KR101411770B1 - Organic Light Emitting Display and Driving Method for the same - Google Patents

Organic Light Emitting Display and Driving Method for the same Download PDF

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KR101411770B1
KR101411770B1 KR1020070125049A KR20070125049A KR101411770B1 KR 101411770 B1 KR101411770 B1 KR 101411770B1 KR 1020070125049 A KR1020070125049 A KR 1020070125049A KR 20070125049 A KR20070125049 A KR 20070125049A KR 101411770 B1 KR101411770 B1 KR 101411770B1
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data signal
scan
power supply
data
signal
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KR1020070125049A
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Korean (ko)
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KR20090058323A (en
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유상호
김진형
한규일
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엘지디스플레이 주식회사
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Abstract

The present invention provides a display device comprising: a display unit in which a plurality of subpixels are arranged; A power supply for supplying a first power supply and a second power supply to the first power supply wiring and the second power supply wiring connected to the subpixel; A scan driver for supplying a scan signal to the scan line connected to the subpixel; A data driver for supplying a data signal to the data line connected to the subpixel; And a controller for supplying a first data signal having a voltage level higher than that of the first power source and a second data signal corresponding to the gray level to the data driver.
Organic light emitting display, reverse, lifetime

Description

[0001] The present invention relates to an organic light emitting display,

The present invention relates to an organic light emitting display and a driving method thereof.

An organic electroluminescent device used in an organic electroluminescent display device is a self-luminous device in which a light emitting layer is formed between two electrodes located on a substrate.

In addition, the organic light emitting display device may include a top emission type, a bottom emission type, or a dual emission type depending on a direction in which light is emitted. It is divided into a passive matrix and an active matrix depending on the driving method.

In such an organic light emitting display, when a scan signal, a data signal, a power supply, and the like are supplied to a plurality of subpixels arranged in a matrix form, the selected subpixel emits light, thereby displaying an image.

On the other hand, in transistors and organic light emitting diodes included in sub-pixels, a luminance variation occurs due to a current change problem due to a hysteresis change of a transistor and a deterioration problem of an organic light emitting diode. To improve display quality, Compensation method is necessary.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of deterioration of subpixels and to display a residual image on a display unit to improve the display quality of the organic light emitting display.

According to an aspect of the present invention, there is provided a display device comprising: a display unit in which a plurality of subpixels are arranged; A power supply for supplying a first power supply and a second power supply to the first power supply wiring and the second power supply wiring connected to the subpixel; A scan driver for supplying a scan signal to the scan line connected to the subpixel; A data driver for supplying a data signal to the data line connected to the subpixel; And a controller for supplying a first data signal having a voltage level higher than that of the first power source and a second data signal corresponding to the gray level to the data driver.

The data driver may divide and output the first data signal and the second data signal received from the control unit at a ratio of 1: 1 within a period in which the scan signal is supplied.

The data driver can output the first data signal and the second data signal with a frequency clock that is two times or more and three times or less faster than the scan signal.

The control unit includes a first memory unit for storing the Nth second data signal to be supplied to the subpixel as a digital signal, a second memory unit for storing the (N-1) th second data signal supplied to the subpixel as a digital signal, And a table for storing values obtained by digitizing voltages applied to both ends of the organic light emitting diodes included in the subpixel.

The control unit may derive the first data signal from the look-up table using the (N-1) th second data signal as an index.

The sub-pixel includes a first switching transistor having a gate connected to the scan wiring, a first end connected to the data line, and a second end connected to the first node, a gate connected to the scan line, a first end connected to the first node, An organic light emitting diode having a first electrode connected to a first power supply line and a second electrode connected to a second node, a gate connected to the first node, and a first end connected to the second node, And a capacitor connected at one end to the first node and connected at the other end to the second power supply line.

According to another aspect of the present invention, there is provided a method of driving a plasma display panel, comprising: supplying a first power source and a second power source through a first power source line and a second power source line connected to a subpixel; Supplying a scan signal through a scan line connected to a sub-pixel; And supplying a first data signal having a voltage level higher than the level of the first power source and a second data signal corresponding to the gray level through the data line connected to the sub pixel, do.

The first data signal and the second data signal can be supplied at a ratio of 1: 1 within a period in which a scan signal is supplied.

The first data signal and the second data signal can be supplied with a frequency clock that is two times or more and three times or less faster than the scan signal.

The first data signal is derived from the look-up table using the (N-1) th second data signal supplied to the sub-pixel as an index, and the look-up table is a value obtained by digitizing the voltage across the OLEDs included in the sub- .

