KR20070045848A - Display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, the device having a plurality of image pixels and a sample pixel for displaying an image, the luminance sensor for sensing a luminance of the sample pixel and generating a detection signal, the image having a predetermined range. A sample data generation unit for generating data of the sample pixels by averaging data of pixels; outputting image data signals corresponding to data of the image pixels to the image pixels; and corresponding to data of the sample pixels to the sample pixels And a data driver for outputting a sample data signal, and a gray voltage generator for outputting a gray voltage corrected according to the detection signal of the luminance sensor to the data driver. Therefore, by sensing the luminance of the sample pixel and correcting the gradation voltage of the data driver, it is possible to compensate for the unbalance of the white balance and the luminance decrease of the image pixel.

OLED display, gray voltage generator, detection signal, luminance

Description

Display device {DISPLAY DEVICE}

1 is a block diagram of an organic light emitting diode display according to an exemplary embodiment of the present invention.

2 is an equivalent circuit diagram of one pixel of an organic light emitting diode display according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating an example of a cross section of a driving transistor and an organic light emitting diode of one pixel of the organic light emitting diode display illustrated in FIG. 2.

4 is a schematic diagram of an organic light emitting diode of an organic light emitting diode display according to an exemplary embodiment.

5A is a block diagram of a sample data generator of an organic light emitting diode display according to an exemplary embodiment.

5B is a block diagram of another sample data generator of an organic light emitting diode display according to an exemplary embodiment.

6 is a signal waveform diagram illustrating an operation of an organic light emitting diode display according to an exemplary embodiment of the present invention.

7 is a graph illustrating a lookup table of a signal controller of an organic light emitting diode display according to an exemplary embodiment of the present invention.

8 is a block diagram of an organic light emitting diode display according to another exemplary embodiment of the present invention.

The present invention relates to a display device.

In recent years, with the reduction in weight and thickness of personal computers and televisions, display devices are also required to be lighter and thinner, and cathode ray tubes (CRTs) are being replaced by flat panel displays.

Such flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), organic light emitting displays, plasma display panels (PDPs), and the like. There is this.

In general, in an active matrix flat panel display, a plurality of pixels are arranged in a matrix form, and an image is displayed by controlling the light intensity of each pixel according to given luminance information. Among these, an organic light emitting display is a display device that displays an image by electrically exciting and emitting a fluorescent organic material. The organic light emitting display is a self-emission type, has a low power consumption, a wide viewing angle, and a fast response time of pixels. It is easy.

The organic light emitting diode display includes an organic light emitting diode (OLED) and a thin film transistor (TFT) driving the same. The thin film transistor is classified into a polysilicon thin film transistor and an amorphous silicon thin film transistor according to the type of the active layer. The organic light emitting diode display employing the polycrystalline silicon thin film transistor has various advantages, and thus is widely used. However, the manufacturing process of the polysilicon thin film transistor is complicated and thus the cost is increased. In addition, such an organic light emitting display device is difficult to obtain a large screen.

On the other hand, an organic light emitting display device employing an amorphous silicon thin film transistor is easy to obtain a large screen, and the manufacturing process is relatively smaller than that of an organic light emitting display device employing a polysilicon thin film transistor.

The organic light emitting diode display displays predetermined light using different organic light emitting diodes emitting red, green, and blue light, respectively. At this time, the organic light emitting device has different luminous efficiency and degree of deterioration according to the emission color. Especially, the organic light emitting device that emits blue light has a shorter lifespan compared to other organic light emitting devices. Is broken and the screen looks yellow.

In addition, organic light emitting devices that emit not only blue but also red and green light deteriorate with time, so that luminance decreases with respect to the same data voltage.

Accordingly, an aspect of the present invention is to provide an organic light emitting display device capable of compensating for a reduction in luminance of each organic light emitting device that emits red, green, and blue light while maintaining white balance.

