Specifications

Sharpness
In a CRT, the energy from the electron beam hitting the phosphors creates light,
which fades after the beam sweeps to other parts of the screen. The sharpness of a
CRT is determined by the size of the area excited by the electron beam. To minimize
the apparent flicker of the phosphor being excited and fading, a good CRT monitor
updates each part of the screen at an extremely fast rate—75 times a second or more.
However, at those speeds it’s difficult to control the spot size of the electron beam and
therefore to create a sharp transition between black and white areas. So a high refresh
rate and a sharp image are difficult to implement simultaneously at high resolutions.
A digital active-matrix display isn’t subject to the physical limitations of an electron
beam being swept across the screen. Each pixel is physically separated from the
others and has an electronic switch that is turned on or off independently. A black
pixel can be adjacent to a white pixel with no difficulty. The result is an incredibly
sharp display.
Lack of flicker
It is widely accepted that watching a flickering monitor for an extended period can
cause eyestrain and associated headaches. Modern CRT displays with high refresh
rates have minimized flickering in their images. LCDs, however, offer an inherent
advantage in this regard: They have no electron beam rapidly “painting” an image on
the screen line by line. Each and every pixel on an LCD is simply turned on and off
independently whenever needed.
Ideal for Wide-Format Designs
Another advantage of LCD displays is based on simple geometry. In a CRT monitor,
the electron beam emanates from the center of the cathode-ray tube, so at the edges
of the screen, it hits the phosphors at a noticeable angle, rather than straight on. The
beam’s footprint becomes oval rather than circular, causing inevitable clarity problems
at the edges of the CRT screen. This problem is even more dramatic in wide-format
CRTs, because the electron beam must be deflected at an even greater angle to reach
the edges and corners.
LCDs, by comparison, have no beam hitting the screen edges at an angle, and there-
fore no geometry problems. The pixels at the edge of an LCD are as crisp as the ones
in the center. Because of this, LCD displays are better devices for wide-aspect-ratio
designs. Creative content—two-page spreads, multiple web pages, video timelines,
and cinematic content—is often wider than it is tall, making an LCD better suited to
support many creative applications.
10
Technology Overview
Apple Cinema Displays