AIt is the uniformity with which liquid crystal
molecules are arranged that determines thequality of images

ligning

Slim, beautiful and ecologically-friendly.
The proliferation of mobile terminals such as Smartphones has beenaccompanied by increasing evolution of liquid crystal displays.
The increased performance of such displays is backed up by Ushio’s
photo-alignment technology for uniformly arranging liquid crystal molecules.

Liquid crystal displays express image movement, colors and shades
by applying voltage to liquid crystal molecules to move them in a
shutter-like manner, controlling the amount of light that passes through from the display’s backlight.
Accordingly, improvement in the quality and speed of images depends on the freedom with which
liquid crystal molecules can be moved, which is what makes it so important that the molecules beregularly aligned.

External appearance of photoalignment system and the lamps
used for photo-alignment

However, in practice this is not so easy to achieve. As with crystals, liquid crystal molecules have atendency to clump together, so they fall into disarray if left to themselves. The important process ofarranging liquid crystal molecules so that they are correctly positioned into the proper orientation isachieved through photo-alignment.

Various types of alignment
Conventionally, liquid crystal molecules are aligned by rubbing them with cloth to orient themwithin grooves as shown in Figure 1. However, this method is not only problematic from an ecologicaland economic perspective, but in terms of other problems such as darker images and reducedcontrast.
These problems are all solved by Ushio’s optical alignment technology. Exploiting their tendency tochange arrangement under the influence of an electromagnetic field, Ushio has succeeded inarranging liquid crystal molecules by irradiation with special light, a method that does not rely on
direct rubbing or use of alignment structures. This non-contact method of alignment not only
increases production yield by reducing dust and static electricity, but also reduces cost by eliminating
the need for alignment structures. Furthermore, it improves contrast and allows greatly reduced
power consumption by improving backlight transmissivity (Figure 3).
The display of that Smartphone you are using may have been produced using Ushio’s
photoalignment technology.

“Aligning with light” The Mechanism
Fig. 1 Direct rubbing with cloth and alignment in grooves (rubbing method)+‒

Static electricity

0.01μm0.1μm

Yield suffers due to fine dust (particles) and generationof static electricity. The special cloth used for rubbing is
not only expensive, but must be frequently replaced,
increasing production cost and lead time.

Alignment film
Dust

Liquid crystal molecules

Fig. 2 Liquid crystal molecules are aligned with a structural pattern
Reduced light transmissivity

Alignment film
Glass substrate

Backlight
Structural pattern for alignmentof liquid crystal molecules

Structural pattern used for liquid
crystal alignment impedes lighttransmission, making images darker
a n d r e d u c i n g i m a g e q u a l i t y.
Increasing the brightness requires alarger backlight, which increases
display size. This method also leaves
irregularities in liquid crystal orderingand angle, reducing response speed.

Fig. 3 Ushio’s optical alignment technology
Increased light transmission

Alignment film
Glass substrate

Backlight

Liquid crystal molecules regularlyaligned in one direction without
structural patterns by means ofirradiation with special light.
Improved light transmission reduces
power requirements and achieves
greater alignment regularity for
improved contrast.