KR20190070536A - Organic light emitting diode display device and method for driving the same - Google Patents

Abstract

The present invention relates to an OLED display device and a driving method thereof which can reduce time to sense threshold voltage (Vth) of a driving TFT (DT) and can avoid increases in a unit cost and an area by forming dummy sub-pixels inside an OLED pixel array and using a current of the dummy sub-pixels as reference voltage. In addition, the OLED display device comprises: a plurality of sub-pixels in which a plurality of scan lines and data lines are arranged to cross each other in a display area and are defined in a matrix shape; a plurality of reference voltage lines which are connected to each of the sub-pixels in a vertical direction of the plurality of sub-pixels; a plurality of dummy sub-pixels which are formed in a non-display area in order to correspond to each of the reference voltage lines and supply reference currents when sensing the threshold voltage of the driving TFT of the sub-pixels in the vertical direction; and a plurality of sensing units which compare the reference current with the threshold current value of the driving TFT through each reference voltage line and output the same.

Description

[0001] The present invention relates to an organic light emitting diode (OLED) display device and a method of driving the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OLED display device, and more particularly, to an OLED display device and a driving method thereof that can reduce a sensing time of a threshold voltage of a driving TFT.

2. Description of the Related Art Flat panel displays that display images using digital data are typically liquid crystal displays (LCDs) using liquid crystals and OLED display devices using organic light emitting diodes (OLEDs) .

Of these, OLED display devices are self-luminous devices that emit the organic light-emitting layer by recombination of electrons and holes, and have high luminance, low driving voltage, easy response time of several microseconds (μs), easy visualization, And it is expected to be a next generation display device because it can be made thinner.

Each of the plurality of pixels constituting the OLED display device includes an OLED element composed of an organic light emitting layer between the anode and the cathode, and a pixel circuit independently driving the OLED element. The pixel circuit includes a thin film transistor (TFT) for supplying a data voltage to a storage capacitor, a driving transistor for controlling a driving current according to a driving voltage charged to the storage capacitor and supplying the OLED element to the OLED, The device generates light proportional to the driving current.

In the OLED display of such a structure, in particular, the driving transistor plays an important role in image quality by controlling the amount of current flowing in the OLED element to display the gradation of the image.

However, even within one display panel, there is a deviation in the electrical characteristics of the driving transistors between the pixels, that is, the threshold voltage (Vth) and the electron mobility, for reasons of process variation and aging change, The current flowing is not constant and a problem arises that the desired gradation can not be realized.

To solve this problem, an OLED display device uses a method of sensing the characteristics of a driving transistor of each pixel and compensating data to be supplied to each pixel by using a sensing value.

FIG. 1 is a circuit configuration diagram of a sub-pixel for sensing a threshold voltage (Vth) change amount of a conventional driving transistor.

Each sub-pixel of a conventional OLED display device includes an organic light emitting diode (OLED) and a pixel circuit for driving the organic light emitting diode, as shown in FIG.

The pixel circuit includes first and second switching TFTs T1 and T2, a storage capacitor Cst, and a driving TFT DT.

The first switching TFT Tl charges the storage capacitor Cst with a data voltage in response to a scan pulse Scan. The driving TFT DT controls the amount of current supplied to the OLED according to the data voltage charged in the storage capacitor Cst to control the amount of light emitted from the OLED. The second switching TFT (T2) senses the threshold voltage and the mobility of the driving TFT (DT) in response to a sensing signal.

The organic light emitting diode OLED may include a first electrode (e.g., an anode electrode or a cathode electrode), an organic light emitting layer, and a second electrode (e.g., a cathode electrode or an anode electrode).

 The storage capacitor Cst is electrically connected between a gate electrode of the driving TFT DT and a source electrode so that a data voltage corresponding to a video signal voltage or a voltage corresponding thereto is applied for one frame time I can keep it.

A method of sensing the threshold voltage Vth of the driving TFT DT is to operate the driving TFT DT in a source follower manner and then receive the source voltage of the driving TFT DT as a sensing voltage, And detects a threshold voltage change amount of the driving TFT DT based on the sensing voltage. The amount of change in the threshold voltage of the driving transistor is determined according to the magnitude of the sensing voltage, thereby obtaining an offset value for data compensation.

More specifically, it is as follows.

The first switching TFT T1 is turned on and the data voltage Data is applied to the gate of the storage capacitor Cst and the driving TFT DT through the data line. .

When the reference voltage is supplied to the reference voltage line Ref and a sensing signal Sense of high level is applied to the second switching TFT T2, the second switching TFT T2 is turned on. Accordingly, the driving TFT DT is driven in the saturation region according to the difference voltage between the data voltage Vdata stored in the storage capacitor Cst and the reference voltage Vref, and a sink current flows. If the reference voltage is not supplied to the reference voltage line Ref, the voltage of the reference voltage line Ref rises to a voltage corresponding to the saturation region. Then, when the threshold voltage Vth of the driving TFT DT is reached, the reference voltage line Ref becomes saturated. At the time of saturation, the sensing signal Sense is applied at a low level, and the voltage in the saturation state is sampled to sense the threshold voltage.

2 is an explanatory diagram for explaining a reference voltage supply method in a conventional OLED display device.

