Oct 8, 2008 11:16
Nikkei Electronics Asia
Sony Corp of Japan has announced eight new BRAVIA liquid crystal
display (LCD) televisions (TV), all excellent products that push the
envelope. Among them, two models are especially eye-popping: (1) an
ultra-thin model only 9.9mm in its thinnest part, and (2) the top-end
model offering the "highest image quality of any BRAVIA ever." Both
amply demonstrate the high potential inherent in LCD TVs.
The 9.9mm-thick 40-inch design (1) is dramatically thinner than the
former champions on the market, the 34.4mm-thick models from Sharp Corp
of Japan in 46-, 42- and 37-inch screen sizes. It is closer, in fact,
to the 3mm thickness of the 11-inch organic light-emitting diode (OLED)
TV released by Sony. The case also closely resembles that of the OLED
TV, and looks like it belongs in the same line-up.
This astonishing thinness was achieved by revamping the backlight: the
design uses white LEDs for the light source, positioned at the edges of
the panel in an edge-light configuration (1). Backlights for
large-screen TVs are usually cold-cathode fluorescent lamps (CCFL)
mounted directly behind the screen. The combination of white LEDs and
edge lighting is the key to the incredible thinness. There are some
problems, however - such as difficulty in boosting brightness - which
have prevented this design from being adopted in large-screen TVs until
now. Sony has not disclosed exactly how it solved these issues. Instead
of the usual approach of edge lights on two sides of the panel, the new
design positions white LEDs on all four edges, probably to increase
brightness.
The second Sony model, with the "highest image quality of any BRAVIA
ever" has a contrast ratio of 1 million to one, and a wide color
reproduction range of 122% of National Television Standard Committee
(NTSC). The crucial point in this model, again, is the backlight. The
structure is the usual direct illumination from the rear, but the light
source consists of three (red, green and blue; RGB) LEDs operated under
area control. Katsumi Ihara, executive deputy president, representative
corporate executive officer, said with pride, "It is every bit as good
as OLED TV imagery." The numbers back him up: the firm's own 11-inch
OLED TV has the same contrast ratio of a million to one, but a color
reproduction range of only 110% NTSC.
Sony successfully demonstrated that LCD TVs can offer characteristics
on a par with OLED TVs, including thinness and image quality. At the
same time, though, the limitations of LCD TVs have become apparent,
because it would seem to be exceedingly difficult to simultaneously
achieve the exhibited thinness (1) and high image quality (2). The high
contrast of (2) is achieved by area control technology, and because of
the way the technology works it can only be used with direct
illumination from the rear. As one TV engineer pointed out, though, the
minimum backlight thickness is 10mm for direct-illumination designs,
meaning it will be difficult to match the thinness of edge lighting.
Now that large-screen LCD televisions have been brought this far, Sony
has no choice but to develop a large-screen OLED set offering both (1)
and (2)... and as soon as possible.
by Takuya Otani
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