KR102171612B1 - Organic light emitting display device - Google Patents

Abstract

The present invention provides an organic light-emitting display device capable of shortening the sensing time of a driving transistor. The organic light-emitting display device according to the present invention includes a driving transistor for emitting an organic light-emitting element by outputting a data current based on a data voltage. A display panel including a plurality of pixels; And operating the display panel in a sensing mode or a display mode, and operating a driving transistor of each pixel in a source follow mode in the sensing mode while being connected to a sensing node between the organic light emitting element and the driving transistor. A panel driver for driving each pixel by sensing a driving characteristic value of the driving transistor for each pixel through a reference line, and correcting input data for each pixel based on a driving characteristic value of the driving transistor for each pixel in the display mode, the In the sensing mode, the panel driver may sense a driving characteristic value of the driving transistor at a short-circuit sensing time set before a voltage saturation period in which a sensing voltage according to a current flowing through the driving transistor is saturated.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY DEVICE}

The present invention relates to an organic light-emitting display device, and more particularly, to an organic light-emitting display device capable of compensating for a characteristic variation of a driving transistor for each pixel.

Recently, the importance of flat panel display devices is increasing with the development of multimedia. In response to this, flat panel displays such as a liquid crystal display device, a plasma display device, and an organic light emitting display device are commercially available. Among the flat panel display devices, the organic light emitting display device has a high response speed, low power consumption, and is self-luminous, so it is drawing attention as a next-generation flat panel display device because there is no problem in a viewing angle.

1 is a circuit diagram illustrating a pixel structure of a general organic light emitting diode display.

Referring to FIG. 1, a pixel P of a general organic light emitting display device includes a switching transistor Tsw, a driving transistor Tdr, a capacitor Cst, and an organic light emitting diode OLED.

The switching transistor Tsw is switched according to the scan pulse SP supplied to the scan line SL to supply the data voltage Vdata supplied to the data line DL to the driving transistor Tdr. The driving transistor Tdr is switched according to the data voltage Vdata supplied from the switching transistor Tsw, so that the data current Ioled flows from the driving power EVdd supplied from the driving power line to the organic light emitting diode OLED. Control. The capacitor Cst is connected between the gate terminal and the source terminal of the driving transistor Tdr to store a voltage corresponding to the data voltage Vdata supplied to the gate terminal of the driving transistor Tdr, and the driving transistor with the stored voltage. Turn on (Tdr). The organic light emitting diode OLED is electrically connected between the source terminal of the driving transistor Tdr and the cathode line EVss to emit light by the data current Ioled supplied from the driving transistor Tdr. Each pixel P of such a general organic light emitting display device uses switching of the driving transistor Tdr according to the data voltage Vdata to reduce the amount of data current Ioled flowing from the driving power EVdd to the organic light emitting diode OLED. A predetermined image is displayed by controlling the size to emit light of the organic light emitting diode (OLED).

In such a general organic light emitting display device, there is a problem in that the threshold voltage (Vth)/mobility characteristics of the driving transistor Tdr are different depending on the position of the organic light emitting display panel according to the nonuniformity of the manufacturing process of the thin film transistor. . Accordingly, in a general organic light emitting display device, even if the same data voltage Vdata is applied to the driving transistor Tdr for each pixel, there is a problem in that uniform image quality cannot be realized due to a variation in current flowing through the organic light emitting element OLED.

In order to solve this problem, the organic light emitting display device of Korean Patent Laid-Open Publication No. 10-2012-0076215 (hereinafter referred to as "prior technical literature") adds a sensor transistor to each pixel, and a switching transistor and a sensor transistor An external compensation technology for compensating the threshold voltage of the driving transistor by sensing the threshold voltage of the driving transistor through a reference line connected to the sensor transistor using the switching of is disclosed.

The organic light-emitting display device of the prior art document detects the change in the threshold voltage of the driving transistor based on the value sensed by the analog-to-digital converter by operating the driving transistor of each pixel in a source follower mode and sensing it. To compensate.

However, in the sensing method disclosed in the prior art document, the sensing voltage is saturated only after a sufficient time has elapsed due to the influence of the capacitance, and thus, in order to accurately compensate the threshold voltage of the driving transistor, when the driving transistor is turned off There is a problem in that the sensing speed is slow because the sensing time is long because it has to wait until.

The present invention has been conceived to solve the above-described problem, and it is an object of the present invention to provide an organic light emitting display device capable of shortening the sensing time of a driving transistor.

In addition, another object of the present invention is to provide an organic light emitting display device capable of compensating for a threshold voltage deviation of a driving transistor for each pixel according to a mobility deviation of the driving transistor for each pixel when a sensing time is shortened.

In addition to the technical problems of the present invention mentioned above, other features and advantages of the present invention will be described below or will be clearly understood by those of ordinary skill in the art from such technology and description.

An organic light emitting diode display according to an exemplary embodiment of the present invention includes a display panel including a plurality of pixels including a driving transistor configured to emit light of an organic light emitting element by outputting a data current based on a data voltage; And operating the display panel in a sensing mode or a display mode, and operating a driving transistor of each pixel in a source follow mode in the sensing mode while being connected to a sensing node between the organic light emitting element and the driving transistor. A panel driver for driving each pixel by sensing a driving characteristic value of the driving transistor for each pixel through a reference line, and correcting input data for each pixel based on a driving characteristic value of the driving transistor for each pixel in the display mode, the In the sensing mode, the panel driver may sense a driving characteristic value of the driving transistor at a short-circuit sensing time set before a voltage saturation period in which a sensing voltage according to a current flowing through the driving transistor is saturated.

The driving characteristic value of the driving transistor is composed of a threshold voltage sensing value and a mobility sensing value of the driving transistor, and in the display mode, the panel driver includes a threshold voltage sensing value of the driving transistor for each pixel sensed at the short axis sensing time. Based on the mobility sensing value, a threshold voltage predicted value of the driving transistor for each pixel corresponding to the voltage saturation period is calculated, and input data for each pixel is corrected based on the calculated threshold voltage predicted value of the driving transistor for each pixel. You can drive the pixels.

The organic light emitting diode display further includes a memory unit storing a threshold voltage sensing value and a mobility sensing value for a driving transistor for each pixel sensed by the sensing mode, and coefficients for each mobility sensing value for a threshold voltage prediction function. In the display mode, the panel driver extracts coefficients of a threshold voltage prediction function corresponding to a mobility sensing value of the driving transistor for each pixel from the memory unit, and extracts coefficients for each pixel and a threshold of the driving transistor for each pixel. The threshold voltage predicted value of the driving transistor for each pixel may be calculated by calculating the threshold voltage predicting function using a voltage sensing value.

The threshold voltage prediction function is based on a first threshold voltage sensing value of the driving transistor for each pixel sensed at the short-circuit sensing time and a second threshold voltage sensing value of the driving transistor for each pixel sensed in the voltage saturation period, and sensing the mobility. It may be a linear function set based on a first function for each mobility sensing value calculated by coordinated with a second threshold voltage sensing value with respect to the first threshold voltage sensing value for each value and linearly interpolated.

The linear coefficient of the threshold voltage prediction function is composed of a second function calculated by coordinating the first-order coefficients of the first functions for each mobility sensing value and linear interpolation, and the threshold voltage prediction function The zero-order coefficient is composed of a third function calculated by coordinating the zero-order coefficients of the first functions for each mobility sensing value and linear interpolation with respect to the mobility sensing value, and the threshold voltage prediction function stored in the memory unit The coefficients of may be linear and zero-order coefficients of the second function, and linear and zero-order coefficients of the third function.

