KR102596934B1 - Organic light emitting display device - Google Patents

Abstract

This specification discloses an organic light emitting display device. The organic light emitting display device includes a first ground portion provided on the upper surface of a substrate; a second ground portion provided on the lower surface of the touch sensing layer on the substrate; It may include a conductive member connected between the first ground portion and the second ground portion.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY DEVICE}

This specification relates to an organic light emitting display device.

An organic light emitting display device is a device that displays images by controlling the amount of light emitted from an organic light emitting element. Organic light-emitting devices (organic light-emitting diodes, etc.) are self-luminous devices that use a thin light-emitting layer between electrodes and have the advantage of being able to be made into thin films. A typical organic light emitting display device has a structure in which a pixel driving circuit and an organic light emitting element are formed on a substrate, and the light emitted from the organic light emitting element passes through the substrate or barrier layer to display an image.

Because organic light emitting display devices are implemented without a separate light source device, they can be manufactured thinner and lighter than existing display devices such as liquid crystal displays (LCDs). Therefore, the organic light emitting display device can be easily implemented as a flexible, bendable, or foldable display device and can be designed in various forms.

The organic light emitting display device displays an image by emitting light from the light emitting diode of the selected subpixel when a scan signal and data voltage are supplied to the subpixels. To this end, the organic light emitting display device includes a driving circuit that drives the subpixels and a power circuit that supplies power to the subpixels. The driving circuit includes a scan driving circuit that supplies a scan signal (or gate signal) and a data driving circuit that supplies a data voltage.

The driving circuit and power circuit are becoming increasingly complex as they not only drive subpixels but also include various degradation compensation functions. Accordingly, various structures are being studied/applied to optimize the driving circuit and power circuit.

The purpose of this specification is to propose a ground structure for the power supply line of an organic light emitting display device. The tasks of this specification are not limited to the tasks mentioned above, and other tasks not mentioned can be clearly understood by those skilled in the art from the description below.

An organic light emitting display device is provided according to an embodiment of the present specification. The organic light emitting display device includes a first ground portion provided on the upper surface of a substrate; a second ground portion provided on the lower surface of the touch sensing layer on the substrate; It may include a conductive member connected between the first ground portion and the second ground portion.

The first ground portion may surround a display area where pixel circuits are arranged. The first ground unit may be connected to a low-potential power line that delivers low-potential power (VSS) to the pixel circuit. Alternatively, the first ground portion may be formed by exposing a low-potential power line that delivers low-potential power (VSS) to the pixel circuit. The first ground portion may be formed of the same material as the source electrode or drain electrode of the thin film transistor (TFT) included in the pixel circuit. The first ground portion and the second ground portion may overlap each other in the vertical direction.

The first ground portion and the second ground portion are connected to each other to expand the ground area, thereby suppressing fluctuations in the driving voltage supplied to the pixel circuit.

The organic light emitting display device may further include a polarization layer between the substrate and the touch sensing layer. At this time, the conductive member may be located on the side of the polarization layer to fill the space between the substrate and the touch sensing layer.

Specific details of other embodiments are included in the detailed description and drawings.

Embodiments of the present specification can provide a display device in which various problems caused by changes in voltage driving a pixel circuit are improved. Accordingly, embodiments of the present specification can provide an organic light emitting display device with improved display quality and reliability. Furthermore, embodiments of the present specification can contribute to improving the productivity of organic light emitting display devices. The effects according to the embodiments of the present specification are not limited to the contents exemplified above, and further various effects are included in the present specification.

1 shows an example display device that may be included in an electronic device.
Figure 2 is a cross-sectional view schematically showing a display area and a non-display area of a display device according to an embodiment of the present specification.
Figure 3 is an exemplary diagram showing the structure of a power supply unit of an organic light emitting display device according to an embodiment of the present specification.
4A and 4B are diagrams showing the structure of a power supply unit of an organic light emitting display device according to another embodiment of the present specification.

The advantages and features of the present specification and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining the embodiments of the present specification are illustrative, and the present specification is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise. When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used. When an element or layer is referred to as “on” another element or layer, it includes instances where the other layer or other element is directly on top of or interposed between the other elements. When a component is described as being “connected,” “coupled,” or “connected” to another component, that component may be directly connected or connected to that other component, but there are no other components between each component. It should be understood that may be “interposed” or that each component may be “connected,” “combined,” or “connected” through other components.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

The size and thickness of each component shown in the drawings are shown for convenience of explanation, and the present invention is not necessarily limited to the size and thickness of the components shown. Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings.