According to an aspect of the present invention, there is provided a display device including: a luminance detector which has a plurality of image pixels and a sample pixel for displaying an image, and detects the luminance of the sample pixel to generate a detection signal; A sample data generation unit which averages data of the image pixels in a predetermined range, and generates data of the sample pixel, outputs an image data signal corresponding to data of the image pixel to the image pixel, and outputs the image pixel to the sample pixel And a data driver for outputting a sample data signal corresponding to the data of the sample pixel, and a gray voltage generator for outputting a gray voltage corrected according to the detection signal of the luminance detector to the data driver.

The sample data generation unit divides the entire gradation into at least two gradation groups having a predetermined range, and counts the number of data of the image pixels included in each gradation group, and selects a specific gradation group from the counter. The apparatus may include a data averager for generating the sample pixel data having an average value of data of the image pixels included in the grayscale group.

The selected gradation group may be the maximum number of data of the image pixels included in the gradation group among the data of the image pixels of one frame. The gradation range of the gradation group may be different for each gradation group.

The sample pixel data may include fixed reference grayscale data applied with a predetermined period.

The display device may include a sensing signal processor configured to read a sensing signal according to luminance when the sample pixel emits light according to the reference gray scale data.

The sample pixel may be a plurality of pixels that emit red, green, and blue light, respectively.

The sample data generator may include a plurality of counters and a data averager for generating data of the red, green, and blue sample pixels, respectively. DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

All. Since the detection signal processing of the detection signal processing unit 800 and the operation of the signal control unit 600 are the same as those of FIG. 1, the thickness is enlarged in order to clearly express various layers and regions in the luminance sensitivity of the image pixel PX. It was. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A display device according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a block diagram of an organic light emitting diode display according to an exemplary embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of one pixel of the organic light emitting diode display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, an organic light emitting diode display according to an exemplary embodiment includes a display panel 300, a scan driver 400 connected to the display panel 300, a data driver 500, and a sensing signal processor. 800, a gray voltage generator 550 connected to the data driver 500, and a signal controller 600 for controlling the gray voltage generator 550.

The display panel 300 may include a plurality of signal lines G ₁ -G _n , D ₁ -D _m , a plurality of voltage lines (not shown), and a plurality of signal lines connected to them and arranged in a substantially matrix form when viewed as an equivalent circuit. Includes an image pixel PX.

Include - (D _m D ₁₎ signal lines _{(G 1 -G n, D 1} -D m) is a data line to a plurality of scanning signal lines (G ₁ -G _n) and passes the data signal to pass the scanning signal. The scan signal lines G ₁ -G _n extend substantially in the row direction and are substantially parallel and separated from each other. The data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other. Each voltage line (not shown) transfers a driving voltage Vdd or the like.

Referring to FIG. 2, each pixel PX, for example, an image pixel of an ith row (i = 1, 2, 3, ..., n) and j columns (j = 1, 2, 3, ..., m) PX includes an organic light emitting element LD, a driving transistor Qd, a capacitor Cst, and a switching transistor Qs.

In the driving transistor Qd, an input terminal is connected with a driving voltage Vdd, an output terminal is connected with an anode electrode of the organic light emitting element LD, and a control terminal is connected with an output terminal of the switching transistor Qs.

The organic light emitting element LD is a light emitting diode having a light emitting layer, and an anode electrode is connected to an output terminal of the driving transistor Qd, and a cathode electrode is connected to a common voltage Vcom. The organic light emitting element LD receives the driving current ILD from the driving transistor Qd to emit predetermined light.

The capacitor Cst is connected between the control terminal and the input terminal of the driving transistor Qd. The capacitor Cst charges and maintains a charge corresponding to the difference between the data voltage Vdat and the driving voltage Vdd supplied through the switching transistor Qs.

In the switching transistor Qs, an input terminal is connected to the data line Dj, an output terminal is connected to the control terminal of the driving transistor Qd, and the control terminal is connected to the scan signal line Gi.

The switching transistor Qs and the driving transistor Qd are formed of an n-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) made of amorphous silicon or polycrystalline silicon. However, these transistors Qs and Qd may also be p-channel MOSFETs. In this case, since the p-channel MOSFET and the n-channel MOSFET are complementary to each other, the operation, voltage, and current of the p-channel MOSFETs are determined by the n-channel MOSFETs. On the contrary.

