Seiko Epson Corporation

Epson Inkjet Technology Enables Uniform Light Emission for Big-Screen OLED TVs

– TOKYO, Japan, May 26, 2009 –

Seiko Epson Corporation ("Epson", TSE: 6724) today announced it has established inkjet technology that enables the uniform deposition of organic material in the production of large-screen organic light-emitting diode (OLED) televisions. The new technology represents a major step toward the realization of 37-inch and larger full-HD OLED TVs by resolving the uneven layering that had previously been an issue with the inkjet method.

OLED televisions are the odds-on favorite to supplant current technologies as the next generation display. Offering outstanding viewing characteristics, including high contrast, wide viewing angle and fast response time, OLED TVs are also lightweight, ultra-thin, and have low power requirements. A major roadblock preventing mass production of large-screen OLED TVs has been the lack of a technology capable of reliably forming uniform organic layers on large substrates. Vacuum thermal evaporation (VTE), currently the most widely used method of depositing organic materials, is surrounded by technical hurdles that have prevented it from solving the layer uniformity issue and making the jump to mass production of large panels. An inkjet process that deposits organic material in liquid form has long been viewed as the ideal alternative.

Epson has recently developed the long-awaited solution in the form of an OLED display fabrication process that leverages the company's proprietary Micro Piezo inkjet technology to achieve markedly greater accuracy in organic material deposition than the conventional technology. The process has been used in trial production to fabricate a highly uniform prototype panel. Extremely uniform layers (volume error < 1%) are achieved by precisely controlling the selection and ejection of multi-size droplets of ink material on a substrate so that only the required volume of material is deposited. Epson's technology dramatically improves both quality and throughput and brings the advent of large-screen OLED TV a significant step closer to realization.

"Large-screen OLED TVs are the future of displays, and Epson is committed to contributing to the transition to volume production through research and development projects involving inkjet fabrication technologies," stated Satoru Miyashita, General Manager of Epson's OLED Development Center.

Details about this technology will be presented at SID 2009, the Society for Information Display's international symposium, seminar and exhibition, to be held in San Antonio, Texas from June 2. Epson will exhibit a 14-inch OLED display having resolution equivalent to a 37-inch full-HD display. The prototype display was trial-manufactured using Epson's inkjet process.

Advantages of an inkjet process in the fabrication of OLED TVs

A process for forming uniform, thin-film layers of organic material on glass substrates is essential for fabricating OLED TVs. Vacuum thermal evaporation (VTE) is currently the most widely used method for forming thin films on glass substrates. This method, performed in a vacuum chamber, requires that a shadow mask be placed in close proximity to the substrate to define the pattern of material deposited on the substrate. VTE, however, has several drawbacks when it comes to fabricating large-screen OLED TVs. On large panels it can be difficult to maintain a uniform deposition rate, primarily due to displacement of the shadow mask when it is exposed to the high temperatures used in this process.

An inkjet printing process is theoretically the better solution for larger display sizes because it enables thin-film layers to be formed via the deposition of liquid organic materials. Employing the same drop-on-demand approach as an inkjet printer, Epson's process accurately deposits organic materials in the precise locations and amounts required. Since inkjet systems use materials extremely efficiently, manufacturers can cut production costs. Used as an OLED TV fabrication system, inkjet technology, which does not require masks and thus involves fewer process steps than VTE, is widely expected to increase production throughput.

See Epson's web site for more information on Micro Piezo inkjet technology.

http://global.epson.com/technology/micropiezo/