Both the STN LCDs and the a-Si AMLCDs have advanced to high levels of production. The lower cost STN LCD is used in word processors and computers, and the higher cost, higher performance a-Si AMLCD is used where video speeds and full color are needed.

Between these two technologies in cost and performance is the MIM technology, also in production and in the marketplace. Most Japanese displays companies are committed to high-volume STN LCD and a-Si AMLCD production. In Japan, it is felt that STN LCDs (and derivatives using compensators and retardation films) and a-Si AMLCDs will be the dominant FPDs throughout the 1990s. They are expected to compete for market shares, with low cost on the one end and high performance on the other. The MIM approach will compete as a price/performance compromise between the lower cost STN LCD and the higher performing a-Si AMLCD.

The other LCD approaches have not reached significant production comparable to STN, MIM, and a-Si AMLCDs. The ECB and FLC displays have not yet been put into production; however, two companies, Stanley and Canon, expect production within a year.

The magnitude of investment made by various companies in STN LCDs and a-Si AMLCDs exceeds any such commitment ever made in the history of flat-panel displays. Table 1.5 tabulates various company project announcements. The table is not definitive as to when the investments are made and what portion of the investment is in land and buildings; it is more important from the standpoint of the total announced projects and the companies involved. Conservatively, the amount totals over two billion U.S. dollars.

Table 1.5
Investments in AMLCD Factories in Japan

Production Size

In size, LCDs are limited to approximately 15 inches by the size of the substrates, electronic line driver issues, and cross-coupling in the row and column display matrix. There have been evolutionary improvements in STN, MIM, and a-Si AMLCD electronic line drivers and cross-coupling such that video graphic adapters (VGA) (640 x 480 lines) and television resolutions are in production in 1991 and will improve as the computer and television industries move to higher resolution.

The physical size of the LCD is limited by machine substrate size. In Japan, the LCD production machine industry has just developed the capability to process substrates nominally 320 mm x 400 mm. This development has been extremely expensive; the major production machines used for making a-Si TFTs typically cost over one million U.S. dollars each.

The sentiment in the LCD manufacturing industry is that a new era of electronic production has arrived, that is, three-micron design rule on printed circuit board- size substrates. New lessons in production processes, production machinery layout, materials handling, and so forth need to be learned. This generation of machinery must pay for itself before the next quantum size change can be considered. As a consequence, the next significant size change, particularly for AMLCDs, may not occur until the year 2000.

Published: June 1992; WTEC Hyper- Librarian