The luminance detector 350 includes a plurality of sample pixels SP _R , SP _G , and SP _B and a sensing unit.

The sample pixels SP _R , SP _G , and SP _B are connected to some of the sample scan signal lines Gs and the data lines, and have substantially the same circuit structure and characteristics as the image pixels PX. The sample pixels SP _R , SP _G , and SP _B include a red sample pixel SP _R , a green sample pixel SP _G , and a blue sample pixel SP _B , depending on the emission color, like the image pixel PX.

One or more sample pixels SP _R , SP _G , and SP _B may exist for each of these emission colors.

If there is one sample pixel (SP _R , SP _G , SP _B ) for each emission color, the red, green, and blue sample pixels (SP _R , SP _G , SP _B ) are arranged approximately in the row direction so that one sample The scan signal line G _s is turned on at the same time and receives a sample data signal from a data line connected to each of the sample pixels SP _R , SP _G , and SP _B.

The sensing unit SU is connected between the sample pixels SP _R , SP _G , and SP _B and the sensing signal processing unit 800, and measures the luminance according to light emission of each of the sample pixels SP _R , SP _G , and SP _B. Sense to generate a sense signal. The sensing unit SU may include a photo diode (not shown) and the like, and may further include a photo transistor (not shown) for amplifying a sensing signal.

Next, detailed structures of the driving transistor Qd and the organic light emitting element LD of the organic light emitting diode display will be described in detail with reference to FIGS. 3 and 4.

FIG. 3 is a cross-sectional view illustrating an example of a cross section of a driving transistor Qd and an organic light emitting element LD of one pixel of the organic light emitting diode display illustrated in FIG. 2, and FIG. 4 is a cross-sectional view of an embodiment of the present invention. A schematic diagram of an organic light emitting element of an organic light emitting display device.

The control electrode 124 is formed on the insulating substrate 110. The control terminal electrode 124 is an aluminum-based metal such as aluminum (Al) or an aluminum alloy, a silver-based metal such as silver (Ag) or a silver alloy, a copper-based metal such as copper (Cu) or a copper alloy, and molybdenum (Mo) And a molybdenum-based metal such as molybdenum alloy, chromium (Cr), titanium (Ti), and tantalum (Ta) are preferably made. However, the control terminal electrode 124 may have a multilayer structure including two conductive films (not shown) having different physical properties. One of the conductive films is made of a low resistivity metal such as an aluminum-based metal, a silver-based metal, or a copper-based metal to reduce signal delay or voltage drop. On the other hand, other conductive films are made of other materials, particularly materials having excellent physical, chemical and electrical contact properties with indium tin oxide (ITO) and indium zinc oxide (IZO), such as molybdenum-based metals, chromium, titanium, tantalum, and the like. A good example of such a combination is a chromium bottom film, an aluminum (alloy) top film, an aluminum (alloy) bottom film and a molybdenum (alloy) top film. However, the control terminal electrode 124 may be made of various various metals and conductors. The control terminal electrode 124 is inclined with respect to the substrate 110 surface and its inclination angle is 30-80 °.

An insulating layer 140 made of silicon nitride (SiNx) is formed on the control terminal electrode 124.

On the insulating film 140, a semiconductor 154 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated as a-Si), polycrystalline silicon, or the like is formed. On the semiconductor 154, a pair of ohmic contacts 163 and 165 made of a material such as n + hydrogenated amorphous silicon doped with silicide or n-type impurities at a high concentration are formed. Side surfaces of the semiconductor 154 and the ohmic contacts 163 and 165 are inclined with respect to the substrate 110 surface, and the inclination angle is 30-80 °.

An input electrode 173 and an output electrode 175 are formed on the ohmic contacts 163 and 165 and the insulating layer 140. The input terminal electrode 173 and the output terminal electrode 175 are preferably made of refractory metals such as chromium, molybdenum-based metals, tantalum, and titanium. It may have a multi-layer structure including a low resistance material upper layer (not shown) disposed thereon. Examples of the multilayer structure include a double layer of chromium or molybdenum (alloy) lower layer and an aluminum upper layer, and a triple layer of molybdenum (alloy) lower layer-aluminum (alloy) interlayer-molybdenum (alloy) upper layer. Like the input terminal electrode 124 and the like, the input terminal electrode 173 and the output terminal electrode 175 are also inclined at an angle of about 30-80 °.

