KR102333321B1 - Flexible display device - Google Patents

Abstract

The present specification discloses an organic light emitting display device. The organic light emitting display device includes: a flexible substrate including a first portion and a curved section bent to a predetermined curvature, and including a second portion disposed outside the first portion; an organic light emitting device disposed on the first portion on the first surface of the flexible substrate; a support layer disposed on the first portion and the second portion on the second surface of the flexible substrate; and a support member disposed on a second surface of the flexible substrate along a boundary line between the first portion and the second portion, wherein the support member has a shape formed by an edge of the first portion, at least a portion It is formed as a corresponding one-piece.

Description

Flexible display device {FLEXIBLE DISPLAY DEVICE}

The present invention relates to a flexible display device and a structure thereof.

Recently, a flexible display device capable of displaying an image even if it is bent like paper by forming a display unit and wiring on a flexible substrate such as plastic, which is a flexible material, is attracting attention as a next-generation display device.

As the range of application of the flexible display device to personal portable devices as well as monitors and TVs of computers is diversified, research on a flexible display device having a reduced volume and weight while having a large display area is in progress. In particular, an organic light emitting display (OLED), unlike a liquid crystal display (LCD), does not require a separate light source and thus can be implemented with a relatively thin thickness. Efforts to manufacture a flexible display device are continuing.

Meanwhile, as the display device is miniaturized, efforts are being made to reduce the bezel area in order to increase the effective display screen size in the display device having the same area. Accordingly, a technique for realizing an optimal bezel area has been introduced by using a flexible substrate as a substrate of a display device and bending a non-display area, which is an area on which an image is not displayed, on the flexible substrate.

[Related technical literature]

1. Narrow bezel type array substrate and liquid crystal display having the same (Patent Application No. 10-2010-0115912)

An object of the present specification is to provide an organic light emitting display device. More specifically, an object of the present specification is to provide a flexible display device having a plurality of curved portions. Another object of the present specification is to provide a support structure that allows an outer portion of a flexible display device to be bent effectively.

According to an embodiment of the present specification, an organic light emitting display device is provided. The organic light emitting display device includes: a flexible substrate including a first portion and a curved section bent to a predetermined curvature, and including a second portion disposed outside the first portion; an organic light emitting device disposed on the first portion on the first surface of the flexible substrate; a support layer disposed on the first portion and the second portion on the second surface of the flexible substrate; and a support member disposed on a second surface of the flexible substrate along a boundary line between the first portion and the second portion, wherein the support member has a shape formed by an edge of the first portion, at least a portion This corresponding one may be formed in one piece.

The shape formed by the edge of the first part is an N-gonal shape, the support member is disposed to correspond to two or more consecutive corners among the edges of the N-gonal shape, and the bending section of the second part includes the support member It may be bent at two or more consecutive corners among the corners of the N-shaped in contact with the .

The shape formed by the edge of the first part is a square shape, the support member is disposed to correspond to all four corners of the quadrangle, and the bending section of the second part is in contact with the support member at the four corners. can be bent

Among the second portions, at least one portion adjacent to a corner of the N-shaped by a predetermined distance or less may be chamfered.

The support member may have a rounded shape in which a surface in contact with the bending section of the second portion is rounded.

The support layer includes a first support film disposed on a first portion of the flexible substrate and a second support film disposed on a second portion of the flexible substrate, wherein the first support film and the second support film are They may be spaced apart from each other with a bending section therebetween.

The first portion may be a display area in which a plurality of pixels are disposed, and the second portion may be a non-display area in which wirings and driver circuits related to the plurality of pixels are disposed.

An organic light emitting diode and a pixel circuit for controlling light emission of the organic light emitting diode may be disposed in the first portion, and a gate-in-panel (GIP) circuit may be disposed in the second portion.

The pixel circuit is implemented by one or more thin-film transistors, and the GIP circuit is one or more thin-film transistors having a semiconductor layer different from that of the thin film transistor implementing the pixel circuit. can be implemented by

The thin film transistor implementing the pixel circuit may have a low temperature poly silicon (LTPS) semiconductor layer, and the thin film transistor implementing the GIP circuit may have an oxide semiconductor layer.

The thin film transistor implementing the pixel circuit may have an oxide semiconductor layer, and the thin film transistor implementing the GIP circuit may have a low temperature poly silicon (LTPS) semiconductor layer.

The pixel circuit is implemented by one or more thin-film transistors, and the GIP circuit includes one or more thin-film transistors having a stack structure different from that of a thin film transistor implementing the pixel circuit. can be implemented by

The thin film transistor implementing the pixel circuit may have a bottom gate structure, and the thin film transistor implementing the GIP circuit may have a co-planar structure.

The thin film transistor implementing the pixel circuit may have a co-planar structure, and the thin film transistor implementing the GIP circuit may have a bottom gate structure.

According to the exemplary embodiment of the present specification, bending at various sides of the display device is possible, so that a display device having a minimized side bezel can be provided. In addition, by using the integral member for supporting the multilateral bending, the above bending process can be easily and without error. In particular, the display device according to the embodiment of the present specification may be manufactured so that there is no mutual interference between the plurality of curved portions.

