Stretchable display panel and stretchable display device including the same

A stretchable display device having a pliant substrate and a plurality of rigid substrates positioned on the first substrate spaced a first selected distance apart from each other. The pliant substrate having a having a first modulus of elasticity and the second substrates having a second modulus of elasticity that is greater than first modulus of elasticity. There is a semiconductor circuit have a semiconductor transistor and positioned on each of the rigid substrates. At least some of the rigid substrates also include an organic light emitting diode formed thereon. The pliant substrate is configured to stretch, moving the rigid substrates a second distance apart from each other that is greater than the first selected distance. Electrically conductive lines extend between respective ones of the second substrates, each of the electrically conductive lines being configured to stretch to maintain the rigid substrates electrically connected to each other when spaced the first distance apart from each other and also when they are spaced the second, greater distance from each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Korean Patent Application No. KR 10-2018-0171997 filed on Dec. 28, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to a display device and, more particularly, to a stretchable display device having a display panel therein that can stretch.

Description of the Related Art

An Organic Light Emitting Display (OLED) that generates light by itself, a Liquid Crystal Display (LCD) that uses separate light sources, and other types of displays are used as the display devices used in a computer monitor, a TV, and a mobile phone.

Display devices are being used in more various fields including not only a computer monitor, a TV, personal mobile devices, and also in display devices having a large display area with reduced volume and weight.

Recently, a stretchable display device manufactured to be able to stretch/contract in a specific direction and change into various shapes by forming a display unit on a flexible substrate that is a plastic material has been spotlighted as a next generation display device.

BRIEF SUMMARY

Accordingly, the present disclosure is directed to a display panel and a stretchable display device that overcomes and compensates for one or more problems due to limitations and disadvantages of the related art.

One of the objects of the present disclosure is to provide a stretchable display device that can stretch. Another object is to provide a high quality image from the display device while it is being stretched and also after is has been stretched and returned to its former shape.

Another object of the present disclosure is to provide a stretchable display device in which a plurality of rigid substrates are disposed on a base substrate made of a pliable material and light emitting elements are formed on some of the rigid substrates, thereby being able to form the light emitting elements without damaging the circuits and light elements on the substrates while providing a display that is stretchable. In some embodiments, various drive and control circuits that are constructed on rigid substrates are also placed on the same pliable base substrate with the light emitting elements, providing a display panel in which the entire panel is stretchable that includes the light emitting elements, drive elements, control circuits are all other circuits that make up the display.

Another object of the present disclosure is to provide a stretchable display device that can sense the degree of stretch of the display panel. One way to sense the degree of stretch makes use of flexible connecting lines electrically connecting a plurality of rigid substrates. Another way disposes stretch sensing lines that can sense the degree of stretch of the display panel.

Another object of the present disclosure is to provide a stretchable display device that can reduce the deterioration of image quality of the stretchable display device. One of the ways to maintain the image quality at a high level is to sense the degree of stretch of a display panel and then generate compensation data in accordance with the degree of stretch sensed that is applied to the data to each pixel.

The present disclosure describes a display device that may be easily bent, flexed or stretched without damaging driving elements and light emitting elements disposed in a stretchable display device by disposing a plurality of rigid substrates on a base substrate composed of a stretchable, pliant or flexible material. The driving and control circuits as well as the light emitting elements are disposed on respective, individual rigid substrates.

The present disclosure may sense the degree of stretch of a substrate using a connecting line by configuring at least one or more connecting lines of a plurality of connecting lines electrically connecting a plurality of rigid substrates spaced apart from each other on a base substrate made of a stretchable material to include two sensing lines.

The present disclosure may use a panel area by configuring at least one or more connecting lines of a plurality of connecting lines as a stretch sensing line and by configuring one of the sensing lines to be the same line that transmits a data signal, gate signal, OLED characteristic correction signal, or other control signal to each subpixel and to sense the degree of stretch of a panel.

The present disclosure may sense the degree of stretch of a display panel by additionally disposing a stretch sensing line that may sense the degree of stretch of the display panel over the display panel that is a different line than a connecting line transmitting a data or gate signal to respective ones of the plurality of pixels.

The present disclosure enables a display panel to stretch and also reduce deterioration of image quality caused by the stretch. One of the ways it does this is to create compensation data by comparing a sensed value of the degree of stretch and a reference value, and then apply compensation data to each respective pixel. In one embodiment, the stretch at each local pixel is sensed and compensation provided that is different on a pixel by pixel basis. In other embodiments, the degree of stretch of a group of pixels is sensed and compensation provide for a group of pixels. In some embodiments, the stretch of the drive and control circuits can be sensed and compensation provided based on the degree of stretch such circuits experience.

According to one embodiment a stretchable display device is provided having a first pliant substrate having a first modulus of elasticity. There are a plurality of second substrates positioned on the first substrate and spaced apart from each other, each of the second substrates being rigid and having a second modulus of elasticity that is greater than first modulus of elasticity. At least one semiconductor transistor is positioned on each of the second substrates of the plurality. There are electrically conductive lines extending between respective ones of the second substrates, each of the electrically conductive lines configured to be stretched while remaining electrically conductive.

In one embodiment, each of the second substrates has a light emitting element positioned thereon. The electrically conductive lines extending between respective ones of the second substrates is a data line that provides a data signal to the light emitting element on the second substrate. The second modulus of elasticity is more than one thousand times greater than the first modulus of elasticity.

The electrically conductive lines have a flexible, twisty, wavy shape in one embodiment. The electrically conductive lines have a stretchable diamond shape in another embodiment.

In one embodiment there is a stretch sensor positioned between the second substrates. The stretch sensor includes a first capacitor whose value remains constant while the stretch sensor is being stretched and a second capacitor whose value varies in relationship to an amount of the stretch while the stretch sensor is being stretched. The stretch sensor is positioned within one of the electrically conductive lines that extends between respective ones of the second substrates. At least one of the electrically conductive lines extending between respective ones of the second substrates is a gate line for the transistor on the second substrate.

In accordance with another embodiment there is a method of using the stretchable display by stretching the first substrate having a first modulus of elasticity a first distance. There are a plurality of second, rigid substrates positioned on the first substrate a first distance away from each other. Each of the second substrates has a second modulus of elasticity that is greater that the first modulus of elasticity. Each of the second substrates of the plurality has at least one semiconductor transistor thereon. During a stretching step, the the respective second substrate move a second distant from each other that is greater than the first distance during the stretching. The electrical connection between the second substrates is maintained by a stretchable conductive line between the plurality of second substrates prior to and after the stretching. In one embodiment, the amount of stretch of the first substrate is measured during the stretching. A stretch compensation signal is generated based on the measured amount of stretch during the stretching. A light emission data signal is transmitted to the organic light emitting diodes during the stretching. The light emission data signal that is transmitted to the organic light emitting diode is modified during the stretching step based on the generated compensation signal. A gate drive signal is transmitted to the at least one transistor on the rigid substrate during the stretching. After a period of time, the stretching terminates the first substrate returns to the unstretched shape after the stretching.

According to one embodiment, there is a method of making a stretchable display panel that includes providing a first pliant substrate having a first modulus of elasticity. A plurality of second, rigid substrates, are formed having respective semiconductor transistor circuits on each of the second, rigid substrates. The second substrates have a second modulus of elasticity that is greater than the modulus of elasticity of the first pliant substrate. The plurality of second, rigid substrates on the first substrate are spaced a selected distance apart from each other. Electrically conductive lines are formed connecting the plurality of second, rigid substrates to each other with respective electrically conductive lines. Each of the electrically conductive lines are pliant and has third modulus of elasticity that is less than the second modulus of elasticity.

An organic light emitting diode is disposed on at least some of the respective ones of the plurality of second, rigid substrates. A stretch sensor is formed in at least one of the plurality of electrically conductive lines connecting the respective ones of the plurality of second, rigid substrates to each other.

DETAILED DESCRIPTION

A size and a thickness of each component illustrated in the drawing are illustrated for convenience of description and ease of understanding, and the present disclosure is not limited to the size and the thickness of the component illustrated.

Hereinafter, a stretchable display device according to exemplary embodiments of the present disclosure will be described in detail with reference to accompanying drawings.

A stretchable display device may be referred to as a display device that may display images even if it is bent, flexed or stretched. A stretchable display device may have high flexibility, as compared with common display devices. Accordingly, the shape of the stretchable display device may be freely changed in accordance with operation by the user such as bending or stretching the stretchable display device. For example, when a user holds and pulls an end of a stretchable display device, the stretchable display device may be stretched by the force of the user. Alternatively, when a user puts a stretchable display device on an uneven wall, the stretchable display device may be disposed to be bent in the surface shape of the wall. Further, when the force applied by a user is removed, a stretchable display device may return into the initial shape.

FIG. 1is an exploded perspective view of a stretchable display device according to an embodiment of the present disclosure. Referring toFIG. 1, a stretchable display device1000according to an embodiment of the present disclosure includes a display panel100, a flexible connecting film200, and a printed circuit board300.

The display panel100can stretch and contract in any one direction of a first direction X and a second direction Y or can 2-dimensionally stretch and contract in the first direction X and the second direction Y. Here, the first direction X and the second direction Y define the plane of the stretchable display device1000and the second direction Y may be a direction different from the first direction X. For example, the second direction Y may be a direction substantially perpendicular to the first direction X.

The display panel100includes a lower substrate110disposed at a lower portion and an upper substrate120disposed on the lower substrate110. Though not shown inFIG. 1, the display panel100may further include a polarizing layer that may be disposed on the upper substrate120or under the lower substrate110. Further, the lower substrate110and the upper substrate120of the display panel100, may be bonded by an adhesive layer.

The lower substrate110is a substrate for supporting and protecting various components of the stretchable display device1000. The lower substrate110may include a first substrate111of the lower substrate110made of a pliable material and being able to stretch and contract and a plurality of second substrates112disposed on the first substrate111of the lower substrate110and made of a rigid material more than the first substrate111. Here, the first substrate111may be referred to as a base substrate or a flexible substrate and the plurality of second substrates112may be referred to as rigid substrates.

