KR20090065740A - Organic light emitting display and method of driving the same - Google Patents

Abstract

An organic electroluminescent display device and a driving method are provided, which can improve the brightness inhomogeneity and display quality. The display unit(DP) comprises a plurality of sub pixels. The scan driver(SDR) supplies scan signal to the display unit. The data driver(DDR) converts the image data signal supplied from outside into the analog data signal and digital data signal according to gradation. The data driver supplies the analog data signal and digital data signal to the display unit.

Description

Organic Light Emitting Display and Method of Driving the Same

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

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

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

In the organic light emitting display device, when a scan signal, a data signal, and a power are supplied to a plurality of subpixels arranged in a matrix form, the selected subpixels emit light to display an image.

On the other hand, the organic light emitting display device has a luminance nonuniformity because the driving transistor is very sensitive to electrical characteristics, and a compensation method using voltage or current has been proposed.

In the voltage compensation method, a program time of a certain time is required to compensate for a threshold voltage of a driving transistor, and a large number of transistors and a complicated control signal have to be used. In addition, the current compensation method is excellent in terms of image quality compensating current mobility and threshold voltage, but the parasitic capacitance component of the data line is very large, so that the compensating ability in the low gray scale region is inferior.

Therefore, the conventional organic light emitting display device has to be provided with a compensation method that can solve the problem of luminance unevenness and improve the display quality.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems of the background art is to provide an improved compensation method capable of solving the luminance non-uniformity problem shown in an organic light emitting display device and improving display quality.

According to the above-mentioned problem solving means, the present invention provides a display unit including a plurality of sub-pixels; A scan driver supplying a scan signal to the display unit; And a data driver converting the image data signal supplied from the outside into an analog data signal and a digital data signal according to the gray level, and supplying a mixture of the analog data signal and the digital data signal to the display unit.

The data driver determines the gray level of the video data signal as the upper bit group and the lower bit group. When the gray level of the video data signal is the upper bit group, the data driver converts the video data signal into an analog data signal, and the gray level of the video data signal is the lower bit group. In this case, the image data signal may be converted into a digital data signal.

The data driver may determine the lower 3 to 4 bits of the gray level of the image data signal as the lower bit group and the remaining bits as the upper bit group.

The data driver may include: a determiner configured to determine whether a gray level of the image data signal is an upper bit group or a lower bit group; An analog driver converting an image data signal corresponding to the upper bit group received from the determination unit into an analog data signal and outputting the analog data signal; And a digital driver converting the image data signal corresponding to the lower bit group received from the determination unit into a digital data signal and outputting the digital data signal.

The data driver includes a first switch positioned between the output terminals of the analog driver and a second switch positioned between the output terminals of the digital driver. The first switch is configured to selectively supply analog data signals and digital data signals to the display unit. Switching operation can be performed.

The digital driver may output a control signal through the second switch so that the subpixels are selectively supplied with the analog data signal and the digital data signal and drive the analog pixel in the analog mode and the digital mode.

The subpixel may include a first switching transistor having a gate connected to the first scan line and one end connected to the data line and the other end connected to the first node, a gate connected to the second scan line and one end connected to the control line. A second switching transistor having the other end connected to the second node, a gate connected to the second node, one end connected to the first node, and a third switching transistor connected to the other end of the third node, and a gate connected to the second scan wiring; A fourth switching transistor having one end connected to the third node and the other end connected to the fourth node, a fifth switching transistor having a gate connected to the first scan wiring and one end connected to the fourth node, and a gate connected to the third node And one end connected to the first power line and the other end connected to the fourth node, a first electrode connected to the other end of the fifth switching transistor, and a second electrode connected to the second power line. It may include an organic light emitting diode, a first capacitor having one end connected to the second node and the other end connected to the first power line, and a second capacitor having one end connected to the first power line and the other end connected to the third node. .

The subpixel may operate in an analog mode when a logic high signal is supplied from the control line and operate in a digital mode when a logic low signal is supplied from the control line.

The gray level corresponding to the driving current of the driving transistor may be expressed in the subpixel when operating in the analog mode, and the gray level corresponding to the emission time of the organic light emitting diode may be expressed in the subpixel when operating in the digital mode.

The first to fourth switching transistors may be P-type transistors, and the fifth switching transistor may be N-type transistors.

Transistors included in the sub pixel may be a poly transistor.

