Foldable display device including spacers in folding area
A foldable display device includes a display panel configured to be folded around a folding axis. The display panel includes spacers disposed in a non-folding area and a folding area, and the spacers may have different sizes or densities. Dimensions of the spacers may be in a direction of the folding axis or intersect the direction of the folding axis. The display panel also includes pixels in an active area that overlap with the spacers, which may help reduce peeling, cracking, defects, or reduction in pixel brightness due to folding of the display device.
1 . A foldable display device comprising:
a display panel configured to be folded around a folding axis, the display panel including:
at least one transistor in a folding area, each of the at least one transistor electrically connected to a light emitting element;
a first plurality of spacers disposed in a non-folding area; and
a second plurality of spacers disposed in the folding area and on the at least one transistor, the second plurality of spacers having different sizes than the first plurality of spacers, each of the second plurality of spacers having a first dimension and a second dimension greater than the first dimension, the second dimensions of the second plurality of spacers each in a direction of the folding axis, each of the second plurality of spacers does not overlap an area of the light emitting element that emits light.
2 . The foldable display device of claim 1 , wherein the second dimension of each spacer of the second plurality of spacers is the greatest dimensions of said each spacer.
3 . The foldable display device of claim 1 , wherein the first dimension of each spacer of the second plurality of spacers is the smallest dimensions of said each spacer, the first dimensions each intersecting the direction of the folding axis.
4 . The foldable display device of claim 1 , wherein the display panel further comprises:
a planarization layer on a flexible substrate; and
a plurality of pixels on the planarization layer, the planarization layer including a contact hole for each of the plurality of pixels, each contact hole overlapping a portion of a corresponding one of the second plurality of spacers.
5 . The foldable display device of claim 4 , wherein the display panel is an organic light emitting display panel and each of the plurality of pixels comprises:
an anode connected to a drain electrode of a transistor of a pixel via the contact hole of the pixel, the corresponding one of the second plurality of spacers overlapping the transistor; and
a cathode overlapping the anode and the corresponding one of the second plurality of spacers.
6 . The foldable display device of claim 5 , further comprising:
an insulating layer on anodes of the plurality of pixels, the second plurality of spacers disposed between the insulating layer and cathodes of the plurality of pixels.
7 . The foldable display device of claim 6 , further comprising:
an encapsulation unit on the cathodes of the plurality of pixels, the encapsulation unit having a height greater than heights of the first plurality of spacers and the second plurality of spacers.
8 . The foldable display device of claim 1 , wherein the second plurality of spacers are arranged in a plurality of columns in the direction of the folding axis, each of the plurality of columns including a subset of the second plurality of spacers spaced from each other.
9 . The foldable display device of claim 8 , wherein at least one of the plurality of columns overlaps the folding axis.
10 . The foldable display device of claim 8 , wherein the plurality of columns include at least a first column of spacers having a first area and a second column of spacers having a second area greater than the first area.
11 . The foldable display device of claim 10 , wherein the first column of spacers and the second column of spacers are disposed on a side of the display panel applied with a compressive force responsive to folding of the foldable display device, the folding axis positioned closer to the first column of spacers than to the second column of spacers.
12 . The foldable display device of claim 10 , wherein the first column of spacers and the second column of spacers are disposed on a side of the display panel applied with a tensile force responsive to folding of the foldable display device, the folding axis positioned closer to the second column of spacers than to the first column of spacers.
13 . The foldable display device of claim 10 , wherein a third area of the first plurality of spacers equals either the first area or the second area.
14 . The foldable display device of claim 10 , wherein the plurality of columns further include a third column of spacers having a third area different than each of the first area and the second area.
15 . The foldable display device of claim 1 , wherein each of the first plurality of spacers has a third dimension and a fourth dimension greater than the third dimension, the fourth dimensions of the first plurality of spacers each intersecting with the direction of the folding axis.
16 . The foldable display device of claim 1 , wherein the first plurality of spacers and the second plurality of spacers have a trapezoidal cross-section with tapered thickness, a first base angle of the trapezoidal cross-section of the first plurality of spacers smaller than a second base angle of the trapezoidal cross-section of the second plurality of spacers.
17 . The foldable display device of claim 1 , wherein the display panel is further configured to be folded around another folding axis distinct from the folding axis.
18 . A foldable display device comprising:
a display panel configured to be folded around a folding axis, the display panel including:
at least one transistor in a folding area, each of the at least one transistor electrically connected to a light emitting element;
a first plurality of spacers disposed in a non-folding area; and
a second plurality of spacers disposed in the folding area and on the at least one transistor, a first density including a number of the first plurality of spacers in a portion of the non-folding area is less than a second density including a number of the second plurality of spacers in a portion of the folding area that is a same size as the portion of the non-folding area, each of the second plurality of spacers does not overlap an area of the light emitting element that emits light.
19 . The foldable display device of claim 18 , wherein the second density number of the second plurality of spacers is at least twice the first density number of the first plurality of spacers.
20 . The foldable display device of claim 18 , wherein the display panel further includes:
a plurality of pixels disposed in an active area, each of the plurality of pixels overlapping with at least one of the first plurality of spacers or the second plurality of spacers.
21 . The foldable display device of claim 20 , wherein the first plurality of spacers and the second plurality of spacers account for 0.25% to 1.25% of an area of the active area.
22 . The foldable display device of claim 21 , wherein the first plurality of spacers accounts for 0.45% to 0.5% of the area of the active area.
