Display panel and display device

• US 20070070282A1
• Filed: 09/20/2006
• Published: 03/29/2007
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ishihara, Shoichi, Miyachi, Koichi, Shibahara, Seiji
• Granted Patent: US 8,120,746 B2
• Time in Patent Office: Days
• US Class Current: 349/141
• CPC Class Codes: G02F 1/07 based on electro-optical liquids exhibiting Kerr effect
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• 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 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/13775 Polymer-stabilized liquid crystal layers
• CPC Class Codes: G02F 1/13781 using smectic liquid crystals G02F1/141 takes precedence
• CPC Class Codes: G02F 1/1392 using a field-induced sign-reversal of the dielectric anisotropy
• 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 display panel includes (i) a first substrate and a second substrate, which face each other, (ii) a medium layer being sandwiched between the first and second substrate, and (iii) first electrodes and second electrodes being provided on that side of the first substrate which faces the second substrate, the display panel performing display operation by generating an electric field between the first and second electrodes. The display panel is configured such that the medium layer comprises a medium that is optically isotropic when no electric field is applied thereon, and whose optical anisotropy magnitude is changeable by and according to the electric field applied thereon; and the first and second electrodes are transparent electrodes, and a distance between the first and the second electrodes is shorter than a distance between the first substrate and second substrate. This configuration attains gives the display panel high response speed and high transmissivity.

Claims

1. A display panel including (i) a first substrate and a second substrate, which face each other, (ii) a medium layer being sandwiched between the first and second substrate, and (iii) first electrodes and second electrodes being provided on that side of the first substrate which faces the second substrate, the display panel performing display operation by generating an electric field between the first and second electrodes, wherein:

the medium layer comprises a medium that is optically isotropic when no electric field is applied thereon, and whose optical anisotropy magnitude is changeable by and according to the electric field applied thereon; and

the first and second electrodes are transparent electrodes, and a distance between the first and the second electrodes is shorter than a distance between the first substrate and second substrate.

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

the first and second electrodes have such a width or widths in a direction parallel to the substrate plane that allows or allow the electric field being generated between the first and second electrodes to induce the change in the magnitude of the optical anisotropy of the medium at a position in a normal direction of the substrate plane within that region of the medium layer which overlaps at least one of the first and second electrodes when viewed in the normal direction of the substrate plane, the electric field being a parabolic electric field.

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

the first and second electrodes have a width not less than 1 μ

m but not more than 8 μ

m in the direction parallel to the substrate plane.

4. The display panel as set forth in claim 1, wherein:

the first and second electrodes are configured to apply the electric field in two or more electric field application directions when viewed in a normal direction of the substrate plane.

5. The display panel as set forth in claim 4, wherein:

two of the electric field application directions make an angle of 90 degrees±

less than 20 degrees therebetween.

6. The display panel as set forth in claim 1, comprising:

polarizers respectively provided to each of the first and second substrates, the polarizers having absorption axis directions that cross each other orthogonally, the first and second electrodes applying the electric field in an electric field application direction that makes an angle of 45 degrees±

less than 10 degrees with each of the absorption axis directions.

7. The display panel as set forth in claim 1, wherein:

at least either of the first and second electrodes is a comb-like shaped electrode having a comb-base portion and tooth portions, which are extended from the comb-base portion in a direction that makes a predetermined angle with respect to a longitudinal direction of the comb-base portion.

8. The display panel as set forth in claim 1, wherein:

the first and second electrodes are comb-like shaped electrodes having a comb-base portion and tooth portions, the tooth portions of the first and second electrodes interleaving each other by being extended from the corresponding comb-base portions in respective directions that make a predetermined angle with respect to longitudinal directions of the corresponding comb-base portions.

9. The display panel as set forth in claim 7, wherein:

the tooth portions have a wedge-like shape that is bent at a predetermined angle.

10. The display panel as set forth in claim 8, wherein:

the tooth portions have a wedge-like shape that is bent at a predetermined angle.

11. The display panel as set forth in claim 9, wherein:

the angle at which the wedge-like shape is bent is an angle of 90 degrees±

less than 20 degrees.

12. The display panel as set forth in claim 10, wherein:

the angle at which the wedge-like shape is bent is an angle of 90 degrees±

less than 20 degrees.

13. The display panel as set forth in claim 1, wherein:

at least either of the first and second electrodes has a groove section in which no electrode material exists when viewed in the normal direction of the substrate plane.