On the other hand, the present invention is a step of determining whether the gray level of the image data signal supplied from the outside is an upper bit group or a lower bit group; Converting the video data signal corresponding to the upper bit group into an analog data signal and converting the video data signal corresponding to the lower bit group into a digital data signal; And a supplying step of supplying a mixture of analog data signals and digital data signals to the subpixels.

In the determining step, if the gray level of the image data signal is the lower 3 to 4 bits, it may be determined as the lower bit group, and the remaining bits may be determined as the upper bit group.

After the converting step, the method may further include a setting step of supplying a control signal to the subpixel such that the subpixel selectively supplied with the analog data signal and the digital data signal is driven in the analog mode and the digital mode.

The gray scale corresponding to the driving current of the driving transistor included in the subpixel is expressed in the subpixel when operating in the analog mode, and the subpixel corresponds to the emission time of the organic light emitting diode included in the subpixel in the digital mode. Gradation can be expressed.

The present invention has the effect of providing an improved compensation method capable of solving the luminance non-uniformity problem shown in the organic light emitting display device and improving the display quality. In addition, the present invention has the effect of being able to write analog data signals and digital data signals in a hybrid form. In addition, the present invention has an effect of providing ease in implementing a large area organic light emitting display device by separately supplying gamma of low gray level and gamma of high gray level.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

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

As shown in FIG. 1, the organic light emitting display device may include a substrate 110. In addition, the display 110 may include a plurality of sub-pixels P on the substrate 110. In addition, the display panel DP may include an adhesive member SL positioned outside the display unit DP. In addition, it may include a sealing substrate 190 for sealing the substrate 110 by the adhesive member (SL). In addition, the display unit DP may include a driving unit DR for supplying a driving signal or the like. In addition, it may include a pad unit (PD) for transmitting a driving signal supplied from the outside to the driving unit (DR).

Here, the substrate 110 may be selected to be a material for forming an element having excellent mechanical strength or dimensional stability. As the material of the substrate 110, a glass plate, a metal plate, a ceramic plate or a plastic plate (polycarbonate resin, acrylic resin, vinyl chloride resin, polyethylene terephthalate resin, polyimide resin, polyester resin, epoxy resin, silicone resin, fluorine) Resin, etc.), but is not limited thereto.

Here, the adhesive member SL may include, but is not limited to, a front sealant, an edge sealant, and a frit.

Here, the sealing substrate 190 may be selected as a transparent material when the organic light emitting display device is an upper emission type, may be selected as a transparent or opaque material when the lower emission type, and may be selected as a transparent material when a double emission type. Can be.

The subpixel P may emit three colors such as red, green, and blue to implement various images, but is not limited thereto. The light emission concept of the subpixel will be described in more detail as follows.

2 is a diagram illustrating an image implementation of a subpixel included in an organic light emitting display device.

As shown in FIG. 2, in the organic light emitting display device, subpixels having a red light emitting layer 130R, a green light emitting layer 130G, and a blue light emitting layer 130B respectively emitting red, green, and blue light are positioned in the display unit. can do.

One subpixel may include a transistor, a capacitor, and an organic light emitting diode, and the organic light emitting diode included in one subpixel may include one or more light emitting layers.

Herein, when the organic light emitting diode is positioned on the substrate 110 without the transistor and the capacitor, the organic light emitting diode included in each sub pixel is positioned on the first electrode 120 and the first electrode 120. The light emitting layers 130R, 130G, and 130B, and the second electrode 140 positioned on the light emitting layers 130R, 130G, and 130B may be included. The first electrode 120 and the second electrode 140 may be selected as an anode or a cathode, respectively, according to the formation method of the organic light emitting diode.

The light emitting layers 130R, 130G, and 130B of the organic light emitting diode may include at least one of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. A more detailed description of these hierarchies is as follows.

3 is a hierarchical structure diagram of the organic light emitting diode shown in FIG. 2.

As shown in FIG. 3, the organic light emitting diode includes a hole injection layer 131, a hole transport layer 132, a light emitting layer 133, an electron transport layer 134, and an electron injection layer disposed on the first electrode 120. 135 and the second electrode 140 positioned on the electron injection layer 135.

First, the hole injection layer 131 may be positioned on the first electrode 120. The hole injection layer 131 may play a role of smoothly injecting holes from the first electrode 120 to the light emitting layer 133, CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene), PANI (polyaniline) and NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine) may be made of any one or more selected from the group consisting of, but is not limited thereto.