The first substrate111may be made of an insulating material that may bend or stretch. For example, the first substrate111may be made of silicon rubber such as polydimethylsiloxane (PDMS) or an elastomer such as polyurethane (PU), so it may have flexibility. The material of the first substrate111, however, is not limited thereto. The first substrate111, which is a flexible substrate, may reversibly expand and contract. Further, an elastic modulus may be several to hundreds of GPa for the Young's Modulus and a tensile fracture rate may be 100% or more. In some embodiments the Young's Modulus or the first substrate is less than 100 GPa, while it is in the range of 100 to 1000 GPa in other embodiments. In some embodiments, it might be in the range of greater than 1000 and less than 10,000 GPa. The thickness of the first substrate111may be 10 μm to 1 mm, but is not limited thereto.

The plurality of second substrates112spaced and disposed by a predetermined distance from each other are disposed on the first substrate111. The plurality of second substrates112are substrates that are rigid more than the first substrate111made of a pliable material, but also may be flexible substrates with less elasticity. The plurality of second substrates112, for example, may be made of polyimide (PI), polyacrylate, polyacetate, and the like.

The modulus of elasticity of the plurality of second substrates112may be higher than that of the first substrate111. The modulus is an elastic modulus showing the ratio of deformation of a substrate to stress applied to the substrate, and when the modulus of elasticity is relatively high, the material is rigid and it resistance to flexing may be relatively high. Accordingly, the plurality of second substrates112may be rigid substrates that are more rigid than the first substrate111. The modulus of elasticity measured as the Young's Modulus of the plurality of second substrates112may be a thousand times or more higher than that of the first substrate111, but is not limited thereto. For example, the second substrates may be comprised of silicon, sapphire, glass or other rigid material and have a Young's Modulus in the range of 100,000 to 1,000,000 GPa. In other instances, the Young's Modulus of the second substrate will be in the range of 10,000,000 to 100,000,000 GPa. In other embodiments it will be in the range of 100,000,000 to 500,000,000 GPa or higher.

A light emitting element and various driving elements for driving the light emitting element, for example, a switching thin film transistor, a driving thin film transistor, a capacitor, etc. are disposed on each of the plurality of second substrates112. Here, the light emitting element may be any one of an organic light emitting element and a micro LED.

In general, a stretchable display device has an easily bending or stretching characteristic, so there have been attempts in the past to use substrates that have a flexible property due to a small modulus. However, when a pliable material such as polydimethylsiloxane (PDMS) having a small modulus is used as the material of a lower substrate on which light emitting elements are disposed, a material having a small modulus is can become weak due to heat, so, due to this characteristic, there is a problem that the substrate is damaged by high temperature, for example, temperature over 100° C. that is generated in the process of forming transistors and the light emitting elements.

Accordingly, light emitting elements should be formed on a substrate made of a material that can withstand high temperature, so damage to the substrate can be avoided in the process of manufacturing light emitting elements. Accordingly, there have been attempts to manufacture a substrate using materials that can withstand high temperature, which is generated in the manufacturing process, such as polyimide (PI). However, materials that can withstand high temperature do not have flexible properties due to large moduli, so substrates are not easily bent or stretched when stretchable display devices are stretched. In addition, various types of light emitting elements, transistors and driving circuits are often constructed on semiconductor substrates which are frequently made of silicon that is rigid. If the individual components of the transistor, such as the gate, gate dielectric, source, drain and other electrodes flex, this will drastically change the operating characteristics of the transistor and, if flexed too much, will destroy the transistor. It is preferred that some circuit elements of the display device not bend or flex.

Therefore, the plurality of second substrates112that are rigid substrates are disposed in the areas where transistors or light emitting elements are disposed in the stretchable display device1000according to an embodiment of the present disclosure, so damage to the stretchable display device1000due to high temperature in the process of manufacturing the transistors or light emitting elements may be minimized.

Referring toFIG. 1, the plurality of second substrates112each may be electrically connected by connecting lines180. The connecting lines180may be electrically connected by connecting pads disposed on each of the plurality of second substrates112. Here, the pads disposed on each of the plurality of second substrates112may be, for example, gate pads, data pads, and power pads. Since the connecting lines180are disposed on the first substrate111, they may have a twister or wavy shape to permit them to stretch without breaking. Although the connecting lines180are shown as having a twisty, wavy shape in an embodiment of the present disclosure, they are not limited thereto. The connecting lines180may have a straight shape, a chevron shape, or a simple way shape depending on the material of the connecting lines180. For example, the lines180may have a diamond shape that will reduce damage to the connecting lines180due to stretching.

In common display devices, various lines such as a plurality of gate lines and a plurality of data lines are extended and disposed between a plurality of subpixels, and a plurality of subpixels are connected to one signal line. Accordingly, in common display devices, various lines such a gate line, a data line, a high-potential power line, and a reference voltage line extend from a side to the other side of the display devices on a substrate without disconnection.

By contrast, in the stretchable display device1000according to an embodiment of the present disclosure, various lines such as gate lines, data lines, high-potential power lines, and low-potential power lines, which are made of a metal material, are disposed on the plurality of second substrates112. That is, in the stretchable display device1000according to an embodiment of the present disclosure, various lines made of a metal material may be disposed on the plurality of second substrates112and may not be formed to be in contact with the first substrate111. Accordingly, various lines disposed in the stretchable display device1000may be patterned to correspond to the plurality of second substrates112and discontinuously disposed.

In the stretchable display device1000according to an embodiment of the present disclosure, the pads on two adjacent second substrates112may be connected by the connecting lines180to connect the discontinuous lines. That is, the connecting lines180electrically connect the pads on two adjacent second substrates112. Accordingly, the stretchable display device1000according to an embodiment of the present disclosure includes a plurality of connecting lines180electrically connecting various lines such as gate lines, data lines, high-potential power lines, and reference voltage lines between the plurality of second substrates112.

The connecting lines180electrically connect the plurality of second substrates112. That is, the connecting lines180are disposed in spacing areas of the plurality of second substrates112. The connecting lines180may be disposed between the pads disposed on the plurality of second substrates112and may electrically connect each pad. For example, though not shown, a gate line made of a metal material may be disposed on the plurality of second substrates112disposed adjacent to each other in the first direction X and gate pads may be disposed at both ends of the gate line. The plurality of gate pads on the plurality of second substrates112disposed adjacent to each other in the first direction X each may be connected to each other by a connecting line180functioning as a gate line. Accordingly, the gate lines disposed on the plurality of second substrates112and the connecting line180disposed on the first substrate111may function as one gate line. Further, all various lines that may be included in the stretchable display device1000, such as the data lines, high-potential power lines, and low-potential power lines, also each may function as one line by a connecting line180, as described above.

Referring toFIG. 1, the connecting lines180may include first connecting lines181and second connecting lines182. The connecting lines180are pliant and have modulus of elasticity that is substantially less than the modulus of elasticity of the second substrates112. In one embodiment, it is greater than the modulus of elasticity of the first substrate111. It might be, in some examples, the modulus of elasticity of the connecting lines180might be 5 to 10 times greater than that of the first substrate111, while in other embodiments, it might be 10 to 100 times greater.

The first connecting lines181refer to those lines disposed in the first direction X on the lower substrate110. The first connecting lines181may connect pads on two substrates112disposed in parallel of the pads on the plurality of second substrates112disposed adjacent to each other in the first direction X to each other.

The first connecting lines181may include a gate connecting line transmitting a gate signal, a high-potential connecting line transmitting high-potential power, and a low-potential connecting line transmitting low-potential power. In addition, the first connecting lines181may further include a stretch sensing line configured to sense the degree of stretch of the lower substrate110. The first connecting lines181, particularly, the stretch sensing line will be described in more detail with reference toFIGS. 6 and 7in association with a stretch sensing function that senses the degree of stretch of the lower substrate110. Meanwhile, although the first connecting lines181are described as being composed of a gate connecting line, a high-potential connecting line, and a low-potential connecting line in this embodiment, they are not limited thereto.

The second connecting lines182refer to those lines disposed in the second direction Y on the lower substrate110. The second connecting line182may connect pads on two substrates112disposed in parallel of the pads on the plurality of second substrates112disposed adjacent to each other in the second direction Y to each other.

The second connecting lines182may be data connecting lines transmitting a data signal to each subpixel. In some embodiments, at least one data connecting line of the data connecting lines that transmit a data signal to each subpixel, that is, the second connecting lines182may be configured to be able to sense the degree of stretch of the lower substrate110and transmit a data signal. Meanwhile, although the second connecting lines182are described as data connecting lines in an embodiment of the present disclosure, they are not limited thereto. The second connecting lines182will be described next in more detail with reference toFIGS. 2 to 5.

Meanwhile, as another embodiment, though not shown inFIG. 1, the second connecting lines182may further include a stretch sensing line configured to sense the degree of stretch of the lower substrate110. In this case, the second connecting lines182may have only a function of sensing the degree of stretch of the lower substrate110without a function of transmitting a data signal. The second connecting lines182, particularly, the stretch sensing line will be described in more detail with reference toFIGS. 8 and 9in association with a stretch sensing function that senses the degree of stretch of the lower substrate110.

Referring toFIG. 1, the connecting lines180electrically connect the pads disposed on adjacent second substrates112of the plurality of second substrates112and extend in a curved shape between the pads. That is, the first connecting lines181and the second connecting lines182each may extend in a wavy shape. For example, as shown inFIG. 1, the first connecting lines181and the second connecting lines182may have a sine waveform. However, the shapes of the first connecting lines181and the second connecting lines182are not limited thereto. For example, the first connecting lines181and the second connecting lines182may have various shapes, for example, they may extend in a zigzag shape or a plurality of diamond-shaped connecting lines extend with the apexes connected.

