A thin-film transistor (TFT) panel is an active matrix display containing a microscopic thin-film transistor in the corner of each pixel. These transistors are formed by an etching process very similar to that used to fabricate semiconductors. Active matrix panels are better suited to the handling of high-quality data and video than passive (or simple) matrix panels because problems with cross-talk and contrast do not arise, even if the panel has a very high pixel count.
High-temperature polysilicon (HTPS) panels are active matrix
displays with TFTs having particularly outstanding elemental
properties. Theses panels offer the advantage of being able
to embed driver ICs, facilitating miniaturization (higher
pixel counts and higher aperture ratios). They are also
more compact and offer higher definition and higher contrast
than conventional TFT panels. These advantages make them
ideal projection display devices, such as light valves for
data projectors and projection TVs.
Epson is a global leader in HTPS panel production, thanks to its strengths in semiconductor and micromechatronic technologies. In fact it boasts a solid track record going back to 1983, when it became the world's first company to succeed in developing a TFT color display for pocket LCD TVs. It began full-scale production of HTPS panels for LCD projectors in 1994 by building on this TFT technology and has manufactured some
18 million panels to date, accumulating great know-how and experience along the way. Around
75% of projectors on the market today employ the LCD system, and Epson manufacturers four of the five HTPS panels used in such systems around the world.
High performance
The formation of thin-film transistors on
a glass substrate requires fairly high temperatures. The
processing temperature for ordinary amorphous silicon panels
is in the range of 300
to 400
For an HTPS panel, though, the temperature reaches as high
as 1000,
and hence its name. HTPS panels offer extremely high performance,
as measured in terms of degree of miniaturization, high
definition, response speed, and reliability.
Specialized applications
HTPS panels are able to embed driver ICs directly onto the surface along the edges. A panel with integrated drivers is more compact and offers higher definition. Another advantage is that they can be built with a light-shielding layer that protects the TFTs from incident light.
This means that even under the intense light inside a projector,
there is no degradation of picture quality.
Because projector images are formed by transmitting light through panels measuring only about one inch, even the slightest speck of dust or flaw on the display panel will show up on the screen magnified several hundred times. This is an important consideration, especially since projectors are now being used to watch movies at home as well as to make business presentations.
*Check the Website of your local
Epson sales company for details of Epson
projectors containing unique HTPS technology.