1 shows an example display device that may be included in an electronic device.

Referring to FIG. 1, the 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 placed around the display area. That is, the non-display area may be adjacent to one or more sides of the display area. In Figure 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 shown in FIG. 1. The display area and the non-display area may have a shape suitable for the design of an electronic device equipped with the display device 100. Exemplary shapes of the display area include pentagon, hexagon, circle, oval, etc.

Each pixel within 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 on a backplane. 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. Additionally, each pixel circuit may be connected to power supply lines (V _DD , V _SS , V _REF , etc.) located in the non-display area to receive the voltage required for driving.

As shown in FIG. 1, the driving circuit may be implemented as a thin film transistor (TFT) in the non-display area. This driving circuit may be referred to as a gate-in-panel (GIP). Additionally, some components, such as data driver ICs, are mounted on separate printed circuit boards and circuit films such as FPCB (flexible printed circuit board), COF (chip-on-film), TCP (tape-carrier-package), etc. It can be combined with a connection interface (PAD, bump, pin, etc.) placed in the non-display area.

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

Figure 2 is a cross-sectional view schematically showing a display area and a non-display area of a display device according to an embodiment of the present specification.

The illustrated display area (A/A) and non-display area (I/A) may be applied to at least a portion of the display area (A/A) and non-display area (I/A) depicted in FIG. 1 . Hereinafter, the display device will be described using an organic light emitting display device as an example.

In the case of an organic light emitting display device, the display area (A/A) includes thin film transistors (102, 104, 108), organic light emitting elements (112, 114, 116), and various functional layers on the base layer (101). are located Meanwhile, in the non-display area (I/A), various driving circuits (eg, GIP), electrodes, wiring, functional structures, etc. may be located on the base layer 101.

The base layer 101 supports various components of the organic light emitting display device 100. The base layer 101 may be formed of a transparent insulating material, such as glass, plastic, etc. The substrate (array substrate) is also referred to as a concept that includes devices and functional layers formed on the base layer 101, such as switching TFTs, driving TFTs, organic light emitting devices, and protective films.

A buffer layer 130 may be located on the base layer 101. The buffer layer is a functional layer to protect the thin film transistor (TFT) from impurities such as alkali ions leaking from the base layer 101 or lower layers. The buffer layer may be made of silicon oxide (SiOx), silicon nitride (SiNx), or a multilayer thereof. The buffer layer 130 may include multi buffers and/or active buffers.

A thin film transistor is placed on the base layer 101 or buffer layer. A thin film transistor consists of a semiconductor layer (active layer), a gate insulator (gate insulator), a gate electrode, an interlayer dielectric layer (ILD), and source and drain electrodes sequentially stacked. Alternatively, the thin film transistor may have a gate electrode 104, a gate insulating layer 105, a semiconductor layer 102, and a source and drain electrode 108 arranged sequentially as shown in FIG. 2.

The semiconductor layer 102 may be made of polysilicon (p-Si), in which case a predetermined region may be doped with impurities. Additionally, the semiconductor layer 102 may be made of amorphous silicon (a-Si), or may be made of various organic semiconductor materials such as pentacene. Furthermore, the semiconductor layer 102 may be made of oxide.

The gate electrode 104 is made of various conductive materials, such as magnesium (Mg), aluminum (Al), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), gold (Au), or alloys thereof. etc. can be formed.

The gate insulating layer 105 and the interlayer insulating layer (ILD) may be formed of an insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx), and may also be formed of an insulating organic material. By selectively removing the gate insulating layer 105 and the interlayer insulating layer, a contact hole exposing the source and drain regions may be formed.

The source and drain electrodes 108 are formed of a single-layer or multi-layered electrode material on the gate insulating layer 105 or the interlayer insulating layer. If necessary, a passivation layer 109 made of an inorganic insulating material may cover the source and drain electrodes 108.

A planarization layer 107 may be located on the thin film transistor. The planarization layer 107 protects the thin film transistor and planarizes its top. The planarization layer 107 may be formed in various forms, and may be formed of an organic insulating film such as BCB (Benzocyclobutene) or acryl, or an inorganic insulating film such as silicon nitride (SiNx) or silicon oxide (SiOx). Various modifications are possible, such as being formed as a single layer or consisting of double or multiple layers.

The organic light emitting device may have a first electrode 112, an organic light emitting layer 114, and a second electrode 116 arranged sequentially. That is, the organic light emitting device includes a first electrode 112 formed on the planarization layer 107, an organic light emitting layer 114 located on the first electrode 112, and a second electrode located on the organic light emitting layer 114 ( 116).

