KR102636565B1 - Organic light emitting display device - Google Patents

Abstract

The present invention is intended to solve the above-described problems, and relates to an organic light emitting display device that can prevent defects in the display panel by reducing the resistance at the interface between the cathode electrode and the second auxiliary cathode electrode. a low-potential power supply voltage supply line formed in a non-display portion of the panel and supplying a low-potential power supply voltage to the display panel; a cathode electrode overlapping the low-potential power voltage supply line and having at least one contact portion; and an auxiliary cathode electrode disposed to overlap the low-potential power supply voltage supply line and the cathode electrode and connecting the low-potential power supply voltage supply line and the cathode electrode, and an edge of the auxiliary cathode electrode that overlaps the cathode electrode. The portion is characterized by comprising a plurality of concave portions and a plurality of convex portions.

Description

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

The present invention relates to an organic light emitting display device, and particularly to an organic light emitting display device that can increase the reliability of a contact portion between a low potential supply line and a cathode electrode of an organic light emitting diode.

Recently, various flat panel display devices are being developed that can reduce the weight and volume, which are disadvantages of cathode ray tubes (CRTs). Examples of such flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light emitting diode displays (OLEDs). : Organic Light Emitting Display), etc.

Among these flat panel displays, organic light-emitting diode displays are self-luminous displays that excite organic compounds to emit light. They do not require the backlight used in LCDs, so they are lightweight and thin, and have the advantage of simplifying the process. . In addition, organic electroluminescent display devices are widely used because they can be manufactured at low temperatures, have a high-speed response speed of 1 ms or less, and have characteristics such as low power consumption, wide viewing angle, and high contrast. there is.

Organic light emitting diode displays include organic light emitting diodes that convert electrical energy into light energy. An organic light emitting diode includes an anode electrode, a cathode electrode, and an organic light emitting layer disposed between these electrodes. Holes are injected from the anode electrode and electrons are injected from the cathode electrode. When holes are injected through the anode electrode and cathode electrode respectively and are injected into the organic emission layer (EML), an exciton is formed, and this exciton emits energy as light and emits light.

This organic light emitting diode display device includes a number of pixels divided by intersections of gate lines, data lines, and common power lines. Each pixel includes a switching thin film transistor, a driving thin film transistor, a storage capacitor, and an organic light emitting diode. The switching thin film transistor is turned on when a scan pulse is supplied to the gate line and supplies the data signal supplied to the data line to the storage capacitor and the gate electrode of the driving thin film transistor. The driving thin film transistor controls the amount of light emitted from the organic light emitting diode by controlling the current supplied from the power line to the organic light emitting diode in response to the data signal supplied to the gate electrode. The storage capacitor stores data supplied from the data line through the switching thin film transistor so that the driving thin film transistor can maintain light emission of the organic light emitting diode by supplying a constant current until the data signal of the next frame is supplied even if the switching thin film transistor is turned off. Charge the voltage.

Hereinafter, a conventional organic light emitting display device will be described with reference to FIG. 1 .

Figure 1 is a cross-sectional view showing a partial area of a conventional organic light emitting display device.

Referring to FIG. 1, a conventional organic light emitting display device includes a display panel 10, a control PCB 20, a source PCB 22, and a chip on film 24.

The chip-on-film 24 is electrically connected to the pads of the source PCB 22 and the data pads of the display panel 25. A source integrated circuit (hereinafter referred to as “source IC”) (SIC) as a source driving circuit is mounted on the chip-on-film 24.

Various wirings are formed on the source PCB 22 to supply digital video data and timing control signals from the control PCB 20 and the power voltage required for the display panel.

Control circuits and data transmission circuits are mounted on the control PCB (20). This control PCB (20) supplies timing control signals and various power voltages for controlling the operation of the data IC (SIC) along with data to the source IC (SIC) of the source COF (24) through the source PCB (22). do.

In FIG. 1, in order to avoid complicating the drawing, signal lines for supplying timing control signals, data signals, etc., and supply lines for supplying high-potential power are omitted, and the cathode electrode ( Only the low-potential power supply line (VSSL) for supplying the low-potential power supply voltage (VSS) to the CAT is shown.