The first connecting lines181and the second connecting lines182, for example, may be made of a metal material such as copper (Cu), silver (Ag), gold (Au). Accordingly, since the connecting lines180have a curved shape, even though the connecting lines180are made of a metal material, the stretchable display device1000of the present disclosure may minimize damage to the connecting lines180when the display panel100is stretched.

The lower substrate110may include a plurality of pixel areas PA defining unit cells, an active area AA including the plurality of pixel areas PA, and a non-active area NA surrounding the active area AA.

The plurality of pixel areas PA each may be an area defining a unit cell of the stretchable display device1000. Each pixel area PA may be defined in an area where one second substrate112is disposed on the first substrate111. That is, the pixel area PA may be defined as an area including one second substrate112and the first substrate111surrounding the second substrate112. Alternatively, the pixel area PA may be defined as an area defined by a middle line in the first direction X and a middle line in the second direction Y in the spacing area between adjacent second substrates112in accordance with the shape of the second substrates112. A light emitting element and various driving elements for driving the light emitting element, for example, a switching thin film transistor, a driving thin film transistor, a capacitor, etc. are disposed on the second substrates112in the pixel area PA.

The active area AA is an area where images are displayed in the stretchable display device1000. The active area AA includes the plurality of pixel areas PA and the spaces between the pixels. That is, the plurality of pixel areas PA may be disposed in a checkerboard shape in the active area AA. The plurality of second substrates112are disposed in the active area AA on the first substrate111and are spaced apart from each other with gaps of a first selected distance between them.

The non-active area NA is an area adjacent to the active area AA. There are no light emitting elements in the NA. The non-active area NA may be disposed to surround the active area AA, adjacent to the active area AA. The non-active area NA is an area where an image is not displayed, and lines and circuits may be disposed in the non-active area NA. For example, a driving circuit such as a gate driving unit and a data driving unit, and a plurality of signal pads and power pads may be disposed in the non-active area AA. The driving circuit and each of the pads may be connected to each of the plurality of pixels disposed in the active area AA. The plurality of second substrates112made a material that is more rigid than the first substrate111may be spaced and disposed with predetermined gaps in the non-active area NA, equally to the active area AA, on the first substrate111made of a bendable or stretchable material.

When the first substrate111is stretched, the second substrates move a second distance apart from each other that is greater than the first selected distance. The connecting lines180provide electrical connection between the second substrates when they are the first distance apart from each other. When the first substrate111is stretched and the second substrates move a greater distance apart from each other, the connecting lines also stretch maintaining the electrical connections between the respective second substrates112to each other.

Although the plurality of second substrates112is described as being spaced apart from each other and disposed in the non-active area NA, equally to the active area AA, and being on the first substrate111with reference toFIG. 1in one embodiment, the present disclosure is not limited thereto. The NA might have one or two larger substrates that are positioned directly adjacent to each other and the display be designed in such a way that the NA is not flexible to stretchable. Substrates made of the same material as the second substrates may be disposed in the non-active area NA throughout the entire surface of the first substrate111. As described above, the reason of disposing the plurality of second substrates112or disposing substrates made of the same material as the second substrates on the first substrate111is for reducing damage to the driving unit or the pads disposed in the non-active area NA. Accordingly, in the structure in which the plurality of second substrates112are spaced and disposed in the non-active area NA, driving elements that may drive a plurality of subpixels, for example, transistors or IC chips constituting a gate driving unit or a data driving unit may be disposed on each of the plurality of second substrates112. The connecting lines180in the active area AA may electrically connect the second substrates112in the non-active area NA and the second substrates112in the active area AA to each other by extending.

The flexible connecting film200, which is films disposed with various components on a base film210made of a flexible material, is a component for supplying signals to the plurality of pixels disposed in the active area A/A of the lower substrate110. The flexible connecting film200is disposed between the display panel100and the printed circuit board300and transmits signals input from the printed circuit board300to the pixels disposed in the active area AA of the lower substrate110. That is, the flexible connecting film200may be disposed between the lower substrate110of the display panel100and the printed circuit board300and may electrically connect the lower substrate110and the printed circuit board300.

The flexible connecting film200may be bonded by a plurality of bonding pads disposed in the non-active area NA. As shown inFIG. 1, a plurality of flexible connecting films200may be disposed in the non-active area NA. At least one of the plurality of flexible connecting films200may perform a function that supplies a power voltage, a data voltage, etc. to each of the plurality of pixels disposed in the active area AA through the bonding pads. Further, at least another one of the plurality of flexible connecting films200may also perform a function that calculates the degree of stretch by receiving a stretch sensing signal from connecting lines180, which perform a function that senses the degree of stretch, of the plurality of connecting lines180disposed on the display panel100through the bonding pads.

The flexible connecting films200include a base film210and a driving IC220and various other components may be disposed on the flexible connecting films200.

The base film210is a layer supporting the driving IC220. The base film210may be made of an insulating material, and more detail, the base film210may be made of an insulating material having flexibility such as polyimide (PI).

The driving IC220is a component that is disposed on the base film210and processes data for displaying images and driving signals for processing the data. Further, the driving ICs220connected to the stretch sensing lines may sense the degree of stretch of the lower substrate110and transmit a sensed stretch value to the controller, for example, a timing controller disposed on the printed circuit board300through the stretch sensing lines. Although the driving ICs220are shown as being mounted in a COF type inFIG. 1, the driving ICs220are not limited thereto and may be mounted in the type of Chip On Glass (COG) or Tape Carrier Package (TCP).

Controllers such as an IC chip and a circuit, for example, a timing controller may be mounted on the printed circuit board300. In one embodiment, the printed circuit board300is rigid and does not stretch. Further, a memory, a processor, etc. also may be mounted on the printed circuit board300. The printed circuit board300transmits signals for driving pixels from the controllers to the pixels. The printed circuit board300may create compensation data by comparing the stretch sensing value transmitted from the driving ICs220connected to the stretch sensing lines with a predetermined reference value.

The printed circuit board300may be electrically connected to each of the plurality of pixels disposed in the active area AA of the display panel100by being connected to the flexible connecting films200.

The upper substrate120is a substrate overlapped with the lower substrate110to protect various components of the stretchable display device1000. The upper substrate120, which is a flexible substrate, may be made of a bendable, pliant or stretchable insulating material. For example, the upper substrate120may be made of a bendable, pliant or stretchable material and may be made of the same material as the first substrate111of the lower substrate110, but is not limited thereto.

Though not shown inFIG. 1, the stretchable display device1000according to an embodiment of the present disclosure may further include a polarizing layer. The polarizing layer, which is a configuration suppressing external light reflection by the stretchable display device1000, may be disposed on the upper substrate120while overlapping the upper substrate120. However, the polarizing layer is not limited thereto and, may be disposed under the upper substrate120, may be disposed under the lower substrate110, or may be omitted, depending on the configuration of the stretchable display device1000.

FIGS. 2 to 5are referred to hereafter to describe in more detail the stretchable display device1000according to an embodiment of the present disclosure.

FIG. 2is an enlarged plan view enlarging one pixel area disposed in a stretchable display device according to an embodiment of the present disclosure.FIG. 3is a schematic cross-sectional view of one subpixel of a stretchable display device according to an embodiment of the present disclosure.FIG. 4is a schematic cross-sectional view of one subpixel of a stretchable display device according to another embodiment of the present disclosure.FIG. 5is a schematic cross-sectional view taken along line V-V ofFIG. 2.

First, referring toFIG. 2, a first substrate111made of a pliable material and a second substrate112made of a material that is more rigid than the first substrate111and disposed on the first substrate111are disposed in a pixel area PA of the stretchable display device1000according to an embodiment of the present disclosure.

A pixel PX including a light emitting element is disposed on the second substrate112in the pixel area PA and a plurality of connecting lines180connecting pixels PX disposed in a plurality of second substrates112to each other is disposed on the first substrate111.

The pixels PX emit light having a specific wavelength band. For example, the pixels PX include sub-pixels SPX respectively emitting red, green, and blue light. Although three subpixels SPX emitting red, green, and blue light are described in an embodiment of the present disclosure, the present disclosure is not limited thereto. For example, the pixels PX may further include a subpixel emitting white light other than the subpixels SPX emitting red, green, and blue light. When a subpixel emitting white light is included, the stretchable display device1000according to an embodiment of the present disclosure may further include a color filter. The subpixels SPX each may include a thin film transistor and a light emitting element. The light emitting element may be any one of an organic light emitting element and a micro LED.

Referring toFIG. 3to describe the structure of the subpixels SPX in more detail, a second substrate112on which a thin film transistor150and a light emitting element160are disposed is disposed in a predetermined area of the first substrate111of the lower substrate110. As described above, the area where the second substrate112on which the thin film transistor150and the light emitting element160are disposed is disposed may be referred to as a rigid area RA and the areas where a first connecting line181and a second connecting line182are disposed may be referred to as pliable areas SA.

Referring toFIG. 3, a buffer layer113is disposed on the second substrate112of the rigid area RA. The buffer layer113may be made of an insulating material, and for example, may be made as a single inorganic layer or a multi-inorganic layer made of a silicon nitride (SiNx), a silicon oxide (SiOx), or silicon oxynitride (SiON).

The buffer layer113is disposed in an area overlapped with the second substrate112of the rigid area RA to protect various components of the stretchable display device1000against permeation of water, oxygen, etc. from the outside. This is because the buffer layer113may be made of an inorganic material, so they may be easily damaged, such as cracking, when the stretchable display device1000is stretched. Accordingly, the buffer layer113may be formed over the second substrate112of the rigid area RA by patterning similar to the shape of the second substrate112of the rigid area RA without being formed to the pliable areas SA that are the spacing area between a plurality of second substrates112. Therefore, since the buffer layer113is formed in the area overlapped with the second substrate112of the rigid area RA, it is possible to suppress damage to the buffer layer113even though the stretchable display device1000according to an embodiment of the present disclosure is deformed, such as, bending or stretching. However, the buffer layer113may be omitted, depending on the structure or characteristics of the stretchable display device1000.

