Display device

• US 7,804,560 B2
• Filed: 12/20/2006
• Issued: 09/28/2010
• Est. Priority Date: 12/28/2005
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Egi, Yuji, Nishi, Takeshi, Ishitani, Tetsuji
• Primary Examiner(s): Dudek; James A
• Application Number:
  US11/613,785
• Publication Number:
  US 20070146580A1
• Time in Patent Office: 1,378 Days
• Field of Search: 349 96- 97, 359491-492, 359/494
• US Class Current: 349/96
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n

Abstract

An object of the invention is to provide a display device having a high contrast ratio by a simple and easy method. Another object of the invention is to manufacture such a high-performance display device at low cost. In a display device having a display element between a pair of light-transmissive substrates, polarizing plates each having an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate are stacked to be provided. At that time, the stacked polarizing plates are arranged so as to be in a parallel nicol state. A wave plate and a retardation film may be provided between the stacked polarizing plates and the substrates.

Claims

1. A display device comprising:

a display element sandwiched between a first light-transmissive substrate and a second light-transmissive substrate which are provided so as to face each other; and

stacked polarizing plates outside the first light-transmissive substrate or the second light- transmissive substrate,

wherein each of the stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the stacked polarizing plates are in a parallel nicol state, and

wherein each of the stacked polarizing plates includes iodine.

2. The display device according to claim 1, wherein the display element is a liquid crystal element.

3. The display device according to claim 1, wherein the display element is a light emitting element.

4. The display device according to claim 1, wherein the display device is an active matrix type display device.

5. The display device according to claim 1, wherein the display device is a passive matrix type display device.

6. A display device comprising:

a display element sandwiched between a first light-transmissive substrate and a second light-transmissive substrate which are provided so as to face each other;

a retardation film outside the first light-transmissive substrate or the second light- transmissive substrate; and

stacked polarizing plates outside the retardation film,

wherein each of the stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the stacked polarizing plates are in a parallel nicol state, and

wherein each of the stacked polarizing plates includes iodine.

7. The display device according to claim 6, wherein the display element is a liquid crystal element.

8. The display device according to claim 6, wherein the display element is a light emitting element.

9. The display device according to claim 6, wherein the display device is an active matrix type display device.

10. The display device according to claim 6, wherein the display device is a passive matrix type display device.

11. The display device according to claim 6, wherein the retardation film is a λ

/4 plate.

12. A display device comprising:

a display element sandwiched between a first light-transmissive substrate and a second light-transmissive substrate which are provided so as to face each other;

first stacked polarizing plates outside the first light-transmissive substrate; and

second stacked polarizing plates outside the second light-transmissive substrate,

wherein each of the first stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the first stacked polarizing plates are in a parallel nicol state,

wherein each of the second stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the second stacked polarizing plates are in a parallel nicol state, and

wherein each of the first and second stacked polarizing plates includes iodine.

13. The display device according to claim 12, wherein the display element is a liquid crystal element.

14. The display device according to claim 12, wherein the display element is a light emitting element.

15. The display device according to claim 12, wherein the display device is an active matrix type display device.

16. The display device according to claim 12, wherein the display device is a passive matrix type display device.

17. The display device according to claim 12, wherein the absorption axes of the first stacked polarizing plates and those of the second stacked polarizing plates are in a cross nicol state.

18. A display device comprising:

a display element sandwiched between a first light-transmissive substrate and a second light-transmissive substrate which are provided so as to face each other;

a first retardation film outside the first light-transmissive substrate;

a second retardation film outside the second light-transmissive substrate;

first stacked polarizing plates outside the first retardation film; and

second stacked polarizing plates outside the second retardation film,

wherein each of the first stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the first stacked polarizing plates are in a parallel nicol state,

wherein each of the second stacked polarizing plates has an extinction coefficient of an absorption axis which is different from that of an absorption axis of another polarizing plate, and absorption axes of the second stacked polarizing plates are in a parallel nicol state, and

wherein each of the first and second stacked polarizing plates includes iodine.

19. The display device according to claim 18, wherein the display element is a liquid crystal element.

20. The display device according to claim 18, wherein the display element is a light emitting element.

21. The display device according to claim 18, wherein the display device is an active matrix type display device.

22. The display device according to claim 18, wherein the display device is a passive matrix type display device.

23. The display device according to claim 18, wherein the retardation film is a λ

/4 plate.

24. The display device according to claim 18, wherein the absorption axes of the first stacked polarizing plates and those of the second stacked polarizing plates are in a cross nicol state.