Overview
Some of the research projects, OCB LCD and controlling LC alignment, conducted by the Display Technology group to develop better technologies for thin-film transistor LCDs (TFT-LCDs) are described below.
Photochemistry of LC alignment film
It is very important how to control the liquid crystal (LC) alignment in LCDs, and physical treatment of organic film coated on the glass substrate is commonly being used.
As we have succeeded in obtaining the same effect only by optical treatment using UV light, we are currently studying the photochemical reaction mechanism of its effect.
Recently, we determined that oxygen plays important role in photochemical reaction of LC alignment film, and that it greatly affects on the tilt angle of LC by changing the atmosphere of UV exposure treatment (Figure 1).
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| Figure 1 The dependence of pretilt angle of LC on UV exposure energy in the presence of chemicals. |
OCB LCD
Although many types of liquid crystal displays (LCDs) are currently available in the market, the viewing angles of displays are not wide enough. In order to solve this problem, intensive studies are on going in many institute, making use of novel mode of liquid crystal alignments.
| type | pixel addressing | alignment mode |
| TFT type | active matrix | twist |
| STN type | simple matrix | super twist |
| OCB type | active matrix | bend |
OCB-LCD has the following features:
- Wide viewing angle.
- Fast response suitable for displaying movies.
As a result, the display is very clear from top to bottom.
We developed the important technique to realize bend mode alignment
of liquid crystals and contributed to the development of OCB-LCD.
Publications
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