Liquid crystal display device having a pair of electrodes over an inner side of a substrate of a liquid crystal element in which a stack of polarizers on the outer side of a substrate are provided and arranged between a pair of protective layers such that no protective layer is located between the stacked polarizers

• US 7,855,770 B2
• Filed: 06/11/2010
• Issued: 12/21/2010
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Egi, Yuji, Nishi, Takeshi, Ishitani, Tetsuji
• Primary Examiner(s): HEYMAN, JOHN S
• Application Number:
  US12/814,027
• Publication Number:
  US 20100245712A1
• Time in Patent Office: 193 Days
• Field of Search: 349 96-106, 349/141
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 2203/04 wavelength independent
• CPC Class Codes: G02F 2203/64 Normally black display, i.e. the off state being black

Abstract

To provide a display device having a high contrast ratio by a simple and easy method and to manufacture a high-performance display device at low cost, in a display device having a display element between a pair of light-transmitting substrates, layers each including a polarizer having different wavelength distribution of extinction coefficient from each other with respect to the absorption axes are stacked and provided on an outer side of the light-transmitting substrates. Further, a retardation plate may be provided between the stacked polarizers.

Claims

1. A liquid crystal display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate which are disposed to face each other;

a liquid crystal element sandwiched between the first light-transmitting substrate and the second light-transmitting substrate;

a pair of electrodes over an inner side of the second light-transmitting substrate;

a layer including stacked polarizers on an outer side of the first light-transmitting substrate or the second light-transmitting substrate; and

liquid crystal molecules adjacent to the pair of electrodes,

wherein the stacked polarizers are arranged so that their absorption axes are deviated from a parallel Nicols state,

wherein the stacked polarizers are provided between a pair of protective layers arranged such that no protective layer is located between the stacked polarizers, and

wherein the liquid crystal molecules are configured to be switched by a lateral electric field between the pair of electrodes.

4. The liquid crystal display device according to claim 1, wherein a distribution of a degree to which a first one of the stacked polarizers absorbs light across a band of wavelengths differs from a distribution of a degree to which a second one of the stacked polarizers absorbs light across the band of wavelengths.

7. The liquid crystal display device according to claim 1, wherein a method of the lateral electric field is selected from IPS mode or FFS mode.

10. The liquid crystal display device according to claim 7, wherein the pair of electrodes is provided on the second light-transmitting substrate in IPS mode.

13. The liquid crystal display device according to claim 7, further comprising in FFS mode:

an insulating film over the inner side of the second light-transmitting substrate,

wherein a first electrode of the pair of electrodes is over the inner side of the second light-transmitting substrate,

wherein a second electrode of the pair of electrodes is over the first electrode,

wherein the second electrode overlaps the first electrode, and

wherein the insulating film is interposed between the first electrode and the second electrode.

16. The liquid crystal display device according to claim 10, wherein a shape of the pair of electrodes is selected from an undulating wave shape, a concentric circular opening shape, a comb-like shape and partially overlapped with each other, or a comb-like shape in which the electrodes are meshed with each other.

19. The liquid crystal display device according to claim 13, wherein shape of the second electrode over the first electrode is selected from a bent dog-legged shape, a concentric circular shape, a comb-like shape in which the electrodes are meshed with other, or a comb-like shape.

2. A liquid crystal display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate which are disposed to face each other;

a liquid crystal element sandwiched between the first light-transmitting substrate and the second light-transmitting substrate;

a pair of electrodes over an inner side of the second light-transmitting substrate;

a first layer including first stacked polarizers on an outer side of the first light-transmitting substrate;

a second layer including second stacked polarizers on an outer side of the second light-transmitting substrate; and

liquid crystal molecules adjacent to the pair of electrodes,

wherein the first stacked polarizers are arranged so that their absorption axes are deviated from a parallel Nicols state,

wherein the second stacked polarizers are arranged so that their absorption axes are in a parallel Nicols state,

wherein the first stacked polarizers are provided between a first pair of protective layers arranged such that no protective layer is located between the first stacked polarizers, and the second stacked polarizers are provided between a second pair of protective layers, and

wherein the liquid crystal molecules are configured to be switched by a lateral electric field between the pair of electrodes.

5. The liquid crystal display device according to claim 2, wherein a distribution of a degree to which a first one of the first stacked polarizers absorbs light across a first band of wavelengths differs from a distribution of a degree to which a second one of the first stacked polarizers absorbs light across the first band of wavelengths, and

wherein a distribution of a degree to which a first one of the second stacked polarizers absorbs light across a second band of wavelengths differs from a distribution of a degree to which a second one of the second stacked polarizers absorbs light across the second band of wavelengths.