Referring toFIG. 3, a transistor150including a gate electrode151, an active layer152, a source electrode153, and a drain electrode154is formed on the buffer layer113. For example, as for the process of forming the transistor150, the active layer152is formed on the buffer layer113, and a gate insulating layer114for insulating the active layer152and the gate electrode152from each other is formed on the active layer152. An inter-layer insulating layer115is formed to insulate the gate electrode151, the source electrode153, and the drain electrode154from each other, and the source electrode153and the drain electrode154that are in contact with the active layer152are formed on the inter-layer insulating layer115.

The gate insulating layer114and the inter-layer insulating layer115may be formed in the area overlapped with the second substrate112in the rigid region RA by patterning. The gate insulating layer114and the inter-layer insulating layer115may also be made of an inorganic material, equally to the buffer layer113, so they may be easily damaged such as cracking when the stretchable display device1000is stretched. Accordingly, the gate insulating layer114and the inter-layer insulating layer115may be formed over the second substrate112of the rigid area RA by patterning similarly to the shape of the second substrate112of the rigid area RA without being formed in the areas between the second substrates112on which the thin film transistors150are disposed, that is, the pliable areas SA.

Only a driving thin film transistor of various thin film transistors that may be included in the stretchable display device1000is shown inFIG. 3for the convenience of description, but a switching thin film transistor, a capacitor, etc. may be included in the display device. Further, although the thin film transistor150is described as having a coplanar structure in the present disclosure, it is not limited thereto various transistors, for example, having a staggered structure may be used.

Referring toFIG. 3, a gate pad141is disposed on the gate insulating layer114. The gate pad141is a pad for transmitting a gate signal to a plurality of subpixels SPX. The gate pad141may be made of the same material as the gate electrode151, but is not limited thereto.

Referring toFIG. 3, a planarization layer116is formed on the thin film transistor150and the inter-layer insulating layer115. The planarization layer116planarizes the top of the thin film transistor150. The planarization layer116may be composed of a single layer or a plurality of layers and may be made of an organic material. For example, the planarization layer116may be made of an acrylic-based organic material, but is not limited thereto. The planarization layer116may have a contact hole for electrically connecting the thin film transistor150and a first electrode161of the organic light emitting element160, a contact hole for electrically connecting a data pad143and the source electrode153, and a contact hole for electrically connecting a connecting pad142and a gate pad141.

In some embodiments, a passivation layer may be formed between the thin film transistor150and the planarization layer116. That is, a passivation layer covering the thin film transistor150may be formed to protect the thin film transistor150from permeation of water, oxygen, etc. The passivation layer may be made of an inorganic material and may be composed of a single layer or a multi-layer, but is not limited thereto.

Referring toFIG. 3, the data pad143, the connecting pad142, and the organic light emitting element160are disposed on the planarization layer116.

The data pad143may transmit a data signal from a second connecting line182, which functions as a data line, to a plurality of subpixels SPX. The data pad143is connected to the source electrode153of the thin film transistor150through a contact hole formed at the planarization layer116. The data pad143may be made of the same material as the first electrode161of the organic light emitting element160, but is not limited thereto. The data pad143may be made of the same material as the source electrode153and the drain electrode154of the thin film transistor150, not on the planarization layer116, but on the inter-layer insulating layer115.

The connecting pad142and the gate pad141may transmit a gate signal from a first connecting line181, which functions as a gate line, to a plurality of subpixels SPX. The connecting pad142is connected to the gate pad141through contact holes formed at the planarization layer116and the inter-layer insulating layer115and transmits a gate signal to the gate pad141. The connecting pad142may be made of the same material as the data pad143, but is not limited thereto.

The organic light emitting element160includes the first electrode161, an organic light emitting layer162, and a second electrode163. In detail, the first electrode161is disposed on the planarization layer116. The first electrode161is an electrode configured to supply holes to the organic light emitting layer162. The first electrode161may be made of a transparent conductive material with a high work function. The transparent conductive material may include an Indium Tin Oxide (ITO), an Indium Zinc Oxide (IZO), and an Indium Tin Zinc Oxide (ITZO). The first electrode161may be made of the same material as the data pad143and the gate pad141disposed on the planarization layer116, but is not limited thereto. When the stretchable display device1000is implemented in a top emission type, the first electrode161may further include a reflective plate. Further, the first electrode161may reflect light emitted from the organic light emitting layer162and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag) which have a lower work function than the second electrode163, or an alloy thereof.

The first electrodes161are spaced and disposed respectively for subpixels SPX and electrically connected to the thin film transistor150though a contact hole of the polarization layer116. For example, although the first electrode161is electrically connected to the drain electrode154of the transistor150inFIG. 3, it may be electrically connected to the source electrode153.

A bank117is formed on the first electrode161, the data pad143, the connecting pad142, and the planarization layer116. The bank117is a component separating adjacent subpixels SPX. The bank117is disposed to cover at least partially both sides of adjacent first electrode161, thereby partially exposing the tops of the first electrode161. The bank117may suppress the problem that an unexpected subpixel SPX emits light or colors are mixed by light emitted in the lateral direction of the first electrode161due to concentration of a current on the edge of the first electrode161. The bank117may be made of acrylic-based resin, benzocyclobutene (BCB)-based resin, or polyimide, but is not limited thereto.

The bank117has a contact hole for connecting the second connecting line182and the data pad143and a contact hole for connecting the first connecting line181functioning as a gate line and the connecting pad142.

The organic light emitting layer162is disposed on the first electrode161. The organic light emitting layer162is configured to emit light. The organic light emitting layer162may include a luminescent material, and the luminescent material may include a phosphorous material of a fluorescent material, but is not limited thereto.

The organic light emitting layer162may be composed of one light emitting layer. Alternatively, the organic light emitting layer162may have a stacked structure in which a plurality of light emitting layers is stacked with a charge generation layer therebetween. The organic light emitting layer162may further include at least one organic layer of a whole transporting layer, an electron transporting layer, a hole blocking layer, an electron blocking layer, a hole injection layer, and an electron injection layer.

Referring toFIG. 3, the second electrode163is disposed on the organic light emitting layer162. The second electrode163supplies electrons to the organic light emitting layer162. The second electrode163may be made of a material having a work function different from the material of the first electrode161. The second electrode163, for example, may be made of Indium Tin Oxide (ITO)-based, Indium Zinc Oxide (IZO)-based, Indium Tin Zinc Oxide (ITZO)-based, Zinc Oxide (ZnO)-based, and Tin Oxide (TO)-based transparent conductive oxides or an Ytterbium (Yb) alloy. Alternatively, the second electrode163may be made of a metal material.

Further, when the stretchable display device1000is implemented in a top emission type, the second electrode163may further include a reflective plate.

Further, the second electrode163may reflect light emitted from the organic light emitting layer162and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag) which have a lower work function than the first electrode161, or an alloy thereof. The second electrode163may be formed by patterning to overlap each of the second substrates112of the rigid areas RA. That is, the second electrode163is formed in the areas overlapped with the second substrates112of the rigid areas RA and may be disposed not to be formed in the pliable areas SA. Since the second electrode163is made of a material, such as a transparent conductive oxide, a transparent metal material, a reflective metal material, and the like, when the second electrode163is formed in the areas between second substrates112on which the organic light emitting elements160are disposed, that is, is formed even in the pliable areas SA, the second electrode163may be damaged when the stretchable display device1000is stretched and contracted. The second electrode163may be formed to respectively correspond to the second substrates112of the rigid areas RA in a plane. The second electrode163may be formed to have an area not overlapped with the areas where the connecting lines180are formed of the areas overlapped with the second substrates112in the rigid areas RA.

Though not shown inFIG. 3, an insulating layer for insulation between two sensing lines constituting the stretch sensing lines disposed by extending from the pliable area SA may be further disposed on the organic light emitting element160.

Referring toFIG. 3, an encapsulation layer108is disposed on the organic light emitting element160. The encapsulation layer108may seal the organic light emitting element160by covering the organic light emitting element160in contact with a portion of the top of the bank117. Accordingly, the encapsulation layer108protects the organic light emitting element160from water, air, or physical shock that may permeate from the outside.

The encapsulation layers108respectively cover the second electrode163patterned to respectively overlap the second substrates112of the rigid areas RA and may be formed on the second substrates112, respectively. That is, the encapsulation layers108are disposed to each cover one second electrode163on one second substrate112and the encapsulation layer108disposed on each of the second substrates112of the rigid areas RA may be spaced apart from each other.

The encapsulation layer108may be formed in the areas overlapped with the second substrates112of the rigid areas RA. As described above, since the encapsulation layers108may be configured to include an inorganic layer, they may be easily damaged, such as cracking, when the stretchable display device1000is stretched. In particular, since the organic light emitting element160is vulnerable to water or oxygen, when the encapsulation layer108is damaged, reliability of the organic light emitting element160may be reduced. Therefore, since the encapsulation layer108is not formed in the pliable areas SA, damage to the encapsulation layer108may be minimized even though the stretchable display device1000according to an embodiment of the present disclosure is deformed, such as, bending or stretching.

However, if necessary, the encapsulation layer108may be formed on the front surface of the lower substrate110including the rigid areas RA and the pliable areas SA.

Compared with common flexible organic light emitting display devices of the related art, the stretchable display device1000according to an embodiment of the present disclosure has a structure in which the plurality of second substrates112that is relatively rigid is spaced apart from each other and disposed on the first substrate111that is relatively pliable. The second electrode163and the encapsulation layers108of the stretchable display device1000are disposed by patterning to correspond to the plurality of second substrates112, respectively. That is, the stretchable display device1000according to an embodiment of the present disclosure may have a structure that enables the stretchable display device1000to be more easily deformed when a user stretches or bends the stretchable display device1000and may have a structure that may minimize damage to the constituting components of the stretchable display device1000when the stretchable display device1000is deformed.

The lower substrate110configured in this way may be bonded to the upper substrate120shown inFIG. 1by an adhesive layer (not shown).