The present invention has the effect of solving the problem of degradation of subpixels and solving the problem of a residual image appearing on the display, thereby improving the display quality of the organic electroluminescence display device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic plan view of an organic light emitting display according to an embodiment of the present invention.

As shown in FIG. 1, the organic light emitting display may include a display unit 120 on which a plurality of subpixels P are disposed. The plurality of subpixels P located on the substrate 110 are vulnerable to moisture or oxygen.

Thus, the substrate 110 and the sealing substrate 130 can be sealed by providing the sealing substrate 130 and forming the adhesive member 140 on the outer substrate 110 of the display unit 120. Meanwhile, a plurality of sub-pixels P may be driven by a driving unit 150 positioned on the substrate 110 to display an image.

The driving unit 150 can generate a scan signal, a data signal, and the like corresponding to various signals supplied from the outside, and can supply the generated signals to the display unit 120. [

The driving unit 150 may include a scan driver for supplying a scan signal to a plurality of subpixels P and a data driver for supplying a data signal to a plurality of subpixels P. [ The scan driver and the data driver may be separately disposed outside the substrate 110 or the substrate 110. The scan driver may include a scan driver and a data driver, have. Hereinafter, an example in which the scan driver and the data driver are separately located will be described.

On the other hand, the above-described subpixels may be as follows.

2A is an exemplary cross-sectional view of the subpixel shown in FIG.

As shown in FIG. 2A, a buffer layer 105 is located on a substrate 110. Buffer layer 105 is selectively using, for example, to form to protect the transistor to be formed in a subsequent process from impurities such as alkali ions leaked from the substrate 110, silicon oxide (SiO 2), silicon nitride (SiNx) .

Here, the substrate 110 may be glass, plastic or metal.

The semiconductor layer 111 is located on the buffer layer 105. The semiconductor layer 111 may include amorphous silicon or crystallized polycrystalline silicon.

In addition, the semiconductor layer 111 may include a source region and a drain region including p-type or n-type impurities, and may include a channel region other than the source region and the drain region.

A first insulating film 115, which may be a gate insulating film, is located on the semiconductor layer 111. The first insulating film 115 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof.

The gate electrode 120c may be positioned at a position corresponding to a certain region of the semiconductor layer 111 located on the first insulating film 115, that is, a channel region when impurities are implanted. The scan line 120a and the capacitor lower electrode 120b may be positioned on the same layer as the gate electrode 120c.

The gate electrode 120c is formed of a material selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper One or an alloy thereof.

The gate electrode 120c may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, Ne, Or an alloy of any one selected from the above.

Further, the gate electrode 120c may be a double layer of molybdenum / aluminum-neodymium or molybdenum / aluminum.

The scan line 120a may be formed of a material selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper One or an alloy thereof. The scan line 120a may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, And may be a multilayer composed of any one or an alloy thereof. Further, the scan line 120a may be a double layer of molybdenum / aluminum-neodymium or molybdenum / aluminum.

The second insulating film 125 to be an interlayer insulating film is located on the substrate 110 including the scan wiring 120a, the capacitor lower electrode 120b and the gate electrode 120c. The second insulating layer 125 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof.

The contact holes 130b and 130c for exposing a part of the semiconductor layer 111 are located in the second insulating film 125 and the first insulating film 115. [

Drain electrodes and source electrodes 140c and 140d electrically connected to the semiconductor layer 111 through the contact holes 130b and 130c passing through the second insulating layer 125 and the first insulating layer 115 are formed in the pixel region Located.

The drain electrode and the source electrode 140c and 140d may be formed of a single layer or multiple layers and may be formed of a single layer of molybdenum (Mo), aluminum (Al), chromium (Cr) , Gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). When the drain electrode and the source electrodes 140c and 140d are multi-layered, a triple layer of molybdenum / aluminum-neodymium, molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum may be used.

The data wiring 140a, the capacitor upper electrode 140b, and the power supply wiring 140e may be positioned on the same layer as the drain electrode and the source electrodes 140c and 140d.

The data wiring 140a and the power supply wiring 140e located in the non-pixel region may be formed of a single layer or multiple layers. When the data wiring 140a and the power wiring 140e are single layers, the data wiring 140a and the power wiring 140e may be made of molybdenum And may be made of any one selected from the group consisting of Al, Cr, Au, Ti, Ni, Ne, and Cu.

