Polymer dispersed liquid crystal film devices, and method of forming the same
First Claim
1. A method of controlling the electro-optical properties of a polymer dispersed liquid crystal (LC) film, comprising:
- forming a solution of a LC dissolved in a polymerizable monomer system,photopolymerizing said solution to form a polymerized film having a dispersion of LC bubbles therein, andspatially varying the conditions of polymerization over said film to spatially vary the sizes of said LC bubbles therein.
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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.
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Citations
9 Claims
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1. A method of controlling the electro-optical properties of a polymer dispersed liquid crystal (LC) film, comprising:
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forming a solution of a LC dissolved in a polymerizable monomer system, photopolymerizing said solution to form a polymerized film having a dispersion of LC bubbles therein, and spatially varying the conditions of polymerization over said film to spatially vary the sizes of said LC bubbles therein. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification