display by mixing three color images of R, G and B.
In establishing this method, he tackled many subjects including control of molecular orientation of liquid crystal, optimizing device parameters, designing of the optical components to control the wavelength characteristics and the driving system of the display and the light source [13-16]. Based on the results of these studies he organized and managed the research projects, "the Collaboration of Regional Entitles for the Advancement of Technological Excellence (CREATE) of Aomori Prefecture", supported by Japan Science and Technology (JST), and he devoted himself as the Research Director to realize the new color LCD in 2001-2006. As a result, he succeeded in the development and prototyping of ultra-high-resolution color LCDs, 15-inch XGA type and 6.5-inch full-spec high-definition type, which achieved high-quality full-color moving image [14-16] (Fig. 5). It was proved by these works that the FS-LCD has high potential of the low power as well as ultra-high-definition display, and showed the possibility of a next-generation display. These results of research are highly evaluated by the overseas as well as domestic societies.
This result is remarkable achievement from both scientific side and industrial side in respect of research towards low power and high performance, which is indispensable to a next-generation LCD. It is recognized to be suitable for the Achievement Award of this society.


Publications

[1] T. Uchida, “A Liquid Crystal Multicolor Display Using Color Filters”, Proc. European Display Res. Conf., pp. 39-42 (1981).
[2] T. Uchida, S. Yamamoto and Y. Shibata, “A Full Color Matrix Liquid Crystal Display with Color Layers on the Electrodes", IEEE Trans. ED-35 (5), pp. 503-507 (1983).
[3] Y. Yamaguchi, T. Miyashita, T. Uchida, “Wide-Viewing-Angle Display Mode for the Active-Matrix LCD Using Bend-Alignment Liquid-Crystal Cell”, SID Symp. Digest, pp.277-280 (1993).
[4] T. Miyashita, P.J. Vetter, Y. Yamaguchi and T. Uchida, “Wide-Viewing-Angle Display Mode for Active-Matrix LCDs Using a Bend-Alignment Liquid-Crystal Cell”, J. Society for Information Display, 3 (1), pp. 29-34 (1995).
[5] C - L. Kuo, T. Miyashita, M. Suzuki and T. Uchida, “Optimum Dark-State Voltage for Wide-Viewing-Angle Optically-Compensated-Bend-Mode Liquid-Crystal Displays”, Japan. J. Appl. Phys., 34 (10B), pp. L1362-L1364 (1995).
[6] C - L. Kuo, T. Miyashita, M. Suzuki and T. Uchida, “Crucial Influences of K33/K11 Ratio on Viewing Angle of Display Mode Using a Bend-Alignment Liquid-Crystal Cell with a Compensator”, Appl. Phys. Let., 68 (11), pp. 1461-1463 (1996).
[7] T. Miyashita and T. Uchida, “Optically Compensated Bend Mode (OCB Mode) with Wide Viewing Angle and Fast Response”, IEICE Trans. on Electronics, E79-C (8), pp. 1076-1082 (1996).
[8] S. Onda, T. Miyashita and T. Uchida, “Mechanism of Excellent Fast Response and Recover in OCB-Cell with Bend Alignment”, Mol. Cryst. Liq. Cryst., 331, pp. 383-389 (1999).
[9] I. Inoue, T. Miyashita, T. Uchida, Y. Yamada and Y. Ishii, “A new solution for splay-bend transition in OCB mode a twisted area”.J. Society for Information Display, 11 (3), pp. 571-577 (2003).
[10] K. Kuboki, T. Miyashita, T. Ishinabe, T. Uchida, “The Transition from the Splay to Bend State in the OCB Cell”, Mol. Cryst. Liq. Cryst., 410, pp. 391-400 (2004).
[11] T. Ishinabe, T. Miyashita, T. Uchida, K. Wako, T. Kishimoto, K. Sekiya, "Improvement of Transmittance and Viewing Angle of Optically Compensated Bend Mode Liquid Crystal Display Using Wide-Viewing-Angle Circular Polarizer", Japan. J. Appl. Phys., 48 (9), pp.092403-1-092403-6 (2009)
[12] T. Uchida, K. Saitoh, T. Miyashita, M. Suzuki, “Field Sequential Full-Color LCD without Color Filter for AM-LCD”, Conf. Record of The International Display Research Conf., p.37 (1997).
[13] N. Koma, T. Miyashita and T. Uchida, “A Novel Driving Method for Field Sequential Color Using an OCB TFT – LCD”, J. Society for Information Display, 9 (4), pp. 331-336 (2001).
[14] T. Ishinabe, K. Wako, K. Sekiya, T. Kimoto, T. Miyashita and T. Uchida, “High Performance OCB-mode for Field Sequential Color LCDs”, J. Society for Information Display, 16 (2), pp. 251-256 (2008.).
[15] K. Kalantar, T. Kishimoto, K. Sekiya, T. Miyashita, T. Uchida, "Spatio-temporal scanning backlight mode for field-sequential-color optically-compensated-bend liquid-crystal display", Journal of Society for Information Display,14 (2), pp.151–159 (2006).
[16] T. Ishinabe, K. Wako, K. Sekiya, T. Kishimoto, T. Miyashita and T. Uchida, "Development of the Field Sequential Color LCDs using OCB-mode", EKISHO, 15 (2), pp.117-124 (2011).

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