Browse Prior Art Database

CONTACTLESS ADDRESSABLE LIQUID CRYSTAL DISPLAY

IP.com Disclosure Number: IPCOM000023659D
Original Publication Date: 1978-Oct-31
Included in the Prior Art Database: 2004-Mar-31
Document File: 2 page(s) / 273K

Publishing Venue

Xerox Disclosure Journal

Abstract

The contactless, addressable liquid crystal display is con-structed by depositing an interdigital transducer 1 on the upper face of a piezoelectric substrate 2 (for example, lithium niobate, YZ cut) while the lower face is metalized 3 and electrically grounded. A high resistivity, room temper-ature, liquid crystal thin film 4 is deposited on substrate 2. A bulk n-type semiconductor 5 with a thin oxidized surface 6 is placed on top of the film 4, and a metallic-coated 7 glass slide 8 covers the semiconductor. The interdigitated trans-ducer 1 is driven by amplifier 10 and conductive coating 7 is separately driven by amplifier 9.

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XEROX DISCLOSURE JOURNAL

CONTACTLESS ADDRESSABLE LIQUID Proposed Classification
CRYSTAL DISPLAY U.S. Cl. 350/160 LC
Dror Sand Int. Cl. G02b 5/23

2

The contactless, addressable liquid crystal display is con-
structed by depositing an interdigital transducer 1 on the
upper face of a piezoelectric substrate 2 (for example,
lithium niobate, YZ cut) while the lower face is metalized 3
and electrically grounded. A high resistivity, room temper-
ature, liquid crystal thin film 4 is deposited on substrate 2.
A bulk n-type semiconductor 5 with a thin oxidized surface 6
is placed on top of the film 4, and a metallic-coated 7 glass
slide 8 covers the semiconductor. The interdigitated trans-
ducer 1 is driven by amplifier 10 and conductive coating 7 is
separately driven by amplifier 9.

In operation, the interdigital transducer 1 is excited by a
short pulse which is converted into two surface acoustic waves
propagating in opposite directions. The insertion loss can be
made quite small. The acoustic surface wave is accompanied by
an evanescent electric field due to the piezoelectric prop-
erties of the substrate 2. The electric field penetrates
through liquid crystal film 4 into the semiconducting
material. When the traveling acoustic pulse reaches the
middle of substrate 2, a short electric pulse is applied to
conducting film 7 on top of semiconductor 5. From the time
when this electric pulse is turned on until a fraction of a
second later, a D.C. electric field will persist in an area
the dimension...