The input terminal electrode 173 and the output terminal electrode 175 are separated from each other and positioned on both sides of the control terminal electrode 124. The control terminal electrode 124, the input terminal electrode 173, and the output terminal electrode 175 together with the semiconductor 154 form a driving transistor Qd, and its channel is the input terminal electrode 173 and the output terminal. It is formed in the semiconductor 154 between the electrodes 175.

The ohmic contacts 163 and 165 exist only between the semiconductor 154 thereunder and the input terminal electrode 173 and the output terminal electrode 175 thereon, and lower the contact resistance. The semiconductor 154 has an exposed portion without being covered by the input terminal electrode 173 and the output terminal electrode 175.

A passivation layer 180 is formed on the input terminal electrode 173, the output terminal electrode 175, the exposed portion of the semiconductor 154, and the insulating layer 140. The passivation layer 180 may be made of an inorganic insulator or an organic insulator, and may have a flat surface. Examples of the inorganic insulator include silicon nitride and silicon oxide. The organic insulator may have photosensitivity and the dielectric constant is preferably about 4.0 or less. However, the passivation layer 180 may have a double layer structure of the lower inorganic layer and the upper organic layer so as not to damage the exposed portion of the semiconductor 154 while maintaining excellent insulating properties of the organic layer.

The pixel electrode 190 is formed on the passivation layer 180. The pixel electrode 190 is physically and electrically connected to the output terminal electrode 175 through the contact hole 185, and may be formed of a transparent conductive material such as ITO or IZO, or a metal having excellent reflectivity of aluminum or silver alloy. have.

The partition 361 is further formed on the passivation layer 180. The partition 361 defines an opening by surrounding a periphery of the pixel electrode 190 like a bank and is made of an organic insulating material or an inorganic insulating material.

An organic light emitting member 370 is formed on the pixel electrode 190, and the organic light emitting member 370 is trapped in an opening surrounded by the partition 361.

As illustrated in FIG. 4, the organic light emitting member 370 has a multilayer structure including auxiliary layers for improving the light emitting efficiency of the light emitting layer EML in addition to the light emitting layer EML. The secondary layer contains an electron transport layer (ETL) and hole transport layer (HTL) to balance electrons and holes, and an electron injecting layer to enhance injection of electrons and holes. (EIL) and hole injecting layer (HIL). Subsidiary layers may be omitted.

The common electrode 270 to which the common voltage Vcom is applied is formed on the partition 361 and the organic light emitting member 370. The common electrode 270 is made of a reflective metal including calcium (Ca), barium (Ba), aluminum (Al), or a transparent conductive material such as ITO or IZO.

The opaque pixel electrode 190 and the transparent common electrode 270 are applied to a top emission organic light emitting display device that displays an image in an upper direction of the display panel 300. The opaque common electrode 270 is applied to a bottom emission organic light emitting display device that displays an image in a downward direction of the display panel 300.

The pixel electrode 190, the organic light emitting member 370, and the common electrode 270 form an organic light emitting element LD illustrated in FIG. 2, and the pixel electrode 190 is an anode and the common electrode 270 is a cathode or a pixel. The electrode 190 becomes a cathode and the common electrode 270 becomes an anode. The organic light emitting element LD emits light of one of the primary colors according to the material of the organic light emitting member 370. Examples of the primary colors include three primary colors of red, green, and blue, and the desired color is represented by a spatial sum of these three primary colors.

Referring back to FIG. 1, the scan driver 400 is connected to the scan signal lines G ₁ -G _n and G _s of the display panel 300 to turn on the switching transistor Qs and the high voltage Von. Scan signals Vg ₁ -Vg _n , Vg _s , which are a combination of low voltage Voff that can be turned off, are applied to scan signal lines G ₁ -G _n , G _s , respectively.