When the data wiring 140a and the power wiring 140e are multilayered, they may be formed of a triple layer of molybdenum / aluminum-neodymium, molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum.

In addition, the data wiring 140a and the power wiring 140e may be formed of a triple layer of molybdenum / aluminum-neodymium / molybdenum.

The third insulating film 145 is located on the data wiring 140a, the capacitor upper electrode 140b, the drain and source electrodes 140c and 140d and the power supply wiring 140e. The third insulating film 145 may be a planarizing film for alleviating the step difference of the lower structure and may be formed of a material such as polyimide, benzocyclobutene series resin, organic material such as acrylate, A spin coating method in which coating is followed by curing, or an inorganic material such as silicon oxide or silicon nitride can be formed by a silicate on glass (SOG) method.

Alternatively, the third insulating layer 145 may be a passivation layer, or may be a silicon nitride layer (SiNx), a silicon oxide layer (SiOx), or a multilayer thereof.

A via hole 165 is formed in the third insulating film 145 to expose either the drain or source electrode 140c or 140d and the drain and source electrodes 140c and 140c are formed on the third insulating film 145 through a via hole 165. [ And 140d, which are electrically connected to one another.

The first electrode 160 may be an anode, and may be a transparent electrode or a reflective electrode. Here, the first electrode 160 may be a transparent electrode when the structure of the organic light emitting display device is a back surface or a double-sided light emission. The first electrode 160 may be a transparent electrode such as indium tin oxide (ITO), indium zinc oxide (IZO) It can be either.

In addition, the first electrode 160 may be a reflective electrode when the structure of the organic light emitting display device is a front emission type, and aluminum (Al), silver (Ag), or the like may be formed under the layer of any one of ITO, IZO, Nickel (Ni), and in addition, a reflective layer may be included between two layers of any one of ITO, IZO, and ZnO.

A fourth insulating layer 155 is disposed on the first electrode 160 to insulate the first electrodes adjacent to the first electrode 160 and include an opening 175 for exposing a portion of the first electrode 160. The light emitting layer 170 is located on the first electrode 160 exposed by the opening 175.

The second electrode 180 is located on the light emitting layer 170. The second electrode 180 may be a cathode electrode and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof having a low work function.

Here, the second electrode 180 may be formed to have a thickness thin enough to transmit light when the organic light emitting display device has a front or both-side light emitting structure, and when the organic light emitting display device has a back light emitting structure, It can be formed thick enough to reflect light.

The above-described embodiments are based on a total of seven masks, namely, a semiconductor layer, a gate electrode (including a scan wiring and a capacitor lower electrode), contact holes, a source electrode and a drain electrode (including a data wiring, a power supply wiring, , The first electrode and the opening are formed by using a mask.

Hereinafter, an embodiment in which an organic electroluminescent display device is formed using a total of five masks is disclosed. The description of the parts overlapping with those described above in the embodiments described below will be omitted.

2B is another cross-sectional exemplary view of the subpixel shown in FIG.

2B, the buffer layer 105 is located on the substrate 110, and the semiconductor layer 111 is located on the buffer layer 105. [ The first insulating film 115 is positioned on the semiconductor layer 111 and the gate electrode 120c, the capacitor lower electrode 120b and the scan wiring 120a are positioned on the first insulating film 115. [ And the second insulating film 125 is located on the gate electrode 120c.

The first electrode 160 is positioned on the second insulating layer 125 and the contact holes 130b and 130c are exposed to expose the semiconductor layer 111. [ The first electrode 160 and the contact holes 130b and 130c may be formed at the same time.

A source electrode 140d, a drain electrode 140c, a data wiring 140a, a capacitor upper electrode 140b, and a power supply wiring 140e are located on the second insulating film 125. [ Here, a part of the drain electrode 140c may be located on the first electrode 160.

A third insulating layer 145 which may be a pixel defining layer or a bank layer is located on the substrate 110 on which the structure is formed and an opening 175 for exposing the first electrode 160 is formed on the third insulating layer 145 do. The light emitting layer 170 is located on the first electrode 160 exposed by the opening 175 and the second electrode 180 is located on the light emitting layer 170.

(Including a scan line and a capacitor lower electrode), a first electrode (including a contact hole), a source / drain electrode (including a data line, a power supply line, and a capacitor upper electrode) And the organic electroluminescent display device using a mask in the process of forming the openings has an advantage that the number of masks is reduced and the manufacturing cost is reduced and the efficiency of mass production is increased.

