LCD Wide-Angle-View Technology
article in DigiTimes reported that Toshiba has included
a new wide-angle-view technology in a 9-inch LCD aimed at mobile audio-visual
use. The text of the article is as follows:
"Toshiba Matsushita Display
Technology (TMDisplay) announced that it has incorporated optically compensated
bend (OCB) and field sequential technologies into its latest 9-inch TFT LCD
According to Toshiba, OCB technology provides exceptionally wide viewing angles
in all directions, without color shifts or inversions, and provides ultra-fast
response time of less than 5ms, even during gray-to-gray transitions. TMDisplay
noted that the viewing angle on its latest panel is 170 degrees in all directions
and the response time is 3.3ms. In addition, by incorporating field sequential
technology, the panel does not require color filters (CFs), and therefore
supports a high transmittance without any absorption loss. Traditionally,
more than 70% of back light brightness is absorbed by CFs."
this technology applicable to Tablet PCs, and if so, when will it appear in
Editor Geoff Walker answers:
has been working on OCB (optically compensated bend) for a number of years.
OCB is another method of making a wide-angle-view LCD like IPS, MVA or FFS.
It works well and seems to be competitive with the other technologies -- although
I don't think Toshiba has said much about the cost yet. One side-benefit
of OCB is that it makes the LCD inherently faster. Another interesting side-benefit
of OCB is that it makes the LCD work much better in cold temperatures (-20C).
Toshiba is focused mostly on mobile screens, so it's natural that they would
show OCB in something like a 9" automotive entertainment screen. As
to when OCB might make it into Tablet PC screens, it depends on how quickly
Toshiba can build their manufacturing ability and get OCB into actual production.
From the Toshiba strategy presentations I've seen, they clearly are planning
to use it in Tablet PC screens. But today they're still presenting OCB as
a "future technology". Note that the article didn't say that the
9" screen is actually being shipped; it's just being exhibited at FineTech, a huge flat panel display show
in Japan this month. My guess is that it will take at least another one to
two years until OCB is actually shipping, and even then it may still be too
high on the cost curve to make it into cost-sensitive Tablet PCs. It will
eventually get there, though, even if it takes 3-5 years.
sequential is becoming popular as a method of eliminating the color filter
in LCDs. In a 32" LCD, the color filter accounts for 25% of the total
cost of the LCD, so it's very significant in the TV world. (I don't know
what the percentage of cost is in a smaller LCD, but whatever it is, it's
not trivial.) In order to do color sequential, a backlight that can alternatively
emit red, green and blue light is required. The only practical kind of backlight
that can do this uses RBG LEDs -- which are still fairly expensive, although
not that much of a problem in a small screen. The LCD controller is synchronized
with the backlight so that when a given color backlight is on, only the matching
color sub-pixels in the LCD are turned on. One advantage of using an RGB
LED backlight is that the color gamut is much higher. Small LCDs typically
can only produce 50% of the NTSC color gamut; with an RGB LED backlight they
can get close to 100%, which means that the color is much richer and more
realistic. Also, as the article points out, the color filter absorbs a lot
of light, so eliminating the filter means you can reduce the brightness of
the backlight, which reduces the power consumption of the LCD significantly.
advantage of color sequential is that instead of using the standard three
subpixels for each pixel (one each for red, green and blue), the LCD can be
redesigned so that it has three times as many regular pixels. What was a
subpixel becomes a small regular pixel, which means that the resolution can
be increased by a factor of up to 3X. The LCD controller is still synchronized
with the backlight; when a given color backlight is on, each pixel is set
to the correct value for that color in the image. Your eyes are actually
seeing a rapid sequence of red-green-blue images, but your brain combines
them into a full-color image.
connection between OCB and color sequential is through performance. OCB inherently
reduces the LCD response time, making it able to change faster. If color
sequential is used to increase the resolution of the LCD, then a faster-responding
LCD is needed because each (former) subpixel is changing three times as often.
So the technologies work well together.
full press release can be found here
(it contains a little more information than the DigiTimes article, although
the English is horrible). A listing of all current Toshiba LCDs can be found
Based in Silicon Valley, Geoff Walker is Global Director of Product Management at Elo TouchSystems. Prior, he was a consultant
with Walker Mobile, LLC (www.walkermobile.com).
Geoff has worked on the engineering and marketing of mobile computers
since 1982 at GRiD Systems, Fujitsu Personal Systems (now Fujitsu
Computer Systems) and Handspring. In addition to mobile computers,
Geoff's areas of particular expertise include displays and digitizers.