1 is a plan view of a flexible display device that may be included in an electronic device;
2 is a cross-sectional view schematically illustrating a stacked structure of a flexible display device according to an exemplary embodiment of the present specification.
3 is a plan view and a cross-sectional view of a curved pattern according to an embodiment of the present specification.
4A and 4B are diagrams illustrating a curved structure of a flexible display device according to an exemplary embodiment of the present specification.

In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It will be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component. Reference to an element or layer “on” another element or layer includes any intervening layer or other element directly on or in the middle of another element. The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not limited to the size and thickness of the illustrated component.

An “organic light emitting display device”, which may also be referred to as a “display device” herein, is used as a general term for an organic light emitting diode panel and a display device employing such an organic light emitting diode panel. In general, there are two different types of organic light emitting display devices, a white organic light emitting type and an RGB organic light emitting type. In the white organic light emitting type, each sub-pixel of a pixel is configured to emit white light, and a set of color filters is used to filter the white light to produce red light, green light and blue light in the corresponding sub-pixel. Also, the white organic light emitting type may include sub-pixels configured without a color filter to form sub-pixels for generating white light. In the RGB organic light emitting type, the organic light emitting layer in each sub-pixel is configured to emit light of a designated color. For example, one pixel includes a red subpixel having an organic light emitting layer emitting red light, a green subpixel having an organic light emitting layer emitting green light, and a blue subpixel having an organic light emitting layer emitting blue light .

In the present specification, a flexible display device refers to a display device to which flexibility is imparted, and includes a bendable display device, a rollable display device, an unbreakable display device, and a foldable display device. It is used in the same meaning as a foldable display device, a twistable display device, a stretchable display device, and a linkable display device. Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a plan view of a flexible display device that may be included in an electronic device.

Referring to FIG. 1 , the flexible display device 100 includes at least one active area, and an array of pixels is formed in the display area. One or more inactive areas may be disposed around the display area. That is, the non-display area may be adjacent to one or more side surfaces of the display area. In FIG. 1 , the non-display area surrounds a rectangular display area. However, the shape of the display area and the shape/arrangement of the non-display area adjacent to the display area are not limited to the example illustrated in FIG. 1 . The display area and the non-display area may have a shape suitable for designing an electronic device on which the flexible display device 100 is mounted. Exemplary shapes of the display area are pentagonal, hexagonal, circular, oval, and the like.

Each pixel in the display area may be associated with a pixel circuit. The pixel circuit may include one or more switching transistors and one or more driving transistors. Each pixel circuit may be electrically connected to a gate line and a data line to communicate with one or more driving circuits such as a gate driver and a data driver located in the non-display area.

As shown in FIG. 1 , the driving circuit may be implemented as a thin film transistor (TFT) in the non-display area. Such a driving circuit may be referred to as a gate-in-panel (GIP). In addition, some components such as data driver IC are mounted on a separate printed circuit board, and circuit films such as FPCB (flexible printed circuit board), COF (chip-on-film), TCP (tape-carrier-package), etc. It may be combined with a connection interface (pad/bump, pin, etc.) disposed in the non-display area by using the . The non-display area may be bent together with the connection interface, so that the printed circuit (COF, PCB, etc.) may be positioned behind the flexible display device 100 .

The flexible display device 100 may include various additional elements for generating various signals or driving pixels in the display area. Additional elements for driving the pixel may include an inverter circuit, a multiplexer, an electrostatic discharge circuit, and the like. The flexible display device 100 may also include an additional element related to a function other than driving a pixel. For example, the flexible display device 100 may include additional elements that provide a touch sensing function, a user authentication function (eg, fingerprint recognition), a multi-level pressure sensing function, a tactile feedback function, and the like. . The above-mentioned additional elements may be located in the non-display area and/or in an external circuit connected to the connection interface.

Several parts of the flexible display device 100 may be bent along the curved line BL. The curved line BL may extend horizontally (eg, in the X direction of FIG. 1 ), vertically (eg, in the Y direction of FIG. 1 ), or diagonally. Based on the design being made, it can be bent in any combination of horizontal, vertical, and diagonal directions.

As mentioned, one or more edges of the flexible display device 100 may be bent away from the planar portion 101 along the curved line BL. Although the curved line BL is illustrated to be positioned close to the edge of the flexible display device 100 , the curved line BL extends across the planar portion 101 or the flexible display device 100 . may extend diagonally at one or more corners of Such a structure may allow the flexible display device 100 to be a foldable display device or a display device in which displays are displayed on both sides of the display device.

Since one or more portions of the flexible display device 100 may be bent, a portion of the flexible display device 100 may be defined as a substantially flat portion and a curved portion. A portion of the flexible display device 100 is substantially flat and may be referred to as a planar portion 101. A portion of the flexible display device 100 is bent at a predetermined angle, and this portion is a curved portion. may be referred to as (102). The bent portion 102 includes a bent section that is actually bent to a predetermined radius of curvature.

2 is a cross-sectional view schematically illustrating a stacked structure of a flexible display device according to an exemplary embodiment of the present specification. In FIG. 2 , for convenience of explanation, it is illustrated that the flat portion 101 is substantially flat, and the curved portion 102 is located at a corner of the flexible display device 100 .