In the conventional OLED display device having such a structure, as shown in FIG. 2, since a reference voltage is commonly supplied to all the reference voltage lines Ref by one source meter, a plurality of The threshold voltage Vth of the driving TFT DT must be sensed for each sub-pixel by sequentially applying a reference voltage to the sub-pixels.

Therefore, it is impossible to simultaneously sense the threshold voltage (Vth) of the driving TFT (DT) of a plurality of sub-pixels connected to one scan line, real time sensing time increases, real time sensing may not be possible, The number of source electrodes corresponding to the number of the reference voltage lines (Ref) is required to simultaneously sense the threshold voltage (Vth) of the driving TFT (DT) of the plurality of sub-pixels connected to the line, The area for installing the source meter has been increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a dummy sub-pixel within an OLED pixel array and using the current of the dummy sub-pixel as a reference voltage so that a threshold voltage (Vth) And an OLED display device which does not increase the unit cost and the area, and a driving method thereof.

According to an aspect of the present invention, there is provided an OLED display device including a plurality of sub-pixels arranged in a display region such that a plurality of scan lines and data lines cross each other and are defined in a matrix form, - a plurality of reference voltage lines respectively connected to the sub-pixels in each vertical direction of the pixel, and a plurality of reference voltage lines formed in the non-display region corresponding to each reference voltage line, A plurality of dummy sub pixels for supplying a reference current at the time of sensing and a plurality of sensing units for comparing the threshold current value of the driving TFT with the reference current through each reference voltage line and outputting the comparison result.

In the OLED display according to the present invention, a predetermined number of reference voltage lines among the plurality of reference voltage lines are grouped into one group, and the threshold current values of the reference current and the driving TFT are And a plurality of sensing units for outputting a comparison result.

According to another aspect of the present invention, there is provided a method of driving an OLED display, including: driving each dummy sub-pixel to output a reference current to each reference voltage line; A step of sequentially driving each sub-pixel formed in the display region to output a threshold current of the driving TFT from each sub-pixel to each of the reference voltage lines; And comparing the stored voltage of each reference voltage line with the threshold voltage of the converted driving TFT to sense the threshold voltage of the driving TFT of each sub-pixel.

A method of grouping a predetermined number of reference voltage lines among the plurality of reference voltage lines into one group and sensing the threshold voltage of the driving TFT through the reference voltage lines of each group includes the steps of: Driving a plurality of sub-pixels in a display region, driving the plurality of sub-pixels to output a reference current to each of the plurality of reference voltage lines, converting the reference current to a voltage, Comparing the stored voltage of each group of reference voltage lines with a threshold voltage of the converted driving TFT; comparing the threshold voltage of each group of reference voltage lines with a threshold voltage of the converted driving TFT; And sensing the threshold voltage of the driving TFT of each sub-pixel.

The OLED display according to the present invention having the above characteristics and the driving method thereof have the following effects.

That is, in the OLED display according to the present invention, the reference voltage lines are arranged in the vertical direction sub-pixels, the dummy sub-pixels are arranged in the respective vertical directions, and the threshold voltages of the driving TFTs of the sub- (Current) in the dummy sub-pixel, it is possible to simultaneously sense the threshold voltages of the driving TFTs of the plurality of horizontal sub-pixels driven by one scan line.

In addition, the real time sensing time can be reduced without increasing the area and the unit cost.

That is, in the case of the 9.7 QXGA model (1536 * 2048), it is possible to reduce by about 128 (1536 / (3 * 4) times than the conventional one horizontal line sensing time.

FIG. 1 is a circuit diagram of one sub-pixel for sensing a variation in threshold voltage (Vth) of a conventional driving transistor
2 is an explanatory diagram for explaining a reference voltage supplying method in a conventional OLED display device.
3 is a block diagram schematically showing an OLED display device according to the present invention.
4 is a schematic configuration diagram of an OLED display panel and a sensing control unit of an OLED display according to a first embodiment of the present invention
FIG. 5 is a diagram showing a configuration of a dummy sub pixel and a display sub pixel connected to a reference voltage line of an OLED display according to the present invention
6 is a specific configuration diagram of a sensing unit of a sensing control unit in an OLED display according to the present invention.
7 is a schematic configuration diagram of an OLED display panel and a sensing control unit of an OLED display according to a second embodiment of the present invention
8 is a circuit diagram for explaining a method of calibrating the output current I _DMY of each dummy sub-pixel of the OLED display according to the first embodiment of the present invention
9 is a circuit diagram for explaining a method of calibrating the output current I _DMY of each dummy sub-pixel of the OLED display according to the second embodiment of the present invention.
10 is a driving waveform diagram of an OLED display according to the present invention

An OLED display device and a driving method thereof according to the present invention having the above features will be described in detail with reference to the accompanying drawings.

3 is a block diagram schematically showing an OLED display device according to the present invention.

3, the OLED display according to the present invention includes an OLED display panel 100 in which a plurality of pixels PX are defined, various control and driving units 110 connected to the OLED display panel 100, To 140).

The OLED display panel 100 includes a plurality of scan lines SCL and a plurality of data lines DL arranged so as to intersect each other on an organic substrate or a plastic substrate and the scan lines SCL and the data lines DL cross Subpixels PX are defined at each of the sub-pixels PX for indicating gradations corresponding to red, green and blue, respectively. Each sub-pixel PX is connected to a reference voltage line Ref for sensing a threshold voltage Vth and an electron mobility μ. Although not shown, the OLED display panel 100 is supplied with power Various lines for supplying the voltage EVDD and the ground voltage ELVSS are further formed.

