KR20200077322A - Display device - Google Patents

Abstract

The present invention provides a display device capable of increasing adhesive properties and mechanical reliability of a substrate by forming a rigid structure in a flexible substrate. According to the present invention, a display device may comprise: a flexible substrate in which a plurality of subpixels are defined; at least one thin film transistor and an organic light emitting diode disposed on the flexible substrate; and at least one rigidity reinforcing portion disposed in the flexible substrate and including a base portion and a plurality of protrusions protruding from the base portion.

Description

Display device {DISPLAY DEVICE}

The present invention relates to a display device and a method for manufacturing the same, and more particularly, to a display device capable of improving adhesion and mechanical reliability of a substrate when stress is applied.

As the information society develops, the demand for a display device for displaying images is increasing in various forms. The display field has rapidly changed to a thin, light and large-area flat panel display device (FPD), which replaces a bulky cathode ray tube (CRT). The flat panel display includes a liquid crystal display device (LCD), a plasma display panel (PDP), an organic light emitting display device (OLED), and an electrophoretic display device : ED).

Among them, the organic light emitting display device is a self-emission device that emits light by itself, and has a fast response speed, high light emission efficiency, high brightness, and a large viewing angle. In particular, the organic light emitting display device can be formed on a flexible flexible substrate as well as can be driven at a lower voltage than a plasma display panel or an inorganic electroluminescent (EL) display and consumes relatively little power. It has the advantage of excellent color.

Recently, a flexible display device that can be freely bent or bent has been developed. In a flexible display device, a thin film transistor and an organic light emitting diode are formed on an elastic transparent substrate surface. However, when the flexible display device is bent or curved, there is a problem in that cracks are generated at the edge portion of the substrate and adhesion to elements formed on the substrate is damaged or damaged.

The present invention provides a display device capable of forming a rigid structure in a flexible substrate and improving adhesion properties and mechanical reliability of the substrate.

The display device according to the present invention includes a flexible substrate having a plurality of sub-pixels defined, at least one thin film transistor and an organic light emitting diode disposed on the flexible substrate, and a plurality of sub-pixels disposed in the flexible substrate and protruding from the base portion and the base portion It may include at least one stiffness reinforcement portion including a protrusion.

The at least one rigid reinforcement part may be disposed to overlap with at least one of the plurality of subpixels.

The base portion and the plurality of protrusions may be integrally formed.

The base portion may be formed in a flat plate shape.

The plurality of protrusions may protrude in the same direction from one surface of the base.

The plurality of protrusions may protrude toward an outer surface of the flexible substrate.

The base portion may have a thickness of 5 to 50% compared to the thickness of the flexible substrate.

The plurality of protrusions may be 50 to 100% in length compared to the thickness of the base.

The distance between the plurality of protrusions may be 10 to 40% of the length of the base.

A part of the base part may have a surface exposed on an upper surface of the flexible substrate.

The display device according to the exemplary embodiment of the present invention includes a rigid reinforcement unit in the flexible substrate, so that surface stress is uniformly applied in the entire area when bending the flexible substrate, thereby preventing damage to the flexible substrate such as cracks. In addition, the display device according to the exemplary embodiment of the present invention has an advantage of reducing the surface stress of the flexible substrate by providing a rigid reinforcement portion in the flexible substrate.

1 is a schematic block diagram of an organic light emitting display device.
2 is a schematic circuit diagram of a subpixel.
3 is a detailed circuit configuration example of a sub-pixel.
4 is a plan view showing an organic light emitting display device.
5 is a plan view showing a sub-pixel of the organic light emitting display device according to the first embodiment of the present invention.
Figure 6 is a cross-sectional view taken along line I-I' of Figure 5;
7 to 9 are simulation results showing the surface stress when bending the flexible substrate.
10 is a cross-sectional view showing an organic light emitting display device according to a second embodiment of the present invention.
11 and 12 is a perspective view showing a rigid reinforcement according to a second embodiment of the present invention.
13 is a sectional view showing a rigid reinforcement according to a second embodiment of the present invention.
14 is a plan view showing another rigid reinforcement in the second embodiment of the present invention.
15 is a perspective view showing protrusions of a rigid reinforcement unit according to a second embodiment of the present invention.
16 is a plan view showing a sub-pixel array of an organic light emitting display device according to a second embodiment of the present invention.
17 is a sectional view showing a subpixel array according to a second embodiment of the present invention.
18 is a cross-sectional view showing a rigid reinforcement according to a second embodiment of the present invention.
19 to 21 are simulation results showing the surface stress when bending the flexible substrate according to the second embodiment of the present invention.
22 is a graph showing surface stress according to a region when bending a flexible substrate according to the first and second embodiments of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The same reference numbers throughout the specification refer to substantially the same components. In the following description, when it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description is omitted. In addition, the component names used in the following description may be selected in consideration of ease of specification preparation, and may be different from parts names of actual products.

