LIQUID CRYSTAL DISPLAY ASSEMBLY HAVING INDEPENDENT CONTRAST AND SPEED OF RESPONSE CONTROLS

• US 3,655,269 A
• Filed: 01/25/1971
• Issued: 04/11/1972
• Est. Priority Date: 01/25/1971
• Status: Expired due to Term

• Current Assignee: George H. Heilmeier
• Original Assignee: George H. Heilmeier
• Inventors: Heilmeier, George H.
• Primary Examiner(s): Yusko, Donald J.
• Application Number:
  US05/109,688
• Time in Patent Office: 442 Days
• Field of Search: 340/166,324 178/7.5,7.3 350/160
• US Class Current: 349/177
• CPC Class Codes: G02F 1/1375 using dynamic scattering

Abstract

A liquid crystal display assembly offering control of the speed of response of the exhibited electro-optical effect by varying the amplitude of the applied energizing signal and further offering independent control of the contrast by varying the frequency of that signal above a predetermined value.

Claims

1. A liquid crystal display assembly comprising a layer of nematic liquid crystal material and means for applying an electrical signal of predetermined amplitude and frequency to said crystal material, said predetermined amplitude being selected to establish the speed of response of the dynamic light scattering electro-optical effect exhibited thereby, and said predetermined frequency being selected above a threshold to independently control the contrast of the resulting display by controlling the motion and turbidity of ions within said nematic material to provide a modification of said dynamic light scattering effect.

2. The liquid crystal display assembly as described in claim 1 wherein means are included for supporting said liquid crystal layer comprising essentially parallel support plates between which said layer is contained, at least one of said support plates being transparent and having a transparent conductive coating on at least one side thereof, and wherein said means for applying said electrical signal of predetermined amplitude and frequency to said crystal material includes said transparent conductive coating.

3. The liquid crystal display assembly as described in claim 1 wherein said independent control over the contrast is initiated at a signal frequency which is dependent upon the amplitude of the applied electrical signal which establishes said speed of response.

4. The liquid crystal display assembly as described in claim 3 wherein said signal frequency at which independent control over the contrast of the exhIbited electro-optical effect is initiated is also dependent upon the resistivity of the nematic liquid crystal material.

5. The liquid crystal display assembly as described in claim 3 wherein said signal frequency at which independent control over the contrast of the exhibited electro-optical effect is initiated is also dependent upon the thickness of the nematic liquid crystal material.