As shown, the one or more flexure portions 102 may flex outwardly from the substantially planar portion with a bend angle θ and a radius of curvature R relative to the flexure axis. The size of each of the curved portions 102 need not be the same. That is, the length from the curved line BL to the outer edge of the substrate 110 in each curved portion 102 may be different from each other. Further, the angle of curvature θ around the axis of flexion and the radius of curvature R from the axis of flexion may be different for each bent portion 102 .

In the example shown in FIG. 2 , the right side of the curved portion 102 has a bending angle θ of 90°, and the curved portion 102 includes a substantially planar section. The bent portion 102 is bent at a larger bending angle θ so that, like the left curved portion 102 of the flexible display device 100 , a portion of the bent portion 102 can go below the flat portion 101 . have. Further, the bent portion 102 may be bent at a bending angle θ of 90° or less.

In some embodiments, the radius of curvature of the bent portion 102 may be between about 0.1 mm and about 10 mm, preferably between about 0.1 mm and about 5 mm, or between about 0.1 mm and about 1 mm, or It may be between about 0.1 mm and about 0.5 mm. In some embodiments, the radius of curvature at the bent portion 102 may be less than 0.5 mm.

In order to increase strength and/or rigidity in a specific portion of the flexible display device 100 , one or more support layers 160 may be provided under the substrate 110 . For example, the support layer 160 may be provided on the inner surface of the planar portion. The support layer 160 may not be provided in a bending section requiring greater flexibility. The support layer 160 may be provided on the curved portion 102 positioned below the planar portion 101 . The increased strength in a specific portion helps in accurately configuring and arranging various components in the flexible display device 100 . When the substrate 110 has greater elasticity than the support layer 160 , the support layer 160 may contribute to suppressing cracking in the substrate 110 .

The substrate 110 and the support layer 160 may be made of a thin plastic film composed of a combination of polyimide, polyethylene naphthalate (PEN), polyethylene tereplate, and other suitable polymers. Other suitable materials that may be used to form the substrate 110 and the support layer 160 include thin glass, dielectric shielded metal foil, multilayer polymers, and polymeric materials in combination with nanoparticles or microparticles. and a polymer film contained therein. The support layer 160 provided on various portions of the flexible display device 100 does not need to be made of the same material. For example, while a thin glass layer is used as the support layer 160 for the flat portion 101 , a plastic film layer may be used as the support layer 160 for the corner portion.

The thickness of the substrate 110 and the support layer 160 is also another consideration in the design of the flexible display device 100 . In one aspect, if the substrate 110 has an excessive thickness, it is difficult for the substrate 110 to be bent with a small radius of curvature. In addition, the excessive thickness of the substrate 110 adds mechanical stress to the components disposed thereon during bending. However, on the other hand, if the substrate 110 is too thin, it will be too weak as a substrate to support components disposed thereon.

To satisfy this requirement, the substrate 110 may have a thickness of about 5 μm to about 50 μm. Preferably, the substrate 110 ranges from about 5 μm to about 30 μm, or from about 5 μm to about 5 μm. It may have a thickness in the range of 16 μm. The support layer 160 may have a thickness of about 100 μm to about 125 μm, about 50 μm to about 150 μm, about 75 μm to 200 μm, 150 μm or less, or 100 μm or more.

In one embodiment, a polyimide layer having a thickness of between about 10 μm and about 16 μm is used as the substrate 110 , and a polyethylene terephthalate (PET) layer having a thickness of between about 50 μm and about 125 μm is used as the support layer 160 . is used as In another embodiment, a polyimide layer having a thickness of between about 10 μm and about 16 μm is used as the substrate 110 , and a thin glass layer having a thickness of between about 50 μm and about 200 μm is used as the support layer 160 . In another embodiment, thin glass is used as the substrate 110 , and the substrate 110 has a polyimide layer serving as the support layer 160 to avoid breakage.

During the manufacturing process, some portions of the flexible display device 100 may be exposed to external light. A material used for manufacturing the components or the components themselves undergo an undesirable state change (eg, a threshold voltage transition in a TFT) due to light exposure during manufacturing of the flexible display device 100 . Some portions of the flexible display device 100 are excessively exposed to the external light compared to other portions. And this can cause non-uniformities (eg mura, shadow defects, etc.). In order to minimize this problem, the substrate 110 and/or the support layer 160 may include one or more materials capable of reducing the amount of external light.

For example, the light blocking material is carbon black chloride mixed with a constituent material (polyimide, other polymer) of the substrate 110 . As described above, the substrate 110 may be formed from polyimide having a shade providing a light blocking function. The substrate 110 may improve visibility by reducing reflection of external light incident from the front surface of the flexible display device 100 .

Instead of the substrate 110 , in order to reduce the amount of light incident from the rear surface of the flexible display device 100 (ie, the surface to which the support layer 160 is attached), the support layer 160 includes a light blocking material. You may. A material constituting the support layer 160 may be mixed with one or more light blocking materials, similar to those described above. Furthermore, both the substrate 110 and the support layer 160 may include one or more light blocking materials. Here, the light blocking material used for the substrate 110 and the support layer 160 does not need to be the same.