Such an organic light emitting display device may have various methods for realizing a color image, and an implementation method thereof will be described with reference to FIGS. 3A to 3C.

3A to 3C are views illustrating embodiments of implementing a color image in an organic light emitting display according to an exemplary embodiment of the present invention.

3A, the color image forming method shown in FIG. 3A includes a red color emitting layer 170R, a green color light emitting layer 170G, and a blue color light emitting layer 170B separately emitting red, green, and blue light, And shows an image implementation method.

As shown in FIG. 3A, red light, green light, and blue light are provided from the respective light emitting layers 170R, 170G, and 170B, respectively, so that red light / green light / blue light are mixed to display a color image.

Here, an electron transport layer (ETL), a hole transport layer (HTL), and the like may be further included at the top and bottom of each of the emission layers 170R, 170G, and 170B.

The color image realization method shown in FIG. 3B is also applicable to organic electroluminescence (EL) emission with a white light emitting layer 270W and a red color filter 290R, a green color filter 290G, a blue color filter 290B, and a white color filter 290W And shows a color image implementation method of the display device.

The white light provided from the white light emitting layer 270W is transmitted through the red color filter 290R, the green color filter 290G, the blue color filter 290B and the white color filter 290W, respectively, as shown in FIG. 3B , And red light / green light / blue light / white light are generated and mixed, respectively, so that a color image can be displayed. Here, the white color filter 290W may be constructed or removed as described above in accordance with the color combination of the white light provided in the white light emission layer 270W and the combination of the white light with the red light / green light / blue light.

In addition, although FIG. 3B shows a color implementation scheme using four subpixels according to the combination of red light / green light / blue light / white light, it is also possible to use a color implementation scheme using three subpixels according to a combination of red light / green light / have.

Here, the upper and lower portions of each white light emitting layer 270W may further include an electron transport layer (ETL), a hole transport layer (HTL), and the like, and the arrangement and structure thereof may be variously modified.

3C includes a blue light emitting layer 370B, a color changing medium 390R, a color changing medium 390G, a color changing medium 390G, medium 370B of the organic light emitting display according to an embodiment of the present invention.

The blue light provided from the blue light emitting layer 370B is converted into a red color conversion medium 390R, a green color conversion medium 390G, a blue color conversion medium color changing medium 370B, respectively, and red light / green light / blue light are generated and mixed, respectively, so that a color image can be displayed.

Here, the blue color conversion medium 370B may be constituted or removed as described above according to the combination of the color of the blue light provided by the blue light emitting layer 370B and the color of the blue light, which is obtained by combining with the red light / green light.

Here, the blue light emitting layer 370B may further include an electron transport layer (ETL), a hole transport layer (HTL), and the like on the top and bottom of the blue light emitting layer 370B.

3A to 3C, the bottom emission structure is illustrated and described. However, the present invention is not limited thereto, and various modifications can be made to the arrangement and structure of the top emission structure.

In addition, although two types of driving methods have been shown and described with respect to the color image realizing method, the present invention is not limited thereto, and various modifications are possible as needed.

Hereinafter, the structure of the organic light emitting diode according to one embodiment of the present invention will be described.

4 is a hierarchical structure diagram of an organic light emitting diode according to an embodiment of the present invention.

Referring to FIG. 4, an organic light emitting diode according to an exemplary embodiment of the present invention includes a substrate 110, a first electrode 160 disposed on the substrate 110, a first electrode 160 disposed on the first electrode 160, A second electrode 180 located on the hole injection layer 171, the hole transport layer 172, the light emitting layer 170, the electron transport layer 173, the electron injection layer 174 and the electron injection layer 174 .

First, a hole injection layer 171 is formed on the first electrode 160. The hole injection layer 171 may function to smoothly inject holes from the first electrode 160 into the light emitting layer 170 and may be formed of at least one selected from the group consisting of CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene ), PANI (polyaniline) and NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine).

The hole injection layer 171 described above can be formed by an evaporation method or a spin coating method.

The hole transport layer 172 plays a role of facilitating the transport of holes and may be formed by using NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine), TPD (N, N'- , N'-bis- (phenyl) -benzidine), s-TAD and MTDATA (4,4 ', 4 "-tris (N-3-methylphenyl-N-phenylamino) But is not limited thereto.

The hole transport layer 172 can be formed by evaporation or spin coating. The light emitting layer 170 described above may be formed of a material that emits red, green, blue, and white light, and may be formed using phosphorescent or fluorescent materials.