The hole injection layer 131 described above may be formed using an evaporation method or a spin coating method.

The hole transport layer 132 serves to facilitate the transport of holes, NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine), TPD (N, N'-bis- (3-methylphenyl) -N , N'-bis- (phenyl) -benzidine), s-TAD and MTDATA (4,4 ', 4 "-Tris (N-3-methylphenyl-N-phenyl-amino) -triphenylamine) It may be made of one or more, but is not limited thereto.

The hole transport layer 132 may be formed using an evaporation method or a spin coating method. The light emitting layer 133 described above may be formed of a material emitting red, green, blue, and white light, and may be formed using phosphorescent or fluorescent materials.

When the light emitting layer 133 is red, it includes a host material including CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl), and PIQIr (acac) (bis (1-phenylisoquinoline) acetylacetonate Phosphorescent light containing a dopant containing any one or more selected from the group consisting of iridium), PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium) and PtOEP (octaethylporphyrin platinum) It may be made of a material, alternatively may be made of a fluorescent material including PBD: Eu (DBM) 3 (Phen) or perylene, but is not limited thereto.

When the light emitting layer 133 is green, it may include a host material including CBP or mCP, and may be made of a phosphor including a dopant material including Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium). Alternatively, the composition may be made of a fluorescent material including Alq3 (tris (8-hydroxyquinolino) aluminum), but is not limited thereto.

When the emission layer 133 is blue, the light emitting layer 133 may include a host material including CBP or mCP, and may be formed of a phosphor including a dopant material including (4,6-F2ppy) 2Irpic.

Alternatively, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distilbenzene (DSB), distriarylene (DSA), PFO-based polymer and PPV-based polymer, but It is not limited.

Here, the electron transport layer 134 serves to facilitate the transport of electrons, at least one selected from the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq and SAlq. It may be made but not limited thereto.

The electron transport layer 134 may be formed using an evaporation method or a spin coating method, but is not limited thereto. The electron transport layer 134 may also prevent the holes injected from the first electrode 120 from passing through the emission layer 133 to the second electrode 140. That is, the hole blocking layer may serve to efficiently combine holes and electrons in the emission layer 133.

Here, the electron injection layer 135 serves to facilitate the injection of electrons, but may be used Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq, but is not limited thereto. .

The electron injection layer 135 may form an organic material and an inorganic material constituting the electron injection layer by a vacuum deposition method, but is not limited thereto.

The hole injection layer 131 or the electron injection layer 135 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 it is not limited thereto.

That is, the inorganic material in the electron injection layer 135 facilitates hopping of electrons injected from the second electrode 140 into the light emitting layer 133, thereby balancing the holes and electrons injected into the light emitting layer 133. The luminous efficiency can be improved.

In addition, the inorganic material in the hole injection layer 131 reduces the mobility of holes injected into the light emitting layer 133 from the first electrode 120, thereby improving the luminous efficiency by balancing the holes and electrons injected into the light emitting layer 133. Can be improved.

Meanwhile, the present invention is not limited to FIG. 3, and at least one of the electron injection layer 135, the electron transport layer 134, the hole transport layer 132, and the hole injection layer 131 may be omitted.

Referring back to FIG. 1, the plurality of sub pixels P included in the display unit DP may be driven by the driver DR to represent an image. The driving unit DR may receive various driving signals required for driving from the outside through the pad unit PD positioned on the substrate 110. Accordingly, the driver DR may generate a scan signal and a data signal in response to various drive signals supplied from the outside, and supply the generated scan signal and the data signal to the display unit DP.

The driving unit DR may include a scan driver supplying a scan signal to the plurality of subpixels P and a data driver supplying a data signal to the plurality of subpixels P. Here, the driver DR is only schematically illustrated as an example in which the scan driver and the data driver are formed on one chip, and the scan driver and the data driver may be determined and positioned outside the substrate 110 or the substrate 110. have.

Hereinafter, a scan driver, a data driver, and a display unit will be schematically shown, and an organic light emitting display device according to an embodiment of the present invention will be described in more detail.

