Charles E Allison

US Patent:

49385682, Jul 3, 1990

Filed:

Jan 5, 1988

Appl. No.:

7/141033

Inventors:

John D. Margerum - Woodland Hills CA
Anna M. Lackner - Los Angeles CA
Elena Ramos - Santa Monica CA
George W. Smith - Birmingham MI
Nuno A. Vaz - West Bloomfield MI
James L. Kohler - Kokomo IN
Charles R. Allison - Flint MI

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

G02F 113
B01J 1302

US Classification:

350334

Abstract:

A method of forming a polymer dispersed liquid crystal (PDLC) film is disclosed which consists of forming a solution of LC dissolved in a monomer, photopolymerizing the solution to form a film having a dispersion of LC bubbles therein, establishing a correlation between the LC bubble size and selected characteristics of the film, selecting a LC bubble size corresponding to desired film characteristics, and controlling the conditions of photopolymerization to achieve said LC bubble size. The LC bubble size is controlled by means of the UV exposure intensity, exposure temperature, exposure wavelength, LC concentration and/or concentration of polymerization initiator. Correlations are noted between LC bubble size and the resulting film's threshold and operating voltages for optical transmission, contrast ratio, absolute transmissivity and electro-optical response times. Special types of films, including in situ gratings and holograms, are obtained by periodically varying the conditions of polymerization over the film to produce a corresponding periodic spatial variation in the LC bubble size; different processes used to achieve this result are noted. Films with LC bubbles in a new size regime that significantly decreases the operating voltage threshold, and with gradients in the bubble size, are also disclosed.

US Patent:

50962825, Mar 17, 1992

Filed:

Mar 23, 1990

Appl. No.:

7/498076

Inventors:

John D. Margerum - Woodland Hills CA
Anna M. Lackner - Los Angeles CA
Elena Ramos - Santa Monica CA
George W. Smith - Birmingham MI
Nuno Yaz - Bloomfield MI
James L. Kohler - Kokomo IN
Charles R. Allison - Flint MI

Assignee:

Hughes Aircraft Co. - Los Angeles CA
General Motors Corporation - Detroit MI
Delco Electronics Corporation - Kokomo IN

International Classification:

G02F 1133

US Classification:

359 3

Abstract:

A method of forming a polymer dispersed liquid crystal (PDLC) film is disclosed which consists of forming a solution of LC dissolved in a monomer, photopolymerizing the solution to form a film having a dispersion of LC bubbles therein, establishing a correlation between the LC bubble size and selected characteristics of the film, selecting a LC bubble size corresponding to desired film characteristics, and controlling the conditions of photopolymerization to achieve said LC bubble size. The LC bubble size is controlled by means of the UV exposure intensity, exposure temperature, exposure wavelength, LC concentration and/or concentration of polymerization initiator. Correlations are noted between LC bubble size and the resulting film's threshold and operating voltages for optical transmission, contrast ratio, absolute transmissivity and electro-optical response times. Special types of films, including in situ gratings and holograms, are obtained by periodically varying the conditions of polymerization over the film to produce a corresponding periodic spatial variation in the LC bubble size; different processes used to achieve this result are noted. Films with LC bubbles in a new size regime that significantly decreases the operating voltage threshold, and with gradients in the bubble size, are also disclosed.