KR100517251B1 - Electric wiring structure for Voltage stability - Google Patents

Abstract

The present invention relates to a panel using an organic light emitting diode, and more particularly, to remove an image quality unstable element of voltage drop through an extension of a power potential wiring that supplies power to an organic light emitting diode and a thin film transistor. It relates to a wiring structure that can be.

To this end, the present invention is defined as a subpixel having a switching thin film transistor, a driving thin film transistor, and an organic light emitting diode on a substrate, the plurality of subpixels are arranged adjacent to be defined as an active region, one side of the substrate An active matrix organic light emitting diode panel having a pad portion for supplying power to the active region, comprising: an external VDD wiring extending from the pad portion and wired to one outside of the active region; A first internal VDD interconnection in which a plurality of interconnections extend in parallel from the external VDD interconnection into the active region; A wire structure for reducing a power supply voltage drop in an active matrix organic light emitting device including a plurality of second internal VDD wires connecting the adjacent first internal VDD wires is proposed. It is characterized by the form.

Description

Wiring structure for reducing power supply voltage drop in active matrix organic light emitting display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to a wiring structure and a wiring method for reducing a power supply voltage drop in an active matrix organic electroluminescent device.

Organic / Polymer LED is a light emitting material made of organic material or conjugated polymer with semiconductor property and sandwiched between two electrodes, and when voltage is applied, current flows into the light emitting material and light is generated from organic material or polymer (called electroluminescence). It is a light emitting display element to be used. In terms of driving, TFT LCD, which is currently attracting much attention as FPD, realizes gradation by controlling the amount of light emitted from the backlight by applying a constant voltage to the liquid crystal. . In contrast, since AMOLED realizes gradation by adjusting light emission according to the amount of current flowing in the device, the unit pixel is composed of at least two TFTs that act as switching devices and driving TFTs that flow current.

AMOLED (active matrix organic light emitting diode) is a display device that puts organic EL (Electro Luminescence) on the active matrix.The organic EL device is a passive matrix type and an active matrix type depending on the structure. If you look briefly at the principle of operation, when power is supplied, electrons move and current flows. At the cathode, electron (-) moves to the light emitting layer with the help of electron transport layer, and at the anode, hole (+ concept) , The electrons are removed) is moved to the light emitting layer with the help of the hole transport layer. Electrons and holes encountered in the light emitting layer, which is an organic material, generate excitons having high energy. At this time, the excitons fall to low energy to generate light. The color of light will vary depending on which organic materials make up the light emitting layer, and full colors can be realized using the organic materials emitting R, G, and B. This is characterized by using organic material which emits light directly unlike LCD which simply opens and closes pixels.

As one of the new flat panel displays (FPD), the organic light emitting display device is self-luminous, and thus has a better viewing angle and contrast than the liquid crystal display device. It is also advantageous from the side. In addition, since it is possible to drive DC low voltage, fast response speed, and all solid, it is strong against external shock, wide use temperature range, and especially inexpensive in terms of manufacturing cost.

In particular, unlike the liquid crystal display device or the plasma display panel (PDP), the deposition and encapsulation equipments can be referred to in the manufacturing process of the organic light emitting device, and the process is very simple.

In the related art, a passive matrix having no separate switching device has been mainly used as a driving method of the organic light emitting device.

However, in the passive matrix method, the scan line and the signal line are crossed to form an element in a matrix form, and the scan line is sequentially driven over time in order to drive each pixel, thereby requiring an average luminance. In order to indicate, the instantaneous luminance is equal to the average luminance multiplied by the number of lines.

However, in the active matrix method, a thin film transistor, which is a switching element for turning on / off a pixel, is positioned for each sub pixel defined as a minimum unit area in which a screen is implemented. The first electrode connected to the thin film transistor is turned on and off in subpixel units, and the second electrode facing the first electrode becomes a common electrode.

In the active matrix method, a data voltage is charged in a storage capacitor (CST), and the power is applied until the next frame signal is applied, thereby for one frame regardless of the number of scan lines. Continue to drive.

Therefore, according to the active matrix method, since the same luminance is applied even when a low current is applied, it has the advantage of low power consumption, high definition, and large size.

Hereinafter, the basic structure and operation characteristics of the active matrix organic electroluminescent device will be described in detail with reference to the accompanying drawings.

