Sony XEL-1 Operating Instructions Manual page 7

the drive circuits and wires are present on the
TFT substrate, the area from which light can
be extracted is limited. In top emission, on the
other hand, light is extracted from the opposite
side of the TFT substrate. Because there are
almost no obstacles, the light can be extracted
efficiently. Sony's OLED displays use the top
emission method, ensuring high brightness and
superb picture quality.
Cathode
Transparent
anode
Bottom emission method
Semitransparent
cathode
Organic
layer
Anode
Top emission method
Figure 2
Vividness
Enjoy colourful pictures of gardens full of
spring flowers and gorges bathed in vibrant
autumn colours.
Colours are reproduced using the red, green
and blue organic layers. The film thickness is
selected to match the wavelength for each
colour (see Figure 3).
The light emitted in the organic layer is
reflected back and forth between the anode
and the cathode. Only light whose wavelength
matches the thickness of the film interferes,
increasing in strength (see Figure 4). As the
light of other superfluous wavelengths
Organic
layer
TFT
TFT
decreases, the colour purity of the light passing
through the semitransparent cathode increases.
As a result, each colour is vividly and clearly
reproduced. The colour purity is further
enhanced by passing the light through a colour
filter.
The self-luminous nature of the OLED display
not only generates the full colour spectrum of
bright images, but delivers vivid colour
reproduction capability at nearly all brightness
levels to produce stunning pictures (see Figure
5).
Polarising film used to be the common method
of preventing reflection of ambient light. The
use of such polarising film, however, causes a
reduction in brightness that would
compromise the properties of the OLED
display. The use of colour filters, on the other
hand, prevent reflection of ambient light and
lessen its effects while enabling the image to
be reproduced in its essential colours.
In addition to the high brightness and high
efficiency of the top emission method, by
selecting the film thickness to match the
wavelength of the light and using colour
filters, Sony has succeeded in producing
brighter, more colourful images. This unique
system of Sony's is called "Super Top
Emission".
red green blue
Figure 3
Figure 4
Glass substrate
Colour filter
Semitransparent
cathode
Organic layer
Anode
TFT
Glass substrate
Glass substrate
Semitransparent
cathode
Organic layer
Anode
Glass substrate
7
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