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

As shown in FIG. 4, the organic light emitting display device according to the exemplary embodiment of the present invention may include a display unit DP including a plurality of sub pixels P. Referring to FIG. In addition, the display driver DP may include a scan driver SDR for supplying a scan signal to the display unit DP. In addition, the data driver may convert an image data signal supplied from the outside into an analog data signal and a digital data signal according to the gray level, and supply the analog data signal and the digital data signal to the display unit DP.

The data driver DDR determines the gray level of the video data signal as an upper bit group and a lower bit group. When the gray level of the video data signal is an upper bit group, the data driver DDR converts the video data signal into an analog data signal, In the lower bit group, the image data signal may be converted into a digital data signal.

As described above, the data driver DDR may include a determiner COMP, an analog driver DDR1, and a digital driver DDR2.

When the image data signal is supplied to the data driver DDR, the determination unit COMP may determine whether the gray level of the supplied image data signal is an upper bit group or a lower bit group. In addition, the analog driver DDR1 may convert an image data signal corresponding to a higher bit group received from the determiner COMP into an analog data signal and output the analog data signal. In addition, the digital driver DDR2 may convert the image data signal corresponding to the lower bit group received from the determination unit COMP into a digital data signal and output the converted digital data signal.

The data driver DDR may determine the lower 3 to 4 bits of the gray level of the image data signal as the lower bit group and the remaining bits as the upper bit group. Alternatively, when representing an image with 8 bits, the range of the lower bit group may be determined based on the data load condition and the frame frequency supplied to the display unit DP and set to digital driving.

That is, the criterion for determining the upper bits and the lower bits may vary according to the number of the plurality of subframes constituting the image data signal and the data load condition. In the present invention, however, the number of subframes constituting the video data signal is four, i.e., 8 bits.

Here, the image data signal supplied from the outside to the data driver DDR is a digital image data signal, and the digital image data signal is composed of one frame including a plurality of subframes.

The data driver DDR may include a first switch S1 positioned between the output terminals of the analog driver DDR1 and a second switch S2 positioned between the output terminals of the digital driver DDR2. .

The first switch S1 included in the data driver DDR may perform a switching operation so that an analog data signal and a digital data signal are selectively supplied to the display unit DP. In addition, the digital driver DDR may output a control signal through the second switch S2 such that the subpixel P is selectively supplied with the analog data signal and the digital data signal, and is driven in the analog mode and the digital mode.

The control signal output from the second switch S2 included in the data driver DDR may be a logic high or logic low signal as a digital signal.

As such, when a control signal corresponding to a logic high or logic low signal is output, the supplied sub-pixel P may operate in an analog mode and a digital mode by a circuit configured therein.

Hereinafter, a circuit configuration of a subpixel configured to vary the gray scale representation by receiving driving signals from the data driver DDR and the scan driver SDR will be described in more detail. However, the circuit configuration of FIG. 5 is only a circuit configuration of a subpixel for explaining an example of the embodiment, and the present invention is not limited thereto.

5 is an exemplary circuit configuration of a subpixel according to an embodiment of the present invention.

As shown in FIG. 5, the subpixel includes a first gate connected to the first scan line SCAN1 [m], one end connected to the data line IDATA [n], and the other end connected to the first node A. Referring to FIG. One switching transistor SW1 may be included. In addition, a second switching transistor SW2 having a gate connected to the second scan line SCAN2 [m], one end connected to the control line DA [n], and the other end connected to the second node B may include a second switching transistor SW2. Can be. In addition, a third switching transistor SW3 may include a gate connected to the second node B, one end connected to the first node A, and the other end connected to the third node C. In addition, a fourth switching transistor SW4 having a gate connected to the second scan line SCAN2 [m], one end connected to the third node C, and the other end connected to the fourth node D may be included. . In addition, a fifth switching transistor SW5 having a gate connected to the first scan line SCAN1 [m] and one end connected to the fourth node D may be included. In addition, the driving circuit TR1 may include a gate connected to the third node C, one end connected to the first power line VDD, and the other end connected to the fourth node D. The organic light emitting diode OLED may further include an organic light emitting diode OLED having a first electrode connected to the other end of the fifth switching transistor SW5 and a second electrode connected to the second power line VSS. In addition, one end may be connected to the second node B and the first capacitor C1 may be connected to the other end of the first power line VDD. In addition, a second capacitor C2 having one end connected to the first power line VDD and the other end connected to the third node C may be included.