The scan lines SCL are connected to a scan driver 120 formed at an outer portion of the display panel 100 to output a scan signal SCAN and the data lines DL output a data voltage Vdata And is connected to the data driver 130.

The reference voltage line Ref formed in the OLED display panel 100 is connected to a sensing control unit 140 that senses the electrical characteristics of the driving TFT through a sink current flowing in the pixel PX.

The timing controller 110 receives a scan control signal GCS, a data control signal DCS, and a sensing drive control signal SCS by receiving external image data, a clock signal, a vertical and horizontal synchronization signal, And the like.

The scan driver 120 sequentially applies a scan signal SCAN to each scan line SCL in response to a scan control signal SCS from the timing controller 110. [ The scan driver 120 may be implemented as a conventional shift register.

The data driver 130 receives a video signal RGB of a digital waveform applied from the timing controller 110 and generates a data voltage Vdata of an analog voltage having a gray scale value that can be processed by the pixel PX, And the data voltage Vdata is supplied to each of the dummy sub-pixels DMY (1) to DMY (5) through the data line DL corresponding to the input data control signal DCS, ((1, 1) to (4, 5), ...) of the region.

The sensing control unit 140 controls the driving of the sub-pixels of the display region through the reference voltage line Ref immediately after the power on / off of the OLED display device or at a time point designated by the user according to the control of the timing controller 110. [ The threshold voltage Vth and the mobility characteristic of the driving TFT DT are sensed and the sensed result is reflected in the data voltage Vdata to compensate the characteristic deviation of the driving TFT DT.

3, the sensing control unit 140 is configured separately from the data driving unit 130. However, the sensing control unit 140 may be integrated into the data driving unit 130 as an integrated IC.

4 is a detailed configuration diagram of an OLED display panel and a sensing control unit of an OLED display according to a first embodiment of the present invention.

The display panel 100 is divided into a display area and a non-display area.

4, a plurality of scan lines S1, S2, S3, and S4 and data lines (not shown in FIG. 4, see FIG. 3) are arranged to intersect with each other in the display region, (1, 1) for displaying gradations corresponding to red, green, and blue respectively at points where the scan lines S1, S2, S3, S4, ... and the data lines DL intersect, ~ (4,5), ...) are defined in matrix form. In order to sense the threshold voltage Vth and the electron mobility μ, each sub-pixel (1, 1) to (4, 5) One reference voltage line Ref is arranged. That is, the sub-pixels in each vertical direction are connected to one reference voltage line Ref.

4, a plurality of dummy sub-pixels DMY (1) to DMY (5), ... corresponding to the reference voltage line (Ref line) are formed in the non-display region , The plurality of dummy sub pixels DMY (1) to DMY (5), ... are driven by a dummy scan line DS and a data line (not shown in FIG. 4, see DL in FIG. 3) And supplies a reference voltage (current) to each reference voltage line (Ref line).

4, the scan driver 120 includes a dummy scan driver DMY (GIP) for driving dummy sub-pixels DMY (1) to DMY (5) And a display scan driver (A / A (GIP)) for driving the sub-pixels ((1,1) to (4,5), ... formed in the display area.

The dummy sub-pixels DMY (1) to DMY (5), ... and the sub-pixels (1,1) to (4,5) And includes the organic light emitting diode OLED, the capacitor Cst, the first and second switching TFTs T1 and T2, and the driving TFT DT as shown in FIG.

4, the sensing control section 140 controls the driving TFT DT of each sub pixel in the display region through each of the reference voltage lines Ref1, Ref2, Ref3, Ref4, Ref5, A sensing unit 10 for sensing a threshold voltage Vth and a mobility characteristic of the sensing TFT 10, a sampling and holding unit 20 for sampling a value sensed by the sensing unit 10, And an analog / digital converter 30 for converting the threshold voltage (Vth) and the mobility characteristic into a digital signal.

That is, the sensing unit 10, the sampling and holding unit 20, and the A / D converter 30 are provided for each of the reference voltage lines Ref1, Ref2, Ref3, Ref4, Ref5,.

In the OLED display according to the present invention configured as shown in FIG. 4, one dummy sub pixel and a vertical display sub pixel are connected to one reference voltage line.

5 is a configuration diagram of a first dummy sub-pixel DMY (1) and a first display sub-pixel (1,1) connected to a reference voltage line Ref1 of an OLED display according to the present invention. That is, one dummy sub-pixel and a plurality of display sub-pixels in the vertical direction are connected to one reference voltage line, but only one dummy sub-pixel and one sub-pixel are shown in FIG.

As described above, the circuit configurations of the first dummy sub-pixel DMY (1) and the first display sub-pixel (1,1) are the same.

The first switching TFT Tl charges the data voltage DATA to the storage capacitor Cst in response to the scan pulse Scan and a second switching TFT Tl that charges the organic light emitting diode Cst according to the data voltage charged in the storage capacitor Cst. A driving TFT DT for controlling the amount of current supplied to the OLED and a threshold voltage and a mobility characteristic value of the driving TFT DT in response to a sensing signal to the reference voltage line Ref A storage capacitor Cst which is connected between a gate electrode of the driving TFT DT and a source electrode and holds a data voltage corresponding to a video signal voltage or a voltage corresponding thereto for one frame time, Respectively.