Meanwhile, although an organic light emitting element is exemplified as a light emitting element inFIG. 3, the light emitting elements of the stretchable display device1000may be micro LEDs. The structure of one subpixel when the light emitting elements of the stretchable display device1000according to an embodiment of the present disclosure are micro LEDs is described hereafter.

Referring toFIG. 4, a common line CL is disposed on the gate insulating layer114. The common line CL is a line applying a common voltage to a plurality of subpixels SPX. The common line CL may be made of the same material as the source electrode153and the drain electrode154of the thin film transistor150, but is not limited thereto. For example, the common line CL may also be made of the same material as the gate electrode151of the thin film transistor150.

A reflective layer423is disposed on the inter-layer insulating layer115. The reflective layer423is a layer for discharging light, which is emitted to the first substrate111of light emitting from the micro LED410, to the outside by reflecting the light upward a stretchable display device1000. The reflective layer423may be made of a metal material having high reflectance.

A first adhesive layer417is disposed on the reflective layer423to cover the reflective layer423. The first adhesive layer417, which is a layer for bonding the micro LED410on the reflective layer423, may insulate the reflective layer423made of a metal material and the micro LED410from each other. The first adhesive layer417may be made of a thermosetting material or a photocuring material, but is not limited thereto. Although the first adhesive layer417covers only the reflective layer423inFIG. 4, the disposition position of the first adhesive layer417is not limited thereto.

The micro LED410is disposed on the first adhesive layer417. The micro LED410is disposed while overlapping the reflective layer423. The micro LED410includes an n-type layer411, an active layer412, a p-type layer413, a p-electrode414, and an n-electrode415. The micro LED410is described as a micro LED410of a lateral structure hereafter, but the structure of the micro LED410is not limited thereto. For example, a micro LED of a flip chip structure may be used as the micro LED410.

In detail, the n-type layer411of the micro LED410is disposed while overlapping the reflective layer423on the first adhesive layer417. The n-type layer411may be formed by injecting an n-type impurity into a gallium nitride having excellent crystallinity. The active layer412is disposed on the n-type layer411. The active layer412, which is a light emitting layer that emits light in the micro LED410, may be made of a nitride semiconductor, for example, an indium gallium nitride. The p-type layer413is disposed on the active layer412. The p-type layer413may be formed by injecting a p-type impurity into a gallium nitride. However, the configuration materials of the n-type layer411, the active layer412, and the p-type layer413are not limited thereto.

The p-electrode414is disposed on the p-type layer413of the micro LED410. The n-electrode415is disposed on the n-type layer411of the micro LED410. The n-electrode415is spaced and disposed apart from the p-electrode414. In detail, the micro LED410may be manufactured by sequentially stacking the n-type layer411, the active layer412, and the p-type layer413, etching a predetermined portion of the active layer412and the p-type layer413, and then forming the n-electrode415and the p-electrode414. In some embodiments, the predetermined portion is a space for spacing the n-electrode415and the p-electrode414and the predetermined portion may be etched to expose a portion of the n-type layer411. In other words, the surface of the micro LED410where the n-electrode415and the p-electrode415are disposed is not a planarized surface and may have different levels. Accordingly, the p-electrode414is disposed on the p-type layer413, the n-electrode415is disposed on the n-type layer411, and the p-electrode414and the n-electrode415are spaced and disposed apart from each other at different levels. Therefore, the n-electrode415may be disposed more adjacent to the reflective layer423in comparison to the p-electrode414. The n-electrode415and p-electrode414may be made of a conductive material, for example, a transparent conductive oxide. Alternatively, the n-electrode415and p-electrode414may be made of the same material, but are not limited thereto.

A planarization layer116is disposed on the inter-layer insulating layer114and the first adhesive layer417. The planarization layer116is a layer that planarizes the top of the thin film transistor150. The planarization layer116may be disposed to planarize the top of the planarization layer116in an area excepting the area where the micro LED410is disposed. The planarization layer116may be composed of two or more layers.

A first electrode421and a second electrode422are disposed on the planarization layer116. The first electrode421is an electrode that electrically connects the thin film transistor150and the micro LED410. The first electrode421is connected to the p-electrode414of the micro LED410through a contact hole formed at the planarization layer116. The first electrode421is connected to the drain electrode154of the thin film transistor150through contact holes formed at the planarization layer116and the inter-layer insulating layer115. However, the first electrode421is not limited thereto and may be connected to the source electrode153of the thin film transistor150, depending on the type of the thin film transistor150. The p-electrode414of the micro LED410and the drain electrode154of the thin film transistor150may be electrically connected by the first electrode421.

The second electrode422is an electrode that electrically connects the micro LED410and the common line CL. In detail, the second electrode422is connected to the common line CL through contact holes formed at the planarization layer116and the inter-layer insulating layer115and is connected to the n-electrode415of the micro LED410through a contact hole formed at the planarization layer116. Accordingly, the common line CL and the n-electrode415of the micro LED410are electrically connected.

When the stretchable display device1000is turned on, voltages having different levels may be supplied respectively to the drain electrode154of the thin film transistor150and the common line CL. The voltage that is applied to the drain electrode154of the thin film transistor150may be applied to the first electrode421and a common voltage may be applied to the second electrode422. Voltages having different levels may be applied to the p-electrode414and the n-electrode415through the first electrode421and the second electrode422, so the micro LED410may emit light.

Although the thin film transistor150is described as being electrically connected to the p-electrode414and the common line CL is described as being electrically connected to the n-electrode415inFIG. 4, they are not limited thereto. That is, the thin film transistor150may be electrically connected to the n-electrode415and the common line CL may be electrically connected to the p-electrode414.

A bank117is disposed on the planarization layer116, the first electrode421, the second electrode422, the data pad143, and the connecting pad142. The bank117may be disposed to overlap an end of the reflective layer423and a portion not overlapped with the bank117of the reflective layer423may be defined as a light emitting area. The bank117may be made of an organic insulating material and may be made of the same material as the planarization layer116. The bank117may be configured to include a black material to suppress a color mixing phenomenon due to light emitted from the micro LED410and transmitted to an adjacent subpixel SPX.

As described above, the light emitting elements of the stretchable display device1000according to an embodiment of the present disclosure may be organic light emitting elements, but also may be micro LEDs410. Since the micro LED410is made of not an organic material, but an inorganic material, reliability is excellent, so the lifespan is longer than that of a liquid crystal light emitting element or an organic light emitting element. The micro LED410has a quick turning speed, has small power consumption, has excellent stability because it has strong shock-resistance, and may display high-luminance images because it has excellent emission efficiency. Accordingly, the micro LED410is an element that is suitable to be applied even to very large screens. In particular, since the micro LED410is made of not an organic material, but an inorganic material, an encapsulation layer that is required when an organic light emitting element is used may not be used. Accordingly, the encapsulation layer that may be easily damaged, such as cracking, when the stretchable display device1000is stretched may be omitted. Accordingly, it is possible to omit use of an encapsulation layer that may be damaged when the stretchable display device1000according to another embodiment of the present disclosure is deformed such as bending or stretching, by using the micro LED410as a light emitting element in the stretchable display device1000. Further, since the micro LED410is made of not an organic material, but an inorganic material, the emitting elements of the stretchable display device1000according to another embodiment of the present disclosure may be protected from water or oxygen and their reliability may be excellent.

Meanwhile, referring toFIGS. 3 and 4, the first connecting line181and the second connecting line182each are connected to the gate pad141and the connecting pad142or the data pad143disposed on the second substrate112of the rigid area RA and may be extended and disposed to the pliable areas SA. In some embodiments, a line damage suppression layer112S may be disposed under the first connecting line181and the second connecting line182disposed on the pliable areas SA.

The line damage suppression layer112S may be disposed on the first substrate111in correspondence to the shape of the first connecting line181and the second connecting line182disposed on the pliable areas SA. That is, when the first connecting line181and the second connecting line182have a wavy shape, the line damage suppression layer112S may correspondingly have a wavy shape, and when the first connecting line181and the second connecting line182have a straight shape, the line damage suppression layer112S may correspondingly have a straight shape. For example, the shape of the line damage suppression layer112S formed on the first substrate111may substantially follow the shape of the first connecting line181and the second connecting line182. The line damage suppression layer112S may be made of the same material as the second substrate112disposed in the rigid area RA. The line damage suppression layer112S, for example, may include silicon rubber such as polydimethylsiloxane (PDMS), an elastomer such as polyurethane (PU), styrene butadiene styrene (SBS), etc. Accordingly, by disposing the line damage suppression layer112S under the connecting line180disposed in the pliable areas SA in the stretchable display device1000according to an embodiment of the present disclosure, it is possible to suppress damage to the connecting line180and control overstretching of the lower substrate110when the stretchable display device1000is stretched.

Referring toFIGS. 2 and 3, a plurality of connecting lines180for electrically connecting a second substrate112and another second substrate112disposed adjacent to the second substrate112are disposed on the first substrate111. The plurality of connecting lines180include a plurality of first connecting lines181disposed in the first direction X and a plurality of second connecting lines182disposed in the second direction Y.

The plurality of first connecting lines181each may be electrically connected to a gate line131a, a high-potential power line131b, and a low-potential power line131cdisposed on the second substrate112. The plurality of first connecting lines181may have a curved shape, that is, a wavy shape to correspond to stretching of the lower substrate110. For example, a curved shape means wave shape or a diamond shape. The plurality of first connecting lines181, for example, may be made of a metal material such as copper (Cu), silver (Ag), and gold (Au). Accordingly, even though the first connecting lines181are made of a metal material, the first connecting lines181extend to have a curved shape on the first substrate111, whereby damage to the plurality of first connecting lines181may be minimized even though the stretchable display device1000is stretched.

