KR20180046322A - Organic Light Emitting Display And Sensing Method For Electric Characteristics Of The Same - Google Patents

Abstract

The present invention includes: a display panel including a plurality of pixels including an organic light emitting sensing pixel and a non-sensing pixel, wherein the plurality of pixels share a first sensing line; a sensing circuit which is connected to a shared sensing line for sensing a leakage current value of the non-sensing pixel and sensing an electrical characteristic value of the sensing pixel into which the leakage current value is mixed; and a sensing value correction circuit for correcting the electrical characteristic value of the sensing pixel based on the leakage current value of the non-sensing pixel. Accordingly, the present invention can remarkably increase the accuracy of sensing.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting display and a method of sensing an electrical characteristic of the organic light emitting display.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display and a method of sensing an electrical characteristic thereof.

The active matrix type organic light emitting display device includes an organic light emitting diode (OLED) which emits light by itself, has a high response speed, and has a high luminous efficiency, luminance, and viewing angle.

The organic light emitting diode (OLED) includes an anode electrode, a cathode electrode, and organic compound layers (HIL, HTL, EML, ETL, EIL) formed therebetween. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer EIL). When a driving voltage is applied to the anode electrode and the cathode electrode, holes passing through the HTL and electrons passing through the ETL are transferred to the EML to form excitons, Thereby generating visible light.

The organic light emitting display device arranges the pixels each including the OLED in a matrix form and adjusts the brightness of the pixels according to the gradation of the image data. Each of the pixels includes a driving TFT (Thin Film Transistor) for controlling a driving current flowing in the OLED according to a voltage (Vgs) applied between the gate electrode and the source electrode of the pixel, (Luminance).

Generally, when the driving TFT operates in the saturation region, the pixel current (Ipixel) flowing between the drain and the source of the driving TFT is expressed by Equation (1) below.

[Equation 1]

Ipixel = 1/2 * (μ * C * W / L) * (Vgs-Vth) ²

In the equation (1),? Represents the electron mobility, C represents the capacitance of the gate oxide film, W represents the channel width of the driving TFT, and L represents the channel length of the driving TFT. Vgs represents the gate-source voltage of the driving TFT, and Vth represents the threshold voltage (or threshold voltage) of the driving TFT.

The electrical characteristics of the driver TFT, such as threshold voltage, electron mobility, and the like, are the factors that determine the driving current Ids as in Equation (1), and therefore must be the same in all pixels. However, due to various causes such as process characteristics, time-varying characteristics, and the like, electric characteristics of the driving TFTs vary between pixels. Since the electrical characteristic variation of the driving TFT causes a luminance variation, it is difficult to realize a desired picture unless such a characteristic variation is compensated.

External compensation techniques are known to compensate for luminance variations due to differences in electrical characteristics of driving TFTs. The external compensation technology senses the electrical characteristics of the drive TFT and corrects the digital data of the input image based on the sensing result.

The sensing operation for the electrical characteristics of the driving TFT is performed in the sensing circuit. The sensing circuit senses the pixel current flowing through each pixel through the sensing line. The pixel current is a reference for judging a change in the electrical characteristics of the driving TFT.

In order to minimize the decrease of the aperture ratio due to the sensing line, as shown in FIG. 1, the plurality of pixels P1 to P4 may share one sensing line. The plurality of pixels P1 to P4 sharing one sensing line may be pixels implementing different colors, and the sensing process for sensing the pixel current may proceed independently in color units. To this end, the sensing process applies a sensing data voltage (Vdata) for causing the pixel current (Ipixel) to flow only to one pixel (sensing pixel) P2 of a specific color among the pixels P1 to P4 sharing one sensing line And applies a black data voltage Vblack to the pixels of the remaining colors (non-sensing pixels) P1, P3 and P4 to block the flow of the pixel current Ipixel.

The threshold voltage of the driving TFT can be shifted in the negative (-) direction and lowered due to various causes. As the threshold voltage of the driving TFT decreases, the leakage current Ileakage of the non-sensing pixels P1, P3, and P4 increases. The leakage current Ileakage of the non-sensing pixels P1, P3, and P4 decreases the accuracy of sensing because the potential of the sensing line is higher than the normal value. 2 (A) shows the potential change of the sensing line according to the pixel current of the sensing pixel as a normal sensing value, and FIG. 2 (B) And shows the potential change of the sensing line due to the leakage current. As can be seen from FIG. 2, the non-normal sensing value is higher than the normal sensing value due to the influence of the leakage current.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an organic light emitting display device and an organic light emitting display device capable of preventing the accuracy of sensing for a sensing pixel from being degraded due to a leakage current of a non-sensing pixel when a plurality of pixels share one sensing line. And a characteristic sensing method.