A first switch SW1 for switching between the second switching TFT T2 and the reference voltage line Ref of the dummy sub-pixel DMY (1) constructed as described above, (Ref) connected between the reference voltage line to which the display sub-pixel (1) is connected and the display sub-pixel (1,1) formed in the display area is connected to the first switch SW2 do.

The reference voltage line Ref is connected to the sensing unit 10 of the sensing control unit 140.

Although only the first display sub-pixel (1,1) connected to the reference voltage line Ref1 is shown in FIG. 5, a plurality of display sub-pixels (2,1), (3) (1, 1), (4, 1), ...) are connected to each other, (1, 1) has the same configuration as the first display sub-pixel ((1,1)).

Also, the remaining reference voltage lines Ref2, Ref3, Ref4, Ref5, ... are provided with the first and second switches SW1 and SW2 as shown in Fig. 5, and have the same configuration.

A specific configuration of the sensing unit 10 of the sensing control unit 140 will now be described.

6 is a specific configuration diagram of a sensing unit of a sensing control unit in an OLED display according to the present invention.

6, the sensing unit 10 of the sensing control unit in the OLED display according to the present invention includes a voltage setting logic unit 11 for converting the current of the reference voltage line Ref into a voltage, A third switch SW3 for switching the voltage output from the voltage setting logic unit 11 and a capacitor for receiving and storing a voltage corresponding to a current output from the dummy sub- (C1) and a voltage corresponding to a current corresponding to a current outputted from the dummy sub pixel stored in the capacitor (C1) and a voltage corresponding to a current outputted from the display sub-pixel and outputting the output according to an output enable signal And a comparator (12) for comparing the output voltage of the comparator

4, a plurality of sub-pixels (1, 1, 2, 1), (3, 1), (4, 1), ... are connected to one reference voltage line Ref1 but the present invention is not limited thereto and four dummy sub-pixels DMY (1), DMY (2), DMY (3), and DMY (4) 1, 2, 1, 3, 1, 4, 1, 2, 2, 2, 2, 3, 2, 3, 3, 3, 4, 3, 4), (2,4), (3,4), (4,4), ... may be connected to one reference voltage line.

4, a plurality of sub-pixels (1,1, 2, 1, 3, 1, 4, 5, 6) arranged in a direction perpendicular to one dummy sub- 1), ... are connected to one reference voltage line Ref1, the four reference voltage lines are grouped into one group, and the threshold voltage of the driving TFT is sensed by one sensing unit of each group .

FIG. 7 is a specific configuration diagram of an OLED display panel and a sensing control unit of an OLED display according to a second embodiment of the present invention.

That is, the first to fourth dummy sub pixels (DMY (1), DMY (2), DMY (3), and DMY (4) 1), (2,1), (3,1), (4,1), ... ((1,2), (2,2), (3,2), (4,2). ((1,3), (2,3), (3,3), (4,3), (1,4), (2,4) 4, 4, ..., ...) are connected to one reference voltage line.

The four fifth to eighth dummy sub-pixels DMY (5), DMY (6), DMY (7) and DMY (8) ), (2,5), (3,5), (4,5), (1,6), (2,6), (3,6), (4,6) (1,7), (2,7), (3,7), (4,7), (1,8), (2,8), (3,8), , 8), ...) are connected to another reference voltage line.

In this way, one reference voltage line is arranged in four dummy sub-pixels and four vertically arranged sub-pixels, and each of the reference voltage lines includes the sensing unit 10, the sampling and holding unit 20, And an analog-to-digital converter 30 are provided.

In the OLED display according to the second embodiment of the present invention shown in FIG. 7, only one dummy sub-pixel among the four dummy sub-pixels connected to one reference voltage line may output the reference current I _DMY .

Therefore, in the OLED display according to the second embodiment of the present invention shown in FIG. 7, only one dummy sub-pixel of the four dummy sub-pixels outputs the reference current I _DMY , so that four dummy sub- It is possible to generate the reference current I _DMY . Therefore, the OLED display according to the second embodiment of the present invention can further reduce the deterioration of the dummy sub-pixels as compared with the OLED display according to the first embodiment of the present invention.

In FIG. 7, the circuit configuration of each sub-pixel and the configuration of the sensing unit are as described in FIGS. 5 and 6. FIG.

Also, the plurality of dummy sub pixels (DMY (1), DMY (2), DMY (3), DMY (4), DMY , The deviation of the electric characteristic of the driving TFT between each dummy sub-pixel, that is, the deviation of the threshold voltage (Vth) and the mobility of the electron mobility can be generated. Therefore, the deviation (I _DMY ) May occur.

When the current (I _DMY ) generated in each of the dummy sub-pixels deviates as described above, the electrical characteristics of the driving TFT of the display sub-pixel can not be accurately sensed. Accordingly, it is necessary to perform initial calibration and real-time correction so that the current I _DMY generated in each dummy sub-pixel generates and outputs a constant value.