Allowing the substrate 110 and the support layer 160 to block unwanted external light improves display uniformity and reduces reflections, but also provides alignment markers for accurate positioning of components, or alignment markers for performing manufacturing processes. can be difficult to recognize. For example, since the arrangement of the layers is determined by comparing the outer edges of the overlapping portion, it is difficult to accurately arrange the components on the substrate 110 or to align the components during bending of the flexible display device 100 . It can be more difficult. In addition, if the substrate 110 and/or the support layer 160 blocks an excessive range of light spectrum (ie, wavelengths of visible light, ultraviolet light, and infrared spectrum), debris or foreign matter in the flexible display device 100 is removed. Checking can be problematic.

Accordingly, in some embodiments, the light blocking material included in the substrate 110 and/or the support layer 160 passes through a specific polarization and/or light within a specific wavelength range used in one or more manufacturing/inspection processes. configured to do As an example, the support layer 160 may pass light (eg, UV, IR) used in the quality inspection and/or alignment process, but block light in the visible wavelength range. The wavelength of the limited range is, when the substrate 110 includes a light blocking material. This helps to reduce the non-uniformity problem of the display device caused by shading caused by the printed circuit film attached to the substrate 110 .

The substrate 110 and the support layer 160 may block or pass a specific type of light together. For example, the support layer 160 may change the polarization of light so that the corresponding light does not pass through the substrate 110 . As such, a specific type of light may pass through the support layer 160 for various purposes during manufacturing of the flexible display device 100 , but is unnecessary for components disposed on the opposite side of the substrate 110 . In order not to affect it, it cannot pass through the substrate 110 .

A backplane of the flexible display device 100 is implemented on the substrate 110 . In some embodiments, the backplane of the flexible display device 100 is implemented with a TFT using a low temperature poly silicon (LTPS) semiconductor layer as an active layer. In one example, the pixel circuit and driving circuits (eg, GIPs) on the substrate 110 may be implemented as NMOS LTPS TFTs. In another example, the backplane of the flexible display device 100 may be implemented by a combination of an NMOS LTPS TFT and a PMOS LTPS TFT. For example, the driving circuit (eg, GIP) on the substrate 110 may include one or more CMOS circuits in order to reduce the number of wires for controlling the scan signal on the gate line.

In addition, in some embodiments, the flexible display device 100 may employ various types of TFTs to implement driving circuits in a pixel circuit in a non-display area and/or a display area. That is, to implement the backplane of the flexible display device 100 , a combination of an oxide semiconductor TFT and an LTPS TFT may be used. In the backplane, the type of TFT may be selected according to operating conditions and/or TFT requirements in the relevant circuit.

The LTPS TFT generally exhibits excellent carrier mobility even in a small profile, and thus is suitable for implementing an integrated driving circuit. The excellent carrier mobility makes LTPS TFTs ideal for components requiring high operating speed. Despite the above-mentioned advantages, the initial threshold voltage may be different between LTPS TFTs due to the grain boundary of the polycrystalline silicon semiconductor layer.

A TFT employing an oxide-based semiconductor layer such as an indium-gallium-zinc-oxide (IGZO) semiconductor layer (hereinafter referred to as an oxide TFT) is different from the LTPS TFT in many aspects. Despite the lower mobility compared to the LTPS TFT, the oxide TFT is generally more advantageous than the LTPS TFT in power efficiency. The low leakage current of the oxide TFT in the off state makes the active state last longer. This can be an important advantage for driving a pixel at a reduced frame rate when a high frame rate is not required to drive the pixel.

As an example, the flexible display device 100 may have a characteristic that all or some pixels of the display area are driven at a reduced frame rate under a specific condition. In this setting, the pixel may be refreshed at a reduced rate depending on the content displayed on the flexible display device 100 . Also, some display areas that display still image data (eg user interfaces, text) may be refreshed at a lower rate than other display areas that display fast-changing image data (eg movies). have. A pixel driven at a reduced refresh rate may have an increased blank period during which a data signal is not provided to the pixel. This will minimize the power consumed by providing the same image data to the pixels. In this embodiment, some TFTs implementing the pixel circuit and/or the driving circuit may be formed of oxide TFTs to minimize leakage current during the blank period. Leakage in the pixel circuit and/or the driving circuit By reducing the current, the pixel can achieve a more stable luminance level even when the display is refreshed at a reduced rate.

Another characteristic of the oxide TFT is that it does not suffer from the problem of the initial threshold voltage change between transistors as much as the LTPS TFT. This aspect can be a significant advantage when the size of the flexible display device 100 increases. Also, the threshold value shift between the LTPS TFT and the oxide TFT under bias stress is different.