The display device according to the present invention is a display device having a display element formed on a flexible substrate. As an example of the display device, an organic light emitting display device, a liquid crystal display device, an electrophoretic display device, or the like can be used. In the present invention, an organic light emitting display device is described as an example. The organic light emitting display device includes an organic film layer made of an organic material between the anode first electrode and the cathode second electrode. Accordingly, holes supplied from the first electrode and electrons supplied from the second electrode are combined in the organic layer to form excitons, which are hole-electron pairs, and are emitted by energy generated when the excitons return to the ground state. It is a self-luminous display device.

The display device according to the present invention can be easily and repeatedly performed with a predetermined ductility, such as rolling (or winding), unrolling, or unwinding. The display device can be wound in various directions as necessary. For example, the display device may be wound in the horizontal and/or vertical direction, or may be wound in the diagonal direction. The display device can be wound in the front direction and/or the rear direction.

Alternatively, the display device may be provided with a predetermined ductility, and a folding or unfolding operation may be repeatedly performed. Alternatively, the display device may be given a predetermined ductility, and an operation of stretching and restoring may be repeatedly performed.

The state change of the display device may be due to a physical external force provided directly by the user. For example, the user can implement a state change of the display device by gripping one end of the display device and providing a force thereto. The state change of the display device may be controlled through a control unit in response to a predetermined specific signal. That is, the state change of the display device can be controlled by the selected driving device and driving circuit.

1 is a schematic block diagram of an organic light emitting display device, FIG. 2 is a schematic circuit configuration diagram of a subpixel, FIG. 3 is a detailed circuit configuration example of a subpixel, and FIG. 4 is a plan view showing the organic light emitting display device to be.

As shown in FIG. 1, the organic light emitting display device includes an image processing unit 110, a timing control unit 120, a data driving unit 130, a scan driving unit 140, and a display panel 150.

The image processing unit 110 outputs a data enable signal DE and the like as well as a data signal DATA supplied from the outside. The image processing unit 110 may output one or more of a vertical synchronization signal, a horizontal synchronization signal, and a clock signal in addition to the data enable signal DE, but these signals are omitted for convenience of description.

The timing control unit 120 receives the data signal DATA along with a driving signal including a data enable signal DE or a vertical synchronization signal, a horizontal synchronization signal, and a clock signal from the image processing unit 110. The timing controller 120 is a gate timing control signal GDC for controlling the operation timing of the scan driver 140 based on the driving signal and a data timing control signal DDC for controlling the operation timing of the data driver 130. Outputs

The data driver 130 samples and latches the data signal DATA supplied from the timing controller 120 in response to the data timing control signal DDC supplied from the timing controller 120, converts it to a gamma reference voltage, and outputs it. . The data driver 130 outputs the data signal DATA through the data lines DL1 to DLn. The data driver 130 may be formed in the form of an integrated circuit (IC).

The scan driver 140 outputs a scan signal in response to the gate timing control signal GDC supplied from the timing controller 120. The scan driver 140 outputs a scan signal through the gate lines GL1 to GLm. The scan driver 140 is formed in the form of an integrated circuit (IC) or is formed in a gate in panel method on the display panel 150.

The display panel 150 displays an image corresponding to the data signal DATA and the scan signal supplied from the data driver 130 and the scan driver 140. The display panel 150 includes sub-pixels SP that operate to display an image.

The subpixels SP include red subpixels, green subpixels, and blue subpixels, or white subpixels, red subpixels, green subpixels, and blue subpixels. The subpixels SP may have one or more different emission areas according to emission characteristics.

As shown in FIG. 2, one subpixel includes a switching transistor SW, a driving transistor DR, a capacitor Cst, a compensation circuit CC, and an organic light emitting diode OLED.

The switching transistor SW operates to switch the data signal supplied through the data line DL to be stored as a data voltage in the capacitor Cst in response to the scan signal supplied through the first gate line GL1. The driving transistor DR operates such that a driving current flows between the power line EVDD (high potential voltage) and the cathode power line EVSS (low potential voltage) according to the data voltage stored in the capacitor Cst. The organic light emitting diode OLED operates to emit light according to the driving current formed by the driving transistor DR.

The compensation circuit CC is a circuit added in the subpixel to compensate for the threshold voltage of the driving transistor DR. The compensation circuit CC is composed of one or more transistors. The configuration of the compensation circuit CC is very diverse according to an external compensation method. An example of this is as follows.

As shown in FIG. 3, the compensation circuit CC includes a sensing transistor ST and a sensing line VREF (or reference line). The sensing transistor ST is connected between the source electrode of the driving transistor DR and the anode electrode of the organic light emitting diode OLED (hereinafter, a sensing node). The sensing transistor ST supplies the initialization voltage (or sensing voltage) transmitted through the sensing line VREF to the sensing node of the driving transistor DR or the sensing node of the driving transistor DR or the voltage of the sensing line VREF. Or it operates to sense the current.

