|Size & Type
active matrix TFT|
||350:1 (typical) |
||200 nit (typical) |
|Prime and Max.
||1024 x 768 @ 75
||304.1mm x 228.1mm|
||31.5 - 60 kHz|
56 - 75
||Analog RGB Interface 15-pin D-sub|
||Video 0.7 Vp-p 75 ohm. Synchronized TTL level
separate composite sync.|
|Video clock frequency
||79 MHz |
||Approx 35W, 5W in standby|
differ from their CRT relatives on many fundamental levels. When comparing the
two, there are a few pointers that are
important to consider. Where CRT displays are typically judged by their
dot pitch, LCD panels have several alternate points which relate to the
quality of a display. The points to watch out for are contrast
ratio, luminance (brightness), and viewing angle.
Looking at contrast ratio first, the
larger the ratio, the better the display panel. The measurement is generally taken
on the differences between black and white levels. For example, a ratio of 1:1 contrast
would conceptually equate to a solid gray screen. From our experiences anything at, or
above a 200:1 contrast ratio is quite good. The CML151XW has a contrast
ratio of 350:1 which puts it at the top of its class.
Brightness is measured in cd/m2 or nits and is important
when comparing TFT display's. If the display is not very bright, the white
background colours can often seem pinkish, or dull when compared side to side
with a CRT or other LCD panel. The panel used in the CML151XW has a brightness
of 200 cd/m2 which is pretty much the norm from what we have been seeing
lately. To give that value some scale, the highest brightness rating typically
sits around 250cd/m2, and the lowest around 150cd/m2. Overall there is a
lot less variance in brightness then there is with contrast.
Lastly, there are the
viewing angles. Viewing angles are measured
perpendicular to the face of the display. The larger the viewing angles in
the up, down, left, and right direction, the better the display. For example the
Hitachi CML151XW has a viewing angle of 45 degrees up, and 55 degrees down. That
means we can view the display from an angle of around 45 degrees (say if we're
standing up and looking down at the display) before the quality of the picture will
be effected. Generally the effect can be described as the display 'grey's
over' - colours are muted, and the entire display takes on a grayish/opaque appearance.
The best viewing angles are typically 80/80/80/80 (up/down/left/right).