In consideration of the above-mentioned characteristics of the LTPS TFT and the oxide TFT, some embodiments of the flexible display device 100 may be applied to a single backplane by combining the LTPS TFT and the oxide TFT. In particular, some embodiments of the flexible display device 100 employ LTPS TFTs to implement a driving circuit (eg, GIP) in a non-display area, and apply an oxide TFT to implement a pixel circuit in a display area. can Because of the excellent carrier mobility of the LTPS TFT, compared to the driving circuit implemented with oxide TFTs, the driving circuit implemented with the LTPS TFT can operate at a higher speed. In addition to this, a driving circuit more integrated by the LTPS TFT can be provided, whereby the size of the non-display area can be reduced. By the excellent voltage holding ratio of the oxide TFT used in the pixel circuit, the leakage current in the pixel can be reduced. In addition, this enables pixels to be driven at a reduced frame rate in a specific part of the display area or under preset conditions (eg, when displaying still images) while minimizing display defects caused by leakage current.

In some embodiments, the pixel circuit may be implemented as an oxide TFT, while the driving circuit may be implemented as a combination of an N-type LTPS TFT and a P-type LTPS TFT. For example, an N-type LTPS TFT and a P-type LTPS TFT may be used to implement a CMOS gate driver (eg, CMOS GIP, data driver). On the other hand, an oxide TFT may be applied to at least some portions of the pixel circuit. Unlike the GIP formed entirely of P-type or N-type LTPS TFTs, the gate output signal from the CMOS gate driver can be controlled by a DC signal or a logic high/low signal. This allows the gate line to be controlled more stably during the blank period, thereby suppressing current leakage from the pixel circuit and unintentional activation of the pixel.

The CMOS gate driver or inverter circuit on the backplane may be implemented as a combination of an LTPS TFT and an oxide TFT. For example, a P-type LTPS TFT and an N-type oxide TFT may be used to implement a CMOS circuit. In addition, the pixel circuit of the display area may be implemented using both the LTPS TFT and the oxide TFT. When applying the two types of TFTs to the pixel circuit and/or the driving circuit, to eliminate the bias remaining at the node between the oxide TFTs during the off-state, and to minimize the bias stress (eg, PBTS, NBTS), the LTPS TFT is It can be strategically placed inside the circuit. Additionally, a TFT connected to a storage capacitor in the circuit may be formed of an oxide TFT to minimize leakage current.

An organic light emitting device (OLED) layer is disposed on the substrate 110 . The organic light emitting device layer 122 includes a plurality of OLED devices. The OLED device is controlled by a pixel circuit and a driving circuit implemented on the substrate 110 , and another external driving circuit connected to a connection interface on the substrate 110 . The OLED layer includes an organic light emitting material layer emitting light of a specific color (eg, red, green, blue). In some embodiments, the organic light emitting material layer may have a stacked structure capable of emitting white light (essentially a combination of multiple colors of light).

The encapsulation layer 124 is provided to protect the organic light emitting device layer 122 from air and moisture. The encapsulation layer 124 may include several material layers to reduce the penetration of air and moisture. In some embodiments, the encapsulation layer 124 may be provided in a thin film shape.

The flexible display device 100 may include a polarization layer 130 to control display characteristics (eg, external light reflection, color accuracy, luminance, etc.). Also, the cover layer 150 may be used to protect the flexible display device 100 .

An electrode for sensing a user's touch input may be formed on one surface of the cover layer 150 and/or at least one surface of the polarization layer 130 . If necessary, an independent layer (hereinafter, referred to as the touch sensor layer 140 ) provided with a touch sensing electrode and/or other components associated with sensing a touch input may be provided in the flexible display device 100 . The touch sensing electrode (eg, touch driving/sensing electrode) is made of indium tin oxide, a carbon-based material such as graphene, carbon nanotubes, a conductive polymer, a hybrid material made of a mixture of various conductive/non-conductive materials, etc. It may be formed of a transparent conductive material. In addition, a metal mesh, for example, an aluminum mesh, a silver mesh, etc. may be used as the touch sensing electrode.

The touch sensor layer 140 may include one or more deformable dielectric materials. One or more electrodes may interface with the touch sensor layer 140 or may be located in the vicinity of the touch sensor layer 140, and may read a signal for measuring an electrical change on the electrode. The measurement is analyzed, and the amount of pressure input to the flexible display device 100 is evaluated using several samples.

In some embodiments, the touch sensing electrode may be utilized to identify a location of a user input and evaluate a pressure of the user input. The touch input position confirmation and touch pressure measurement may be performed by measuring a change in capacitance of a touch sensing electrode on one surface of the touch sensor layer 140 . The touch sensing electrode and/or other electrodes may be used to measure a signal indicating a pressure on the flexible display device 100 by a touch input. This signal is obtained from the touch sensing electrode at the same time as the touch signal or at a different timing.

The deformable material included in the touch sensor layer 140 may be an electrically active material, and the amplitude and/or frequency of the material is controlled by an electric signal and/or an electric field. Such a deformable material is a piezo ceramic, electro-active-polymers, and the like. Accordingly, the touch sensing electrode and/or the separate electrode may activate the deformable material to bend the flexible display device 100 in a desired direction. Additionally, the electrically active material is activated and vibrates at a desired frequency to provide tactile and/or texture feedback on the flexible display device 100 . The flexible display device 100 may employ a plurality of electrically active materials so that bending or vibration of the flexible display device 100 is provided at the same time or at different timings. Such a combination may be used to create a sound wave from the flexible display device 100 .