In the display mode, the panel driver includes a linear coefficient and a zero-order coefficient of the second function corresponding to a mobility sensing value of the driving transistor for each pixel in the memory unit, and a linear coefficient and a zero-order coefficient of the third function. Extracting coefficients; The second and third functions using the extracted linear and zero-order coefficients of the second function, the extracted linear and zero-order coefficients of the third function, and a mobility sensing value of the driving transistor for each pixel Calculating a first-order coefficient and a zero-order coefficient of the threshold voltage prediction function through each operation; The threshold of the driving transistor for each pixel through the calculation of the threshold voltage prediction function using the calculated first and zero order coefficients of the calculated threshold voltage prediction function and a threshold voltage sensing value of the driving transistor for each pixel sensed at the short axis sensing time. The voltage predicted value can be calculated.

In the display mode, the panel driver calculates a characteristic compensation value for each pixel based on a deviation between the predicted threshold voltage of the driving transistor for each pixel and the initial threshold voltage predicted value of the driving transistor for each pixel stored in the memory unit, and calculates Each pixel may be driven by correcting input data of a corresponding pixel according to the determined characteristic compensation value for each pixel.

The driving characteristic value of the driving transistor is composed of a threshold voltage value and a mobility value of the driving transistor, and in the sensing mode, the panel driver moves a movement set for each pixel-specific driving transistor mobility sensing value and a sensing reference data voltage. Based on the degree coefficient, a sensing data voltage for each pixel is generated, and the driving transistor of each pixel is operated in a source follower mode by using the sensing data voltage for each pixel, so that the threshold voltage and mobility of the driving transistor for each pixel By sensing each, a threshold voltage sensing value and a mobility sensing value of the driving transistor for each pixel may be generated.

The organic light emitting diode display further includes a memory unit storing a threshold voltage sensing value and a mobility sensing value for a driving transistor for each pixel sensed by the sensing mode, and a mobility coefficient for each sensing reference data voltage, wherein the In the sensing mode, the panel driver compensates the mobility according to the mobility sensing value of the driving transistor for each pixel based on the mobility sensing value of the driving transistor for each pixel stored in the memory unit and the mobility coefficient for each voltage of the sensing reference data. A gain value may be calculated, and the sensing data voltage for each pixel may be generated using the sensing reference pixel data and the mobility compensation gain value.

In the sensing mode, the panel driver calculates an average mobility value based on a mobility sensing value of a driving transistor for each pixel stored in the memory unit, and calculates the average mobility value and a mobility sensing value of the driving transistor. A mobility compensation value may be calculated using the mobility compensation value and a mobility compensation gain value may be calculated using the mobility compensation value and the mobility coefficient.

In the display mode, the panel driver calculates a characteristic compensation value for each pixel based on a deviation between a threshold voltage sensing value of the driving transistor for each pixel stored in the memory unit and an initial threshold voltage sensing value for the driving transistor for each pixel, and calculates Each pixel may be driven by correcting input data of a corresponding pixel according to the determined characteristic compensation value for each pixel.

According to the means for solving the above problem, the present invention can shorten the sensing time of the driving transistor for each pixel by sensing the threshold voltage at the shortened sensing time set before the voltage saturation period of the sensing voltage.

In addition, the present invention predicts the threshold voltage of the voltage saturation section from the threshold voltage sensed at the short-circuit sensing time and compensates for the threshold voltage of the driving transistor for each pixel, thereby reducing the mobility deviation of the driving transistor for each pixel caused by shortening the sensing time. Compensation, and through this, the luminance uniformity of the display panel can be improved.

In addition, the present invention generates a sensing data voltage for each pixel based on a mobility sensing value of a driving transistor for each pixel and senses a threshold voltage at a shortened sensing time, thereby shortening the sensing time of the driving transistor for each pixel and shortening the sensing time. It is possible to compensate for the mobility deviation of the driving transistor for each pixel, and thereby improve the luminance uniformity of the display panel.

1 is a circuit diagram illustrating a pixel structure of a general organic light emitting diode display.
2 is a diagram illustrating an organic light emitting display device according to the present invention.
3 is a diagram illustrating a sensing voltage waveform and a short-axis sensing time point in a sensing mode of the organic light emitting diode display according to the first example of the present invention.
FIG. 4 is a diagram illustrating a sensing voltage waveform and a short-axis sensing time point in a sensing mode of an organic light emitting diode display according to a second example of the present invention.
5 is a diagram illustrating a configuration of an organic light emitting display device according to a first example of the present invention.
6 is a circuit diagram illustrating the pixel structure shown in FIG. 5.
7 is a block diagram illustrating a column driver shown in FIG. 5.
8 is a driving waveform diagram in a sensing mode in the organic light emitting diode display according to the first example of the present invention.
9 is a driving waveform diagram in a display mode in the organic light emitting display device according to the first example of the present invention.
10 is a graph for explaining luminance uniformity of a display panel for the present invention and Comparative Examples 1 and 2;
11 is a diagram illustrating a configuration of an organic light emitting diode display according to a second example of the present invention.
12 is a graph showing a current flowing through a driving transistor versus a data voltage in the present invention and a comparative example.

The meaning of the terms described in this specification should be understood as follows.

Singular expressions should be understood as including plural expressions unless clearly defined differently in context, and terms such as "first" and "second" are used to distinguish one element from other elements, The scope of rights should not be limited by these terms. It is to be understood that terms such as "comprise" or "have" do not preclude the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof. The term “at least one” is to be understood as including all possible combinations from one or more related items. For example, the meaning of “at least one of the first item, the second item, and the third item” means 2 among the first item, the second item, and the third item as well as each of the first item, the second item, or the third item. It means a combination of all items that can be presented from more than one.

Hereinafter, exemplary embodiments of the organic light emitting display device according to the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to elements of each drawing, the same elements may have the same numerals as possible even if they are indicated on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof may be omitted.

2 is a diagram illustrating an organic light emitting display device according to the present invention.

Referring to FIG. 2, an organic light-emitting display device according to an exemplary embodiment of the present invention includes a display panel 100, a panel driver 200, and a memory unit 300.

The display panel 100 may include a plurality of pixels P including driving transistors that emit light of an organic light-emitting device by outputting a data current based on a data voltage.

The panel driver 200 drives the display panel 100 in a display mode or a sensing mode. Here, the display mode refers to driving of the display panel 100 to display a predetermined image by emitting an organic light emitting element included in each pixel P according to input data, and the sensing mode is a driving transistor for each pixel It means driving of the display panel 100 to sense the threshold voltage and/or mobility of. For example, the sensing mode may be performed when a user (or product) is set before product shipment of the organic light emitting display device, and may be performed at a user setting or a set period after product shipment of the organic light emitting display device. Here, the set period may be a power-on period of the organic light-emitting display device, a power-off period of the organic light-emitting display device, a power-on period after a set driving time, or a power-off period after a set driving time.

In the sensing mode, the panel driver 200 according to the first example operates the driving transistors of each pixel in a source follower mode while operating the driving transistor of each pixel through a reference line connected to a sensing node between the organic light emitting device and the driving transistor. The voltage of the sensing node is sensed, but the voltage of the sensing node is sensed at the shortened sensing point (or any point at which the voltage of the sensing node increases) set before the voltage saturation period when the voltage of the sensing node is saturated. Each pixel P is driven by generating a driving characteristic value and correcting input data for each pixel based on a driving characteristic value of a driving transistor for each pixel in the display mode.

For example, in the sensing mode, the panel driver 200 according to the first example uses a sensing node as a source electrode of a driving transistor as a precharging voltage Vpre having a constant voltage level, as shown in FIG. 3. After initialization, a shortened sensing point set before the saturation point (Tsat) when the sensing voltage according to the current flowing through the driving transistor operating in the source follower mode is saturated while supplying the sensing data voltage (Vdata_sen) to the gate electrode of the driving transistor The voltage of the sensing node is sensed at (Tsen). That is, since the sensing voltage is saturated after a sufficient time has elapsed after initialization due to the influence of the capacitance, the sensing time is lengthened because it is necessary to wait until the driving transistor is turned off, but the panel driver 200 according to the first example A shortens the sensing time of the sensing mode by sensing the sensing voltage at the shortened sensing time Tsen set before the voltage saturation period Tsat in which the sensing voltage of the sensing node is saturated.

In the display mode, the panel driver 200 according to the first example includes a voltage saturation period based on a driving characteristic value of a driving transistor for each pixel sensed at a short-axis sensing time Tsen, that is, a threshold voltage sensing value and a mobility sensing value. Each pixel P is driven by calculating a threshold voltage prediction value of the driving transistor for each pixel of (Tsat), correcting input data for each pixel according to the calculated threshold voltage prediction value of the driving transistor for each pixel.

For example, the panel driver 200 according to the first example extracts coefficients of a threshold voltage prediction function corresponding to a mobility sensing value of a driving transistor for each pixel from the memory unit 300, and extracts coefficients for each pixel and A threshold voltage prediction value of the driving transistor for each pixel may be calculated by calculating a threshold voltage prediction function using the sensing value of the threshold voltage of the driving transistor for each pixel.

In the memory unit 300, coefficients for calculating a threshold voltage prediction function in the panel driver 200 according to the first example are stored for each mobility sensing value of the driving transistor. The threshold voltage prediction function may be formed of a linear function as shown in Equation 1 below.

The coefficients (A, B, C, D) for the operation (Vth'_sat) of the threshold voltage prediction function may be calculated through the following process and stored in the memory unit 300. In conjunction with 1, it will be described in detail as follows.

First, the mobility of the driving transistor for each pixel is sensed through the above-described sensing mode, and a mobility sensing value of the driving transistor for each pixel is calculated. Additionally, a mobility map for the display panel 100 may be generated based on the mobility sensing value for each pixel.

Then, through the above-described sensing mode, the threshold voltage of the driving transistor for each pixel is sensed at the short-circuit sensing time Tsen to calculate a first threshold voltage sensing value of the driving transistor for each pixel. Additionally, a first threshold voltage map for the display panel 100 may be generated based on the first threshold voltage sensing value for each pixel.

Then, through the above-described sensing mode, the threshold voltage of the driving transistor for each pixel is sensed in the voltage saturation period Tsat, and a second threshold voltage sensing value of the driving transistor for each pixel is calculated. Additionally, a second threshold voltage map for the display panel 100 may be generated based on the second threshold voltage sensing value for each pixel.

Then, pixels P having the same mobility sensing value in the display panel 100 are extracted using the calculated mobility sensing value for each pixel.

Then, the first threshold voltage sensing values and the second threshold voltage sensing values of the pixels P extracted for each mobility sensing value are plotted as a second threshold voltage sensing value with respect to the first threshold voltage sensing value. Then, linear interpolation is performed to calculate a first function for each mobility sensing value.

Then, a linear term coefficient is extracted from the first function for each mobility sensing value, and the extracted linear term coefficients for each mobility sensing value are coordinated with respect to the mobility sensing value (α_sen), and a second function (M) is obtained by linear interpolation. Calculate.

Then, the zero-order coefficient (or constant) is extracted from each of the first functions for each mobility sensing value, and the extracted zero-order coefficients for each mobility sensing value are coordinated with respect to the mobility sensing value (α_sen), followed by linear interpolation. Calculate the function (N).

Then, the first-order coefficient (A) and the zero-order coefficient (B) from the second function (M), and the first-order coefficient (C) and the zero-order coefficient (D) from the third function (N) are extracted. And stored in the memory unit 300.

The coefficients A, B, C, and D for the operation (Vth'_sat) of the threshold voltage prediction function as described above are the first of the driving transistors for each pixel sensed at the shortened sensing time Tsen for each mobility sensing value. By calculating based on the threshold voltage sensing value and the second threshold voltage sensing value of the driving transistor for each pixel sensed in the voltage saturation period Tsat, the panel driver 200 according to the first example is a mobility sensing value of the driving transistor for each pixel. The short-axis sensing time point through the calculation of the threshold voltage sensing value (Vth_sen) of (α_sen) and the short-circuit sensing point Tsen and the threshold voltage prediction function (Vth'_sat) using the coefficients (A, B, C, D) From the threshold voltage sensing value Vth_sen of (Tsen), the predicted threshold voltage value Vth'_sat of the voltage saturation period Tsat is calculated.

In the display mode, the panel driver 200 according to the first example is sensed by the first sensing mode and the threshold voltage predicted value of the driving transistor for each pixel calculated through the operation of Equation 1 A pixel-specific characteristic compensation value for compensating for a change in the threshold voltage of the driving transistor for each pixel is calculated based on the deviation between the stored initial threshold voltage predicted values of the driving transistor for each pixel, and then the corresponding pixel ( Each pixel P is driven by correcting the input data of P) to generate correction data for each pixel.

As described above, the panel driver 200 according to the first example predicts the threshold voltage of the voltage saturation period Tsat from the threshold voltage sensing value Vth_sen and the mobility sensing value α_sen sensed at the short axis sensing time Tsen. Accordingly, the sensing time of the driving transistor for each pixel is shortened, and a deviation of the threshold voltage of the driving transistor for each pixel is compensated according to the mobility deviation of the driving transistor for each pixel due to the shortening of the sensing time.

The panel driver 200 according to the second example is configured for each pixel based on a mobility sensing value of a driving transistor for each pixel stored in the memory unit 300 and a mobility coefficient corresponding to a sensing reference data voltage in the sensing mode. A mobility compensation gain value is calculated to generate a sensing data voltage for each pixel, and as shown in FIG. 4, the driving transistor of each pixel is set to a source follower mode using the sensing data voltage Vdata'_sen for each pixel. The memory unit 300 senses the voltage of the sensing node through the reference line at the short-circuit sensing time Tsen and generates a driving characteristic value of the driving transistor for each pixel, that is, a threshold voltage sensing value and a mobility sensing value. Save it to. That is, in the sensing mode, the panel driver 200 generates the sensing pixel data DATA for each pixel through the calculation of Equation 2 below, and corresponds to the generated sensing pixel data DATA for each pixel. Each pixel P may be driven in a sensing mode by using the sensing data voltage Vdata'_sen for each pixel.

Hereinafter, a process in which the panel driver 200 according to the second example generates the sensing pixel data DATA for each pixel through the operation of Equation 2 will be described in detail as follows.

First, the memory unit 300 includes a threshold voltage sensing value and a mobility sensing value (α _sen ) of a driving transistor for each pixel sensed by a previous sensing mode, and a mobility for each sensing reference data voltage set by a prior experiment. The coefficient α _coe is stored.

The panel driver 200 according to the second example extracts a mobility sensing value α _sen of a driving transistor for each pixel and a mobility coefficient α _coe for each sensing reference data voltage from the memory unit 300.

Thereafter, the panel driver 200 according to the second example includes a mobility sensing value α _sen of all pixels P of the display panel 100 based on the extracted mobility sensing value α _sen . The average mobility value (α _avg ) is calculated, the average mobility value (α _avg ) is divided by the pixel-specific mobility sensing value (α _sen ), and the resulting value is calculated to the power of 1/2 _{Compute the} compensation value (α _comp ).

Then, the panel driving unit 200 according to the second example subtracts 1 from the mobility compensation value α _comp , multiplies the result value by the mobility coefficient α _coe , and calculates the result by multiplying the result value. By adding 1, the mobility compensation gain (α _gain ) is calculated for each pixel.

