Organic light emitting display

Korean Patent Application No. 10-2015-0010844, filed on Jan. 22, 2015, in the Korean Intellectual Property Office, and entitled: “Organic Light Emitting Display,” is incorporated by reference herein in its entirety.

1. Field

Embodiments relate generally to an organic light emitting display that is bendable.

2. Description of the Related Art

Flat panel displays (FPDs) include an organic light emitting display (OLED), a liquid crystal display (LCD), and a plasma display panel (PDP).

Embodiments are directed to an organic light emitting display, including a substrate including a first region and a second region adjacent to the first region, a plurality of first organic light emitting elements located in the first region, a plurality of second organic light emitting elements located in the second region, and a plurality of first thin film transistors located in the second region and connected to the first organic light emitting elements in the first region to drive the first organic light emitting elements. The first thin film transistors do not overlap with the first organic light emitting elements.

The first region may not overlap the first thin film transistors.

The first region may be a bendable region.

The first region may extend from one lateral end to another lateral end of the substrate. The first organic light emitting elements may be in a form of three or more columns and rows.

The second region may be in a form of two second regions on the substrate. The first region is between the two second regions.

The organic light emitting display may further include a plurality of second thin film transistors located in the two second regions and connected to the second organic light emitting elements. The first thin film transistors and the second thin film transistors may overlap with at least one of the second organic light emitting elements.

Each of the first thin film transistors and the second thin film transistors may include a source electrode, a drain electrode, and a gate electrode. The drain electrode of the first thin film transistors may be longer than a drain electrode of the second thin film transistor.

The drain electrode of the first thin film transistor extends from the first region to the second region.

The first region may be a region where stress is concentrated when the organic light emitting display is bent.

The first region may include an inorganic insulating layer having openings and an organic material insulating layer that covers the openings in the inorganic insulating layer.

The first region may include a plurality of the first regions. The substrate may include a plurality of third regions, the third regions including third organic light emitting elements and third thin film transistors, the third thin film transistors overlapping with the third organic light emitting elements to drive the third organic light emitting elements.

The third region may include first thin film transistors connected to the first organic light emitting elements to drive the first organic light emitting elements.

The third regions may be between the first regions.

The first region and the third region may be bendable regions.

Features will become apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which:

FIG. 1 illustrates a top plan view of an organic light emitting display according to a an exemplary embodiment.

FIG. 2 illustrates a side view depicting a folded state of the organic light emitting display of FIG. 1 .

FIG. 3 illustrates a circuit diagram of the organic light emitting display according to the exemplary embodiment.

FIG. 4 illustrates a cross-sectional view of the organic light emitting display according to the exemplary embodiment.

FIG. 5 illustrates an enlarged top plan view of the organic light emitting display according to the exemplary embodiment.

FIG. 6 illustrates a top plan view of an organic light emitting display according to another exemplary embodiment.

FIG. 7 illustrates a cross-sectional view of the organic light emitting display according to the exemplary embodiment illustrated in FIG. 6 .

FIG. 8 illustrates a top plan view of an organic light emitting display according to another exemplary embodiment.

FIG. 9 illustrates a circuit diagram of the organic light emitting display according to the exemplary embodiment illustrated in FIG. 8 .

Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or element, it can be directly on the other layer or element, or intervening layers may also be present. Further, it will be understood that when a layer or element is referred to as being “between” two layers or elements, it can be the only layer or element between the two layers, or one or more intervening layers or elements may also be present. Like reference numerals refer to like elements throughout.

An organic light emitting display according to an exemplary embodiment will now be described in detail with reference to FIGS. 1 and 2 .

FIG. 1 illustrates a top plan view of an organic light emitting display according to an exemplary embodiment, and FIG. 2 illustrates a side view depicting a folded state of the organic light emitting display of FIG. 1 .

Referring to FIGS. 1 and 2 (and also FIGS. 3 to 5 ), an organic light emitting display 100 according to an exemplary embodiment includes: a substrate (SUB); and a plurality of first organic light emitting elements 10 , a plurality of first thin film transistors TR 1 , a plurality of second organic light emitting elements 20 , and a plurality of second thin film transistors TR 2 formed on the substrate (SUB).

