REV.-A
Optical
contrast
of
the liquid crystal is produced in
the
mechanism
as
follows:.
First,
only
the
light
elements
which
oscillate in a specific
direction
are
transmitted
through
the
upper
polarizer
plate
onto
the
liquid crystal. The light, arriving on
the
liquid crystal, is affected,
depending
on
whether
an electric field is applied
or
not:
<
When
no
electric field is
applied>
The penetrating
light
is polarized
by
90
0
• This causes
the
oscillation
direction
of
the
light
to
coin-
cide
with
the
polarization
direction
of
the
polalrilzer plate and
the
light
is
transmitted
through
it.
Then,
the
light
strikes
the
bottom
reflector plate and is reflected, so
that
the
panel looks
light
(white).
<
When
an
electric field is
applied>
The
twisted
orientation
of
the
liquid crystal is corrected
by
the electric field and
the
optical
activity
is removed. The oscillation
direction
of
the
light
penetrating
the liquid crystal layer does
not
coincide
with
the
polarization
direction
of
the
lower
polarizer plate and is
shut
off
by
it. suits in no
reflection
from
the
bottom
reflector plate so
that
the
panel looks
dark
(black).
The reaction
to
the
electric field varies depending on temperature.
To
compensate
this, a variable
resistor, called
VIEW
ANGLE is provided in
the
voltage source circuit.
• Display
dot
(segment)
Each display
dot
has
an
area
of
0.45
(high) x
0.41 (wide)
mm
2
•
These
dots
are laid
out
at a
vertical
pitch
of
0.5
mm
and
at
a horizontal
pitch
of
0.46
mm
as
shown
in Fig.
2-76.
Notes:
046
0.41
D
9
~
()1
o
()1
(Unit:
mm)
Fig.
2-76
Display
Dot
Dimensions
And
Layout
As
described above, variation
of
liquid crystal reaction can be compensated
for
by
adjusting
the
X-V
drive line signal voltage
with
the
sliding
type
variable resistor
VIEW
ANGLE
over
a certain
temperature range.
If
the range is exceeded, however,
this
compensation
is
no
longer
possible,
and
the
LCD panel may
exhibit
one
of
the
following
problems:
<
Lower
temperature>
• Liquid crystal reaction is
slow
and a
long
time
is required until selected
dots
become visible (up
to
several seconds
may
be required)
•
When
the
temperature
further
falls,
no
selected
dots
are visible over
the
entire panel.
< Higher
temperature>
• The entire area
of
the
panel looks
dark
(black) and selected
dots
are
not
easily recognizable.
2-75
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