In the switching transistor SW, a source electrode or a drain electrode is connected to the data line DL, and the other of the source electrode or the drain electrode is connected to the gate electrode of the driving transistor DR. In the driving transistor DR, the source electrode or the drain electrode is connected to the power line EVDD, and the other of the source electrode or the drain electrode is connected to the first electrode that is the anode of the organic light emitting diode OLED. The capacitor Cst has a lower electrode connected to the gate electrode of the driving transistor DR, and an upper electrode connected to the anode electrode of the organic light emitting diode OLED. In the organic light emitting diode OLED, the first electrode is connected to the other of the source or drain electrode of the driving transistor DR, and the second electrode, which is a cathode electrode, is connected to the second power line EVSS. The sensing transistor ST has a source electrode or a drain electrode connected to the sensing line VREF, and a source electrode to the other of the first electrode of the organic light emitting diode OLED and the source or drain electrode of the driving transistor DR. Alternatively, the other one of the drain electrodes is connected.

The operating time of the sensing transistor ST may be similar/same as or different from the switching transistor SW according to an external compensation algorithm (or configuration of the compensation circuit). For example, the switching transistor SW may have a gate electrode connected to the first gate line GL1, and the sensing transistor ST may have a gate electrode connected to the second gate line GL2. In this case, a scan signal Scan is transmitted to the first gate line GL1 and a sensing signal Sense is transmitted to the second gate line GL2. As another example, the first gate line GL1 connected to the gate electrode of the switching transistor SW and the second gate line GL2 connected to the gate electrode of the sensing transistor ST may be connected to share in common.

The sensing line VREF may be connected to the data driver. In this case, the data driver can sense the sensing node of the sub-pixel during real-time, non-display period of the image or N frame (N is an integer greater than or equal to 1) and generate a sensing result. Meanwhile, the switching transistor SW and the sensing transistor ST may be turned on at the same time. In this case, the sensing operation through the sensing line VREF and the data output operation for outputting the data signal are separated (divided) based on the time division method of the data driver.

In addition, the compensation target according to the sensing result may be a digital data signal, an analog data signal or gamma. In addition, the compensation circuit that generates a compensation signal (or compensation voltage) based on the sensing result may be implemented as an internal data driver, an internal timing controller, or a separate circuit.

The light blocking layer LS may be disposed only under the channel region of the driving transistor DR, or may be disposed under the channel region of the switching transistor SW and the sensing transistor ST as well as under the channel region of the driving transistor DR. The light blocking layer LS may be used for the purpose of simply blocking external light, or the light blocking layer LS may be connected to another electrode or line, and may be used as an electrode constituting a capacitor or the like. Therefore, the light blocking layer LS is selected as a metal layer of a multi-layer (multi-layer of different metals) so as to have light-shielding properties.

In addition, in FIG. 3, a subpixel having a 3T (Transistor) 1C (Capacitor) structure including a switching transistor SW, a driving transistor DR, a capacitor Cst, an organic light emitting diode (OLED), and a sensing transistor ST is shown. Although described as an example, when the compensation circuit CC is added, it may be configured of 3T2C, 4T2C, 5T1C, 6T2C, and the like.

Referring to FIG. 4, the organic light emitting display device includes a flexible substrate FSUB, a display unit AA, a non-display unit NA, a GIP driving unit GIP disposed on both sides of the display unit AA, and a lower side of the flexible substrate FSUB. It includes a pad portion (PD) disposed in. In the display unit AA, a plurality of sub-pixels SP are arranged to emit R, G, B or R, G, B, and W to realize full color. The GIP driving unit GIP is disposed on the non-display unit NA other than the display unit AA to apply a gate driving signal to the display unit AA. The pad portion PD is disposed on one side, for example, of the display portion AA, and chip-on films COF are attached to the pad portion DP. Data signals and power applied through the chip-on film COF are applied to a plurality of signal lines (not shown) connected from the display unit AA.

Hereinafter, the organic light emitting display device according to the embodiments of the present invention described above in detail.

<First Example>

5 is a plan view showing a sub-pixel of the organic light emitting display device according to the first embodiment of the present invention, FIG. 6 is a cross-sectional view taken along line I-I' of FIG. 5, and FIGS. 7 to 9 are views of the flexible substrate This is a simulation result showing the surface stress when bending.

In the organic light emitting display device according to an exemplary embodiment of the present invention, a plurality of subpixels are disposed to emit light of red (R), white (W), green (G), and blue (B) to produce full color. Implement it. In addition, a plurality of sub-pixels may be provided with cyan, magenta, and yellow pixels, and any known pixel configuration may be applied. In addition, although a plurality of sub-pixels shows a striping method in which red (R), white (W), green (G), and blue (B) are arranged in a single row, they are also arranged in a pentile manner. Can be.