1 is a view showing a basic pixel structure of a general active matrix organic electroluminescent device.

As shown, a scanning line is formed in a first direction, a signal line and a power supply line (VDD) are formed in a second direction crossing the first direction and spaced apart from each other by a predetermined distance. Define one subpixel area.

A switching TFT, which is an addressing element, is formed at an intersection point of the scan line and the signal line, and is connected to the switching thin film transistor and the power supply line VDD to form a storage capacitor C _ST . And a driving thin film transistor, which is connected to the storage capacitor C _ST and a power supply line VDD, to form a current source element, and is connected to the driving thin film transistor to form an organic electroluminescent diode. ) Is configured.

When the organic light emitting diode is supplied with a current in the forward direction, the organic light emitting diode has a positive (N) junction between the anode electrode, which is a hole providing layer, and the cathode electrode, which is an electron providing layer. Electrons and holes recombine with each other as they move through the part, and thus have a smaller energy than when the electrons and holes are separated, thereby utilizing the principle of emitting light due to the energy difference generated.

The organic light emitting diode is classified into a top emission type and a bottom emission type according to a traveling direction of light emitted from the organic light emitting diode.

2 is a schematic cross-sectional view of a conventional active matrix organic electroluminescent device.

As illustrated, a thin film transistor T is formed on the inner surface of the first substrate 10 in which a subpixel area, which is the smallest unit for implementing a screen, is defined, and is connected to the thin film transistor T. The first electrode 12 is formed in a pixel unit, and covers an edge portion of the first electrode 12 below the first electrode 12, and has a main region of the first electrode 12 as the opening 14. An interlayer insulating layer 16 is formed, and an organic light emitting layer 18 is formed below the interlayer insulating layer 16 and connected to the first electrode 12 through the opening 14 described above. ), A second electrode 20 is formed on the entire surface of the substrate.

The above-described subpixels consist of red, green, and blue subpixels that emit red, green, and blue colors, and the red, green, and blue subpixels form one pixel unit.

The organic light emitting layer 18 interposed between the first and second electrodes 12 and 20 and the first and second electrodes 12 and 20 forms an organic light emitting diode device (E).

The thin film transistor T includes a semiconductor layer 2, a gate electrode 4, a source electrode 6, and a drain electrode 8, and the first electrode 12 is substantially formed of the source electrode 8. Through the connection of the current is supplied from the thin film transistor (T).

Although not shown in detail in FIG. 2, the thin film transistor for an organic light emitting diode is a switching thin film transistor which serves as a switching element at a point where a gate wiring and a data wiring are crossed, a drain electrode and a power supply wiring of the switching thin film transistor. A driving thin film transistor (TDD) connected to the VDD to supply a current to the organic light emitting diode device E, and the thin film transistor T in the drawing corresponds to the driving thin film transistor.

The second substrate 22 is disposed to face the first substrate 10 and is an encapsulation substrate spaced apart from the organic light emitting diode device E by a predetermined distance. The first and second substrates are disposed. Edge portions between the substrates 10 and 22 are sealed by the seal pattern 30.

In addition, a recess 24 is formed in the inner central portion of the second substrate 22, and the recess 24 includes a moisture absorbent 26 and a tape on the inner surface of the substrate including the moisture absorbent 26. (28) is attached.

The active matrix type organic light emitting diode having the panel configuration as described above supplies power to each of the subpixels through a pad on the panel and a VDD wiring to supply power to the anode side of the organic light emitting diode.

FIG. 3 is a schematic diagram of a VDD wiring on a panel for supplying power to an active region where subpixels are concentrated using the active matrix type organic light emitting diode, and FIG. 4 is a diagram showing a VDD wiring associated with pixels in an active region. to be.

However, in FIG. 3, in the structure of the external VDD wiring 50 configured outside the active region formed on the first substrate 10 and the internal VDD wiring 60 configured inside the active region A, the inside As shown in the VDD wiring 60 in the horizontal direction in FIG. 3, it can be seen that the VDD wiring 60 is formed only in one direction for all the pixels in the active area A. FIG.