Then, the panel driver 200 according to the second example multiplies the mobility compensation gain value α _gain for each pixel and the sensing reference pixel data DATA_ref corresponding to the set sensing reference data voltage, The sensing pixel data DATA is generated, and a sensing data voltage Vdata'_sen for each pixel corresponding to the sensing pixel data DATA for each pixel is generated.

Meanwhile, a process of calculating the mobility coefficient α _coe for each voltage of the sensing reference data stored in the memory unit 300 is as follows.

First, a data voltage for sensing for each pixel corresponding to the sensing pixel data DATA for each pixel according to the operation of Equation 2 is generated using a mobility coefficient α _coe between 0 and 1. By performing the sensing mode using the credit data voltage, the slope of the sensing voltage for the mobility sensing value α _sen is calculated for each sensing reference data voltage.

In addition, a mobility coefficient α _coe corresponding to a mobility sensing value αsen equal to 0 (zero) is extracted from the slope of the sensing voltage relative to the mobility sensing value α _sen for each sensing reference data voltage, and the memory It is stored in the unit 300.

Accordingly, the mobility coefficient α _coe of each pixel is individually stored in the memory unit 300 for each sensing reference data voltage. As such, the mobility coefficient α _coe for each pixel compensates for the mobility deviation α_high and α_low of the driving transistor Tdr for each pixel occurring at the short sensing time Tsen of the sensing mode due to the shortening of the sensing time. It is used to generate the sensing data voltage Vdata'_sen for each pixel.

In the display mode, the panel driver 200 according to the second example is configured for each pixel based on a difference between the threshold voltage sensing value of the driving transistor for each pixel stored in the memory unit 300 and the initial threshold voltage sensing value of the driving transistor for each pixel. After calculating a pixel-specific characteristic compensation value for compensating for a change in the threshold voltage of the driving transistor, the input data of the corresponding pixel P is corrected according to the calculated characteristic compensation value for each pixel to generate correction data for each pixel. Drive P).

As described above, the panel driver 200 according to the second example uses the sensing data voltage Vdata'_sen for each pixel based on the mobility sensing value α _sen of the driving transistor for each pixel before the voltage saturation period Tsat. By sensing the threshold voltage and mobility of the driving transistors for each pixel at the shortened sensing time (Tsen) set in, the sensing time of the driving transistors for each pixel is shortened while the sensing time is shortened. Compensates for the threshold voltage deviation of the driving transistor.

Hereinafter, a configuration of an organic light emitting display device including a panel driver according to a first example of the present invention described above will be described with reference to FIGS. 5 to 9.

5 is a diagram illustrating a configuration of an organic light emitting diode display according to a first example of the present invention, and FIG. 6 is a circuit diagram illustrating a pixel structure illustrated in FIG. 5.

Referring to FIGS. 5 and 6, the organic light emitting display device according to the first example of the present invention includes a display panel 100, a panel driver 200, and a memory unit 300 as described above.

The display panel 100 includes first to mth (where m is a natural number) scan control lines SL1 to SLm, first to mth sensing control lines SSL1 to SSLm, and first to nth (but, n is a natural number greater than m) data lines DL1 to DLn, first to nth reference lines RL1 to RLn, first to nth driving power lines PL1 to PLn, a cathode electrode (not shown), and It includes a plurality of pixels P.

Each of the first to mth scan control lines SL1 to SLm is formed in parallel at regular intervals along a first direction, that is, a horizontal direction of the display panel 100.

Each of the first to mth sensing control lines SSL1 to SSLm is formed at regular intervals in parallel with each of the scan control lines SL1 to SLm.

The first to nth data lines DL1 to DLn are in a second direction of the display panel 100 so as to cross each of the scan control lines SL1 to SLm and the sensing control lines SSL1 to SSLm, that is, They are formed side by side at regular intervals along the vertical direction.

Each of the first to nth reference lines RL1 to RLn is formed at regular intervals in parallel with each of the data lines L1 to DLn.

Each of the first to nth driving power lines PL1 to PLn is formed at regular intervals in parallel with each of the data lines DL1 to DLn. Each of the first to nth driving power lines PL1 to PLn may be commonly connected to a driving power common line CPL formed in an upper and/or lower non-display area of the display panel 100. Optionally, each of the first to nth driving power lines PL1 to PLn may be formed at regular intervals in parallel with each of the scan control lines SL1 to SLm, and in this case, the driving power common line ( CPL) may be formed in the left and/or right non-display area of the display panel 100.

The cathode electrode may be formed in a cylindrical shape on the entire surface of the display panel 100 or may be formed in a line shape parallel to each of the data lines DL1 to DLn or the scan control lines SL1 to SLm. have.

Each of the plurality of sub-pixels P is defined by each of the first to m-th scan control lines SL1 to SLm and each of the first to n-th data lines DL1 to DLn intersecting each other. Is formed. Here, each of the plurality of sub-pixels P may be any one of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. One unit pixel displaying one image may include an adjacent red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel, or may include a red pixel, a green pixel, and a blue pixel.

Each of the plurality of pixels P may include a first switching transistor Tsw1, a second switching transistor Tsw2, a driving transistor Tdr, a capacitor Cst, and an organic light emitting diode OLED. Here, the transistors Tsw1, Tsw2, and Tdr are thin film transistors TFT, and may be a-Si TFT, poly-Si TFT, oxide TFT, or organic TFT.

The first switching transistor Tsw1 is switched by a first scan pulse SP1 to output a data voltage Vdata supplied to the data line DL. To this end, the first switching transistor Tsw1 includes a gate electrode connected to an adjacent scan control line SCL, a first electrode connected to an adjacent data line DL, and a first node that is a gate electrode of the driving transistor Tdr. and a second electrode connected to (n1). Here, the first and second electrodes of the first switching transistor Tsw1 may be a source electrode or a drain electrode according to a current direction.

The second switching transistor Tsw2 is switched by a second scan pulse SP2 to apply a voltage Vref or Vpre supplied to the reference line RL to a second node n2 that is a source electrode of the driving transistor Tdr. (Or the sensing node). To this end, the second switching transistor Tsw2 includes a gate electrode connected to an adjacent sensing control line SSL, a first electrode connected to an adjacent reference line RL, and a second electrode connected to a second node n2. do. Here, the first and second electrodes of the second switching transistor Tsw2 may be a source electrode or a drain electrode according to a current direction.

The capacitor Cst includes first and second electrodes connected between the gate electrode and the source electrode of the driving transistor Tdr, that is, between the first and second nodes n1 and n2. The first electrode of the capacitor Cst is connected to the first node n1, and the second electrode of the capacitor Cst is connected to the second node n2. The capacitor Cst charges a voltage difference between the voltages supplied to each of the first and second nodes n1 and n2 according to the switching of the first and second switching transistors Tsw1 and Tsw2, and then The driving transistor Tdr is switched according to the set voltage.

The driving transistor Tdr is turned on by the voltage of the capacitor Cst to control the amount of current flowing from the driving voltage line PL to the organic light emitting diode OLED. To this end, the driving transistor Tdr includes a gate electrode connected to the first node n1, a source electrode connected to the second node n2, and a drain electrode connected to the driving voltage line PL.

The organic light emitting diode OLED emits light by the data current Ioled supplied from the driving transistor Tdr to emit monochromatic light having a luminance corresponding to the data current Ioled. To this end, the organic light-emitting device OLED includes a first electrode (eg, an anode electrode) connected to the second node n2, an organic layer (not shown) formed on the first electrode, and a second electrode connected to the organic layer. It includes an electrode (eg, a cathode electrode). In this case, the organic layer may be formed to have a structure of a hole transport layer/organic emission layer/electron transport layer or a hole injection layer/hole transport layer/organic emission layer/electron transport layer/electron injection layer. Furthermore, the organic layer may further include a functional layer for improving the luminous efficiency and/or lifespan of the organic emission layer. In addition, the second electrode may be individually connected to each of the plurality of pixels P or may be commonly connected to the plurality of pixels P, and low potential power EVss is supplied to the second electrode.

The panel driver 200 drives the display panel 100 in a sensing mode or a display mode. In the sensing mode, the panel driver 200 operates the driving transistor Tdr of each pixel P in a source follower mode, and the sensing node n2 through the second switching transistor Tsw2 at the short axis sensing time point. The voltage of the sensing node n2 is sensed through the reference line RL connected to the memory unit by generating each of the threshold voltage sensing value Vth_sen and the mobility sensing value α_sen of the driving transistor Tdr for each pixel. 300). In the display mode, the panel driver 200 calculates a threshold voltage sensing value Vth_sen and a mobility sensing value α_sen for each pixel stored in the memory unit 300 and the threshold voltage prediction function (Vth A predicted threshold voltage value of the driving transistor Tdr for each pixel in the voltage saturation period is calculated through the calculation of Equation 1 using coefficients A, B, C, D for'_sat), and the calculated pixel The input data Idata for each pixel is corrected according to the predicted threshold voltage of the star driving transistor Tdr to emit light of the organic light emitting diode OLED of each pixel P. To this end, the panel driving unit 200 includes a timing controller 210, a row driving unit 220, and a column driving unit 230.

The timing control unit 210 senses the threshold voltage and mobility of the driving transistor Tdr for each pixel at each set or set period by a user, according to a sensing mode, the row driving unit 220 and the column. ) Operate the driving unit 230 in the sensing mode. For example, in the sensing mode, the timing control unit 210 includes first and second row control signals RCS1 and RCS2 and pixels for operating the driving transistor Tdr of each pixel P in a source follower mode. Pixel data DATA for star sensing and a data control signal DCS may be generated. In the sensing mode, the timing controller 210 includes a sensing bias voltage Vdata_Sen for each pixel and a threshold voltage V_Vth of the driving transistor Tdr for each pixel provided from the column driver 230 Based on the mobility value V_α, the threshold voltage sensing value Vth_sen and the mobility sensing value α_sen of the driving transistor Tdr for each pixel are generated and stored in the memory unit 300.

The timing controller 210 operates the row driver 220 and the column driver 230 in a display mode according to a display mode for displaying an image on the display panel 110. For example, the timing controller 210 is used for calculating a threshold voltage sensing value (Vth_sen) and a mobility sensing value (α_sen) for each pixel in the memory unit 300 and the threshold voltage prediction function (Vth'_sat). Extracting the coefficients A, B, C, D, and calculating the predicted threshold voltage of the driving transistor Tdr for each pixel in the voltage saturation period through the operation of Equation 1, and the calculated driving for each pixel. The input data Idata for each pixel is corrected according to the predicted threshold voltage of the transistor Tdr, and correction data DATA for each pixel is generated and provided to the column driver 230. In addition, the timing controller 210 includes first and second row control signals RCS1 and RCS2 and a data control signal DCS for emitting the organic light emitting device OLED of each pixel P according to a display mode. To control the driving of the row driving unit 220 and the column driving unit 230.

The row driver 220 sequentially generates a first scan pulse SP1 based on a first row control signal RCS1 supplied from the timing controller 210 to control the first to mth scans. It is sequentially supplied to the lines SL1 to SLm. In addition, the row driver 220 sequentially generates a second scan pulse SP2 based on a second row control signal RCS2 supplied from the timing controller 210, and the first to m-th It is sequentially supplied to the sensing control lines SSL1 to SSLm. Here, each of the row control signals RCS1 and RCS2 may include a start signal and a plurality of clock signals. The row driver 220 according to an example includes a scan line driver 222 and a sensing line driver 224.

The scan line driver 222 is connected to one side and/or the other side of each of the first to mth scan control lines SL1 to SLm. The scan line driver 222 generates a first scan signal that is sequentially shifted based on the first row control signal RCS1, and generates the first scan signal by using the high voltage and the low voltage. The level is shifted with a scan pulse SP1 and sequentially supplied to the first to mth scan control lines SL1 to SLm.

The sensing line driver 224 is connected to one side and/or the other side of each of the first to mth sensing control lines SSL1 to SSLm. The sensing line driver 224 generates a second scan signal that is sequentially shifted based on the second row control signal RCS2, and generates the second scan signal by using the high voltage and the low voltage. The level is shifted with 2 scan pulses SP2 and sequentially supplied to the first to mth scan control lines SL1 to SLm.

The column driver 230 is connected to the first to nth data lines DL1 to DLn and operates in a display mode and a sensing mode according to a mode control of the timing controller 210.

In the display mode, the column driver 230 provides a data voltage Vdata in units of horizontal lines based on the correction data DATA for each pixel and a data control signal DCS supplied from the timing controller 210. Is supplied to the data lines DL1 to DLn and the reference voltage Vref is supplied to the reference lines RL1 to RLn. In the sensing mode, the column driver 230 includes a driving transistor Tdr for each pixel based on the sensing pixel data DATA for each pixel and a data control signal DCS supplied from the timing controller 210. The threshold voltage and mobility of are sensed to provide the threshold voltage value V_Vth and the mobility value V_α of the driving transistor Tdr for each pixel to the timing controller 210. To this end, the column driver 150 includes a data driver 232, a switching unit 234, and a sensing unit 236, as shown in FIG. 7.

In response to the data control signal DCS supplied from the timing controller 210 according to the display mode, the data driver 232 converts the correction data DATA for each pixel supplied from the timing controller 210 into a data voltage. It is converted into (Vdata) and supplied to the first to nth data lines DL1 to DLn, respectively. In addition, the data driver 232 responds to the data control signal DCS supplied from the timing controller 210 according to the sensing mode, and the sensing pixel data DATA for each pixel supplied from the timing controller 210 ) Is converted into a sensing bias voltage Vdata_Sen and supplied to the first to nth data lines DL1 to DLn, respectively.

In response to the data control signal DCS supplied from the timing controller 210 according to the display mode, the switching unit 234 applies the reference voltage Vref supplied from the outside to the first to nth reference lines RL1 To RLn) respectively. In addition, the switching unit 234 applies a precharging voltage Vpre supplied from the outside in response to a precharging switch signal supplied from the timing control unit 210 according to the sensing mode. To RLn) to initialize each of the first to nth reference lines RL1 to RLn to a precharging voltage Vpre, and then to each of the first to nth reference lines RL1 to RLn in response to a sampling switch signal Is connected to the sensing unit 236. To this end, the switching unit 234 according to an example includes first to nth reference lines RL1 to RLn, respectively, and first to nth selectors 234a to 234n connected to the sensing unit 236. The selector 234a to 234n may be formed of a multiplexer.

The sensing unit 236 is connected to the first to nth reference lines RL1 to RLn through the switching unit 234 in the sensing mode to supply voltages of each of the first to nth reference lines RL1 to RLn. After sensing, a threshold voltage value V_Vth and a mobility value V_α corresponding to the sensed voltage are generated and provided to the timing controller 210. To this end, the sensing unit 236 includes first to nth analog-to-digital converters 236a to 236n connected to the first to nth reference lines RL1 to RLn through the switching unit 234. Can be configured.

8 is a driving waveform diagram in a sensing mode in the organic light emitting diode display according to the first example of the present invention.

A sensing mode of an organic light emitting diode display according to a first example of the present invention will be described with reference to FIGS. 5 to 8.

First, the organic light emitting diode display according to the first example of the present invention senses a threshold voltage of the driving transistor Tdr by operating the driving transistor Tdr included in the pixel P in a source follower mode. To this end, the timing controller 210 includes a data control signal DCS for driving the pixel P in the first to third periods t1, t2, and t3, the first and second row control signals RCS1, and RCS2) is generated and supplied to the row driver 220 and the column driver 230, and at the same time, sensing data DATA, which is a bias voltage supplied to the gate electrode of the driving transistor Tdr, is generated. It is supplied to the column driver 230.

In addition, the row driver 220 linearly drives each of the first and second switching transistors Tsw1 and Tsw2 during the sensing mode in response to the first and second row control signals RCS1 and RCS2. In order to operate in the mode, the first and second scan pulses SP1 and SP2 are generated at the same voltage level and supplied to each of the scan control line SL and the sensing control line SSL.

In addition, the data driver 232 of the column driver 230 converts the sensing pixel data DATA for each pixel into a sensing bias voltage Vdata_Sen in response to the data control signal DCS. It is supplied to the data line DL during the first to third periods t1, t2, and t3. At the same time, the switching unit 234 of the column driver 230 applies a precharging voltage Vpre to the reference line RL during the first period t1 in response to a precharging switch signal S_pre. After supplying, the reference line RL is floated during the second period t2, and then the reference line RL is applied during the third period t3 in response to a sampling switch signal S_sam. It is connected to the sensing unit 236. Accordingly, the sensing unit 236 senses the voltage of the reference line RL at the shortened sensing time Tsen set in the third period t3, converts the sensed voltage to analog-digital, and drives each pixel. The threshold voltage value V_Vth of the transistor Tdr is generated and provided to the timing controller 210.

In such a sensing mode, the pixel P operation of each of the first to third periods t1, t2, and t3 according to the driving of the row driver 220 and the column driver 230 is performed. It is as follows.

First, in the first period t1, the first switching transistor Tsw1 is turned on by the first scan pulse SP1 of a high voltage, and the sensing bias voltage Vdata is supplied to the data line DL. The second switching transistor Tsw2 is turned on by a second scan pulse SP2 of a high voltage, supplied to the gate electrode of the driving transistor Tdr, and the precharging voltage Vpre supplied to the reference line RL. ) Is supplied to the sensing node n2. In this case, the sensing bias voltage Vdata has a level of a target voltage set to sense the threshold voltage of the driving transistor Tdr. Accordingly, during the first period t1, the sensing node n2 that is the source electrode of the driving transistor Tdr and the reference line RL are initialized to the precharging voltage Vpre.

Then, in the second period t2, since the turn-on state of the first switching transistor Tsw1 is maintained by the first scan pulse SP1 of a high voltage, the gate voltage of the driving transistor Tdr is used for sensing. It is fixed to the bias voltage (Vdata). At this time, the reference line RL is in a floating state by the switching unit 234 of the column driving unit 230. Accordingly, the driving transistor Tdr operates in a saturation driving mode by the sensing bias voltage Vdata supplied to the gate electrode, whereby the voltage corresponding to the current flowing through the driving transistor Tdr is Due to the influence of capacitance, the floating reference line RL is gradually charged.

Then, in the third period T3, each of the first and second switching transistors Tsw1 and Tsw2 is maintained in a turned-on state, and the voltage on the sensing node is saturated before the voltage saturation period Tsat. The reference line RL is connected to the sensing unit 236 through the switching unit 234 of the column driving unit 230 by a sampling switch signal S_sam generated at a set shortened sensing time point Tsat. do. Accordingly, the sensing unit 236 senses the voltage Vsense of the reference line RL, analog-to-digital converts the sensed voltage Vsense to obtain a threshold voltage V_Vth of the driving transistor Tdr. It is generated and provided to the timing control unit 210. Accordingly, the timing control unit 210 includes a driving transistor for each pixel based on the bias voltage Vdata for sensing for each pixel and a threshold voltage V_Vth of the driving transistor Tdr for each pixel provided from the sensing unit 236. The threshold voltage sensing value Vth_sen of Tdr) is calculated and stored in the memory unit 300. In this case, the threshold voltage sensing value Vth_sen of the driving transistor Tdr may be a voltage Vdata-V_Vth obtained by subtracting the threshold voltage value V_Vth from the sensing bias voltage Vdata.

Meanwhile, the timing controller 210 calculates the threshold voltage sensing value Vth_sen of the driving transistor Tdr for each pixel through the sensing mode as described above, stores it in the memory unit 300, and then stores the driving transistor Tdr for each pixel. The sensing mode is performed again to sense the mobility. In this case, the timing controller 2108 performs the same sensing mode as described above, but the first switching transistor Tsw1 of each pixel P is turned on only during the first period t1, and is used for sensing. The driving of each of the row driving unit 220 and the column driving unit 230 is controlled so that the bias voltage Vdata_sen is supplied only during the first period t1. Accordingly, when the sensing mode is re-performed, in the second period t2, as the gate-source voltage of the driving transistor Tdr is all increased due to the turn-off of the first switching transistor Tsw1, the capacitor Cst is A reference in which the gate-source voltage of the driving transistor Tdr is maintained by the voltage and a voltage corresponding to the current flowing through the driving transistor Tdr, that is, a voltage corresponding to the mobility value V_α of the driving transistor Tdr, is plotted. It is charged in line RL. And, when performing the sensing mode again, the sensing unit 236 of the column driver 230 senses the voltage Vsense of the reference line RL, and converts the sensed voltage Vsense to analog-digital. Accordingly, the mobility value V_Vth of the driving transistor Tdr is generated and provided to the timing controller 210. Accordingly, the timing controller 210 calculates the mobility value V_α of the driving transistor Tdr for each pixel provided from the sensing unit 236 as a mobility sensing value α_sen and stores it in the memory unit 300 do.

9 is a driving waveform diagram in a display mode in the organic light emitting display device according to the first example of the present invention.

A sensing mode of an organic light emitting diode display according to a first example of the present invention will be described with reference to FIGS. 5 to 7 and 9.

First, in a display mode, the timing controller 210 includes a threshold voltage sensing value Vth_sen and a mobility sensing value α_sen of the driving transistor Tdr for each pixel in the memory unit 300, and the threshold voltage prediction function. The coefficients (A, B, C, D) for the operation (Vth'_sat) of are extracted, and the extracted threshold voltage sensing value (Vth_sen) for each pixel, mobility sensing value (α_sen), and coefficients (A, A predicted threshold voltage value of the driving transistor Tdr for each pixel is calculated through the operation of Equation 1 using B, C, and D). In addition, the timing controller 210 is based on a difference between the predicted threshold voltage of the driving transistor Tdr for each pixel stored in the memory unit 300 and the initial threshold voltage predicted value of the driving transistor for each pixel. A characteristic compensation value for each pixel for compensating for a voltage change is calculated, and then input data of the pixel P is corrected according to the calculated characteristic compensation value for each pixel, thereby generating correction data DATA for each pixel. At the same time, the timing controller 120 generates first and second row control signals RCS1 and RCS2 for driving the pixel P in the addressing period DM_t1 and the light emission period DM_t2 to generate the aforementioned row ( row) is supplied to the driving unit 220 and simultaneously generates correction data DATA for each pixel and a data control signal DCS, and supplies them to the column driving unit 230.

The row driver 220 has a high voltage level during the addressing period DM_t1 in response to each of the first and second row control signals RCS1 and RCS2, and is low during the emission period DM_t2. First and second scan pulses SP1 and SP2 having a voltage level of voltage are respectively generated and supplied to the scan control line SL and the sensing control line SSL.

The data driver 232 of the column driver 230 converts the correction data DATA for each pixel into a data voltage Vdata in response to the data control signal DCS, and converts the correction data DATA for each pixel into a data voltage Vdata during the addressing period DM_t1. It is supplied to the data line DL. At the same time, the switching unit 234 of the column driver 230 supplies a reference voltage Vref to the reference line RL during the addressing period DM_t1 in response to a precharging switch signal.