When the light emitting layer 170 is red, it includes a host material containing carbazole biphenyl (CBP) or mCP (1,3-bis (carbazol-9-yl) wherein the dopant comprises at least one selected from the group consisting of iridium, iridium, PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium) and PtOEP (octaethylporphyrin platinum) Or PBD: Eu (DBM) 3 (Phen) or Perylene. However, the present invention is not limited thereto.

When the light emitting layer 170 is green, it may be made of a phosphorescent material including a dopant material including a host material including CBP or mCP and containing Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium) Alternatively, it may be made of a fluorescent material including Alq3 (tris (8-hydroxyquinolino) aluminum), but is not limited thereto.

When the light emitting layer 170 is blue, it may include a phosphorescent material including a dopant material including (4,6-F2ppy) 2Irpic including a host material including CBP or mCP.

Alternatively, the fluorescent material may include any one selected from the group consisting of spiro-DPVBi, spiro-6P, distyrylbenzene (DSB), distyrylarylene (DSA), PFO polymer, and PPV polymer. It is not limited.

Here, the electron transport layer 173 serves to smooth the transport of electrons, and may be any one or more selected from the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq and SAlq But is not limited thereto.

The electron transporting layer 173 can be formed by an evaporation method or a spin coating method. The electron transport layer 173 may also prevent holes injected from the first electrode from passing through the light emitting layer to the second electrode. That is, it may serve as a hole blocking layer and may serve to efficiently combine holes and electrons in the light emitting layer.

Here, the electron injection layer 174 serves to smooth the injection of electrons, and may use Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq .

The electron injection layer 174 may be formed by vacuum evaporation of organic and inorganic materials forming the electron injection layer.

Here, the hole injection layer 171 or the electron injection layer 174 may further include an inorganic material, and the inorganic material may further include a metal compound. The metal compound may include an alkali metal or an alkaline earth metal. Metal compound including an alkali metal or alkaline earth metal LiQ, LiF, NaF, KF, RbF, CsF, FrF, BeF 2, MgF 2, CaF 2, SrF 2, BaF any one selected from the group consisting of 2 and RaF 2 or more But is not limited thereto.

That is, the inorganic material in the electron injection layer 174 facilitates hopping of electrons injected from the second electrode 180 into the light emitting layer 170, thereby balancing the holes and electrons injected into the light emitting layer, Can be improved.

The inorganic material in the hole injection layer 171 reduces the mobility of holes injected from the first electrode 160 into the light emitting layer 170 so as to balance the holes and electrons injected into the light emitting layer 170, .

Here, the present invention is not limited to FIG. 4, and at least one of the electron injection layer 174, the electron transport layer 173, the hole transport layer 172, and the hole injection layer 171 may be omitted.

Hereinafter, a schematic configuration of an organic light emitting display according to an embodiment of the present invention will be described in more detail.

5 is a schematic block diagram of an organic light emitting display according to an embodiment of the present invention.

5, the organic light emitting display includes a storage unit 130, a controller 140, a data driver 150, a scan driver 160, a power supplier 170, And a display unit 180.

The storage unit 130 stores the data signal supplied from the outside and can supply the stored data signal to the controller 140. The data signal stored in the storage unit 130 is stored as a digital signal, but is not limited thereto.

The control unit 140 divides the video data signal received from the storage unit 130 into an N-th second data signal to be supplied to the subpixel P and an (N-1) -th second data signal supplied to the subpixel P (Frame Buffer [N]) and a second memory unit (Frame Buffer [N-1]). In addition, the organic light emitting diode may include a look-up table (LUT) for storing values obtained by converting voltages applied to both ends of the organic light emitting diodes included in the subpixel.

The control unit 140 may derive the first data signal from the look-up table (LUT) using the (N-1) th second data signal as an index. The first data signal may have a voltage level higher than that of the first power source output from the power supply unit 170. [

The data driver 150 converts the Nth second data signal received from the controller 140 into an analog signal and supplies the analog signal to the subpixel P located in the display unit 180. [

The scan driver 160 may supply a scan signal through a scan line connected to the subpixel P. [

The power supply unit 170 may supply the first power and the second power through the first power line and the second power line connected to the sub-pixels. The first power source may be a voltage higher than the ground potential, and the second power source may be a ground potential or lower voltage.

The display unit 180 may include a plurality of subpixels P positioned in a matrix form. The subpixel P located in the display unit 180 can selectively emit light by a signal and a power supplied from the data driver 150, the scan driver 160, and the power supply unit 170 described above.