A first region S 110 and a second region S 120 adjacent to the first region S 110 are formed on the substrate (SUB). The first region S 110 is foldable or bendable based on a reference line L 1 passing through the center of a length direction (Y-axis direction) of the substrate (SUB). As shown in FIG. 2 , the first region S 110 may be formed as bent regions that are symmetrical to each other based on the reference line L 1 . The first region S 110 may be formed, for example, at the center of the length direction of the substrate (SUB). In some implementations, the first region S 110 may be any region where stress is concentrated when bent.

The first region S 110 may extend from one lateral end to the other lateral end along a width direction (X-axis direction) of the substrate (SUB) direction. Two second regions S 120 may be formed on the substrate (SUB), and the first region S 110 may be disposed between the second regions S 120 . The second region S 120 may be fixed by a hard frame so as to not be bendable.

The organic light emitting display according to exemplary embodiments will be described more fully with reference to FIGS. 3, 4, and 5 .

FIG. 3 illustrates a circuit diagram of the organic light emitting display according to this exemplary embodiment, FIG. 4 illustrates a cross-sectional view of the organic light emitting display according to this exemplary embodiment, and FIG. 5 is an enlarged top plan view of the organic light emitting display according to this exemplary embodiment.

Referring to FIG. 3 , a plurality of scan lines SLn, a plurality of data lines DLm, a plurality of first organic light emitting elements 10 , a plurality of first thin film transistors TR 1 , a plurality of second organic light emitting elements 20 , and a plurality of second thin film transistors TR 2 may be formed on the substrate (SUB).

The organic light emitting display 100 according to this exemplary embodiment is shown to include the substrate (SUB), the scan lines SLn, the data lines DLm, the first organic light emitting elements 10 , the first thin film transistors TR 1 , the second organic light emitting elements 20 , and the second thin film transistors TR 2 . In some implementations, the organic light emitting display 100 according to the this exemplary embodiment may further include a driving power line, an initial power line, a capacitor, etc.

The substrate (SUB) may have a rectangular shape in a plan view, and may be bendable in a length direction (Y-axis direction) as a direction that is parallel with long sides of the substrate (SUB). The substrate (SUB) may contain a suitable material that allows the substrate (SUB) to be bent. For example, the substrate (SUB) may contain one or more of a polymer material such as polyimide, a metal material, and an inorganic material. The substrate (SUB) may have a film shape.

The directions in which the scan lines SLn extend may vary. For example, as shown in FIG. 3 , each of the scan lines SLn may extend in a horizontal direction (X-axis direction), and the scan lines SLn may be spaced apart in a vertical direction. The scan lines SLn may be connected to the thin film transistors TR 1 and TR 2 , and the organic light emitting elements (organic light emitting diodes) may emit light depending on signals of the scan lines SLn.

The direction in which the data lines DLm extend may vary. As illustrated in FIG. 3 , each of the data lines DLm may extend in a vertical direction (Y-axis direction), and the data lines DLm may be spaced apart in a horizontal direction. The data lines DLm respectively cross the scan lines SLn in an insulated manner. The data lines DLm may be connected to the thin film transistors TR 1 and TR 2 , and the organic light emitting elements 10 and 20 may emit light depending on signals of the data lines DLm.

A cross-section structure of the organic light emitting display will be described with reference to FIG. 4 .

A first thin film transistor TR 1 and a second thin film transistor TR 2 may have the same configuration except for being respectively disposed in different regions. Accordingly, the description of the first thin film transistor TR 1 may also apply to the second thin film transistor TR 2 .

The first thin film transistor TR 1 may include an active layer AC, a gate electrode GE, a source electrode SE, and a drain electrode DE; a first insulating layer IL 1 disposed between the gate electrode GE and the active layer AC; and a second insulating layer IL 2 disposed between the gate electrode GE and the source electrode SE. The source electrode SE and the drain electrode DE may be covered by a third insulating layer IL 3 . The drain electrode DE of the first thin film transistor TR 1 may be connected to a first electrode E 1 of the first organic light emitting element 10 . The drain electrode DE of the first thin film transistor TR 1 may be formed to be longer than the drain electrode DE of the second thin film transistor TR 2 . The drain electrode DE of the first thin film transistor TR 1 may extend from the first region S 110 to the second region S 120 .