The plurality of second connecting lines182each may be electrically connected to first to third data lines132a,132b, and132cdisposed on the second substrate112. The plurality of second connecting lines182may have a curved shape, that is, a wavy shape to correspond to stretching of the lower substrate110. The plurality of second connecting lines182, for example, may be made of a metal material such as copper (Cu), silver (Ag), and gold (Au). Accordingly, even though the plurality of second connecting lines182is made of a metal material, the second connecting lines182extend to have a curved shape on the first substrate111, whereby damage to the second connecting lines182may be minimized even though the stretchable display device1000is stretched.

Any one second connecting line182S (hereafter, referred to as a ‘second stretch sensing line’) of the plurality of second connecting lines182may sense the degree of stretch of the lower substrate110while performing a function that transmits a data signal. Accordingly, the second stretch sensing line182S may be electrically connected to first and second data lines132aand132bdisposed on the second substrate112.

The second stretch sensing line182S may include a second stretch sensing Rx line182Sa (which may be referred as an Rx line) and a second stretch sensing Tx line182Sb that may sense the degree of stretch. Accordingly, the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb that are configured to be able to sense the degree of stretch of the lower substrate110are disposed in the second stretch sensing line182S that is any one connecting line of the plurality of connecting lines180in the stretchable display device1000according to an embodiment of the present disclosure. Therefore, it is possible to find out the degree of stretch of the lower substrate110by sensing capacitance C between the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb before stretching and between the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb after stretching and determining a difference of the capacitance C before and after stretching.

Referring toFIG. 2, a gate line131afor transmitting a gate signal to each subpixel SPX, a high-potential power line131bfor transmitting high-potential power to each subpixel SPX, a low-potential power line131cfor transmitting low-potential power to each subpixel SPX, and first to third data lines132a,132b, and132cfor transmitting a data signal to each subpixel SPX are disposed on the second substrate112.

The gate line131a, the high-potential power line131b, and low-potential power line131care disposed in the first direction X on the second substrate112and may be electrically connected to a plurality of first connecting lines181disposed in the first direction X on the first substrate111.

The first to third data lines132a,132b, and132care disposed in the second direction Y on the second substrate112and may be electrically connected to a plurality of second connecting lines182disposed in the second direction Y on the first substrate111. In particular, the first data line132amay be electrically connected to the second stretch sensing Rx line182Sa extending from the second stretch sensing line182S disposed on the first substrate111. The second data line132bmay be electrically connected to the second stretch sensing Tx line182Sb extending from the second stretch sensing line182S disposed on the first substrate111. Accordingly, the second stretch sensing Rx line182Sa may be the first data line132aon the second substrate112and the second stretch sensing Tx line182Sb may be the second data line132bon the second substrate112. In some embodiments, the first data line132ais a line supplying a data signal to any one subpixel SPX and the second data line132bis a line supplying a data signal to another subpixel SPX disposed adjacent to the any one subpixel SPX. That is, the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb constituting the second stretch sensing line182S on the first substrate111may sense the degree of stretch according to stretch of the first substrate111. The second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb constituting the second stretch sensing line182S on the second substrate112may transmit a data signal. Further, the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb constituting the second stretch sensing line182S each function as a data line supplying data to two subpixels, whereby it is possible to increase area utilization by reducing the number of connecting lines disposed on the first substrate111.

Referring toFIG. 5, the second stretch sensing Rx line182Sa of the second stretch sensing line182S disposed on the first substrate111is electrically connected to the first data line132atransmitting a data signal to a corresponding subpixel by the data pad143. Further, the second stretch sensing Tx line182Sb of the second stretch sensing line182S disposed on the first substrate111is electrically connected to the second data line132bof a subpixel adjacent to the subpixel connected to the first data line132a. Accordingly, the second stretch sensing Rx line182Sa of the second stretch sensing line182S may transmit a data signal to any one subpixel and the second stretch sensing Tx line182Sb may transmit a data signal to a subpixel adjacent to the any one subpixel.

As such, when the second stretch sensing line182S plays both roles as a data line and stretch sensing line, the second stretch sensing line182S may be configured to transmit a data signal in a period in which a data signal is applied, and senses the degree of stretch of the first substrate111in a period in which a data signal is not applied.

Such a stretchable display device1000according to an embodiment of the present disclosure is configured such that any one second connecting line182S of the plurality of connecting lines180, particularly, the plurality of second connecting lines182includes the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb. Accordingly, when the first substrate111is stretched, the degree of stretch is sensed using the capacitance between the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb. Further, by connecting each of the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb to each of the first data line132aand the second data line132bdisposed on the second substrate112, it is possible to reduce the area of the second connecting line182S disposed on the first substrate111.

Meanwhile, as described above, the case when at least one connecting line182S of the plurality of connecting lines180may transmit a data signal to a subpixel SPX and sense the degree of stretch of the first substrate111is described as an embodiment. However, the stretchable display device1000according to an embodiment of the present disclosure is not limited thereto and may be configured to be able to transmit a gate signal and play a role that may sense the degree of stretch of the first substrate111. As such, an embodiment about a stretch sensing line that plays roles as a gate line and stretch sensing is described next in more detail with reference toFIGS. 6 and 7.

FIG. 6is an enlarged plan view enlarging one pixel area disposed in a stretchable display device according to another embodiment of the present disclosure.FIG. 7is a schematic cross-sectional view taken along line VII-VII′ ofFIG. 6.

Before looking intoFIGS. 6 and 7, the structure of one subpixel shown inFIGS. 6 and 7, as compared with the subpixel structure shown inFIGS. 2 and 5, is different only in the disposition position of the stretch sensing line and is the same in substantial configuration, so repeated description for the same reference numerals is omitted.

First, referring toFIG. 6, a first stretch sensing line181S of a plurality of connecting lines180disposed on a first substrate111may be disposed to extend in a first direction X. That is, at least any one of a plurality of first connecting lines181extending in the first direction X may be the first stretch sensing line181S.

The first stretch sensing line181S may include a first stretch sensing Rx line181Sa (which may be referred as an Rx line) and a first stretch sensing Tx line181Sb that may sense the degree of stretch.

Referring toFIG. 6, first and second gate lines131aand131bfor transmitting a gate signal to each subpixel SPX, a high-potential power line131cfor transmitting high-potential power to each subpixel SPX, a low-potential power line131dfor transmitting low-potential power to each subpixel SPX, and first to third data lines132a,132b, and132cfor transmitting a data signal to each subpixel SPX are disposed on a second substrate112. Here, the first and second gate lines131aand131bmay be lines respectively transmitting a first scan signal and a second scan signal in accordance with each subpixel.

Referring toFIG. 6, the first stretch sensing line181S disposed on the first substrate111is disposed on the first gate line131a, and any one of a first stretch sensing Rx line181Sa and a first stretch sensing Tx line181Sb constituting the first stretch sensing line181S may be electrically connected to the first gate line131a.

Referring toFIG. 7, the first stretch sensing Rx line181Sa of the first stretch sensing line181S disposed on the first substrate111is electrically connected to the first gate line131atransmitting a first gate signal to each subpixel through a connecting pad142. Accordingly, the first connecting line181S including the first stretch sensing Rx line181Sa may play a role of a gate line transmitting the first gate signal. Further, the first stretch sensing Tx line181Sb of the first stretch sensing line181S disposed on the first substrate111may be disposed on an insulating layer118positioned at a higher level than the first stretch sensing Rx line181Sa. That is, the first stretch sensing Rx line181Sa and the first stretch sensing Tx line181Sb may be disposed at different levels. An insulating layer may be interposed between the first stretch sensing Rx line181Sa and the first stretch sensing Tx line181Sb. In some embodiments, the insulating layer118may be an inorganic layer that is a partial configuration of an encapsulation layer108of a subpixel.

As such, the first stretch sensing line181S including the first stretch sensing Rx line181Sa and the first stretch sensing Tx line181Sb that may sense the degree of stretch by a capacitance difference before and after stretching is disposed in the first direction X that is the same as the direction in which a gate line extends in the stretchable display device according to an embodiment of the present disclosure. Accordingly, it is possible to sense the degree of stretch in the first direction X by comparing the capacitance values between the first stretch sensing Rx line181Sa and the first stretch sensing Tx line181Sb before and after stretching when the first substrate111is stretched in the first direction X.

Meanwhile, the first gate line131aand the first stretch sensing Rx line181Sa of the first stretch sensing line181S are described as being electrically connected inFIG. 7. However, a first stretch sensing line181S may be additionally disposed in the first direction X to perform a stretch sensing function separately from the gate line disposed on a second substrate112.

Further, a stretch sensing line may be separately disposed not only in the first direction X, but also in the second direction Y.

As such, an embodiment when a stretch sensing line that may sense stretch is additionally disposed is described next in detail with reference toFIGS. 8 and 9.

FIG. 8is an enlarged plan view enlarging one pixel area disposed in a stretchable display device according to another embodiment of the present disclosure.FIG. 9is a schematic cross-sectional view taken along line VIII-VIII′ ofFIG. 8.

Before looking intoFIGS. 8 and 9, the structure of one subpixel shown inFIGS. 8 and 9, as compared with the subpixel structure shown inFIGS. 2 and 5, is different only in the disposition position of the stretch sensing line and is the same in substantial configuration, so repeated description for the same reference numerals is omitted.

Referring toFIG. 8, a stretch sensing line182S of a plurality of connecting lines180disposed on a first substrate111may be disposed to extend in a second direction Y. That is, at least any one of a plurality of second connecting lines182extending in the second direction Y may be a second stretch sensing line182S.

The second stretch sensing line182S may include a second stretch sensing Rx line182Sa and a second stretch sensing Tx line182Sb that may sense the degree of stretch.

Referring toFIG. 8, a gate line131afor transmitting a gate signal to each subpixel SPX, a high-potential power line131bfor transmitting high-potential power to each subpixel SPX, a low-potential power line131cfor transmitting low-potential power to each subpixel SPX, and first to third data lines132a,132b, and132cfor transmitting a data signal to each subpixel SPX are disposed on the second substrate112. Here, the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb constituting the second stretch sensing line182S may be disposed on a separate layer regardless of the first to third data lines132a,132b, and132ctransmitting a data signal to each subpixel SPX.