The first electrode 112 is electrically connected to the drain electrode 108 of the driving thin film transistor through a contact hole. When the organic light emitting display device 100 is a top emission type, the first electrode 112 may be made of an opaque conductive material with high reflectivity. For example, the first electrode 112 may be formed of silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), tungsten (W), chromium (Cr), or an alloy thereof. . The first electrode 112 may be an anode of an organic light emitting diode.

The bank 110 is formed in the remaining area excluding the light emitting area. Accordingly, the bank 110 has a bank hole that exposes the first electrode 112 corresponding to the light emitting area. The bank 110 may be made of an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx), or an organic insulating material such as BCB, acrylic resin, or imide resin.

The organic light emitting layer 114 is located on the first electrode 112 exposed by the bank 110 . The organic light-emitting layer 114 may include a light-emitting layer, an electron injection layer, an electron transport layer, a hole transport layer, and a hole injection layer. The organic light-emitting layer may be composed of a single light-emitting layer structure that emits a single light, or may be composed of a plurality of light-emitting layers that emit white light.

The second electrode 116 is located on the organic light emitting layer 114. When the organic light emitting display device 100 is a top emission type, the second electrode 116 is a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). By being formed of a material, the light generated in the organic light emitting layer 114 is emitted to the upper part of the second electrode 116. The second electrode 116 may be a cathode of an organic light emitting diode.

Encapsulation layer 120 is positioned on second electrode 116. The encapsulation layer 120 prevents oxygen and moisture from penetrating from the outside to prevent oxidation of the light emitting material and electrode material. When an organic light-emitting device is exposed to moisture or oxygen, pixel shrinkage, which reduces the light-emitting area, may occur, or dark spots may appear within the light-emitting area. The encapsulation layer is composed of an inorganic film made of glass, metal, aluminum oxide (AlOx), or silicon (Si)-based material, or an organic film 122 and an inorganic film 121-1, 121-2. This may be an alternating stacked structure. At this time, the inorganic film (121-1, 121-2) serves to block the penetration of moisture or oxygen, and the organic film 122 serves to flatten the surface of the inorganic film (121-1, 121-2). do. If the encapsulation layer is formed of multiple thin film layers, the movement path of moisture or oxygen becomes longer and more complicated than in the case of a single layer, making it difficult for moisture/oxygen to penetrate into the organic light-emitting device.

Although pixel circuits and light emitting devices are not disposed in the non-display area (I/A), a base layer 101 and organic/inorganic functional layers (130, 105, 107, 120, etc.) may be present. Additionally, materials used to construct the display area (A/A) may be disposed in the non-display area (I/A) for other purposes. For example, the same metal 104' as the gate electrode of the display area TFT, or the same metal 108' as the source/drain electrodes may be disposed in the non-display area I/A for wiring or electrodes. Furthermore, the same metal 112' as one electrode (eg, anode) of the organic light emitting diode may be disposed in the non-display area (I/A) for wiring and electrodes.

The base layer 101, buffer layer 130, gate insulating layer 105, planarization layer 107, etc. of the non-display area (I/A) are the same as those described in the display area (A/A). The dam 140 is a structure that prevents the organic layer 122 from spreading too far into the non-display area (I/A). Various circuits and electrodes/wires disposed in the non-display area (I/A) may be made of the gate metal 104' and/or the source/drain metal 108'. At this time, the gate metal 104' is formed from the same material as the gate electrode of the TFT in the same process, and the source/drain metal 108' is formed from the same material as the source/drain electrode of the TFT in the same process.

For example, source/drain metal may be used as a power source (e.g., low potential power supply (V _SS )) wiring 108'. At this time, the low-potential power wiring 108' is connected to the metal layer 112', and the cathode 116 of the organic light-emitting diode is connected to the source/drain metal 108' and the metal layer 112'. Power can be supplied through. The metal layer 112' may contact the power wiring 108', extend along the outermost sidewall of the planarization layer 107, and contact the cathode 116 at the top of the planarization layer 107. The metal layer 112' may be a metal layer formed from the same material and in the same process as the anode 112 of the organic light emitting diode.

A polarizing layer 170 may be located on top of the encapsulation layer 120. The polarization layer 170 may be provided to suppress visibility deterioration due to external light. Depending on the implementation, the polarization layer 170 may be provided only on the top of the display area A/A.

