Light-modulation element and production method thereof

• US 6,215,535 B1
• Filed: 10/16/1997
• Issued: 04/10/2001
• Est. Priority Date: 08/11/1992
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mochizuki, Hideaki, Nakajima, Junji, Wakemoto, Hirofumi, Yamamoto, Masao
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Ngo, Julie
• Application Number:
  US08/951,737
• Time in Patent Office: 1,272 Days
• Field of Search: 359/51, 359/52, 252/299.1, 252/299.01, 252/299.5, 349/86, 349/89
• US Class Current: 349/86
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals

Abstract

The present invention provides a light-modulation element comprising at least: liquid crystal droplets having a particle size between 0.6 μm-2 μm, which have light-modulating functions to scatter light rays or transmit light rays and polymer matrix having an interstructure thickness of 0.5 μm or less between the liquid crystal droplets. The light-modulation element works to scatter light rays or transmit light rays by turning on a voltage or turning off a voltage. The light-modulation element is produced by a polymerization process and a mixing step to separate out liquid crystal phases in a polymer matrix.

Claims

1. A light-modulation element comprising:

a pair of electrodes facing each other, one of the electrodes being transparent and

a light-modulating layer between the pair of electrodes, comprising liquid crystal droplets of fluorine series existing separately from each other and a polymer matrix keeping the liquid crystal droplets, and wherein the liquid crystal droplets are contained in amount of about 81 to 90% by weight,

a mean particle size of liquid crystal droplets being within the range between 0.6-2 μ

m and an interstructure mean thickness of the polymer matrix between the liquid crystal droplets being 0.1-0.5 μ

m or less.

4. The light-modulation element of any one of claims 1, 2 and 3 which at least a part of the liquid crystal droplets have not circular shapes but distorted shapes.

5. The light-modulation element of any one of claim 1, 2 and 3, in which the polymeric matrix is formed from photopolymerizable materials.

6. The light-modulation element of any one of claims 1, 2 and 3, in which the polymer matrix is formed from a photopolymerizable material comprising at least benzyl dimethyl ketal.

7. The light-modulation element of any one of claims 1, 2 and 3, in which the polymer matrix is formed from a photopolymerizable material comprising at least 2-ethylhexyl acrylate.

2. A light-modulation element comprising a light-modulating layer of composed fluorine series liquid crystal droplets and a polymer matrix, in which the volume content of the liquid crystal droplets is about 81 to 90% by weight.

3. A light-modulation element comprising a light-modulating layer composed of fluorine series liquid crystal droplets and a polymer matrix, in which the volume content of the liquid crystal droplets having a mean particle size of 0.6 μ

m to 2 μ

m after the polymer matrix is hardened is about 81 to 90% by weight.