In such a display mode, the operation of the pixel P of each of the addressing period DM_t1 and the emission period DM_t2 according to driving of the row driver 220 and the column driver 230 will be described. As follows.

First, in the addressing period DM_t1, the first switching transistor Tsw1 is turned on by the first scan pulse SP1 of a high voltage, and the data voltage Vdata supplied to the data line DL is first The node n1 is supplied to the gate electrode of the driving transistor Tdr, and the second switching transistor Tsw2 is turned on by the second scan pulse SP2 of a high voltage to be supplied to the reference line RL. The reference voltage Vref is supplied to the second node n2, that is, the source electrode of the driving transistor Tdr. Accordingly, the capacitor Cst connected to the first node n1 and the second node n2 is charged with the difference voltage Vdata-Vref between the data voltage Vdata and the reference voltage Vref.

Then, in the light emission period DM_t2, the first switching transistor Tsw1 is turned off by the first scan pulse SP1 of the low voltage, and the second scan pulse SP2 is turned off. As the switching transistor Tsw2 is turned off, the driving transistor Tdr is turned on by the voltage Vdata-Vref stored in the capacitor Cst. Accordingly, the turned-on driving transistor Tdr supplies a data current Ioled determined by a difference voltage Vdata-Vref between the data voltage Vdata and the reference voltage Vref to the light emitting device OLED. As a result, the light emitting element OLED emits light in proportion to the data current Ioled flowing from the driving power line PL to the second electrode (or the cathode electrode). That is, in the light emission period DM_t2, when the first and second switching transistors Tsw1 and Tsw2 are turned off, a current flows through the driving transistor Tdr, and the light emitting element OLED emits light in proportion to the current. As the voltage of the second node n2 increases, the voltage of the first node n1 increases as the voltage of the second node n2 increases by the capacitor Cst, and thus the voltage of the capacitor Cst increases. The gate-source voltage Vgs of the driving transistor Tdr is continuously maintained so that the light-emitting element OLED continues to emit light until the addressing period DM_t1 of the next frame.

10 is a graph for explaining luminance uniformity of a display panel for the present invention and Comparative Examples 1 and 2;

In FIG. 10, the graph of the present invention shows the luminance uniformity for each gray level to which both the short-axis sensing method and data compensation are applied, Comparative Example 1 shows the luminance uniformity for each gray level using only the short-axis sensing method, and Comparative Example 2 is Represents luminance uniformity for each gray level.

As can be seen from FIG. 10, the present invention can confirm that the luminance uniformity is higher than that of Comparative Example 1 of the single-axis sensing method, and it can be confirmed that the saturation sensing method has a form similar to the graph of Comparative Example 2.

As a result, in the organic light emitting diode display according to the first example of the present invention, the sensing time of the driving transistor for each pixel is shortened, and the threshold voltage of the driving transistor for each pixel according to the mobility deviation of the driving transistor for each pixel due to the shortening of the sensing time By compensating for the deviation, uniformity of luminance of the display panel 100 may be improved.

Hereinafter, a configuration of an organic light emitting display device including the panel driver according to the second example of the present invention described above will be described with reference to FIG. 11.

11 is a diagram illustrating a configuration of an organic light emitting diode display according to a second example of the present invention.

6, 7 and 11, the organic light emitting display device according to the second example of the present invention includes a display panel 100, a panel driver 200, and a memory unit 300, as described above. In addition, the panel driving unit 200 includes a timing control unit 210, a row driving unit 220, and a column driving unit 230. In the organic light-emitting display device according to the second example of the present invention having such a configuration, the remaining components except for the timing control unit 210 and the memory unit 300 are the organic light-emitting display device according to the first example of the present invention. It is the same, so it will be omitted in the following description.

First, the memory unit 300 includes a threshold voltage sensing value (Vth_sen) and a mobility sensing value (α _sen ) of a driving transistor for each pixel sensed by a previous sensing mode, and a reference data voltage for sensing set by a prior experiment. The mobility coefficient α _coe is stored.

In the sensing mode, the timing controller 210 calculates a mobility sensing value α _sen of a driving transistor for each pixel and a mobility coefficient α _coe for each sensing reference data voltage Vdata_ref in the memory unit 300. After extraction, the pixel data DATA for sensing for each pixel are generated through the calculation of Equation 2 using the extracted mobility sensing value α _sen and the mobility coefficient α _{coe as} shown in FIG. 4. As described above, the mobility deviations α_high and α_low of the driving transistor Tdr for each pixel generated at the shortened sensing time Tsen of the sensing mode due to the shortening of the sensing time are compensated.

Then, the timing control unit 210 provides the generated pixel-specific sensing pixel data DATA to the column driving unit 230 to be synchronized with the row driving unit 220 and the column driving unit. Each of the 230 is controlled in a sensing mode.

In the sensing mode, the column driver 230 generates a sensing data voltage Vdata'_sen for each pixel and supplies the sensing pixel data DATA for each pixel to the pixel P, and the reference Each of the threshold voltage sensing value Vth_sen and the mobility sensing value α _sen of the driving transistor for each pixel is sensed through the line RL and provided to the timing controller 210.

In the above-described display mode, the timing controller 210 drives each pixel that is sensed by the threshold voltage sensing value of the driving transistor for each pixel sensed at the short-range sensing time of the sensing mode and the first sensing mode and stored in the memory unit 300. Based on the deviation between the initial threshold voltage sensing values of the transistors, a pixel-specific characteristic compensation value is calculated for compensating for a change in the threshold voltage of the driving transistor for each pixel, and then input of the pixel P according to the calculated characteristic compensation value for each pixel. Each pixel P is driven by correcting data to generate correction data for each pixel.

The organic light emitting diode display according to the second example of the present invention performs a sensing mode according to the driving waveform of the sensing mode illustrated in FIG. 8 to sense the threshold voltage sensing value Vth_sen and mobility of the driving transistor for each pixel. Generate a value (α _sen ). In this case, the organic light emitting diode display according to the second example of the present invention is a bias voltage for operating the driving transistor of each pixel P in a source follow mode, which is generated according to the operation of Equation 2 The sensing data voltage Vdata'_sen for each pixel is used.

In addition, the OLED display according to the second example of the present invention drives each pixel P by performing a display mode according to a driving waveform of the display mode illustrated in FIG. 9. In this case, the organic light emitting diode display according to the second example of the present invention is based on a deviation between the threshold voltage sensing value Vth_sen of the driving transistor for each pixel stored in the memory unit 300 and the initial threshold voltage sensing value of the driving transistor for each pixel. After calculating a pixel-specific characteristic compensation value for compensating for a change in the threshold voltage of the driving transistor for each pixel, the input data of the corresponding pixel P is corrected according to the calculated characteristic compensation value for each pixel to obtain the pixel-specific correction data DATA. And drives each pixel P.

12 is a graph showing a current flowing through a driving transistor versus a data voltage in the present invention and a comparative example.

12(a) is a graph of a comparative example in which the short-circuit sensing method and the threshold voltage compensation are applied to measure the current flowing through the driving transistor for the data voltage. And a graph of the present invention in which a current flowing through a driving transistor with respect to a data voltage is measured by applying threshold voltage compensation.

As can be seen from (a) of FIG. 12, in the comparative example, it can be seen that grayscale inversion occurs in the low grayscale area (LGA). That is, in the comparative example, the deviation of the threshold voltage sensing value occurs according to the mobility deviation (α_high, α_low) of the driving transistor for each pixel occurring at the short-circuit sensing time, and the threshold voltage compensation based on the deviation of the threshold voltage sensing value. As a result, grayscale inversion occurs in the low grayscale area (LGA).

