Liquid crystal display device having an orientation layer containing liquid crystal with a controlled orientation and method for manufacturing the same

• US 5,528,401 A
• Filed: 07/28/1994
• Issued: 06/18/1996
• Est. Priority Date: 07/28/1993
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ishii, Yutaka, Narutaki, Yozo, Yamamoto, Yoshitaka
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): Dudek, James A.
• Application Number:
  US08/281,560
• Time in Patent Office: 691 Days
• Field of Search: 359/51, 359/52, 359/75, 359/76
• US Class Current: 349/124
• CPC Class Codes: G02F 1/133711 by organic films, e.g. polymeric films
• CPC Class Codes: G02F 1/133749 for low pretilt angles, i.e. lower than 15 degrees

Abstract

A liquid crystal display having a liquid crystal layer between substrates is provided with a liquid crystal orientation layer sandwiched between a substrate and the liquid crystal layer. The liquid crystal orientation layer is made of a mixture of liquid crystal molecules and a photo polymerizable compound. While projecting an ultraviolet ray so as to harden the photo polymerizable compound, a predetermined voltage set according to a desired pretilt angle is applied, thereby fixing the orientation of the liquid crystal molecules. The liquid crystal molecules of the liquid crystal layer are controlled so as to have an orientation direction set according to the pretilt angle of the liquid crystal orientation layer. The described liquid crystal orientation layer offers easy and accurate control of the pretilt angle. Therefore, for example, in the DAP mode liquid crystal display, a small pretilt angle can be set on an entire surface of the substrate, thereby achieving a high contrast display.

Claims

1. An information display device comprising:

a liquid crystal layer sandwiched between substrates;

plural voltage applying elements formed on at least one of said substrates for applying a voltage which controls an orientation direction of liquid crystal molecules; and

a liquid crystal orientation layer including a mixture of a solid substance and liquid crystal molecules, said liquid crystal molecules having a predetermined orientation in accordance with a voltage applied by said plural voltage applying elements to said liquid crystal orientation layer during curing of said solid substance, said liquid crystal orientation layer being formed between said liquid crystal layer and said at least one of said substrates.

2. The information display device as set forth in claim 1, wherein:

the solid substance is a polymerized compound of a polymerizable high polymer.

3. The information display device as set forth in claim 2, wherein:

the polymerizable high polymer is a photo polymerizable high polymer.

4. The information display device as set forth in claim 2, wherein:

the polymerizable high polymer is a thermal polymerizable high polymer.

5. The information display device as set forth in claim 1, wherein:

said liquid crystal orientation layer includes liquid crystal molecules whose orientation directions are varied from one another by applying different voltages from different ones of said plural voltage applying elements to corresponding portions of said liquid crystal orientation layer.

6. The information display device as set forth in claim 1, wherein:

a ratio of the liquid crystal to the solid substance in said liquid crystal orientation layer is in a range of 90-95%.

7. A method for manufacturing an information display device having a liquid crystal layer sandwiched between substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizable high polymer and liquid crystal molecules on at least one of said substrates; and

(b) controlling an orientation direction of the liquid crystal molecules in said liquid crystal orientation layer at a predetermined angle while polymerizing the polymerizable higher polymer in accordance with a voltage applied by plural voltage applying elements located on one side of said liquid crystal orientation layer to said liquid crystal orientation layer.

8. The method for manufacturing the information display device as set forth in claim 7, wherein said step (a) is composed of the steps of:

(c) preparing the mixture of the polymerizable high polymer and the liquid crystal molecules;

(d) preparing substrates which sandwich the mixture; and

(e) sandwiching the mixture between said substrates.

9. The method for manufacturing the information display device as set forth in claim 7, wherein the polymerizable high polymer in said step (a) is a photo polymerizable high polymer.

10. The method for manufacturing the information display device as set forth in claim 7, wherein the polymerizable high polymer in said step (a) is a thermal polymerizable high polymer.

11. The method for manufacturing the information display device as set forth in claim 7, wherein:

in said step (b), by applying a voltage to said liquid crystal orientation layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by projecting light to said liquid crystal orientation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the orientation direction of the liquid crystal molecules at a predetermined angle.

12. The method for manufacturing the information display device as set forth in claim 7, wherein:

in said step (b), by applying a voltage to said liquid crystal orientation layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by applying heat to said liquid crystal oreintation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the oreintation direction of the liquid crystal molecules at a predetermined angle.

13. The method for manufacturing the information display devices as set forth in claim 7, wherein:

in said step (b), by applying an electric field to said liquid crystal orientation layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by projecting light to said liquid crystal orientation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the orientation direction of the liquid crystal molecules at a predetermined angle.

14. The method for manufacturing the information display device as set forth in claim 7, wherein:

in said step (b), by applying an electric field to said liquid crystal layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by applying heat to said liquid crystal orientation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the orientation direction of the liquid crystal molecules at a predetermined angle.

15. A method for manufacturing an information display device having a liquid crystal layer sandwiched between substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizing the polymerizable high polymer and liquid crystal molecules on at least on one of said substrates; and

(b) controlling an orientation direction of the liquid crystal molecules in said liquid crystal orientation layer to be 1°

while polymerizing the polymerizable high polymer by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² while applying a voltage to said liquid crystal orientation layer so that the orientation direction of said liquid crystal molecules is set to 1°

.