As described above, the controller 140 may supply the data driver 150 with a first data signal having a voltage level higher than that of the first power source and a second data signal corresponding to the gray level.

The data driver 150 receives the first data signal and the second data signal from the control unit 140 and divides the first data signal and the second data signal into a 1: To all subpixels (P) located in the subfield (180). That is, the first data signal may be supplied for 1/2 time of one scan period, and the second data signal may be supplied for the remaining 1/2 hour.

For this, the data driver 150 may output the first data signal and the second data signal at a frequency clock of two times or more and three times faster than the scan signal output from the scan driver 160, but is not limited thereto .

Hereinafter, one embodiment of the present invention will be described in more detail based on the circuit configuration and driving waveform of the subpixel P shown in FIG. 5 and FIG. See FIG. 5 together to help understand the description.

FIG. 6 is an exemplary view of a subpixel shown in FIG. 5, and FIG. 7 is a schematic waveform diagram illustrating a driving method of an organic light emitting display according to an embodiment of the present invention.

6, the subpixel P includes a first switching transistor S1 connected to a gate of the scan line SCAN, one end connected to the data line DATA and the other end connected to the first node A, ). The second switching transistor S2 may include a gate connected to the scan line SCAN, one end connected to the first node A, and the other end connected to the second node B. [ The organic light emitting diode D may include a first power supply line VDD connected to the first electrode and a second node B connected to the second electrode. The driving transistor Tl may include a gate connected to the first node A, a first end connected to the second node B, and a second end connected to the second power supply line VSS. In addition, it may include a capacitor Cst having one end connected to the first node A and the other end connected to the second power supply line VSS.

Here, the transistors S1, S2, and T1 included in the sub-pixel P may be N-type as shown, but are not limited thereto. In addition, the circuit configuration of the subpixel configured as described above is intended to illustrate an embodiment of the present invention, but is not limited thereto.

5 through 7, the subpixel P located on the display unit 180 may be supplied with a scan signal Scan through a scan line SCAN connected to the scan driver 160. Referring to FIG. The scan driver 160 may sequentially supply the scan signals Scan to all the subpixels P located in the display unit 180. [

The power supply unit 170 may be in a state of supplying the first power supply Vdd and the second power supply Vss through the first and second power supply lines VDD and VSS connected to the subpixel P. [

The first switching transistor S1 and the second switching transistor S2, which are supplied with the scan signal Scan from the scan driver 160, may be turned on. Thus, the capacitor Cst connected to the first node A can be connected to the data line DATA, and the driving transistor Tl can be a diode connection.

The data driver 150 supplies the first data signal D1 having a higher voltage level than the first power source through the data line DATA connected to the subpixel P, 2 data signal D2.

The data driver 150 receives the first data signal D1 and the second data signal D1 supplied from the control unit 140 at a frequency clock twice as fast as the scan signal Scan within the scan period Sn1, D2 can be supplied to the subpixel P. The data driver 150 may supply the first data signal D1 and the second data signal D2 to the subpixel P at a 1: 1 ratio.

In other words, the data driver 150 inverts the first data signal D1 within a period in which the first switching transistor S1 and the second switching transistor S1 are turned on by the scan signal Scan for 1/2 hour And outputs the second data signal D2 for the remaining 1/2 hour.

In order to supply the first data signal D1 and the second data signal D2 to the subpixel P at such a ratio, a frequency clock twice as fast as the scan signal Scan may be required. However, in the present invention, it is described that a clock of about two times or more and about three times or less than the scan signal Scna may be required. However, the clock signal may require four times or more depending on the performance or data amount of the driving apparatus.

Since the first data signal D1 has a voltage level higher than that of the first power source Vdd, the organic light emitting diode D receives the first data signal D1 and the first power source Vdd And a reverse voltage Reverse caused by a voltage difference between the first and second electrodes. As a result, electrons and holes trapped at the interface of the organic light emitting diode D can be recovered by the "Electrical Field ".

In this driving method, the same first data signal D1 is not supplied to both ends of the organic light emitting diode D, but may be supplied in a form suitable for each gray representation. In other words, the reverse voltage Reverse applied to the organic light emitting diode D may be a voltage corresponding to the (N-1) th second data signal by the look-up table (LUT) included in the controller 140. That is, although the first data signal D1 may be determined according to the (N-1) th second data signal, the magnitude of the voltage of the first data signal D1 may be smaller than the voltage of the scan signal Scan.