FIG. 8 is a circuit diagram illustrating a method of calibrating an output current I _DMY of each dummy sub-pixel of the OLED display according to the first embodiment of the present invention.

First, the initial correction will be described as follows.

In the specific configuration of the OLED display panel and the sensing control unit of the OLED display according to the first embodiment of the present invention as illustrated in FIG. 4, as shown in FIG. 8, the current I _SM output from the source- And the third switch SW3 is turned on to store the voltage corresponding to the current I _SM outputted from the source meter to the capacitor C1.

When the third switch SW3 and the second switch SW2 of FIG. 5 are turned off and the first switch SW1 of FIG. 5 is turned on, the dummy sub-pixel DMY ) To generate a current I _DMY from the dummy sub-pixels DMY (1) and outputs the current I _DMY to the reference voltage line Ref, and the current I _DMY ) To a voltage and applies the voltage to the comparator (12).

The comparator 12 compares the voltage corresponding to the current I _SM outputted from the source mounter stored in the capacitor C1 with the voltage corresponding to the current outputted from the dummy sub pixel and outputs the result.

The output current I _DMY of the dummy sub-pixel DMY (1) is corrected by compensating the data value applied to the dummy sub-pixel DMY (1) by using the output value of the comparator 12, do.

The above method is performed in all the dummy sub-pixels to calibrate the output current I _DMY of each dummy sub-pixel.

The following real-time compensation is described as follows.

Since the real-time correction can not correct all the dummy sub-pixels, it is corrected using the data value compensated at the initial correction and the data compensation value of one dummy sub-pixel.

For example, in the initial correction, the data compensation value of the first dummy sub-pixel DMY (1) is "A", the data compensation value of the second dummy sub-pixel DMY (2) The data compensation value of the third dummy sub-pixel DMY (3) is "C", the data compensation value of the fourth dummy sub-pixel DMY (4) is "D" 5)) is "E ". It is assumed that deterioration has occurred in each dummy sub-pixel after a certain period of time since the initial correction.

After a predetermined time has elapsed, the degree of deterioration is measured for the first dummy sub-pixel DMY (1) in the same manner as described in the initial correction method, and the data value corresponding thereto is compensated. At this time, the data of the first dummy sub-pixel DMY (1) Assume the compensation value is "a". Then, it is predicted that the other dummy western pixels will also have deteriorated after a lapse of a certain time. Therefore, if the data compensation value of the second dummy sub-pixel DMY (2) is "b" and the data compensation value of the third dummy sub-pixel DMY (3) is "b" , The data compensation value of the fourth dummy sub-pixel DMY (4) is "d", and the data compensation value of the fifth dummy sub-pixel DMY (5) is "e".

The data compensation values (b, c, d, e) of the second to fifth dummy sub-pixels thus predicted are calculated by the following equation (1).

[Equation 1]

b = a + A-B)

c = a + (A-C)

d = a + A-D)

e = a + (A-E)

In this way, the real-time correction compensates the data by measuring the actual output current value of only one dummy sub-pixel, and the remaining dummy sub-pixels calculate the initial data compensation value and the data compensation value of the one dummy sub-pixel , And real-time correction proceeds.

On the other hand, in the OLED display according to the second embodiment of the present invention illustrated in FIG. 7, each dummy sub-pixel must be corrected at the initial and real time.

9 is a circuit diagram illustrating a method of calibrating an output current I _DMY of each dummy sub-pixel of an OLED display according to a second embodiment of the present invention.

First, the initial correction will be described as follows.

In the specific configuration of the OLED display panel and the sensing control unit of the OLED display according to the second embodiment of the present invention as described with reference to FIG. 7, the display sub-pixels start with the assumption that the data value is compensated.

9, the first switch SW1 is turned off, and the second switch SW2 and the third switch SW3 are turned on to turn on one of the display sub-pixels (1 , 1) is generated by the conversion to a current output (I _{PXL (1,1))} into a voltage by the voltage setting logic (11), and a third said output current to said capacitor (C1) via a switch (SW3) (I _{PXL (1,1)} ).

When the third switch SW3 and the second switch SW2 of FIG. 5 are turned off and the first switch SW1 of FIG. 5 is turned on, the dummy sub-pixel DMY ) To generate a current I _DMY from the dummy sub-pixels DMY (1) and outputs the current I _DMY to the reference voltage line Ref, and the current I _DMY ) To a voltage and applies the voltage to the comparator (12).

The comparator 12 compares the voltage corresponding to the current I _{PXL (1,1)} output from the display sub-pixel (1,1) stored in the capacitor C1 and the voltage corresponding to the current I _PXL )), And outputs a result of the comparison.

The output current I _DMY of the dummy sub-pixel DMY (1) is corrected by compensating the data value applied to the dummy sub-pixel DMY (1) by using the output value of the comparator 12, do.

The above method is performed in all the dummy sub-pixels to calibrate the output current I _DMY of each dummy sub-pixel.

The following real-time compensation is described as follows.

As described above, in the OLED display according to the second embodiment of the present invention shown in FIG. 7, only one dummy sub-pixel among the four dummy sub-pixels connected to one reference voltage line outputs the reference current I _DMY .

Therefore, in the OLED display according to the second embodiment of the present invention shown in FIG. 7, the remaining three dummy sub-pixels not used at the time of real-time correction are used.

