Polymer dispersed liquid crystal film devices, and method of forming the same
US4938568A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 5, 1988 |
| Grant date | Jul 3, 1990 |
| Priority date | — |
| Expiry date | Jan 5, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
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 siz…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.