Liquid-crystal panel of polymer dispersed type and method of manufacturing the same

• US 6,341,000 B1
• Filed: 06/29/1998
• Issued: 01/22/2002
• Est. Priority Date: 12/27/1993
• 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: Uemura, Tsuyoshi, Inoue, Kazuo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Nguyen, Dung
• Application Number:
  US09/106,144
• Time in Patent Office: 1,303 Days
• Field of Search: 349/92, 349/93, 349/89, 349/86, 349/90, 349/155, 349/182, 349/183
• US Class Current: 349/93
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13392 spacers dispersed on the cell substrate, e.g. spherical particles, microfibres

Abstract

A liquid-crystal panel comprises a pair of transparent glass substrates each being provided with an electrode. Between the glass substrates are disposed spacers for defining a space and a mixture of droplets of a liquid crystal having a mean diameter of 3.0 μm or less and of a photo-curing polymer. The edge portions of the glass substrates are sealed with a seal polymer. In curing the photo-curing polymer during the process of manufacturing the liquid-crystal panel, the dose of an ultraviolet ray is set to 500 mJ/cm² or more so as to reduce the diameters of the droplets of the liquid crystal, thereby preventing light leakage in the state without a voltage applied and improving the contrast. If the spacers are colored, the effect of preventing light leakage is increased. If the spacers are subjected to a surface treatment for rejecting the liquid crystal or composed of a polymer material of the same type as that of the photo-curing polymer, variations in diameter of the droplets of the liquid crystal can be prevented. With the structure, it becomes possible to provide a liquid-crystal panel in which light leakage in the black mode is reduced and which presents uniform and high-contrast display of images.

Claims

1. A method of manufacturing a liquid-crystal panel of polymer dispersed type, comprising the steps of:

preparing in advance a pair of substrates each being provided with an electrode for applying a voltage and dispersing, on one of said pair of substrates, spacers for holding the substrates at a specified distance, surface portions of said spacers having either a scarce affinity with droplets of a liquid crystal or a large affinity with a polymer member;

holding said substrate on which the spacers are dispersed and the other substrate so that they are opposed to each other with the spacers interposed therebetween, mixing a prepolymer member not containing a crosslinkage-type polymer with said liquid crystal, and filling the mixture into the space between the substrates; and

curing said prepolymer member and forming said polymer member, while causing a phase separation between said polymer member and said liquid crystal simultaneously, so as to separate said liquid crystal in droplets having a mean diameter of 3.0 μ

m or less, wherein said polymer member comprises a photo-curing polymer and said polymer member is irradiated with light equal to or more intense than 500 mJ/cm² in the step of curing said prepolymer member.

2. A method of manufacturing a liquid-crystal panel of polymer dispersed type, according to claim 1, further comprising the step of treating the surface portions of said spacers so that they have the property of rejecting said liquid crystal.

3. A method of manufacturing a liquid-crystal panel of polymer dispersed type according to claim 2, wherein, in the step of treating the surface portions of said spacers so that they have the property of rejecting the liquid crystal, a surface-active agent containing fluorine as its main component is absorbed by the surfaces of the spacers.

4. A method of manufacturing a liquid-crystal panel of polymer dispersed type according to claim 1, wherein at least the surface portions of the spacers are composed of a material of the same type as that of said polymer member.