In the above wiring structure, a voltage drop problem occurs due to a resistance of the VDD wirings 50 and 60 itself due to a length problem of the VDD wiring, which is caused by the voltage supplied to the first pixel 1st and the voltage. The N th pixel causes an imbalance in the voltage supplied, causing a problem in that the image quality on the panel is not uniformly expressed.

This is because the VDD wiring itself, in which the power supply potential VDD is transferred to the Nth pixel, has limitations in the wiring width and the thickness of the wiring due to the problem of the high resolution panel layout.

The formula for calculating the resistance of the conductor

R = ρ * (L / A) (unit: Ω) (ρ: resistivity, L: length, A: cross-sectional area)

As can be inferred from, when the wiring width cannot be widened due to the problem of panel configuration, the resistance of the wiring itself increases in proportion to the length of the wiring, so in the case of the Nth pixel, the resistance of the VDD wiring itself Voltage drop will occur.

This should be solved through a realistic method of widening or increasing the thickness of the VDD wiring. This problem is caused by the narrower area of one pixel in the active area A in the panel design. Difficulties to solve are obvious.

The present invention to solve the above problems, the present invention further extends the area of the wiring in the active area for supplying power to each pixel to solve the voltage drop caused by the resistance of the wiring itself to maintain the uniformity of the image quality The main purpose is that.

In addition, since it provides a wiring structure that can further improve the internal structure of the subpixels in the active region, another object of the present invention is to propose a unique scheme that enables efficient design in the arrangement and structure of pixels.

In order to achieve the above object, the present invention is defined as a subpixel having a switching thin film transistor, a driving thin film transistor and an organic light emitting diode on a substrate, the plurality of subpixels are disposed adjacent to the active region. An active matrix type organic light emitting diode panel having a pad portion for supplying power to the active region on one side of the substrate, the external VDD wiring extending from the pad portion and wired to one outside of the active region; and; A first internal VDD interconnection in which a plurality of interconnections extend in parallel from the external VDD interconnection into the active region; A wiring structure for reducing a power supply voltage drop in an active matrix type organic light emitting display device including a plurality of second internal VDD wires connecting the adjacent first internal VDD wires is proposed.

A first external VDD wire and a second external VDD wire extending from the pad part to be wired on opposite sides of the active area by applying the wiring structure; A first internal VDD wire connected to the second external VDD wire through a plurality of wires through the active area in the first external VDD wire; A wiring structure for reducing a power supply voltage drop in an active matrix type organic light emitting display device including a plurality of second internal VDD wires connecting the adjacent first internal VDD wires is provided.

In the wiring structure, only one first internal VDD wiring is wired to each subpixel.

In the wiring structure, the second internal VDD wiring is connected to the source terminal of the driving thin film transistor.

In addition, the first internal VDD wiring and the second internal VDD wiring in each wiring structure are characterized in that their wiring forms a network structure.

Hereinafter, an embodiment of a wiring structure for reducing a power supply voltage drop in an active matrix organic light emitting display device according to the present invention will be described with reference to the accompanying drawings.

First embodiment

FIG. 5 is a view schematically illustrating a VDD wiring on a panel for explaining an embodiment of a wiring structure for reducing a power supply voltage drop in an active matrix type organic light emitting display device according to the present invention. A plurality of subpixels including a switching thin film transistor, a driving thin film transistor, and an organic light emitting diode are adjacent to each other to form a predetermined active region A. The power is supplied to the subpixel provided with the organic light emitting diode. A pad portion P is formed on the outer substrate 10 of the active region A.

The pad part P supplies an operating power supply VDD to each subpixel constituting the active area A, and has an external VDD wiring 50 formed along one side of the active area. At this time, the external VDD wiring 50 is configured outside the active region.

In the external VDD wiring 50, a plurality of first internal VDD wirings 60a for supplying power to each sub-pixel constituting the pixel portion of the active region, that is, the pixel portion, are extended. In this case, the first internal VDD wiring ( 60a) is wired only once for each subpixel and is arranged in parallel with each other.

The first internal VDD interconnections 60a are electrically connected to adjacent first internal VDD interconnections 60a, and the connection is performed by the second internal VDD interconnections 60b.

Preferably, the first internal VDD wiring 60a and the second internal VDD wiring 60b have a mesh structure.