Thereafter, when the second data signal D2 is supplied to the subpixel P, the capacitor Cst supplies the second data signal D2, which has entered the first node A through the first switching transistor S1, It can be stored as voltage. In this state, when the first switching transistor S1 is turned off, the driving transistor T1 can be driven as much as the data voltage stored in the capacitor Cst. Then, the organic light emitting diode D can emit light by receiving the first power supply Vdd from the first power supply line VDD.

Hereinafter, a driving method of an organic light emitting display according to an embodiment of the present invention will be schematically described. 5 to 7 are also referred to for facilitating understanding of the explanation.

First, a step of supplying a first power source Vdd and a second power source Vss to the first power source line VDD and the second power source line VSS connected to the subpixel P is performed.

The power supply unit 170 supplies the first power Vdd and the second power Vss through the first power supply line VDD and the second power supply line VSS connected to all the subpixels P located in the display unit 180. [ ).

Next, a step of supplying a scan signal (Scan) through a scan line (SCAN) connected to the subpixel (P) is performed.

The scan driver 160 may sequentially supply the scan signals Scan to the scan lines SCAN connected to all the subpixels P located on the display unit 180. [

At this time, the first and second switching transistors S 1 and S 2 supplied with the scan signal Scan may be turned on, and the driving transistor T 1 may be diode-connected by the second switching transistor S 2.

Next, the first data signal D1 having a voltage level higher than the level of the first power source Vdd and the second data signal D2 corresponding to the gray level are supplied through the data line DATA connected to the subpixel P Supply step.

The data driver 150 applies the first data signal D1 and the second data signal D1 to the subpixel P in which the first and second switching transistors S1 and S2 among the subpixels P located in the display unit 180 are turned on, And can supply the data signal D2.

At this time, both ends of the organic light emitting diode D connected between the first power supply line VDD and the second node B of the subpixel P are connected to the first power supply Vdd and the first data signal D1 It is possible to have an effect that a reverse voltage (Reverse) is applied by the level difference.

Here, the first data signal D1 and the second data signal D2 may be supplied in a 1: 1 ratio within the scan period Sn1 to which the scan signal Scan is supplied. For this, the first data signal D1 and the second data signal D2 can be supplied with a frequency clock that is two times or more and three times or less faster than the scan signal Scan.

The first data signal D1 may be derived from a look-up table (LUT) included in the controller 140 using the (N-1) th second data signal supplied to the subpixel P as an index. The look-up table (LUT) may have a value obtained by digitizing voltages applied to both ends of the organic light emitting diode D included in the subpixel P, as described above.

Therefore, the same first data signal D1 is not supplied to both ends of the organic light emitting diode D, but may be supplied in a form suitable for each gray representation. In other words, the reverse voltage Reverse applied to the organic light emitting diode D may be a voltage corresponding to the (N-1) th second data signal by the look-up table (LUT) included in the controller 140. That is, the first data signal D1 may be determined according to the (N-1) th second data signal. However, the magnitude of the voltage of the first data signal D1 may be smaller than the magnitude of the voltage of the scan signal (Scan).

Although not shown in the figure, when the second data signal D2 is supplied to the subpixel P, the capacitor Cst is supplied with the second data D2 inputted to the first node A through the first switching transistor S1 And store the signal D2 as a data voltage. In this state, when the first switching transistor S1 is turned off, the driving transistor T1 can be driven as much as the data voltage stored in the capacitor Cst. Then, the organic light emitting diode D can emit light by receiving the first power supply Vdd from the first power supply line VDD.

The present invention can improve the lifetime of the device by supplying a reverse voltage to both ends of the organic light emitting diode during the first half of the scan period. In addition, since the operation region of the driving transistor operates from a logic high level to a logic low level for the remaining 1/2 hour of the scan period, only one direction is used in terms of the hysteresis of the transistor, so that afterimage improvement effect can be obtained. In addition, when the organic light emitting display device is driven, image quality degradation problems such as a change in white balance caused by the lifetime difference of each sub pixel (e.g., R, G, B) can be improved.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and equivalents thereof should be construed as being included within the scope of the present invention.

1 is a schematic plan view of an organic light emitting display according to an embodiment of the present invention.

FIG. 2A is an exemplary cross-sectional view of the subpixel shown in FIG. 1; FIG.

FIG. 2B is another cross-sectional exemplary view of the subpixel shown in FIG. 1; FIG.

3A to 3C illustrate embodiments of implementing a color image in an organic light emitting display according to an embodiment of the present invention.