A method of driving the OLED display according to the present invention will now be described.

10 is a driving waveform diagram of an OLED display according to the present invention.

The method of driving an OLED display according to the present invention is a method of initially correcting each dummy sub-pixel DMY (1) to DMY (5), ..., as described with reference to FIGS. 8 and 9, Go ahead. The method of initial correction of each dummy sub-pixel (DMY (1) to DMY (5), ...) has been described above and will be omitted.

First, a driving method for displaying an image in the OLED display according to the present invention will be described.

The scan / sense signal DS (Scan / Sense (DMY)) is not activated in the dummy sub-pixels DMY (1) to DMY (5), ... in the dummy scan driver DMY GIP Level signal output) The dummy sub pixels DMY (1) to DMY (5) are not driven.

The second switch SW2 of FIG. 5 is turned on and the sub-pixels ((1,1) to (4,5) formed in the display region in the display scan driver A / Sense (PXL) is sequentially applied to each of the scan lines S1, S2, S3, S4 and S5 of the scan / sense signal Scan / Sense (PXL) A data signal is supplied to each data line to display an image.

Next, a method of sensing the threshold voltage (Vth) of the driving TFT DT of each of the sub-pixels ((1,1) to (4,5)) in the OLED display device according to the present invention will be described as follows .

The method of sensing the threshold voltage Vth of the driving TFT DT of each sub-pixel ((1,1) to (4,5), ...) according to the present invention includes the steps of 1) of sensing the threshold voltage Vth of the driving TFT DT and outputting the threshold voltage Vth of the sensed driving TFT DT.

First, an OLED display according to a first embodiment of the present invention will be described with reference to FIG.

The step (1) of storing the reference voltage is performed by turning on the first switch SW1 of FIG. 5 and the third switch SW3 of FIG. 6 in a state in which the second switch SW2 of FIG. The scan / sense signal DS (Scan / Sense (DMY)) is applied to the dummy sub-pixels DMY (1) to DMY (5), ... in the dummy scan driver DMY GIP, And drives the dummy sub pixels DMY (1) to DMY (5), ..., by supplying a data voltage (high level signal output).

The dummy sub-pixels DMY (1) to DMY (5), ...) are driven to output currents I _DMY (5), ... from the dummy sub pixels _DMY And outputs it to the reference voltage line Ref. The voltage setting logic unit 11 of FIG. 6 converts the current I _DMY into a voltage and stores it in the capacitor C1. Thus, the capacitor C1 stores the reference voltage.

Next, the step (2) of sensing the threshold voltage Vth of the driving TFT DT is performed in a state where the first switch SW1 of FIG. 5 and the third switch SW3 of FIG. 6 are turned off (1, 1) to (4, 5) formed in the display region in the display scan driver (A / A (GIP)), turning on the second switch Sense signal (Scan / Sense (PXL)) sequentially to each of the scan lines (S1, S2, S3, S4, S5, (1, 1) to (4, 5) formed in the display region by supplying a data signal to each data line in synchronization with the sense (PXL).

(1, 1) to (4, 5)) formed in the display region and driving the sub-pixels ( And outputs the current I _PXL to the reference voltage line Ref. The voltage setting logic unit 11 of FIG. 6 converts the current I _DMY to a voltage and outputs the current I _DMX to the comparator 12 of FIG. .

The comparator 12 compares the reference voltage stored in the capacitor C1 with the voltage corresponding to the current output from the display sub-pixel.

The step (3) of outputting the threshold voltage (Vth) of the sensed driving TFT (DT) is performed such that the comparator (12) outputs the comparison result value in synchronization with the output enable signal (EM) (20) samples the value output from the comparator (12) and converts the sampled value into a digital signal in the A / D converter (30).

The threshold voltage Vth of the driving TFT DT of each of the sub-pixels (1, 1) to (4, 5)) is sensed through the above steps ( Lt; / RTI >

Next, an OLED display device according to a second embodiment of the present invention described with reference to FIG. 7 will be described as follows.

As described above, in the OLED display device according to the second embodiment of the present invention, since four dummy sub-pixels are connected to one reference voltage line, only one of the four dummy sub-pixels is driven.

The step of storing the reference voltage includes the step of supplying a scan / sense signal DS (Scan) to the dummy sub pixels DMY (1) to DMY (5), ... in the dummy scan driver DMY GIP / Sense (DMY)) is activated (the 'high' level signal is output), and only one of the four dummy sub-pixels is driven by applying a data voltage to one dummy sub-pixel among the four dummy sub-pixels.

For example, in FIG. 7, when the reference current I _DMY is outputted only in the first dummy sub-pixel DMY (1), the fifth dummy sub-pixel DMY (5) The data voltages are supplied only to the pixels DMY 1 and DMD 5 and the second to fourth dummy sub pixels DMY 2 and DMY 3, 4) and the sixth to eighth dummy sub-pixels DMY 6, DMY 7, DMY 8 and so on.

5 and the third switch SW3 shown in Fig. 6 are turned on in a state where the second switch SW2 of Fig. 5 is turned off, and the first switch SW1 of Fig. And the fifth dummy sub pixels DMY (1), DMY (5),. The first and fifth dummy sub-pixels DMY (1), DMY (5), ...) are driven to drive the first and fifth dummy sub-pixels DMY (1) And outputs the current I _DMY to the reference voltage line Ref and converts the current I _DMY into a voltage at the voltage setting logic unit 11 of FIG. C1. Thus, the capacitor C1 stores the reference voltage.

