Method of manufacturing liquid crystal display element

• US 5,162,934 A
• Filed: 03/20/1992
• Issued: 11/10/1992
• Est. Priority Date: 07/31/1989
• Status: Expired due to Fees

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Niiyama, Satoshi, Kumai, Hiroshi, Gunjima, Tomoki
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): TRAN, MINH LOAN
• Application Number:
  US07/854,762
• Time in Patent Office: 235 Days
• Field of Search: 350/331 R, 350/334, 350/343, 350/344, 350/347 E, 350/347 V, 359/51, 359/80, 359/81, 359/94, 359/102, 430/20, 428/1
• US Class Current: 349/93
• CPC Class Codes: G02F 1/13 based on liquid crystals, e.g. single liquid crystal display cells

Abstract

A method of manufacturing a liquid crystal display element comprising a pair of substrates and a liquid crystal composition injected into and cured in an evacuated cell constituted with the substrates, wherein the degree of vacuum in the cell is from 0.5 to 10 mmHg, the composition forms a liquid crystal and polymer composite in which the nematic liquid crystal is dispersed and held in the resin matrix, and light transparent-scattering states are attained by agreement and disagreement between the refraction index of the liquid crystal and the refractive index of the resin matrix under control of an electric field applied across the electrodes. Residual bubbles left in the cell are disposed in the peripheral portion not constituting the display portion or in the pocket portion formed integrally to the peripheral portion.

Claims

1. A method of manufacturing a liquid crystal display cell comprising a sealed pair of substrates with peripheral portions, each substrate having an electrode thereon, and provided with an injection port, said cell having a display portion, which comprises:

sealing a pair of substrates provided with electrodes along the periphery thereof except for the area of said injection port to prepare a display cell whose periphery is not a part of the display portion of the cell and which has a vacant interior;

placing said cell in a vessel;

reducing the pressure of the atmosphere within the vessel and cell down to a pressure of 0.5 to 10 mmHg and then injecting a liquid crystal composition of a mixture of a nematic liquid crystal and a curable compound through the injection port by permitting the pressure to increase within the vessel, thereby allowing the resulting pressure increase in the vessel to force the liquid crystal composition through the injection port of the vacant interior of the cell, thereby filling the cell with the composition, which filling is accompanied by the presence of bubbles in the cell;

sealing the filled cell at the injection port; and

curing said liquid crystal composition within the tightly sealed cell under conditions in which the bubbles in the cell are in the peripheral, non-display portion of the cell, thereby forming a liquid crystal-polymer matrix composite in which the nematic liquid crystal is dispersed and held within the matrix of the polymer, the relationship between the refractive index of the liquid crystal and the refractive index of the polymer matrix, when under control of an electric field applied across the pair of electrodes of the cell, being such that when there is agreement between the refractive indexes of the liquid crystal and the polymer matrix, the cell is treatment, and when there is disagreement between the refractive indexes of the liquid crystal and polymer matrix, a light-scattering state exists.

2. The method of claim 1, wherein said curable compound is a light curable compound, said liquid crystal composition is injected into the cell as a homogeneously dissolved solution, and said curable compound is exposed to light to form the liquid crystal-polymer composite.

3. The method of claim 2, wherein said curable compound is a light curable vinyl resin.

4. The method of claim 3, wherein said curable compound is a light curable acryl resin.

5. The method of claim 4, wherein said curable compound is a light curable acryl resin containing an acryl oligomer.

6. The method of claim 1, wherein said liquid crystal composition further comprises not less than 5% by weight of at least one ingredient, which, under the reduced pressure conditions of said cell, has a boiling point of greater than 60°

C.

7. The method of claim 6, wherein said liquid crystal composition containing ingredients further contains low boiling ingredients which are present int he composition when the vessel is subjected to pressure reduction.

8. The method of claim 1, wherein said liquid crystal composition is brought into contact with the injection port of said cell, and subsequently, the liquid crystal composition is injected into the cell by the release of vacuum in the vessel.

9. The method of claim 8, wherein the injection of liquid crystal composition into the cell is facilitated by the admission of pressurizing gas into the vessel.

10. The method of claim 1, wherein a pocket portion is formed on the periphery of said cell by outwardly bulging the seal of the cell at the non-display portion thereof apart from the injection port of the cell, with curing of the injected composition occurring while the residual bubbles in the cell are in the pocket portion.