Each of the first insulating layer IL 1 , the second insulating layer IL 2 , and the third insulating layer IL 3 may be a laminate including at least one of an organic layer and an inorganic layer.

The active layer AC may be made of polysilicon, an oxide semiconductor, or the like. The active layer AC may include a channel region in which impurities are not doped, and a source region and a drain region formed at two respective sides of the channel region, in which impurities are doped. The impurities may vary according to a kind of thin film transistor. For example, the impurities may be N-type impurities or P-type impurities. In the case where the active layer AC is formed of an oxide semiconductor, which may be vulnerable to an external environment such as exposure at a high temperature, a separate passivation layer may be added in order to protect the oxide semiconductor.

A pixel circuit that drives an organic light emitting element may have various types of suitable configurations. For example, the pixel circuit may include a plurality of thin film transistors and one or more capacitors.

The first organic light emitting element 10 may include the first electrode E 1 connected to the drain electrode DE of the first thin film transistor TR 1 , an organic light emitting layer OL disposed on the first electrode E 1 , and a second electrode E 2 disposed on the organic light emitting layer OL.

The first electrode E 1 may be an anode that is a hole injection electrode. The first electrode E 1 may be an optically reflective electrode or an optically transmissible electrode. In some implementations, the first electrode E 1 may be a cathode that is an electron injection electrode.

The organic light emitting layer OL may be disposed on the first electrode E 1 . The organic light emitting layer OL may be made of a low-molecule organic material or a high-molecule organic material such as poly(3,4-ethylenedioxythiophene) (PEDOT). The organic light emitting layer OL may include a red organic emission layer that emits red light, a green organic emission layer that emits green light, and a blue organic emission layer that emits blue light. The red organic emission layer, the green organic emission layer, and the blue organic emission layer may be formed in a red pixel, a green pixel, and a blue pixel, respectively, thereby realizing various color images. The organic light emitting layer OL may realize the color image by laminating the red organic emission layer, the green organic emission layer, and the blue organic emission layer together in the red pixel, the green pixel, and the blue pixel, and forming a red color filter, a green color filter, and a blue color filter for each pixel. As another example, white organic emission layers emitting white light may be formed as the organic light emitting layer OL, and a red color filter, a green color filter, and a blue color filter may be formed to provide the red pixel, the green pixel, and the blue pixel, thereby implementing the color image. In the case of implementing the color image by using the white organic emission layer as the organic light emitting layer OL and the color filters, a process of using a deposition mask to deposit the red organic emission layer, the green organic emission layer, and the blue organic emission layer on respective pixels, that is, on the red pixel, the green pixel, and the blue pixel, may be omitted. The white organic emission layer as the organic light emitting layer OL may be formed to have a single organic emission layer, and may further include a configuration in which a plurality of organic emission layers are laminated to emit white light. For example, the organic light emitting layer OL may include a configuration in which at least one yellow organic emission layer and at least one blue organic emission layer are combined to emit white light, a configuration in which at least one cyan organic emission layer and at least one red organic emission layer are combined to emit white light, and a configuration in which at least one magenta organic emission layer and at least one green organic emission layer are combined to emit white light.

The second electrode E 2 may be disposed on the organic light emitting layer OL. The second electrode E 2 may be a cathode that is an electron injection electrode. The second electrode E 2 may be an optically reflective electrode or an optically transmissible electrode. The second electrode E 2 may be disposed on the entire display area of the substrate (SUB) to cover the organic light emitting layer OL. In some implementations, the second electrode E 2 may be a anode that is a hole injection electrode.

Disposition of the organic light emitting elements and the thin film transistors will be described with reference to FIG. 5 .

First organic light emitting elements 10 may be disposed in the first region S 110 , and second organic light emitting elements 20 , second thin film transistors TR 2 connected to the second organic light emitting elements 20 to drive the second organic light emitting elements 20 , and first thin film transistors TR 1 connected to the first organic light emitting elements 10 to drive first organic light emitting elements 10 , may be disposed in the second region S 120 . The first thin film transistors TR 1 may not be formed in the first region S 110 , but the first organic light emitting elements 10 may be formed in the first region S 110 . Thus the first thin film transistors TR 1 may not overlap the first region S 110 .