8. The liquid crystal display device according to claim 2, wherein a method of the lateral electric field is selected from IPS mode or FFS mode.

11. The liquid crystal display device according to claim 8, wherein the pair of electrodes is provided on the second light-transmitting substrate in IPS mode.

14. The liquid crystal display device according to claim 8, further comprising in FFS mode:

an insulating film over the inner side of the second light-transmitting substrate,

wherein a first electrode of the pair of electrodes is over the inner side of the second light-transmitting substrate,

wherein a second electrode of the pair of electrodes is over the first electrode,

wherein the second electrode overlaps the first electrode, and

wherein the insulating film is interposed between the first electrode and the second electrode.

17. The liquid crystal display device according to claim 11, wherein a shape of the pair of electrodes is selected from an undulating wave shape, a concentric circular opening shape, a comb-like shape and partially overlapped with each other, or a comb-like shape in which the electrodes are meshed with each other.

20. The liquid crystal display device according to claim 14, wherein shape of the second electrode over the first electrode is selected from a bent dog-legged shape, a concentric circular shape, a comb-like shape in which the electrodes are meshed with other, or a comb-like shape.

22. The liquid crystal display device according to claim 2, further comprising:

a light source on an outer side of the second stacked polarizers.

24. The liquid crystal display device according to claim 22, wherein the light source is light emitting diode (LED).

26. The liquid crystal display device according to claim 24, wherein the light emitting diode (LED) is configured to be driven by a successive additive color mixture method (a filed sequential method).

3. A liquid crystal display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate which are disposed to face each other;

a liquid crystal element sandwiched between the first light-transmitting substrate and the second light-transmitting substrate;

a pair of electrodes over an inner side of the second light-transmitting substrate;

a first layer including first stacked polarizers on an outer side of the first light-transmitting substrate;

a second layer including second stacked polarizers on an outer side of the second light-transmitting substrate; and

liquid crystal molecules adjacent to the pair of electrodes,

wherein the first stacked polarizers are arranged so that their absorption axes are deviated from a parallel Nicols state,

wherein the second stacked polarizers are arranged so that their absorption axes are in a parallel Nicols state,

wherein the first layer including the first stacked polarizers has a first polarizer and a second polarizer which are sequentially stacked from the first light-transmitting substrate, and

wherein the first stacked polarizers and the second stacked polarizers are arranged so that their absorption axes are in a crossed Nicols state,

wherein the first stacked polarizers are provided between a first pair of protective layers arranged such that no protective layer is located between the first stacked polarizers, and the second stacked polarizers are provided between a second pair of protective layers, and

wherein the liquid crystal molecules are configured to be switched by a lateral electric field between the pair of electrodes.

6. The liquid crystal display device according to claim 3, wherein a distribution of a degree to which a first one of the first stacked polarizers absorbs light across a first band of wavelengths differs from a distribution of a degree to which a second one of the first stacked polarizers absorbs light across the first band of wavelengths, and

wherein a distribution of a degree to which a first one of the second stacked polarizers absorbs light across a second band of wavelengths differs from a distribution of a degree to which a second one of the second stacked polarizers absorbs light across the second band of wavelengths.

9. The liquid crystal display device according to claim 3, wherein a method of the lateral electric field is selected from IPS mode or FFS mode.

12. The liquid crystal display device according to claim 9, wherein the pair of electrodes is provided on the second light-transmitting substrate in IPS mode.

15. The liquid crystal display device according to claim 9, further comprising in FFS mode:

an insulating film over the inner side of the second light-transmitting substrate,

wherein a first electrode of the pair of electrodes is over the inner side of the second light-transmitting substrate,

wherein a second electrode of the pair of electrodes is over the first electrode,

wherein the second electrode overlaps the first electrode, and

wherein the insulating film is interposed between the first electrode and the second electrode.

18. The liquid crystal display device according to claim 12, wherein shape of the pair of electrodes is selected from an undulating wave shape, a concentric circular opening shape, a comb-like shape and partially overlapped with each other, or a comb-like shape in which the electrodes are meshed with each other.

21. The liquid crystal display device according to claim 15, wherein shape of the second electrode over the first electrode is selected from a bent dog-legged shape, a concentric circular shape, a comb-like shape in which the electrodes are meshed with other, or a comb-like shape.

23. The liquid crystal display device according to claim 3, further comprising:

a light source on an outer side of the second stacked polarizers.

25. The liquid crystal display device according to claim 23, wherein the light source is light emitting diode (LED).

27. The liquid crystal display device according to claim 25, wherein the light emitting diode (LED) is configured to be driven by a successive additive color mixture method (a filed sequential method).