According to an aspect of the present invention, there is provided an OLED display device including a display panel including a plurality of pixels including a sensing pixel and a non-sensing pixel, the plurality of pixels sharing a sensing line; A sensing circuit connected to the shared sensing line for sensing a leakage current value of the non-sensing pixel and sensing an electrical characteristic value of the sensing pixel into which the leakage current value is mixed; And a sensing value correction circuit for correcting the electrical characteristic value of the sensing pixel based on the leakage current value of the non-sensing pixel.

The sensing value correction circuit calculates a final sensing value of the sensing pixel by subtracting the leakage current value of the non-sensing pixel from the electrical characteristic value of the sensing pixel.

The electrical characteristic value of the sensing pixel is a pixel current value flowing in the driving TFT of the sensing pixel.

The present invention further includes a data driving circuit for generating a data voltage for sensing for the flow of the pixel current and a black data voltage for blocking the flow of the pixel current.

The data driving circuit applies the black data voltage to the gate electrode of the driving TFT included in the sensing pixel and the gate electrode of the driving TFT included in the non-sensing pixel so as to sense the leakage current value of the non- do.

The data driving circuit applies the sensing data voltage to the gate electrode of the driving TFT included in the sensing pixel so that the electrical characteristic value of the sensing pixel incorporated with the leakage current value is sensed, The black data voltage is applied to the gate electrode of the driving TFT included.

According to another aspect of the present invention, there is provided a method of sensing an electrical characteristic of an organic light emitting display device including a plurality of pixels including a sensing pixel and a non-sensing pixel, wherein the plurality of pixels share one sensing line, Sensing a leakage current value of the sensor through a shared sensing line; Sensing an electrical characteristic value of the sensing pixel in which the leakage current value is mixed through the shared sensing line; And correcting the electrical characteristic value of the sensing pixel based on the leakage current value of the non-sensing pixel.

In the case where a plurality of pixels share one sensing line, the leakage current of the non-sensing pixel is firstly sensed, the pixel current of the sensing pixel incorporated with the leakage current is sensed secondarily, And subtracts the result of the first sensing. Accordingly, the present invention can obtain the pixel current value of the sensing pixel excluding the leakage current value, thereby greatly improving the sensing accuracy of the sensing pixel.

FIG. 1 is a diagram for explaining that the accuracy of sensing for a sensing pixel is degraded due to leakage current of a non-sensing pixel.
FIG. 2 is a graph showing that the abnormal sensing value due to the leakage current becomes higher than the normal sensing value excluding the influence of the leakage current.
3 is a block diagram illustrating an organic light emitting display according to an embodiment of the present invention.
Figure 4 is a simplified representation of a sensing line sharing structure in which a plurality of pixels share a sensing line.
5 is a view showing an example of the connection configuration between the pixel array and the data driving circuit.
6 is a diagram illustrating a connection configuration of a pixel and a sensing circuit according to an embodiment of the present invention.
7 is a diagram illustrating another connection configuration of a pixel and a sensing circuit according to an embodiment of the present invention.
8 is a flowchart illustrating a method of sensing an electrical characteristic of an organic light emitting display according to an embodiment of the present invention.
9 and 10 are views for explaining the leakage current value sensing operation of the non-sensing pixel of FIG.
FIGS. 11 and 12 are views for explaining the electric characteristic value sensing operation of the sensing pixel of FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other partially or wholly and technically various interlocking and driving are possible and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating an organic light emitting display according to an embodiment of the present invention. Figure 4 is a simplified representation of a sensing line sharing structure in which a plurality of pixels share a sensing line. 5 is a diagram showing an example of the connection configuration between the pixel array and the data driving circuit.

3 to 5, an OLED display according to an exemplary embodiment of the present invention includes a display panel 10, a timing controller 11, a data driving circuit 12, a gate driving circuit 13, a memory 16 ), A sensing value correction circuit 20, and a sensing circuit 30.

A plurality of data lines 14A and sensing lines 14B and a plurality of gate lines 15 are crossed on the display panel 10 and the pixels P are arranged in a matrix form for each of the intersection areas .