The organic light emitting elements 10 and 20 may be disposed on the substrate (SUB) in a lattice form with columns and rows. The first organic light emitting elements 10 may be disposed in a form with three or more columns and rows in the first region S 110 . Accordingly, a region in which three or more first organic light emitting elements 10 are continuously disposed may not overlap with the thin film transistors TR 1 and TR 2 .

As shown in FIG. 5 , the second region S 120 may include an overlapped region S 121 in which the second organic light emitting elements 20 , the first thin film transistors TR 1 , and the second thin film transistors TR 2 are disposed together, and a single region S 122 in which only the second organic light emitting elements 20 and the second thin film transistors TR 2 are disposed. In the overlapped region S 121 , the first thin film transistors TR 1 and the second thin film transistors TR 2 are overlapped with pixel areas formed by the second organic light emitting elements 20 .

An interval between the thin film transistors TR 1 and TR 2 in the overlapped region S 121 may be narrower than the interval in the single region S 122 . For example, there may be 120 thin film transistors TR 1 and TR 2 disposed in a space occupied by 100 pixel areas in the overlapped region S 121 . 100 thin film transistors among 120 thin film transistors may be the second thin film transistors TR 2 and 20 thin film transistors thereof may be the first thin film transistor TR 1 . Accordingly, in the overlapped region, the first thin film transistors TR 1 and the second thin film transistors TR 2 are overlapped with at least one of the second organic light emitting elements 20 .

As described above, only the first organic light emitting elements 10 are disposed in the first region S 110 , such that deterioration of the first thin film transistors TR 1 may be prevented when the organic light emitting display is bent, and the first region S 110 may be easily bent.

An organic light emitting display according to another exemplary embodiment will be now described with reference to FIGS. 6 and 7 .

Parts that are different from the exemplary embodiment illustrated in FIGS. 1 to 5 will be described, and parts that are the same as in the exemplary embodiment illustrated in FIGS. 1 to 5 are described above with reference to FIGS. 1 to 5 . For better comprehension and ease of description, the constituent elements of this exemplary embodiment that are the same as the previous exemplary embodiment will have the same reference numerals.

FIG. 6 illustrates a top plan view of an organic light emitting display according to this exemplary embodiment, and FIG. 7 is a cross-sectional view of the organic light emitting display illustrated in FIG. 6 .

Referring to FIGS. 6 and 7 , an organic light emitting display 200 according to this exemplary embodiment may include a substrate (SUB), and a plurality of organic light emitting elements 10 and 20 and thin film transistors TR 1 and TR 2 formed on the substrate (SUB). A first region S 210 and second regions S 220 may be formed on the substrate (SUB). The first region S 210 may be disposed between the second regions S 220 and may be formed as a bendable region. A plurality of openings OP 1 may be formed in the first region S 210 . The openings OP 1 may be formed in a first insulating layer IL 1 and a second insulating layer IL 2 made of an inorganic material. The openings OP 1 may be formed to have a polygonal, circular, or elliptical cross-section. A third insulating layer IL 3 made of an organic material may be formed on the second insulating layer IL 2 to cover the openings OP 1 .

According to this exemplary embodiment, the plurality of openings OP 1 may be formed in the first region S 210 . Accordingly, damage to the first insulating layer IL 1 and the second insulating layer IL 2 made of the inorganic material due to stress that may occur when the substrate (SUB) is bent may be minimized. In addition, the first region S 210 may be easily bent. Accordingly, stress applied to the second region S 220 may be decreased, thereby protecting the thin film transistors.

An organic light emitting display according to another exemplary embodiment will now be described with reference to FIGS. 8 and 9 .

Parts that are different from the exemplary embodiment illustrated in FIGS. 1 to 5 will be described, and parts that are the same as in the exemplary embodiment illustrated in FIGS. 1 to 5 are described above with reference to FIGS. 1 to 5 . For better comprehension and ease of description, the constituent elements of the this exemplary embodiment that are the same as the previous exemplary embodiments will have the same reference numerals.