On the other hand, as can be seen from (a) of FIG. 12, in the present invention, it can be confirmed that grayscale inversion does not occur in the low grayscale area (LGA). That is, the present invention generates a data voltage for each pixel sensing to compensate for the mobility deviation (α_high, α_low) of the driving transistor for each pixel, which is generated at the time of the short axis sensing, based on the single axis sensing method and the mobility compensation gain value. Accordingly, since the threshold voltage is sensed and threshold voltage compensation is performed based on this, grayscale inversion does not occur in the low grayscale area (LGA).

As a result, in the organic light emitting diode display according to the second example of the present invention, the sensing time of the driving transistor for each pixel is shortened, and the threshold voltage of the driving transistor for each pixel according to the mobility deviation of the driving transistor for each pixel due to the shortening of the sensing time By compensating for the deviation, uniformity of luminance of the display panel 100 may be improved.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical matters of the present invention. It will be obvious to those who have the knowledge of. Therefore, the scope of the present invention is indicated by the claims to be described later, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

100: display panel 200: panel driver
210: timing control unit 220: row driving unit
230: column driver 232: data driver
234: switching unit 236: sensing unit
300: memory unit

Claims (11)

A display panel including a plurality of pixels including a driving transistor configured to emit light of an organic light emitting element by outputting a data current based on a data voltage;
A reference connected to a sensing node between the organic light-emitting device and the driving transistor while operating the display panel in a sensing mode or a display mode and operating the driving transistors of each pixel in a source follow mode in the sensing mode Through a line, the driving characteristic value of the driving transistor for each pixel consisting of the threshold voltage sensing value and the mobility sensing value of the driving transistor is sensed, and input data for each pixel is corrected based on the driving characteristic value of the driving transistor for each pixel in the display mode. A panel driver for driving each pixel; And
And a memory unit storing threshold voltage sensing values and mobility sensing values for the driving transistors for each pixel sensed by the sensing mode, and coefficients for mobility sensing values for the threshold voltage prediction function; and
In the sensing mode, the panel driver senses a driving characteristic value of the driving transistor at a short-circuit sensing time set before a voltage saturation period in which a sensing voltage according to a current flowing through the driving transistor is saturated, and
In the display mode, the panel driver extracts coefficients of a threshold voltage prediction function corresponding to a mobility sensing value of the driving transistor for each pixel from the memory unit, and extracts coefficients for each pixel and a threshold voltage of the driving transistor for each pixel. An organic light emitting diode display device configured to calculate a threshold voltage predicted value of the driving transistor for each pixel by calculating the threshold voltage predicting function using a sensing value. The method of claim 1,
In the display mode, the panel driver predicts a threshold voltage of the driving transistor for each pixel corresponding to the voltage saturation period, based on a sensing value of a threshold voltage and a mobility sensing value of the driving transistor for each pixel sensed at the short-axis sensing time. An organic light emitting diode display device configured to drive each pixel by calculating a value and correcting input data for each pixel based on the calculated threshold voltage predicted value of a driving transistor for each pixel. delete The method of claim 1,
The threshold voltage prediction function is based on a first threshold voltage sensing value of the driving transistor for each pixel sensed at the short-circuit sensing time and a second threshold voltage sensing value of the driving transistor for each pixel sensed in the voltage saturation period, and sensing the mobility. An organic light-emitting display device that is a linear function set based on a first function for each mobility sensing value calculated by coordinated with a second threshold voltage sensing value with respect to a first threshold voltage sensing value for each value and linearly interpolated. The method of claim 4,
The linear coefficient of the threshold voltage prediction function is composed of a second function calculated by linearly interpolating the linear coefficients of the first functions for each mobility sensing value, and
The zero-order coefficient of the threshold voltage prediction function is composed of a third function calculated by coordinating the zero-order coefficients of the first functions for each mobility sensing value with respect to a mobility sensing value and linear interpolation,
The coefficients of the threshold voltage prediction function stored in the memory unit are linear and zero-order coefficients of the second function, and linear and zero-order coefficients of the third function. The method of claim 5,
In the display mode, the panel driver,
The memory unit extracts a first-order coefficient and a zero-order coefficient of the second function corresponding to a mobility sensing value of the driving transistor for each pixel, and a first-order coefficient and a zero-order coefficient of the third function,
The second and third functions using the extracted linear and zero-order coefficients of the second function, the extracted linear and zero-order coefficients of the third function, and a mobility sensing value of the driving transistor for each pixel Calculate the first-order coefficient and the zero-order coefficient of the threshold voltage prediction function through each operation,
The threshold of the driving transistor for each pixel through the calculation of the threshold voltage prediction function using the calculated first and zero order coefficients of the calculated threshold voltage prediction function and a threshold voltage sensing value of the driving transistor for each pixel sensed at the short axis sensing time. An organic light emitting diode display that calculates a voltage prediction value. The method according to any one of claims 1, 2, 4 to 6,
In the display mode, the panel driver,
A characteristic compensation value for each pixel is calculated based on a deviation between the predicted threshold voltage value of the driving transistor for each pixel stored in the memory unit and the initial threshold voltage predicted value for the driving transistor for each pixel, and the calculated characteristic compensation value for each pixel An organic light-emitting display device that drives each pixel by correcting input data of a corresponding pixel. A display panel including a plurality of pixels including a driving transistor configured to emit light of an organic light emitting element by outputting a data current based on a data voltage; And
A reference connected to a sensing node between the organic light-emitting device and the driving transistor while operating the display panel in a sensing mode or a display mode and operating the driving transistors of each pixel in a source follow mode in the sensing mode Through a line, the driving characteristic value of the driving transistor for each pixel consisting of the threshold voltage sensing value and the mobility sensing value of the driving transistor is sensed, and input data for each pixel is corrected based on the driving characteristic value of the driving transistor for each pixel in the display mode. And a panel driver configured to drive each pixel,
In the sensing mode, the panel driver senses a driving characteristic value of the driving transistor at a short-circuit sensing time set before a voltage saturation period in which a sensing voltage according to a current flowing through the driving transistor is saturated, and
In the sensing mode, the panel driver generates a sensing data voltage for each pixel based on a mobility sensing value of the driving transistor for each pixel and a mobility coefficient set for each sensing reference data voltage, and generates the sensing data for each pixel. By operating the driving transistor of each pixel in a source follower mode using a voltage, the threshold voltage and the mobility of the driving transistor for each pixel are sensed to generate a threshold voltage sensing value and a mobility sensing value of the driving transistor for each pixel. Organic light emitting display device. The method of claim 8,
Further comprising a memory unit storing a threshold voltage sensing value and a mobility sensing value for the driving transistor for each pixel sensed by the sensing mode, and a mobility coefficient for each sensing reference data voltage,
In the sensing mode, the panel driver includes a mobility sensing value of a driving transistor for each pixel stored in the memory unit and a mobility coefficient of a driving transistor for each pixel based on a mobility coefficient for each voltage of a sensing reference data. An organic light-emitting display device that calculates a compensation gain value and generates a sensing data voltage for each pixel by using sensing reference pixel data and the mobility compensation gain value. The method of claim 9,
In the sensing mode, the panel driver,
An average mobility value is calculated based on a mobility sensing value of a driving transistor for each pixel stored in the memory unit,
A mobility compensation value is calculated using the average mobility value and a mobility sensing value of the driving transistor,
An organic light-emitting display device that calculates a mobility compensation gain value using the mobility compensation value and the mobility coefficient. The method according to any one of claims 9 to 10,
In the display mode, the panel driver,
A characteristic compensation value for each pixel is calculated based on a deviation between the threshold voltage sensing value of the driving transistor for each pixel stored in the memory unit and the initial threshold voltage sensing value for the driving transistor for each pixel, and according to the calculated characteristic compensation value for each pixel. An organic light-emitting display device that drives each pixel by correcting input data of a corresponding pixel.

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