Some components may make it difficult to bend the flexible display device 100 along the curved line BL. Some components, such as the support layer 160 , the touch sensor layer 140 , and the polarization layer 130 , may add strength to the flexible display device 100 . In addition, the thickness of the components shifts the neutral plane of the flexible display device 100 , and accordingly, some of the components generate greater flexural stress than other components.

For easier bending and improved reliability of the flexible display device 100 , the configuration of components in the curved portion 102 is different from that in the substantially planar portion. Some components present in the substantially planar portion are not disposed in the bent portion 102 or are provided in different thicknesses. The support layer 160 , the polarization layer 130 , the touch sensor layer 140 , the color filter layer, and/or other components that interfere with the bending of the flexible display device 100 may not be present in the curved portion 102 . have. If the flexure portion 102 is not visible or accessible to the user, then such components are not required.

In order to provide information to the user, a secondary display area 102b is in the curved portion 102, however, depending on the purpose and/or form of the information provided by the secondary display area, some of the above components may not be necessary. not. For example, if the auxiliary display area emits only a color or displays text or a simple GUI only with a contrast combination (eg, black text or icon on a white background), the polarization layer 130 and/or the color filter layer may It is unnecessary for the bent portion 102 . In addition, if a touch function is unnecessary in the curved portion 102 , the touch sensor layer 140 may not be present. Although an auxiliary display area for displaying information is not provided in the curved portion 102 , if necessary, the curved portion 102 may include the touch sensor layer 140 and/or the electrically active material layer.

Since the bending section 102b is most affected by the bending stress, various stress reducing structures are applied to the components on the bending section. To this end, some of the components in the planar portion 101 are not present in at least one portion on the curved portion 102 . By selectively removing components in the bending section, a separation is achieved between the parts with the flat section 101 and the bending section 102 , whereby the bending section is freed from the respective components.

As shown in FIG. 2 , the support layer 160 in the flat portion 101 and the support layer 160 in the bent portion 102 are formed without the support layer 160 in the bent section 120b. As a result, they may be separated from each other. Instead of the support layer 160 attached to the substrate 110 , a support member 180 having a rounded end may be disposed in a lower curved section of the substrate 110 . Various other components, for example, the polarization layer 130 and the touch sensor layer 140 may not exist in the curved section 102b. The removal of the component may be performed through cutting, etching (wet etching, dry etching), scribing, or other suitable methods. Instead of cutting or other removal, divided pieces of the component may be formed in selected portions (eg, substantially planar portions and curved portions), such that no corresponding component is present in the bending section.

Instead of being completely removed from the flexion portion 102 , some components may have a flexion pattern along the flexion line and/or a portion within the flexion section to reduce flexural stress.

3 is a plan view and a cross-sectional view of a curved pattern according to an embodiment of the present specification. The curved pattern 300 may be applied to several components. The curved pattern 300 may be used for the support layer 160 , the polarization layer 130 , the touch sensor layer 140 , and the like.

The flexible display device 100 may utilize one or more curved patterns 300 . The number of bending patterns used in the parts and the shape of the bending patterns are not limited. If desired, the depth of the pattern 300 may be such that it penetrates completely through the part, but only partially penetrates each layer. In order to reduce bending stress, not only a passivation layer covering the conductive line, but also a buffer layer between the substrate 110 and the TFT may be provided with a curved pattern.

As mentioned, the support layer 160 does not exist in the bending section for easy bending of the substrate 110 . However, due to the absence of the support layer 160 , the curvature of the bent section is easily deformed by an external force. In order to support the substrate 110 and maintain the curvature of the curved section, the flexible display device 100 may include a support member 180 , which may be referred to as a mandrel. . The support member 180 shown in FIG. 2 includes a body portion and an end portion. The substrate 110 and the support member 180 are disposed such that a rounded end portion is positioned on a lower surface of the substrate 110 in correspondence to the curved section.

In an embodiment in which the curved portion 102 is at the corner of the flexible display device 100 , the support member 180 may be positioned at the corner of the flexible display device 100 . In this setting, as shown in FIG. 2 , a portion of the substrate 110 surrounds the end of the support member 180 and is positioned on the lower surface of the support member 180 . Various circuits and components (a driving IC, a connection interface with a connecting chip-on-flex (COF), a printed circuit board, etc.) in the non-display area are provided on the substrate 110 located behind the flexible display device 100 . may be provided on the In this way, even if it is not a flexible part, it may be positioned below the display area.

The support member 180 may be formed of a plastic material such as polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), or polyethylene terephthalate (PET). The strength of the support member 180 made of the plastic material may be controlled by an additive that increases the thickness and/or strength of the support member 180 . The support member 180 may be formed in a desired color (eg, black, white, etc.). In addition, the support member 180 may be made of a hard material such as glass, ceramic, metal, or a combination thereof.

The size and shape of the end portion of the support member 180 may vary depending on a desired minimum curvature in the bending section. In some embodiments, the thickness of the tip portion and the body portion may be substantially the same. In another embodiment, the planar body portion may be thinner than the tip portion. Having a thinner body portion, the support member 180 may support the bent section while avoiding an unnecessary increase in thickness of the flexible display device 100 .

