Methods of compensating liquid crystal displays using DC balancing

• US 6,771,339 B2
• Filed: 10/19/2001
• Issued: 08/03/2004
• Est. Priority Date: 12/27/1996
• Status: Expired due to Fees

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Huang, Austin L., Knox, Richard M.
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US10/006,737
• Publication Number:
  US 20020039158A1
• Time in Patent Office: 1,019 Days
• Field of Search: 345/97, 349/117, 349/98, 349/75, 349/74, 349/77, 349/81
• US Class Current: 349/117
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/141 using ferroelectric liquid crystals
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable

Abstract

In a reflective mode FLC application, a ¼-wave plate compensating FLC is used in series with a ¼-wave imaging FLC to compensate for the effects of DC balancing. Alternatively, the compensating wave plate could be any odd ¼-wave multiple, such as 3λ/4, 5λ/4, etc. The FLCs are driven in synchronization between on and off states with the total effective retardation for each FLC being either none or one-half wavelength in a double pass.

Claims

1. A method of compensating in an optical system comprising:

retarding polarized light using a quarter-wave compensator in an on-state responsive to a first state of a DC balancing signal to provide retarded light and avoiding retarding the polarized light using the quarter-wave compensator in an off-state responsive to a second state of the DC balancing signal, that is opposite the first state;

imparting information on the retarded polarized light using a quarter-wave imager in an on-state responsive to the first state of the DC balancing signal to provide imaged retarded polarized light and avoiding imparting information on the retarded polarized light using the quarter-wave compensator in an off-state responsive to the second state of the DC balancing signal;

reflecting the imaged retarded polarized light back toward the quarter-wave compensator and the quarter-wave imager to provide reflected and retarded polarized light; and

further retarding the reflected and retarded polarized light using the quarter-wave compensator and the quarter-wave imager.

2. The method of claim 1, further comprising:

providing polarized light by reflecting light off of a polarized reflector.

3. The method of claim 1, wherein further retarding comprises providing an output light, the method further comprising transmitting the output light through a polarizing reflector.

4. The method of claim 1, wherein retarding the polarized light comprises retarding by an odd multiple of one-quarter of the wavelength of the polarized light.

5. The method of claim 1 wherein retarding and further retarding comprise retarding and further retarding within the same device.