The data driver 500 is connected to the data lines D ₁ -D _m of the display panel 300 to apply an analog data voltage Vdat representing an image data signal or a sample data signal to the data lines D ₁ -D _m . do.

The gray voltage generator 550 receives the gray scale control signal CONT4 from the signal controller 600, converts the gray scale control signal CONT4 into an analog gray voltage, and outputs it to the digital-analog converter (not shown) of the data driver 500. The gray voltage generator 550 has a different gray reference voltage according to the emission color.

The sensing signal processor 800 receives a sensing signal from the sensing unit SU and processes the signal to generate a digital sensing signal DSN.

The scan driver 400, the data driver 500, the gray voltage generator 550, and the sense signal processor 800 may be directly mounted on the display panel 300 in the form of a plurality of driving integrated circuit chips, or may be provided with a flexible printed circuit film. It may be mounted on a flexible printed circuit film (not shown) and attached to the display panel 300 in the form of a tape carrier package (TCP). In contrast, the scan driver 400, the data driver 500, the gray voltage generator 550, and the sense signal processor 800 are formed on the display panel 300 together with signal lines and transistors to form a system on panel (SOP). It can also be implemented.

The signal controller 600 controls operations of the scan driver 400, the data driver 500, the gray voltage generator 550, and the sense signal processor 800.

The signal controller 600 is configured to control the input image signals R, G, and B and their display from an external graphic controller (not shown), for example, a vertical synchronization signal Vsync and a horizontal synchronization signal ( Hsync, main clock MCLK, and data enable signal DE are provided.

The signal controller 600 includes a sample data generator 650 for generating sample pixel data R _S , G _S , and B _S according to the received input image signals R, G, and B.

5A is a block diagram of a sample data generator of an organic light emitting diode display according to an exemplary embodiment.

Referring to FIG. 5A, the sample data generator 650 of the organic light emitting diode display according to the exemplary embodiment includes registers 651, 652, and 653 and data averagers 656, 657, and 658.

The registers 651, 652, and 653 receive the image signals R, G, and B of one frame from the outside and store them for a predetermined time. The data averagers 656, 657, and 658 calculate average values of the image signals R, G, and B stored in the registers 651, 652, and 653, and sample pixel data R _S and G having these average values. _S , B _S ).

The image signals R, G, and B stored in the registers 651, 652, and 653 of the sample data generator 650 need not be the image signals R, G, and B of all the image pixels PX. It may be the image signals R, G, and B of a plurality of specific image pixels PX. When the sample pixel data R _S , G _S , and B _S are generated using the image signals R, G, and B of a plurality of specific image pixels PX, the memory of the registers 651, 652, and 653 is reduced. In addition, the number of operations performed on the average value calculation can be reduced.

The sample data generator 650 includes red, green, and blue registers 651, 652, and 653 and one data averager 656, 657, and 658, respectively, according to the emission color. The registers 651, 652, and 653 of a specific emission color, for example, the red register 651, receive an image signal R of the red image pixel PX from the outside and store the image signal R from the outside, and average the red sample pixel SP. and it generates a pixel data sample (R _S) of _R).

5B is a block diagram of another sample data generator of an organic light emitting diode display according to an exemplary embodiment.

Referring to FIG. 5B, another sample data generator 650 of the organic light emitting diode display according to an exemplary embodiment may include counters 651, 652, and 653 and data averagers 656, 657, and 658. It includes.

The counters 651, 652, and 653 include a plurality of gradation groups obtained by dividing the entire gradations into a predetermined range. The counters 651, 652, and 653 receive image signals R, G, and B of one frame from the outside, and select a gray level group including grays represented by the respective image signals R, G, and B.

The counters 651, 652, and 653 count the number of image signals R, G, and B included in each gray level group, and count the gray level group including the largest number of image signals R, G, and B. Choose. The data averagers 656, 657, and 658 calculate average values of the image signals R, G, and B of the gradation group selected by the counters 651, 652, and 653, and sample pixel data R having these average values. _S , G _S , B _S )

The range of the gradation groups of the counters 651, 652, and 653 may be different for each gradation group, and the number and range of the gradation groups are characteristically distinguished by experiments. Can be determined.