Referring toFIG. 9, the second stretch sensing Rx line182Sa of the second stretch sensing line182S disposed on the first substrate111may be spaced and disposed apart from a second electrode163of an organic light emitting element160. Further, the second stretch sensing Tx line182Sb is disposed on the second stretch sensing Rx line182Sa and an insulating layer118may be disposed between the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb. In some embodiments, the insulating layer118may be an inorganic layer constituting an encapsulation layer (108inFIG. 3). That is, the second stretch sensing line182S extending from the first substrate111to the second substrate112regardless of the first to third data lines132a,132b, and132cis disposed on the second substrate112and may be disposed regardless of lines transmitting a signal even on the second substrate112.

As such, the second stretch sensing line182S including the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb that may sense the degree of stretch by a capacitance difference before and after stretching is disposed to extend the second direction Y that is the same as the direction in which the first to third data lines132a,132b, and132cextend in the stretchable display device according to an embodiment of the present disclosure. Accordingly, it is possible to sense the degree of stretch in the second direction Y by comparing the capacitance values between the second stretch sensing Rx line182Sa and the second stretch sensing Tx line182Sb before and after stretching when the first substrate111is stretched in the second direction Y.

Meanwhile, in an embodiment of the present disclosure, the cases when the first stretch sensing line181S disposed in the first direction X and the second stretch sensing line182S disposed in the second direction Y are described as different embodiments. However, the first stretch sensing line181S disposed in the first direction X and the second stretch sensing line182S disposed in the second direction Y to sense the degree of stretch in both directions may be disposed together in the same first substrate111.

A more detailed description of the configuration of such stretch sensing lines according to an embodiment of the present disclosure is as follows.

FIG. 10is a schematic plan view for illustrating the configuration of stretch sensing lines disposed in a stretchable display device according to an embodiment of the present disclosure.FIG. 11is a cross-sectional view schematically showing one configuration example taken along line a-a′ ofFIG. 10.FIG. 12is a cross-sectional view schematically showing one configuration example taken along line b-b′ ofFIG. 10.FIG. 13is a cross-sectional view schematically showing another configuration example taken along line a-a′ ofFIG. 10.FIG. 14is a cross-sectional view schematically showing another configuration example taken along line b-b′ ofFIG. 10.FIG. 15is a cross-sectional view schematically showing another configuration example taken along line a-a′ ofFIG. 10.FIG. 16is a cross-sectional view schematically showing another configuration example taken along line b-b′ ofFIG. 10.

Referring toFIG. 10, a stretch sensing line180S disposed on a first substrate111may include a stretch sensing Rx line180Sa and a stretch sensing Tx line180Sb. Here, the stretch sensing line180S may include a first stretch sensing line181S and a second stretch sensing line182S. Such a stretch sensing line180S is disposed to have a wavy shape, for example, a sine waveform, so the stretch sensing line180S may have a plurality of bending points P. Hereafter, for helping understand description, a portion to a bending point that is adjacent in one direction with respect to any one bending point P is referred to and described as a first connecting portion180S1and a portion to a bending point that is adjacent in another direction with respect to any one bending point P is referred to and described as a second connecting portion180S2.

Referring toFIGS. 10 and 11, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb constituting the stretch sensing line180S may be disposed in a stacked type. However, in the stretch sensing line180S, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb may be disposed to cross at the bending point P. This is configured to sense the degree of stretch of a lower substrate110by sensing a capacitance C2difference between the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb in the present specification. This is for sensing the capacitance C2difference by disposing a stretch sensing Tx line180Sb at the first connecting portion180S1and a stretch sensing Rx line180Sa at the second connecting line180S2to face each other. However, an embodiment of the present disclosure in which a stretch sensing Rx line180Sa of the first connecting portion180S1and the stretch sensing Rx line180Sa of the second connecting line180S2are disposed to face each other is just described as an example, whereby it may be possible to sense the degree of stretch by sensing a capacitance difference according to the distance of them.

It may also be possible to sense a degree of stretch using the principles of a strain gauge in which the resistance of a wire, such as a copper wire, changes when it is either stretched or compressed. The various lines180s,181s182setc. can be comprised a copper or another metal that has a known change in resistance based on a selected stretch of the wire. In some embodiments, the flexibility of the display100will be of an amount that a stain gauge type stretch sensor will be acceptable, while in other embodiments, the flexibility may be so great that curved, twisty or more flexible connections is preferred to be used for lines180s,181s,182s, etc.

Referring toFIGS. 11 and 12, an insulating layer180Si is interposed between the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb. Looking into in more detail, the stretch sensing line180S may include a line damage suppression layer112S disposed on the first substrate111, a stretch sensing Rx line180Sa disposed on the line damage suppression layer112S, an insulating layer180Si disposed on the stretch sensing Rx line180Sa, and a stretch sensing Tx line180Sb disposed on the insulating layer180Si.

The line damage suppression layer112S is disposed along the line shape of the stretch sensing line180S, thereby being able to suppress damage by stretching of the stretch sensing line180S. In an embodiment, the line damage suppression layer may be disposed under the stretch sensing line in correspondence to the shape of the stretch sensing line. That is, when the stretch sensing line180S has a wavy shape, the line damage suppression layer112S may correspondingly have a wavy shape, and when the stretch sensing line180S has a straight shape, the line damage suppression layer112S may correspondingly have a straight shape. For example, the shape of the line damage suppression layer112S may substantially follow the shape of the stretch sensing line180S. The line damage suppression layer112S may be made of a material that is more rigid than the first substrate111and may be made of polyimide (PI), polyacrylate, polyacetate, or the like.

A stretch sensing Rx line180Sa and stretch sensing Tx line180Sb may be made of a flexible metal material. For example, the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb may be made of a metal material such as copper (Cu), silver (Ag), and gold (Au). However, the configuration of the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb is not limited thereto. For example, the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb may be made by distributing conductive particles in a stretchable base material made of a similar material as the first substrate111.

The insulating layer180Si may be made of an insulating material, and for example, may be made as a single inorganic layer made of a silicon nitride (SiNx), a silicon oxide (SiOx), or silicon oxynitride (SiON). However, the material constituting the insulating layer180Si is not limited only to an inorganic material and may be made of even an organic layer.

Referring toFIG. 11, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb of the first connecting portion180S1are stacked, and spaced and disposed by a predetermined distance, and capacitance between the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb In some embodiments may be referred to as first capacitance C1. That is, the first capacitance C1may be capacitance between the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb at the first connecting portion18051. Accordingly, the first capacitance C1value may be a constant value.

Further, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb of the second connecting portion180S2are stacked, and spaced and disposed by a predetermined distance and capacitance between the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb In some embodiments may be referred to as first capacitance C1. That is, the first capacitance C1of the first connecting portion180S1and the first capacitance C1of the second connecting portion180S2may have the same value.

Meanwhile, referring toFIG. 11, the capacitance between the stretch sensing Tx line180Sb of the first connecting portion180S1and the stretch sensing Rx line180Sa of the second connection portion180S2may be defined as second capacitance C2. Accordingly, the stretchable display device1000according to an embodiment of the present disclosure may sense the degree of stretch of a stretchable display device by sensing a change of the second capacitance C2.

Stretch sensing of the stretch sensing line180S configured as such may be made through the following expression.

In the above expression, C1is the first capacitance between the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb at the first connecting portion180S1and the second connecting portion180S2, C2is the second capacitance between the stretch sensing Tx line180Sb at the first connecting portion180S1and the stretch sensing Rx line180Sa at the second connecting portion180S2before stretching, and C2′ is the second capacitance between the stretch sensing Tx line180Sb at the first connecting portion180S1and the stretch sensing Rx line180Sa at the second connecting portion180S2after stretching.

In stretch sensing of the stretch sensing line180S configured as such, when the first capacitance C1value is large in comparison to the second capacitance value C2, sensing by stretch may be easy. For example, when the values of the first capacitance C1and second capacitance C2are the same, for example, assuming that the first capacitance C1and second capacitance C2values are each 2, a sensing value by stretch is calculated as ⅓ when substituting this value into the [Expression 1] and calculating (first embodiment). Meanwhile, when the first capacitance value of the first capacitance C1is larger than the second capacitance value of the second capacitance C2, for example, assuming that the first capacitance C1value is 6 and the second capacitance C2value is 3, a sensing value by stretch is calculated as ½ when substituting these values into the [Expression 1] and calculating (second embodiment). Further, when the first capacitance value of the first capacitance C1is smaller than the second capacitance value of the second capacitance C2, for example, assuming that the first capacitance C1value is 1 and the second capacitance C2value is 3, a sensing value by stretch is calculated as 1/12 when substituting these values into the [Expression 1] and calculating (third embodiment). As such, when the first capacitance C1value is higher than the second capacitance C2value, a sensing value by the largest stretch is derived, so it is possible to find out a sensing change by stretch of the first substrate111more easily than when the first capacitance C1value is higher than the second capacitance C2value.

As such, in order to more easily sense the degree of stretch of the first substrate111, the higher the dielectric constant of the insulating layer180Si than the first substrate111, the more advantageous it may be. Accordingly, the higher the dielectric constant of the insulating material making the insulating layer180Si than the insulating material making the first substrate111, the more advantageous it may be in stretch sensing of the first substrate111.

Further, in the stretch sensing line180S, the smaller the distance between the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb disposed on each of the first connecting portion180S1and the second connecting portion180S2before stretching than the distance between the stretch sensing Tx line180Sb of the first connecting portion180S1and the stretch sensing Rx line180Sa of the second connecting portion180S2, the more advantageous it may be in stretch sensing.

Meanwhile, looking into the configuration of the stretch sensing line180S at a bending point P with reference toFIG. 12, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb may be disposed in a stacked type on the same vertical axis.

As such, in the stretch sensing line180S, the configuration in which the stretch sensing Rx line180Sa and stretch sensing Tx line180Sb are stacked and the insulating layer180Si is interposed between the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb may be applied to the embodiment described with reference toFIGS. 2 and 5described above.