Here, the first to fourth switching transistors SW1, SW2, SW3, and SW4 may be P-type transistors, and the fifth switching transistor SW5 may be N-type transistors, but is not limited thereto. In addition, the transistors SW1, SW2, SW3, SW4, SW5, and TR1 included in the subpixel P may be poly transistors, but are not limited thereto.

Here, according to the sub pixel circuit configuration described above, the organic light emitting display device can be driven by the following driving waveform.

6 is a view illustrating a driving waveform for explaining a driving method according to an embodiment of the present invention.

As illustrated in FIG. 6, the subpixel may receive the first scan signal scan1 [m] output from the scan driver through the first scan line SCAN1 [m], and the second scan signal scan2. [m]) may be supplied through the second scan line SCAN2 [m]. In addition, the sub pixel may receive analog and digital data signals idata [n] output from the data driver through the data line iDATA [n]. In addition, the subpixel may receive the control signal da [n] output from the data driver through the control line DA [n].

Here, when the first scan signal scan1 [m] corresponding to the logic row is supplied to the subpixel through the first scan line SCAN1 [m], the first switching transistor SW1 may be turned on, and the fifth The switching transistor SW5 may be turned off.

Here, when the second scan signal scan2 [m] corresponding to the logic row is supplied to the subpixel through the second scan line SCAN2 [m], the second switching transistor SW2 and the fourth switching transistor SW4. Can be turned on. In this case, the amount of charge in the first capacitor C1 may vary depending on whether the control signal da [n] supplied through the control wiring DA [n] is logic high or logic low, and the subpixel may have a first value. It may be selected as an analog mode or a digital mode according to the charge amount of the capacitor C1. That is, when the logic high signal is supplied from the control wiring DA [n], the logic mode may be operated in the analog mode, and when the logic low signal is supplied from the control wiring DA [n], the logic mode may be operated in the digital mode. .

Subsequently, when a data signal corresponding to each gray level is supplied through the data line IDATA [n], a data voltage corresponding to the gray level may be stored in the second capacitor C2 included in the subpixel, and the organic light emitting diode OLED ) Can emit light.

Here, in the analog mode, the sub-pixel may be expressed by the driving current of the driving transistor TR1, and in the digital mode, the sub-pixel is the gray level corresponding to the emission time of the organic light emitting diode OLED. Can be expressed.

The driving method of the organic light emitting display device including the configuration as described above may be as follows.

7 is a driving flowchart for explaining an embodiment of the present invention.

The driving method according to an embodiment of the present invention may include a determination step S102, a conversion step S104, and a supply step S108.

The determination step S102 is a step of determining whether the gray level of the image data signal supplied from the outside is an upper bit group or a lower bit group.

To this end, in the determining step S102, it is possible to determine whether the gray level of the image data signal supplied from the outside is an upper bit group or a lower bit group using the determination unit COMP included in the data driver DDR.

Here, the data driver DDR may determine the lower 3 to 4 bits of the gray level of the image data signal as the lower bit group and the remaining bits as the upper bit group. However, the criterion for determining the upper bits and the lower bits may vary according to the number of subframes constituting the image data signal. In the present invention, however, the number of subframes constituting the video data signal is four, i.e., 8 bits.

Here, the image data signal supplied from the outside to the data driver DDR is a digital image data signal, and the digital image data signal is composed of one frame including a plurality of subframes.

The converting step S104 is a step of converting an image data signal corresponding to an upper bit group into an analog data signal and converting an image data signal corresponding to a lower bit group into a digital data signal.

To this end, in the converting step S104, the image data signal corresponding to the upper bit group received from the determination unit COMP may be converted into an analog data signal using the analog driver DDR1. In addition, the digital driving unit DDR2 may convert the image data signal corresponding to the lower bit group received from the determination unit COMP into a digital data signal and output the converted digital data signal.

On the other hand, after the converting step (S104), it may further include a setting step (S106) of supplying a control signal to the sub-pixels to drive the sub-pixels selectively supplied with the analog data signal and the digital data signal in the analog mode and the digital mode. have.

To this end, in the conversion step S104, the first switch S1 included in the data driver DDR may be used to selectively supply the analog data signal and the digital data signal to the display unit DP.

The second switch S2 may be used to selectively receive the analog data signal and the digital data signal and to drive the analog pixel signal in the analog mode and the digital mode. In this case, the control signal output from the second switch S2 included in the data driver DDR may be a logic high or logic low signal as a digital signal. As such, when a control signal corresponding to a logic high or logic low signal is output, the supplied sub-pixel P may operate in an analog mode and a digital mode by a circuit configured therein.

