Liquid crystal optical device

• US 5,844,651 A
• Filed: 10/11/1996
• Issued: 12/01/1998
• Est. Priority Date: 10/13/1995
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Reimer, Dirk, Fukushima, Akiyuki, Matsui, Eriko, Yasuda, Akio, Yoshizawa, Atsushi
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGO, HUYEN LE
• Application Number:
  US08/728,918
• Time in Patent Office: 781 Days
• Field of Search: 252/299.01, 349/134, 349/171, 349/172, 349/184, 349/33
• US Class Current: 349/134
• CPC Class Codes: C09K 19/0225 Ferroelectric
• CPC Class Codes: G02F 1/141 using ferroelectric liquid crystals

Abstract

An object of the present invention is to provide a liquid crystal display device such as an FLC display which is significantly reduced for the temperature dependence of the liquid crystal properties. A liquid crystal optical device 31 in which a plurality of transparent substrates 2a, 2b are opposed to each other at a predetermined gap 32, with transparent electrodes 3a, 3b and liquid crystal alignment films 4a, 4b being disposed, respectively, to the opposing surfaces and ferroelectric liquid crystal (FLC) 30 is disposed in the gap 32, wherein the ferroelectric liquid crystal 30 has a layer texture 30A, and the change of the layer tilt angle is less than 3° within an entire temperature range in the smectic C* phase. An atom group substituted and introduced with a fluorine atom is bonded to a chiral molecular skeleton of a ferro electric liquid crystal molecule, and the atom group substituted and introduced with a fluorine atom has a fluorinated phenylene ring, wherein said liquid crystal material has a uniform texture achieved by applying rectangular electric pulses while slowly cooling from an isotropic phase to a low temperature smectic A phase, followed by application of bipolar electric pulses while cooling to room temperature.

Claims

1. A liquid crystal optical device in which a plurality of substrates are opposed to each other at a predetermined gap with electrodes and liquid crystal alignment films being disposed, respectively, on the opposed surfaces, and a liquid crystal material is disposed in said gap, wherein said liquid crystal material has a layered structure, and the change of the layer tilt angle is greater than 0°

and less than 3°

in an entire temperature range of a smectic C* phase, wherein an atom group substituted and introduced with a fluorine atom is bonded to a chiral molecular skeleton of a ferro electric liquid crystal molecule, and wherein the atom group substituted and introduced with a fluorine atom has a fluorinated phenylene ring, wherein said liquid crystal material has a uniform texture achieved by applying rectangular electric pulses while slowly cooling from an isotropic phase to a low temperature smectic A phase, followed by application of bipolar electric pulses while cooling to room temperature.

2. A liquid crystal optical device as defined in claim 1, wherein the liquid crystal material has a plurality of layer textures, and the change of the layer spacing is less than 2Å

in an entire temperature range of the smectic C* phase.

3. A liquid crystal optical device as defined in claim 1, wherein the liquid crystal material forms the smectic C* phase at least within a temperature range from -5°

C. to 57°

C.

4. A liquid crystal optical device as defined in claim 1, wherein the layer tilt angle is more than 20°

in the smectic A phase.

5. A liquid crystal optical device as claimed in claim 1, wherein said layer tilt angle is in a range of 2°

-3°

.

6. A liquid crystal optical device as defined in claim 1, wherein the layer texture of the liquid crystal material is a tilted bookshelf texture.

7. A liquid crystal optical device as claimed in claim 1, wherein the liquid crystal material includes 2,3-difluoro-substituted phenyl-pyrimidine.

8. A liquid crystal optical device as claimed in claim 1, wherein said rectangular electric pulses are of an amplitude of approximately 30 volts and a frequency of approximately 100 hertz and are applied while cooling from an isotropic phase to a smectic A phase.

9. A liquid crystal optical device as claimed in claim 1, wherein said bipolar electric pulses are of an amplitude of approximately 30 volts and a duration of approximately 250 microseconds and duty cycle of approximately 10 microseconds.

10. A liquid crystal optical device in which a plurality of substrates are opposed to each other at a predetermined gap with electrodes and liquid crystal alignment films being disposed, respectively, on the opposed surfaces, and a liquid crystal material is disposed in said gap, wherein said liquid crystal material has a layered structure, and the change of the layer tilt angle is greater than 0°

and less than 3°

in an entire temperature range of a smectic C* phase, wherein the layered tilt angle is more than 20°

in the smectic A phase, wherein the electroclinic angle of the liquid crystal material is more than 5°

at a smectic A phase to smectic C phase transition temperature (TAC)+0.5°

K. and at an electric field of 20 V/μ

m, the electroclinic angle of the liquid crystal material is more than 2.5°

at a smectic A phase to smectic C phase transition temperature (TAC)+2°

K. and at an electric field of 20 V/μ

m, and an electroclinic effect is provided in a tilted smectic A phase.