A plurality of pixels P connected to different data lines 14A may share the same gate line with the same sensing line. For example, as shown in Fig. 4, the R pixel PR for red display, the W pixel PW for white display, the G pixel PG for green display, B pixels PB can be commonly connected to one sensing line 14B. The sensing line sharing structure in which the first sensing line 14B is commonly connected to the plurality of pixels PR, PW, PG, PB is advantageous in increasing the aperture ratio of the display panel. Under the sensing line sharing structure, the sensing lines 14B may be arranged one for each of the plurality of data lines 14A. The sensing line 14B may be shared by, but not limited to, four pixels of different colors as shown in the figure. The sensing line 14B may be shared by two or more pixels of different colors. The sensing line 14B may be disposed in parallel with the data line 14A as shown in the figure, but not limited thereto, and may be disposed so as to intersect with the data line 14A. The sensing line 14B shared by the plurality of pixels PR, PW, PG, PB is connected to the sensing circuit 30. [

Each of the pixels P is supplied with a high potential drive voltage EVDD and a low potential drive voltage EVSS from a power supply not shown. The pixel P of the present invention may have a circuit structure capable of sensing the electrical characteristics of the driving TFT. The circuit configuration of the pixel P can be variously modified. For example, in addition to the OLED and the driver TFT DT, the pixel P may include at least two switch TFTs and at least one storage capacitor. The TFTs constituting the pixel P may be implemented as a p-type, an n-type, or a hybrid type in which a p-type and an n-type are mixed. In addition, the semiconductor layer of the TFTs constituting the pixel P may include amorphous silicon, polysilicon, or an oxide.

The timing controller 11 can temporally separate the sensing drive and the display drive according to a predetermined control sequence. Here, the sensing driving is a driving for sensing the deterioration of the OLED and for updating the compensation value, and the display driving is a driving for displaying an input image in which the compensation value is mixed. By the control operation of the timing controller 11, the sensing driving is performed in the vertical blank period during the display driving, or in the power on sequence period before the display driving is started, or in the power off sequence period after the display driving is finished . The vertical blanking period is a period during which input image data (DATA) is not written, and is arranged between vertical active periods in which input image data (DATA) for one frame is written. The power-on sequence period means the transient period from when the driving power is applied until the input image is displayed. The power-off sequence period means a transient period from the end of the display of the input image until the driving power is turned off. On the other hand, the sensing driving may be performed in the vertical active section.

Also, the sensing operation may be performed in a state where only the screen of the display device is turned off during the period in which the system power is being applied, for example, in a standby mode, a sleep mode, a low power mode, and the like. The timing controller 11 senses a standby mode, a sleep mode, a low power mode, and the like according to a predetermined sensing process and controls all operations for sensing driving.

The timing controller 11 controls the timing of the data driving circuit 11 based on the timing signals such as the vertical synchronizing signal Vsync, the horizontal synchronizing signal Hsync, the dot clock signal DCLK and the data enable signal DE input from the host system. A data control signal DDC for controlling the operation timing of the gate driving circuit 12 and a gate control signal GDC for controlling the operation timing of the gate driving circuit 13 can be generated. The timing controller 11 may generate the control signals DDC and GDC for driving the display and the control signals DDC and GDC for sensing driving differently.

The gate control signal GDC includes a gate start pulse, a gate shift clock, and the like. The gate start pulse is applied to the gate stage that generates the first output to control its gate stage. The gate shift clock is a clock signal commonly input to the gate stages, and is a clock signal for shifting the gate start pulse.

The data control signal DDC includes a source start pulse, a source sampling clock, and a source output enable signal. The source start pulse controls the data sampling start timing of the data driving circuit 12. The source sampling clock is a clock signal that controls sampling timing of data based on the rising or falling edge. The source output enable signal controls the output timing of the data driving circuit 12.

The timing controller 11 may derive a compensation value based on the final sensing value calculated by the sensing value correction circuit 20 during sensing operation and store the derived compensation value in the memory 16. [ The compensation value stored in the memory 16 can be updated at each sensing operation. The timing controller 11 can compensate for the luminance deviation due to a change in the electrical characteristics of the driving TFT by correcting the digital data DATA of the input image based on the compensation value read from the memory 16 during the display driving. The timing controller 11 supplies the corrected video data (DATA) to the data driving circuit (12).

The data driving circuit 12 includes a plurality of digital-analog converters (hereinafter, DAC) connected to each data line 14A. The DAC converts the corrected image data (DATA) applied from the timing controller 11 in accordance with the data timing control signal (DDC) when the display is driven, into data voltages for image display and supplies the data voltages to the data lines 14A. On the other hand, the DAC can generate a sensing data voltage or a black data voltage in accordance with a data timing control signal (DDC) applied from the timing controller 11 in the sensing operation, and supply the sensing data voltage or the black data voltage to the data lines 14A.

