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February 7, 2001

Sony Develops World's Largest Full Color Organic EL Display

- Next Generation Consumer Display Device for the Broadband Network Era -

13-inch Full Color Organic EL Display (Prototype)
*Composite picture of the actual screen and the frame/background
*Left: Postcard for size comparison

Sony Corporation today announced the development of a large-scale Active Matrix Organic Electroluminescence (OEL) display driven by thin film transistors (TFT).This was achieved through the utilization of Sony's proprietary Top emission Adaptive Current drive (TAC) technology that realizes high luminance and high resolution for large-scale displays over 10 inches.The featured prototype is 13 inches diagonally with a resolution of 800x600 pixels.

OEL displays driven by low-temperature polysilicon TFT are characterized by the self-luminous characteristic which offers wide viewing angle, high contrast ratio and precise color reproduction.OEL displays are also highly luminant, extremely thin and respond quickly to moving pictures.Recognizing their potential, the display industry is actively involved in R&D efforts for applications such as handhelds (PDA) and mobile phones. However, conventional driving systems induce non-uniformity of luminance which makes it difficult to apply OEL displays to large-scale applications.Also, the physical structure of OEL displays poses many technological challenges to attain higher luminance and resolution in the future.

In order to overcome the above challenges and to apply the OEL displays to large-scale displays over 10 inches, Sony developed the TAC technology to effectively drive the pixels thus attaining uniform luminance and high picture quality.Having developed the prototype, Sony will now advance its development to establish a mass production process to practically apply OEL displays to consumer display and computer monitor applications.

With the arrival of the broadband network era, display devices will play a key role as an interface connecting users to a variety of contents available over the network system.Sony will continue to actively develop next-generation display technologies that fulfill the requirements for a variety of applications and form factors.

Outline of the Top emission Adaptive Current drive (TAC) Technology
1) Current Mode Programmed Pixel-Driver Circuit
The conventional 2-transistor driver circuit has an inherent problem of luminance non-uniformity due to the varying characteristics of the individual pixels.The TAC utilizes 4 transistors, of which 2 transistors are paired up to offset those variations to attain uniform luminance over the entire screen.As a result, luminance non-uniformity can be minimized to facilitate the development of large-scale displays over 10 inches.

2) Top Emission Structure
Unlike the conventional bottom emission structure where emitted light is partly blocked by the TFT structure, top emission structure emits light through the opposite side without any interference.In addition to increasing luminance, pixels can be fabricated smaller to realize higher resolution.

3) All Solid-State Structure
OEL substrate deteriorates rapidly when exposed to moisture and oxygen in the atmosphere.Conventional OEL displays use metal caps and moisture-absorbent to seal the panel, which add thickness to the panels.The top emission structure allows the OEL substrate to be sealed by a transparent plate, which does not require moisture-absorbent.This realizes an all solid-state panel that can be made substantially thinner compared to the conventional structure.

Specifications of the Prototype
Display Size 13 inch diagonal(264x198mm)
Number of Pixels 800x600(SVGA)
Pixel Pitch 0.33x0.33mm
Color (CIE) R(0.66,0.34)G(0.26,0.65)B(0.16,0.06)
Color Temperature (White) 9300 K
Peak Intensity 300cd/m2
Driver Type Low-Temperature Polysilicon Active Matrix