In this embodiment, one subpixel of red, white, green, and blue will be described as an example. In addition, in the following description, a subpixel structure of 2T1C will be illustrated and described.

Referring to FIG. 5, the organic light emitting display device according to the first exemplary embodiment of the present invention includes a first gate line GL1 and a data line DL intersecting the first gate line GL1 on a flexible substrate (not shown). ) And the power line EVDD are arranged to divide the subpixels SP. The subpixel SP of the present invention refers to an inner region partitioned by the intersection of the first gate line GL1, the data line DL, and the power line EVDD. Although a gate line is not disposed in a lower portion of the subpixels SP in the drawing, subpixels SP may be defined because a gate line of an adjacent pixel exists.

A switching transistor SW, a driving transistor DR, and a capacitor Cst are disposed in each subpixel SP of the present invention, and an organic light emitting diode (not shown) to which the driving transistor Dr is connected is disposed. The switching transistor SW functions to select a pixel. The switching transistor SW includes a semiconductor layer 121, a gate electrode 123 branched from the first gate line GL1, a source electrode 124 branched from the data line DL, and a drain electrode 126. do. The capacitor Cst includes a capacitor lower electrode 127 connected to the drain electrode 126 of the switching transistor SW and a capacitor upper electrode 128 connected to the power line EVDD. The driving transistor DR serves to drive the first electrode 290 of the pixel selected by the switching transistor SW. The driving transistor DR includes a semiconductor layer 245, a gate electrode 255 connected to the capacitor lower electrode 127, a source electrode 270 branched from the power line EVDD, and a drain electrode 275. The organic light emitting diode (not shown) includes a first electrode 290 connected to the drain electrode 275 of the driving transistor DR, a light emitting layer (not shown) including a light emitting layer formed on the first electrode 290, and a second electrode. (Not shown).

Hereinafter, it will be described with reference to FIG. 6, which is a cross-sectional view taken along line I-I' of FIG.

Referring to FIG. 6, in the organic light emitting display device 100 according to the first embodiment of the present invention, at least one subpixel SP is positioned on the flexible substrate 200. The sub-pixel SP includes a driving transistor DR and an organic light emitting diode OLED connected to the driving transistor DR.

In more detail, the flexible substrate 200 has flexibility and can bend or bend freely to provide flexibility of the organic light emitting display device. The flexible substrate 200 is a transparent and elastic material, and for example, resins such as urethane, ethylene, styrene, siloxane, and rubber may be used. Preferably, the flexible substrate 200 may be made of polydimethylsiloxane (PDMS).

The first buffer layer 230 is positioned on the flexible substrate 200. The first buffer layer 230 serves to protect the transistor formed in a subsequent process from impurities flowing out of the substrate 200. The first buffer layer 230 may be silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof.

The light blocking layer 235 is positioned on the first buffer layer 230. The light blocking layer 235 blocks external light from entering and prevents photocurrent from occurring in the transistor. The light blocking layer 235 may be made of MoTi having excellent light absorption and conductivity. The second buffer layer 240 is positioned on the light blocking layer 235. The second buffer layer 240 insulates the light blocking layer 235 and protects a transistor formed in a subsequent process. The second buffer layer 240 is formed of the same material as the first buffer layer 230 described above.

The semiconductor layer 245 is positioned on the second buffer layer 240. The semiconductor layer 245 may be formed of a silicon semiconductor or an oxide semiconductor. The silicon semiconductor may include amorphous silicon or crystallized polycrystalline silicon. Here, polycrystalline silicon has a high mobility (over 100 cm 2 /Vs), low energy consumption, and excellent reliability, so it can be applied to gate drivers and/or multiplexers (MUX) for driving elements or to driving transistors within pixels. have. On the other hand, since the oxide semiconductor has a low off-current, it is suitable for a switching transistor having a short on time and a long off time. In addition, since the off current is small, the voltage retention period of the pixel is long, which is suitable for a display device requiring low-speed driving and/or low power consumption. In addition, the semiconductor layer 245 includes a drain region and a source region including p-type or n-type impurities, and a channel therebetween.

The gate insulating layer 250 is positioned on the semiconductor layer 245. The gate insulating layer 250 may be silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof. The gate insulating layer 250 may be formed on the entire flexible substrate 200, but may also be formed by patterning only a portion of the semiconductor layer 245. The gate electrode 255 is positioned on the gate insulating layer 250 in a certain region of the semiconductor layer 245, that is, a position corresponding to a channel when impurities are implanted. The gate electrode 255 is selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It is formed from any one or alloys thereof. In addition, the gate electrode 255 is a group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) It may be a multi-layer consisting of any one selected from or alloys thereof. For example, the gate electrode 255 may be a double layer of molybdenum/aluminum-neodymium or molybdenum/aluminum.