11. The method of claim 10, wherein said pocket portion is removed by cutting the pocket form the cell.

12. A method of manufacturing a liquid crystal display cell comprising a sealed pair of substrates with peripheral portions, each substrate having an electrode thereon, and provided with an injection port, said cell having a display portion, which comprises:

sealing a pair of substrates provided with electrodes along the periphery thereof except for the area of said injection port to prepare a display cell whose periphery is not a part of the display portion of the cell and which has a vacant interior;

placing said cell in a vessel;

reducing the pressure of the atmosphere within the vessel and cell down to a pressure of 0.5 to 10 mmHg and then injecting a liquid crystal composition of a mixture of a nematic liquid crystal, a curable compound and not less than 5% by weight of at least one ingredient which, under the pressure of the cell, has a boiling point of greater than 60°

C. through the injection port by permitting the pressure to increase within the vessel, thereby allowing the resulting pressure increase int he vessel to force the liquid crystal composition through the injection port of the vacant interior of the cell, thereby filling the cell with the composition, which filling is accompanied by the presence of bubbles in the cell;

sealing the filled cell at the injection port; and

curing said liquid crystal composition within the tightly sealed cell under conditions in which the bubbles in the cell are in the peripheral, non-display portion of the cell, thereby forming a liquid crystal-polymer matrix composite in which the nematic liquid crystal is dispersed and held within the matrix of the polymer, wherein the refractive index of the matrix resin substantially agrees with the ordinary refractive index (n_o) of the liquid crystal.

13. The method of claim 12, wherein said curable compound is a light curable compound, said liquid crystal composition is injected into the cell as a homogeneously dissolved solution, and said curable compound is exposed to light to form the liquid crystal-polymer composite.

14. The method of claim 12, wherein said curable compound is a light curable acryl resin.

15. A method of manufacturing a liquid crystal display cell comprising a sealed pair of substrates with peripheral portions, each substrate having an electrode thereon, and provided with an injection port, said cell having a display portion, which comprises:

sealing a pair of substrates provided with electrodes along the periphery thereof except for the area of said injection port to prepare a display cell whose periphery is not a part of the display portion of the cell and which has a vacant interior;

placing said cell in a vessel;

reducing the pressure of the atmosphere within the vessel and cell down to a pressure of 0.5 to 10 mmHg and then injecting a liquid crystal composition of a mixture of a nematic liquid crystal, a curable compound and not less than 5% by weight of at least one ingredient which, under the pressure of the cell, has a boiling point of greater than 60°

C. through the injection port by permitting the pressure to increase within the vessel, thereby allowing the resulting pressure increase int he vessel to force the liquid crystal composition through the injection port of the vacant interior of the cell, thereby filling the cell with the composition, which filling is accompanied by the presence of bubbles in the cell which are positioned in the peripheral, non-display portion of the cell; and

curing said liquid crystal composition within the tightly sealed cell, thereby forming a liquid crystal-polymer composite in which the nematic liquid crystal is dispersed and held within the resin matrix of the polymer, wherein the refractive index of the resin matrix substantially agrees with the ordinary refractive index (n_o) of the nematic liquid crystal.

16. The method of claim 15, wherein the injected curable composition is cured when the bubbles are present and fixed in the peripheral portion of the cell on the side opposite the injection port.

17. A method of manufacturing a liquid crystal display cell, comprising a sealed pair of substrates with peripheral portions, each substrate having an electrode thereon, and provided with an injection port, said cell having a display portion, which comprises:

sealing a pair of substrates provided with electrodes along the periphery thereof except for the area of said injection port to prepare a display cell whose periphery is not a part of the display portion of the cell, which seal outwardly bulges in the non-display portion of the cell apart from the injection port, said cell having a vacant interior;

placing said cell in a vessel;

reducing the pressure of the atmosphere within the vessel and cell and then injecting a liquid crystal composition of a mixture of a nematic liquid crystal and a curable compound through the injection port by permitting the pressure to increase within the vessel, thereby allowing the resulting pressure increase int he vessel to force the liquid crystal composition through the injection port of the vacant interior of the cell which is under reduced pressure, thereby filling the cell with the composition, which filling is accompanied by the presence of residual bubbles in the cell; and

curing said liquid crystal composition within the tightly sealed cell, thereby forming a liquid crystal-polymer composite in which the nematic liquid crystal is dispersed and held within the resin matrix of the polymer and in which the residual bubbles are left in the pocket formed by the outward bulging of said seal, the relationship between the refractive index of the liquid crystal and the refractive index of the resin matrix, when under control of an electric field applied across the pair of electrodes of the cell, being such that when there is agreement between the refractive indexes of the liquid crystal and the resin matrix, the cell is transparent, and when there is disagreement between the refractive indexes of the liquid crystal and the resin matrix, a light-scattering state exists.

18. The method of claim 17, wherein curing of the curable compound is conducted after displacing the bubbles into the pocket portion of the cell.

19. The method of claim 17, wherein the pocket portion of the cell is removed by cutting.

20. The method of claim 19, wherein the pocket portion of the cell is removed by cutting after the curable compound is cured.