In a conventional organic light emitting display device, as shown in FIG. 1, the low-potential power source (VSS) is transmitted from the control PCB 20 to the source PCB 22 and the source IC to the cathode electrode (CAT) formed on the display panel 10. is supplied to

The low-potential power supply voltage supply line (VSSL) for supplying the low-potential power supply voltage (VSS) is connected to the cathode electrode (CAT) through the control PCB (20), source PCB (22), and chip-on-glass (24).

However, the low-potential power supply voltage supply line (VSSL) is formed when forming the gate line on the display panel 10 of the organic light emitting display device to reduce the number of processes, and the cathode electrode (CAT) is formed by forming the organic light emitting diode after forming the data line. Since they are formed when forming an OLED, the low-potential power supply voltage supply line (VSSL) and the cathode electrode (CAT) are formed in different layers. Therefore, in order to connect the low-potential power supply line (VSSL) and the cathode electrode (CAT), a number of contact holes must be formed in the layer existing between them.

In this configuration, between the low-potential power supply voltage supply line (VSSL) and the cathode electrode (CAT), an insulating film covering the low-potential power supply voltage supply line (VSSL) is formed on the insulating film and forms the display area (active area) of the display panel. ), a first auxiliary cathode electrode formed on the same layer as the source / drain electrode of the thin film transistor, a passivation film covering the first auxiliary cathode electrode, an overcoat layer located on the passivation film for planarization, and on the overcoat layer. A second auxiliary cathode electrode formed on the same layer as the pixel electrode is disposed. In the contact area between the low-potential power supply voltage supply line (VSSL) and the cathode electrode (CAT), the first auxiliary cathode electrode is connected to the low-potential power supply voltage supply line (VSSL) through a through hole penetrating the interlayer insulating film, and the low-potential power supply The passivation film and overcoat layer on the voltage supply line (VSSL) are removed, the first auxiliary cathode electrode and the second auxiliary cathode electrode are directly connected, and the cathode electrode is disposed on the second auxiliary cathode electrode.

However, when the cathode electrode is placed on the second auxiliary cathode electrode, the second auxiliary cathode electrode formed of a transparent electrode such as ITO and the overcoat layer made of an organic insulating material disposed below the second auxiliary cathode electrode do not have good mutual contact, creating a void. This occurs, and as a result, when the cathode electrode is placed on the second auxiliary cathode electrode, if the metal material for forming the cathode electrode seeps into the gap, the thickness of the cathode electrode becomes thin.

Accordingly, the resistance at the interface where the second cathode auxiliary electrode and the cathode electrode contact increases, causing damage to the display panel when the display panel is driven for a long time.

Therefore, the present invention is intended to solve the above-mentioned problems, and its purpose is to provide an organic light emitting display device that can prevent defects in the display panel by reducing the resistance at the interface between the cathode electrode and the second auxiliary cathode electrode. .

The organic light emitting display device of the present invention for achieving the above object includes: a low-potential power supply voltage supply line formed in a non-display portion of a display panel and supplying a low-potential power supply voltage to the display panel; a cathode electrode overlapping the low-potential power voltage supply line and having at least one contact portion; and an auxiliary cathode electrode disposed to overlap the low-potential power supply voltage supply line and the cathode electrode and connecting the low-potential power supply voltage supply line and the cathode electrode, and an edge of the auxiliary cathode electrode that overlaps the cathode electrode. The portion includes a plurality of concave portions and a plurality of convex portions.

In the above configuration, the plurality of concave portions and the plurality of convex portions may be alternately arranged in n units (n is a natural number).

Additionally, the plurality of concave portions may have at least one shape among circular, oval, triangular, and polygonal shapes.

Additionally, the auxiliary cathode electrode may include: a first auxiliary cathode connected to the low-potential power supply voltage supply line through a plurality of contact holes penetrating an insulating film covering the low-potential power supply voltage supply line; and a second auxiliary cathode electrode disposed on the first auxiliary cathode electrode exposed through an inorganic insulating film and an organic insulating film sequentially covering the first auxiliary cathode electrode.

Additionally, the edge portion of the second auxiliary cathode electrode may include the plurality of concave portions and the plurality of convex portions.

Additionally, the inorganic insulating film and the organic insulating film include an opening exposing the first auxiliary cathode electrode, and the second auxiliary cathode electrode includes the first auxiliary cathode electrode and the inorganic insulating film exposed through the opening, and the organic insulating film. It is disposed in a partial area on the insulating layer, and the cathode electrode may be disposed on the organic insulating layer to cover the second auxiliary cathode electrode.

