Date Visited: October 3, 1991
Report Author: J. Covert
Dai Nippon Printing (DNP) was established in 1876 as Japan's first full-scale printing company and has grown to be the "largest-scale all-inclusive printing company in the world," with $7.45 billion annual sales and 11,900 employees in 1990. Business includes printing on paper (60% of business); printing on plastic, metal, wood, glass, cloth, leather; packaging; decorative interior materials; and electronic parts. Electronic areas include color CRT shadow masks, color filters for image tubes and solid state imagers (video cameras, color FAX, LCD displays with line widths 10 - 500 microns), microlens array screens, photo-etching, CAD/LSI design systems, TR/IC/LSI/VLSI photomasks, video printing, electroforming, etching, stamping, and printed wiring boards. Headquarters are in Tokyo, with 20 division offices, 47 sales branches, and 20 production facilities around the world.
We were greeted by Mr. Kamei and Mr. Wada, who indicated that discussions would include LC, EL, and plasma displays with research only (no production) for plasma displays. Professor Uchiike participated in all discussions, including plans for the SID meeting in two years at Hiroshima. He indicated HDTV displays would be on exhibit, and that Sharp was interested in sponsoring a new SID award.
Mr. Tsuda discussed color filters for LCDs. Uniformity of filter thickness is more critical for STN than for TFT LCDs, and it is easier to achieve uniformity for stripe pixel patterns vs. mosaic and triangle. They are beginning improved black matrix material research, but are currently using only 20-30 microns line width chromium black matrix (done with photo stepper 1-micron design rule lithography).
Four methods for manufacturing LCD color filters were discussed (dyed, dispersed, electrodeposition, and printing), with comparative capabilities and characteristics given for each. Dai Nippon produces color filters only for TFT LCDs (none for STN) using the dispersed method. A printing method is being developed for the low-end laptop market to save manufacturing costs using three fewer process steps. Uniformity of the ink transfer is the biggest problem in this development today. Toppan uses the dyed method which has a lower operating temperature than the dispersed method, but is best to design the filter's transmission spectrum. Shinto Chemitron produces color filters using the electrodeposition method.
Five color filters were shown. One looked like 6- x 8-inch VGA using color stripes. Two were 3 x 5 inches with triads, and two were 2- x 2-inch quads (about 512 x 512 pixels). DNP produces 30-50 microns color filters for camcorders using the dispersed method. They made some critical process changes for this application, but details were not provided.
Mr. Kojima addressed JTEC questions regarding plasma displays. The level of activity in plasma displays was discussed. NEC and DNP have stopped production. AC plasma work continues at Fujitsu (production), NEC (research), DNP (research), and Hiroshima University (research). DC plasma work continues at Oki (production), Matsushita (production), Okaya (production), NHK (research), DNP (research), Mitsubishi (research), Hitachi (research), Noritake (components only), and Electro Communication University (research). Interest in plasma is increasing for large color HDTV because of difficulty in achieving large color LCD HDTV.
Professor Uchiike commented on plasma displays. He was positive about achieving adequate driver pulse current load for large panels. He indicated phosphor efficiency is near 100% with UV excitation. He was positive about generating UV from He-Xe gas that does not generate light efficiently. He indicated UV energy does not get through the phosphor protective layer; however, the ions do damage phosphor without a protective layer.
The level of activity in EL displays was discussed. EL work has stopped at NTT, NEC, Fujitsu, and Hitachi. EL work is continued at Oki, Tottori University, Ehime University, Sharp (production), and Komatsu.