Since the curved section is supported by the end portion of the support member 180 , the body portion extending toward the flat portion of the flexible display device 100 does not need to extend to the display area. If the body portion can extend below the display area for various reasons, the length of the body portion from the end portion toward the opposite end to the surface area for supporting the support member 180 is sufficient.

In order to secure the support member 180 in the flexible display device 100 , an adhesive layer 170 may be provided on a surface of the support member 180 . The adhesive layer 170 may include a pressure-sensitive adhesive, a foam-type adhesive, a liquid adhesive, a light-cured adhesive, or other suitable adhesive material. have. In some embodiments, the adhesive layer 170 may be formed of or include a material that can be compressed to function as a cushioning material for a portion adhered by the adhesive layer 170. For example, the adhesive layer 170 The constituent material of may be compressible. The adhesive layer 170 may be formed in a multi-layer structure, and the multi-layer structure includes a buffer layer (eg, polyolefin foam) disposed between upper and lower layers of an adhesive material layer.

The adhesive layer 170 may be located on one or more of the upper and lower surfaces of the body portion of the support member 180 . When the curved portion 102 of the flexible display device 100 wraps around the end portion of the support member, the adhesive layer 170 forms a lower surface (ie, a surface facing the rear surface) and an upper surface (ie, a front surface) of the body portion. and the side facing) may be provided. If necessary, an adhesive layer 170 may be provided between the end of the support member 180 and the inner surface of the substrate 110 .

During bending, a portion of the flexible display device 100 on one surface of the support member 180 may be pulled toward the support member 180 , and the substrate 110 may be disposed at an uppermost end of the end portion and It may be impacted by the lowermost edge. Accordingly, the height of the adhesive layer 170 and the height of the support layer 160 between the support member 180 and the substrate 110 are between the uppermost edge of the end and the surface of the body portion where the adhesive layer 170 is located. more than the vertical distance. In other words, the height of the space caused by the thickness difference between the end portion and the body portion is less than or equal to the sum of the thicknesses of the support layer 160 and the adhesive layer 170 .

Depending on the shape of the support member 180 , the thickness of the adhesive layer 170 on the upper and lower surfaces of the body portion may be different. For example, the body portion thinner than the end portion may not exist at the center of the end portion. In this case, the space on one side of the support member 180 may be larger than the space on the opposite side.

In another example, the lowest edge of the end portion is inside the bottom line of the body portion, leaving space on only one side of the body portion. In this case, the adhesive layer 170 on one side of the body portion may be thicker than the opposite side.

4A and 4B are diagrams illustrating a curved structure of a flexible display device according to an exemplary embodiment of the present specification.

4A and 4B illustrate the flexible display device 100 and the support member 180 as viewed from the rear surface (a surface opposite to the image display surface). As shown in FIG. 4A , the support member 180 is disposed on the rear surface of the flexible display device (substrate), and as shown in FIG. 4B , the outer portion of the flexible display device (substrate) is bent in the rear direction.

The flexible display device 100 may include a flexible substrate, an organic light emitting diode, a support layer, a support member, and the like. The structures of the flexible substrate, the organic light emitting diode, the support layer, and the support member are the same as those described with reference to FIGS. 1 to 3 .

The flexible substrate may include a first portion (planar portion); and a second portion (a curved portion) disposed outside the first portion, wherein the second portion may include a bending section bent to a predetermined curvature.

In this case, the first portion may be a display area in which a plurality of pixels are disposed. Also, the second portion may be a non-display area in which wirings and driver circuits related to the plurality of pixels are disposed.

The organic light emitting device may be disposed on the first portion on the first surface of the flexible substrate. In addition, an organic light emitting device and a pixel circuit for controlling light emission of the organic light emitting device may be disposed in the first portion. Meanwhile, a gate-in-panel (GIP) circuit may be disposed in the second portion.

The pixel circuit is implemented by one or more thin-film transistors, and the GIP circuit is one or more having a semiconductor layer of a different type than that of a thin film transistor implementing the pixel circuit. It may be implemented by a thin film transistor. For example, the thin film transistor implementing the pixel circuit may have a low temperature poly silicon (LTPS) semiconductor layer, and the thin film transistor implementing the GIP circuit may have an oxide semiconductor layer. Conversely, the thin film transistor implementing the pixel circuit may have an oxide semiconductor layer, and the thin film transistor implementing the GIP circuit may have a low temperature poly silicon (LTPS) semiconductor layer.

Meanwhile, the pixel circuit and the GIP circuit may be implemented by one or more thin film transistors having different types of stack structures. For example, the thin film transistor implementing the pixel circuit may have a bottom gate structure, and the thin film transistor implementing the GIP circuit may have a co-planar structure. Conversely, the thin film transistor implementing the pixel circuit may have a co-planar structure, and the thin film transistor implementing the GIP circuit may have a bottom gate structure.

The support layer may be disposed on the first portion and the second portion on the second surface of the flexible substrate. In this case, the support layer may include a first support film disposed on the first portion and a second support film disposed on the second portion, wherein the first support film and the second support film form the bending section. They may be disposed to be spaced apart from each other by being interposed therebetween.