The first internal VDD wiring 60a and the second internal VDD wiring 60b are made of a conductive metal, but preferably, the first internal VDD wiring 60a is made of the same material as the gate line (ie, the scan line). The second internal VDD wire 60b and the second internal VDD wire 60a and the second internal VDD wire 60 may be formed in the process of forming the data signal line and the scan line using the same material as the data line (that is, the data data signal line). 60b) can be formed at the same time.

As shown in FIG. 6, the second internal VDD wiring 60b is connected to the source terminal of the driving thin film transistor to supply power for driving the organic light emitting diode. At this time, there is an advantage that can be designed to share the power supply wiring with the driving thin film transistor of the adjacent sub-pixel as shown.

Second embodiment

FIG. 7 is an application diagram of a wiring structure for reducing a power supply voltage drop in an active matrix organic light emitting display device according to the present invention as described above, wherein an external power supply potential wiring formed outside the active area A is further added. The wiring structure is shown.

That is, in the pad part P, a first external VDD wiring 50a and a second external VDD wiring 50b are formed outside both sides of the active region A facing each other, and the first external VDD wiring ( The first internal VDD wiring 60a extending from 50a is connected to the second external VDD wiring 50b.

This means that the VDD power can be supplied to each subpixel more stably than the first embodiment, and the external VDD wiring is formed on any side outside the active region, so that the stable VDD power can be supplied.

Of course, the second embodiment shows two external power potential wirings, which is intended to illustrate that two or more external power potential wirings can be applied, and may constitute three or four external power potential wirings. Is natural.

As described above, the wiring structure for reducing the power supply voltage drop in the active matrix type organic light emitting display device according to the present invention exemplifies the applicability in a flat panel display device (FPD) model that aims at a high resolution and a compact model. In addition, the most significant advantage is that it is a method that can perform the stabilization of the image quality along with the structural development.

1 is a view showing a basic pixel structure of a general active matrix organic electroluminescent device

2 is a schematic cross-sectional view of a conventional active matrix organic electroluminescent device.

FIG. 3 shows a VDD wiring on a panel for supplying power to an active region in which pixel units using the active matrix type organic light emitting display device are concentrated.

4 is a diagram illustrating VDD wiring for pixels in an active region in a panel using a conventional active matrix type organic light emitting display device.

FIG. 5 is a view briefly showing a VDD wiring on a panel for explaining a first embodiment of a wiring structure for reducing power supply voltage drop in an active matrix type organic light emitting display device according to the present invention.

FIG. 6 is a diagram illustrating device arrangement and wiring in a pixel portion to which a wiring structure for reducing power supply voltage drop is applied in an active matrix type organic light emitting display device according to the present invention.

FIG. 7 is a view briefly showing a VDD wiring on a panel for explaining a second embodiment of a wiring structure for reducing power supply voltage drop in an active matrix type organic light emitting display device according to the present invention.

<Description of the symbols for the main parts of the drawings>

A: active area P: pad portion

50,50a, 50b: VDD wiring outside active area

60, 60a, 60b: VDD wiring inside active area

Claims (8)

delete delete delete delete A substrate includes a switching thin film transistor, a driving thin film transistor, an organic light emitting diode, and is defined as a subpixel, and the plurality of subpixels are disposed adjacent to each other to define an active region, and the active region is formed on one side of the substrate. In an active matrix organic light emitting diode panel having a pad unit for supplying power, First and second external VDD wires extending from the pad part and wired to opposite outer sides of the active area; A plurality of first internal VDD wires connected to the second external VDD wire through the active area in the first external VDD wire; A plurality of second internal VDD wires connecting the adjacent first internal VDD wires; Wiring structure for reducing power supply voltage drop in an active matrix organic light emitting device comprising a The method according to claim 5, The plurality of first internal VDD wirings have a wiring structure for reducing a power supply voltage drop in an active matrix organic light emitting diode, characterized in that only one wire is connected to each subpixel. The method according to claim 5, The plurality of second internal VDD wirings may be connected to the driving thin film transistors to reduce a power supply voltage drop in an active matrix organic light emitting diode. The method according to claim 5, The plurality of first internal VDD wires and the plurality of second internal VDD wires have a wiring structure of a wire structure to reduce power supply voltage drop in an active matrix type organic light emitting display device.