The Mechanism Of Controlling Light - Sony LUMA Product Information Manual

6
A deeper look into LCDs

-The mechanism of controlling light

As explained above, the Liquid Crystal molecules
in contact with the two alignment films align
themselves with the filter grooves and, therefore,
are at a 90-degree angle. The molecules in-
between rotate in directions such that the
molecules from top to bottom of the Liquid Crystal
form a twisted chain.
This twisted chain is the normal orientation of the
molecules when voltage is not applied. In this
orientation, the light wave that passes the first
polarized filter is twisted along the twist of the
molecule chain, and therefore passes the second
polarized filter. Because light passes when
Polarized
panel
Alignment
film
Alignment
film
Polarized
panel
Figure 6-5.
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Product Information Manual Sony Professional LCD Monitors
OFF
Light
voltage is not applied, this mode is called
'normally white'.
When voltage is applied, the molecules gradually
untwist and stand vertical. When they stand
completely vertical, the light entering the first
polarized filter will no longer be twisted (by the
molecules) and its vibration plane will no longer
match the second filter. Needless to say, this light
will be blocked at the second filter and will not go
to the other side of the LCD device. The amount
of light that passes can be linearly controlled
depending on the voltage applied, i.e., how much
the molecule chain is untwisted or how vertical the
molecules stand.
ON
Polarized
panel
Alignment
film
Alignment
film
Polarized
panel
Direction of light vibration
Liquid Crystal Molecules
Light