23 . The foldable display device of claim 21 , wherein the second plurality of spacers accounts for 0.45% to 1% of the area of the active area.
24 . A foldable display device comprising:
a display panel including:
at least one transistor in a folding area;
a first plurality of spacers disposed in a non-folding area;
a second plurality of spacers disposed in the folding area and on the at least one transistor, the second plurality of spacers having different size or density than the first plurality of spacers;
a plurality of pixels disposed in an active area, each of the plurality of pixels overlapping with at least one of the first plurality of spacers or the second plurality of spacers, wherein each of the at least one transistor is electrically connected to a corresponding light emitting element of one of the plurality of pixels, each of the second plurality of spacers does not overlap an area of the light emitting element that emits light.
25. The foldable display device of claim 24 , wherein the display panel includes an active area and a non-active area, the active area including the plurality of pixels in an array, wherein each of the plurality of pixels include a circuit unit that comprises a driving thin film transistor.
26. The foldable display device of claim 25 , wherein at least one driving thin film transistor overlaps with at least one of the first plurality of spacers or the second plurality of spacers.
27. The foldable display device of claim 25 , further comprising: a driving circuit in the non-active area.
28. The foldable display device of claim 25 , wherein the folding area includes a part of the active area and a part of the non-active area.
29. The foldable display device of claim 28 , wherein the folding area is in folded around a folding axis.
30. The foldable display device of claim 28 , wherein the folding area is out-folded around a folding axis.
31. The foldable display device of claim 28 , where non-folding areas of the display panel overlap each other while the display panel is folded.
32. The foldable display device of claim 24 , wherein the display panel further comprises:
a substrate that is flexible; and
a back plate disposed under the substrate.
33. The foldable display device of claim 26 , further comprising:
a planarization layer on at least one driving thin film transistor; and
an organic light emitting element on the planarization layer, the organic light-emitting element including an anode. an organic light-emitting layer on the anode, and a cathode on the organic light emitting layer.
34. The foldable display device of claim 33 . further comprising:
a bank on a part of the anode and the planarization layer,
wherein the first plurality of spacers and the second plurality of spacers are on the bank.
35. The foldable display device of claim 33 . further comprising:
a color filter on the organic light emitting element and overlapping the organic light-emitting layer.
36. The foldable display device of claim 33 . further comprising:
an encapsulation unit on the cathode. the encapsulation unit comprising an inorganic layer and an organic layer on the inorganic layer.
37. The foldable display device of claim 24 , wherein the first plurality of spacers have a total number and position that is respectively different from a total number and position of the second plurality of spacers.
38. The foldable display device of claim 24 , wherein a shape of at least one of the first plurality of spacers is different from a shape of at least one of the second plurality of spacers.
39. The foldable display device of claim 38 . wherein the shape of the at least one of the second plurality of spacers is a polygonal shape.
40. The foldable display device of claim 24 , wherein at least one of the first plurality of spacers has a length that extends in a direction perpendicular to a folding axis and is greater than a length that extends in a direction that is parallel to the folding axis.
41. The foldable display device of claim 36 , wherein a thickness of the second plurality of spacers is less than a thickness of the encapsulation unit.
42. The foldable display device of claim 24 , wherein at least one first spacer of the first plurality of spacers has an upper surface having a width that is less than a width of a lower surface of the at least one first spacer and at least one second spacer of the second plurality of spacers has an upper surface having a width that is less than a width of a lower surface of the at least one second spacer.
43. The foldable display device of claim 24 , wherein a material of the first plurality of spacers is a same as a material of the second plurality of spacers, and the first plurality of spacers and the second plurality of spacers are on a same layer.
44. The foldable display device of claim 42 , wherein an inclined surface is between the upper surface and the lower surface of the at least one first spacer and an inclined surface is between the upper surface and the lower surface of the at least one second spacer,
wherein a base angle between the lower surface and the inclined surface of the at least one first spacer is different from a base angle between the lower surface and the inclined surface of the at least one second spacer.
45. The foldable display device of claim 44 , wherein the base angle of the at least one second spacer is greater than the base angle of the at least one first spacer.
46. The foldable display device of claim 33 . wherein the second plurality of spacers includes a first subset of spacers and a second subset of spacers,
wherein a size at least one of the first subset of spacers in a direction along a folding axis is different from a size of at least one of the second subset of spacers in the direction along the folding axis.
47. The foldable display device of claim 46 , wherein at least one of the first subset of spacers and the second subset of spacers overlaps a contact hole in the planarization layer.
48. The foldable display device of claim 46 , wherein at least one of the first subset of spacers and the second subset of spacers overlaps with a part of the anode.
49. The foldable display device of claim 46 , wherein at least one of the first subset of spacers has a size in a direction perpendicular to the folding axis that is different from a size of at least one of the second subset of spacers in the direction perpendicular to the folding axis.
50. The foldable display device of claim 46 , at least one spacer of the first subset of spacers and the second subset of spacers has a width that is shorter than a length of the at least one spacer.
51. The foldable display device of claim 50 , wherein the width extends in a same direction as the folding axis.
52. The foldable display device of claim 46 , wherein the second plurality of spacers are arranged in a plurality of columns in the direction of the folding axis.
53. The foldable display device of claim 52 , wherein at least one of the plurality of columns overlaps the folding axis.
54. The foldable display device of claim 24 , wherein the display panel is further configured to be folded around another folding axis that is different from the folding axis.