Ferroelectric liquid crystal devices using materials with a de Vries smectic A phase

• US 6,870,163 B1
• Filed: 09/01/2000
• Issued: 03/22/2005
• Est. Priority Date: 09/01/1999
• Status: Expired due to Fees

• Current Assignee: David M. Walba
• Original Assignee: DT FLCO, Inc. (Micron Technology, Inc.)
• Inventors: Xue, Jiuzhi, Walba, David M.
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US09/653,437
• Time in Patent Office: 1,663 Days
• Field of Search: 250/341.1
• US Class Current: 250/341.1
• CPC Class Codes: C09K 19/02 characterised by optical, electrical or physical properties of the components, in general
• CPC Class Codes: C09K 19/0266 Antiferroelectrics
• CPC Class Codes: G01N 21/19 Dichroism
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor

Abstract

Bistable and analog FLC devices employing chiral nonracemic liquid crystal materials exhibiting de Vries smectic A phases. The invention provides certain liquid crystal material that can be employed in both bistable and analog device configurations. The invention also provides a method for identifying liquid crystal materials that will exhibit both bookshelf structure in SSFLC cells and provide V-shaped switching in an analog device configuration.

Claims

1. A method for identifying a chiral nonracemic liquid crystal material useful in both bistable SSFLC devices and analog devices comprising determining the presence of a deVries smectic A phase in a chiral nonracemic liquid crystal, the presence of the phase being indicative of that the material will exhibit bookshelf geometry and V-shaped switching when introduced into the appropriate FLC device configurations, wherein infrared dichroism measurements are made to determine the presence of the de Vries smectic A phase.

2. The method of claim 1 wherein the chiral nonracemic liquid crystal material is a V-shaped switching material.

3. The method of claim 1 wherein the chiral nonracemic liquid crystal material is an antiferroelectic liquid crystal material.

4. The method of claim 1 wherein the chiral nonracemic liquid crystal material comprises a swallow-tailed liquid crystal.

5. The method of claim 1 wherein the chiral nonracemic liquid crystal material comprises a liquid crystal dimer.

6. The method of claim 5 wherein the dimer comprises a siloxane group.

7. The method of claim 1 wherein the chiral nonracemic liquid crystal material exhibits a tilted smectic phase.

8. The method of claim 7 wherein the chiral nonracemic liquid crystal material exhibits the phase sequence 1→

SmA→

SmC* and the smectic A phase is a de Vries smectic A phase over a useful portion of the SmA phase.

9. The method of claim 1 wherein the chiral nonracemic liquid crystal material exhibits a chiral smectic C phase.