Method for forming an electro-optical device

• US 5,525,273 A
• Filed: 09/15/1993
• Issued: 06/11/1996
• Est. Priority Date: 09/19/1992
• Status: Expired due to Fees

• Current Assignee: Energy Laboratories, Inc.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Konuma, Toshimitsu, Nishi, Takeshi, Shimizu, Michio, Moriya, Kouji
• Primary Examiner(s): Timm, Catherine
• Application Number:
  US08/120,794
• Time in Patent Office: 1,000 Days
• Field of Search: 264/1.3, 264/1.4, 264/22, 264/1.36, 264/1.38, 359/51, 359/52
• US Class Current: 264/1.38
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13756 the liquid crystal selectively assuming a light-scattering state G02F1/1334, G02F1/13718 take precedence

Abstract

The present invention provides a method of fabricating a dispersion-type liquid crystal electro-optical device comprising a pair of substrates disposed opposite to each other with a space therebetween and provided with electrodes respectively on their inner surfaces, and a liquid crystal mixture containing a liquid crystal and a transparent resin and sandwiched between the pair of substrates. The method comprises steps of: filling up the space between the pair of substrates with the fluid liquid crystal mixture, applying a voltage across the electrodes to apply an electric field to the fluid liquid crystal mixture to collect the charge of the fluid liquid crystal mixture in the vicinity of the electrodes; and setting the transparent resin. The dispersion-type liquid crystal electro-optical device has a high voltage retention and a low transmissivity in the scattering state, and is capable of clearly displaying pictures at a high contrast ratio.

Claims

1. A method for forming a liquid crystal electro-optical device comprising the steps of:

providing a mixture of a liquid crystal and a curable transparent resin between a pair of electrodes;

applying an electric field to said mixture in order to move mobile charges which are contained in said liquid crystal to said resin; and

hardening said transparent resin to fix said mobile charges in said resin, wherein said electric field is applied until an electric current flowing through said liquid crystal reduces to 1/5 to 1/100 of an initial current.

2. The method of claim 1 wherein said transparent resin comprises an ultraviolet ray curing resin, and said hardening is carried out by irradiating said transparent resin with an ultraviolet ray.

3. The method of claim 1 wherein said transparent resin comprises a thermosetting resin, and said hardening is carried out by heating said transparent resin.

4. The method of claim 1 wherein said electric field is not lower than 0.5 V/μ

m.

5. The method of claim 1 wherein said hardening is carried out at a temperature higher than room temperature.

19. The method of claim 1, 6 or 14 wherein said mixture and said pair of electrodes are supported by a pair substrates.

6. A method for forming a liquid crystal electro-optical device comprising the steps of:

providing a mixture of a liquid crystal and a curable transparent resin between a pair of electrodes;

applying an electric field to said mixture in order to move mobile charges which are contained in said liquid crystal to said resin; and

then

hardening said transparent resin to fix said mobile charges in said resin,

wherein the application of said electric field is continued during said hardening and wherein said electric field is applied until an electric current flowing through said liquid crystal reduces to 1/5 to 1/100 of an initial current.

7. The method of claim 6 wherein said transparent resin comprises an ultraviolet ray curing resin, and said hardening is carried out by irradiating said transparent resin with an ultraviolet ray.

8. The method of claim 6 wherein said transparent resin comprises a thermosetting resin, and said hardening is carried out by heating said transparent resin.

9. The method of claim 6 wherein said electric field is not lower than 0.5 Vμ

m.

10. The method of claim 6 wherein said hardening is carried out at a temperature higher than room temperature.

11. The method of claim 6 wherein said hardening is carried out after current flowing between said electrodes by the application of said electric field reaches a peak.

12. The method of claim 8 wherein said transparent resin is hardened at a temperature of 70°

to 120°

C. by said heating.

13. The method of claim 6 wherein said electric field is a DC electric field.

14. A method for forming a liquid crystal electro-optical device comprising the steps of:

providing a mixture of a liquid crystal and a curable transparent resin between a pair of electrodes;

applying a DC electric field to said mixture in order to move mobile charges which are contained in said liquid crystal to said resin; and

hardening said transparent resin to fix said mobile charges in said resin, wherein said electric field is applied until an electric current flowing through said liquid crystal reduces to 1/5 to 1/100 of an initial current.

15. The method of claim 14 wherein said transparent resin comprises an ultraviolet ray curing resin, and said hardening is carried out by irradiating said transparent resin with an ultraviolet ray.

16. The method of claim 14 wherein said transparent resin comprises a thermosetting resin, and said hardening is carried out by heating said transparent resin.

17. The method of claim 14 wherein said electric field is not lower than 0.5 Vμ

m.

18. The method of claim 14 wherein said hardening is carried out at a temperature higher than room temperature.