An adhesive layer 145 may be positioned between the polarizing layer 170 and the encapsulation layer 120. The adhesive layer 145 adheres the encapsulation layer 120 and the polarizing layer 170. The adhesive layer 145 may be a heat-curing or natural-curing type adhesive. For example, the adhesive layer 145 may be made of a material such as barrier pressure sensitive adhesive (B-PSA).

A touch-sensitive layer 180 may be disposed on the polarization layer 170. The touch sensing layer 180 may be provided to detect a user's touch input. The touch sensing layer 180 includes a touch sensing electrode that senses a touch input; a touch driving electrode that transmits a driving signal to the touch sensing electrode; Various conductors connecting the electrodes, pads provided for connection to a control circuit, etc. may be arranged. The touch sensing layer 180 and the polarizing layer 170 may be adhered to each other using a transparent adhesive (OCA, etc.).

Figure 3 is an exemplary diagram showing the structure of a power supply unit of an organic light emitting display device according to an embodiment of the present specification.

In an organic light emitting display device, the voltage of the received driving power ((V _REF , V _DD , V _SS , etc.) may vary depending on the position of the pixel. In the case of a low-potential power supply voltage (V _SS ), the voltage on one side of the display area It is applied to the inlet (e.g. PAD) and transmitted to the pixel circuit through a power line extending along the outside. At this time, the low-potential power supply voltage (V _SS ) transmitted to the pixel circuit far from the inlet is that of the conductor. It may be different from the voltage delivered to the pixel circuit near the inlet due to resistance, etc. If the low-potential power supply voltage (V _SS ) changes (rises or falls) in this way, in some pixels, the low-potential power supply voltage (V _SS ) and Since the margin between different driving voltages is not sufficiently secured, the luminance and/or color uniformity of the display area decreases. Additionally, this variation in low-potential power supply voltage (V _SS ) causes organic light emission. It may cause malfunction of the display device.

Recently, as organic light emitting display devices have become larger, the possibility of the above-mentioned power fluctuation problem occurring is increasing, and the need to improve this problem is increasing. As an improvement plan for the power fluctuation problem, as shown in FIG. 3, the display device 100 is connected to a circuit board 210 on one side to receive various control signals/power, etc., and is connected to a ground pad (GND) provided on the other side. A structure in which a low-potential power supply voltage line (EVSS) is connected is being applied. In addition, one side of the flexible circuit board 220 is attached to the ground pad (GND), and the other side of the flexible circuit board 220 is connected to the external ground 300 to strengthen grounding. Here, the external ground 300 may be a metal plate or frame that supports the display device.

Despite this complementary structure, it is difficult to provide multiple ground pads (GND) on the board. Accordingly, it is very difficult to completely suppress fluctuations (especially increases) in the low-potential power supply voltage (V _SS ). In addition, even if a sufficiently large number of ground pads (GND) can be made, the attachment process for the flexible circuit board 220 is added, thereby increasing material and process costs. Additionally, as additional processes are added, the tact time increases and the productivity of the display device decreases.

The inventors recognized this problem and designed a structure that suppresses fluctuations in low-potential power supply voltage more stably and efficiently.

4A and 4B are diagrams showing the structure of a power supply unit of an organic light emitting display device according to another embodiment of the present specification.

The organic light emitting display device 100 adopts an improved structure that maximizes the grounding area to suppress voltage fluctuations. In particular, the embodiment to be described below adopts a structure in which the grounding effect of the power supply line and manufacturing convenience are improved compared to the embodiment described in FIG. 3. FIGS. 4A and 4B are diagrams illustrating the present embodiment. For convenience of explanation, only specific components (eg, a ground portion) are shown and other elements are omitted. The organic light emitting display device 100 includes a first ground portion (GRD1) provided on the upper surface of the substrate 160; a second ground portion (GRD1) provided on the lower surface of the touch layer 180 on the substrate 160; It may be configured to include a conductive member 195 connected between the first ground portion (GRD1) and the second ground portion (GRD1).