An interlayer insulating layer 260 insulating the gate electrode 255 is positioned on the gate electrode 255. The interlayer insulating film 260 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or multiple layers thereof. The source electrode 270 and the drain electrode 275 are positioned on the interlayer insulating layer 260. The source electrode 270 and the drain electrode 275 are connected to the semiconductor layer 245 through contact holes exposing the source/drain regions of the semiconductor layer 245, respectively. The source electrode 270 and the drain electrode 275 may be formed of a single layer or multiple layers, and when the source electrode 270 and the drain electrode 275 are single layers, molybdenum (Mo), aluminum (Al), and chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). In addition, when the source electrode 270 and the drain electrode 275 are multi-layered, a double layer of molybdenum/aluminum-neodymium, a titanium/aluminum/titanium, molybdenum/aluminum/molybdenum, or a three-layer of molybdenum/aluminum-neodymium/molybdenum It can be made. Accordingly, a driving transistor DR including the semiconductor layer 245, the gate electrode 255, the source electrode 270, and the drain electrode 275 is formed.

The overcoat layer 280 is positioned on the flexible substrate 200 including the driving transistor DR. The overcoat layer 280 may be a flattening film for alleviating the step difference of the lower structure, and is made of organic materials such as polyimide, benzocyclobutene series resin, and acrylate. The overcoat layer 280 may be formed by a method such as spin on glass (SOG) for coating the organic material in a liquid form and then curing. A via hole 285 exposing the drain electrode 275 is positioned in a portion of the overcoat layer 280.

An organic light emitting diode (OLED) is positioned on the overcoat layer 280. More specifically, the first electrode 290 is positioned on the overcoat layer 280. The first electrode 290 acts as a pixel electrode and is connected to the drain electrode 275 of the driving transistor DR. The first electrode 290 may be made of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO) as an anode.

When the organic light emitting display device is implemented in a top-emission type, the first electrode 290 may include a reflective layer and function as a reflective electrode. The reflective layer may be made of aluminum (Al), copper (Cu), silver (Ag), nickel (Ni), or alloys thereof, preferably APC (silver/palladium/copper alloy). The first electrode 290 may be formed of a multilayer including a reflective layer. For example, the first electrode 290 may be formed of a triple layer made of ITO/APC/ITO. When the organic light emitting display device is implemented as a bottom-emission type, the first electrode 290 may function as a transmissive electrode.

On the first electrode 290, a bank layer 300 partitioning a pixel is positioned. The bank layer 300 is made of organic materials such as polyimide, benzocyclobutene series resin, and acrylate. The bank layer 300 has an opening 310 exposing the first electrode 290. The organic layer 320 is positioned on the first electrode 290 exposed by the opening 310. The organic layer 320 includes a light emitting layer in which electrons and holes are combined to emit light, and may further include at least one of a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer.

The second electrode 330 is positioned on the organic layer 320. The second electrode 330 is a cathode electrode and may be formed of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or alloys thereof having a low work function.

When the organic light emitting display device is implemented as an upper emission type, the second electrode 330 may function as a transmission electrode. The second electrode 330 may be formed of a transparent conductive material such as Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO), and magnesium (Mg) and calcium (Ca) having a thickness thin enough to allow light to pass therethrough. , Aluminum (Al), silver (Ag) or alloys thereof. Alternatively, when the organic light emitting display device is implemented as a lower emission type, the second electrode 330 may function as a reflective electrode.

An encapsulation layer 340 may be disposed on the organic light emitting diode OLED. The encapsulation layer 340 may block moisture and/or oxygen from flowing into the organic light emitting diode (OLED), and may function to prevent a decrease in the lifetime and a decrease in luminance of the organic light emitting diode (OLED). The encapsulation layer 340 may be provided in a form in which at least one inorganic layer and at least one organic layer are stacked. The inorganic film and the organic film may be alternately arranged. Alternatively, the encapsulation layer 340 may include a metal material. For example, the encapsulation layer 340 may be made of iron (Fe), a nickel (Ni) alloy, invar, or steel use stainless (SUS) having a low thermal expansion coefficient.

Meanwhile, the organic light emitting display device according to the first embodiment of the present invention may include a rigid reinforcement unit 220 on the substrate 200.