According to the organic light emitting display device according to the present invention, the contact line at the edge of the auxiliary cathode electrode disposed between the cathode electrode and the low-potential power voltage supply line is extended and lengthened, thereby reducing contact resistance, thereby increasing resistance even when the display panel is driven for a long time. You can achieve the effect of preventing damage to the display panel due to increased use.

1 is a plan view showing a portion of a conventional organic light emitting display device;
2 is a block diagram schematically showing an organic light emitting display device according to an embodiment of the present invention;
FIG. 3 is an equivalent circuit diagram schematically showing one pixel area of the display panel of the organic light emitting display device shown in FIG. 2;
4 is a plan view showing a partial area of an organic light emitting display device according to an embodiment of the present invention;
Figure 5 is a plan view showing area R1 in Figure 4;
Figure 6 is a cross-sectional view taken along line II' in Figure 5;
7A is a plan view showing an example of an auxiliary cathode electrode of an organic light emitting display device according to an embodiment of the present invention;
Figure 7b is a plan view showing another example of an auxiliary cathode electrode of an organic light emitting display device according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, the component names used in the following description may have been selected in consideration of ease of specification preparation, and may be different from the component names of the actual product.

Hereinafter, an organic light emitting display device according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3.

FIG. 2 is a block diagram schematically showing an organic light emitting diode display device according to an embodiment of the present invention, and FIG. 3 is an equivalent circuit diagram schematically showing one pixel area of the display panel of the organic light emitting diode display device shown in FIG. 2. am.

Referring to Figures 2 and 3, the organic light emitting display device according to the present invention provides a timing signal to the display panel (DP), a data driver (DD) disposed on one side of the display panel (DP), and a data driver (DD). a timing controller (TC), a gate driver (GD) disposed on the other side of the display panel (DP), and a high-potential voltage line (ELVDD) and a low-potential voltage line (ELVSS) that supply power to the display panel (DP). may include.

The data driver (DD) is equipped with a source IC (SIC), one side is connected to one end of the source printed circuit board (DPCB), and the other side is a chip-on-film (COF) attached to one end of the display panel (DP). Includes.

The data driver (DD) converts digital video data (RGB) input from the timing controller (TC) into an analog gamma compensation voltage and generates a data voltage. The data voltage output from the data driver DD is supplied to the data lines DL.

The gate driver (GD) includes a gate IC (GIC) and sequentially supplies gate pulses synchronized with the data voltage to the gate lines (GL) to select pixels of the display panel (DP) to which the data voltage is written.

The timing controller (TC) inputs timing signals such as the vertical synchronization signal (Vsync), horizontal synchronization signal (Hsync), data enable signal (Data Enable, DE), and main clock (MCLK) from the host system (HS). It synchronizes the operation timing of the data driver (DD) and the gate driver (GD). The data timing control signal for controlling the data driver (DD) includes a source sampling clock (SSC), a source output enable signal (Source Output Enable), etc. The gate timing control signal for controlling the gate driver (GD) includes gate start pulse (Gate Start Pulse, GSP), gate shift clock (GSC), and gate output enable signal (GOE). Includes. The timing controller (TC) may be mounted on a control PCB (CPCB).

The host system (HS) can be implemented as any one of a television system, set-top box, navigation system, DVD player, Blu-ray player, personal computer (PC), home theater system, and phone system. . The host system (HS) includes a system on chip (SoC) with a built-in scaler and converts digital video data (RGB) of the input image into a format suitable for display on the display panel (DP). The host system (HS) transmits timing signals (Vsync, Hsync, DE, MCLK) along with digital video data to the timing controller (TC).

The pixel array of the display panel DP includes pixels defined by the intersection of data lines DL and gate lines GL. Each pixel includes an organic light emitting diode (OLED), which is a self-luminous device.

Referring to FIG. 3 , a plurality of data lines DL and a plurality of gate lines GL intersect in the display panel DP, and pixels are arranged in a matrix form in each intersection area. Each pixel has an organic light-emitting diode (OLED), a driving thin film transistor (hereinafter referred to as TFT) (DT) that controls the amount of current flowing through the organic light-emitting diode (OLED), and a voltage between the gate and source of the driving TFT (DT). Includes a programming unit (SC) for setting.

The programming unit SC may include at least one switch TFT and at least one storage capacitor.