14. The display panel as set forth in claim 9, comprising:

data signal lines and scanning signal lines, which cross each other,

the first and second electrodes being provided in each pixel that are respectively provided in correspondence with each intersection of the data signal lines and scanning signal lines,

at least either of the data signal lines and the scanning signal lines being shaped to be extended along the wedge-like shape of the at least one of the first and second electrodes.

15. The display panel as set forth in claim 10, comprising:

data signal lines and scanning signal lines, which cross each other,

the first and second electrodes being provided in each pixel that are respectively provided in correspondence with each intersection of the data signal lines and scanning signal lines,

at least either of the data signal lines and the scanning signal lines being shaped to be extended along the wedge-like shape of the at least one of the first and second electrodes.

16. The display panel as set forth in claim 14, wherein:

at least either of the data signal lines and the scanning signal lines is made of one of, or an alloy of two or more of Al, Mo, Ti, W, Ta, Cr, Nd, and Cu.

17. The display panel as set forth in claim 15, wherein:

at least either of the data signal lines and the scanning signal lines is made of one of, or an alloy of two or more of Al, Mo, Ti, W, Ta, Cr, Nd, and Cu.

18. The display panel as set forth in claim 14, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal line,

the common signal lines being made of the same material as the scanning signal lines and/or the data signal lines.

19. The display panel as set forth in claim 15, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal line,

the common signal lines being made of the same material as the scanning signal lines and/or the data signal lines.

20. The display panel as set forth in claim 14, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal lines,

the common signal lines being in parallel with the scanning signal lines.

21. The display panel as set forth in claim 15, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal lines,

the common signal lines being in parallel with the scanning signal lines.

22. The display panel as set forth in claim 20, wherein:

in the direction parallel with the substrate plane, the scanning signal lines have a width smaller than a distance between the common signal lines and the scanning signal lines.

23. The display panel as set forth in claim 21, wherein:

in the direction parallel with the substrate plane, the scanning signal lines have a width smaller than a distance between the common signal lines and the scanning signal lines.

24. The display panel as set forth in claim 14, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal lines,

the common signal lines being in parallel with the data signal lines.

25. The display panel as set forth in claim 15, wherein:

the first or second electrodes are respectively connected to the corresponding data signal lines respectively via switching elements that are turned ON and OFF in accordance with a signal supplied to the corresponding scanning signal lines,

the display panel comprising;

common signal lines connected to the first or second electrodes that are not connected with the corresponding data signal lines,

the common signal lines being in parallel with the data signal lines.

26. The display panel as set forth in claim 24, wherein:

in the direction parallel with the substrate plane, the data signal lines have a width smaller than a distance between the common signal lines and the data signal lines.

27. The display panel as set forth in claim 25, wherein:

in the direction parallel with the substrate plane, the data signal lines have a width smaller than a distance between the common signal lines and the data signal lines.

28. The display panel as set forth in claim 1, comprising:

a third electrode or third electrodes provided to the second substrate.

29. The display panel as set forth in claim 28, wherein:

the third electrode or third electrodes have a potential that is fixed to a constant value.

30. The display panel as set forth in claim 28, wherein:

the third electrode or third electrodes have a shape that does not overlap the first and second electrodes when viewed in the normal direction of the substrate plane.

31. The display panel as set forth in claim 28, wherein:

the third electrode or third electrodes are transparent electrodes.

32. The display panel as set forth in claim 28, wherein:

the third electrode or third electrodes function as heating means for heating the medium layer.

33. The display panel as set forth in claim 1, wherein:

the medium has an orientational order smaller than a visible light wavelength when no electric field is applied thereon.

34. The display panel as set forth in claim 1, wherein:

a selective reflection wavelength band or a helical pitch of the medium is not more than 400 nm.

35. A display device comprising:

a display panel including (i) a first substrate and a second substrate, which face each other, (ii) a medium layer being sandwiched between the first and second substrate, and (iii) first electrodes and second electrodes being provided on that side of the first substrate which faces the second substrate, the display panel performing display operation by generating an electric field between the first and second electrodes, wherein the medium layer includes a medium that is optically isotropic when no electric field is applied thereon, and whose optical anisotropy magnitude is changeable by and according to the electric field applied thereon; and

wherein the first and second electrodes are transparent electrodes, and a distance between the first and the second electrodes is shorter than a distance between the first substrate and second substrate.