Liquid crystal display device and electronic apparatus

• US 7,843,540 B2
• Filed: 01/17/2006
• Issued: 11/30/2010
• Est. Priority Date: 02/28/2005
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Shimamura, Hideo, Ozawa, Kinya
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): NGUYEN, THANH NHAN P
• Application Number:
  US11/332,147
• Publication Number:
  US 20060203169A1
• Time in Patent Office: 1,778 Days
• Field of Search: 349/141, 349/106
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133541 Circular polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/13731 based on a field-induced phase transition G02F1/13781 takes precedence
• CPC Class Codes: G02F 1/13775 Polymer-stabilized liquid crystal layers
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

A liquid crystal display device of the present invention is a liquid crystal display device having a first substrate, a second substrate, a liquid crystal layer disposed between the first and second substrates, and a plurality of pixels each having a display region, in that: the liquid crystal layer is optically isotropic when an selective electric field is not applied and optically aisotropic when an electric field is applied and includes a material whose refractive index changes depending on the strength of the electric field; and the plurality of pixels include first and second pixels different in the electric field strength.

Claims

1. A liquid crystal display device, comprising:

a first substrate;

a second substrate;

a liquid crystal layer disposed between the first and second substrates, the liquid crystal layer being optically isotropic when a selective electric field is not applied, the liquid crystal layer being optically anisotropic when an electric field is applied, a refractive index of a material of the liquid crystal layer being changed depending on a strength of an electric field the liquid crystal layer including a composite liquid crystal composition, the composite liquid crystal composition including a low molecule liquid crystal material and a polymer network, the polymer network being formed among constituent molecules of the low molecule liquid crystal material, and the polymer network being formed by polymerizing nonliquid crystal monomers, the low molecule liquid crystal material having a blue phase between a cholesteric phase and an isotropic phase;

a first pixel formed on the first substrate, the first pixel having a first electric field strength;

a second pixel formed on the first substrate, the second pixel having a second electric field strength, the first electric field strength and the second electric field strength being different; and

a reflective film formed between the first substrate and the liquid crystal layer, a portion of the liquid crystal layer being overlapped with the reflective film, the portion of the liquid crystal layer having an optical phase difference Δ

nd, the optical phase difference Δ

nd being approximately λ

/4.

2. The liquid crystal display device according to claim 1, the first pixel displaying a first color, the second pixel displaying a second color, the first color and the second color being different, the first pixel having at least a first pixel electrode and at least a first common electrode, the first pixel having a first distance between the first pixel electrode and the first common electrode, the second pixel having at least a second pixel electrode and at least a second common electrode, the second pixel having a second distance between the second pixel electrode and the second common electrode, the first distance and the second distance being different, each of the first pixel electrode, the first common electrode, the second pixel electrode and the second common electrode being positioned between the first substrate and the liquid crystal layer, a first electric field being generated between the first pixel electrode and the first common electrode, and a second electric field being generated between the second pixel electrode and the second common electrode.

3. The liquid crystal display device according to claim 2, at least a first portion of the liquid crystal layer being overlapped with the first pixel, at least a second portion of the liquid crystal layer being overlapped with the second pixel, the first portion and the second portion having different refractive indexes.

4. The liquid crystal display device according to claim 2, a first portion of the liquid crystal layer being overlapped with the first pixel, a first light of a first wavelength being modulated by the first portion, a second portion of the liquid crystal layer being overlapped with the second pixel, a second light of a second wavelength being modulated by the second portion, the first distance being larger than the second distance, the first wavelength being shorter than the second wavelength.

5. The liquid crystal display device according to claim 4, the first color being blue and the second color being green.

6. The liquid crystal display device according to claim 2, the first color and the second color being different so that the liquid crystal display device requires no color filters.

7. The liquid crystal display device according to claim 1, the liquid crystal layer including a pseudo-isotropic liquid crystal.

8. An electronic apparatus including the liquid crystal display device according to claim 1.

9. A liquid crystal display device, comprising:

a first substrate;

a second substrate;

a liquid crystal layer disposed between the first and second substrates, the liquid crystal layer being optically isotropic when a selective electric field is not applied, the liquid crystal layer being optically anisotropic when an electric field is applied, a refractive index of a material of the liquid crystal layer being changed depending on a strength of an electric field, the liquid crystal layer including a composite liquid crystal composition, the composite liquid crystal composition including a low molecule liquid crystal material and a polymer network, the polymer network being formed among constituent molecules of the low molecule liquid crystal material, and the polymer network being formed by polymerizing nonliquid crystal monomers, the low molecule liquid crystal material having a blue phase between a cholesteric phase and an isotropic phase a portion of the liquid crystal layer having an optical phase difference Δ

nd, the optical phase difference Δ

nd being approximately λ

/2;

a first pixel formed on the first substrate, the first pixel having a first electric field strength; and

a second pixel formed on the first substrate, the second pixel having a second electric field strength, the first electric field strength and the second electric field strength being different.

10. The liquid crystal display device according to claim 9, the first pixel displaying a first color, the second pixel displaying a second color, the first color and the second color being different, the first pixel having a first electrode and a second electrode, both the first electrode and the second electrode being positioned between the first substrate and the liquid crystal layer, an electric field being generated between the first electrode and the second electrode.

11. The liquid crystal display device according to claim 10, the first color and the second color being different so that the liquid crystal display device requires no color filters.

12. A liquid crystal display device, comprising:

a first substrate;

a second substrate;

a liquid crystal layer disposed between the first and second substrates, the liquid crystal layer being optically isotropic when a selective electric field is not applied, the liquid crystal layer being optically anisotropic when an electric field is applied, a refractive index of a material of the liquid crystal layer being changed depending on a strength of an electric field, the liquid crystal layer including a composite liquid crystal composition, the composite liquid crystal composition including a low molecule liquid crystal material and a polymer network, the polymer network being formed by polymerizing nonliquid crystal monomers, the low molecule liquid crystal material having a blue phase between a cholesteric phase and an isotropic phase;

a first pixel formed on the first substrate, the first pixel having a first electric field strength; and

a second pixel formed on the first substrate, the second pixel having a second electric field strength, the first electric field strength and the second electric field strength being different.

13. The liquid crystal display device according to claim 12, the non liquid crystal monomer being an acrylate-based monomer that has an alkyl group as the side chain.

14. The liquid crystal display device according to claim 12, the first pixel displaying a first color, the second pixel displaying a second color, the first color and the second color being different, the first pixel having a first electrode and a second electrode, both the first electrode and the second electrode being positioned between the first substrate and the liquid crystal layer, an electric field being generated between the first electrode and the second electrode.

15. The liquid crystal display device according to claim 14, the first color and the second color being different so that the liquid crystal display device requires no color filters.