16. A method for manufacturing an information display device having a liquid crystal layer sandwiched between substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizable high polymer and liquid crystal molecules on at least on one of said substrates; and

(b) controlling an orientation direction of the liquid crystal molecules in said liquid crystal orientation layer at a predetermined angle by applying a static magnetic field to said liquid crystal orientation layer in a direction set to a desired pretilt angle of the liquid crystal molecules in said liquid crystal orientation layer wile polymerizing the polymerizable high polymer.

17. The method for manufacturing the information display device as set forth in claim 16, wherein:

in said step (b), by applying a magnetic field to said liquid crystal orientation layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by projecting light to said liquid crystal orientation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the orientation direction of the liquid crystal molecules at a predetermined angle.

18. The method for manufacturing the information display device as set forth in claim 16, wherein:

in said step (b), by applying a magnetic field to said liquid crystal orientation layer, the liquid crystal molecules are controlled so as to have a predetermined orientation direction, in the meantime, by applying heat to said liquid crystal orientation layer, the polymerizable high polymer is polymerized and hardened, thereby fixing the liquid crystal molecules and controlling the orientation direction of the liquid crystal molecules at a predetermined angle.

19. The method for manufacturing the information display device as set forth in claim 16, wherein:

in said step (b),

the pretilt angle of the liquid crystal molecules in said liquid crystal orientation layer is controlled to be 1°

by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer while a static magnetic field of 300000 Gauss is being applied to said liquid crystal orientation layer in a direction tilted from a substrate normal by 1°

.

20. The method for manufacturing the information display device as set forth in claim 16, wherein:

in said step (b),

said liquid crystal molecules are composed of first liquid crystal molecules and second liquid crystal molecules,

a pretilt angle of said first liquid crystal molecules in said liquid crystal orientation layer is controlled to be 3°

by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer which is partially masked, while a static magnetic field of 300000 Gauss is being applied to said liquid crystal orientation layer in a direction tilted from a substrate normal by 3°

, and

a pretilt angle of said second liquid crystal molecules in said liquid crystal orientation layer are controlled to be 3°

in an opposite direction to the pretilt angle of said first liquid crystal molecules by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer from which a mask is removed, while a static magnetic field of 300000 Gauss is being applied to said liquid crystal orientation layer in a direction tilted from the substrate normal by 3°

in an opposite direction to a case of controlling the pretilt angle of said first liquid crystal molecules, thereby forming different pretilt angles in respective areas on one substrate.

21. A method for manufacturing an information display device having a liquid crystal layer sandwiched between substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizable high polymer and liquid crystal molecules on at least on one of said substrates;

(b) controlling an orientation direction of the liquid crystal molecules in said liquid crystal orientation layer at a predetermined angle while polymerizing the polymerizable high polymer; and

(c) forming thin film transistor elements on said substrate, wherein said step (b) further comprises;

controlling the pretilt angle of the liquid crystal molecules in said liquid crystal orientation layer to be 2°

or 5°

by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/c², while applying a voltage onto said liquid crystal orientation layer so that the pretilt angle of the liquid crystal molecules is set to 2°

or 5°

.

22. A method for manufacturing an information display device having a liquid crystal layer sandwiched between substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizable high polymer and liquid crystal molecules on at least on one of said substrate; and

(b) controlling a pretilt angle of the liquid crystal molecules in said liquid crystal orientation layer to be 1°

while polymerizing the polymerizable high polymer by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer while applying a static magnetic field of 300000 Gauss to said liquid crystal orientation layer in a direction tilted from a substrate normal by 1°

.

23. A method for manufacturing an information display device having a liquid crystal layer sandwiched between the substrates, comprising the steps of:

(a) forming a liquid crystal orientation layer made of a mixture of a polymerizable high polymer and liquid crystal molecules on at least one of said substrates, said liquid crystal molecules being composed of first liquid crystal molecules and second liquid crystal molecules; and

(b) controlling an orientation direction of said liquid crystal molecules in said liquid crystal orientation layer at a predetermined angle while polymerizing the polymerizable high polymer including controlling a pretilt angle of said first liquid crystal molecules in said liquid crystal orientation to be 3°

by hardening the polymerizable high polymer by protecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer which is partially masked, while applying a static magnetic field of 300000 Gauss to said liquid crystal orientation layer in a direction tilted from a substrate normal by 3°

, and controlling a pretilt angle of said second liquid crystal molecules in said liquid crystal orientation layer to be 3°

in an opposite direction to the pretilt angle of said first liquid crystal molecules by hardening the polymerizable high polymer by projecting an ultraviolet ray having an intensity of 20 mW/cm² to said liquid crystal orientation layer from which a mask is removed, while a static magnetic field of 300000 Gauss is being applied to said liquid crystal orientation layer in a direction tilted from the substrate normal by 3°

in an opposite direction to a case of controlling the pretilt angle of said first liquid crystal molecules, thereby forming different pretilt angles in respective areas on one substrate.