KR20120041579A - Organic light emitting diodde desplay device - Google Patents

Abstract

PURPOSE: An organic light-emitting diode display device is provided to reduce resistance of a cathode power wiring without enlarging a bezel by forming the cathode power wiring as a structure put between an array substrate and an encapsulation substrate. CONSTITUTION: An active array indicating video data is formed on an array substrate(SUBS). An encapsulation substrate(EC) seals the active array. A cathode power wiring(CAT) is formed as a structure put between the array substrate and the encapsulation substrate. The cathode power wiring supplies cathode voltage to an organic light-emitting diode. A sealant(SL) is formed between the array substrate and the encapsulation substrate. The cathode power wiring comprises a first cathode power wiring formed on the array substrate, a spacer formed on the encapsulation substrate, and a second cathode power wiring contacted to the first cathode power wiring.

Description

Organic light emitting diode display device {ORGANIC LIGHT EMITTING DIODDE DESPLAY DEVICE}

The present invention relates to an organic light emitting diode display device including a cathode power supply wiring surrounding a non-display area outside of an active array.

Various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. Such flat panel displays include liquid crystal displays (hereinafter referred to as "LCDs"), field emission displays (FEDs), plasma display panels (hereinafter referred to as "PDPs") and electric fields. Light emitting devices; and the like.

PDP is attracting attention as the most advantageous display device for light and small size and large screen because of its simple structure and manufacturing process. TFT Film (Thin Film Transistor LCD) is the most widely used flat panel display device, but has a narrow viewing angle and low response speed. Electroluminescent devices are classified into inorganic electroluminescent devices and organic light emitting diode devices (hereinafter referred to as "OLEDs") according to the material of the light emitting layer. Self-luminous devices emit light by themselves and have fast response speed and high luminous efficiency, luminance, and viewing angle. There is this.

1A and 1B, an OLED display device includes an array substrate SUBS on which an active array AA is formed, an encapsulation substrate EC facing the substrate SUBS, and an array substrate SUBS and an encapsulation substrate EC. Sealant (SL) for joining the same. Sealant SL may generally be used as an ultraviolet curing agent. The active array AA displays video data including data lines, gate lines intersecting the data lines, and pixels arranged in a matrix form as shown in FIG. 2. Each pixel includes an OLED, a driving TFT DT, a switch TFT ST, a capacitor Cst, and the like as shown in FIG. 2. The pixels are supplied with a high potential supply voltage VDD and a cathode voltage. The driving TFT DT adjusts the amount of current flowing through the OLED according to the voltage (gate voltage) of the gate electrode to which the data voltage is applied. The switch TFT ST supplies the data voltage from the data line DL to the gate electrode of the driving TFT DT in response to the gate pulse supplied to the gate line GL. The anode electrode of the OLED is connected to the drain electrode of the driving TFT DT, and the cathode voltage is supplied to the cathode electrode of the OLED. OLEDs comprise multiple layers of organic compounds. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (Electron injection layer, EIL). When a driving voltage is applied to the anode and cathode electrodes of the OLED, electrons passing through the hole, the electron injection layer (EIL), and the electron transport layer (ETL) supplied through the hole injection layer (HIL) and the hole transport layer (HTL) are emitted from the light emitting layer ( EML) to form excitons, and as a result, the emission layer EML emits visible light.

In the array substrate SUBS, a cathode power wiring CAT is formed between the active array AA and the sealant SL. The cathode power wiring CAT surrounds the non-display area outside the active array and supplies the cathode voltage supplied from the outside to the OLED cathode electrode of each pixel through the cathode power input terminal.

The size of the active array (AA) of the OLED display device is increasing as the screens of smartphones and navigation devices become larger and applied to TVs. As a result, the cathode power wiring CAT surrounding the active array AA becomes longer, and as a result, the wiring resistance becomes larger, which increases the cathode voltage applied to the pixels. Hereinafter, the rise of the cathode voltage will be referred to as "cathode rising".

In the active array AA, P1 and P2 are closest to the cathode power input terminal, and P3 and P4 are farthest from the cathode power input terminal. The inventors of the present invention conducted an experiment for confirming the cathode rising of a conventional OLED display device. In the OLED display sample used in this experiment, the cathode power wiring (CAT) is a three-layer structure of titanium (Ti) / aluminum (Al) / titanium (Ti), the thickness is 500kW / 2000kW / 500kW. In addition, the wiring width of the cathode power supply wiring CAT formed on the OLED display sample is 100 μm. As a result of the experiment, when the cathode voltage was set to 0V, the voltages near P3 and P4 of the active array AA were measured to about 1.0208V due to the resistance of the cathode power supply wiring CAT. This cathode rising lowers the luminance of the pixels due to the OLED cathode voltage increase in pixels near P3 and P4, causes a luminance difference with pixels near P1 and P2, and also causes an increase in power consumption.