For example, in an organic light emitting diode display having a total gray scale of 256 levels, all grays are divided into eight gray levels, and all gray levels are set to the same 32. Of the 100 image signals (R, G, B) of one frame, two in the first gradation group having 0-31 gradations, five in the second gradation group having 32-63 gradations, 64-95 8 in the 3rd gradation group having steps, 10 in the 4th gradation group having steps 96-127, 40 in the 5th gradation group having steps 128-159, 6th in the 6th gradation group having steps 160-191 Suppose that five video signals R, G, and B are included in the seventh grayscale group having 20, 192-223 steps, and the eighth grayscale group having 224-255 steps, the counters 651, 652, 653) selects a gray level group of the fifth step. Accordingly, the image signals R, G, and B of the image pixels PX, which are averaged by the data averagers 656, 657, and 658, have 40 image signals R, G, B). The organic light emitting diode display having the sample data generator 650 maintains the white balance by generating sample pixel data R _S , G _S , and B _S from a plurality of image signals R, G, and B having small deviations. Can be.

In addition, although the image signals R, G, and B of all the image pixels PX of one frame may be applied to the counters 651, 652, and 653, the image signals R, G, of the image pixels PX of a specific region may be applied. Only G, B) may be applied to the counters 651, 652, 653.

The sample data generator 650 includes one of the red, green, and blue counters 651, 652, and 653 and the data averagers 656, 657, and 658 according to the emission color. The counters 651, 652, and 653 of the specific emission color, for example, the red counter 651, receive an image signal R of the red image pixel PX from the outside, process the image, and average the red sample pixel SP. and it generates a pixel data sample (R _S) of _R).

 The signal controller 600 properly processes the image signals R, G, and B according to the operating conditions of the display panel 300 based on the input image signals R, G, and B and the input control signal, and scan control signals CONT1. ), A data control signal CONT2, a sensing control signal CONT3, a gray scale control signal CONT4, and the like.

The signal controller transmits the scan control signal CONT1 to the scan driver 400, and the digital image pixel data DAT and sample pixel data R _S , G _S , and B _S processed with the data control signal CONT2 are data driver. In operation 500, the sensing control signal CONT3 is sent to the sensing signal processor 800, and the gray control signal CONT4 is sent to the gray voltage generator 550.

The scan control signal CONT1 includes a scan start signal STV for instructing the scan start of the high voltage Von and at least one clock signal for controlling the output of the high voltage Von. The scan control signal CONT1 may also include an output enable signal OE that defines the duration of the high voltage Von.

The data control signal CONT2 includes a horizontal synchronization start signal STH for transmitting data of one pixel row, a load signal LOAD for applying a corresponding data voltage to the data lines D1-Dm, a data clock signal HCLK, and the like. It includes.

Hereinafter, an operation of the organic light emitting diode display will be described.

6 is a signal waveform diagram illustrating an operation of an organic light emitting diode display according to an exemplary embodiment of the present invention.

Referring to FIG. 6, in the average sample pixel data interval, the signal controller 600 receives the image signals R, G, and B of one frame, and thus, the image pixel data DAT and the image signals R, G, and B. Sample pixel data R _S , G _S , and B _S having an average value of are generated.

The data driver 500 controls the digital image data DAT according to the data control signal CONT2 from the signal controller 600 and the gray voltages V _R , V _G , and V _B from the gray voltage generator 550. The sample pixel data R _S , G _S , and B _S are converted into analog image data signals and sample data signals, respectively.

The scan driver 400 sequentially changes the scan signals Vg _{1 to} Vg _n to the high voltage Von according to the scan control signal CONT1 from the signal controller 600.

When the scan signal Vg _i of the high voltage Von is supplied from the scan driver 400, the switching transistor Qs of the image pixel PX is turned on. The driving transistor Qd receives the analog image data signal Vdat through the turned-on switching transistor Qs and outputs a corresponding driving current I _LD to the organic light emitting element LD. Therefore, the organic light emitting element LD emits light corresponding to the driving current I _LD supplied. This operation proceeds to the image pixels PX of the nth row in order to display one image.