The sensing data voltage is a voltage that can be applied to the gate electrode of the driving TFT to turn on the driving TFT, that is, a voltage capable of flowing a pixel current to the driving TFT. The black data voltage is a voltage that is applied to the gate electrode of the driving TFT to turn off the driving TFT, that is, a voltage that prevents the pixel current from flowing to the driving TFT.

When sensing an electrical characteristic value of a sensing pixel incorporating a leakage current value, a sensing data voltage is applied to a sensing pixel to be sensed and a black data voltage is applied to a non-sensing pixel sharing a sensing line with a sensing pixel . On the other hand, when the leakage current value of the non-sensing pixel is sensed, the black data voltage can be commonly applied to the non-sensing pixel and the sensing pixel.

The sensing circuit 30 may be mounted on the data driving circuit 12. [ The sensing circuit 30 includes a plurality of sensing units SU connected to the sensing lines 14B and mux portions SS1 and SS2 for selectively connecting the sensing units SU to an analog- And a shift register SR for generating a selection control signal to sequentially turn on the switches of the mux portions SS1 and SS2. Each sensing unit SU may be implemented as a current sensing type or voltage sensing type current-voltage converter. The ADC can convert an analog sensing signal inputted through the mux portions SS1 and SS2 into a digital sensing signal and output it to the sensing value correction circuit 20. [

The sensing circuit 30 senses and converts the leak current value Vsen1 of the non-sensing pixel sharing one sensing line 14B to the sensing value correction circuit 20. The sensing circuit 30 senses and converts the electrical characteristic value Vsen2 of the sensing pixel sharing one sensing line 14B and outputs it to the sensing value correction circuit 20. [ Here, the leakage current value Vsen1 of the non-sensing pixel is a value obtained by sensing the current leaked from the driving TFT of the non-sensing pixel, and the electrical characteristic value Vsen2 of the sensing pixel is the leakage current value Vsen1 of the non- Is a value obtained by sensing the pixel current flowing through the driving TFT of the added sensing pixel. The reason that the leakage current value Vsen1 of the non-sensing pixel is incorporated into the electrical characteristic value Vsen2 of the sensing pixel is because it takes a shared sensing line structure.

The sensing value correction circuit 20 corrects the electrical characteristic value Vsen2 of the sensing pixel based on the leakage current value Vsen1 of the non-sensing pixel. Specifically, the sensing value correction circuit 20 subtracts the leakage current value Vsen1 of the non-sensing pixel from the electrical characteristic value Vsen2 of the sensing pixel, thereby calculating the final sensing value Vsen1 of the non- Lt; / RTI > Since the final sensing value does not include the leak current value Vsen1 of the non-sensing pixel, the accuracy of sensing is increased. The sensing value correction circuit 20 may be incorporated in the timing controller 11, but is not limited thereto. The sensing value correction circuit 20 may be mounted outside the timing controller 11. [

The gate driving circuit 13 generates a scan control signal based on the gate control signal GDC during the sensing operation and supplies the scan control signal to the first gate lines 15A (i) to 15A (i + 3) And supplies it to the second gate lines 15B (i) to 15B (i + 3).

The gate driving circuit 13 generates a scan control signal based on the gate control signal GDC during display driving and supplies the generated scan control signal to the first gate lines 15A (i) to 15A (i + 3) And supplies it to the second gate lines 15B (i) to 15B (i + 3).

The shifter resistors constituting the gate driving circuit may be manufactured in the form of an integrated circuit and connected to the display panel 10 or may be connected to the display panel 10 through a TFT process of a gate driver in panel (GIP) Or may be formed directly on the non-display area.

6 is a diagram illustrating a connection configuration of a pixel and a sensing circuit according to an embodiment of the present invention. 7 is a view showing another connection configuration of the pixel and the sensing circuit according to the embodiment of the present invention. It should be noted that the technical concept of the present invention is not limited to Fig. 6 and Fig. 7 since Fig. 6 and Fig. 7 are merely examples of the pixel and the sensing circuit.

6 and 7, each pixel P includes an OLED, a driving TFT (Thin Film Transistor) DT, a storage capacitor Cst, a first switch TFT ST1, and a second switch TFT ST2. .