The rigid reinforcement unit 220 may be disposed in the flexible substrate 200. Specifically, one surface of the rigid reinforcement unit 220 may be exposed outside the flexible substrate 200 and the other surface may be disposed inside the flexible substrate 200. The stiffness reinforcement unit 220 is provided with a predetermined stiffness, so that it can maintain a sturdy state compared to the surrounding area when the display device changes state. Since the rigidity reinforcement unit 220 can limit the state change of the display device by its rigidity, the rigidity reinforcement unit 220 is not formed on the front surface of the flexible substrate 200 but is formed locally in a predetermined region. The material constituting the rigid reinforcement unit 220 may be selected as a material having a higher rigidity than the material constituting the flexible substrate 200. For example, when the flexible substrate 200 is formed of a PDMS material, the stiffness reinforcement unit 220 may be formed of a polyimide (PI) or an acryl-based material having higher stiffness than polydimethylsiloxane (PDMS). The rigid reinforcement unit 220 may have a rectangular shape, such as the flexible substrate 200, and may be disposed on the flexible substrate 200.

The rigid reinforcement unit 220 is disposed in the flexible substrate 200, and the flexible substrate 200 is exposed to a high temperature environment and damaged during the process for forming the driving transistor DR and/or the organic light emitting diode OLED. It can function to prevent things. In addition, the rigidity reinforcement unit 220 may function to limit external force that causes displacement of the transistor DR and/or the organic light emitting diode OLED when the state of use of the display device changes (winding and unwinding, etc.). Can. That is, in the product use environment, the rigidity reinforcement unit 220 maintains a state in which the transistor DR and/or the organic light emitting diode OLED is disposed in a sturdy state compared to the surrounding area, so that the elements disposed in the area are It can function as a base layer that can minimize displacement.

7 to 9 are simulation results showing the surface stress when bending the flexible substrate. The simulation was performed by fabricating a flexible substrate with a rigid reinforcement. This simulation measured the degree of surface stress of the flexible substrate after bending some of the flexible substrate in a direction perpendicular to the longitudinal direction. 7 to 9 shows that the surface stress is relatively large as it goes from blue to red.

7 to 9, in the case of the first embodiment, it is shown that the surface stress exerts a great effect in the longitudinal direction from the center of the flexible substrate when the state of the flexible substrate changes. This may mean that when the state of the flexible substrate changes, surface stress is concentrated on a specific portion of the flexible substrate and does not act uniformly over the entire region. Therefore, the flexible substrate having a rectangular rigid reinforcement portion does not have a surface stress uniformly applied in the entire region when bending, and thus damage such as cracks in the flexible substrate may occur.

Hereinafter, in the second embodiment of the present invention, a structure capable of reducing the concentration of the surface stress of the flexible substrate is disclosed.

<Second Example>

10 is a cross-sectional view showing an organic light emitting display device according to a second embodiment of the present invention, FIGS. 11 and 12 are perspective views showing a rigidity reinforcing part according to a second embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a rigid reinforcement according to an embodiment, FIG. 14 is a plan view showing another rigid reinforcement according to a second embodiment of the present invention, and FIG. 15 is a perspective view showing protrusions of the rigid reinforcement according to a second embodiment of the present invention to be. In the following description, the same reference numerals are used for the same structures as the first embodiment described above, and the description thereof will be omitted.

Referring to FIG. 10, the organic light emitting display device according to the second exemplary embodiment of the present invention includes an organic light emitting diode connected to a flexible substrate 200, a rigid reinforcement unit 220, a driving transistor DR, and a driving transistor DR OLED).

The flexible substrate 200 is flexible and freely bends or bends to give flexibility of the organic light emitting display device. The flexible substrate 200 is a transparent and elastic material, and for example, resins such as urethane, ethylene, styrene, siloxane, and rubber may be used. Preferably, the flexible substrate 200 may be made of polydimethylsiloxane (PDMS).

The rigidity reinforcement unit 220 provided on the flexible substrate 200 may be disposed in the flexible substrate 200. Specifically, one surface of the rigid reinforcement unit 220 may be exposed outside the flexible substrate 200 and the other surface may be disposed inside the flexible substrate 200. The material constituting the rigid reinforcement unit 220 may be selected as a material having a higher rigidity than the material constituting the flexible substrate 200. For example, when the flexible substrate 200 is formed of a PDMS material, the stiffness reinforcement unit 220 may be formed of a polyimide (PI) or an acryl-based material having higher stiffness than polydimethylsiloxane (PDMS).

Specifically, referring to FIGS. 10 to 12, the rigid reinforcement unit 220 includes a plate-shaped base 222 and protrusions 224 protruding in one direction from the base 222.

The base portion 222 is formed of a flat plate shape and is given a predetermined rigidity, so that it can maintain a sturdy state compared to the surrounding area when the display device changes state. The base 222 is exposed on the top surface of the flexible substrate 200, and serves to maintain adhesion to the first buffer layer 230 formed on the base 222.

