LIQUID CRYSTAL DISPLAY DEVICE

• US 20070126962A1
• Filed: 12/01/2006
• Published: 06/07/2007
• Est. Priority Date: 12/05/2005
• Status: Abandoned Application

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Egi, Yuji, Nishi, Takeshi, Ishitani, Tetsuji
• Application Number:
  US11/565,976
• Publication Number:
  US 20070126962A1
• Time in Patent Office: Days
• US Class Current: 349/119
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/16 series; tandem
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

A problem exists in that black luminance in a liquid crystal display device when seen in a dark place is high compared to black luminance of a light emitting element in a non-light-emitting state, so as a result, contrast ratio is low. There is a high demand for contrast ratio to be improved. Therefore, it is an object of the present invention to provide a liquid crystal display device with improved contrast ratio and a wide viewing angle. Retardation films and stacked polarizing plates are provided over light transmitting substrates which sandwich a display element. A film having liquid crystal with hybrid oriented liquid crystal, a film having liquid crystal with twisted orientation, uniaxial retardation films, or biaxially retardation films can be used as the retardation films. It is preferable that the stacked polarizing plates comprise two polarizing plates.

Claims

1. A liquid crystal display device comprising:

a first light transmitting substrate;

a second light transmitting substrate opposed to the first light transmitting substrate;

a liquid crystal material interposed between the first light transmitting substrate and the second light transmitting substrate; and

a retardation film and stacked polarizing plates disposed on an outer side of the first light transmitting substrate such that the retardation film is located between the first light transmitting substrate and the stacked polarizing plates,

wherein the stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement.

2. The liquid crystal display device according to claim 1 wherein the stacked polarizing plates has two polarizing plates.

3. The liquid crystal display device according to claim 1, wherein the retardation film is selected from the group consisting of a film comprising liquid crystal with a hybrid orientation, a film comprising liquid crystal with a twisted orientation, a uniaxial retardation film, and a biaxially retardation film.

4. The liquid crystal display device according to claim 1, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is applied between the first electrode and the second electrode, and conducts black display when a voltage is not applied between the first electrode and the second electrode.

5. The liquid crystal display device according to claim 1, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is not applied between the first electrode and the second electrode, and conducts black display when a voltage is applied between the first electrode and the second electrode.

6. A liquid crystal display device comprising:

a first light transmitting substrate;

a second light transmitting substrate opposed to the first light transmitting substrate;

a liquid crystal material interposed between the first light transmitting substrate and the second light transmitting substrate;

a first retardation film and first stacked polarizing plates disposed on an outer side of the first light transmitting substrate such that the first retardation film is located between the first light transmitting substrate and the first stacked polarizing plates; and

a second retardation film and a second polarizing plate disposed on an outer side of the second light transmitting substrate such that the second retardation film is located between the second light transmitting substrate and the second polarizing plates,

wherein the first stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement.

7. The liquid crystal display device according to claim 6 wherein the first stacked polarizing plates have two polarizing plates.

8. The liquid crystal display device according to claim 6, wherein each of the first and second retardation films is selected from the group consisting of a film comprising liquid crystal with a hybrid orientation, a film comprising liquid crystal with a twisted orientation, a uniaxial retardation film, and a biaxially retardation film.

9. The liquid crystal display device according to claim 6, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is applied between the first electrode and the second electrode, and conducts black display when a voltage is not applied between the first electrode and the second electrode.

10. The liquid crystal display device according to claim 6, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is not applied between the first electrode and the second electrode, and conducts black display when a voltage is applied between the first electrode and the second electrode.

11. A liquid crystal display device comprising:

a first light transmitting substrate;

a second light transmitting substrate opposed to the first substrate;

a liquid crystal material interposed between the first light transmitting substrate and the second light transmitting substrate;

a first retardation film and first stacked polarizing plates disposed on an outer side of the first light transmitting substrate such that the first retardation film is located between the first light transmitting substrate and the first stacked polarizing plates; and

a second retardation film and second stacked polarizing plates disposed on an outer side of the second light transmitting substrate such that the second retardation film is located between the second light transmitting substrate and the second stacked polarizing plates,

wherein the first stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement and the second stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement; and

the absorption axes of the first stacked polarizing plates disposed are in a cross nicol arrangement with respect to the absorption axes of the second stacked polarizing plates.

12. The liquid crystal display device according to claim 11 wherein each of the first stacked polarizing plates the second polarizing plates has two polarizing plates.

13. The liquid crystal display device according to claim 11, wherein each of the first and second retardation films is selected from the group consisting of a film comprising liquid crystal with a hybrid orientation, a film comprising liquid crystal with a twisted orientation, a uniaxial retardation film, and a biaxially retardation film.

14. The liquid crystal display device according to claim 11, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is applied between the first electrode and the second electrode, and conducts black display when a voltage is not applied between the first electrode and the second electrode.

15. The liquid crystal display device according to claim 11, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is not applied between the first electrode and the second electrode, and conducts black display when a voltage is applied between the first electrode and the second electrode.

16. A liquid crystal display device comprising:

a first light transmitting substrate;

a second light transmitting substrate opposed to the first substrate;

a liquid crystal material interposed between the first light transmitting substrate and the second light transmitting substrate;

a first retardation film and first stacked polarizing plates disposed on an outer side of the first light transmitting substrate wherein the first retardation film is located between the first light transmitting substrate and the first stacked polarizing plates;

a second retardation film and second stacked polarizing plates disposed on an outer side of the second light transmitting substrate wherein the second retardation film is located between the second light transmitting substrate and the second stacked polarizing plates; and

a color filter disposed on an inner side of at least one of the first light transmitting substrate and the second light transmitting substrate,

wherein the first stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement and the second stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement; and

the absorption axes of the first stacked polarizing plates are in a cross nicol arrangement with respect to the absorption axes of the second stacked polarizing plates.

17. The liquid crystal display device according to claim 16, wherein each of the first stacked polarizing plates and the second stacked polarizing plates has two polarizing plates.

18. The liquid crystal display device according to claim 16, wherein each of the first and second retardation films is selected from the group consisting of a film comprising liquid crystal with a hybrid orientation, a film comprising liquid crystal with a twisted orientation, a uniaxial retardation film, and a biaxially retardation film.

19. The liquid crystal display device according to claim 16, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is applied between the first electrode and the second electrode, and conducts black display when a voltage is not applied between the first electrode and the second electrode.

20. The liquid crystal display device according to claim 16, wherein:

the first light transmitting substrate includes a first electrode,

the second light transmitting substrate includes a second electrode, and

the display device conducts white display when a voltage is not applied between the first electrode and the second electrode, and conducts black display when a voltage is applied between the first electrode and the second electrode.

21. A display device comprising:

a first substrate and a second substrate opposed to each other;

a display element interposed between the first and second substrates;

a first retardation film and first stacked polarizing plates disposed on an outer side of the first substrate such that the first retardation film is located between the first substrate and the first stacked polarizing plates; and

a second retardation film and a second polarizing plate disposed on an outer side of the second substrate such that the second retardation film is located between the second substrate and the second stacked polarizing plates,

wherein the first stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement and the second stacked polarizing plates are disposed such that their absorption axes are in a parallel nicol arrangement, and

the absorption axes of the first stacked polarizing plates are in a cross nicol arrangement with respect to the absorption axes of the second stacked polarizing plates.

22. The display device according to claim 21 wherein the display element is a liquid crystal element.