Electro-Optical Devices from Banana-Shaped Liquid Crystals

KSU.216

Abstract: This invention offers a display that can be switched between scattering and clear states c. 100 times faster than PDLCs with principally 180 degree viewing angle.  In addition, the switching modes – from opaque to clear and clear to opaque - can be interchanged in less than a second.  After changeover, both the opaque and clear states can be stable at zero fields.  The work of the device in reflection mode was also demonstrated.  This invention encompasses a liquid crystal device comprising tilted smectic phases of banana-shaped (bent-core) liquid crystal molecules and a method for fabricating a light modulating device. The method comprises the steps of providing a pair of substrates with a cell gap between and permanently disposing at least one banana-shaped liquid crystal material into the cell gap. The present invention also provides a method of generating an image by providing  a pair of substrates with a cell gap, providing transparent electrodes on each of the substrates adjacent to the cell gap, disposing at least one banana-shaped liquid crystal material into the cell gap, and applying an electric field across the electrodes. The tilted smectic phases of banana-shaped liquid crystal may be in either a racemic or a chiral state. The application of an electric field transitions the banana-shaped liquid crystal material between the racemic and chiral states, and both the racemic and the chiral states are stable in the absence of an electric field.

Applications:

Useful wherever PDLCs speed and viewing angle is not enough, for versatile optical devices both in transmission or reflection mode, where both video-rate applications and optical storage capabilities are required.  Examples include cell phones, personal computers, electronic books, and in light shutters that use energy only during switchover between modes.

Advantages:

Versatility, faster switching speed, greater viewing angle, and no backlighting required.

Inventors:  Drs. Antal Jakli, Dr. Liang-Chy Chien, D. Kruerke, S. Sawade, & G. Heppke