The step (2) of sensing the threshold voltage (Vth) of the driving TFT (DT) is performed in the state in which the first switch SW1 of FIG. 5 and the third switch SW3 of FIG. 6 are turned off, The second switch SW2 of FIG. 5 is turned on, and the sub-pixels ((1,1) to (4,5), (1,1) to (4,5) formed in the display region in the display scan driver A / Sense (PXL) is sequentially applied to each of the scan lines (S1, S2, S3, S4, S5, (1, 1) to (4, 5) formed in the display region by supplying data signals to the data lines in synchronization with the data lines (PXL, PXL).

(1, 1) to (4, 5)) formed in the display region and driving the sub-pixels ( And outputs the current I _PXL to the reference voltage line Ref. The voltage setting logic unit 11 of FIG. 6 converts the current I _DMY to a voltage and outputs the current I _DMX to the comparator 12 of FIG. .

The comparator 12 compares the reference voltage stored in the capacitor C1 with the voltage corresponding to the current output from the display sub-pixel.

The step (3) of outputting the threshold voltage (Vth) of the sensed driving TFT (DT) is performed such that the comparator (12) outputs the comparison result value in synchronization with the output enable signal (EM) (20) samples the value output from the comparator (12) and converts the sampled value into a digital signal in the A / D converter (30).

The threshold voltage Vth of the driving TFT DT of each of the sub-pixels (1, 1) to (4, 5)) is sensed through the above steps ( Lt; / RTI >

As described above, in the OLED display according to the present invention, the reference voltage lines are arranged in the vertical sub-pixels, the dummy sub-pixels are arranged in the respective vertical directions, and the threshold voltages of the driving TFTs of the sub- It is possible to sense the threshold voltages of the driving TFTs of the plurality of horizontal sub-pixels driven by one scan line at the same time.

In addition, the real time sensing time can be reduced without increasing the area and the unit cost.

That is, in the case of the 9.7 QXGA model (1536 * 2048), it is possible to reduce by about 128 (1536 / (3 * 4) times than the conventional one horizontal line sensing time.

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 general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

10: sensing unit 11: voltage sensing logic unit
12: comparator 20: sampling and holding unit
30: Analog-to-digital converter 100: Display panel
110: timing controller 120: scan driver
130: Data driver 140:

Claims (22)