The supply step S108 is a step of supplying an analog data signal and a digital data signal to the subpixel.

To this end, in the supply step S108, the first scan signal and the second scan signal may be supplied to the subpixel using the scan driver SDR, and the analog data signal and the digital data signal may be supplied using the data driver DDR. .

Hereinafter, a description will be given of a subpixel arranged in a 3 * 3 form, one frame data signal, and a driving waveform. However, in describing the driving method according to an exemplary embodiment of the present invention, the above-described FIGS. 4 and 5 will be referred to together to increase understanding.

8 is a layout view of a subpixel for explaining a driving method according to an exemplary embodiment of the present invention.

As illustrated in FIG. 8, in order to describe the driving method according to an exemplary embodiment of the present invention, the subpixels are arranged in a 3 * 3 form as an example.

Here, (1) of the figure shows a high gray level and a low gray level that the data driver DDR will supply to the 3 * 3 subpixels positioned on the display portion DP. AD) is supplied and low gradation indicates that the digital data signal DD is supplied.

As described above, the data driver DDR may use the determiner COMP, the analog driver DDR1, and the digital driver DDR2 as described above.

Accordingly, the high gray HG corresponding to the upper bit is converted into the analog data signal AD and supplied to the corresponding subpixel, and the low gray LG corresponding to the lower bit is converted into the digital data signal DD. It may be supplied to the corresponding subpixel.

Meanwhile, according to the assumptions described above, one frame may be supplied to the subpixel in the following form.

9 is a schematic diagram of a frame data signal for explaining a driving method according to an embodiment of the present invention. However, for better understanding of the description, it is assumed that one frame data signal 1 frame supplied to the subpixel P is composed of four subframes SF1, SF2, SF3, SF4, that is, 8 bits. Continue.

As illustrated in FIG. 9, the data driver DDR may supply a first sub frame SF1 corresponding to an upper bit as an analog data signal to program the subpixel. In addition, an operation mode of the subpixel may be set to an analog or digital mode by using a control signal output from the data driver DDR. In this case, the section in which the first sub frame SF1 is supplied may be a section in which analog program & mode setting can be performed.

Here, after the mode is set in the section in which the first sub frame SF1 is supplied, the second sub frame SF2, the third sub frame SF3, and the fourth sub frame SF4 belonging to the lower bits are Programming can be done with digital data signals.

3x3 subpixels supplied with the first to fourth subframes SF1 to SF4 may perform operations corresponding to the supplied data signals. Accordingly, the first sub frame SF1 may express a desired high gray level according to the driving current of the driving transistor TR1 driving corresponding to the data voltage stored in the second capacitor C2. In addition, the second to fourth sub-frames SF2 to SF4 except for the first sub-frame SF1 may adjust the light emission time according to the first scan signal scan1 [n] to express a desired low gray scale.

Here, it may be assumed that "I _Gray " in the figure is a state in which an analog or digital data signal is held, and "1" in the figure may be assumed to be a gradation representation state corresponding to the analog data signal, and "0" in the figure. Can be assumed to be a gradation representation state corresponding to the digital data signal.

The present invention provides an organic light emitting display device having a hybrid compensation method using an analog current compensation method and a digital voltage driving method. Using the hybrid compensation method as described above enables improved image quality compared to the conventional compensation method. In addition, since the lower 3 to 4 bits can be removed from the analog driver, that is, the output channel of the current digital to analog converter (DAC) included in the data driver, it is possible to solve the problem of current offset, as well as the cost of the chip. It can lower the and can provide a simple driving method. In addition, the present invention can provide ease of implementation of a large-area organic light emitting display device by separately supplying gamma of low gray level and gamma of high gray level.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

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

2 is a diagram illustrating an image implementation of a subpixel included in an organic light emitting display device.

3 is a hierarchical structure diagram of the organic light emitting diode shown in FIG. 2.

4 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention;

5 is an exemplary circuit configuration of a subpixel according to an embodiment of the present invention.

6 is a view illustrating a driving waveform for explaining a driving method according to an embodiment of the present invention.

7 is a driving flowchart for explaining an embodiment of the present invention.

8 is a layout view of a subpixel for explaining a driving method according to an exemplary embodiment of the present invention.