The protrusions 224 increase adhesion effective area with the flexible substrate 200 to improve adhesion with the flexible substrate 200, thereby dispersing surface stress when bending the flexible substrate 200. Due to the protrusions 224, the rigid reinforcing part 220 may be integrated with the flexible substrate 200 due to increased adhesion to the flexible substrate 200. In order to increase the effective area of adhesion with the flexible substrate 200, the protrusions 224 are projected in one direction from one surface of the base 222 to be formed in plural. The protrusions 224 are made of a plurality of pillar shapes. As illustrated in FIG. 10, the protrusions 224 have a plurality of pillar shapes protruding toward the outer surface of the flexible substrate 200.

Referring to FIG. 13, the base portion 222 of the rigid reinforcement portion 220 of the present invention may be formed to a thickness of 5 to 50% compared to the thickness of the flexible substrate 200. Here, if the thickness T of the base portion 222 is 5% or more with respect to the thickness of the flexible substrate 200, rigidity may be imparted to the flexible substrate 200. In addition, when the thickness T of the base portion 222 is 50% or less with respect to the thickness of the flexible substrate 200, it is possible to prevent the flexibility of the flexible substrate 200 from being reduced below a design value. For example, the flexible substrate 200 having a base 222 made of a thickness T of 20% of the thickness of the flexible substrate 200 is made of a thickness T of 30% of the thickness of the flexible substrate 200 It may be more flexible than the flexible substrate 200 having the base portion 222.

The protrusions 224 of the rigid reinforcing portion 220 of the present invention may be made of a length (L1) of 50 to 100% compared to the thickness (T) of the base portion (222). Here, when the length L1 of the protrusions 224 is 50% or more compared to the thickness T of the base 222, the effective area of adhesion between the protrusions 224 and the flexible substrate 200 is increased to increase the flexible substrate 200. It can disperse the surface stress when bending. When the length L1 of the protrusions 224 is 100% or less compared to the thickness T of the base 222, the protrusions 224 may be prevented from interfering with the flexibility of the flexible substrate 200.

Also, referring to FIG. 14, the protrusions 224 of the rigid reinforcing part 220 of the present invention may be arranged spaced apart from each other at regular intervals. The distance D at which the protrusions 224 are spaced apart may be 10 to 40% of the length L2 of the base 222. Here, if the gap D spaced apart from the protrusions 224 is too narrow, the protrusions 224 are densely formed to make it difficult to coat the flexible substrate 200 material on the rigid reinforcement part 220. However, in the present invention with reference to FIG. 14, if the distance D between the protrusions 224 is 10% or more compared to the length L2 of the base 222, the material of the flexible substrate 200 is placed on the rigid reinforcement part 220. When coating, it is possible to prevent coating between the protrusions 224.

In addition, if the number of protrusions 224 is too small, the area in contact with the flexible substrate 200 decreases and the adhesive strength decreases. In the present invention with reference to FIG. 14, the distance D between the protrusions 224 spaced apart is the base 222. If the length (L2) of 40% or less compared to the number of protrusions 224, it is possible to prevent at least the adhesive strength with the flexible substrate 200 is lowered.

Referring to FIG. 15, the protrusions 224 of the rigid reinforcement unit 220 of the present invention may be formed in various shapes in cross section. The shape of the cross section of the protrusions 224 may be a shape for improving the effective area of adhesion to the flexible substrate 200.

For example, as shown in FIGS. 11 and 12, the protrusions 224 may have a rectangular cross section. In addition, as illustrated in FIG. 15, the protrusions 224 may have a circular cross section, a triangular shape, a star shape, a pentagonal shape, or the like. However, the present invention is not limited to this, and any shape is possible as long as it is a shape for improving the effective area of adhesion to the flexible substrate 200.

16 is a plan view showing a subpixel array of an organic light emitting display device according to a second embodiment of the present invention, and FIG. 17 is a cross-sectional view showing a subpixel array according to a second embodiment of the present invention.

Referring to FIG. 16, in the organic light emitting display device according to the second embodiment of the present invention, a plurality of subpixels SP are disposed on the flexible substrate 200. Each sub-pixel SP is formed with an organic light emitting diode and is provided with a light emitting unit EA that emits light. As illustrated in FIG. 5, each subpixel SP is connected to the first gate line GL1, the data line DL, and the power lines EVDD to drive the organic light emitting diode. The first gate line GL1, the data line DL, and the power line EVDD are formed with a meandering curve, so that even if the organic light emitting display device is freely bent, it can be easily prevented from being shorted or damaged.

In addition, a liquid metal may be applied to the wirings of the first gate line GL1, the data line DL, and the power supply line EVDD. The liquid metal is a new alloy material made by mixing zirconium with titanium, nickel, and copper. In particular, it is molded into a free shape like plastic at high temperatures and has excellent strength. Accordingly, in the present invention, liquid metal is applied to wirings such as the first gate line GL1, the data line DL, and the power line EVDD to freely deform the flexible substrate when the organic light emitting display device is bent or bent. It is possible.