Next, when the scan signal Vg _s of the high voltage Von is applied to the sample scan signal line G _s connected to the sample pixels SP _R , SP _G , and SP _B , the sample pixels SP _R , SP _G , The organic light emitting element LD of SP _B emits predetermined light according to the sample data signal.

Since the sample data signal has an average value of the image data signals of the image pixels PX of the corresponding frame, the luminance of the sample pixels SP _R , SP _G , and SP _B has an average value of the luminance of the plurality of image pixels PX. .

When this operation is repeated for a plurality of frames, the sample pixels SP _R , SP _G , and SP _B have a luminance similar to that of the organic light emitting element LD of the image pixel PX due to deterioration of the organic light emitting element LD. Has a decrease.

Next, in the detection period, the signal controller 600 transfers the reference gray data, which is fixed to a specific value as the sample pixel data R _S , G _S , and B _S , to the data driver 500 together with the image pixel data DAT. Output In this case, the reference gray scale data may represent the highest gray level.

The data driver 500 controls the reference gray scale data and the image pixel data according to the data control signal CONT2 from the signal controller 600 and the gray voltages V _R , V _G , and V _B of the gray voltage generator 550. DAT) is converted into an analog reference grayscale data signal and an image data signal.

The image pixel PX of the display panel 300 receives the scan signal Vg _i transitioned to the high voltage Von from the scan driver 400, and receives the image data signal from the data driver 500 to emit a predetermined light. It emits light. After the light emission operation of the n rows of image pixels PX is completed, the sample pixels SP _R , SP _G , and SP _B receive the scan signal Vg _s having the high voltage Von from the scan driver 400.

The switching transistors Qs of the sample pixels SP _R , SP _G , and SP _B are turned on by the scan signal Vg _s of the high voltage Von, and the driving transistor Qd is transferred through the switching transistor Qs. The driving current flows according to the reference gray scale data signal, and the light emitting element LD emits predetermined light according to the driving current. Sample pixel _{(SP R, SP G, SP} B) sensing unit (SU) which is connected to detects the brightness of the sample pixel _{(SP R, SP G, SP} B), thereby detecting that has an analog current or voltage Generate a signal.

In this case, the signal controller 600 outputs the sensing control signal CONT3 to the sensing signal processor 800, and thus the sensing signal processor 800 reads the sensing signal of the sensing unit SU. The sensing signal processor 800 amplifies and analog-to-digitalizes the read sensing signal, generates a digital sensing signal DSN, and outputs the digital sensing signal DSN to the signal controller 600.

The signal controller 600 outputs the gray scale control signal CONT4 corrected according to the digital sensing signal DSN supplied from the sensing signal processor 800 to the gray voltage generator 550.

7 is a graph illustrating a lookup table of a signal controller of an organic light emitting diode display according to an exemplary embodiment of the present invention.

Referring to FIG. 7, a look-up table has a function indicating a gray scale control signal CONT4 for data DATA representing gray scales. The lookup table LUT has a plurality of graphs having different gamma values according to the digital sensing signal DSN supplied from the sensing signal processor 800.

In the average sample data section before the sensing operation, for example, when the gray scale control signal CONT4 is output according to the zeroth function, in the sensing section, the signal controller 600 may include a digital sensing signal having information of luminance reduction. According to DSN), the gray scale control signal CONT4 according to the first function having a gamma value larger than the zeroth function is output.

The fourth to fourth functions are determined according to the digital sensing signal DSN having information of luminance reduction, and the gray scale control is performed by interpolation in the case of the digital sensing signal DSN corresponding to the gamma value between the five functions. Signal CONT4 may be generated. The signal controller 600 has red, green, and blue lookup tables LUTs having different gamma values depending on the luminous efficiency and the degree of deterioration of the organic light emitting element LD.

The gray voltage generator 550 receives the gray scale control signal CONT4 of the first function and converts the gray scale voltages V _R , V _G , and V _B to the data driver 500.