The first ground portion GRD1 is provided on one side of the substrate 160 (the side facing the touch layer 180). Here, the substrate 160 refers to the lower part of the polarization layer 170 in the structure shown in FIG. 2, that is, from the base layer 101 to the encapsulation layer 120 or adhesive layer 145. A circuit board 210 is connected to the board 160 so that various control signals, power, etc. can be input. The first ground portion GRD1 may extend to surround the display area where the pixel circuits are arranged. At this time, the first ground portion (GRD1) may be formed on a single layer using the same material as the source electrode or drain electrode of the thin film transistor (TFT) included in the pixel circuit. Alternatively, a specific portion of the first ground portion (GRD1) may be connected to a conductor in another layer in a jumping structure. The jumping structure is connected through a contact hole or directly connected. The first ground portion GRD1 may be provided separately from and connected to a low-potential power line that delivers low-potential power V _SS to the pixel circuit. Alternatively, the first ground portion (GRD1) may be a low-potential power line itself that delivers low-potential power (V _SS ) to the pixel circuit. That is, the first ground portion GRD1 may be a low-potential power line that transmits low-potential power V _SS to the pixel circuit exposed to the outside. At this time, the upper insulating layers of the low-potential power line are removed.

The second ground portion GRD2 is provided on one side of the touch layer 180 (the side facing the lower substrate). The touch sensing layer 180 may be in the form of a film in which touch sensing electrodes, touch driving electrodes, etc. are arranged. The second ground portion (GRD2) may be used to ground electrodes, conductors, etc. that make up the touch sensing circuit. The second ground portion (GRD2) may overlap the first ground portion (GRD1) in the vertical direction. At this time, the widths of the second ground portion (GRD2) and the first ground portion (GRD1) may be the same or different.

The conductive member 195 physically/electrically connects the first ground portion (GRD1) and the second ground portion (GRD1). The conductive member 195 may be a conductive foam tape. The first ground portion (GRD1) and the second ground portion (GRD1) are combined through the conductive member 195 to provide a ground portion with a large area. That is, the first ground portion (GRD1) and the second ground portion (GRD2) are connected to each other through the conductive member 195 to expand the ground area, thereby providing the driving voltage supplied to the pixel circuit, especially the low-potential power supply voltage ( V _SS ) fluctuations can be suppressed. The first ground portion (GRD1) and the second ground portion (GRD1) may be connected to the ground of the touch sensing driving circuit or the system ground of the electronic device including the display device. Unlike the embodiment of FIG. 3, expanding the ground area in this way does not require additional attachment of a flexible circuit board, etc., so the increase in materials and processes, which had been pointed out as a disadvantage, can be solved.

The organic light emitting display device 100 according to this embodiment may further include a polarization layer 170 between the substrate 160 and the touch sensing layer 180. In this case, the conductive member 195 may be located on the side of the polarization layer 170 and fill the space between the substrate 160 and the touch sensing layer 180, as shown in FIG. 4B. If this space is empty, it must be trimmed to prevent damage to the display. However, if the space next to the polarizing layer is filled with a conductive member as in the embodiment, the trimming process can be omitted and the process can be streamlined.

Although embodiments of the present specification have been described in detail with reference to the attached drawings, the present specification is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit thereof. Accordingly, the embodiments disclosed in this specification are not intended to limit the technical idea of the present invention, but rather to explain it, and the scope of the technical idea of the present invention is not limited by these embodiments. Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, and can be technically linked and driven in various ways by those skilled in the art, and each embodiment can be performed independently of each other or together in a related relationship. It may be implemented. The scope of protection of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

Claims (11)

A first ground portion provided on the upper surface of the substrate;
a second ground portion provided on the lower surface of the touch sensing layer on the substrate; and
It includes a conductive member connected between the first ground portion and the second ground portion,
The first ground portion surrounds a display area where pixel circuits are arranged. According to claim 1,
The first ground portion surrounds three sides of the display area. According to claim 1,
An organic light emitting display device further comprising a polarizing layer between the substrate and the touch sensing layer. According to clause 3,
An organic light emitting display device wherein the conductive member is located on a side of the polarization layer. According to clause 4,
The conductive member fills a space between the substrate and the touch sensing layer. According to claim 1,
The first ground unit is connected to a low-potential power line that delivers low-potential power (V _SS ) to the pixel circuit. According to claim 1,
The first ground portion is an organic light emitting display device in which a low-potential power line that transmits low-potential power (V _SS ) to a pixel circuit is exposed to the outside. According to claim 6 or 7,
The first ground portion is formed of the same material as the source electrode or drain electrode of the thin film transistor (TFT) included in the pixel circuit. According to claim 1,
An organic light emitting display device wherein the first ground portion and the second ground portion overlap each other in a vertical direction. According to claim 1,
An organic light emitting display device that suppresses fluctuations in a driving voltage supplied to a pixel circuit by connecting the first ground portion and the second ground portion to each other to expand the ground area. According to claim 1,
The organic light emitting display device wherein the first ground portion and the second ground portion are in contact with three sides of the display area.

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