FIG. 8 illustrates a top plan view of an organic light emitting display, and FIG. 9 is a circuit diagram of the organic light emitting display.

Referring to FIGS. 8 and 9 , an organic light emitting display 300 according to the this exemplary embodiment includes a substrate (SUB), and a plurality of first organic light emitting elements 10 , a plurality of first thin film transistors TR 1 , a plurality of second organic light emitting elements 20 , a plurality of second thin film transistors TR 2 , a plurality of third organic light emitting elements 30 , and a plurality of third thin film transistors TR 3 , which are formed on the substrate (SUB).

First regions S 310 , second regions S 320 adjacent to the first regions S 310 , and third regions S 330 disposed between the first regions may be formed on the substrate (SUB). For example, two second regions S 320 may be formed on the substrate (SUB), and the first regions S 310 and the third regions S 330 may be disposed between the two second regions S 320 . The plurality of first regions S 310 may be formed on the substrate (SUB), and the third regions S 330 are disposed between the first regions S 310 .

The second regions S 320 may be fixed by a hard frame so as to not be bendable. The first regions S 310 and the third regions S 330 may be foldable or bendable based on a reference line L 1 passing through the center of a length direction (Y-axis direction) of the substrate (SUB). As shown in FIG. 2 , the first regions S 310 and the third regions S 330 may be formed as bent or bendable regions, and the bent or bendable regions may be symmetrical to each other based on the reference line L 1 .

A plurality of scan lines SLn and data lines DLm may be formed on the substrate. The first thin film transistors TR 1 , the second thin film transistors TR 2 , and the third thin film transistors TR 3 may be connected to the scan lines SLn and the data lines DLm. The first thin film transistors TR 1 , the second thin film transistors TR 2 , and the third thin film transistors TR 3 may be disposed in a lattice form. The first organic light emitting elements 10 , the second organic light emitting elements 20 , and the third organic light emitting elements 30 may also be disposed in a lattice form.

The first organic light emitting elements 10 may be disposed in the first regions S 310 . Second organic light emitting elements 20 , second thin film transistors TR 2 connected to the second organic light emitting elements 20 to drive the second organic light emitting elements 20 , and first thin film transistors TR 1 connected to the first organic light emitting elements 10 to drive first organic light emitting elements 10 may be disposed in the second region S 320 . Third thin film transistors TR 3 connected to the second organic light emitting elements 30 and the third organic light emitting elements 30 to drive the third organic light emitting elements 30 , and the first thin film transistors TR 1 connected to the first organic light emitting elements 10 to drive the first organic light emitting elements 10 , may be disposed in the third region S 330 .

The first organic light emitting elements 10 may be formed in the first regions S 310 , and the first thin film transistors TR 1 may not be formed in the first regions S 310 Thus the first regions S 310 may be formed to not be overlapped with the first thin film transistors TR 1 . The first organic light emitting elements 10 may be electrically connected to the first thin film transistors TR 1 disposed in the second regions S 320 or the third regions S 330 .

According to this exemplary embodiment, the third regions S 330 may be formed between the first regions S 310 . Accordingly, an interval between the first organic light emitting element 10 and the first thin film transistor TR 1 may decrease. In addition, the first thin film transistor TR 1 may not be formed in the first region S 310 , thereby improving flexibility of the organic light emitting display. Further, even if third region S 330 is disposed in a bendable region, the first region S 310 with excellent flexibility may be bent to a relatively greater extent, and the third region S 330 may be bent to a relatively lesser extent. Accordingly, deterioration of the thin film transistor disposed in the third region S 330 may be minimized.

By way of summation and review, among the flat panel displays, a flexible display device may be flexible or foldable when desired by a user or in a manufacturing process. However, when a flexible display device is bent or folded, a bent or folded portion of the flexible display device may be deformed or damaged. Accordingly, the quality of the flexible display device may deteriorate. When the flexible display device is frequently bent or folded, durability and convenience of the flexible display device may deteriorate.

Embodiments advance the art by providing a flexible display device that may improve durability and convenience thereof even when subjected to repeated bending. In the flexible display device, thin film transistors may be prevented from deteriorating due to bending.

Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope thereof as set forth in the following claims.