[comp.sys.laptops] ACTIVE MATRIX, how fast is it??

reneb@philica.ica.philips.nl (Rene Bax) (04/03/91)

Hi,
I want to buy a notebook computer and want a FAST an crisp display.
Now, I read the article in the February 1991 issue of BYTE, where they
say that the active matrix screens (also called TFT or Thin Film Transistor)
are very good in speed and in contrast.
Amongst others the SANYO MBC-17NB, the ZEOS 286 and the OGIVAR INTERNOTE 286
were tested. The article said that the notebooks all had the same active
matrix LCD screen, developed by OGIVAR, and according to BYTE the screens
were 'outstanding'.

This month I saw the SANYO MBC-17NB ... what a disappointment...
The screen didn't look fast at all and also had that irregular blue color,
typical for supertwisted screens. The manual said that the LCD screen
was of the STN type (SuperTwist Nematic), and could show only *8* gray scales.
It didn't say a thing about TFT or active matrix.
The 32 gray scales mentioned in the BYTE article were only for the external
monitor.
Here come the questions:
* What exactly is 'active matrix' and how fast is it (e.g. in terms of
  refresh rate).
* To anybody who saw the ZEOS 286 screen: how is the speed/contrast?
* How about the screen for the ZEOS 386SX (the one I'm really interested in),
  is it the same as the one for the ZEOS 286 and therefore the same as that
  for the SANYO??

Rene Bakx
Philips Innovation Centre Aachen
Email: reneb@ica.philips.nl

jst@cca.ucsf.edu (Joe Stong) (04/04/91)

In article <789@philica.ica.philips.nl> reneb@ica.philips.nl () writes:
>I want to buy a notebook computer and want a FAST an crisp display.
>* What exactly is 'active matrix' and how fast is it (e.g. in terms of
>  refresh rate).

My question is not so much about refresh rate, so much as it is
about the time for a pixel to go (90%?) dark, and time for a pixel
to go light.  I kind of think the screens refresh as fast as the
technology needs to have them refresh, but the problem is the
response speed of the liquid crystals.  I'd like to see a screen
that's readable during scrolling.  They seem to scroll much faster
than they can "settle".

No, I don't like long-persistence phosphors, either.  I suspect if
you could get these two numbers into the 5 millisecond range, the
display would look good in motion, right now, it looks like they
are in the 60 millisecond range.

	Joe Stong   jst@cca.ucsf.edu