Meanwhile, the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb constituting the stretch sensing line180S are described above as being sequentially stacked with the insulating layer180Si therebetween, but the configuration of the stretch sensing line is not limited thereto.

Referring toFIGS. 13 and 14, a stretch sensing line180S according to another embodiment may be configured such that a stretch sensing Rx line180Sa and a stretch sensing Tx line180Sb are disposed in the same plane and an insulating layer180Si is disposed only on the stretch sensing Rx line180Sa. By simultaneously forming the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb and then forming the insulating layer180Si such that the insulating layer180Si is disposed only on the stretch sensing Rx line180Sa, it is possible to reduce process steps, as compared with the embodiment shown inFIGS. 10 and 11, so such a stretch sensing line180S according to another embodiment may be more advantageous in terms of process.

Further, referring toFIGS. 15 and 16, a stretch sensing line180S may be a structure in which a transparent conductive layer180St is further disposed in the structure of the stretch sensing line180S shown inFIGS. 13 and 14. That is, referring toFIGS. 15 and 16, the transparent conductive layer180St may be disposed to be in direct contact with the insulating layer180Si and the stretch sensing Tx line180Sb. In some embodiments, a transparent metal layer180St may be made of any one of an Indium Tin Oxide (ITO), an Indium Zinc Oxide (IZO), and an Indium Tin Zinc Oxide (ITZO). As such, by disposing the transparent metal layer180St over the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb and disposed to be in direct contact with any one of the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb, thereby being able optimizing touch sensitivity while increasing a first capacitance C1value.

In order to sense the degree of stretch of such a first substrate111, a stretch sensing unit may be further disposed in the stretchable display device1000according to an embodiment of the present disclosure.

FIG. 17is a block diagram of a stretchable display device according to an embodiment of the present disclosure.

Referring toFIG. 17, a stretchable display device according to an embodiment of the present disclosure may include a display panel1710, a timing controller1720, a stretch sensing unit1730, a gate driving unit1740, a data driving unit1750, and a memory1760.

The display panel1710includes a plurality of pixels PX electrically connected to n gate lines GL1, . . . , GLn disposed in a first direction, and m data lines DL1, . . . , DLm disposed in a direction that is different from the first direction. Accordingly, the plurality of pixels PX display an image by a driving signal or a driving voltage applied through the gate lines GL1, . . . , GLn and the data lines DL1, . . . , DLm.

The display panel1710includes an active area AA and a non-active area NA adjacent to the active area AA. A plurality of pixels PX is disposed in the active area AA and an image is displayed on the basis of gradation that each pixel PX displays. In each of the plurality of pixels PX, a pixel circuit in which a light emitting element from which light is emitted and a plurality of driving elements for driving the light emitting element are disposed is disposed. Because such a display panel1710is configured to be able to stretch, it may have a structure in which a second structure112made of a material that is more rigid than a first substrate111may be disposed in an area where pixels PX are disposed on the first substrate111made of a stretchable material.

In one embodiment ofFIG. 17, the pliable substrate111may be disposed only under the light emitting elements of the active area AA. The NA that is the rest of the display panel1710can be disposed on a more rigid substrate. Alternatively, the pliable substrate111may be disposed under the entire display panel1710so that the circuits in the NA, even those who do not omit light, can be flexed and stretched.

The timing controller1720processes image data RGB that are input from the outside to be suitable for the size and resolution of the display panel1710and then supplies the image data to the data driving unit1750. The timing controller1720creates a plurality of gate control signals GCS and data control signals DCS using synchronous signals SYNC, for example, a dot clock signal DCLK, a data enable signal DE, a horizontal synchronizing signal Hsync, and a vertical synchronizing signal Vsync. Further, the timing controller1720receives a stretch degree sensing value of the display panel1710sensed by the stretch sensing unit1730and creates an image compensation data cdata according to stretch of the display panel1710by comparing the received stretch degree value and a lookup table stored in advance in the memory1760, and may control the image compensation data to be applied to each pixel P through the data driving unit1750.

The stretch sensing unit1730is electrically connected to a stretch sensing line180S disposed in the display panel1710and may sense the degree of stretch before and after stretch of the display panel1710. The stretch sensing value SV sensed as such may be transmitted to the timing controller1720. The stretch sensing unit1730, as described above, senses a capacitance difference before and after stretch between a stretch sensing Rx line180Sa and a stretch sensing Tx line180Sb constituting the stretch sensing line180S and then may transmit a sensed value to the timing controller1720.

The gate driving unit1740supplies a gate signal to the n gate lines GL1, GLn in accordance with a gate control signal GCS supplied from the timing controller1720. In some embodiments, the gate signal may include at least one scan signal SCAN and light emitting control signal EM.

A common gate driving unit may be configured in a type in which it is formed independently from a display panel and electrically connected to the display panel in various ways. However, the gate driving unit1740of a stretchable display device according to an embodiment of the present disclosure may be built in a Gate In Panel (GIP) manner on a non-active area NA in a thin film pattern shape in substrate manufacturing of the display panel1710. AlthoughFIG. 17shows that only one gate driving unit1740is provided in a non-active area NA of the display panel1710, the present disclosure is not limited thereto and two gate driving units1740may be disposed at both sides of an active area AA.

Since the gate driving unit1740is disposed in built-in type in the display panel1710, a plurality of second substrates (112ofFIG. 1) may be disposed in a space type over the first substrate (111ofFIG. 1) in the non-active areas NA where the gate driving unit1740is disposed. That is, the gate driving unit1740may be made in a structure in which a circuit constituting each stage constituting the gate driving unit1740is disposed on the second substrate (112ofFIG. 1) and a connecting line connecting each stage is disposed on the first substrate (111ofFIG. 1).

The data driving unit1750converts image data RGB and compensation data cdata into a data voltage in accordance with a data control signal DCS supplied from the timing controller1720and supplies the converted data voltage to pixels P through the m data lines DL1, . . . , DLm. The voltage provided as the data value for the light emitting pixel elements can therefore be changed, whether to increase it or to decrease it to compensate the stretching of the display. The memory1760may store compensation data related to stretch of the display panel1710in a form of lookup table LUT. Although the memory1760is described as a separate configuration from the timing controller1720in an embodiment of the present disclosure, the memory1760is not limited thereto and may be made as a configuration that is included in the timing controller1720. The look up table can be created by performing a large number of stretches while measuring the change needed in the data signal to generate a light emitted at each pixel that has the same luminance value and characteristics both when it stretched and when it is not stretched. The stretch value can be measure locally, for a small group of pixels that are undergoing stretch and the compensation amount cdata, can be supplied to only those pixels, or it can be measured for the flexible display as a whole and applied to all active pixels on the display.

A method of sensing the degree of stretch of a stretchable display device according to an embodiment of the present disclosure configured as such is as follows.

FIG. 18is a flowchart sequentially showing an image compensation method of a stretchable display device according to an embodiment of the present disclosure.

The concepts disclosed herein include a method of sensing a stretching of a substrate and measuring the amount of stretch on an active basis, namely, while the stretch is occurring. Steps of this method are also shown inFIG. 18and are described below.

Referring toFIG. 18, the stretch sensing unit1730senses whether stretch of the display panel1710has occurred (S1810). The stretch sense of the display panel1710may sense the degree of stretch of the display panel1710in a period in which a data signal or a gate signal is not applied, in a case that a stretch sensing line senses panel stretch and transmits a data signal or a gate signal.

Further, when a stretch sensing line is separately disposed regardless of signal transmission for stretch sensing, it may be made by control of the timing controller1720or may be configured to sense whether there is stretch every set time.

Thereafter, when it is determined that stretch has been made by the stretch sensing unit1730(S1820), a sensing value of how much the display panel1710has been stretched is calculated (S1830). In some embodiments, a stretch degree sensing value may be calculated through [Expression 1] on the basis of a capacitance difference before and after stretch between the stretch sensing Rx line180Sa and the stretch sensing Tx line180Sb.

Such a stretch degree sensing value SV is transmitted to the timing controller1720and then the timing controller1720reads a predetermined reference value from the memory1760(S1840). In some embodiments, the predetermined reference value, as described above, may be stored in a lookup table type in the memory1760.

Thereafter, the timing controller1720creates compensation data cdata by comparing the predetermined reference value and the stretch degree sensing value (S1850) and applies the created compensation data cdata to each pixel P through the data driving unit1750(S1860) such that image distortion by stretch of the display panel1710is compensated by the compensation data, thereby being able to minimize deterioration of image quality.

According to one embodiment, a method of sensing an amount of stretch in a stretchable display is carried out by the following steps. There is a sensing a first reference value of stretch in a first substrate having a first modulus of elasticity. The first substrate is the flexible substrate111as described herein. There are plurality of rigid substrates112on the flexible substrate as described herein. After this first reference value is obtained, the first substrate is stretched a first distance. The second substrates are maintained as rigid and unstretched. As a result of the stretching, the second substrates are moved second substrates a second distant from each other that is greater than the first distance. During the stretching the electrical connection by a stretchable conductive line between the plurality of second substrates prior to and after the stretching is maintained. After the stretching the amount of stretch from the first reference value is sensed.

The method also includes generating a stretch compensation signal based on the measured amount of stretch during the stretching. During the stretching, a light emission data signal is transmitted to the organic light emitting diodes. In one embodiment, a timing controller that controls the stretch sensing line will sense a degree of stretch in a period when the data signal is not applied and transmit the data signal to the organic light emitting diode in a period after the degree of stretch has been sensed. A compensation signal to the data signal is generated based on the amount of stretch and the light emission data signal that is transmitted to the organic light emitting diode during the stretching is modified based on the generated compensation signal. In one embodiment, a gate drive signal is transmitted to the at least one transistor on the rigid substrate during the stretching.

After a period of time, the amount of stretch may increase and the steps described above and those shown inFIG. 18are repeated. Also, after a period of time, the stretching may end and the first substrate is returned to the unstretched shape after the stretching.