The
Field Emission Display(thin CRTs) are a relatively new
display type. It has a
image contrast equal to a normal
CRT but has a
thickness of under 1cm.
Unlike the normal CRT the FED have
electron emitters for
every
phosphor dot. This means that there is no need for
a
deflection system thus that the long 'neck' and the
curves of the normal CRT isn't needed. Also, the
electron cannons can be replaced by an
array
of small
electron emitters.
The basic buildup of a FE cell:
top
emitter Phosphor
layer dot
| |
B | : |_| | |
a |-: *| | F
s |-: F *| | a
e |-: o g *| | c
|-: c r *| | e
l |-: u i *| | p
a |-: s d *| | l
y |-: i *| | a
e |-: g *| | t
r |-: _ *| | e
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Emission
spikes
A FE display consists of one cell like this for each phosphor dot
(3 dots per
pixel). The base
layers of the cells on the same
row,
is connected together. The top emitter layer are connected in
columns. This makes a column/row system so each dot can be
individually
addressed. To light the phosphor in one cell you address
connect
voltages to the
appropriate row and to the column. This makes the
emission spikes send out electrons. Since each cell has many spikes(often
more than 3000), the 'wear' on one individual
spike is
minimal.
The focusing grid's
electric field collimates the flow of
electrons so that they only hit the correct dot.
This form of display have a higher
brightness and
contrast
than the
Active Matrix LCD(TFT display), but needs an
accelerating voltage. But unlike the CRT, that may have 15kV to 25kV,
it needs only 500V-1kV.
Due to its
compact size and lower
voltages than
CRTs, and lower weight than
plasma displays
it has the
potential to become an important technology
in future
computer screens. But due to the need for
vaccum
inside the
display, it has proven to be hard to make
a FED larger than 10" that doesn't have a high
danger of self
implosion.