4 is a hierarchical structure view of an organic light emitting diode according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display.

FIG. 6 is an exemplary view of the subpixel shown in FIG. 5; FIG.

FIG. 7 is a schematic waveform diagram for explaining a driving method of an organic light emitting display according to an embodiment of the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

130: storage unit 140:

150: Data driver 160:

170: power supply unit 180: display unit

Claims (10)

  1. A display unit in which a plurality of subpixels are arranged;
    A power supply for supplying a first power supply and a second power supply to a first power supply line and a second power supply line connected to the subpixel;
    A scan driver for supplying a scan signal to a scan line connected to the sub-pixel;
    A data driver for supplying a data signal to a data line connected to the sub-pixel; And
    And a controller for supplying a first data signal having a voltage level higher than a level of the first power source and a second data signal corresponding to a gray level to the data driver.
  2. The method according to claim 1,
    The data driver may include:
    And divides and outputs the first data signal and the second data signal received from the control unit in a ratio of 1: 1 within a period in which the scan signal is supplied.
  3. The method according to claim 1,
    The data driver may include:
    And outputs the first data signal and the second data signal with a frequency clock that is two times or more and three times or less faster than the scan signal.
  4. The method according to claim 1,
    Wherein,
    A second memory unit for storing the N-th second data signal to be supplied to the sub-pixel as a digital signal, and a second memory unit for storing the (N-1) And a table for storing values obtained by digitizing voltages applied to both ends of the organic light emitting diodes included in the subpixel.
  5. 5. The method of claim 4,
    Wherein,
    And derives the first data signal from the look-up table using the (N-1) th second data signal as an index.
  6. The method according to claim 1,
    The sub-
    A first switching transistor having a gate connected to the scan wiring, one end connected to the data wiring and the other end connected to a first node, a gate connected to the scan wiring, a first end connected to the first node, An organic light emitting diode having a first electrode connected to the first power supply line and a second electrode connected to the second node, a gate connected to the first node, and a second node connected to the second node, And a capacitor having one end connected to the first node and the other end connected to the second power supply line.
  7. Supplying a first power supply and a second power supply through a first power supply line and a second power supply line connected to a subpixel;
    Supplying a scan signal through a scan line connected to the sub-pixel; And
    Supplying a first data signal having a voltage level higher than a level of the first power source and a second data signal corresponding to a gray level through a data line connected to the sub-pixel,
    Wherein the step of supplying the scan signal and the step of supplying the first data signal and the second data signal are simultaneously performed.
  8. 8. The method of claim 7,
    Wherein the first data signal and the second data signal,
    And supplies the scan signal in a 1: 1 ratio within a period in which the scan signal is supplied.
  9. 8. The method of claim 7,
    Wherein the first data signal and the second data signal,
    And supplying the scan signal with a frequency clock that is two times or more and three times or less faster than the scan signal.
  10. 8. The method of claim 7,
    Wherein the first data signal comprises:
    An N-1 < th > second data signal supplied to the subpixel is derived from an index table using an index,
    Wherein the look-up table is a value obtained by digitizing voltages applied to both ends of the organic light emitting diode included in the sub-pixel.
KR1020070125049A 2007-12-04 2007-12-04 Organic Light Emitting Display and Driving Method for the same KR101411770B1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20060092163A (en) * 2003-08-29 2006-08-22 세이코 엡슨 가부시키가이샤 Electric circuit, method of driving the same, electronic device, electro-optical device, and electronic apparatus
KR20070003575A (en) * 2005-06-30 2007-01-05 엘지.필립스 엘시디 주식회사 Light emitting device
JP2007279701A (en) 2006-03-13 2007-10-25 Canon Inc Pixel circuit and image display apparatus having pixel circuit
KR20070105083A (en) * 2006-04-25 2007-10-30 엘지전자 주식회사 Method for driving organic electro luminescence display device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20060092163A (en) * 2003-08-29 2006-08-22 세이코 엡슨 가부시키가이샤 Electric circuit, method of driving the same, electronic device, electro-optical device, and electronic apparatus
KR20070003575A (en) * 2005-06-30 2007-01-05 엘지.필립스 엘시디 주식회사 Light emitting device
JP2007279701A (en) 2006-03-13 2007-10-25 Canon Inc Pixel circuit and image display apparatus having pixel circuit
KR20070105083A (en) * 2006-04-25 2007-10-30 엘지전자 주식회사 Method for driving organic electro luminescence display device

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