The support member 180 may be disposed on the second surface of the flexible substrate along a boundary line between the first part and the second part. In this case, the support member 180 may have an integrated structure in which at least one portion corresponds to a shape formed by an edge of the first portion.

If a separate support member (eg a mandrel) is used for each of the N sides of the bend, it is difficult to place each support member in the correct position, and it takes a long time to work. However, in the present invention, by using the integrated support member, the above bending process can be easily performed without errors.

As shown in FIG. 4A , if the support member 180 has an edge having a predetermined width, the inside or the outside of the edge of the support member 180 may be aligned with the boundary line between the first part and the second part. If a narrower bezel width is desired, it is preferred that the outer side of the support member fits the perimeter.

If the shape formed by the edge of the first portion is an N-shaped shape, the support member 180 may be disposed to correspond to two or more consecutive corners among the N-gonal corners. Accordingly, the bending section of the second portion may be bent at two or more consecutive corners among the corners of the N-shaped in contact with the support member 180 . In addition, in order to prevent overlapping during bending, at least one or more portions 102c adjacent to the corner of the N-shaped by a predetermined distance or less among the second portions may be chamfered. Although FIG. 4A illustrates that a certain couple is chamfered at a right angle to each corner, the shape and size of the cut portion may be variously modified according to the design of the display device. For example, the cut portion may have a polygonal shape, a sector shape, an oval shape, or the like.

Referring to the examples of FIGS. 4A and 4B , the shape formed by the edge of the first part is a rectangular shape. Accordingly, the support member 180 may be formed in the form of a frame frame disposed to correspond to all four corners of the quadrangle. Of course, the support member 180 may be formed in a shape corresponding to two or three adjacent corners among four corners. Thereafter, the bending section of the second portion may be bent at the four corners in contact with the support member 180 . In this way, a display device having a rectangular display area can have no bezels at the four corners or can be made very small. Also, referring to FIG. 4B , it can be seen that the four vertex portions are cut so that the bent portions do not overlap each other when folded back.

The above description and the accompanying drawings are merely illustrative of the technical spirit of the present invention, and those of ordinary skill in the art to which the present invention pertains can combine configurations within a range that does not depart from the essential characteristics of the present invention. , various modifications and variations such as separation, substitution and alteration will be possible. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: flexible display device
101: flat part
102: bent part
102b: bend section
110: flexible substrate
122: organic light emitting device layer
124: encapsulation layer
160: support layer
170: adhesive layer
180: support member

Claims (14)

a first part; and
a flexible substrate including a bending section bent to a predetermined curvature and having a second portion arranged to form a boundary line with the first portion by surrounding an outer portion of the first portion;
an organic light emitting device disposed on the first portion on the first surface of the flexible substrate;
a support layer disposed on the first portion and the second portion on the second surface of the flexible substrate; and
and a support member disposed on the second surface of the flexible substrate along the boundary line and integrally disposed in the same shape as the boundary line. According to claim 1,
The shape formed by the boundary line is an N-gonal shape,
The support member is disposed to correspond to the boundary line of the N-shaped shape,
The curved section of the second portion is in contact with the support member and is bent in the direction of the second surface to form a corner. 3. The method of claim 2,
The N-shaped form is a square form,
An organic light emitting display device, characterized in that. delete 3. The method of claim 2,
The organic light emitting display device according to claim 1, wherein a surface of the support member in contact with the curved section of the second portion is rounded. According to claim 1,
The support layer is
a first support film disposed on a first portion of the flexible substrate and a second support film disposed on a second portion of the flexible substrate;
and the first support film and the second support film are spaced apart from each other with the bending section therebetween. According to claim 1,
The first portion is a display area in which a plurality of pixels are disposed,
and the second portion is a non-display area in which wirings and driver circuits related to the plurality of pixels are disposed. 8. The method of claim 7,
An organic light emitting device and a pixel circuit for controlling light emission of the organic light emitting device are disposed in the first portion,
and a gate-in-panel (GIP) circuit is disposed in the second portion. 9. The method of claim 8,
The pixel circuit is implemented by one or more thin-film transistors,
The GIP circuit is implemented by one or more thin film transistors having a semiconductor layer of a different type from that of the thin film transistor implementing the pixel circuit. 10. The method of claim 9,
The thin film transistor implementing the pixel circuit has a low temperature poly silicon (LTPS) semiconductor layer,
The thin film transistor implementing the GIP circuit has an oxide semiconductor layer. 10. The method of claim 9,
The thin film transistor implementing the pixel circuit has an oxide semiconductor layer,
The thin film transistor for implementing the GIP circuit comprises a low temperature poly silicon (LTPS) semiconductor layer. 9. The method of claim 8,
The pixel circuit is implemented by one or more thin-film transistors,
wherein the GIP circuit is implemented by one or more thin film transistors having a stack structure different from that of the thin film transistors implementing the pixel circuit. 13. The method of claim 12,
The thin film transistor implementing the pixel circuit has a bottom gate structure,
The thin film transistor implementing the GIP circuit has a co-planar structure. 13. The method of claim 12,
The thin film transistor implementing the pixel circuit has a co-planar structure,
The thin film transistor implementing the GIP circuit has a bottom gate structure.

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