The OLED includes an anode electrode connected to the source node N2, a cathode electrode connected to the input terminal of the low potential driving voltage (EVSS), and an organic compound layer positioned between the anode electrode and the cathode electrode.

The driving TFT DT controls the pixel current Ipixel input to the OLED according to the gate-source voltage Vgs. The driving TFT DT has a gate electrode connected to the gate node N1, a drain electrode connected to the input terminal of the high potential driving voltage EVDD, and a source electrode connected to the source node N2. The storage capacitor Cst is connected between the gate node N1 and the source node N2. The first switch TFT ST1 applies a voltage (for example, a sensing data voltage, a black data voltage, an image display data voltage) on the data line 14A to the gate node N1 in response to the scan control signal SCAN do. The first switch TFT ST1 has a gate electrode connected to the first gate line 15A, a drain electrode connected to the data line 14A, and a source electrode connected to the gate node N1. The second switch TFT (ST2) switches the current flow between the source node (N2) and the sensing line (14B) in response to the sensing control signal (SEN). The second switch TFT ST2 has a gate electrode connected to the second gate line 15B, a drain electrode connected to the sensing line 14B, and a source electrode connected to the source node N2.

The sensing circuit 30 including the current sensing type sensing unit SU is shown in Fig.

Referring to FIG. 6, the sensing circuit 30 is implemented with a current sensing type sensing unit (SU) including a current integrator (CI), a sample and hold unit (SH), and an ADC.

The current integrator CI is connected to the pixel P via a sensing line 14B. The current integrator CI applies the initialization voltage Vpre to the source node N2 of the pixel P through the sensing line 14B. The current integrator CI then integrates the pixel current Ipixel input from the pixel P to generate the analog sensing voltage Vsen. The current integrator CI includes an inverting input terminal (-) receiving the pixel current Ipixel through the sensing line 14B, a non-inverting input terminal (+) connected to the input terminal of the initializing voltage Vpre, An integral capacitor Cfb connected between the inverting input terminal (-) and the output terminal of the amplifier AMP and a reset switch RST connected to both ends of the integrating capacitor Cfb .

A sample-and-hold unit SH is connected to the output terminal of the current integrator CI. The sample-and-hold unit SH samples the analog sensing voltage Vsen output from the amplifier AMP and supplies it to the ADC. The ADC converts the analog sensing voltage (Vsen) into a digital signal.

The sensing circuit 30 including the voltage sensing type sensing unit SU is shown in Fig.

7, the sensing circuit 30 is implemented with a voltage sensing type sensing unit (SU) including a sample and hold unit SH, a sampling switch SAMP, and an initialization switch SPRE, and an ADC.

The initialization switch SPRE connects the input terminal of the initialization voltage Vpre to the sensing line 14B. The initializing voltage Vpre is applied to the source node N2 of the pixel P through the sensing line 14B while the initialization switch SPRE is turned on.

The sampling switch SAMP connects the sample-and-hold section SH to the sensing line 14B. While the sampling switch SAMP is turned on, the sample & hold portion SH is connected to the pixel P via the sampling switch SAMP and the sensing line 14B. The sample & hold unit SH samples the pixel current Ipixel charged in a line capacitor (not shown) of the sensing line 14B to generate and supply the analog sensing voltage Vsen to the ADC. The ADC converts the analog sensing voltage (Vsen) into a digital signal.

8 is a flowchart illustrating a method of sensing an electrical characteristic of an organic light emitting display according to an embodiment of the present invention. 9 and 10 are views for explaining the leakage current value sensing operation of the non-sensing pixel of FIG. 11 and 12 are views for explaining the electric characteristic value sensing operation of the sensing pixel of FIG.

A method of sensing an electrical characteristic of an organic light emitting display according to an embodiment of the present invention is directed to a display panel having a plurality of pixels including a sensing pixel and a non-sensing pixel, wherein the plurality of pixels share one sensing line .

As shown in FIG. 8, a method of sensing an electrical characteristic of an OLED display according to the present invention includes sensing a leak current value Vsen1 of a non-sensing pixel through a shared sensing line, Sensing an electrical characteristic value of the pixel through a shared sensing line; and correcting an electrical characteristic value of the sensing pixel based on the leakage current value Vsen2 of the non-sensing pixel. Here, the step S3 of correcting the electrical characteristic value Vsen2 of the sensing pixel based on the leakage current value Vsen1 of the non-sensing pixel may include correcting a leakage current value of the non-sensing pixel in the electrical characteristic value Vsen2 of the sensing pixel (Vsen2-Vsen1) of the sensing pixel by subtracting the final sensing value (Vsen1) of the sensing pixel. The electrical characteristic value Vsen2 of the sensing pixel indicates a pixel current value flowing in the driving TFT of the sensing pixel.