9 is a schematic diagram of a frame data signal for explaining a driving method according to an embodiment of the present invention;

<Explanation of symbols on main parts of the drawings>

DP: display unit P: subpixel

DDR: data driver SDR: scan driver

DDR1: Analog Drive DDR2: Digital Drive

COMP: judgment

Claims (15)

A display unit including a plurality of sub pixels; A scan driver supplying a scan signal to the display unit; And And a data driver converting the image data signal supplied from the outside into an analog data signal and a digital data signal according to the gray level, and supplying the analog data signal and the digital data signal to the display unit. The method of claim 1, The data driver, The gray level of the video data signal is determined as an upper bit group and a lower bit group. When the gray level of the video data signal is the upper bit group, the video data signal is converted into the analog data signal, and the gray level of the video data signal is An organic light emitting display device for converting the image data signal into the digital data signal in a lower bit group. The method of claim 2, The data driver, And determining lower 3 to 4 bits of the gray level of the image data signal as the lower bit group and determining the remaining bits as the upper bit group. The method of claim 1, The data driver, A determination unit which determines whether the gray level of the image data signal is an upper bit group or a lower bit group; An analog driver converting the image data signal corresponding to the upper bit group received from the determination unit into the analog data signal and outputting the analog data signal; And And a digital driver converting the image data signal corresponding to the lower bit group received from the determination unit into the digital data signal and outputting the digital data signal. The method of claim 4, wherein The data driver, A first switch located between the output terminals of the analog driver, and a second switch located between the output terminals of the digital driver; And the first switch is switched so that the analog data signal and the digital data signal are selectively supplied to the display unit. The method of claim 5, The digital driver, And a sub-pixel to selectively receive the analog data signal and the digital data signal and to output a control signal through the second switch to drive the analog data signal and the digital data signal. The method of claim 1, The sub pixel is, A first switching transistor having a gate connected to the first scan wire and one end connected to the data wire and the other end connected to the first node, a gate connected to the second scan wire and one end connected to the control wire and the other end connected to the second node. The connected second switching transistor, a third switching transistor having a gate connected to the second node, one end connected to the first node, and another end connected to a third node, and a gate connected to the second scan wiring; A fourth switching transistor having one end connected to a third node and the other end connected to a fourth node, a fifth switching transistor having a gate connected to the first scan wiring and one end connected to the fourth node, and a third node connected to the third node; A driving transistor having a gate connected thereto, one end connected to a first power line, and the other end connected to the fourth node, and a first electrode connected to the other end of the fifth switching transistor; An organic light emitting diode having a second electrode connected to a second power line, a first capacitor having one end connected to the second node and the other end connected to the first power line, and one end connected to the first power line, An organic light emitting display device comprising a second capacitor having the other end connected to three nodes. The method of claim 7, wherein The sub pixel is, The organic light emitting display device operates in an analog mode when a logic high signal is supplied from the control line and operates in a digital mode when a logic low signal is supplied from the control line. The method of claim 7, wherein When the sub-pixel is operated in the analog mode, a gray level corresponding to a driving current of the driving transistor is expressed. And the sub-pixel when the sub-pixel is operated in the digital mode, and corresponding gray scales are expressed by light emission time of the organic light emitting diode. The method of claim 7, wherein The first to fourth switching transistors are P-type transistors, and the fifth switching transistors are N-type transistors. The method of claim 7, wherein Transistors included in the sub pixel, An organic light emitting display device which is a poly transistor. Determining whether the gray level of the image data signal supplied from the outside is an upper bit group or a lower bit group; A conversion step of converting the video data signal corresponding to the upper bit group into the analog data signal and converting the video data signal corresponding to the lower bit group into the digital data signal; And And supplying the analog data signal and the digital data signal to a sub pixel. The method of claim 12, In the determining step, And determining the lower bit group and the remaining bits as the upper bit group when the gray level of the image data signal is lower 3 to 4 bits. The method of claim 12, After the conversion step, And a setting step of supplying a control signal to the subpixel so that the subpixel selectively supplied with the analog data signal and the digital data signal is driven in an analog mode and a digital mode. . The method of claim 14, When the sub-pixel is operated in the analog mode, a gray level corresponding to a driving current of a driving transistor included in the sub-pixel is expressed. And a gray level corresponding to a light emission time of an organic light emitting diode included in the subpixel when the subpixel is operated in the digital mode.

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