The large screen of OLED display device deepens the problem of cathode rising, and the problem of brightness difference and power consumption according to the screen position. In order to improve cathode rising, the wiring resistance of the cathode power supply wiring CAT can be increased to reduce the wiring resistance. However, since the bezel BZ is a non-display area, the size of the bezel BZ is reduced as much as possible. The larger bezel BZ limits the size of the active array AA and limits the aesthetic design of the screen.

The present invention provides an OLED display device capable of minimizing cathode rising without increasing bezel.

An OLED display device of the present invention comprises: an array substrate having an active array for displaying video data using OLED; An encapsulation substrate for encapsulating the active array; And a cathode power wiring formed in a structure filled between the array substrate and the encapsulation substrate to supply a cathode voltage to the OLED.

The present invention forms a cathode power wiring in a structure filled between the array substrate and the encapsulation substrate to increase the thickness of the cathode power wiring. Therefore, the present invention can reduce the resistance of the cathode power wiring without increasing the bezel.

1A is a plan view illustrating a conventional OLED display device.
FIG. 1B is a cross-sectional view of the OLED display taken along the line "I-I '" in FIG. 1A.
FIG. 3 is a diagram showing the results of a cathode rising experiment of the OLED shown in FIG. 1A.
4A is a plan view illustrating an OLED display device according to an exemplary embodiment of the present invention.
FIG. 4B is a cross-sectional view of the OLED display taken along the line "II-II '" in FIG. 4A.
FIG. 5 is a cross-sectional view illustrating in detail a first embodiment of the cathode wiring shown in FIGS. 4A and 4B.
6 is a cross-sectional view illustrating in detail a second embodiment of the cathode wiring shown in FIGS. 4A and 4B.
FIG. 7 is a cross-sectional view showing in detail a third embodiment of the cathode wiring shown in FIGS. 4A and 4B.
8 is a cross-sectional view showing in detail a fourth embodiment of the cathode wiring shown in FIGS. 4A and 4B.
9 and 10 illustrate a touch screen applied to an OLED display device according to an exemplary embodiment of the present invention.
11 is a view showing the results of the cathode rising experiment of the OLED display device according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like numbers refer to like elements throughout. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

4A and 4B, an OLED display device according to an exemplary embodiment of the present invention includes an array substrate SUBS on which an active array AA is formed, an encapsulation substrate EC facing the substrate SUBS, and an array substrate ( And a sealant SL for joining the SUBS and the encapsulation substrate EC. The array substrate SUBS may be used as a transparent substrate or a metal substrate. As the encapsulation substrate EC, a transparent substrate may be used. Sealant SL may generally be used as an ultraviolet curing agent.

The active array AA displays video data including data lines, gate lines intersecting the data lines, and pixels arranged in a matrix form as shown in FIG. 2. Each of the pixels includes an OLED, a driving TFT DT, a switch TFT ST, a capacitor Cst, and the like.

The cathode power wiring CAT is formed to have a structure filled between the array substrate SUBS and the encapsulation substrate EC. To this end, the cathode power wiring CAT may be formed on each of the array substrate SUBS and the encapsulation substrate EC to be in contact with each other, or may be implemented in combination with a spacer or a sealant. The cathode power wiring CAT supplies the cathode voltage supplied from the outside to the OLED cathode electrode of each pixel through the cathode power input terminal. Cathode power wiring (CAT) can reduce the resistance in the same material and the same wiring width compared to the prior art. Accordingly, the cathode power wiring CAT of the present invention can reduce its resistance without increasing the size of the bezel BZ in the large screen high resolution 0LED display device.

The cathode power wiring CAT may be made of the same metal as the prior art. Since the cathode power wiring CAT can increase the thickness to reduce the resistance, the wiring width can be designed to be equal to or less than that of the prior art, for example, between 50 μm and 100 μm. The thickness of the cathode power wiring CAT formed on the array substrate SUBS and the encapsulation substrate EC is determined by the thickness of the active array AA, the spacing between the array substrate SUBS and the encapsulation substrate EC, and the process technology. In consideration, it can be designed with a thickness of between 5000Å ~ 7000Å.

5 to 8 are diagrams illustrating various embodiments of the cathode wiring CAT.

Referring to FIG. 5, the first embodiment of the cathode interconnection CAT includes a first cathode interconnection formed on the array substrate SUBS and a second cathode interconnection formed on the encapsulation substrate EC. The first cathode wire may be formed of a three-layer structure of titanium (Ti), aluminum (Al), and titanium (Ti). The second cathode wiring includes a spacer CSP having a predetermined thickness and a metal layer covering the spacer CSP and contacting the first cathode wiring. The metal layer of the second cathode wiring may be formed of any one or more of titanium (Ti) and aluminum (Al). The spacer CSP may be formed of a non-conductive or conductive spacer, and a conductive spacer is preferable to reduce resistance.