The switch TFT is turned on in response to a scan signal from the gate line GL, thereby applying the data voltage from the data line DL to one electrode of the storage capacitor.

The driving TFT (DT) controls the amount of light emitted by the organic light-emitting diode (OLED) by controlling the amount of current supplied to the organic light-emitting diode (OLED) according to the level of voltage charged in the storage capacitor. The amount of light emitted by an organic light emitting diode (OLED) is proportional to the amount of current supplied from the driving TFT (DT).

Each pixel is connected to a high-potential power supply voltage source (VDD) and a low-potential power supply voltage source (VSS), and receives high-potential power supply voltage and low-potential power supply voltage, respectively, from a power generator (not shown).

TFTs constituting a pixel may be implemented as a p type or as an n type. Additionally, the semiconductor layer of the TFTs constituting the pixel may include amorphous silicon, polysilicon, or oxide. An organic light emitting diode (OLED) includes an anode electrode (ANO), a cathode electrode (CAT), and an organic light emitting layer (not shown) interposed between the anode electrode (ANO) and the cathode electrode (CAT). The anode electrode (ANO) is connected to the driving TFT (DT). The organic light-emitting layer includes an emission layer (EML), a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and An electron injection layer (EIL) may be disposed.

Hereinafter, an organic light emitting display device according to an embodiment of the present invention will be described in more detail with reference to FIGS. 4 to 6.

FIG. 4 is a plan view showing a partial area of an organic light emitting display device according to an embodiment of the present invention, FIG. 5 is a plan view showing area R1 in FIG. 4, and FIG. 6 is a plan view along line II' of FIG. 5. This is a cross-sectional view taken.

First, referring to FIG. 4, the display panel (DP) of the organic light emitting display device according to an embodiment of the present invention receives a low-potential power supply voltage (VSS) through a chip-on-film (COF). It includes a cathode electrode (CAT) connected to a line (VSSL) and a low-potential power supply voltage supply line (VSSL).

In FIG. 4, in order to avoid complicating the drawing, signal lines for supplying timing control signals, data signals, etc., and high potential power supply voltage supply lines for supplying high potential power are omitted, and the organic light emitting display device It shows a low-potential power supply voltage supply line (VSSL) and a cathode electrode (CAT) for supplying a low-potential power supply voltage (VSS) to the cathode electrode (CAT).

Referring to FIGS. 5 and 6 showing region R1 in FIG. 4, the low-potential power supply voltage supply line (VSSL) is connected to the cathode electrode (CAT) through the first auxiliary cathode electrode (ACATa) and the second auxiliary cathode electrode (ACATb). ) is connected to. Hereinafter, the connection structure of the low-potential power supply line (VSSL) and the cathode electrode (CAT) will be described in more detail.

A buffer layer (BUF) is disposed on the substrate (SUB) of the display panel (DP), and a low-potential power supply voltage supply line (VSSL) is disposed on the buffer layer (BUF). The buffer layer (BUF) may be omitted.

An insulating film (ILD) is stacked on the low-potential power supply line (VSSL) to cover them.

A first auxiliary cathode electrode (ACATa) is disposed on the insulating film (ILD) to be connected to the low-potential power supply voltage supply line (VSSL) exposed through a plurality of contact holes (CH).

On the first auxiliary cathode electrode (ACTa), a passivation film (PAS) made of an inorganic insulating material to cover it and an overcoat layer (OC) made of an organic insulating material to planarize the passivation film (PAS) are sequentially laminated. The passivation film (PAS) and the overcoat layer (OC) have an opening OP exposing the first auxiliary cathode electrode ACATa.

A second auxiliary cathode electrode (ACATb) is formed on the overcoat layer (OC) to contact the first auxiliary cathode electrode (ACATa) exposed through the opening OP. The second auxiliary cathode electrode (ACATb) is present on the first auxiliary cathode electrode (ACATa) exposed through the opening OP, as well as on some areas of the passivation film (PAS) and the overcoat layer (OC).

The cathode electrode (CAT) of the organic light emitting diode is disposed on the overcoat layer (OC) on which the second auxiliary cathode electrode (ACATb) is formed to cover the second auxiliary cathode electrode (ACATb).

Next, the second auxiliary cathode electrode (ACATb) will be described in more detail with reference to FIGS. 7A and 7B.