The step S1 of sensing the leakage current value Vsen1 of the non-sensing pixel will be described in detail with reference to FIGS. 9 and 10. FIG. Here, it is assumed that the sensing circuit 30 is implemented as a voltage sensing type sensing unit (SU) and an ADC as shown in FIG.

The R pixel PR, the W pixel PW, the G pixel PG and the B pixel PB share one sensing line 14B and the first and second gate lines 15A and 15B. The electrical characteristics of the R pixel PR, the W pixel PW, the G pixel PG and the B pixel PB are independently sensed for each color. When a pixel of one color is to be sensed, The pixels become non-sensing objects. A pixel to be sensed is a sensing pixel, and a pixel to be non-sensing is a non-sensing pixel. Hereinafter, as an example, it is assumed that a W pixel PW is a sensing pixel, and an R pixel PR, a G pixel PG, and a B pixel PB become non-sensing pixels.

9 and 10, the process of sensing the leakage current value Vsen1 of the non-sensing pixels PR, PG, and PB includes the initialization period (1), the sensing period (2), and the sampling period (3) .

When the scan control signal SCAN of the on level ON is applied to the first gate line 15A in the initialization period ①, the first switch TFT ST1 of the pixels PR, PW, PG, ) Are simultaneously turned on. The black data voltage Vblack supplied to the data lines 14A is applied to the gate electrodes of the driving TFTs included in the pixels PR, PW, PG, PB.

In the initialization period (1), when the initialization switch SPRE is turned on, the initialization voltage Vpre is supplied to the sensing line 14B. When the sensing control signal SEN of the ON level ON is applied to the second gate line 15B in the initialization period (1), the potential of the second switch TFT (ST2) of the pixels PR, PW, ) Are simultaneously turned on. The initialization voltage Vpre supplied to the sensing line 14B is applied to the source electrodes of the respective driving TFTs included in the pixels PR, PW, PG, PB.

The difference between the black data voltage Vblack and the initializing voltage Vpre is lower than the threshold voltage of each driving TFT included in the pixels PR, PW, PG, PB. Therefore, during the initialization period (1), each driving TFT included in the pixels PR, PW, PG, PB is programmed with an OFF condition in which the pixel current can not flow. During the initialization period (1), the potential of the sensing line 14B becomes the initializing voltage Vpre.

When the scan control signal SCAN of the OFF level is applied to the first gate line 15A within the sensing period (2), the first switch TFT ST1 of the pixels PR, PW, PG, Are simultaneously turned off. Accordingly, the gate electrode of each driving TFT included in the pixels PR, PW, PG, PB is floated.

Within the sensing period (2), the sensing circuit 30 turns off the initialization switch SPRE and floats the sensing line 14B. The source electrodes of the driving TFTs included in the pixels PR, PW, PG, and PB are connected to the second switch TFT ST2, because the sensing control signal SEN maintains the ON level (ON) And is continuously connected to the sensing line 14B.

When the leakage current Ileakge flows to each driving TFT of the pixels PR, PW, PG, PB during the sensing period (2), the potential of the sensing line 14B gradually rises due to the leakage current Ileakge.

In the sampling period (3), the sensing circuit 30 turns on the sampling switch SAMP to sample the leak current value Vsen1 of the pixels PR, PW, PG, PB flowing through the sensing line 14B do. The voltage difference? V1 between the leakage current value Vsen1 and the initialization voltage Vpre is proportional to the leakage current Ileakge. The leakage current value Vsen1 includes not only the leakage current of the non-sensing pixels PR, PG and PB but also the leakage current of the sensing pixel PW. However, since the leakage current is very small, the leakage current value Vsen1 of the pixels PR, PW, PG, and PB may be regarded as the leakage current value Vsen1 of the non-sensing pixels PR, PG, and PB .

The leak current value Vsen1 of the non-sensing pixels PR, PG, PB is converted into a digital signal through the ADC and then supplied to the sensing value correction circuit.

Next, referring to FIGS. 11 and 12, step S2 of sensing the electrical characteristic value of the sensing pixel PW into which the leakage current value is mixed will be described in detail. Here, it is assumed that the sensing circuit 30 is implemented as a voltage sensing type sensing unit (SU) and an ADC as shown in FIG.