Referring to FIG. 6, the second embodiment of the cathode interconnection CAT includes a first cathode interconnection formed on the array substrate SUBS and a second cathode interconnection formed on the encapsulation substrate EC. The first cathode wiring includes a metal wiring and a conductive spacer CSP covering the metal wiring. The metal wiring of the first cathode wiring can be formed in a three-layer structure of titanium (Ti) / aluminum (Al) / titanium (Ti) and the thickness thereof is formed at the same level as the prior art. The second cathode wiring includes a conductive spacer CSP. The conductive spacer CSP of the first cathode wiring and the conductive spacer CSP of the second cathode wiring are in contact with each other.

7 and 8, the third and fourth embodiments of the cathode wiring CAT include a metal wiring formed on the array substrate SUBS, a metal wiring covering the metal wiring, and between the array substrate SUBS and the encapsulation substrate EC. The conductive sealant CSL may be formed on and bond the substrates SUBS and EC to each other. As illustrated in FIG. 8, the conductive sealer CSL may cover only a part of the metal wiring to increase the bonding force between the array substrate AA and the encapsulation substrate EC. An existing nonconductive sealant SL may be disposed outside the conductive sealant CSL. The metal wiring can be formed in a three-layer structure of titanium (Ti) / aluminum (Al) / titanium (Ti) and the thickness thereof is formed at the same level as the prior art. The conductive sealant CSL may be used as a known conductive sealant. For example, a conductive sealant CSL including metal powder or conductive balls evenly dispersed in an ultraviolet curing agent may be used. According to the present invention, sealants SL and CSL are simultaneously drawn on an array substrate SUBS, and then the sealant EC is aligned and the sealant SL and CSL are irradiated with ultraviolet rays. (SL, CSL) can be formed simultaneously. The non-conductive sealant SL may be omitted as shown in FIG. 8.

The OLED display device of the present invention can be applied together with a touch screen. The touch screen may be implemented as a capacitive type, resistive type, or pressure type touch sensor, and may be disposed on the OLED display device in an on-cell or in-cell type. For example, the electrodes TS of the touch screen may be formed on the inner surface of the encapsulation substrate EC that faces the active array AA as shown in FIG. 9, and may be formed in the OLED display device in an in-cell type. In addition, the electrodes TS of the touch screen may be formed on the outer surface of the encapsulation substrate EC to form an on-cell type OLED display device as shown in FIG. 10.

11 shows the experimental results for the present invention. In this experiment, the cathode power wiring CAT had the structure as shown in FIG. 5 and was formed in a three-layer structure of titanium (Ti) / aluminum (Al) / titanium (Ti). The thickness of titanium (Ti) / aluminum (Al) / titanium (Ti) is 1000 kV / 4000 kV / 1000 kPa. The wiring width of the cathode power wiring CAT formed on the OLED display sample is 100 μm. As a result of the experiment, when the cathode voltage was set to 0V, the voltages near P3 and P4 of the active array AA were measured to about 0.5953V due to the resistance of the cathode power supply wiring CAT. As a result, the cathode rising of the present invention could be lowered to approximately 1/2 level compared to the prior art.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

CAT: Cathode Power Wiring AA: Active Array Board
SUBS: Array Board EC: Encapsulation Board
CSP: Spacer SL: Sealant

Claims (6)

An array substrate on which an active array for displaying video data using an organic light emitting diode is formed;
An encapsulation substrate for encapsulating the active array; And
And a cathode power line formed between the array substrate and the encapsulation substrate to supply a cathode voltage to the organic light emitting diode. The method of claim 1,
The cathode power wiring,
A first cathode power supply wiring formed on the array substrate; And
And a second cathode power line covering the spacer and in contact with the first cathode power line. The method of claim 1,
The cathode power wiring,
A metal wiring formed on the array substrate;
A first conductive spacer formed on the array substrate to cover the metal wiring; And
And a second conductive spacer formed on the encapsulation substrate and in contact with the first conductive spacer. The method of claim 1,
The cathode power wiring,
A metal wiring formed on the array substrate;
And a conductive sealant formed between the array substrate and the encapsulation substrate and covering at least a portion of the metal wiring. The method of claim 1,
The encapsulation substrate,
An organic light emitting diode display device comprising electrodes of a touch screen formed on the encapsulation substrate in an on-cell or in-cell type. The method of claim 2,
The cathode power wiring,
It comprises a metal layer of titanium (Ti) / aluminum (Al) / titanium (Ti),
An organic light emitting diode display device having a wiring width between 50 μm and 100 μm and a thickness between 5000 μm and 7000 μm.

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