FIG. 7A is a plan view showing an example of a second auxiliary cathode electrode of an organic light emitting display device according to an embodiment of the present invention, and FIG. 7B is a plan view showing another example of a second auxiliary cathode electrode of an organic light emitting display device according to an embodiment of the present invention. This is a floor plan showing an example.

Referring to FIGS. 7A and 7B, the second auxiliary cathode electrode (ACATb) according to an embodiment of the present invention is configured such that an edge portion includes a plurality of concave portions and a plurality of convex portions.

In Figure 7a, the concave part has an angled part, and in Figure 7b, the concave part has a circular part, and an example of a configuration in which the concave part and the convex part are alternately arranged is shown, but the present invention is not limited thereto. For example, the shape of the concave portion may have at least one of a circular shape, an oval shape, a triangular shape, and a polygonal shape.

Additionally, the examples of FIGS. 7A and 7B show an example in which concave portions and convex portions are alternately disposed, but concave portions and convex portions may be alternately disposed in n units (n is a natural number).

According to the second auxiliary cathode electrode (ACATb) as described above, the path of the edge portion of the second auxiliary cathode electrode (ACATb) in contact with the cathode electrode (CAT) is long, so from the perspective of the cathode electrode (CAT) 2 The amount of current supplied from the auxiliary cathode electrode (ACATb) to the cathode electrode (CAT) increases. According to Ohm's law, as the amount of current increases under the same voltage, the resistance decreases, so the resistance at the interface where the second auxiliary cathode electrode (ACATb) and the cathode electrode (CAT) meet decreases. Therefore, according to the organic light emitting display device according to an embodiment of the present invention, the resistance at the interface where the second auxiliary cathode electrode (ACATb) and the cathode electrode (CAT) meet is reduced, so that the display due to the increase in resistance even when the display panel is driven for a long time This has the effect of preventing damage to the panel.

Through the above-described content, those skilled in the art will be able to make various changes and modifications without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be determined by the scope of the patent claims.

CAT: cathode electrode CH: contact hole
ACATa: first auxiliary cathode electrode ACATb: second auxiliary cathode electrode
OC: Overcoat layer OP: Opening
VSS: Low-potential power supply line VSSL: Low-potential power supply line

Claims (7)

a low-potential power voltage supply line formed in a non-display portion of the display panel and supplying a low-potential power supply voltage to the display panel;
a cathode electrode overlapping the low-potential power voltage supply line and having at least one contact portion; and
It includes an auxiliary cathode electrode disposed to overlap the low-potential power supply voltage supply line and the cathode electrode and connecting the low-potential power supply voltage supply line and the cathode electrode,
An edge portion of the auxiliary cathode electrode that overlaps the cathode includes a plurality of concave portions and a plurality of convex portions,
An edge portion of the auxiliary cathode electrode including the plurality of concave portions and the plurality of convex portions is in contact with the cathode electrode,
The auxiliary cathode electrode is,
a first auxiliary cathode electrode connected to the low-potential power voltage supply line through a plurality of contact holes penetrating an insulating film covering the low-potential power supply voltage supply line; and
an inorganic insulating film sequentially covering the first auxiliary cathode electrode, and a second auxiliary cathode electrode disposed on the first auxiliary cathode electrode exposed through the organic insulating film and directly connected to the cathode electrode,
The second auxiliary cathode electrode completely overlaps the cathode electrode,
The cathode electrode completely covers the second auxiliary cathode electrode,
An organic light emitting display device in which no layer is interposed between the second auxiliary cathode electrode and the cathode electrode.
According to claim 1,
An organic light emitting display device in which the plurality of concave portions and the plurality of convex portions are alternately arranged in units of n (n is a natural number).
According to claim 1,
The organic light emitting display device wherein the plurality of concave portions have at least one shape selected from the group consisting of circular, oval, triangular, and polygonal shapes.
delete According to claim 1,
An edge portion of the second auxiliary cathode electrode includes the plurality of concave portions and the plurality of convex portions.
According to claim 5,
The inorganic insulating film and the organic insulating film include an opening exposing the first auxiliary cathode electrode,
The second auxiliary cathode electrode is disposed on the first auxiliary cathode electrode and the inorganic insulating film exposed through the opening, and a partial area on the organic insulating film,
The cathode electrode is disposed on the organic insulating film to cover the second auxiliary cathode electrode.
delete