Therefore, in the average sample data section after the detection section, the image data signal and the sample data signal are generated according to the gray scale voltages V _R , V _G , and V _B of the first function. Therefore, the degree of luminance decrease due to deterioration of the organic light emitting element LD of the image pixel PX is sensed, and thus the white balance and luminance decrease can be compensated by increasing the gamma voltages V _R , V _G , and V _B. have.

The gamma voltage (V _R , V _G , V _B ) compensation according to the luminance detection is performed with a predetermined period by a timer included in the signal controller 600, so that the luminance and the unbalance of the white balance that occur continuously are continuously generated. To compensate periodically.

8 is a block diagram of an organic light emitting diode display according to another exemplary embodiment of the present invention.

Referring to FIG. 8, an organic light emitting diode display according to another exemplary embodiment of the present invention may include a display panel 300, a scan driver 400 connected to a sign 300, a data driver 500, and a sensing signal processor. 800, a gray voltage generator 550 connected to the data driver 500, and a signal controller 600 for controlling the gray voltage generator 550.

In another exemplary embodiment, the organic light emitting diode display includes a scan driver 400, a data driver 500, a gray voltage generator 550, a detection signal processor 800, and a signal controller 600 controlling them. Since it is the same as that, description thereof is omitted.

The display panel 300 is connected to a plurality of scan signal lines G ₁ -G _n and a plurality of data lines D ₁ -D _m , and includes a plurality of image pixels PX and a plurality of image lines arranged in a substantially matrix form. The luminance sensor 350 includes a sample pixel SP _R , SP _G , and SP _B and a detector SU.

The sample pixels SP _R , SP _G , and SP _B have the same circuit configuration and device characteristics as those of the image pixel, and, like the image pixel PX, the red sample pixel SP _R and the green sample pixel SP _G according to the emission color. And a blue sample pixel SP _B.

The red, green, and blue sample pixels SP _R , SP _G , and SP _B are arranged in approximately column directions, connected to each scan signal line, and commonly connected to one sample data line D _S. Accordingly, the red, green, and blue sample pixels SP _R , SP _G , and SP _B are sequentially turned on in accordance with a scan signal that transitions to the high voltage Von, thereby converting the sample data signal from the sample data line D _S. To be supplied.

The sensing unit SU is connected between the sample pixels SP _R , SP _G , and SP _B and the sensing signal processing unit 800, and the luminance according to the emission of each of the sample pixels SP _R , SP _G , and SP _B is measured. It is possible to compensate for the detection and generation of the detection signal.

As described above, according to the present invention, the luminance of the sample pixel may be sensed and the gray voltage of the data driver may be corrected to compensate for the unbalance and the decrease in the white balance of the image pixel.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (8)

A plurality of image pixels for displaying an image, A luminance sensor including a sample pixel and generating a detection signal by sensing the luminance of the sample pixel; A sample data generator which averages data of the image pixels in a predetermined range and generates data of the sample pixels; A data driver which outputs an image data signal corresponding to the data of the image pixel to the image pixel, and outputs a sample data signal corresponding to the data of the sample pixel to the sample pixel; A gray voltage generator which generates and corrects a gray voltage according to the detection signal of the luminance detector, and outputs the corrected gray voltage to the data driver. Display device comprising a. In claim 1, The sample data generation unit, A counter for dividing the entire grayscale into at least two grayscale groups having a predetermined range, and counting the number of data of the image pixels included in each grayscale group; and And a data averager for selecting a specific gray level group from the counter and generating the sample pixel data having an average value of data of the image pixels included in the gray level group. In claim 2, And wherein the selected gray level group is the maximum number of data of the image pixels included in the gray level group among data of the image pixels of one frame. In claim 3, The gradation range of the gradation group is different for each gradation group. In claim 4, And the sample pixel data includes fixed reference grayscale data applied with a predetermined period. In claim 5, The display device And a sensing signal processor configured to read a sensing signal corresponding to luminance when the sample pixel emits light according to the reference gray scale data. In claim 6, The sample pixel is a plurality of pixels that emit red, green, and blue light, respectively. In claim 7, The sample data generator includes a plurality of counters and a data averager for generating data of the red, green, and blue sample pixels, respectively.

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