The R pixel PR, the W pixel PW, the G pixel PG and the B pixel PB share one sensing line 14B and the first and second gate lines 15A and 15B. The electrical characteristics of the R pixel PR, the W pixel PW, the G pixel PG and the B pixel PB are independently sensed for each color. When a pixel of one color is to be sensed, The pixels become non-sensing objects. A pixel to be sensed is a sensing pixel, and a pixel to be non-sensing is a non-sensing pixel. Hereinafter, as an example, it is assumed that a W pixel PW is a sensing pixel, and an R pixel PR, a G pixel PG, and a B pixel PB become non-sensing pixels.

11 and 12, the process of sensing the electrical characteristic value of the sensing pixel PW into which the leakage current value is mixed includes the initialization period (1), the sensing period (2), and the sampling period (3) Lt; / RTI >

When the scan control signal SCAN of the on level ON is applied to the first gate line 15A in the initialization period ①, the first switch TFT ST1 of the pixels PR, PW, PG, ) Are simultaneously turned on. The sensing data voltage Vdata is applied to the gate electrode of the driving TFT of the sensing pixel PW through the data line 14A and the first switch TFT ST1 and the data line 14A and the first switch The black data voltage Vblack is applied to the gate electrodes of the driving TFTs included in the non-sensing pixels PR, PG, PB via the TFT ST1.

In the initialization period (1), when the initialization switch SPRE is turned on, the initialization voltage Vpre is supplied to the sensing line 14B. When the sensing control signal SEN of the ON level ON is applied to the second gate line 15B in the initialization period (1), the potential of the second switch TFT (ST2) of the pixels PR, PW, ) Are simultaneously turned on. The initialization voltage Vpre supplied to the sensing line 14B is applied to the source electrodes of the respective driving TFTs included in the pixels PR, PW, PG, PB.

The difference between the black data voltage Vblack and the initialization voltage Vpre is lower than the threshold voltage of each driving TFT included in the pixels PR, PW, PG, PB and the sensing data voltage Vdata and the initialization voltage Vpre, Is higher than the threshold voltage of each driving TFT included in the pixels (PR, PW, PG, PB). Therefore, during the initialization period (1), the driving TFT included in the sensing pixel PW is programmed to an ON condition in which the pixel current can flow, and each driving TFT included in the non-sensing pixels PR, PG, And is programmed with an OFF condition in which current can not flow. During the initialization period (1), the potential of the sensing line 14B becomes the initializing voltage Vpre.

When the scan control signal SCAN of the OFF level is applied to the first gate line 15A within the sensing period (2), the first switch TFT ST1 of the pixels PR, PW, PG, Are simultaneously turned off. Accordingly, the gate electrode of each driving TFT included in the pixels PR, PW, PG, PB is floated.

Within the sensing period (2), the sensing circuit 30 turns off the initialization switch SPRE and floats the sensing line 14B. The source electrodes of the driving TFTs included in the pixels PR, PW, PG, and PB are connected to the second switch TFT ST2, because the sensing control signal SEN maintains the ON level (ON) And is continuously connected to the sensing line 14B.

During the sensing period (2), a pixel current Ipixel flows in the driving TFT of the sensing pixel PW. When the leakage current Ileakge flows to each driving TFT of the non-sensing pixels PR, PG and PB during the sensing period (2), the pixel current Ipixel in which the leakage current Ileakge is mixed is applied to the sensing line 14B, . During the sensing period (2), the potential of the sensing line 14B gradually rises by the pixel current Ipixel into which the leakage current Ileakge is mixed.

In the sampling period (3), the sensing circuit 30 turns on the sampling switch SAMP to turn on the pixel current Ipixel flowing in the sensing line 14B, that is, the pixel current Ipixel into which the leakage current Ileakge is mixed, . The voltage difference DELTA V2 between the electrical characteristic value Vsen2 of the sensing pixel PW in which the leakage current Ileakge is mixed, i.e., the leakage current Ileakge, and the initialization voltage Vpre is the leakage current Ileakge ) Is proportional to the pixel current (Ipixel) in which it is incorporated.

The electrical characteristic value Vsen2 of the sensing pixel PW into which the leakage current Ileakge is mixed is converted into a digital signal through the ADC and then supplied to the sensing value correction circuit. The sensing value correction circuit subtracts the leakage current value Vsen1 of the non-sensing pixels PR, PG, PB from the electrical characteristic value Vsen2 of the sensing pixel PW into which the leakage current Ileakge is incorporated, (Vsen2-Vsen1) of the target PW.