A plurality of sub-pixels arranged in a display area such that a plurality of scan lines and data lines cross each other and are defined in a matrix form;
A plurality of reference voltage lines respectively connected to sub-pixels in each vertical direction of the plurality of sub-pixels;
A plurality of dummy sub-pixels formed in a non-display region corresponding to each reference voltage line to supply a reference current when sensing a threshold voltage of a driving TFT of the sub-pixels in the vertical direction; And
And a sensing unit for comparing the threshold current value of the driving TFT with the reference current through each reference voltage line. The method according to claim 1,
A dummy scan driver for supplying a scan signal and a sense signal to the plurality of dummy sub pixels,
And a display scan driver sequentially supplying a scan signal and a sense signal to a scan line of sub-pixels formed in the display area. The method according to claim 1,
Each dummy sub-pixel and each sub-
An OLED element; a first switching TFT (T1) for supplying a data voltage to the storage capacitor in response to the scan signal;
A driving TFT for controlling an amount of light emitted from the OLED by controlling an amount of current supplied to the OLED according to a data voltage charged in the storage capacitor,
And a second switching TFT responsive to the sensing signal for outputting a current corresponding to a threshold voltage of the driving TFT to the reference voltage line. The method of claim 3,
And a first switch for switching between the reference voltage line and the second switching TFT. The method according to claim 1,
And a second switch for switching between a reference voltage line to which the dummy sub pixel of the non-display area is connected and a reference voltage line to which the sub pixel of the display area is connected. The method according to claim 1,
The sensing unit includes:
A voltage setting logic unit for converting the reference current input through each reference voltage line and the threshold current of the driving TFT into a voltage and outputting the voltage,
A capacitor for receiving and storing a voltage corresponding to a reference current output from the dummy sub-pixel through the voltage setting logic;
A third switch for switching between the voltage setting logic unit and the capacitor,
And a comparator for comparing a voltage stored in the capacitor with a voltage corresponding to a threshold current of the driving TFT and outputting the comparison result. A plurality of sub-pixels arranged in a display area such that a plurality of scan lines and data lines cross each other and are defined in a matrix form;
A plurality of reference voltage lines respectively connected to sub-pixels in each vertical direction of the plurality of sub-pixels;
A plurality of dummy sub-pixels formed in a non-display region corresponding to each reference voltage line to supply a reference current when sensing a threshold voltage of a driving TFT of the sub-pixels in the vertical direction; And
And a sensing unit for dividing a predetermined number of reference voltage lines among the plurality of reference voltage lines into one group and comparing the reference current with a threshold current value of the driving TFT through each group of reference voltage lines, Device. 8. The method of claim 7,
Each group including four dummy sub-pixels and four reference voltage lines connected to four vertical sub-pixels. 8. The method of claim 7,
A dummy scan driver for supplying a scan signal and a sense signal to the plurality of dummy sub pixels,
And a display scan driver sequentially supplying a scan signal and a sense signal to a scan line of sub-pixels formed in the display area. 8. The method of claim 7,
Each dummy sub-pixel and each sub-
An OLED element; a first switching TFT (T1) for supplying a data voltage to the storage capacitor in response to the scan signal;
A driving TFT for controlling an amount of light emitted from the OLED by controlling an amount of current supplied to the OLED according to a data voltage charged in the storage capacitor,
And a second switching TFT for outputting a current corresponding to a threshold voltage of the driving TFT to the reference voltage line in response to a sensing signal,
And a first switch for switching between the reference voltage line and the second switching TFT. 8. The method of claim 7,
And a second switch for switching between a reference voltage line to which the dummy sub pixel of the non-display area is connected and a reference voltage line to which the sub pixel of the display area is connected. 8. The method of claim 7,
The sensing unit includes:
A voltage setting logic unit for converting the reference current input through each reference voltage line and the threshold current of the driving TFT into a voltage and outputting the voltage,
A capacitor for receiving and storing a voltage corresponding to a reference current output from the dummy sub-pixel through the voltage setting logic;
A third switch for switching between the voltage setting logic unit and the capacitor,
And a comparator for comparing a voltage stored in the capacitor with a voltage corresponding to a threshold current of the driving TFT and outputting the comparison result. A plurality of reference voltage lines respectively connected to the sub-pixels in each vertical direction of the plurality of sub-pixels, and a plurality of reference voltage lines, And a plurality of dummy sub-pixels formed in a non-display region corresponding to the sub-pixels to supply a reference current when sensing a threshold voltage of the driving TFT of the sub-pixels in the vertical direction,
Driving each dummy sub-pixel to output a reference current to each reference voltage line;
Converting the reference current into a voltage and storing the voltage;
Sequentially driving each sub-pixel formed in the display region to output a threshold current of the driving TFT from each sub-pixel to each of the reference voltage lines;
Converting a threshold current of the driving TFT into a voltage; And
And comparing the stored voltage of each reference voltage line with a threshold voltage of the converted driving TFT to sense a threshold voltage of the driving TFT of each sub-pixel. 14. The method of claim 13,
Further comprising the step of initially correcting the output of each dummy sub-pixel before driving each dummy sub-pixel to output a reference current to each reference voltage line. 15. The method of claim 14,
Wherein the initial correction step comprises:
Converting the current (I _SM ) output from the source meter into a voltage and storing the converted voltage;
Driving each dummy sub pixel to generate a reference current in each reference voltage line and converting it into a voltage,
And comparing the stored voltage with a reference voltage of each of the converted dummy sub-pixels to compensate a data value supplied to each dummy sub-pixel. 14. The method of claim 13,
After comparing the stored voltage of each reference voltage line with the threshold voltage of the converted driving TFT and sensing the threshold voltage of the driving TFT of each sub-pixel,
Further comprising the step of real-time correcting an output of each of the dummy sub-pixels before sensing a threshold voltage of a driving TFT of each of the following sub-pixels. 17. The method of claim 16,
Wherein the real-
Calculating a compensated data value of each dummy sub-pixel and a data compensation value of one dummy sub-pixel at the time of initial correction and compensating each dummy sub-pixel in real time. A plurality of reference voltage lines respectively connected to the sub-pixels in each vertical direction of the plurality of sub-pixels, and a plurality of reference voltage lines, And a plurality of dummy sub-pixels formed in a non-display region corresponding to the plurality of sub-pixels to supply a reference current when sensing a threshold voltage of the driving TFT of the sub-pixels in the vertical direction, A method of driving an OLED display device in which a plurality of reference voltage lines are divided into a group,
Driving one of the dummy sub-pixels of each group to output a reference current to each reference voltage line;
Converting the reference current into a voltage and storing the voltage;
Sequentially driving each sub-pixel formed in the display region to output a threshold current of the driving TFT from each sub-pixel to each of the reference voltage lines;
Converting a threshold current of the driving TFT into a voltage; And
And comparing the stored voltage of the reference voltage line of each group with the threshold voltage of the converted driving TFT to sense a threshold voltage of the driving TFT of each sub-pixel. 19. The method of claim 18,
Further comprising the step of initially correcting the output of each dummy sub-pixel before driving each dummy sub-pixel to output a reference current to each reference voltage line. 20. The method of claim 19,
Wherein the initial correction step comprises:
Converting a current generated and output from one of the sub-pixels into a voltage and storing the converted voltage;
Driving each dummy sub-pixel to generate a current from each dummy sub-pixel and converting it into a voltage,
And comparing the stored voltage with a reference voltage of each of the converted dummy sub-pixels to compensate a data value supplied to each dummy sub-pixel. 19. The method of claim 18,
The step of comparing the stored voltage of each reference voltage line with the threshold voltage of the converted driving TFT to sense the threshold voltage of the driving TFT of each sub-pixel, then sensing the threshold voltage of the driving TFT of each of the subsequent sub- And correcting an output of each of the dummy sub-pixels in real time in real time. 22. The method of claim 21,
Wherein the real-
Wherein the reference current is compensated in real time for each dummy sub-pixel among dummy sub-pixels of each group.

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