We evaluate the quality of the TFT display
with the help of a program called Nokia Monitor Test. The software
application displays a range of colours and test patterns that can help
diagnose just about any visual problems or defects a TFT display may
contain. It can also be a very useful tool for properly adjusting a
display to the correct settings. The software consists of eleven tests
which can be run in steps as adjustments are made to the OSD. As the tests
are run we look for the following problems, only one of which should be
inoperable (broken pixel).
Broken Pixels: What we class as a 'broken pixel' can
fall under any one of the following circumstances: Pixel always on (any
colour), pixel always off, pixel unable to display a shade (red, green,
blue, black, white), pixel shown colour gradient.
Pixel Clock: If the number of dot clocks within one
horizontal synch are not properly configured the screen will appear to
drift or vertical stripes may be generated. This should be correctable by
the on screen menu.
Phase: If the phase of the display data and dot clock
are not correctly tuned the screen can flicker, or text be displayed
blurry. For example text may appear dithered, or when looking at a test
pattern of a one-pixel black, one-pixel white checkerboard pattern the
pattern may be distorted. This should be correctable by the on screen
screen. Vertical stripes.
Response Time: We look for any streaking associated
with moving a full page of text up or down quickly. Displays with slower
refresh rates tend to show some degree of image streaking or text
discoloration which can be distracting.
Stand Stability: TFT displays are fragile components and the
stand should offer adequately stable support as well as be easily
|Text dithering effect
by either phase adjustment problems, or lower than optimal
||Sharp text is
displayed with monitor on best resolution
We deduct marks for quality control if there are any predominant
broken pixels in a display. While many manufacturers may consider a
few broken pixels acceptable, we believe the high cost of TFT displays
should translate into a clear and unblemished