On the other hand, when the scan control signal SCAN of the on level (ON) is again applied to the first gate line 15A within the sampling period (3), the first switch SW1 of the pixels PR, PW, The TFT ST1 is simultaneously turned on. The black data voltage Vblack is applied to the gate electrode of the driving TFT of the sensing pixel PW through the data line 14A and the first switch TFT ST1 and the data line 14A and the first switch TFT The black data voltage Vblack is applied to the gate electrodes of the driving TFTs included in the non-sensing pixels PR, PG and PB through the data line ST1. By the black data voltage Vblack applied to the gate electrode, the driving TFT included in the sensing pixel PW is reset to the OFF condition where the pixel current can not flow.

As described above, according to the present invention, when a plurality of pixels share one sensing line, the leakage current of the non-sensing pixel is firstly sensed, the pixel current of the sensing pixel into which the leakage current is mixed is secondarily sensed, The result of primary sensing is subtracted from the result of secondary sensing. Accordingly, the present invention can obtain the pixel current value of the sensing pixel excluding the leakage current value, thereby greatly improving the sensing accuracy of the sensing pixel.

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

10: Display panel 11: Timing controller
12: data driving circuit 13: gate driving circuit
14A: Data line 14B: Sensing line
15A: first gate line 15B: second gate line
20: sensing value correction circuit 30: sensing circuit

Claims (12)

A display panel having a plurality of pixels including a sensing pixel and a non-sensing pixel, the plurality of pixels sharing a sensing line;
A sensing circuit connected to the shared sensing line for sensing a leakage current value of the non-sensing pixel and sensing an electrical characteristic value of the sensing pixel into which the leakage current value is mixed; And
And a sensing value correction circuit for correcting an electrical characteristic value of the sensing pixel based on a leakage current value of the non-sensing pixel. The method according to claim 1,
The sensing value correction circuit includes:
Wherein a final sensing value of the sensing pixel is calculated by subtracting a leakage current value of the non-sensing pixel from an electrical characteristic value of the sensing pixel. 3. The method of claim 2,
Wherein the electrical characteristic value of the sensing pixel is a pixel current value flowing in the driving TFT of the sensing pixel. The method of claim 3,
Further comprising a data driving circuit for generating a sensing data voltage for the pixel current and a black data voltage for interrupting the flow of the pixel current. 5. The method of claim 4,
The data driving circuit includes:
Wherein the black data voltage is applied to the gate electrode of the driving TFT included in the sensing pixel and the gate electrode of the driving TFT included in the non-sensing pixel so that the leakage current value of the non-sensing pixel is sensed. 5. The method of claim 4,
The data driving circuit includes:
The sensing data voltage is applied to the gate electrode of the driving TFT included in the sensing pixel so that the electrical characteristic value of the sensing pixel into which the leakage current value is mixed is sensed, And applies the black data voltage to the electrode. A method of sensing an electrical characteristic of an organic light emitting display having a plurality of pixels including a sensing pixel and a non-sensing pixel, wherein the plurality of pixels share one sensing line,
Sensing a leakage current value of the non-sensing pixel through a shared sensing line;
Sensing an electrical characteristic value of the sensing pixel in which the leakage current value is mixed through the shared sensing line; And
And correcting the electrical characteristic value of the sensing pixel based on the leakage current value of the non-sensing pixel. 8. The method of claim 7,
The step of correcting the electrical characteristic value of the sensing pixel based on the leakage current value of the non-
And calculating a final sensing value of the sensing pixel by subtracting the leakage current value of the non-sensing pixel from the electrical characteristic value of the sensing pixel. 9. The method of claim 8,
Wherein the electrical characteristic value of the sensing pixel is a pixel current value flowing in the driving TFT of the sensing pixel. 10. The method of claim 9,
Generating a sensing data voltage for the flow of pixel currents and a black data voltage for blocking the flow of the pixel currents. 11. The method of claim 10,
Applying the black data voltage to the gate electrode of the driving TFT included in the sensing pixel and the gate electrode of the driving TFT included in the non-sensing pixel so that the leakage current value of the non-sensing pixel is sensed A method of sensing an electrical property of an organic light emitting display. 11. The method of claim 10,
The sensing data voltage is applied to the gate electrode of the driving TFT included in the sensing pixel so that the electrical characteristic value of the sensing pixel into which the leakage current value is mixed is sensed, And applying the black data voltage to an electrode of the organic light emitting display device.

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