Referring to FIG. 17, the above-described rigid reinforcement unit 220 of the present invention is disposed corresponding to one sub-pixel SP formed on the display panel 150, respectively. That is, one rigid reinforcement unit 220 is disposed in a one-to-one correspondence with one sub-pixel SP. In this embodiment, although the shape of the rigid reinforcement unit 220 is shown as a rectangle, any shape is possible as long as it has the same shape as the shape of the sub-pixel SP. In addition, in the present embodiment, although one rigid reinforcement unit 220 is illustrated and described as one to one corresponding to one subpixel SP, one rigid reinforcement unit 220 includes at least two or more subpixels SP ). Alternatively, one or more rigid reinforcement units 220 may be disposed in one sub-pixel SP.

18 is a cross-sectional view showing a rigid reinforcement unit according to a second embodiment of the present invention.

As shown in FIG. 18, the rigid reinforcement part 220 of the present invention may be formed with a protrusion 224 from the end of the base part 222. 13, the protruding portion 224 of the rigid reinforcing portion 220 is shown and described as protruding away from the end of the base portion 222. However, the projecting portions 224 of the present invention may be projected to coincide with the ends of the base portion 222. The shapes of the protrusions 224 shown in FIGS. 13 and 18 do not significantly affect the adhesive strength and flexibility of the flexible substrate 200 and the rigid reinforcement unit 220, so that the protrusions 224 protrude from the base 222 Any shape is possible.

19 to 21 are simulation results showing the surface stress when bending the flexible substrate according to the second embodiment of the present invention. The simulation was performed by fabricating a flexible substrate having the rigid reinforcement shown in FIG. 13 described above. This simulation measured the degree of surface stress of the flexible substrate after bending some of the flexible substrate in a direction perpendicular to the longitudinal direction.

19 to 21, in the case of the second embodiment, it shows that the surface stress is uniformly applied to the entire flexible substrate when the state of the flexible substrate changes. This may mean that when the state of the flexible substrate changes, surface stress is not concentrated on a specific portion of the flexible substrate and acts uniformly over the entire region. Therefore, in the flexible substrate provided with the rigid reinforcement part according to the second embodiment of the present invention, surface stress during bending acts uniformly in the entire region, thereby preventing damage such as cracks in the flexible substrate.

22 is a graph showing surface stresses according to regions when bending the flexible substrate according to the first and second embodiments of the present invention. In the graph, the horizontal axis represents one side of the flexible substrate as 0 and the distance to the other side, and the vertical axis represents the surface stress value.

Referring to FIG. 22, in the flexible substrate of the first embodiment, a surface stress value for each region is from 17500000 to 24421242.38. In the flexible substrate of the second embodiment, the surface stress value for each region is from 2500000 to 19535811.86.

Through this, it is shown that when the rigid reinforcement part of the structure according to the second embodiment of the present invention is provided, the surface stress value of the flexible substrate can be significantly reduced.

As described above, the display device according to the exemplary embodiment of the present invention includes a rigid reinforcement unit in the flexible substrate, so that surface stress is uniformly applied in the entire area when bending the flexible substrate to prevent damage to the flexible substrate such as cracks. In addition, the display device according to the exemplary embodiment of the present invention has an advantage of reducing the surface stress of the flexible substrate by providing a rigid reinforcement unit in the flexible substrate.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the technical configuration of the present invention described above is in other specific forms without changing the technical spirit or essential features of the present invention by those skilled in the art to which the present invention pertains. It will be understood that it can be practiced. Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. In addition, all modifications or variations derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

200: flexible substrate 220: rigid reinforcement
222: base 224: protrusion

Claims (10)

A flexible substrate in which a plurality of subpixels are defined;
At least one thin film transistor and an organic light emitting diode disposed on the flexible substrate; And
A display device disposed on the flexible substrate and including at least one rigid reinforcement part including a base part and a plurality of protruding parts protruding from the base part. According to claim 1,
The at least one stiffness reinforcement unit is disposed to overlap with at least one of the plurality of sub-pixels. According to claim 1,
The base unit and the plurality of protrusions are integral display devices. According to claim 1,
The base portion is a display device made of a flat plate shape. According to claim 1,
The plurality of protrusions are display devices protruding in the same direction from one surface of the base. The method of claim 5,
The plurality of protrusions is a display device protruding toward the outer surface of the flexible substrate. According to claim 1,
The base portion is a display device made of a thickness of 5 to 50% of the thickness of the flexible substrate. According to claim 1,
The plurality of protrusions is a display device having a length of 50 to 100% of the thickness of the base portion. According to claim 1,
The display device comprising 10 to 40% of the length of the base portion is spaced apart from the plurality of protrusions. According to claim 1,
A display device with a surface of which is partially exposed on a top surface of the flexible substrate.

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